Natural History Museum Library 000163823 PHILOSOPHICAL TRANSACTIONS OP THE ROYAL society OR LONDON. FOR THE YEAR MDCCCLXV. VOL. 155. LONDON: PRINTED BY TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET. MDCCCLXV. ADVERTISEMENT. The Committee appointed by the Royal Society to direct the publication of the Philosophical Transactions , take this opportunity to acquaint the Public, that it fully appears, as well from the Council-books and Journals of the Society, as from repeated declarations which have been made in several former Transactions , that the printing of them was always, from time to time, the single act of the respective Secretaries till the Forty-seventh Volume; the Society, as a Body, never interesting themselves any further in their publication, than by occasionally recommending the revival of them to some of their Secretaries, when, from the particular circumstances of their affairs, the Transactions had happened for any length of time to be intermitted. And this seems principally to have been done with a view to satisfy the Public, that their usual meetings were then continued, for the improvement of knowledge, and benefit of mankind, the great ends of their first institution by the Eoyal Charters, and which they have ever since steadily pursued. But the Society being of late years greatly enlarged, and their communications more numerous, it was thought advisable that a Committee of their members should be appointed, to reconsider the papers read before them, and select out of them such as they should judge most proper for publication in the future Transactions; which was accordingly done upon the 26th of March 1752. And the grounds of their choice are, and will continue to be, the importance and singularity of the subjects, or the advantageous manner of treating them ; without pretending to answer for the certainty of the facts, or propriety of the reasonings, contained in the several papers so published, which must still rest on the credit or judgement of their respective authors. It is likewise necessary on this occasion to remark, that it is an established rule of the Society, to which they will always adhere, never to give their opinion, as a Body, upon any subject, either of Nature or Art, that comes before them. And therefore the a 2 [ iv ] thanks, which are frequently proposed from the Chair, to be given to the authors of such papers as are read at their accustomed meetings, or to the persons through whose hands they received them, are to be considered in no other light than as a matter of civility, in return for the respect shown to the Society by those communications. The like also is to be said with regard to the several projects, inventions, and curiosities of various kinds, which are often exhibited to the Society ; the authors whereof, or those who exhibit them, frequently take the liberty to report and even to certify in the public newspapers, that they have met with the highest applause and approbation. And therefore it is hoped that no regard will hereafter be paid to such reports and public notices ; which in some instances have been too lightly credited, to the dishonour of the Society. The Meteorological Journal hitherto kept by the Assistant Secretary at the Apart- ments of the Eoyal Society, by order of the President and Council, and published in the Philosophical Transactions, has been discontinued. The Government, on the recom- mendation of the President and Council, has established at the Eoyal -Observatory at Greenwich, under the superintendence of the Astronomer Eoyal, a Magnetical and Meteorological Observatory, where observations are made on an extended scale, which are regularly published. These, which correspond with the grand scheme of observations now carrying out in different parts of the globe, supersede the necessity of a continuance of the observations made at the Apartments of the Eoyal Society, which could not be rendered so perfect as was desirable, on account of the imperfections of the locality and the multiplied duties of the observer. A List of Public Institutions and Individuals, entitled to receive a Copy of the Philosophical Transactions of each year, on making application for the same directly or through their respective agents, within five years of the date of publication. Observatories. Armagh. Cape of Good Hope. Dublin. Edinburgh. Greenwich. Kew. Liverpool. Madras. Oxford (Radcliffe). Institutions. Barbadoes Library and Museum. Calcutta Asiatic Society. Geological Museum. Cambridge Philosophical Society. Cape Town South African Library. Dublin Royal Dublin Society. Royal Irish Academy. Edinburgh Royal Society. London Admiralty Library. Chemical Society. College of Surgeons. Entomological Society. Geological Society. Geological Survey of Great Britain. Horticultural Society. Institute of British Architects. Institution of Civil Engineers. Linnean Society. London Institution. Royal Asiatic Society. Royal Astronomical Society. Royal College of Physicians. Royal Geographical Society. Royal Institution of Great Britain. Royal Medical and Chirurgical Society. Royal Society of Literature. Society of Antiquaries. Society of Arts. The Queen’s Libraiy. The Treasury Library. United Service Museum. Zoological Society. Halt a Public Library. Manchester Literary and Philosophical Society. Melbourne University Library. Montreal McGill College. Oxford Ashmolean Society. Radcliffe Library. Swansea Royal Institution. Sydney University Library. Woolwich Royal Artillery Library. Belgium. Brussels Academie Royale de Medecine. Royal Academy of Sciences. DenmarTc. Copenhagen Royal Society of Sciences. France. Montpellier Academy of Sciences. Eaculte de Medecine. Paris Academy of Sciences. Depot de la Marine. Ecole des Mines. Geographical Society. Geological Society. Jardin des Plantes. Societe d’Encouragement pour l’lndustrie Rationale. Toulouse Academy of Sciences. Germany. Altona Observatory. Berlin Royal Academy of Sciences. Society of Experimental Philosophy. Briinn Haturforschender Yerein. Dresden Caesarean Acad, of naturalists. Erankfort natural History Society. Giessen University. Gottingen University. Hamburg naturwissenschaftlicher-Yerein. Konigsberg Koniglichen Physikalisch Okonomischen Gesellschaft. Leipzig Royal Saxon Society of Sciences. Mannheim ...... Observatory. Munich Royal Academy of Sciences. Prague Bohemian Society of Sciences. Vienna Imperial Academy of Sciences. Geologische Reiehsanstalt. Wurzburg Physico-Medical Society. A List of Public Institutions and Individuals, entitled to receive a Copy of the Philosophical Transactions of each year, on making application for the same directly or through their respective agents, within five years of the date of publication ( continued ). Hungary. Pesth Hungarian Academy of Sciences. Italy. Bologna Academy of Sciences. Catanea Accademia Gioenia di Scienze Naturali. Florence Royal Observatory. Milan Institute of Sciences, Letters, and Arts. Modena Italian Society of Sciences. Naples Institute of Sciences. Palermo Academy of Sciences and Letters. Rome Academy de’ Nuovi Lincei. Collegio Romano. Turin Royal Academy of Sciences. Venice Institute of Sciences, Letters, and Arts. Java. Batavia .......... Batavian Society of Sciences. Netherlands. Amsterdam ...... Royal Institute. Haarlem ........ Dutch Society of Sciences. Rotterdam ...... Batavian Society of Experimental Philosophy. Portugal. Lisbon Royal Academy of Sciences. Russia . Kazan Imperial University. Moscow Imperial Society of Naturalists. Public Museum. Pulkowa Observatory. St. Petersburg .... Imperial Academy of Sciences. Spain. Cadiz Observatory. Madrid Royal Academy of Sciences. Sweden and Norway. . Christiania Royal University. Drontheim Royal Society of Sciences. Gottenburg Kongl. Vetenskaps oeh Vitterhets Samhalle. Stockholm Royal Academy of Sciences. Switzerland. Bern Allg. Schweizerischen Gesellschaft. Geneva Societe de Phys. et d’Hist. Naturelle. Transylvania. Klausenburg Society of the Transylvanian Museum. United States. Albany New York State Library. Boston American Academy of Sciences. Newhaven (Conn.) .The Editors of the American Journal. Cambridge Harvard University. Philadelphia Academy of Natural Sciences. American Philosophical Society. Washington ...... Smithsonian Institution. Observatory. Th Q fifty Foreign Members of the Royal Society. A List of Public Institutions and Individuals, entitled to receive a Copy of the Astro- nomical Observations (including Magnetism and Meteorology) made at the Royal Observatory at Greenwich, on making application for the same directly or through their respective agents, within two years of the date of publication. Observatories. Institutions. Altona. Aberdeen Armagh. Berlin Berlin. Bologna Breslau. Boston Brussels. Brunswick, U.S. . . Cadiz. Cambridge Cambridge. Cambridge, U.S. . . Cape of Good Hope. Dublin Coimbra. Edinburgh Copenhagen. Royal Society. Dorpat. Glasgow Dublin. Gottingen Edinburgh. Leyden Helsingfors. London Konigsberg. Royal Institution. Madras. Royal Society. Mannheim. The Queen’s Library. Marseille. Oxford Milan. Paris Munich. Board of Longitude. Oxford. Depot de la Marine. Palermo. Pesth Paris. Philadelphia Seeberg. St. Andrews Tubingen. St. Petersburg .... Turin. Stockholm Vienna. Upsal Wilna. Waterville, Maine (U.S.) . . College. Individuals. Lowndes’ Professor of Astronomy Cambridge. Plumian Professor of Astronomy Cambridge. President of the Eoyal Society London. South, Sir James . The Earl of Rosse . A List of Observatories, Institutions and Individuals, entitled to receive a Copy of the Magnetical and Meteorological Observations made at the Koyal Observatory, Greenwich. Observatories. Bombay Lieut. P. W. Mitcheson. Cambridge, United States . . Prof. J. Lovering. Christiania C. Hansteen. Gotha P. A. Hansen. Heidelberg M. Tiedemann. Kew B. Stewart. Kremsmiinster P. A. Beslhuber. Leipzig Professor Mobius. Lisbon Senhor da Silveira. Marburg Professor Gerling. Prague K. Jelinek. Stockholm Professor H. Selander. St. Petersburg (Twelve copies for distri- bution to the Bussian Mag. and Met. Obs.) Toronto Professor Kingston. Upsal Washington Professor Svanberg. Institutions. Bombay Geographical Society. Bonn University. Boston, U.S The Public Library (late Bowditch). Cambridge Philosophical Society. Cherkow University. Falmouth Boyal Cornwall Poly- technic Society. London House of Lords, Library. House of Commons, Li- brary. King’s College. Boyal Society. University College, Li- brary. Paris Meteorological Society. St. Bernard Convent. . "Washington Smithsonian Institution. Woolwich Office of Mag. and Met. Publication. Individuals. Bache, Dr. A. D Washington. Buys Ballot, Dr Utrecht. Dove, Prof. H. W Berlin. Erman, Dr. Adolph Berlin. Fox, B. W., Esq Falmouth. Harris, Sir W. Snow Plymouth. Hoskins, Dr. S. E Guernsey. Kaemtz, Prof. L. F Dorpat. Kreil, Prof. K Vienna. Lloyd, Bev. Dr Dublin. Loomis, Prof. E. Yale College, New- haven (Conn.). Phillips, Prof. John Oxford. Quetelet, A Brussels. Sabine, Major-General, B.A. . . London. Senhor da Souza Coimbra. Vernon, G. V., Esq Manchester. Wartmann, Prof. Elie Geneva. Younghusband, Col., B.A Woolwich. Adjudication of the Medals of the Royal Society for the year 1865 by the President and Council. The Copley Medal to Mons. Michel Chasles, For. Memb. R.S., for his Historical and Original researches in Pure Geometry. A Royal Medal to Joseph Prestwich, Esq., F.R.S., for his numerous and valuable Contributions to Geological Science, and more especially for his Papers published in the Philosophical Transactions, on the general question of the Excavation of River- valleys, and on the Superficial Deposits in France and England in which the Works of Man are associated with the remains of Extinct Animals. A Royal Medal to Archibald Smith, Esq., F.R.S., for his Papers in the Philosophical Transactions, and elsewhere, on the Magnetism of Ships. Professor H. E. Roscoe’s Paper, entitled “ On a Method of Meteorological Regis- tration of the Chemical Action of Total Daylight,” was appointed as the Bakerian Lecture. The Croonian Lecture was delivered by Professor Lionel Smith Beale, F.R.S. : it was entitled “ On the Ultimate Nerve-fibres distributed to Muscle and some other tissues, with Observations upon the Structure and probable Mode of Action of a Nervous Mechanism.” CONTENTS OF VOL. 155. I. On the Spectra of Ignited Gases and Vapours , with especial regard to the different Spectra of the same elementary gaseous substance. By Dr. J. Plucker, of Bonn , For. Mernb. B.S. , and Dr. J. W. Hittorf, of Munster page 1 II. On the Osteology of the genus Glyptodon. By Thomas H. Huxley, F.B.S. . . 31 III. Investigations of the Specific Heat of Solid Bodies. By Hermann Kopp. Com- municated by T. Graham, Esq., F.B.S. 71 IV. On the Composition of Sea-water in the different parts of the Ocean. By Georg Forchhammer, Professor at the University , and Director of the Polytechnic Insti- tution at Copenhagen. Communicated by the President 203 V. On the Magnetic Character of the Armour-plated Ships of the Boyal Navy, and on the Effect on the Compass of particular arrangements of Iron in a Ship. By Frederick: John Evans, Esq., Staff Commander B.N., F.B.S., Superintendent of the Compass Department of Her Majesty's Navy; and Archibald Smith, Esq., M.A., F.B.S., late Fellow of Trinity College, Cambridge, Corresponding Member of the Scientific Committee of the Imperial Bussian Navy 263 VI. On some Foraminifera from the North Atlantic and Arctic Oceans, including Davis Straits and Baffin's Bay. By W. Kitchen Parker, F.Z.S., and Professor T. Rupert Jones, F.G.S. Communicated by Professor Huxley, F.B.S. . . 325 VII. New Observations upon the Minute Anatomy of the Papillae of the Frog's Tongue. By Lionel S. Beale, M.B., F.B.S., Fellow of the Boyal College of Physicians, Professor of Physiology and of General and Morbid Anatomy in King's College, London ; Physician to King's College Hospital, &c 443 VIII. A Dynamical Theory of the Electromagnetic Field. By J. Clerk Maxwell, F.B.S 459 [ Vi ] IX. On the Embryogeny of Antedon rosaceus, Linck (Comatula rosacea of Lamarck). By Professor Wyville Thomson, LL.D., F.B.S. E., M.B.I.A., F.G.S., &c. Com- municated by Thomas Henry Huxley, F.B.S page 513 X. On the Sextactic Points of a Plane Curve. By A. Cayley, F.B.S 545 XI. A Description of some Fossil Plants , showing Structure , found in the Lower Coal- seams of Lancashire and Yorkshire. By E. W. Binney, F.B.S. . . . . 579 XII. The Bakerian Lecture. — On a Method of Meteorological Registration of the Chemical Action of Total Daylight. By Henry Enfield Roscoe, B.A., F.B.S., Professor of Chemistry in Owens College , Manchester 605 XIII. On the Commissures of the Cerebral Hemispheres of the Marsupialia and Mono- tremata as compared with those of the Placental Mammals. By William Henry Flower, F.B.S., F.B.C.S. , Conservator of the Museum of the Royal College of Surgeons of England 633 XIV. On the Sextactic Points of a Plane Curve. By William Spottiswoode, M.A., F.B.S., &c 653 XV. On the Marsupial Pouches, Mammary Glands, and Mammary Foetus of the Echidna Hystrix. By Professor Owen, F.B.S., &c 671 XVI. On the Influence of Physical and Chemical Agents upon Blood ; with special refer- ence to the mutual action of the Blood and the Respiratory Gases. By George Harley, M.D., Fellow of the Royal College of Physicians, Professor of Medical Jurisprudence in University College, London. Communicated by Professor Sharpey, M.D., Sec. B.S. 687 XVII. On a New Geometry of Space. By J. Plucker, of Bonn, For.Memb. B.S. 725 Index 793 Presents Appendix. [ i ] LIST OF ILLUSTRATIONS. Plates I. to III. — Drs. J. Plucker and J. W. Hittorf on the Spectra of Ignited Gases and Vapours. Plates IV. to IX. — Professor Huxley on the Osteology of the genus Glyptodon. Plates X. & XI. — Staff-Commander Evans and Mr. A. Smith on the Magnetic Cha- racter of the Armour-plated Ships of the Royal Navy. Plates XII. to XIX. — Mr. W. K. Parker and Professor T. R. Jones on some Forami- nifera from the North Atlantic and Arctic Oceans. Plate XX. — Professor Kopp on the Specific Heat of Solid Bodies. Plates XXI. and XXII. — Professor Beale’s New Observations upon the Minute Anatomy of the Papillae of the Frog’s Tongue. Plates XXIII. to XXVII. — Professor W. Thomson on the Embryogeny of Antedon rosaceus , Linck ( Comatula rosacea of Lamarck). Plates XXVIII. & XXIX. — Professor Roscoe on a Method of Meteorological Regis- tration of the Chemical Action of Total Daylight. Plates XXX. to XXXV. — Mr. E. W. Binney on some Lower-coal-seam Fossil Plants. Plates XXXVI. to XXXVIII. — Mr. W. H. Flower on the Cerebral Commissures of the Marsupialia and Monotremata. Plates XXXIX. to XLI. — Professor Owen on the Marsupial Pouches, Mammary Glands, and Mammary Foetus of the Echidna Eystrix. PHILOSOPHICAL TRANSACTIONS. I. On the Spectra of Ignited Gases and Vapours, with especial regard to the different Spectra of the same elementary gaseous substance. By Dr. J. Plucker, of Bonn, For. Memb. B.S., and Dr. J. W. Hittorf, of Munster. Received February 23, — Read March 3, 1864. 1. In order to obtain the spectra of all the elementary bodies, you may make use either of flame or the electric current. For this purpose flame is preferable on account of its easy management, and therefore was immediately introduced into the laboratory of the chemist. But its use is rather limited, the metals of alkalies being nearly the only sub- stances which, if introduced into flame, give spectra exhibiting well-defined bright lines. In the case of the greater number of elementary substances the temperature of flame, even if alimented by oxygen instead of air, is too low. Either these substances are not reduced into vapour by means of flame, or, if reduced, the vapour does not reach the temperature necessary to render it luminous in such a degree that by prismatic analysis we obtain its characteristic rays. The electric current, the heating-power of which may be indefinitely increased by increasing its intensity, is alone fitted to produce the pecu- liar spectra of all elementary bodies. 2. In applying the electric current we may proceed in two ways. In one mode of proceeding the substance to be examined by its spectrum is at the same time, by means of the current, transformed into vapour and rendered luminous. In the other mode the substance is either in the gaseous state, or, if not, has been converted into it by means of a lamp, and the electric current ignites the substance in passing through. 3. The first way of proceeding is the least perfect, but we are obliged to recur to it in the case of all such elementary bodies as neither by themselves nor combined with other substances can be vaporized without altering the least-fusible glass. If the sub- stance to be examined be a metal, the extremities of the conducting- wires are made of it and placed at a short distance from one another. When the strong spark of a large Leyden jar, charged by Ruhmkorff’s powerful induction-coil, is sent through the space between the two extremities of the conducting-wires, minute particles of the metal, mdccclxv. b 2 DES. J. PLUCKEE AND J. W. HITTOEF ON THE starting off from them, are volatilized: even in the gaseous state they conduct the electric current from point to point, and exhibit, while heated by it, the characteristic spectral lines of the metal. In all experiments made in this way, either air or another permanent gas occupied the space between the two extremities of the wires. The con- sequence of this is, the interposed gas partly conducting the electric current on its way through it, two spectra are obtained at the same time — the spectrum of the metal and the spectrum of the interposed gaseous medium. This inconvenience is the greater, as in most cases the number of bright lines constituting gas-spectra is a considerable one ; it is least in the case of hydrogen, the spectrum of which, if appearing under these con- ditions, becomes nearly a continuous one (59). If the substance submitted to experi- ment be not a metal or charcoal, the extremities of the metallic wires are to be covered with it. Then we get with the spectrum of the non-conducting substance at the same time the spectrum of the metal covered by it. 4. The spectra are obtained the most beautifully and are the most suitable for exami- nation in their minute details, if the substance be in the gaseous state before the electric discharge is sent through it. The spectral tubes for enclosing gas, first proposed and employed by one of us, were in most cases, with some modifications, adopted for our more recent researches. Our tubes, as represented by the diagram (fig. 1), gene- ^ rally consist of a capillary middle part 30-40 millims. long, and T5-2 millims. in diameter, forming a narrow channel, by which two larger spheres, with platinum electrodes traversing the -glass, communicate with one another. The small tube starting from one of the spheres serves to establish the com- munication with the exhauster, to which it is either attached by means of a cement (sealing-wax for instance), or soldered by the blowpipe. The ex- hauster, made solely of glass, without any metal, is connected with an addi- tional system of glass tubes and glass cocks, by means of which the spectral tube is most easily filled with the gas to be examined. If the gas be a per- manent one, the apparatus by which it is developed, and its accessory parts, by which it is purified and dried, may, as well as the spectral tube, simulta- neously and separately be evacuated. The gas arrives directly from the appa- ratus into the tube, which, ad libitum , may be alternately filled and ex- hausted again. Finally, the tension of the gas is regulated and measured by means of a manometer in connexion with the exhauster. 5. In order to compare with one another the spectra corresponding to different densities of the gas, or even to a mixture of different gases, the tube may be examined by the spectroscope while attached to the exhauster. But generally the spectral tube was blown off and hermetically sealed at the extremity of the narrow tube starting from one of the spheres. This tube equally serves to attach the spectral tube before the slit of the spectroscope. 6. If the substance submitted to examination were at the ordinary temperature in the liquid or solid condition, the tube destined to receive it was made of a glass diffi- SPECTRA OF IGNITED GASES AND VAPOURS. 3 cultly fusible, and bent as shown by the diagram (fig. 2). After having introduced into it a small quantity of the substance, the last traces of air were expelled from the tube, which was finally blown off. Put before the slit of the spectroscope, the enclosed substance was, by means of a lamp, reduced into vapour and, if necessary, kept in the gaseous state (fig. 3), and the density of the vapour regulated. The glass of our spectral tubes of this description is fused with such difficulty, that these highly evacuated tubes, when becoming red-hot by the lamp, are not altered by the pressure of the surrounding air. Fig. 2. Fig. 3. 7. Before giving a general account of the results we have obtained, it seems necessary to enter into some preliminary discussions regarding the admirable working of Geissler’s exhauster, and the phenomena shown by our tubes when highly evacuated by it. The essential part of Geissler’s exhauster is a large glass ball, containing ten to twenty kilogrammes of mercury, which in its upper part communicates, by means of a doubly perforated stopcock of glass, either with the free air, or with the spectral tube to be evacuated. From the lower part of the ball, which is invariably fixed, descends a longer tube of glass communicating at its lower extremity with a moveable similar tube, the free end of which enters into a large open bottle. When this bottle with the moveable tube is lifted up, the mercury within the apparatus entirely fills the ball, if commu- nicating with the air. This communication having been interrupted, a Torricellian vacuum is formed when the bottle descends. By establishing the communication with the spectral tube, the gas within it will be dilated. After the ascent and descent of mer- cury has thus been alternately produced often enough, no perceptible trace of air will remain within the spectral tube. 8. A tube evacuated in this way does not permit the induction current of Ruhmkorff’s smaller apparatus (which in air gives a spark of about 15 millims.) to pass through. The current of his large apparatus forces a passage ; but the spectrum we obtain in this case is very faint ; it shows no traces of the bands of nitrogen, but solely the lines of hydrogen and the large fields of vaporized carbon (51). The hydrogen-lines take their origin from hygroscopic water covering the interior surface of the spectral tube, the carbon-bands probably from the minute traces of fatty matter hitherto employed in b 2 4 DES. J. PLUCKEE AND J. W. HITTOEF ON THE greasing the stopcocks. (The oxygen simultaneously obtained by decomposition is not indicated.) The hydrogen-lines given by spectral tubes made of common glass are more brilliant than those of tubes made of less fusible glass, the hygroscopic state of the glass not being the same in both cases. Though within the interior of the exhauster the air is in contact with the surface of concentrated English sulphuric acid, or, what is preferable, with anhydrous phosphoric acid, we never succeeded in expelling the last traces of hygroscopic water, not even by strongly heating the spectral tube during evacuation. If, in the usual way, a Leyden jar be intercalated into the current of Ruhmkorff’s large induction coil, we must conclude, from the powerful charge of the jar, as proved by flashes of light, that within the spectral tube the tension of electricity, before it effects its passage, is very high. In this case the electric light is more bright, and of a fine colour like that of blue steel. When analyzed by the prism, it shows the spectral lines of hydrogen and oxygen, mixed with other spectral lines, among which those of sodium and silicium are the brightest. At the same time the interior surface of the capillary part of the tube tarnishes. Hence we conclude that the decomposed glass partly conducts the current. By means of our tubes, therefore, the theoretical conclusions of Dr. Faraday, that electricity being merely a peculiar condition of ponderable matter cannot exist without it, and cannot move without being carried by it, are confirmed and supported in a striking way*. 9. As soon as the tube encloses perceptible traces of air, the spectral lines resulting from the ingredients of the glass entirely disappear. Though the temperature of the gas be raised by the passing current to an immense height, nevertheless, on account of its great tenuity and the short duration of the discharge, the gas is not able to heat the surface of the glass sufficiently to volatilize it. In this case also no spectral lines owing to particles starting from the platinum electrodes appear in the capillary part of the tube. Those lines are to be seen only near the electrodes, namely, in the aureola surrounding the negative pole. 10. The temperature of the particles of air seized by the weakest electric spark by far surpasses the temperature of the hottest obtainable flame. For no flame whatever shows the spectral lines of air, which are constantly seen in the spark. In order to raise the temperature of the discharge of Ruhmkorff’s induction coil, you may either increase the power of the inducing current, or diminish the duration of the induced one. The last plan may be found preferable in most cases. The heat excited in a given conductor by a current sent through it increases in the ratio of the square of intensity, but decreases in the ratio of the duration of the current. Admitting, therefore, that the conductibility is not altered by elevation of temperature, and that the quantity of induced electricity remains the same, we conclude that the heating-power of the induced current is in the inverse ratio of its duration. But the resistance opposed by gases to the passage of * Mr. Gassiot has already obtained vacua so nearly perfect as to present an obstacle to electric conduction. See Philosophical Transactions for 1859, p. 148. SPECTRA OE IGNITED GASES AND VAPOURS. 5 electricity depends essentially upon their temperature. At the ordinary temperature it is rather too great to be measured, but, according to hitherto unknown laws, it rapidly decreases when the temperature rises beyond that of red heat. The law above men- tioned is therefore not strictly applicable in the case of gaseous conduction. 11. Electricity can only be discharged through a given stratum of air, from one point to another, after a certain electric tension takes place in these points. This tension depends upon the chemical constitution of the gas, and, the gas being the same, it is nearly in the ratio of its density and the distance of the two points. The quantity of electricity required to produce that degree of tension which must precede the electric discharge through our spectral tubes, enclosing gas of a given density, may be inde- finitely increased by interposing a Leyden jar. The less the distance between the coat- ings of the jar, and the larger their surface, the greater quantities of electricity will be accumulated on them, ready for discharge at the moment when the electric tension of the electrodes entering our tube reaches that intensity which alone allows the discharge to take place. Thus the Leyden jar is the most proper and most easy means for short- ening the duration of the discharge, and consequently increasing the temperature of the gas. In several cases, especially if a vapour like that of mercury be examined, which isolates less, it will be found more convenient, instead of replacing the Leyden jar by a larger one, to increase the charge of the same jar by intercalating into the circuit a spark micrometer, by means of which you may add to the resistance within the spectral tube the resistance of any stratum of air. 12. The leading idea by which one of us was guided when he first (1857) directed his attention to spectral analysis, was to concentrate the light in Geissler’s tubes by con- fining the electric current within a capillary channel *. The construction of our tubes immediately follows from it. Accordingly we gave, for different purposes, a different diameter to their capillary part. The length of this part is of very little influence if the tubes are very highly exhausted ; we had to shorten our recent tubes, intended to enclose gases and vapours of a greater density, rendered luminous by a powerful induc- tion coil. 13. We employed in our researches the large spectral apparatus constructed by M. Steiniieil. The refracting angle of one of the four flint prisms belonging to the apparatus is 60°, the angle of the three others 45°. Generally we made use of only two prisms (of 60° and 45°), and of a magnifying power of only 18. It is well known that the slit of the apparatus, if illuminated by sodium-light (by the flame of alcohol containing common salt), is seen double. According to the width of the slit and the dispersive power of the prisms, the two well-defined images, having both * Plucker : “ Spectra der elektrischen Licbtstromungen,” 30 Marz 1858, Poggendorff’s ‘ Annalen,’ vol. civ.; “ Ueber die Spectra der verschiedenen Gase, wenn durch dieselben bei starker Verdiinnung die elektriscbe Ent- ladung bindurchgebt,” 25 Aug. 1858, Ibid. vol. cv.; “ Ueber die Constitution der elektriscben Spectra von ver- scbiedenen Gasen und Dampfen,” 5 Mai 1859, Ibid. vol. cvii. 6 DRS. J. PLUCKER AND J. W. HITTORF ON THE the breadth of the slit as observed without the interposed prisms, are either superposed, or touch one another, or are separated by a black space. In making use of the two prisms, we generally regulated the aperture of the slit so that the two small sodium- bands appeared separated by a black space having nearly the breadth of these bands. In this case the angle at which the aperture of the slit is seen is equal to half the angu- lar distance of the two middle lines of the bands, and therefore equal to half the angu- lar distance of the two sodium-bands themselves after being reduced by narrowing the slit to mathematical lines. If the images touch each other, the aperture of the slit and the two sodium-lines are seen at the same angle. 14. The first fact which we discovered in operating with our tubes, guided by the above explained principles, was the following one : — There is a certain number of elementary substances , which , when differently heated , fur- nish two kinds of spectra of quite a different character , not having any line or any band in common. The fact is important, as well with regard to theoretical conceptions as to practical applications — the more so as the passage from one kind of spectra to the other is by no means a continuous one, but takes place abruptly. By regulating the temperature you may repeat the two spectra in any succession ad libitum. We will now treat more explicitly the case of Nitrogen , which first unfolded to us its different spectra. These spectra, obtained in the easiest and most striking way, have been examined by us in every point of view. The other cases of double spectra may hereafter be spoken of in a more summary manner. 15. We examined nitrogen prepared in different ways, even in the state of greatest purity ; but we found that, in order to get pure spectra of it, it was not necessary to free the gas from all traces of air *. Therefore we may select the following prepara- tion, imperfect as it is, in order to give an instance of constructing nitrogen-tubes. Three absorbing apparatus were connected with one another and, by means of a stop- cock, with the exhauster, the first two being filled with a solution of pyrogallic acid in hydrate of potash, and the third with concentrated sulphuric acid. After having evacuated the interior of the exhauster and the spectral tube connected with it, by care- fully turning the stopcock air was very slowly admitted, leaving its oxygen and carbonic acid to the first two, and its aqueous vapour to the third absorbing apparatus. Thus by and by the exhauster, with the tube, was filled with nitrogen, the manometer always indicating the tension of the gas. These operations being repeated several times by alternately evacuating and introducing new nitrogen, finally, the tension of the gas * Whatever may he, under certain conditions, the practical importance of prismatic analysis in detecting certain substances converted into vapour, whatever may be its use in indicating traces of a single gas imper- ceptible by other means, mixtures of permanent gases are not fitted to be examined by the prism. A gas, if mixed in rather small proportion with another one, entirely escapes observation. The proportion necessary to render it visible depends upon the nature of the gas as well as upon the temperature of ignition. SPECTEA OE IGNITED GASES AND VAPOUES. i (measured by means of the manometer) being from 40 millims. to 80 millims., the spec- tral tube was melted off and hermetically sealed. 16. When we send through our nitrogen-tube the direct discharge of Ruhmkorff’s large induction coil, without making use of the Leyden jar, we observe a beautiful richly coloured spectrum. This spectrum is not a continuous one, but divided into bands, the character of which differs essentially at its two extremities ; its middle part is in most cases less distinctly traced. Towards the more refracted part of the spectrum, the bands, illuminated by the purest blue or violet light, present a channeled appear- ance *. This effect is produced by a shading, the intensity of which decreases from the more to the less refracted part of each band. On applying four prisms instead of two, we perceive a small bright line, forming an interstice between two neighbouring chan- nels, and the shading is, by the telescope of the spectral apparatus, resolved into dark lines. The number of such dark lines of one of the brightest bands (of the eighth band, we always count from the red to the violet) was found to be thirty-four, or nearly so. Their mutual distance is nearly the same, but their darkness decreases towards the least- refracted limit of each channeled band. Hence we concluded, the breadth of the band having been measured, that the angular distance of two contiguous shading-lines was nearly equal to the distance of the two sodium-lines. The breadth of the channeled bands varies, but the character of all is absolutely the same ; only if foreign bright lines like those of hydrogen are simultaneously seen, it becomes slightly disturbed. We may distinguish seventeen bands of this description ; the first three are smaller ones, the fourth is traversed by H/3, the eleventh by Hyf. At the violet extremity the light is very faint. 17. The bands of the less refracted part of the spectrum are all of nearly the same breadth, but smaller than those just described, and of quite a different appearance. Making use of only a single prism, and of a small magnifying power, we count eighteen such bands, starting from the extreme red and extending to the greenish yellow, where they are bounded by a dark space. H a falls within the fourth, and the double sodium-line (Na) within the fourteenth of these bands. Under favourable circum- stances, both extremities of the spectrum being equally developed, these bands extend to the channeled part, their number rising to thirty-five. All have the same general character, but not the same brightness. From the extreme red the intensity of light * Under favourable conditions such a band appears furrowed semicircularly ; but psychological effects of this description may be quite different : partly by our own will, partly by exterior circumstances, the bands may be seen convex as well as concave. Even the engraving of the bands (Plate I.) shows it. Let it be illuminated by daylight through a window, you will see the bands concave if their more refracted and shaded part be directed towards the window ; if in the opposite direction, the bands will appear convex. The shade passes from one side to the other if really concave and convex bands are replaced by one another ; so it does if the illuminating light pass to the opposite side. Accordingly, the stereoscopic appearance depending upon the direction from which the light comes, the mind passes judgment on it unconsciously. t "We denote by Ha, H/3, and Hy the three bright lines of the spectrum of hydrogen (the red, the bluish green, and the violet one). See 57. 8 DRS. J. PLUCKEE AND J. W. HITTORF ON THE increases to the eighth band ; over the ninth, tenth, and eleventh, especially over the two last, a shadow is spread, which gives to the red a rather brownish tint. The next seven bands are of a fine orange and yellow colour. The nineteenth and twentieth bands are very dark, the twenty-first is less dark. The following bands have a green colour, varying in brightness. The darkest are the twenty-eighth and twenty-ninth, succeeding the lightest ones. The cause producing these bands and their shading by dark transverse lines is evidently not the same as that which produces the shadow overspreading some of them. This may be concluded, for instance, from the fact that the shadow which darkens the nineteenth and twentieth bands, without entirely destroying their limits, spreads at the same time over the neighbouring third part of the preceding eighteenth band. 18. When the light sent out from the incandescent nitrogen within the capillary tube is dispersed by means of four prisms, the shading of the less refracted bands also is resolved into dark narrow lines ; but these lines are smaller than the similar lines of the more refracted bands, and their distribution quite different. If the dispersion increase, in each band we at first perceive a new dark limit ; but the design becoming gradually more defined, we observe in each band extremely delicate bright lines bounded by a shadow or by dark lines. By closer examination of a band we distinguish first a least-refracted small part, occupying about the seventh part of the whole, formed by two bright lines including a somewhat larger dark space. The first of these two bright lines touches the dark extremity of the preceding band ; the second is bounded by a subtle dark line, to which succeeds a third bright line, smaller than the two first. A fourth bright line divides the whole band into two parts, one less refracted, comprising the small one just described, the other more refracted and larger — the breadth of the two parts being about in the ratio of 4 : 5. Starting from the bright middle line, a feeble shading is produced by a number of most subtle dark lines, the darkness of which decreases towards the least-refracted part. Similar but darker lines produce the stronger shading of the larger more refracted part, decreasing in the same direction from the extremity of the whole band towards its bright middle line. The stereoscopic effect produced by the shading of the bands is represented by the diagram (Plate I.). The configuration of all the bright orange and yellow bands is exactly the same ; it is rather obscured in the case of the preceding bands by the shadow spreading over them, but becomes the same again in the bright red ones. Even in the dark bands 19 to 21, traces of the design are to be seen. The appearance of the green bands, though the general character be the same, slightly differs ; the shading in the middle part of them being increased, they rather seem to be divided into two. The accordance of these bands, even to the minute detail of their configuration, is a fact worthy of attention. 19. The character of the two systems of bands on the extremities of the spectrum is SPECTEA OE IGNITED GASES AND YAPOUES. 9 entirely stereotype ; all apparent changes result from the different intensity of light. The middle part of the spectrum, on the contrary, may much differ from that which we have described ; you may even say that this part varies more or less essentially on replacing one spectral tube enclosing nitrogen by any other. Sometimes the traces of the less refracted bands are seen far beyond H/3, spreading over the channeled part of the spectrum ; in other cases the channeled appearance goes in the opposite direction as far as the sodium-line, disturbing the character of the bands. 20. Now, instead of the direct discharge of Ruiimkorff’s large induction coil, let us send through the very same spectral tubes the discharge of the interposed Leyden jar. The spectrum then obtained (Plate II.) has not the least resemblance to the former one. The variously shaded bands which we have hitherto described are replaced by brilliant lines on a more or less dark ground. Neither the distribution of these new lines nor their relative brightness gives any indication whatever of a law. Nevertheless the place occupied by each of them remains under all circumstances invariably the same. If exactly determined, not only does each line undoubtedly announce the gas within the tube, but the gas may even, without measuring, be recognized at first sight by charac- teristic groups into which the lines are collected. 21. The new spectrum of nitrogen extends towards the red slightly beyond the hydrogen-line Ha, which if the gas be not dried with care will be seen simultaneously, enclosed by two red nitrogen-lines, the less refracted of which is twice as distant as the more refracted. There are in the spectrum five groups of brilliant lines especially remarkable. The orange group, slightly less refracted than Na, is formed by four lines, the second of which is the brightest ; the third, not quite so bright, is closely followed by the fourth, which is very faint. The second (yellow) group contains seven lines, among which the fifth is brightest. The third (light-green) and the fourth (dark-green) group contain each nine lines. The third and sixth lines of the light-green group and the sixth and seventh (both near to each other) of the dark-green group are brightest. The fifth (light-blue) group (the distance of its middle part from H/3 and Hy is about in the ratio of 3 : 4) is formed by six lines, the second of which is the brightest, the first slightly less bright ; the last four lines, nearly equally distant from each other, are slightly less bright again. Two groups, of three fainter lines each, fall between the two green groups and between the dark-green and the blue. We may mention also two bright single lines, placed out of the groups — a green line preceded by an expanded one, and a light-violet line followed at a short distance by a bright band. Besides, there are in the spectrum more or less faint bands or expanded lines extending beyond Hy nearly as far as the distance between this line and H/3, i. e. about to Fraunhofer’s line H. 22. We may denote the orange, yellow, light-green, dark-green, and blue groups by I, ii, hi, iv, and v, and the single lines of them by the arabic numbers, the place they occupy in each group being reckoned from the less to the more refracted. Thus by adding the chemical symbol of the gas we get a general method of denomination, mdccclxv. c 10 DBS. J. PLUCKER AND J. W. HITTORP ON THE according to which N n 5, N iv 6, N iv 7, and N v 2, for instance, indicate the brightest lines of the groups of the nitrogen-spectrum. 23. Not only is the general character of the two kinds of spectra we obtained when nitrogen was heated in our tubes, either by the direct discharge or by the discharge of the interposed Leyden jar, quite different, but the difference is even so great that the bright lines of one of the spectra do not in the least fall within the brighter part of the bands constituting the other. Thus, for instance, the bright yellow line (N ii 5) falls within the nineteenth band, the darkest of all the bands constituting the less refracted part of the spectrum ; the bright blue line (N v 2) falls into the darker part of one of the channeled spaces. Accordingly it appears by no means probable that by increasing the temperature the shaded bands of one spectrum may be transformed gradually into the bright lines of the other ; nevertheless it would be desirable to prove by experiment that the passage from one spectrum to another is a discontinuous and abrupt one. 24. For a given nitrogen-tube which without the Leyden jar gives the spectrum of bands, and by means of the commonly used jar the spectrum of bright lines, you may easily select a jar of smaller covering, which, if intercalated, exhibits the curious phe- nomenon of two rival spectra disputing existence with each other. Sometimes one of the spectra, sometimes the other appears ; and for moments both are seen simultaneously. Especially the brighter lines of the second spectrum abruptly appear in the blue and violet channeled spaces of the first, and, according to the fluctuation of the induced current, either suddenly disappear again or subsist for some time, and constitute with the added fainter lines the second spectrum. We obtain in an easier and a continuous way both spectra simultaneously by making use of a small Leyden jar, and increasing its charge by an intercalated stratum of air the thickness of which increases till the bright lines appear within the bands of the primitive spectrum. 25. By these and other experiments it is evidently proved that ignited nitrogen shows two quite distinct spectra. Each bright line of one of these spectra, each of the most subtle lines into which, by means of the telescope, the bands of the other are resolved, finally depends upon the molecular condition of the ignited gas, and the corresponding modification of the vibrating ether within it. Certainly, in the present state of science, we have not the least indication of the connexion of the molecular constitution of the gas with the kind of light emitted by it ; but we may assert with confidence that, if one spectrum of a given gas be replaced by quite a different one, there must be an analogous change of the constitution of the ether, indicating a new arrangement of the gaseous molecules. Consequently we must admit either a chemical decomposition or an allo- tropic state of the gas. Conclusions derived from the whole series of our researches led us finally to reject the first alternative and to adopt the other. 26. The same spectral tube exhibits, in any succession whatever, as often as you like, each of the two spectra. You may show it in the most striking way by effecting the intercalation of the Leyden jar by means of a copper wire immersed in mercury. As SPECTEA OE IGNITED GASES AND VAPOURS. 11 often as the wire is taken out of the mercury we shall have the spectrum of bands ; as soon as the communication is restored, the spectrum of bright lines. Hence we con- clude that the change of the molecular condition of nitrogen which takes place if the gas be heated beyond a certain temperature by a stronger current, does not permanently alter its chemical and physical properties, but that the gas, if cooled below the same limit of temperature, returns again to its former condition. 27. The essentially different character of the two extremities of the first spectrum of nitrogen, as described (16-19), and the indistinctness of its middle part, suggested to us the idea that, in reality, the observed spectrum might originate from the superposition of two single spectra. Accordingly one of these single spectra, the more refracted part of which is best developed, must be formed by channeled spaces ; the other one, the less refracted part of which is best developed, must be a spectrum of shaded bands. In different cases, either the one or the other of the spectra may be predominant. In order to confirm our conjecture it was necessary to get the two spectra separated. 28. The discharge of Ruhmkorff’s coil through a spectral tube is changed the less by introducing the Leyden jar, the weaker is the resistance opposed to it by the tube. Accordingly the two different degrees of temperature to which the gas rises by the discharge when, the coil remaining the same, we either make use of the jar or not, may be regulated in such a way as to approach one another more and more. Let the tension of the gas of about 10 millims. remain the same, the temperature produced by the discharge will be diminished by increasing the interior diameter of the capillary part of the spectral tube. Thus we succeeded in constructing a tube which, when the direct discharge was sent through it, became incandescent with the most brilliant gold- coloured light, which might easily be confounded with the light of highly ignited vapours of sodium ; but with the intercalated jar, the light of the incandescent gas within the same tube had a fine bluish-violet colour. The yellow light, when analyzed by the prism, gave a beautiful spectrum of shaded bands, extending with decreasing intensity to the blue, the channeled spaces being scarcely perceptible. The bluish light, when examined, was resolved by the prism into channeled spaces extending towards the red, while the former bands almost entirely disappeared. We may transform each colour and its corresponding spectrum into the other ad libitum. Hence it follows that there is another allotropy of nitrogen, which, like the former, is not a stable and permanent one, but depends only upon temperature. The modification in which nitrogen becomes yellow corresponds to the lower, the modification in which it becomes blue to the higher temperature. 29. When we send the direct discharge of Ruhmkorff’s coil through one of Geissler’s wider tubes enclosing very rarefied nitrogen or air (the oxygen of air becomes not visible here), we see the negative pole surrounded by blue light, the light at the positive pole being reddish yellow. In such of Geissler’s tubes as are especially calculated to show how the light starting in all directions from the different points of the negative elec- trode is by the action of an electro-magnet concentrated along the magnetic curves c 2 12 DBS. J. PLUCKER AND J. W. HITTORF ON THE passing through these points, the blue light is most beautiful. It belongs generally to the nitrogen alone, which, on account of the greater resistance at the negative electrode opposed to the discharge, reaches a higher intensity of heat there than at the positive pole. When analyzed by the prism, the blue light gives the spectrum of channeled spaces, with traces only of the less refracted bands. The reddish-yellow light of the positive pole is more faint, and therefore not so easy to be submitted to spectral analysis. 30. When Ruhmkorff’s large induction coil is discharged in common air between two points the distance of which does not exceed a few centimetres, we obtain, as is well knoAvn, a brilliant spark surrounded by an aureola, the colour of which is partly bluish violet, partly reddish yellow. In order to separate these colours more distinctly from each other, the aureola, moved by the slightest breath, may be extended into a large surface by blowing it sideways. But the separation may be best made when the dis- charge takes place between the two poles of an electro-magnet in the equatorial direc- tion. While the straight spark is not acted upon by the electro-magnet to any sensible degree, the aureola is expanded into a fine surface, bounded by the spark starting from one to the other extremity of the electrodes, and by a semicircle passing through these extremities. At a certain rarefaction of air this surface appeared most beautifully bounded by a semicircular golden-coloured band, and divided by a similar band into two parts*. We may explain now in a satisfactory way the appearance, hitherto mysterious, of the golden light. Both the yellow and the blue light are owing to the nitrogen of the air, reduced by the heat of the current into the two allotropic states which exhibit the spectra of channeled spaces and of bands. The brilliant white light of the spark partly belongs to the oxygen, partly to the nitrogen of the air, both highly ignited, the nitrogen being in that allotropic state in which it exhibits the spectrum of bright lines. 31. In order to complete the history of the spectrum of nitrogen we add two remarks. First, by intercalating a Leyden jar and, in order to weaken the current, at the same time a stratum of water or a wet thread, we may also reduce the spectrum of bright lines to the spectrum of bands. Secondly, by increasing the density of the gas, or, if the gas be less dense, by intercalating at the same time a large jar and a stratum of air, the bright lines of the spectrum, at the highest obtainable temperature, will expand. Out of a great number of observations made in this direction we shall describe only one. 32. A short spectral tube enclosing nitrogen of a tension of about 250 millims. refused passage to the discharge of Ruhmkorff’s large induction coil, when three of Grove’s elements were made use of and the jar intercalated. Without the jar the discharge passed through and produced a bright but rather undefined spectrum of bands. When the current continued to pass, the indistinctness of the spectrum in- creased, and after short intervals brilliant coloured lines appeared and disappeared again, like lightning-flashes. These lines, occupying always the same place, belonged to the second spectrum of nitrogen, the brightest yellow and green lines of which * Pll'cker, “TTeber die Einwirkung desMagnetes auf die elektrische Entladung,” Poggendohff's ‘Annalen,’ vol. cxiii. p. 267. SPECTRA OF IGNITED GASES AND VAPOTJRS. 13 (N ii 5, N iv 6, N jv 7) were specially observed. When we made use of twelve of Grove’s elements ranged into three sets of four combined ones, the current even passed after we interposed the Jar, and we got a most dazzling second spectrum of the gas. The bright lines of this spectrum, rising from a ground itself brighter than it usually is, ceased at an increased brilliancy to be well defined. The two brilliant green lines both expanded, and were united into a single broad line ; the double yellow lines, though expanded, yet remained double. The spectrum was progressing towards a continuous one . 33. In recapitulating, we get the following results: — Nitrogen in the state of greatest rarefaction, such as may be obtained by Geissler’s exhauster, like other gases does not allow the induction current to pass through. But when its tension is only a small fraction of a millimetre, the current begins to pass and renders the gas luminous. Below a certain limit of temperature ignited nitrogen sends out a golden-coloured light, giving the spectrum of bands. Above this limit the colour of the light is replaced by a bluish violet, the spectrum of channeled spaces replacing simultaneously the spectrum of bands. When, by means of the intercalated jar for instance, the temperature rises to a second higher limit, the light of the gas, becoming white and most brilliant, gives, if analyzed by the prism, a spectrum of quite a different description : bright lines of different intensity, with the colour indicated by the place they occupy, rise from a dark ground. By increasing the power of the discharge these lines become more brilliant, but the brilliancy does not increase in the same ratio for them all. New bright lines appear, which formerly, on account of their extreme faint- ness, were not visible ; but the number of such lines is not unlimited. By increasing the heat of the ignited nitrogen to the last extremity, the lines, especially the brighter ones, gradually expand, approaching thus to a continuous spectrum. 34. Those spectra which are composed of larger bands showing various appearances according to their being differently shaded by subtle dark lines , we generally call spectra of the first order. In the same spectrum the character of the bands is to a certain extent the same, the breadth of the bands varies in a more or less regular way. On the con- trary, those spectra in which brilliant coloured lines rise from a more or less dark ground, we call spectra of the second order. Ignited nitrogen therefore exhibits, if its temperature increase, successively two spectra of the first and one of the second order. 35. In the case of sulphur, which we may select as another instance, there are two different spectra, one of the first and one of the second order. In common air the flame of sulphur gives a continuous spectrum ; if fed with oxygen we get a spectrum of the first order, but it is faint and its bands are not well defined. In order to get the sulphur-spectrum most perfect, we must recur to our spectral tubes. A doubly bent short tube (6), into which we introduced a small quantity of sulphur, was evacuated by means of Geissler’s exhauster, and while attached to it heated by a lamp, in order to expel as much as possible the moisture it contained. Finally, the mano- meter showing no more tension of the remaining gas, the tube was hermetically sealed 14 DES. J. PLtJCKEE ANT) J. W. HITTOEF ON THE by a blowpipe. The direct charge of Ruhmkorff’s large induction coil sent through it, generally indicates by their spectra traces of remaining foreign substances (8). But when the tube was heated by a small alcohol-lamp, at a certain moment a fine sulphur- spectrum of the first order appeared, undisturbed by any former spectrum. The beauty of the spectrum increased when we continued to heat moderately. 36. We counted thirty-seven well-defined bands, extending nearly from Ha to Hy. Seven of these bands, the first of which was of a dark-red colour and visible only under favourable circumstances, preceded the sodium-line, eighteen fell between this line and H/3, and eleven between H/3 and Hy, the last of which being broader, appears some- times divided into two. After a last band, traversed by Hy, a larger and strongly shaded space extended towards the extreme violet. The breadth of the bands increased from the less to the more refracted part of the spectrum. In each band, contrary to what takes place in the case of nitrogen, namely, with regard to its chan- neled spectrum, the shading produced by fine dark lines decreases from the less to the more refracted extremity. The darkest part of the shadow is bounded by a small sepa- rate band of a varied appearance, generally formed by two small bright lines including a somewhat larger dark one. By these small bands the purely channeled character of the spectrum is disturbed. 37. If, while the discharge is passing, we continue to heat the tube by a lamp, the brightness of the spectrum always increases ; but if we approached to a certain degree of temperature, in different parts of the spectrum we have described, bright-coloured lines belonging to the sulphur-spectrum of the second order appeared and disappeared again according to the fluctuating heat, till at last the second of the two rival spectra remained undisturbed. The colour of the light was changed. In cooling again after the lamp was taken off, the light within the tube changed its colour again, while the spectrum of the second order was replaced by the spectrum of the first order. There is a certain elevation of temperature at which the increased density of the vapour does not permit the discharge to pass ; the light within the tube is extinguished, but abruptly reappears after cooling. 38. Well-defined bright lines, constituting a fine sulphur-spectrum of the second order, are obtained if moderate discharges of Rhumkoeff’s large induction coil are sent through the tube, the tube being slightly heated by means of an alcohol-lamp, and a small Leyden jar being intercalated. At first the spectrum extends only from about the sodium-line to H/3. One observes chiefly a characteristic group of sixteen lines, followed at some distance by two separate lines. The spectrum once developed persists even after taking off the lamp. When we continue to heat, the brightness of the group increases and its lines begin to expand, while at the same time the hitherto black ground is coloured. The brilliancy may be increased to such an extent as to be unbearable to the eye. Beyond the sodium-line, towards the red extremity, new distinct lines appear, among which we particularly distinguish a triple line, remarkable as well for its fine red colour as for its distinctness, and nearer to Ha a second such triple line, at first well SPECTEA OF IGNITED GASES AND VAPOUES. 15 defined but soon merging into a single one. Like the less refracted part of the spec- trum, the most refracted part is developed only at a higher ignition of the vapour of the sulphur. At its violet extremity (we do not give here a full description of the middle part) we observe at the same distance from one another five well-defined fainter bright lines. Then follows, after an expanded violet band, a group of four bright lines, the second of which is accompanied by a more refracted, the fourth by a less refracted faint line. The fourth line especially is distinct to a degree seldom observed at so high a refraction and so great a power of the discharge. After two bands of faint light, there is seen at the end of the spectrum a group of four slightly expanded bright lines, preceded by an expanded violet band. 39. Like sulphur, selenium has two spectra — one of the first, another of the second order. 40. Ignited carbon, even in a state of greatest division, gives a continuous spectrum. 41. We select, among the various compound gases which, if decomposed in flame, give the spectrum of carbon, in the first place cyanogen. The gas was procured by heating cyanide of mercury introduced into a retort of glass by means of a lamp. The flame of it may be fed either with oxygen or with air. When a jet of cyanogen mixed with oxygen is kindled, in the interior part of the flame a most brilliant cone of a whitish-violet light is seen, the limit between the ignited and the cold part of the jet. This cone exhibiting the spectrum of vapour of carbon best developed, we conclude that the cyanogen must be decomposed into carbon and nitrogen, the carbon being in the gaseous condition a moment before its combination with oxygen takes place*. 42. In order to prevent explosion of the mixture of cyanogen and oxygen, it is pre- ferable that the jets of the two gases meet from opposite sides before the slit of the spec- tral apparatus, forming there, if kindled, a brilliant, flat, vertical surface. The jet of cyanogen might be obtained directly from the retort, by the heating of tvhich it may be regulated. Thus we get, all being properly arranged, a splendid and richly coloured spectrum. Especially we distinguish eight groups of bright lines , which, being all of the same general character, indicate at first sight the existence of vapour of carbon. We shall denote these groups, starting from the less refracted and proceeding to the more refracted ones, by a, b, c, d, e, f, g , h. The group a is formed by five, b by six, c by four, d by five, e by seven, f by three, g by seven, and h by three bright lines. But these lines, of a measurable breadth and a quite different appearance, are not to be confounded with the bright lines which, in the case of nitrogen and sulphur, for instance, constitute spectra of the second order. In each group the first line is the brightest ; the following, which are nearer to one another, decrease in intensity, and under less favourable circum- stances the last ones are not seen. Hence the groups, according to an expression of Mr. Attfield, have the appearance of a portico. The red group (a) is not always seen distinctly (less distinctly in the present case than in the case of other gaseous com- * Mr. Attfield has the merit of haying first stated that spectra hitherto attributed to compound gaseous substances, are to he referred to the vapour of carbon itself (Philosophical Transactions for 1862, p. 221). 16 DES. J. PLtJCKEE AND J. W. HITTOEF ON THE pounds of carbon) ; the group f is very faint, the group g beautifully violet, h rather ultra-violet. 43. The whole spectrum, except its red extremity, is divided into large shaded fields. The shadow increases from the less to the more refracted part of each field ; from its Drighter less refracted part arise the bright lines of one group, the first of these lines towards the darkest extremity of the preceding field. As well as in the former cases of nitrogen and sulphur, the shadow is produced by dark transversal lines on a coloured ground. But here the distance of the shading-lines from each other varies even in the same field. Towards the bright, i. e. the less refracted extremity of each field, the distance decreases, while at the same time the darkness and the breadth of the lines is diminished. The space between two consecutive lines appeared to be greatest in the field containing the group c, at a distance from d about twice as great as that from c. There we counted, on making use of two prisms and applying a magnifying-power of eighteen, the aperture of the slit being regulated in the ordinary way (13), nine shading- lines, including eight nearly equal small bands, the total breadth of which corresponded to five divisions of our arbitrary scale. Hence we computed the angular distance of two consecutive dark lines which we observed to be about five-fourths of the distance of the sodium-lines. The dark shading-lines also appear within the bands bounded by the lines of the brighter characteristic groups. The band between the second and the third bright line of the yellow group b, the total breadth of which corresponds to four divisions of our arbitrary scale, was divided by dark lines into twelve smaller bands of about equal breadth. Accordingly the angular distance of two such consecutive lines is about two- thirds the distance of the two sodium-lines. The dark lines within the neighbouring band, bounded by the first and second bright line of the same group, were much nearer to one another, and their number too great to be counted with certainty. 44. Between the groups f and g there is indicated a particular distribution of light and shadow, which, being a faint copy of what takes place if olefiant gas be burned instead of cyanogen, will be better understood after we have described the spectrum of the new gas. 45. The least-refracted part of the spectrum, preceding the first line of the group a , essentially differs from the more refracted part already described. There are three fine red bands contiguous to the first bright line of the group, extending nearly to Ha, and beyond this hydrogen-line, after a dark space, two similar but not so well-defined bands. The breadth of these bands is nearly the same, and all are shaded in a similar way. Contrary to the distribution of shadow in the larger field, the shadow is strongest in the less refracted part of each band ; in the most refracted part we observed two bright lines. 46. When the combustion of cyanogen took place in air, the bands we have just described were best developed, and new similar ones added. They extended from beyond Ha nearly to H/3. The breadth of these bands slightly increases towards the violet end of the spectrum, their general description remaining the same. We especially counted seven such bands, the first of which is traversed by the double sodium-line, and the last SPECTEA OF IGNITED GASES AM) VAPOURS. 17 is bounded at the place formerly occupied by the second bright line of the character- istic group c. When the flame of cyanogen is fed by air, we observe under favourable circumstances no traces of the groups a and b, the least-refracted bright line of the group c faintly appears, d is scarcely indicated, but the groups e , f, g are fully developed, especially the last one, of a fine violet colour. 46. In supplying the flame of cyanogen by air increasingly mixed with oxygen, we distinctly see two spectra overlying one another. One of these spectra (the spectrum of bands) giving way step by step to the other, the appearance is continually changed. The red bands only remained undisturbed, they became even more distinct by the increased intensity of the combustion. The adjacent group a is scarcely developed, evidently on account of an imperfect extinction of the overlying bands. The superposition of the two spectra introduces new details into the general configu- ration of the resulting spectrum. Thus, for instance, at a certain intensity of combus- tion the interval between the first and second bright line of the group b is divided by four fine bright lines into five spaces, the breadth of which decreases towards the violet part of the spectrum. Thus also in the large field containing the group c, the influ- ence of the spectrum of bands is rendered sensible by a particular distribution of shadow. 47. Secondly, we submitted to a closer examination olefiant gas, H4 C4, when burned either with oxygen or with air. We operated as we did in the former case of cyanogen ; only the gas, prepared by heating a mixture of alcohol and sulphuric acid, was previ- ously introduced into a gasometer. The luminous cone which exhibits the spectrum of vapour of carbon is of a fine blue colour, especially if the flame is fed by oxygen. 48. In the spectrum thus obtained the characteristic groups a, b, c, and d appeared on a shaded ground. All these groups, especially the red one a, scarcely seen in the spectrum obtained by the combustion of cyanogen, are finely developed. The last line of b and d is slightly expanded ; but there is no trace whatever either of the bands of the spectrum of cyanogen, if burned in common air, or even of the groups e and g. Instead of these groups there is quite a new configuration. Equally distant from the place which the groups occupied in the former spectrum, a small well-defined black band was seen, bounded on the more refracted side by a violet space, which, being of great brilliancy where it touches the band, was shaded gradually till the spectrum, not extending beyond the place of the group g , was extinguished. This violet space is tra- versed by well-defined dark lines, equally distant from each other, but more apart than the shading lines we described in former cases. The black band is bounded on its less refracted side by a bright line, having the breadth of the lines of the characteristic groups, which at a certain distance was preceded by a more diffused violet light, tra- versed, like the brilliant one on the opposite side, by dark but less distinct lines. Here also the faint group f appeared. The distribution of light and shade producing the configuration just described i& MDCCCLXV. d 18 DRS. J. PLtJCKER AND J. W. HITTORF ON THE seen also, distinctly but faintly, in the spectrum we obtained by the combustion of cyanogen with oxygen, where at the same time the groups e and g are beautifully expressed (44). 49. Among the gases exhibiting the spectrum of vapour of carbon, when enclosed in our spectral tubes and decomposed by the heat of the discharge of Ruhmkorff’s coil, we first select oxide of carbon. In operating with this gas as we did with nitrogen, we got, if the Leyden jar was intercalated, simultaneously the spectrum of vapour of carbon and the spectrum of oxygen ; without the jar, the pure spectrum of vapour of carbon. In the last case the heat of the discharge is high enough to ignite vapour of carbon, but not sufficient to give the spectrum of oxygen. The single spectrum, as well as the combined one, is obtained accordingly ad libitum ; whence we conclude that as the successive discharges pass through the spectral tube, the gas is alternately decom- posed and recomposed again. 50. We shall in a few words describe the spectrum obtained without the jar, at a ten- sion of the gas, when observed by means of the manometer before the spectral tube was sealed, of 32 millims. Four characteristic groups only were seen, a, b , c, and d. When the current first passed, the band a appeared completely ; after some time its two first lines only remained, rising as isolated bright lines from a dark ground ; finally all the group dis- appeared. The groups b, c, and d remained nearly unchanged ; there appeared only two bright lines of c , the place corresponding to the two following ones being very brilliant. The whole spectrum was divided into large fields, similar to the fields we described in the case of the flame of cyanogen fed with oxygen. But in this case each field is bounded at its more refracted and shaded extremity by the first bright line of a charac- teristic group ; the following lines, bordered by shading, rise from the lightest part of the adjacent field. In the new instance the fields are not bounded in the same way. After the group a has disappeared, there is a differently shaded dark space, extending to the place of the third bright line of that group. In the remaining part of the spec- trum we may distinguish seven shaded fields. The first goes a little beyond the first bright line of the group 5, where it is bounded by a transversal line, dividing the band formed by the first two lines of the group into a dark less refracted and a light more refracted part. Accordingly the first bright line rises from the dark end of the first field, the remaining lines from the light end of the second field. The second field does not reach the first bright line of the following group c , this line being nearly equally distant from the extremity of the field and the next line of the same group. The third field goes slightly beyond Hp ; the fourth to the first line of the group d ; the fifth nearly to the place occupied by the fifth line of the group e ; the sixth approaches the place of the group/; and the seventh extends to the fourth line of the group g. The fourth and sixth fields presented the appearance of pure channeled spaces, as described in the case of nitrogen. SPECTRA OF IGNITED GASES AND VAPOIJES. 19 51. If the heating-power of the discharge be too strong, spectral tubes enclosing oxide of carbon at a higher tension showed only three large shaded fields, without any traces of the characteristic groups. The first two of these fields are coincident with the second and third of the former fields ; the third occupies the place of the fourth and fifth former fields united into one. Here the shading of the three large fields not being disturbed by any additional appearance, the transversal shading lines were observed most distinctly even in making use of four prisms and employing a magni- fying power of 36. In observing especially the light and less refracted part of the first field close to its extremity, these lines, on account of their extreme subtleness, are scarcely to be perceived ; when they begin to become well defined they are very near to each other; but towards the more refracted part of the field their distance increases simultaneously with their breadth, till, at some distance from the bright extremity, the dark expanded lines are resolved into small shaded bands*. 52. Spectral tubes containing carbonic acid instead of oxide of carbon gave essen- tially the same spectra. The increased quantity of oxygen of the decomposed gas may be observed by means of the interposed jar. In such tubes there was no carbon depo- sited, not even after a long passage of the discharge. 53. All compound gases enclosed in our spectral tubes are decomposed by the heat produced by the discharge of Ruhmkorff’s large induction coil ; but instantly after the discharge passes, the recomposition takes place. The recomposition is prevented only by a sudden cooling of the elementary gases obtained by the decomposition. Thus, for instance, spectral tubes enclosing cyanogen are scarcely fitted for observation, the inte- rior surface of their capillary part being instantaneously blackened by the deposited carbon. No carburetted hydrogen resists final decomposition by the passing current. We add only a few observations, made by means of spectral tubes. 54. The spectrum of the light hydrocarbon gas, C2 H4, obtained without the Leyden jar, at once showed the expanded bright lines of hydrogen and an imperfect spectrum of vapour of carbon, especially the brightest lines of the characteristic groups b , c, and d. By intercalating the jar, the hydrogen-spectrum, approaching to a continuous one, became quite predominant. Olefiant gas , C4 H4, of a primitive tension of about 70 millims., gave, without the jar, a scarcely visible spectrum ; by intercalating the jar, the three hydrogen-lines Ha, H/3, Hy appeared well defined, and the spectrum of vapour of carbon, with its groups a, b, c , d , and its shaded large fields, well developed. Methyl , C2H3, showed, without the jar, at once Ha, H/3, Hy, and the characteristic groups e and g ; with the interposed jar these two groups disappeared, and were replaced by the groups a, b, c, and d. Acetylene, C4 H2, though according to Berthelot and Morren formed from its * The same spectrum, but fainter, is obtained under quite different conditions. We have already noticed, in the introductory remarks, that in a spectral tube evacuated to the last degree by Geissler’s exhauster, vaporized carbon is indicated by its spectrum. The spectrum obtained is that described above (8). D 2 20 DES. J. PLUCKEE AND J. W. HITTOEF ON THE elements when Davy’s charcoal light is produced within an atmosphere of hydrogen, when introduced into our tubes is nevertheless rapidly decomposed by the discharge, and most incompletely recomposed after the discharge has passed. The inside of the tubes is instantly blackened, and in the first moment only, along with the spectrum of hydrogen, we perceive the groups of carbon-lines seen in the case of olefiant gas. 55. Finally, Ruhmkorff’s large induction coil was discharged between two electrodes of carbon, surrounded by an atmosphere of hydrogen. The four groups a , b, c, and d were obtained, constituting the spectrum of vaporized carbon. 56. In resuming, we are struck by the variety of appearances presented by ignited vapour of carbon when submitted to spectral analysis under different conditions. But, whatever may be this variety, it is impossible not to admit that all or nearly all of the various types of spectra we described are derived from the same source. We may distinguish four such types : 1st, the bands, especially seen when the flame of cyanogen is fed by air ; 2ndly, the particular distribution of light and shadow near H|3 when the flame of olefiant gas is fed by oxygen ; 3rdly, the large fields shaded by transversal dark lines ; 4thly, the characteristic groups of bright lines, a, b, c, d, e, f, g, h , which are to be ranged into two different sets, a, b , c, d, and e, f, g, h. It is a curious fact that all these different types, either fully developed or indicated only, are represented in the flame of cyanogen, if fed with oxygen, while in all the other cases we examined there are represented either a single type or two types, or even three, — namely, 1, the third type alone ; 2, the first type, with the second set of groups ; 3, the third type, with one set of groups (a, b , c, d) ; 4, the same type, with the other set ( e , g) ; 5, the second and third types, with the first set of groups. There is no doubt that the different types correspond to different degrees of temperature, — the temperature being lowest when the bands are principally developed, lower in the case of the second set of groups than in the case of the first, lower in the case of the shaded large fields than in the case where the characteristic groups appear simultaneously. In the present state of the question we are not able fully to explain the various types of spectra of carbon. It is only proved that all spectra which we referred to carbonic vapour do not contain any bright line belonging to another elementary gas. Either the well-known spectra of foreign admixed gases, of nitrogen, oxygen, hydrogen, for instance, do not appear at all ; or if they do, they may be subtracted from the whole apparent spectrum. It appears doubtful that the different types depend solely upon temperature. If so, the temperature varying in the different parts of the ignited vapour of carbon, different types may be seen simultaneously. We shall not now discuss the influence which the coexistence of foreign gases might have on the spectra of vapour of carbon, nor may we here decide whether or not, in the lower temperature of the flame, a gaseous compound of carbon, not being entirely decomposed, exhibits, with the spectrum of the vapour of carbon, simultaneously the spectrum of the undecomposed gas. In the spectrum of cyanogen, for instance, we got no visible traces of the spectrum SPECTEA OF IGNITED GASES AND VAPOUES. 21 of nitrogen (originating from the decomposed gas), whether we supplied the flame by a jet of oxygen, or operated in open air; but in both cases there is no reason not to admit that the bands, which are not seen in the case of any other compound of carbon, were owing to the undecomposed cyanogen (see no. 61). 57. With regard to the spectrum of hydrogen , we first refer to former observations. The spectrum one of us obtained by sending the discharge of Ruhmkorff’s small induction coil through one of his highly evacuated spectral tubes, constructed by M. Geissler, shows only three bright lines, which he denoted by Ha, H/3, and Hy. The beautiful red light of the ignited rarefied gas, divided into these three bright lines, even after having passed through the four prisms of Steinheil’s spectral apparatus, remains highly concentrated. At a magnifying power of 72, the three bright lines or small bands thus obtained are well defined. Their apparent breadth is equal to the breadth of the slit ; consequently, on further narrowing the slit, they approach gra- dually to mathematical lines. Hence we conclude that, under the above-mentioned conditions, the length of wave of the light constituting each of the three hydrogen-lines is constant, and remains so if by widening the slit the lines are expanded into bands. In referring the middle lines of such bands to the middle line of the direct image of the slit, we obtain its angle of refraction. It was proposed to employ these middle lines instead of Fraunhofer’s dark lines of the solar spectrum in determining the indices of refraction*. This proceeding has since been proved to be very expedient f. 58. Hydrogen permits the electric discharge to pass at a lower tension than other gases do. When Ruhmkorff’s small induction coil was discharged through a spectral tube enclosing hydrogen, which was gradually rarefied to the highest tenuity to be reached by means of Geissler’s exhauster, finally the beautiful red colour of the ignited gas became fainter, and passed gradually into an undetermined violet. When analyzed by the prism, Ha disappeared, while H/3, though fainter, remained well defined. Accordingly light of a greater length of wave was the first extinguished $. 59. Hydrogen shows in the most striking way the expansion of its spectral lines, and their gradual transformation into a continuous spectrum. When the direct discharge of Ruhmkorff’s large induction coil is sent even through the old spectrum tubes enclosing hydrogen, the formerly obtained spectrum is essentially altered. By increas- ing the power of the coil, the violet line Hy first expands ; while it continues to expand, the expansion of the bluish-green line H/3 becomes visible. Let the aperture of the slit be regulated so that the double sodium-line will separate into two single lines nearly touching one another. Then, the angular breadth of H/3 becoming two or three minutes, the breadth of Hy is about double. The expansion takes place as well * Poggendorff’s * Annalen,’ vol. cvii. p. 497. t Landolt: “Ueber die Breehungsexponenten flUssiger homologer Verbindungen,” Poggendorff’s ‘Annalen/ vol. cxvii. p. 353. t Plucker : “ Ueber recurrente Strome und ihre Anwendung zur Darstellung von Gasspectren,” Poggen- dorff’s * Annalen/ vol. cxvi. p. 51. 22 DES. J. PLtJCKEE AND J. W. HITTOEE ON THE towards the less as towards the more refracted part of the spectrum. Ha remains almost unchanged after H y has passed into an undetermined large violet band, and H/3 extended its decreasing light on its two sides. On employing the Leyden jar, and giving to the gas in our new tubes a tension of about 60 millims., the spectrum is already transformed into a continuous one, with a red line at one of its extremities. At a tension of 360 millims. the continuous spectrum is highly increased in intensity, while the red line Ha, expanded into a band, scarcely rises from it. If the electric spark passes through hydrogen at the ordinary tension, the ignited gas on its way always gives the spectrum of the three expanded lines*. 60. Even in the old spectral tubes enclosing highly rarefied hydrogen, the ground, from which the three characteristic lines rise, did not appear always of the same dark- ness ; in some instances new bright lines appeared, especially in the neighbourhood of the sodium-line. In resuming the subject, we pointed out the existence of a new hydrogen-spectrum , corresponding to a lower temperature, but having no resemblance at all to the spectra of the first order of nitrogen, sulphur, &c. In this spectrum, of a peculiar character, if fully developed, we observe a great number of well-defined bright lines, almost too numerous to count and represent by an engraving, but brilliant enough to be examined at a magnifying power of 72, after the light has passed through four prisms. * After Fraunhofer, and especially Dr. Wheatstone, directed the attention of philosophers to the electric spectrum, Masson indicated the red hydrogen-line, hut without referring in an explicit way to its origin. Angstrom first separated the spectrum of gas from the spectra of metal. In the diagram he gave of the hydrogen-spectrum, he represented, by means of curves, the intensity of light along the whole length of the spectrum, especially the maxima of intensity within the red, the green, and the violet. These maxima corre- spond to Ha, H/3, H y, here expanded into bands, the breadth of which, as well as their decreasing intensity towards both ends, are indicated by the extension and steepness of the curves. After one of us published his first researches on the spectra of ignited gases, M. van der Willigen, in operating with strong induced currents, determined in a similar way the maxima of intensity of the hydrogen-spectrum. The spectra thus obtained are not calculated to prove the connexion existing between the bright lines of ignited gases or vapours and Fraunhofer's dark lines of the solar spectrum. Starting, in his first communica- tion made to the Eoyal Swedish Academy, 1853, from the theoretical conception “ that the dark lines of the solar spectrum are to be regarded as an inversion of the bright lines of the electric spectrum,” M. Angstrom concluded the coincidence of Ha with Eraunhoeer’s line C ; but the diagram shows that this conclusion was not based on exact measurement. One of us, in his publication of 1859, not being guided by any theoretical view on this point, first announced the coincidence of H/3 with Fraunhofer's E, and fixed the position of Hy near G, of Ha at a distance of two minutes from C. When at a later period he made use of Steinheil’s large spectral apparatus, he pointed out at first sight the exact coincidence of Ha with C, Hy with a marked black line at some distance from G, towards E. In operating with spectral tubes, M. Angstrom confirmed these results. (The spectroscope employed in 1859 being a small and imperfect one, there was given to the slit an aperture of more than three minutes. The adjustment was made with regard to H/3. Hence the error finally made in determining the position of Ha may be fully explained, by the circumstance that the illuminated border of the slit was observed instead of the illuminated aperture itself.) — Angstrom : “ Optische Hnter- , suchungen,” Poggendorfe’s c Annalen,’ vol. xciv. ; “ Ueber die ERAUNHOEER’schen Linien im Sonnenspectrum,” Ibid. vol. cxvii. Yan der Willigen : “ Over het electrische Spectrum, Yerhandelingen der K. Hollandsehe Academie (Natuurkunde vii. & viii.). Plucxer, Poggendorfe’s ‘ Annalen,’ vol. evii. p. 544. SPECTRA OF IGNITED GASES AND VAPOURS. 23 61. On sending the direct discharge of Ruhmkorff’s coil through a tube of glass from one-fourth to one-eighth of an inch in diameter, provided with electrodes of platinum or of aluminium, enclosing hydrogen at a tension of 5 to 10 millims., a luminous thread of light of a bluish-white colour was seen passing along the axis of the tube, without touching the glass. When analyzed by the prism, it gave a faint spectrum of the above-mentioned numerous bright lines, especially within the red and the yellow. Among these lines neither Ha nor Hy were seen ; H/3 only appeared, but less bright than many of the other lines. By interposing the Leyden jar and gradually increasing its charge (12), all lines became brighter, H/3 surpassing all other lines in brilliancy ; Ha appeared beautifully, Hy fainter. Hence we conclude that the numerous bright lines belong neither to the vaporized metal of the electrodes, nor to the decomposed interior surface of the glass, but solely to the hydrogen, constituting a new spectrum of it. This spectrum may be seen simultaneously with the three characteristic lines Ha, H/3, Hy ; but at an increased temperature, when these lines begin to expand, it entirely disappears. 62. We got only one spectrum of oxygen in operating exactly in the same way as we did in the case of nitrogen, with merely this difference, that under the same con- ditions a spectrum of equal brightness was obtained only by means of a stronger discharge. Accordingly if oxygen, enclosed in the spectral tube, be replaced by com- mon air, the spectrum of the oxygen it contains does not appear until after interposing the Leyden jar. We do not enter here into the detail of the oxygen-spectrum, but conclude with a general remark. Nearly all luminous lines of the spectra of the second order expand when the temperature of the ignited gas increases beyond a certain limit ; but neither do all lines reach the same brightness before expanding, nor do the lines in the different parts of the spectrum expand at the same temperature. That is seen best in the spec- trum of the second order of oxygen. The bright lines constituting the characteristic groups of its middle part oppose the greatest resistance to expansion. If they are best defined, the luminous lines towards the red extremity, most distinct at a lower tem- perature, are already expanded, while towards the violet extremity the luminous lines are scarcely developed ; they will be brightly developed, become well defined, and extend very far, after the ignited oxygen reaches a temperature at which the groups of the middle part are expanded. Hence arises the difficulty of representing the oxygen- spectrum. A drawing exhibiting the well-defined lines successively developed in its different parts is rather an ideal image than a true representation of nature. 63. Water introduced into a small spectral tube was kept boiling till the last traces of air were expelled, and then, before all the water was evaporated, the tube was hermetically sealed. The direct discharge, if passing, scarcely rendered the tube luminous, but with the intercalated jar the peculiar red light of hydrogen appeared, exhibiting the charac- istic lines Ha, H/3, Hy well defined. When these lines became gradually expanded, the lines of the oxygen-spectrum successively appeared with an increasing intensity, 24 DES. J. PLUCKEE AND J. W. IIITTOEF ON THE finally rising from the hydrogen-spectrum transformed into a continuous one. Here the heat of the discharge is increased by the increased density of the vapour of water, and reciprocally the evaporation is accelerated by the rising temperature of the discharge. The vapour of water is decomposed by the discharge ; the ignited hydrogen resulting from the decomposition exhibits a spectrum at a lower temperature than the resulting oxygen does. After the discharge ceases, oxygen and hydrogen are recomposed again to water. 64. Phosphorus , when treated like sulphur (35), exhibits a beautiful spectrum of the second order. Whatever may be the gradual change of the intensity of light produced by regulating as well the discharge as (by means of a lamp) the heat of the spectral tube, we get only one spectrum of bright lines successively developed. Among them there is one announcing at first sight the presence of vapour of phosphorus, a triple orange line, formed by two single lines of first intensity, and a third less bright one bisecting the interval between them. The other brightest lines are seen within the green. We get no difference at all by introducing into the spectral tube either common or red phosphorus. After the current had passed for some time, common phosphorus was seen, within the tube, transformed into a subtle powder of the red kind. 65. Chlorine , Bromine , and Iodine were among the substances first submitted to spec- tral analysis by one of us. On resuming the subject we fully confirmed the formerly obtained results, that not any two of the numerous spectral lines, characterizing the three substances, were coincident. By means of the electric current we got in all instances only spectra of the second order. We were especially desirous of ascertaining whether there existed a spectrum of iodine, corresponding to a lower temperature, the inverse or negative image of which agreed with the spectrum produced by absorption on sending sunlight (which, in order to prevent the influence of Fraunhofer’s dark lines, may be replaced by the light of phosphorus in combustion) through a stratum of heated vapour of iodine. Thus, indeed, we obtain more than fifty shaded bands, the breadth of which decreases from the violet to the red, constituting a spectrum of the first order. The flame of hydrogen in open air was not fitted to ignite vapour of iodine introduced into it sufficiently. But by feeding the flame by oxygen we got a new spectrum. Large fields, shaded by dark transversal lines, differently bounded, but quite similar to the third type of the spectra of vapour of carbon, constituted a spectrum of the first order. But the spectrum we might have expected according to theory was not seen. 66. Arsenic , when treated like sulphur and phosphorus, gives a well-defined spectrum of the second order. 67. So does mercury when introduced into a spectral tube from which air is expelled, either by means of Geissler’s exhauster, or by boiling the mercury within it. After a slight heating of the tube by means of an alcohol-lamp the discharge passes; and having once passed, it continues to do so, even without the lamp. Vapour of mercury SPECTRA OF IGNITED OASES AND VAPOURS. 25 opposing a comparatively small resistance to the passing current, we found it useful to intercalate at the same time a Leyden jar and a stratum of air. Thus, indeed, by regu- lating as well the density of the vapour as the thickness of the stratum, we obtained the best-developed spectrum. The least quantity of mercury, if vaporized, becomes visible by the passing current. Especially when mixed with other metals like arsenic, antimony, &c., we may detect even the least traces of it, which would entirely elude chemical analysis. Thus, for instance, we observed that arsenic, whatever may be its origin, is not free from mercury. After introducing a small quantity of it, which we heated by an alcohol-lamp when we placed it before the slit of the spectral apparatus, in a few moments four lines of great brightness, among which was a double yellow one, rose from a dark ground, but before the spectrum was fully developed it was abruptly replaced by another quite as brilliant. The first spectrum obtained belongs to vapour of mercury, first developed by evapora- tion, the second to arsenic, which increasingly vaporized at a higher temperature dis- putes the conduction of the discharge with the mercury, the vapour of which, according to its small existing quantity, reaches only a very low limit. The spectrum of arsenic remaining alone, gradually increased in brilliancy by the development and expansion of its bright lines. In cooling the spectral tube, by taking off the lamp, the spectrum of arsenic lost its extreme brilliancy; well-defined bright lines, the number of which gradually diminished, rose from a dark ground, and were replaced again by the spectral lines of mercury, till finally all light was extinguished. 68. The metals of alkalies, sodium, potassium, lithium, thallium show, even at the lower temperature of Bunsen’s lamp, a spectrum of the second order, consisting of bright lines, the number of which is increased by the higher temperature of the current, while the principal ones are expanded. 69. Barium, strontium, calcium show, even in Bunsen’s lamp, shaded bands, and a bright chief single line at the same time. This line, green in the case of barium, bluish violet in the case of strontium, violet in the case of calcium, fully exhibits the character of the bright lines in the spectra of the second order. The bands, if well developed, constitute a spectrum of the first order. We examined especially the spectrum of barium, by introducing its chloride into the hydrogen-flame. In making use of two prisms and employing a magnifying power of eighteen, we distinctly obtained the shading of the bands resolved into dark lines, finer and closer to one another than in former similar cases. Thus we proved that the band-spectrum of baryta is in every respect a spectrum of the first order. 70. Spectra of the first order were observed in the case of a few heavy metals only. Among these metals we mention in the first instance lead. We obtain its spectrum in Bunsen’s lamp, but in order to get it beautifully developed we must make use of the oxyhydrogen flame. The spectra we obtained were identically the same whatever com- pound of lead was introduced into that flame. We especially examined its combinations with chlorine, bromine, iodine, and oxygen. In all cases we observed larger bands, MDCCCLXV. e 26 DRS. J. PLUCKER AND J. W. HITTORF ON THE which by increased temperature were divided into smaller ones. Each band has a chan- neled appearance produced by fine dark lines, the darkness of which increases from the more to the less refracted extremity of the band, contrary to what takes place in the violet channeled spaces of nitrogen. Chloride of lead, when examined within our spectral tubes, showed no traces of bands ; they were replaced by bright lines. But on account of the great difficulty of vaporizing it, the spectrum of the second order, owing to lead, is best developed by the discharge of Ruhmkorff’s coil between two electrodes made from this metal and surrounded by an atmosphere of hydrogen. The spectrum of this gas being under these conditions nearly a continuous one (59), the bright lines of the lead-spectrum of the second order rise from a coloured ground. More than fifty lines were counted, although the fainter ones did not appear. 71. When either chloride or bromide or iodide of copper is introduced into the flame of Bunsen’s lamp, we get spectra of bands, but these bands are not exactly the same, they differ from one another by additional bands*. In the oxyhydrogen flame the bands are better developed, but we did not succeed in resolving the shadows of the hands into dark lines. At the same time four lines of single refrangibility appeared. The number of these lines was increased and the number of bands reduced, when chlo- ride of copper was examined within our spectral tubes. The well-known spectrum of the second order was fully developed, and every trace of bands extinguished, by dis- charging Ruhmkorff’s coil between two copper electrodes. 72. Finally, manganese exhibited a curious spectrum of the first order, most similar to that of carbon (third and fourth type (56)). The whole spectrum is equally divided into large fields, but these fields are shaded differently by fine transversal lines, the shadow increasing from the more to the less refracted extremity of each field. From the brighter less refracted part rise groups of bright lines, similar to the groups of carbon, but the lines of the groups are differently distributed. When Ruhmkorff’s large coil was discharged between two electrodes made from man- ganese (we surrounded them with an atmosphere of hydrogen), a pure spectrum of the second order, free from any traces whatever of the former spectrum, was obtained. Explanation of the Plates. In determining the different spectra both of the first and the second order, the dispersing prisms occupied invariably the same position, corresponding to the minimum deviation of the green hydrogen-line H/3, i. e. of Fraunhofer’s F. All spectra repre- sented in the Plates are referred to the three hydrogen-lines Ha, H/3, Hy, and the double sodium-line Na. Generally two prisms of about 60° and 45° were employed, * This fact has been noticed by At. A. Mitscheblich with regard to the chloride and the iodide, and attri- buted by him to the undecomposed salt (Toggendobff’s ‘ Annalen,’ 1862, vol. ii. p. 299). SPECTBA OF IGNITED GASES AND VAPOURS. 27 giving the distances of Ha and Na on one side and of Hy on the other side from H/3, by the following numbers of divisions of an arbitrary scale : 139-6, 100-5-101, 88-5. In the first Plate portions of all the coloured spectra are represented as they appear by making use of two additional prisms of 45°. PLATE I. contains spectra of the first order. The first spectrum, N, belonging to nitrogen, is taken under such conditions that both its extremities appear equally developed. To the whole spectrum is added a representation of two bands, C, of its more refracted part, obtained by means of the four prisms. Here a determined number of subtle dark transverse lines produce the channeled appearance. Likewise the configuration of two orange bands, A, and two green ones, B, is represented, exhibiting the character of the less refracted part of the spectrum (15-19, 27, 28). S represents the spectrum of sulphur, as obtained by means of an exhausted bent spectral tube enclosing sulphur moderately heated by an alcohol lamp, and traversed by the charge without an interposed jar (35, 36). Two green and two blue shaded bands, as seen by means of the four prisms, are repre- sented by A and B. C I shows the spectrum of vapour of carbon obtained by the combustion of cyanogen in oxygen. It exhibits within the large shaded fields groups of peculiar bright lines, the brilliancy of which it was impossible to represent. These groups are denoted by a , b , c , d, e, f\ g , h. The red extremity becomes fainter when the heat of com- bustion increases, and even appears more distinct if the combustion takes place in air (41-46). The configuration of One of the red bands, as seen when the four prisms are employed, is represented by A. C ii exhibits the spectrum of vapour of carbon obtained by means of spectral tubes enclosing oxide of carbon, the gas being decomposed by the electric discharge (49, 50). On taking away all characteristic groups, the remaining part of the spectrum, consisting only of three large shaded fields, is that obtained if the density of the gas be greater and the discharge too strong (51), as well as in the case of imperceptible traces of decomposed carbonic combinations (8). C hi shows the less refracted part of the brightest of the large shaded fields (51). C iv exhibits a peculiar distribution of light and shade within the violet, scarcely indi- cated in Ci, but well developed when olefiant gas instead of cyanogen is burnt in oxygen (48). 28 DBS. J. PLTTCKER AND J. W. HITTOEF ON THE PLATES II. & III. represent spectra of the second order, on a scale one-third larger than the scale of Plate I. In Plate II. N shows the second spectrum of nitrogen (20-23), O the spectrum of oxygen (63), S the second spectrum of sulphur (37, 38), Se of selenium (39). In Plate III. I shows the spectrum of iodine, Br of bromine, Cl of chlorine. Some remarks may be added here with regard to the conditions under which the spectra are obtained. Iodine was introduced into a bent spectral tube, and the tube exhausted as far as possible. While more recently tubes have been constructed which do not allow the discharge of Ruhmkokff’s large coil to pass, not even at a very short distance of the electrodes, the same effect will scarcely be obtained if iodine is enclosed in the tube. Accordingly the very first moment the phenomena described in art. 8 take place ; but soon after, vapour of iodine is developed, and by the heating power of the discharge we get, without the Leyden jar, a spectrum of mere iodine, consisting of very well-defined lines on a dark ground. After the interposition of the jar these lines became more brilliant, but remained well defined, and their number increased. Then the position and the intensity of the lines of the middle part were determined, while the red extremity was not at all developed, and the violet one most imperfectly. If the density of the vapour is increased by heating the tube by means of an alcohol lamp, the lines deter- mined are expanded, while the’ground becomes illuminated. The brilliancy so increases that the eye can scarcely bear it, till at last the discharge ceases to pass. While the middle part approaches to continuity, a certain number of delicate brilliant red lines, seen in the diagram, appear, and do not lose their distinctness as long as the discharge passes. Towards the violet extremity new lines likewise appear, hut though that extre- mity becomes most brilliant, we were not able to get the lines well defined. Accordingly the position of the expanded lines is approximately indicated by dotted lines. A drop of bromine was introduced into a small exhausted spectral tube. The tension of its vapour being too great to allow the discharge to pass, the vaporized fluid was expelled till the remaining vapour obtained a tension of about 6 centimetres. But by and by the vapour of bromine, combined with the platinum of the electrodes, was deposited on the interior surface of the tube, and after some time, evidently from want of sufficient conducting matter, the beautiful spectrum fainted almost suddenly. The spectrum was taken with the interposed jar. In this case Ha and H/3 are simulta- neously seen, but expanded, indicating traces of remaining water. The lines of oxygen are not seen. Without the jar hydrogen is not indicated. Then four bright lines, belonging to bromine, appear in the neighbourhood of Ha. While, with the interposed jar, they are fully expanded like this hydrogen-line, a less refracted subtle line appears, always remaining most distinct. The blue and violet extremity of the spectrum is better defined than in the case of iodine. SPECTRA OF IGNITED GASES AND VAPOURS. 29 The spectrum of chlorine is taken under similar conditions with the spectrum of bromine. The spectral tube most carefully exhausted was several times filled with chlorine and exhausted again. The final tension of the remaining gas was about 6 centi- metres, as it was in the former case. P exhibits the spectrum of phosphorus (64). We conclude with a general remark regarding more or less all the spectra of the second order represented in Plates I. & IT. The intensity attributed to the different bright lines constituting these spectra corresponds to the condition in which they are best developed.. There seems to be a general rule that all luminous lines become brighter and are finally expanded, when the heating-power of the discharge continually increases. But for different lines the intensity does not rise in the same ratio : thus lines less brilliant at first than others may afterwards surpass them in brilliancy. The inten- sity attained by the different luminous lines before they are expanded greatly differs ; lines may disappear by expansion, while others of the same spectrum do not yet appear. The least-refracted lines generally resist expansion the most. MDCCCLXV. F S pect Nitrogen HH iiiiSili ! & m&W; ■ msmH •t:k| Spectra secundi Ordinis Ni trojciii^/ Ncl jj t Phil. Trans. MDCCCLXYTlateH. >ni Oxygen ii Sulphuris Selenii i. j ih_— iL ! i 3. Si Engraved and print edT>y A..Henrv. Bonn. Spectra secundi ordinis ,c J B C 1 1 1 Phil. Trans. MDCCCLXV.PlatellL i Bromi Chlori Phosphori in r — I — i — L_i J. 1. 1 I I I I Ensnared anl^rinte.l"by A.Eenrj Bonn. [ 31 ] II. On the Osteology of the genus Glyptodon.. By Thomas EL Huxley, F.B.S. Received December 30, 1863, — Read January 28, 1864, Part I. — -The history of the discovery and determination of the remains of the Eoplophoridce. Part II. — -A description of the skeleton of Glyptoclon davipes, Owen ( Hoplophorus Selloi, Lund?). § 1. Description of the Skull. § 2. Description of the Vertebral Column. Part I. — The history of the discovery and determination of the remains of the Hoplo- phoridae, or animals allied to. or identical with , Glyptodon clavipes. The earliest notice of the discovery of the remains of Glyptodon-Yike animals is con- tained in the following extract from a letter, addressed to M. Auguste St. Hilaire by Don Damasio Laranaga, Cure of Monte Video, which appears in a note at p. 191 of the fifth volume of the first edition of Cuvier’s ‘ Ossemens Fossiles,’ published in 1823: — “I do not write to you about my Dasypus (Megatherium, Cuv.), because I propose to make it the subject of a memoir which, I trust, may not be unworthy of the 'atten- tion of those European savants who take an interest in fossils. I will merely say that I have obtained a femur, which was found in the Rio del Sauce, a branch of the Saulis Grande. It weighs about seven pounds, and may be six or eight inches wide. In all points it resembles the femur of an Armadillo. I will send you one of its scales. The tail, as you have seen, is very short and very large ; it also possesses scutes, but they are not arranged in rings, or in whorls. These fossils are met with, almost at the sur- face, in alluvial, or diluvial, formations of a very recent date. It would seem that similar remains exist in analogous strata near Lake Merrim, on the frontier of the Portuguese colonies.” Cuvier expresses no opinion as to the accuracy, or otherwise, of Don Damasio Laranaga’s identification of his Dasypus with the Megatherium, an identification which, it will be seen, was erroneous. The volume of the Transactions of the Royal Academy of Sciences of Berlin for the year 1827 contains a memoir by Professor Weiss* upon the collections of fossils and minerals gathered in South America by Sellow, accompanied by five plates, four of which display excellent representations of various portions of the dorsal and caudal dermal armour, and of part of a femur, of one or more species of Glyptodon. Some of these fossils (the fragments of the dorsal dermal armour) were obtained at three feet from the surface, in the marly clay of which the banks of the Arapey Chico (a branch * Ueber das siidliche Ende des Gebirgzuges von Brasilien in der Provinz San Pedro do Sul und der Banda Oriental oder dem Staate von Monte Video : nach den Sammlungen des Herrn Fa. Sellow, von Herrn Weiss (Gelesen in der Akademie der Wissenschaften am 9. August 1827, und 5. Juni 1828). MDCCCLXV. G 32 PROFESSOR HUXLEY ON THE OSTEOLOGY OE THE GENUS GLYPTODON. of the Arapey Grande, an affluent of the Uruguay) are formed. The skeleton of the Megatherium now at Madrid was found in a similar clay which underlies Buenos Ayres. The femur and the fragment of caudal armour were procured from the banks of the Quegnay, a more northern affluent of the Uruguay than the Arapey. Weiss remarks upon these fossils ( l . c. p. 276) “that it can hardly he doubted that they belonged to no other animal than the Megatherium , Cuv. Cuvier himself pub- lished, in a note to p. 191 of his ‘ Recherches sur les Ossemens Fossiles,’ t. v. le partie, the first information which he received, in 1823, that his Megatherium was a loricated animal. M. Laranaga, parish priest of Monte Video* (from whom this information was derived, and in whose house M. Sellow, in 1822, saw two fragments of the armour, one belonging to the back and the other to the tail, which were found between Monte Video and Maldonado, in a gully opening into the Arroyo de Solis), believed the animal to be an Armadillo, Dasypus ; Cuvier had already pointed out the similarity of the extremities to this genus and to Myrmecopliaga. However, the armour plates found on the Arapey show no trace of a zonary arrangement, and the fragments possessed by M. L Aran ag a also leaving a doubt on this point, it may remain an open question whether the Megatherium possessed a veritably jointed armour, or whether it was not more probably provided with a solid shield.” The figures show, and Professor Weiss remarks upon, the raised conical form of the marginal pieces of the carapace. In the course of his description of the parts of the skeleton of a Megatherium sent to this country by Sir Woodbine Parish, Mr. Clift f remarks, “ In these latter instances the osseous remains were accompanied by an immense shell or case, portions of which were brought to this country ; but most of the bones associated with the shell crumbled to pieces after exposure to the air, and the broken portions preserved have not been sufficiently made out to be, at present, satisfactorily described. Representations, how- ever, of parts of the shell in question are given in the plate annexed.” The plate (46) to which reference is here made exhibits views of the inner and outer surfaces of parts of the carapace of a Glyptodon. In a note (p. 437) Mr. Clift mentions that casts of the principal bones in question have been sent, among other places, to the Jardin des Plantes at Paris. The next work upon this subject in the order of time, is the very valuable essay com- municated by Professor E. D’Alton to the Berlin Academy in 1833 Sellow had * [“ A friend of natural history and, in every way, an estimable man, who has now unfortunately become blind,” writes M. Sellow regarding him to M. von Olfers on the 10th October 1829. We can therefore no longer look for the appearance of his promised essay on these fossil remains.] t “ Some account of the Remains of the Megatherium sent to England from Buenos Ayres by Woobblne Parish, jun., Esq., F.G.S., E.R.S.” By William Clift, Esq., E.G.S., F.R.S. Bead June 13, 1832. Transactions of the Geological Society, vol. iii. 2nd series. t “ Ueber die von dem verstorbenen Herrn Sellow aus der Banda Oriental mitgebrachten fossilen Panzer- Eragmente und die dazu gehorigen Knochen-Ueberreste,” with four plates. The volume of the * Abhand- lungen der Koniglichen Akademie der Wissenschaften,’ in which this essay appears, was published in 1835. PROFESSOR HUXLEY OH THE OSTEOLOGY OF THE GENUS GLYPTODON. 33 been compelled by the local authorities to send to Bio Janeiro all the bones and the finest pieces of the carapace, which he discovered in association with the fragments of dermal armour figured by Weiss*; but, by good fortune, these additional materials at length found their way into the Berlin Museum, and afforded D’ Alton the materials for his memoir, in the first section of which the pieces of the carapace of the fossil animal are described ; while the second section is devoted to an account of the structure of the dermal armour of living Armadillos, and the third to a description of the fossil bones found in juxtaposition with that dermal armour. The results of the comparison of the fossil armour with that of existing Armadillos are thus stated : — “ If we compare these fossil dermal plates with those of living species of Dasypus , it becomes obvious that all the peculiarities of the former may be paralleled by the latter; but with this difference, that while, as appears from Sellow’s report, all the fossil plates belonged to one and the same animal, their peculiarities are not all found associated together in any one living species. The majority of the fossil plates which were distant from the margin, e.g. those represented by Weiss in figs. 1, 4, & 5, and many described above, exhibit the greatest similarity to the dermal plates of Dasypus niger ; and thence it may be concluded that the epidermis of the Dasypus of the ancient world (if for brevity’s sake I may so name the animal), like that of the Dasypus niger , was divided differently from the bony plates, and that strong hairs were arranged in the interstices of the epidermic scales. “ The pieces which belonged to the edge, or the pointed marginal scutes (Zacken), most nearly resemble those of D. Poyou (fig. 12 of our first Plate), and D. grandis shows a somewhat similar formation. In addition, the thoracic shield and the moveable zones of D. villosus (fig. 18) are also provided with pointed marginal scutes; and, according to Azara, the Tatou pichey exhibits similar structures. But in all the animals provided with such pointed scutes, they are directed from above, and forwards, downwards, and * Professor Owen writes (On the Olyptoclon clavipes, Geol. Trans, vol. hi. pp. 82, 83), “ The portions of the tessellated bony armour figured by Professor Weiss, pi. 1 and 2, and described at p. 277 of his memoir, were obtained by Sellow' on the Arapey-Chico in the province of Monte Yideo ; but no bones either of the Megatherium, or any other animal, are mentioned as having been associated with them. A third series of fossils, in which fortunately some bones of the extremities were discovered associated with the tessellated bony case,, was presented to Sellow by the President of the province of San Pedro, with the information that they had been originally discovered in the proximity of Rio Janeiro.” ■ This, however, appears to be a misapprehension of the state of the case.. The armour figured by Weiss in pi. 1 and 2 of his memoir, and the “ third series of fossils ” were associated together : and so far from the President of the province of San Pedro having presented anything to Sellow, it was Sellow who was obliged to present the fossils to the President, or at any rate, to dispose of them according to his orders. “ Denn die Aufforderung. des damaligen Prasidenten der Provinz San Pedro, des Yisconde des S. Leopoldo, nothigte ihn [Sellow] den hauptsachlichsten Theil dieser fossilen Ueberreste nach Rio Janeiro abzuliefern.” It is therefore sufficiently obvious that the fossils were not found at Rio Janeiro, but were sent to that place from Arapey-Chico. G 2 34 PROFESSOR HUXLEY ON THE OSTEOLOGY OF THE GENUS GLYPTODON. backwards ; and therefore some of the fragments may be referred to the left, and some to the right side From the preceding comparisons it follows that the fossil scutes are similar to those of the thoracic and pelvic shields of different living Armadillos, although they differ from them in many respects. But if objections should still be raised to regard- ing the animal which bore the fossil armour as an Armadillo (Giirtelthier), two replies may be made. In the first place, neither the entire skeleton nor the perfect shell of the animal have been obtained. Of the skeleton, the vertebral column, the ribs, and sternum are wanting — or exactly those parts which the moveable zones (Gurtel) would have covered. Secondly, the moveable zones themselves, although among the charac- teristic features of the Armadillos, are of less importance than was formerly believed, as Azara has already pointed out.” The state of the bones indicated that they appertained to a young animal, the epi- physes being distinct. Those described belonging to the fore limb are, a part of the scapula (?), the distal end of the left humerus, the radius and ulna, nearly perfect, and eighteen bones of the fore foot. Of the latter, five belonged to the carpus, of which the three proximal are interpreted by D’Alton as the semilunare (Mondbein), cuneiforme (das dreieckige Bein), and pisi forme (Erbsenbein). I shall endeavour to show, in the course of my description of the specimen which forms the subject of this memoir, that the determinations of the semilunare and cuneiforme are perfectly correct, but that the so-called pisiforme is not rightly named. The distal bones are, according to D’Alton’s interpretation, which I can fully confirm, the magnum and the unciforme. Two entire metacarpal bones, and fragments of another, are considered by the author of the memoir to correspond with the third, fourth, and fifth of an ordinary five-toed fore foot ; but they are really the second, third, and fourth, Professor D’Alton having taken the surface of the cuneiform, which articulates with the fifth metacarpal, for the surface of articulation with the pisiform. The phalanges of the digits belonging to these metacarpal bones, and three of their sesamoid bones, are carefully described and figured. The resemblances of the bones of the forearm with those of the existing Armadillos are pointed out, especial weight being laid upon the extension of the cuneiform round the unciform, and its articulation with what D’Alton supposes to be the fifth meta- carpal ; and certain analogies of the fore foot with that of the mole are indicated. A fragment of the distal end of a leg-bone, the seven tarsal bones, the four outer metatarsal bones ; their digits, except the ungual phalanges ; and some other bones of the hind foot, in a more or less fragmentary state, are described and figured, and atten- tion is drawn to the remarkably short and strong character of the foot. In conclusion B’Alton remarks, “Though, as I have endeavoured to show above, there is a certain agreement between the manus of the fossil animal and that of the Armadillos, yet the foot shows us no greater similarity than may be observed between it and many other five-toed animals. Hence the osteology of the primeval animal does not afford a sufficient confirmation of the view which we derived from the consideration of the carapace, viz. that the bones, together with the fragments of dermal armour. PKOEESSOK HUXLEY ON THE OSTEOLOGY OF THE GENUS GLYPTODON. 35 might have belonged to an animal nearly allied to the Armadillos, or perhaps even to a very large, probably extinct, species of Dasypus. The fossil bones are too few to afford a safe foundation for so decided an opinion respecting the zoological affinities of the animal. A tolerably perfect skeleton is necessary in order to enable us, from the bones alone, to draw a safe conclusion as to the structure pf the remainder of an animal.” Singularly enough, D’ Alton does not mention the Megatherium throughout this paper, which however affords, by implication, an ample demonstration that the bony armour described has nothing to do with that animal*. In 1836, Laurillard, in editing the eighth volume of the second edition of Cuvier’s ‘ Ossemens Fossiles,’ appends the following note to the letter of Don D. Laranaga, quoted above : — “ It is very possible that the Megatherium was, in fact, covered by a scaly cuirass ; but the great fragments which have been found must not be hastily attributed to it ; for the plaster casts sent from London f prove that an Armadillo of gigantic size coexists with the Megatherium on the plains of Buenos Ayres. These characteristic fragments consist of a calcaneum, an astragalus, and a scaphoid, which depart from those of existing Armadillos only in size, and by purely specific differences.” In 1836, then, it was clearly made out that the cuirassed extinct animal of South America is not the Megatherium and is allied to the Armadillos. However, Dr. Buckland, whose Bridgewater Treatise appeared in this year, and who therefore could hardly have been acquainted with the views of D’Alton and of Laurillard, still associated the dermal armour with the Megatherium — supporting his views by an elaborate and inge- nious teleological argument, which, like most reasonings of the kind, appeared highly satisfactory. But, in 1837, all further doubt upon the subject was removed by the dis- coveries of Dr. Lund, who, in that year, despatched to Copenhagen the second of the remarkable series of memoirs in which he reconstructed the ancient Fauna of Brazil J. In this paper Dr. Lund established the genus Hoplopliorus upon the dermal armour and certain bones of an edentate quadruped closely allied to, if not identical with, the “ Dasypus ” of Laranaga. Hoplophorus euphractus , the sole species of the new genus described in the memoir, was estimated by its discoverer to be of the size of an ox, and to have been provided with a carapace most nearly resembling that of Tolypeutes, but of an astonishing thick- ness. The extremities are said to have the general structure of those of the Armadillos, * Thus Muller says in his memoir on the hind foot, cited below, “ In der letzten Abhandlung ist von Herrn D’ Alton bewiesen, dass der Panzer nicht dem Megatherium angehort.” t Vide swpra, p. 32. Mr. Pentland appears to have been led to the same opinion by the examination of these casts in 1835. See Transactions of the Geological Society, vol. vi. ser. 2nd, p. 85, and Mr. Pentlaxd’s letter to M. Aeago in the ‘ Comptes Rendus’ for March 11, 1839. £ “ Blik paa Brasiliens Dyreverden for sidste Jordomvaeltning. Anden Afhandling : Patte dyrene. Lagoa Santa, 16de Novbr. 1837,” published in ‘ Det Kongelige DanskeYidenskabernes Selskabs Naturvidenskabelige og Mathematiske Afhandlingar,’ Ottende Deel, 1841, p. 70. A notice of Lund’s labours, containing the names of his genera, is to be found in the ‘Oversigt over det Kongelige Danske Yidenskabernes Selskabs Fordhandlingar i Aaret 1838/ published by Oksted, the Secretary of the Academy. 36 PROFESSOR HUXLEY ON THE OSTEOLOGY OE THE GENUS GLYPTODON. the feet being short and thick, with remarkably broad and short nails ; so that they must have resembled those of an Elephant, or a Hippopotamus. The skull was sloth-like, and its jugal arch exhibited the structure characteristic of those animals. The teeth were similar to the molars of Ccvpybara, but simple instead of being made up of many plates. Professor Bronn, publishing the .second edition of his 4 Lethsea Geognostica ’ in the spring of 1838, and unacquainted with Lund’s labours, proposed the name of Chlamy- dotherium for the animal to which the carapace described by Weiss and D’Alton belonged, in case the foot should really appertain to it ; and Orycterotherium , in case the foot should belong to a different animal. In March of the same year, it appears that M. Vilardebo, Director of the Museum of Monte Video, and M. Isabelle published conjointly, in Nos. 2551, 2553, and 2555 of a journal, the ‘ Universal,’ an account of an animal which they had discovered on the Pedernal, in the Department of Canelones*. After removing a thin layer of clay, these observers met with a shield formed of pieces of bone separated from one another by a slight interval ; these pieces, 25 to 50 millimetres in diameter, and varying in thickness from 12 to 40 millimetres, were hexagonal: the largest occupied the dorsal region of the carapace, and the smallest its lateral regions. Each polygon presented a central disk (14 to 27 millimetres in diameter), from whence radiated six or eight lines, between which as many quadrangular arese were left. These pieces of bone were symphysially united so as to form a very regular mosaic : the cara- pace appeared to be fringed with conical pieces forming a semicircle of 24 centimetres. The carapace was about 4 metres wide, and was as convex as a cask. The bones dis- covered in it were lumbar vertebrae and pelvic bones. In another place was discovered a femur about 0-57 metre long, with many plates of the carapace, and a tail formed of a single mass of bone (covered nevertheless by pieces soldered together), in the middle of which were widely separated caudal vertebrae. The tail was more than 0-50 metre long, and more than O' 36 metre in diameter at the base. Tire authors discuss the question — to what class do these fossils belong 1 — with much sagacity, and conclude by expressing the opinion that they appertain to a species of Dasypus , which they term I), antiquus, and which they briefly characterize as follows : 44 Cingulis dorsalibus nullis: verticillis caudalibus nullis.” The volume of the Transactions of the Danish Academy, already cited, contains another communication from Dr. Lund, dated Lagoa Santa, September 12, 1838, in which he speaks of the fossils described by D’ Alton, and identifies the animal to which they belonged, generically, with Hoplophorus, though he regards it as a distinct species, and names it Hoplophorus Selloi. Accompanying this paper are sundry figures of parts of the carapace and of bones of the hind foot of Hoplophorus. Dr. Lund returns to the subject in a long letter addressed to M. V. Audouin, dated the 5th of November 1838 (extracts from which are published in the 4 Comptes Rendus ’ for the 15th of April 1839), which contains an enumeration, with brief descriptive notices, of the seventy-five species of fossil Mammalia which this untiring explorer had * See the Bulletin de la Societe Geologique de France, t. xi. p. 159 (1840). PROFESSOR HUXLEY ON THE OSTEOLOG-Y OF THE GENUS GLYPTODON. 37 extracted in the preceding five years from the caverns of Brazil. Among the rest the writer describes : — “ 6°. Hoplophorus , a genus very remarkable for the heavy proportions of its species, for their gigantic size, as well as for the singular manner in which it combines different types of organization ; however, their characters approximate them most nearly to the Sloth family. These strange animals were armed with a cuirass which covered all the upper part of the body, and which was composed of little hexagonal scutes, except in the middle of the body, where the scutes took a quadrate form, and were disposed in innumerable transverse bands. The bones of the trunk, as well as the great bones of the extremities, are also very similar to those of the Tatous, and particularly to those of the Cachicames ; but the bones which compose the feet are so shortened and have their articular faces so flattened, that nothing similar is to be seen in any animal skeleton, and that it is inconceivable how such feet should have been used in digging. The form of the teeth also indicates that these singular animals could feed only on vegetable sub- stances, and it is to be supposed that they grazed after the fashion of the great Pachy- derms. However this may be, the Hoplophorus , of which M. Lund describes two species, present the peculiarity, hitherto regarded as special to the Sloth, of having a descending branch to the zygomatic arch. These two species were as large as an ox. Fragments of the skeletons have already been described by MM. Weiss and D’Alton of Berlin.” — Loc. cit. pp. 572, 573. A summary of Lund’s researches, despatched by him from Lagoa Santa on November 5, 1838, and published in the Ann ales des Sciences Naturelles for 1839, under the title of “ Coup d’ceil sur les especes eteintes de mammiferes de Bresil : extrait de quelques memoires presentes a l’Academie Boyale des Sciences de Copenhague,” gives a sub- stantially similar account of Hoplophorus. The species Hoplophorus Selloi is identified with the cuirassed animal described and figured by Weiss and D’Alton. The sixth volume of the second series of the Transactions of the Geological Society contains an elaborate memoir by Professor Owen* on the bones associated with the dermal armour, figured by Mr. Clift in the memoir already cited ; and on certain teeth, upon which the genus Glyptodon was founded by the same writer, in Sir Woodbine Parish’s work on Buenos Ayres 'j*. Professor Owen considers these remains to be specifically identical with those collected by Sellow, and described by Weiss and D’Alton ; so that if Lund was right in ascribing the same fossils to his genus Hoplophorus, Glyptodon becomes a synonym of the latter. In the memoir under consideration the general form and the minute structure of the * “ Descriptions of a tooth and part of the skeleton of the Glyptodon clavipes, a large quadruped of the eden- tate order, to which belongs the tessellated bony armour described and figured by Mr. Clift in the former volume of the Transactions of the Geological Society, with a consideration of the question whether the Megatherium possessed an analogous dermal armour.” By Richard Owen, Esq., F.G.S., F.R.S. (Read March 23rd, 1839 : an abstract of this paper appeared in No. 62 of the ‘ Proceedings.’) f * Buenos Ayres and the provinces of the Rio de la Plata,’ 1838, p. 178 e. 38 PEOFESSOE HUXLEY ON THE OSTEOLOGY OF THE GENUS GLYPTODON. teeth, the distal end of the humerus, the radius, two phalanges of the fore foot, “ the anchylosed distal extremities of the tibia and fibula, an astragalus, calcaneum, seaphoides, cuboides, external cuneiform bone, the three phalanges of the second toe, and the mid- dle and distal phalanges of the third and fourth toes, with a few sesamoid bones,” all belonging to the left side, are described ; while the tooth and the bones of the leg and foot are figured. Professor Owen considers that the dental characters “ seem to indicate a transition from the Edentata to the pachydermatous Toxodon ,” and sums up his general conclu- sions as to the affinities of Glyptodon thus : — “ It may be concluded, therefore, that the extinct edentate animal to which belongs the fossil tessellated armour described by Weiss, Buckland, and Clift, cannot be called an Armadillo, without making use of an exaggerated expression, and still less a species of Megatherium ; but that it offers the type of a distinct genus, which was much more nearly allied to the Dasypodoid than to the Megatherioid families of Edentata, and most probably connected that order of quadrupeds with the heavy coated Rhinoceros of the Pachydermatous group” (l. c. p. 96). In the same year (1839) Professor D ’Alton proposed for the animal, the remains of which he had originally described, the name of Pacliypus ; so that by this time no fewer than six names had been applied to mammals all of which are certainly closely allied to the Hoplophorus of Lund, whether they are, or are not, generically identical with it, and which may therefore be appropriately termed Hoplophoridce. In 1845 Professor Owen returned to the Glyptodon question, in the ‘Descriptive and illustrated Catalogue of the Fossil Organic Remains of Mammalia, and Aves contained in the Museum of the Royal College of Surgeons of England.’ It is here stated (p. 107) that “those specimens of the present genus which were presented to the College by Sir Woodbine Parish are from a low marshy place, about five feet below the surface, in the bank of a rivulet, near the Rio Matanza, in the Partido of Canuelas, about twenty miles to the south of the city of Buenos Ayres.” The parts thus found associated are not stated, with the exception of the bones of the left hind leg and foot (p. Ill), to have belonged to the same individual. They consist of a molar tooth, part of the left ramus of the lower jaw, a fragment of the humerus, the left radius, a metacarpal bone and two phalanges, the shaft and distal epiphyses of the femur (1), the anchylosed distal ends of the tibia and fibula, and numerous bones of the left hind foot. These had already been described and figured in the Geological Society’s Transactions. As new specimens, there are described and figured an almost, entire carapace of Glyptodon clavipes, from the Pampas of Buenos Ayres, and many dermal bones, all of which are marked “ Purchased,” and appear not to have been accompanied by bones of the endoskeleton. Nos. 551, 552, 554, 555, 556, 557 are fragments of carapace, all presented by Sir W oodbine Parish, and obtained from the locality mentioned above. They are ascribed by Professor Owen to no less than three distinct species, however, PROFESSOR HUXLEY ON THE OSTEOLOGY OF THE GENUS GLYPTODON. 39 viz. Glyptodon clavipes, G. reticulatus, and G. ornatus ; a fourth species, G. tulerculatus, is based upon purchased specimens, from the Pampas of Buenos Ayres, the precise locality of which is not stated. The fact that the dermal ossicles of three species of Glyptodon were found in the same locality as the bones described, and the absence of any evidence demonstrating the association of the ossicles ascribed to G. clavipes, rather than those attributed to the other species, with the bones, throws, it will be observed, some doubt upon the certainty of that ascription, and opens the question whether the bones really belonged to one form of carapace or to another. Of the Plates which illustrate the c Catalogue,’ the first contains a side view, partly restored, of the Glyptodon clavipes ; the second, views of the carapace and tail ; the third, of the skull ; the fourth and fifth, of parts of the carapace ; and the description of the Plates comprises accounts of the structure of the skull and of the tail, parts which had not been received until after the printing of the body of the catalogue. In what locality the skull and the tail were obtained, and upon what evidence they are ascribed to the particular species, G. clavipes , is not stated. The lower jaw and the defensive bony covering of the skull in plate 1 “ are restored on the authority of an original sketch of an entire specimen of this species of Glyptodon transmitted to Sir Woodbine Parish from Buenos Ayres.” The bones of the fore foot are given in outline after D’Alton. On the 8th of June, 1846, the late Johannes Muller read a short paper to the Ber- lin Academy upon the bones of the leg and hind foot described by D’Alton, which had been worked out and mounted by the help of Professor Owen’s memoir. This paper, accompanied by an excellent plate, was published in 1849*. The number of the ‘ Comptes Bendus ’ for August 28, 1855, contains a “ Description d’un nouveau genre d’Edente fossile renfermant plusieurs especes voisines des Glypto- dons, et classification methodique de treize especes appartenant a ces deux genres,” by M. L. Nodot, Director of the Museum of Natural History at Dijon; and this essay, enlarged and illustrated with plates, appeared two years later in the 4 Memoires de l’Academie Imperiale de Dijon,’ Deuxieme Serie, tom. v. 1857f. M. Nodot, in his introductory remarks, states that Vice-Admiral Dupetit brought back from Monte Video, in 1846, a great number of fossil bones which had been collected by Dr. Numez on the banks of the river Lujan, and were given to the Vice-Admiral by the orders of the Dictator Rosas. Admiral Dupetit presented most of these remains to the Museum of the Jardin des Plantes in Paris ; but dying before * “ Bemerkungen fiber die Fussknoehen des fossilen Giirtelthiers ( Glyptodon clavipes, Ow.),” Abhand- lungen d. Konigl. Akad. d. Wissenschaften, 1849. t Under the title “ Description d’un nouveau genre d’Edente fossile renfermant plusieurs especes voisines du Glyptodon, suivie d’une nouvelle methode de classification applicable a toute l’histoire naturelle et speciale- ment a ces animaux. Avec un atlas de douze planches lithographiees.” MDCCCLXV. H 40 PROFESSOR HUXLEY ON THE OSTEOLOGY- OF THE GENUS GLYPTODON. he had disposed of all, his widow bestowed two boxes full of detached dermal ossicles on the Dijon Collection. Out of these, by dint of four months’ constant toil, M. Nodot reconstructed the carapace. Subsequent investigations in the store-rooms of the Jardin des Plantes revealed almost the whole of the tail, and many important parts of the skeleton, of what M. Nodot believed to be the same individual animal, mixed up, however, with fragments of Mylo- don, Megatherium , and Scelidotherium. Besides these, M. Nodot found the tolerably complete extremity of the tail of another individual of the same genus in the Geological Gallery, and the right half of a lower jaw with the teeth, which he judged to belong to this individual. The bones which M. Nodot, guided as it would seem chiefly by their colour, identi- fies as belonging to the same individual with the carapace, are, “ the lateral and poste- rior part of the cranium, the occiput, the meatus auditorius, the zygomatic arch and its long apophysis, three alveoli, and the sagittal crest ; the atlas, the axis, the vertebra of the fifth ring of the tail ; the two femora entire ; the tibiae and fibulae anchylosed ; the calcanea; the astragali ; the other tarsal bones ; the left metatarsus ; the three external toes of the left hind foot ; the left radius ; the ungual phalanx of one of the digits of the fore foot ; and the ungual phalanx of an internal toe of the hind foot.” The cara- pace and the tail are fully described by M. Nodot, who considers their peculiarities sufficient to justify him in establishing for these remains the new genus Schistopleuron. How far he was justified in so doing is a point which must be discussed at the end of this memoir ; but there can be no question that “ Schistopleuron ” is one of the IIoplo- phoridce, closely allied to Glyptodon clavipes ; and hence M. Nodot’s descriptions of the mandible, sternum, and femur constitute substantial additions to our knowledge of the organization of that family. The mandible is unlike the sketch furnished to Professor Owen and adopted by him, but very like that which will be described below. The first piece of the sternum and the first two ribs were so anchylosed together as to leave no trace of their primitive sepa- ration. On the 14th of November, 1862, 1 presented to this Society a “ Description of a new Specimen of Glyptodon, recently acquired by the Royal College of Surgeons of England,” which was published in the fifty-third Number of the ‘ Proceedings of the Royal Society.’ The remains of the specimen, described briefly in this preliminary notice and, in full, in the present memoir, were presented to the Royal College of Surgeons by Senor Don Maximo Terrero, having been discovered in 1860 on the estate of his brother, Senor Don Juan N. Terrero, which is situated on the banks of the river Salado, in the district of Monte, in the Province of Buenos Ayres, and about eighty miles due south of the city of that name. No portions of any other animal, nor any duplicate bones, have been discovered among the osseous relics the description of which has been entrusted to me by the authorities PEOEESSOE HUXLEY ON THE OSTEOLOG-Y OF THE GENUS GLYPTODON. 41 of the College of Surgeons — a circumstance which justifies the belief that they all belonged to one and the same animal, and gives them a peculiar value, the more especially as there can be little doubt of the specific identity of the new specimen with the animal to which the skull ascribed by Professor Owen to Glyptodon clavipes belongs. I have thus been enabled to add to what was already known of Glyptodon clavipes, descriptions of the most essential peculiarities of the fore part of the skull, the entire palate, the mandible, the greater part of the spinal column, the pelvis, and the com- plete fore and hind feet, and to announce the existence, in this animal, of a conforma- tion of the spinal column hitherto unknown in the Mammalian, and, indeed, in the Vertebrate series — the last cervical and two anterior dorsal vertebrae being anchylosed together into a single osseous mass articulated by ginglymi with the rest of the vertebral column. As another very remarkable peculiarity of this genus, I have pointed out the extraordinary characters of the pelvis, and the fact that the cuneiform bone in the carpus articulates with two metacarpal bones, the fourth and fifth, while the unciform does not articulate with the fifth at all. Since the appearance of my paper in the 6 Proceedings of the Royal Society,’ and in- deed not until the months of May and June 1863, M. Serres, apparently unacquainted with what had been done in these matters, has redescribed the joint between the second and third dorsal vertebrae, though he appears to be still unaware of the existence of the 4 trivertebral bone.’ In addition, M. Serres makes known the interesting circumstance, that the posterior edge of the manubrium of the sternum, anchylosed (as M. Nodot had pointed out, though M. Serres does not refer to him) with the first pair of ribs, pre- sents two concave articular facets, by which it was united with the rest of the sternum, which must have presented two convex surfaces adapted to the foregoing in order to allow of a movement of flexion. M. Serres is of opinion that this mechanism is intended to allow of the retraction of the head : “II est done vraisemblable qu’au moment du danger, peut-etre meme que dans le repos ou le sommeil, le Glyptodon flechissait le col pour ramener la tete sous la coupole de la carapace”*. In his second communication to the Academy, M. Serres still speaks of the “anchy- losis of the first two dorsal vertebrae ” onlyf . Professor Burmeister, Director of the Museum at Buenos Ayres, has been good enough to communicate to me a letter, addressed by him to the Editor of the 4 Nacion Arjentina’ on the 5th July, 1863, commenting upon a lecture upon the Glyptodon which I delivered before the President and Council of the Royal College of Surgeons, which was published in the Medical Times and Gazette for the 28th of February and * “Note sur deux articulations ginglymo'ides nouvelles existant chez le Glyptodon, la premiere entre la deuxieme et la troisieme vertebre dorsale, la seconde entre la premiere et la deuxieme piece du sternum. Par M. Sebkes” (Comptes Eendus, May 11, 1863). t “ Deuxieme Note sur le developpement de 1’ articulation vertebro-stemale du Glyptodon, et les mouvemens de flexion et d’ extension de la tete chez cet animal fossile. Par M. Sekbes” (Comptes Eendus, June 1, 1863). H 2 42 PROFESSOR HUXLEY ON THE OSTEOLOGY OF THE GENUS GLYPTODON. 7th of March, 1863, and which contains the substance of the statements previously- published in the ‘Proceedings’ of this Society. Professor Bukmeister affirms that the skeleton of the Glyptodon in the Museum of Buenos Ayres is much more perfect than that in the lloyal College of Surgeons ; that it has the seven cervical vertebrae complete ; and that the five middle cervical vertebrae are anchylosed together, while the seventh is very delicate and fragile. Under these circumstances, it would appear that Professor Burmeister considers the trivertebral bone (my description of which he confirms) to be composed of the three anterior dorsal vertebrae. Professor Burmeister is further of opinion that the peculiar mechanism of the joint formed by the trivertebral bone with the rest of the spinal column has not that respi- ratory function which I have ascribed to it; but, with M. Serres, he thinks that its object is to allow of the application of the cephalic shield to the anterior aperture of the shield of the body. Professor Burmeister goes on to remark — “ As little do I agree with Mr. Huxley as to the immobility of the ribs, which are wholly wanting in the London skeleton. The skeleton of the Museum of Buenos Ayres has nine ribs, three of which being complete, prove that they possess a certain mobility, moving downwards and backwards on their articulations with the spinal column, as in other Mammalia, but without doubt in a manner somewhat different from the ordinary way.” I am at a loss to divine on what grounds Professor Burmeister ascribes to me the opinion that the ribs are immoveable, and why he affirms that they are wholly wanting- in the London skeleton. What I have stated is, that the first rib is immoveable ; and so far from the ribs being wholly wanting, I have particularly mentioned their presence *, and have alluded to the characters of the first *f\ Professor Burmeister adds that I am in error in supposing that the dorso-lumbar vertebrae were immoveably united. I believe, however, from Professor Burmeister’s own words, that my description is substantially accurate. These words are : — “ There exists a moveable place between the dorsal and the lumbar vertebrae, though the mobility is not so complete as that of the three first anchylosed vertebrae upon the following ones. In this part, the skeleton of Buenos Ayres presents a complete column, formed by eleven vertebrae incorporated into a solid piece, of a very peculiar form, with three crests in the upper part, the two lateral of which bear the ribs in articular exca- vations. The total number of dorsal vertebrae and of ribs is therefore fourteen. Then follow on these the lumbar vertebrae, all anchylosed together and immoveably united with the sacrum.” I do not venture to doubt the accuracy of Professor Burmeister’s description of the specimen under his own eyes ; but nevertheless, as will be seen by-and-by, it is also true that the account I have given of the Glyptodon in the College Museum is quite accu- rate. And indeed, as Professor Burmeister admits that all the dorsal and all the * Proceedings of the Royal Society, Z. c. p. 317. t Ibid. p. 319. PROFESSOR HUXLEY ON THE OSTEOLOGY OP THE GENUS GLYPTODON. 43 lumbar vertebrae respectively were anchylosed together, with only an imperfect mobi- lity at the junction of the two solid masses, I do not see how, in any important respect, his view of the matter differs from mine. The last criticism which Professor Burmeister offers, refers to what he terms my error in ascribing five toes to the fore foot, when, as he affirms, it possesses only four. Pro- fessor Burmeister states that I have figured five toes to the foot of the Glyptodon in the lecture already referred to ; but he is mistaken ; only four toes are there represented, numbered, according to the digits of the typical foot which they represent, 2, 3, 4, 5. In the ‘ Proceedings’ (p. 325) I have expressly stated — “The trapezium possesses only a very small double articular facet on its palmar face. If this gave support to a metacarpal, it must have been very small ; and as at present neither it nor any of the hallucal phalanges have been discovered, it is possible the pollex may have been altogether rudimentary. In any case the pollex must have been so much smaller and more slender in proportion than that of Dasypus, that the animal must have had a practically tetradactyle fore foot.” The errors, therefore, to which Professor Burmeister adverts, appear to me to arise to a great extent from his not having rightly comprehended my statements ; and in part, it may be, from our having to deal with different objects. Part II. — Description of the Skeleton of Glyptodon clavipes, Owen ( Hoplophorus Selloi, Lund 1). The materials which have been available for the following description of the osteology of Glyptodon are, in the first place, the skeleton referred to in the previous section as having been presented by Senor Terrero to the Royal College of Surgeons; secondly, the detached parts which have been already described by Professor Owen, and are now contained in the Museum of the Royal College of Surgeons ; thirdly, some fragmentary specimens in the British Museum ; and fourthly, photographs of a skeleton of Glyptodon in the Museum of Turin. The two latter sources of information, however, are of altogether secondary importance, and will be adduced merely in confirmation of the results obtained from the study of the two former series of materials, — in treating of which, I shall speak of the fragments of Glyptodon clavipes described by Professor Owen as the “ type specimen,” and of the skeleton presented by Senor Terrero as the “ new specimen.” § 1. Description of the Skull of Glyptodon clavipes. In the new specimen * the anterior part of the skull, from a line drawn transversely, immediately behind the zygomatic processes, to the anterior end of the snout, is in a remarkably good state of preservation — the boundaries of the anterior nares, the antero- lateral parts of the maxillary bones, the nasal, and the fore part of the frontal, bones being quite uninjured. Behind the imaginary transverse line in question this cranium * Plate IY, figs. 1 & 3, Plate V., and Plate YI. figs. 1, 2, 4, & 5. 44 PROFESSOR HUXLEY ON THE OSTEOLOGY OF THE GENUS GLYPTODON. is very imperfect — the entire roof and sides, and the greater part of the base of the skull being absent, while a small portion only of the sphenoidal region is preserved. Of the facial bones, those entering into the palate are preserved almost in their entirety, and one ramns of the lower jaw is nearly complete. This skull therefore supplies almost all those parts which were wanting in the cranium of the type speci- men, in which the whole of the roof of the skull, from the nasal bones to the supra- occipital inclusive, most of the exoccipital, alisphenoidal, and orbitosphenoidal regions of the lateral walls, and of the basioccipital, basisphenoidal, and presphenoidal parts of the base, together with the temporal bones, are in good condition, while the premax- illary, maxillary, and palatine bones, with the mandible, are absent. In order to give a tolerably complete view of the structure of the skull, I shall, in the first place, describe that of the new specimen ; I shall next proceed to a comparison of the parts common to this fossil and the skull of the type specimen, in order to demonstrate the specific identity of the two ; and then I shall endeavour to supply what is wanting in the new specimen by information derived from the study of the type. The skull of the new specimen of Glyptodon clavipes. — The anterior nares have a trapezoidal form, the upper of the two parallel sides of the trapezoid being nearly three times as long as the lower, so that the two lateral boundaries converge from the roof towards the base of the nares (Plate VI. fig. 1). The upper boundary of the anterior nares is formed by the anterior edges of the thick nasal bones, which are bevelled obliquely from below upwards, and so rounded off late- rally that the contour of the two forms a large arc of a circle, the chord of which measures 3-4 inches (Plate IV. fig. 1). The upper surface of each nasal bone is rough and perforated by many vascular foramina, which open forward ; and the two nasal bones are separated by a suture, which can be traced backwards in the middle line for 2'2 inches, and then comes to an abrupt termination. I presume that the extent of this suture indicates the distance to which the nasal bones reach backwards ; but there are no traces of the nasofrontal, or nasomaxillary sutures. The middle of the under surface of each nasal bone presents a strong, rounded, longitudinal ridge, on each side of which there is an equally distinct concavity, and the apposed slightly thickened inner edges of the two nasal bones form a third, less marked, median ridge. The expanded upper edge of the perpendicular plate of the ethmoid embraces this middle ridge, while the nasal turbinal bones are continuous with the ridges on each side of it (Plate VI. fig. 1). A well-marked notch, or sinuosity, separates the upper from the lateral contour of the anterior nares ; and, about an inch below this, the inner surface of the outer wall of the nostril exhibits a rounded elevation or thickening. Still more inferiorly, the wall of the nasal cavity is somewhat excavated, so as to present a thin anterior edge, which passes into the trough-like lower boundary, constituted by the palatine portions of the prsemaxillse. These are separated throughout their whole length in the middle line (a distance of rather more than an inch) by a fissure less than one-tenth of an inch in diameter posteriorly, but twice as wide in front, the prsemaxillse becoming more PEOFESSOE HUXLEY ON THE OSTEOLOG-Y OF THE GENUS GLYPTODON. 45 distant by the divarication of their anterior and internal angles. The thick and rough anterior edges of the preemaxillee diverge obliquely from one another, both forwards and outwards and upwards and outwards, at a very obtuse angle, the interval between their anterior and external terminations amounting to 1-5 inch (Plate IV. fig. 3). Viewed laterally, the anterior ends of the nasal bones are seen to project about half an inch beyond the upper part of the lateral boundary of the nares, which slopes upwards and backwards with a slight forward concavity from the palatine portion of the preemaxilla (Plate V. fig. 1). The nasal cavity is divided, longitudinally, by a very strong osseous septum, which extends to the posterior end of the premaxillary fissure below, and to within 0-4 inch of the anterior contour of the nasal bones above (Plate VI. fig. 1). This septum terminates, in front and below, in a thin jagged edge; but above, it expands into a broad plate T2 inch wide, presenting a deep and broad notch above, into which, as I have previously stated, the conjoined median edges of the nasal bones are received. The septum is about 2'6 inches high in front; and of this height 2-2 inches, or about five-sixths, is formed by the perpendicular plate of the ethmoid, while the rest belongs to the vomer (Vo.). The ethmoidal plate is thin in front, thicker in the middle, and thin again posteriorly. The lower half is somewhat excavated on each side, from above downwards ; it ends in an inferior edge, or rather surface, 0-7 inch in diameter, anchylosed with the upper edge of the vomer, which has, in front, a corresponding thickness. The floor of the anterior part of the nasal cavity (i. e. as far as the level of the fourth alveolus) is concave from side to side, and convex from before backwards, its convexity corresponding with, but being much more strongly marked than, the concavity of the arched roof of the palate. At about 2 inches from the anterior boundary, a sharp longitudinal ridge commences upon the floor of each division of the nasal cavity, and extends backwards, for a distance of about 1| inch, to the summit of the arch formed by that floor (Plate VI. fig. 1, a). Each ridge has a sloping convex external face, and a perpendicular concave inner face, 0-2 inch high. Between the latter and the side of the vomer, which is excavated for a corresponding distance from above downwards, lies a canal, a quarter of an inch wide, and open above and at its ends. The- floor of each nasal chamber rises gradually into its lateral wall ; and upon this, about three-fourths of an inch from the floor, appears a ridge which, at about an inch from the antero-lateral margin of the nostril (or just above the anterior end of the ridge on its floor), passes backwards into the commencement of the inferior spongy bone (Plate VI. fig. 1, b ). The root of attachment of this bone to the maxilla is, as usual, a narrow and thin, though long, bony plate, which on its free, or inner, side is continued into two scroll-like lamellae, an upper and a lower. The upper scroll comes much further forward than the lower, and is a stout plate of bone, slightly concave inwards and convex outwards. In front, it ends in a thin free edge. Superiorly, its margin is folded over outwards, and becomes anchylosed with the lateral wall of the nasal chamber. The inferior lamella commences about an inch behind the superior one. It is thick, 46 PROFESSOR HUXLEY ON THE OSTEOLOGY OF THE GENUS GLYPTODON. convex inwards and concave outwards, and its inferior edge becomes much thickened as it curves outwards. It is attached to the maxilla by an anterior and superior thin, and a posterior and inferior, much thicker, plate of bone. Three passages, consequently, lie between the lateral walls of the nasal chamber and the ‘ scrolls ’ of the inferior turbinal, — an upper, long, narrow, and flattened from side to side ; a middle, reniform in section ; and an inferior, rounded in contour. The ridges upon the under surfaces of the nasal bones are continued, as I have stated above, into two thick plates of lamellated bone (Plate VI. fig. 1, c), which increase in depth from before backwards and pass into what are, probably, the superior ethmoidal turbinals. Their inner surfaces are flattened and parallel with the sides of the perpendicular plate of the ethmoid. Their outer surfaces, irregularly concave, are separated by but a narrow interval from the concave faces of the superior scrolls of the inferior turbinal bone. The posterior view of this fragmentary skull (Plate VI. fig. 2) affords a further insight into the arrangement of the bones which contribute to the formation of the olfactory chambers. The aspect presented is that of a transverse section taken just in front of the anterior end of the cranial cavity. The comparatively thin posterior part of the lamina jperpendicularis of the ethmoid (Fth) is seen abutting, above, against the frontal bones (Fr), and, below, becoming connected with the vomer (Vo), the posterior nearly straight free edge of which bone ends on the floor of the nostrils, at the level of the posterior margin of the third molar tooth, and thence slopes obliquely upwards and backwards. The ethmovomerine plate, however, is not free from all lateral' connexion with the tur- binal bones, as is commonly the case ; but a thin plate of bone, convex forwards and concave backwards, passes, on each side, from the vomer and the lamina perpendicularis to the lateral masses of the ethmoid. The inner surfaces of these are marked by broad flattened grooves, directed forwards and downwards, and separated by sharp ridges, which, in the recent state, were probably produced into delicate plates of bone. The lower portion of the lateral mass of the ethmoid, which represents the middle turbinal, is continuous with the inferior turbinal. The upper portion, representing the superior turbinal, is similarly continuous with the nasal turbinal. The superior tur- binal of each side forms the floor of a considerable cavity (Plate VI. fig. 2), which is walled in, externally and above, by the frontal bone, and represents a frontal sinus. A rounded dome (a) of bone projects backwards from the anterior wall of this cavity, which appears to communicate with the nasal fossse only by a few foramina, situated around the margins of the dome. The palate (Plate IV. fig. 3) is singularly narrow, seeing that its length, measured in a straight line, is about 9^ inches, while its width, between the outer edges of the alveoli, nowhere exceeds 3 inches. The longitudinal contour of the palate is concave anteriorly, convex posteriorly (Plate V. fig. 1). The crown of the arch of the anterior concave portion is opposite the hinder margin of the third alveolus ; from thence the roof of the palate slopes, downwards and forwards, to the free premaxillary edge. From the same point it slopes, downwards and backwards, to the level of the hinder margin PROFESSOR HUXLEY ON THE OSTEOLOGY OE THE GENUS GLYPTODON. 47 of the fifth alveolus, while behind the sixth it ascends, somewhat abruptly, to its pos- terior termination. Throughout the posterior two-thirds of its length, the palate is slightly and evenly concave from side to side ; but, from the third alveolus forwards, its middle part rises to form a median convexity, which ends by a rough, abruptly truncated ridge (Plate IV. fig. 3, a ), behind the premaxillary fissure. It forms, in fact, the posterior boundary of a transverse fissure ending in a notch, or short canal, at each extremity, which represents the anterior palatine foramen, and which, taken together with the intermaxillary fissure, simulates very closely the form of a T. A deep groove (&) separates the raised part of the palate from the alveolar margin, and ends, behind, in a canal which burrows into the substance of the bone opposite the anterior edge of the third tooth on both sides. On the left side, however, the hinder part of the groove is bridged over by a bar of bone. Large foramina are situated, along a line continuing the groove, opposite the third and fourth alveoli ; but no such apertures appear in the posterior part of the palate until quite its hinder extremity is reached, when, on each side, two crescentic fossae (Plate IV. fig. 3, c), wider in front than behind, lie on the inner side of the last alveolus, and appear to separate the palatine from the maxillary bones. They end caecally above. The bony palate exhibits no distinct sutures, except a trace of a maxillary suture behind the anterior palatine foramen, and of a palatine suture, which widens behind into a cleft, separating the arcuated, divergent inner and posterior boundaries of the palatine bones. The free surfaces of the bony masses which bound the palate, poste- riorly, are so smooth and unbroken, that I suspect the pterygoid bones must be repre- sented in them. As the palate presents very nearly the same width throughout, while the roof-bones of the skull are always much wider than it, it follows that any vertical section of the skull, perpendicular to its long axis, in the palatine region, would exhibit a trapezoidal form, like that of the anterior nares — the predominance of the upper side over the lower being still more marked. But in the antorbital region the roots of the zygomatic processes are so large, and stand out so much from the sides of the head, that the skull, viewed in front, looks almost like a cube, with its lower face produced forwards and downwards into a truncated wedge (Plate VI. fig. 1). The only trace of a suture visible upon any part of the sides of the facial wedge is an almost obliterated one (Plate V. fig. 1, a), which runs from a slight notch, opposite the level of the anterior palatine foramen and in front of the first alveolus, upwards and slightly backwards, and marks off the ascending process of the prsemaxilla from the maxilla. This ascending process, very narrow in the middle, widens above and joins the nasal bone, so that the circumference of the anterior nares is completed by the prsemaxillse and nasal bones only. Opposite the second and third alveoli, the maxillary bone, as I have stated; above, widens out and expands into the root of a stout zygomatic arch, whence a process, nearly 6 inches long by 2 inches wide, passes directly downwards. The process is much flattened from before backwards (Plate VI. fig. 1), and is arched from above downwards (Plate V. mdccclxv. i 48 PROFESSOR HUXLEY ON THE OSTEOLOGY OF THE GENUS GLYPTODON. fig. 1), so as to be convex in front and concave behind. Its inner edge is thick and rounded, except towards its termination, where it presents some slight irregularities or cligitations. The outer edge is comparatively thin and rugose ; it is bevelled off inte- riorly, and more obliquely on the right side than on the left. The inner part of the front face of the process looks almost directly forwards, and is very smooth ; but the outer part of that face looks outwards more than forwards, and is rugose (Plate YI. fig. 1). The hinder, concave face of the process (Plate VI. fig. 2) is divided by an oblique ridge (b), which passes from its superior and external to its inferior and internal angle into two areee — an inner, smooth, and an outer, rough and tuberculated. The superior and external part of the process, where it was doubtless continued into the zygoma, is evidently fractured. The root of the zygoma is perforated near its origin by a large, oval, infraorbital canal, the lower edge of which is rather more than an inch distant from the lower margin of the root of the zygoma. The canal is short, and is directed forwards and outwards. The lachrymal foramen is a round aperture, placed upon the anterior edge of the orbit, T6 inch above the infraorbital canal (Plate V. fig. 1, b). The internal walls of eight alveoli, on each side, are preserved. The external walls ture to be 0-450 between 46° and 19°; Regnault § found it between 71° and 21° to be 0-436. These numbers, obtained with different preparations, are not indeed com- parable for a decision of the question just discussed, but they render improbable a com siderable increase in the specific heat of benzole with the temperature. What I more especially lay weight upon is this : the specific heats of solids which I have determined at various temperatures, by their agreement with the numbers previously found by others, do not indicate any influence of a change of specific heat of naphtha with the temperature. 30. My stock of the naphtha, discussed in § 27, was used before I had investigated all the solid substances, for which a determination of the specific heat appeared necessary. Another quantity of the same coal-tar naphtha was subjected to the same treatment as indicated there, and the portion passing over between 105° and 120° used for the remainder of the experiments. To ascertain the specific heat of this naphtha B, I made the four following series of experiments : — I. — Experiments with Glass 1. Temperature of the Air 18°-l-18°-3. T. T'. i. t. M. /• X. sp. H. O O 0 0 grms. grms. g™. 51-5 19-6 9-33 17-22 26-96 2-70 0-651 0-419 52-7 19-9 19-64 17-49 26-95 59 55 0-413 50-5 19-8 19-54 17-51 26-99 0-420 49-9 20-0 19-73 17-75 26-995 2-695 || 59 0-422 Mean . . . 0-418 * Relation des experiences .... pour determiner les lois et les donnees physiques necessaires au calcul des machines a feu, vol. ii. p. 262 (1862). t Ann. de Chim. et de Phys. [3] vol. ix. pp. 336 & 349. £ Poggendorff’s ‘ Annalen,’ vol. lxxv. p. 107. § Relation, etc vol. ii. p. 283. || After drying the stopper. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 103 II. — Experiments with Glass 3. Temperature of the Air 18°T-18°-3. T. T'. t\ t. M. /. X. sp. H. 51-4 19-7 19-36 17-32 grins. 26-94 grms. 3-085 grm. 0-453 0-415 51-5 19 9 19-63 17-56 26-965 55 0-426 49-1 19-9 19-61 17-73 26-955 55 « 0-416 50-5 20-1 19-82 17-86 . 26-98 3*08 * 0-418 Mean • - - 0-419 III.- —Experiments with Glass 1. Temperature of the Air 17°-8-18°-3. T. T'. t'. t. M. /• X. sp. H. 52-2 19-8 19-49 17-27 grms. 26-97 grms. 2-80 grm. 0-651 0-427 50-6 20-0 19-73 17-64 26-96 59 „ 0-425 51-2 20-2 19-92 17 82 26-98 55 0-420 51-3 20-2 19-86 17-76 26-99 95 ?? 0-418 50-4 20-2 19-86 17-85 26-95 2-785 * 55 0-410 Mean 0-420 IV. — Experiments with Glass 3. Temperature of the Air 18° ■4. . T. T'. t'. t. M. /• X. sp. H. 50-2 19-7 19-43 17-33 grms. 26-96 grms. 3-31 grm. 0-453 0-424 50-1 20-1 19-77 17-66 26-99 55 95 0-416 52-5 20-2 19-87 17-65 26-96 55 59 0-423 50-1 20-1 19-83 17-82 26-95 55 55 0-409 51-4 20-2 19-93 17-82 26-97 3-29 * 55 0-417 Mean 0-418 The average of the means of these four series of experiments, 0-418, 0-419, 0*420, 0-418, gives 0-419 for the specific heat of coal-tar naphtha B between 20° and 50°. In the preceding method of experiment, whether water or naphtha of the kind described is contained in the vessel, a temperature much higher than 50° cannot be employed; for otherwise the quantity of liquid evaporating and condensing on the stopper becomes far too considerable. Perhaps with hydrocarbons of higher boiling- points higher temperatures might be ventured upon: I have no experiments on this subject. PART III.— DETERMINATION OF THE SPECIFIC HEAT OF INDIVIDUAL SOLID SUBSTANCES. 31. By the method whose principle and mode of execution have been discussed in the preceding, I have determined the specific heat of a large number of solid substances. I * After drying the stopper. MDCCCLXV. Q 104 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. should have liked to include a still larger number of bodies in my investigations ; but a limit was put by the straining of the eyes from constant reading of finely divided scales, and by the injurious action which the long-continued working with coal-tar naphtha produces. My crystallographic collection furnished me with much material for investigating the specific heat of both naturally occurring and artificially prepared substances, but for much more I have to thank others. By far the greater part of the chemical prepara- tions investigated ! obtained from the Laboratory of the University of Giessen, through the kindness of the Director, Professor Will, and of the assistants, Professor Engelbach, to whom my thanks are especially due, Drs. Korner and Dehn. Professor Wohler, of Gottingen, placed a number of chemical preparations at my disposal. Professor Bunsen, of Heidelberg, has helped me to the investigation of some rubidium-com- pounds. Platinum and iridium I have been furnished with by M. Her^eus, the pro- prietor of the well-known platinum-manufactory in Hanau. I have had a very large number of minerals from the mineral collection of the University of Giessen, through the kindness of the Director, Professor Knop; and to obtain the necessary quantity of dioptase, Professors Blum of Heidelberg, and Dunker of Marburg, have contributed. 32. The signification of the letters in the statement of the following experiments and their calculation is clear from § 17 ; in reference to the value of the numbers for M, compare § 21, for x § 22, for T' § 23, for y § 27 and § 30. It would require too much space always to give the comparison of my results with those of other observers. I can only do this in individual cases where there are con- siderable differences and their discussion is of importance. For other substances, where there are recent observations by trustworthy observers, the Tables in § 82 to § 89 give data for comparison. 33. Sulphur: pieces of transparent (rhombic) crystals from Girgenti. I made three series of experiments with this substance. I.— Experiments with Water. Glass 1. Temperature of the Air 13°-2. T. O T'. O t'. o t. M. grms. m. grms. /• grm. y* sc. grm. sp. H. 45-8 15-5 15-24 11-74 26-95 4-16 1-765 1-000 0-651 0-168 46*0 16-2 15-93 12-52 26-935 55 55 55 55 0-160 45-2 16-0 15-73 12-42 26-945 55 55 55 0-153 45-8 16-4 16-05 12-74 26-96 55 1-75* 55 Mean 55 0-153 0-159 * After drying the stopper : compare § 25. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 105 II. — Experiments with Water. Glass 2. Temperature of the Air 13°*2. T. T'. t'. t. M. m. /• y- X. sp. H. O O 0 0 grins. grms. grms. grin. 45*8 16*4 16*07 12*36 26*96 4*815 2*09 1*000 0*487 0*171 47*3 16*6 16*33 12*46 26*95 33 55 5? 33 0*170 44*1 16*5 16*15 12*74 26*925 33 99 55 33 0*156 45*1 16*6 16*28 12*77 26*96 33 2*07* „ Mean 33 0*159 0*164 Both these series of determinations are from the time when I first worked at this subject. Towards the end, when I had acquired tolerable readiness, I made a third series, which agreed very closely with the results previously obtained. III. — -Experiments with Water. Glass 3. Temperature of the Air 17°*2. T. T. o t'. 0 t. o M. grms. m. grms. /• grms. y- CC. grm. sp. H. 43*7 19*1 18*83 15*79 26*99 4*92 2*065 1*000 0*453 0*166 43*5 19*1 18*84 15*84 26*97 33 33 33 33 0*162 43*3 19*2 18*92 15*92 26*94 33 33 33 0*170 43*1 19*2 18*87 15*93 26*98 33 2*05 * 33 Mean 33 0*166 0*166 Taking the mean of the means obtained in the three series of experiments, 0T59, 0T64, 0T66, we obtain 0T63 as the specific heat of rhombic sulphur between 17° and 45°. By the method of cooling, Dulong and Petit found the specific heat of sulphur at the mean temperature to be 0T88 ; Neumann found 0*209 by the method of mixture; for sulphur which had been purified by distillation, fused and cast in rolls, Begnault found f the specific heat between 14° and 98° to be 0*2026. In these expe- riments a development of heat depending on a change from amorphous sulphur into rhombic-crystallized appears to have cooperated, and to have caused the circumstance observed by Begnault, that after immersing the heated sulphur in the water of the calorimeter, the maximum temperature was only set up after an unusually long time. Sulphur which has solidified after being melted, usually contains an admixture of amorphous sulphur, the greater the more the melting-point has been exceeded, which at the ordinary temperature passes slowly, at 100° more rapidly, into crystallized, accom- panied by disengagement of heat. The transformation of the sulphur set up by the heating, and continued in the water of the calorimeter, brought about this slow appear- ance of the maximum temperature, and made the specific heat appear too great ; for Begnault’s subsequent determinations J, also made between 97° and 99° and the mean temperature, gave it considerably less: 0*1844 for freshly melted sulphur (in which * After drying the stopper. t Ann. de China. et de Phys. [2] vol. lxxiii. p. 50. Ibid. [3] vol. ix. pp. 326 & 344. Q 2 106 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. superfusion had been avoided P) ; 0-1803 for sulphur which had been melted two months ; 0*1764 for what had been melted two years (and which had then given 0-2026) ; 0-1796 for sulphur of natural occurrence. The difference between the latter result and my own doubtless depends, partially at least, on the fact that Regnault’s determination was made between 14° and 99° (the latter of which temperatures is very near the melting- point of rhombic sulphur) ; mine was made between 17° and 45° *. Tellurium : crystalline pieces f . Experiments with Naphtha A. Glass 3. Temperature of the Air 18 °*6-19°v T. T'. t'. t. M. m. /• y- ■ X. sp. H. o o o o grms. grms. grm. grm. 51-8 20-4 20-07 17-96 26-93 10-80 1-93 0-431 0-453 0-0486 51-3 20-3 20-02 17-93 26-98 35 33 33 0-0495 51-5 20-7 20-36 18-33 26-93 33 33 „ 0-0454 51-0 20-7 20-43 18-43 26-955 „ 1-91$ 33 0-0466 Mean 0-0475 34. Boron. — I have made some experiments with this substance, which have some interest for the question whether this body has essentially different specific heats in its different modifications ; but the results are not very trustworthy, owing to the spongy nature of the amorphous boron and the doubtful purity of the crystallized variety. The amorphous Boron § which I investigated was pressed in small bars, and had stood several days in vacuo over sulphuric acid. Experiments with Naphtha A. Glass 1. Temperature of the Air 17o"0-17o-2. T. o T'. o o t. o M. grms. m. grm. /• grms. y- X . grm. sp. H. 49-0 18-7 18-73 16-36 26-955 1-52 2-515 0-431 0-651 0-246 48-1 18-6 18-55 16-23 26-965 99 99 99 99 0-254 48-0 18-6 18-64 16-33 26-95 99 99 99 99 0-252 47-9 18-7 18-72 16-42 26-95 99 2*49 J 99 Mean 99 0-262 0-254 Even if the results of the individual experiments agree tolerably with each other they are not very trustworthy ; for the quantity of boron (only 1^ grm.) is very small, and the amount of heat due to the boron is a very small part of the total (comp. § 19). Yet I do not consider the result of the above series of experiments (that between 18° and 48° the specific heat of amorphous boron is about 0-254) as being very far from * There is nothing known certainly as to whether the different modifications of sulphur have essentially different specific heats. Marchand and Scheerer’s experiments on brown and yellow sulphur made by the method of cooling, compare in Journal fiir Prakt. Chemie, vol. xxiv. p. 153. f “ Obtained from Yienna, and obviously distilled.” — Wohler. + After drying the stopper. § “ Prepared from boracic acid by sodium, and treated with hydrochloric acid.” — Wohler. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 107 the truth. There are no considerable accidental errors of observation in these experi- ments, to judge from their agreement with one another. Of the constants for calcu- lating the experiments, x and y must be taken into account in regard to any possible uncertainty. It has been assumed that #=0‘615 and ^=0-431 ; if we took #=0*63 and y=0*41, the specific heat as the mean of four experiments would be =0*30 ; if x were 0-67 and y 0*45, the specific heat would be 0*21. But from what has been com- municated in § 22 and § 27 in reference to the determination of x and y, it cannot be assumed that any possible uncertainty in reference to these values can reach either of the above limits. It can be assumed with the greater certainty that the specific heat of amorphous boron is between 0*2 and 03 and nearly 0*25, because x and y could not simultaneously both be found too great or too small (if x had been too small y would have been too great, and vice versd). Crystallized Boron *. Experiments with Naphtha A. Glass 3. Temperature of the Air 18°*9-18°*7. T. T'. t'. t. M. m. /• y- X. sp. H. O 0 0 o grms. grms. gnn. grm. 50*9 20*8 20*52 18*53 26*94 2*82 1*53 0*431 0*453 0*237 51*3 20*8 20*52 18*52 26*975 55 55 55 55 0*233 51*5 20*8 20*53 18*53 26*985 n 55 55 55 0*229 51*4 20*8 20*46 18*43 26*99 55 l*52f „ Mean 55 0*222 0*230 Hence the specific heat of the crystallized (adamantine) boron investigated is 0*230 between 21° and 51°; it is pretty near that found for amorphous boron, 0*254. Reg- nattlt found J (between 98° and 100° and the mean temperature) 0*225 for a specimen of crystallized boron prepared by Rousseau; 0*257 for one prepared by Debray; 0*262 for one obtained from Deville; and 0*235 for a specimen of graphitic boron prepared by Debray. The specific heat of amorphous boron could not be determined by Reg- nault’s method, because, when heated to 100° in air, it partially oxidizes into boracic acid with disengagement of heat (three experiments, in which the quantity of boracic acid formed was determined, and its specific heat, but not the thermal action due to the forma- tion of hydrated boracic acid in immersion in water allowed for, gave respectively 0*405, 0*348, and 0*360, which numbers Regnault does not consider as even approximately re- presenting the specific heat of amorphous boron), and when greatly cooled disengages a quantity of air when immersed in warmer water, which renders the results uncertain. * “Made in Paris, probably by Rousseau, and doubtless by melting borax with aluminium. To conclude from its external appearance, it probably contained some aluminium and carbon : compare the analysis in Ann. der Chem. und Pharm. vol. ci. p. 347.” — Wohlek. t After drying tbe stopper. + Ann. de Chim. et de Pbys. [3] vol. lxiii. p. 31. 108 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 35. Phosphorus. — I have only made a few determinations with ordinary yellow phos- phorus, which was cast in sticks. Experiments with Water. Glass 1. Temperature of the Air 10o,9. T. T'. t'. t. M. m. /• y- X m sp. H. O o 0 o grms. grms. grms. grm. 38-8 13-5 13-20 10-05 26-95 3-075 2-065 1-000 0-651 0-208 33-8 12-9 12-62 10-03 26-97 „ „ ,, 55 0-204 35-5 13-2 12-91 10-17 26-93 55 2-06* J? 55 0-195 Mean 0-202 The specific heat of yellow phosphorus, as deduced from these determinations, is somewhat greater than that found by Regnault, doubtless because in my experiments the upper limit of temperature, T', was nearer the melting-point of phosphorus, 44°. Compare § 82. Antimony. — Purified by Liebig’s method ; crystalline pieces. I. — Experiments with Naphtha A. Glass 2. Temperature of the Air 14°-7. T. T'. t'. t. M. m. /• y- X. sp. H. o O o 0 o grms. grm. grm. 46-4 16-0 15-65 13-42 26-945 12-245 1-925 0-431 0-487 0-0539 44-9 15-9 15-64 13-54 26-98 5> 55 55 55 % 0-0520 44-2 15-8 15-53 13-52 26-96 55 1-91* „ Mean '55 0-0496 0-0518 II. — Experiments with Water. Glass 1. Temperature of the Air 15° •8-16°-l. T. T'. t\ t. M. m. /• y- X . sp. H. 0 o o o grms. grms. grms. grm. 45-0 17-9 17-60 14-22 26-945 11-835 2-095 1-000 0-651 0-0519 45-1 17-9 17-64 14-25 26-96 55 55 55 55 0-0519 45-0 17-9 17-64 14-25 26-965 55 55 55 55 0-0530 45-4 18-1 17-76 14-34 26-955 ” 2-085* „ Mean 51 0-0542 0-0528 From these determinations, the average of the means of both series of determinations, 0-0518 and 0-0528, the number 0-0523 is the specific heat of antimony between 17° and 45°. Bismuth. — Purified by melting with nitre, and cast in small bars. In the case of this metal also, I have made a series of determinations with coal-tar naphtha in the glass, and one with water. After drying the stopper. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 109 I. — Experiments with Naphtha A. Glass 3. Temperature of the Air 180,9-180,8. T. 50-8 T'. 20-6 t'. . 20-33 t. 18-33 M. grms. 26-99 m. grms. 20-71 /• grm. 1-70 y- 0-431 x. sp. H. grm. 0-453 0-0291 50-3 20-7 20-42 18-43 26-955 99 99 „ „ 0-0302 50-1 20-6 20-33 18-37 26-955 99 99 99 0-0292 50-9 20-7 20-40 18-42 26-955 99 1-685 * 99 „ 0-0284 Mean . . . 0-0292 II. — Experiments with Water. Glass 1. Temperature of the Air 16°-7-16°-8. T. 45-2 T'. 18? 7 t'. 18-44 . t. 15-25 M. grms. 26-97 m. grms. 19-43 /- grm. 1-995 1-000 x. sp. H. grm. 0-651 0-0309 45-5 18-9 18-57 15-36 26-965. 99 „ 99 ,. 0-0313 45-0 18-9 18-64 15-47 26-975 99 99 99 „ 0-0324 46-0 181 18-82 15-56 26-99 99 1-985* 99 Mean . „ 0-0327 . . 0-0318 From these determinations we get for the specific heat of bismuth between 30° and 48° the number 0-0305. 36. Carbon. — It is known how different are the numbers obtained for the specific heat of carbon in its different forms. I have determined the specific heat for comparatively only a few of the modifications of carbon — for gas-carbon, for natural and artificial gra- phite. Before the experiment each of these substances was strongly heated for some time in a covered porcelain crucible, and then allowed to cool, and immediately trans- ferred into the glass for its reception, and, after weighing, naphtha poured over it. Gas-carbon from a Paris gas-works ; very dense, of an iron-grey colour, and left very little ash when calcinedf. It was used in pieces the size of a pea, and two series of experiments were made. * After drying the stopper. t This carbon, as well as the above-mentioned varieties of graphite, was analyzed in the Laboratory at Giessen by Mr. Hubek. The gas-carbon gave, when placed in a platinum boat and burned in a stream of oxygen,— I. II. III. IV. V. Carbon . . 97-19 98-25 97-73 98-08 98-55 Hydrogen . '. . . 0-53 0-15 0-68 0-37 1-00 Ash . . 0-61 0-62 0-73 0-23 0-69 98-33 99-02 99-14 98-68 100-24 110 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. I. Experiments with Naphtha A. Glass 1. Temperature of the Air 18o,9-190,2. T. T'. t'. t. M. m. /• y • X. sp. H. O O o 0 grms. grms. grm. grm. 52*9 20*8 20*53 18*13 26*955 3*135 1*825 0*431 0*651 0*184 52*6 20*9 20*63 18*26 26*98 „ 33 „ 0*185 51*7 20*7 20*42 18*06 26*97 33 35 33 „ 0*196 52*4 20*9 20*58 18*23 26*98 33 1*805* 33 J? 0*186 Mean . . . 0T88 II. — Experiments with Naphtha A. Glass 3. Temperature of the Air 20°*5-20°*8. T. T'. t' t. M. m. /• y- X. sp. H. 52*6 22*6 22*33 20*23 grms. 26*985 grms. 3*345 grm. 1*935 0*431 grm. 0*453 0*180 52*2 22*5 22*23 20*14 26*985 33 33 33 33 0*183 52*3 22*5 22*20 20*12 26*965 33 33 33 33 0*179 52*5 22*6 22*31 20*22 26*955 1*91* 33 33 0*182 Mean . . . 0*181 These determinations give as the average of the means of both sets of experiments the number 0*185 as the specific heat of gas-carbon between 22° and 52°. Natural graphite from Ceylon. Left very small quantities of ash when calcinedf. I. — Experiments with Naphtha A. Glass 3. Temperature of the Air 18°*9-19°*2. T. T'. t'. t. M. o o o 0 grms. 51*4 20*8 20*48 18*13 26*975 51*4 20*8 20*51 18*13 26*99 51*8 20*8 20*54 18*15 26*975 52*0 20*8 20*54 18*13 26*99 * After drying the stopper, t In Mr. Hubeb’s analyses this substance was m. /• y- X . sp. H. grms. grms. grm. 4*025 2*085 0*431 0-453 0*179 55 33 0*186 „ ?5 33 0*181 „ 2*06* „ 33 0*183 Mean 0*183 in a platinum boat, then burned in a porcelain tube in oxygen. I. II III. Carbon 99-11 98-52 Hydrogen . . 0-17 0-06 Ash . . 0-26 0-27 0-51 99-55 99-09 The residual porous ash left after the combustion was tolerably white, with admixed red particles. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. Ill II. — Experiments with Naphtha A. Glass 1. Temperature of the Air 19°-0-18°*7. T. T'. t\ t. M. m. /• y- X. sp. H. 0 o grms. grms. gnu. grm. 53-9 21-1 20-77 18-22 26-97 3-515 1-935 0-431 0-651 0-174 52-2 21-0 20-73 18-31 26-96 55 55 » „ 0-176 52*1 21*2 20-86 18-52 26-94 „ 0-158 53-0 21-0 20-73 18-32 26-97 „ 55 „ „ 0-155 52-8 21-0 20-73 18-33 26-965 55 1-91* „ „ 0-160 Mean 0-165 III. — Experiments with Naphtha A. Glass 3. Temperature of 1 the Air ■ 19°-9-20°-0. T. T'. t'. t. M. m. /- y- X . sp. H. 0 o o o grms. grms. grms. grm. 51-6 21*9 21-55 19-33 26-97 3-90 2-05 0-431 0-453 0-174 51-3 22-0 21-71 19-52 26-955 55 55 0-174 51-5 22-0 21-70 19-52 26‘97 55 55 0-168 51-5 21-9 21-63 19-42 26-96 5J 2-04* 55 55 0-175 Mean . . . 0T73 The average of the means of these three series of determinations, 0T83, 0T65, and 0T73, gives 0T74 as the specific heat of Ceylon graphite between 21° and 52°. Iron graphite from Oberhammer, near Sayn, separated upon black ordnance iron. Thin, very lustrous laminae, freed from iron by treatment with aqua regia as much as possible, yet not completely f. * After drying the stopper. t This iron graphite, according to Mr. Huber’s analyses, in which it was also burned in oxygen in a plati= i num boat placed in a porcelain tube, gave the following results : — • I. II. III. Carbon . . 97-01 96-12 96-37 Hydrogen . . 0-12 0-18 Ash . . 4-88 C» 3-99 101-89 101-11 100-54 It is probable that both in this graphite and in that of natural occurrence, the hydrogen is not essential, but arises from hygroscopic moisture. The residual ash contained porous particles consisting of sesquioxide of iron and silica, and also small pellets, covered externally with a layer of magnetic oxide of iron : these dissolved in hydrochloric acid at first quietly, and afterwards under disengagement of hydrogen ; and in the solution small blisters of graphite could he perceived. It is owing to the oxidation of the iron that the sum of the constituents in all cases exceeds 100. R MDCCCLXV. 112 PEOFESSOE KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. I. Experiments with Naphtha A. Glass 3. Temperature of the Air 19o-0-18°-7. T. T'. t'. t. M. m. /• y ■ ■ X, sp.H. O grins. grms. grms. grm. 52-5 20-8 20-53 18-21 26-955 2-51 2-445 0-431 0-453 0-186 52-9 21-1 20-84 18-54 26-98 55 2-565* 55 55 0-156 51-4 20-9 2064 18-43 26-94 „ 55 ,, „ 0-157 52-0 20-9 20-60 18-33 26-99 55 2-545f „ 55 0-168 Mean 0-167 .—Experiments with Naphtha A. Glass 1. Temperature of the Air 19°-9-20°-0. T. T'. t'. t. M. ra. /• y- oc. sp. H. o O 0 o grms. grms. grms. grm. 52-1 21-9 21-57 19-32 26-94 2-48 2-205 0-431 0-651 0-164 51-7 22-0 21-66 19-45 26-97 55 55 55 55 0-163 51-5 22-0 21-73 19-54 26-98 55 55 „ 0-162 51-5 22-0 21-66 19‘46 26-945 55 2-19f 55 55 0*167 Mean . 0T64 The average of the means of both these series of experiments, 0T67 and 0T64, gives 0T66 as the specific heat of iron graphite between 22° and 52°. The results previously known in reference to the specific heat of carbon, differ greatly for its different conditions, as also do the results obtained by different inquirers and by different methods for the same condition. But even leaving out of consideration the numbers obtained by De la Rive and Marcet by the method of cooling, there are still considerable differences between Regnault’s results, obtained by the method of mixture, and my own. Regnault found for animal charcoal 0-261, for wood-charcoal 0-241, for gas-carbon 0-209, for natural graphite 0-202, for iron graphite 0*197, for diamond 0-1469 ; his experiments gave greater numbers for the same substance than my own. I think that exactly for a substance like carbon in its less dense modifications, my method promises more accurate results than that of Regnault. Even in mine, the substance, after being strongly heated before the experiment, might absorb gases or aqueous vapour, which would make the specific heat too great. But in Regnault’s method this source of error might also operate, and more especially also the source of error due to the disengage- ment of heat when porous substances are moistened by water. These sources of error, which affect the determination of the specific heat of the various modifications of carbon and make it too high, have the more influence the looser and the more porous the sub- stance investigated. I believe that the only certain determination of the specific heat of carbon is that of diamond, and all other determinations are too high, owing to various circumstances, and in Regnault’s experiments with wood and animal charcoal, &c., owing to the heat disengaged when these substances are moistened by water. * After some more naphtha had been added. t After drying the stopper. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 113 37. Silicium. — I have investigated this substance in four different modifications. Amorphous Silicium *. — For the experiments picked coherent pieces were used, which had stood for several days in vacuo over sulphuric acid. Experiments with Naphtha A. Glass 3. Temperature of the Air 19°-2. T. T'. t'. t. M. m. /• V' X. sp. H. 0 grms. grm. grms. grm. 0-251 5l-5 20-7 20-38 18-13 26-95 1-095 2-88 0-431 0-453 50-0 20-8 20-54 18-46 26-975 55 „ 99 99 0-208 50-4 21-0 20-66 18-55 26-98 „ ,, 99 99 0-221 50-5 20-9 20-59 18-52 26-935 „ 2-87f „ 99 0-177 Mean . . . 0-214 The very discordant results of these experiments are very little trustworthy ; the quantity of silicium, 1 grm., was too small, and its thermal action inconsiderable as com- pared with that of the other substances immersed with it in the water of the calorimeter. Graphitoidal Silicium J. Experiments with Naphtha A. Glass 3. Temperature of the Air 16°-7-17°-2. T. T'. a. t. M. m. /• y- x. sp. H. O o o o grms. grms. grm. grm. 51-0 18-8 18-51 16-34 26-965 3-155 1-83 0-431 0-453 0-182 52-3 19-1 18-82 16-59 26-975 99 99 99 „ 0-181 51-1 18-9 18-62 16-44 26-98 99 99 99 „ 0-185 50-4 18-8 18-52 16-43 26-95 l-81f 99 „ 0-174 Mean . . . 0-181 Crystallized Silicium . — Grey needles §. Experiments with Naphtha A. Glass 1. Temperature of the Air 19°-1. T. O T'. o t'. 0 t. o M. grms. m. grms. /• grm. y- X. grm. sp. H. 53-8 21-1 20-83 18-53 26-94 2-395 1-955 0-431 0-651 0-168 52-6 21-0 20-74 18-52 26-975 99 99 99 ,5 0-168 52-3 21-0 20-72 18-52 26-98 99 99 99 55 0-168 51-9 21-0 20-66 18-53 26-975 99 l-935f Mean 55 0-156 0-165 * “ Prepared from silicofluoride of potassium by means of sodium.” — Wohler. t After drying the stopper. + “ Obtained by melting silicofluoride of potassium, or sodium, with aluminium ; the aluminium was then extracted with hot hydrochloric acid, and the oxide of silicium with fluoric acid.” — Wohler. § “ This silicium was prepared from the silicofluoride of potassium, or sodium, by sodium and zinc, and the lead (from the zinc) removed by nitric acid. Whether it was afterwards treated with hydrofluoric acid 1 cannot say, but probably so. It was quite unchanged when heated in the vapour of hydrochlorate of chloride of silicium (passed by means of hydrogen). Probably it contained, however, like all silicium reduced by zinc, a trace of iron, which appears when it is heated in chlorine. An experiment with another portion of such silicium gave, however, so little iron that its quantity could not be determined.” — Wohler. R 114 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. Fused Silicium *. Experiments with Naphtha A. Glass 1. Temperature of the Air 18°*9-180,7. T. T'. t'. t. M. m. /• y- a?. sp. H. Q grms. grms. grm. grm. 0-142 49-0 20-5 20-24 18-40 26-97 417 1-555 0-431 0-651 50-5 20*7 20-43 18-52 26-96 99 55 0139 49-7 20-6 20-27 18-42 26-965 99 55 55 55 0136 50-8 20-7 20-43 18-52 26.94 99 l-145f „ 55 0136 Mean . . . 0138 38. Tin : reduced from the oxide, cast in small bars. I. — Experiments with Naphtha A. Glass 1. Temperature of the Air 17°-8-180,8. T. T'. t'. t. M. m. /• y- CO. sp. H. 0 0 grms. grms. grm. grm. 51-4 19-8 19-46 1714 26-965 14-835 1-385 0-431 0-651 0-0493 51-4 19-9 19-62 17-23 26-98 99 99 99 99 0-0539 51-3 20-0 19-72 17-34 26-95 99 99 99 0-0540 51-5 20-3 20-03 17-65 26-995 99 1-365 f „ 99 0-0553 Mean 0-0531 11. — Experiments with Water. Glass 1. Temperature of the Air 15' 3-5-15°-9. T. T'. t'. t. M. m. /• y- X. sp. H. o 0 o o grms. grms. grm. grm. 45-1 17-5 17-24 14-13 26-975 14-62 1-595 1-000 0-651 0-0543 46-4 17-5 17-24 13-94 26-985 99 99 99 99 0-0571 45-6 17-6 17-34 1414 26-99 99 99 99 99 0-0574 45-7 17-6 17-34 1414 26-95 99 1-58 f 99 99 0-0573 Mean 0-0565 The average of the means of these two series of observations gives 0-0548 as the specific heat of tin between 19° and 48° at 0-0548. Platinum : several pieces of fused platinum and of thick platinum wire. Experiments with Naphtha A. Glass 1. Temperature of the Air 170,8-18°-2. T. T’. t'. t. M. m. /• y • X . sp. H. 53-5 20-4 20-14 17-23 grms. 26-96 grms. 23-625 grm. 2-225 0-431 grm. 0-651 0-0322 52-8 20-0 19-65 16-73 26-975 99 99 99 99 0-0335 51-5 20-0 19-73 16-95 26-96 99 99 99 0-0326 50-9 20-0 19-74 17-05 26-96 „ 2-205 f 99 99 0-0316 I have also made a few experiments with a piece of fused iridium which M. Herjsus gave me. "Wohler had obtained it from Detille ; it formed a cylindrical piece. After drying the stopper. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 115 Experiments with Naphtha A. Glass 3. Temperature of the Air 170,8-18°-2. T. T'. t'. t. M. m. /• y- X . sp. H. O o o o grms. grms. grms. grm. 51-8 19-5 19.24 16-93 26-995 16-66 2-04 0-431 0-453 0-0359 51-0 19-6 19-26 16-95 26-97 55 95 59 55 0-03911 50-0 19-5 19-24 17-06 26-965 59 55 55 59 0-0357 50-5 19-6 19-34 17-13 26-93 „ 2-03 * 0-0359 Excluding • the second experiment, which is obviously uncertain, these determinations give 0-0358 as the specific heat of iridium. This iridium was not free from metals of smaller atomic weight and greater specific heat. For various specimens of impure iridium, Regnault (Ann. de Chim. et de Phys. [2] vol. lxxiii. p. 53; [3] vol. xlvi. p. 263 ; vol. lxiii. p. 16) found 0-0368, 0-0363, 0-0419, and for almost pure iridium 0-0326. 39. Silver : pure, cast in bars. Experiments with Naphtha A. Glass 3. Temperature of the Air 18°-9-19°T. T. T'. t'. t. M. m. /• y- X. sp. H. o O o o grms. grms. grm. grm. 52-1 21-1 20-82 18-15 26-975 21-51 1-585 0-431 0-453 0-0552 51-5 21-1 20-77 18-14 26-99 55 55 55 55 0-0557 51-4 20-9 20-62 17-94 26-98 55 55 95 „ 0-0574 50-9 21-0 20-65 18-06 26-95 55 59 55 „ 0-0557 51-0 21-1 20-83 18-25 26-965 59 1-565* „ 55 0-0558 Copper. — Commercial copper wires f . I. — Experiment with Naphtha A. Glass 1. Mean Temperature . . . 0-0560 of the Air 13°-2. T. T'. t\ t. M. m. /• y ■ X . sp. H. o 0 0 0 grms. grms. grm. grm. 44-3 15-9 15-64 12-64 26-985 16-505 1-675 0-43] . 0-651 0-0895 46-2 15-1 14-82 11-43 26-97 „ 55 55 „ 0-0949 45-7 15-2 14-91 11-63 26-97 55 55 55 55 0-0926 47-7 15-2 14-93 11-43 26-98 „ 1-67* „ „ 0-0930 * After drying the stopper, t With reference to what has been said in § 24, I Mean here communicate a series . . . 0-0925 of experiments (one o earliest) where t' was much more above the temperature of the air than usual, and hence too small numbers were obtained for the specific heat of the substance in question. Experiments with Naphtha A. Glass 2. Temperature 130-8. T. T'. t'. t. M. m. /. y> X. sp. H. 45-6. 16-5 16-23 13-02 grms. 26-98 grms. 18-33 grm. 1-96 0*431 grm. 0*487 0-0897 48-5 16-9 16-64 13-21 26-97 99 0-0870 43-7 16-5 16-15 13-21 26-98 99 1-95* 0-0867 * After drying the stopper. 116 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. II. — Experiments with Naphtha B. Glass 3. Temperature of the Air 19°‘4-19o,0. T. T'. t'. t. M. TO. /• y- X. sp. H. grms. grms. grm. grm. 55-0 21-9 21-62 18-06 26-96 19-725 1-56 0-419 0-453 0-0909 54-1 21-4 21T1 17-60 26-965 55 55 55 55 0-0906 53-6 21-2 20-86 17-36 26-99 55 55 55 55 0-0917 54-2 21-3 20-96 17-44 26-98 55 55 55 0-0902 51-7 21-2 20-85 17-55 26-965 ” 1-545 * „ Mean 55 0-0921 0-0911 hi.—: Experiments with Water. Glass 1. Temperature of the Air 18! o* OO i — 1 1 T. T'. t'. t. M. TO. /• y- OB. sp. H. 0 O 0 o grms. grms. grm. grm. 49-7 20-8 20-50 16-17 26-95 18-26 1-625 1-000 0-651 0-0965 50-0 20-6 20-32 15-93 26-96 55 55 0-0958 49-5 20-8 20-50 16-22 26-93 55 „ 0-0953 47-9 20-9 20-62 16-64 26-945 55 1-615 * „ Mean 55 0-0934 0-0953 According to these determinations, the mean of the average results 0-0925, 0-0911, 0-0953, the number 0-093 represents the specific heat of copper between 20° and 50°. 40. Lead : reduced from sulphate of lead and cast in small bars. I. — Experiments with Naphtha A. Glass 1. Temperature of the Air 18°-9-18°-8. T. T'. t'. t. M. TO. /• y- X. sp. H. O O o o grms. grms. grm. grm. 50-5 20-6 20-33 18-23 26-995 19-93 1-465 0-431 0-651 0-0308 50-5 20-7 20-43 18-35 26-975 55 55 55 „ 0-0302 50-9 20-7 20-44 18-35 26-965 55 55 55 55 0-0293 50-5 20-6 20-32 18-24 26-94 55 1-445 * 55 0-0302 Mean , . . 0-0301 II. — Experiments with Water. Glass 1. Temperature of the Air 15°-5-150,9, T. T'. t'. t. M. TO. /• y- X . sp. H. 46-0 o 17-5 17-21 14-02 grms. 26-96 grms. 24-845 grm. 1-56 1-000 grm. 0-651 0-0325 45-3 17-6 17-32 14-23 26-985 55 55 55 0-0322 45-9 17-7 17-42 14-25 26-945 55 55 55 55 0-0329 46-1 17-9 17-61 14-43 26-985 „ 1-55 * 55 55 0-0339 Mean . . . 0-0329 The mean of the averages of both series of experiments, 0-0301 and 0-0329, gives for the specific heat of lead between 19° and 48° the number 0-0315 * After drying the stopper, PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 117 Zinc : purified, cast in small bars. I. — Experiments with Naphtha A. Glass 3. Temperature of the Air 170,8-18°-9. ,T. T'., t'. o t. o M. grms. m. grms. /• grm. y • X. grm. sp. H. 51-5 20-5 20-22 17*23 26-995 15-555 1-745 0-431 0-453 0-0899 51-1 20-3 19-95 16-96 26-985 „ 55 55 55 0-0909 51-7 20-6 20-25 17-24 26-99 55 55 55 55 0-0905 50-9 20-5 20-23 17-25 26-945 55 1-72* 55 Mean ” 0-0930 0-0911 II. — Experiments with Water. Glass 1. Temperature of the Air 16o,0-16°-5. T. T'. t'. t. M. m. /• y • X . sp. H. o o o o grms. grms. grm. grm. 43-0 17-7 17-43 13-82 26-98 14-25 1-855 1-000 0-651 0-0943 43-1 18T 17-84 14-26 26-965 55 55 55 „ 0-0951 42-7 18-1 17-82 14-32 26-96 55 55 55 55 0-0933 42-7 18-4 18-05 14-54 26-99 55 55 55 „ 0-0977 42-9 18-5 18-23 14-74 26-97 1-845 * „ 55 0-0956 Mean . . . 0-0952 These determinations give 0-0932 as the mean of the means of the two series of determinations for the specific heat of zinc between 19° and 47°. Cadmium : cast in small bars. Experiments with Naphtha A. Glass 1. Temperature of the Air 18°-9-19°T. T. T'. t[. t. M. m. /• 2/* X . sp. H. o O o 0 grms. grms. grm. grm. 53-7 21-0 20-72 18-24 26-955 13-335 1-555 0-431 0-651 0-0542 51-6 20-9 20-56 18-23 26-97 55 55 55 55 0-0544 51-9 20-8 20-47 18-12 26-98 55 „ 55 0-0538 52-3 20-8 20-52 18-14 26-975 „ 1-535* 55 55 0-0544 Mean . . . 0-0542 Magnesium : metallic globules and masses comminutedf . Experiments with Naphtha A. Glass 1. Temperature of the Air 180,6-19°1. T. T'. t'. t. M. m. /• y- X. sp. H. o O o o grms. grms. grm. grm. 53-3 20-6 20-32 17-74 26-995 3-485 1-42 0-431 0-651 0-249 51-8 20-6 20-26 17-83 26-97 55 0-240 51-0 20-6 20-33 17-94 26-99 ,, 5} 0-247 51-6 21-0 20-72 18-33 26-96 „ 1-40 * 55 „ 0-244 Mean . . . 0-245 * After drying the stopper. t “ The magnesium was prepared hy the methods of Deville and Caron, and Wohler. The reguline masses were not remelted, hut treated with dilute hydrochloric acid, then washed with water and dried at a gentle temperature.” — Engelbach. 118 PKOFESSOE KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. Iron : pieces of iron wire. I. — Experiments with Naphtha A. Glass 2. Temperature of the Air 130-2. T. T'. t'. t. M. m. /• y- SC. sp. H. 0 o o o grms. grms. grm. grm. 46-6 16-2 15-92 12-52 26-97 17-565 1-46 0-431 0-487 0-108 45-4 15T 14-83 11-33 26-95 55 „ ,, 55 0-114 46-0 15-1 14-77 11-22 26-935 55 „ 55 55 0-113 46-2 15-2 14-91 11-34 26-98 55 1-455 * 55 „ 0-113 Mean 0-112 II. — Experiments with Water. Glass 1. Temperature of the Air 16°- o" r- i— i 1 oo T. T'. t'. t. M. m. /• y • sc. sp. H. O 0 a o grms. grms. grm. grm. 43-2 18-8 18-46 15-02 26-985 15-57 1-425 1-000 0-651 0-111 42-9 19*1 18-84 15-47 26-975 55 55 ,, „ 0-112 43-6 19*3 19-04 15-62 26-99 55 55 „ 0-111 42-5 19*3 19-01 15-72 26-985 55 1-42* 55 55 0-113 Mean . . . 0-112 The means of both series of experiments give for the specific heat of iron between 17° and 44° the number 0T12. With reference to what has been said in § 24, the following series of experiments made at the beginning of my investigation are given, in which t' exceeded the ordinary temperature much more than usual, and hence the numbers for the specific heat of iron were found somewhat too small. Experiments with Naphtha A. Glass 1. Temperature of the Air 13°-8. T. T'. t'. t. M. m. /• y- sc. sp. H. o O 0 o grms. grms. grm. grm. 48-1 16-4 16-12 12-73 26-93 15-57 1-185 0-431 0-651 0-111 44-5 16-3 15-97 13-03 26-905 ,, „ „ „ 0-106 45-7 16-6 16-26 13-23 26-97 55 55 „ 55 0-106 47-0 16-7 16-43 13-23 26-96 55 1-17* 55 55 0-103 Another source of error which may make the numbers for the specific heat < substance investigated too small, has been discussed in § 18 and 24, — the circumstance, namely, that the substance may fill the glass so densely as to impede the circulation of the liquid, or make it impossible. This circumstance made the numbers for the specific heat of chromium , which were obtained from the following series of observa- tions, too small. The chromium was reduced from chloride of chromium according to Wohler’s method by means of zinc (Ann. der Chem. und Pharm. vol.'cxi. p. 230); the heavy, finely crystalline powder deposits in the glass as a dense mass impeding the circulation. The following results were obtained : — * After drying the stopper. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 119 Experiments with Naphtha A. Glass 3. Temperature of the Air 19°*8-19°T. T. T'. t'. t. M. m. /• y- X . sp. H. 0 o 0 o grm. grms. grms. grm. 51-2 21-6 21*34 18*96 26*965 6*725 2*405 0*431 0*453 0*101 51*2 21-6 21*33 18*95 26*97 55 „ „ 0*101 50-8 21-5 21*24 18*92 26*945 55 55 „ „ 0*096 51*8 21-5 21*22 18*81 26*99 55 2*36 * „ „ 0*101 As the atomic weight of chromium is somewhat smaller than that of iron, it is to be supposed that the specific heat of chromium is somewhat greater than that of iron. Aluminium : a piece of a small bar f. Experiments with Naphtha A. Glass 3. Temperature of the Air 18°*6-18°*4. T. T'. t'. t. M. m. /• y- X. sp. H. 0 O 0 o grms. grms. grm. grm. 52*3 20*9 20*64 18*03 26*98 5*916 1*45 0*431 0*453 0*197 51*9 20*7 20*44 17*83 26*995 55 55 55 „ 0*200 52*2 20*9 20*62 17*95 26*97 55 55 55 55 0*207 51*0 20*8 20*47 17*93 26*975 55 1*435 * 55 55 0*202 Mean . . . 0-202 42. Remisulphide of Copper, €u2S$. Copper-glance was investigated ; a dense spe- cimen with conchoidal fracture from Liberty Mine in Maryland and a crystallized specimen of unknown locality, which also I tested as to its purity. Experiments with Naphtha A. Glass 1. Temperature of the Air 160,T. T. T'. t'. t. M. m. /• y- X. sp. H. 52*6 19*0 18*72 15*74 grms. 26*995 grms. 8*775 grm. 1*595 0*431 grm. 0-651 0*120 52*0 18*9 18*58 15*65 26*995 55 55 „ 55 0*120 52*6 19*0 18*72 15*74 26*99 55 55 55 55 0*120 51*6 18*8 18*53 15*63 26*96 „ 1*58 * 55 55 • 0*120 Mean . . . 0*120 * After drying the stopper. t “ By remelting Paris aluminium, by which, it became poorer in iron ; contains probably still some iron and silicium.” — Wohler. + All formulae of compounds whose specific heat is discussed in the following are written under the assump- tion of the new atomic weights (see § 2). MDCCCLXV. S 120 PEOFESSOB KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. Sulphide of Mercury, -HgS. Pieces of a sublimed cake of cinnabar*. Experiments with Naphtha A. Glass 1. Temperature of the Air 20o,3-21°T. T. T'. t\ t- M. m. f. y. X. sp. H. O o o o grms. grms. grm. grm. 50-9 22-2 21-94 19-79 26-95 13-44 1-565 0-431 0-651 0-0516 51-8 22-3 22-02 19-80 26-95 55 55 55 35 0-0523 51-2 22-4 22-05 19-92 26-98 55 55 55 33 0-0499 51-8 22-4 22-14 19-93 26-98 „ 1-55 f „ Mean , ” 0-0528 0-0517" Sulphide of Zinc. -Zn -S. Fragments of crystals of black Zinc-blende from Bohemia. Experiments with Naphtha A. Glass 1. Temperature of the Air 14°T. T. T'. t'. t. M. to. /• y- sp. H. ■ 0 O o o grms. grms. grm. grm. 50-8 16-3 16-02 13-18 26-975 7-00 1-64 0 •431 0-651 0-123 46-7 16-1 15-83 13-33 26-935 55 55 • 55 55 0-120 44-1 15-9 15-63 13-32 26-94 55 55 55 55 0-121 44-8 16-2 15-93 13-63 26-94 5? 55 55 55 0-116 43-1 15-9 15-63 13-42 26-97 5? 1-625 f 55 55 0-120 Mean . . . 0T20 Sulphide of Lead, Pb -S. Cleavage fragments of Galena from the Harz. Experiments with Naphtha A. Glass 1. Temperature of the Air 14°-5-14°-9. T. T'. t\ t. M. TO. /• y- X. sp. H. o o 0 o grms. grms. grm. grm. 51-3 16-4 16-05 13-34 26-93 13-835 1-78 0-431 0-651 0-0486 48-6 16-4 16-05 13-54 26-975 55 55 55 55 0-0495 45-7 16-1 15-83 13-53 26-95 55 55 55 55 0-0489 48-4 16-2 15-94 13-44 26-925 55 1-765 f „ Mean 55 0-0490 0-0490 * This cinnabar was found, on being tested, to be free from admixed uncombined sulphur. In experiments with another specimen of beautiful crystalline appearance, I obtained considerably greater numbers for the specific beat. Experiments with Naphtha A. Glass 1. Temperature of the Air 160,3-16°-6. T. T'. t'. t. M. TO. /- y- X. sp. H. 0 O o o grms. grms. grm. grm. 53-0 18-5 18-23 15-72 26-975 9-805 1-72 0-431 0-651 0-0582 51-5 18-4 18-14 15-76 26-96 „ „ „ }> 0-0557 52-0 18-4 18-13 15-73 26-99 „ „ „ „ 0-0546 51-6 18-5 18-16 15-81 26-97 1-70+ „ ,, 0-0542 But the Naphtha which bad been in contact with this cinnabar, left on evaporation a considerable quantity of sulphur, the admixture of which made the specific beat too large, f After drying the stopper. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 121 43. Sulphide of Copper and Iron, Cu Ee -S2, or Gu^Ee^S. Crystals and fragments of crystalline masses of Copper pyrites from Dillenburg. Experiments with Water. Glass 1. Temperature of the Air 17°-2- -17° -5. T. T'. t'. t. M. m. /• y • X. sp. H. 47-5 o 19-1 18-82 15-22 grms. 26-975 grms. 7-365 grm. 1-825 1-000 grm. 0-651 0-128 48-0 19-4 19-12 15-44 . 26-985 55 99 99 „ 0-135 47-6 19-5 19-23 15-65 26-975 59 „ 99 55 0-131 48-1 19-6 19-25 15-64 26-985 59 59 95 55 0-128 47-6 19-5 19-23 15-64 26-94 59 1-81* 55 55 0-133 Mean . . . 0-131 Bisulphide of Iron, Ee S2. Small crystals and crystalline fragments of Iron pyrites from Dillenburg. I. — Experiments with Naphtha A. Glass 2. Temperature of the Air 130,3. T. T'. t'. t. M. m. /• y- X. sp. H. O o o 0 grms. grms. grm. grm. 47-1 16-0 15-66 12-74 26-92 10-11 1-81 0-431 0-487 0-125 46-2 15-9 15-61 12-77 26-93 „ 55 55 59 0-124 47T 16-0 15-74 12-87 26-97 55 55 55 „ 0-121 47-9 16-2 15-87 12-95 26-93 1-795 * „ 55 0-121 Mean . . . 0-123 II. — Experiments with Water. Glass 3. Temperature of the Air 17°-4-17°'5. T. T'. o t'. t. M. grms. m.- grms. /• grms. y- X. grm. sp. H. 47-1 19-7 19-43 15-33 26-97 10-145 2-295 1-000 0-453 0-127 47-5 19-7 19-42 15-23 26-955 „ „ „ 55 0-130 47-6 19-8 19-47 15-33 26-965 59 55 ,, 55 0-125 47-4 19-8 19-52 15-36 26-945 55 2-28* „ Mean 55 0-131 0-128 The average of the means of both these series of experiments, 0*123 and 0-128, makes the specific heat of iron pyrites between 18° and 47°=0T26. 44. Suboxide of Copper, €u20. A crystalline fine-grained Bed copper-glance of con- choidal fracture was used for investigation. s 2 * After drying the stopper. 122 PKOFESSOE KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. Experiments with Naphtha A. Glass 3. Temperature of the Air 160,7. T. T'. t'. t. M. m. /• y- X» sp. H. O o 0 o grms. grms. grm. grm. 51-6 18-7 18-36 15-80 26-97 8-67 1-635 0-431 0-453 0-109 51-0 18-6 18-26 15-73 26-995 55 55 55 0-110 50-8 18-6 18-26 15-72 26-96 55 55 5? 0-112 52-3 18-6 18-33 15-66 26-95 ” 1-625 * „ Mean ?? 0-113 0-111 Oxide of Copper, €u O. Granular freshly ignited oxide of copper. Experiments with Naphtha A. Glass 1. Temperature of the Air 17°T-170,9. T. O 51- 1 52- 0 51T 50-8 T'. 19-2 19-3 19*4 19-4 t'. 18-86 18- 95 19- 11 19-07 t. 16-23 16-23 16-43 16-43 M. grins. 26-965 26-985 26-94 26-97 m. grins. 6-295 /• grm. 1-85 y- 0-431 1-83 * „ Mean X. grm. 0-651 sp. H. 0-123 0-126 0-132 0-131 0-128 Oxide of Lead , PbO. Larger pieces of litharge freed by the sieve from the finer particles. Experiments with Naphtha A. Glass 3. Temperature of the Air 17°-4-17°-6. T. O T'. O t'. 0 t. 0 M. grms. m. grms. /• grms. y- X. grm. sp. H. 51-5 19-1 18-83 16-51 26-965 10-17 2-11 0-431 0-453 0-0559 50-4 19-1 18-84 16-63 26-95 ?? 55 0-0532 49-2 19-0 18-73 16-56 26-98 „ 55 55 0-0567 48-5 19-0 18-73 16-63 26-985 2'10 * „ Mean 55 0-0554 0-0553 Oxide of Mercury , HgO. Crystalline pieces of Mercurius prcecipitatus per se, freed by the sieve from finer particles. Experiments with Naphtha A. Glass 1. Temperature of the Air 170,4-170-6. T. T'. t\ t. M. m. /• y- X. sp. H. O 0 0 0 grms. grms. grm. grm. 53-1 19-3 19-03 16-64 26-985 8-45 1-925 0-431 0-651 0-0506 52-0 19-1 18-83 16-46 26-975 55 „ 55 0-0547 51-5 19-1 18-83 16-53 26-935 55 „ 0-0510 50-4 19-1 18-82 16-56 26-965 ” 1-915 * „ Mean 55 0-0557 0-0530 Hydrate of Magnesia , MgO + H20. Transparent cleavage laminae of Brucite from Texas in Pennsylvania. Dried at 40°-50°. After drying the stopper. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 123 Experiments with Naphtha A. Glass 3. Temperature of the Air 170-2. T. T'. t'. t. M. m. /• y- X. sp. H. 0 O o o grms. grms. grms. grm. 51-9 19-4 19-13 16-02 26-985 3-59 2-29 0-431 0-453 0-318 52-2 19-5 19-23 16-12 26-99 55 5> ?) 55 0-314 48-2 19-3 19-04 16-32 26-95 55 y> 55 0-305 49*2 19*6 19-32 16-53 26-985 55 2-27* „ Mean 55 0-310 0-312 45. Spinelle, Mg Al204f . Transparent crystalline grains from Ceylon of octahedral form. I. — Experiments with Naphtha A. < Glass 1. Temperature of the Air ll°-5. T. T'. t'. t. M. in. /• y • X. sp. H. o 0 0 o grms. grms. grm. grm. 45-6 13-8 13-52 10-88 26-925 5-025 1-325 0-431 0-651 0-202 44-1 13-5 13-23 10-68 26-965 55 55 55 55 • 0-204 46-0 13-8 13-46 10-84 26-96 55 55 55 55 0-193 44-8 13-9 13-55 11-04 26-975 55 1-32* 55 55 0-193 Mean 0-198 II. — Experiments with Naphtha A. Glass 2. Temperature of the Air ll°-5, T. T'. t'. t. H. m. /• y- X. sp. H. O 0 o o grms. grms. grm. grm. 45-7 14-1 13-83 11-47 26-935 5-025 1-265 0-431 0-487 0-195 46-1 13-8 13-54 11-14 26-95 „ 55 55 55 0-193 46-2 13-2 12-85 10-33 26-975 55 55 55 „ 0-205 48-0 13-8 13-45 10-93 26-95 „ 1-26* 55 55 0-190 Mean . . . 0T96 I subsequently received another quantity of spinelle grains, also from Ceylon, and have made the following series of experiments with this material. III. — Experiments with Naphtha A. Glass 1. Temperature of the Air 15°-5. T. T'. t'. t. M. in. /• y- X. sp. H. o o o 0 grms. grms. grm. grm. 46-6 17-7 17-36 14-53 26-94 7-53 1-34 0-431 0-651 0-187 47-5 17-8 17-46 14-53 26-96 „ 55 55 55 0-190 47-6 17-8 17-54 14-63 26-965 55 55 „ 55 0-187 48-4 17-8 17-54 14-54 26-95 55 1-32* 55 55 0-189 Mean . . . 0188 * After drying the stopper. t Abich’s analysis of red spinelle from Ceylon (Rammeesberg’s ‘ Handbuch der Mineralchemie,’ p. 161), gave the following results compared with those calculated by the above formula : — A1„03. Cr203. MgO. FeO. Si02. Total. Analysis 69-01 1-10 26-21 0-71 2-02 99-05 Calculation 71-99 „ 28-01 „ „ 100-00 124 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. These determinations give as the average of the means of the three series of experi- ments (0T98, 0T96, and 0T88) 0T94 for the specific heat of spinelle between 15° and 46°. Chrome Iron Ore , Mg] -FeA Or* Al, G4#. Fragments of granular pieces, partly dis- tinctly crystalline, of chrome iron ore from Baltimore. Experiments with Naphtha A. Glass 1. Temperature of the Air 14°‘2-13°’8. T. T'. n. t. M. m. /• y- cc. sp. H. O o o o grms. grms. grm. grm. 47-6 16-4 16-12 13-14 26-97 7-625 1-63 0-431 0-651 0T63 46-9 16-5 16-24 13-38 26-985 33 J} 33 0-155 46-8 16-4 16-13 13-24 26-925 33 „ 55 33 0-158 46-4 1.6-4 16-13 13-28 26-955 „ 1-61 f 5J 33 0-159 Mean . . . 0459 Magnetic Iron Ore , Fe3 04. Small crystals and crystalline fragments from Pfitsch in Tyrol. I. — Experiments with Naphtha A. Glass 1. Temperature of the Air ll°-0. T. T'. t'. t. M. m. /• y - X. sp. H. O o o o grms. grms. grm. grm. 45-1 13-9 13-64 10-54 26-96 9-07 1-43 0 1-431 0-651 0-156 47-4 13-8 13-53 10-23 26-97 33 33 33 33 0-152 49T 14-1 13-84 10-42 26-98 33 33 33 0-151 47-6 14-1 13-83 10-54 26-92 33 1-415 f 33 33 0-152 Mean . 0-153 II. — Experiments with . Water. Glass 3. Temperature of the Air 19°-5-190,4. T. T'. t'. . t. M. m. /• y- X. sp. H. O o o o grms. grms. grm. grm. 43-5 : 21-6 21-32 : 18-02 26-985 10-625 1-925 1-000 0-453 0-159 42-7 21-6 21-32 : 18-13 26-99 33 33 33 t33 0-160 43-0 : 21-6 21-33 : 18-12 26-97 33 1-91 f 33 3 3, 0-158 Mean . 0-159 These determinations give as the mean of the averages of the two sets of experi- ments, 0-156 for the specific heat of magnetic iron ore between 18° and 45°. * The admissibility of this formula for the ore investigated follows from the following comparison of the results calculated from it, with those which Abich had obtained (Rammelsbebg’s £ Handbuch der Mineral- chemie,’ p. 172) by the analysis, a of compact, b of crystallized chrome iron ore from Baltimore. Cr203. Al,03. Fe O. MgO. Total. Analysis f a 55-37 13*97 19-13 10-04 98-51 ' 1 b 60-04 11-85 20-13 7-45 99-47 Calculation . . ... 58-32 13-11 18-37 10-20 ’ 100-00 f After drying the stopper. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 125 46. Sesquioxide of Iron , Ee2 03. Crystals and crystalline pieces of specular iron from St. Gotthard. I. — Experiments with Naphtha A. Glass 1. Temperature of the Air 12°*4-120,3. T. T'. t'. t. M. M. /• y- x. sp. H. Q grms. grms. grm. grm. 47-0 14-8 14-47 11-38 26-97 7-51 1-74 0-431 0-651 0-158 46-4 14-7 14-43 11-43 26-975 33 33 55 33 0-153 45-8 14-7 14-44 11-52 26-925 „ „ „ „ 0-150 45-8 15-0 14-73 11-83 26-98 33 1-72* „ 33 0-153 Mean 0-154 II.- -Experiments with Water. Glass 1. Temperature of the Air 19°-5. T. T. t'. t. M. m. /• y- X. sp. H. 0 O 0 0 grms. grms. grm. grm. 44-1 21-5 21-17 17-81 26-97 8-845 1-935 1-000 0-651 0-161 43-6 21-6 21-26 18-01 26-985 33 33 33 55 0-158 42-5 21-5 21-23 18-12 26-985 „ 33 55 0-159 42-8 21-6 21-33 18-22 26-98 33 1-92* 33 „ 0-157 Mean 0-159 The specific heat of specular iron between 18° and 45°, according to these determi- nations, is 0T57, the mean of the averages of both series of experiments 0T54 and 0-159. Iserine, Ee6 Ti3 03 f . Indistinct crystalline grains from the Iserwiese in the Riesenge- birge. Experiments with Naphtha A. Glass 2. Temperature of the Air 140,2-130'8. T. T'. t'. t. M. m. /• y- x. sp. H. o o 0 o grms. grms. grm. grm. 46-6 17-1 16-77 13-43 26-975 11-145 1-415 0-431 0-487 0-176 47-0 16-7 16-43 12-97 26-98 33 „ 33 ,, 0-178 46-5 16-6 16-33 12-93 26-93 33 33 33 „ 0-176 47-0 16-9 16-56 13-15 26-98 33 1-39 * 33 Mean „ 0-177 . . . 0T77 * After drying the stopper. f This formula corresponds to the composition assumed by Rammelsberg (Handbuch der Mineralchemic, pp. 413, 1015) for iserine from the Iserwiese, namely, 3 (FeO Ti 02)+Fe3 03. 126 PKOFESSOB KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. Oxide of Chromium , Cr2 03. Crystalline crusts prepared from oxychloride of chromium. Experiments with Naphtha A. Glass 3. Temperature of the Air 19°T. T. T'. t'. t. M. m. /• y- X. sp. H. 52-1 21-5 21*23 18*53 grms. 26*955 grms. 5*405 grm. 2*255 0*431 grm. 0*453 0*176 51-5 2T2 20*93 18*22 26*955 55 55 55 0*181 53-1 21-4 21*06 18*25 26*945 55 55 55 55 0*178 52-1 21*2 20*94 18*23 26*99 55 2*245 * 55 „ 0*175 Mean . . . 0T77 Hydrated Sesguioxide of Manganese Mn2 03-|-H2 Of. Fragments of good crystals of Manganite from Ihlefeld in the Harz, dried at 40° to 50°. Experiments with Naphtha A. Glass 3. Temperature of the Air 14°*6-14°*4. T. T'. t\ t. M. m. /• y- X . sp. H. c 0 o grms. grms. grm. grm. 47*0 17*1 16*82 13*83 26*985 8*31 1*855 0*431 0*453 0*174 45*6 17*0 16*69 13*83 26*94 55 55 55 55 0*173 45*7 17*0 16*73 13*85 26*92 ” 1*845* „ Mean 55 0*174 0*174 I made subsequently another series of experiments with a specimen from the same locality dried at the ordinary temperature. Experiments with Naphtha A. Glass 3. Temperature of the Air 17°*7— 1 7°*4. T. T'. t'. t. M. m. /• y- X. sp. H. o o 0 0 grms. grms. grm. grm. 52*0 20*5 20*15 17*06 26*95 8*04 1*77 0*431 0-453 0*178 52*3 20*3 2Q-02 16*86 26*975 55 55 55 55 0*180 51-9 20*1 19*77 16*65 26*965 55 55 55 55 0*178 51*6 20*1 19*84 16*80 26*995 55 1*75 % 55 55 0*174 Mean 0*178 The specific heat of manganite between 19° and 49° is 0T76, the mean of the averages of both series of determinations. * After drying the stopper. t “ Manganite dried at about 80°-90°, and then kept for half a day over sulphuric acid, gave in a ■water- determination, in which the water was collected in a chloride of calcium tube, 9-96 per cent, of water.” — Knop. The above formula requires 10-23 per cent, of water. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 127 47. Binoxide of Manganese, Mn 02. Pyrolusite from Ilmenau, dried at 100°-110°*. Experiments with Naphtha A. Glass 1. Temperature of the Air 14°*4-140,5. T. T'. ti. t. M. m. /• y- X . sp. H. 5T6 o 17-0 16-70 13-41 grins. 26-955 grms. 6-32 grms. 2-06 0-431 grm. 0-651 0-162 48-5 16-9 16-63 13-63 26-945 55 55 55 55 0-161 45-9 16-9 16-61 13-86 26-93 55 55 55 55 0-161 44-0 16-9 16-64 14-13 26-97 55 2-04 f 55 99 0-153 Mean . . . 0T59 Titanic Acid, Ti G2. I have investigated the one quadratic modification, rutile, and the rhombic modification Brookite or Arkansite ; I had no material for the investigation of anatase, the other quadratic modification. Rutile. Fragments of crystals from Saxony and from France. Experiments with Naphtha A. Glass 1. Temperature of the Air 130,5-130,7. T. T'. ti. t. M. m. /■ y- X. sp. H. 0 O o 0 grms. grms. grm. grm. 47-9 16-0 15-73 12-63 26-95 8-055 1-60 0-431 0-651 0-159 47-6 16-1 15-78 12-73 26-97 55 55 5? 0-158 45-2 15-9 15-56 12-73 26-965 55 55 „ ,, 0T56 45-6 16-1 15-84 13-01 26-965 55 l-58f „ 5? 0-156 Mean . . . 0T57 Brookite or Arkansite. Beautiful small crystals from hotsprings in Arkansas, puri- fied by treatment with hydrochloric acid from adherent oxide of iron. Experiments with Naphtha A. Glass 1. Temperature of the Air 16°T-160,3. T. T'. ti. t. M. m. /• y- X. sp. H. O o o o grms. grms. grm. grm. 47-1 18-2 17-94 15-22 26-97 8-00 1-415 0-431 0-651 0-160 49-3 18-5 18-23 15-22 26-96 55 ,, 5? 0-161 49-2 18-7 18-40 15-52 26-935 55 55 55 55 0T60 49-0 18-6 18-31 15-43 26-96 55 1-395 f 55 55 0-163 Mean . . . 0T61 .* This pyrolusite was not pure binoxide, but probably contained some manganite also. In experiments made by Mr. Oeseb in the Giessen laboratory, this pyrolusite, dried at 100° to 110°, gave, when heated in a current of dry air, the water being collected in a chloride of calcium apparatus, 1-21 per cent, of water ; treated with oxalic acid, 'as much carbonic acid was disengaged as corresponded to 95-36 per cent, of binoxide. As the specific beat of manganite (0-176) does not very much differ from that found for pyrolusite (0-159), I neglected to introduce a correction for the small quantity of manganite. t After drying the stopper. MDCCCLXV. T 128 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. Binoxide of Tin, Sn G2. Fragments of crystals of tinstone from Saxony. Experiments with Naphtha A. Glass 2. Temperature of the Air 140,5. T. T'. t'. t. M. m. /• y- X. sp. H. O O 0 0 grins. grms. grm. grm. 50-4 17-0 16-66 13-52 26-99 14-495 1-71 0-431 0-487 0-0906 46-6 16-4 16T4 13-33 26-925 55 55 55 55 0-0884 45-1 16-4 16-05 13-35 26-96 55 55 59 55 0-0905 45-7 16-3 16-04 13-32 26-98 55 1-695 * 55 „ 0-0882 Mean . . . 0-0894 48. Silicic Acid, Si 02. Pieces of transparent quartz (rock-crystal) from the Grimsel. I. — Experiments with Naphtha A. Glass 1. Temperature of the Air 17°-7-17°'4. T. T'. t'. t. M. m. /• y • X. sp. H. grms. grms. grm. grm. 53-8 20-1 19-83 17-03 26-99 4-88£ ► 1-58 0-431 0-651 0T86 52-5 19-8 19-53 16-77 26-96 55 5 5 55 55 0-193 51-8 19-7 19-43 16-77 26-98 55 55 55 55 0-185 51-7 19-7 19-42 16-76 26-945 55 55 55 55 0-186 52-7 19-7 19-35 16-64 26-96 55 1-56 * „ 55 0-182 Mean 0-186 II. — Experiments with Naphtha A. Glass 3. Temperature of the Air 19°T-19°-4. T. T'. t'. t. H. m. /• y- X. sp. H. O o o o grms. grms. grm. grm. 51-5 21-0 20-74 18-36 26-985 5-135 1-635 0-431 0-453 0-185 51-0 21-1 20-79 18-45 26-96 55 55 55 55 0-185 52-6 21-2 20-92 18-45 26-955 55 55 55 55 0-187 52-6 2i*2 20-89 18-42 26-97 55 1-62* „ 55 0-189 Mean 0-187 III. — Experiments with Naphtha B. Glass 3. Temperature of the Air 17°-8-17°-9. T. T'. t'. t. M. m. /• y- X. sp. H. 0 0 o o grms. grms. grm. grm. 50-0 20-0 19-69 17-27 26-98 5-645 1-70 0-419 0-453 0T75 50-5 19-9 19-64 17-14 26-97 ,, 55 55 55 0-184 50-0 20-1 19-82 17-40 26-99 „ 55 55 5J 0T81 50-0 20-0 19-66 17-22 26-975 1-685* „ 5J 0-178 Mean 0-180 * After drying the stopper. PEOEESSOE KOPP ON THE SPECIFIC HEAT OE SOLID BODIES. 129 IV. — Experiments with Water. Glass 1. Temperature of the Air 170,8-18°-3. T. T'. t'. t. M. m. /• > X. sp. H. O O o o grms. grms. grm. grm. 47-6 19-7 19-37 15-72 26-945 5-02 1-93 1-000 0-651 0-188 47-9 19-9 19-57 15-92 26-95 55 55 55 55 0-186 47-6 20-0 19-65 16-03 26-985 55 55 55 55 0-191 47-3 20-0 19-67 16-08 26-98 55 1-915* „ 0-196 Mean . . . 0T90 The average of these four means, 0T86, 0T87, 0T80, 0T90, gives 0T86 as the specific heat of quartz between 20° and 50°. It was interesting to determine also the specific heat of amorphous silicic acid. I ac- cordingly made experiments with opal and with hyalite, taking into account the water contained in these minerals. If the quantity of silica in the mineral taken is m , that of the water in it w, and z the specific heat of the water contained in the mineral, then, taking the other symbols in the sense hitherto assigned to them, the specific heat of the silica in the mineral can be calculated by the formula sp. H= M(t'—t) — (x+fy + wz) (T— T') m (T-T') But though the quantity of water contained in the (air-dried) minerals investigated is so small (scarcely exceeding 4 per cent.), the specific heat of silicic acid is found to be very different, according as (a) the specific heat z is put equal to 1, that of liquid water, (/3) or equal to 048, that of solid water or ice (which is at least correct for far the greater part of the water of these minerals, vide § 97). I give as follows, under a and (3, the numbers resulting from both calculations. Noble Opal from Honduras: yellowish, colourless in small pieces. The air-dried mineral contained 4-3 per cent, of water ; in the following experiments 4T2 grms. of opal were used, containing, therefore, 3- 943 grms. of anhydrous substances ( m ) and 0T77 grm. of water (w). Experiments with Naphtha B. Glass 3. Temperature of the Air 18°-5-18°-7. T. T'. t'. t. M. m. w. f. y. x. sp. H. o o o o grms. grms. grm. grm. grm. a. (}. 50- 4 20-6 20-34 18-10 26-98 3-943 0-177 1-69 0-419 0-453 0-175 0-198 52-6 20-6 20-32 17-84 26-985 „ „ „ „ „ 0-191 0-214 51- 9 20-6 20-32 17-92 26-98 „ „ „ „ „ 0-185 0-209 51-3 20-6 20-32 17-96 26-955 „ „ 1-67* „ „ 0-188 0-211 Mean . . . 0-185 0-208 Hyalite from Steinheim near Hanau. Small limpid spheroidal masses. The air- dried mineral contained 3-65 per cent, of water. In the following experiments 3‘795 * After drying the stopper. T 2 130 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. grms. of hyalite were used, which therefore contained 3*656 grms. of anhydrous sub- stance (m) and 0*139 grm. of water (w). Experiments with Naphtha B. Glass 1. Temperature of the Air 17°*8-17°*9. T. T'. t'. t. ■< M. m. w. f. y. x. sp. H. o o o o grms. grms. grm. grm. grm. a. (i. 50*4 19*8 19*50 17*26 26*98 3*656 0*139 1*345 0*419 0*651 0*170 0*190 0*172 0*192 0*175 0*194 0*173 0*193 0*173 0*192 In another series of experiments 4*475 grms. of hyalite were used, containing 4*312 grms. anhydrous substance (m) and 0*163 grm. water (w). Experiments with Water. Glass 1. Temperature of the Air 17° *1-17°*2. T. r. t'. t. M. m. w. /• y- X . sp. H. O o o o grms. grms. grm. grm. grm. a. /3. 43*5 18*9 18*55 15*41 26*97 4*312 0*163 1*88 1*000 0-651 0*174 0*193 42*7 19*1 18*83 15*79 26*99 55 55 55 55 55 0*182 0*201 42*7 19*2 18*87 15*84 26*955 55 „ 55 55 55 0*181 0*201 42*9 19*2 18*94 15*92 26*955 55 55 1*865* „ Mean . 55 0*175 0*195 0*178 0*197 The specific heat of amorphous silica must lie between the numbers standing under a and (3, and coming nearer those under (3. It does not seem to differ materially from that found for crystallized silica. 49. Molybdic Acid, Mo Os. Greyish-white powder, which, when heated in a porce- lain crucible, became permanently bright grey : the results are not trustworthy. Experiments with Naphtha A. Glass 3. Temperature of the Air 19°*5-20°*1. T. T'. t'. t. M. m. /• y • X . sp. H. o o 0 0 grms. grms. grms. grm. 51*4 20*9 20*64 18*44 26*99 2*27 2*65 0*431 0*453 0*155 51*3 21*3 21*04 18*88 26*97 55 55 „ 0*153 51*5 21*4 21*12 18*94 26*995 55 >5 55 55 0*159 51*2 21*4 21*06 18*93 26*96 55 2*635 * 55 55 0*149 Mean . , * 0*154 50*8 19*8 19*51 17*23 26*98 50*4 19*8 19*53 17*27 26*97 51*4 19*8 19*53 17*21 26*98 1*33* IVfpnn After drying the stopper. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 131 Tungstic Acid , W 03. Yellow powder. Experiments with Naphtha A. Glass 1. Temperature of the Air 19o,5-20°T. T. T'. t'. t. M. m. f. y. x. sp. H. o o o o grms. grms. grm. grm. 52T 21-3 21-02 18-60 26-98 6*89 1-965 0-431 0-651 0-0902 52-8 21-5 21-16 18-73 26-99 „ „ „ „ 0-0868 50- 5 21-4 21-14 18-84 26-965 „ „ „ „ 0-0919 51- 9 21-6 21-29 18-93 26-985 „ 1-95* „ „ 0-0886 Mean . . . 0-0894 Of the above pulverulent metallic acids only small quantities were used, and their thermal action was only a small proportion of the whole thermal action observed. The results can only be considered as approximations to the true specific heat. 50. Chloride of Sodium, Na Cl. Pure chloride of sodium fused. Experiments with Naphtha A. Glass 1. Temperature of the Air 10o"9-ll°-5. T. T'. t'. t. M. m. /• y- X. sp. H. O o 0 o grms. grms. grm. grm. 45-8 12-3 11-97 9-34 26-91 3-65 1-57 0-431 0-651 0-215 45-5 12-7 12-44 9-88 26-94 55 55 ,, 0-212 45-7 13-0 12-74 10-20 26-99 55 1-56* 55 „ 0-212 Mean . . . 0-213 Almost clear pieces of rock-salt, sharply dried. Experiments with Naphtha A. Glass 2. Temperature of the Air 10°-9-ll°-5. T. T'. t'. t. M. m. /• y- X . sp. H. o 0 0 o grms. grms. grms. grm. 44-8 12-6 12-32 9-63 26-95 3-955 2-025 0-431 0-487 0-225 45-8 13-0 12-73 10-04 26-935 55 55 55 55 0-214 44-6 13-3 13-01 10-43 26-95 55 2-015 * „ Mean ” 0-219 0-219 Chloride of Potassium, K Cl. Pure salt fused f . I. — Experiments with Naphtha A. Glass 2. Temperature of the Air 12°T-12°-2. T. T'. t'. t. M. m. f. y. x. sp. H. o o o o grms. grms. grm. , grm. 46-3 14-0 13-73 11-24 26-98 3-665 2-265 0-431 0-487 0-168 45-7 14-2 13-86 11-44 26-99 „ „ „ „ 0-167 * After drying the stopper. t These experiments with fused chloride are more trustworthy than those with crystallized salt, which, however, are very near ; for the latter, in loose crystals, only in small quantity, filled the glass used in the determinations. The experiments with sharply dried crystallized chloride of potassium gave the following results : — 132 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. II. — Experiments with Naphtha A. Glass 2. Temperature of the Air 10°*9. T. T'. t'. t. M. m. /- y- X. sp. H. 46*0 o 12*7 12*41 9*98 grms. 26*95 grms. 3*685 grm. 1*915 0*431 grm. 0*487 0*178 45*6 12*8 12*53 10*15 26*96 „ 99 99 „ 0T75 46*4 13*0 12*74 10*34 26*955 99 99 99 99 0*169 45*0 12*9 12*64 10*34 26*975 99 1*90* 99 99 0*170 The mean of the preceding six determinations gives 0T71 as the specific heat of chloride of potassium between 13° and 46°. Chloride of Rubidium, Rb Cl. Pure salt fused. Experiments with Naphtha A. Glass 2. Temperature of the Air 14°*3-14°*5. T. T'. o t'. t. 0 M. grms. m. grms. /• grm. y- X. grm. sp. H. 47*9 16*1 15*84 13*64 26*96 5*22 1*835 0*431 0*487 0*112 46*0 16*2 15*92 13*83 26*975 99 99 „ 99 0*118 44*3 16*2 15*93 14*00 26*94 99 99 99 99 0*110 43*8 16*4 16*13 14*26 26*98 ” 1*82* 99 Mean 99 0*109 0*112 51. Chloride of Ammonium , NH4 Cl. I have made five series of experiments with different forms of this salt. Chloride of Ammonium , crystallized from pure aqueous solution in very small octa- hedra. I. — Experiments with Naphtha A. Glass 1. Temperature of the Air 12°T-11°*8 T. T'. t'. t. M. m. /• y- X. sp. H. 0 0 0 • o grms. grm. grms. grm. 51*3 13*7 13*43 10*39 26*96 1*445 2*255 0*431 0*651 0*387 44*9 13*7 13*44 10*93 26*99 „ 99 99 99 0*380 44*6 14*0 13*70 11*26 26*905 „ 2*245* „ 99 0*365 Mean . . . 0*377 I. — Experiments with Naphtha A. Glass 1. Temperature of the Air 12°-l-12°-2. T. T' t\ t. M. m. /• y- X. sp. H. o O 0 0 grms. grms. grms. grm. 44-1 13-7 13-39 11-11 26-945 1-795 2-485 0*431 0-651 0-166 47*0 14-1 13-84 11-42 26-96 » » 99 0-145 II.- -Experiments with Naphtha A. Glass 1. Temperature of the Air 12°-9. 45-6 14-5 14-22 11-90 26-945 2-365 2-125 0-431 0-651 0-187 45-7 14-4 14-14 11-90 26-98 ,, }J 0-154 46-5 14-7 14-43 12-14 26-955 2-115* „ 0-160 * After drying the stopper. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 133 II. — Experiments with Naphtha A. Glass 2. Temperature of the Air 120,9. T. T'. t'. t. M. m. /• y- X. sp. H. O o 0 o grms. grm. grms. grm. 47-0 14-5 14-24 11-45 26-93 1-88 2-495 0-431 0-487 0-399 45-0 14-8 14-46 11-93 26-98 95 55 55 55 0-371 45-1 14-8 14-46 11-93 26-99 ” 2-485* „ Mean 55 0-370 0-380 Only a small quantity of this finely crystallized chloride of ammonium goes into the glasses which I used for the experiments. Hence I also investigated chloride of ammo- nium in more compact pieces. Long fibrous pieces from a sublimation cake : III. — Experiments with Naphtha A. Glass 2. Temperature of the Air 12°T-11°'8. T. T'. t'. t. M. , m. /• y- X. sp. H. 0 0 o o grms. grms. grms. grm. 45-5 13-9 13*63 10-73 26-97 2-76 2-20 0-431 0-487 0-377 45-1 14-2 13-92 11-07 26-97 „ 55 55 55 0-381 44-2 14-2 13-93 11-20 26-98 „ 2-19* „ Mean 55 0-371 0-376 From the so-called “ gas liquor,” Noellner has prepared a very pure chloride of am- monium, apparently in quadratic trapezoedra. With such crystals, 8 to 10 millims. long, I made the following determinations : — . — Experiments with Naphtha A. Glass 1. Temperature of the Air 14°-1- T. T'. t. t. M. m. /• y- X. sp. H. o o o o grms. grm. grms. grm. 48-5 15-9 15-63 12-84 26-99 1-978 2-085 0-431 0-651 0-384 44-7 16-0 15-73 13-32 26-93 „ 55 55 55 0-360 44-8 16-0 15-70 13-32 26-97 59 2-075* „ Mean ” 0-346 0-363 Finally, I examined chloride of ammonium which had crystallized, from a solution containing urea, in beautiful transparent cubes of 2 to 3 millims. in the side. V. — Experiments with Naphtha A. Glass 2. Temperature of the Air 14°T-13°-8. T. o T'. t'. o t. o M. grms. m. grms. /• grms. y- X. grm. sp. H. 45-2 16-0 15-73 13-05 26-92 2-595 2-34 0-431 0-487 0-376 44-4 16-1 15-83 13-25 26-975 55 55 95 55 0-371 45-7 16-4 16-08 13-45 26-96 55 2-33* „ Mean 55 0-358 0-368 The mean of the means of the five series of determinations, 0-377, 0-380, 0-376, 0-363, 0-368, gives 0-373 for the specific heat of chloride of ammonium between 15° and 45°. * After drying the stopper. 134 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 52. Chloride of Mercury, Hg Cl2. Well-dried crystals. Experiments with Naphtha A. Glass 1. Temperature of the Air 9°*2. T. T'. t'. t. M. m. /• y- oc. sp. H. O o 0 o grms. grms. grms. grm. 45*2 11*5 11*17 8*86 26*985 6*07 1*885 0*431 0*651 0*0636 44*3 11*2 10*90 8*50 26*99 55 2*105* 55 5J 0*0657 46*1 11*5 11*21 8*72 26*915 55 2*10f 55 0*0628 Mean . . . 0*0640 Chloride of Magnesium , Mg Cl2. Pieces of a beautiful preparation which had solidi- fied with crystalline structure after being melted. Experiments with Naphtha A. Glass 1. Temperature of the Air 13°*2. T. T'. t'. t. M. m. /• y- X. sp. H. o o 0 o grms. grms. grms. grm. 47*5 14*8 14*53 12*13 26*98 2*235 2*01 0*431 0-651 0*207 46*4 15*0 14*72 12*43 26*98 55 55 55 55 0*201 45*6 15*1 14*84 12*63 26*96 55 2*115* „ 55 0*175 46*9 15*3 15*03 12*73 26*945 55 2*105f „ Mean 55 0*180 0T91 Chloride of Barium , Ba Cl2. Pieces of a specimen which was of a dead white colour after solidifying. Experiments with Naphtha A. Glass 1. Temperature of the Air 14°*4. T. T'. t'. t. M. m. /. y- X. sp. H. o o 0 0 grms. grms. grm. grm. 46*2 16*2 15*87 13*64 26*975 6*795 1*72 0*431 0*651 0*0902 48*0 16*3 16*02 13*64 26*96 55 55 55 „ 0*0930 47*1 16*3 16*03 13*73 26*945 55 55 55 „ 0*0912 46*4 16*2 15*94 13*73 26*97 55 l*705f 55 55 0*0865 Mean . . . 0*0902 Crystallised Chloride of Barium, Ba Cl2+ 2H20. Crystals dried in vacuo. Experiments with Naphtha A. Glass 3. Temperature of the Air 16°T-16°*8. T. T'. t'. t. M. m. /• y- X . sp. H. o o 0 o grms. grms. grms. grm. 45*5 17*6 17*34 15*04 26*975 5*055 2*14 0*431 0*453 0*168 47*1 17*8 17*50 15*03 26*955 55 55 55 55 0*177 47*0 18*0 17*74 15*33 26*975 5J 55 55 0*171 46*2 18*2 17*94 15*63 26*965 55 2*125f 55 55 0*169 Mean . . . 0*171 * After adding some more naphtha. (The naphtha was apparently sucked up by the crystals of chloride of mercury, hence more naphtha was added. The liquid formed a smeary border at the side of the glass, but there was no deliquescence of the crystals in the naphtha.) f After drying the stopper. PEOFESSOE KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 135 Chloride of Chromium, €r2 Cl6. Violet insoluble chloride of chromium twice boiled out with water, washed and dried at 130°. As a porous mass this substance is but ill suited for an accurate determination of the specific heat. I pressed it, by means of a glass rod, in a glass tube into small disks, between which the naphtha could circulate. Th e object of this is to prevent a stagnation of the liquid absorbed by the solid mass, in consequence of which the water of the calorimeter assumes its maximum more slowdy, and hence the specific heat is found too low (compare §§ 18 & 24) ; but this object is not quite attained in this way*. Experiments with Naphtha A. Glass 1. Temperature of the Air ll0-4-ll°-5. T. T'. t'. t. M. m. /• y- X. sp. H. O O o o grms. grms. grms. grm. 47-5 13-2 12-86 10-32 26-93 3-165 2-095 0-431 0-651 0-139 47-5 13-0 12-73 10-13 26-97 55 55 55 „ 0-151 43-8 12-9 12-63 10-33 26-945 55 55 55 55 0-143 46-0 13-0 12-65 10-21 26-94 55 2-085f „ 55 0-140 Mean . . . 0T43 I should have liked to determine the specific heat of a solid metallic chloride of the formula 11 Cl3, and tried with chloride of antimony, but it coloured naphtha yellow when poured upon it, and became itself milky white, forming a heavy layer below the naphtha, and fused completely a little above 40°. 53. Chloride of Zinc and Chloride of Potassium, ZnK2Cl4. Crystals dried at 100° to 110°$. Experiments with Naphtha A. Glass 1. Temperature of the Air 14°-3-14°-5. T. T'. i. t. M. in. /• y- X. sp. H. o o o 0 grms. grms. grms. grm. 48-7 16-2 15-93 13-53 26-915 3-01 2-02 0-431 0-651 0-155 47-1 16-3 16-04 13-77 26-965 55 ,, 55 55 0-155 46-5 16-4 16-12 13-92 26-955 55 „ 55 0-150 44-1 16-4 16-14 14-13 26-94 55 2-00f 55 „ 0-147 Mean . . . 0T52 * The above source of error was of more importance, and the experiments gave far lower numbers for the specific heat of chloride of chromium when this body was not formed in disks, but just placed in the vessel and moderately lightly pressed. The following results were obtained in this manner : — Experiments with Naphtha A. Glass 2. Temperature of the Air ll°-5. T. T'. t'. t. M. m. /• y- X . sp. H. 46-4 O . 13-4 13-12 10-52 grms. 26-915 grms. 2-425 grms, 3-035 0-431 grm. 0-487 0-134 45-6 13-8 13-53 11-04 26-985 „ „ 0-131 45-7 13-8 13-52 11-02 26-99 yy yy 0-132 45-6 13-8 13-48 11-02 26-95 „ 3-015f yy 0-123 f After drying the stopper. + “ These crystals were deposited from a solution which contained for one equivalent of chloride of potassium MDCCCLXV. U 136 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. Hydrated Chloride of Copper and Potassium , €uK2Cl4+2H2G. Air-dried crystals. Experiments with Naphtha A. Glass 3. Temperature of the Air 17°-0-17°-2. T. T'. t'. t: M. m. /• y- X. sp. H. O o o o grms. grms. grm. grm. 51-4 19-1 18-80 16-33 26-95 4-085 1-86 0-431 0-453 0-197 50-4 19-0 18-66 16-26 26-94 55 55 55 55 0-197 50-0 19-1 18-77 16-43 26-955 „ 55 55 0-193 49-2 19-0 18-68 16-35 26-95 59 1* *84* 55 55 0-204 Mean . . . 0-197 Chloride of Tin and Potassium, Sn K2 Cl6. Crystals dried at 105°- Experiments with Naphtha A. Glass 3. Temperature of the Air 16°-4-17°-3. T. T'. t'. t. M. m. /. y- x. sp. H. Q Q o - o grms. grms. grm. grm. 50-1 18-3 17-97 15-70 26-96 5-305 1-77 0-431 0-453 0-134 51-1 18-7 18-42 16-12 26-93 9 9 55 55 „ 0-131 49-5 18-7 18-36 1.6-19 26-955 55 55 55 „ 0T29 49-1 18-8 18-52 16-34 26-965 „ 1-76* 55 „ 0-137 Mean . . . 0-133 Chloride of Platinum and Potassium, Pt K2 Cl6. Well-formed small'crystals. Experiments with Naphtha A. Glass 2. Temperature of the Air ll°-5-ll°-2. T. T\ t'. t. M. m. /• y- X. sp. H. O O o o grms. grms. grm. grm. 44-3 13-2 12-91 10-55 26-93 7-25 1-55 0-431 0-487 0-122 46T 13-4 13-06 10-67 26-975 55 55 „ 55 0-113 47-9 13-5 13-18 10-68 26-975 55 55 55 0-111 48-1 13-5 13-23 10-76 26-98 1-535 * 55 55 0-107 Mean . . . 0-113 at least two equivalents of chloride of zinc. In the analyses (the potassium was not determined) there were— Found 24-0 per cent. Zinc, 49-3 and 49-6 Cl. Calculated .... 22-85 per cent. Zn, 49*75 per cent. Cl, and 27*40 K. “ The crystals were only pressed between paper, and hence were impregnated with some mother-liquor, which explains the excess of zinc found.” — Engelbach. * After drying the stopper. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 137 54. Fluoride of Calcium , €a Fl2. Cleavage pieces of fluor-spar from Miinsterthal in Baden. Experiments with Naphtha A. Glass 1. Temperature of the Air 18°-4-19T. T. T'. t'. t. M. m. /• y- X . sp. H. 50-5 20-7 20-42 17-67 grms. 26-985 grms. 5-675 grin. i 1-56 0-431 grm. 0-651 0-206 49-9 20-4 20-07 17-33 26-94 „ 99 99 0-208 50-1 20-5 20-22 17-43 26-97 95 ii 0-215 49-9 20-6 20-26 17-53 26-965 ii 99 99 0-209 50-5 20-8 20-49 17-75 26-98 „ T54: 99 9/ 0-207 Mean 0-209 Cryolite , A1 Na3 Fl6. Comminuted cryolite from Greenland, smartly dried. Experiments with Naphtha A. Glass 2 !. Temperature of the Air 19° •2-19°-5. T. T'. t'. t. M. m. /• y- X . sp. H. 50-6 21*5 21-21 18-44 grms. 26-975 grms. 5-55 grm. 1-775 0-431 grm. 0-453 0-243 50-0 21-5 21-15 18-43 26-965 ,, 99 99 99 0-244 49-6 21-5 21-17 18-53 26-965 99 99 99 99 0-237 50-6 21-6 21-27 18-56 26-985 99 „ 99 99 0-235 51-0 21-6 21-34 18-62 26-99 99 1-75* „ „ 0-232 Mean 0-238 55. Cyanide of Mercury, Hg C2 N2. Well-dried crystals. Experiments with Naphtha A. Glass 2. Temperature of the Air 9°-2. T. T'. t'. t. M. m. /• y- X. sp. H. 45-2 o 11-2 10-86 8-34 grms. 26-935 grms. 6-555 grm. 1-955 0-431 grm. 0-487 0-100 47-0 11-5 11-23 8-62 26-965 99 99 99 99 0-098 49-5 11-7 11-43 8-64 26-955 99 99 99 0-099 43-7 11-5 11-22 8-84 26-95 „ 1-94* 99 „ 0-101 Mean 0-100 Cyanide of Zinc and Potassium , Zn K2 G4 N4. Distinct crystals. I made four series of experiments with this substance. Crystals dried in vacuo. I. — Experiments with Naphtha A. Glass 2. Temperature of the Air ll°-8-ll°*5. T. T'. t'. t. M. m. /• V' X . sp. H. 44-9 13-8 13*53 11-13 grms. 26-96 grms. 2-515 grms. 2-195 0-431 grm. 0-487 0-257 48-0 13-9 13-64 11-13 26-93 ii 99 99 99 0-218 46-9 13-9 13-57 11-12 26-94 „ 99 99 0-225 45-0 13-9 13-63 11-34 26-975 ii 2-175* „ 99 0-223 Mean . . . 0-231 * After drying the stopper. 138 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. II. — Experiments with Naphtha A. Glass 2. Temperature of the Air 12°-4-12°*3. T. T'. t'. t. M. m. /• y- X . sp. H. O o o o grms. grms. grms. grm. 45-5 14-5 14-15 11-83 26-97 2-465 2-225 0-431 0-487 0-232 46-7 14-5 14-22 11-74 26-97 „ 99 99 99 0-256 45-2 14-3 13-96 11-72 26-945 99 2-17* 99 99 0-215 45-2 14-5 14-23 11-95 26-92 „ „ 99 99 0-234 Mean . . . 0-234 Crystals dried at 100°. III. — Experiments with Naphtha A. Glass 1. Temperature of the Air ll°-8-ll°-5. T. T'. t'. t. M. m. /• y- X. sp. H. 46-6 13-5 13-20 10-74 grms. 26-955 grms. 2-415 grm. 1-665 0-431 grm. 0-651 0-263 48-5 13-8 13-53 10-96 26-99 99 99 99 0-261 44-3 13-6 13-26 11-05 26-99 „ 99 99 99 0-238 45-2 13-6 13-32 11-04 26-93 „ l-655f 99 99 0-240 Mean . . . 0-251 IV. — Experiments with Naphtha A. Glass 1. Temperature of the Air ll°-2-ll-3. T. o T'. o t'. o t. o M. grms. m. grms. /• grm. V’ X. grm. sp. H. 49-4 13-3 13-04 10-43 26-94 2-255 1-78 0-431 0-651 0-235 46-7 13-4 13-11 10-62 26-98 99 99 99 „ 0-266 49-2 13-6 13-33 10-72 26-955 99 99 99 55 0-247 48-0 13-5 13-22 10-73 26-97 99 l-765f „ Mean 55 0-237 0-246 The specific heat of cyanide of zinc and potassium between 14° and 46° is 0-241 as the mean of the averages of the four series of determinations, 0-231, 0-234, 0-251, 0-246. Crystallized Ferrocyanide of Potassium , Ee K4 G6 N6+ 3 H2 G. Fragments of air-dried crystals. Experiments with Naphtha A. Glass 1. Temperature of the Air 19°-2. T. T'. t'.% t. M. m. /• y • X. sp. H. o O o o grms. grms. grm. grm. 50-6 21-3 21-03 18-46 26-98 3-425 1-69 0-431 0-651 0-288 51-3 21-1 20-82 18-22 26-98 99 99 99 99 0-275 51-0 21-0 20-74 18-14 26-97 99 99 99 99 0-280 51-0 21-1 20-84 18-26 26-965 99 l-675f „ Mean 99 0 278 0-280 * After removing some naphtha on the stopper, t After drying the stopper. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. Ferridcyanide of Potassium, Fe K3 €6 N6. Well-formed crystals, smartly dried. Experiments with Naphtha A. Glass 2. Temperature 13°*2. T. T'. t'. o o t. o M. grins. m. grms. /• grms. y • X. grm. sp. H. 48-5 15-3 15-01 12-23 26*95 3-63 2-025 0*431 0*487 0*247 45-1 15-0 14-66 12-20 26-92 55 55 55 „ 0*232 47T 15-5 15-23 12-68 26-975 55 55 55 55 0*225 44*4 15-3 15-00 12-64 26*98 55 2-015* 55 Mean 55 0*229 0*233 56. Nitrate of Soda, Na NG3. Crystallized salt, briskly dried. Experiments with Naphtha A. Glass 2. Temperature of the Air 11°*8. T. T'. t'. t. M. m. /• y- X. sp. H. o O o o grms. grms. grms. grm. 47*2 14*3 13*95 11*02 26*91 3-645 2*25 0*431 0*487 0*258 46*2 14*9 14*55 11*82 26*945 55 55 55 ,, 0*245 46*5 14*3 14-02 11*13 26*93 55 55 55 „ 0*263 44*3 14*1 13-84 11*15 26*945 55 2-235* „ 55 0*261 Mean . . . 0*257 Fused Salt. Experiments with Naphtha A. Glass 1. Temperature of the Air 11°*8. T. o T'. o t'. o t. o M. grms. m. grms. /• grm. y- X. grm. sp. H. 47*8 13*9 13*62 10*57 26*98 3*92 1*66 0*431 0*651 0*271 43*9 14*3 14*03 11*43 26*065 ,, 55 55 55 0*256 43*6 14*6 14*33 11*83 26*925 55 55 55 55 0*243 46-4 14*5 14*22 11*43 26*965 ” 1*65* Mean 55 0*254 0^ Nitrate of Potass , K N G3. Smartly dried crystallized salt. Experiments with Naphtha A. Glass 1. Temperature of the Air 12°T-12°*4. T. T'. t’. t. M. m. /• y- X. sp. H. 44*2 o 14*2 13*88 11*43 grms. 26*93 grms. 3*105 grm. 1*845 0*431 grm. 0*651 0*242 46*5 14*4 14*14 11*56 26*99 55 55 0*233 45*6 14*3 14*03 11*53 26*97 55 55 55 0*228 44*7 14*0 13*74 11*31 26*98 55 1*83* 55 55 0*224 Mean . . . 0-232 After drying the stopper. 140 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. Fused Salt. Experiments with Naphtha A. Glass 2. Temperature of the Air 12°T-12°-4. T. T'. t'. t. M. m. /• y- X. sp. H. O O o o grms. grms. grms. grm. 46-6 14-5 14-20 11-53 26-94 3-745 2-035 0-431 0-487 0-234 45-9 14-4 14-14 11-56 26-935 55 55 55 55 0-225 46-1 14-3 14-03 11-44 26-96- 55 55 55 55 0-222 44-7 14-1 13-83 11-32 26-96 55 2-02* „ 0-228 Mean . . . 0-227 57. Nitrate of Ammonia, N2H403. Vitreous transparent pointed crystals, like those of nitre ; dried in vacuo over sulphuric acid. I. — Experiments with Naphtha A. Glass 2. Temperature of the Air 10°-9. T. T'. £. t. M. m. /• y- X. sp. H. o 32-3 12-7 12-43 10*53 grms. 26-92 grms. 2-555 grms. 2-41 0-431 grm. 0-487 0-424 31-1 12-8 12-52 10-66 26-945 55 55 55 55 0-475 29-2 12-6 12-33 10-63 26-92 55 55 55 55 0-482 33-5 13-1 12-81 10-74 26-93 55 2-405* „ 55 0-473 Mean . . . 0-463 . — Experiments with Naphtha A. Glass 2. Temperature of the Air 140,4-15r T. T'. t'. t. M. m. /• . y- X . sp. H. O 32-4 15-9 15-57 14-02 grms. 26-96 grms. 2-025 grms. 2-29 0-431 grm. 0-487 0-455 30-8 15-7 15-44 14-03 26-975 55 55 55 55 0-449 31-5 16-0 15-66 14-23 26-95 55 5 5 55 55 0-435 32-9 16-2 15-93 14-37 26-97 55 55 55 0-449 Mean . . . 0-447 The specific heat of nitrate of ammonia between 14° and 31° is as the mean of the averages of both series of experiments, 0-463 and 0-447, = 0-455. The crystals were quite unchanged at this temperature. In these experiments the difference of temperature T — T' was but small, and it would not be surprising to find even greater deviations among the individual results than are exhibited by the above numbers in the last column. Nitrate of ammonia cannot be heated much above 30°, because it then undergoes a molecular change, which apparently is accompanied by disengagement of heat. This was observed in a series of experiments in which the heat was raised to 45° or 48°; the crystals which, dried in vacuo , were originally of a vitreous lustre and transparent, became, like the crystals dried at 100°, milky-white, porous. * After drying the stopper. PEOFESSOE KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 141 and absorbent of naphtha. In these experiments the following numbers were obtained. Experiments with Naphtha A. Glass 2. Temperature of the Air 12°T-12°-4. T. T'. t'. t . M. m. /• y X . sp. H. o O o o grms. grms. grms. grm. 44-9 14-8 14-53 11-23 26-935 2-69 2-295 0-431 0-487 0-549 45-9 14-9 14-62 11-23 26-94 99 99 99 ,, 0-546 47-6 14-6 14-32 10-70 26-925 99 2*445* 99 99 0-531 46-4 15-0 14-73 11-24 26-98 99 2-425f 99 0-545 The numbers for the specific heat of nitrate of ammonia are throughout greater than those found between 14° and 31°; and probably because through the heating to 45° or 48° the change was set up during the experiments. Experiments with nitrate of ammonia in which, by drying at 100°, this change had been effected before making the experiments, gave numbers which more closely approach the first set, though somewhat greater, and on the whole not very concordant. I obtained in a series of experiments the following results with dull milky crystals dried at 100°. Experiments with ' Naphtha A. Glass 1. Tempe: rature of the Air 9°-7. T. T'. t\ t. M. m. /. y- X. sp. H. O O o o grms. grms. grms. grm. 45-0 12-3 11-95 8-96 26-975 '2-03 1-77 0-431 0-651 0-519 45-6 12-3 12-03 9-01 26-935 33 99 „ 0-507 44-9 12-6 12-26 9-32 26-965 1-90* 99 99 0-485 45-1 12-5 12-24 9-31 26-98 33 99 99 0-470 45-4 12-6 12-33 9-32 26-965 „ 2-08$ 99 99 0-457 Crystals dried at 100°-110°, which apparently had been softened, gave the following numbers. Experiments with Naphtha A. Glass 1. Temperature of the Air 12°T-12°-4. T. T\ t'. t. M. m. /. y. x. sp. H. O 0 o 0 grms. grms. grms. grm. 44-6 14-2 13-93 11-03 26-97 2-095 1-91 0-431 0-651 0-524 43-6 14-4 14-13 11-42 26-935 99 99 99 „ 0-489 47-8 14-8 14-54 11-44 26-975 „ 2-04* „ 0-479 46-5 14-6 14-32 11-23 26-96 „ 2-02f „ „ 0-520 I do not know the nature of the change which nitrate of ammonia undergoes fust above 40°. * After adding some naphtha. t After drying the stopper. $ After more naphtha. 142 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 58. Nitrate of Strontia, Sr N2 06. Crystallized, dried at 100°. Experiments with Naphtha A. Glass 3. Temperature of the Air 14°*9-16°-0. T. T'. t\ t. M. m. /• y- CC. sp. H. O o o o grms. grms. grms. grm. 46-0 16-6 16-33 13-95 26-955 4-575 2-10 0-431 0-453 0-180 46-8 17-1 16-83 14-43 26-95 *9 99 99 99 0-179 46-7 17-1 16-84 14-44 26-935 99 99 99 99 0-180 47-9 17-2 16-93 14.43 26-975 99 2-085* „ „ 0-185 Mean . . . 0T81 Nitrate of Baryta, Ba N2 06. Crystals dried at 100°. Experiments with Naphtha A. Glass 2. Temperature of the Air 130,3-1 3°*4. T. o T'. o t'. o t. o M. grms. m. grms. /• grms. y- X. grm. sp. H. 48-7 15-3 15-23 12-52 26-98 4-995 2-255 0-431 0-487 0-149 48-5 15-4 15-13 12-43 26-985 99 99 99 „ 0-149 47-1 15-5 15-23 12-72 26-955 99 99 „ 0-137 46-1 15-6 15-32 12-85 26-95 99 2-24* 99 Mean 55 0-146 (KL46 Nitrate of Lead, Bb N2 06. Crystals dried at 100°. Experiments with Naphtha A. Glass 1. Temperature of the Air 13°-3-13°-4. T. T'. t\ t. M. m. /• y. X. sp. H. o O o 0 grms. grms. grm. grm. 46-8 15-7 15-35 12-73 26-925 7-955 1-675 0-431 0-651 0-113 48-2 15-8 15-53 12-82 26-98 99 99 99 0-111 48-1 16-1 15-83 13-22 26-965 99 99 99 0-104 45-0 15-9 15-57 13-15 26-99 99 1-655* „ Mean 55 0-111 0-110 59. Chlorate of Potass, K C103. Pure well-dried crystals. Experiments with Naphtha A. Glass 1. Temperature of the Air 16°-4-17°-3. T. T'. t'. t. M. m. /• y- X. sp. H. 50-6 18-4 18-12 15-63 grms. 26-97 grms. 2-485 grms. 2-18 0-431 grm. 0-651 0-199 50-0 18-6 18-25 15-83 26-945 99 99 99 0-196 48-3 18-8 18-45 16-22 26-95 99 99 99 0-180 48-4 18-8 18-53 16-24 26-96 „ 2-165* 99 99 0-202 Mean . . . 0-194 * After drying the stopper. PKOFESSOE KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 143 Crystallized Chlorate of Baryta, Ba Cl2 06+H2 O. Crystalline crusts, dried in vacuo. Experiments with Naphtha A. Glass 1. Temperature of the Air 14°*3-14°*4. T. T'. t'. t. M. m. /. y- X. sp. H. Q o 0 o grms. grms. grms. grm. 46*7 16*1 15*83 13*53 26*97 3*02 2*135 0*431 0*651 0*151 46*2 16*2 15*92 13*62 26*915 99 99 99 99 0*163 46*5 16*1 15*76 13*45 26*95 99 99 99 99 0*158 46*5 16*1 15*83 13*53 26*99 „ 2*13* 0*157 Mean . . . 0*157 Perchlorate of Potass, K Cl 04. Well-formed crystals. Experiments with Naphtha A. Glass 2. T. T'. t'. t. M. m. o o o o grins. grms. 46*6 13*7 13*43 11*02 26*93 3*205 45*7 13*6 13*33 10*94 26*98 44*9 13*7 13*43 11*10 26*955 44*0 13*6 13*33 11*04 26*945 Temperature of the Air 11°*5. y. x. sp. H. /• grms. 2*115 2*095* X. grm . 0*431 0*487 0*179 „ „ 0*190 „ „ 0*192 „ „ 0*199 Permanganate of Potass, K Mn 04. Crystals. Experiments with Naphtha A. Glass 1. Temperature of the Air 11°*5. T. T'. t'. t. M. m. /• y- X. sp. H. O o 0 o grms. grms. grm. grm. 44*3 13*7 13*43 11*02 26*955 3-655 1*83 0*431 0*651 0T87 45*6 13*7 13*43 10*94 26*955 99 99 99 99 0*181 46*0 13*8 13*51 11*03 26*99 99 99 99 0*175 46*2 13*7 13*44 10*95 26*935 99 1*815* 99 99 0*173 Mean . . . 0*179 60. Metaphosphate of Soda, NaP03. Prepared as a transparent vitreous mass by igniting phosphate of soda and ammonia. Experiments with Naphtha A. Glass 2. Temperature of the Air 14°*4-14°*5. T. T'. t'. t. M. m. /• y- x. sp. H. o o 0 o grms. grms. grm. grm. 49*1 16*7 16*37 13*54 26*92 4*70 1*845 0*431 0*487 0*227 48*3 16*8 16*45 13*75 26*975 99 99 99 „ 0*219 43*1 16*5 16*23 13*96 26*92 99 „ 0*216 43*3 16*7 16*44 14*23 26*935 99 1*83* 99 „ 0*205 Mean . . . 0*217 * After drying the stopper. MDCCCLXV. X 144 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. Phosphate of Silver , Ag3PG4: yellow powder dried at 110°. This substance, in the quantity I used, is but ill fitted for procuring accurate results. I have made two series of experiments with it, but the results obtained thereby are only to be considered as rough approximations. I. — Experiments with Naphtha A. Glass 1. Temperature of the Air 20°-5-20o,8. T. T'. t'. t. M. m. /• y- X. sp. H. O 0 o 0 grms. grms. grms. grin. 51-4 22-5 22-19 20-16 26-99 3-775 2-105 0-431 0*651 0-0895 52-0 22-4 22-14 20-12 26-955 33 33 3? 33 0-07451 51-5 22-5 22-16 20-13 26-965 33 33 33 33 0-0872 51-5 22-5 22-15 20-14 26-985 „ 2-095* „ 33 0-0839 Meanf . . . 0-0869 II. — Experiments with Naphtha A. Glass 3. Temperature of the Air 16°-3-16°-6. T. T'. t'. t. M. m. /• y- 00. sp. H. o 0 o grms. grms. grms. grm. 51-1 18-4 18-12 15-72 26-955 4-545 2-555 0-431 0-453 0-0933 51-5 18-4 18-13 15-73 26-995 33 53 ,, „ 0-0887 51-8 18-5 18-22 15-76 26-94 33 33 33 33 0-0959 51-6 18-6 18-33 15-93 26-98 33 2-54* 33 33 0-0911 Mean . . . 0-0923 The mean of both these means gives 0 0896 as the specific heat of phosphate of silver. This number, as already remarked, is but little trustworthy. But it may be concluded from these experiments that the specific heat of phosphate of silver cannot differ much from 0-09. Phosphate of Potass, K H2P 04. Clear crystals dried at 110°. Experiments with Naphtha A. Glass 1. Temperature of the Air 14°-9-16o,0. T. T'. t'. t. M. m. /• y- X . sp. H. 46-8 16-9 16-56 14-21 grms. 26-96 grms. 3-95 grm. 1-575 0-431 grm. 0-651 0-200 48-0 17-2 16-89 14-43 26-965 33 33 33 33 0-209 47-5 17-4 17-09 14-71 26-96 33 33 33 33 0-203 48-0 17-2 16-92 14-43 26-995 33 1-56* 33 33 0-218 Mean . . . 0-208 * After drying the stopper. f Excluding the second experiment. PROFESSOR KOPP GIST THE SPECIFIC HEAT OF SOLID BODIES. Arseniate of Potass, KH2As 04. Clear crystals dried at 105°. Experiments with Naphtha A. Glass 2. Temperature of the Air 14°*3-14°*4. T. T'. t'. t. M. m. /• y- X. sp. H. O 0 0 0 grms. grms* grms. grm. 47*1 16*2 15*93 13*43 26*96 4*455 2*05 0*431 0*487 0*182 47*5 16*2 15*92 13*43 26-975 99 99 99 0*174 45*1 16*1 15*84 13*54 26*955 „ 99 99 99 0*172 45*5 16*3 16*01 13*70 26*955 „ 2*045* 99 99 0*172 Mean . . . 0-175 61. Carbonate of Soda, Na2 G 03. Fused salt.* Experiments with Naphtha A. Glass 2. Temperature of the Air 150-5. T. T'. G t. M. m. /• . y ■ a?.' sp. H. o 0 o o grms. grms. grms. grm. 48*0 17*7 17*35 14*54 26*935 4*575 2*08 0*431 0*487 0*244 47*9 17*7 17*43 14*63 '26*95 99 99 ?5 0*244 48*1 17*7 17*40 14*53 26*985 . . 99 99 0*254 48-1 17*7 17*43 14*63 26*965 99' 2*055 * 99 * „ ' 0*243 Mean . . . 0*246 Carbonate of Potass, K2 C03. Fused salt. Experiments with Naphtha A. Glass 1. Temperature of the Air 15°* T. T'. t'. t. M. TO. /. X» sp. H. O o o o grms. grms. grm. grm. 47*4 .17*4 17*14 14*75 26*975 3*045 1*96 0*651 0*215 47*5 17*4 17*12 14*73 26*975 99 99 99 0*212 47*3 17*4 17*14 14*82 26*95 99 95 99 0*196 45*6 17*5 17*21 15*02 26*96 „ 1*95* 99 0*200 Mean . 0*206 Carbonate of Bubidium, Rb2 €03. Fused salt. Experiments with Naphtha A. Glass 2. Temperature of the Air 150-5. T. T'. t'. t. M. m. /• X. sp. H. o O 0 o grms. grms. grm. grm. 49*3 17*7 17*38 14*80 26*965 6*855 1*95 0*431 0*487 0*127 47*1 17*4 17*13 14*70 26*955 99 99 99 0*128 46*8 17*6 17*33 14*94 26*97 99 99 99 0*128 45*8 17*6 17*33 15*16 26*93 99 1*93* „ 0*110 Mean . . . 0*123 * After drying the stopper. 146 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 62. Carbonate of Lead, Pb C03. Cerussite from Washington mine, Davidson county, North Carolina : beautiful clear crystals. Experiments with Naphtha A. Glass 1. Temperature of the Air 130,8. T. T'. t'. t. 31. m. /• y* X. sp. H. 49-2 103 16*03 13-16 grms. 26-95 grms. 11-42 grm. 1-90 0-431 grm. 0-651 0-0772 49-8 16-0 15-68 12-72 26-94 55 55 55 ?? 0-0779 47-4 15-9 15-60 12-80 26-94 55 55 55 „ 0-0810 46-5 15-9 15-64 12-94 26-97 55 55 55 ?> 0-0797 43-2 15-8 15-55 13-14 26-96 „ 1-885* ?? 0-0795 Mean . . . 00791 Carbonate of Lime , €a C03. I have investigated both the rhombic and the rhom- bohedral modification. Arragonite. Fragments of clear crystals from Bilin, in Bohemia Experiments with Naphtha A. Glass 1. Temperature of the Air 13°*8. T. o T\ o t'. o t . o 31. grms. m. grms. A grm. y- X. grm. sp. H. 51-1 16-8 16-53 13-25 26-965 6-445 1-94 0-431 0-487 0-195 46-6 16-0 15-70 12-73 26-98 ?? 55 55 ?? 0-201 45-8 16-1 15-83 12-94 26-975 ?! 55 ?? 0-216 44-0 16-0 15-74 13-03 26-965 „ 55 55 „ 0-200. 44-3 15-9 15-63 12-86 26-955 ?? 1-92* 55 Mean ?? 0-204 0-203 Calcareous Spar. Cleavage pieces of transparent specimens from Auerbach, on the Bergstrasse. Experiments with Naphtha A. Glass 1. Temperature of the Air 14°-4-14°-7. T. T'. t'. t. 31. m. /■ y- cc. sp. H. o _ O 0 o grms. grms. grm. grm. 49-5 15-5 15-24 12-13 26-98 5-425 1-48 0-431 0-651 0-217 49-6 16-3 15-96 13-00 26-96 55 55 55 0-204 48-2 16-1 15-83 12-94 26-915 55 55 55 55 0-209 45-2 16-2 15-94 13-42 26-93 55 1-465* „ 55 0-195 Mean . . . 0-206 After drying the stopper. PEOFESSOB KOPP OX THE SPECIFIC HEAT OF SOLID BODIES. 147 63. Magnesian Spar, Ca^ Mgi C03*. Specimens of magnesian spar from the Zillerthal. Experiments with Naphtha A. Glass 3. Temperature of the Air 15°T-15°*9. T. T. f. t. IT. m, . /• y. X. sp. H. c 0 o grms. grms. grm. grm. 48*9 17*7 17*43 14*52 26*96 6*195 1*76 0*431 0*453 0*210 48*3 17*9 17*60 14*77 26*96 55 55 55 55 0*210 47*0 17*9 17*64 15*02 26*995 1*745 f ,, 0*198 Mean . . . 0*206 Spathic Iron, -F Mn^ Mg^ C03$ . Cleavage pieces of reddish crystals from Bieber, Hesse Cassel. Experiments with Naphtha A. Glass 1. Temperature of the Air 14°*6-14°*4. T. T. t'. t. 11. m . /• y- X . sp. H. o O 0 o grms. gnus. grm. grm. 47*7 17*0 16*74 13*92 26*98 6*56 1*78 0*431 0*651 0*162 45*6 16*9 16*63 13*94 26*93 „ 55 55 55 0*169 46*1 16*9 16*55 13*83 26*965 1*765 f „ 0*168 Mean . . . 0*166 64. Zircon, ZrSi04, or Irh SL 0.,. Hyacinth crystals from Ceylon. Experiments with Naphtha A. Glass 1. Temperature of the Air 18c*4-19°*8. T. T- t\ t. ll. rn. /• y- sp. H. o o o o grms. grms. grm. grm. 51*2 20*6 20*33 17*46 26*945 9*69 1*32 0*431 0*651 0T35 50*2 20*8 20*54 17*83 26*955 55 55 55 „ 0*131 51*0 21*0 20*74 18*01 26*97 55 55 „ 0*127 52*0 21*2 20*87 18*03 26*96 55 55 55 „ 0*131 51*1 21*3 21*03 18*24 26*93 55 l*30f „ „ 0*135 Mean . . . 0*132 * The results of my analysis of this spar (Ann. der Chem. nnd Pharm. Ixxxi. 50) are, compared with the numbers required by the above formula, as follows : — CaO COs. ITgOCO,. FeO CO/. Total. Found 54-3 42-2 37 100-2 Calculated .... 54-3 45-7 „ 100-0 t After drying the stopper. X The numbers found in my analysis of this spathic iron (Ann. der Chem. nnd Pharm. Ixxxi. 51) are given below, compared with those calculated on the above formula. FeO C02. HhO C02. CaOCO,. Mg0C02. Xb. Total. Found 73-7 19-0 0-9 6-6 0-7 100-9 Calculated .... 74-7 18-6 ,, 6-7 „ 100-0 “With some HnO C03. b Insoluble in aqua regia. 148 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. Chrysolite , Mg^. -Fe^. Si04*. From Dockweiler in the Eifel. Transparent to trans- lucent bright green crystalline fragments. Experiments with Naphtha A. Glass 1. Temperature of the Air 190,2-19°-5. T. T. t'. t. M. m. f. y • so. sp. H. G grms. grms. grm. grm. 5P3 21-4 21-14 18-53 26-985 5-84 1-475 0-431 0-657 0-183 50-4 21-4 21-13 18-55 26-965 „ 55 55 0T91 50-9 21-5 21-17 18-54 26-985 „ 55 9? 0-193 50-9 21-5 21-16 18-55 26-96 55 0-189 49-9 21-4 21-13 18-63 26-975 „ l-45f „ 99 0-187 Mean 0-189 Olivine , Mg* » Fe^ Si 04 J, , From a spheroidal mass surrounded by lava from the Eifel. Experiments with Naphtha A. Glass 1. Temperature of the Air 190, 0-19°-6. T. T'. t'. t. M. m. /. y- X , sp. H. 0 o 0 o grms, grms. grm. grm. 51-5 21-6 21-26 18-53 26-975 6-37 1-425 0-431 0-651 0-188 51-4 21*3 -20-97 18-22 26-975 ,, 59 0-188 51-5 21-6 21-25 18-52 26-975 „ 55 0T88 52-1 21-8 21-52 18-72 26-97 „ 1-41 f „ 99 0-194 Mean 0-187 65. Wollastonite, €a Si G; 5. Pure j pieces of Wollastonite from Finnland. Experiments with Naphtha A. Glass 1. Temperature of the Air 17°*2. T. T'. t'. t. M. m. f. y. x. sp. H. O O o o grms. grms. grm. grm. 51-0 19-4 19-12 16-33 26-955 5-31 1-81 0-431 0-651 0-179 50-5 19-1 18-76 16-01 26-945 5-9 5 9 55 55 0-175 50-0 19-2 18-92 16-19 26-98 95 95 55 55 0-181 50-7 19-4 19-13 16-40 26-97 l-785f „ 0-176 Mean . . . 0-178 * An analysis by Professor Knop gave tbe following results, which are collated with the numbers required by the above formula SiOs. MgO. FeO. Ah03. Total. Found 40-95 50-82 8-83 trace 100-60 Calculated .... 41-15 49-87 8-98 39 100-00 t After drying the stopper. t This olivine has the same composition as the above chrysolite. Professor Knop found for this olivine the following numbers, which are compared with those required by the above formula Si02. MgO. FeO. A1203. Total. Found ... 41-85 49-10 8-75 trace 99-70 Calculated .... 41-15 49-87 8-98 100-00 PROFESSOR EOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 149 Diopside, Mgj Si 03. Fragments of a greenish and white crystal of the charac- teristic aspect of the diopside from Schwarzenstein in the Tyrol. Experiments with Naphtha A. Glass 1. Temperature of the Air 16°’3-160-5, T. T'. t'. t. M. m. /• y- X. sp. H. G o 0 o - grms. grms. grin. grin. 48-1 18-7 18-42 15-65 26-99 6-17 1-55 0-431 0-651 0-186 49-4 18-4 18-13 15-22 26-98 55 55 55 0-185 51-8 18-6 18-25 15-13 26-98 55 55 55 0-185 50-8 18-8 18-54 15-53 26-925 55 1-53* 55 55 0-186 Mean . . . 0-186 Diqptase, €uSi03-j-H2O. Eine crystals from the Kirgisensteppe. Experiments with Naphtha A. Glass 3. Temperature of the Air,16°-7-T6°-4. T. T'. t'. t. M. m. /• y- X . sp. H. 49-8 18-9 18-63 16-04 grms. 26-94 grms. 5-545 grm. 1-80 0-431 grm. 0-453 0-186 50-3 19-1 18-76 16-17 26-95 55 55 55 5? 0-182 50-3 18-9 18-64 16-05 26-99 55 55 55 0-180 48-5 18-9 18-5.8 : 16T3 26-945 55 1-79* 55 55 0-181 Mean . . . 0-182 Qrthoclase, Al2 K2 Si6 016. Cleavage pieces of a flesh-coloured reddish orthoclase from Aschaffenburg. Experiments with Naphtha A. Glass 3. Temperature of the Air 18°‘4-19°T. T. T'. t\ t. M. m. /• y- X. sp. H. 0 O 0 o grms. grms. grm. grm. 50-6 20-2 19-86 17-42 26-945 5-185 1-78 0-431 0-453 0-182 49-6 20-3 20-00 17-63 26-95 55 55 55 „ 0-185 51-1 20-5 20-15 17-71 26-94 55 55 55 55 0-179 51-2 20-5 20-21 17-73 26-965 55 1*77* „ 55 0-186 Mean . . . 0-183 Albite, Al2 Na2 Si6 0i6. Fragments of white crystals from Pfunders, in Tyrol. Experiments with Naphtha A. Glass 3. Temperature of the Air 180-7-19°-8. T. T'. t\ t. M. m. /• y- X . sp. H. o 0 o o grms. grms. grm. grm. 52-4 20-3 20-04 17-44 26-955 4-835 1-84 0-431 0-453 0-194 50-7 20-8 20-53 18-14 26-975 55 55 55 0-188 50-1 20-9 20-63 18-30 26-935 55 55 55 55 0-187 52-0 21-1 20-82 18-33 26-955 55 55 55 55 0-192 50-4 21-3 21-04 18-73 26-97 „ T82* „ 55 0-187 Mean . . . 0-190 * After drying the stopper. 150 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 66. Borate of Soda, Na2B407. Beautiful transparent vitreous pieces of fused borax. Experiments with Naphtha A. Glass 2. Temperature of the Air 140,4. T. T'. t'. t. M. m. /• y- X. sp. H. O 0 o o grms. grms. grms. grm. 46-6 16-6 16"33 13-67 26-95 4.475 2-005 0-431 0-487 0-232 46-8 16-6 16-33 13-65 26-98 99 99 „ 0-233 46-5 16-6 16-33 13-73 26-965 99 ,, 0-222 46-6 16-8 16-54 13-93 26-945 99 1-99* „ ,, 0-227 Mean . . . 0-227 Hydrated Borate of Soda, Na2 B4 07+lO H2 0. Crystallized borax dried in the air. Experiments with Naphtha A. Glass 3. Temperature of the Air 16°-3-160-5. T. T'. t'. t. M. m. /■ y • X. sp. H. 50-9 18-7 18-43 15-43 grms. 26-98 grms. 3-38 grm. 1-745 0-431 grm. 0-453 0-387 50-3 18-4 18-13 15-15 26-95 99 99 99 0-388 49T 18-5 18T6 15-33 26-96 99 99 99 99 0-381 49-5 18-8 18-45 15-61 26-945 99 1-73* 99 99 0-383 Mean . . . 0-385 67. Tungstate of Lime, Ca W04. Crystals of Scheelite from Zinnwald in Bohemia. Experiments with Naphtha A. Glass 1. Temperature of the Air 16°-7-16°-4. T. T'. t'. t. M. m. /• y- X. sp. H. o o o o grms. grms. grm. grm. 50-3 19-3 19-00 16-27 26-96 11-575 1-34 0-431 0-651 0-0990 49-5 19T 18-84 16-22 26-96 99 99 99 99 0-0946 50-5 19-0 18-71 15-94 26-97 99 99 99 99 0-0988 48-6 19-0 18-66 16-12 26-99 99 1-325* „ 99 0-0945 Mean . . . 0-0967 Wolfram, Fe§ Mn* W04f. Fragments of crystals from Altenberg in the Erzgebirge. Experiments with Naphtha B. Glass 1. Temperature of the Air 19°T-19°-0. T. T'. t'. t. M. m. /• y- X. sp. H. 0 o 0 o grms. grms. grm. grm. 52-1 21-1 20-83 18T4 26-985 11-455 1-525 0-419 0-651 0-0918 52-9 21-2 20-92 18-14 26-975 5? 99 99 99 0-0939 54-0 21-2 20-92 18-04 26-97 99 0-0941 54-8 21-4 21-13 18-23 26-945 „ 1-51* 99 99 0-0921 Mean . . . 0-0930 *■ After drying the stopper. t According to Kerndt’s analysis of. the wolfram of Altenberg (Rammelsberg’s ‘ Handbuch der Mineral. Ohemie,’ p. 308). PEOFESSOE K.OPP ON THE SPECIFIC HEAT OF SOLID BODIES. 151 Molybdate of Lead , Pb M 04. Comminuted crystals of Wiilfenite (Gelbbleierz) from Bleiberg in Carinthia. Experiments with Naphtha A. Glass 3 Temperature of the Air 17°-6-17°-4. T. T'. t'. t. M. m. /• y- X. sp. H. 50-2 19-3 18-95 16-45 grms. 26-98 grms. 8-69 grms. 2-32 0-431 grin. 0-453 0-0840 50-0 19-2 18-92 16-43 26-97 55 55 ?? „ 0-0837 48-6 19-1 18-84 16-47 26-935 55 5T 55‘ >» 0-0818 49-3 19-3 19-01 16-62 26-98 „ 2-295* „ 55 0-0814 Mean . . . 0-0827 68. Chromate of Lead, Pb €r G4. For the investigation pieces of artificially prepared chromate of lead were used, which after fusion had solidified to an aurora-red mass of a fibrous crystalline structure, and with crystal needles on the surface. Experiments with Naphtha A. Glass 3. Temperature of the Air 17°T-17°’9. T. T'. t'. t. M. m. A U’ X. sp. H. o o 0 0 grms. grms. grm. grm. 50-0 19-0 18-74 16-22 26-975 10-60 1-93 0-431 0-453 0-0857 50-1 19-2 18-92 16-34 26-985 55 55 55 55 0-0931 49-6 19-2 18-93 16-42 26-975 55 55 55 55 0-0889 49-9 19-3 19-02 16-44 26-99 55 1-915* „ 55 0-0940 Mean . 0-0900 Chromate of Potass, K2 Cr G4. Crystals of the neutral salt dried at 105° Experiments with Naphtha A. Glass 1. Temperature of the Air 16c •l-16°-8. T. T'. t'. t. M. m. /• y- X. sp. H. o o 0 o grms. grms. grm. grm. 49-1 18-0 17-69 15-13 26-985 4-995 1-535 0-431 0-651 0-182 45-7 17-8 17-49 15-14 26-975 55 55 55 „ 0-192 47-3 17-9 17-62 15T3 26-995 55 55 55 55 0-195 48-2 18-2 17-93 15-43 26-955 » 1-525* „ 55 0-188 Mean . . . 0-189 Acid Chromate of Potass, K2 Cr2 G7 Crystals of the so-called bichromate. Experiments with Naphtha A. Glass 1. Temperature of the Air 19°T-19°'5. T. T'. t'. t. M. m. /• y- X . sp. H. o o o o grms. grms. grm. grm. 53-3 21-1 20-83 18-33 26-97 4-275 1-58 0-431 0-651 0-178 51-5 21-1 20-82 18-42 26-95 5 5 „ 55 55 0-186 51-6 21-1 20-76 18-33 26-96 55 55 55 „ 0-191 52-6 21-2 20-93 18-45 26-975 55 1-555* „ 55 0T89 Mean . . . 0T86 * After drying tlie stopper. T MDCCCLXV. 152 PKOFESSOE KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 69. Sulphate of Soda, Na2 S04. Crystalline crusts briskly dried. Experiments with Naphtha A. Glass 1. Temperature of the Air 110,2-110,4. T. T. t’. t. M. m. /• y- X. sp. H. O o o 0 grms. grms. grm. grm. 44-2 12-8 12-52 9-94 26-97 3-465 1-73 0-431 0-651 0-236 47*8 13-2 12-93 10-14 26-93 59 95 55 0-224 46*1 13-2 12-93 10-25 26-95 59 95 99 „ 0-230 46-6 13-6 13-32 10-69 26-975 55 1-716* „ Mean ” 0-219 0-227 Sulphate of Potass , K2 S04. Crystal crusts sharply dried. Experiments with Naphtha A. Glass 2. Temperature of the Air ll°*2-ll0-4. T. T'. t'. t. M. m. /• y- X. sp. H. o 0 o <3 grms. grms. grms. grm. 44-5 12-7 12-44 12-02 26-915 3-405 2-145 0-431 0-487 0-187 47-0 13-2 12-93 10-22 26-95 „ 2-30f „ 0-200 45-9 13-3 13-02 10-41 26-95 99 55 95 „ 0-200 43-1 13-3 13-03 10-67 26-95 2-275* „ Mean 59 0-196 0-196 Acid Sulphate of Potass, KH S04. Well-formed crystals dried at 100° J. The salt became feebly red on the surface in contact with the coal-tar naphtha. cperiments with Naphtha A. Glass 1. Temperature of the Air 17° •0-17°- T. T'. t\ t. M. m. /• y- X. sp. H. o o o o grms. grms. grm. grm. 50-7 19-4 19-12 16-43 26-94 3-445 1-85 0-431 0-651 0-251 50-4 19-3 19-01 16-36 26-945 95 55 0-245 50-5 19-3 18-97 16-34 26-96 5? J? 59 0-239 51-9 19-4 19-05 16-32 26-965 59 1-83* „ Mean 55 0-239 0-244 70. Sulphate of Ammonia, N2 H8 S04. I made two series of experiments with this salt. Crystals dried in vacuo over sulphuric acid. I. — Experiments with Naphtha A. Glass 2. Temperature of the Air 10o,9-llo,3. T. T'. t'. t. M. m. /• y- X . sp. H. o o o 0 grms. grms. grm. grm. 45-1 13-0 12-73 9-73 26-93 3-425 1-825 0-431 0-487 0-363 44-5 13-4 13-12 10-25 26-98 ?? 59 59 99 0-355 44-3 13-2 12-93 10-08 26-93 1-815* „ 55 0-350 Mean 0-356 * After drying the stopper. + After adding some naphtha. $ Dr. Engelbach found the quantity of potass in these crystals to be 33'70 and 34-13 per cent. Calculated from the above formula 34-61 per cent, are required. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 153 Crystals dried at 120°. II. — Experiments with Naphtha A. Glass 1. Temperature of the Air 10°'9-llo,31. T. T'. t'. t. M. m. /• & X. sp. H. O 0 0 o grms. grms. gnu. grm. 44-2 12-9 12-63 9-97 26-94 2*84 1*555 0-431 0-661 0-341 42-2 12-6 12-33 9-81 26-95 T. ) *5 r) 55 0-343 45-4 13-3 12-96 10-30 26-985 55 55 55 55 0-322 46-7 13-0 12-72 9-77 26-935 „ 1-535* 55 55 0-368 Mean . . . O' 344 The mean of the means of both series of experiments, 0-356 and 0-344, gives for the specific heat of sulphate of ammonia between 13° and 45° the number 0-350f. 71. Sulphate of Lead, Bb£G4. Fragments of transparent crystals of lead- vitriol from Miisen, near Siegen. Experiments with Naphtha A. Glass 1. Temperature of the Air 17°-6-17°*4. T. O T'. o t'. t. O- M. grms. m. grms. /• grm. y- X* grm. sp. H. 48-3 19-6 19-33 16-90 26-975 12-575 1-47 0-431 0-651 0-0795 50-9 19-3 19-00 16-23 26-96 55 55 55 55 0-0858 49-9 19-3 19-01 16-33 26-985 „ 55 55 0-0858 50-4 19*6 19-24 16-63 26-99 55 1-45* 55 Mean 55 *' 0*0798- 0-0827 Sulphate of Baryta , Ba S04. Cleavage pieces of crystal of heavy spar from the Auvergne. I. — Experiments with Naphtha A. Glass 1. Temperature of the Air 15°T-150,9. T., T'. t'. t. M. m. /• y- X. sp. H. o 0 o o grms. grms. grm. grm. 46-5 17-4 17-12 14-64 26-945 9-15 1-405 0-431 0-651 0-113 48-5 17-5 17*17 14-56 26-97 55 55 55 5? 0-111 44-6 17-4 17-05 14-82 26-97 55 1-395* „ Mean 55 0-105 0*110 * After drying the stopper. t I had made a third series of experiments with large dry transparent crystals of sulphate of ammonia, but in which t' exceeded more than usual the temperature of the air, and hence numbers were found for the body investigated which are somewhat too small. Experiments with Naphtha A. Glass 2.. Temperature of the Air 9°-7. t: T' t'. U M. w. /• & X. sp^ H. 45-6 O 12-4 12-05 8-86 grms. 26-935 grms. 3-725 grms. 2-015 0-431 gnn. 0-487 0-331 47-1 12-8 12-45 9-22 26-97 „ „ ,, 0-318 42-9’ 12-6 12-25 9-42 26-99 „ „ 55 ,, 0*313 44-1 12-5 12-22 9-24 26-95 ,, „ >> 55* 0-318 47-0 12-7 12-36 9-16 26-94 „ 1-985® ,r 0-314 ® After removing some naphtha from the stopper. Y 2 154 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. XX.— -Experiments with Naphtha A. Glass 1. Temperature of the Air 160'7-17°-2. T. T', t'r t. M. m. /• y- X. sp. H. O o o o grms. grms. grin. grni. 49-9 19-0 18-65 16-13 26-96 7-77 1-68 0-431 0-651 0-106 50*9 19-0 18-74 16-14 26-94 55 55 55 0-106 49-0 19-0 1067 16-22 26-96 „ 1-665* 55 „ 0-107 Mean . . . 0T06 The mean of the means of these two sets of experiments gives 0T08 for the specific heat of heavy spar between 18° and 44°. Sulphate of Strontia, Sr S04. Crystals of celestine from Dornburg, near Jena. Experiments with Naphtha A. Glass 3. Temperature of the Air 150,6-16°T. T. T'. t'. t. M. m. /• V‘ X . sp. H. O O o 0 grms. grms. grm. grm. 50-2 17-8 17-47 14-74 26-965 7-63 1-90 0-431 0-453 0-137 50-5 T7-7 17-43 14-64 26-955 55 55 0-134 51-4 17 -8 17-51 14-64 26-995 >5 55 „ 0-135 52-7 17-9 17-55 14-61 26-955 55 1-875* „ „ 0-133 Mean . . . 0T35 72. Sulphate of Lime, CaS04. Small crystalline pieces of anhydrite. I. — Experiments with Naphtha A. Glass 1. Temperature of the Air 130,2-13°*7. T. T'. t'. t. M. m. /• y- X. sp. H. 46-1 15-6 15-33 12-72 grms. 26-98 grms. 5-305 grm. 1-715 0-431 grm. 0-651 0-173 46-5 15-5 15-22 12-53 26-93 55 55 55 55 0-178 45-7 15-6 15-34 12-74 26-92 55 55 55 „ 0-176 43-6 15*7 15-44 13-11 26-94 v 1-70* 55 55 0-163 Mean . 0-173 II. — Experiments with Water. Glass 3. Temperature of the Air 17' 3-9-18°-3. T. T'. t'. t. M. m. /• V' X. sp. H. 47-5 19-9 19-62 15-62 grms. 26-95 grms. 5-62 grms. 2-415 1-000 grm. 0-453 0-185 47T 19-8 19-53 15-61 26-99 55 55 „ 0-179 47-1 20-1 19-77 15-87 26-975 55 55 55 0-183 47-5 20-2 19-94 16-03 26-98 55 2-40* 0-180 Mean . . . 0T82 The average of the means of these determinations gives 0T78 as the specific heat of anhydrite between 18° and 46°. After drying the stopper. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 155 Hydrated Sulphate of Lime, GaSG4+2 H2 O. Cleavage pieces of transparent Gypsum from Reinhardtsbrunn, in Thuringen. Experiments with Naphtha A. Glass 2. Temperature of the Air 13°-2-13°-7. T. T'. t'. t. M. m. /• y- X. sp. H. 47-2 15-6 15-29 12-32 grms. 26-94 grms. 4-335 grms. 2-115 0-431 giro. 0-487 0-261 47-4 15-8 15-53 12-57 26-99 „ 99 99 5) 0-261 45-7 15-8 15-53 12-73 26-96 99 99 99 „ 0-260 44-2 16-0 15-73 12-13 26-94 99 2-095* 99 5? 0-252 Mean . . . 0-259 73. Crystallized Sulphate of Copper , Gu SG4-J-5 H20. Crystals of Blue vitriol dried in the air. xperiments with Naphtha A. Glass 1. Temperature of the Air 14c •1-14°- T. T'. t'. t. M. m. /• y- X. sp. H. o 0 o o grms. grms. grm. grm. 50-8 16-4 16-08 12-82 26-99 4-12 1-65 0-431 0-651 0-290 47-3 16-4 16-05 13-12 26-965 99 99 „ „ 0-290 46-7 16-5 16-16 13-34 26-99 99 99 99 99 0-281 45-0 16-6 16-26 13-63 26-965 99 1-635* 99 99 0-277 Mean 0-285 Crystallized Sulphate of Manganese, Mn S04-J-5 H2 O. Crystals of the salt isomor- phons with blue vitriol. speriments with Naphtha A. Glass 2. Temperature of the Air 14' 3-l-14°-2. T. T'. t'. t. M. m. /• y- X. sp. H. O o o o grms. grms. grm. grm. 48-5 16-7 16-42 13-23 26-945 4-12 1-97 0-431 0-487 0-332 45-7 16-4 16-14 13-24 26-945 99 99 99 0-323 46-5 16-7 16-43 13-53 26-98 99 99 0-313 44-0 16-8 16-53 13-85 26-945 99 1-955* 99 ?? 0-322 Mean 0-323 Crystallized Sulphate of Nickel, Ni S04-{-6 H2 0. Crystals of quadratic nickel vitriol dried in vacuo. xperiments with Naphtha A. Glass 1. Temperature of the Air 15 °-6-16°- T. T'. t'. t. M. m. /• y- X. sp. H. o O o o grms. grms. grm. grm. 52-5 18-0 17-74 14-61 26-97 3-60 1-655 0-431 0-651 0-307 50-3 17-7 17-42 14-37 26-995 99 99 5) 0-322 51-5 17-7 17-36 14-24 26-985 99 „ 0-313 52-8 181 17-82 14-62 26-94 9* 1-63* 5? ,, 0-314 Mean 0-313 After drying the stopper. 156 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 74. Crystallized Sulphate of Magnesia, Mg S04+7 H2 G. Air-dried crystals of Epsom salt. I have made two series of experiments with this salt. In one the temperature did not exceed 40°, and in the other did not attain 50°. In both cases the crystals remained transparent and unchanged. I. — Experiments with Naphtha A. Glass 3. Temperature of the Air 19°-8-19° -9. T. T'. t'. t. M. m. /• y- X. sp. H. O O 0 o grms. grms. grm. grm. 38-5 21 6 21-29 19-77 26-96 3-175 1-845 0-431 0-453 0-371 39-3 21-6 21-32 19-73 26-945 ,, 55 55 5J 0-369 38*7 21-6 21-34 19-83 26-98 55 55 55 0-357 37-7 21-6 21-27 19-85 26-935 „ 1-835* 55 „ 0-356 Mean . . . O’ 363 II. — Experiments with Naphtha A. Glass 1. Temperature of the Air 16°T. T. T'. tr. t. M. m. /• y- X. sp. H. o* o o 0 grms. grms. grm. grm. 47-6 18-3 18-04 15-42 26-97 2-775 1-81 0-431 0-651 0-353 47*9 18-4 18-12 15-43 26-985 55 55 55 55 0-371 45-2 18-3 17-96 15-53 26-94 „ 55 55 55 0-361 43-9 18-3 17-96 15-67 26-975 55 1-795 * 55 55 0-356 Mean . . . 0-360 These determinations give as the mean of the two series 0-362 for the specific heat of crystallized sulphate of magnesia below 50°f . Crystallized Sulphate of Zinc, Zn S04+7 H2 0. Transparent crystals of white vitriol, dried in the air. In the determinations a heat but little over 50° could be employed; towards 50° the crystals undergo decomposition in the coal-tar naphtha J. Experiments with Naphtha A. Glass 1. Temperature of the Air 13°-4. T. T'. t'. t. M. m. /. y<. x. Sp. H. ooo o grms. grms. grm- grm. 28-7 14-6 14-33 12-93 26-945 3-55 1-655 0-431 0-651 0*369 30-7 14-9 14-62 13-13 26-95 „ „ „ „ 0-332 This series of experiments had to be interrupted here. I subsequently made another set. * After drying the stopper. f Above 50° the salt with 7 at. water of crystallization undergoes decomposition. A series of experiments in which the temperature exceeded 50° gave the following results. Experiments with Naphtha A. Glass 3. Temperature of the Air 20°-3-21°-l. T. T'. t'. t. M. m. f- y- X. sp. H. o 51-5 22-6. 22:32 1061 grms. 26-995 grms. 3-43 grm. 1-57 0-431 grm. 0-453 0-409 51-4 22-8 22-52 19-55 26-93 „ „ )} 0-475 51-0 23-0 22-71 19-73 26-945 „ „ „ 0-507 500’ 23-0 22-71 19-81 26-93 „ 1-56* „ 99 0-515 The results are as if more and more water in the free state had been eliminated.. After the experiments the crystals were swollen, and externally milk white, still containing a clear nucleus inside. % In the following series of experiments, in which a heat of towards 50° was employed, the crystals of white PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 157 Experiments with Naphtha A. Glass 1. Temperature of the Air 14°-4-15°-Q. T. T'. t'. t. M. m. /• y- X. sp. H. Q o 0 grms. grms. grm. grm. 3,0-9 15-7 15-43 14* * * §03 26-93 3-49 1-645 0-431 0-651 0-321 32-3 16-0 15-65 14-13 26-96 55 55 55 55 0-331 30-8 15-8 15-52 14-03 26-95 55 „ „ 55 0-377 32-8 16-1 15-83 14-23 26-97 .55 1-635* 55 55 0-352 In all these experiments the crystals employed remained clear. The mean of the six experiments gives 0-347 as the specific heat of crystallized sulphate of zinc. Crystallized Sulphate of Iron, Ee S04+7 H2 0. Dry crystals of green vitriol. Experiments with Naphtha A. Glass 2. Temperature of the Air 16°T. T. T'. t'. t. M. m. /• y- X . sp. H. 0 o o grms. grms. grm. grm. 47-9 18*6 18-32 15-56 26-93 3-47 1-91 0-431 0-487 0-354 47-5 18-6 18-25 15-55 26-925 „ „ „ „ 0-347 46-0 18-5 18-21 15-64 26-955 55 55 55 55 0-348 44-6 18-4 18-13 15-73 26-96 „ 1-895* 55 55 0-336 Mean . . . 0-346 Crystallized Sulphate of Cobalt, Co B04+7 H2 G. Crystals of the salt isomorphous with green vitriol. In the following experiments the crystals remained transparentf . Experiments with Naphtha A. Glass 2. Temperature of the Air 13°'4-13°-2. T. T'. t'. t. M. m. /• y- X. sp. H. 0 o o grms. grms. grm. grm. 31-6 14-9 14-63 12-96 26-97 3-445 1-895 0-431 0-487 0-405 29-9 14-8 14-54 13-14 26-945 55 55 55 ,, 0-347 28-4 15-0 14-67 13-43 26-93 55 55 55 55 0-345 31-6 15-2 14-94 13-44 26-94 1-885* 55 0-338 Mean . . . 0-343 J vitriol undergo an essential change. At the end of the experiments they were opaque, and no longer detached, as before, hut as if swollen up in the glass. These experiments gave the following numbers : — , Experiments with Naphtha A. Glass 1. Temperature of the Air 14°-8-14°-4. T. T'. t'. t. M. TO. /• y- X . sp. H. o O 0 0 grms. grms. grm. grm. 47-4 17-0 16-74 13-62 26-94 3-465 1-695 0-431 0*651 0-399 47-6 17-0 16-72 13-62 26-945 „ „ „ 0-389 45-1 16-9 16-63 13-77 26-975 „ 1-655 § „ 0-396 43-8 17-1 16-83 14-22 26-99 „ ,, „ 0-368 * After drying the stopper. f In a series of experiments, in which the temperature amounted to 50°, the crystals of sulphate of cobalt with seven atoms of water underwent a change ; they were opaque, and stuck in the glass as if swollen up ; and the numbers found for the specific heat were considerably greater. J Excluding the first experiment. The temperature of the glass, together with the solid substance and the liquid, exceeded in all experiments the final temperature of the water in the calorimeter only by about 15°. § After removing some naphtha from the stopper. 158 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 75. Crystallized Sulphate of Magnesia and Potass , Mg K2 S2 Os+ 6 H2 O. Well- shaped crystals. Experiments with Naphtha A. Glass 3. Temperature of the Air 17°’0-17°-2. T. T'. t'. t. M. m. /• y- X . sp. H. 51-0 19-4 19-13 16-43 grms. 26-99 grms. 4-135 grms. 1-735 0-431 grm. 0-453 0-267 51-0 19-3 19-02 16-33 26-965 5 5 55 55 55 0-263 50-0 19-3 19-02 16-43 26-96 55 55 55 55 0-260 50-2 19-4 19-06 16-44 26-95 55 1-715* 55 55 0-266 Mean . . . 0-264 Crystallized Sulphate of Zinc and Potass , -Zn K2S2G8-(-6H20. W ell-shaped crystals ; in both the following series they remained transparent and unchanged. 1. — Experiments with Naphtha A. Glass 1. Temperature of the Air 19°-8-19°-9. T. T'. t'. t. M. m. /• y- X. sp. H. 40-2 21-7 21-37 19-73 grms. 26-925 grms. 3-965 grm. 1-535 0-431 grm. 0-651 0-271 40-6 21-7 21-42 19-75 26-935 3, 55 55 55 0-269 40-2 21-7 21-38 19-73 26-955 55 55 55 55 0-275 39-8 21-7 21-40 19-83 26-925 55 1-52* 55 55 0-260 Mean 0-269 II. — Experiments with Naphtha A. Glass 2. Temperature of the Air 14°-8-140,4. T. T'. t'. t. M. m. /• y- X . sp. H. 48-9 16-9 16-64 13-63 grms. 26-94 grms. 4-365 grm. 1-98 0-431 grm. 0-487 0-273 47-2 16-8 16-50 13-63 26-92 55 55 55 0-275 48-0 16-9 16-61 13-69 26-98 55 55 „ 0-273 45-7 16-9 16-63 13-96 26-97 „ 1*965 ’ 55 55 0-267 Mean 0-272 The mean of the means of both series of experiments gives 0-270 as the specific heat of crystallized sulphate of zinc and potass between 19° and 40°-50°. Crystallized Sulphate of Nickel and Potass , Ni K2 S2 08+6 H2 O. Well-formed crystals. Experiments with Naphtha A. Glass 2. Temperature of the Air 130,3-13°-5. T. T'. t'. t. M. m. /• 2/* X. sp. H. 49-1 o 16-1 15-84 12-77 grms. 26-94 grms. 4-775 grm. 1-945 0-431 grm. 0-487 0-247 45-1 15-6 15-34 12-61 26-96 55 „ 55 >» 0-245 45-5 15-8 15-46 12-73 26-945 55 55 55 „ 0-241 44-0 15-6 15-32 12-69 26-975 55 1-925* 55 jj 0-247 Mean . . . 0*245 * After drying the stopper. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 159 76. Crystallized Sulphate of Alumina and Potass , Al2 K2 S4 Gl6+24 H2 G. Transparent air-dried crystals of alum. Experiments with Naphtha A. Glass 1. Temperature of the Air 17°*2-17°*4. T. T'. t'. t. M. m. /• y- 07. sp. H. 49*1 19*5 19*16 16*55 grms. 26*98 grms. 2*87 grm. 1*595 0*431 grm. 0*651 0*362 49*6 19*1 18*83 16*12 26*985 „ 55 59 55 0*369 49*0 19*3 18*96 16*32 26*99 95 55 55 0*370 49*5 19*3 18*95 16*23 26*96 55 1*58* „ 55 0*382 Mean . . . 0*371 Crystallized Sulphate of Chrome and Potass , Or2 K2 S4 Gl6+24 H2 G. Air-dried crystals of chrome alum : they remained unchanged in the following experiments. Experiments with Naphtha A. Glass 3. Temperature of the Air 17° *2-17°*4. T. T' t'. t. M. m. /• y- X. sp. H. o O o o grms. grms. grm. grm. 50*9 19*3 19*03 16*14 26*95 3‘70 1*875 0*431 0*453 0*325 50*6 19*4 19*06 16*23 26*965 55 55 55 55 0*320' 50*9 19*5 19*23 16*34 26*995 *5 55 59 95 0*331 51*4 19*6 19*34 16*46 26*97 55 1*865* 55 55 0*320 Mean . . . 0*324 77. Chloride of Carbon , G2 Cl6. The determination of the specific heat of this, the so-called sesquichloride of carbon, has given me much trouble. I first investigated, in two series of experiments, a preparation which, after melting in a small glass tube, had solidified in porcelain-like white crusts f. I. — Experiments with Water. Glass 1. Temperature of the Air 18°*5-18°*8. T. T'. t'. t. M. m. /• y- 07. sp. H. 53*5 20*5 20*22 16*16 grms. 26*94 grms. 3*765 grm. 1*61 1*000 grm. 0*651 0*280 52*2 20*4 20*10 16*18 26*945 55 55 55 „ 0*282 52*0 20*7 20*43 16*83 26*97 55 59 55 55 0*269 52*6 20*8 20*45 16*61 26*965 55 1*585* 0*271 Mean . . . 0*276 * After drying the stopper. t Sesquichloride of carhon was prepared by continuously passing chlorine into crude chloride of ethylene in the sunlight, and washing the solidified product with water ; it was then again treated with chlorine and washed with solution of soda and much water. The crystalline mass was afterwards repeatedly pressed between bibu- lous paper (by which a small quantity of an oily product was absorbed), dried in the air, then washed with cold alcohol, dried, and fused, and the parts which had crept up the sides separated when solid. — Eegelbacu. MDCCCLXV. Z 160 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. II. — Experiments with Water. Glass 1. Temperature of the Air 170,5-17°‘4. T. T'. t'. t. M. m. /• y- X. sp. H. O O 0 o grms. grms. grm. grm. 50-2 19-8 19-54 15-54 26-955 3-525 1-995 1-000 0-651 0-256 50-1 19-6 19-33 15-31 26-94 55 55 55 jj 0-257 50-5 19-7 19-36 15-24 26-96 V 55 55 „ 0-272 49-2 19-7 19-43 15-52 26-97 „ 55 55 w 0-263 47-8 19-7 19-36 15-62 26-99 5,5, 1-965* 55 „ 0-277 Mean . . . 0-265 I should not have hesitated to take the number 0-27, the mean of the averages of both these series of determinations, as the normal specific heat of sesquichloride of carbon, and to consider it as sufficiently below the melting-point (according to Faraday this is at 160°), if the connexion between the specific heat of solid bodies and their composition, discussed in § 96 et seq., had not been known to me; but the specific heat of sesqui- chloride of carbon calculated therefrom is 0-177. This deviates from the number found in a manner which at first I could not understand. The idea that the specimen was im- pure was inadmissible f. To try whether the porcelain-like mass of sesquichloride which solidified on fusion had an essentially different specific heat from that not fused, I re- crystallized the substance from ether, washed the crystals (which showed very distinctly the characteristic form of the body as described by Brooke and Laurent) with a little ether, and dried them at 100°. Dried at this temperature, without being melted, they were white, like porcelain, and gave now the following results. III.— Experiments with Water. Glass 3. Temperature of the Air 18°*4-18°-7. T. T'. t'. t. M. m. / y • X. sp. H. 49-2 20-6 20-34 16-53 grms. 26-935 grms. 3-835 grms. 2-06 1-000 grm. 0-453 0-280 49-2 20-7 20-42 16-62 26-94 55 55 55 55 0-281 49-0 20*8 20-53 16-81 26-95 2-05* 55 5 5- 0-274 Mean . . . 0-275 That is essentially the same specific heat as my earlier experiments gave. If now it was improbable that the specific heat of sesquichloride of carbon did not differ much from 0-27, I might, on the other hand, also consider it improbable that this compound would make an exception to the relation which I had found between specific heat and composition — a relation which holds good in hundreds of cases of solid bodies. Sesquichloride of carbon would be the only exception to the validity of this relation ; but this single exception would be sufficient to disprove its universal applicability, * After drying tlie stopper. t In the specimen I investigated, Mr. Dehx found 90T9 per cent, chlorine ; the quantity calculated from the formula C2 Cla is 89-88 per cent. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 161 and to leave it undecided when, and in how many cases, other such exceptions might occur. Although the great distance of the temperatures used in my experiments from the melting-point of sesquichloride of carbon made it improbable, it was yet possible that the specific heat of this body varies considerably at the temperatures which I used, and is only constant and normal at still lower temperatures. In the preceding experiments I had heated sesquichloride of carbon to 49°-52° ; it was improbable that this body, at so great a distance from its melting-point (160°), should absorb latent heat in softening in appreciable quantity, yet the circumstance that this substance is brittle in the cold, but distinctly tougher at 50°, led me to determine the specific heat at lower tem- peratures than in the previous case. I made the two following series of experiments, a with sesquichloride crystallized from alcoholic, and b from ethereal solution : in both series the crystals dried at 100° were porcelain white in appearance. a.— Experiments with Water. Glass 1. Temperature of the Air 170,8. T. T'. t'. t. M. m. /• y- X . sp. H, O o o Q grms. grms. grms. grm. 36-8 19-7 19-35 17-42 26-98 2-11 2-085 1-000 0-651 0-146 37-6 19-8 19-52 17 52 26-94 55 „ 55 „ 0-138 37-2 19-7 19-44 17-51 26-94 55 55 55 55 0-111 37 T 19*8 19-45 17-53 26-98 55 2-075 55 0-127 b.— Experiments with Water. Glass 3. Temperature of the Air 17°-8. T. T'. t\ t. M. m. /• y- X . sp. H. o o 0 0 grms. grms. grms. grm. 37*2 19-8 19-45 17-42 26-98 3-64 2-11 1-000 0-453 0-161 37-2 19*7 19-43 17-42 26-99 55 55 „ „ 0-148 37-3 19-7 19-44 17-42 26-965 55 55 0-146 37-3 19-7 19-44 17-43 26-965 55 2-10 55 55 0-145 h these series can only be considered as giving approximate : results. In both the magnitude T — T' is very small, not as much as 18°; in the series a the quantity of solid was moreover small, and its thermal action but a small fraction of the entire amount observed. The mean of the four experiments of the series b would give the specific heat between 20° and 37° at 0T5, and the first experiment of the series a agrees well with this. The specific heat here found between 20° and 37° comes very near that calculated from the composition, and is so much less than that found between 20° and 50°, that it is probable this substance may towards 50° absorb heat in softening, the amount of which may make the numbers for the specific heat too great. To decide upon this point, T made two additional series of experiments in which, since the vessel containing sesquichloride of carbon and water could only be slightly heated * After drying the stopper. z 2 162 PKOFESSOE KOPP ON THE SPECIFIC HEAT OE SOLID BODIES. (not to 40°), and the difference of temperature T — T' accordingly was small, I used all possible care. I thus obtained the following results. a. Crystals obtained from ethereal solution dried at 100°: milky white. Experiments with Water. Glass 1. Temperature of the Air 16°T- -15°-7. T. T'. t'. t. M. m. /. y • tf- sp. H. 37 T o 18-1 17-84 15-64 grins. 26-94 grms. grin. 3-58 1-845 grm. 1-000 0-651 0-174 37-1 18-2 17-92 15-73 26-99 55 55 55 55 0-176 37-2 18-0 17-72 15-63 26-985 „ 1-835* „ „ 0165 Temperature of the Air 16°T. 43-7 18-2 17-93 14-93 26-995 3-58 1-835 1-000 0-651 0-193 43-5 18-2 17-93 14-95 26-97 55 55 V 55 0-193 Temperature of the Air 16°-2. 51-9 18-4 18-12 13-86 26-995 3-58 1-82 1-000 0-651 0-269 48-6 18-1 17-77 13-84 26-975 55 55 55 55 0-281 Clear crystals obtained from ethereal solution, dried by passing a current < air over them at the ordinary temperature. Experiments with Water. Glass 3. Temperature of the Air 16°-2- -15°*7. T. T'. t'. . t. M. m. /. y- X. sp. H. 36-9 18-2 17-93 15-62 grms. 26-99 grms. grms. 4-235 2-155 1-000 grm. 0-453 0-171 36-8 18-2 17-92 15-64 26-99 55 55 „ „ 0-184 37-1 18-3 18-01 15-63 26-975 „ 2T45* 55 - 0-193 Temperature of the Air 16T°'-16C >•2. T. T'. t'. t. M. m. /. y- X. sp. H. 43-4 o 18-1 17-84 14-63 grms. 26-99 grms. grms. 4-235 2-145 1-000 grm. 0-453 0-195 43-4 18-2 17-90 14-70 26-96 55 55 55 55 0-195 Temperature of the Air 16°-2. 52-0 18-9 18-63 14-05 26-955 4-235 2T25 1-000 0-453 0-272 47-3 18-1 17-83 13-73 26-945 55 55 55 „ 0-285 In the last series of experiments, on heating to about 50° a change took place in the hitherto clear crystals ; they became dull and resembled porcelain. By special experi- ments I found that transparent crystals of sesquichloride of carbon gradually heated in water underwent this change at 50°-52°. These determinations leave no doubt that, as is the case with other substancesf, for * After drying the stopper. f I call to mind the experiments of Pebsox, who found (Ann. de Chim. et de Phys. [3] vol. xxvii. p. 263) for the specific heat of bees’ wax melting at 610,8, Between —21° and +3° 6° and 26° 26° and 42° 42° and 58° 0-4287 0-504 0-82 1-72 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 163 temperatures near their melting-points, so also with sesquichloride of carbon at a temperature of 50° (that is more than 100° from its melting-point), the specific heat (or rather the number which is obtained for this in determinations) rapidly and con- siderably increases. From the last two series of experiments the specific heat of sesqui- chloride of carbon is Between 18° and 37°. Mean of experiments: a . . . 0172 ' „ b . . . 0-183 Between 18° and 43°. 0193 0195 0-194 Between 18° and 50°. 0-275 0-279 0-277 Average 0*178 The specific heat of sesquichloride of carbon increases much more between 43° and 50° than between 37° and 43°. It may be assumed that for temperatures below 37° the number found, 0-178, comes very near the true specific heat of this compound, that is, uninfluenced by heat of softening. 78. Cane-sugar , G12H220u. Dried crystalline fragments of clear sugarcandy. Experiments with Naphtha A. Glass 3. Temperature of the Air 20o,6. T. T'. t'. t. M. m. /• y- X. sp. H. O O o o grms. grms. grm. grm. 49-9 22-2 21-93 19-75 26-96 3-165 1-625 0-431 0-453 0-306 51-4 22-6 22-26 20-03 26-94 55 95 95 „ 0-295 51-4 22-6 22-30 20-05 26-965 55 1-62* 95 55 0-302 Mean . . . 0-301 Fine loaf-sugar was recrystallized from water, the mother-liquor washed off with dilute alcohol, the pure white crystals dried at 100°. They gave the following results. Experiments with Naphtha B. Glass 1. Temperature of the Air 18°'5-18°*7. T T'. t'. t. M. m. /• y- X, sp. H. O O 0 o grms. grms. grm. grm. 51-5 20-9 20-62 18-16 26-945 2-915 1-54 0-419 0-651 0-299 51-6 20-7 20-43 17-95 26-95 „ 59 55 „ 0-297 50-3 20-6 20-33 17-94 26-985 55 1-52* „ 59 0-303 Mean . . . 0-300 I also examined amorphous cane-sugar. Crystals dried at 100°, as used in the pre- ceding experiment, were melted in an oil-bath at 160°-170°, and the fused mass allowed to cool in the closed tube. The resultant amorphous amber-like viscous mass, exactly resembling colophony, was comminuted (as rapidly as possible to avoid the absorption of moisture), and gave the following results. After drying tlie stopper. 164 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. Experiments with Naphtha B. Glass 1. Temperature of the Air 18o,0-18°-4. T. T'. t'. t. M. m. /• y- x. sp. H. O o o 0 grms. grms. grm. grm. 51-4 20-1 19-82 17-24 26-97 2-475 1-77 0-419 0-651 0-336 50-9 20-0 19-74 17-20 26-99 55 55 55 55 0-334 51-6 20-1 19-78 17-15 26-975 55 55 55 0-345 50-9 20-1 19-77 17-20 26-96 55 1-75* 55 55 0-357 Mean . . . 0-342 The pieces of amorphous sugar used for these experiments were clear even when the experiments were concluded. In the investigation of such a hygroscopic substance it is impossible to avoid with certainty any absorption of water ; yet it seems to me improbable that the difference between the number O' 342 found for amorphous cane-sugar between 20° and 51°, and 0'301 for crystallized sugar between the same limits, depends on an absorption of water by the former ; but it is probable that the greater specific heat found for amorphous sugar depends on the fact that at 50° even it contains some heat of softening. According to Wohler’s observations, bodies in the amorphous condi- tion have other, in general lower, fusing-points than those in the crystallized statef; crystallized cane-sugar melts at 160° C., amorphous between 90° and 100p; at the latter temperature the amorphous sugar may be drawn out in threads, but even at a lower tem- perature the softening begins. Mannite , €6H14G6. Crystallized mannite, dried at 100°, was melted in the oil-bath at 160°-170°, and the radiant crystalline mass was comminuted. It gave the following results J. Experiments with Naphtha B. Glass 3. Temperature of the Air 17°T-17°'8. T. T'. t'. t. M. m. /• y- X. sp. H. o O o o grms. grms. grm. grm. 51-1 19-3 18-92 16-57 26-98 2-56 1-815 0-419 0-453 0-318 51-6 19^4 19-12 16-64 26-93 55 „ 55 55 0-336 51-0 19-5 19-19 16-82 26-965 55 55 55 0-319 51-3 19-6 19-31 16-92 26-93 55 1-805 * 55 55 0-321 Mean 0-324 After dryin g the stopper. t Ann. der Chem. und Pharm. vol. xli. p. 155. I also worked with mannite which was crystallized i in slender prisms and dried at 100°. Experiments with Naphtha B. Glass 3. Temperature of the Air 17°-4. T. T'. t. M. m /- y X. sp. H. O O 0 0 grms. grms. grms. gras. 49-5 19-2 18-85 16-61 26-95 2-13 2-14 0-419 0-453 0-302 51-3 19-3 19-03 16-64 26-94 „ „ 0-311 50-5 19-3 19-04 16-74 26-98- ,, 2- 13* 99 0-302 I consider the somewhat larger numbers obtained by using the compact pieces which had been melted to be more correct. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 165 79. Tartaric Acid , 04 Hfl Ofi. Dried fragments of larger crystals. Experiments with Naphtha A. Glass 1. Temperature of the Air 20°-6. T. T'. t'. t. M. m. /• y- X. sp. H. Q 0 o 0 grins. grms. grm. grm. 51-3 22-4 22-12 19-74 26-985 3-16 1-53 0-431 0-651 0-289 50-5 22-5 22-23 19-94 26-96 99 „ „ 0-283 50-7 22-6 22-32 20-03 26-97 99 1-52* yy it 0-282 Mean . . . 0-285 Small crystals dried at 100°. Experiments with Naphtha B. Glass 3. Temperature of the Air 18o,0-18°-4. T. 6 T'. o t'. o t. 0 M. grms. m. grms. /• grm. y- X. grm. sp. H. 51-1 20-0 19-68 17-15 26-97 3-57 1-69 0-419 0-453 0-289 50-9 20-0 19-72 17-20 26-99 99 99 99 99 0-291 51-3 20-0 19-73 17-18 26-97 99 „ 99 „ 0-290 50-5 19-9 19-63 17T3 26-97 99 1-68* 99 Mean 99. 0-293 0-291 The average of the means of both series of experiments gives 0-288 as the specific heat of crystallized tartaric acid between 21° and 51°. Crystallized Bacemic Acid , €4He06+H20. Fragments of air-dried transparent crystals, which remained clear in the experiments made with them. Experiments with Naphtha B. Glass 1. Temperature of the Air 16°'4-16°-9. T. T', t'. t. M. m. /• y- X . sp. H. o o 0 o grms. grms. grm. grm. 50-5 18-6 18-33 15-63 26-945 3-17 1-495 0-419 0-651 0-317 50-3 18-6 18-33 15-64 26-965 tt 99 99 99 0-319 50-6 18-7 18-43 15-73 26-965 „ 99 99 99 0-317 50-0 18-8 18-52 15-86 26-975 „ 1-48* „ 99 0-324 Mean 0-319 Succinic Acid, €4H604. Small crystals dried at 100°. Experiments with Naphtha B. Glass 1. Temperature of the Air 17° •3-17°-: T. T'. t'. t. M. m. /• y- X . sp. H. o O 0 0 grms. grms. grm. grm. 51-4 19-4 19-05 16-54 26-985 2-455 1-64 0-419 0-651 0-317 50-5 19-4 19-13 16-70 26-95 99 99 99 0-313 50-8 19-5 19-24 16-80 26-965 99 99 0-311 50-9- 19-6 19-26 16-82 26-935 99 1-625 99 0-313 Mean . . 0-313 After drying the stopper. 166 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 80. Formiate of Baryta, G2 H2 Ba 04. Beautiful clear crystals dried at 100°. Experiments with Naphtha B. Glass 3. Temperature of the Air 180*5-18°*8. T. T'. t'. t. M. m. /• y- X. sp. H. o or- 1 20*6 20*31 17*93 grms. 26*98 grms. 6*91 grm. 1*615 0*419 grm. 0*453 0*142 53*1 20*7 20*40 17*85 26*94 55 55 „ „ 0*143 51*8 20*7 20*41 17*95 26*97 55 55 55 55 0*145 52*4 20*7 20*38 17*93 26*99 55 1*58* 55 55 0*141 Mean . . . 0T43 Crystallized Neutral Oxalate of Potass, C2 K2 04+H2 O. Air-dried transparent crystals, which remained clear in the experiments made with them. T. T'. t'. t. M. m. /■ y- X. sp. H. O 0 0 0 grms. grms. grm. grm. 49*4 19*3 19*00 16*52 26*995 3*57 1*765 0*419 0*651 0*233 49*3 19*4 19*12 16*62 26*95 „ 55 55 55 0*241 49*0 19*5 19*15 16*72 26*945 „ 55 55 55 0*232 50*0 19*6 19*26 16*73 26*97 „ 1*755* „ 55 0*240 Mean . . . 0*236 Crystallized Oxalate of Potass (quadroxalate), C2 H K 04+C2 H2 04 + 2 H2 O. Crystals dried in the air, which were also clear after the experiments. Experiments with Naphtha B. Glass 3. Temperature of the Air 16°‘7-16°*9. T. T'. t'. t. M. m. /• y- X. sp. H. 0 0 o 0 grms. grms. grm. grm. 50*1 18*6 18*34 15*77 26*965 3*375 1*76 0*419 0*453 0*283 49*8 18*7 18*42 15*86 26*98 „ „ 55 55 0*288 50*2 18*8 18*45 15*91 26*98 55 „ 55 55 0*278 50*3 18*7 18*43 15*86 26*95 55 1*745 * 55 „ 0*282 Mean . . . 0*283 Acid Tartrate of Potass, G4H5K06. Crystals dried at 100°. Experiments with Naphtha B. Glass 3. Temperature of the Air 16°*6-16°*8. T. T'. t'. t. M. m. /• y- X . sp. H. O o 0 o grms. grms. grm. grm. 50*8 18*6 18*32 15*73 26*965 3*89 1*69 0*419 0-453 0*259 51*0 18*6 18*34 15*72 26*95 55 55 55 55 0*262 50*6 18*7 18*41 15*85 26*935 55 55 55 55 0*257 50*3 18*6 18*34 15*84 26*965 55 1*675 * 55 55 0*250 Mean . . . 0*257 After drying the stopper. PEOFESSOE KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 167 Crystallized Tartrate of Soda and Potass , G4 H4 Na K 06 + 4 Ha 0. Fragments of transparent air-dried Seignette salt, which remained clear in the experiments made with them. Experiments with Naphtha B. Glass 1. Temperature of the Air 16°‘7-16°‘9. T. T'. t'. t. M. m. /• y- X. sp. H. O O Ot o grins. grms. grm. grm. 50-0 19-0 18-72 16-03 26-99 3-385 1-415 0-419 0*651 0-324 50-5 18-8 18-47 15-68 26-93 „ yy yy 0-333 50-5 18-9 18-57 15-82 26-95 yy yy « yy yy 0-325 50-4 18-9 18-61 15-84 26-965 yy yy yy 0-333 50-5 18-9 18-57 15-83 26-965 yy 1-40* yy. yy 0-325 Mean . . . 0-328 Crystallized Acid Malate of Lime, €4 H4 Ca 0a-f 04 H6 05 + 8 H2 O. Small crystals dried over sulphuric acid, which remained clear in the following experiments : T. o T'. o t'. o t. o M. grms. m. grms. f. grm. y- X. grm. sp. H. 50-8 19-4 19-11 16-55 26-985 2-76 1-89 0*419 0-453 0-346 50-1 19-5 19-20 16-73 26-965 yy yy yy „ 0-337 50-5 19-6 19-34 16-84 26-94 yy yy „ 0-339 50-4 19-6 19-27 16-82 26-97 yy 1-865* „ Mean 5) 0-330 0-338 IY.— TABLE OF THE SUBSTANCES WHOSE SPECIFIC HEAT HAS BEEN EXPEEIMENTALLY DETEEMINED. 81. In the following I give a summary of those solid substances of known composition for which there are trustworthy determinations of the specific heat. I have endea- voured to make this summary complete ; yet I have not thought it necessary to include all known determinations; for instance, all those referring to the metals most frequently investigated. But it appeared to me desirable to include completely the determinations of experimenters who have investigated a greater number of substances, in order to see how far the results obtained by different inquirers are comparable ; in inserting the numbers which I found for many substances of which the specific heats had been already determined by others, I had no other intention than that of offering criteria for judging how far these determinations are comparable, and1 may be used for the con- siderations which are given in the fifth Division. The determinations given in the following summary are principally due to Dulong and Petit (D. P.), Neumann (N.), Regnault (R.), and myself (Kp.). There are besides some of Person (Pr.), of Alluard (A.), and the recent investigations of Pape (Pp.) are also included. By far the largest number of these detemiinations have been made by the method of mixture. A few only of the elements investigated by Dulong and Petit, mdccclxv. After drying the stopper. 2 A 168 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. and some of the chemical compounds by Neumann have been determined by the method of cooling. Where it is not otherwise stated in reference to the temperature, all deter- minations refer to temperatures between 0° and 100°. Where the determination has been made beyond these limits, or where a more accurate statement of temperature is important, it is noticed. Where the same substance has been repeatedly investigated by the same observer, the result obtained for the purer preparation, and in general the most certain result, is taken. In the following the chemical formula is given for each substance, the symbols used both here and subsequently, when not otherwise mentioned, refer to the numbers given in the last column of § 2 as the most recent assumptions for the atomic weights, the corresponding atomic weight, and the atomic heat, viz. the product of the specific heat and the atomic weight. 82. Elements and Alloys. Atomic Specific weight. heat. 0-0557 Ag . . . 00 o rH 0-0570 0-0560 A-l . . . . . . 27 4 | 0-2143 0-202 As . . . . . 75 0-0814 Au . . . . . 197 ''Amorphous . . 0-0298 0-0324 0-254 B . . . . . . 10-9 ' ) Graphitoidal 0-235 | Crystalline .... 0-225- 0-230 -0-262 ( 1 0-0288 Bi . . . . . . 210 < | * * ‘ ‘ ’ ’ ’ 0-0308 0-0305 Br . . . . 80 Between —78° and 20° 0-0843 '’Wood charcoal . 0-241 Gas carbon .... 99 .... 0-204 0-185 C . . . . . . 12 - Natural graphite 99 • 0-202 0-174 Iron graphite . . . 0-197 99 ... 0-166 ^Diamond 0-1469 €d . . . . . 112 < f 0-0567 0-0542 Go' . . . . . . 58-8 | r 0-1067 0-0949 Gu . . 63*4 - ) Hammered .... 0-0935 1 Heated f 0-0952 0-0930 0-1100 I ¥e . . . 56 • :::::::: 0-1138 0-112 Hg . . . . 200 . Between —78° and —40° 0-0319 Atomic heat. D. P. 6-02 R. 6-16 Kp. 6-05 R. 5-87 Kp. 5-53 R. 6-11 D. P. 5-88 R. 6-38 Kp. 2-77 R. 2-56 Kp. 2-51 R. 2-45 -2-86 D. P. 6-05 R. 6-47 Kp. 6-41 R. 6-74 R. 2-89 R. 2-45 Kp. 2-22 R. 2-42 Kp. 2-09 R. 2-36 Kp. 1-99 R. 1-76 R. 6-35 Kp. 6-07 R. 6-27 1). P. 6-02 R. 5-93 R. 6-04 Kp. 5-90 D.P. 6-16 R. 6-37 Kp. 6-27 R. 6-38 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 169 Sb Se . Si . Sn Te T1 W Zn Atomic Specific Atomic weight. heat. heat. I . 127 0-0541 R. 6-87 ir ..... 198 0-0326 R. 6-45 K . 39-1 Between — 78° and % . . . 0-1655 R. 6-47 Li . 7 0-9408 R. 6-59 Mg 24 • • • 0-2499 R. 6-00 0-245 Kp. 5-88 Mn 55 . 0-1217 R. 6-69 Mo 96 . 0-0722 R. 6-93 Na 23 . Between -34° and 7°. . . 0-2934 R. 6-75 M 58-8 0-1092 R. 6-42 Gs 199-2 0-0311 R. 6-20 '"Yellow, between 13° and 36° 0-202 Kp. 6-26 55 „ 7° „ 30° 0-1895 R. 5-87 P . 31 < 55 „ ~21° „ 7° 0-1788 Pr. 5-54 55 „ -78° „ 10° 0-1740 R. 5-39 LRed „ 15° „ 98° 0-1698 R. 5-26 r . . . 0-0293 D.P. 6-06. Pb to o —7 ) 0-0314 R. 6-50 i . . . 0-0315 Kp. 6-52 Pd 106-6 . 0-0593 R. 6-32 I r 0-0314 D.P. 6-20 Pt 197-4 - \ 0-0324 R. 6-40 1 ) 0-0325 Kp. 6-42 R-h 104-4 0-0580 R. 6-06 1 0-1880 D. P. 6-02 S . 32 - Rhombic, between 14° and 99° 0-1776 R. 5-68 l L 55 „ 17° „ 45° 0-163 Kp. 5-22 0-0507 D.P. 6-20 122 79-4 28 118 128 204 184 65-2 ( Amorphous, bet. —27° and 8° « Crystalline, „ 98° „ 20° L » m » -18° „ 7° f Grapbitoidal Crystallized 4 „ .... 0-167- Fused 0-156- 0*0508 0-0523 0-0746 0-0762 0-0745 0-181 0-165 -0-179 0-138 -0-175 0-0514 0-0562 0-0548 0-0474 0-0475 0-0336 0-0334 0-0927 0-0956 0-0932 It. Kp. R. R. R. Kp. Kp. R. 6-20 6-38 5- 92 6- 05 5-92 5-07 4-62 4-68-5-01 Kp. R. 4- D. P. R. Kp. R. Kp. R. R. D.P. R. Kp. 3-86 -4-90 6-06 6-63 6-46 6-07 6-08 6-85 6-15 6-04 6-23 6-08 2 a 2 170 PROEESSOR KOPP ON THE SPECIFIC HEAT OE SOLID BODIES. Alloys which only melt far above 100°. Atomic •Specific Atomic weight. heat. heat. Bi Bn ... . 328 0-0400 R. 13,1 Bi Sn2 . . . . 446 0-0450 R. 20-1 Bi Sn2Sb . . . 568 0-0462 R. 26-2 BiSn2SbZn2 . . 698-4 0-0566 R. 39-5 Pb Sb . . . . 329 0-0388 R. 12-8 Pb Bn ... . 325 0-0407 R. 13-2 PbSn2 . . . . 443 83. Arsenides and Sulphides. 0-0451 R. 20-0 Co As2 . . . . 208-8 Speis cobalt 0-0920 N. 19-2 As the locality of this mineral is not given, the formula and atomic weight are not certain. Metals replacing the cobalt can, however, have little influence on the atomic weight and the product. Ag2S. . . . 248 F used .... 0-0746 R. 18-5 €o As S . . . 166 Cobalt glance 0-1070 N. 17-8 Cu2 B . . . 158-8 < Fused .... Copper glance 0-1212 0-120 R. Kp. 19-2 19-1 PeAsB . . . 163 Mispickel . . . 0-1012 N. 16-5 AsS . . . . 107 Commercial 01111 N. 11-9 CoS . . . . 90-8 Fused .... 0-1251 R. 11-4 Cui Pei S . . 91-7 1 Copper pyrites 0-1289 0-131 N. Kp. 11-8 12-1 Be S . . . . 88 Fused .... 0-1357 R. 11-9 ' Cinnabar . . 0-052 N. 121 HgB . . . . 232 \ 55 • 0-0512 R. 11-9 ( 0-0517 Kp. 12-0 M'S . . . . 90-8 Fused .... 0-1281 R. 11-6 ' Galena .... 0-053 N. 12-7 PbS . . . . 239 ^ 0-0509 R. 12-2 ( ' „ .... 0-0490 Kp. 11-7 SnS . . . . 150 Fused .... 0-0837 R. 12-6 I r Zinc-blende 0-1145 N. 11-1 Zn S . . . . 97-2 * | 0-1230 R. 12-0 1 0-120 Kp. 11-7 Pe7S8 . . . 648 < \ Magnetic pyrites 0-1533 0-1602 N. R. 99-3 103-8 As9 So . . 246 Natural .... 0-1132 N. 27-8 Bi2 S3 . . . 516 Artificial 0-0600 R, 31-0 Sb2S3 . . . 340 < f Natural . . . 0-0907 N. 30-8 1 Artificial 0-0840 R. 28-6 CMarcasite . . . 0-1332 N. 164) ] Iron pyrites 0-1275 N. 15-3 PeS2 . . . . 120 ‘ 0-1301 R. 15-6 l 0-126 Kp. 15-1 Mo S2 . . . 160 i \ Natural . . . 0-1067 0-1233 N. R. 171 19-7 Bn S2 . . . 182 Aurum musivum 0-1193 R. 21-7 PROFESSOK KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 84. AgCl. €u Cl . Hg Cl. KC1 . Li Cl . NaCl . Rb Cl . NH4C1 Ba Cl2 Ca Cl2 SgCl2 MgCl2 Mn Cl2 Rb Cl2 Bn CL Sr Cl 2 . Zn Cl2 BaCl2+2H20 CaCl2+6H“ Rt K2 Cl6 Bn K9 CL Cr2Cl6 AgBr KBr . Na Br Pb Br2 Agl Cul Hgl KI Nal Hgl2 Rbl2 CaTL A1 Na3 Fle 0 Atomic weight. 143-5 98-9 235-5 74-6 42-5 58-5 120-9 53-5 Fused . Sublimed Fused . Rock-salt Fused . 208 111 271 j Fused I » - 99 f Sublimed 95 126 278 189 158-6 136-2 244 219 285-4 488-6 409-2 317-4 188 119-1 103 367 235 190-4 327 166-1 150 454 461 78 210-4 ( Fused I ,, Between —21° and 0° Fused Powder Fused Fluor-spar DLID BODIES. 171 impounds. Specific heat. 0-0911 R. Atomic heat. 13-1 0-1383 R. 13-7 0-0521 R. 12-3 0-1730 R. 12-9 0-171 Kp. 12-8 0-2821 R. 12-0 0-2140 R. 12-5 0-213 Kp. 12-5 0-219 Kp. 12-8 0-112 Kp. 13-5 0-373 Kp. 20-0 0-0896 R. 18-6 0-0902 Kp. 18-8 0-1642 R. 18-2 0-0689 R. 18-7 0-0640 Kp. 17-3 0-1946 R. 18-5 0-191 Kp. 18-2 0-1425 R. 18-0 0-0664 R. 18-5 0-1016 R. 19-2 0-1199 R. 19-0 0-1362 R. 18-6 0-171 Kp. 41-7 0-345 Pr. 75-6 0-152 Kp. 43-4 0-113 Kp. 55-2 0-133 Kp. 54-4 0-143 Kp. 45-4 0-0739 R. 13-9 0-1132 R. 13-5 0-1384 R. 14-3 0-0533 R. 19-6 0-0616 R. 14-5 0-0687 R. 13-1 0-0395 R. 12-9 0-0819 R. 13-6 0-0868 R. 13-0 0-0420 R. 19-1 0-0427 R. 19-7 0-2082 N. 16-2 0-2149 R. 16-8 0-209 Kp. 16-3 0-238 Kp. 50-1 * The preparation contained carbonate of soda. 172 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. Atomic 85. Oxides. Specific Atomic weight. heat. heat. Gu2 O . . . . . 142-8 \ \ Bed copper ore 99 0-1073 0-111 N. Kp. 15-3 15-9 H20 . . . . . . 18 J [ Ice between —21° and — 2° . 0-480 Pr. 8-6 1 „ 78° „ 0° . 0-474 B. 8-5 Desains found the specific heat of ice between —20° and 0° to be 0513 ; Person, be- tween — 20° and 0° =0-504 ; Hess, between —14° and 0° =0-533. Person is of opinion that ice, even somewhat below its melting-point, between —2° and 0°, absorbs heat of fusion. GuG . . MgO . . Mn G . . . MO . . . Pb O . . . ZnO Mg 0+H2G Fe3 04 Mg Al2 04 . Mg*Fe*Gr*Al* A1203 . . As2 Oq . . b2 03 Bi203 0ro 0Q O, *eTi*Oa . Sb2 03 . . Mn2 03+H2G 79-4 216 40 71 74-8 223 Commercial Crystalline Feebly ignited Strongly ignited . Fused .... Crystalline powder 81 58 232 -{ Brucite . . Magnetic iron ore 142-8 196 102-8 198 69-8 468 152-4 160 ■i Spinelle Chrome iron ore . Sapphire Opaque Fused . 155-5 . 292 . 176 Crystalline .... Artificial, feebly ignited „ strongly ignited Specular iron .... Iserine Fused . Manganite 0-137 N. 10-9 0-1420 B. 11-3 0-128 Kp. 10-2 0-049 N. 10-6 0-0518 B. 11-2 0-0530 Kp. 11-4 0-276 N. 11-0 0-2439 B. 9-8 0-1570 B. 11-1 0-1623 B. 12-1 0-1588 B. 11-9 0-0509 B. 11-4 0-0512 B. 11-4 0-0553 Kp. 12-3 0-132 N. 10-7 0-1248 B. 10-1 0-312 Kp. 18-1 0-1641 N. 38-1 0-1678 B. 38-9 0-156 Kp. 36-2 0-194 Kp. 27-7 0-159 Kp. 31-2 0-1972 N. 20-3 0-2173 B. 22-3 0-1279 B. 25-3 0-2374 B. 16-6 0-0605 B. 28-3 0-196 N. 29-9 0-1796 B. 27-4 0-177 Kp. 27-0 0-1757 B. 28-1 0-1681 B. 26-9 0-1692 N. 27-1 0-1670 B. 26-7 0-154 Kp. 25-1 0-1762 N. 27-4 0-177 Kp. 27-5 0-0901 B. 26-3 0-176 Kp. 31-0 PEOFESSOE KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. Pyrolusite f Quartz Mn G2 . . Atomic weight. . . 87 SiG2 . . . . . 60 SixZr*G2 . . . 90*8 Sn 02 . . 150 TiG2 . . . . . 82 -Mo G3 . . . . . 144 wo3 . . . . . 232 K2GG3 . . . . 138*2 Na2GG3. . . . 106 Rb2 G ©3 . . . . 230*8 Ba G ©3 . . 197 €a€Qg CaxMgi€G3 Fe G ©0 1 Zircon Cassiterite Artificial Eutile . Brookite Fused . | Pulverulent 86. Carbonates and Silicates. Fused Witherite 100 92 116 -Calc-! spar Arragonite rr | Spathic iron SOLID BODIES. 173 Specific Atomic heat. heat. 0*159 Kp. 13*8 0*1883 N. 11*3 0*1913 E. 11*5 0*186 Kp. 11*2 0*1456 E. 13*2 0*132 Kp. 12*0 0*0931 N. 14*0 0*0933 E. 14*0 0*0894 Kp. 13*4 0*1716 E. 14*1 0*1724 N. 14*1 0*1703 E. 14*0 0*157 Kp. 12*9 0*161 Kp. 13*2 0*1324 E. 19*1 0*154'? Kp. 22*2 0*0798 R. 18*5 0*0894? Kp. 20*7 0*2162 R. 29*9 0*206 Kp. 28*5 0*2728 E. 28*9 0*246 Kp. 26*1 0*123 Kp. 28*4 0*1078 N. 21*2 0*1104 R. 21*7 0*2046 N. 20*5 0*2086 R. 20*9 0*206 Kp. 20*6 0*2018 N. 20*2 0*2085 R. 20*9 0*203 Kp. 20*3 0*2161 N. 19*9 0*2179 R. 20*0 0*206 Kp. 19*0 0*182 N. 21*1 0*1934 R. 22*4 The minerals investigated doubtless contained part of the iron, replaced by metals of lower atomic weight. The atomic weight and the product assumed above are somewhat too great. Feji. Mm?T Mg^ G G3 1 1 2 • 9 Mg-FejGOj, . . 91 T PbG0Q . . 267 Spathic iron 0T66 ( Cerussite 1 0*166 Kp. 18*7 0*227 N. 20*7 0*0814 N. 21*7 0*0791 Kp. 21*1 Eegnault found for precipitated carbonate of lead still containing water, the specific heat 0*0860. 174 PKOFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. Atomic Specific Atomic •weight. heat. heat. Sr € 03 . . . . 147-6- Strontianite Artificial . 0-1445 0-1448 N. R. 21-3 21-4 GaSi 03 . . . 116 Wollastonite 0-178 Kp. 20-7 Gai Mgi Si 03 . . 108 j [ Diopside from Tyrol [ . » 0-1906 0-186 N. Kp. 20-6 20-1 CuSi 03-f H2 0 . 157-4 Dioptas 0-182 Kp. 28-7 | f Olivine 0-189 Kp. 27-6 MgfrFeT?rSi 04 . 145-8^ Crysolite 0-189 Kp. 27-6- 1 0-2056 N. 30-0 1 | Adularia 0-1861 N. 103-7 Al2 K2 Si6 016 . . 557 \ Orthoclase 0-1911 N. 106-4 1 1 „ 0-183 Kp. 101-9 Al2 Na2Si6016 . . 524-8 j i Albite 0-1961 0-190 N. Kp. 102-9 99-7 Borates , Molybdates , Tungstates , Chromates, and Sulphates. KB02 . . . . 82' Fused . . 0-2048 R. 16-8 NaB02 . . . . 65-9 55 •••••• . . 0-2571 R. 16-9 Bb B2 04 . . . . 292-8 55. . . 0-0905 R. 26-5 Pb B4 07 . . . . 362-6 55 . . 0-1141 R. 41-4 K2B407 . . . . 233-8 55 . . 0-2198 R. 51-4 Na2B407 . . . 201-6 j [ :::::: . . 0-2382 . 0-229 R. Kp. 48-0' 46-2 Na2B407 + lOH20 381-6 Crystallized borax . . 0-385 Kp. 146-9 Pb Mo 04 . . . 367 Yellow lead ore . . . . . 0-0827 KP. 30-4 GaW04 . . . 2:88 Scheelite . . 0-0967 Kp. 27-9 Pe| Mnf W 04 . . 303-4 j \ Tungsten 1 „ . . 0-0930 . . 0-0978 Kp. R. 28-2 29-7 The locality of the wolfram investigated by Regnault is not known, and the com- position uncertain. But the change in the ratio in which iron and manganese are present in the mineral alters little in the atomic weight. PbGr 04 K2 Gr ©4 K2Gr207 khso4 k2so4 . Na2S04 . n2h8so4 BaS04 . Ca S©4 . 323.4 . 194-4 . 2:94-6 . 136-1 . 174-2 . 142 . 132 . 233 . 136 Fused 0-0900 Kp. 29-0 Crystallized 0-1851 R. 36-0 5? 0-189 Kp. 36-7 55 0-1894 R. 55-8 55 0-186 Kp. 54-8, 5? * 0-244 Kp. 33-2 Fused 0-1901 R. 33.-1 Crystallized 0-196 Kp. 34-1 Fused 0-2312 R. 32-8 Crystallized 0-227 Kp. 32-2 ,5 . 0-350 Kp. 46-2 Heavy spar 0-1088 K 25-4 0-1128 R. 26-3 9? 0-108 Kp. 25-2 Calcined gypsum .... 0-1966 R. 26-7 Anhydrite .' . 0-1854 N. 25-2 55 ••••••• 0-178 Kp. 24-2 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 175 Atomic Specific Atomic weight. heat. heat. €uSG4 159-4 Solid pieces . 0-184 Pp. 29-3 MgS04 120 J Dehydrated salt . . 0-2216 R. 26-6 Solid pieces . . . 0-225 Pp. 27-0 MnS04 151 ,, . 0-182 Pp. 27-5 Artificial . . 0-0872 R. 26-4 PbS04 ..... 303 4 Lead vitriol . 0-0848 N. 25-7 l . 0-0827 Kp. 25-1 Artificial . . 0-1428 R. 26-2 SrS04 183-6 ^ Celestine . . . . 0-1356 N. 24-9 i . 0T35 Kp. 24-8 ZnS04 161-2 Coarse powder . 0-174 Pp. 28-0 0uS04+HQ0 . . 177-4 Pulverulent . 0-202 Pp. 35-8 Mg S04+H9 0 . . 138 Coarse powder . 0-264 Pp. 36"4 ZnS04+Ho 0 . . . 179-2 Solid pieces . 0-202 Pp. 36-2 €aS04+2H20 . . 172 j Gypsum . . . . 0-2728 . 0-259 N. Kp. 46-9 44-6 €uS04+2H20 . . 195-4 Pulverulent . 0-212 Pp. 41-4 ZnS04+2H20 . . 197-2 Solid pieces . 0-224 Pp. 44-2 Fe S04+3 H20 206 99 * . 0-247 Pp. 50-9 €uS04+5H20 . . 249-4 J [ Crystallized . . L . 0-285 . 0-316 Kp. Pp. 71-1 78-8 MnS04+5H20 . . 241 J l :: : : . 0-323 . 0-338 Kp. Pp. 77-8 81-5 MS04+6 He, 0 . . 262-8 99 • * . 0-313 Kp. 82-3 0oB04+7H;0 . . 280-8 99 * ■ . 0-343 Kp. 96-4 FeS04+7H20 . . 278 j f . 0-346 . 0-356 Kp. Pp. 96-2 99-0 MgS04+7H20 . . 246 J i ” : : . „ 0-362 . 0-407 Kp. Pp. 89-1 100-1 ZnS04+7H20 . . 287-2 - 1 : : . 0-347 . 0-328 Kp. Pp. 99-7 94-2 Mg K2 S2 08+ 6 H9 0 402-2 99 . 0-264 Kp. 106-2 NiK2 s2 08+61I20 437 99 . 0-245 Kp. 107-1 ZnK2 B.,08+6 HL0 443-4 99 . 0-270 Kp. 119-7 A12K2S4016+24H20 949 „ alum . 0-371 Kp. 352-1 €r2K2S4016+24H20 998-6 „ chrome alum . 0-324 Kp. 323-6 88. Arseniates, Phosphates, Pyrophosphates and Metaphosphates, Nitrates, Chlorates , Perchlorates, and Permanganates. K As 03 . . . . 162-1 Fused '. . . . . . . . 0-1563 R. 25-3 K H2 As 04 . . . 180-1 Crystallized .... . . 0-175 Kp. 31-5 Pb3As208 . . . . 899 Fused . . 0-0728 R. 65-4 Ag3P04 . . . . 419 Pulverulent .... . . 0-0896? Kp. 37-5 KH2P04 . . . . 136-1 Crystallized .... . . 0-280 Kp. 28-3 Na2HP04+12H20 358 Between — 21° and 2° . . . 0-408 Pr. 146-1 The determination of the specific heat refers to the crystallized salt. For the fused and afterwards solidified salt Person found the specific heat between the same range of temperature considerably greater, =0'68 to 0'78; but the mass obtained by solidifying MDCCCLXV. 2 B 176 PROFESSOR ZOPP OA THE SPECIFIC HEAT OE SOLID BODIES. the fused salt gradually alters (it becomes crystallized again) with increase of volume, which is very considerable when the fused salt is allowed to cool very rapidly. Atomic Specific Atomic. weight. heat. heat. Pb3P2 08 . . . . 811 0-0798 R. 64.7 k4p907 . . . . 330-4 Fused 0-1910 R. 63-1 Na4 P2 07 266 0-2283 R. 60-7 Pb9 P9 07 . . . . 588 0-0821 R. 48-3 Na P 03 102 0-217 Kp. 22-1 CaP2©6 . . . . 198 0-1992 R. 39-4 Ag N 03 . . . . 170 0-1435 R. 24-4 [ „ 0-2388 R. 24-1 KN03 101-14 , 0-227 Kp. 22-9 Ki Na4 N 03 . . . Crystallized 0-232 Kp. 23-5 93 Fused* 0-235 Pr. 21-9 „ 0-2782 R. 23-6 Na N 03 . . . . . 85 0-256 Kp. 21-8 N2H403 . . . . 1 [ Crystallized ...... 0-257 Kp. 21-8 80 0-455 Kp. 36-4 Ba N2 06 . . . . 261 j r 0T523 0-145 R. Kp. 39*8 37-9 Pb N2 06 331 3i5 0-110 Kp. 36-4 Sr N2 06 . . . . 211-6 0-181 Kp. 38-3 K Cl 03 , . . . . 122-6 j i Fused Crystallized 5? 0*2096 0-194 R. KP. 25*7 23*8 BaCl206+H20 . . 322 0-157 Kp. 50-6 K Cl 04 . . . . . 138-6 0-190 Kp. 26-3 K Mn 04 . . . . 158-1 5? 0*179 Kp. 28*3 89. So-called Organic Compounds. Hg€2N2 . . . . 252 Crystallized cyanide of mercury 0-100 Kp. 25*2 ZnK204N4 . . . 247-4 J \ ,, cyanide of zinc and ] 1 potassium J l 0-241 Kp. 59-6 BeK3C6N6 . . . 329-3 \ | Crystallized ferricyanide of po- ) I tassium I [ 0-233 Kp. 76*7 Be K4 06 Ng+ 3 H2 0 422-4 j [ Crystallized ferrocyanide of po- | [ tassium J \ 0-280 Kp. 118-3 g2ci6 237 Between 18° and 37° . . . 0-178 Kp. 42-2 The specific heat between 18° and 43° was found = 0T94; between 18° and 50° = 0-277. €10 H8 128 Between -26° and 18° . . 0-3096 A. 39-6 The specific heat of naphthaline was found to be 0-3208 between 0° and 20°, and 0-3208 between 20° and 65°. G27 H54°2 G46 H92 6^2 . 410 . 676 } Between —21° and 3° 0-4287 Pr. 175-8 289-8 * Obtained as mass of constant melting-point (2190,8) by fusing equivalent quantities of nitrate of potass and nitrate of soda. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 177 The first formula is that of one constituent of bees’ wax, cerotic acid ; the second is that of the other, palmitate of melissyle. In reference to the numbers found for the specific heat of bees’ wax at higher temperatures, compare the last remark in § 77. Atomic Specific Atomic weight. heat. heat. ~ ^ 049 f Crystallized cane-sugar . . . 0-301 Kp. 102-9 12 22 H • • 0 | Amorphous cane-sugar . . . 0-342 Kp. 117-0 €6H1406 .... 182 Mannite 0-324 Kp. 59-1 04H604 .... 118 Succinic acid 0-313 Kp. 36-9 04H606 .... 150 Tartaric acid 0-288 Kp. 43-2 €4H606+H20 . . 168 Racemic acid 0-319 Kp. 53-6 O2H2Ba04 . . . 227 Formate of baryta .... 0-143 Kp. 32-5 02K204+H20 . . 184-2 Neutral oxalate of potass . . 0-236 Kp. 43-5 04H3K08+2H2 0 . 254-1 Quadroxalate of potass . . 0-283 Kp. 71*9 04H5K06. . . . 188-1 Acid tartrate of potass . . . 0-257 Kp. 48-3 €4H4NaK06+4H2O 282-1 Seignette salt 0-328 Kp. 92-5 08Hlo0a0lo+8 H20 450 Acid malate of lime . . . 0-338 Kp. 152-1 The preceding Tables contain the material, obtained experimentally, which serves as subject and basis for the subsequent considerations on the relations of the specific heat of solid bodies 'to their atomic weight and composition. PART Y.— ON THE RELATIONS BETWEEN ATOMIC HEAT AND ATOMIC WEIGHT OR COMPOSITION. 90. I discuss in the sequel the regularities exhibited by the atomic heats of solid bodies, the exceptions to these regularities, and the most probable explanation of these exceptions. In regard to the views which I here develope, much has been already expressed or indicated in former speculations ; in this respect I refer to the first part of this paper, in which I have given the views of earlier inquirers as completely as I know them, and as fully as was necessary to bring out the peculiar value of each. It is unnecessary, then, to refer again to what was there given ; but I will complete for individual special points what is to be remarked from an historical point of view. But before discussing these regularities, the question must be discussed whether the atomic heat of a given solid substance is essentially constant, or materially varies with its physical condition. It depends on the result of this investigation, how far it may with certainty be settled whether the general results already obtained are of universal validity, or whether exceptions to them exist. The specific heat of a solid body varies somewhat with its temperature ; but the variation of the specific heat with the temperature is very small, provided the latter does not rise so high that the body begins to soften. Taking the numbers obtained by Regnault for lead, by Dulong and Petit, and by Bede and by Bystkom, for the specific heats of several metals at different temperatures, the conviction follows that the changes of specific heat, if not of themselves inconsiderable, are yet scarcely to be regarded in comparison with the discrepancies in the numbers which different observers have found 2 b 2 178 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. for the specific heat of the same body at the same temperature. At temperatures at which a body softens, the specific heat does indeed vary considerably with the tempera- ture (compare for example § 77); but these numbers, as containing already part of the latent heat of fusion, give no accurate expression for the specific heat, and are altogether useless for recognizing the relations between this property and the atomic weight or composition. Just as little need the small differences be considered which Regnault found for a few metallic substances according as they were hammered or annealed, hard or soft. For dimorphous varieties of the same substance, even where there are considerable differences in the specific gravity, the specific heats have not been found to be materially different (compare FeS2, § 83 ; T-i©2, § 85; Ca€ 03, § 86). The results obtained with these substances appear to me more trustworthy than those with graphite and the various modifications of boron and silicium, which moreover have given partly the same specific heat for the graphitoidal and adamantine modification of the same element. What trustworthy observations we now possess decidedly favour the view that the dimorphic varieties of the same substance have essentially the same specific heat. 91. The view has been expressed that the same substance might have an essentially different specific heat, in the amorphous and crystalline conditions. I believe that the differences of specific heat found for these different conditions depend, to by far the greatest extent, upon other circumstances. The Tables in § 83 to § 89 contain a tolerable number of substances which have been investigated both after being melted, and also crystallized ; there are no such differences in the numbers as to lead to the supposition that the amorphous solidified substance had a different specific heat to what it had in the crystallized state. No such influence of the condition has been with any certainty shown to affect the validity of Dulong and Petit’s, or of Neumann’s law. I may here again neglect what the determinations of carbon, boron, or silicium appear to say for or against the assumption of a considerable influence of the amorphous or crystalline condition on the specific heat. Re gn AULT found (§ 85) that the specific heat of artificially prepared (uncrystalline'?) and crystal- lized titanic acid did not differ. According to my investigations (§ 48) silicic acid has almost the same specific heat in the crystallized and in the amorphous condition. In individual cases, where the specific heat of the same substance for the amorphous and crystallized modification has been found to be materially different*, it may be shown that foreign influences affected the determination for the one condition. Such influ- ences are especially: 1. That one modification absorbed heat of softening at the tem- perature of the experiment ; that is doubtless the reason why the specific heat of yellow * De la Rive and Makcet (Ann. de Chim. et de Phys. [2] vol. lxxv. p. 118) found the specific heat of vitreous to be different from that of opaque arsenious acid, and considered the fact to he essential ; hut their method was not fitted to establish such a difference. Pape’s view, too (Poggendokff’s Annalen, vol. cxx. pp. 341 and 342), that it is of essential importance for the specific heat of hydrated sulphates whether the salts are crystallized or not, does not appear to me to he proved by what he has adduced. PROFESSOR. KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 179 phosphorus was found to be considerably greater at higher temperatures than that of red phosphorus, but not at low ones (compare § 82), that the specific heat of amorphous cane-sugar was found to be decidedly greater than that of crystallized (§ 78), and, ac- cording to Regnault’s opinion, also that the specific heat of amorphous selenium between 80° and 18° was found much greater ( = 0103) than that of the crystalline, while for lower temperatures there was no difference in the specific heats of the two substances (§ 82). 2. That in heating one modification its transition into the other is induced, and the heat liberated in this transition makes the numbers for the specific heat in- correct; in § 33 I have discussed the probability that this circumstance, in Regnault’s first experiments with sulphur, gave the specific heat much too high, and it is possible that it was also perceptible in the above-mentioned experiments with amorphous sele- nium. 3. That in immersing heated porous bodies in the water of the calorimeter heat becomes free (compare § 19) ; I consider this as the reason why Regnault found the specific heat of the more porous forms of carbon so much greater than that of the more compact (compare § 36) ; and Regnault himself sees in this the reason why he found the specific heat of the feebly ignited and porous oxides of nickel and of iron greater than that of the same oxides after stronger heating (compare § 85). From the importance of this subject for the considerations to be afterwards adduced, I have here had to discuss more fully what differences are real and what are only appa- rent in the numbers found for the specific heat of one and the same substance. Even if the apparent differences are often considerable, their importance diminishes, if allowance is made for the foreign influence which may have prevailed. In many cases, on the other hand, a body in totally different modifications has almost exactly the same specific heat if these foreign influences are excluded. It may, then, be said that, from our present knowledge, one and the same body may exhibit small differences with cer- tain physical circumstances (temperature, different degree of density), but never so great that they may be taken as an explanation why a body decidedly and undoubtedly forms an exception to a regularity which might have perhaps been expected for it — provided that the determination of the specific heat, according to which the body in question forms an exception, is trustworthy, and kept free from foreign influences. 92. Among the regularities in the atomic heat of solid bodies, that found by Dulong and Petit for the elements stands foremost. A glance at the atomic heats of the so- called elements collated in § 82, shows that for by far the greater number the atomic heats are in fact approximately equal. But the differences in the atomic heats, even of those elements which are usually regarded as coming under Dulong and Petit’s law, are often very considerable, even when the comparison is limited to those which are most easily obtained in a pure state, and even if numbers are taken for the specific heats which give the most closely agreeing atomic heats. Regnault * sought an explanation of the differences of the atomic heats of the elements in the circumstance that the latter could not be investigated in comparable conditions of temperature and density ; further^ that the numbers for the specific heat, as determined for solid bodies, contain, besides * Annal. de Chim. et de Phys. [2] vol. lxxiii. p. 66, and [3] vol. xlvi. p. 257. 180 PROFESSOR KOPP OjSt THE SPECIFIC HEAT OF SOLID BODIES. the true specific heat (for constant volume), also the heat of expansion. As specific heat we can indeed only take the sum of the heats necessary for heating and for expan- sion. But it is not yet proved that the products of the first, quantity (the specific heat for constant volume) and the atomic weights would agree better than the atomic heats now do ; it is only a supposition, and even the very contrary may be possible with individual substances. Temperature has an influence on the specific heat of solid bodies, and to a different extent with different bodies. Even in this respect, also, all means are wanting by which the different temperatures at which bodies are really comparable can be known, and a comparison made of their atomic heats. The utmost possible is to determine the specific heat at such a distance from the melting-point that latent heat of softening can have no influence. It is impossible to say with certainty whether the atomic heats of bodies compared at other temperatures than those which are nearly identical (ranging about 90° on each side of 10°) will show a closer agreement. It is not probable. Changes in the specific heat of solid bodies, so long as they are unaffected by heat of softening, are small in comparison with the differences which the atomic heats of individual elements show. And it is well worth consideration that individual elements (phosphorus and sulphur, e.g.) at temperatures relatively near their melting-points, have not materially greater specific heats than other elements (iron and platinum, for example) at temperatures relatively distant from their melting-points, but, on the con- trary, considerably smaller. As regards the influence of density on the specific heat, it is undoubtedly certain that the latter may somewhat vary with the former ; but it is equally so that, in all cases in which substances of undoubted purity were examined and the sources of error mentioned (§91) excluded, this variation is too inconsiderable to give an adequate explanation of the differences of the atomic heats found for the various solid elements. I need not here revert to the considerations developed in §§ 90 and 91, as to how far a difference in the physical condition of a solid substance exercises an essential influence on its specific heat ; for whatever view may be held in reference to this influence, and generally in reference to the circumstances which alter the specific heat of a substance, and therewith the atomic heat, this is certain, that there are individual elements whose atomic heat is distinctly and decidedly different from that of most other elements. Such elements are, from § 82, first of all boron, carbon, and silicium. The decision of the question whether these elements really form exceptions to Dulong and Petit’s law presupposes, besides a knowledge of their specific heat, a knowledge of their atomic weight also. There can be no exceptions to Dulorg and Petit’s law, if, regardless of anything which may be in opposition to it, the principle is held to, that the atomic weights of the elements must be so taken as to agree with this law. As a trial whether this law is universally applicable, the atomic weights ought rather to be taken as established in another manner. It may be confessed that the determination of the true atomic weights by chemical and physico-chemical investigations and considerations is still uncertain, and many questions are still unanswered the settlement of which may influence that determination. But there seems now to be no more trustworthy basis PKOFESSOll KOPP OIST THE SPECIFIC HEAT OF SOLID BODIES. 181 for fixing the atomic weights of the elements than that of taking, as the atomic weights of the elements, the relatively smallest quantities which are contained in equal volumes of their gaseous or vaporous compounds, or of which the quantities contained in such volumes are multiples in the smallest numbers; and no better means appear to exist for determining the atomic weights of those elements the vapour-densities of whose compounds could not be determined, than the assumption that in isomorphous compounds the quantities of the corresponding elements are as the atomic weights of the latter. On this basis, and using this means, the numbers for the atomic weights have been determined which are contained in the last column of the Table in § 2, and are used in § 82 et seq. The atomic weights B=10*9, €=12, Si =2 8, cannot be changed for others. That the atomic weights of tin and silicium are as 118 to 28, is further proved by the isomorphism of the double fluorides. But to these atomic weights correspond atomic heats which are far smaller than those found for most other elements. From the chemical point of view it is inadmissible to take the atomic weights of boron, carbon, and silicium * in such a manner as to make their atomic heats agree with Dulong and Petit’s law. In any case these three elements form exceptions to Dulong and Petit’s law. The sequel will show that this is the case with many other elements. 93. In many compounds the regularity is observed, that by dividing their atomic heat by the number of elementary atoms contained in one molecule of the compound, a quotient is obtained which comes very near the atomic heat of most of the elements — that is, 6-4. This is found in the alloys enumerated in § 82, and also in a great number of compounds of definite proportions. A few of the most important cases may be given here. For speiscobalt, CoAs2 (compare § 83), this quotient is ^=6*4; for the chlorine compounds, R Cl and R Cl f , the mean of the atomic heats given in § 84 is 12*8, and the quotient —=Q'4:. Of the chlorine compounds, R Cl2, the mean atomic heat of all the determinations in § 84 is 18*5, and the quotient ^=6*2. It is also very near this value in the double chlorides; inZnK2 Cl4 it is ^ =6*2, for R K2 Cl6 (the mean of the determinations of PbK2 Cl6 and Sn K2C16) it is ~=6T. For bromine compounds, RBr (both here and in the following examples the means are taken of the determinations in § 84), H^=6*9; for PbBr2 ^=6*5; for iodine compounds, RI and RI,^p=6'7, and for the iodine compounds, RI2, ^=6'5. But this regularity, though met with in many compounds, is by no means quite * For Begnatjlt’s observation, whether, considering the specific heat which he found for silicium, its atomic weight is to be so taken that silicic acid contains 2 atoms of silicium to 5 of oxygen, compare Ann. de Chim. et de Phys. [3] vol. lxiii. p. 30. For Scheekek’s remark, that according to the most probable specific heat of silicium its atomic weight must be taken so that for 1 atom of silicium there are 3 atoms of oxygen, compare Poggendoeff?s ‘ Annalen,’ vol. cxviii. p. 182. + In the sequel E stands for a uni-equivalental and E a polyequivalental atom of a metal. 182 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. universal. The oxygen compounds of the metals correspond to it in general the less the greater the number of oxygen atoms they contain as compared with that of metal. The mean atomic heat of the oxides EG in § 85 is 11T, and the quotient ^=5*6. The quotient for the oxides R203 and R2 03 (even excluding the determinations of alumina and boracic acid) is only ?7j?=5*4; for the oxides R02 (even excluding the determinations for silicic acid and zircon) only ^=4*6 ; for the oxides R03, the mean of Regnault’s determinations only ~=4-7. Still smaller is the quotient for com- pounds which contain boron in addition to oxygen ( e . g. for the compounds R B02 (compare § 87) it is only — =4*2; for boracic acid, B2 03, it is only I^=3*3), and also for compounds which contain silicium in addition to oxygen (it is ^=3*8 for silicic acid, Si 02, compare § 85), or which contain oxygen as well as hydrogen (for ice, II2 0, it is only ^=2*9*, compare § 85), or which contain hydrogen and carbon besides oxygen (e. g. it is only ^=2*6 for succinic acid, 04H6 O4, compare § 89). It may be said in a few words what are the cases in which this quotient approximates to the atomic heat of most elements, and what the cases in which it is smaller. It is near 6 ’4 in those compounds which only contain elements whose atomic heats, corresponding to Dulong and Petit’s law, are nearly = 6*4; it is smaller in compounds which contain elements not coming under Dulong and Petit’s law and having a much smaller atomic heat than 6*4, and which are recognized as exceptions to this law, either directly, if their specific heat has been determined for the solid condition (compare § 92), or in- directly, if it be determined in the manner to be subsequently described. 94. The determinations of specific heat given in §§ 83 to 89 contain the proofs hitherto recognized for the law that chemically-similar bodies of analogous atomic con- stitution have approximately the same atomic heat ; and a considerable number of new ex- amples of the prevalence of this regularity are given by my determinations. The groups of analogous compounds need not again be collated, as Neumann has done for a smaller and Regnault for a larger number of groups and for individual elements contained in them. What I will here discuss is the prevalence, beyond the limits of our previous * Considering the atomic heat of liquid water to be 18, Garnier (Compt. Rendus, vol. xxxv. p. 278) thought that the quotient obtained by dividing the atomic weight by the number of elementary atoms in one atom of the compound, -U =6, came near the atomic heat of the elements. But it requires no explanation that, in a comparison with the atomic heats of solid elements and solid compounds, that atomic heat must he taken for the compound H2 9 which is obtained from the specific heat of ice, and not from that of water. Garnier is not alone in his error, which is rather to he ascribed to the circumstance that formerly both solids and liquids were compared, as regards their specific heat, in considerations how this property is influenced by the composition. Hermann more especially (Nouveaux Memoires de la Societe des Naturalistes de Moscou, vol. iii. p. 137) compared liquid water with solid compounds, as did also Schroder (Poggendorff’s * Annalen,’ vol. Iii. p. 279) and L. Gmeein in an early discussion of this subject (Gehler’s ‘ Physicalische Worterbuch, neue Bearbeitung,’ vol. ix. p. 1942), while he subsequently (Handbuch der Chemie, 4. Aufl., vol. i. p. 220) more correctly compared the specific and the atomic heat of ice with that of other solid compounds. PEOFESSOE KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 183 knowledge, of the regularity, that compounds of analogous atomic constitution have approximately the same atomic heat. To this belongs, first, the existence of this regularity in the case of chemically similar bodies, which exhibit an analogy of atomic constitution, when their formulae are written with the atomic weights admitted in recent times for the elements, but which could not be recognized so long as the equivalents of the elements were taken as a basis, or the formula written, as by Regnault, with the use of the so-called thermal atomic weights. The approximate equality of the atomic heats of analogous nitrates and chlorates, of the alkalies for example, had been already observed. The same character, the haloid, is ascribed both to carbonates and to silicates, but as these formulae were formerly written, an analogy in the composition of chlorates and nitrates, or carbonates and silicates, could not be assumed. But salts of these four different classes, as well as arseniates and metaphosphates, have analogous atomic constitutions if we assume the recent atomic weights. The same salts have then also approximately equal atomic heats. We get the atomic heat Of chlorate of potass, K Cl 03, § 88 M* 24*8 „ the nitrates, RN03, in § 88 M 23-0 ,, metaphosphate of soda, NaP03, § 88 22T ,, arseniate of potass, KAs03, §88 25-3 „ the carbonates, RG03, § 86 M 207 „ the silicates, RSi03, § 86 M 20'5 The differences in these approximately concordant atomic heats are partly essential and explainable. I come to this again (§ 95). According to the more recent assumptions for the atomic weights, certain perchlorates, permanganates, and sulphates have analogous atomic composition, and these salts have also approximately equal atomic heats ; this has been found to be For perchlorate of potass, KC104, § 88 26-3 „ permanganate of potass, K Mn 04, §88 28 -3 „ the sulphates, RS04, named in § 88 . M 26T But approximate equality in the atomic heat is not only found in such compounds of analogous chemical composition as have similar chemical character, but also in such as have totally dissimilar chemical character. The chemical character of protosesquioxide of iron (magnetic iron ore) is quite different from that of neutral chromate of potass. Sesquioxide of iron, or arsenious acid, have a chemical character totally different from nitrates or arseniates, or bodies of similar con- stitution But for the first-named compounds and for the last-named compounds, as respectively compared with each other, there is analogy in chemical composition and approximate equality of atomic heat. The atomic heat has been found to be * M signifies the mean of all determinations. 2 C MDCCCLXV. 184 PEOFESSOE KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. For magnetic iron ore, Fe3 04, §85 M 37‘7 „ chromate of potass, K2 Or 04, § 87 M 36‘4 „ sesquioxide of iron, Fe2 03, § 85 M 26-8 „ arsenious acid, As203, § 85 25’3 „ the nitrates, RNG3, named in § 88 23-0 „ arseniate of potass, K As 03, § 88 25-3 But there is even in a more extended sense approximate equality of atomic heat in bodies of analogous atomic composition. If the formulae of the oxides, R 02 (oxide of tin for instance) are doubled, they become R2 G4, and are then analogous to those of the sulphates, R S G4, or of tungstate of lime or of perchlorate of potass and other salts. To the formulae thus made analogous equal atomic heats correspond. The following atomic heats have been found : — Oxide of tin, Sn2 04, compare § 85 . M 27*6 Titanic acid, Ti204, „ M 27’3 The sulphates, R S04, in § 87 M 26T Tungstate of lime, Ga W 04, compare § 87 27-9 Perchlorate of potass, KC104, compare § 88 26*3 Permanganate of potass, KMnG4, compare § 88 28-3 If the formulae of the oxides, RQ2, are trebled they become R3Oe, analogous to those of the nitrates RN2G6 (nitrate of baryta, e.g.), and similar salts. Here also approxi- mately equal atomic heats correspond to the formulae thus made analogous. The atomic heats are as follows : — Oxide of tin, Sn3G6, compare § 85 M 41-4 Titanic acid, Ti3 06, „ M 41*0 The nitrates, RN2G6, in § 88 M 38T Metaphosphate of lime, €a P2 06, compare § 88 39-4 How little the atomic heat of compounds depends on their chemical character may he proved from a greater series of examples than those adduced in the preceding. It is, however, unnecessary to dwell upon this. The comparisons and considerations con- tained in the sequel complete what has here been developed as a proof of the principle that the atomic heat of bodies is independent of their chemical character. 95. The foregoing comparisons give examples of cases in which bodies of analogous atomic structure, with a totally different chemical character, have approximately the same atomic heat ; they show that with reference to the atomic heat, monoequivalent and poly- equivalent elementary atoms have the same influence, which, indeed, followed already from Regnault’s comparisons ; that the atomic heat of a substance for its polyfold atomic formula may be compared with that of another substance for a simple atomic formula. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 185 The preceding contains a generalization of Neumann’s law ; but as certainly as this law is recognized in the preceding in a more general manner than was formerly assumed, as little is it universally applicable. Regnault’s investigations have shown that Neumann’s law is not rigidly valid. Even for those compounds which contain the same element as electronegative constituent, and have similar atomic constitution, he found the atomic heats as much as to 9- dif- ferent from each other*. The reason of this he seeks in the same circumstances, which in his view prevent a closer agreement in the atomic weights of the elements (com- pare § 92). Differences of this kind, and even still more considerable, occur in the atomic heats of compounds for which greater agreement in these numbers might be expected — of such compounds, "that is, as contain elements of the same, or almost the same atomic heat combined with the same other element in the same atomic proportion. To this belongs the fact that the atomic heat has been found so different (§ 85) for the isomorphous com- pounds, magnetic iron ore (37*7), chrome iron ore (31 ’2), and spinelle (27*7), and for alumina (21*3) and for sesquioxide of iron (26‘8). In the atomic heats of such analogous compounds there are differences for which, or rather for the magnitude of which, as furnished by our present observations, I know at present no adequate explanation. But there is another kind of difference in the atomic heats of analogous compounds, which exhibits a regularity, and for which an explanation can be given. Certain elements impress on all their compounds the common characteristic, that their atomic heat is much smaller than that of most analogous compounds. The atomic heat of boracic acid, B2 03, is only 16-6, while that of most other compounds, R2 03 and R2 03, is between 25 and 28 (§ 85). The atomic heat of the borates, R B 02, is (§ 87) only 16-8,. while that of R202, as the mean of the determinations in § 85, is 22*2. The atomic heat of Rb B2 04 is (§ 87) only 26'5, while that of Ee304 (§ 85) in the mean is 37-7. Similar results have been obtained for compounds of certain other elements, of carbon and of silicium for instance, that is, of those elements which in the free state have a smaller atomic heat than that of most other elements. This observation leads to the question whether the elements enter into compounds with the atomic heats which they have in the free state, and in connexion with this, how far is it permissible to make an indirect determination of the atomic heat of the elements (in their solid state) from the atomic heats of their (solid) compounds. 96. The assumption that elements enter into compounds with the atomic heats they have in the free state would be inadmissible, if not only the atomic structure as ex- pressed by the empirical formula, but also the grouping of the elements to proximate constituents, as is endeavoured to be expressed by the rational formula, influenced the atomic heat of the compounds. That the latter is not the case is very probable from the comparisons made in § 94, where approximately equal atomic heats were obtained for compounds of analogous empirical formulae, even with the greatest dissi- * Ann. de Chim. et de Phys. [3] vol. i. p. 196. 2 c 2 186 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. milarity of chemical character. That that, which may be supposed and expressed by the so-called rational formula in reference to the internal constitution of compounds, does not affect the atomic heat, becomes more probable from the fact that chemically similar, and even isomorphous compounds, one of which contains an atomic group in the place of an individual atom in the other, exhibit dissimilar atomic heats. This is seen, for instance, in comparing analogous chlorine and cyanogen compounds (Cy=CN); the latter have far greater atomic heats. Thus the atomic heat Of chloride of mercury, HgCl2, § 84, is 18'0 „ cyanide of mercury, Hg Cy2, § 89 25'2 „ chloride of zinc and potassium, Zn K2 Cl4, § 84 43’4 „ cyanide of zinc and potassium, Zn K2 Cy4, §89 . . . . . . . 59 '6 In like manner ammonium compounds (Am=N H4) have atomic heats considerably greater than the corresponding potassium compounds. This is seen from the following Table : — Chloride of potassium, K Cl, § 84 M 12’9 „ ammonium, Am Cl, § 84 20-0 Nitrate of potass, KN 03, § 88 M 23*5 „ ammonia, Am N 03, § 88 36*4 Sulphate of potass, K2 Sq4, §87 M 336 „ ammonia, Am2 Sq4, § 87 46-2 97. That undecomposable atoms and atomic groups are contained in compounds with the atomic heats they have in the free state is further probable from the fact that the sum of the atomic heats of such atoms, or atomic groups, as when united form a certain compound, is equal or approximately equal to the atomic heat of this compound. For many compounds whose elements obey Dulong and Petit’s law, what has been stated in § 93 contains the proof that the atomic heat of these compounds is equal to the sum of the atomic heats of the elementary atoms contained in one atom of the compounds. That this is also observed when atomic groups are supposed to be united, forming more complicated compounds, will be seen by bringing forward a few examples. The atomic heat has been found For the oxides, BO, enumerated in § 85 M 11T „ sesquioxide of iron, Fe2 03, § 85 M 26*8 Sum for Fe2 R04 . . . 37-9 „ magnetic iron ore, Fe3 04, § 85 M 37*7 „ the oxides, B0, in § 85 M 11T „ the acids, R 03, in § 85, according to Regnault .... M 18-8 Sum for R R 04 . . . 29-9 „ chromate of lead, Pb0r04, §87 29’0 PEOFESSOE KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 187 For the oxides named in § 85, SO M 111 „ binoxide of tin, Sn 02, § 85 M 13-8 SumforRR03 . . . 24-9 „ sesquioxide of iron, Fe2 03, §85 M 26*8 „ chromate of potass, K2€r04, § 87 M 36 '4 „ the acids, R03, in § 85 (Regnault) 18-8 Sum for K2€rRG7 . . . 55*2 „ acid chromate of potass, K2€r2 07, § 87 M 55-3 „ binoxide of tin, Sn306, § 85 M 41*4 „ base, R2 02, mean of determinations, § 85 M 22*2 SumforSgOg . . . 63*6 „ arseniate of lead, Pb3 As208, § 88 65-4 To this belongs the fact that water is contained in solid compounds with the atomic heat of ice*. The different determinations of the specific heat of this substance (§ 85) gave the atomic heat for greater distances from 0°, 8-6, and for temperatures nearer 0°, 9T to 9*2. The atomic heats have been found For BaCl2+2H20, §84 41*7 ForH20. „ the chlorides, R Cl2, § 84 M 18-5 Remains for 2 H2 0 . . . 23-2 11-6 ,, OaCl2+6 H2 O, § 84 75*6 „ the chlorides, R Cl2, § 84 M 18-5 Remains for 6 H2 O . . . 57T 9-5 „ Brucite, Mg G-j-H2 0, § 85 18-1 „ the oxides, R O, § 85 M 11 1 Remains for H2 O . . . . 7‘0 7"0 „ dioptase, €uSi03+H20, § 86 28-7 „ the silicates, R Si 03, § 86 M 205 Remains for H2 O . . . . 8-2 8-2 „ Na2B4O7+10H2O, § 87 146-9 „ Na2B497, §87 47T Remains for 10 H2 O . . . 99-8 10-0 » gypsum, €aS04+2H20, § 87 M 45-8 „ the sulphates, RS04, § 87 M 26-1 Remains for 2 H2 O . . . 19-7 9-9 * Even before Person (compare § 14) L. Gmelin bad speculated (Handbucb der Chemie, [4] Aufl. vol. i. p. 223) whether from the atomic heats of anhydrous sulphate of lime and of ice that of gypsum could be calcu- lated. The results of calculation deviated considerably from the atomic heat as deduced from the observed specific heat of gypsum ; the specific heat, and therewith the atomic heat of ice, were at that time incorrectly known. 188 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. The Tables in § 84 to 89 contain data for several such comparisons, which lead to the same result as the preceding — that the atomic heat of water contained in solid com- pounds may, by subtracting the atomic heat of the anhydrous solid from that of the hydrated solid compound, be obtained in sufficient approximation to the atomic heat deduced from the direct determination of the specific heat of ice. The deviations from each other and from the atomic heat of ice as directly determined, which these indirect determinations exhibit, are not to be wondered at when it is considered that all uncer- tainties in the atomic heats, from whose difference the atomic heat of solid water is deduced, are concentrated upon this difference. 98. The view already expressed and defended (compare especially § 12 and 13), that atoms and atomic groups are contained in solid compounds with the same atomic heat which they have in the free state, is opposed to the view which has also been frequently expressed and defended — that the atomic heat of an element may in certain com- pounds differ from what it is in the free state, and may be different in different com- pounds. This view, and the reasons which may possibly be urged in its favour, must here be discussed. The first statement of this view (compare § 6) simply goes to assert that the atomic heats of compounds may be calculated in accordance with the values resulting from the determinations of the specific heat, assuming that one constituent of the compound has the same atomic heat as in the free state, the other an altered one. What alteration is to be assumed depends merely on what assumption adequately satisfies the observed specific heat of the compound. The accuracy of the assumption is susceptible of no further control ; the assumption itself cannot be regarded as an explanation of the observed atomic heat of the compound. And nothing is altered in this by assuming (compare § 6 and 11) that the changes in the atomic heat of a substance on entering into chemical compounds take place in more or less simple ratios. A greater degree of probability must be granted to the view (compare § 10) that the atomic heats of the constituents of compounds, and the differences in the atomic heats of these bodies, according as they are combined or in the free state, depend upon the state of condensation in which these bodies are contained. If, for instance, from a consideration of the specific gravities or specific volumes (the quotient of the specific weights into the atomic weights) of compounds and of their constitutents, a conclusion could be drawn with some degree of certainty as to the state of condensation in which the latter are present in the former, and if definite rules could be given for the varia- tions of the atomic heats with the state of condensation, the result of such an investiga- tion, if it agreed with the observed results for the atomic heats of compounds, might be called an explanation of these observations. But what is here presupposed is partially not attained and partially not attempted. And, moreover, as far as can be judged from individual cases, the same element, when contained in different states of condensa- tion, appears to have the same atomic heat. It has been attempted to deduce the state of condensation, or the specific volume of oxygen in its compounds with heavy metals, PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLED BODIES. 189 by subtracting from the specific volume of the oxide that of the metal in it, and con- sidering the remainder as the volume of oxygen. It would follow from this that the specific volume of oxygen in suboxide of copper is much greater (about four times as great) than in oxide of tin. But if the atomic heat of oxygen be deduced by sub- tracting from the atomic heat of the oxide that of the metal in it, it is found that the atomic heat of oxygen in suboxide of copper and in oxide of tin gives almost exactly the same number. Hence it does not seem that the state of condensation in which a constituent may be contained in a compound has any material influence on the atomic heat of this constituent. 99. From all that has been said in the foregoing paragraphs the following must be adhered to. (1) Each element in the solid state, and at a sufficient distance from its melting-point, has one specific or atomic heat, which may, indeed, somewhat vary with physical conditions, different temperature, or density for instance, but not so consider- ably as to be regarded in considering in what relations the specific heat stands to the atomic weight or composition; and (2) that each element has essentially the same specific or atomic heat in compounds as it has in the free state. On the basis of these two fundamental laws it may now be investigated what atomic heats individual elements have in the solid free state and in compounds. Indirect deductions of the atomic heats of such elements as could not be investigated in the solid free state are from these propositions admissible : that from the atomic heat of a compound containing such an element the atomic heat of everything else in the compound is subtracted, and the remainder considered as the expression for the atomic heat of that element. Such in- direct determinations of the atomic heat of elements may be uncertain, partly because the atomic heat of the compounds is frequently not known with certainty, as is seen from the circumstance that analogous compounds, for which there is every reason to expect the same atomic heat, are found by experiment to have atomic heats not at all agreeing ; but more especially because the entire relative uncertainty in the atomic heats for a compound, and for that which is to be subtracted from its composition, is concentrated upon a small number, the residue remaining in the deduction. But when such deductions are made, not merely for individual cases, but for different com- pounds, and for entire series of corresponding compounds, they may be considered suffici- ently trustworthy to make the speculations based upon them worthy of attention. Of course in indirectly deducing the atomic heat of an element, its simpler compounds, and those containing it in greatest quantity (measured by the number of atoms), promise the most trustworthy results. 100. For Silver , Aluminium , Arsenic , Gold, Bismuth, Bromine , Cadmium, Cobalt, Copper, Iron, Mercury , Iodine, Iridium, Potassium, Lithium, Magnesium , Manganese, Molybdenum, Sodium, Nickel, Osmium, Lead, Palladium, Platinum, Rhodium, Antimony, Selenium, Tin, Tellurium, Thallium, Tungsten, and Zinc, it may be assumed, from the de- terminations of their specific heat in the solid state (§ 82), that their atomic heats, in 190 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. accordance with Dulong and Petit’s law, are approximately equal, the average being 6‘4. I do not think that all these elements have really the same atomic heat, but think that some of them will subsequently be considered as exceptions to the above-mentioned law, as it will in the sequel be proved that several elements have an atomic heat differing from 6 ’4. But for none of the previously mentioned elements are the present data, and the presumed deviation of the atomic heat from that of other elements, sufficient to justify their being separated from them. To the elements just mentioned chlorine must be associated from the close agreement of the corresponding chlorine, bromine, and iodine compounds (§ 84), and of the compounds K Cl 03, 24*8, and K As 03, 25’3 (§ 88). To the atomic heats of these latter compounds those of individual salts KN03 approximate closely; the latter gave (§ 88) 21*8-24’4, mean 2S,0, which on the whole agrees sufficiently closely with those found for the metallic oxides, B2 03 (§ 85). I count nitrogen also among the elements whose atomic heat may be assumed at 6'4, like that of most other elements; without, however, con- sidering the determination of the atomic heat of this element as very trustworthy. To deduce the atomic heat of this element with certainty, compounds are wanting which contain, besides nitrogen, elements whose atomic heat has been directly determined. The fact that the atomic heat of the nitrates, R2 N2 ©6, was found (§ 88) in the mean to be 38T, a third of which, 12‘7, is somewhat less than the average atomic heat found for the oxides of heavy metals of the formula R 02, might be a reason for assign- ing to nitrogen a smaller atomic heat ; while, on the other hand, the atomic heats of other nitrogen compounds, in which it is true other elements enter whose atomic heat is only indirectly determined, do not favour this view. In the class of elements with the atomic heat about 6 '4, barium , calcium , and strontium may be placed from the agreement in the atomic heats of their compounds with the atomic heats of corresponding compounds of such elements as have been found by the direct determination of their specific heat in the free solid state to belong to that class (compare the atomic heats of the compounds RC12 in § 84, R©03in § 86, R S04 in § 87, and SN2G6 in § 88); further, rubidium (compare the atomic heats of the compounds B Cl in § 84, and R2 € 03 in § 86) ; then also chromium (from the agreement in the atomic heats of Cr2 03 and ¥e2 03, § 84), and titanium (from the agreement in the atomic heats of Ti 02 and Sr 02, § 84). To place zirconium in the same class has no other justification than that on this assumption the atomic heat of zircon may be calculated in accordance with that deduced from the observed specific heat of this mineral. 101. According to direct determinations of the specific heat, sulphur and phosphorus do not belong to this class. The more trustworthy determinations (for sulphur the last two, for phosphorus the last three of the numbers in § 82) assign to these elements the atomic heat 5 '4. That sulphur has a smaller atomic heat than the elements discussed in the last paragraphs follows from the atomic heats of sulphur compounds, compared PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 191 with those of the corresponding compounds of such elements as have an atomic heat = 6'4. The average atomic heat of compounds RS and RS is 11*9, according to the determinations in § 83, while those of chlorine compounds RC1 and R Cl (§ 84) =12*8, that of the corresponding bromine compounds =13*9, and of the corresponding iodine compounds =13*4. In comparing more complicated sulphur compounds, sulphates, for instance, with other compounds of analogous composition, the same is met with ; although such complicated compounds are of little value in giving data for deciding on such small differences. The specific heat of the simpler phosphorus compounds has not been investigated ; for more complicated compounds, although they point to a smaller atomic heat for P than 6-4, the above remark also applies. The determinations of the specific heat of silicium give for this element also a smaller atomic heat than 6*4 (compare § 82), and the same conclusion results from a comparison of the atomic heats of Si 02, and the oxides, R 02, of the silicates R Si 03, and the oxides R2 03. The atomic heat to be assigned to silicium cannot as yet be settled with any degree of certainty. Direct determinations, varying considerably from each other, give a specific heat mostly greater than 4; while the numbers obtained indirectly, and them- selves also not closely agreeing, are partly considerably smaller. If in the sequel I put the atomic heat of silicium at 3*8, corresponding to the lowest number found for the specific heat of this element, I do so for want of other and more certain data. I con- sider this number as quite uncertain. The atomic heat of boron , from the direct determinations of the specific heat, is con- siderably smaller than 6 *4 ; and the atomic heats of boron compounds confirm this, as was discussed in §§ 93 and 95. By comparing the atomic heats of such boron and sul- phur compounds as contain along with boron and sulphur the same elements in the same proportions, the atomic heat of boron is found to be half that of sulphur. The atomic heat of KB02=16*8 is exactly half that found for K2B04=33*6; the atomic heat of BbB204 = 26’5 is almost exactly equal to that for RbS04=25*7. Taking the atomic heat of S, in accordance with the above discussion, at 5-4, that of B would be 2 ’7; the numbers obtained directly for the atomic heat of boron (§ 82) from the expe- riments on the specific heat of this element agree with sufficient accuracy. In the sequel I take the atomic heat of B at 2-7. A smaller number is obtained in other compari- sons ; for instance, of the atomic heats of B2 03 and of the oxides R2 03, or of the salts R B 02 and the oxides R2 02 ; but in such indirect determinations of the atomic heat, where such small numbers are to be determined, as is here the case with the atomic heat of boron, the results are very uncertain, owing to the fact that the entire uncertainty in the atomic heats of the compounds, and in the assumption that the elements correspond- ing to boron in compounds of analogous composition have really the atomic heat, =6*4, is thrown on the final result. Lastly, carbon also, from the direct determinations of its specific heat (§ 82), has a much smaller atomic heat than 6 ’4. The same result follows from a comparison of the atomic heats of carbon compounds : the atomic heat of the carbonates, R2 € 03=28,4 as mdccclxv. 2 D 192 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. the mean of the determinations in § 86, is much smaller than that of R303(==3R0), which is the mean of the numbers in § 85 =33*3; the atomic heat of the carbonates RG03 =20*7, as the mean of the determinations in § 86, is much smaller than 27*1, the number found for As2 03, Bi293, Gr2 03, Fe203, and Sb203 as the atomic heat of oxides R203. I put the atomic heat of carbon at T8 for G, as deduced from the deter- mination of the specific heat of its purest variety, diamond. 102. In the preceding paragraphs I have discussed the elements which, from the determinations of their specific heat in the solid free state, have a smaller atomic heat than about 6-4. There remain to be discussed a few elements whose atomic heats are also less than those of most other elements, but can only be deduced from those of their compounds. To this category belongs hydrogen *, even if the indirect determination of its atomic heat in the solid state is liable to the uncertainty just discussed. The atomic heat of water, H20, is (§ 85) =8*6, and smaller by 7 than that of suboxide of copper, Gu20, which was found in the mean to be 15*6 ; the atomic heat of hydrogen would thus be -|=3 '5 less than that of the elements to which copper belongs, as regards its atomic heat ; hence the former would be 6'4 — 3-5 = 2’9. The atomic heat of chloride of ammo- nium, N H4 Cl, has been found to be 2(M) (§ 84) ; the subtraction of the atomic heats for N+ Cl=6-4+6-4=12'8, leaves 7’2 as the atomic heat of 4H, and therefore T7 for that of H. The atomic heat of nitrate of ammonia, N2H4G3, is 36-4 (§ 88); subtracting therefrom as the atomic heat of N2+03, the number 27T, which has previously been fre- quently mentioned as the atomic heat of oxides R203, we haye 9 -3 as the atomic heat of 4H, that is 2‘3 for that of H. I put in the sequel the atomic heat of hydrogen at 2'3. That oxygen has a smaller atomic heat than 6*4, follows from the fact that the oxygen compounds of the metals have a considerably smaller atomic heat than the correspond- ing chlorides, iodides, or bromides. For instance, the atomic heat of the oxides -R0 is as the mean of the determinations in § 85 =11T, while that of the chlorides RC1 and RC1 (§ 84), is 12’8, that of the corresponding bromides 13‘9, and of the corresponding iodides 13’4. That of the oxides, R02, as the mean of the determinations in § 85, of . Mn02, Sn02, and Ti02 is 13*7, while that of the chlorides RC12 (§ 85) is 18*5, and of the iodides Rl2=19’4. Taking the atomic heat of the other elements, which are contained in the following compounds, at 6-4, the atomic heat of oxygen, as deduced from the atomic heat of the oxides R 0 (11T in the mean), is =4*7 ; as deduced from the oxides B2 03 (27T as the mean of the oxides of this formula previously frequently mentioned), it is =4-8; from the above oxides, R02 (13*7 in the mean), it is =3-7; it is found (compare § 88) from K As 03 (25-3) to be 4T; from Pb3 As2 08 (65-4) to be 4*2; from KC103 (24-8) to be 4-0; from KC104(26‘3) to be 3*4; from K-Mn04 (28’3) to be 3 ’9. In the sequel I take the round number 4 for the atomic heat of 0. * L. Gmelin (Handbuch der Chemie, 4 Aufl. vol. i. pp. 216 and 222) ascribed to hydrogen the same capacity for heat as that of an equivalent quantity of lead or mercury (H=l, Cu=31-7, Hg=100); Schroder (Poggend. Ann. vol. lii. p. 279) and Cannizzaro (II Nuovo Cimento, vol. vii. p. 342) ascribed to hydrogen the same atomic heat as that of most other elements (H=l, Cl=35-5, €hi=63*4, Hg=200). PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 193 Fluorine appears, lastly, to have a considerably smaller atomic heat than 6*4. The atomic heat of fluoride of calcium, Ga Fl2, has been found to be (§ 84) only 16 '4, con- siderably smaller than the corresponding chlorides, bromides, and iodides. I put the atomic heat of fluorine at 16'4~6'4=5. 103. Taking, in accordance with what has just been said, the atomic heat which an element has in a solid compound, At 6*4 for Ag, Al, As, Au, Ba, Bi, Br, Ga, Gd, Cl, Go, Gr, Gu, Be, Hg, I, Fr, K, Li, Mg, Mn, Mo, N, Na, M, Os, Bb, Pd, Ft, Bb, Bh, Sb, Be, Bn, Sr, Te, Ti, Tl, W, Zn, and Zr, At 5-4 for S and P, at 5 for FI, 4 for O, 3-8 for Si, 2*7 for B, 2-3 for H, and 1*8 for G ; and assuming that the atomic heat of a solid is given by the sum of the atomic heats of the elements in it, we obtain the atomic heats ; and dividing them by the atomic weights, we obtain the specific heats, in sufficiently close agreement with the specific heats as obtained by direct determinations of this property. In the following Table I give for all compounds for which the specific heat has been determined in a trustworthy manner, the specific heat calculated on these assumptions, compared with the numbers found experimentally. I give this calculation and this com- parison in the same order which was followed in the synopsis § 82 to 89, and I refer to the latter as regards special remarks on the determinations. To distinguish the observers, N. again stands for Neumann, B. Begnault, Kp. Kopp, Pr. Person, A. Al- luard, and Pp. Pape. Alloys. (Compare § 82.) At * Atomic Atomic Specific Specific heat. heat. heat. ° Calculated. Calculated. Observed. Bi Bn . . . . . 328 12-8 0-0390 0-0400 B. BiSn2 . . . . . 446 19-2 0-0430 0-0450 B. Bi Sn2 Sb . . . . 568 25-6 0-0451 0-0462 K. Bi Sn2, Sb Zn2 . . 698-4 38-4 0-0550 0-0566 B. PbSb . . . . . 329 12-8 0-0389 0-0388 B. PbSn . . . . . 325 12-8 0-0394 0-0407 B. PbSn2 . . . . . 443 19-2 0-0433 0-0451 B. 104. Arsenides and Sulphides. (Compar CO qo •O’ GoAs2 . . . . . 208-8 19-2 0-0919 0-0920 N. Ag2B . . . . . 248 18-2 0-0734 0-0746 B. GoAsS . . . . 166 18-2 0-110 0-107 N. Gu2B . . . . . 158-8 18-2 0-115 0-121 B. 0-120 Kp. Fe As B . . . . 163 18-2 0-112 0-101 N. AsB . . . . . 107 11-8 0-110 0-111 N. GoB . . . . . 90-8 11-8 0-130 0-125 B. Gui. Per. B . . . . 91-7 11-8 0-129 0-129 N. 0-131 Kp. Fe B . . . . . 88 11-8 0-134 0-136 B. HgS . . . . . 232 11-8 0-0509 0-052 N. 0-0512 B. NiS . . . . . 90-8 11-8 0-130 0-128 B. 2 d 2 194 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. • Atomic Specific Specific beat. beat. beat. w eigut. Qa^cu]a|;e(j- Calculated. Observed. Pb s . . . . . 239 11-8 0-0494 0-053 N. 0-0509 R. 0-0490 Sn S ... . . 150 11-8 0-0787 0-0837 K. ZnS . . . . . 97*2 11-8 0-121 0-115 N. 0-123 R. 0-120 Fe7 S8 . . . . . 648 88-0 0-136 0-153 N. 0-160 R. As„ Bo . . . 246 29-0 0-118 0-113 N. Bi2S3 . . . . . 516 29-0 0-0562 0-060 K. Sb9S3 . . . . . 340 29-0 0-0853 0-0907 N. 0-0840 R. Fe B2 . . . . . 120 17-2 0-143 0-128-0-133 N. 0-130 R. 0-126 Mo So • . • . . 160 17-2 0-107 0-107 N. 0-123 R. Sn S2 . . . . . 182 17-2 0-0945 0-119 K. 105. Chlorides , Bromides , Iodides , and Fluorides. (Compare § 84.) Ag Cl . . . . . 143-5 12-8 0-0892 0-0911 R. Cu Cl . . . . . 98-9 12-8 0-129 0-138 K. Hg Cl . . . . . 235-5 12-8 0-0543 0-0521 K. K Cl . . . •. . 74-6 12-8 0-172 0-173 K. 0-171 Kp. Li Cl . . . . . 42-5 12-8 0-301 0-282 R. NaCl . . . . . 58-5 12-8 0-219 0-214 R. 0-213-0-219 Kp. Kb Cl . . . . . 120-9 12-8 0-106 0-112 Kp. N H4 Cl . . . . 53-5 22-0 0-411 0-373 Kp. Ba Cl2 . . . . . 208 19-2 0-0923 0-0896 R. 0-0902 Kp. Ca Cl2 . . . Ill 19-2 0-173 0-164 R. HgCl2. . . . . 271 19-2 0-0708 0-0689 R. 0-640 Kp MgCl2. . . . . 95 19-2 0-202 0-195 R. 0-191 Kp. Mn Cl2 . . . . 126 19-2 0-152 0-143 R. PbCl2 . . . . . 278 19-2 0-0691 0-0664 R. Sn CL . . . . . 189 19-2 0-102 0-102 R. Sr Cl2 . . . . . 158-6 19-2 0-121 0-120 R. ZnCl2 . . . . . 136-2 19-2 0-141 0-136 R. BaCl2+2H2G . . 244 36-4 0-149 0-171 Kp. CaCl2+6H20 . . 219 70-8 0-323 0-345 Pr. Zn K2 Cl4 . . . . 285-4 44-8 0-157 0-152 Kp. Pt K2 Cl6 . . . . 488-6 57-6 0-118 0-113 Kp. Sn K2 Cl6 . . . . 409-2 57-6 0-141 0-133 Kp. Cr2 Cl6 . . . . 317-4 51-2 0-161 0-143 Kp. Ag Br . . . . . 188 12-8 0-0681 0-0739 R. K Br . . . . . 119-1 12-8 0-107 0-113 R. Na Br . . . . . 103 12-8 0-124 0-138 R. Pb Br2 . . . . . 367 19-2 0-0523 0-0533 R. Agl . . . . . 235 12-8 0-0545 0-0616 R. Cu I ... . . 190-4 12-8 0-0672 0-0687 R. Kg I . . . . . 327 12-8 0-0391 0-0395 R. K I .... . . 166-1 12-8 0-0771 0-0819 R. Na I ... . . 150 12-8 0-0853 0-0868 R. Hgl2 . . . . . 454 19-2 0-0423 0-0420 R. Pbl2 . . . . . 461 19-2 0-0416 0-0427 R. Ca Fl2 . . . . . 78 16-4 0-210 0-208 N. 0-215 R. 0-209 A1 Na3 Fig . . 210-4 55-6 0-264 0-238 Kp. Kp Kp Kp Kp. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 195 106. Oxides. (Compare § 85.) . Atomic Atomic Specific Specific heat. heat. heat. weig t. Qajcu2ated. Calculated. Observed. Gu2 0 142-8 16-8 0-118 0-107 N. 0-111 Kp. H20 18 8-6 0-478 0-480 Pr. 0-474 E. Gu0 79-4 10-4 0-131 0-137 N. 0-142 E. 0-128 Kp. Hg0 216 10-4 0-0481 0-049 N. 0-052 E. 0-053 Kp. Mg 9 40 10-4 0-260 0-276 N. 0-244 E. MnO 71 10-4 0-146 0-157 E. IO 74-8 10-4 0-139 0-159 E. Pb0 22-8 10-4 0-0466 0-0512 E. 0-0553 Kp. ZnO 81-2 10-4 0-128 0-132 N. 0-125 E. Mg'0+H,0 . . 58 19-0 0-328 0-312 Kp. Fe304 232 35-2 0-152 0-164 N. 0-168 E. 0-156 Kp. Mg Al2 04 . . . . 142-8 35-2 0-246 0-194 Kp. Mgi Fei Gr| AL 04 . 196 35-2 0-179 0-159 Kp. Alg 03 102-8 24-8 0-241 0-197 N. 0-217 E. As203 198 24-8 0-125 0-128 E. B203 69-8 17-4 0-249 0-237 E. Bi203 468 24-8 0-0530 0-0605 E. Gr203 152-4 24-8 0-163 0-196 N. 0-180 E. 0-177 Kp. Fe203 160 24-8 0-155 0-169 N. 0-167 E. 0-154 Kp. BerTi!03 . . . 155-5 24-8 0-160 0-176 N. 0-177 Kp. Sb203 292 24-8 0-0849 0-0901 E. Mn203+H20 . . 176 33-4 0-189 0-176 Kp. Mn02. . . . . 87 14-4 0-166 0-159 Kp. Si©2 60 11-8 0-197 0-188 N. 0-191 E. 0-186 Kp. Si’. ZriO, .... 90-8 13-1 0-144 0-146 E. 0-132 Kp. fin©,’ ..... 150 14-4 0-096 0-093 N. 0-093 E. 0-089 Kp. Ti©2 82 14-4 0-176 0-172 N. 0-171 E. 0-159 Kp. Mo03 144 18-4 0-128 0-132 E. 0-154] Kp. W03 232 18-4 0-0793 0-0798 E. 0-0894] Kp. 107. Carbonates and Silicates. (Compare § 86.) K2G03 .... 138-2 26-6 0-192 0-216 E. 0-206 Kp. Na2G03 .... 106 26-6 0-251 0-273 E. 0-246 Kp. Eb2 C 03 .... 230-8 26-6 0-115 0-123 Kp. BaG03 .... 197 20-2 0-103 0-108 N. 0-110 E. GaG03 .... 100 20-2 0-202 0-203 N. 0-209 E. 0-205 Kp. 0aiMgx003 92 20-2 0-220 0-216 N. 0-218 E. 0-206 Kp. EelMnyMgyG03 112-9 20-2 0-179 0-166 Kp. Mg|Be|003 . . 91-1 20-2 0-222 0-227 N. Pb G 03 . . . . 267 20-2 0-0757 0-0814 N. 0-0791 Kp. Sr G 03 . . . . 147-6 20.2 0-137 0-145 N. 0-145 E. Ga Si 03 . . . . 116 22-2 0-191 0-178 Kp. Gai Mgi. Si 03 . . 108 22-2 0-205 0-191 N. 0-186 Kp. GuSi03+H20. . 157-4 30-8 0-195 0-182 Kp. Mgfi£eTySi04 . . 145-8 32-6 0-223 0-206 N. 0-189 Kp. A-l2 K2 Si6 016 . . 557 112-4 0-202 0-191 N. 0-183 Kp. Al2Na2Si6016 . . 524-8 112-4 0-214 0-196 N. 0-190 Kp. 196 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 108. Borates , Molybdates , Tungstates , Chromates , and Sulphates. (Compare § 87.) • Atomic Atomic Specific Specific heat. heat. heat. ° L' Calculated. Calculated. Observed. K B 02 .... 82 17-1 0-209 0-205 R. NaBG2 .... 65-9 17-1 0-260 0-257 R. Pb B2 04 .... 292-8 27-8 0-0949 0-0905 R. P-bB4G7 .... 362-6 45-2 0-124 0-114 R. K2B4G7 .... 233-8 51-6 0-221 0-220 R. Na9B4G7 . . . 201-6 51-6 0-256 0-238 R. 0-229 Kp. Na9 B4G7-f-10H9G 381-6 137-6 0-366 0-385 KP. Pb MoG4 .... 367 28-8 0-0785 0-0827 Kp. GaWG4 .... 288 28-8 0-100 0-0967 Kp. -Fes. Mns W G4 . . 303-4 28-8 0-0949 0-0978 R. 0-0930 Kp. Pb Cr G4 .... 323-2 28-8 0-0891 0-0900 Kp. K2 Gr G4 .... 194-4 35-2 0-181 0-185 R. 0-189 Kp. K2 Gr2G7 .... 294-6 53-6 0-182 0-189 R. 0-186 Kp. khsg4 .... 136-1 30-1 0-221 0-244 Kp. K38G4 .... 174-2 34-2 0-196 0-190 R. 0-196 Kp. Na9SC4 .... 142 34-2 0-241 0-231 R. 0-227 Kp. N2H8SG4 . . . 132 52-6 0-398 0-350 Kp. Ba S G4 .... 233 27-8 0-119 0-109 N. 0-113 R. 0-108 Kp. GaSG4 . . . . 136 27-8 0*204 0-197 R. 0-185 N. 0-178 Kp. Cu£G4 .... 159-4 27-8 0-174 0-184 Pp. -Mg S G4 .... 120 27-8 0-232 0-222 R. 0-225 Pp. M-n B G4 .... 151 27-8 0-184 0-182 Pp. Pb SG4 .... 303 27-8 0-0917 0-0872 R. 0-0848 N. 0-0827 Kp. SrSG4 .... 183-6 27-8 0*151 0-143 R. 0-136 N. 0-135 Kp. ZnSG4 .... 161-2 27-8 0-172 0-174 Pp- €uSG4+H2G . . 177-4 36-4 0-205 0-202 Pp- Mg£G4+H2G . . 138 36-4 0-264 0-264 Pp. Zn-SG4 + H2G . . 179-2 36-4 0-203 0-202 Pp. GaSG4 + 2H9G . 172 45-0 0-262 0-273 N. 0-259 Kp. €uSG4+2H2G . 195-4 45-0 0-230 0-212 Pp. Zn-SG4 + 2H2G . 197-2 45*0 0-228 0-224 Pp. Fe£G4+3H2G . 206 53-6 0-260 0-247 Pp. GuBG4+5H9G . 249-4 70-8 0-284 0-285 Kp. 0-316 Pp. MnSG4+5H2G . 241 70-8 0-294 0-323 Kp. 0-338 Pp. MSG4 + 6H2G . 262-8 79-4 0-302 0-313 Kp. GoSG4+7H9G . 280-8 88-0 0-313 0-343 Kp. Fe£G4 + 7H9G . 278 88-0 0-317 0-346 Kp. 0-356 Pp. MgSG4 + 7H2G . 246 88-0 0-358 0-362 Kp. 0-407 Pp. MSG4+7H2G . 280-8 88-0 0-313 0-341 Pp. ZnSG4+7 H2 G . 287-2 88-0 0-306 0-347 Kp. 0-328 Pp. Mg K2 B2 G8 + 0 H2G 402-2 113-6 0-282 0-264 Kp. m K2S2G8+6H2G 437 113-6 0-260 0-245 Kp. Zn K9 B9Go+6 H9G 443-4 113-6 0-256 0-270 Kp. -ALKoB.G, + 24 H9G 949 317-6 0-335 0-371 Kp. Gr2K2S4G16 + 24 H2G 998-6 317*6 0-318 0-324 Kp. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 197 109. Arseniates, Phosphates, Pyrophosphates and Metaphosphates, Nitrates, Chlorates , Perchlorates, and Permanganates. (Compare § 88). Atomic weight. Atomic Specific Specific heat. heat. heat. Calculated. Calculated. Observed. KAsOg .... 162*1 24-8 0-153 0-156 R. K H2 As 04 . . . 180-1 33-4 0-185 0T75 Kp. Pbo As2 Ofi . . . 899 64-0 0-0712 0-0728 R. Ag3P04 .... 419 40-6 0-0969 0-0896] Kp. kh2po4 . . . 136-1 32-4 0-238 0-208 Kp. Na2HP04+12H2G 358 139-7 0-390 0-408 Pr. Pb3P208 .... 811 62-0 0-0764 0-0798 R. K4P207 .... 330-4 64-4 0-195 0T91 R. Na4P207 .... 266 64-4 0-242 0-228 R. Pb2P907 .... 588 51-6 0-0878 0-0821 R. NaP03 .... 102 23-8 0-233 0-217 Kp. CaP206 .... 198 41-2 0-208 0T99 R. AgNOg .... 170 24-8 0-146 0T44 R. KNOg .... 101-1 24-8 0-245 0-239 R. KiNarNOg . . . 93 24-8 0-267 0-235 Pr. NaNOg . . . . 85 24-8 0-292 0-278 R. N2H4Og .... 80 34-0 0-425 0-455 Kp. Ba N2 06 .... 261 43-2 0-166 0-152 R. Pb N2 06 .... 331 43-2 0-130 0-110 Kp. -SrN206 . . . . 211-6 43-2 0-204 0-181 Kp. K Cl Og . . . . 122-6 24-8 0-202 0-210 R. BaCl206+H20 . 322 51-8 0-161 0-157 Kp. K Cl ©4 . . . . 138-6 28-8 0-208 0-190 Kp. KMn04 .... 158-1 28-8 0T82 0-179 Kp. Kp. Kp. Kp. Kp. 110. Organic Compounds. Cyanide of mercury „ zinc and potassium Ferrocyanide of po- tassium . . . Ferricyanide of po- tassium Chloride of carbon Napthaline . . Cerotic acid . . . Palmitate of melis- syle . . Cane-sugar . Mannite . . . , Succinic acid . . Tartaric acid . . Racemic acid . Formiate of baryta Oxalate of potass HgG9 N„ Fe4K4G6N6 + 3H20 . C2C16 . . :} £6h14o6 . €4H6G2 . €4H6G6 . €2H6G6+H20 G2 H9 Ba 04 . c2k;o4+h2o (Compare § 89). . . Atomic Atomic Specific Specific weight. heat. heat. heat. Calculated. Calculated. Observed. 252 22-8 0-091 0-100 Kp. 247-4 52-0 0-210 © to i—1 Kp. 329-3 74-8 0-227 0-233 Kp. 422-4 107-0 0-253 0-280 Kp. 237 42-0 0-177 0-178 Kp. 128 36-4 0-284 0-310 A. 410 108-8 0-441 | 676 302-4 0-447 J 0-429 Pr. 342 116-2 0-340 0-301 Kp. 182 67-0 0-368 0-324 Kp. 118 37-0 0-314 0*313 Kp. 150 45-0 0-300 0-288 Kp. 168 53-6 0-319 0-319 Kp. 227 30-6 0-135 0-143 Kp. 184-2 41-0 0-223 0-236 Kp. 198 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. Atomic weight. Atomic Specific heat. heat. Calculated. Calculated. Specific . heat. Observed. Quadroxalateofpot- ] ass . . . . fG*H8 K08 + 2 HO . . 254-1 69-7 0-274 0-283 Kp. ) Bitartrate of potass KOe . . . . 188-1 49-1 0-261 0-257 Kp. Seignette salt . O, h. NaK0fi + 4H9O 282-1 87-6 0-311 0-328 Kp. Bimalate of potass . C8 H10 Ga G10+8H2O. 450 152-6 0-339 0-338 Kp. 111. The preceding synopsis shows, for the great majority of substances contained in it, an adequate agreement between the observed specific heats and those calculated on such simple assumptions. In estimating the differences, the extent must be remem- bered to which various observers differ for the same substance. It must be considered that the present better determinations of the specific heat, even those made by the same experimenter, for substances where it may be expected that Neumann’s law applies, do not exactly agree with it, not more nearly than within or ^ of the value ; and that for those elements which are considered here as obeying Dulong and Petit's law, even greater deviations occur between the numbers found experimentally and those to be expected on the assumption of the universal validity of this law. (These deviations, i. e. the differences between the atomic heats found for these elements, are seen from § 82.) The extent to which the experimentally determined specific heats deviate from such a law, Neumann’s for instance, in bodies for which calculation takes it as applying, gives of course the means of judging what differences may occur between the observed and calculated numbers without invalidating the admissibility of the calculation attempted. And it is as much a matter of course that, in those bodies in which a marked deviation from Neumann’s law has been already mentioned (compare § 95), a greater difference is found in the present synopsis between calculation and observation. I consider the agreement between calculation and observation, as shown in the synopsis § 103 to 110, as in general sufficient for a first attempt of that kind. But it need scarcely be mentioned that I by no means consider the calculated as more accurate than the observed numbers, or among several numbers consider that the most accurate which is nearest the calculated ; for that, the bases of calculation are much too uncertain. The list of atomic heats given at the commencement of § 103 is scarcely much more accurate than were the first tables of atomic weights; but just as the latter have expe- rienced conlinual improvements, and thus what was at first only an approximate agree- ment between the calculated and observed composition of bodies has been brought within considerably narrower limits, and apparent exceptions been explained, so, in like manner, will this be the case for ascertaining what atomic heats are to be assigned to the elements, and how the atomic heats of compounds may be deduced therefrom. This much, however, may even now be said, that while formerly for many solid substances a statement of the specific heat could in no way be controlled, a concealed source of error for the determination of this property was not indicated, and an error which materially altered the number for this property could not be recognized, at present, even if only roughly, spell a control is possible. Compare § 77. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 199 PART VI.— CONSIDERATIONS ON THE NATURE OF THE CHEMICAL ELEMENTS. 112. The proof given in the preceding that Dulong and Petit’s law is not univer- sally valid, justifies certain conclusions, in reference to the nature of the so-called chemical elements, which may here be developed. What bodies are to be regarded as chemical elements X Does the mere fact of inde- composability determine this X or may a body be indecomposable in point of fact and yet from reasons of analogy be regarded not as an element but as a compound X The history of chemistry furnishes numerous examples of cases in which sometimes one and some- times another mode of view led to results which at present are regarded as accurate. The earths were in 1789 indecomposable in point of fact, when Lavoisier expressed the opinion that they were compounds, oxides of unknown metals. Lavoisier’s argumenta- tion was based on the fact that the earths enter as bases into salts, and that it was to be assumed in regard to all salts, that they contained an oxygen acid and an oxygen base. But the view, founded on the same basis, that common salt contains oxygen, and the subsequent view that what is now called chlorine contained a further quantity of oxygen besides the elements of an oxygen acid, did not find an equally permanent recog- nition. On the basis of the actual indecomposability of chlorine, Davy maintained from about 1810 its elementary character; and this view has become general, especially since Berzelius, after a long struggle against it, adopted it, more I think because he was outvoted than because he was convinced. Almost all chemists of the present time consider chlorine, and in conformity therewith bromine and iodine, as elementary bodies ; but the persistence is known with which Schonbein attacks this view, and adheres to the opinion that these bodies are oxygen compounds, peroxides of unknown elements. Is there anything which enables us to decide with more certainty on the elementary nature of chlorine and the analogous bodies than has hitherto been the easel No one can maintain that the bodies which chemists regard as elements are abso- lutely simple substances. The possibility must be confessed that they may be decomposed into still simpler bodies ; how far a body is to be regarded as an element is so far relative, that it depends on the development of the means of decomposition which practical che- mistry has at its disposal, and on the trustworthiness of the conclusions which theoretical chemistry can deduce. A discussion as to whether chlorine or iodine is an elementary body can only be taken in the sense whether chlorine is as simple a body as oxygen or manganese, or nitrogen ; or whether it is a compound body, as peroxide of manganese or peroxide of hydrogen for example. If Dulong and Petit’s law were universally valid, it would not merely indicate for chemical elements a relation between the atomic weight and the specific heat in the solid state, but it could be used as a test for the elementary nature of a body whose atomic weight is known. That iodine, from a direct determination of specific heat, and chlorine by an indirect determination had atomic heats agreeing with Dulong and mdccclxv. 2 E 200 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. Petit’s law, would be a proof that iodine and chlorine, if compounds at all, are not more so than other so-called elements for which this law is regarded as valid. According to Neumann’s law, compounds of analogous atomic composition have approximately the same atomic heats. In general, bodies, whose atom consists of a greater number of indecomposable atoms, or is of more complicated composition, have greater atomic heats. In these compounds, more especially those whose elements all follow Dulong and Petit’s law, magnitude of atomic heat is exactly a measure of the com- plexity or of the degree of composition (compare § 93). If Dulong and Petit’s law were valid, it could be concluded with great positiveness that the so-called elements, if they are compounds of unknown and simpler substances, are compounds of the same order. It would be a remarkable result that the act of chemical decomposition had everywhere found its limit at such bodies as those which, if compound at all, have with every difference of chemical deportment the same degree of composition. Imagine the simplest bodies, probably as yet unknown to us, the true chemical elements, forming a horizontal spreading layer, and piled above them, the simpler and then the more complicated compounds ; the universal validity of Dulong and Petit’s law would include the proof, that all elements at present assumed by chemists lay in the same layer, and that chemistry in recognizing hydrogen, oxygen, sulphur, chlorine, and the different metals as indecomposable bodies, had penetrated to the same depth in that field of inquiry, and had found at the same depth the limit to its penetration. This result I formerly propounded * when I still believed in the validity of Dulong and Petit’s law. But with the proof that this law is not universally true, the conclu- sion to which this result leads loses its justification. Starting now from the elements recognized in chemistry, we must rather admit that the magnitude of the atomic heat of a body depends not only on the number of elementary atoms contained in one atom of it, or on the complexity of the composition, but also on the atomic heat of the elementary atoms entering into its composition ; it appears now possible that a decom- posable body may have the same atomic heat as an indecomposable one. To assume in chlorine the presence of oxygen, and to consider it as analogous to per. oxide of manganese, or in general to the peroxide of a biatomic element f, is less in accordance with what is at present considered true in chemistry, than to consider it as the peroxide of a monoequivalent element, analogous to peroxide of hydrogen. It is remarkable that peroxide of hydrogen, in the solid state or in solid compounds, must have almost as great an atomic heat (for H0 2-3+4 = 6-3) as those elements which obey Dulong and Petit’s law, and especially as iodine, bromine, and chlorine, according to the direct and to the indirect determination of their atomic heat ; the same must be the case for the analogous peroxides of such still unknown elements as have an atomic heat * “ On the Difference of Matter from the Empirical point of view,” an Academical Discourse. Giessen, i860. f I will not omit to mention that equivalent weights of iodine and peroxide of manganese have almost equal capacity for heat. As regards oxidizing action, 127 of iodine corresponds to 43-5 peroxide of manganese; Regnault found the specific heat of the former =0-0541; I found that of the latter =0-159; 127 x 0-0541 =6-87; 43-5 x 0-159=6-92. PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 201 as great as that of hydrogen. As far as may be judged from its specific heat, chlorine may be such a peroxide ; but this consideration shows no necessity for assuming that it actually is so. In a great number of cases the atomic heat of compounds gives more or less accurately a measure for the degree of complexity of their composition*. And this is the case also with such compounds as are comparable in their chemical deportment to undecomposed bodies. If cyanogen or ammonium had not been decomposed, or could not be so with the means at present offered by chemistry, the greater atomic heats of their compounds, compared with those of analogous chlorine or potassium compounds (compare § 96), and of cyano- gen and ammonium as compared with chlorine and potassium, would indicate the more complex nature of those so-called compound radicals. The conclusion appears admis- sible that for the so-called elements the directly or indirectly ascertained atomic heats are a measure for the complexity of their composition. Carbon and hydrogen, for example, if not themselves simple bodies, are more so than silicium or oxygen ; and still more complex compounds are the elements which are now considered as following Dulong and Petit’s law; with the restriction, however, that for these also the atomic heats may be more accurately determined and differences proved in them which justify similar conclusions f. One might be tempted, by comparing atomic heats, to form an idea how the more complex of the present indecomposable bodies might be composed of more simple ones, just as such a comparison has been shown to be possible for chlorine ; but it is at once seen that to carry out such an attempt the atomic heats of the elements, especially those which can only be indirectly determined, are not settled with adequate certainty. It may appear surprising, or even improbable, that so-called elements which can replace each other in compounds, as, for instance, hydrogen and the metals, or which enter into compounds as isomorphous constituents, like silicium and tin, should possess unequal atomic heats and unequal complexity of composition. But this is not more surprising than that indecomposable bodies, and those which can be proved to be com- pound, as, for example, hydrogen and hyponitric acid, or potassium and ammonium, should replace one another, preserving the chemical character of the compounds, and even be contained as corresponding constituents in isomorphous compounds. I have here expressed suppositions in reference to the nature of the so-called elements which appear to me based on trustworthy conclusions from well-proved principles. It is * The differences in the atomic heats of the elements are of course most distinctly seen in their free state, but in their analogous compounds these differences are the less prominent the more complex the compounds, that is, the greater the number of atoms of the same kind and the same atomic heat which are united to those elementary atoms whose atomic heat is assumed to he unequal. The difference in the atomic heats of G and As, for instance (1*8 and 6-4), is relatively far greater than for Ga <3 G3 and K As03 (20-2 and 24-8). f It is possible, for example, that certain indecomposable bodies which only approximately obey Dulong and Petit’s law, are analogous compounds of simpler substances of essentially different atomic heat : the approximate agreement of the atomic heats of such indecomposable bodies would then depend on a similar reason to that for the atomic heats of Ga € 03 and K As 03. Compare the previous note. 202 PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. in the nature of the case that the certain basis of fact and of what can be empirically de- monstrated must be left. It must also not be forgotten that these conclusions only allow something to be supposed as to which of the present indecomposable bodies are more complex and which of simpler composition, and nothing as to the question what sim- pler substances may be contained in the more complex ones. The consideration of the atomic heats may say something as to the structure of a compound atom, but in general gives no clue as to the qualitative nature of the simpler substances used in the construc- tion of the more complex atoms. But even if these suppositions are not free from un- certainty and imperfection, they appear worthy of attention in a subject which, for science, is still so much in darkness, as is the nature of the indecomposable bodies. Fk ib. Tnms. MDCCCLXV . PteXX. fflMnfflii IBilillflllflMiiiiii — Kg. 8. Bg.7. [ 203 ] IV. On the Composition of Sea-water in the different parts of the Ocean. By Georg Forchhammer, Professor at the University, and Director of the Polytechnic Institu- tion at Copenhagen. Communicated by the President. Received July 28, — Read November 17, 1864. In the year 1843 a friend of mine, Mr. Ennis of Falmouth, sent me some bottles of sea- water from the Mediterranean, which I subjected to a chemical examination, a work which induced me to collect what other chemists had determined about the constitution of the water of the great Ocean. This labour convinced me that our knowledge of the composition of sea-water was very deficient, and that we knew very little about the differences in composition which occur in different parts of the sea. I entered into this labour more as a geologist than as a chemist, wishing principally to find facts which could serve as a basis for the explanation of those effects that have taken place at the formation of those voluminous beds which once were deposited at the bottom of the ocean. I thought that it was absolutely necessary to know with precision the composition of the water of the present ocean, in order to form an opinion about the action of that ocean from which the mountain limestone, the oolite and the chalk with its flint have been deposited, in the same way as it has been of the most material influence upon science to know the chemical actions of the present volcanos, in order to determine the causes which have acted in forming the older plutonic and many of the metamorphic rocks. Thus I determined to undertake a series of investi- gations upon the composition of the water of the ocean, and of its large inlets and bays, and ever since that time I have assiduously collected and analyzed water from the dif- ferent parts of the sea. It is evident that it was impossible to collect this material in a short time, and without the assistance of many friends of science, and I most gratefully acknowledge how much I am indebted to many distinguished officers of the Danish and British Navy, as well as to many private men, who were all willing to undertake the trouble carefully to collect samples of sea-water from different parts of the ocean, both from the surface and from different depths. I shall afterwards, when giving the parti- cular analyses, find an opportunity to mention the name of each of those to whom I am indebted for my material. While I was thus occupied for a space of about twenty years, another series of expe- riments closely allied to my work was commenced in England, and has partly been published under the able and scientific superintendence of Rear-Admiral FitzRoy. This most important series of observations regards the specific gravity of sea- water from the most different parts of the globe ; it comprehends a much more numerous series mdccclxv. 2 F 204 PROFESSOR FORCHHAMMER ON THE COMPOSITION than my observations, but I trust that it will not make my work superfluous, but that both these investigations will supplement each other. By the kindness of Admiral FitzRoy I am able to compare the instruments which are used by the British Navy with my chemical analyses, and thus to obtain a comparison between both series. I have at different times found an opportunity to publish several parts of my obser- vations, and in 1859 I collected what had been done up to that time in an academical treatise in the Danish language*. Since that time I have obtained numerous samples of sea-water, principally from places which my previous examination had not reached. In this new form, and greatly augmented by new facts, I permit myself to lay it before the illustrious scientific society of a nation to whose navigators I owe so great a part of the material for my inquiries. This part contains an enumeration of the elements which hitherto have been ascertained to exist in the water of the ocean, and an explanation of the methods used to show their presence and to determine their quantity. It con- tains a determination as complete as possible of the distribution of the saline substances at the surface of the different parts of the sea, and in the different depths at the same place. On the Elements which occur in the Water of the Ocean. The elements which occur in greatest quantity in sea-water have been long known, and chlorine, sulphuric acid, soda, magnesia, and lime have for more than a century past been considered as its essential parts. In our century iodine, bromine, potash, silica, phosphoric acid, and iron have been discovered in sea-water, and the latest inquiries, my own included, have brought the number of elements occurring in sea-water up to twenty-seven. Next to direct analyses of sea-water, the analysis of sea-weeds, and of animals living in the sea, offers us precious means of determining those elements which occur in so small a quantity in sea-water, that it hitherto has been impossible to ascertain their presence in the water by chemical tests. It is now well known that the organic beings collect substances which are necessary for their existence, and thus offer the means to the chemist of ascertaining that these Substances were present in the medium in which the organisms lived, and from which they collected their food. As to the plants of the sea, the whole fucoid tribe derive the substances of which they consist from the sur- rounding sea-water and from the air with which they are in contact, but not from the soil on the bottom of the sea, since that part of them which generally is called their root is no root at all, and is not qualified to extract food from the soil and stones to which it adheres. Even those marine plants which do not belong to the fucoid tribe, as, for instance, the Zostera marina , and which have a real root, that may extract food from the soil, will most probably extract the great quantity of mineral elements which they contain mostly from the surrounding sea-water. As to the animals that live in the sea, they derive their substance either from the sea-water itself, or from plants that are * Om Soevandets bestanddele og deras Fordeling : Hayet. af G. Forchhammek, Professor ved Kjobenhavns TJniyersitet. OF SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 205 nourished by sea-water, or from other animals that live upon sea-weeds, thus deriving their whole mineral substance either directly or indirectly from the sea. I have availed myself of the means which the organisms of the sea furnish, to determine a great number of elements that thus must exist in solution in sea-water. As to this great number of elements contained in the sea-water, we might ask one question, which is of great importance for the history of the earth, viz. how all these elements got into the sea, whether they were in the original sea, or subsequently got into the sea, where they are now slowly accumulating. When we consider that the sea constantly loses a great quantity of pure water by evaporation, and that a large part of this water falls on the land, dissolves a number of substances from it, and carries them at last into the sea, where they constantly would increase in quantity if it were not for its organisms which deprive it again of them, we may well suppose that these two effects, of which the one acts to increase, and the other to diminish the quantity of mineral substances in sea-water, are pretty equal, and leave the sea unchanged. I will, however, not dwell upon these mutual chemical decompositions and combinations, which, partly depending upon organic life, partly upon inorganic mechanical and che- mical forces, play such a great part in the changes of the earth, but I hope at some future time to find leisure to publish my investigations in this branch of the history of the earth. The elements which hitherto have been found in sea-water are, — 1. Oxygen. — Besides that oxygen which is a constituent part of water, and other compounds that occur in the sea, such as the sulphates, phosphates, carbonates, and silicates, it occurs in a free uncombined state, absorbed by the water itself. It plays a very material part in the small but constant changes which take place in the sea- water, and whose general effects are that the organic substances dissolved in it are changed into carbonic acid and water. This effect takes place principally near the surface, and decreases with increasing depth ; and water from the deeper parts of the sea is able to destroy the colour of a greater quantity of the hypermanganate of potash than that from the surface, which again shows that there is more organic matter undestroyed in the deep sea. 2. Hydrogen. — Besides the hydrogen which belongs to the composition of water, it occurs in the organic substances and in the ammonia which are dissolved in sea-water. 3. Chlorine. — Next to the elements of water chlorine is the element which occurs in greatest quantity in sea-water, and has from the earliest times been recognized as such. 4. Bromine has been long known as an essential part of the sea, easily recognized in the residue from the evaporation of sea-water after the crystallization of the greater part of the chloride of sodium. 5. Iodine. — This substance is well known to have been the first element in sea-water discovered not directly, but by the analysis of the ashes of fucoidal plants, which by organic power had collected and concentrated it from sea-water. 6. Fluorine. — Dana long ago showed that fluorine occurs in the lime of corals, where 2 f 2 206 PROFESSOR FORCHHAMMER ON THE COMPOSITION its presence may be ascertained with great facility. To prove directly its existence in sea-water, I evaporated 100 lbs. of it taken in the Sound near Copenhagen, and when it was so much condensed that the salt began to crystallize, I precipitated the whole by an excess of ammonia, washed the precipitate, and dissolved in muriatic acid. It was now again precipitated by ammonia, and the precipitate boiled with a solution of muriate of ammonia. The washed precipitate weighed now 3T04 English grains, and was divided into two parts, of which one was heated in a small platinum crucible with sulphuric acid. The vapours etched glass. The other part was distilled in a bent glass tube with sulphuric acid, and the vapour condensed in a solution of ammonia. The vapours etched the glass tube, and when the ammoniacal liquor was evaporated and the salt dissolved, silica remained. With much greater facility the fluorine was shown in the stony matter deposited at the bottom of the boilers of the Transatlantic steamers, of which I owe samples to the late Dr. G. Wilson of Edinburgh, who likewise discovered fluorine in sea-water. 7. Sulphur. — This element occurs in considerable quantity in sea-water combined with oxygen as sulphuric acid, forming salts with baryta, strontia, lime, and magnesia. In pure sea-water, or in such sea-water as only contains a very small quantity of organic matter, no decomposition of the sulphates takes place, and I have kept sea-water for many years in well-corked bottles without the least alteration. Near the shores and at the mouth of great rivers, where considerable quantities of organic matter are washed into the sea, it is easily decomposed, particularly if it is kept in bottles. This decompo- sition shows itself always by the production of sulphuretted hydrogen. Water from the polar regions is very subject to decomposition, probably on account of a greater quan- tity of organic matter than in water from lower latitudes. It is, however, very difficult to assign all the different causes which may produce decomposition of sea-water. All the water which was brought by the Swedish Spitzbergen Expedition in bottles from the polar sea was decomposed, and emitted sulphuretted hydrogen when the bottles were opened, while all the water brought from the same sea by the same Expedition in tubes of glass, hermetically closed by melting, was undecomposed. Hyperman- ganate of potash is the best test for the sulphuretted hydrogen of such water, its colour is instantaneously destroyed by the water, and sulphuric acid is formed again. The quantity of sulphuretted hydrogen formed in such water differs greatly, and depends, at least partly, upon the quantity of organic matter contained in it. Water from the Mediterranean is very subject to this kind of decomposition ; but the greatest quantity of sulphuretted hydrogen which I have met with in any sample was found in water which I owe to Admiral Washington, and which had been taken by Captain Peevost of the ‘ Satellite’, under 35° 46' S. lat. and 52° 57' W. long., off the east coast of South America, and not very far from the mouth of the Rio de la Plata ; 3000 grains of this water destroyed the colour of 455 drops of a solution of hypermanganate of potash, of which the same quantity of ordinary sea-water only bleaches four to six drops*. * This test has only a relative value in comparing different kinds of water, the quantity of oxygen required for complete oxidation being proportional to the quantity of hypermanganate destroyed. or SEA- WATER IN THE DIFFERENT PARTS OF THE OCEAN. 207 In this kind of decomposition, where sulphuretted hydrogen is formed, the organic matter is changed into carbonic acid and water, while the oxygen which this change requires is taken from the sulphates, and the sulphuret thus formed takes its oxygen again from the hypermanganate. Thus the result of the series of decompositions is the revival of the same sulphate with which it began, and the formation of carbonic acid and water from the organic matter which was present. In the second case, where the hypermanganate directly oxidizes the organic matter, the same quantity of oxygen must be used, and the same products are obtained. In both cases the oxygen is ultimately derived from the hypermanganate. This reasoning supposes that no oxygen from the atmosphere is absorbed, and no sulphuretted hydrogen has escaped during the opera- tions. The absorption of oxygen is prevented by the cork of the bottle, but when it is opened some sulphuretted hydrogen certainly will escape, and we may conclude that in the cases where sulphuretted hydrogen is formed, there has been a little more organic matter than the hypermanganate indicates. This fermentation of the sea-water occasions of course a loss of sulphuric acid, and makes the analysis in some degree inaccurate. The greatest loss of sulphuric acid which I have observed was in the case of the water from the 4 Satellite ’ above mentioned, where the proportion to chlorine was found to be 9T3: 100, while the mean proportion is 1T94: 100, thus about one-seventh of the sulphuric acid was decomposed. It is very probable that this great quantity of organic matter is owing to the water of the Eio de la Plata, because the water contained only 17*721 chlorine, while the mean number for that region is 19*376, which seems to prove a considerable admixture of river-water. I may here also mention a curious instance where no decomposition had taken place, although the circumstances seemed to be very favourable for it. The sample had been taken by the late Sir James Koss in 1841, at 77° 32' S. lat., in the neighbourhood of the great ice-barrier, and it was marked “ Sea-water containing animalculae.” It was very muddy when I opened the bottle, but had not the least smell of sulphuretted hydro- gen. Tested without being filtered, 1000 grains bleached 180 drops of the hyperman- ganate ; when filtered the same quantity bleached 39 drops. It contained thus a great quantity of organic matter. The quantity of chlorine was 15*748, which proves that it was much diluted, probably by the melted ice from the barrier ; the proportion of sulphuric acid to chlorine was 11*65 : 100, which approaches pretty near to the normal proportion. It had been about twenty years in the bottle when I analyzed it, and the cork was sound. It is difficult to conceive why this water had not suffered any decom- position. 8. Phosphorus. — This element, in combination with oxygen, is a never failing part of sea-water, which remains as phosphate of lime when the water is evaporated to dryness and the salts remaining dissolved in boiling water. The small quantity of insoluble matter which remains consists of phosphate of lime, sulphates of baryta and of strontia, fluoride of calcium, carbonate of lime, and silica. When this mixed substance is heated with muriatic acid, filtered, and tested with molybdate of ammonia, phosphoric acid will 208 PROFESSOR FORCHHAMMER ON THE COMPOSITION always be found ; or when the insoluble remainder from evaporation is heated in a glass tube with potassium, it will, when breathed upon, emit the smell of phosphuretted hydrogen. 9. Nitrogen occurs in sea-water combined with hydrogen as ammonia, and its presence may be shown by mixing sea-water with a solution of baryta, and distilling the mixture in a glass retort. In the distilled portion ammonia may be shown by adding some drops of nitrate of protoxide of mercury, which will form grey clouds, or by muriatic acid and chloride of platinum, which, when carefully evaporated, will leave the well-known yellow salt insoluble in alcohol. It can hardly be doubted that this ammonia is partly formed by the living animals of the sea, which exhale ammonia, and partly by the putrefaction of their dead bodies. We might ask why we find so small a quantity of ammonia, the causes for its formation being so general ; but it is well known that plants will absorb it, and that the circulation of nitrogen in the sea is between sea-water, plants, and ani- mals, as it is on the dry land between soil, plants, and animals. 10. Carbon occurs always in the water of the sea, partly as free carbonic acid, partly, but in very small quantities, as carbonate of lime, partly in combination with oxygen, hydrogen, and nitrogen as organic matter, derived from the destruction of the numerous organic beings that live in the sea. It is by the oxidation of these substances that the sulphates of sea-water are decomposed, and that the hypermanganate of potash is bleached when boiled with sea-water ; and it is owing to these substances that all sea- water disoxidizes the peroxide of iron either to protoxide or to sulphuret, and that all ferruginous clay or sand deposited in deep sea has a dark colour. 11. Silicium . — Silica is found in the insoluble remainder from the evaporation of sea- water when the salts are dissolved in water. It can be separated from the phosphates and fluorides by dissolving in weak muriatic acid, when it remains undissolved along with small quantities of sulphate of baryta and strontia. In this state it is easily recognized by the blowpipe. In the Sponges it is collected in great quantity ; and when the large cyathiform sponge from Singapore is calcined, it leaves a skeleton which retains the original form and size of the sponge, and consists almost entirely of silica, the large pores of it being lined with oxide of iron, which evidently has belonged to some part of the animal itself. It is found also in other animals of the sea, and it occurs in the ashes of sea-weeds of the fucoid family, though it is not yet ascertained whether it belongs to the fucus itself, or to the infusoria which usually cover its surface. 12. Boron. — I have long tried to find boracic acid in sea-water, but for a long time all my endeavours were vain. Notwithstanding I felt convinced that it must be there, since both boracic acid and borates are not very rare, and a great part of its salts with lime and magnesia are more or less soluble in water. Thus I thought that water from the land must have carried boracic acid into the sea, where it still must be accu- mulating, since we do not know any combination by which it could be separated again from the water. An additional proof of the correctness of this idea I found in the occurrence of Stassfurthite (mostly consisting of borate of magnesia), together with all OF SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 209 other salts that occur in sea-water, in the beds of rock-salt at Stassfurth in Germany. The lower part of this bed of rock-salt, which by a boring was not penetrated through at a depth of 800 feet, consists of pure chloride of sodium. Upon this rest the other salts of sea-water, consisting of magnesia, lime, and potash combined with muriatic and sulphuric acids in numerous combinations, among which we also find the Stassfurthite (borate of magnesia with chloride of magnesium). Boracite, a similar combination of boracic acid, occurs at Luneburg and at Segeberg, associated with gypsum and chloride of sodium, which latter at Luneburg forms a spring of saturated brine, and at Segeberg occurs in separate crystals imbedded in the gypsum. I thought I might be able to form a borate insoluble in water, and with such charac- teristic properties that it might be possible to determine the boracic acid in it. It is well known that Heintz, by melting chloride of magnesium, chloride of sodium, mag- nesia, and boracic acid, obtained octohedral crystals, which were boracite, and another set of crystals, of hemiprismatic form, which also contained boracic acid and magnesia. The crystals were microscopic, but could easily be recognized by their different form of crystallization. To make myself acquainted with these different artificial combinations, I melted borax, common salt, and sulphate of magnesia in a crucible, allowed it to cool slowly, and dissolved it in water. There remained a heavy crystalline powder, which under the microscope proved to consist of six-sided hemiprismatic prisms, containing both magnesia and boracic acid. I could not discover any octohedral crystal, and no boracite seemed to have been formed. In another experiment I fused common salt, magnesia, and borax; after solution I obtained the same hemiprismatic crystals, but no octohedrons ; and felt now convinced that I hardly should obtain boracite by fusing salt of sea-water, but that I might obtain the hemiprismatic borate if sea-water con- tained boracic acid. The experiment was made in the following way : — I evaporated 6 lbs. of sea-water taken from the Sound near Copenhagen, transferred the salt into a perfectly clean platinum crucible, which was placed upon magnesia in a common Hessian crucible, exposed it to a white heat, and cooled slowly. After solution of the salt, the powder remaining was placed under the microscope, where it was found to consist almost entirely of hemiprismatic crystals which frequently formed twins* and by their whole exterior showed themselves to be essentially different from the hemiprismatic borate. Many of them were corroded at the sides and ends, as if they had partly been dissolved. I supposed them to be gypsum, which of course must be formed by the evaporation of sea-water ; and although the gypsum by melting would be changed into anhydrite, they afterwards, during washing with water, would again form a hydrate. I thought even several times to have seen square prisms (anhydrite'?) change into the hemiprismatic form under my observation in the microscope, and get oblique cracks like one cleavage of gypsum. The powder was again washed with hot water, and the solution was found to contain both sulphuric acid and lime. When the wash-water contained only traces of sulphuric acid, the powder, greatly diminished in quantity, was again 210 PROFESSOR FORCHHAMMER ON THE COMPOSITION observed under the microscope, and showed very few half-dissolved prisms of gypsum, but numerous very small octohedrons, which had been hidden by the gypsum. Besides these octohedrons, some hemiprismatic crystals were found, precisely similar to those which I formerly had obtained when forming a borate of magnesia. The powder con- tained, further, some prisms which were striated parallel to the axis, and had a face per- pendicular to this axis ; they resembled precisely the crystals which I several years ago described as artificial apatite, and which were obtained by fusing calcined bones with chloride of sodium ; and they were in fact apatite, formed of the phosphoric acid, fluorine, chlorine, and lime of the sea-water. Of the powder in question, which essen- tially consisted of octohedrons, I dissolved 7T84 grains in nitric acid, which left 0T60 grain of a reddish powder consisting mostly of oxide of iron, but showing also under the microscope hemiprismatic crystals like the borate of magnesia. The nitric solution gave with ammonia a precipitate which weighed 0*633, and contained phosphoric acid. At last the remaining solution gave with phosphate of soda and an excess of ammonia 16’667 ignited phosphate of magnesia=6‘074 pure magnesia. The sum of all these substances thus determined was 6‘867, so that only a quantity amounting to 0‘317 grain which was wanting could be boracic acid. It was thus clear that the octohedrons analyzed could not be boracite, and there could hardly be any doubt but that the substance was essentially pure magnesia, mixed with small quantities of oxide of iron, phosphate of lime, and other substances which were still to be determined. Pure magnesia occurs among the Vesuvian minerals crystallized in regular octohedrons, and has obtained the name of Periclase. In this case the periclase was formed by the decomposition of the hydrate of chloride of magnesium contained in the salt of sea-water, and decomposed in the melting heat. As a further proof of its nature as pure magnesia, it may be mentioned that, when boiled with a solution of sal- ammoniac, it was dissolved with a strong smell of ammonia. The solution contained magnesia, and nothing else besides salts of ammonia could be discovered. When the octohedral crystals were removed by boiling with a solution of sal-ammo- niac, the remaining powder contained only hemiprismatic prisms of the supposed borate of magnesia, crystals of apatite, and very acute six-sided pyramids, which in their form had some similarity to crystals of sapphire, and a considerable quantity of amorphous red oxide of iron, probably mixed with silica. A portion of this powder was moistened with sulphuric acid, and during twenty-four hours left to spontaneous evaporation. I could now observe crystals of sulphate of magnesia and needles of sulphate of lime. The substance, nearly dry, was mixed with diluted alcohol, which, when inflamed, showed the green margin of the flame characteristic of boracic acid, and gave a brown colour to curcuma paper, although the solution was acid. It is thus proved that this salt con- tained boracic acid, which in this case could only be derived from sea-water. When this powder was boiled with muriatic acid, apatite, borate of magnesia, and silicate of peroxide of iron were dissolved, and a very small quantity of the six-sided pyramids remained, which resisted the action of acids, but were made soluble by fusing with OF SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 211 carbonate of soda. When the soda was washed away, the remaining substance dissolved in muriatic acid, and it could now be proved that alumina was present. The quantity of these six-sided pyramids obtained from 6 lbs. of sea-water was, however, so small, that no experiments could be made to ascertain whether it contained other substances besides alumina. I have been somewhat more explicit in relating my experiments to ascertain the exist- ence of boracic acid and alumina in sea-water, partly because I found it very difficult to find unequivocal proofs of their presence, and partly because it interested me highly to find how useful the microscope may be in inorganic analysis, when used in combination with chemical tests. When I had convinced myself that boracic acid occurred in sea-water, it appeared to me in the highest degree probable that the organisms of the sea would collect it, and that it might be found in their ashes. I was so fortunate as to begin my experiments with a plant that contained it in a rather large quantity, viz. the Zoster a marina. The plant was collected in the month of December, at the sea-shore near Copenhagen, dried, and burnt. The ashes were washed with water, and the solution, which contained mostly chloride of potassium and sulphate of potash, contained also a small quantity of boracic acid, probably combined with soda. The insoluble part of the ashes was moistened with sulphuric acid until it had a sour taste, evaporated in a moderate heat to dryness, and washed with water. When this solution was mixed with strong alcohol and filtered, it burned with a green flame, and gave to curcuma paper a brown, and to litmus paper a red colour. To separate the boracic acid from the other substances I chose super- heated steam, a method to which I was led by a consideration of the way in which boracic acid reaches the lagoons of Tuscany. It is well known that this acid comes with steam from the interior of the earth, and is condensed when escaping from the fumaroles. An experiment in which I mixed dry borax with sulphuric acid, and exposed it to the action of superheated steam at 300° to 400° Centigrade, volatilized not only boracic acid in form of a solution, but gave even the well-known scales of its hydrate. The experiment with the distillation of the ashes of Zostera marina with sulphuric acid and superheated steam succeeded completely. The water contained boracic acid, which by a slow evaporation was obtained in crystalline scales ; and another portion of it was converted into borax, which was obtained in its regular form. Even Fucus vesiculosus contains the same acid, but in a much smaller quantity. 13. Silver. — Malaguti first showed that silver occurs in the organisms of the sea; I have subsequently proved it to exist in a coral, a Pocillojoora, and several chemists have since tried to prove that silver is precipitated by the galvanic current between the copper coating of a vessel and sea-water. If the last determination is confirmed, the existence of silver in sea-water is proved by direct experiment. From the Pocillojpora alcicornis I have separated it in the following manner : — I dissolved the coral in muriatic acid, precipitated the solution by hydrosulphate of ammonia, and dissolved the preci- pitate, which consisted of sulphurets, of phosphate of lime, and fluoride of calcium, in mdccclxv. 2 G 212 PROFESSOR FORCHHAMMER ON THE COMPOSITION very weak cold muriatic acid, which left the sulphurets of silver, lead, and copper pro- bably mixed with those of cobalt and nickel. These sulphurets were separated from the solution, evaporated to dryness with a little nitric acid, to which were added a few drops of muriatic acid, and dissolved in water, which leaves sulphate of lead and chlo- ride of silver undissolved. When the filter which contained the latter substances is burnt, the silver is reduced to metal ; a solution of pure soda will dissolve the sulphate of lead and leave the silver, which, when dissolved in nitric acid, can be tested with muriatic acid. I obtained from Pocillopora alcicornis about 3,000,000? or from a solid cubic foot of the coral about half a grain of silver. 14. Copper has not been discovered in sea- water itself, but occurs so frequently in the lime-salts of the animals of the sea, and in the ashes of the sea- weeds, that it can be discovered with great facility by its well-known tests. In the Pocillopora I found about six times more copper than silver, in the coral Heteropora abrotanoides about 350*000 copper, and in the yellowish-green substance which remained after the filtration of the muddy sea-water which Sir James Ross had taken in 77° 33' S. lat., it could be shown with great facility. Also the ash of Fucus vesiculosus contained copper. 15. Lead occurs, like copper, in the shells of the animals of the sea and in the ashes of sea-weeds, but in greater quantity. In the Pocillopora alcicornis there was found about eight times as much lead as silver, and in Heteropora abrotanoides about 50q00 of the coral. It occurs likewise in Fucus vesiculosus. 16. Zinc. — It has not been shown directly in sea- water, nor could I find it in the lime-salts of shells and corals, but it occurs in considerable quantities in the ashes of sea- weeds; 400 grains of the ashes of Zostera marina contained 0T39 oxide of zinc = 3-^00. It occurs also in the ashes of Fucus vesiculosus. 1 7. Cobalt. — I have discovered this metal in the ashes of Zostera marina , and in the fossil sponges of the chalk, but not in the large cyathiform sponge of the present sea from Singapore. 18. NicJcel. — We have no such delicate test for nickel as the blowpipe is for cobalt, but I have several times observed the well-known brown colour of the solution on pre- cipitating the sulphurets of the ashes of sea-weed by hydrosulphate of ammonia, and I think we are fairly entitled to suppose that these two metals occur together in sea-water as they occur in company in the mineral kingdom. 19. Iron can be discovered directly in sea-water by evaporating it to dryness and dissolving the salts again in water, when it remains insoluble and combined with silica. It remains mixed with all the other combinations that are insoluble or difficultly soluble in water, but in the solution of these residues in muriatic acid can easily be indicated by the common prussiate of potash. It occurs in great quantity in the ashes of sea-weeds and the lime-salts of sea animals. 20. Manganese can be determined directly in sea-water, accompanying the oxide of iron separated from a rather large quantity of sea-water, by the application of the well-known test for manganese before the blowpipe with carbonate of soda and nitrate OF SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 213 of soda or potash. In some sea-weeds it occurs in considerable quantity, particularly in the ashes of Zostera marina when it is in full growth. This ash contains about 4 per cent, of it, enough, when muriatic acid is poured upon the ash, to cause an effer- vescence of chlorine. Manganese is found in a much smaller quantity in the animals of the sea. 21. Aluminium. — I have often tried to find alumina in sea-water which had been filtered, but always without result, until at last, in my experiments to find boracic acid, I found alumina also, as is mentioned under boron. Aluminium must thus be enume- rated as one of the elements that occur in the water of the sea. It occurs in greater quantity than most metals, iron, and perhaps manganese, excepted. 22. Magnesium. — This element occurs, as is well known, in large quantity in sea- water, in about the same quantity as sulphuric acid, and only sodium and chlorine are found in greater quantity. Sea-weeds contain it likewise in considerable quantity, and it is a constant companion of the carbonate of lime which the shell-fishes and corals deposit. In Serjgula jiligrana it amounts to 13-49 per cent, carbonate of magnesia. Its average quantity is, however, only 1 per cent. 23. Calcium. — Lime occurs in sea-water in a small quantity combined with carbonic acid, and dissolved in an excess of it ; in a greater quantity combined with phosphoric acid, and as fluoride of calcium ; but the greatest quantity is combined with sulphuric acid. Among all the bases which river-water carries into the sea, lime is the most fre- quent ; and it is only owing to the organic beings of the sea, and principally to its lower animals, that so small a quantity remains, lime being constantly separated by the organo- chemical action of these animals. 24. Strontium. — I have discovered this element in the sea-water, and also in the deposit of the boilers of the Transatlantic steamers. It occurs likewise in the ashes of the fucoid plants, and specially in the Fucus vesiculosus. I shall here explain how I have convinced myself that this plant contains both strontia and baryta. When the ash was successively extracted, first with water, and then with muriatic acid, a rather considerable quantity of insoluble substances remained, which was fused with carbonate of soda, and again extracted by water containing some pure soda to dissolve the silica, while the sulphuric acid from the sulphate of strontia and baryta had combined with the soda of the carbonate. To remove the lime from the remainder, I dissolved it in muriatic acid which contained a little sulphuric acid. What remained undissolved was again fused with carbonate of soda and extracted with water. The remaining car- bonates were now dissolved in muriatic acid, and afterwards precipitated by a solution of sulphate of lime. The mixed sulphates of strontia and baryta were separated by flaosilicic acid, and the salt of strontia dissolved in alcohol, which then burned with the beautiful red colour of strontia. 25. Baryta occurs both hi sea-weeds and in sea-animals, but the ashes of sea-weeds contain more of it than the corals and shells. It can even be determined directly in sea- water, and in the deposits of the boilers of the Transatlantic steamers. 2 g 2 214 PROFESSOR FORCHHAMMER ON THE COMPOSITION 26. Sodium. — It is well known that sodium in combination with chlorine forms the most important salt in sea-water; next to chlorine, oxygen, and hydrogen, sodium is the most abundant element in sea-water. 27. Potassium is the alkaline element which, next to sodium, occurs most frequently in sea-water, and it may easily be shown in the sea-water itself. On the Quantitative Analysis of Sea-water. It is evident that an analysis which should determine the quantity of every one of the substances now enumerated would be a very laborious task, and that the number of analyses required to ascertain the composition of sea- water in different parts of the ocean would be a work exceeding the power of a single observer. Besides this there is another difficulty, which makes a series of such analyses quite impossible ; 100 lbs. of sea-water would be the least quantity that could be used, but such a quantity could but with difficulty be procured, and could not be kept unaltered by evaporation and fermentation. Fortunately such analyses are not required, and of the numerous elements discovered in sea-water, only a few occur in such a quantity that their quantitative determination can be of any consequence. It is besides a result of my analyses of sea-water, that the differences which occur in water from different parts of the ocean essentially regard the proportion between all salts and water, the strength of sea-water, or, to use another expression, its salinity , and not the proportion of the different elements of the salts invicem ; in other words, the difference in the proportion between chlorine and water may be very variable, but the proportion between chlorine and sulphuric acid, or lime or magnesia will be found almost invariable. The sub- stances which, in respect of quantity, play the principal part in the constitution of sea- water, are chlorine, sulphuric acid, soda, potash, lime, and magnesia ; those which occur in less, but still determinable quantity are silica, phosphoric acid, carbonic acid, and oxide of iron. All the numerous other elements occur in so small a proportion, that they have no influence whatever on the analytical determination of the salinity of sea- water, though, on account of the immense quantity of sea-water, they are by no means indifferent, when we consider the chemical changes of the surface of the earth which the ocean has occasioned, or is still producing. In my complete quantitative analyses I have always determined the quantity of chlo- rine, sulphuric acid, magnesia, lime, and potash. The sodium or soda is calculated under the supposition that there were no other metalloids or acids than chlorine or sulphuric acid, and no other bases or oxides of metals than lime, magnesia, potash, and soda ; it was supposed, besides, that the sea-water was neutral. These suppositions are not quite correct : of metalloids we find, besides chlorine, bromine, iodine, and fluorine ; of acids we find, besides sulphuric acid, also carbonic, boracic, silicic, and phosphoric acids ; and of bases we find, besides those that have been enumerated, a great number ; but all these substances occur in very small quantities, and may be neglected. I have, however, in most cases determined the quantity of insoluble remainder left when sea- Or SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 215 water is evaporated to dryness, dissolved in water, and washed until all sulphate of lime is removed. This remainder contains silica, phosphate of lime, carbonate of lime, sulphate of baryta and strontia, oxide of iron, and probably borate of magnesia or lime, and is in my memorandum of the analysis mentioned under one head, with the designation Silica, &c. In those cases where this small remainder was not deter- mined, it was calculated proportionally to the quantity of chlorine. Thus, for instance, water taken in 44° 33' N. lat. and 42° 54' W. long, contained, in 1000 parts, chlorine 18-842, and silica , &c. 0-069. In water taken in 47° 50' N. lat. and 33° 50' W. long., the quantity of chlorine was found to be IT 740, and silica is, according to the former proportion, calculated as 0-072. In this case the silica, &c. was yyj of the quantity of the chlorine, and in general it is less than yyy ; thus the possible error is utterly un- important. I rejected a method often used, which consists in evaporating sea- water to dryness, because it is inaccurate, and the result depends partly upon trifling circumstances. If evaporated by steam of 100° C. there will remain a very notable quantity of water, which quantity can only be ascertained with great difficulty. If it is dried at a higher temperature, muriatic acid from the chloride of magnesium will be driven out together with the water. I preferred thus, as I have already mentioned, to determine the quan- tity of the five above-named substances, to ascertain under one head all the small quan- tities of the different substances that remain insoluble in water, such as silica, phosphate of lime, &c., and to calculate the soda. At first I tried to separate the quantity of all the different substances in one portion of sea-water, but soon found that this method was neither so exact nor so easy as that which I shall now explain. 1. Of one portion of 1000 grains, I separated the chlorine by nitrate of oxide of silver after I had poured a few drops of nitric acid into the water. In those cases where the water had fermented, I allowed it to stand in an open glass jar, in a warm place, until all smell of sulphuretted hydrogen had disappeared. To try how exact a result this method could give, I took a larger portion of sea-water, and weighed three different portions, each of 3000 grains, and precipitated the chlorine. The result was — Chloride of silver. 145-451 145-544 145-642 Mean . . 145-541 The greatest difference is — 0-090 = 0-022 chlorine. -{-0-083=0-020 chlorine. These small differences are probably due to the small irregularities occasioned by the evaporation of very small quantities of water during weighing. The dried chloride of silver was as much as possible removed from the filter, melted in a porcelain crucible, 216 PEOEESSOE EOECHHAMMEE ON THE COMPOSITION weighed, and calculated as pure chloride of silver. The filter was burnt in a platinum crucible, by which the small quantity of chloride of silver was reduced to metallic silver, from which the chlorine which had been combined with it was calculated. This suppo- sition is correct if the quantity of chloride of silver adhering to the filter is very small. 2. The determination of the sulphuric acid was likewise made with 1000 grains of sea-water, which, after addition of some few drops of nitric acid, was precipitated with nitrate of baryta. To try the exactness of the method three portions of sea-water were weighed, each of 3000 grains. The result was — Sulphate of baryta. 12-417 12-316 12-250 Mean . . . 12-328 The greatest difference was — 0-078=0-027 sulphuric acid. q-0-089 = 0-030 sulphuric acid. 3. To determine lime and magnesia 2000 grains (in the latter experiments only 1000 grains) were weighed, and mixed with so much of a solution of sal-ammoniac that pure ammonia did not produce any precipitate, then ammonia was added until the liquid had a strong smell thereof. It was now precipitated with a solution of the com- mon phosphate of soda and ammonia, and filtered when the precipitate had collected into a granular powder. The precipitate thus obtained consists of tribasic phosphate of lime, and tribasic phosphate of magnesia and ammonia, which was washed with a weak solution of ammonia. All the filtered solution and the wash-water was evapo- rated in a steam-bath to dryness, and afterwards digested in a tolerably strong solution of pure ammonia, by which means there is further obtained a small quantity of the phosphates. The dry phosphates of lime and magnesia are heated, and if they are not completely white, they are moistened with a few drops of nitric acid, and again heated and afterwards weighed. The mass was now dissolved in muriatic acid mixed with alcohol until the whole contained 60 per cent, (volume) thereof, mixed with a few drops of sulphuric acid, and allowed to stand for twelve hours, when the sulphate of lime is collected on a filter, heated and weighed. It contains, besides the sulphate of lime, silica, oxide of iron, phosphate of alumina, and sulphate of baryta and strontia, from which substances the sulphate of lime is separated by boiling it with a solution containing 10 per cent, of chloride of sodium, which dissolves the sulphate of lime and leaves the other combinations undissolved. The remainder is washed, heated, and its weight deducted from that of the sulphate of lime. To try how exact the determination of the lime was, I have taken three times 3000 grains of the same water, separated the lime, and obtained the following results : — OF SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 217 Sulphate of lime. 2-761 2-753 2- 684 Mean . . . 2-733 The greatest differences are — -0-049 = 0-020 lime. + 0-028=0-012 lime. To find the quantity of magnesia contained in the weighed mixture of the phosphates of magnesia and lime, the lime, whose quantity has been determined, must, by calcu- lation, be converted into tribasic phosphate of lime, and deducted from the whole quantity of phosphates ; the other small quantities of different salts, which had been precipitated with the sulphate of lime, must likewise be deducted ; the remainder is bibasic phosphate of magnesia, from which the pure magnesia is calculated. The sea- water tried in this way gave, after deduction of lime, silica, &c., the following result: — Pure magnesia. 3- 913 3-970 3-942 Mean . . . 3-942 The differences from the mean are — -0-029 + 0-028 4. The determination of potash or potassium -in sea-water was tried by different me- thods, but gave no satisfactory results, so that I must consider the quantity of potash in the analyses as far less exact than any of the other substances whose quantity has been determined in sea-water. Happily there is so small a quantity of potash in sea-water, that any error in the determination of that substance has only an insensible influence on the whole result. For a number of the analyses I have used the following method. The weighed sea-water was evaporated to dryness, the dry mass again dissolved in water, and the undissolved residue washed with warm water until all sulphate of lime is dis- i solved, and the wash-water does not contain any sulphuric acid. The remaining powder consists of the different after-named salts and oxides insoluble in water ; it is generally weighed and noted under one head. To this solution I add so much carbonate of lime that the sulphuric acid finds lime enough to combine with, and as much muriatic acid as would dissolve the lime of the carbonate. The quantity of carbonate of lime is determined in the following way. The equivalent of sulphate of baryta being 1456, and that of carbonate of lime being- 625, there will be an excess of lime if I take carbonate of lime in such a quantity that 218 PROFESSOR FORC1IHAMMER OjST THE COMPOSITION its weight is one-half of the quantity of sulphate of baryta, obtained from an equal quantity of the same sea-water in a previous experiment for the determination of sul- phuric acid. All is now evaporated to dryness and dissolved in alcohol of 60 per cent., which leaves the sulphate of lime and dissolves all the chlorides ; so that the solution is quite free from sulphuric acid. It is now a third time evaporated with a sufficient quantity of chloride of platinum. Alcohol of 60 per cent, leaves the chloride of plati- num and potassium, which might be weighed, and the quantity of chloride of potassium calculated from it ; but as it is most difficult in a laboratory where there is constantly work going on to avoid the absorption of the vapours of ammonia by evaporating liquors, I prefer heating the double chloride to a dull red heat, and assisting the decomposition of the chloride of platinum by throwing small pieces of carbonate of ammonia in the crucible. When all the chloride of platinum is decomposed, the crucible is weighed, the chloride of potassium is extracted by alcohol of 60 per cent., and the remainder weighed again. This method has the advantage, that even if a small quan- tity of gypsum should have accompanied the double chloride, it will have no influence upon the determination of the chloride of potassium. When I do not want to determine the insoluble remainder, I evaporate the sea-water with a sufficient quantity of chloride of calcium, and thus leave out one evaporation and solution. In the few cases where I have tried to determine the different substances which in this chapter I have called silica, &c., I have used the following method. The filter upon which the remainder is collected and washed is burnt in a platinum crucible, evaporated with some drops of muriatic acid, and dissolved in water. What remains is silica, often coloured by a little oxide of iron, and mixed with a small quantity of sulphates of baryta and strontia. It is evaporated with fluoric acid and a drop of sulphuric acid to get rid of the silica. What remains after evaporation and heating is sulphate of baryta, of strontia, and oxide of iron. The solution in muriatic acid is precipitated by ammonia, and the precipitate is noted as phosphate of lime, but con- tains besides a little fluoride of calcium. The remaining liquid contains a little lime, which I precipitate with oxalate of ammonia, and suppose to have been in the sea-water as carbonate of lime dissolved by carbonic acid. In the water of the great ocean there occurs only a very small quantity of carbonate of lime, but near the shores, in the bays and inlets, and principally in the mouth of the great rivers, its quantity increases with the quantity of fresh water from the land. If the sulphates of the sea-water are decomposed to sulphurets, there is always precipitated a larger quantity of carbonate of lime, but that is the result of the decomposition, and its carbonic acid is owing to the organic substances which are oxidized by the oxygen of the sulphates. I have never tried to ascertain the nature and quantity of the gases which occur in sea-water, because the collection of sea-water for that purpose would require quite different precautions from those which were necessary for the water intended for the analysis of its solid contents. It might seem that the relative quantity of salt might be inexact, because water might OF SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 219 have evaporated through the cork during the long time which often elapsed between the time when it was taken up from the sea, and the time when it was analyzed. It is, however, easy to see whether the quantity of water in the bottle has diminished, or whether the cork has been corroded ; in both cases the sample has been rejected, but I must remark that these cases have been rare. In the last three or four years all the samples which have been taken according to my direction have been marked on the neck of the bottle with a file, on that place to which the water reached when the bottle was filled. As to the calculation of the combinations of the different substances that have been found by the analysis, I have chosen the following method : — The whole quantity of lime was supposed to be united with sulphuric acid. What remained of sulphuric acid after the saturation of lime, was supposed to be combined with magnesia. What remained of magnesia after the saturation of sulphuric acid, was supposed as magnesium to enter into combination with chlorine, and form chloride of magnesium. The potash was supposed to form chloride of potassium. That portion of chlorine which was not combined with magnesium or potassium, was supposed to form a neutral combination with sodium. Lastly, that small quantity of different substances, “ silica, &c.,” was added, and the sum of all these combinations thus calculated forms the number which in the Tables is called “All Salts.” It is hardly necessary to remark, that it is quite indifferent how we suppose the acids and bases to be combined in sea-water, the sum must always be the same, provided the salts are neutral, and all the acids (chlorine included) are determined, as well as all the bases, with the exception of soda. On the Distribution of the Salts in the different parts of the Sea . The next question to be considered refers to the proportion between all the salts together and the water ; or to express it in one word, I may allow myself to call it the salinity of the sea-water, and in connexion with this salinity or strength, the proportion of the different solid constituent parts among themselves. On comparing the older chemical analyses of sea-water, we should be led to suppose that the water in the different seas had, besides its salinity, its own peculiar character expressed by the different proportions of its most prevalent acids and bases, but the following researches will show that this difference is very trifling in the ocean, and has a more decided character only near the shores, in the bays of the sea, and at the mouth of great rivers, wherever the influence of the land is prevailing. In the Tables which are annexed to this paper I have always calculated the single substances and the whole quantity of salt for 1000 parts of sea- water, but besides this I have calculated the proportion between the different substances determined, referred to chlorine =100, and of all the salts likewise referred to chlorine. This last number is found if we divide the sum of all the salts found in 1000 parts of any sea-water by the quantity of chlorine found in it, and I call it the coefficient of that sample of sea- mdccclxv. 2 H 220 PEOFESSOE FOECHHAMMEE ON THE COMPOSITION water. The following remarks, and the Tables which belong to them, will show that there is a very small difference in the coefficient of the different parts of the ocean, but that the differences become striking in the neighbourhood of the shores. A. On the salinity of the surface of the different 'parts of the ocean and its inlets. In the Tables annexed to this paper I have divided the sea into seventeen regions. My reason for doing so was that by this method I was able to avoid the prevailing influence which those parts of the ocean which are best known, and from which I have most observations, would exert upon the calculations of the mean number for the whole ocean. First Region. The Atlantic Ocean between the Equator and 30° N. lat. — The mean of fourteen complete analyses is 36T69 per 1000 salt; the maximum is 37*908 per 1000, the minimum 34*283. The maximum lies in 24° 13' N. lat. and 23° 11' W. long., about 5° W. from the coast of Africa, where no rivers of any size carry water from the land, and where the influence of the dry and hot winds of the Sahara is prevailing. The maximum for the region is also the maximum of surface-water for the whole Atlantic ; it is equal to the mean salinity of the Mediterranean, and only the maximum of that sea off the Libyan desert and that of the Red Sea are higher. The minimum is from 4° 10' S. lat. and 5° 36' W. long, close to the coast of Africa, where the large masses of fresh water which the great rivers of that region pour into the ocean exercise their influence. Its coefficient is 1*810. Second Region. The Atlantic Ocean between 30° N. lad. and a line from the north point of Scotland to the north point of Newfoundland. — The mean of twenty-four complete analyses is 35*946 salt, the maximum 36*927, and the minimum 33*854. The maximum is in 38° 18' N. lat. and 43° 14' W. long, in the middle of the Atlantic; the minimum occurs in 43° 26' N. lat. and 44° 19' W. long., and is evidently owing to the enormous quantity of fresh water which the St. Lawrence, through its southern mouth, pours into the Atlantic. This region is under the influence of the Gulf-stream, and the corre- sponding South Atlantic region has only a mean salinity of 35*038. Its coefficient is 1*812. Third Region. The northern part of the Atlantic , between the northern boundary of the second region , and a line from the south-west cape of Iceland to Sandwich Bay in Labrador. — The mean salinity deduced from twelve complete analyses is 35*391, its maximum 36*480, its minimum 34*831. The maximum falls in 55° 45' N. lat. and 20° 30' W. long., just on the boundary of Region 2, the minimum in 60° 25' N. lat. and 3° 15' W. long., near the large northerly opening of the North Sea. This region owes evidently its high salinity to the large northern direct branch of the Gulf-stream. Its coefficient is 1*808. Fourth Region. This region comprehends the East Greenland current , which flows along the east coast of Greenland towards the south and west , turns towards the north , when it reaches the south promontory of Greenland , runs along the west coast of that large land into Davis Straits , where it disappears in the polar current from Baffin's Bay. OF SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 221 — I owe most of the samples from this current to Colonel Schaffner, who took them on his expedition to Iceland and Greenland connected with the Northern Transatlantic Tele- graph. The quantities being too small to allow a complete analysis, I have only deter- mined the quantities of chlorine and sulphuric acid. I have, however, analyzed three other samples of water from this current taken by Captain Gram, who during many years commanded one of the Danish Government’s Greenland ships ; and from these three complete analyses I have deduced the coefficient 1-813, instead of 1-812, which is the mean coefficient of the whole ocean. Thus I have calculated the mean salinity of the East Greenland current to be 35-278*, while it is in the third region 35-391, and in the sea between Norway and Spitzbergen 35-347. These observations about the salinity of the current, connected with some other observations which will be afterwards discussed, make it highly probable that the East Greenland current is the returning Gulf-stream. At all events it is no polar current, which will easily be seen in comparing it with the Baffin’s Bay current with a salinity 33-281, or the water to the north of Spitzbergen with 33-623, or the Patagonian polar current, which runs along the west coast of South America, and has 33-966. Nor is it probable that it comes from the north shores of Siberia, where such a great number of powerful rivers bring a vast quantity of fresh water into the sea. Its salinity is so great that it even exceeds that of the South Atlantic Region, between 30° S. lat. and the line between the Cape of Good Hope and Cape Horn, whose salinity is only 35-038. Fifth Region, A. The Baffin's Bay and Davis Straits Begion. — The mean of eight complete analyses is 33-281, the maximum 34*414, the minimum 32-304. This region shows the very interesting fact that its salinity increases on passing from latitude 64° toward the North, being in 64° 32-926, in 67° 33-187, somewhat further to the North 33-446, and in latitude 69° 33*598. This peculiarity is owing to the powerful current from the Parry Islands, which through different sounds passes into Baffin’s Bay, where it is mixed with the great quantity of fresh water that comes into the sea from the West Greenland glaciers. Had this fact been known before the sounds that connect the Parry Archipelago with Baffin’s Bay were discovered, it might have proved the existence of these sounds, because bays and inlets show quite the reverse ; the further we get into them the less saline the water becomes. Fifth Region, B. The Polar Sea between the North Cape in Norway and Spitzbergen. — I have eleven samples of water taken on the Swedish Spitzbergen Expedition by Pro- fessors Nordenskjold and Blomstrand, of which I have rejected one taken in one of the bays of Spitzbergen, and another belonging to the sea to the north of Spitzbergen. None of these analyses were complete, and I have only determined the quantity of chlorine and of sulphuric acid; and even the latter could in several instances not be determined, since the water had fermented. The mean quantity of chlorine in the nine remaining samples was 19-507 ; and if we take the mean coefficient of the four North * If we take the general coefficient of the ocean, 1-812, the salinity of the East Greenland current would be 35-258, which of course makes no material difference. 2 h 2 222 PROFESSOR FORCHHAMMER ON THE COMPOSITION Atlantic regions (the East Greenland current included), 1-810, 1-812, 1-808, 1-813, it will be 1-811 ; and if we use this coefficient, the mean salinity of that part of the sea will be 35-327, or if we take the mean coefficient of the whole ocean, 1-812, it will be 35-347. The maximum was in 76° 15' N. lat. and 13° 15' E. long., with 20-019 chlo- rine = 36-254 salt; the minimum in 70° 30' N. lat. and 19° 5' E. long., with 18-993 chlorine =34-396, near the coast of Norway, which evidently has had influence upon the result*. Fifth Region, C. The Polar Sea to the North of Spitzbergen. — I have only one observa- tion, of which I owe the sample to Professor Blomstrand. It is from 80° N. lat. and 12° E. long., containing 18-517 chlorine, which gives, with a coefficient of 1-812, a salinity of 33-623. Sixth Region. The German Ocean or the North Sea. — The mean of six complete ana- lyses is 32-823 per 1000 salt, the maximum is 35 041, the minimum 30-530 per 1000 salt, the maximum is from the mouth of the channel near the Gallopper, and the minimum is from Heligoland, where the water of the Elbe has a considerable influence. The mean coefficient is 1-816, which also shows the influence of the land. Seventh Region. The Kattegat and the Sound. — The quantity of salt in the water of this region is very variable ; a northerly current and wind brings water which is richer in salt than that brought by a southerly wind and current. The mean of six complete analyses and 141 observations, in which only the chlorine was determined, gives 16-230 per 1000 salt, the maximum 23-243, and the minimum 10*869. It must further be remarked that the proportion of chlorine and lime, which in the whole ocean are in mean number 100 : 2 -96, in this region are 100 : 3-29, which again must be considered as depending upon the influence of the land. The mean coefficient is 1-814. Eighth Region. The Baltic. — The mean numbers are deduced from complete analyses of samples of sea-water taken on board the Frigate ‘ Bellona,’ on a voyage from Copenhagen to St. Petersburg, combined with a complete analysis of water from Svartklubben to the north of Stockholm. Its salinity varies very much in the different localities, and is of course less in the eastern than in the western portions of the Baltic ; it varies also in the same place according to wind and current. I found the mean for this region 4-931 per 1000 salt, the maximum 7-481 in the channel between Bornholm and Sweden, the minimum in the merchant harbour of Kronstadt =0-610 per 1000 salt. The mean proportion of chlorine and lime is 100 : 3-64, in the Bay of Finland it is 100 : 7-49. The mean coefficient is 1-835, in the merchant harbour of Kronstadt it is 2-230. The influence of the land is here expressed in these different numbers. Ninth Region. The Mediterranean. — All my observations lie between the Straits of Gibraltar and the Greek Archipelago. It is a general belief that the water of the Mediterranean contains more salt than the water of the ocean in general, and this opinion depends partly upon some analyses, partly upon the observation that at the Straits of Gibraltar there is a constant upper-current, which runs into the Mediterranean, * That this sea is a branch of the Gulf-stream was acknowledged long ago. OF SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 223 and an under-current which carries its waters into the Atlantic. This opinion of the superior salinity of the Mediterranean has been completely confirmed by eleven com- plete analyses of water taken between the Straits of Gibraltar and the Greek Archipe- lago. The mean salinity of this region is 37*936, while the whole ocean contains 34*388 per 1000 salt. Its coefficient is 1*815. Its maximum (39*257) falls between the Island of Candia and the African shore off the Libyan desert, as the maximum of the Atlantic is off the Sahara, but the mean of the Mediterranean is a little higher than the maximum of the Atlantic ; the whole Mediterranean is under the influence of Africa, and its hot and dry winds. The minimum for the Mediterranean is at the Straits of Gibraltar with 36*301 ; the mean salinity of the northern Atlantic Ocean between 30° and 40° N. lat., but more towards the west, is 36*332 (deduced from eight complete analyses) ; the surface-water from the Straits of Gibraltar is thus corresponding to that from the Atlantic of the same latitude. When entering the Straits the quantity of salt increases rather rapidly, and is at a short distance from them, at 4° 2' W. long., 37*014; between the Balearic Islands and the Spanish coast it is 38*058, and a little further on 38*321, between the Island of Sardinia and Naples 38*654. Somewhat nearer to the coast of Malta it decreases to 38*541, and further on towards Greece it decreases again to 38*013, and would probably decrease more in the direction of the Bosphorus, but I have no observations from that part of the Mediterranean. From Malta to the coast of Africa it increases to the maximum of 39*257. There is another opinion generally reported, that the water of the Mediterranean contains a greater proportion of magnesia than the water of the ocean. This is, how- ever, not the case ; the mean proportion between chlorine and magnesia is for the Medi- terranean 100 : 10*90, and for the ocean 100 : 11*07 ; nor is there any remarkable differ- ence in the proportions of the other main substances. The proportion between chlorine and sulphuric acid is for the ocean 100 : 11*89, and for the Mediterranean 100 : 11*82 ; for lime it is in the ocean 100 : 2*96, and in the Mediterranean 100 : 3*08. Tenth Begion, A. The Black Sea and the Sea of Assov. — Like the Baltic, the Black Sea contains sea-water of but little strength, and the mean deduced from three observa- tions, of which one is from myself, the two others by M. Gobel, is 15*894, maximum =18*146, minimum =11*880. In my own analysis of water from the Black Sea, fifty English miles from the Bosphorus, I found the proportion of chlorine 100, to sulphuric acid 11*71, to lime 4*22, to magnesia 12*64, and thus a considerable increase in the lime and magnesia. Tenth Begion, B. The Caspian Sea. — This sea being by many geologists considered to have been in former times in connexion with the Black Sea, it might be of some interest to compare its water with that of the Black Sea. I have, however, not had opportunity of making an analysis of it myself, but have calculated other analyses according to my method. Of these five analyses four are by M. Mahner, and published by M. Baer in his ‘ Caspian Studies’ (Caspische Studien). As might be expected, the quantity of saline matter shows great differences, between 56*814 per 1000 in the Bay of Karassu or 224 PROFESSOR FORCHHAMMER ON THE COMPOSITION Kaidaik, and 6-236 per 1000. The proportion between chlorine, sulphuric acid, lime, and magnesia, is 100 : 44-91 : 9-34 : 21-48. It is quite evident that the Caspian Sea, if it ever had any connexion with the Black Sea, must have changed its character entirely since that time, and this change might either be occasioned by the different salts which the rivers brought into the lake, and which accumulated there by evaporation of the water, or it might be caused by the deposition of different salts in the basin of the Caspian Sea itself. If we now compare the abnormal proportions in the Caspian Sea, Chlorine 100, Sulphuric acid 44-91, Lime 9-34, Magnesia 21*48, with the normal proportions in the ocean, Chlorine 100, Sulphuric acid 11*89, Lime 2-96, Magnesia 11-07, we find that the excess of lime and magnesia will nearly neutralize the excess of sulphuric acid, and leave only a small quantity of sulphuric acid (3-72), which may be neutralized by alkalies. Thus rivers which brought sulphate of lime and of magnesia into the Cas- pian Sea, might in the lapse of 100 and 1000 years certainly change the composition of its water in the direction which it now has. Its mean coefficient is 2-434. Eleventh Region. The Atlantic Ocean between the Equator and 30° 8. lat. — The mean quantity of salts in this region, deduced from seven observations, is 36‘553, the maximum 37-155, the minimum 35-930. The relative quantity of chlorine, sulphuric acid, lime, and magnesia is 100: 12-03:2-91: 10-96. The water of this region is richer in salt than the corresponding region in the North Atlantic Sea. Its coefficient is 1-814. Twelfth Region. The Atlantic Ocean between 30° S. lat. and a line from Cape Horn to the Cape of Good Hope. — Mean salinity 35-038, maximum 35-907, minimum 34-151; the maximum not far from the Cape of Good Hope, the minimum not far from the Falkland Islands. Its salinity is less than the corresponding region in the North Atlantic (Region 2), which is 35-932, even less than the third and fourth regions (the East Greenland current), whose salinity is 35-278. This seems partly to depend upon the Gulf-stream, which causes a considerable evaporation in the northern part of the Atlantic, partly upon the River Plata in the South Atlantic, which carries an enormous quantity of fresh water into the southern sea. I have analyzed four samples of sea- water taken under the influence of that large river. One, taken by Captain Pkevost in 35° 46' S. lat. and 52° 57' W. long., almost at the mouth of the Plata, contained so much organic matter that a great part of its sulphuric acid was decomposed, so that the original quantity of salt could not be ascertained, but the quantity of chlorine, which, as far as we know, is not affected by the fermentation of the water, was only 17-721, which, multiplied by 1-808, the coefficient of this region, gives a quantity of salts — 32-040 ; the other three samples, taken between 40° 30' and 50° 31' S. lat., and 40° 50' and 52° 15' W. long., are all far below the mean salinity of this region. It deserves to be remarked, that all the samples from the western part of this region have a less OF SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 225 quantity of sulphuric acid than the normal, and the samples from the eastern part of the region nearer to the African coast have a proportion of sulphuric acid which is con- siderably greater than the normal quantity. Does this depend upon the more prevailing volcanic character of the west coast of Africa compared to the east coast of America \ Thirteenth Region. The sea between Africa and the East Indian Islands. — The mean of this region is 33-868, but it is deduced from observations that have given very different results. The maximum (35’802) is from 31-54 S. lat., 72° 37' E. long., about midway between the Cape of Good Hope and Australia. Now in the North Atlantic Ocean even the mean salinity between 30° and 55° N. lat. is 35-932, thus greater than the maximum in this region, though this maximum is from near 32° S. lat. The fact is striking. The minimum (25-879) is from a place high up in the Bay of Bengal, and of course highly influenced by the vast quantity of water from the Ganges. It lies, how- ever, about 300 English miles from the mouth of the Ganges ; and another specimen from N. lat. 17° 20', and about sixty miles nearer the mouth of the Ganges, has 32-365 per 1000 salt, so that it seems as if some other cause has also been operating to weaken the sea-water at the minimum place. Fourteenth Region. The sea between the south-east coast of Asia , the East Indian Islands , and the Aleutic Islands. — The mean quantity of salt, deduced from seven com- plete analyses, is 33-506, the maximum from a place to the south-east of Japan, in 38° 31' N. lat., is only 34*234, less than the maximum of the German Ocean between 50° 60' N. lat., and surrounded by land (35-041). The minimum (32-370) between the larger East Indian Islands depends evidently upon the influence of the surrounding land. The mean proportion of chlorine, suphuric acid, lime, magnesia, isl00:ll-76: 3-05:10-99, very nearly normal. The mean coefficient is 1-815. Fifteenth Region. The sea between the Aleutic Islands and the Society Islands , between 38° N. lat. and 32° S. lat. — The mean quantity of salt is only 35-219, which is very near the mean of the East Greenland current (35-278), and very much below the mean of the Atlantic between 30° S. and 30° N. lat., which is 36-321. Its maximum is 36-061 near Borabora, about 16° S. lat., while the maximum of the corresponding tropical part of the Atlantic is 37-908 ; its minimum, under 38° 26' N. lat., very far from any land, is 34-157. The mean proportion of chlorine, sulphuric acid, lime, and magnesia is 100 : 11-67 : 2-93 : 11-06. The mean coefficient is 1-806. Sixteenth Region. The Patagonian cold-water current. — Mean 33-966 per 1000, maxi- mum 34-152, minimum 33-788. The minimum is in the southernmost part of this current, and the maximum under 35° 22' S. lat. The mean proportion of chlorine, sulphuric acid, lime, and magnesia is 100 : 11-78 : 2'88 : 11-04. The mean coefficient is 1-806. Seventeenth Region. The South Polar Sea. — I have only three analyses, all on samples taken by the late Sir James Ross. One was from 77° 32' S. lat., 188° 21' E. long., close to the great ice-barrier. The water was full of animalculae, but, notwith- standing, had not fermented. The quantity of salt which it contained was 28-565 per 1000. The next sample was from 74° 15' S. lat., 167° E. long. ; the water was muddy, 226 PEOFESSOE FOECHHAMMEE ON THE COMPOSITION probably from animalculae and diatomacese. The place was not far from Victoria Land, at some distance from Coulman Island. It contained only 15-598 salt. The third, from 65° 57' S. lat., 164° 37' E. long., had the surprising quantity of salt 37‘513 per 1000. The mean of these three observations is 27’225 per 1000 ; but this mean number is of very little consequence, being derived from numbers differing so greatly. It is, however, very surprising that water from the neighbourhood of the supposed Antarctic continent should have a salinity higher than any one found in the south equatorial regions of the Atlantic, and only be exceeded by a single one in the North Atlantic regions. I am sure that no material fault exists in the analysis, and this curious fact must thus remain unexplained until repeated observations in that region shall procure us further informa- tion. Should the observation be proved to be correct, it would render the existence of a “ Gulf-stream ” in the Antarctic zone very probable. There is still another peculiarity in these observations which deserves attention, viz. the great proportion of sulphuric acid to chlorine. In the water in the neighbourhood of Coulman’s Island it is 12-47 : 100, and in that from 65° 57' S. lat. 12-55 : 100, while in the whole ocean it is as 11‘89 : 100. This might depend upon the very pronounced volcanic character of the Antarctic continent. There is still one question to be discussed with respect to the Antarctic Sea, how it is to enter into the mean numbers of the whole ocean. The observation from the neighbourhood of Coulman’s Island must be rejected, because it is too near the land, and we have no corresponding observations from the open Antarctic Ocean. Its high coefficient (1*861) shows the great influence of the neighbouring land. The observation from 65° 57' S. lat. must also be rejected as doubtful; there remains only the observation from the neighbourhood of the great ice-barrier, and I have taken that for the mean of the Antarctic region. General Results of the preceding investigation. If we except the North Sea, the Kattegat, Sound, and Baltic, the Mediterranean and Black Sea, the Caribbean Sea and the Bed Sea, which have all the characters of bays of the great ocean, the mean numbers are the following : — Sea-water. Chlorine. Sulphuric acid. Lime. Magnesia. All salts. Coefficient. 1000 18-999 2-258 0-556 2-096 34*404 1*812 100 11-88 2-93 11-03 Equivalents 429 45 16 82 Thus it is evident that sea-water in its totality is as little a chemical compound as the atmospheric air ; that it is composed of solutions of different chemical compounds ; that it is neutral, because it everywhere in the atmosphere finds carbonic acid to neutralize its bases, and everywhere on its bottom and shores finds carbonate of lime to neutralize any prevailing strong acid ; that, lastly, the great stability of its composition depends upon its enormous mass and its constant motion, which occasions that any local varia- tion is evanescent compared to the whole quantity of salt. OF SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 227 If we take the mean numbers for the five regions of the Atlantic between the south- ernmost point of Greenland and that of South America, we find the mean quantity of salt for the whole Atlantic 35*833, while the sea between Africa and the East Indies has only 33-850, the sea between the East Indies and the Aleutic Islands 33*569, and the South Sea, between the Aleutic Islands and the Society Islands, 35-219 per 1000 salt. The Atlantic is thus that part of the ocean which contains the greatest proportion of salt, which result is rather surprising if we consider the vast quantity of fresh water which the rivers of Africa, America, and Europe pour into it : of Africa four-fifths are drained into the Atlantic either directly or through the Mediterranean ; it is most pro- bably nine-tenths of America which is drained into the Atlantic, since the Cordilleras run close to the western shore of the continent ; and of Europe, also, about nine-tenths of the surface sends its superfluous water to the Atlantic. This greater quantity of fresh water from the land, and the greater quantity of salts in the corresponding sea, seem to contradict each other, but can be explained by a higher temperature, and, as the result of this higher temperature, a greater evaporation. Some of the large bays of the ocean have in the tropical or subtropical zone a greater mean than the Atlantic: such are the Mediterranean, with 37-936 per 1000 salt (mean of eleven observations); the Caribbean Sea, with 36-104 per 1000 (one observation); the Eed Sea, 43-067 per 1000 (mean of two but little differing observations), which is the greatest salinity of the sea I know of. In approaching the shores the sea-water becomes less rich in salts, a fact which finds its explanation in the more or less great quantity of fresh water which runs into the sea. On such shores where only small rivers flow out, the effect produced is but very trifling, as, for instance, on the western shores of South America. The effect of large rivers in diluting the sea-water is much greater than is generally supposed ; thus the effect of the La Plata river, whose mouth lies in about 35° of S. latitude, was still observable in a sample of sea-water taken at 50° 31' S. lat., at a distance of 15° of lati- tude, or 900 English miles from the mouth of the river; at about the same distance, the water of the North -Atlantic Sea suffered a considerable depression in salinity, pro- bably owing to the water of the St. Lawrence. This influence is of a double kind, partly in diluting the sea-water, partly in mixing it up with organic substances that will occasion its decomposition by putrefaction. The polar currents contain less salt than the equatorial. I have determined the quantity and nature of the salts in two very well-defined polar currents, — the West- Greenland polar current, with 33-176 per 1000 salt, and the Antarctic polar or Pata- gonian current, on the west side of South America, which contains 33-966. It is highly interesting to observe that the East Greenland current, which according to its geogra- phical relations might be considered as a polar current, which in fact has been con- sidered in that way, has a very high mean quantity of salt, viz. 35*278 per 1000, while the sea to the north of Spitzbergen, according to one analysis, contains 33-623 per 1000 salt. I think I shall afterwards, from other phenomena also, prove that the East mdccclxv. 2 i 228 PROFESSOR EORCHHAMMER ON THE COMPOSITION Greenland current is a returning branch of the Gulf-stream ; but I may here remark that the great quantity of salt which it contains almost by itself proves the more equa- torial nature of this current. As to the chemical substances which constitute the salts of the sea-water, it must be remarked that the polar current of West Greenland contains a larger quantity of sul- phuric acid than any other region, with the exception of the south polar region and the East Greenland current. The proportion between chlorine and sulphuric acid is — For the West Greenland current . For the East Greenland current . Near Coulman’s Island, Victoria Land From 65° 57' S. lat 100 : 12-27 100 : 12-34 100 : 12-47 100 : 12-55 The mean proportion for the ocean is 100 : 11-89 This excess of sulphuric acid in the Antarctic Sea might be explained by the decided volcanic character of its islands and shores ; even for the East Greenland current, the neighbourhood of Iceland and its volcanos might account for the excess of sulphuric acid; but the West Greenland polar current is under no such influence, and the sur- face-water of the Mediterranean, where so many volcanos exist, has 11-82 sulphuric acid, which is even a little below the mean proportion, 11-89. Only the water from the depth of the Mediterranean has an increased proportion of sulphuric acid, viz. 12-07. Thus it appears improbable that the excess of sulphuric acid in these polar regions should be owing only to volcanic action. It might depend upon the want of fucoidal plants. I have formerly, in a paper printed in the Report of the British Association for 1844, shown that the fucus tribe has a great attraction for sulphuric acid, and that the sulphuric acid, by the putrefaction of the plant, is reduced to soluble sulphurets and to sulphuretted hydrogen, which with the oxide of iron, which is partly dissolved, partly suspended in water, will form sulphuret of iron. Thus the sulphur will disappear from sea-water, and a great quantity of sea-weeds will diminish the quantity of sulphuric acid in the sea- water. Now it is well known that the polar regions have few or no sea-weeds, and Sir James Ross, when returning from the Antarctic polar region, remarks expressly that he observed the first sea-weed very far from the southernmost port of his voyage. An unusually small quantity of sulphuric acid seems to exist in the first of my regions, that part of the Atlantic which lies between the Equator and 30° N. lat., its relative quantity being 11*75. Does that depend upon the Sargassum Seal The greatest proportion of lime in the ocean occurs in its second region, the middle part of the northern Atlantic, where its proportion is 3"07, the mean proportion being 2*96; the least quantity of lime is found in the West Greenland polar current, with a proportion of 2-77 ; and next to that in the Patagonian polar current, with a proportion of 2*88. Wherever in other regions the influence of land is prevailing, the lime is like- wise prevailing. In the Baltic I found its proportion 3-59, in the Kattegat 3-29, in that Or SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 229 part of the German Ocean which lies close to the Kattegat 3*15, and in the whole German Ocean 2 -87. In a sample from the Black Sea which I analyzed I found it 4-22. B. On the difference of the contents of Sea-water at the surface and in different, depths. It would be natural to suppose that the quantity of salts in sea-water would increase with the depth, as it seems quite reasonable that the specific gravity of sea-water would cause such an arrangement. But this difference in specific gravity relative to the increase in the quantity of salts is counteracted by the decreasing temperature from the surface to the bottom. We have parts of the sea where the .quantity of solid salts increases with the depth ; in other parts it decreases with the increasing depth ; in other places hardly any difference can be found between surface and depth ; and, lastly, I have found one instance where water of a certain depth contained more salt than both that aboveand below. These differences are to a great extent dependent upon currents both on the surface and in different depths. The phenomenon of double currents at the Straits of Gibraltar has been long known, and in close connexion with these double currents the saline contents of the water of the Mediterranean increase in quantity with; the depth. There is, however, one exception in the Mediterranean, under interesting circumstances, which I shall afterwards discuss more at length. I have made eleven complete analyses of the surface-water of the Mediterranean, and calculated another quoted in Violette et Archambault, ‘ Dictionnaire des analyses chimiques,’ vol. i. p. 358, without a more exact reference to the place where it was taken. Of my own analyses, one must be rejected on account of the great quantity of sulphuretted hydro* gen that had been formed, and of course caused a loss of sulphuric acid ; but it causes also a loss of lime, because the formation of sulphuretted hydrogen is contemporaneous with the formation of carbonic acid, which will precipitate the lime when deprived of its sulphuric acid. The mean number of the remaining analyses of surface-water is 20889 per 1000 for the chlorine, and 37‘936 for all salts. The mean number for chlo- rine of eight analyses of water taken from a depth of between 300 to 600 feet is 21T38. In each case the deep water was richer in chlorine than that from the surfaoe, except in one instance, where the chlorine of the surface-water was 21 '718, and all salts, calcu- lated from a complete analysis, were 39*257 per 1000, while the chlorine of water taken from a depth of 522 feet was 21-521 per 1000. This curious exception occurred between Candia and the African coast, where the dry and hot winds from the neigh- bouring Libyan desert evidently cause a strong evaporation and a considerable eleva- tion of temperature, which counteract each other as to specific gravity. The difference between the upper and lower current in the Straits of Gibraltar is, in the surface-water,, chlorine 20-160 per 1000, all salts 36*391, and in the depth of 540 feet, chlorine 20-330. The cause why the surface-current is Atlantic water flowing into the Mediterranean,, and the under-current Mediterranean water flowing into the Atlantic, has long since been assigned to depend upon the comparatively small quantity of water that flows from the land into the Mediterranean, and the hot and dry African winds that cause more water 2 i 2 230 PROFESSOR FORCHHAMMER ON THE COMPOSITION to evaporate than the rivers bring into the sea. My analyses have not given me any reason to alter anything in our views of the cause of this difference, nor do I regard the single instance of water that is more rich in salts at the surface than in the depth as more than a local exception. As to the difference between surface and deep water for other substances, I shall only remark that the deep water of the Mediterranean contains a remarkable excess of sul- phuric acid. The proportion between chlorine and sulphuric acid is For the whole ocean . . . 100 : 11-89 Mediterranean surface . . . 100 : 11-82 Mediterranean depth . . . 100 : 12-07 Already in the Straits of Gibraltar the difference has the same character. The proportion is For the surface 100 : 11-42 For the deep water .... 100 : 11-93 In some places, however, in the Mediterranean the surface-water is richer in sulphuric acid than water from the depth ; thus, for instance, the sea between Sardinia and Naples had a proportion of 12-55 sulphuric acid in surface-water. In the Baltic we have the same phenomenon ; the water from the depth contains likewise more salt than that from the surface, but the direction of the currents is the reverse. The upper-current goes generally (not always) out of the Baltic, and the under- current goes, as it would appear, always into the Baltic. The cause of this great differ- ence between the Baltic and the Mediterranean is evident ; the Baltic receives the excess of atmospheric water from a great part of Europe. The greater part of Sweden, the greater part of European Russia, and a great part of North Germany send their water into the Baltic, and the evaporation is comparatively small. Thus the excess must find its way through the Sound and the Belts. With the assistance of Captain Prosilius, who in the year 1846 commanded the vessel at the station of Elsinore, the surface- current was observed on 134 days, from the 27th of April to the 11th of September ; of which on 24 days it ran from the north, on 86 days from the south, and on 24 days there was no surface-current at all. The quantity of chlorine was determined for every sample by titration, and from that the quantity of salt deduced by multiplication with the determined coefficient 1-812. The mean quantity of salt for the current from the North was 15*994 per 1000; that for the current from the South 11-801 ; that for the period when there was no current at all was 13-342. Once a week a sample was taken from the bottom, by sending a reversed bottle down to the bottom, turning it there, and after having allowed it to stand some time, taking it slowly up. The mean of nineteen observations was 19-002 per 1000 salt, which, according to the manner in which the samples were taken, is rather under than above the real mean, and proves clearly that it is water from the Kattegat which runs at the bottom of the Sound. But we have also direct observations of the same fact. Some years ago a steamer was, close to Elsinore, struck by another steamer, and sunk a very short time after the collision. Or SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 231 When afterw ards, in quiet sea, without current, a diver went down to save the passen- gers’ goods, he found a violent current from the North. To the same class of pheno- mena belongs also the observation that large deep-going vessels not unfrequently go on in the Sound against surface-current, where smaller vessels do not succeed. This under-current of Elsinore reaches often, and perhaps always, the harbour of Copenhagen, which I ascertained by a series of observations for which the laying of gas- and water-pipes offered me a good opportunity. To carry these pipes under the harbour, from Copenhagen to Christianshaven, on the Island Amager, a tunnel was pro- jected through a solid hard limestone of the chalk formation, which lies under Copen- hagen, its harbour, and its neighbourhood. When the tunnel was completed, it was found that the sea-water slowly filtered through the limestone, and fell down in drops from the roof of the tunnel. Comparative analyses would show how the water of the bottom of the harbour differed from that of the surface, and I might at the same time clear up another rather important question. It is generally known that the question of the formation of the dolomites, or the double carbonates of lime and magnesia, has excited a great interest, and many theories have been proposed about their formation. I myself have shown that a solution of carbonate of lime in carbonic acid water, when poured into sea-water, precipitates both carbonate of lime and carbonate of magnesia, but that the quantity of magnesia increases with the increased temperature in which the decomposition takes place. Neutral carbonate of lime thrown into sea-water would however, even at the boiling-point, not precipitate any carbonate of magnesia. It might, however, be a question of time, and it might be possible that such a decomposition would take place if sea- water during a long time was in close connexion with solid carbonate of lime. This would be the case if sea-water slowly filtered through 30 feet of solid limestone, which it does in the tunnel. We cannot, of course, expect to obtain any result by comparative analyses of the limestone ; any change in the composition of this great mass of limestone would be so small that no result could be drawn from it, but we might analyze the sea-water filtered through the stone, and determine very small changes in its composition. Thus a series of comparative analyses of the sea- water from the surface of the harbour, of that from the bottom of it, and of the water filtered through the limestone into the tunnel, would show, first, whether the under-current from Elsinore reaches the harbour of Copenhagen ; and secondly, whether the limestone roof of the tunnel acts upon the salts of magnesia in the sea-water which filters through it. The experiments were made in the following way: once a week, from the 3rd of March to the 25th of April, 1852, one sample was taken of sea-water from the surface of the harbour over the tunnel, another sample from the bottom of the harbour at the same place, and a third sample was collected from the filtering water in the tunnel. The mean of these analyses gave, For the surface 15-845 per 1000 salt For the bottom of the harbour . 17-546 „ For the tunnel 18-315 „ 232 PROFESSOR FORCHHAMMER ON THE COMPOSITION which, seems to prove that the under-current from Elsinore, at least at that season, reached Copenhagen. The difference between the water from the bottom of the har- bour and the tunnel might either be occasioned by the slowness with which the water filters through the limestone of 30 feet thickness, so that it was water from another period which at last reaches the tunnel, or it may be explained by the way in which the samples from the bottom were taken, by sending an open bottle reversed down to the bottom, where it was turned and allowed to stand some time, to let the heavier water from the bottom dislodge the lighter water which had entered the bottle. The mean relative quantity of lime and magnesia was — For the surface . . 1 lime to 4-062 magnesia. For the bottom . . 1 lime to 4-153 magnesia. For the tunnel . . 1 lime to 3-485 magnesia. The proportion between lime and magnesia is therefore pretty much the same in the water from the surface and the bottom of the harbour, but in the water from the tunnel the relative proportion of the lime is increased. This may depend either upon a diminution of the magnesia, or upon an increase of the lime, or upon a combination of both effects ; but if these changes took place only according to equivalents, it would prove that there had been formed dolomitic combination by the filtration of the mag- nesia salts of sea-water through the carbonate of lime in the limestone. To ascertain this point, I have compared the lime and magnesia with a third substance in sea-water, for which I chose chlorine. This mean proportion was — For the surface . . 100 chlorine : 2-82 lime : 11-07 magnesia. For the bottom . . 100 chlorine : 2-62 lime : 10-96 magnesia. For the tunnel . . 100 chlorine : 3-11 lime : 11-08 magnesia. It follows from these comparisons that the absolute quantity of lime had increased in the water of the tunnel, but that the absolute quantity of the magnesia in the same filtered water had not decreased, but was as nearly the same as an analysis could show. Thus the increase of the lime depended upon the solution of some carbonate of lime from the limestone. It was further found that water from the tunnel, when evaporated to dryness and dissolved, left more carbonate of lime than surface-water. The cause of this solution of the carbonate of lime was evidently to be sought in a bed of black mud which covers the bottom of the harbour, and is slowly converted into carbonic acid by the atmospheric oxygen absorbed by the sea-water. The sea-water impregnated with carbonic acid had dissolved some of the limestone through which it filtered. Here might also be the place to mention and explain a rather curious phenomenon which is observed all along our coasts of the 'Sound and the Baltic, at least as far as Kiel. When the ice in spring begins to thaw, it disappears quite suddenly, and all the fishermen along the shore assure you. unanimously that it sinks. I have examined a great number of these men, and have .not found a single one who did not confirm the sudden disappearance of the ice in spring,, and who did not consider it to be quite OF SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 238 certain that the ice in spring sinks. I could, however, not find a single one of them who had in spring fished the ice up in his nets, while they very often in autumn and the beginning of the winter find it at the bottomland see it rise to the surface*. It was evident that the sudden disappearance of the ice in spring was the fact which they had observed, and that the sinking of the ice was the popular explanation of the fact. The natural philosopher will not allow ice to sink in sea-water, and it seems neces- sary to find another explanation. In order to give that I must first mention another pecu- liarity with the under-current of Elsinore. I observed on the 2nd of March, 1850, the temperature of the under-current with a maximum thermometer to be +2'6 C. (360,8F.) at the depth of 108 feet, while the temperature at the surface was +1'6 G. (340,9 F.). Early in the next spring a friend of mine repeated the observation, and found likewise the higher temperature in the under-current, the difference being about 2° C. A third observation made in summer gave no difference. To explain this, I must observe that the Water of the Kattegat, at least in its depth, is a branch of that great part of the Gulf- stream that passes along the western shores of Norway, and that the under-current at Elsinore necessarily must be less affected by the cold which reigns over the Baltic in winter time. Thus the under-current has in spring a higher temperature than the water of the surface, and at the same time contains a greater quantity of salt. Suppose, now, that the ice towards spring has begun to thaw and has become porous, as is generally the case, the. warmer and more saline water will come in contact with it from below, and will melt it,, partly on account of its temperature above freezing-point, partly on account of the greater quantity of salt which it contains. Thus without any apparent greater changes on the- surface the ice will melt quickly and almost imperceptibly, and disappear. This effect of the under-current will be increased by the peculiarity of sea-water, that its point of greatest density lies below the freezing-point of pure water, and a constant series of small vertical currents will be formed where the warmer water rises, and that which is refrigerated by the contact with the ice sinks, which motion always will increase the melting of the surface-ice. Besides at Elsinore and at Copenhagen, it has been observed at Kiel, near Stockholm, and in the Bay of Finland, that the deeper water is more saline than that of the surface. At Svartklubben, near Stockholm, water from the surface contained 3-256 chlorine '=5-919 salt, and from a depth of 720 feet 3-912 chlorine =7T82 salt (coefficient T836); in the Bay of Finland, between the islands Nervoe and Sukjeld, the surface- water contained 3-552 per 1000 salt, while in a depth of 180 feet it contained 4*921. It was only for the two larger salt-water basins of Europe, the Mediterranean and * This formation of the bottom ice is very frequently observed on our shores. There is a fishing bank a little to the north of Elsinore, where the fishermen often in the beginning of the winter find themselves suddenly surrounded by ice, which they see rise through the water, containing numerous pieces of Fucus inclosed in its • mass. The same fact has also been observed not. far from Copenhagen, and off Nyborg in the Great Belt. It seems, in fact, a phenomenon peculiar to such places where a strong current runs over a place that is not very deep. 234 PROFESSOR EORCHIIAMMER ON THE COMPOSITION the Baltic, that I was able to determine the quantity of salt near the surface and in the depth, but it is very probable that similar differences also may occur in other large inlets of the ocean. I want, however, direct observations in sufficient number, and shall here only mention an observation from the Caribbean Sea, where surface-water contained 19-936 chlorine, and water from a depth of 1170 feet contained 19*823 per 1000 chlorine. This difference in which the deeper water is less saline may be another instance of the effect of hot winds, like the water from the Mediterranean between Africa and the Island of Candia. Going on now to the main section of the ocean, we will begin with the Atlantic, about which we have the best information, and which seems to show the most interesting facts. I will state the results of my investigations in moving from Baffin’s Bay towards the south. In Baffin’s Bay itself the water of the surface contains the same quantity of salt as that of the depth, but as soon as we pass the southernmost point of Greenland, the water of the surface contains more salt than that from the depth. This difference increases in going towards the Equator, and is indeed very considerable near that line. About the Equator, and a little to the south of it, many irregularities appear, as, for instance, in one case where the strongest water was found between two weaker portions above and below. In other cases the quantity of salt decreased with the depth, and in some instances it increased with it. I shall now state the observations themselves. Dr. Rink; sent me water from the surface in Baffin’s Bay to the west of Disco Island, Avhich contained 33-594 per 1000 salt, and at the same place from a depth of 420 feet, which contained 33-607. The difference is so small that it signifies nothing. At the southern- most point of Greenland a small difference is observed, viz. in 59° 45' N. lat. and 39° 4' W. long., where surface-water contains 35-067, and that from a depth of 270 feet 34-963; but in about the same latitude and about 13° further towards W., at 59° 42' N. lat. and 51° 20' long., the proportion was reversed, the surface-water contained 34-876 per 1000 salt, while that from the depth contained 34-975 per 1000. From the sea between Iceland and Greenland (in which it appears that a returning branch of the Gulf-stream, the East Greenland current, runs towards the S.W.) I have obtained eight specimens from a depth between 1 200-1800 feet. Unfortunately no specimens of water from the surface were taken at the same time, but we have a sufficient number of other surface observations, and thus we may compare the mean numbers, which are 35*356 for the surface, and 35-057 for a depth between 1200-1800 feet. In comparing the single obser- vations of the deep water, we find that it contains the greatest quantity of salt in the eastern part at 35° 1' W. long., with 35-179 per 1000 salt, decreasing regularly towards the westernmost part of this region in 55° 40' W. long., with a quantity of salt =34-858 per 1000. Specimens taken by Captain Gram in 59° 50' N. lat. and 7° 52' W. long., contained for surface-water 35-576 per 1000, and for water from 270 feet depth 35-462. I have two other comparative analyses of water from the East Greenland current, of which I owe the specimens to Colonel Schaffner. The analyses were not made com- ON SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 235 plete, but only chlorine and sulphuric acid were determined, which gives at 64° 30' N. lat. and 26° 24' W. long., for the surface, 19-616 chlorine, which with a coefficient 1-812 is =35-544 salt; for a depth of 1020 feet, 19-504 chlorine, which with a coefficient 1-812 is =35-341 salt. The next analysis of water from 62° 47' N. lat. and 37° 31'-5 W. long., gave for the surface, 19-491 chlorine =35*318 per 1000 salt; for a depth of 1200 feet, 19-466 chlorine =35-272 per 1000 salt. Further to the S.W., near the bank of Newfoundland, specimens taken by Captain von Dockum gave, for the surface, 36-360 per 1000 salt; for a depth of 240 feet, 36-598 per 1000 salt, which is an increasing quantity of salt for the deep water, and coincides with other observations which show that this curious decreasing of the quantity of salt, with the increasing depth, belongs only to the deep part of the Atlantic far from the shores. On the European side of that ocean three samples, taken by Captain Schulz at 47° 15' N. lat. and 9° 30' W. long., gave the following quantities of salt; — from the surface, 35-922 per 1000; from a depth of 390 feet, 35-925 per 1000 ; from a depth of 510 feet, 36"033 per 1000 ; thus showing a trifling increase of salt with the depth. The most complete set of experiments showing this influence of the shores, I have made on twelve samples taken by the ‘Porcupine’ in 1862, which I owe to the obliging kindness of Rear-Admiral FitzRoy. The samples are taken between 50° 56' and 55° 22' N. lat., and 12° 6' and 15° 59' W. long., about four degrees to eight degrees of longitude to the west of Ireland, and five of them were from the surface, while seven were from deep water, between 1200 and 10,500 feet. The mean of the five surface observations Chlorine. Sulphuric acid. Lime. is — Potash. Magnesia. All salts. 19-662 2-342 0-566 0-367 2-205 35-613. The mean of the seven observations from the deep sea is — Chlorine. Sulphuric acid. Lime. Potash. Magnesia. All salts. 19-677 2-357 0-583 0-363 2-193 35-687 2 K MDCCCLXV. 236 PROFESSOR, EORCHHAMMER ON THE COMPOSITION Chlorine =100, the proportions are — Chlorine. Sulphuric acid. Lime. Potash. Magnesia. All salts. For surface . . . 100 11-91 2-88 1-87 11-21 181-1 For deep water . . 100 11-98 2-96 1-84 11*14 181-4 The difference is very trifling, and the quantities of salts increase in a very slight degree with the depth. I owe all the other samples from the North Atlantic Ocean which have been used for my analyses, of which I am now going to give the results, to the late Sir James Eoss, through the assistance of the most honourable and learned President of the Royal Society, General Sabine, who always is most willing to assist scientific labours with his powerful influence and his prudent advice, and to whose intercession I am indebted for several of the most interesting results I have obtained in this investigation. At 18° 16' N. lat. and 29° 56' W. long., from the surface, 20-429 chlorine =36-833 per 1000 saltf °°e“ r { of water from Sir J. Ross=l*803); from 3609 feet, 19-666 chlorine =35*448 per 1000 salt. At 16° 27' N. lat and 29° W. long., from the surface, 20-186 chlorine =36-395 per 1000 salt (coefficient 1-803); from 900 feet, 20-029 chlorine =36*112 per 1000 salt (coefficient 1-803); from 2700 feet, 19- 602 chlorine =35-342 per 1000 salt (coefficient 1*803). At 15° 38' N. lat. and 28° 10' W. long. from the surface, 20- 081 chlorine =36-206 per 1000 salt (coefficient 1-803) ; from 3360 feet, 19-744 chlorine =35-598 per 1000 salt (coefficient 1-803). At 14° 18' N. lat. and 27° 15' W. long., surface observation wanting; from 900 feet, 19*934 chlorine =35*941 per 1000 salt (coefficient 1*803); from 2700 feet, 19- 580 chlorine =35*303 per 1000 salt (coefficient 1*803) ; from 3600 feet, 19*705 chlorine =35*528 per 1000 salt (coefficient 1-803). At 12° 36' N. lat. and 25° 35' W. long., from the surface, 20- 114 chlorine =36*195 per 1000 salt (direct observation) ; from 11,100 feet, 19-517 chlorine =35*170 per 1000 salt (direct observation). or SEA- WATER IN THE DIFFERENT PARTS OE THE OCEAN. 237 At 11° 43' N. lat. and 25° 6' W. long., from the surface, 20-035 chlorine = 36-123 per 1000 salt; from 3600 feet, 19-855 chlorine =35*799 per 1000 salt; from 4500 feet, 19-723 chlorine =35-561 per 1000 salt. At 1° 10' N. lat. and 25° 54' W. long., from the surface, 19-757 chlorine =35-622 per 1000 salt; from 1800 feet, 19*715 chlorine =35*546 per 1000 salt; from 3600 feet, 19-548 chlorine =35*245 per 1000 salt. For the South Atlantic Ocean, the relation between the salts of the upper and lower parts of the sea is variable and difficult to explain. In 0° 15' S. lat. and 25° 54' W. long, the quantity of salts found in different depths was as follows : — from the surface, wanting ; from 900 feet, 19-763 chlorine =35-820 (coefficient 1-814); from 1800 feet, 19- 991 chlorine =36-264 (coefficient 1-814);. from 4500 feet, 19*786 chlorine =35*892 (coefficient 1-814);, from 5400 feet, 20*007 chlorine =36-293 (coefficient 1-814). Most deviating is a series of observations from 22° 37' S. lat. and 34° 57' W. long. : — < from the surface, 20- 397 chlorine =37-000 (coefficient 1-814); from 900 feet, 20-323 chlorine =36*866 (coefficient 1-814); from 1800 feet, 23*189 chlorine =42-165 (coefficient 1-814);, from 2700 feet, 20-331 chlorine =36-880 (coefficient 1*814); from 3600 feet, 20-405 chlorine =37*015 (coefficient 1*814). Already in the water from different depths immediately on the south side of the Equator there is a curious variation ; at 1800 feet it is about one-half per 1000 richer in salt than at 900 feet, and in 4500 feet the quantity of salt has diminished as much as it 2 k 2 238 PROFESSOR FORCHHAMMER ON THE COMPOSITION had increased before. At 5400 feet it has a greater quantity of salt than any of the upper specimens has shown. In the series from 22° 37' S. lat. the surface has a high number, higher than any corresponding sample from the North Atlantic, it sinks a little at 900 feet, but rises at 1800 feet to a quantity of salt which does not occur in any other place in the whole Atlantic, not even the maximum of the Mediterranean, and we know only the Red Sea which exceeds it ; it is as if the water of the Red Sea were transported to this submarine current. I thought there might be a fault in the deter- mination of the chlorine, and repeated it; but the difference was very insignificant, being in the one case 23-187, in the other 23-191, the mean being 23-189. I thought that by some accident some salt might have come into the instrument by which the water was taken, and I made a complete analysis of the water, but the different sub- stances which were determined showed but slight differences from the normal propor- tions, viz. — Chlorine. Sulphuric acid. Lime. Potash. Magnesia. 22° 37' S. lat., 1800 feet . . 100 11-59 2-77 2-14 11-29 South Atlantic .... . 100 12-03 2-91 — 10-96 might perhaps be owing to an evaporation in the bottle, but then the bottle was full, and cork and sealing-wax were sound, while about one-seventh of its whole con tents must have been evaporated to explain the difference. If there is any mistake in this curious observation, it must probably have been caused by a negligence which left the instrument for taking the water from the deeper part of the sea partly filled with sea-water, exposed to evaporation in tropical heat, and sent it down without being cleaned. I should hardly think that such a fault could have been committed, and we must hope that new experiments will confirm the fact. The series of observations from 0° 15' S. lat. belong in fact to the same kind, by the alternation of stronger and weaker sea-water in different depths ; but the curious and surprising fact in the observation from 22° 37' S. lat. is, that in the whole Atlantic Ocean we do not know a single place where water with that quantity of salt occurs. The next specimen, from 22° 37' S. lat. and a depth of 2700 feet, is very nearly the same as that from 900 feet, and that from 5400 feet very near that from the surface of the same place. It appears thus that the water of the North Atlantic Ocean, between the southernmost part of Greenland and the equator, decreases in salinity with the depth, but that this curious fact is observed only in the middle bed of the Atlantic, and disappears when we approach the shores on both sides of the ocean. As to the cause of this rather surprising state, I am still of the same opinion which I expressed when I first observed it, that it depends upon a polar under-current. The hypothesis has been published, that it depended upon fresh-water springs at the bottom of the ocean, and such an opinion might have some chance as long as we only had few observations ; but now we have such a number of observations spread over a vast extent of the ocean, that it appears to be quite impossible to explain it by springs of fresh water, which of course must be more frequent and more powerful near the land, from which they have their OF SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 239 origin. Observation, however, shows the reverse ; near the shores the water is either uniform throughout its whole depth, or the quantity of salt increases with the depth. The next question is whether we can find a similar distribution in the other parts of the ocean. As to the southern portion of the Atlantic, there occurs such a confused distri- bution of the quantity of salt in the different depths at the same place, that we are not able as yet to draw any conclusions from it, but must wait for more copious observations. , As to the other parts of the ocean, I have only very few observations from the sea between Africa and the Aleutic Islands; but these few observations do not show any regularity, or at all events seem more to incline to an increase of the quantity of salt with the increasing depth. The geographical distribution between land and sea is, how- ever, quite different in this large part of the ocean. While a strong polar current from Baffin’s Bay pours its cold and less saline waters into the North Atlantic Sea, the large mass of Asia prevents any north polar current from reaching the south Asiatic sea, into which the numerous great rivers of Asia send vast quantities of warm fresh water. As to the south polar currents, we know very little about their influence upon the salinity of the southern ocean; but in Sir James Ross’s ‘Voyage’ (vol. ii. p. 133) there is an observation upon the different specific gravity in different depths, which indicates a state of things similar to that in the North Atlantic Ocean. His observations are these : — “At 39° 16' S. lat., 177° 2' W. long., the specific gravity of the surface-water 1-0274, at 150 fathoms 1-0272, and at 450 fathoms 1-0268, all tried at the temperature of 60° F., and showing that the water beneath was specifically lighter than that of the surface when brought to the same temperature ; our almost daily experiments confirmed these results ” *. The ’principal currents of the Atlantic , the Equatorial current , the Gulf -stream , and the East Greenland current. These three currents are in fact only the same ; they begin, as is well known, in the Bay of Benin, under the Equator, and the main current runs straight to the west over the Atlantic to Cape Roque, on the east coast of South America. I certainly shall not try to lessen the weight of the arguments which assign the cause of this equatorial current to the rotatory motion of the earth, but I will only give some remarks as to other influences that act to the same effect. If we compare the quantity of salt which is found in sea-water in the region between * To compare these observations of specific gravity with the quantity of salt in different depths, which I have mentioned in the former part of this paper, I shall here refer to some experiments which I have made to obtain a ratio by which I could compute the quantity of salts in the sea-water from the specific gravity, and vice versa. I have compared, in thirteen specimens of sea-water, the specific gravity with the quantity of chlorine which the water contained, between 13°-75 C. (56°-75 F.) and 18°-8 C. (65°-8 F.). It was found that a unit in the fourth decimal place of the specific gravity of sea-water, measured by the hydrometer, is equal to l.ooY.ooo chlorine, the minimum being 66, the maximum 76. To find what quantity of salt corresponds to the specific gravity of the surface-water, as determined by Sir James Ross to he 1-0274, we must multiply 274 by 71, which gives 19-454 chlorine in the sea-water, and that number being multiplied by the general coefft-' cient 1-812, gives 35-251 per 1000 salt for the water from the surface. According to the same computation the sea-water from 150 fathoms contained 34-993 per 1000 salt, and that from 450 fathoms 34-478 per 1000 salt. 240 PEOFESSOE FOECHIIAMMEE ON THE COMPOSITION 5° N. lat. and 5° S. lat. with those between 5° and 20° to the North and of 5° to 30° to the South, we find the interesting fact that the water flowing in the vicinity of the Equator contains less salt than that which flows both to the north and to the south of it. For the equatorial region (5° S. to 5° N.) the mean of six observations is 35*575 per 1000 ; or if we leave out a sample from Sir James Ross, from 150 fathoms’ depth (that from the surface is wanting), it is 35 ‘520. From 5° to 20° N. the mean of eight analyses is 36 ’2 79, and from 5° to 30° S. the mean of six analyses is 36*631 per 1000. This difference is still more striking on comparing the salinity of the equatorial region with that of the northern Atlantic region (second region), whose mean is 35*932 per 1000 salt. It deserves further attention, that the maximum of the equatorial region is below the mean of its neighbours both to the south and to the north. It appears to me that this curious fact can be explained only by the vast quantity of fresh water which the Niger, the Ogaway, and a number of other West African rivers carry in this region into the sea, which all gets into the equatorial current, and moves to the westward. It is evident that this warm water must increase its relative quantity of salt by evaporation during its motion across the Atlantic, and a comparison of the analyses of the single samples of the water from the equatorial current shows that this effect really takes place. The easternmost sample contains the minimum, with 34*238 per 1000, and the two westernmost samples contain the greatest quantity of salt, with 36*084. Thus the equatorial current appears as a continuation of the large West African rivers of the equatorial zone, which dilute the sea-water of the equatorial region with about 8 per cent, of fresh water, and thus counteract the great evaporation. While the equatorial current continues its course along the north-east coast of South America, it receives and carries with it the waters of the Paranahyba, the Araguai, the Amazon river, the Esse- quibo, the Orinoco, and numerous smaller rivers of the north coast of South America ; but though I have no observations from this part of the current*, the fact is shown by three observations from the sea in the neighbourhood of the Danish islands of St. Croix * [When my remarks on the equatorial current between Cape Eoque and the West Indian islands were written, I was not aware of the very interesting observations which General Sabine made in 1822, on the influence of the water of the Amazon river on that of the Equatorial current. I shall now insert them here, their hearing being in the same way as my deficient observations. In 5° 8' N. lat. and 50° 28' W. long, a distinct line of separation was observed between the pure blue water of the ocean and the discoloured water mixed with that from the Amazon river, the mouth of which was about 300 miles distant. The blue water had a specific gravity of 1-0262, which according to my calculation (p. 37) is =33-672 per 1000 salt, while the water on the other side of the line of separation was 1-0204=26-345 per 1000 salt; further on, under the influence of the river, it was 1-0185=23-800 per 1000 salt. But the river water kept on the surface and in a depth of 126 feet, the specific gravity was l-0262(= 33-672 per 1000 salt).. In 7° 1' N. lat. and 52° 38'-5 W. long, the specific gravity was 1-0248=31-905 per 1000 salt, and in 120 feet depth again 1-0262 specific gravity. In 7° 5' N. lat. and 53° 30' W. long, it was 1-0253=32-549 per 1000 salt. In the Gulf of Paria, off the mouth of the Orinoco, the specific gravity was 1-0204=26-345 per 1000 salt, and in crossing one of the branches of the- river itself the specific gravity was found to be only 1-0064=8-234 per 1000 salt. See ‘An Account of Experiments to determine the Figure of the Earth, by Edwakd Sabine. London, 1825.’— G, F., April, 1865.] OF SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 241 and St. Thomas, whose mean salinity is 35*7 per 1000 ; while two degrees more to the north the mean of two observations is 36*7, which seems to be the normal salinity of the West Indian Sea. In the Caribbean Sea, where the Magdalene river gives a new quantity of fresh water, the sea contains on the surface, according to one observation, 36*104 per 1000 salt. I have unfortunately no observation from the Mexican Gulf, nor from the beginning of the Gulf-stream, where it leaves the Mexican Gulf, but to the north of the Bermudas it contains only 35*883 per 1000 salt, about the same quan- tity which the equatorial current contains between 20° and 30° W. longitude. From that place the salt of the Gulf-stream increases constantly during its course towards the north-east, viz. 36*105 per 1000, 36*283 per 1000. In 43° 26' N.lat. and 44° 19' W. long., about 16° of longitude to the east of the southern mouth of the St. Lawrence, between Nova Scotia and Newfoundland, it sinks suddenly to 33*854 per 1000, and rises from thence slowly in its course towards the east to 34*102 and 35*597, until, midway between Newfoundland and the south-western cape of Great Britain, it has risen to 35*896 per 1000, a quantity of salt which diminishes very little in the whole North Atlantic Ocean between Scotland and Iceland. During this whole long course, from the Bay of Benin to Spitzbergen, this remarkable current shows a constant oscillation between the diluting influence of the large rivers and the evaporation occasioned by the high temperature of the current. Now we shall try to trace its further progress. I have always thought that the East Greenland current was of polar origin, and that it carried the waters from the large opening between Spitzbergen and the northernmost coast of Greenland into Davis’s Straits, where it turns and mixes its waters with the polar current that comes from the North American polar sea through Lancaster Sound, and the numerous other sounds that connect Baffin's Bay with the American polar sea, but I never had an opportunity of making comparative analyses of the water from that but seldom visited part of the ocean. Colonel Schaffner had the kindness on his voyage between the eastern part of Iceland and the south part of Greenland to take a number of samples, which I have analyzed, and the result of which will be found in my fourth region, the East Green- land current. The mean of twelve observations of water, taken for the greatest part by Colonel Schaffjster (three by Captain Gram), is 35*278 per 1000 salt, where one analysis of water taken in the ice-pack is left out, being no fair sample of sea-water from that region. In comparing this mean number with that of the North Atlantic Ocean (35*391), there will hardly be found any difference in the quantity of salt the two contain ; while there is a great difference between these and the real polar current of Baffin’s Bay, which is 33*281 per 1000, or of the Patagonian polar current (33*966). I think we may infer from this fact, that the East Greenland current is a returning branch of the Gulf- stream, and that the east coast of Greenland proportionally gives very few icebergs and very little glacial water to the sea. For comparison’s sake I shall mention here that the sea about midway between Norway and Spitzbergen contains 35*222 per 1000. I found the water taken on the south side of that island to contain 35*416 per 1000, while that 242 PROFESSOR FORCHHAMMER ON THE COMPOSITION on the north side of Spitzbergen contained 33-623 per 1000. The last-mentioned sample seems to be real polar water, while all the water that flows between Norway, Spitzbergen, Iceland, and the east coast of Greenland partakes of the nature of the Gulf-stream. Besides the reasons just mentioned for considering the East Greenland current to be a returning branch of the Gulf-stream, reasons which are deduced from the quantity of salt which the water contains, there are other reasons which lead to the same result. It is well known that the Gulf-stream brings tropical fruits from America to the coast of Norway, and it has once brought a river-vessel loaded with mahogany to the coast of the Faroe Islands. It is likewise known that similar fruits to those which are found on the Norwegian shores are carried by the sea to the coast of Iceland, and principally to its north and east coasts, where they only could get if the Gulf-stream turns between Spitz- bergen and Iceland, and thus runs between Iceland and Greenland towards the south- west. It would be difficult to explain how a polar current could bring tropical fruit to the north coast of Iceland. On the west coast of Greenland the south-easterly wind brings in winter a mild tem- perature, and this fact is so generally known in the Danish colonies of Greenland, that many of the colonists are convinced that there are volcanos in the interior of that snow-clad land. The temperature which this current, that in winter and spring is full of drifting ice (not icebergs), communicates, can of course not be above freezing-point, hut that temperature is mild, when the general temperature in winter is 8°, 10°, or 12° R. below the freezing-point. All these facts together leave hardly any doubt in my mind that it is the Gulf-stream which runs along the east coast of Greenland, and at last in Davis’s Straits mixes its waters with the polar current from Baffin’s Bay. In its course towards the south it meets the main part of the Gulf-stream at Newfoundland, where it partly mixes with it to begin its circulation anew, partly dives under it, and runs as a ground stream as far as the Equator. In a similar way the southern branch of the Gulf- stream, which goes parallel to the western shores of South Europe and North Africa, joins the equatorial current at its beginning in the Bay of Benin, and begins also its circulation anew. Chemical Decomposition in Sea-water. If we consider the almost uniform composition of sea-water in the different parts of the ocean, such as they are represented by comparing the salts with the quantity of chlorine as unity, and thus avoiding the influence of the different quantities of water in which they are dissolved, we might be inclined to suppose the salts of sea-water to be in chemical combination with each other, and to form a compound salt with definite proportions. This is however not the case, and sea-water is not more a chemical com- pound than the atmospheric air, and the steadiness of the quantity of the different sub- stances depends partly upon the enormous mass of the water of the ocean, compared to which all changes disappear, partly upon the constant motion which current and wind occasion. In the bays and those parts of the sea which only have narrow sounds that connect them with the main ocean, where therefore the general motion of the sea 4 OF SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 243 cannot have that influence it has in the open ocean, we observe differences which show the influence of the land upon the constituent parts of the sea-water. This want of chemical combination between different salts will become more evident when, instead of comparing their different quantities, we compare the relative number of their equi- valents. The mean quantity of the different substances in the whole ocean, as deduced from the mean of regions I., II., III., IV., V., XI., XII., XIII, XIV, XV, XVI, XVII, is in 1000 parts of sea-water, — Chlorine. 18-999 Sulphuric acid. 2-258 Lime. Potash. Magnesia. 0-556 0-367* 11-03 All salts. 34-404 Coefficient. 1-811 Sulphuric acid. 11-88 Chlorine =100. Lime. Potash. Magnesia. 2-93 1-87* 11-03 All salts. 181-1 Chlorine. 429 Proportion of Equivalents. Sulphuric acid. Lime. Potash. 45 16 6 Magnesia. 82. There is one question which deserves a closer examination, viz. how the salts that now constitute the water of the sea came into it X Is it the land that forms the sea, or is it the sea that makes the land X Are the salts that now are found in sea-water washed out of the land by the atmospheric water X Has the sea existed from the beginning of the earth X and has it slowly but continually given its elements to form the land X To try to give an answer to these most important questions, let us suppose that any river, for instance the Rhine, had its outlet into a valley with no communication with the sea, it would be filled with water until its surface was so great, that the annual evaporation was equal to the quantity of water which the river carried into it ; then there would be a physical equilibrium but no chemical, because all the water that was carried into the lake would contain different mineral substances, which the rain-water had dis- solved from the country which the river drains, while the loss by evaporation would be pure water. The quantity of saline substances in the lake would constantly go on increasing until chemical changes would occasion the precipitation of different salts. By comparing the chemical constitution of the water of the Rhine, we might form an idea of the different elements contained in the water of this lake. We should find that among the bases the lime was prevailing, and next to it the magnesia, next to it the soda, the iron, the manganese, the alumina, and potash. Of acids the carbonic would be prevailing, and next to it the sulphuric, the muriatic (chlorine), and the silicic. Now all these substances are found in sea- water, but the proportions are quite different. * The potash which I have mentioned here represents in fact not the mean of all the observations in the great ocean, but only the mean of a number of determinations for the northern part of the Atlantic, my older observations on the quantity of potash in the other parts of the ocean being not exact enough. This quantity of potash differs most probably very little from the real mean. MDCCCLXV. 2 L 244 PEOFESSOE FOECHHAMMEE ON THE COMPOSITION The ocean is in fact such a lake, into which all the rivers carry what they have dissolved from the land, and from which pure water evaporates ; and whatever we think about the constitution of the primitive ocean, this effect of the rivers, which has lasted for thousands of years, must have had an influence upon the sea. Why do we not observe a greater influence of the rivers 1 Why does not lime, the prevailing base of river-water, occur in a greater proportion in the water of the ocean 1 In all river-water the number of equivalents of sulphuric acid is much smaller than that of lime, and yet we find in sea-water about three equivalents sulphuric acid to one of lime. There must thus be in sea- water a constantly acting cause that deprives it again of the lime which the rivers furnish, and we find it in the shell fishes, the corals, the bryozoa, and all the other animals which deposit carbonate of lime. From the proportion between sulphuric acid and lime in river-water and in sea-water, it is evident that these animals are able not only to deprive the water of its carbonate of lime, of which sea-water contains very little, but that they also must decompose the sulphate of lime, a decomposition which probably depends upon the carbonate of ammonia which is formed by the vital process of these animals. I have shown that a salt of ammonia occurs in sea-water, certainly in small quantities, which however does not signify much, since the ammonia is constantly absorbed by the sea-weeds. Thus it is a chemical action of small animals which con- stantly deprives the sea of its excess of lime. Next to the lime we must consider the silica, which is a constant constituent of river- water, and the immense quantity of diatomacese, of infusoria, and sponges will account for the small quantity of it at any given time in sea-water. I shall name next the sulphuric acid. All the shells of shell fishes, all the carbonate of lime in the corals and bryozoa contain some sulphate of lime, about one per cent, or less, but all the sea-weeds attract a great quantity of sulphates, which by the putrefaction of the plants are changed into sulphurets ; and the sulphurets give again their sulphur to the iron, both that which is dissolved in sea-water, and that which in the form of oxide, combined with clay and other earths, is mechanically suspended in the water of the sea, principally near the shores. Thus the sulphur is made insoluble and disappears from the brine. The mag- nesia enters in a small quantity into the shells and corals, but only a small quantity is thus abstracted from sea-water, and at last the soda and muriatic acid or chlorine form, as far as we know, by the pure chemical or organico-chemical action that takes place in the sea, no insoluble compound. Thus the quantity of the different elements in sea- water is not proportional to the quantity of elements which river-water pours into the sea, but inversely proportional to the facility with which the elements in sea-water are made insoluble by general chemical or organo-chemical actions in the sea ; and we may well infer that the chemical composition of the water of the ocean in a great part is owing to the influence which general and organo-chemical decomposition has upon it, whatever may have been the composition of the primitive ocean. I shall, however, not dwell any longer on this side of the question, which deserves a much more detailed representation than I can give it here. OF SEA- WATER IN THE DIEEEEENT PARTS OF THE OCEAN. 245 There is a more special decomposition of sea-water, which takes place exceptionally, but these exceptions are very frequent. They depend upon the organic beings that live in the sea, die, and decay in the sea, and are finally dissolved. Of these substances that have their origin from organic beings, I have already named ammonia ; but there are other substances of organic origin, probably of a more complicated nature, which I have observed in the following way. If we pour one or two drops of a solution of hypermanganate of potash into fresh sea-water, which has no smell of sulphuretted hydrogen, we shall after a short time observe a change in the colour of the liquid, but it is hardly more than the first drop that is decomposed so soon after it has been mixed with sea-water. The next decomposition goes slower, and is only finished after the liquid has been boiled for some time. Now if we pour hypermanganate of potash into a very diluted solution of ammonia, it will be completely decomposed by warming the mixture to a slight degree. I suppose that the first action upon the hypermanganate depends upon the ammonia in sea-water, and the next, which is slower and requires boiling and a longer time of action, depends probably upon the other products of spon- taneous decomposition of organic matter. Coinciding with these observations is the experience that sea-water taken near the surface decomposes a smaller quantity of hypermanganate than that which is taken from the depth. If it was ammonia that produced the decomposition, there is no reason why there should be less of it near the surface than in deep water, since it being combined with a strong acid (either sulphuric or muriatic) neither could be volatilized nor oxidized. If it was organic matter, it would be oxidized near the surface, on account of the absorbed oxygen of the atmosphere. When this organic matter increases in sea-water near the shores, or at the mouth of rivers, it will cause a real putrefaction, and attack the sulphates, converting them into sulphurets, which again are decomposed by the carbonic acid formed from the organic substances at the expense of the oxygen of the sulphuric acid. This sulphuretted hydrogen gets free, the carbonic acid will precipitate lime, and a loss of sulphuric acid by fermentation will always occasion a loss of lime in sea-water. Putrefaction seldom decomposes more than a small quantity of the sulphuric acid present in sea-water, and even where it seems to have been very powerful, not one-third part of the sulphuric acid has been destroyed. While thus a portion of the sulphates always remains unde- composed, there also seems always to remain a portion of the organic matter unoxidized. The sulphuretted hydrogen acts instantaneously upon hypermanganates, but when all smell of sulphuretted hydrogen has disappeared, there still remains some substance in putrefied sea-water which bleaches the hypermanganates when the water is boiled. It may be one of the lower oxides of sulphur, or it may be that the organic substance was not fully oxidized. There is still one general effect of the organic substances dissolved in sea-water, that all iron is reduced from peroxide to protoxide, all mud from the deeper parts of the sea is dark coloured, either grey, bluish, or green. All Sir James Ross’s deep soundings brought blue or green mud or sand to the surface. 2 L 2 426 PROFESSOR FORCHHAMMER ON THE COMPOSITION In the following Tables the sulphuric acid, lime, magnesia, and potash are given both in parts per 1000 sea-water, and referred to chlorine as 100. The latter numbers are distinguished by being enclosed in parentheses. First Region. — From the Equator to 30° N. lat. Chlorine. Sulphuric Lime. Magnesia. All salts together. Coefficient. acid. 1. Sir James Ross, June 11, 1843. 1 19-757 2-303 0-584 2-333 35-737 1-801 N. lat. 1° 10', W. long. 25° 54' J (11-66) (2-96) (11-81) 2. Captain Irminger, September 9, 1 847. \ 19-584 2-315 0-765 2-179 35-803 1-803 Tocorady Bay, Guinea, 1 mile from the land... J (11-66) (3-85) (10-99) 3. Captain Irminger, September 7? 1847- 1 N. lat. 4° 10', W. long. 5° 36' / 19-014 2*224 0-660 2-163 24-283 1-803 20-070 (11-64) (3-47) (11-37) 36-327 4. Sir James Ross, July 6, 1843. 1 N. lat. 6° 43', W. long. 27° 4' / f>. Valkyrie, February 3, 1848. 19-766 2-415 0-568 2-117 35-941 1-818 N. lat. 10°, W. long. 24° 19£' J (12-22) (2-87) (10-71) 6. Sir James Ross, July 11, 1843. 1 N. lat. 11° 43', W. long. 25° 6' J 20-035 36-263 7. Sir James Ross, July 22, 1843. 1 20-114 2-343 0-619 2-315 36-195 1*800 N. lat. 12° 36', W. long. 25° 33' J (11-39) (3-08) (11-21) 8. Sir James Ross, July 25, 1843. 1 N. lat. 15° 38', W. long. 27° 15' / 20-081 36-347 9. Sir James Ross, July 26, 1843. 1 N. lat. 16° 57', W. long. 29° / 20-186 36-537 10. Sir James Ross, July 27, 1843. 1 N. lat. 18° 6', W. long. 29° 56' / 20-429 36-976 11. Ornen, October 19, 1846. 1 19-818 2-376 0-567 2-123 35-775 1-805 N. lat. 19° 20', W. long. 65° 28' / (11-99) (2-86) (10-76) 12. Valkyrie, January 28, 1848. 1 N. lat. 24° 13', W. long. 23° 1 1' J 20-898 2-446 0-595 2-280 37-908 1-814 (11-70) (2-85) (10-91) 13. Captain von Dockum, July 17, 1845. 1 19-650 2-309 0-567 2-236 35-732 1-819 Between the Islands St. Croix and St. Thomas / (11-75) (2-89) (11-36) 14. Captain von Dockum, July 18, 1845. 1 17*798 2-304 0-426 2-195 35-769 1-807 Likewise between the two islands J (11-64) (2-15) (11-69) 15. Ornen, October 23, 1846. 1 20-320 2-423 0-602 2-208 36-784 1-810 N. lat. 22° 43', W. long. 65° 12' J (11-92) 2-344 (2-96) 0-554 (10-87) 2-164 16. Captain von Dockum, Julv 29, 1845. 1 20-145 36-508 1-812 N. lat. 22° 30', W. long. 69° 1 0' / (11-64) (2-75) (10-74) 17- Captain Irminger, March 17, 1849. 1 20-302 2-450 0-620 2-302 36-736 1-809 N. lat. 25° 4', W. long. 65° 40' j (12-07) (3-05) (11-34) 18. Captain von Dockum, July 30, 1845. 1 N. lat. 23° 26', W. long. 64° 8' / 20-291 2-207 (10-88) 2-418 0-606 (2-99) 0-600 2-251 (11-09) 2-217 36-352 1*792 19. Ornen, October 28, 1846. 1 20-389 36-838 1-807 N. lat. 29° 27', W. long. 60° 1' / (11-86) (2-94) (10-87) Mean <| ' 20-034 2-348 0-595 2-220 36-253 1-810 (11-75) (2-98) (11-11) Maximum j : 20-898 2-450 (12-22) 0*765 (3-85) 2-333 (11-81) 37-908 1-819 Minimum j ■ 19-014 2-207 (10-88) 0-426 (2-15) 2-117 (10-71) 34-283 1-792 OF SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 247 Second Region. — The Atlantic between 30° N. lat. and a line from the northernmost point of Scotland to the north point of Newfoundland. Chlorine. Sulphuric acid. Lime. Magnesia. All salts together. Coefficient. 1. Captain von Dockum, August 3, 1843. ] N. lat. 31° 51', W. long. 67° 23' f 20*159 2*449 0*607 2*460 36*480 1*810 (12*15) (3*01) (12*20) 1 2. Captain von Dockum, August 3, 1843. ] N. lat. 32°„52', W. long. 68°. To the west of l the Bermudas 1 20*064 2*489 (12*15) 0*566 (2*82) 2*062 (10*28) 36*635 1*826 | 3. Captain Schulz, September 28, I860. 1 20*160 2*302 0*610 2*134 36*391 1*805 Straits of Gibraltar j (11*42) (3*03) (10*59) 4. Ornen, November 5, 1846. 20*080 2*398 0*600 2*250 36*304 1*808 N. lat. 36° 13', W. long. 55° 7' | (11*94) (2*98) (11*20) 5. Captain von Dockum, August 6, 1843. | N. lat. 36° 52', W. long. 66° 38'. North from L 19*890 2*336 0*595 2*299 35*883 1*804 Bermudas in the Gulf-stream J (11*74) (2*99) (11*66) 6. Ornen, November 7, 1846. | 20*103 2*518 0*643 2*177 36*643 1*823 N. Iat. 37° 5', W. long. 48° 24' j 7. Captain von Dockum, August 7, 1843. 1 N. lat. 37° 24', W. long. 6l° 8' j (12*52) (3*15) (10*83) 19*943 2*374 (11*90) 2*557 0*595 (2*98) 0*689 2*284 (11*45) 2*260 36*105 1*810 8. Ornen, November 9, 1846. 1 20*247 36*928 1*824 N. lat. 38° 18', W. long. 43° 2' J (12*63) (3*40) (11*16) 9. Captain von Dockum, August 13, 1843. 1 20*063 2*432 0*588 2*208 36*283 1*808 N. lat. 39° 39', W. long. 55° 16' J (12*12) (2*93) (11*01) 10. Captain von Dockum, August 13, 1843. 1 N. lat. 40° 21', W. long. 54° 15' J 20*098 2*425 0*606 2*391 36*360 1*809 (12*07) (3*02) (11*90) 11. Ornen, November 11, 1846. j N. lat. 40° 53', W. long. 36° 23'. S.W. from l the Newfoundland Bank J 20*062 2*427 (12*10) 0*718 (3*58) 3*123 (10*58) 36*389 1*814 12. Captain von Dockum, August 17, 1843. 1 18*685 2*208 0*534 2*081 33*854 1*812 N. lat. 43° 26', W. long. 44° 19' J (11*82) (2*86) (11*14) 13. Captain von Dockum, August 18, 1843. j N. lat. 44° 33', W. long. 42° 34'. E. from the l 18*842 2*236 0*560 2*079 34*102 1*810 Newfoundland Bank J (11*87) (2*97) (11*03) 14. Omen, November 13, 1846. \ 19*890 2*376 0*650 2*154 36*032 1*812 N. lat. 44° 39', W. long. 30° 20' j (11-95) (3*27) (10*83) 15. Ornen, November 15, 1846. 1 19*857 2*400 0*582 2*185 36*010 1*813 N. lat. 46° 22', W. long. 22° 55' J (12*09) (2*93) (11*01) 16. Ornen. \ 19*892 2*400 0*586 2*175 36*090 1*814 N. lat. 47° 10', W. long. 18° 45' j (12*09) (2*94) (10*94) 17* Ornen. \ 19*722 2*441 0*590 2*166 35*872 1*819 N. lat. 47° 17', W. long. 14° 24' j (12*38) (2*99) (10*98) 18. Captain von Dockum. N. lat. 47° 17f, W. long. 19° 9' ( 19*656 2*346 0*580 2*170 35*625 1*812 (11*94) (2*95) (11*04) 36*119 19. Captain von Dockum. 19*915 2*413 0*587 2*172 1*814 N. lat. 47° 18', W. long. 21° 6|' j (12*12) 2*327 (2*95) 0*583 (10*91) 2*265 20. Captain von Dockum. 1 19*860 35*896 1*808 N. lat. 47° 40', W. long. 32° 7' J (11*72) (2*94) (11*40) 21. Captain Schulz. 1 19*664 2*556 0*589 2*273 35*922 1*823 N. lat. 47° 45', W. long. 9° 30' J (13*01) (2*99) (11*57) 22. Captain von Dockum. N. lat. 47° 50’, W. long. 33° 50' j 19*749 2*320 0*601 2*183 35*597 1*803 (11*75) (3*04) (11*06) 23. Ornen. 1 19*882 2*393 0*726 2*077 36*093 1*815 N. lat. 48° 10', W. long. 9° 35' J (12*03) (3*65) (10*45) 24. Captain von Dockum. 1 N. lat. 50° 3', W. long. 11° 6' J 25. Porcupine, mean of 5 analyses of surface- ) water taken between 51° 9' and 55° 32’ N. 1 19*691 2*336 (11*86) 0*572 (2*90) 2*208 (11*21) 35*570 1*806 19*662 2*342 0*566 2*205 35*613 1*811 lat., and 12° 11' and 13° 59' W. long J Mean j 19*828 2*389 0*607 2*201 35*932 1*812 (12*05) (3*07) (11*10) 36*927 1*826 Maximum J 20*247 2*557 (13*01) 0*726 (3*65) 2*460 (12*20) Minimum j 18*685 2*208 0*534 2*062 33*854 1*791 | (11*08) (2*82) (10*28) 248 PROFESSOR FORCHHAMMER ON THE COMPOSITION Third Region. — The northern part of the Atlantic, between the northern boundary of the second region, and a line from the south-west point of Iceland to Sandwich Bay, Labrador. Chlorine. Sulphuric acid. Lime. Magnesia. All salts. Coefficient. 1. Lieutenant Skibsted, 1844. J 19-287 2-254 0-488 2-136 34-831 1-806 W. long. 3° 15', N. lat. 60° 25' { (11-68) (2-51) (11-07) 2. Captain Paludan, May 8, 1845. j W. long. 5° 19', N. lat. 60° 94' | 19-485 2-289 0-568 2-146 35-223 1-808 (11-75) (2-92) (11-01) 3. Captain Gram, May 5, 1845. J W. long. 7° 52', N. lat. 59° 50' 1 19-671 2-342 0-592 2-210 35-576 1-809 (11-91) (3-01) (11-23) 4. Captain Gram, 1845. j W. long. 7° 20', N. lat. 60° 20' 1 19-619 2-296 0-587 1-820 35-387 1-814 (11-70) (2-99) (9-28) 6. Captain Gram, May 7, 1845. J W. long. 14° 7'» N. lat. 60° 9' 1 19-620 2-306 0-581 2-189 35-493 1-809 (11-75) (2-96) (11-16) 6. Captain Gram, 1845. W. long. 16° 32', N. lat. 61° 1 19-558 2-285 0-581 2-330 35-281 1-804 (11-68) (2-97) (11-91) 7. Taken by an Unknown. J 20-185 2-336 0-699 2-241 36-480 1-807 W. long. 20£°, N. lat. 55|° 1 (H-59) (3-31) (11-10) 8. Captain Gram, May 10, 1845. J W. long. 20° 30', N. lat. 59° 58' 1 19-560 2-294 0-584 2-214 35-291 1-804 (11-73) (2-99) (11-32) 9- Captain Paludan, Mav 10, 1845. J 19-466 2-343 0-576 2-117 35-348 1-816 W. long. 23° 3', N. lat. 62° 15' ' 1 (12-04) (2-96) (10-88) 10. Captain Gram, May 15, 1845. J W. long. 26° 23', N. lat. 59° 50' 1 19-545 2-330 0-583 2-190 35-397 1-811 (11-92) (2-98) (11-20) 11. Captain Gram. j 19-579 2-277 0-570 2-196 35-399 1-808 W. long. 26° 37', N. lat. 60° 30’ 1 (11-63) (2-91) (11-22) 12. Captain Gram, September 1, 1845. j W. long. 36°, N. lat. 58° 58' \ 19-386 2-365 0-578 2-135 34-990 1-805 (12-20) (2-98) (11-01) Mean j 19-581 2-310 0-528 2-160 35-391 1-808 (11-80) (2-97) (11-03) Maximum j 20-185 2-385 (12-50) 0-669 (3-31) 2-330 (11-98) 36-480 1-811 Minimum j 19-287 2-254 (11-59) 0-488 (2-51) 1-820 (9-28) 34-831 1-804 OF SEA-WATEE IN THE DIFFEEENT PAETS OF THE OCEAN. 249 Fourth Kegion. — The East Greenland Current. Chlorine. Sulphuric acid. Sulphuric acid. Chlorine = 100. All salts. Coefficient 1-813. 1. Colonel Schaffner, September 2, I860. 1 Faxefjord, Iceland. W. long. 24° 1' 30", N. lat. 64° 16' 11' J 2. Colonel Schaffner, September 3,1860. ] W. long. 26° 24', N. lat. 64° 30' J 3. Colonel Schaffner, September 6, I860. ] W. long. 27° 8', N. lat. 64° 15' J 4. Colonel Schaffner, September 8, I860. ] W. long. 29° 36', N. lat. 63° 25' J 5. Colonel Schaffner, September 9, I860. ] W. long. 27° 34' 35", N. lat. 63° 34' 30" J 6. Colonel Schaffner, September 9, I860. 1 W. long. 33° 22' 45", N. lat. 63° 24' i 7. Colonel Schaffner, September 10, I860, i W. long. 37° 31' 30", N. lat. 62° 47' 8. Colonel Schaffner, September 11, I860. W. long. 38° 18', N. lat. 62° 16' 34" 9. Colonel Schaffner, September 13, I860, j In ice pack. W. long. 41° 45', N. lat. 60° 48' 40"* j 10. Colonel Schaffner, September 14, I860. W. long. 40° 56', N. lat. 59° 49' 11. Captain Gram, May 18, 1845. W. long. 33° 32', N. lat. 60° 23'* 12. Captain Gram, May 20, 1845. W. long. 39° 4', N. lat. 59° 26'* 13. Captain Gram, May 22, 1845. W. long. 46° 1', N. lat. 57° 57'* 19*517 19-616 19-579 19-518 19-545 19442 19-491 19-469 16-831 19-136 19-512 19-306 19-365 2-360 2-420 2-382 2-293 2-300 2-341 2-291 2-309 1- 995 2- 252 2-385 2-310 2-305 12-09 12-34 12-17 11-75 11- 77 12- 04 11-75 11-86 11-85 11- 75 12- 22 11-97 11-90 35-385 35-563 35-495 35-386 35-435 35-248 35-337 35-297 30-515 34- 694 35- 390 35-067 35-038 Mean 19*458 2-329 11-97 35-278 Maximum 19-616 2-420 12-34 35-563 Minimum 19-136 2-252 11-75 34-694 * This observation in the pack is not used for determining the means. Observations 11, 12, 13 are complete analyses with a coefficient 1-814, 1-816, and 1-809 ; mean 1-813. This mean coefficient is used for calculating the quantity of all salts in Colonel Schafkstek’s samples, where there was not enough for complete analysis. 250 PROFESSOR FORCHHAMMER ON THE COMPOSITION Fifth Region. — Davis Straits and Baffin’s Bay. Chlorine. Sulphuric acid. Lime. Magnesia. All salts. Coefficient. 1. Captain Gram, May 26, 1845. N. lat. 60° 32', W. long. 53° 11' 19*010 2*283 0*550 2*115 34*414 1*810 (12*01) (2*89) (11*13) 2. Captain Gram, June 2, 1845. N. lat. 62° 8', close to the island ved Fre- derickshaab 18*317 2*161 (11*80) 0*551 (301) 2*036 (11*12) 33*109 1*808 3. Captain Gram, June 12, 1845. Close to the Killiksut Islands near Nanarsuit (about N. lat. 60°) 18*386 2*144 (11*66) 0*546 (2*97) 2*018 (10*98) 33*190 1*806 4. Dr. Kaiser, September 5, 1845. 18*251 2*131 0*455 2*140 32*926 1-804 N. lat. 64° 41', Davis Straits j (11*68) 2*187 (12*27) (2*49) 0*496 (2*78) (11*73) 2*005 (11*25) 5. Dr. Kaiser, September 4, 1845. N. lat. 66° 58', about 30 English sea-miles from Greenland 17*818 32*304 1*813 6. Dr. Kaiser, August 30, 1845. N. lat. 68° 43', W. long. 52° 45', harbour of 18*325 2*238 (12*21) 0*495 (2*70) 2*080 (11*35) 33*187 1*811 S7. Dr. Kaiser, September 3, 1845. 8 sea-miles from Godhavn, Disco (about N. lat. 69° 50 ) 18*401 2*255 (12*25) 0*455 (2*47) 2*008 (10*91) 33*446 1*818 8. Dr. Rink, July 5, 1849. N. lat. 69° 45', 24 English sea-miles W. from Disco 18*524 2*268 (12*24) 0*530 (2*86) 2*109 (11*39) 33-595 1*814 Mean - r 18*379 2*208 0*510 2*064 32*281 1*811 (12*01) (2*77) (11*23) Maximum 19*010 17*818 12*27 11*66 3*01 11*73 10*91 34*414 1*818 Minimum 2*47 32*304 1*804 Sixth Region. — The North Sea. Chlorine. Sulphuric acid. Lime. Magnesia. All salts. Coefficient. 1. 1844. 1 18*772 2*312 0*488 2-128 34*302 1*827 Between the Orkneys and Stavanger, in Norway I i (12*31) (2*59) (11*33) 2. 1844. 1 18-278 2*223 0-455 2*192 33*294 1*822 S.W. of Egernsund. Norway J b (12*14) (2-49) (11*98) 3. Captain vonDockum, September 16, 1845.^ In the Hooft in the deep channel near the Galloppers 19*282 2-351 (12-19) 0*560 (2*90) 2*166 (11*23) 35*041 1-817 4 Captain von Dockum, September 18, 1845. About forty-five English sea-miles W. from the lighthouse of Hanstholm i r 17*127 2-079 (12*09) 0*548 (3*19) 1*929 (11*26) 31*095 1*815 5. Captain von Dockum, September 18, 1845. ] L 18*131 2-141 0*565 2*037 32*674 | 1*802 Skagerack, between Hirtshals and the Skau. J 1“ (11*81) (3-12) (11*23) 6. Back, S. Heligoland. Analysis from Erdmanns Journal, Bd. 34, P- 185 J i 16*830 2-008 (11*93) 0*485 (2*88) 1*866 (11-09) 30*530 1*814 Mean r 18-070 2*185 0*517 2*053 32*823 1*816 i (12*09) (2*86) (11*25) Maximum i ! 19*295 2-351 (12*31) 0*565 (3-19) 2*192 (11*98) 35*041 1*827 Minimum [ 17*127 2-008 (11*77) 0-455 (2*49) 1*866 (11*09) 30*530 1*808 OF SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 251 Seventh Region. — The Kattegat and the Sound. Chlorine. Sulphuric acid. Lime. Magnesia. All salts. Coefficient. 1845, April. North of Kullen. Current f 6-227 0-776 0-195 0-712 11-341 1-821 from the South j (12-46) (3-13) (11-43) 1845, April. North of the island of Anhalt, j 8-429 1-028 0-257 Current from the South \ (12-09) (3-02) 1845, June. North of Kullen. Current from j 9*376 1-178 0-393 0-986 17-254 1-840 the North j (12-57) (4-19) (10-51) 1845, June. North of Anhalt. Current from J 9-632 1099 0-298 1-059 17*355 1-802 (11-41) 1 3-10) (10-99) 1844. Captain Skibsted. Kattegat j 10-077 1-208 (11-54) 0-319 (2-78) 1-253 (11-31) 19-940 1-801 Elsinore. Mean of 134 observations between ] April 17 and September 11, 1846 j 12-827 23-243 1846, October 4. Copenhagen. Current J 5-966 0-750 0-196 0-620 10-869 1-822 from the South \ (12-57) (3-28) (10-39) Copenhagen. Mean of 7 observations between 1 Q**7 A O 1 K.Q/I 1 March 3 and April 21, 1852 J O / Z lO 1 Sandefjord, on the south-east coast of Norway, f 7-740 0-875 0-266 0-818 13-996 1-808 Analyzed by Professor Strecker [ (11-30) (3-44) (10-59) Mean j 8-780 0-998 0-275 0-908 16-230 1-814 (11-94) (3-29) (10-86) Maximum j 12-827 1-2/8 0-393 1-253 23-243 1-840 (12-57) (4-19) (11-43) Minimum j 5-966 0-750 (11-30) 0-195 (2-78) 0-620 (10-39) 10-869 1-801 Eighth Region. — The Baltic. Chlorine. Sulphuric acid. Lime. Potash. Magnesia. All salts. Coeffi- cient. 1. Bellona. N. lat. 58° 27) E. long. 20° ... | 3-863 0-489 (12-65) 0-136 (3-52) 0-066 (1*71) 0-447 (11*57) 7*061 1-828 2. Bellona. Between Hammersh uus, on thelsland f 4-079 0-514 0-126 0-094 0-436 7-481 1-834 of Bornholm, and Sandhammer in Sweden \ (12-60) (3-09) (1-99) (10-69) 3. Bellona. Between Oland and Gothland... j 3-991 0-527 (13-19) 0-137 (3-43) 0-075 (1-88) 0-480 (12-03) 7*319 1-834 4. Bellona. Entrance of the Bay of Finnland | 3-833 0-472 (12-33) 0-145 (3-78) 0-068 (1*77) 0-508 (13-25) 6-933 1-809 5. Bellona. Bay of Finnland, between Hog- f 2-596 0-346 0-092 0-044 0-299 4-763 1-835 land and Tysters \ (13-31) (3-54) (1*69) (11-52) 6. Bellona. Bay of Finnland, between Nervoe J 1-931 0-239 0-076 0-047 0-226 3-552 1-839 and Seskjeld I (12-38) (3-91) (2-43) (11-70) 7. Bellona. Bay of Finnland, W. from Kron- j 0-331 0-040 0-019 0-023 0-046 0-738 2-230 stadt \ 8. Bellona. Bay of Finnland. Merchant- f 0-294 (11-95) 0-044 (5-81) 0-022 (0-69) 0-006 (13-90) 0-046 0-610 2-075 harbour of Kronstadt \ (14-97) (7*49) (0-21) (15-65) 1-836 9. Svartklubben, to the North of Stockholm... j 3-265 0-407 (12-50) 0-132 (4-05) 0-056 (1-72) 0-403 (12-38) 5-919 Mean | 2-687 0-342 0-098 0-053 0-321 4-931 1-835 (100-00) (12-73) (3-64) (1-97) (11*94) Maximum | 4-079 0-527 0-145 0-094 0-508 7-481 2-230 (100-00) (14-97) (7-49) (2-43) (15-65) 0-610 Minimum | 0-294 0-040 0-019 0-006 0-046 1-809 (100-00) (11*95) (3-09) (0-21) (10-69) 2 M MDCCCLXV. 252 PROFESSOR FORCHHAMMER ON THE COMPOSITION Ninth Region. — The Mediterranean. Chlorine. Sulphuric acid. Lime. Potash. Magnesia. All salts. Coeffi- cient. 1. Heimdal, Captain Schulz, Sept. 28, I860. f 20-160 2-302 0-610 0-415 2-134 36-391 1-805 Straits of Gibraltar (11-42) (3-03) (2-06) (10-59) 2. Heimdal, Captain Schulz, Sept. 29, I860. N. lat. 36° 9'. W. Ion*?. 4° 2' 20-235 2-583 (12-8) 0-613 (3-03) 0-345 (1-70) 2-305 (11-39) 37-014 1-829 3. Heimdal, Captain Schulz, Oct. 8, I860. N. lat. 40° 28', E. long. 1° 48'. Between the Balearic island and the Spanish coast > 21-085 2-444 (11-59) 0*641 (3-04) 0-474 (2-25) 2-402 (11-39) 38-058 1-805 4. Heimdal, Captain Schulz, Oct. 10, I860. 21-056 2-542 0-635 0-336 2-356 38-321 1-819 N. lat. 41° 12', E. long. 2° 23' (12-07) (3-02) (1-60) (11-19) 5. Heimdal, Captain Schulz, Oct. 12, I860. N. lat. 42° 25', E. long. 6° O'. Between Bar- celona and Corsica > 21-217 Q to T* ^ Cn Or CO OO 0-629 (2-96) 0-428 (2-03) 2-379 (11-21) 38-290 1-805 6. Heimdal, Captain Schulz, Oct. 20, 1860/) N. lat. 40° 25', E. long. 11° 43'. Between Sar- dinia and Naples J > 21-139 2-652 (12-55) 0-660 (3-12) 0-492 (2-33) 2-322 (10-98) 38-654 1-828 7. Mr. Ennis, 1837. Malta -j f 20-497 2-471 (12-06) 0-640 (3-12) 0-174 2-074 (10-12) 37-177 1-814 8. Heimdal, Captain Schulz, Nov. 13, 1860/) N. lat. 36° 10', E. long. 16° 10'. To the East of Malta j >■ 21-297 2-514 (11-8) 0-686 (3*22) 0-417 (1-96) 2-403 (11-28) 38-541 1-809 9- Heimdal, Captain Schulz, Oct. 23, 1860/) 21-180 2-390 0-597 0-304 2-392 38-013 1-795 N. lat. 37° 20', E. long. 16° 32'. Between Malta >- (11-29) (2-82) (1-41) (11-29) and Greece J Sulphuretted hydrogen. 10. Heimdal, Captain Schulz, Oct. 28, I860, i N.lat.33°34', E. long. 24° 34'. Between Candia< and the coast of Africa 1 r 21-718 2-517 (11-60) 0-677 (3-12) 0-392 (1-80) 2-447 1(11*27) 39-257 1-808 11. The Mediterranean; exact place unknown. | 20-900 2-433 0-621 0-32 2-223 37*655 Calculated after an analysis in Yiolette and<^ Brom. 432 (11-64) (2-97) :(i0-64) Archambault’s ‘Analyses chimiques’ 1 21-332 Mean \ f 20-889 2-470 0-642 0-372 2-277 37-936 1-815 l (11-82) (3-08) (1-78) (10-90) Maximum i. r 21-718 2-652 0-622 0-492 2-447 (11-39) 39-257 1-829 L (12-59) (3-22) (2-33) 36-391 Minimum < r 20-160 2-302 0-597 (2-82) 0-174 2-074 (10-12) 1-805 i (11*42) Rem auks. — No. 9 is not taken in the calculation of the mean coefficient, on account of the decomposition of the sulphuric acid, which always lowers the coefficient ; the small quantity of lime in No. 9 depends probably upon the same decomposition, the sulphate of lime being changed into sulphuret of calcium, which again, by carbonic acid and water, is decomposed into sulphuretted hydrogen and carbonate of lime, which is precipitated. OF SEA-WATER IN THE DIFEERENT PARTS OF THE OCEAN. 253 Tenth Region, A. — The Black Sea and the Sea of Assou. Chlorine. Sulphuric acid. Lime. Magnesia. All salts. Coefficient. 1. Water from the Black Sea, 50 English f 9-963 1-167 0-420 1-259 18-146 1-821 (100-00) 9-869 (100-00) (11-71) 1-032 (10-46) (4-22) 0-182 (1-84) (12-64) 1-126 (11-41) 2. Water from the Black Sea. Gobel j 17*666 1*790 3. Water from the Sea of Assou. Gobel ... j 6-569 (100-00) 0-674 (10-26) 0-128 (l'9fi) 0-672 (10-23) 11*880 1*808 Mean j 8-800 0-958 0-243 1-019 15-897 1*806 (100-00) (10-89) (2-76) (11-58) Maximum ^ 9-963 1-167 0-420 1-259 18*146 1*821 i(100-00) (11-71) (4-22) (12-64) Minimum | 6-569 0-674 0-128 0-672 11*880 1*790 (100-00) (10-26) (1-84) (10-23) B. — From the Caspian Sea. 1 / 2-731 (100-00) 1-106 (40-50) 0-268 0-700 (25-63) 6*236 2-283 (9-81) 2. Baer. From Tuik Karaga. Analysis by J 5-741 2-316 0-373 1-240 14-000 2-439 Mehner, Baer (Caspische Studien) [ ,(100-00) (40-34) (6-50) (21-60) 3. Baer. Bay of Kaidak or Karassi. Ana- J 23-976 10-112 1-432 4-657 56-814 2-370 lysis by Mehner, Baer (Caspische Studien) [ (100-00) (42-11) (5-91) (19-42) 4. Baer. Bay of Mertuyi Kultak. Analysis j 12-504 5-613 1-733 2*096 31-000 2-480 by Mehner, Baer (Caspische Studien) ) (100-00) (44-89) (13-86) (16-76) 5. Baer. Bay of Krasnowood. Analysis by f 6-182 3-494 0-760 1-471 16-410 2-654 Mehner, Baer (Caspische Studien) (_ (100-00) (56-52) (12-29) (23-80) Mean | 10-227 4-528 0-913 2-033 24-892 2*434 (44-27) (8-93) (19*88) Maximum | 23-976 10-112 1-733 4-657 56-814 2-654 (56-52) (13-86) (25-63) 6-236 Minimum j 2-731 1-106 0-268 0-700 2-283 (40-34) (5-91) (16-76) 2 M o 254 PROFESSOR FORCHHAMMER ON THE COMPOSITION Eleventh Region. — The Atlantic, between the Equator and 30° S. latitude. Chlorine. Sulphuric acid. Lime. Magnesia. All salts. Coefficient. \ 20*003 2-312 (11*56) 0-596 (2-98) 2*235 (11-17) 36*084 1-804 [ 20*491 2*465 (12-03; 0*598 (2*92) 2*218 (10*82) 37*155 1*813 j- 20*397 37*001 1-814 f 20-115 2-428 (12*07) 0-580 (2-88) 2*233 (11*10) 36-442 1-812 | 19*831 2-393 (12-07) 0-596 (3-01) 2-254 (11*37) 35-930 1-812 | 20-049 2-379 (11-87) 0-563 (2*81) 2*253 (11*24) 36*261 1-809 | 20*166 2-537 (12-58) 0*585 (2-90) 2-022 (10-03) 36-997 1*835 | 20-150 2-419 (12-03) 0*586 (2*91) 2-203 (10*96) 36*553 1-814 | 20-491 2*537 (12*58) 0-598 (3*01) 2*254 (11*37) 37*155 1*835 | 19*831 2-312 (11-56) 0*563 (2*81) 2-022 (10-03) 35*930 1-804 1. Valkyrie, February 11, 1848. S. lat. 3° 19', W. long. 25° 34' 2. Valkyrie, February 1 6, 1848. S. lat. 17° 9', W. long. 33° 29* 3. Sir James Ross. S. lat. 22° 37', W. long. 34° 57' 4. Dr. Fischer, 1846. S. lat. 23°' 5', W. long. 37° 15' 5. Dr. Fischer, 1846. S. lat. 28° 15', W. long. 38° 26' 6. Captain Prevost, February 4, 1857- S. lat. 29° 14', W. long. 47° 37' 7. Valkyrie, March 15, 1848. S. lat. 29° 131', w. long. 38° 26' Mean Maximum Minimum Twelfth Region. — The Atlantic between S. lat. 30° and the southernmost points of America and Africa. Chlorine Sulphuric Lime MsguGsi&a All salts. Coefficient. acid. Dr. Fischer, 1846. 1 19*809 2-329 0*583 2*234 35-807 1*808 S. lat. 30° 45', W. long. 42° 30' J (11*76) 2*253 (2*94) 0-582 (11*28) 2*156 Dr. Fischer, 1846. 1 19*237 34-774 1*808 S. lat. 40° 3(y, W. long. 40° 50' ( (11*71) 2*194 (3-03) 0-557 (11*21) 2*135 Dr. Fischer, 1846. I 19*154 34*526 1-803 i S. lat. 45° 20', W. long. 48° 40' f (11-45) 2*245 (2-91) 0-518 (11-15) 2*190 Dr. Fischer, 1846. 1 18*909 34*151 1*806 S. lat. 50° 31', W. long. 52° 15' / (11*87) 2*451 (2*74) 0*541 (11*58) 2*091 Fregat Valkyrie, 1848. \ S. lat. 36° lli', W. long. 6° 39' / 19*431 35-065 1*805 (12*61) (2* 78) (10-76) Fregat Valkyrie, 1848. 19*713 2-404 0-553 2-156 35-907 1-821 S. lat. 37° 1 1 A', E- long. 12° 25^-' j (12*19) (2-81) (11-04) Mean j 19*376 2*313 0*556 2-160 35*038 1*809 (11*94) (2-87) (11-15) Maximum | 19*809 2*451 (12-61) 0*583 (3-03) 2*234 (11*58) 35*907 1*821 Minimum j 18-909 2-194 (11*45) 0*518 (2*74) 2-091 (10*76) 34*151 1*803 Captain Prevost*. J S. lat. 35° 46', W. long. 52° 57' i ' 17*721 1*615 (9*10) Sulphuretted 0-448 (2*49) 1-899 (iO-72) 34*489 1*946 hydrogen. * This sample has been left out in the calculation of the mean numbers because the quantity of sulphuric acid was greatly diminished by putrefaction. OF SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 255 Thirteenth Region. — The sea between Africa and the East Indian Islands. Chlorine. Sulphuric acid. Lime. Magnesia. All salts. Coefficient. 1. Galathea, September 24, 1845. 19753 2*361 0*600 2*207 35*802 1*812 S. lat. 31° 54', E. long. 72° 27' (11*98) (3*04) (11*17) 2. Galathea, October 1, 1845. 19-498 2*341 0*569 2*105 35*381 1*814 S. lat. 14° 14', E. long. 83° 38' (12*01) (2*92) (10*80) 3. Galathea, October 6, 1845. 19*381 2*334 0*591 2*005 35*169 1*815 N. lat. 0° 19', E. long. 84° 51' , (12*04) (3*05) (10*35) 4. Galathea, October 28, 1845. 14*289 1*724 0*446 1*699 25*879 1-818 N. lat. 17° 20', E. long. 88° 12' . (12*06) (3*12) (11-89) 32*365 5. Galathea, December 31, 1845. 17-838 2*131 0*543 1*944 1*814 N. lat. 18° 17', E. long. 90° 13' J (11-94) (3*04) (10*90) 6. Galathea. ] 18*246 2*156 0*547 1-997 33*036 1-817 | Nancovri on the Nicobar Islands J > (11*81) (3*00) (10*94) 7. Galathea, May 13, 1846. ] 17*970 2*132 0*547 1-979 32*766 1*823 S. lat. 4° 54', E. long. 107° 15', Sea of Java... J ► (11*88) (3*07) (11*01) 8. Valkyrie, April 14, 1848. 1 S. lat. 38° 52', E. long. 30° 31' J 19*413 2*470 0*543 2*134 35*583 1-833 > (12*72) (2*80) (10*99) 9. Valkyrie, April 19, 1848. 1 S. lat. 36° 59', E. long. 47° 23' J 19-710 2*349 0*572 2*193 35*701 1*816 f (11*92) (2*90) (11*13) 10. Valkyrie, April 26, 1848. ] 19*548 2*380 0*588 2*101 35*415 1*817 S. lat. 35° 2\ E. long. 62° 52' J (12*17) (3*01) (10-75J 11. Valkyrie, May 14, 1848. S. lat. 1° 56', E. long. 81° 5' J 19*626 2*330 0*567 2*207 35*512 1*809 (11-87) (2*89) (11*24) 12. Valkyrie, May 21, 1848. 1 N. lat. 12° 3', E. long. 80° 8' J L 18*763 2*250 0*567 2*086 33*809 1*802 r (11-99) (3*02) (11*12) Mean ■ r 18*670 2*247 0*557 2*055 33*868 1*814 l (12*04) (2*98) (11*01) Maximum < r 19*753 2*470 (12*72) 0*600 2*207 35*802 1*833 i (3*12) (11-89) Minimum - f 14*289 1*724 (11*81) 0*446 (2*80) 1*699 (10*35) 25*879 1*802 Fourteenth Region. — The sea between the S.E. shore of Asia, the East Indian and the Aleutic Islands. 1 Chlorine. Sulphuric acid. Lime. Magnesia. All salts. Coefficient. 1. Galathea, May 18, 1846. 1 The Chinese Sea. > S. lat. 0° 33', E. long. 107° 22' J 17*757 2*104 (11*85) 0*516 (2*90) 1*958 (11*03) 32*370 1*823 2. Galathea. 1 18*486 2*258 0*572 2*067 33*680 1-822 N. lat. 4° 30', E. long. 107° 16' / (12-21) (3-03) (11*19) 3. Galathea. ) 17-923 2-160 0*533 1*961 32*533 1-815 N. lat. 25° 40', E. long. 120° 50' j (12*05) (2*97) (10*94) 4. Galathea. 1 18*564 2*209 0*552 2*022 33*580 1*809 N. lat. 30° 56', E. long. 127° 30' J (II 90) (2*97) (10*89) 5. Galathea. 18*847 2*257 0*575 2*089 34*153 1*812 N. lat. 30° 56', E. long. 139° 39' / (11-98) (3*05) (10*08) 6. Galathea. 18*873 2*247 0-613 2*046 34*234 1*814 N. lat. 38° 31', E. long. 148° 27' / (11-90) (3-25) (10*84) 7- Galathea. 1 18*788 2-213 0*580 2*048 33-990 1*809 N. lat. 38° 35', E. long. 148° 44' J (11-78) (3*09) (10*90) Mean | 18*462 2*207 0*563 2*027 33-506 1*815 (11*95) (3*05) (10*93) 34-234 1*823 Maximum j 18*873 2*258 0*613 2*089 (12*05) (3*25) (11*19) 32-370 1*809 Minimum j 17-757 2*104 0*516 1*958 (11-78) (2*90) (10*84) 1 256 PEOFESSOE FOECHHAMMEE ON THE COMPOSITION Fifteenth Region. — The sea between the Aleutic Islands and the Society Islands. Chlorine. Sulphuric acid. Lime. Magnesia. All salts. Coefficient. 1. Galathea, September 11, 1846. N. lat. 38° 26', E. long. 172° 11’ 2. Galathea, September 17, 1846. N. lat. 38° 42', W. long. 176° 53' 3. Galathea, September 21, 1846. N. lat. 37° 3', W. long. 160° 5' 1 4. Galathea, September 24, 1846. | N. lat. 32° 8', W. long. 150° 17' 1 5. Galathea, October 5, 1846. Off Honolulu, Sandwich Islands J 6. Galashea. Off Matuiti J 7. Galathea. Off Borabora J f 18- 908 19- 006 19*244 19-824 19-625 19*943 19*917 2-195 (11-61) 2-220 (11-68) 2-243 (11-65) 2-316 (11-68) 2-283 (11-63) 2-326 (11-66) 2-347 (11-78) 0-545 (2-88) 0-535 (2-82) 0-555 (2-88) 0-549 (2-83) 0-580 (2-95) 0-610 (3-06) 0-623 (3-13) 2-066 (10-93) 2-078 (10-93) 2-110 (10-69) 2-209 (11-14) 2-152 (10-96) 2-224 • (11-15) 2-252 (11-31) 34-157 34-274 34- 715 35- 877 35- 395 36- 051 36-061 1-806 1-803 1-804 1-809 1-804 1-808 1-805 Mean ■ Maximum • Minimum • I 19*495 19-943 18-908 2-276 (11*67) 0-347 (11-78) 2-195 (11-61) 0-571 (2-93) 0-623 (3-13) 0-535 (2-82) 2-156 (11-06) 2-252 (11-31) 2-066 (10-69) 35- 219 36- 061 34-157 1-807 1-809 1-803 Sixteenth Region. — The Patagonian current of cold Water. Chlorine. Sulphuric acid. Lime. Magnesia. All salts. Coefficient. 1. Dr. Fischer. 1 18-769 2-133 0*507 2-116 33-788 1-800 S. lat. 57° 27', W. long. 66° 57' J (11*37) (2-70) (11-27) 2. Dr. Fischer. 18-796 2-210 0*546 2-048 33-969 1-807 S. lat. 52° 38', W. long. 76° 20' J (11-76) 2-238 (2*91) 0-560 (10-90) 2-036 3. Dr. Fischer. 18-760 33-980 1-811 S. lat. 47° 40', W. long. 78° 25' J (11*89) 2-226 (2-98) 0-563 (10-85) 2-100 4. Dr. Fischer. | 18-768 23-932 1-808 S. lat. 38° 10', W. long. 78° 14' j (11-86) 2-224 (3-00) 0-537 (11*19) 2-079 5. Dr. Fischer. j 18-754 33-976 1-812 S. lat. 33° 54', W. long. 74° 23’ 1 (11-86) 2-257 (2-86) 0-531 (11*09) 2-076 6. Captain Prevost. | 18-976 34-152 1-800 S. lat. 35° 22', W. long. 73° 49' J (11*89) (2-80) (10-94) Mean - 18-804 2*215 0-541 2-076 33-966 1-806 (11*78) (2-88) (11-04) Maximum < 18-976 2-257 (11*93) 0-563 (3-00) 2-116 (11-27) 34-152 1-812 Minimum j 18-754 2-133 (11*37) 0-507 (2*70) 2-036 (10-85) 33-788 1-800 Seventeenth Region. — The South Polar Region. Chlorine. 1 Sulphuric 1 acid. Lime. Magnesia. All salts. Coefficient. 1. Sir James Eoss, January 30, 1841. 1 S. lat. 77° 32', E. long. 188° 21'. Near the V ice barrier J 2. Sir James Eoss, February 25, 1841. | S. lat. 74° 15', E. long. 167° O'. Near Caulmans > i Island ; J 3. Sir James Ross, March 6, 1841. 1 | S. lat. 65° 57', E. long. 164° 34' / 15-748 8-477 20-601 1-834 (11-65) 1- 053 (12-42) 2- 586 (12-55) 0-498 (3-16) 0-251 (2-96) 0-623 (3-02) 1- 731 (10-99) •887 (10-46) 2- 231 (10-83) 28-565 15-776 37-513 1-814 1-861 1-821 Mean* j 14-942 1-824 (12-21) 4-57 (3-06) 1-616 (10-81) 27-285 1-826 * These mean numbers are uncertain, the number of observations being very limited, and so very different. I should think that the first observation will he a fair sample of South Polar water, and have preferred it to the mean of the three observations in the calculation of the means of the whole ocean. OF SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 257 Comparison of the Means of all the Regions of the Ocean (German Ocean, Kattegat, Baltic, Mediterranean, and Black Sea excepted). Chlorine. Sulphuric acid. Lime. Magnesia. All salts. Coefficient. I. The Atlantic between the equator and N. lat. 30° J 20-034 2-348 (11-75) 2-389 (12-05) 0-595 (2-98) 0-607 (3-07) 2-220 (11-11) 2-201 (11-10) 36-253 1-810 II. The Atlantic between N. lat. 30° and a line front the north point of Scotland to New- foundland > 19-828 35-932 1-812 III. The northernmost part of the Atlantic... - IV. The East Greenland Current ' 19*581 19-458 2-310 (11-80) 2-329 (11-97) 0-528 (2-97) 2-160 (11-03) 35-391 35-278 1-808 1-813 V. Davis Straits and Baffin’s Bay < ' 18-379 2-208 (12-01) 0-510 (2-77) 2*064 (11-23) 33-281 1-811 XI. The Atlantic between the equator and ] 20-150 2-419 0-586 2-203 36-553 1-814 S. lat. 30° J f (12-03) (2-91) (10-96) XII. The Atlantic between S. lat. 30° and a~l line from Cape Horn to the Cape of Good Hope J > 19-376 2-313 (11-94) 0-556 (2-87) 2-160 (11-15) 35-038 1-809 XIII. The Ocean between Africa, Borneo, ] 18-670 2-247 0-557 2-055 33-868 1-814 and Malacca J (12-04) (2-98) (11*01) XIV. The Ocean between the S.E. coast of 1 Asia, the East Indian, and the Aleutic Islands J 18-462 2-207 (11-95) 0-563 (3-05) 2-027 (11*98) 33-506 1-815 XV. The Ocean between the Aleutic and the] 19*495 2-276 0-571 2-156 35-219 1-807 Society Islands J > (11-67) (2-93) (11-06) XVI. The Patagonian cold-water current ... < r 18-804 2-215 (11-78) 0-541 (2-88) 2-076 (11-04) 33-966 1-806 XVII. The South Polar Sea < j 15-748 1-834 (11-65) 0-498 (3-16) 1-731 (10-99) 28-565 1-814 i Mean 18-999 2-258 0-556 2-096 34-404 1-811 Mean proportion of the most"! i important substances in sea- water, chlorine=l00 J 11-88 2-93 11-03 f Enuivalents 429 45 16 82 Comparison between the quantity of Salt in the water of the surface and the depth of the Sea, between Africa and the East Indies. Depth. Chlorine. Sulphuric acid. Lime. Magnesia. All salts. Coefficient. r Surface 19*626 2-330 0-567 2-207 35-512 1-809 Valkyrie, May 14, 1848. J 1 (11*87) (2-89) (11-25) S. lat. 1° 56', E. long. 81° 5' 1 215 feet 19-606 2-451 0-558 2-147 35-819 1-827 L (12-50) (2-85) (10-75) 1 r Surface 19*548 2-349 0-588 2-101 35-415 1-817 Valkyrie, April 28, 1848. J I (12-02) (3-01) (10-75) S. lat. 35° 2', E. long. 62° 52' i 300 feet 19-786 2-380 0-572 2-218 35-671 1-803 L (1 203) (2-89) (11-21) 258 PROFESSOR FORCHHAMMER ON THE COMPOSITION Comparison between the quantity of Salt in the water of the surface and the depth of the Sea, between the East Indian and Aleutic Islands. Depth. Chlorine. Sulphuric acid. Lime. Magnesia. All salts. Coefficient. I r Surface 18-873 2-178 0-615 2-046 34-052 1-804 Galathea, August 27, 1846. N. lat. 38° 31', E. long. 148° 27' . J (11-54) (3-26) (10-84) ..1 300 feet 19-075 2-249 0-543 2-132 34-426 1-805 1 L (11-79) (2-85) (11-18) I r Surface 18-846 2-258 0-572 2-067 34-132 1-811 Galathea, May 23, 1846. •• (11*98) (3-04) (10-97) N. lat. 4° 30', E. long. 1073 16' . i 360 feet 18-885 2-195 0-567 2-147 34-033 1-802 1 L (11-62) (3-00) (11-38) Comparison between the quantity of Salt in Sea-water from different depths in the South Atlantic Ocean. Samples taken by Sir James Boss. Depth. Chlorine. Sulphuric acid. Lime. Magnesia. All salts. Coefficient. 900 feet 19-763 2-584 0*657 2-249 36-165 1-830 (13-07) (3-32) (11-38) 36-358 1800 feet 19*991 2-456 0-566 2-191 1-819 Sir James Ross, June 10, 1844. J (12-29) (2-83) (10-96) S. lat. 0° 15', W. long. 25° 54' | 4500 feet 19*786 2-398 0-554 2-320 35-889 1-814 (12-12) (2-80) (11*73) 36-313 5400 feet 20*007 2-418 0-574 2*187 1-815 (12-09) (2*87) (10-93) Sir James Ross, June 2, 1 843. T S. lat. 14° 22', W. long. 22° 35' / 3600 feet 19*743 Sir James Ross, June 4, 1843, 1 S. lat. 15° 23', W. long. 23° 40' / Sir James Ross, June 8, 1843. f S. lat. 21° 48', W. long. 31° 24' j 2700 feet 19*346 900 feet 19*604 Sir James Ross, June 9, 1843. I ! S. lat. 22° 24', W. long. 32° 53' J f 3600 feet 19-627 Surface 20-397 Sir James Ross, June 10, 1843. J S. lat. 22° 37', W. long. 34° 57' i 900 feet 1800 feet 2700 feet 20-323 23-189 20-331 l 3600 feet 20-405 Surface 20-166 2-537 0-585 2-022 36-997 1-835 Valkyrie, March 15, 1848. J (12-58) (2-90) (10-03) S. lat. 29° 15'-5, W. long. 38° 26' ..A 480 feet 19*736 2-448 0-573 2-023 36-227 1-835 (12-40) (2-90) (10-25) Sir James Ross, March 28, 1843. f '6300 feet 19*635 2-346 0-631 2-140 35-607 1-813 S. lat. 43° 10', Long. 14° 44'

1862. N. lat. 51° 9', W. long. 15° 59' ... >- Surface 19-690 2-285 0-577 0-433 Sp. gr. 1-0280. J Porcupine, July 3, 1862. 1 N. lat. 52° 9', W. long. 15° 10' ... V (11-60) (2-93) (2-20) Surface 19-706 2-381 0-570 0-367 Sp. gr. 1-0265. I Porcupine, July 3, 1862. 1 N. lat. 52° 9', W. long. 15° 10' ... 1 (12-08) (2-89) (1-86) 5100 feet 19-752 2-297 0-580 0-433 Sp. gr. 1-0280. 1 (11-73) (2-94) (2-19) Porcupine, Aug. 29, 1862. | N. lat. 51° 58', W. long. 12° 47' ... 1 2400 feet 19*666 2-323 0-611 0-364 Sp. gr. 1-0280. J (11-811 (3-11) (1-85) j Surface 19-645 2*339 0-583 0-335 Porcupine, August 28, 1862. ( (11*91) (29-7) (1-71) N. lat. 52° 40', W. long. 15° 58' ... f 10,500 feet 19-758 2-423 0-563 0-325 (12-26) (2-90) (1-64) Porcupine. N. lat. 53° If, W. long. 12° 55' ... 1 Sp. gr. 1-0280. Surface 19-651 2-352 0-557 0-374 1200 feet 19*424 (11-97) 2-405 (12-38) (2-83) 0-559 (2-83) (1-90) 0-351 (1-81) Porcupine, August 16, 1862. N. lat. 55° 32', W. long. 12° 11' ... 1 Sp. gr. 1-0255. Surface 9780 feet 19-616 19-686 2-359 (11-99) 2-330 0-545 (2-78) 0-599 0-325 (1-65) 0-323 (11-84) (3-04) (1-64) Mean of surface observations 19-662 2-342 0-566 0-367 (11-9.1) (2-88) (1-87) Mean of observations from the depth ... 19*677 2-357 0-583 0-374 (11-98) (2-96) (1-90) Water from the Red Sea, and from different depths in the Baltic. Depth. Chlorine. Sulphuric acid. Lime. Potash. Water from the Red Sea. | Procured by Mr. Polack of Alexandria 23-730 2-889 0-689 0-387 f (12-17) (2-90) (1-63) From WTady Rarandel, upon the Sanai 23-171 2-761 peninsula, taken by Mr. Neergaard ... (11-92) r Surface 3-256 0-407 0-132 0-056 (12-50) (4-05) (1*71) 108 feet 3-663 Baltic. 240 feet 3-881 Water from Svartklubleen, taken by 300 feet 3-912 Messrs. Widegreen and Nystrom | 510 feet 3-969 600 feet 3-958 0-565 0-137 0-058 (14-27) (3-46) (1-47) 720 feet 3-960 1 1 948 feet 3-977 OF SEA-WATER IN THE DIFFERENT PARTS OF THE OCEAN. 261 Sea between lat. N. 51° l'£ and 55° 32'; and long. W. 12° 6' and 15° 59'. Magnesia. Silica, &c. Chloride of Sulphate of Sulphate of Chloride of Chloride of All salts. Coefficient. sodium. magnesia. lime. potassium. magnesium. 2-211 (11-24) 0-110 27-977 2-376 1-353 0-700 3-212 35-728 1-816 2-211 (11-18) 0-100 28-056 2-279 1-483 0-603 3-344 35-865 1-814 2-235 (11-35) 0-074 27-735 2-213 1-402 0-686 3-438 35-548 1-805 2-226 (11-30) 0-105 28-005 2-373 1-385 0-581 3-305 35-754 1-814 2-179 (11-03) 0-071 28-119 2-298 1-409 0-685 3-206 35-788 1-812 2-175 (11-06) 0-071 27-914 2-193 1-487 0-575 3-330 35-570 1-809 2-128 (10-83) 0-071 28-139 2-279 1-418 0-531 3-145 35-583 1-811 2-209 (11-18) 0-078 28-188 2-451 1-369 0-517 3-203 35-806 1-812 2-145 (10-92) 0-113 28-119 2-355 1-354 0-592 3-131 35-664 1-815 2-183 (11-24) 0-104 27-740 2-432 1-359 0-555 3-158 35348 1-820 2-225 (11-34) 0-088 27-916 2-379 1-326 0-517 3-298 35-524 1-811 2-182 (11-08) 0-069 28-081 2-253 1-457 0-511 3-261 35-632 1-810 2-192 (11-15) 0-090 27-983 2-320 1-377 0-581 3-263 35-615 1-811 2-193 (11-14) 0-086 28-011 2-326 1-417 0-592 3-245 35-677 1-813 Water from the Red Sea, and from different depths in the Baltic. Magnesia. Silica, &c. Chloride of sodium. Sulphate of magnesia. Sulphate of lime. Chloride of potassium. Chloride of magnesium. All salts. Coefficient. 2-685 (11-31) 0-136 33-871 2-882 1-676 0-612 3-971 43-148 1-818 0-403 (12-38) 0-027 4-474 0-329 0-322 0-089 0-678 5-919 1-818 0-441 (11-14) 0-072 5-810 0-632 0-333 0-092 0-526 7-465 1-886 Water from the Mediterranean. — Comparison between water from the surface and from different depths. 262 ON THE COMPOSITION OE SEA-WATER. Silica, }&c. 1 All salts. Coefficient. I' 1 1 1-803 1-805 1-829 1-805 1-836 1-820 1-805 g 00 1-814 1-810 s 1-808 1-813 1-811 2 g t & 11 fill 11 i 37- 177 38- 541 CO ? n I S : S : ? £ i S CO 1 I 0-093 0-083 0-138 0-087 0-075 i 0 GO 1 1 1 ! » afsf 1 ill llsllfi gf : or ^2 : or ^or ^or ^ • dr^. if sfsf GTO&C if dr^ jf III ll Potash. ZtZt I hi linn i it Zt tr 5 eo" Sill hi man ii O IE III! fl It III II fl or ^dr ^ dr 2U®* O®* 0®* 0®* O®* O®* CJ®* O®* O®1 O®1 CJ®* C- ®* C-®* O®1 O®* CJ®* C- s.? « ? s ? Chlorine. isg'ggs.sss.ssggssss'gss; siSSSSS. S5SS§SSS««® 20- 845 21- 155 18-999 Depth. Surface. Surface. 540 feet Surface. Depth * Surface. Depth* Surface. Depth * Surface. 420 feet Surface. 300 feet Surface. Surface. 390 feet Surface *. 522 feet Surface. 522 feet 1. Straits of Gibraltar, procured by Mr. Ennis, Falmouth, f 1837 } 2. Straits of Gibraltar, taken by Captain Schulz, September 1 28, I860 1 3. Straits of Gibraltar, taken by Captain Schulz, September J 28, I860, from 540 feet depth 1 4, 5*. A little on the Mediterranean side of the Straits, N. lat. 7 36° 9', W. long. 4° 2', September, 29, I860; j 6, 7** Between the Balear island and the Spanish coast, N. lat.J i 40° 28', E. long. 1° 48', October 8, I860 1 > 8, 9*. Between the Balear island and the Spanish coast, N. lat.J 41° 12', E. long. 2° 23', October 10, I860 1 10, 11. About midway between Corsica and Barcelona, N. lat.J 49.° 95'. F. Innor. fi° ft'. fWnher 19 1 Sfift 1 12, 13. Between Sardinia and Naples, N. lat. 40° 25', E. long.) 11° 43'. fWnher 9ft. 1 8fift 1 14. Malta, procured by Mr. Ennis, 1837 / 15, 16. Somewhat to the east of Malta, N.lat.36° 10', E.long.J 1<1° lft' IS. ISfift 1 tij J w §‘ fe & A I » o i 11 ! 15 1 i| : |e 5 « ® ; ti 1 19, 20. Between Candia and the coast of Africa, N. lat. 33° 34', J I'. Inna. 94° 34'. OctnUor 98 1 8fift 1 r [ j ? ) i Mean of surface observations j Mean of observations of deep water j Mean of the surface of the ocean -j The depth in samples 5, 7, 9 is not exactly noticed, hut it must have heen between 300 and 540 feet. [ 263 } V. On the Magnetic Character of the Armour-plated Ships of the Royal Navy , and on the Effect on the Compass of particular arrangements of Iron in a Ship. By Frederick John Evans, Esq., Staff Commander R.N., F.R.S. , Superintendent of the Compass Department of Her Majesty's Navy; and Archibald Smith, Esq., M.A., F.R.S., late Fellow of Trinity College , Cambridge, Corresponding Member of the Scientific Committee of the Imperial Russian Navy. Received March 9, — Read March 16, 1865. The present paper may be considered as a sequel to a paper published in the Philo- sophical Transactions for 1860, page 337, under the title “ Reduction and Discussion of the Deviations of the Compass observed on board of all the Iron-built Ships, and a selec- tion of the Wood-built Steam-ships in Her Majesty’s Navy, and the Iron Steam-ship ‘ Great Eastern’; being a Report to the Hydrographer of the Admiralty. By F. J. Evans, Master R.N.” Like the former, the present paper is presented to the Royal Society, with the sanction of the Lords Commissioners of the Admiralty. In the brief interval which has elapsed since the publication of that paper, changes of the greatest importance have taken place in the construction of vessels of war, which have been accompanied by corresponding changes in the magnetic disturbance of their compasses. Not only has there been a great increase in the surface and mass of iron used in the construction of those parts of the ship in which iron was formerly used, but iron has been adopted for many purposes for which it was not then used, and much of the iron thus added far exceeds in thickness any that was formerly in use. Among the masses thus added we may specially mention iron masts and yards, armour-plating, and gun-turrets. These changes have materially affected the problem of the correction of the deviation of the compass. They have not only greatly increased those errors which were formerly taken into account, but they have given importance to errors and causes of error which it was formerly considered might be safely neglected. These changes led to, if they did not necessitate, a complete revision of the mathematical theory of the deviations of the compass, and of the practical methods of ascertaining and applying the deviation. This revision was undertaken by us at the request of the Admiralty, and the results are contained in the ‘ Admiralty Manual for ascertaining and applying the Deviations of the Compass caused by the Iron in a Ship,’ published by the order of the Lords Commissioners of the Admiralty. London: Potter, 1862. Second edition, 1863. It is gratifying to us to be able to state, as an indication that this work has been found mdccclxv. 2 o 264 STAFF COMMANDER EVANS AND MR. A. SMITH ON THE MAGNETIC useful by others engaged in the like investigations, that it has been already translated into Russian, French, and German. The methods of reduction previously in use, and which are those made use of in the paper already referred to, as well as in the valuable Reports of the Liverpool Compass Committee, are those deduced from the approximate formula for the deviation, S=A+B sin £'+C cos £'+D sin 2£'+E cos 2£', as given in the Supplement to the ‘ Practical Rules for ascertaining the Deviations of the Compass which are caused by the Ship’s Iron,’ published by the Admiralty in 1855. In connexion with this formula use was made of the invaluable graphic method known as Napier’s curve. At that time observations of horizontal and vertical force did not enter into the usual routine of observations made on board ship, although many very valuable observations of these forces had been made by the Liverpool Compass Committee ; and no formulae had been published for the deduction from such observations of any of the parts of the deviation. This will explain why, in the paper of 1860, the discussion was con- fined to the coefficients which are derived from observations of deviation only, viz. A, B, C, D, E. The new modes of construction brought into prominence the diminution of mean directive force which a compass-needle suffers in an iron ship, particularly when placed between two iron decks. It is well known that in the interior of a thick iron shell the effect of the earth’s magnetic force is nearly insensible. This is not caused by the iron of the shell intercepting the earth’s magnetism, but by an opposite magnetism being induced which nearly neutralizes the earth’s magnetism whatever be the inductive capa- city of the shell, and whatever be the thickness of the shell, provided only that the thickness bears a considerable proportion to the diameter of the shell. When the shell is thin, the diminution of force is still considerable, but it then depends in a very much greater degree on the inductive capacity and the thickness of the shell. The destruction of force is total in the case of a spherical shell whatever be its thickness, if the inductive capacity be infinite. An iron ship, as regards a compass-needle between decks, may be compared to a thin iron shell. Before the ship is launched, and when every particle of iron in her structure has by continued hammering become saturated with magnetism, she may be compared to a thin shell of high inductive capacity, and the directive force on a needle in the inte- rior is consequently greatly diminished. When the ship is launched and placed succes- sively on every azimuth, she may be compared to a thin shell of low inductive capacity. The mean directive force on a needle in her interior will be considerably diminished, but the diminution will depend much more on the thickness of the surrounding iron. This diminution has been found so considerable in the case of iron-built and particu- larly iron-plated ships, as to have become a matter of serious consideration in selecting a place for the compasses. CHARACTER OF THE ARMOUR-PLATED SHIPS OF THE ROYAL NAVY. 265 Observations of horizontal force, for the purpose of ascertaining the diminution of the mean directive force, have now become part of the regular series of observations made in ships in which its determination is of importance, and formulae and graphic methods, for the purpose of deducing from them the proportion of the mean value of the directive force to North to the earth’s horizontal force, are given in the ‘ Admiralty Manual.’ Another error of the greatest importance, which has been brought into prominence in the modern class of iron -built ships, is the “ heeling error.” The deviations obtained by the usual process of swinging are for a vessel in an upright position. It is found by experience that, as the vessel heels over, the north end of the compass-needle is drawn either to the weather or lee side, generally in the northern hemisphere to the former, and the deviation so produced when the ship’s head is near North or South, often exceeds the angle of heel. This not only produces a deviation which may cause a serious error in the ship’s course, but if the ship is rolling, and particularly if the period of each roll approximates to the period of oscillation of the compass, it produces a swinging of the compass-needle which may make the compass for the time useless for steering. This error had been known to exist, and its amount had even been measured in the case of Her Majesty’s ships Eecruit (1846), Bloodhound (1847), Sharpshooter (1848), and in various cases recorded by the Liverpool Compass Committee (1855-61); but no method had been proposed for determining this error by observations made with the ship upright, and considerable obscurity was even supposed to rest on the causes and law of this deviation. The application of Poisson’s formulae has entirely removed the obscurity, and furnishes an easy method of determining the heeling error by observations of vertical force made on one or more directions of the ship’s head. These observations have likewise now become a regular part of the complete series of magnetic observations made in the principal iron ships of Her Majesty’s Navy. Fortunately the mechanical correction of this error, when its amount is ascertained, is not difficult, and as the correction does not affect the deviation when the ship is upright, its application is free from some of the objections which exist to the mechanical correc- tion of the ordinary deviation. The importance of being thus able to detect the heeling error by observations of a simple kind made with the ship upright is great, and this is perhaps one of the most practically useful of the immediate results of the application of mathematical formulae to this subject. Besides these, which may be called the direct results of the additional observations now made, and of the application to them of the mathematical formulae, there are some other results of the use of the formulae which have a practical value as well as a theo- retical interest. Among these is the separation into their constituent parts of the several coefficients, so as to indicate the particular arrangements of the iron from which each arises. This is not only of great theoretical interest, but is of considerable practical importance in 2 o 2 266 STAFF COMMANDER EVANS AND MR. A. SMITH ON THE MAGNETIC indicating the place which should be selected for the compass, and also in enabling us to anticipate or account for the subsequent changes which take place in the deviation. Another and perhaps even more important result is that we are enabled by observa- tions made with the ship’s head in one direction, and therefore when she is in dock or even on the stocks, to determine the coefficients and construct a table of deviations, including the heeling error, without swinging the ship. To explain this, we may observe that for the complete determination of the deviations of the compass when the ship is upright and in one geographical position, six coefficients are required. But of these two vanish when the iron is symmetrically arranged, two more are so nearly the same in ships of the same class that they can be estimated with a near approximation to the truth ; we have therefore only two coefficients left, and these can be determined by an observation of deviation, and an observation of horizontal force made without altering the direction of the ship’s head. So as regards the heeling error, to determine this three additional quantities are generally necessary, but of these one is zero when the iron is symmetrically arranged ; another may be estimated, and the third may then be determined by a single observation of vertical force. The quantities so estimated change little after the ship is completed, so that any assumption made as to their value may he checked by subsequent observations. These considerations will show the importance of not only making the observations we have mentioned, but of reducing the observations made, and of tabulating, discussing, and publishing the results of the observations. In the Tables it will be seen that the original observations are not given ; they, as well as the curves and computations by which the coefficients are derived, are carefully preserved among the records of the Admiralty Hydrographic Office, and may at any time be referred to ; but the coefficients, at least so far as regards the deviation of the horizontal needle, represent so exactly the observations made, that to give them here at length would he an unnecessary waste of space. The observations, the results of which are tabulated, were made in the following manner. The deviations of the Standard Compass were observed by reciprocal simul- taneous bearings of the Standard Compass and an azimuth compass on shore, in the manner described in the ‘Admiralty Manual.’ The admirable construction of the Admi- ralty Standard Compass, as regards design and workmanship, accuracy of adjustment and magnetic power, leaves nothing further to be desired for such observations. The arrangement of its four needles obviates, as we have shown in a former paper*, the sextantal error caused by the length of the needle when acted on by iron placed near it. The deviations of the steering and maindeck compasses were obtained by observations of the direction of the ship’s head by those compasses, made simultaneously with the observations of the Standard Compass. These compasses in the Royal Navy are of * Philosophical Transactions, Part II. 1862. CHARACTER OE THE ARMOUR-PLATED SHIPS OE THE ROYAL NAVY. 267 simpler construction than the Standard, not being fitted with the azimuth circle, and generally having only two needles, but they are of little inferior accuracy, magnetic power and delicacy. The two needles are arranged so as to obviate the sextantal error above alluded to. The Tables of deviations of these compasses have in all cases been most satisfactory, and on those points on which the directive force is very much diminished, they con- tinue to give satisfactory indications which compasses of inferior workmanship would wholly fail to do. The observations of horizontal force were made by vibrating a small flat lenticular needle 2f inches long and ^ inch broad, fitted with a sapphire cap, on a pivot of its own, made to screw into the socket of the pivot of the Standard Compass, and comparing the time of vibration with that of the same needle vibrated on shore. The observations of vertical force were made by vibrating a dipping-needle of 2f inches, placed in the position of the compass, the needle being made to vibrate in a vertical plane at right angles to the magnetic meridian. The observation might of course be made by vibrating the needle in the plane of the meridian and observing the dip ; and in low dips that method is probably the best. In so high a dip as that of England, vibrations in the east and west plane are sufficiently accurate, and enable us to dispense with observations of dip. In the selection of these instruments it has been found of great importance that they should be light, portable, easily and quickly fixed in position, capable of being placed in the exact position of the compass, should admit of observations being made quickly and in rough and boisterous weather, and should be such that each separate observation should give a useful result. When the observer can command favourable circumstances of observation, as in the case of observations made in a ship on the stocks, it is possible that instruments of greater nicety may give more exact results, but for the ordinary observations which can be made in the process of swinging a ship, we have every reason to be satisfied with the results obtained from the instruments we have described. As the formulae made use of in the reductions are nowhere published except in the ‘ Admiralty Manual,’ it seems necessary here to give them with a brief indication of the manner in which they are obtained. The effect of the iron of a ship on the compass-needle is assumed to be due partly to the transient magnetism induced in the soft iron by the magnetism of the earth, and partly to the permanent magnetism of the hard iron. Simple physical considerations show that the components of the first in any three directions in the ship are linear functions of the components of the earth’s magnetism in the same directions, the last is expressed by constant forces acting in the same three directions. If, therefore, the components of the earth’s force on the compass be X in the direc- 268 STAFF COMMANDER EVANS AND ME. A. SMITH ON THE MAGNETIC tion of the ship’s head, Y to starboard, Z vertically downwards or to nadir, and if the components of the ship’s permanent magnetism in the same directions be P, Q, and R, and of the total force of earth and ship in the same three directions X', Y', Z', then Ship’s force to head =X'— X=«X+JY+cZ+P, . . . . (1) Ship’s force to starboard =Y'—Y=^X+^Y+/Z+Q, (2) Ship’s force to nadir =Z' — Z== sin (2£' +&)+($; cos(2£'-|-&). . . (10) If the deviations are small, we have approximately S=A+B sin£'+C cos£'+D sin2£'+E cos2£', (11) in which A, B, C, D, E are (nearly) the arcs of which 9t, 93, (5, 2), (S are the sines. The term 93 sin £' + (S cos £' may be put under the form \/932+(£2 sin (£'- \-a ), in which a, called the starboard angle, is an auxiliary angle such that tan a=|^ • If the soft iron of the ship be symmetrically arranged on each side of the fore-and-aft line of the ship through the compass, then 4=0, d= 0, /= 0, 91=0, / B2+C2) is the maximum of semicircular deviation. is the tangent starboard angle, or of angle measured to right of fore and aft of line of ship, in which the force causing the semicircular deviation acts. 2) = (approximate value in degrees =D) is the maximum of quadrantal deviation from soft iron symmetrically placed. — 1^ =~ is the part of 2> arising from fore-and-aft soft iron. ® 1^ = — A is the part of 2) arising from transverse soft iron. ($, = (approximate value in degrees =E) is the maximum of quadrantal deviation from soft iron un symmetrically placed. tan is the heeling coefficient, or the deviation to windward in degrees for one degree of heel when ship’s head North or South by disturbed compass. ^2) + ^— 1^ tan 0 is the part of heeling coefficient from transverse soft iron. - — i j tan 6 is the part of heeling coefficient from vertical soft iron, and vertical force of hard iron. 9 is the increase or decrease of vertical force above or below mean when ship’s head is tanS North or South. CHAEACTEE OF THE AEMOUE-PLATED SHIPS OF THE EOYAL NAVY. 271 ?+- H tan 6 =93 H, ^+1 H' tan ^=S5,H' are the equations for determining c and P separately when S3 has been determined in two different latitudes ; (St-dg A i—i' ' i—i' ’ 7=SSH— tan 6 K A A are equations for determining c and P separately when observations have been made in one geographical position, but on two different angles of heel ; ®= i^cos£-(l + ©)cos£, ©= sin £'+(!-$) sin £ are equations for determining SB and (5 by observations of deviation and horizontal force on one azimuth of the ship’s head, X and 3) being known or, estimated. There is a physical representation of Poisson’s fundamental equations so simple, and which gives us so great a power of estimating the effect on the compass of different arrangements of iron in a ship, as well as of tracing to their cause any peculiarities in the observed deviation, that it seems desirable, before entering on the peculiarities of structure and deviation in armour-plated ships, to explain this representation, and to show how it explains the phenomena of deviation. If an infinitely thin straight rod of soft iron be magnetized by the induction of the earth, the effect will be the same as if each end became a pole having an intensity pro- portional to the component of the earth’s force resolved in the direction of the rod, and to the section and capacity for induction of the rod. Let us now suppose nine soft iron rods placed as Plate X. It will be seen that for each rod we must distinguish the two cases, that in which its coefficient is +, and that in which it is — . It will also be seen that in the three cases, viz. —a, — e, —k, in which the rod passes through the compass, we may consider both ends as acting, but that in other cases it is convenient to consider only the action of the near end, and that the far end is at an infinite distance. The rod a, it will be observed, can only be magnetized by the component X, b only by Y, and c only by Z ; and if we call aX, bY, and cZ the force with which these rods attract the north end of the needle, and if we suppose, as we are at liberty to do, the mdccclxv. 2 p 272 STAFF COMMANDER EVANS AND MR. A. SMITH ON THE MAGNETIC rods being imaginary, that they exercise no action on one another, a , b , and c will produce a force to head =aX+bY+cZ ; so d , e, and /will produce a force to starboard =dK+eY+fZ, and g , h, and k will produce a force to nadir =#X+AY+£Z. By comparing these results with Poisson’s formulae, we see that for the effect of the soft iron of the ship, however complicated its arrangement may be, we may substitute the nine soft iron rods. The quantities P, Q, E in the general equations may be conveniently represented by three bar-magnets, placed in fixed positions in the ship ; P attracting the north end of the compass-needle to the head, Q to starboard, and E to nadir. Very simple considerations will show us that the two rods a and e will increase the directive power on the needle in the proportion of l + ~7y~ : 1? and that the other seven rods, as well as the permanent forces P, Q, E, will not affect the mean directive force. Simple considerations will also show that a and e will produce a deviation, ^sin2£=Dsin2£ nearly. Like considerations will show that c and P will produce a deviation, C-Z^T sin £ = ^ tan 0 + ~ ^ sin £'=B sin £'. Also that f and Q will produce a deviation, /Z + Q. y. ( f QA y. ^ y. cos ^ tan^-f-g ) cos £'=C cos The other less important terms, as well as the heeling error, may be obtained in the same manner. DISCUSSION OF THE TABLES. At the risk of some repetition it may be convenient to give here a brief explanation of the quantities tabulated. The first five quantities, A, B, C, D, E, are the “approximate coefficients” which give the deviation of the compass on every course by means of the expression S = A+ B sin £ + C cos £ + D sin 2£ + E cos 2£, in which & is the deviation, the azimuth of the ship’s head measured eastward from the direction of the disturbed needle, A, B, C, D, E being expressed in degrees and minutes. This expression is sufficiently accurate for deviations not exceeding 20° ; for larger deviations, the exact expression for the deviation given in the preceding part of the CHARACTER OF THE ARMOUR-PLATED SHIPS OE THE ROYAL NAVY. 273 paper requires the use of the “ exact coefficients ” 9(, S3, (5, 2), (S, which are not ex- pressed in degrees and minutes, but are nearly the sines of the corresponding angles A, B, C, D, E. For the purpose of this discussion we may confine our attention to A, B, C, D, E. A is the “ constant part of the deviation.” A real value of A can only be caused by elongated horizontal masses of soft iron unsymmetrically arranged with reference to the compass, and would be the same in all parts of the globe. An arrangement of hori- zontal soft iron rods such as that in fig. 1 would give a positive value to A and no other term in the deviation. This, however, is not an arrangement which would occur on shipboard. Fig. 1. Fig. 2. A soft iron rod such as that in fig. 2 would give -f A to the starboard compass, com- bined with +E; and — A, combined with — E, to the port compass. This arrangement is not unfrequent in the relative positions of the spindle of the steering-wheel and the binnacle compasses placed near it for the guidance of the helmsman. In compasses placed in the middle line of the ship such an arrangement is improbable, and in such case A has probably little or no real value. An apparent value may, how- ever, be given to A by index-error in the compass on board, index or other error in the shore compass with which it is compared, or error of observations generally. When the ship heels over, an elongated horizontal mass of iron, which was symme- trically placed from being below the compass, as the screw-shaft or the keel, is thrown to one side, and an A may then be introduced caused by and proportional to the angle of heel ; but this has not been found of sufficient amount to require attention in practice. The terms B sin £'+C cos £' make up together what is called the “semicircular devia- tion B depending on fore-and-aft forces, and having its zero when the ship’s head is North or South, its maximum when it is East or West ; C depending on transverse forces, and having its zero when the ship’s head is East or West, its maximum when it is North or South. B consists of two parts, one a coefficient arising from vertical induction in soft iron before or abaft the compass, and being multiplied by the tangent of the dip and a factor - hereafter explained ; the other a coefficient arising from permanent magnetism of the 2 p 2 274 STAFF COMMANDER EVANS AND MR. A. SMITH ON THE MAGNETIC hard iron in the ship acting in the fore-and-aft line, and multiplied by the reciprocal of the earth’s horizontal force, and also by the factor ^ . The last part may be considered as itself consisting of two parts ; one, of the subpermanent magnetism induced while the ship was building by the vertical component of the earth’s force, and which probably bears some relation to the transient magnetism induced by the same vertical component ; another, of the subpermanent magnetism induced while the ship was building by the headward component of the earth’s horizontal force. C theoretically consists of similar parts acting towards the sides of the ship ; but as the iron may in general be considered as symmetrically arranged on each side of the compass, the value of C is probably, in all cases when the ship is upright and the com- pass is amidships, to be attributed to subpermanent magnetism induced while the ship was building by the transverse component of the earth’s horizontal force. The part of B consisting of transient induced magnetism varies as the tangent of the dip. The other part of B and C vary inversely as the earth’s horizontal force. As regards changes which take place after launching, without a change of geographical position, there are differences between the several parts of B and C which require notice. When the ship is launched, notwithstanding that her head is no longer kept in one fixed direction, the forces which cause the two first-mentioned parts of B still act in precisely the same direction as before, and these two parts probably undergo little change. With the third part of B and the whole of C the case is very different. The forces which cause these parts cease to act in the same direction as at first. If the vessel is allowed to swing at her anchors, or is under sail or steam, she will probably on an average be nearly as much on one point as on another ; or, which would come to nearly the same thing, if she is lying in a tideway she may be alternately for six hours in one direction and for six hours in the opposite direction. A great portion of the C and of that part of the B which arose from horizontal force thus become dispelled. The symmetry which gives C its character ceases the moment the ship heels. An addition is then made to C proportional to the angle of heel, and this addition consists in fact of two parts, corresponding to the two parts of B which, as we have seen, do not exist in the original C, viz. a part consisting of transient magnetism induced by the vertical force, and a part consisting of subpermanent magnetism induced by the same force. These will be more conveniently considered when we come to discuss the heel- ing error. The semicircular deviation may be put under the form \/B2+C2sin(^'+a), in which v/B2-J-C2 represents the maximum of semicircular deviation, a f tan «= -j the angle to the right of the ship’s head of the force causing this deviation; for convenience, these two quantities are tabulated in the eleventh and thirteenth columns. The terms D sin 2£'-}-E cos 2£' make up what is called the “quadrantal deviation.” CHAEACTEE OE THE AEMOTTE-PLATED SHIPS OP THE EOYAL NAVY. 275 This can only be caused by horizontal induction in soft iron. E can only be caused by horizontal induction in soft iron unsymmetrically distributed, but of any shape ; an E may therefore be caused by the compass being placed out of the midship line and exposed to the influence of spherical or cylindrical masses, such as the iron gun-turrets of modern war-vessels. D, which in ordinary cases is always +, is caused by horizontal induction in soft iron arranged according to one or other of the following types : — Pig. 3. Pig. 4. + a \\a In the figures -f -a represents masses of soft iron entirely before or entirely abaft the compass, as engines, boilers, funnels, iron masts, &c.; — a represents soft iron extending through the position of the compass, as the keel and hull of the ship, the screw-shaft, armour-plating, &c., the effect of the latter in almost all cases exceeding that of the former, so that a is in general negative; — e represents the effect of all the transverse soft iron, as the bottom of the ship, the iron decks (except where interrupted by hatch- ways near the compass), iron deck beams, and the engines, boilers, &c. ; -\- e represents the masses of iron, comparatively few in number, which lie to one side of the compass, as decks where the compass is in or over a hatchway, occasional guns, davits, & c. In every ship which has been examined, the effect of the transverse iron extending through the position of the compass exceeds that of any masses of iron wholly on one side, and e is negative and greater than a ; and as 2 = ^^, 2), and consequently D, are in almost all cases + . D and E do not change with a change of geographical position. In almost all cases in iron-built ships, not only is the direction of the needle directly affected by the iron of the ship, but a further prejudicial effect is caused by the soft iron diminishing the mean directive force of the needle, and so indirectly increasing the effect of all disturbing forces. This is shown by the factor X, which gives the mean value of the directive force, or rather of the northern component of the directive force in the ship, and which is almost always less than unity, the force on shore being considered as unity. The cause of this diminution will be seen by figs. 3 & 4. In fig. 4 a little considera- tion will show that both —a and — e diminish the directive force. In fig. 3 +a in- 276 STAFF COMMANDER EVANS AND MR. A. SMITH ON THE MAGNETIC creases the directive force, — e diminishes it; but as — e always exceeds -\-a, the result is a diminution on the whole. The expression for X in terms of a and e is X = l + a + e The tabulated values of X are obtained by comparing the terms of vibration of a hori- zontal needle vibrated in the position of the compass in the ship and also on shore; X does not change with a change of geographical position. The determination of 3) and X gives us the means of determining the two parts a and e, and also the two parts of which D is composed, separately ; and these are accordingly tabulated. The preceding are the only coefficients which affect the compass when the ship is upright ; but when the ship heels over, new disturbing forces are called into play, caused by arrangements of soft or hard iron of one or other of the following types: — Fig. 5. — e represents, as before, the transverse soft iron, which will evidently, as the ship heels over, produce a force to windward, or the high side of the ship, on the north end of the needle. If the rods -\-7c and — k represent soft iron, then -| -k gives a force acting down- wards on the north end of the needle, which, as the ship heels, becomes a force to wind- ward ; — k a force acting upwards, which, as the ship heels, becomes a force to leeward. The permanent magnetism of the ship will generally act downwards if the compass is over the end which has been South in building, upwards if over the end which has been North in building. The amount of the two forces may be ascertained by vibrating a dipping-needle on shore and in the ship with her head in certain positions. The pro- portion of the mean vertical force on board to the vertical force on shore is denoted by the coefficient p, which is tabulated for those ships in which the observations have been made. From the values of 3) and X we obtain by a simple formula, viz. ^3) + 1^ tan 6 1°, the “ heeling coefficient to windward,” or the deviation to windward caused, when the ship’s head is N. or S. by compass, by an angle of heel of 1°. When this coefficient has a negative sign it indicates a deviation to leeward. The values of the heeling coefficient so deduced are tabulated. The value changes with a change of geographical position. From the values of p, 3) and X we may also determine how much of the heeling error arises from the transverse soft iron represented in the figures 3, 4 & 5, and how CHARACTER OF THE ARMOUR-PLATED SHIPS OF THE ROYAL NAVY. 277 much from the vertical soft iron and the hard iron, the first = ^2)+ 1^ ^an ^ *°’ the second =■ tan H°; and these two parts are tabulated in the next columns. If we have not an opportunity of observing the vertical force on a sufficient number of points to obtain its mean value, the values observed will be affected by soft iron represented by the rod g , in the following figure : — Fig. 6. the value of [m on any azimuth £ being in fact increased by + cos where 6 is the dip. It is therefore convenient to know the values of q or and these are also ^ ^ tan 0 tabulated ; g does not change with a change of geographical position. In comparing the heeling error when the ship’s head is North or South, we must beware of falling into the error of confusing the two senses in which these words may be used. It may seem most natural to suppose the ship’s head to be North or South when upright, and that she is then heeled over without altering her direction. In that case we should have (nearly) Heeling error head North : heeling error head South : : 1 — 25 : 1 +93. In fact the heeling error is nearly inversely proportional to the directive force on the needle. But this is not the sense in which the term is generally used. In general we suppose the ship swung when heeled to starboard and again when heeled to port, and the devia- tions tabulated in the usual way, according to the ship’s azimuth by disturbed compass. In this case, which is the simplest mode of considering the error for the purpose of correction, the heeling error, head North, will only differ from the heeling error, head South, by reason of the quantity g , i. e. by reason of the difference of the vertical and not of the horizontal forces in the two positions. The importance of the heeling error, owing to its large amount in certain ships, will be seen in the discussion of the values given in the Tables ; and the importance of being able to determine it by observations easily made, and without the necessity of actually heeling over the ship, can hardly be overrated. We are now in a position to consider the numerical values of the coefficients given in the Tables. 278 STAFF COMMANDER EVANS AND ME. A. SMITH ON THE MAGNETIC Constant Deviation. A. The values of A, when the compass is placed in the middle line of the ship, and when the deviations have been observed with every care, are always so small, that the values which appear in the Tables may be considered rather as errors of adjustment and observation than as real values. In fact it may be inferred that in all cases where the compass is in the middle line of the ship, we may consider A as zero. It results from this, and is important in practice, that we may safely take the mean of the compass bearings of any object, on four or more equidistant compass courses, as the correct magnetic bearing ; observing, however, that if we observe on four points only, and D be large, these ought to be either the cardinal or the quadrantal points. Semicircular Deviation , B sin C cos g. The points which require attention are, — 1. Its original value and its connexion with the direction of the ship in building, and the position of the compass in the ship. 2. The changes which take place after launching. 3. The subsequent changes. 4. The changes which take place on a change of geographical position. 1. In wood-built ships, as maybe seen by an inspection of the Deviation Tables given in the work of the late Captain E. J. Johnson, R.N., on the deviation of the compass, the direction of the force causing the semicircular deviation is in northern latitudes nearly towards the ship’s bow. In iron-built ships it is nearly to that part of the ship which was South in building ; or, in other words, the starboard angle as given in the Tables, is nearly the same as the azimuth of the ship’s head to the East of South in building ; thus, — Starboard angle, or direction Direction of bead in building. of semicircular deviation. Orontes . . N. 66° W. or S. 246° E. 235° Tamar . . . West or S. 270° E. 279° The case of the armour-plated ships is an interesting exception to this rule. Such ships are generally plated after launching, and in a different position from that of building. In these ships the angle of the semicircular force is generally intermediate between the angle of the ship’s head to the East of South in building, and the like angle in being iron plated ; thus, — Warrior . Black Prince Defence . Resistance Valiant Direction of bead in building. N. 3 E. or S. 177 E. S. 20 E. 20 S. 47 W. 313 Direction of bead in plating. N.W. or S. 225 E. South. 0 S. 19° E. 19 West. 270 generally to westward Direction of Semicircular Deviation. 195 8 0 f 313 * 1282 CHARACTER OF THE ARMOUR-PLATED SHIPS OF THE ROYAL NAVY. 279 From these results we may infer that the process of plating an iron ship in the direc- tion opposite to that of building will always produce a diminution, which in some cases may become a reversal of her semicircular deviation ; and that by duly taking advantage of this circumstance, the deviations of iron-plated ships may be brought within manageable limits. The Tables show, as might have been anticipated, the much larger amount of the deviation in the steering and main-deck compasses than in the Standard Compass, and the advantages to be derived from a judicious selection of a place for the compass ; un- fortunately even in the case of the Standard Compass the choice of position is so limited by the exigencies of the arrangements for working and fighting the ship, that the devia- tions in these compasses are generally larger than could be wished. 2. After launching, and when the vessel is swinging at anchor, or sailing or steaming in various directions, the values of B and C generally diminish rapidly ; and this change would no doubt be accelerated by the vessel being exposed to blows or jars in a position different from that of building. The following cases show a rapid change of B and C after launching. The most instructive have been selected from the Tables, but the elaborate series of observations made in the Great Eastern (Phil. Trans. 1860) are the most conclusive, as that ship was in every respect prepared for sea, and the observations are strictly comparable throughout. H.M.S. Achilles, built in dry dock at Chatham, and fully plated there also, head S. 52° E., floated out of dock 24th December 1868, and moored head and stern in the River Medway, head S. 62° E. In March 1864, after taking in steam machinery, the ship made a short trial trip down the river, and then returned to the former moorings, but with her head secured in the opposite direction, or N. 62° W. Equipment and fittings completed by October 11th, when the head was shifted round to S. 55° E., and on the following day steamed to Sheerness and commenced sea service. 23. 1863. Dec. 23. — In dock at Chatham + ■464 + •323 1864. Sept. 26. — Complete for sea, head N. 62° W. . . + •377 + •037 Oct. 11. — Complete for sea, head S. 55° E. . . +•355 + •062 Oct. 13. — Swinging at anchor, Sheerness . . . + •362 +•047 Dec. 5. — At Plymouth, after 25 days in dock,) - + *361 + •123 head S. 79° E J H.M.S. Royal Oak, wood-built ship, iron-plated in dock at Chatham, head S. 49° E„ 1863. Mar. 19. — Floated out of dock + •253 + •287 April 11. — Swinging at anchor, River Medway . + •231 + •197 June 2. — Swinging at anchor, River Medway . + •248 + •128 1864. Jan. 8. — Swinging at anchor, Plymouth . + •218 + •172 The example of the Achilles is very instructive. The large value of (S+’323 giving mdccclxv. 2 Q 280 STAFF COMMANDER EVANS AND MR. A. SMITH ON THE MAGNETIC a C of 19°, which was caused by the ship having been built, plated, and moored with the starboard side South, is reduced to +‘037 or 2° 10' by lying for six months with the port side South. This amount does not alter materially while the ship is allowed to swing, but when she is twenty* five days in dock with the starboard side South, it suddenly rises to + T23 or 7°. SB, it will be observed, changes much less at first, and hardly changes at all afterwards ; this difference must be attributed in part to this, that while the whole of (5 is to be attributed to subpermanent magnetism arising from horizontal induction in transverse hard iron, a large part of the original S3 was probably caused by the transient magnetism arising from vertical induction in soft iron, and a further part by the subpermanent mag- netism arising from vertical induction in hard iron, so that possibly not more than TOO was caused by the subpermanent magnetism arising from induction from the headward com- ponent of the horizontal force, nearly the whole of which may have been removed by six months’ reversal of her direction, so as to leave little room for subsequent change of S3. In connexion with this part of the subject we may observe that the same circumstances which cause the transient magnetism arising from horizontal induction in transverse iron (—&) to be greater than the transient magnetism arising from horizontal induction in fore-and-aft iron ( — a), lead us to expect that the subpermanent magnetism arising from horizontal induction in transverse hard iron ((5) will be greater than the subper- manent magnetism arising from horizontal induction in fore-and-aft hard iron (changing part of S3), and that consequently we should expect the relative changes of 6 which take place on a change of direction to be greater than those of S3, and this will be found to be verified in almost all cases, except when the ship has been built nearly North and South. 3. After a certain time, which may be roughly estimated at a year after launching, this process seems to stop, and the values of B and G remain remarkably permanent. The former paper* contains numerous examples of this in ordinary iron-built ships. This will appear also from the following instances of the iron-plated ships. Standard Compass. a <£. Warrior. September 1861 . . . -•449 -•124 October 1861 . . . . -•409 -•092 July 1862 .... -•321 -•114 June 1863 .... —-■317 — T32 July 1864 .... -•311 -•054 October 1864 .... -•307 -•072 Defence. February 1862 .... +•464 + •005 March 1863 .... + •379 -•034 December 1863 . . , . + •403 -•016 April 1864 .... + •391 f © © -a October 1864 .... + •379 -•034 * Philosophical Transactions, Part II. I860. CHARACTER OR THE ARMOUR-PLATED SHIPS OF THE ROYAL NAVY. 281 Standard Compass. 33. e. Black Prince. November 1861 . + -422 + •058 September 1862 . . . -f-383 + •074 July 1863 . . + •384 + •067 April 1864 . . , +-389 + •086 October 1864 . . . +-349 + •050 Resistance. August 1862 . , , +T49 -•158 June 1863 . . . +T52 -•138 December 1863 . . , +T06 -•120 December 1864 . +-065 -•153 It will be remembered in the foregoing examples that the ships have been frequently subjected to the strains in docking, trials, in gales of wind, and at high rates of speed, and especially to concussions from the drilling and firing their heavy ordnance. A striking example of the permanency of the magnetism of an “ old ” iron ship after severe concussion is afibrded in the case of the Adventure troop-ship built in 1854. This ship, in the course of foreign service during a fog, struck on a rock with sufficient force to tear away and crush in 20 feet of the stem and bow under water ; appended are the coefficients observed before proceeding on the foreign service, and after the injuries sustained had been repaired in dock. 1862. April 26th . . . = U73 + -186 1862. October 28th , . — -07X + T86 An equally close agreement will be fonnd, on reference to the Tables, to exist in the other magnetic coefficients of this ship ; the exact accordance of the numerical values is of course accidental, but is conclusive as to the great wear and tear and rough usage an old iron ship can undergo without her magnetic conditions being changed. 4. The determination of the proportion of the semicircular deviation, or rather of B, which arises from vertical induction in soft iron, and that which arises from the perma- nent or subpermanent magnetism of hard iron, is a matter of great interest. Theore- tically it may be determined in two modes, either by observing the deviation in two different magnetic latitudes, or by observing the deviation with the ship upright and heeled over. Unfortunately there is a great want of observations under these circum- stances. The deviations of the iron-plated ships, given in the Tables, were carefully observed both at Lisbon and Gibraltar, but the difference of latitude between either place and England is too small, and the change in the subpermanent magnetism too great to enable us to derive any very certain results from these observations. The difficulty of heeling a large ship is so great that few observations except in an upright position can be expected ; we owe, however, to the zeal of the officers in com- mand of the Warrior*, Black Prince, and Defence, that these ships were swung at * Magnetip science is footed to the Honourable Captain Cochrane of Her Majesty’s Ship Warrior, for the interest he has evinced,, and the assistance he has rendered in obtaining poprplete records of that ship ; and 2 q 2 282 STAFF COMMANDER EYANS AND MR. A. SMITH ON THE MAGNETIC Lisbon upright, and heeled about 7° to starboard and to port. The agreement of the values of the coefficient ~ derived by the different methods is not very satisfactory, and it can only be considered as a rough approximation to the truth. From the equation for comparison of semicircular deviation in different latitudes ?+Htan^=9BH. P c_ A* A Warrior .... — ‘471 +‘058 Black Prince . . . +‘061 +-142 Defence .... +‘206 +‘079 Resistance. . . . —330 + T90 From heeling-error formulae. jj. A Warrior +T08 Black Prince +*181 Defence +T19 Taking the mean of the several values in the ships. Original value of B. c a Part of B from soft iron. Part of B from hard iron. Warrior -241 •083 + 12 — 3&1 Black Prince + 23 •161 + 23 0 Defence + 25f •099 + 141 + 114 Taking the present values of B in the ships. B. C Part of B Part of B k from soft iron. from hard iron. Warrior -17 •083 + 12 -29 Black Prince + 19 •161 + 23 — 4 Defence + 21 •099 + 141 + 61 And in any other magnetic latitude for which the horizontal force is H, the hori- zontal force in England being 1 and the dip 6, we should have O 29 ° Warrior .... B=— jj +4f tan 6. Black Prince. . . B= — g + 9^ tan 0. o Defence .... B= ^|+5§tan0. also to William Mates, Esq., Master of Her Majesty’s Ship Defence, for a valuable series of observations made in that ship, and for his exertions in obtaining results in several ships of the Channel Squadron. CHARACTER OF THE ARMOUR-PLATED SHIPS OF THE ROYAL NAVY. 283 Quadrantal Deviation, D sin 2£'+E cos 2£\ Mean force to North XH. The Tables show that the values of E when the ship is upright and the compass in the midship line, give no certain indication of any real value. The more accurate the instrument, and the more careful the observations, the smaller E generally is. When the compass is not in the midship line the case is different ; an E may then have a considerable value. Instances of this will be seen in the deviations of the Royal Sovereign, the peculiar construction and fittings of which ship made it necessary to place compasses considerably out of the midship line, and with gun turrets placed diagonally to them. At the steering wheel on upper deck . At the steering wheel in captain’s cabin (Port side Forward on lower deck (Starboard side . E= — 9 14 . E= — 5 10 . E=+4 38 . E= — 4 42 It will easily be seen that a +E would be caused by a gun turret in the first and third quadrant relatively to the compass, and a — E by a turret in the second and fourth. The close agreement of the numerical value of E in the two last examples, with the difference in their signs, is striking. The value of the E introduced by the ship heeling by an angle i to starboard being £±£?- 2A and both c and g being generally positive, we should expect a — E when the ship heels to starboard, a +E when she heels to port, and this is the case in the few instances we have in the Tables. E. Warrior. — Standard Compass . . Black Prince. — Standard Compass . Defence. — Standard Compass o o \n to starboard -0 45 m to port . . +o 59 m to starboard -1 25 to port . + 1 50 n to starboard -0 05 .7* to port . . + 1 50 D. As regards D, the most important point is its magnitude in different positions in ships of different classes. The usual or average value of D has greatly increased since the publication of the Paper in 1860. In that paper it was observed that a value for this coefficient not exceeding 4° and ranging between that amount and 2°, might be assumed to represent 284 STAFF COMMANDER EVANS AND MR. A. SMITH ON THE MAGNETIC the average or normal amount in vessels of all sizes, and in only two vessels mentioned in that paper did D exceed 5°. In the iron-built armour-plated ships its average amount in the Standard Compass is about 7°, in the steering-compass about 10°, and in the main-deck compass about 12°. In the wood-built iron-plated ships the value of D is small. The following Table gives the value in different ships. Warrior. Black Prince. Achilles. Defence. Resistance. Hector. Valiant. Royal Oak (wood- built). Standard compass Starboard steering Main deck + 8 27 + 11 56 + 11 43 + 7 38 + 10 32 + 13 16 + $ 58 + 8 51 + 12 13 + 7 o + 10 16 + 14 35 + 6 17 + 8 28 + 14 0 + 5 24 + 8 24 + 9 47 + 4 54 + 6 52 + 8 05 + 3 09 + 1 47 + 1 28 The large amount in the Standard and Steering Compass of the Warrior is doubtless owing to the rifle tower which is immediately before them, and which gives a -f a. The small comparative values in the Hector and Valiant to the iron-plating being extended from end to end in the ship giving a — a, and the absence of a complete transverse armour bulkhead, the existence of which in the Defence and Resistance, as well as in the Warrior and Black Prince, give large — e, and consequently large deviations in the bin- nacle and main-deck compasses. Between the Resistance and the Defence there is a remarkable difference. These are nearly sister ships, but with this difference, that from the different position of the mizen- mast in the two ships their standard and steering compasses are very differently placed with reference to the transverse armour bulkhead. In the Resistance the Standard Compass is exactly above the bulkhead at a height of 12 feet. The steering-compass is about 4 feet in front, and the same height above it ; while in the Defence these compasses are about 20 feet abaft it. Such a bulkhead, when magnetized at right angles to its plane, will produce a fore-and-aft force on all points in, or nearly in, the same plane in the opposite direction to the mag- netizing force. It will therefore, in the case of the standard and steering-compasses of the Resistance, introduce a —a as well as a — e, while it will produce little or no —a in compasses placed as in the Defence, and a much smaller — e. These differences do not show themselves in the value of D, which is in fact less in the Resistance than in the Defence, notwithstanding the much more powerful action of the forces which cause it. In order to see them, we must obtain separately the two parts of the quadrantal deviation D, or the value of a and e. This is done in the fol- lowing Table:- — CHARACTER OF THE ARMOUR-PLATED SHIPS OF THE ROYAL NAVY. 285 Warrior. Black Prince. Achilles. Defence. Resist- ance. Hector. Valiant. Royal Oak (wood- built). q, , i / From fore-and-aft induction. . . " [ From transverse induction ... + 06 - I 4 - 2 45 - 2 42 - 5 55 - 3 51 - 2 14 — 1 19 + 8 24 + 11 42 + 9 40 + 9 44 + 12 21 + 9 15 + 7 11 + 4 32 Starboard f From fore-and-aft induction. . . + 0 14 - 3 47 - 3 47 - 2 17 - 7 53 - 3 23 - 2 59 - 2 7 Steering . . . \ From transverse induction . . . + 11 46 + 14 28 + 12 43 + 12 35 + 16 33 + 11 49 + 9 54 + 3 51 -w- • -j-. ,f From fore-and-aft induction... am ec y jrrom transverse induction . . . - 2 35 - 3 9 - 2 10 - 1 02 - 5 58 - 6 56 - 3 51 +15 58 + 15 36 + 16 58 + 15 11 + 15 54 + 15 14 + 5 20 Standard .. | g + 002 -112 -079 -•078 -158 -109 -•068 -043 -■256 -•322 -•277 -•278 -•326 -•263 -•214 -143 Starboard fa . + ■006 -100 -•103 -•064 — 193 -093 -•085 -•066 Steering . . . \ e -•340 -■380 -•343 -■348 - 401 -•325 - 281 -122 fa -•068 -•083 -048 -027 -151 — •176 — 116 Main Deck •! -•418 -•407 — •434 -•409 -■397 -•380 -160 The conclusions we have drawn will be seen to be supported by this separation. Thus we see that the Warrior is the only vessel which has a -\-a and a -J-D from fore-and-aft iron. In the Hector and Valiant the D is comparatively small, because the — a is large, the — e small. In the Resistance the two parts, the difference of which makes up the D, are very much larger than in the Defence, though the resulting value of D is less. The comparison of the values of D and of a and e in the compasses of the Royal Oak with those in the compasses of the Hector and Valiant is very instructive. These ships are nearly alike in dimension, in the arrangement of the iron-plating, and the posi- tion of the compasses. The Royal Oak has an iron upper deck, but is otherwise wood- built. The Hector and Valiant are entirely iron-built. A first inspection of the Table might lead us to infer that the large value of D in the iron-plated ships is due to the armour-plating at the sides, but the comparison with the Royal Oak shows this not to be the case. In fact a little consideration will show that, as regards longitudinal induction, the effect of armour-plating continued from end to end is to produce a — a ; that, as regards transverse induction, the effect of the parts which run fore and aft is to produce a small -\-e, and the effect of the transverse parts near the extremities of the ship to produce a small — e, so that on the whole the tendency is probably rather to diminish than to increase D. The large value of D in the iron ships is evidently attributable to the increased amount of transverse iron in decks, bulkheads, iron beams, and the iron bottom of the ship, the magnetism of which is, as it were, con- ducted upwards by the iron sides. X. The value of X is so closely connected with that of D that it is desirable to consider them together. In the earlier built iron vessels X was very nearly equal to 1. In the Rainbow, at four stations distributed along nearly the whole length of the ship, X ranged from -972 to T003. In the Ironsides, the first iron-built sailing ship, it was ‘917 at 286 STAFF COMMANDER EVANS AND MR. A. SMITH ON THE MAGNETIC the steering-compass. In several iron-built ships purchased into the Royal Navy from ten to fifteen years after Mr. Airy’s observations, X averages at present about -930. In the iron-plated ships of the present day it ranges from 'TOO to -900. The following are its values in the iron-plated ships before mentioned. Warrior. Black Prince. Achilles. Defence. Resistance. Hector. Valiant. Royal Oak (wood- built). Standard compass •873 •783 •822 •822 •758 •814 •859 •907 Starboard steering •833 •760 •777 •794 •703 •791 •817 •906 Main deck •757 •755 •759 •782 •726 •722 •862 The large value in the Warrior is evidently owing to the rifle tower, the small value in the Resistance, as compared to the value in the Defence, to the position of the com- passes with respect to the armour bulkheads as above described, and with reference to the armour-plating generally. Familiarity with the values of 2 and X in vessels of different classes, is of great import- ance in enabling us to deduce 95 and (§, by observations made without swinging. The mathematical theory from which the values of 2) and X are derived, supposes that the transient induced magnetism to which 2 and 1— X owe their values, is instan- taneously developed, and as instantaneously destroyed or altered as the ship assumes a new position. This we cannot suppose to be exactly true; but whether the time required for the soft iron to receive its new magnetic state as the ship swings is appre- ciable has been a matter of doubt. The opinion of the authors of the Report of the Liverpool Compass Committee (an opinion entitled to the greatest weight) was, that an appreciable time was required, and that the value of D in particular might be different according as the vessel was swung slowly or quickly ; we have not, however, been able to detect any difference in the values of D which can be attributed to any cause of this nature. The most remarkable feature, however, in X and 2 is the change which takes place with the lapse of time, indicating apparently a change in the molecular structure of the soft iron by which it becomes less susceptible of induced magnetism. This is shown clearly in the following Table : — CHARACTER OE THE ARMOUR-PLATED SHIPS OE THE ROYAL NAVY. 287 1 Standard. Starboard steering. Main deck. X © X © X 2) Achilles T October 1864 •822 + •121 •777 + •154 •755 + •214 | [ December 1864 •854 + •116 •819 + •137 •804 + •188 | 'November 1861 •716 + •145 Black Prince. < September April 1862 1864 •783 •846 + •134 + •137 •760 + •184 [November 1864 •849 + •122 •881 + •144 f February 1862 •822 + •122 •794 + •179 •759 + •254 ! Defence < 1 December 1863 •853 + •122 •842 + •180 •810 + •230 1 April 1864 •857 + •112 •853 + •159 •828 + •233 i [October 1864 •852 + •112 •830 •842 + •230 Resistance ... j f August 1862 •758 + •111 •782 + ■244 ! [ December 1863 •850 + •122 •880 + •219 1 [" March 1863 •861 + •047 Royal Oak ... < April 1863 •907 + •061 •887 + •067 1 [ June 1863 •907 + •055 •906 + •031 Dromedary... j 'July 1862 •841 + •104 |_ December 1862 •861 + •097 These changes, and particularly that in the value of X, seem far too great, far too regular, and far too consistent, to be attributed to any cause except some molecular change in the structure of the iron which, with the lapse of time, renders it less suscep- tible of induced magnetism. Whether this change is accompanied by any change which can affect the strength, the liability to oxidation, or any other qualities of the iron, is a point on which we are not able to offer any information, but we beg to suggest it as a question deserving a careful experimental investigation. Heeling Error. As the heeling coefficient depends partly on vertical induction in transverse iron, partly on the mean vertical force arising from permanent magnetism and vertical induc- tion in vertical iron, and as the two conspire when the vertical force of the ship acts downwards, or when p is greater than unity, and counteract each other when the ver- tical force acts upwards, or when p is less than unity, we may expect great differences in the heeling coefficient in different ships. In those which have been built head North, we may expect a large heeling error in compasses near the stern, and a smaller one in compasses near the bow, and the converse in ships built head South. This we find to be the case. In these cases the uniformity of the heeling coefficients from transverse iron is remark- able, and they are, as might be expected, all of the same sign ; the differences, it will be seen, are nearly all in the part which arises from vertical force ; this varies from 1° 6' in the Warrior to —1° 9' in the Enterprise. It will be seen that in the wood-built iron-plated ships the vertical force is generally mdccclxv. 2 R 288 STAFF COMMANDER EVANS AND MR. A. SMITH ON THE MAGNETIC diminished. This is doubtless the effect of the iron plating, which acts as a — Jc. No doubt in iron-plated iron-built ships the effect is the same, and the heeling error is probably diminished and not increased by the effect of the iron plating. Observations of vertical force have not been made in the main-deck compasses of these ships ; but pro- bably there the heeling error would be small, and possibly be a heeling error to leeward. We must observe that there has not been an opportunity of making an exact com- parison of the values of the heeling coefficient deduced from theory with those deduced from actually heeling and swinging the ship. The great amount of labour and time required to heel a ship of the class we are discussing, and swing her, has prevented such observations being made in more than a very small number of cases. In the case of the Warrior, Black Prince, and Defence, advantage was taken of their being heeled at Class of Ship. Iron plated. 'July 1862. Jan. 1863. Sept. 1862. Jan. 1863. April 1864. Oct. 1864. Dec. 1864. Oct. 1864. ships, , Dec. 1864. iron- " ' Feb. 1862. Jan. 1863. April 1864. Aug. 1862. Dec. 1863. Feb. 1864. (Jan. 1865 April 1863. June 1863. Feb. 1864. Wood ships, ptted. | 1864‘ | June 1864. 1 Iron ships. ( July 1863. Nov. 1863. Sept. 1863. Feb. 1863. Feb. 1863. Mar. 1863. June 1863. Name of Ship. Warrior ,, Lisbon Black Prince „ Lisbon Achilles (Standard aft) „ (Standard forward), Defence „ Lisbon Resistance Hector Valiant Royal Oak Prince Consort Ocean Enterprise (Iron topsides) . . Orontes Tamar „ (Binnacle over rudder) Wye Caradoc Clyde Industry City of Sydney Direction of Head in building. N. 3°E S. 20° E S. 51° 40' E. ... S. 47° W S.86i°W S. 20° E. S. 87° W Plated S. 49°E Plated S. 39° W Plated S. 79° E Built and plated S. 56° W. N. 66° W West Probably to E.S.E. .. Probably to N. by W. Probably to N.E. . . . Probably to S. by E. Probably to W.N.W. •945 •971 •870 •896 1-217 1-240 1040 •968 1071 1044 •848 •929 •622 1117 1-248 M95 1002 1-275 •859 1-246 +•069 +•106 +•118 +•262 + 111 +•194 +■210 -•172 -•165 +•138 +•117 +•157 +•176 + 190 +•120 +•045 +•127 +•038 + 112 +•152 + 147 +•294 +•252 Heeling coefficient from Heeling coefficient windward. vertical induction in trans- verse iron. vertical force and in- duction in vertical iron. +0 43 +0 32 +1 06 +0 50 +1 49 +1 22 +1 01 +° 43 +0 48 -0 11 +0 09 -0 05 +0 50 +0 52 +0 43 +0 50 +0 43 +0 49 +0 37 -0 23 -0 18 +0 40 +0 41 +0 27 +0 25 + 1 29 + 1 18 +0 51 +0 33 +0 42 +0 08 — 0 03 -0 06 +0 59 +0 30 +0 36 +1 04 +0 45 +0 14 +0 08 +1 18 +0 53 +0 48 -0 03 +0 45 +0 37 +0 11 +0 48 +0 24 +0 23 -0 17 -0 19 +0 07 +0 04 +0 16 -0 24 -0 08 +0 19 -0 34 -0 15 +0 37 -1 09 -0 29 +0 36 +0 28 + 1 04 +0 31 +0 28 +0 20 +0 42 +0 51 + 1 10 +0 27 +0 34 + 1 0 +0 14 +0 01 +0 15 +0 35 +0 47 +1 22 +0 18 -0 23 -0 05 +0 46 +0 45 + 1 31 CHARACTER OE THE ARMOUR-PLATED SHIPS OE THE ROYAL NAVY. 289 Lisbon for the purpose of cleaning the bottoms, to swing them at the same time, and the heeling coefficients so obtained correspond very satisfactorily with those obtained in England from observations of horizontal and vertical force. But, unfortunately, at present we have no instances in which the horizontal and vertical forces were observed at the time and place at which the ship was heeled and swung; and it seems very desirable that the theory should be put to the practical test, though there seems no reason to doubt that the results of the two methods would agree within the limits of errors of observation. 9- g is one of those quantities which it is of importance to be able to estimate with some approach to accuracy, in order that the value of the mean vertical force, or p, may be determined by observations of the vertical force made with the ship’s head on one point only. The Tables show that this may3 be done ; g, as might be expected, is larger the nearer the stern the Standard Compass is placed, and is negative in compasses placed near the bow. Achilles +‘194 Resistance +T76 Defence +T57 Black Prince +T18 Warrior + -069 Achilles (Standard forward) . . — T72 There are indications of changes in the value of the heeling coefficient and in the value of g from the lapse of time, corresponding to the changes in the values of 2) and X; but more extended observations are necessary to show the amount and law of these changes. To afford a clear view of the general structure of the armour-plated ships, and the position of the several compasses, profile sketches of these ships are given (Plate XI.), and it may be deemed of sufficient interest to add a brief description of their general arrangements as affecting their magnetic characteristics. The Warrior, Black Prince, and Achilles, of 6100 tons, are types of the largest size iron-built and iron-plated ships of war ; they are 380 feet long, 58 feet beam, 26 feet draught of water, propelled by engines of 1250 horse-power, and carry from forty to twenty heavy guns. 3750 tons of iron is used in the construction of the hull, which varies in thickness from 1^ inch near the keel to f inch behind the armour-plates. For the Achilles 1200 tons of iron 4^ inches thick was employed for the armour-plating. The Hector and Valiant of 4100 tons, and the Defence and Resistance of 3700 tons, are types of the medium and smaller-sized iron-built and iron-plated ships of war. In the general features of construction they are similar to the Warrior, Black Prince, and Achilles ; all are frigate-built, or with a main deck for the principal battery of guns, 2 r 2 290 STAFF COMMANDER EVANS AND MR. A. SMITH ON THE MAGNETIC and the only wood used in the hulls, with the exception of teak-wood backing to the armour plates, is for the surface covering of the iron decks, and for the personal arrangements and accommodation of the crews. In the Warrior, Black Prince, Defence, and Resistance, the armour-plating of 4^-inch iron is not continued to the bow or stem, but where it terminates is continued from side to side of the ship as an armour bulkhead. In the Achilles, Hector, and Valiant, the armour plating is continued round the ship, but of smaller dimensions near the bow and stern, and with corresponding smaller transverse-armour bulkheads. The Royal Oak, Prince Consort, Caledonia, and Ocean, of 4050 tons, 800 to 1000 horse-power engines, and carrying thirty-five heavy guns, are types of the largest-sized wood-built iron plated-ships ; the hull, with the exception of the iron upper deck and its supporting iron beams and uprights, is entirely constructed of wood ; the exterior of the hull to 4 feet below the water-line (in this respect similar to the iron-built ships) is plated with 4|-inch iron entirely round. The Enterprise, of 993 tons, is the type of the smaller-sized wood-built ship ; she is constructed to carry four heavy guns within a square battery of 4^-inch iron, and has a continuous armour belt of 4|-inch iron round the ship ; the upper deck, deck beams, and top sides are of thin plate-iron. The Royal Sovereign, of 3765 tons, is an experimental class of vessel; she was origin- ally a wood-built three-decked ship of 110 guns, but now cut down to the lower-gun deck, plated continuously round with 5^-inch iron, and with an iron upper deck and bul works. The armament of five guns of large calibre is worked within four turrets ; the iron frame of these turrets varies in thickness from 5^ to 10 inches ; and the largest, arranged to carry two guns, weighs 146 tons. The internal arrangements of all these classes of ships allow little room for selection in the position of the compasses. The accurate drawings, kindly furnished by the Department of the Controller of the Navy, enables their several positions to he shown with reference to the most important masses of iron. CHARACTER OE THE ARMOUR-PLATED SHIPS OF THE ROYAL NAVY. 291 TABLES OF COEFFICIENTS. I. Iron-plated, Iron-built Ships. II. Iron-plated, Wood-built Ships. III. Iron-built Ships, Her Majesty’s Navy. IV. Iron-built Ships, Mercantile Marine. Table op Terrestrial Magnetic Elements employed in discussion OP MAGNETIC COEFFICIENTS. 292 STAFF COMMANDER EVANS AND MR. A. SMITH ON THE MAGNETIC Table I. — Iron-plated, Iron-built Ships. Compass. Approximate coefficients. A B c D E 51 S3 e $ • e 1" r p piiec Standard. Greenhithe . . Sept. 16, 17, 1861 +1 7 -24 15 - 7 42 + 9 23 0 1 +0 39 +•019 -•449 -124 +•164 +•010 « 19, Portsmouth. . Oct. 15, 17, 1861 -1 0 -22 12 - 5 52 + 8 56 +0 44 -•017 -•409 -•092 + •155 +•013 in 19 Gibraltar ...Feb. 1862 -IS 51 — 6 0 + 8 20 +0 23 --293 -•095 +-I45 +•006 s ■9 Portsmouth... July 28, 29, 1862 -0 12 -17 24 - 7 9 + 8 27 + 1 8 -•003 -•321 -•114 +•148 +•020 ■Ml 19 Gibraltar ...Nov. 1862 + 1 0 -14 39 - 4 5° + 8 25 -0 43 +•017 —•272 -•077 +•146 —•012 ± P ■9 f Heeled 7-J0 to Fort +0 50 14 43 + 6 45 + 8 9 +° 59 +•015 -•272 +•108 +•*43 +•017 hi If in Lisbon -I Upright, Jan. 1863 ... +0 50 — H 33 - 3 34 + 7 48 —0 24 +•015 —•269 -■057 +•136 -•007 ■" *6 P t Heeled 7I,-0 to Starboard +0 44 -15 36 -13 37 + 8 17 -0 45 +•013 -•287 —•216 +-I45 -•013 * V Devonport ...May 1, 1863 -0 12 -17 10 - 8 18 + 8 26 -0 32 -•003 -•317 -132 +•146 -■009 r 203 Madeira Bee. 28, 30, 1863 -1 59 — 12 56 — 2 48 + 7 15 -0 4 -'°35 -•239 — •046 +■126 —•001: 191 Plymouth ...June 1864 +0 25 -16 45 - 3 24 + 8 44 -0 19 +■007 -•311 -•054 +152 -•005 r 190 Portland Oct. 28, 1864 -0 17 -16 35 - 4 33 + 8 45 -0 41 -•005 -•307 -•072 +•152 -■012 1® 193 Starboard Greenhithe ...Sept. 16, 17, 1861 +0 20 -20 19 - 7 35 + 15 28 -0 7 +•006 -•395 -111 +•268 -•002 f 195; steering. Portsmouth... Oct. 15, 17, 1861 +0 12 -20 37 - 6 37 +15 51 -0 11 +■003 -•402 -•098 +■273 -•003 Ml 193j Portsmouth... July 28, 1862 -1 48 -15 31 - 7 50 + 11 56 +0 43 -031 -•296 -•121 +•208 +•012 Jin 202 Devonport ...May 1, 1863 -0 7 -16 28 -10 24 + 12 3 -0 31 -•002 -•312 -•160 +•210 -•009 js 20/ Main deck. Greenhithe ...Sept. 11, 1861 -0 30 -25 56. -12 6 +10 58 -1 15 1 [ Greenhithe ...Sept. 16, 17, 1861 +0 55 -22 34 - 7 49 + 11 43 -1 46 Standard. Greenock1 ... Nov. 1861 +0 10 +23 0 + 3 41 + 8 19 +0 25 +•003 +•422 +•058 +•145 +•00; 8 Portsmouth... Sept. 2, 1862 +0 49 +20 59 + 4 40 + 7 38 0 0 + 014 +•383 +•074 +•134 •00( u 11 f Heeled to Port +° 57 +15 31 + 9 11 + 6 45 +1 50 +•016 + '282 +•148 +•117 +•035 *?{ Lisbon \ Upright, Jan. 1863 ... —0 1 +15 39 + 3 12 + 7 24 — I 20 •000 +•288 +•052 +•129 — •02'; h ioj y Heeled 6£° to Starboard +0 1 + 15 14 — 2 6 + 7 14 -I 25 •000 +•280 -•034 +•126 — •021! 353 Portland J une and July 1863 +0 2 +21 8 + 4 10 + 7 6 +0 51 •000 +•384 +•067 +•124 +•011 lj» 10 Madeira Jan. 1864 -0 25 + 13 12 + 4 29 + 7 *9 —0 6 —•007 +•243 +•072 +•128 -■00 » .0} Lisbon Jan. and Feb. 1864 +0 2 + iS 8 + 3 59 + 7 20 —0 38 •000 +•278 +•064 +•128 — •oil, i] Portland Mar. and Apr. 1864 + 1 22 +21 16 + 5 24 + 7 54 -0 24 +•024 +•389 +•086 +•137 -•00; ; |P 12} Portland Oct. 1864 +0 30 + 19 5 + 35 + 7 2 -0 3 +•009 +•349 + 050 +•122 -•00; a j Starboard Portsmouth. . . Sept. 2, 1862 +2 59 +20 9 + 8 10 + 10 32 + 1 37 + 052 +•379 +•136 +■184 +•02! k nr steering. Plymouth . . . Nov. 1864 +2 19 + 19 40 + 6 13 + 8 18 + 1 45 +•010 + •363 +•103 +•144 +-03( p IS Main deck. Portsmouth...! Sept. 2, 1863 — ! 9 +27 25 + 84 + 13 16 +0 2 -•020 +•516 +•120 +•231 •001 1- :« | 13 Exact coefficients. .((iisimsk ffeilw \0^r Warrior. (6109 tons), Iron-plated, iron hull, 40 guns, 1250 horse-power. Built at Blackwall River Thames ; head N. 3° E. magnetic. Launched Dec. 29, 1860. Plated with head generally to N.W. Black Prince. (6109 tons), Iron-plated, iron hull, 41 guns, 1250 horse-power. Built at Glasgow ; head S. 20’ E. magnetic. Launched Feb. 27, 1861. Plated head South. 1 X observed at Greenock =-804, multiplied by earth’s horizontal force '89='716. “‘tatoj'oi CHAEACTEE OF THE ABMOUB-PLATED SHIPS OF THE EOYAL NAVY. 293 Table I. — Iron-plated, Iron-built Ships. Km um of semicircular deviation V B2+C2 Coefficients of horizontal induction. Part of D from Mean Heeling Heeling coefficients from 9 tan 8 H( ontal force of ship Vi 82+S2*- force to North, X Fore- and-aft, Transverse Fore- and-aft induction. Transverse Vertical force, f* t coefficient to windward , Vertical induction Vertical force and 9 i mnt. Direction. a t e t induction. X in trans- verse iron. induction in vertical t t o O 0 1 0 1 ° 1 0 1 •466 1954 23 | 16 4 154 •419 (■308 \-409 •341 r-z8z {■375 1924 198 1994 196 •873 1-145 +•002 -•256 +0 6 + 8 24 1-399 +1 49 +0 43 + 1 06 1 + +•069 15 ;j '293 (■* 75 \-345 r584 192 + 1 22 +0 32 +0 50 •360 217 19 •344 203 ■860 1163 -•015 -•265 -0 28 + 8 52 1 4 17 [■243 \ -328 •314 r9i 190 174 •316 193 214 •410 1954 21f •414 1934 17| •320 202 •833 1-201 +•006 -•340 +0 14 + 11 46 194 •352 207 •878 M39 +•062 -•306 +2 0 +10 04 234 ■426 8 /•804 1-716 1-396 -180 -•388 -7 15 + 15 40 204! ■390 11 •783 1-277 -112 -•322 -4 4 +11 42 •945 +0 50 +1 1 -0 11 + •048 + 118 16 •318 (•293 \-369 •282 274 104 353 +0 52 +° 43 + 09 204! ■390 10 H /■254 t‘343 164 i5l 1-286 1 -360 »3 778 1-285 — •122 -•322 -4 28 + 11 53 22 •399 I24 •846 M82 -•038 -•270 -1 19 + 9 11 •971 +0 43 +0 48 -0 5 +•045 194 •354 8 ■849 1-178 -•047 - 255 -1 36 + 8 38 21? •404 20 ■760 1-316 -•100 -•380 -3 47 + 14 28 204 j -377 16 •881 1135 +•008 -•246 +0 14 + 8 4 284 •530 13 •757 1-321 -•068 -•418 -2 35 + 15 58 ian force to North (XH) being unit. f Earth’s Horizontal force (H) being unit. % Earth’s Vertical force (Z) being unit. 294 STAFF COMMANDER EVANS AND MR. A. SMITH ON THE MAGNETIC Table I. (continued). — Iron-plated, Iron-built Ships. Approximate coefficients. Exact coefficients. l l Compass. Place. Date. i A B c D E 21 23 g : O f 0 1 0 1 O / 0 1 Standard(aft). Sheerness . . Oct. 12, 13, 1864 -0 16 +19 54 + 2 56 + 6 58 -0 56 -•005 +•362 + 047 + 121 -•01 Plymouth t .. Dec. 5, 1864 -0 35 +19 54 + 7 38 + 6 41 -0 32 -010 +•361 +■123 +•116 -•00 Standard Sheerness ...Oct. 12, 13, 1864 -0 10 +21 42 + 1 11 + 7 19 -0 31 -■003 +•396 + 019 +•128 -■00 (forward). Plymouth . . Dec. 5, 1864 +0 39 + 19 51 + 6 15 + 5 44 -1 01 +•011 +•357 +•102 + 100 -4 Starboard Sheerness . . Oct. 12, 13, 1864 +0 07 +23 31 + 4 10 + 8 51 -1 20 +•002 +•432 + 061 +•154 -02 steering. Plymouth . . Dec. 5, 1864 -0 55 +23 30 + 10 04 + 7 51 -0 30 -016 +•427 +•160 + 137 -00 Main deck Sheerness . . Oct. 12, 13, 1864 -0 47 +12 42 + 2 19 +12 13 +0 21 -014 +•244 +•031 +•214 +•00 (starboard). Plymouth . . Dec. 5, 1864 -1 11 +14 17 + 3 49 +10 46 +1 23 -•021 +•271 +•059 + 188 +•02 - Standard. Sheerness ...Feb. 17, 18, 1862 -0 28 +25 43 + 0 17 + 7 0 +0 5 -•008 +•464 + 005 +•122 +-001 Baltic Sea ...July and Aug. 1862 -0 17 +2 * * S.5 35 - 0 25 + 6 25 —0 41 —•005 +•463 — •007 +•112 —•01 Gibraltar . . .Nov. 15, 1862 +0 16 + 15 21 - 4 15 + 69 +0 25 +•005 +■280 —•069 +•107 +'°°! ! f Heeled to Port + 1 47 + 16 39 + 2 49 + 7 18 +1 50 +•031 +'3°5 +•045 +•127 +•03 , Lisbon < Upright, Jan. 1863 ... + 1 41 + 16 26 - 1 5 + 74 +0 42 +•029 +•302 — ■018 +-i*3 +‘°1 ■' (_ Heeled 7J6 to Starboard + 1 38 + 16 27 - 4 40 + 70 -0 5 +■028 +-3°i -•075 +•122 +■0(1 li Flushing &1 Portsmouth J March 3, 21, 1863 +0 5 +20 50 - 2 8 + 6 50 -0 11 +•001 +•379 -•034 + 119 -Oflj Plymouth . . , Tenerife .Dec. 1863 + 1 6 +22 18 - 0 57 + 6 59 -0 7 +•019 +■403 + •292 -016 + 122 +•114 -•00.; .Jan. 2, 3, 1864 ... —•040 Gibraltar . . .Jan. 9, 13, 1864... — 1 0 + 15 25 - 1 44 + 6 30 —0 46 -•017 +•282 — ■928 + ■113 —•oil Lisbon .Jan. and Feb. 1864 +0 40 + 16 37 - 1 18 + 6 22 -0 7 + •012 + ‘3°3 — •021 +■111 — -oc Portland .Mar. and Apr. 1 864 +0 21 +21 37 - 0 24 + 6 26 -0 24 +•005 + •391 -•007 + 112 — oc ; Portland Oct 1864 -0 23 +20 55 -26 + 6 23 +0 10 -007 +■379 -034 +•112 +’0( Starboard Sheerness . . .Feb. 17, 18, 1862 +0 16 + 36 14 + 0 56 +10 16 + 1 7 +•005 +•653 +•014 +•179 + 011 steering. Plymouth . . Portland & 1 Downs ... J Dec. 1863 +1 4 +31 18 - 1 21 + 10 19 +0 36 +•019 +•572 -•020 + 180 +•01 Apr. and May 1864 + 014 +•586 -•030 +•159 +01 Devonport .. .Nov. 1864 +•546 -056 + 159 ... Main deck. Sheerness . . .Feb. 17, 18, 1862 -0 51 +36 23 + 0 42 + 14 35 -0 55 -•015 + •669 +•010 +•254 -0,| Plymouth . . Portland &1 Downs ... J .Dec. 1863 + 1 16 +26 44 + 0 34 + 13 10 -0 6 + 022 +•505 +•009 +•230 -•oc; Apr. and May, 1863 + 019 +•450 +•004 +•233 -•01 Devonport .. Nov 1864 +•486 -030 +•230 J Achilles*. (6121 tons). Iron-cased, iron hull, 20 guns, 1250 horse-power. Built at Chatham, and fully plated in dock ; head S. 51° 40' E. magnetic. Floated outofdock Dec. 24, 1863. Defence. (3720 tons). Iron-plated, iron hull, 16 guns, 600 horse-power. Built on River Tyne ; head S. 47° W. magnetic Launched Apr. 24, 1861. Plated with head S. 19° E. magnetic. S3 •464 * A ™tt fa tw o ij 1 »S3 Starboard steering. Sheerness ...Jan. 12, 16, 1865... +2 7 + 7 35 -20 12 + 6 52 -0 14 +•037 ■ +•138 -•325 +•120 -•00 — Main deck (Starboard). Sheerness ...Jan. 12, 16, 1865... +2 35 + 5 29 -18 39 + 85 -0 12 +■045 +•101 -•297 +•142 —00 11 2® (l) Hector, June 9, 1863. In basin at Portsmouth, by observations of Deviation and Horizontal force on one point, and employing X and D of February 1864, B= + -398, C = + '159. CHAEACTEE OE THE AEM OTJE-PL ATED SHIPS OP THE EOTAL NAVY. 297 Table I. (continued). — Iron-plated, Iron-built Ships. a Mas um of semicircular deviation V B2+C2 Mean Coefficients of horizontal induction. Part of D from Mean Vertical force, P Heeling coefficient Heeling coefficients from Ho mtal force of ship /W+W2*. North, X X Fore- and-aft, Transverse Fore- Transverse windward, X Vertical induction Vertical force and g tan0 9 unt. Direction. t t t induction. induction. t in vertical iron. t t ~ "1 o ° / 0 / 0 1 ° / 0 ! 12*| •218 313 •758 1-319 -•158 -•326 -5 55 +12 21 1071 +1 18 +1 4 +0 14 +•071 +•176 r-i29 1-162 3°5* m •205 317f 9* •160 311* •850 1-176 -046 -•254 -1 33 +8 34 1044 +0 53 +0 45 +0 8 +•076 +•190 6* /’JO 7 \ -158 285* 7* /•124 I-J83 291 19 •312 298 ■703 1-423 -•193 -•401 -7 53 + 16 33 m •290 313 151 •266 313 19* •316 305 •782 1-279 -•027 -•409 -1 2 + 15 11 16 •266 311 114 •187 292 •880 1-136 +■073 -■313 +2 25 +10 15 24* •400 12* •814 1-228 -■109 -•263 -3 51 + 9 15 •983 +0 45 +0 48 -0 3 -•005 -•013 33* •568 16* •791 1-264 -•093 -•325 -3 23 + 11 49 34* •572 25 •726 1-377 -151 —397 -5 58 +15 54 13 •216 282* •859 M64 -•068 -•214 -2 14 + 7 11 1-061 +0 48 +0 37 +0 11 +•048 +•120 21* •353 293 •817 1-224 -•085 -•281 -2 59 + 9 54 19* •313 288* •722 1-385 -•176 -•380 -6 56 +15 14 ean force to North (\H) being unit. f Earth’s Horizontal force (H) being unit. + Earth’s Vertical force (Z) being unit. 2 s 2 298 STAFF COMMANDER EVANS AND MR. A. SMITH ON THE MAGNETIC Table II. — Iron-plated, Wood-built Ships. Ship. Compass. Place. Date. Approximate coefficients. Exact coefficients. A B 1 \° D E 21 25 (£ © a Royal Oak. Iron-cased, wood-built, 4056 tons, 35 guns, 800 horse-power. Iron-plated ; head S. 49° E. Floated out of dock March 19, 1863. Standard. Chatham Mar. 19, 1863 Chatham Apr. 11, 1863 Sheerness June 2, 1 863 Plymouth ...Jan. 8, 1864 Malta Mar. i, 1864 0 1 -0 39 -0 12 -1 9 +13 56 + 12 20 + 88 + 7 26 + 10 9 + 6 1 + 39 + 2 19 + 2 58 ° 1 +0 1 +0 20 — 0 48 -011 -•003 — '020 +•253 + •231 +•248 +•218 +'H3 + ■287 + 197 +•128 +•172 + *I08 +•047 + •061 + •055 +•040 +•052 2 •00 +-0uij — *0 1.j Starboard steering. Chatham Apr. 11, 1863 Sheerness June 2, 1863 +0 15 +24 5 + 14 25 + 1 47 + 1 17 +•004 +•377 +•414 +•379 + •241 + 067 + 031 +•02: Main deck. "Sheemess J une 2, 1863 -1 54 +32 22 + 12 47 + 1 28 -0 11 -•033 +•546 +■210 + ■026 —•00: Prince Consort. Iron-eased, wood-built, 4045 tons, 35 guns, 1 000 horse-power. Iron-plated ; j heads. 39° W. Standard. Milford May 25, 1863 Plymouth ...Feb. 9, 1864 -0 6 -0 28 +33 39 +25 36 -13 41 - 3 53 + 2 18 + 36 -0 4 -0 33 -001 -008 + •569 +•447 -•222 -•064 + 040 +•054 -00 -•01 Caledonia. Iron-cased, wood-built, 4125 tons, 35 guns. 1000 horse-power. Iron-plated ; headS. 26° W. Standard. Sheerness June 15, 1864 +0 18 +25 47 - 8 21 + 2-57 +0 20 + •005 +■448 -•138 +•051 ; +-00i Ocean. Iron-cased, wood-built, 4047 tons, 35 guns. 1000 horse-power. Iron-plated ; head S. 79° E. Standard. Devonport ...Aug. 3, 1864 +0 8 +13 2 + 15 23 + 2 31 -0 4 + •002 + •229 +■259 +•044 — 00 Royal Sovereign. Iron-cased, wood-built, turret ship of 1 5 guns, 3765 tons, 800 horse-power. Iron-plated ; head S. 72° E. 1 Standard. Portsmouth... July 21, 22, 1864 -0 3 + 12 38 + 13 39 + 7 41 +0 7 -•001 +•233 + •219 +•134 +■00 Steering wheel (upper deck). Portsmouth. . .July 21, 22, 1864 -1 8 +23 30 -19 40 + 13 3 -9 14 -022 +•487 -•323 +•238 -•15l Steering wheel (Cap.’s cabin). Portsmouth... July 21, 22, 1864 -0 25 +20 11 + 4 56 + 6 20 -5 10 -•007 +•364 +•086 + 110 -•09 Starbaforward (lower deck). Portsmouth... July 21, 22, 1864 -0 37 -13 15 +40 15 + 15 43 -4 42 -•004 -•277 + ■563 +•272 -07 Port, forward (lower deck). Portsmouth... July 21, 22, 1864 +6 42 -14 35 -78 + 13 23 +4 38 +•117 -•286 -•119 + ■233 +-08i +•01 Suspended over fore- turret. Portsmouth. . .July 21, 22, 1864 +1 0 -19 33 + 9 23 + 89 + 0 1 Enterprise \ (993 tons), 4 guns, 160 h.-p. screw. Built and plated at Deptford; head S.56°W. Launched February 1864. Standard. Greenhithe ...June 7, 1864 + 1 24 +14 42 -18 45 + 2 34 +0 35 +•025 +•257 -•312 +•045 ■ Wolverene 2. (703 tons), 2 1 guns, 400 h. p. screw. Built at Woolwich; head S.S.W. Launched in 1863. Standard. Greenhithe ...May 31, 1864 +0 23 + 14 10 - 2 11 + 3 20 +0 46 +•007 +•253 -•036 ■ +•058 ■ +01 1 Wood bottom, Iron-cased, with central iron battery. Iron topsides, decks and beams. a Wood hull, iron beams and stanchions. CHARACTER OF THE ARMOUR-PLATED SHIPS OF THE ROYAL KAVY. 299 Table II. — Iron-plated, Wood-built Ships. Maa um of semicircular deTiation Coefficients of horizontal induction. Part of D from Heeling coefficients from VB2+C2 Mean Mean Heeling Ho jntal toree ot ship Vi82+S'2* force to North, X Fore- and-aft, Transverse Fore- and-aft induction. Transverse Vertical force. t coefficient windward, Vertical induction Vertical force and J7_ tan 0 9 A unt. Direction. t a + t induction. X in trans- verse iron. induction in vertical iron. t t 0 •382 48| •861 1-162 -•098 -•178 ° \ -3 16 + 62 ° 1 ° i ° 1 1 ■304 40* •907 1102 -038 -•148 -1 12 + 4 39 •896 +0 7 +0 24 -0 17 +■018 + 045 51 •280 27* •907 1-102 -043 -143 -1 19 + 4 32 •882 +0 4 +0 23 -0 19 +■052 +•127 6 0 •278 S'I79 [-264 38 37 •534 45 •887 1127 -054 - 172 -1 43 + 5 30 8 •480 30 •906 1104 -•066 -•122 -2 7 + 3 51 If •586 21 •862 1160 -•116 -160 -3 51 + 5 20 J •612 339 •840 1190 -•126 -•194 -4 18 + 6 36 6 ■452 352 •950 1053 + •001 -101 0 0 + 36 •848 -0 8 +0 16 -0 24 +•015 +•038 !7 •469 343 •895 1117 -059 -•151 -1 53 + 4 46 •346 48* •923 1083 -■036 -118 -1 9 + 3 40 •929 -0 15 +0 19 -0 34 + 045 +•112 18* •320 43* ■912 1-097 + •044 -•204 + 1 5 + 6 36 50* ■584 326 •980 1020 +•202 -■212 +5 58 + 7 7 ■374 13* •917 1091 +•028 -•184 +0 34 + 5 45 Ml? •629 116 •783 1277 -•003 -•431 -0 2 + 15 55 16* ■310 203 ■811 1-233 ■000 -■379 0 0 + 13 25 23f •406 309* •817 1-224 -146 +■220 -5 6 + 7 44 •622 -0 29 +0 37 -1 9 +•062 +•152 •256 352 •962 1039 + 018 -094 +0 35 + 2 45 •953 + 0 7 +0 14 -0 7 L # M a force to North (\H) being unit. t Earth’s Horizontal force (H) being unit. J Earth’s Vertical force (Z) being unit. 300 STAFF COMMANDEE EVANS AND ME, A. SMITH ON THE MAGNETIC Table III. — Iron-built Ships, Her Majesty’s Navy. deviation lib! I®*1 Ship. Compass. Place. Date. Approximate coefficients. Exact coefficients. A B C D E 2t S3 e lit Orontes. (2812 tons), 4 guns, 500 h.-p., screw. Built at Birkenhead ; head N. 66° W. magnetic. Launched Nov. 22, 1862. Standard. Plymouth ...May 26, 1863 Portsmouth ...July 7, 1863 G.ofGoodHope, Nov. 1864 -0 31 -0 2 -1 40 0 1 - 7 45 - 6 55 “ 9 39 0 ! -12 20 -12 0 — 10 41 +5 46 +5 30 +5 49 0 1 -0 24 -0 13 0 0 -009 •000 — •029 -141 -•125 -•177 -•203 -•198 -•178 +•100 +•096 +•101 -•007 -•004 •ooc U •234 F p Starboard steering. Portsmouth ...July 7, 1863 -0 43 -10 27 -13 7 +7 16 -0 22 -•012 -•191 -■213 +•126 — 00( u Tamar. (2812 tons), 4 guns, 500 h.-p., screw. Built at Millwall, River Thames ; head West. Launched Jan. 5, 1863. Standard. Sheerness Nov. 21, 23, 1863 Portsmouth ...Oct. 1864 +0 18 +0 4 + 1 42 + 2 11 -10 49 - 5 26 +3 18 +3 11 +0 33 +0 22 +•005 +•001 +■031 +•038 -•184 -•095 +■058 +•056 +■011 + 001 f ■» Starboard steering. Sheerness Nov. 21, 23, 1863 -1 50 + 7 15 -17 14 +3 27 +0 8 -•032 +•128 -•288 +•060 +-ooJ ■SIS Adventure. (1794 tons), 400 horse-power, screw. Built at Birkenhead. Launched Feb. 17, 1855. Standard. Greenhithe . . .April 26, 1 862 . . . Greenhithe ...Oct. 28, 1862 .. . Yokohama, Japan. . .Nov. 1 1 , 1 864. +0 2 +0 8 - 4 5 - 3 59 - 3 28 + 10 59 + 10 59 + 8 4 +2 56 +2 53 +2 49 +0 26 +0 10 —0 19 ■000 +•002 -073 -•071 — •061 +•186 +■186 +-I39 + 051 +•050 + ‘°49 +-00'| +•00 i* -B 1* Dromedary. (647 tons), 100 horse-power, screw. Standard. Greenhithe ...July 8, 1862 Greenhithe .. .Dec. 16, 1862 -f"V 32 +0 21 + 50 + 4 59 -11 50 -10 55 +6 0 +5 33 +0 14 +0 44 +■009 +•006 +■091 +•091 -•194 -•179 +•104 +■097 +•041 +•01; L # Wye. (700 tons), 100 horse-power, screw. Standard. Greenhithe ...Sept. 1, 1863 +0 25 + 3 24 +10 50 + 1 31 +0 5 +•007 +•059 +•186 +•026 +•00 H Caradoc. (676 tons), Paddle-wheel, 350 h.-p. Built at Blackwall. Launched July 1847. Standard. Greenhithe ...Feb. 12, 1863 -0 43 -13 28 - 2 54 +2 3 -0 7 -•012 -■238 -049 +•036 —•00 !ffl ; *1 1 Industry. (638 tons), Screw, 80 horse-power. Built at Blackwall. Launched 1854. Standard. Greenhithe ..March 14, 1863 ... -0 13 + 11 32 - 2 16 +2 58 -0 6 -•004 +•206 -•038 +•052 -■00 Supply. (638 tons), Screw, 80 horse-power. Built at Blackwall. Launched June 1854. Standard. Greenhithe ...Oct. 17, 1863 -0 12 -13 32 - 1 40 +2 55 +0 16 -•003 -•240 -•028 + ■051 +•00 CHARACTER OF THE ARMOUR-PLATED SHIPS OF THE ROYAL NAVY. 301 Table III. — Iron-built Ships, Her Majesty’s Navy. Mai um of semicircular deviation VB2+C2 Mean Coefficients of horizontal induction. Part of D from Mean Heeling Heeling coefficients from Ho >ntal force of ship $%*+<§?*. North, A A Fore- and-aft, Transverse Fore- Transverse Vertical force, (* coefficient to windward Vertical 1 induction Vertical force and 9 tune 9 A unt. Direction. t t t induction. induction. * verse iron. in vertical t t „ o ° / o , ° 1 0 / ° 1 14* •247 235 14 •234 238 •875 1-143 -041 -•209 -1 22 +6 40 1-164 + 1 4 +0 36 +0 28 + 023 +•056 i4* r-a5i \-293 2Z5 17 •286 228 •862 1-160 -•029 -•247 -0 58 +8 13 11 •187 279| •870 1-150 -•080 -•180 -2 38 +5 58 1-317 +0 51 +0 31 +0 20 +•060 +•147 6 •102 292 18 J •315 294 •886 1-129 -■061 -•167 -2 0 +5 27 1-248 + 1 10 +0 28 +0 42 +•120 +•294 U| ■200 111 •922 1-085 -031 -•125 -1 0 +3 56 H| •199 111 ■918 1-090 -•035 -•129 -1 8 +4 1 9 r-i5i V249 -II3 12f] •215 295 ■841 M86 -•072 -•246 -2 21 +8 21 12 •201 297 •861 1-161 -•056 — •222 -1 50 +7 28 ll*j •395 72 •869 1151 -•108 -154 -3 34 + Ox 1195 + 1 0 +0 27 +0 34 +•103 +•252 13f •243 191* •945 1058 - 021 -•089 -0 38 +2 42 1 002 +0 15 +0 14 +0 1 HI •209 3491 •937 1-067 -014 -112 -0 41 +3 40 •859 -0 5 +0 18 -0 23 13| •242 186£ •925 1-081 -•028 -•122 -0 55 +3 47 * M 1 force to North (\H) being unit. f Earth’s Horizontal force (H) being unit. Earth’s Vertical force (Z) being unit. 302 STAFF COMMANDER EVANS AND MR. A. SMITH ON THE MAGNETIC Table IV. — Iron-built Ships, Mercantile Marine. Ship. Compass. Place. Date Approximate coefficients. Exact coefficients. A B C D E % 35 e m @ ' ° 1 o / ° I ° / ° t Rainbow1 Station No. 1 Deptford July and Aug. 1 838 +0 40 — 50 36 -11 4 + 1 23 +0 38 + 012 -•802 -•173 +•024 +•01 „ No. 2 +0 3o -18 45 -12 57 +2 30 +0 2 +•010 -•327 -•217 +•044 +•00 „ No. 3 +0 42 -15 46 -10 39 +3 7 -0 2 + 012 -•279 -•181 +•054 -•00, „ No. 4 +0 5 - 8 5 - 9 33 +3 26 +0 2 +•001 — •145 -•161 +•060 ■ + •00 1 Ironsides2 . . . Binnacle, or Liverpool ... Oct 27, 1838 . . 0 0 -24 16 +20 50 +2 15 — 0 1 •000 -•416 +•346 +•039 ■00 i steering. l Great Eastern3 Standard River Thames... Sept. 7, 1859 ... -0 10 +23 13 +25 38 +4 21 -0 37 -•003 + •402 +•408 +■076 -•01 position. Portland ....Sept. 12, 1859... -1 3 +22 42 + 16 43 +4 44 -0 45 -•018 +•400 +•27 2 +•082 -•01 Compass aft River Thames... Sept. 7, 8, 1859 -l 40 +13 34 +22 41 +7 55 -0 12 -•029 +•247 +•359 +•138 -•00 on platform. Compass on River Thames... Sept. 8, 1859 ... +0 3 +31 56 + 17 47 +4 31 -0 9 +•001 +•551 +•282 +•079 -•00 fore bridge. • Clyde Standard (rrcenhithe ...T?eh. 21. 1863 +0 41 - 7 56 + 7 25 +4 43 +0 8 +•012 -143 +•124 + •082 • +•00 position. City op Sydney. . . Standard Greenhithe ... .June 13, 1863 + 1 27 - 3 29 -18 51 +4 32 +0 23 +•025 -063 -•311 +•079 +•00 position. ^(00“ feriton IPL-r fT' « | 19 C j 21 I* I 21 ill I 14 I ill | 45 34 ■® ! 55] a 1 2? « 258 ft. in. ft. in. 1 Station No. 1, (near the binnacle) 13 2 distant from the extreme part of stern, 4 0,)- from deck. ,, 2, 31 9 ,, 3, 48 3 4 f 151 6 \ „ ” ’ { 47 0 from knight head of stem J „ „ 2 See Philosophical Transactions, 1839, Part I. p. 206. 3 See Philosophical Transactions, 1860, Part II. p. 375. See Philosophical Transactions, 1839, Part I. p. 167. ctetoXortl Table of Terrestrial Magnetic Elements. [1864.] Place. In British absolute units. Dip 6. Tan i. Horizontal force at Greenwich being unit*. Horizontal force. Vertical force. Horizontal force. Vertical force. Greenwich 3-83 + 9-53 + 68 7 + 2*49 1-00 + 2-49 Greenhithe 3-84 + 9*50 + 68 5 + 2*48 1-00 + 2-48 Sheerness 3*83 + 9*50 + 68 2 + 2-48 1-00 + 2-48 Portsmouth 3-86 + 9*48 + 67 50 + 2*45 1-01 + 2-47 Portland 3-88 + 9-50 + 67 45 + 2-44 1-01 + 2-47 Plymouth 3-86 + 9-54 + 67 58 + 2-47 1*01 + 2*49 Milford 3-62 + 9-80 + 69 44 + 2-71 •95 + 2-56 Greenock 3-38 + 10-04 + 71 23 + 2-97 •88 + 2-63 For British absolute units multiply by 3-83. For Foreign absolute units multiply by 1-76. 11 CHARACTER OF THE ARMOUR-PLATED SHIPS OF THE ROYAL NAVY. 303 Table IV. — Iron-built Ships, Mercantile Marine. Alaxi m of semicircular deviation V B*+C» Mean force to North, X t X Coefficients of horizontal induction. I Part of D from Mean vertical force, Heeling coefficient. windward , * Heeling coefficients from 9 tan 0 9 t Hori ital force of ship !&+&*■ Fore- and-aft a t Transvers< e t Fore- and-aft induction. Transverse ^induction. Vertical induction in trans- verse iron Vertical force and induction in vertical Am * Direction. - o ° i ° 1 ° i o / •822 192 •984 1016 +•008 -■040 +0 14 + 1 9 2J •392 213 •972 1029 +•015 -071 +0 24 +2 7 •332 213 i 1-003 •997 +•057 -•050 +1 40 + 1 26 •217 228 •999 1001 +•060 -•060 + 1 43 + 1 43 2 ■542 140 •914 1-094 -•050 -•122 -1 33 +3 50 . -574 45iV •791 1-264 -•072 -192 -3 50 +8 13 ;-4S4 34£ •775 1-291 -•082 -•209 -4 4 +8 48 H [i •438 55 £ •897 1115 +•066 -•182 +0 38 +7 18 H 1 •619 27 •892 1121 -•038 -•178 -4 38 +9 16 1 •189 139 ■870 1149 -•059 -•201 -1 57 +6 39 1 1-275 1 22 +0 35 +0 47 l H •158 258J •816 1-225 -•120 -■248 -4 8 +8 44 1-246 1 31 +0 46 +0 45 * Me force to North (\H) being unit. f Earth’s Horizontal force (H) being unit. X Earth’s Vertical force (Z) being unit. Table of Terrestrial Magnetic Elements. [1864.] Place. In British absolute units. Dip 6. Tan 6. Horizontal force at Greenwich being unit || . Horizontal force. Vertical force. Horizontal force. 1 Vertical force. Lisbon 4-82 + 8-46 + 7*89 + 8-27 + 8-10 + 7*29 -6-43 + 7-08 + 60 23 + 1-76 + 1-55 + 1-60 + 1-49 + 1-29 -1-44 + 1*12 1-26 + 2-21 Gibraltar 5-09 5-17 5*44 + 57 9 + 57 55 + 56 10 + 52 20 1 — 55 8 + 48 10 1-33 + 2-06 Madeira 1-35 + 2-16 + 2-12 Teneriffe 1*42 Malta 5-65 1*47 + 1-90 — 1*68 + 1-85 Simons Bay, Cape of Good Hope Yokohama, Japan J 4-48 6-32 M7 1-65 MDCCCLXV. f For British absolute units multiply by 3-83. I For Foreign absolute units multiply by 1’76. 2 T 304 STAFF COMMANDER EVANS AND ME. A. SMITH ON THE MAGNETIC ON THE EFFECT ON THE COMPASS OF PAETICULAB MASSES OF SOFT IRON IN A SHIP*. The form of the general equations for the effect of the soft iron of a ship on the compass does not, as we have seen, depend on the form, position, or inductive capacity of the iron. They involve, it is true, nine coefficients which depend on these particulars, but the data of the problem are in general not these particulars, but the effects which they cause in certain definite positions of the ship. This is fortunate, because, while the form of the general equations is obtained at once from very simple physical considera- tions, and while the special formulae required are deduced from these by simple trigono- metrical operations, and the coefficients are then deduced from the observations by a simple arithmetical operation, the a priori determination of the effect on the compass of given masses of iron is, in all but the very simplest cases, a matter of great and gene- rally insuperable difficulty. It is however in all cases interesting, and in some cases important, to be able to form an approximate estimate of the nature and amount of the effects on the compass of particular masses of iron, and although the precise cases of masses of iron in which the problem admits of an exact solution may not often occur, yet cases frequently occur of masses of iron sufficiently resembling them to have much light thrown on their effects by the knowledge of the effect of the simpler bodies which they most nearly resemble. The most general case for which the problem can be solved is that of ellipsoids and ellipsoidal shells, including the forms into which these degenerate, as spheres, spheroids, plates, cylinders, &c., but the general solution is so extremely unmanageable, in its practical application, that it is more convenient to consider the simpler cases indepen- dently. The cases which we shall consider are — 1. Infinitely thin rods of finite or infinitesimal length. 2. Infinitely thin plates of finite dimensions magnetized longitudinally. 3. Infinite plates of finite thickness magnetized perpendicularly. 4. Spheres. 5. Spherical shells. 6. Infinitely long cylinders magnetized perpendicularly. 7. Infinitely long cylindrical shells magnetized perpendicularly. A little consideration will show that there is hardly any arrangement of iron in a ship which does not bear more or less resemblance to one or other of these cases. The physical theory of Coulomb, on which Poisson’s mathematical theory is based, supposes, as is well known, that there is no separation of two kinds of magnetism except within infinitely small elements of the iron ; but on this theory, if the iron be homoge- * I beg to express my obligations to Professor W. Thomson for much of what is contained in this part of the paper, and at the same time to express my hope that he may be induced to complete the promised Treatise on the Mathematical Theory of Magnetism, part of which was published in the Phil. Trans. 1851. — A. S. CHARACTER OF THE ARMOUR-PLATED SHIPS OF THE ROYAL NAVY. 305 neons, the result on all external bodies is precisely the same as that of a certain distri- bution of North and South magnetism on the surface of the iron. To avoid the ambiguity which arises from the use of the terms “ North” and “ South” magnetism, we shall speak of the magnetism of the north end of the needle and the southern hemisphere of the earth as red magnetism, of the south end of the needle and the northern hemisphere as blue magnetism. I. An infinitely thin rod. Let S be the area of a section of the rod, F the component of the earth’s force in the direction of the rod, and x a coefficient depending on the inductive capacity of the iron. Each end of the rod will have a quantity of free magnetism =«SF, the magnetism being red at the north end, blue at the south end of the rod. If x, y, z be the coordinates, r the distance of the blue end, A, y', z' the coordinates, / the distance of the red end, l the length of the rod, X, Y, Z the components of the earth’s force, then the effect of the rod on a red particle at the origin is a force Towards x=xS (jp—ps) Y+ “-77-Z To war Towards ds y=x S (y-y) j: *-*x+/ iT+'-fl®, -X+S^Y If the rod be infinitely short, and x’ — x=dx, y' —y=dy, z1 — z—dz, l=ds, then force Towards dsl~x (x dx y dy z ds 1 2. r ds'rds ' r ds dx\(dx dy dz \ Towards y—x S- dx y ds + 1 dJ) _M Jf x+§A+M r ds 1 r ds J risj yds 1 ds ' ds y Towards If the rod be in the plane of x, y and parallel to the axis of x, then z, dy and dz— 0, and force Towards x- Towards y = ^ 3fX, Towards 2 = 0. If the rod be in the axis of x, then x==r, and the force is 2 y^X in the direction of -\-x. If the rod be in the axis of y , then #=0, and the force is ^Tf X in the direction of — x. The. product «S£X is called the moment of the magnetic rod. 2 t 2 306 STAFF COMMANDER EVANS AND MR. A. SMITH ON THE MAGNETIC We will now pause to state what is known of the value of * for iron of different kinds. The coefficient * is the quantity so designated by Neumann in Crelle’s Journal, vol. xxxvii. p. 21, Weber in Gotting. Trans, vol. vi. p. 20, and Thalen in Nov. Act. Soc. Reg. Upsal. 1861. It is related to the Tc of Poisson’s papers in the fifth volume of the ‘ Memoires de l’lnstitut,’ and to the g of Green’s celebrated “ Essay on the Mathematical Theories of Electricity and Magnetism ” (Nottingham, 1828 ; reprinted in Crelle’s Journal, vol. xlvii.), by the equation 47 r — X Green, in the essay referred to, finds, from some experiments of Coulomb on steel wire, ^=•986636, whence *=17-625. Weber finds the following values of * : Steel tempered to glass hardness and already magnetized . . . 4-091 Steel tempered to glass hardness with no permanent magnetism . 4-934 Soft steel 5-61 Soft iron 36 Thalen finds, from six specimens of soft iron carefully annealed, the following values : Specimen. x. 1 34-58 2 3 27-24 45-26 4 32-25 5 44-23 6 36-96 Mean . . . 36- 75 From observations of iron bars given by Scoresby in his 6 Magnetical Investigations,’ vol. ii. p. 320, we derive X. Iron rod, not struck 16-77 Iron rod, struck .... ... 44*07 From observations which we have made with a rod of iron x^-ths of an inch in dia- meter, 3 feet long, we have found X. Iron, not struck . 1^-48 Iron, struck several sharp blows, about 80 Hence probably in the iron plates used in ship-building * may vary from 10 to 30. CHAEACTEE OE THE AEMOUE-PLATED SHIPS OE THE EOYAL NAVY. 307 2. An infinitely thin plate of finite dimensions magnetized longitudinally. If F be the component of the earth’s magnetism in the plane, and perpendicular to any part of the edge, we shall have a distribution of red magnetism on the northern edge of the plate, of blue magnetism on the southern ; and if m be the thickness of the plate, then the force exerted by a part of the blue edge of length ds, or a red particle at a distance r, will be mds and the effect of the whole edge will be given by ordinary integration. Such a plate may in fact be considered as a collection of thin iron rods laid side by side, parallel to the direction of the component of the earth’s force which we are considering. 3. An infinite plate of finite thickness magnetized perpendicularly. Let F be the component of the earth’s force perpendicular to the plate. The northern surface of the plate will have a distribution of red free magnetism, the southern surface of blue ; the amount of each on an element of surface —dS being 1+47TX , ($, K, x ; but there would be no interest in the general solution, as the rods we have to deal with in practice are always parallel to one of the principal axes, and these we shall therefore consider separately. mdccclxv. 2 u 312 STAFF COMMANDER EVANS AND MB. A. SMITH ON THE MAGNETIC Transverse longitudinal masses of Iron extending from side to side as Iron beams. Let m be the length of the beam, or in general the breadth of the vessel, r the distance of either end of the beam from the compass, S the area of the section of the beam. It is easily seen that such a beam will give no coefficient except xS m Every such beam therefore diminishes the directive force and produces a + qua- drantal deviation, the effect being directly proportional to the mass of the beam, inversely proportional to the cube of the distance of its ends. If we have a rectangle of four beams, two fore-and-aft and two transverse, the compass being in or directly above or below the centre of the rectangle, l being the length of the two fore-and-aft beams, m of the two transverse beams, we shall have a=-2zSL / / whence X=1-^S xs l — m T ~r*-' Such beams may be compared to the armour-plating of a ship, and we thus see that for a compass near the centre of the ship, l being greater than m , the effect of such plating will be to diminish the quadrantal deviation. In accordance with this result, we find that in the wood-built iron-plated ships, when the compasses are inside the rectangle of the armour-plating, the quadrantal deviation is very small. When, as in the case of the Warrior and Black Prince, the plating does not extend from end to end, and the compasses are near or even outside one end, the case is different. Thus if the fore-and-aft coordinates of the ends be ad and x, and the distances from the compass r' and r, we shall have a=2*s{-^+*}, e=2*s{-^+^}, _ -As(x+y z'-y] r3 “ r13 f When the plating extends abaft the compass x is negative, and when this is the case, ad being of course greater than y, so long as x is greater than y, or so long as the plating CHARACTER Of THE ARMOUR-PLATED SHIPS OE THE ROYAL NAVY. 313 extends half the breadth of the ship abaft the compass , it will diminish the quadrantal deviation. When — | y—{rf —y)^m }» or when the armour-plating extends a little less than half the breadth abaft the compass, its effect on the quadrantal deviation vanishes, and when the distance is less than that last mentioned, it increases the quadrantal deviation. If the central part of a beam be cut out, and if y and y' be the transverse coordinates, r, r' the distances of its outer and inner extremities from the compass, «=2*s{=£+^}. Hence if such a beam be near the compass so that it will increase the directive force and diminish the quadrantal deviation ; if distant it will have the opposite effect. A vertical rod, z being the vertical coordinate of the upper, z1 of the lower end, x and y being the horizontal coordinates, will produce c —%Sx (k—ptj ’ k =*S ^“3 * The effect which is of most interest is that of k, as it affects the heeling error. If z be negative, z1 positive, or if the upper end of the beam be above and the lower end below the level of the compass, we see that k will be negative, and will in general diminish the heeliug error. If the rod be a short one of length n, here k will be +, as £> JL r<*/3’ or, in other words, if the centre of the rod be within the cone traced out by a line through the compass, making an angle of 54° 45' with the vertical, k will be positive, and the force of the rod will act downwards and increase the heeling error. On the other hand, if the centre of the rod be without the cone, k will be negative, and the force will act upwards and decrease the heeling error. Hence we see that in all cases, except when the compass is raised very much above the upper part of the armour-plates, the effect of armour-plating will be to diminish the heeling error. 2u 2 314 STAFF COMMANDER EVANS AND ME. A. SMITH ON THE MAGNETIC Thin Plate magnetized in its plane. If the compass be above or below the centre of a rectangular plate, which may repre- sent the iron deck of a ship, lx being the length, 2 y the breadth, n the thickness, z the height of the compass above it, r the distance from the compass to one corner, and v the volume of the plate, 4 xnxy xv 1 4 xnxy xv 1 r.(y2 + £2)- V y* + z*' 1 2r\y+z2 a>2 + 2-2J or such a plate will always produce a diminution of the directive force, and if x>y, or if its length be in the fore-and-aft direction, a positive quadrantal deviation. A vertical thin plate, such as a transverse bulkhead, may, as regards transverse induction, be considered as a series of thin horizontal beams giving a — e, diminishing X and increasing 3). As regards vertical induction, it may be considered as a series of •vertical rods giving a -\-c if before the compass, a — c if abaft, and a -f- k or — 1c according nearly as the centres of the supposed vertical rods are within or without the cone we have described. There would be no difficulty in computing the effect of such a bulkhead of given position and thickness if k were known. Thick Plate magnetized perpendicularly . If the length and breadth of the plate be infinite or very great compared to the distance of the compass, such a plate will produce no effect on the compass, the effect of one surface being exactly neutralized by that of the other. When the dimensions of the plate are finite we may arrive at an approximate result, by supposing lines drawn from the compass to every point on the edge of the further surface. The parts of the two surfaces within the pyramid bounded by these lines will neutralize each other, leaving only a margin of the nearer surface to act on the compass. The effect of this may be easily computed, by computing the effect of four such red or blue lines, as the case may be, the free magnetism in a unit of length being F — X breadth of margin. From these considerations we see that the effect of even a thick armour-plating, magnetized perpendicularly, will not be great. The effect of a thick transverse armour bulkhead, on a compass immediately above and near it, will be to produce a — a, which maybe easily computed, as we may suppose the dimensions of the plate in every direction below its upper surface to be infinite. If l be the thickness of the bulkhead, n the height of the compass above its centre, CHARACTER OF THE ARMOUR-PLATED SHIPS OF THE ROYAL NAVY. 315 Sphere. Let the centre of the sphere be at a distance r from the centre of the compass, and let r make angles a, (3, y with the coordinate axes to head, to starboard, and to nadir, and let 4t r 3 3 PS- An M. Then a=M(S cos2 a — 1), b=d= M 3 cos a cos/3, whence c=g= M 3 cos a cosy, e=M(3 cos2/3— 1), f=h= M 3 cos (3 cos y, &=M(3cos2y— 1), A = 1+y {1 — 3 cos2 y}, 21= o, 95 = M 0 , . — o cos a cos y tan 0, (5= M — 3 cos (3 cos y tan 6. 2>= y • (cos2 a — cos2 /3), <$ = — 3 cos a cos p, From these we see that a sphere, wherever placed, will increase X and give a — k if 1 cos y<— ' V 3 or y>54° 45', and will decrease X and give a -\-k if y<54° 45'. Hence if, as before, we suppose a double cone traced out by a line passing through the compass, making an angle 54° 45' with the vertical, all spherical masses of iron whose centres are placed without the cone will increase the directive force and diminish the usual heeling error. All spherical masses whose centres are placed within the cone will diminish the directive force and increase the heeling error. Hence, as far as pos- sible, no iron should be either below or above the compass within an angle of 54° 45' of the vertical passing through the compass. If cos a > cos (3 , or if the centre of the sphere be in either fore-and-aft quadrant, the 316 STAFF COMMANDER EVANS AND. ME. A. SMITH ON THE MAGNETIC effect of the sphere is to increase the quadrantal deviation ; if in the starboard or port quadrant, it will decrease the quadrantal deviation. If we have two spheres, one on each side and at the level of the compass, a =90°, y=90°, j3=0° and 180°, whence X=l+M, 3M 1+M' 1 + (?)' nearly. Hence we get the following for the effect of two such spheres according to the number of semidiameters which their centres are distant from the centre of the compass. r. e. D. 2 V •333 19 30 3 P •107 6 10 4 p •046 2 40 bp •023 1 20 Hence also we find the distance of the spheres required to correct any given qua- drantal deviation 2, Ant ~3x As we have supposed — ^-=1, the deviation which two balls of iron of the usual 1 +TX kind will correct will be one or two per cent, less than the above. When the sphere is in either of the diagonal planes, a=45°, |3=45°, or a= — 45°, /3=135°, 2=0, and or (S is the same as the 2 when the sphere is in a principal plane. This We should of course anticipate. M From the expression 33= — 3 cos a cos y tan 0, we see that in the northern hemisphere, if the sphere be below and before, or above and abaft the compass, we have a + semi- circular deviation ; if above and before, or below and abaft, a — semicircular deviation. Spherical Shell. The effect, if the compass be exterior to the shell, will be precisely the same as that of a sphere if for M we substitute M (i+H ti 1 + Airx -f 4 8/ CHARACTER OF THE ARMOTJR-PLATEE SHIPS OE THE ROYAL NAVY. 317 or nearly, when * is large and 1 — ~ small, i_2 l— i+— - p own Hence we see that the force of the shell will be half that of a sphere of equal external radius if * be 12 and the thickness of the shell be y-jjo of the semidiameter, or if *=24 and the thickness be 2-50 °f the semidiameter, or if *=36 and the thick- ness of the shell be 3-^0 of the semidiameter. Hence the effect of a tank ^th of an inch thick and 4 feet diameter would probably be about one-third that of a solid mass of the same dimensions. The effect of such a mass as a rifle-tower 4^ inches thick and 10 feet in diameter will be nearly the same as if it were of solid iron. Such a tower placed in front of a compass, as in the Warrior, will give a considerable +«, a — e of half the amount, and therefore increase \ and 3D, and if the compass be neither much above nor below it, decrease the heeling error. Infinite cylinder magnetized perpendicularly to its length. A compass placed at a considerable height above the deck, near an iron mast or funnel, may be considered as acted on by a vertical cylinder or cylindrical shell of infi- nite length. If r be the distance of its centre from the centre of the compass, p and ^ the radii of the outer and inner surfaces of the cylinder, then when the cylinder is solid, M= 2wk p2 1 + 2wn r 2 and when the cylinder is hollow M= 2™ v2 1 + 2ww r2 (1+2 w*y H) l + 4** + 4»V H) 2wn p2 p 1 + 2 wn r2 q 1 p + 2wx nearly, if * is large and 1 — ® small. Also a = M, e = — M; hence * K = 1, ■ 2) = M; whence we get the remarkable result, that a long vertical cylinder or a cylindrical shell 318 STAFF COMMANDER EVANS AND MR. A. SMITH ON THE MAGNETIC does not alter the mean directive force on a compass placed near its centre as regards elevation. It may be interesting to compare the effect of two solid stanchions placed one on each side of the compass with that of two solid spheres, in correcting the quadrantal deviation. The effect of the stanchions would be nearly whence r . ©. D. 2p •500 30° 0 •222 12 50 4 p •125 7 10 5j> •080 4 36 A mast or stanchion placed as we have supposed would generally diminish the heel- ing error. We may compare the effect on the directive force of a compass on the main deck of an iron ship with the effect on a compass in the interior of a spherical shell. In some ships the value of X at the main-deck compass is about *75. Comparing this value with the expression for the force in the interior of a spherical shell, viz., F we have or taking * as 24, 1_2=J- ; p 8irx 1 £_J_ p~ 600 nearly, or the effect is the same as if the compass were inclosed in a spherical shell of an inch thick and 50 feet radius, or half an inch thick and 25 feet radius. We may observe that at present one of the great difficulties in deducing numerical results as to the effect of rods or plates of iron, arises from our ignorance of the value of x for iron used for building or plating ships. We hope to be able on some future occasion to be able to communicate to the Royal Society the result of observations made for the purpose of determining this value in plates of iron of different kinds. CHARACTER OF THE ARMOUR-PLATED SHIPS OF THE ROYAL NAVY. 319 GENERAL CONCLUSIONS. The following appear to be the principal conclusions to be drawn from the applica- tion of observation and theory to the magnetic phenomena in iron ships. 1. The original semicircular deviation depends principally on the direction of the ship’s head in building, and consists principally in an attraction of the north point of the needle to the part of the ship which was (nearly) south in building. 2. This attraction is caused by the subpermanent magnetism induced in the ship when building, by the horizontal force of the earth. 3. If we consider separately, first, the effect of the subpermanent magnetism induced by the fore-and-aft component of the horizontal force, and secondly, the effect of the subpermanent magnetism induced by the transverse component of the horizontal force, the first is relatively less than the second. This, if the direction of the ship in building does not coincide with a cardinal point, modifies the direction of the semicircular devia- tion produced. 4. A third part, being the remainder of the semicircular deviation, is independent of the direction of the ship in building. It is the effect of the subpermanent and transient magnetism induced in the ship by the vertical force of the earth, and it consists in an attraction of the north point of the needle to the bow or stern. In the usual place of the Standard Compass this part is, in the northern hemisphere, an attraction of the north point of the needle towards the bow ; but if the compass is placed nearly in front of a large vertical mass of iron, as the stern-post, it may be towards the stern. 5. The first and second parts of the semicircular deviation diminish rapidly after the ship has been launched, the second generally most rapidly ; but after a time, which may be taken roughly as a year, if the ship has been allowed to swing on all azimuths, they attain a very fixed and permanent amount, from which they do not afterwards vary to any great extent. The third part changes little, if at all, so long as the ship remains in the same latitude. 6. The changes which take place in the semicircular deviation of a ship built East and West are generally relatively greater than in one built North and South. 7. The transient magnetism induced by the earth’s horizontal force adds to the effect of the subpermanent magnetism induced by the same force, when she is on the stocks, and afterwards when her head is in the same direction in which it was while building. 8. The effect of the subpermanent and transient magnetism induced by the hori- zontal force when the ship is on the stocks is principally, and if the ship is built on a cardinal point entirely, to produce a diminution of the directive force on the needle, and very little, and if built on a cardinal point not at all, to produce deviation. 9. The same effect (nearly) is produced at a subsequent time if the ship’s head is placed on the direction in which it was while building. mdccclxv. 2 x 320 STAFF COMMANDER EVANS AND MR. A. SMITH ON THE MAGNETIC 10. This diminution of the directive force is greater if the ship has been built East and West than if built North and South. 11. The deviations in an iron ship which has been built East or West are more preju- dicial than in a ship built North or South in the following respects: — 1. They are less symmetrical and regular, and therefore more perplexing to the seaman. 2. They change more relatively after launching. 3. They diminish the directive force more when the ship is on particular points. 12. When a ship has been built head North, the upper part of the stern and the lower part of the bow are strongly magnetized ; the upper part of the bow and the lower part of the stern are weakly magnetized. When a ship has been built head South, the upper part of the bow and the lower part of the stern are strongly, the upper part of the stern and the lower part of the bow are weakly magnetized. Consequently in ships built head North, a compass placed near the stern will have a large semicircular deviation. 13. In the last case there will be a large downward force on the north point of the needle, which will produce a large heeling error. In ships built head South, both the last errors will probably be small. 14. On the whole, for compasses to be placed in the after part of the ship, the best direction for building is head South. For compasses near the centre of the ship, the directions head North and head South are nearly equally good. 15. The diminution of the mean directive force is the mean of the diminution caused by the transient magnetism induced by the horizontal force when the ship’s head is North or South, and that induced when her head is East or West, i. e. it is the mean of the thrust from the north end and from the north side. 16. The quadrantal deviation is caused by the excess of the latter over the former, i. e ., by the excess of the thrust from the north side over the thrust from the north end. 17. The diminution of the directive force and the amount of the quadrantal deviation are nearly the same at the same level in different parts of the ship. They increase in descending from the position of the Standard Compass to the compasses on the upper and main decks. They diminish with the lapse of time. 18. By substituting wood for iron in the part of the deck below and above the compass, and within an angle of 35° 15' of the vertical line passing through the compass, and having no masses of iron with their centres within 54° 15' of the same vertical line, the directive force is increased and the quadrantal and heeling error generally diminished. 19. In selecting a place for the Standard Compass, care should be taken to avoid as much as possible the proximity of the ends of elongated masses of iron, particularly if placed vertically ; or, if they cannot be avoided, then a place should be selected where they diminish instead of increasing the semicircular deviation. The neighbourhood of rifle and gun turrets in ships carrying them should be as much as possible avoided. CHARACTER OF THE ARMOUR-PLATED SHIPS OF THE ROYAL NAVY. 321 20. In the construction of iron-built and iron-plated ships, regard should be had to the providing a suitable place for the Standard Compass. It is not difficult for any one who has studied the question, to suggest arrangements which would greatly mitigate the injurious effects of the iron of the ship ; the difficulty is to reconcile them with the requirements of construction and of working. Postscript. Since the foregoing paper was read, additional observations of deviations have been made in the Achilles and Defence, and observations in two new iron-built armour-plated ships, the Minotaur and Scorpion, the results of which are contained in the annexed Table. The observations in the Achilles show a continued diminution in the value of S3 and a continued tendency in 6 to return to its original value. The Defence con- tinues to show great permanence both in 93 and (5. The Minotaur, of which it has been thought desirable to give a woodcut drawn to the same scale as the ships represented in Plate XI., illustrates in a very remarkable manner some of the principles deduced from other ships. The Minotaur is the first iron-built ship completely plated from end to end ; her quadrantal deviation is con- sequently small. Having been built and plated head north, the original deviations in all the compasses were very large. In the steering and poop compasses the maximum deviation was above 60°. With deviations of this amount the compass becomes useless unless corrected by magnets, and magnets were consequently applied, which removed almost entirely the semicircular deviation. Probably in a very short time we shall find the original — 93 of these compasses to have so far diminished that the compasses will be found to be greatly over corrected and to have a considerable +93. Magnets were also applied to the Standard Compass. The heeling error at the poop compass is very large, 2° 46'. This arises from the compass being so near the stern of the ship, built and plated head north, and also from its being elevated above the armour-plating. It is interesting to contrast it with the heeling error of the steering compass, where from the peculiar configuration of the armour-plating being such as to give a — Jc, the heeling error is diminished and of a moderate amount. The Scorpion is a remarkable instance of the change which takes place in the semi- circular deviation from a change of position in a new iron-built vessel. Having been built head N. 76° W., or S. 254° E., the original value of 93 was — ’246, and the original starboard angle was 233-|°. After lying four months head S. 47° W. or S. 313° E., the value of 93 changed its sign and became +‘225, and the starboard angle increased to 303A°, thus following very nearly the direction of the south line in the ship. The Scorpion is an instance of the successful correction of the heeling error by means of a vertical magnet. This reduced the heeling error from 1° 38' to 2; for each degree of heel. 2x2 STAFF COMMANDER EVANS AND MR. A. SMITH ON THE MAGNETIC 322 Ship. Compass. Place. Date. Approximate coefficients. Exact coefficients. A B c D E 1 e ; Minotaur. (6621 tons), 1350 horse-power, 26 guns, Iron-cased, iron hull. Built on same slip as Warrior ; head N. 3° E. magnetic. Launched Dec. 12, 1863. Plated head N. 22° E. in Victoria Docks. Scorpion. (1857 tons), 350 horse-power, 4 guns, Iron-cased turret ship, iron hull. Built at Birkenhead ; head N. 76° W. Standard. Victoria Docks, March 28, 1865 | EiverThames, March 30, 1865 ... Sheerness April 10, 1865 .. j 0 1 By denial D of k -0 47 -0 5 5 %on and h larch 30 a -23 26 -20 30 + 0 44 ° \ orizontal . dopted .... + 64 + 4 25 — 0 16 0 1 force on o\ + 5 41 + 5 43 + 5 43 0 1 ne point : , -0 54 -0 26 —0 26 1 \ andj II — -014 I--001 after coi -•487 -•420 -•379 ” reetion + •174 +•099 + •069 by mag +•100 +•100 nets. -° — 0(| Starboard steering. Sheerness April 10, 1865 .. | +0 32 -61 0 — 0 28 + 0 45 + 2 8 + 5 56 -0 7 ( [+•009 | — *965 after correction I+-015 | + -103 by magnets. -■Olj Poop (on fore part), Sheerness April 10, 1865 .. j +1 16 -60 0 - 1 55 + 20 + 5.8 + 4 55 -0 5 < I+-022 after co7 ( — ■948 •reetion ( + •038 by mag I+-086 nets. -•01 I Standard. Birkenhead . . . October 31, 1864 1 March 14, 1865 { Birkenhead •! [ March 15, 1865 j By deviat D of M lapse of From obse been lyi 53 1 after com ion and he arch 1865 ' time nations n ng four m + 0 32 | ’.ction by 7, rrizontal J adopted , lade in on onths 8. 4 + 1 43 rngnets. rorce on 07, with smal e quadran 7° W. + 10 47 te point: ) 'l allowanc t after shq -0 52 t and 1 •e for L 0 had~\^ -•015 -•246 + •225 + •009 -•355 -•341 + •030 +-i9°( +•180 +■187 mum -•O' Achilles (continued). Standard. Portland April 1865 Lisbon May 4, 1865 + 16 50 + 12 30 + 6 40 +•322 +•274 +•191 + •132, +•115 ■■ .. I* Defence (continued). Standard. Portland April 3, 1865 Lisbon May 1, 1865 +0 13 +0 23 + 20 19 + 16 51 - 0 14 - 1 is + 6 09 + 6 16 -0 36 +0 04 + •004 +-o°7 +•367 +•307 -•004 — •021 +•107 +•109 -f Hi + ’1 7 CHARACTER OE THE ARMOTJR-PLATED SHIPS OF THE ROYAL NAVY. 323 R imum of semicircular deviation VB2 + C2 Mean force to North, X t 1 X Coefficients of horizontal induction. Part of D from Mean Vertical force, P X Heeling coefficient Heeling coefficients from 9 tan 6 ! i 9 izontal force of ship Vs82+®2*. Fore- and-aft, a t Transverse e t Fore- and-aft induction. Transverse induction. to windward, X Vertical induction in trans- verse iron. Vertical force and induction in vertical aount. Direction. O 0 1 0 / ° / 0 ! 0 1 •516 1604 24 •432 1664 •876 1142 -•036 -•212 -1 12 + 6 57 21 •385 1694 •892 1-121 -•019 -•197 -0 38 + 6 51 1-442 .+ ] 21 +0 35 +0 46 61 ■965 179 •811 1-233 -•106 -•272 -3 43 + 9 42 1-091 +1 ? +0 50 +0 17 6( •950 177| •826 1-211 -•103 -•245 -3 33 + 8 30 1-660 +2 46 +0 46 +2 0 •434 2334 *8 10 as sumed. 1-472 + 1 39 •406 3034 1-636 + 1 38 + 1 02 +0 36 -•050 •838 1-193 -•037 -•350 -0 7 + 10 57 ( -826 +0 2 ( after co erection b\ y vertical magnet. | •374 304 •844 1-185 -•059 -•253 -1 57 + 8 38 / ’3°6 (•384 } *6 ■820 1219 -•086 — •274 “3 2 + 9 37 2( •367 3594 •875 1-143 -•031 -•219 -1 02 + 7 13 If (■308 (•387 } 356 •855 1-169 -•052 -•238 -1 46 + 8 0 Mean force to North (AH) being unit. t Earth’s Horizontal force (H) being unit. I Earth’s Vertical force (Z) being unit. ' FhiL. Trouts. MDCCCLXK Flcct&X. Phi b. Jrcune. MDCCCL Plata XT. [ 325 ] VI. On some Foraminifera from the North Atlantic and Arctic Oceans , including Davis Straits and Baffin's Bay. By W. Kitchen Parker, F.Z.S., and Professor T. Rupert Jones, F.G-.S. Communicated by Professor Huxley, F.B.S. Received April 26, — Read May 12, 1864. Table oe Contents. § I. Introduction : — Page 1. Soundings from Baffin’s Bay. (Table I.) 325 2. Dredgings from the Hunde Islands. (Table II.) 326 3. Dredgings from Norway. (Tables III. & IY.) 329 4. Soundings from the North Atlantic. (Tables V. & YI.) 331 5. General Remarks 334 § II. Descriptions. Genera, Species, and Varieties. (Table VII.) 336 Descriptions of the Plates 412 Appendix I. — Additional North Atlantic Foraminifera 422 Appendix II. — Professor J.W. Bailey’s Researches on the “Virginian” Foraminifera of the North Atlantic. (Table VIII.) 423 Appendix III. — Further Researches by Professor J. W. Bailey 428 Appendix IV. — Mr. Pouktales’ Researches on North Atlantic Foraminifera 429 Appendix V. — The Foraminifera of the “ Celtic” and “ Virginian” Provinces of the North Atlantic, as a Fauna. (Table IX.) 430 Appendix VI. — Distribution of Foraminifera. (Tables X. & XI.) 434 Appendix VII. — The North- Atlantic Soundings. (Table XII.) 439 (Map [Plate XII.] and Plates XIII. to XIX.) Introduction. The specimens here described are comprised in four collections ; namely — 1. From Baffin’s Bay, between 76° 30' and 74° 45' North Latitude. These specimens are derived from seven deep-sea soundings made during one of the Arctic Expedi- tions under Sir Edward Parry. These soundings were confided to us by Professor Huxley, of the Museum of Practical Geology, Jermyn Street, to which Institution they had been given in April 1853 by Mr. J. W. Lowry, who received them of Mr. Fisher, Assistant-Surgeon in the Expedition alluded to. The Foraminifera obtained by us from these soundings are tabulated in Tables I., IV., and VII. This material from the “Arctic Province” of Naturalists is but scanty. None of the Foraminifera here obtained are numerous, except Polystomella striatopunctata, Nonionina Scapha, Truncatulina lobatula, and Cassidulina laevigata ; the first two of which are at home in Arctic waters : and none have attained here a large size except Lituolae. The material from 150 fathoms yielded these relatively large and numerous specimens. mdccclxv. 2 Y 326 ME. W. K. PAEKEE AND PEOFESSOE T. E. JONES ON SOME Table I. — Table of the Soundings from Baffin’s Bay. No. Depth. Condition of bottom, &c. Genera and subgenera of Foraminifera. fathoms. 1. Lat. 75° 10', Long. 60° 12' . . 9 Pine grey syenitic sand, with syenitic fragments j inch and less in length. Nodosarina (Dentalina), La- gena, Planorbulina (Truncatu- lina), Polystomella (and Nonio- nina), Cassidulina, Miliola (Quinqueloculina), Lituola. 2. Lat. 76° 30', Long. 77° 52' . . 150 Greyish muddy micaceous sand, with angular syenitic fragments | inch and less in length. Globigerina, Planorbulina (Truncatulina), Pulvinulina, Polystomella (and Nonionina), Cassidulina, Lituola. 3. Lat. 74° 45', Long. 59° 17'. . 250 Greysandymud; sand,quartzose, angular and rounded. No Foraminifera. 4. Lat. 75° 25', Long. 60° .... 314 Syenitic sand, with fragments of syenite | inch and less in length. Miliola (Triloculina), Lituola. 5. • Lat. 76° 20', Long. 76° 27' . . 2 No Foraminifera. 6. Lat. 75°, Long. 59° 40' ... . 230 Grey mud, with quartzose sand, partly rounded, and with several partly rounded fragments of lava- rock. Planorbulina (Truncatulina), Polystomella (and Nonionina), Miliola (Quinqueloculina), Li- tuola. 7. Lat. 76° 10', Long. 76° .... Sand from an iceberg. Grey, heavy, fine, micaceous, syenitic sand, with fragments (f in. largest); some grains slightly worn. No Foraminifera. 2. From the Hunde Islands, in South-east or Disco Bay, on the west coast of Greenland (lat. 68° 50' W., long. 53° N.). Five soundings taken by Dr. P. C. Sutherland (now Surveyor-General of Natal) in 1850, and confided to us by Professor Huxley of the Museum of Practical Geology, to which Museum they were given by Dr. Sutherland in 1853. Dr. P. C. Sutherland’s observations on the Arctic Regions visited by him were pub- lished in his ‘Journal of a Voyage in Baffin’s Bay and Barrow Straits in the years 1850-51,’ 2 vols. 8vo, 1852; and in the Quart. Journ. Geol. Soc. vol. ix. p. 296, &c. See Tables II., IV., VII. for the Foraminifera from the Hunde Islands. FOB A MIN IFERA FROM THE NORTH ATLANTIC AND ARCTIC OCEANS. 327 Table II. — Table of the Dredgings and Foraminifera from the Hunde Islands, Disco Bay. No. Depth. Character of bottom. G-enera and subgenera of Foraminifera. 1. Hunde Islands . . fathoms. 25 to 30 Pale-grey micaceous clay; more Polymorphina, Planorbulina (Trunca- 2. 28 to 30 than half small mica-flakes. With vegetable matter (fucal); Hydro- zoa ( Sertularia ); Polyzoa ( Bereni - cea, &c.); Entomostraca ( Cythere , &c.); Bivalve and univalve Mol- lusks. (About an ounce.) Gravel of hornblende-schist and tulina), Pulvinulina, Polystomella (and Nonionina), Nummulina, Cassidulina, Bulimina, Textularia (andYerneuilina), Cornuspira, Miliola (Quinqueloculina, Triloculina), Lituola. Globigerina, Planorbulina (Trunca- 3. 30 to 40 syenite (largest fragments 1| inch long). Seaweed ( Fucus ) ; Nulli- pores ; fragments of Balanus (pre- dominant) ; Crustacea ( Talitrus , Cythere,

, we have -n d¥ ?i=?—dr where F is got from the equation d12 F 1 d¥ dr2 ' r dr = -4 vp-p, r being the distance from the axis of the cylinder. Let one term of the value of F be of the form T rn, where T is a function of the time, then the term of p which produced it is of the form — -t— n?Trn-2. 47 T[& Hence if we write *=t+7 (-p+f r+TTir** wr‘+ ** n~- ' dt ' " r j2 1 ds T dt2‘ r4— &c. q I I2 . 22 dtS point is CfP \ 7 , 1 rp [X.7T dT /A2 1 d2T Jli-^;=0, =P, =0, &c. When t=oo , w = s • =0. (S), = 0, &c. a' /P \ 7 lm „ 1 LOT2 dT , f*27T3 1 fi?2T - 25r(j -p)rdrdt= -W+ 2Y~dir +lr TVFTs &c- from t=0 to =oo . When £=0, p= 0 throughout the section, .\ =P, = 0, &c- When t= co , p=0 throughout \ ) = 05 =0, &c. Also if l be the length of the wire, and R its resistance, k=4; and if C be the current when established in the wire, C= -yp The total counter current may be written B(T--T.)-|4c=-^by§(35). PROFESSOR CLERK MAXWELL ON THE ELECTROMAGNETIC FIELD. 511 Now if the current instead of being variable from the centre to the circumference of the section of the wire had been the same throughout, the value of F would have been F=T+W(l-Q, where y is the current in the wire at any instant, and the total countercurrent would have been Hence ff IdF l -2 %rdr— § a„.„_K(T.-iy-!(.|EO=— L'C !-> say- L=L'-fcfcZ, or the value of L which must be used in calculating the self-induction of a wire for variable currents is less than that which is deduced from the supposition of the current being constant throughout the section of the wire by +/+ where l is the length of the wire, and [Jj is the coefficient of magnetic induction for the substance of the wire. (116) The dimensions of the coil used by the Committee of the British Association in their experiments at King’s College in 1864 were as follows : — metre. Mean radius ....... =«=T58194 Depth of each coil =§ = -01608 Breadth of each coil .... = c = -01841 Distance between the coils . . . =-02010 Number of windings .... ^=313 Diameter of wire =-00126 The value of L derived from the first term of the expression is 437440 metres. The correction depending on the radius not being infinitely great compared with the section of the coil as found from the second term is — 7345 metres. The correction depending on the diameter of the wire is 1 . . \ & . + -44997 per unit oi length J Correction of eight neighbouring wires +-0236 For sixteen wires next to these +-0008 Correction for variation of current in different parts of section — -2500 Total correction per unit of length -22437 Length 311-236 metres. Sum of corrections of this kind 70 „ Final value of L by calculation 430165 „ This value of L was employed in reducing the observations, according to the method explained in the Report of the Committee*. The correction depending on L varies as the square of the velocity. The results of sixteen experiments to which this correc- tion had been applied, and in which the velocity varied from 100 revolutions in seventeen seconds to 100 in seventy-seven seconds, were compared by the method of * British Association Reports, 1863, p. 169. 512 PROFESSOR CLERK MAXWELL ON THE ELECTROMAGNETIC FIELD. least squares to determine what further correction depending on the square of the velocity should be applied to make the outstanding errors a minimum. The result of this examination showed that the calculated value of L should be multiplied by 1-0618 to obtain the value of L, which would give the most consistent results. We have therefore L by calculation 430165 metres. Probable value of L by method of least squares 456748 „ Eesult of rough experiment with the Electric Balance (see § 46) 410000 „ The value of L calculated from the dimensions of the coil is probably much more accurate than either of the other determinations. C 513 ] IX. On the Ernbryogeny of Antedon rosaceus, LincJc (Comatula rosacea of Lamarck). By Professor Wyville Thomson, LL.D., F.B.S.E., M.B.I.A., F.G.S., &c. Com- municated by Thomas Henry Huxley, F.B.S. Received December 29, 1862, — Read February 5, 1863*. In the year 1827 Mr. J. V. Thomson, Deputy Inspector-General of Military Hospitals, described and figured what he believed to be a new recent Crinoid, under the name of Pentacrinus Europceus ; and in June 1835 communicated to this Society a “Memoir on the Star-fish of the genus Comatula , demonstrative of the Pentacrinus Europceus being the young of our indigenous species.” In this memoir the author describes and figures a series of Pentacrinus Europeans from its earliest stage, in which it is represented as “ an attached ovum in the form of a flattened oval disk, by which it is permanently fixed to the point selected, giving exit to an obscurely jointed stem ending in a club-shaped head”; to its most perfect attached condition, in which the head is compared with, and found closely to resemble the youngest free Antedon taken with the dredge. The period of the disappearance of the pentacrinoid larvae on the oar-weed exactly corresponds with that of the appearance of the most minute free Antedons in the water. Mr. Thomson’s observations were conclusive. I am not aware that they have hitherto been repeated in detail on the European species, but the “ pentacrinoid ” stage of Ante- don has ever since been the frequent and familiar prize of the dredger, the wonderful beauty and gracefulness of its form and movements, and its singular relations to the Echinoderm inhabitants of modern and of primaeval seas, rendering it an object of ever recurring admiration and interest. The remarkable discoveries of Professors Sars and Johannes Muller on the meta- morphoses of the embryo and its appendages in other Echinoderm orders rendered it probable that the germ of Antedon might pass through some earlier transitional stage before assuming the fixed pentacrinoid form. Dr. W. Busch undertook this investigation, and for this purpose he visited Orkney in J uly 1849, and procured a supply of specimens in Kirkwall Bay. As those of Dr. Busch are the only recorded observations on the early stages in the embryology of the Crinoids, I shall briefly abstract his results published in Muller’s ‘ Archiv,’ 1849, and more fully * Subsequently to tbe reading of this paper it was arranged that the author should take up a somewhat later stage in the development, which he had at first intended to leave to Dr. Carpenter. The paper was accordingly returned to him that it might receive the necessary additions ; but no alteration of importance has been made in the description of the earlier developmental stages, which formed the subject of the memoir presented to the Royal Society. 4 A MDCCCLXV. 514 PROFESS OR W. THOMSON ON THE EMBRYOGENY OE ANTEDON in his own ‘ Beobachtungen iiber Anatomie und Entwickelung einiger wirbellosen Seethiere’ (Berlin, 1851). The author alludes to the position of the ovary in Antedon , and to the peculiar way in which the impregnated ova remain hanging in bunches from the ovarian aperture. He describes the formation from the segmented yelk-mass of a uniformly ciliated club- shaped embryo, which escapes from the vitelline membrane and swims freely in the water (Beobachtungen, &c., pi. 13. fig. 13). During the next four-and-twenty hours a bunch of long cilia appears on the narrower anterior extremity, and near it, on the side of the embryo which is turned downwards in a state of rest, a small round opening which he regards as the provisional larval mouth. Three slightly elevated ridges now gird the body transversely at equal distances (op. tit. pi. 13. fig. 14), and gradually become clothed with long cilia, the smaller cilia disappearing from the intervening spaces. The inte- gument between the first and third ciliated ring becomes inverted into a large oval depression, a fourth ciliated band appears near the posterior extremity of the embryo, and a few delicate areolated calcareous plates are developed within the integument. The embryo now becomes slightly curved, the large oval opening which the author regards as the excretory orifice becomes more distinct in the centre of the ventral surface, and the embryo attains its most perfect larval form (pi. 14. figs. 1 & 2). The form of the larva now rapidly alters ; on the ninth day (pi. 14. fig. 3) the posterior extremity has become much enlarged and invested with a thick gelatinous integument. This distended extremity becomes slightly lobed, the anterior bunch of cilia and the posterior ciliated bands disappear, the mouth and anus become indistinct (pi. 14. fig. 5), and at length (pi. 14. fig. 6) a row of four delicate tubes bearing pinnules appears along either side of the larva, the rudiments of the arms of the Crinoid. Dr. Busch was unable to pursue his researches further. In many points his observations are inconsistent with those which I have repeated during the last three years with great care, and I believe that he has misconceived the nature and relations of the organs of the larval embryo. Dr. Busch’s account of the first appearance of the pentacrinoid form is certainly contrary to my experience ; I have been led, however, by inconsistencies in my own observations upon different broods in different seasons, to believe that the mode of development may to a certain extent vary with circumstances. I find, for instance, that when the ova are liberally supplied with fresh sea-water and placed in a warm temperature, the later stages of larval growth are, as it were, hurried over ; so that the free larva scarcely attains its perfect form before being distorted by the growing crinoid. In other instances, in colder seasons and in a less favourable medium, the larva reaches a much higher degree of independent development, and retains for a longer period the larval form. In 1859 I communicated to this Society a short notice (Proc. Boyal Society, vol. ix. p. 600) of the earlier stages in the development of Antedon. My observations were made upon one or two broods of Antedon in a single season. I had an opportunity at that time of tracing carefully the earliest phases in the development of the pseudembryo, but EOSACEUS, LINCK (COMATULA EOSACEA OE LAMAECK). 515 subsequent observations have led me to believe that in some of the later stages the young of Antedon were confounded with those of a Turbellarian, which resembled them closely, and which during that season accompanied them in great numbers. These earlier obser- vations were imperfect and hurried in consequence of the difficulty which I then expe- rienced in rearing the young, of their extreme delicacy, and of the rapidity with which they passed through their developmental steps. These difficulties have since been to a certain extent overcome by the frequent repetition of the observations, and by due regu- lation of the temperature of the tanks and of the supply of food and water. M. Dujardix has figured* with great accuracy, but without any description, an early stage in the development of the pentacrinoid young of Antedon Mediterraneus, Lam., which he observed at Toulon in May 1835. The figure represents the oral valves par- tially open, with a group of tubular tentacles protruded from the cup. It is highly characteristic. On the 16th of February, 1863, Professor Allmax communicated to the Royal Society of Edinburghf a paper “ On aPrebrachial stage in the development of Comatula.” The author procured a single specimen of the stage represented by Dujardix, and in Plate XXVI. of the present memoir, among the refuse of a dredging boat on the coast of South Devon. Dr. Allmax describes this minute Crinoid as consisting of a body and a stem ; the body formed of a calyx covered by a pyramidal roof. The calyx is composed of five large separate plates. Between the lower edges of these plates and the summit of the stem, there is a. narrow zone, in which “ no distinct indications of a composition out of separate plates can be detected.” Between the upper angles of every two contiguous plates there may, with some care, be made out a minute intercalated plate. The pyra- midal roof which closes the cup is composed of five large triangular plates, each sup- ported by its base upon the upper edge of one of the large plates of the calyx, and with the small intercalated plates encroaching upon its basal angles. Long flexible append- ages or cirri rise out of the calyx, and in the expanded state of the animal, are thrown out between the edges of the five diverging plates of the roof. Dr. Allmax counted fourteen of these appendages, but could not determine their exact number. “They appear to be cylindrical with a canal occupying their axis ; as far as they can be traced backwards they are seen to be furnished with two opposite rows of rigid setae or fine blunt spines. Between every two opposite setae a transverse line may be seen stretching across the cirrus, and indicating its division into transverse segments.” The author never succeeded in tracing these appendages to their origin. Besides these long exten- sile cirri, there is also an inner circle of short apparently non-extensile appendages. It was only occasionally that the author succeeded in getting a glimpse of these. “They appear to constitute a circle of slightly curved rods or narrow plates probably five in number, which arch over the centre and are provided along their length with two opposite rows of little tooth-like spines. They seem to be articulated to the upper or * Suites a Buffon. Zoophytes Echinodermes, par M. E. Dujakdin et par M. E. Htjpe. Paris, 1862. t Transactions of the Eoyal Society of Edinburgh, vol. zxiii. 4 a 2 516 PROFESSOR W. THOMSON ON THE EMBRYOGENY OF ANTEDON ventral side of the calyx by their base, and may be seen in a constant motion, which consists in a sudden inclination upon their base towards the centre, followed immediately by a resumption of their more erect attitude.” The interior of the calyx is occupied by a reddish-brown visceral mass, obscurely visible through the walls. The author did not succeed in getting a view of the mouth, and detected no anal aperture. Dr. Allman accurately describes the general structure of the stem ( loc . tit. p. 243) ; he conceives, however, that “ the multiplication of the segments of the stem seems to take place by the division of the pre-existing ones, and this division seems indicated by the transverse ridges, which in several of the segments may be seen running round the centre.” A detailed description of the developmental stage which forms the subject of Dr. Allman’s communication will be found at pp. 525 & 526 of the present memoir. It is unfortunate that so able an observer had not an opportunity of making himself fully acquainted with this interesting form by the study of a sufficient number of specimens. In 1856 Professor Sars communicated to the Seventh Meeting of the Scandinavian Association a most interesting paper on the Pentacrinoid stage of Antedon Sarsii (Duben and Koren). The only specimen observed was dredged on the 14th of March with Halicliondria ventilahrum , from a depth of 50 fathoms near Bergen. It was in every respect a fully developed Antedon , from the centre of whose centro-dorsal plate proceeded a long thin cylindrical articulated stem attached inferiorly to the sponge. The disk with its central mouth, the long, cylindrical, excentric anal tube, the radial grooves, the ten arms with their characteristic articulations and syzygies, the pinnules with their tentacles, the rows of red-brown spots on the margins of the grooves on the arms and pinnules, and the dorsal cirri, were completely developed as in the adult form. All the arms were unfortunately broken, the portions left bore nine to ten pairs of pinnules. Six of these were of the ordinary form ; the three or four proximal pairs, which alternated less regu- larly, were setaceous, destitute of tentacles and pigment spots, the innermost pair longer than the others, as in the adult ; all the pinnules were attenuated, the generative element being as yet undeveloped. The dorsal cirri, twenty to thirty in number, were thickly set round the circumference of the centro-dorsal plate. They were fully formed, and the joints and terminal claws had the form characteristic of A. Sarsii. The stem was 20 millimetres in length, and consisted of thirty-one joints ; but as it was broken from its place of attachment, some of the inferior joints may have been lost. The two or three lowermost joints preserved became shorter towards the base, and the upper joints towards the attachment of the stem to the centro-dorsal plate decreased likewise in length ; the second joint was about half the length of the third, and the first only half that of the second; but the first joint was dilated upwards to its insertion. The middle joints of the stem are three to three and a half times longer than wide, and are all dice-box shaped like the joints of the dorsal cirri of the species. From this observation it would appear that the development of A. Sarsii is continued ROSACETTS, LIXCK (COMATULA ROSACEA OF LAMARCK). 517 to a much later period in the pedunculated condition than that of A. rosaceus; the dis- engagement of the latter species from its stem constantly occurs between the middle of August and the middle of September. The capture of the specimen described by Sars in March would seem to indicate that the development of the Pentacrinoid of A. Sarsii extends over nearly a year. The early portion of the history of the development of Antedon described in the fol- lowing pages divides itself naturally into two stages. The Echinoderms present in the most marked degree a peculiarity which seems to be only imperfectly indicated in the other invertebrate subkingdoms. This peculiarity consists in the successive development from a single egg, of two organisms, each appa- rently presenting all the essential characters of a perfect animal. These two beings seem to ditfer from one another entirely in plan of structure. The first, derived directly from the germ-mass, would appear at first sight to homologate with some of the lower forms of the Annulosa ; the second, subsequently produced within or in close organic connexion with the first, is the true Echinoderm. The extreme form of this singular cycle, in which the development of a provisional zooid as a separate, independent, living organism, is carried to its full extent, is by no means constant throughout the whole subkingdom, although its existence has been established for all the recent orders. In each order it appears to be exceptional, and in certain cases it is known to be carried to its most abnormal degree in one species, while in a closely allied species of the same genus the mode of reproduction differs but slightly from the ordinary inver- tebrate type. To avoid ambiguity in the discussion of such singular relations, I believe it is necessary to introduce certain new terms. For an organism which possesses all the apparent cha- racters of a distinct animal, which is developed from the germ-mass, and which maintains a separate existence before the appearance of the embryo, I would propose the term pseudembryo ; and for all the appendages which homologate with the whole or with parts of such a pseudembryo, even although they do not assume fully the characters of a distinct animal form, I would propose the term pseudembryonic appendages. The same prefix may distinguish the organs of the temporary zooid, where such exist, pseudostome, pseudocele , pseudoproct, &c. The reason for the retention of this series of terms, and for the rejection as applied to the provisional organism of the ordinary terms “ embryo ” and “ larva,” will be fully discussed hereafter. The first stage includes the development, structure, and life-history of the pseud- embryo. While the special external form of the pseudembryo is still perfectly retained, and while its special functions are still in full activity, the form of the pentacrinoid embryo is gradually mapped out within the provisional zooid, and the permanent organs of the embryo are differentiated within its sarcode-substance. The pseudembryo then becomes gradually distorted by the embryo developing within it, its special assimilative and loco- motive organs disappear, and the external layer of its sarcode-substance subsides into the 518 PROFESSOR W. THOMSON ON THE EMBRYOGENY OF ANTEDON general integument of the embryo, still retaining sufficiently the histological characters of the pseudembryonic integument to leave no doubt that it is simply produced by its modification and extension. From the appearance of the first traces of the permanent embryonic structures within the pseudembryo, the development of the pentacrinoid larva advances' steadily ; and there is no natural separation into stages of its subsequent progress until the young Antedon drops from the larval stem. At one period, however, during the development of the pentacrinoid there is a marked change in the external form and in the anatomical rela- tions of the larva, owing to the sudden widening out of the radial portion of the disk, and the breaking through of the anal opening. Division of labour has been found expedient in the present investigation, and my portion of the task ends just before the development of the Pentacrinoid has reached this point. I think it only right, how- ever, to mention that Dr. Carpenter, who has been at the same time working out the later stages in the development of the Pentacrinoid and the structure of the mature Antedon, has most freely communicated to me all his results. My description of the development of the pentacrinoid larva has had therefore all the advantage of the light thrown upon the earlier stages by Dr. Carpenter’s researches on the later. The observations whose combined results have been condensed into the present com- munication have extended over the last four years. I have had an opportunity each season of watching the more or less favourable development of one or two sets of embryos. As stated above, these observations have not in all cases thoroughly tallied ; their inconsistencies depending, I believe, in some instances upon error of observation, and in others upon actual discrepancies in the process of development under different circumstances. In Arran, in June 1860, I had a most favourable opportunity of tracing a single brood from the segmentation of the yelk almost to the maturity of the penta- crinoid young. I took the opportunity to revise and check previous special observa- tions ; and each stage of the development of this group was described and figured with great care, and with the advantage of previous familiarity with the successive modifica- tions in form. To avoid all possibility of confusion, I have incorporated in the following detailed description those results only which were confirmed by these later observations ; and all the figures of the free pseudembryos, and of the origin of the pentacrinoid form, refer to the successive stages in the development of this single brood. On this occasion the pseudembryos remained for perhaps a somewhat shorter time than usual in their free condition, and their growth was early arrested by the development of the perma- nent calcareous plates. The pseudembryos, however, during their brief independent existence, attained their perfect and usual external form ; and the subsequent transitions, though rapid, were normal. The ovaries of Antedon have been frequently described. During the latter part of summer, autumn, and early winter they can only be traced as delicate lines of whitish stroma, beneath the integument of the upper (oral) surface of the pinnules, and imme- diately beneath the tentacular canals which in the ordinary condition of the pinnules EOSACETTS, LINCK (COMATTJLA EOSACEA OE LAMAECK). 519 lie in the groove of the calcareous joints. About the end of February or the beginning of March, the integument of the pinnules becomes slightly turgid ; and this turgescence increases till towards the end of May or the beginning of June, when the eggs are fully formed. The mature ovaries are short, entire, fusiform glands distending widely the inte- gument of the pinnules, and provided with a special aperture which perforates the distended skin on that side of the pinnule which is turned towards the end of the arm. The aperture is bounded by a somewhat thickened ring of apparently elastic tissue, which acts as an imperfect sphincter. Examining the ovary by compression shortly after it has begun to enlarge, the meshes of the stroma (Plate XXIII. fig. 1) are found to contain a clear mucilaginous protoplasm with minute ova in various early stages of development. Tracing the development of the ova, the formative fluid first becomes slightly opalescent, and a minute, highly refractive, lenticular body makes its appear- ance, which subsequently declares itself as the germinal spot. This body remains some time slowly enlarging without much further change. A delicate film now rises from one side of it, and this film gradually extends till the germinal spot appears to be attached to the inner wall of a spherical cell with perfectly transparent fluid contents, the germinal vesicle (Plate XXIII. fig. 2, a-c). The blastema in the neighbourhood of the germinal vesicle becomes slightly granular, and the granules accumulate so as to form a distinct granular layer round the cell. This layer, the nascent yelk, is shortly found to be invested by a delicate vitelline membrane ; but this membrane does not appear to originate from the germinal vesicle as a nucleus, as in the case of the latter from the germinal spot. The impression rather is that the surrounding fluid is influenced to a certain distance by the chemical forces acting in the germinal vesicle, and that a membrane is produced at the point of junction between the blastema so influenced and the general fluid contents of the ovary. The egg now increases in size without much further change in structure. The vitelline membrane rapidly expands (Plate XXIII. fig. 2, cl-o), and its contents become more dense, till at length it has attained a diameter of about ‘5 millimetre, and is entirely filled with a yelk-mass composed of oil-cells of the usual form. The ripe eggs are now discharged from the ovary ; they remain, however, for some time (in some cases three or four days) entangled in the loose stroma of the ovary, and hanging from the ovarian aperture like a bunch of grapes. The testis resembles the ovary in form and situation. A transparent mucus distends the integument of the pinnule. The fluid becomes opalescent, then granular, and finally the cavity becomes filled with amass of fusiform parent cells (Plate XXIII. fig. 4). The contents of these cells are at first perfectly transparent ; soon, however, they lose their transparency and become granular, and at length the cells are found to contain a progeny of ten or twelve minute spherical “ vesicles of evolution.” Bright refractive spots, the heads of the spermatozoa, three or four in number, appear in each of these secondary cells ; and finally, the walls of the parent cells and vesicles give way, and the 520 PROFESSOR W. THOMSON ON THE EMBRY 0 GrENY OF ANTEDON cavity of the pinnule is filled with a mucilaginous liquid charged with myriads of mature spermatozoa (Plate XXIII figs. 5 & 6). The form of the spermatozoon is intermediate between that of a club on cards and a spade (Plate XXIII. fig. 7), with a vibratile filament of great length attached to the obtuse end. There is no special opening to the testis, so that the female may be at once distinguished by the ovarian aperture. The seminal fluid seems to be discharged by the thinning away and dehiscence of the integument. The spermatozoa are dispersed in the water. Impregnation appears to take place after the discharge of the ova, but while they are still hanging from the ovarian aperture. An hour or two after impregnation the germinal vesicle disappears, or at all events leaves its former superficial position. The yelk-mass contracts and becomes more opaque and dense, leaving a clear space immediately within the vitelline membrane, which is thus more clearly defined, perfectly transparent and structureless, with the surface slightly and irregularly echinated (Plate XXIII. fig. 8). Consequently on the con- traction of the yelk, a number of minute spherical pale yellow oil-globules are appa- rently pressed out into the space within the vitelline membrane (Plate XXIII. fig. 11). The appearance of the “ richtungs-blaschen ” may be very readily traced in the egg of Antedon. At a point on the circumference of the yelk a very distinct globule, about half the diameter of the germinal vesicle, with an obscure nucleus, passes out of the yelk-mass into the surrounding space. In all the cases in which I have observed it, this globule has been accompanied by two or three minute rounded granular masses. Plate XXIII. fig. 14, a-c, are careful representations of three groups of these globules. They remain perfectly distinct from the divisions of the yelk during the earlier stages of segmentation ; at the close of this process, however, it becomes difficult to distinguish them from the ultimate divisions of the mulberry mass. In Antedon , yelk-segmentation is complete (Plate XXIII. figs. 9-13). Its first appearance is a slight groove passing- inwards from the circumference of the yelk, immediately at the point where the so-called “richtungs-blaschen” have been extruded. If the egg be now subjected to slight pressure, a transparent nucleus may be observed in the centre ; and at each stage of segmentation the nucleus may be readily detected in the centre of each segment. A few hours after segmentation has been completed, the surface of the germ-mass becomes slightly more transparent. The ultimate yelk-spherules are still sufficiently evident, giving the surface a distinctly mammillated appearance (woodcut A). This gradually disappears, the spherules seem to coalesce upon the outer surface, remaining distinct a little longer towards the inner surface of this rudimentary germinal membrane, and a few hours later they have become entirely fused into a continuous structureless sarcode-layer (woodcut B). While these changes are taking place in the outer layer, the central portion of the germ-mass becomes resolved into a mucilaginous protoplasm sufficiently fluid towards the centre to allow of an active circulation of granules and oil-globules, but apparently continuous with, and graduating into, the lower surface of the more consistent peripheral layer. A. Usual condition of the mulberry mass immediately after segmentation has been completed. B. Appearance of the nascent pseudembryo after the coalescence of the ultimate spherules of the germ-mass. C. Pseu- dembryo shortly before the rupture of the vitelline sac. In this case the development of the pseudembryo from the germ-mass resembles in every way the development of the embryo in most of the invertebrate groups ; on three occasions, however, during the examination of a series of eight or ten broods, a whole brood of embryos were evolved under somewhat different circumstances. The surface of the mulberry mass became somewhat looser and more transparent, and under slight pressure a large, somewhat darker and more consistent central nucleus was observed (Plate XXI Y. fig. 1). This nucleus increased in size from hour to hour, the peripheral portion of the contents of the vitelline membrane gradually liquefying and becoming absorbed into the nucleus. At length the oval outline of the pseudembryo might be traced through the flocculent mass of semitransparent semifluid yelk. The remainder of the yelk now became completely transparent and liquid, the embryo increased rapidly in size, and its form was more clearly defined through the wall of the vitelline sac (Plate XXIY. figs. 1-4). I believe, however, that this latter is an abnormal mode of development, depending probably upon imperfect aeration. Observed during the process of development within the vitelline membrane, the embryo is at first nearly regularly oval, and the surface appears to be uniformly ciliated. I have never met with an instance in which the embryo escaped in this condition. In all the cases which I have observed, the ciliated bands so characteristic of the pseud- embryonic form have made their appearance before the rupture of the vitelline sac (woodcut, C) ; and frequently the pseudembryo has become somewhat reniform, a de- pressed ciliated patch indicating the position of the pseudostome. The pseudembryo frequently, but not constantly, rotates slowly and irregularly within the vitelline sac, the rotation depending evidently upon 4he action of the cilia on the surface of the pseudembryo. Immediately after escaping from the vitelline membrane, the pseud- embryo is about *8 millim. in length, oval, slightly enlarged towards one extremity, and girded by four nearly equidistant transverse ciliated bands. It consists throughout of very delicately vacuolated sarcode, which becomes more and more consistent towards the periphery, where it forms a smooth firm surface, which is not, however, bounded by any definite membrane. Towards the centre the substance becomes more fluid, and is mdccclxv. 4 B 522 PROFESSOR W. THOMSON ON THE EMBRYOGENY OF ANTEDON turbid with oil-cells and granules. At this stage distinct molecular motion may he observed in the central portion, and a granular semifluid mass escapes if the larva be ruptured by pressure. The surface is dotted over with the wider ends of large pyriform lemon-coloured oil-cells immersed perpendicularly in the sarcode. Between these oil- cells the sarcode is nearly transparent, containing merely a few scattered granules. The ciliated bands project slightly above the general surface. They are greyish and granular, and appear to be rather more consistent than the surface of the sarcode, which rises up to them, sinking somewhat in the interspaces. The cilia are very long; they do not vibrate with the regular rhythmical lash of ordinary cilia, but seem to move independently, their motion regulating the rapidity and direction of the movements of the animal in the water. There is a large tuft of still longer cilia in perpetual vibratile motion at the narrower (posterior) extremity of the body. At first the pseudembryo is simply barrel-shaped, and regularly hooped by the four parallel transverse ciliated bands. Sometimes, while yet within the vitelline sac, but at all events within a few hours after its rupture, the body becomes slightly curved, somewhat like a kidney bean ; and on the concave surface, the third band from the anterior extremity arches forwards towards the second band ; and in the wider space thus left at this point between the third and fourth bands, a large pyriform inversion of the superficial sarcode-layer takes place (Plate XXIV. fig. 7). This inversion is narrower anteriorly, becoming wider and deeper towards the poste- rior extremity. Its margins are richly ciliated. Simultaneously with the appearance of this depression, a small round aperture may be observed immediately behind it, sepa- rated from it by the fourth ciliated band, and close to the posterior tuft of cilia. This aperture is surrounded by a ring of darker granular tissue, and the outline of a short arched canal may be detected passing under the fourth ciliated band and uniting the deep posterior extremity of the larger aperture, which thus becomes irregularly funnel- shaped, with the smaller circular opening. The large ciliated key-hole-like inversion of the sarcode is undoubtedly the pseudo- stome ; and resembles closely in form and position the same organ in other echinoderm pseudembryos. The loop-like canal beneath the posterior ciliated band is the extremely rudimentary pseudocele, and the round aperture is the pseudoproct. The pseud- embryo swims with either extremity in advance indifferently ; the anterior and posterior extremities are therefore only defined at this stage by the relative positions of the mouth and anus. It swims rapidly with a peculiar swinging semi-rotatory motion. The oral surface is turned downwards in a state of rest. The pseudembryo sometimes remains for several days, increasing in size till it becomes from 1*5 millim. to 2 millims. in length, without undergoing any further change. In other cases indications of the areo- lated calcareous plates of the Echinoderm appear within a few hours of the rupture of the vitelline sac. Usually not until the pseudembryo has assumed its mature and perfect form, but sometimes much earlier, several minute calcareous spicula make their appearance beneath EOSACETJS, LINCK (COMATULA EOSACEA OF LAMAECK). 523 the external layer of sarcode. The spicula are at first blunt irregular cylinders ; but shortly they fork at either end, and at length, by repeatedly dichotomizing and anasto- mosing, they form delicate plates of calcareous network. When definitely developed, these plates are ten in number, and they arrange themselves in two transverse rings of five each, within the wider anterior portion of the pseudembryo, the posterior row being slightly in advance of the pseudostome. These plates are at first round and expand regularly; the plates of the anterior row being arranged symmetrically above those of the posterior series (Plate XXIV. fig. 7.). They are imbedded in the substance of the sarcode, which for some time remains transparent within and without ; gradually, however, the space within the plates becomes turbid and opaque, and at length a rounded brownish granular mass fills up the lower portion of the cup formed by the calcareous trellis. A series, varying in number, of delicate calcareous rings may now be detected, forming a curved line passing backwards from beneath the centre of the lower ring of plates, behind and slightly to the left of the mouth of the pseudembryo ; and a large cribriform plate is rapidly developed close to the posterior extremity behind the anus (Plate XXIV. fig. 6). The rings are regular in their inner contour, but externally they are rough with minute branching spicula and excrescences. About twenty-four hours later the pseudembryo still retains its original form, and its rapidity of movement in the water is unimpaired. The anterior wider portion has become still more bulbous and enlarged, and a thick layer of firm transparent sarcode, thickly studded with columnar oil-cells, forms a dome-shaped arch over the anterior extremity. The sarcode external to the calcareous framework is extremely transparent, and the dark granular hemispherical brownish mass within the lower tier of plates is more clearly defined ; while above it and within the upper part of the space included within the plates, the outline of a second more transparent delicately granular hemi- sphere has become apparent. The two rows of plates are now irregularly square in outline, the plates of the lower series slightly contracted beneath, and those of the upper tier above; so that the ten plates forming the two rows, and now placed in close juxtaposition, form a delicate calcareous basket pentagonal in transverse section and slightly contracted above and below. A hollow sheaf of parallel calcareous rods, united together by short anastomosing lateral branches, is formed within each of the calcareous rings of the series passing backwards from the base of the calcareous cup. These sheaves are, as it were, hound in the centre by the calcareous rings, and the rods remain irregular and constantly increasing in length at either end of the sheaf, the irregular growing ends of the rods of one sheaf meeting and mixing with those of the sheaves next it. Thus we have formed what at first appears to be a continuous curved calca- reous rod; a slight amount of pressure, however, is sufficient to separate the joints from one another, and to show its true structure. The base of the sheaf of rods passing through the last ring of the series abuts against the centre of the upper surface of the circular cribriform plate, now rapidly increasing in size, and becoming more defined in contour, immediately behind the anus (Plate XXIV. figs. 8, 9, & 10). 4b 2 524 PROFESSOR W. THOMSON ON THE EMBRYOGENY OF ANTEDON We have thus the rudiments of the “ pentacrinoid stage” of the Antedon clearly defined and rapidly advancing in development within the body of the pseudembryo, while the latter still retains in perfection its independent form and its special organs of locomotion and of assimilation. I have found it utterly impossible at this stage to trace the formation of the viscera of the young pentacrinoid, on account of the close calcareous network in which the nascent organs are enveloped. From its colour and position, however, there can be no doubt that the mass occupying the base of the cup represents the origin of the stomach with its granular hepatic folds, while the upper more transparent sarcode-hemisphere indicates the nascent tissues of the vault, and at a subsequent stage originates the ambu- lacral ring with its radial branches and the tissues of the young arms. The two rows of plates, enclosing the viscera and forming the cup at this early period, represent the basal and the oral series of plates, which are remarkably suppressed and modified during the subsequent development of the crinoid. The jointed calcareous rod is the stem of the Pentacrinoid, and the circular calcareous plate afterwards supports the round fleshy disk by which the base of the stem adheres to its point of attachment. From six to twenty-four hours later the pseudembryo becomes more sluggish in its movements, and begins to lose its characteristic contour. The anterior extremity becomes somewhat flattened, and then slightly depressed in the centre. The stem of the included crinoid lengthens, and the sarcode of the body of the pseudembryo contracts towards it. The pseudostome and pseudoproct become obscure and are shortly obliterated, the sarcode forming a thick, smooth, uniform layer over the stem and over its terminal disk. The two posterior ciliated bands disappear, the anterior bands remaining entire a little longer, and still subserving the locomotion of the pseudembryo. The anterior bands then likewise gradually disappear, the pseudembryo sinking in the water and resting upon a sea-weed or a stone, to which it becomes finally adherent. At this stage the pseudembryo is irregularly oval and in form slightly contracted posteriorly, expanded and gibbous anteriorly, the anterior extremity flattened or slightly cupped. The posterior extremity expands into a small rounded disk (Plate XXV. fig. 1). Slightly compressed and examined by transmitted light, the Pentacrinoid larva has but little altered from the description given above; the joints of the stem are somewhat lengthened, and the cup is rather more open by the growth and slight separation of the upper portions of the plates of the upper tier. The whole of the pentacrinoid is entirely invested by a thick layer of transparent sarcode, which is merely the substance of the body of the larva which has contracted uniformly over the body and stem of the crinoid, its surface retaining, with the exception of the absence of the bands of cilia, the same character as the surface of the pseudembryo, with the same pyriform oil-cells arranged in the same way, and leaving the same interstices of nearly transparent deli- cately vacuolated sarcode. The head of the crinoid now becomes more regularly pyri- form, and the stem rapidly lengthens. The posterior disk becomes firmly and perma- nently fixed to its point of attachment. The wide anterior extremity now shows a EOSACEUS, LINCK (COMATULA EOSACEA OF LAMAECK). 525 distinct central depression, and the raised external rim indicates a division into five crescentic lobes. The whole cup gradually expands and increases in size. The five basal plates enlarge and become more definite in form. Their upper edges are still irregular in outline, somewhat crescentic, arching upwards towards the bases of the orals ; but the lateral edges are now bounded by smooth straight calcareous bands, the sides of each plate applied with the intervention of a narrow band of sarcode to the similar edges of the two contiguous plates. The narrow lower edges of the basals are rough and irregular, resting on the upper surface of the irregular ring-like rudiment of the centro-dorsal plate. The oral plates likewise undergo a change in form. They become wider infe- riorly, and the sides of the plates towards the lower margin curve outwards, the lower borders thus becoming concave, the convexity turned inwards towards the centre of the body. At the same time the upper edges, which remain narrow and rounded, curve slightly forwards and inwards towards the opening of the cup. If the animal remain undisturbed in well aerated water, when the development of the skeleton has reached this stage, the five lobes (the “ oral lobes”) forming the edge of the calyx gradually expand, till the cup assumes the form of an open bell (Plate XXVI. fig. 1). Imme- diately on opening, at least five, and more usually fifteen, delicate, extremely extensile tentacles are protruded from the cup. The mouth, with the organs immediately surrounding it, is formed even before the separation of the oral lobes. It may be seen occupying the centre of the cup (Plate XXVI. fig. 3) immediately after its expansion, as a large patent aperture. When the cup is fully expanded, the transparent tissue continuous with the five oral lobes, and forming the margin of the disk, seems to curve over uniformly into the wide funnel-shaped central opening. The mouth, however, frequently contracts, though it never appears to close completely ; and when contracted it is bordered by a slightly thickened very contractile rim, which projects over the cavity of the oesophagus and forms an imperfect sphincter. When this sphincter is relaxed and the mouth fully open, it is easy to see down to the very bottom of the digestive cavity, a sac-like space apparently simply hollowed out in the general sarcode-body (Plate XXVI. fig. 3). Commencing immediately within the mouth, a series of irregularly-lobed glandular masses, of a pale yellowish-brown colour, project into the cavity of the stomach, curving in an irregular spiral down to the bottom of the cup. These glandular folds are richly clothed with long vibratile cilia. The merest film of sarcode separates their secretion from the stomach-cavity. The slightest touch, even of a hair, ruptures them and causes the effusion of a multitude of minute granules, some colourless and transparent, and others of a yellow or brownish hue. There can be little doubt from their position and colour that these lobes form a rudimentary liver. They appear very early in the penta- crinoid, colouring the lower portions of its body in the earlier stages of its growth within the pseudembryo. They increase steadily in bulk during its later stages, and with but little change of character make up a large portion of the visceral mass in the adult Antedon. 526 PROFESSOR W. THOMSON ON THE EMBRYOGENY OE ANTEDON A wide vascular ring surrounds the mouth, occupying nearly the whole of the space between the lip and the base of the oral lobes. This ring seems to be simply hollowed out in the uniform sarcode. Its walls are not contractile, it maintains a constant diameter of about 0'08 millim. It is filled with a transparent liquid, which passes like- wise into all its tubular appendages ; and as granules move rapidly in this fluid, the walls of the ring would seem to be ciliated, though hitherto no cilia have been detected, even in sections and under high powers. The upper and outer margin of the ring gives origin to two classes of tubular tentacles. In a very few cases in which I had an oppor- tunity of looking into the cup immediately after its expansion, the total number of these appendages has been fifteen, five extensile, and ten non-extensile. I have never seen fewer ; and I feel convinced that these, with the vascular ring from which they spring, are developed towards the close of the pseudembryonic stage and within the closed cup ; they are protruded so immediately after its first expansion. Radially, the ring gives off five highly mobile, irritable, and extensile tubular tenta- cles, one opposite each of the intervals between the oral lobes. The cavity of these tentacles is continuous throughout, and immediately continuous with the cavity of the oral ring. Their wall seems to consist of a simple contractile sarcode-layer, studded with oval yellowish endoplasts. There is no definite differentiation of a contractile fibrous tissue. Under a high power, however, the sarcode appears to have a longitu- dinal arrangement ; this may possibly be due to motion among the particles producing a play of light. The walls of these tentacles are produced into numerous delicate tubular processes (Plate XXVI. fig. 3 e), their cavities continuous with those of the tentacles. These processes are arranged in three or four irregular longitudinal rows. They are extensile, their walls when extended are extremely delicate, transparent, and apparently structureless. When contracted two or three delicate ring-like rugae appear on the walls of each (Plate XXV. fig. 3). Each process is terminated by a minute three- lobed slightly granular head. At the base of each of these processes there is a delicate crescentic leaf-like fold, slightly granular, and most distinctly marked when the tentacle is retracted. When one of the extensile tentacles is wholly or partially retracted, it is thrown into obscure transverse wrinkles, which give it at first sight the appearance of being divided by a series of dissepiments. When the tentacle is fully extended these folds totally disappear. At the base of each of these five “ azygous tentacles ” there is a conical thickening and enlargement of the sarcode-tissue, contracting outwards towards the tentacle which is continuous with its apex, and whose cavity passes through it to unite at its base with the oral vascular ring. This conical projection is the commence- ment of the young arm. The azygous tentacle terminates it, and leads it out, as it were, up to the point of bifurcation. The tentacle remains persistent for some time in the angle between the two first brachial joints (Plate XXVII. figs. 1 & 3), and finally becomes absorbed and disappears. These five azygous tentacles are the first of a system of “ extensile tentacles” which are subsequently developed in very extended series as appendages of the radial and brachial tentacular canals. In almost all cases, EOSACEUS, LINCK (COMATULA EOSACEA OF LAMAECK). 527 as soon as the interior of the cup can be examined after its expansion, the number of extensile tentacles has reached fifteen ; but from the one or two instances in which the ten additional tentacles have been absent, there can be no doubt that they are developed somewhat later than the five already described. They arise in five pairs, one tentacle on either side of and slightly within the base of each of the azygous tentacles, which they resemble closely in character. They commence as minute csecal diverticula from the canal which passes through the enlarged base of the azygous tentacle, and become rapidly developed into tubular prolongations. At this stage (Plate XXVI. fig. 1), when the cup is open, the fifteen tentacles are usually fully extended, curving over the edge of the cup in the angles between the oral lobes, in threes, the azygous tentacle somewhat longer in the centre, and one of the paired tentacles on either side. Interradially, opposite each of the oral lobes, there is a pair of short tubular tentacles, their cavities likewise continuous with that of the oral vascular ring. These tentacles appear simultaneously with the five azygous extensile tentacles, immediately on the expansion of the cup. They are flexible, but not extensile, slightly club-shaped towards the distal extremity, which is fringed on either side by a single row of short conical tubercles. The base of these tentacles is involved in the contractile sarcode ring sur- rounding the mouth. When the disk is fully expanded they lie in pairs up against the inner surface of the oral lobes. They are frequently, however, gathered inwards together, or singly curving over the mouth. They form part of a very characteristic system of “ non-extensile tentacles,” which afterwards fringe the radial and brachial grooves. At this stage, then, the oral ring usually gives off twenty-five tentacular appendages, of which fifteen are radial and extensile, and ten are interradial and non- extensile. Imbedded in the sarcode at the base of each of the azygous tentacles, a peculiar glandular body is very early developed. At first it consists of a minute vesicle con- taining a transparent fluid. The vesicle gradually increases in size till it attains a dia- meter of about 0'08 millim. in diameter. Its contents become granular, and at length it has the appearance of a large cell with a special wall, included in a capsule formed of a firm sarcode-layer, from which the cell can be turned out unbroken. The cell contains a number of large, irregularly-formed, transparent, slightly granular masses, which are set free by the rupture of the cell-wall. These masses are quite colourless. They are coloured by carmine more deeply than the general substance of the body, and after death they become immediately strongly coloured by the red pigment set free from the perisom. I have been utterly unable to determine the function of these bodies. They are produced in great numbers, during the growth of the pentacrinoid, along the edges of the radial and brachial grooves, and are permanent in the mature Antedon. The only speculation which seems to me at all feasible, a specu- lation which derives some support from their peculiar affinity for colouring matter, is that they are glands connected with the secretion of calcareous solution for the develop- ment and nutrition of the skeleton, analogous to the calcareous glands so constantly met 528 PROFESSOR W. THOMSON ON THE EMBRTOGENY OF ANTEDON with in the pseudembryos and young of some of the other Echinoderm orders. At this early period no general body-cavity can be detected separating the wall of the stomach from the body. The stomach seems to be simply excavated in the structureless body- substance, and the organism corresponds generally with the Ccelenterate type. The external sarcode-layer still retains much the same character which it possessed in the pseudembryonic stage. Its basis is transparent and structureless, with imbedded pyri- form oil-cells, endoplasts, and granules. The stem now gradually lengthens, by additions to either end of the sheaf-like calca- reous cylinders which form the axes of the stem joints, and by the addition of new rings which rapidly become filled up by the vertical tissue, at the top of the stem, imme- diately beneath the rudiment of the centro-dorsal plate (Plate XXVI. fig. 2). The disk of attachment becomes opaque by the addition of calcareous matter, and is firmly fixed. The centro-dorsal ring (Plate XXVI. fig. 2) is more definite in form, though it is still simply perforated in the centre, and in connexion with the sarcode-axis of the stem, and bears no traces of dorsal cirri. The basals expand and form a wide, nearly con- tinuous cup. By the rapid expansion of the body, five diamond-shaped spaces are left at the points where the upturned angles of two oral plates are opposed to the bevelled- off upper angles of two adjacent basals. In these spaces cylindrical spicula appear, which soon become club-shaped, dichotomize, branch, and anastomose into delicate net-like superficial plates, irregularly oval, slightly produced superiorly, their upper, narrower portions resting beneath, and supporting, the gradually extending sarcode pro- jections which are terminated by the azygous tentacles (Plate XXVII. fig. 1). The equatorial portion of the body, the band between the upper edges of the basals and the lower edges of the orals, now rapidly expands. The five young arms extend outwards, their bases carrying out with them a zone of sarcode which gives the central portion of the body a great additional width. The oral plates maintain their original position, so that they are now completely separated from the basals by this intervening equatorial band ; and are left, a circle of five separate plates, each enclosed in its sarcode-lobe, on the centre of the upper surface surrounding the mouth, and enclosing the ten non-extensile tentacles only. The first radial plates begin to thicken, especially towards the upper margin, and this thickening is produced by the growth, beneath the cribriform super- ficial calcareous film, of a longitudinal mass of tissue of the same character as that which forms the cylindrical axis of the stem joints. On the lower surface of each arm, in linear series, immediately above the first radials, two spicula, horseshoe-shaped, with the opening above, appear almost simultaneously, and become quickly filled up with elongating sheaves of longitudinal trellis-work. These extend along beneath the extending arms, and indicate the second radials and the radial axillaries. The upper surface of the arms now becomes grooved by the development, on either side of the central vessel, of a series of delicate crescentic leaves. These leaves are hollow, communicating by special apertures with the radial vessel, and filled with fluid from it. At the base of each of the leaves there is a pair of tentacles forming a group EOSACEUS, LINCK (COMATULA EOSACEA OE LAMAECK). 529 with the leaf, and along with it communicating with the vessel. One of these tentacles (the distal one) is somewhat larger than the proximal; they are both slightly club- shaped, the club-shaped extremity fringed on either side with conical papillae. They are non-extensile, and resemble in every particular the ten non-extensile tentacles early developed from the oral ring. A group consisting of a crescentic leaf and two non- extensile tentacles lies immediately at the base of each extensile tentacle, and a little lower down the arm (Plate XX,VII. fig. 3 d). Minute spicules, some of them simple or key-shaped, and others expanding into a cribriform film, appear in the superficial sar- code-layer along the back or edges of the arms ; and, usually at the base of each of the tentacles, irregularly imbedded in the sarcode-substance, there is one of the calcareous glands. Immediately on the expansion of the equatorial portion of the cup, the wall of the stomach becomes separated by a distinct body-cavity filled with fluid, from the body- wall. The stomach seems to hang in this cavity as a separate sac, attached to the body- wall here and there by sarcodic bands and threads. As the disk expands, the radial canal may be distinctly seen rising from the oral ring, crossing the narrow disk and run- ning along the upper surface of the arm, communicating on either side with the various tentacles and respiratory leaves, and ending at the extremity of the arm in the azygous tentacle. Beneath the radial canal a tubular extension of the perivisceral space passes along the radial grooves. This series of vessels, for which Dr. Carpenter proposes the term “ cceliac canals,” afterwards extends throughout the whole length of the arms. In the mature Antedon Dr. Carpenter has observed a third vessel intermediate between the coeliac and tentacular canals; but no trace of this vessel can be detected in the earlier stages in the development of the pentacrinoid. A little later, the end of the arm shows a tendency to bifurcate, and two half rings, with their enclosed sheaves of calcified tissue, give the first indication of the first two brachials. At the stage which I have described the arm is free, from the base of the second radial ; at a later stage the visceral sac extends to the bifurcation, and the whole of the radial portion of the arm becomes included in the cup and disk. The azygous tentacles go no further than the bifurcation. They remain for some time in the centre, between the two divisions of the arm, while secondary branches from the radial canal run on in the brachial grooves. About the period of the development of the second radials, a forked spicule makes its appearance in one of the interradial spaces between the upper portions of two of the first radial plates. This gradually extends in the usual way till it becomes developed into a round cribriform superficial plate. Simultaneously with the appearance of this “ anal ” plate, a ceecal process like the finger of a glove rises from one side of the stomach and curves towards the plate. The plate increases in size, becomes enclosed in a little flattened tubercle of sarcode, and maintaining its upright position it passes slightly outwards, leaving a space on the edge of the disk between itself and the base of the oral plate immediately within it. Towards this space the csecal intestinal process directs itself. It rises up through it mdccclxv. 4 c 530 PEOFESSOE W. THOMSON ON THE EMBEYOGENY OF ANTEDON in the form of an elongated tubular closed papilla. The summit of the papilla is finally absorbed, and a patent anal opening is formed. The details of these later changes belong, however, more properly to a subsequent stage. Having thus described generally the development of the Pentacrinoid stage of Ante - don up to a point when a marked change takes place in its structure and economy, I shall now discuss, in somewhat fuller detail, certain general considerations arising from the successive steps of the developmental process. The relations of the Pseudembryo. — In Antedon the germ-mass is resolved, at all events to a great extent, into sarcode having the peculiar delicately vacuolated structure so characteristic of this zoological element. The sarcode contains multitudes of “ endo- plasts and of oil-cells and granules scattered through its substance, but these latter I must regard merely as stores of various organic compounds elaborated as secretions and excretions during the development of the organism. In the centre of the sarcode zooid there is usually a darker nucleus, indicating a special accumulation of granular matter. I have satisfied myself, however, that this condition is not essential, as in some cases in which the young were developed in clear water, with a scanty supply of nourishment, the pseudembryo became transparent throughout. Still it is conceivable that a germ of the original substance of the mulberry-mass may be retained to originate the Crinoidal embryo. At all events, the temporary organism which I have termed the Pseudembryo is entirely dependent for its form and structure upon the sarcode into which the whole or the greater portion of the germ-mass is resolved. This sarcode zooid possesses all the peculiarities of the sarcode organisms among the Protozoa and the lower forms of the Ccelenterata. Its external surface is richly ciliated, and if lightly touched with a bristle it moves off rapidly, by means of these cilia, in a direction opposite to the touch, giving -evidence of a high degree of irritability and power of automatic motion, without the slightest trace of a special nervous system. During the early stages of its development, and before the differentiation of a special assimilative tract, the body increases rapidly in size ; the sarcode is therefore capable, as in the case of the astomatous Protozoa, of absorption over the whole external surface, and of assimilation throughout the entire internal substance. Whatever at this stage may be the relations of the granular nucleus of the pseud- embryo, I believe the external ciliated absorbent and irritable sheet of sarcode must be regarded as a special provisional organ for the nutrition and aeration of the nascent embryo. Dr. Carpenter * has already suggested a correspondence between the zooid pseudembryo in the Urchins and Starfishes, and the temporary embryonic structures in * 44 "We Fere find the yolk-mass converted into a structure, ■which, is destined only to possess a transient existence, and which disappears entirely by the time that the development of the offset from it has advanced so far that it begins to assume the characters of the permanent organism. This, however, is what takes place in the higher vertebrata ; for the structures first developed in the egg of the bird hold nearly the same rela- tion to the rudimentary chick, that the 4 Pluteus ’ bears to the incipient Echinus or Ophiura, or the 4 Bipin- naria’ to the incipient Starfish.” — Principles of Comparative Physiology, 4th edit. p. 568. EOSACETTS, LINCK (COMATULA EOSACEA 0 E LAMAECK). 531 the higher animals ; and I have developed the analogy* still further, in tracing the conti- nuity of the cavity of the pseudembryonic appendages in Asteracanthion with the vascular system of the young Starfish. The sarcode cylinder preceding and afterwards investing the embryo of Antedon must undoubtedly be referred to the same category of structures. As the development of the pseudembryo proceeds, a large funnel-shaped ciliated pseudostome with an obscure intestine and a minute pseudoproct are formed ; and the zooid, which at first resembled a Plagiophrys or Difflugia in simplicity of structure, may now be compared to a Vorticella or Bursaria. The alimentary system is, however, extremely simple. The digestive tract is rudi- mentary, and the function of the large funnel-shaped oesophagus, with its loop-like pseudocele, seems to be to produce a rapid and special current of fresh water to the general mass of absorbent sarcode rather than to localize the assimilative function. The functional activity of the pseudembryo appears to reside essentially in the peri- pheral layer. During the earlier stages of its development the central portion consists of a dusky granular semifluid substance, increasing gradually in opacity, and exhibiting active molecular motion; afterwards the centre is devoted to the building up of the viscera of the embryo at the expense of this previously secreted pabulum ; hut during the earlier stages of the growth of the embryo, its increasing bulk does not appear to interfere in any way with the functions of its nurse. Absorption, as indicated by increase in size and weight, is at no period more rapid than when the pseudembryo is losing its special organs of locomotion and assimilation, and becoming torpid and distorted by the growth of the included organism. The hollow cylinder of sarcode forming the independent living body of the pseud- embryo, at a certain stage loses its cilia, its special organs of assimilation are obliterated, it appears to merge its distinct life in a second harmonized combination of organs which has grown up within it, and the whole layer, without the slightest change in structure, subsides into the perisom of the Pentacrinus. Histologically the ectosarc of the pseudembryo must be regarded as having been the integument of the Crinoid throughout, its functions highly modified and exalted for a special purpose. The hard structures of the perisom, the two rows of cup-plates and the stem, are accordingly developed in the substance of this integument ; and the out- line of the Crinoid is thus frequently mapped out in calcareous trellis-work before there is the least trace of the differentiation of internal organs. The stem has clearly no con- nexion with the viscera whatever, it is a temporary appendage to the radial skeleton. Until we have accurate details of the embryogeny of a more extended series from the various Echinoderm orders, I believe it would be premature to discuss at length the morphology of the pseudembryo of Antedon. At present we are acquainted with many species belonging to widely differing genera, scattered apparently irregularly through the four orders of the subkingdom, which produce independently organized pseud- * “ On the Embryology of Asteracanthion vioTaceus (M. & T.),” Quarterly Journal of the Microscopic Society, 1861, p. 99. 4 C 2 532 PKOEESSOR W. THOMSON ON THE EMBRYOGENY OE ANTEDON embryonic nurses, presenting a distinct bilateral symmetry in the arrangement of their alimentary system and natatory apparatus. A certain community of plan appears to run through the swimming group described by Professor Muller ; but subsequent observations would seem to indicate that so high a development of the pseudembryo is exceptional. In genera closely approximated to those in which the pseudembryo is most highly organized, or even in allied species of the same genus, the pseudembryonic appendage is reduced to a mere rudimentary vascular tuft, or to a simple investment of sarcode. My own observations would lead me to suspect that the independent development of the pseudembryo may be greatly modified, even in the same species, under different circumstances of light, warmth, aeration, and nourishment. The pseudembryo of Antedon resembles very closely what Professor Muller has described as the “ pupa stage ” in certain Holothuridea. The young Holothuria, how- ever, has in these instances, according to Muller’s observations, passed through the phase of a pseudembryonic zooid (Auricularia), with a special mouth and alimentary canal, special natatory lobes, and a regular bilateral symmetry, before assuming the pupa form of a closed sarcode-cylinder girded with ciliated bands and devoid of special organs. In Antedon the “Auricularia” and the “pupa” stages are, as it were, fused into one. The “pupa” form is at once developed from the germ-mass, but it is pro- vided with the assimilative organs of the Auricularia, though in a very rudimentary degree. Further metamorphosis proceeds very similarly in both cases. In both the organs of the young are gradually differentiated within a sarcode-cylinder, the branchial tentacles finally protruding through an anterior sarcode dome. The close analogy is highly marked in the Synaptidse, the group whose metamorphoses have been observed by Muller, in which, as in the Crinoids, the oral tentacles are highly developed at the expense of the vessels of the ambulacral region. One or two remarkable differences, however, exist. In Antedon no part whatever of the alimentary canal is adopted by the nascent Crinoid. In Antedon the development of the organs of the embryo is confined to the anterior region of the pseudembryo, the posterior portion containing the stalk, a temporary appendage. In the Holothuridea the whole pupa passes by simple metamor- phosis into the body of the perfect form, the apical pole being occupied by the excre- tory orifice of the alimentary canal. In the Holothuridea the madreporic tubercle and the sand canal, though frequently extremely rudimentary in the mature form, seem uniformly conspicuous during the development of the young. In the pseudembryonic stage of Antedon no trace of this organ has been observed. I believe that, in zoological language, the term “ embryo ” has hitherto been under- stood to indicate a young animal during the early stages of its development ; an orga- nism which is produced by the differentiation of the whole or of part of the segmented yelk, and which is a stage in progress towards the mature form of its species. Any accessory or deciduous parts have usually been termed embryonic appendages ; but these embryonic appendages have always been regarded as parts of the embryo, although EOSACETTS, FIACK (COMATULA EOSACEA OF LAMAECK). 533 temporary, yet partaking during their life, of the life of the embryo, and as affording ho evidence of possessing independent vitality. I imagine that as the term Embryo has not been applied to the yelk, or to the germ-mass before the separation of the organs of the young, it would be a like misapplication of the term to apply it to any stage in the development from that germ-mass of a being whose organs do not homologate with, and never by any subsequent metamorphosis become converted into, the analogous organs of the perfect form. Again, according to the ordinary conception of a “ larva,” it is a stage in the development of an animal during which its external form differs to a greater or less degree from that of the “imago” or mature form, and its organs are greatly modi- fied for the performance of certain functions at the expense of others ; but the organs of the larva are essentially the organs of the imago ; and the individual which is formed of the sum of these organs, and which manifests vital phenomena, is the same individual which subsequently lives as the imago. It is utterly inconceivable that the larva and the imago should exist as separate individuals at the same time. The relations of the pseudembryo are entirely different. It is developed from the germ-mass as a distinct animal form, manifesting a combination of vital phenomena, through a sum of organs which attain a distinct maturity of their own, and which never pass in combination into the sum of the organs of the perfect being. So complete is this independence, that in cases where this type of the reproductive process is carried out most fully, as in Bipin- naria, the embryo is at a certain period cast off from the pseudembryo, and both beings continue for some time to manifest independent life. I would therefore define a “pseudembryo” or a “ pseudembryonic appendage” as any provisional appendage pro- duced from the germ-mass, which manifests the functions of organic and animal life through the medium of a combination of organs which precede and do not homologate with the organs of the true embryo. This appendage may be reduced to a condition of extreme simplicity. It may exist merely as a layer of structureless sarcode, ciliated, and manifesting the form of life characteristic of the simpler Protozoa ; within which the organs of the embryo are gradually built up. In most, however, if not in all the invertebrate groups, the so-called embryo differs greatly in external form from the mature organism. It usually commences in aquatic animals as a “ ciliated germ ” ; and in this condition, whether within the vitelline sac or free after the rupture of the sac, it increases in size by absorption through the general surface. Very usually various lobes and fringes are produced, frequently richly ciliated, extensions of a transparent sarcodic investing layer, within which — but bearing to it only obscure relations in form — the nascent organs of the true embryo are slowly differentiated. During this period the permanent organs, so far as their special functions are concerned, are utterly inert. They are merely growing. The rudiments of the alimentary canal are being laid down, but probably the mouth has not yet “broken through.” The entire zooid, however, is by no means inactive. It moves rapidly through the water, its movements beautifully characteristic, and appa- rently guided by an obstruction-perceiving and light-perceiving instinct. 534 PROFESSOR W. THOMSON ON THE EMBRY 0 GEN Y OE ANTEDON The perfect organic and relative life of this being, closely comparable to the life of the most highly gifted members of the protozoic snbkingdom, does not certainly exist in the sum of the permanent organs ; it resides, I believe, simply in a pseudembryonic sarcodic layer, endowed with the same properties which this zoological element possesses when isolated, as in the Protozoa. Gradually the sarcode eliminates from the products of its own assimilation the constituents, and elaborates the tissues, of the permanent special organs; and when these are sufficiently developed, it loses its own individuality, its vital activity passing into the organs which it has produced, and performing through their medium more effectively and condensedly, functions, which, as a transient nurse- layer, it performed in a manner perfect as to its simple object of temporary nutrition, though somewhat feeble and diffuse. In respect to the essentials of this process, some of the Holothuridea among the Echinodermata seem to conform almost exactly to the ordinary Invertebrate type. The pseudembryonic sarcode-layer is here little more special or independent than it is in the embryos of the Annelids and Mollusks, and infinitely less so than in some Turbellarians ; and the transition from this condition, through the Crinoids, in which a short alimentary canal is formed in the sarcode layer, — and the “Plutei” in which the “ Echinoderm disk” with its accompanying permanent organs is developed within the pseudembryo and covered by its general integument, the whole substance of the pseudembryo being finally absorbed into the embryo, — to the “ Bipin- naria,” in which the independent life of the pseudembryonic zooid is apparently carried to its limit, is so perfectly gradual as to leave no doubt whatever of the uniformity of the embryogenic plan. This being the case, that is to say, a vast number of invertebrate embryos combining in their earlier stages pseudembryonic appendages possessing independent vitality with the nascent organs, no special divergence from the ordinary mode of development is to be anticipated in cases in which the pseudembryo attains unusual individual indepen- dence. We find accordingly the earlier stages in the development of the pseudembryo in the Echinoderms conforming closely to the general mode of development of the “ embryo” of aquatic invertebrates. The earlier stages in the development of the Tissues of the Pentacrinoid. The general connective tissue. — As stated above, the general transparent investment which during the earlier stages of its development makes up the greater portion of the substance of the pentacrinoid, is produced by the gradual extension and modification of the sarcode substance of the pseudembryo. The pseudembryo is moulded from the germ-mass, and at first its surface retains the mammillated structure, the result of the ultimate segmentation of the yelk. At first each spherule retains a trace of the original enclosed endoplast ; this, however, shortly disappears. No cell-membrane can be detected investing these spherules at any period. An hour or two after the rupture of the vitel- line sac, the mammillated structure entirely disappears, the ultimate spherules being fused into a structureless layer. The external layer is firm and consistent. If the ROSACEUS, LINCK (COMATULA ROSACEA OE LAMARCK). 535 pseudembryo die at this stage, shortly after its death, a delicate film is sometimes separated from the surface of portions of the body, similar to the film which is observed under similar circumstances on the surface of Infusoria. I do not believe, however, that this film previously existed as a special membrane; but am rather inclined to think that it is produced after death by the coagulation of a layer of mucous excretion. Pyriform capsules of considerable size, about 0-03 millim. in diameter, are imbedded here and there in the superficial layer. These cells are of a pale yellow colour, full of a yellow fluid, which when the cell is crushed escapes as a round refrac- tive globule. The wide end of the capsule is superficial, the narrower extremity passes inwards and ends in a delicate thread-like process, which is lost in the substance of the sarcode. I have been able to detect no special wall to these capsules, the fluid of which seems simply to be enclosed in a pyriform space in the continuous sarcode : I regard these as reservoirs of oil. The peripheric layer is nearly free from granules ; but passing from without inwards, minute granules, compound granular masses, and endoplasts become more numerous; the sarcode at the same time apparently losing in consistency, till at length, towards the inner surface of the consistent perisomatic layer, it becomes densely granular, and no distinct line of demarcation can be detected between the sarcode which still retains a certain consistency, and the central semifluid protoplasm, in which the granules exhibit active molecular motion. The outer layer, when compressed and examined with a high power, exhibits between the endoplasts and oil-cells a very finely vacuolated structure. Minute spaces, somewhat like the lacunae of bone, filled with a clear liquid, are scattered through the sarcode ; and uniting these there is a system of exceedingly delicate tubules which may be compared to the canaliculi ; they are much less nume- rous, however, only about six or eight apparently radiating from each lacunar space. Even while under observation, the size of these spaces appears to vary, one or two which were prominent in one part of the field gradually contracting and becoming indistinct, while others previously scarcely visible seem to expand into view. I believe that this appearance is caused by the circulation of fluid through the system of vacuoles and vessels by movements depending upon the general contractility of the body-substance. Near the close of the free stage, when the embryo is beginning by its growth to distort the form of the pseudembryo, the integument of the wider anterior extremity of the pseudembryo immediately above the mouth of the embryo seems to become columnar in structure and opaque with closely packed long oil-cells, arranged vertically, and forming a kind of dome. In the earliest fixed stage this dome gradually splits up into the five oral lobes, each with its enclosed oral plate. The devlapment of the Skeleton. — To make the description of the development and relations of the parts of the calcareous skeleton of the pentacrinoid stage of Antedon intelligible, I shall in the first place describe very briefly the arrangement of the hard parts in the mature Antedon and in some nearly allied forms. I shall touch on this 536 PROFESSOR W. THOMSON ON THE EMBRYOGENT OE ANTED ON part of the subject lightly, as Dr. Carpenter is preparing an elaborate memoir on the skeleton of Antedon. I adopt, in concert with Dr. Carpenter, a nomenclature differing very slightly from that proposed by M. de Koninck in his valuable work on the fossil Crinoids of the Carboniferous System of Belgium. I accept for convenience of descrip- tion the division of the body of a Crinoid into three parts, the stem, the head, and the arms. The head consists of two hemispheres, a dorsal or apical, and an oral hemisphere. The former I shall term the cup of the Crinoid, and the latter the disk. It must be remembered, however, that all the radial portions of the head belong morphologically and physiologically to the arms. In the earlier stages of development the radial plates of the cup, and the radial vessels of the disk, form the budding arms ; and it is only at a later period that a distinction is produced between radial and brachial portions, by the development of the visceral mass and the extension of the space for its accom- modation. The mature Antedon has no true stem. The cup is closed beneath by a large circular plate hollowed out above into a small rounded chamber. The inferior convex surface of this plate in Antedon rosaceus is pitted with a series of small rounded depressions perforated in the centre with minute channels communicating with the cavity of the plate. Into these depressions are inserted a number of jointed calcareous cirri. I shall term the circular plate the “ centro-dorsal plate,” and the appendages the “ dorsal cirri.” The centro-dorsal plate in Antedon does not belong to the cup. It represents a coalesced series of the nodal stem-joints in the stalked Crinoids. In Pentacrinus {Neocrinus) asterias (L.), the stem grows by additions immediately beneath the row of basal plates of the cup. These plates are five in number, inter- radial, wedge-shaped, their outer wider ends knob-like, heading and corresponding with the salient angles of the pentagonal stem. Their inner narrower ends nearly meet in the centre, each being only slightly truncated and emarginated, so that the five grooved ends may unite in forming the walls of a canal, which is continuous with the central canal of the stem, and through which the central sarcode-cylinder of the stem passes to branch to special perforations in the first radials. The lower surface of each basal plate is hollowed by a longitudinal groove crenated on the edges, and the five grooves are so arranged that when the basals are in position, they form together a star-like mould, in which the joints of the stem are formed. This cavity holds from three to four stem- joints at a time; one extremely small at the bottom of the mould, the others gradually increasing in size and gradually forced out and added to the lengthening stem, by the growth of those behind them. The joints developed in this position are all nodal, that is to say, they subsequently bear whorls of cirri. The internodal joints, varying in number in different species, are developed afterwards between these, each new internodal joint originating apparently immediately beneath the nodal joint. The dorsal cirri represent a varying number of compressed whorls of the stem-cirri of stalked species which possess such appendages. EOSACEUS, LINCK (COMATULA EOSACEA OF LAMAECK). 537 The centro-dorsal plate with its dorsal cirri in Antedon is therefore the homologue of the stem with its cirri in the stalked Crinoids. The true cup in the mature Antedon consists inferior] y of a delicate rosette of more or less fully coalesced small cribriform calcareous plates ; which have been shown by Dr. Carpenter, in a series of beautiful observations, to be the remains of the row of five basal plates which occupy so prominent a place in the cup of the Pentacrinoid. This rosette is completely concealed in the cavity of the ring formed by the first five radials. Around the basal rosette, and alternating with its segments, five elongated calcareous blocks, triangular in transverse section, the first radial plates, form a column within the base of the cup. In A. rosaceus these plates are entirely concealed by the centro-dorsal plate and by the series of second radials. In some species of the genus Antedon , they project beyond the centro-dorsal plate, forming above its upper edge a closed ring which supports the series of second radials. The centro-dorsal plate, the basals, and the first radials are immoveably cemented together ; they do not, however, coalesce, and may be easily separated after boiling in weak caustic potash. A ring of five second radial plates placed in close contact, form, externally, the base of the cup in Antedon rosaceus, resting within upon the upper surfaces of the first radials, and exter- nally upon the edge of the centro-dorsal plate. Kesting upon the second radials, we have next a row of five triangular axillary radial plates, each bevelled above into two diverging surfaces for the articulation of the first brachial joints. The axillary radials are not in immediate contact laterally, they are separated by minute wedge-shaped prolongations downwards of the perisom of the disk. In Antedon rosaceus, the basals, and the first, second, and axillary radials form the whole of the skeleton of the cup. In certain species of Antedon, as in A. Milleri (Muller, sp.), a series of five minute inter- radial plates are intercalated between the angles of the axillary radials, and in other forms, as in A. Solaris (Lam., sp.), and A. tessellatus (Muller, sp.), the whole of the perisom of the disk is covered with a pavement of irregular flat plates. We are unac- quainted with the development of Pentacrinus ( Neocrinus ) asterias (L.), but in the mature form the perisom of the disk is continuously tessellated, and some of the plates pass irregularly downwards between the axillary radials. In Pentacrinus ( Neocrinus ) decorus (nob.), the surface of the disk is rough with irregularly scattered blocks, like fragments of perforated bricks ; and these descend into the spaces between the axillary radials, though without any regular arrangement. The basal and oral plates. — The first portions of the skeleton which appear are the two rings of five plates each, the plates of the upper ring directly superposed on those of the lower, which form the trellised basket, completely enclosing the viscera of the Pentacrinoid during the early stages of its growth within the pseudembryo. The plates of the upper tier subsequently extend into the five oral lobes, and remain as five valve-like interradial oral plates during the greater part of the pentacrinoid stage. The lower series are the basals. These are permanent, with some remarkable modifi- MDCCCLXV. 4 D 538 PROFESSOR W. THOMSON ON THE EMBRYO OENY OF ANTEDON cations in form, in the mature Antedon. These ten plates appear simultaneously as delicate spicula imbedded within the firm peripheric layer of the pseudembryo, usually only a few hours after its escape from the vitelline sac, and before there is any trace of the permanent organs of the embryo. The spicula are hollow throughout. They are at first simple and cylindrical ; shortly they become club-shaped at each end; each thickened end then divides into two diverging branches, equal in length to the original rod ; these fork in their turn, till on their second bifurcation their branches meet and coalesce with the corresponding branches from the opposite end of the original spiculum. By thus constantly branching and anastomosing on one plane, the spiculum extends into a delicate net-like plate, the meshes of which are at first irregularly hexagonal, but afterwards become rounded. The extending calcareous tubes are constantly closed, and constantly hollow to the end. They appear to grow by the molecular removal of calcareous matter from the back of the growing point, and its deposition in advance. At first all the ten plates are round ; but as they expand they become irregularly square, their edges during the free condition of the embryo remaining rough with sprouting spicules. About the time of the fixing of the pentacrinoid, the basals, which have now assumed a somewhat definite form, narrower beneath and expanding above, have their lateral edges bounded by straight lines, so that the edges of two adjacent plates are closely applied to one another. Even after their edges have become thus defined, the plates go on steadily increasing in size, apparently by interstitial growth. The upper edges of the basals still remain rounded and rough. Their lower edges are likewise irrregular, but these soon become obscured by the growth of the centro-dorsal ring. The oral plates extend principally upwards into the oral lobes, where they become lengthened and somewhat contracted, their edges fringed with diverging pointed spicules (Plate XXVI. fig. 1). . As development proceeds they change somewhat in form. The upper angle is slightly depressed, and the sides at the inferior angles are raised, the raised edges at that stage lying up against the sides of the second radials. Absorption of the inferior portion of the oral plates commences about the time of the appearance of the first brachial joints and of the anal plate (Plate XXVII. fig. 1). Both basal and oral plates consist at first of a delicate cribriform calcified film, formed by the lateral extension of a single layer of calcareous tubing only. As they increase in size, however, they gradually thicken, and this thickening is effected by the network sending in from its inner surface irregular processes which branch and unite to form a second layer not quite so regular as the first, but resembling it in general character. This process is repeated till the plates have attained the required thickness. In the oral plates the thickening is very slight, and is confined to the lower portion of the plates. The stem. — As described above, shortly after the appearance of the spicula indicating the basal and oral plates, a chain of six or seven calcareous rings may be observed curving from the centre of the space between the bases of the basal plates ; behind, and usually somewhat to the left of the pseudostome and pseudocele, and abutting against a round EOSACEITS, LINCK (COMATTJLA EOSACEA OE LAMAECK)/ 539 cribriform plate which makes its appearance at the same time close to the posterior extremity of the pseudembryo, behind and below the pseudoproct. Immediately beneath the basal plates an irregular calcareous ring is early formed, considerably wider and broader than the ordinary rings of the stem. This ring, which is subsequently deve- loped into the permanent centro-dorsal plate, gradually thickens and becomes more regular in form, maintaining its position at the top of the stem, the lower edges of the basal plates resting on its upper surface. During the earlier stages of the growth of the pentacrinoid it is simply a circular band of the ordinary calcified areolar tissue, enclosing a sheaf of the peculiar fasciculated tissue of the stem, gradually enlarging, with a central aperture continuous with the bore of the tube-like stem-joints. It is not till some time after the latest stage described in the present memoir, that the rudiments of the first dorsal cirri appear round its lower contour. The rings which originate the ordinary stem-joints commence as small curved hollow spicules. At first they may often be seen open and imperfect ; afterwards they completely close (Plate XXIV. fig. 6). The inner surfaces of the rings are smooth, the outer roughened with projecting branches. I have only once or twice seen the rings of the stem in this early simple stage. Very soon after their appearance, usually before the pseudembryo has attained its full size, a hollow sheaf of calcareous rods united by minute calcareous trabeculae arises within each ring. The stem-joint increases in length by additions to each end of these cylinders. The centre of the cylinder is occupied by a consistent sarcodic thread running through the whole length of the stem. At this stage no fibrous tissue can be detected, either mixed with the calcified tissue or in the outer perisom. Additions are made to the length of the stem by the formation of new rings immediately beneath the centro-dorsal plate, the new rings becoming, as in the former case, gradually filled up by cylinders of linear cal- cified tissue. As the calcareous axis of the stem increases in width, the original rings girding the centre of the joints expand. They remain permanent during the whole of the fixed stage, and give the stem of the Pentacrinoid its characteristic beaded appear- ance. The terminal plate of the stem is formed on the same plan as the basals and orals. It is developed as a simple round cribriform plate within the posterior extremity of the pseudembryo ; and when this extremity becomes expanded into a disk of attach- ment, it supports and forms the skeleton of the terminal sucker. Afterwards it becomes thickened by irregularly deposited calcareous matter. The layer of soft tissue between the calcareous disk and the point of attachment seems to be at length absorbed, and the stem is permanently fixed by amorphous cement. The first and second radial joints and the axillary radials. — Shortly after the fixing of the Pentacrinoid and the opening of the cup, a third series of five plates make their appearance as minute branching spiculse occupying the spaces left by the bevelling off of the upper angles of the basal plates and the lower angles of the orals, thus forming an intermediate series between the basals and orals, and alternating with them. The spicula indicating the origin of these plates, the first radials, branch and extend in the manner already described, till at length they form diamond-shaped films consisting of a 4 d 2 540 PEOFESSOE W. THOMSON ON THE EMBEYOGENT OF ANTEDON single layer of cribriform calcified tissue. The plates shortly begin to thicken ; but their mode of growth at once distinguishes them as fundamentally different in structure from the basals and orals. Processes are sent inwards from the inner surface of the superficial film as before ; but the added tissue is longitudinal and fasciculated, resem- bling precisely in structure and mode of growth the inner cylinder of the joints of the stem ; and, as in the case of the stem, tubular perforations are formed in it for the passage of the sarcode-cords, which subsequently extend in like channels through the joints of the arms and pinnules. The second radial joints and the radial axiilaries rapidly succeed the first radials, and are developed nearly in the same way. They first appear as horseshoe-shaped spicula, or imperfect rings, which have the same relation to the joints which the stem-rings have to their included cylinders. The spicula soon become filled up with lengthening fasciculated tissue ; the joints at this period are slightly grooved longitudinally on their upper surfaces to accommodate the radial vessels. The anal plate, the interradial plates, and the plates and spicula of the perisom. — Upon the appearance of the second and third radial joints, the perisom between and somewhat above two of the first radials rises into a rounded papilla, towards which a csecal process of the digestive cavity is directed. On the outer side of this papilla a branching spicule appears which rapidly extends into a round plate. This, the anal plate, grows, and afterwards thickens precisely on the model of the basal and oral plates ; it contains none of the fasciculated tissue proper to the radial system. The basal and oral plates, the first and second radials, the radial axiilaries, and the anal plate seem to complete the series of essential parts entering into the cup of the pentacrinoid. In one or two cases however, I have observed about the time of the first appearance of the anal plate, a series of five minute rounded plates developed interradially between the lower edges of the oral plates and the upper edges of the basals. These interradial plates sometimes remain permanent in the mature Antedon rosaceus, and they appear to be constantly present in some species, as for instance in another and a rarer British form, Antedon Milleri (Muller). They usually occur, finally, in groups of three or five. They are irre- gular in form, and they resemble the anal plate in structure and mode of growth. Simple and key-like spicula and small round cribriform plates are imbedded irregularly in the perisom of the arms, often almost covering the second and third radial joints with a dermal calcified layer, but never overlying the basal or oral plates of the body. General remarks on the Skeleton. — The skeleton of the pentacrinoid is composed of two systems of plates, which I shall term respectively the radial and the perisomatic system, thoroughly distinct in their structure and mode of growth. The radial system consists of the joints of the stem, the centro-dorsal plate, the radial plates, and the joints of the arms (and subsequently of the pinnules). The perisomatic system includes the basal and oral plates, the anal plate, the interradial plates, and any other plates or spicula which may be developed in the perisom of the cup or disk. In the recent Pen - tacrini, and in certain species of Antedon, the disk is paved or studded with plates belonging to the perisomatic system, and a double series of like plates fringe the radial EOSACEUS, LINCK (COMATULA EOSACEA OE LAMAECK). 541 and brachial grooves. The joints or plates of the radial system may be at once distin- guished by their being chiefly made up of the peculiar fasciculated (or radial) tissue of parallel rods which I have already described, and by their being perforated for the lodgment of a sarcodic axis. At first each radial element appears to consist of two parts. A stem-joint always commences with an annular spicule, within which the cylinder of “radial” tissue seems to arise. An arm-joint begins with a crescentic spicule, and a radial plate with an expanded single cribriform film. From the strong contrast which these superficial portions present to the tissue which is afterwards developed beneath them, I am inclined to refer the outer rings and films, even of the brachial joints and radial plates, to the perisomatic system, and to regard the radial system of plates as composed essentially of the “radial” tissue alone. The plates and joints of the radial system are singularly uniform in their structure and arrangement throughout the whole of the crinoidal series. They seem to form, as it were, an essential skeleton whose constant general arrange- ment stamps the order with its most important and prominent character. In the Pen- tacrinoid the radial system of radial- and arm-joints supports the extensions of the radial vessels, and the radial vessels with their oesophageal vascular ring clearly arise in con- nexion with the disk, on the oral aspect of the animal. The radial plates arise at the opposite or apical pole. The first portion of the radial system which appears is the stem. When the sarcode-axis of the stem enters the cup, passing through the centro-dorsal plate and between the lower edges of the basals, it splits into five threads which enter the first radial plates, and after a somewhat singular distribution in the walls of the cup, which is not apparent till a later stage, they follow out the growing arms, the arm-joints being moulded round them as they extend. The perivisceral sac lies in the cleft formed by the five radial branches of the stem. The plates of the perisomatic system commence as simple cribriform films imbedded in the outer layer of the perisom, and thicken by a repetition inwards of the same diffuse areolar tissue. They are essentially variable in number and in arrangement ; most of the minor structural modifications throughout the group depend upon the multiplication or suppression of plates of this series. Even in the same species they are by no means constant. In Antedon rosaceus the perisom of the disk is usually naked, but specimens from certain localities have well-defined groups of perisomatic interradial plates developed in the angles between the radial axillaries, and in some individuals rows of similar plates are imbedded along the margins of the radial grooves in the perisom of the disk. The entire body of the Pentacrinoid is, at first, while yet included within the pseudembryo and during its earliest fixed stage, surrounded and enclosed by plates of the perisomatic system alone, and it is quite con- ceiveable that plates belonging to this system may expand and multiply so as to form a tessellated external skeleton to the mature animal, the radial system being entirely absent, or represented only in the most rudimentary form. I believe that all the modifications of the skeleton Avhich characterize the principal divisions of the Echinoderm subkingdom will be found to depend mainly upon the relative development or suppression of the radial and perisomatic systems of plates. 542 PROFESSOR W. THOMSON ON THE EMBRYOGENY OF ANTEDON With reference to the form and position of the oral plates, Professor Allman has sug- gested some interesting analogies between this transition stage of Antedon and the per- manent condition of the fossil genera Haplocrinus, Coccocrinus, Stephanocrinus , and Lageniocrinus. I thoroughly agree with Dr. Allman, that the oral plates of the Penta- crinoid are in all probability homologous with valve-like plates surrounding the mouth only in all crinoidal genera in which such plates occur. In Antedon rosaceus they dis- appear during the later stages in the growth of the Pentacrinoid young, and in all known species of the genus Antedon , even in those with a tessellated disk, they are wanting in the mature form. In Pentacrinus ( Neocrinus ) asterias , (L.), the mature form to which the fixed stage of Antedon is evidently most analogous, they are said to remain permanent. The evidence on this point is as yet extremely defective. It rests entirely upon the descriptions and sketches of M. Duchassaing *, which are sufficiently graphic, hut by no means technically exact. In two nearly allied species, Pentacrinus {Neocrinus) Mulleri (Oersted) and P. [N.) decorus (nob.), in both of which I have had an opportunity of examining the perisom of the disk, the oral plates are totally absent. Almost all Dr. Allman’s illustrations are necessarily taken from a small aberrant family of Crinoids, the Haplocrinidse, of whose structure we know as yet very little. With the exception of Stephanocrinus , which only doubtfully belongs to the group, all the genera are Devonian, preceded by the peculiar Cystideans of the Upper Silurians, and ushering in the carboniferous Blastoids. Notwithstanding Professor Mullek’s discovery of rudimentary free arms, I cannot help still leaning to the view that the triangular interradial valves in the Haplocrinidae may, like the pointed upper tier of interradial plates in the Pentremites, surround not only the mouth, but ovarian and anal openings ; a discussion of the homologies of the fossil Crinoids is however foreign to the object of the present memoir. The development of the assimilative and vascular systems, so far as it has been possible to observe it at this early stage, has already been described in detail. Explanation of the Plates. PLATE XXIII. Eig. 1. Portion of the ovary under slight pressure, showing ova in various stages of development, X 40 linear. Fig. 2, a-o. Ova in various stages, from the first appearance of the germinal spot 2, a to the maturity of the egg 2, o, X 40 linear. Eig. 3. Yelk-granules, X 120 linear. * Quoted by M. de Kokixck, “ Recherehes sur les Crinoi'des du terrain Carbonifere de Belgique,” p. 53. Brussels, 1854. BOSACEUS, LIXCK (COMATULA EOSACEA OE LAMAECK). 543 Fig. 4. A group of parent cells containing vesicles of evolution, and forming a portion of the tissue of the testis, X 40 linear. Fig. 5, a-e. Parent cells with vesicles of evolution in various stages of development, X40 linear. Fig. 6, a-c. Mature vesicles of evolution containing spermatozoa, X 80 linear. Fig. 7. Spermatozoa, X 120 linear. Fig. 8. Egg shortly after impregnation, X 40 linear. Figs. 9-13. The process of yelk segmentation, x40 linear. Fig. 14, a-c. Further enlarged views of the earlier stages of yelk segmentation, showing three groups of the “ direction vesicles,” X 80 linear. PLATE XXIV. Figs. 1-4. The development of the pseudembryo within the vitelline membrane, X 40 linear. In this case the development is somewhat abnormal. Fig. 5. Dorsal aspect of the pseudembryo shortly after the rupture of the vitelline sac, X 40 linear. Fig. 6. Dorsal view of the pseudembryo a little more advanced, X.40 linear. Fig. 7. Ventral aspect of the pseudembryo a little later, showing the pseudostome and pseudoproct, and the rudiments of the cup plates of the embryo, X 40 linear. Figs. 8, 9, 10. Ventral, dorsal, and lateral aspects of the pseudembryo shortly before the disappearance of the ciliated bands, X 40 linear. PLATE XXV. Figs. 1-3. The pseudembryo losing its special organs of assimilation and locomotion and passing into the “ pentacrinoid stage,” X40 linear. PLATE XXVI. Fig. 1. Pentacrinoid larva immediately after the complete separation of the oral valves, expanded, X 40 linear. Fig. 2. Pentacrinoid in the same stage, the cup closed, x40 linear, but afterwards slightly reduced to suit the size of the plate. Fig. 3. A portion of the oral disk of the same stage seen from above, in a state of com- plete expansion : a, patent oral aperture bounded by a ring of contractile tissue, and showing yellow richly ciliated granular folds, arranged somewhat spirally on the walls of the digestive cavity; b, central ring of the radial vascular system ; c, non-extensile tentacles in immediate connexion with the vascular 544 PEOFESSOE W. THOMSON ON THE EMBEYOGENY OF ANTEDON EOSACEHS. ring, ten in number, and laid up in a state of complete expansion in pairs against the inner surfaces of the oral valves f; d, first pair of extensile radial tentacles ; e, azygous radial extensile tentacle leading out the growing arm to its bifurcation, and giving off pairs of tentacles of the same series from its base. X 40 linear. PLATE XXVII. Fig. 1. Pentacrinoid larva immediately before the expansion of the ventral disk: a, centro-dorsal plate ; b, series of basal plates ; c, first radial plates ; d, second radial joint; e, third radial ; f, first brachial joint; g, anal plate; h, stem- joint ; k, cribriform plate supporting the disk of attachment ; l, granular vis- ceral mass ; to, csecal process passing from the stomach towards the papilla which indicates the position subsequently occupied by the anal tube ; n, oral valve and plate. X 40 linear, slightly reduced. Fig. 2. An example in a somewhat earlier stage, expanded, and showing the arrangement of the non-extensile tentacles in connexion with the oral vascular ring, X 40 linear, considerably reduced. Fig. 3. End of an extending arm further enlarged : a, 5, and c, first, second, and third radial joints ; d, superficial spicules and small cribriform plates of the peri- somatic system ; e, lenticular “ gland’”? ; f, radial vessel passing out on the arm to terminate in the azygous extensile tentacle A, after giving off the second paii’ of extensile tentacles k, Jc ; g, leaf and pair of tentacles of the non-extensile tentacular system. X 40 linear. Fig. 4. Pseudembryo uncompressed and observed by reflected light : a , pseudostome ; b, pseudoproct ; c, c, c, c, ciliated bands. X 40 linear. All the figures, except Plate XXVII. fig. 4, have been drawn from specimens under slight pressure, and with a special view to the details of internal structure. The contour has been thus in some cases to a certain extent lost, and the figures, especially those of the pseudembryo, must be understood to represent individuals slightly flattened. BvUb. Trouts. MDCXEEXVT FLate, JXXHI . Ffol. Trams. WtCtQHTT.Flate, XT W Eg 8. Edwin l£.Wliains.JLS. sc. Figl. zgy- T. ajcLnafc.rlfil idv^M.Wli^cms.FLS. sc. Bui. Trans. lUPfTOW VI**,. XXVT 3awm lOSSDiamsiXS. sc. Hf 2. Phub. Trans. MDCCCE^itoeXXM. Edwin. M-WHa-ma TT. S. [ 545 ] X. On the Sextactic Points of a Plane Curve. By A. Cayley, F.B.S. Received November 5, — Read December 22, 1864. It is, in my memoir “ On the Conic of Five-pointic Contact at any point of a Plane Curve”*', remarked that as in a plane curve there are certain singular points, viz. the points of inflexion, where three consecutive points lie in a line, so there are singular points where six consecutive points of the curve lie in a conic ; and such a singular point is there termed a “sextactic point.” The memoir in question (here cited as “ former memoir”) contains the theory of the sextactic points of a cubic curve ; but it is only recently that I have succeeded in establishing the theory for a curve of the order m. The result arrived at is that the number of sextactic points is =m(12m— 27), the points in question being the intersections of the curve m with a curve of the order 12m— 27, the equation of which is (12m2-54m+57)H Jac. (U, H, ns) + (m— 2)(12m-27)H Jac. (U, H, Hg) +40(m-2)2 Jac. (U, H, ^ )=0, where U=0 is the equation of the given curve of the order m, H is the Hessian or determinant formed with the second differential coefficients (a, h, c,f g , h) of U, and, (91, 33, C, 4f, 1?) being the inverse coefficients (^[=5c— f2, &c.), then Q=(g, as, e, f, 2/'> V, if (a1, V , c',f\ g\ h1) are the second differential coefficients of H, then we have b,Q=(b,&, . . X a’,..) (=b,Qg) + ( a, ..XbX ..) (=b,Og); * Philosophical Transactions, vol. cxlix. (1859) pp. 371 — 400. MDCCCLXV. 5 E 546 PEOEESSOE CAYLEY ON THE SEXTACTIC POINTS OE A PLANE CURVE. viz. in +12g we consider as exempt from differentiation (a', b\ d,f',g', H) which depend upon H, and in d,Qg we consider as exempt from differentiation ($, 33, C, Jf, d% z-\-dz -\-\d?z -{-^d3z -\--^diz +xio dsz. 4. Hence if B j = tfcrB* + dyby + dzbg, B 2 = d2xdv + d?yby -+- d?zb„ &c., we have, in addition to the equations U=0, B.U^O, (B?+2B2)U=0, (B?+3d1B2+S,)U=0, (^i + SBfBa-f-dBjBg-f- 3B2-|-B4)Uz=0, of my former memoir, the new equation (B?+10^2+10^?B3 + 15B1^22+5B1B4+10B^3+^5)U=0, and in addition to the equations, (P —ax-^-by-\-cz), - (m-2)B?U+P.-|B2U=0 - ^[(m-l)^H3(m-2)^1b2]U+P.i(^-l-3B1B2)U+B1P.iB2U=0, -*[(*»- l)(^t + ^A) + (m- 2)^,+ 3BS)]U +P-^+6B^2+4aia3 + 3B-)U+B1P.i{B;+8B1^)U+iBiP.4drU=0, giving in the first instance P=2(m— 2), B P=a diU 3 9?U > -P _ 1 (at ■ + 69?92)U _ 4 a?U (9? + 39i92)U a ~2 d?U 99?U 9?U and leading ultimately to the before-mentioned value of n, we have the new equation — wo [(m— 1)(B? + 10B?B2+ 10B2B3 +153^5) + (m— 2)(5dA + 10B2B3)]U + P • T2o(^i + 1 OB JB2+ 10BiB3 4- 15BjB2 +5BA+10BA) U + BtP.* (B}+ 6B2B2+ 4B1B3+ 3B2)U +iB2P. 1 (B»+ +iBsP. | B?U=0. 5 e 2 548 PBOFESSOB CAYLEY ON THE SEXTACTIC POINTS OF A PLANE CHEVE. 5. This may be written in the form -2[(m-l)(B;+10B?9a+10B^3+15B1^)+(»i-2)(5BA+10BaB3)]U + P( B'+IOB^ + IOB^+ISB^ +5B1B4+10B3B3) U + 5b4P( b?+ 63$,+ 43,3,+ 3b22)U +10b2P( b?+ 3BjB2)U +10b3P( BJU)=0; or putting for P its value, =2(m— 2), the equation becomes - 2(b5+10b$2 + 10d$3+15b1b2)U + 53^(3*+ 6b?b2+ 43x3a+ 3b2 )U +10b2P(b?+ 3b,b2)U +10b3P.b2U=0; or, as this may also be written, 2(bs+10b?b2+10b-2b3+15b1b2)U + 5b 4P . b4U + 10baP . b3U + 10b3P . b2U = 0. 6. But the equation n = -| gDH + ADU, which is an identity in regard to (X, Y, Z), gives 31P=lH3‘H’ a3P=t h3,H+A3sU, 3,P=tHaaH+A3,U; and substituting these values, the foregoing equation becomes 2(b* + l0b2b2+10b2b3+15b1b2)U +(5b4Ub1H+10b3Ub2H + 10b2Ub3H)f ^ + A.20b2Ub3U=0 ; or putting for A its value, = g^g(— 3nH+4'vP), and multiplying by fH2 this is 9H2(b* + 10b?b2 + 10b?b3 + lSb^U +15H (b4Ub^H+2b3Ub2H + 2b2Ub3H) + (-3QH + 4>P).10b2Ub3U=0, which is, in its original or unreduced form, the condition for a sextactic point. PROFESSOR CAYLEY ON THE SEXTACTIC POINTS OP A PLANE CURVE. 549 Article Nos. 7 & 8. — Notations and Remarks. 7. Writing, as in my former memoir, A, B, C for the first differential coefficients of U, we have Bv— C^, Gx — Av, Ay — BX for the values of dx, dy , dz, and instead of the symbol B used in my former memoir, I use indifferently the original symbol B15 or write instead thereof B, to denote the resulting value 3i(=^)=(Bv-C^)B,+(CX-A»)^+(A|m(-Bx)B>, and I remark here that for any function whatever O, we have BO= A , B , C X , y , v B,Q, B.Q, B.O =Jac. (U, a, Q), where §=Xx-\-yy-{-vz. I write, as in the former memoir, ®=(a, as, c, f, -fi ( 1 7 m2 — 5 6 m 5 1 ) $>d H } + ^Iy4{(-Um-22)(d.V)H -(10m-18)c>VH} d4Ud,H + 2d3Ud2H + 2d2Ud3H =j^^{(-6m2+18m-12)H2dBH) = — ^ Jac. (U, C>, H), .... (J)* (J) here and elsewhere refers to the Jacobian Formula, see post, Article Nos. 34 & 35. PROFESS OK CAYLEY ON THE SEXTACTIC POINTS OE A PLANE CURVE. 551 for substituting this value of (3Hb— 205 H) the equation becomes divisible by SJ ; and dividing out accordingly, the condition becomes 51m2 — 198m + 183 m — 2 H2 Jac. (U, O, H) +(— 96m+l 6 8)H2(b . V)H+(-90m+162)H2bVH+(120m-240)HbHVH +^(9H2b0-45Ii05H + 40'IbH)=0. 13. We have (see post, Article Nos. 36 to 40) Jac. (U, $, H)=— (d. V)H; and introducing also 5 . VH in place of b VII by means of the formula bVH=b(VH)-(b.V)H, the condition becomes |5Irf-198», + l83 _(6m_6)|H8(3 _ y)H + (_90m+162)H2b(VH) +120(m-2)HbHVH +a(9HabQ-45HQbH+4(WbH)=0, or, as this may be written, (45m2-180m+171)H2(b . V)H +(— 90to + 162)(to— 2)H2b(VH)+12Q(m— 2)2HbHVH +(m-2)S-(9H2bO-45HQbH+40^bH)=0. Article Nos. 14 to 17 . — Third transformation. 14. We have the following formulae, ^Jac.(U, VH, H)— (5m— 11)BHVH+(3to— 6)Hb(VH)=0, . ... (J) S-Jac. (U, V, H)H— (2m— 4 )bHVH+(3m— 6)H(b . V)H=0, . . . . (J) in the latter of which, treating V as a function of the coordinates, we first form the symbol Jac. (U, V, II), and then operating therewith on H, we have Jac. (U, V, H)H ; these give Jac. (U, VH, H), H(3.V)H= f9HVH-3jA^jJac.(U,V , H)H; and substituting these values, the resulting coefficient of HbHVH is ( 45m2-180m+171)f + (-90m+162)^=^ + 120( m—2)2, which is =0. 552 PROFESSOR CAYLEY. ON THE SEXTACTIC POINTS OE A PLANE CURVE. 15. Hence the condition will contain the factor 9, and throwing out this, and also the constant factor 1 . it becomes m— 2 (_ 15w»+60m— 57)HJac.(U, V , H)H +(30m-54)(m-2) HJac.(U, VH, H) +(m-2)2(9H2BQ-45HQBH+40^H)=0. 16. We have BJ(VH)=p..V)H+B#VH, viz. in (B,*. V)H, treating V as a function of ( x , y, z ) we operate upon it with B* to obtain the new symbol B* . V, and with this we operate on H ; in BitV we simply mul- tiply together the symbols B*. and V, giving a new symbol of the form (B2, B^, BaB„) which then operates on H. We have the like values of By (VH) and B2(VH); and thence also Jac. (U, VH, H)= Jac. (U, V, H)H+ Jac. (U, VH, H), viz. in the determinant Jac. (U, V, H) the second line corresponding to V is B*. V, Bj, . V, Bs . V (V being the operand) ; and the Jacobian thus obtained is a symbol which operates on H giving Jac. (U, V, H)H ; and in the determinant Jac. (U, VH, H) the second line is B,rVH, By VH, BSVH (V being simply multiplied by B*, B^, B. respectively). 17. Substituting, the condition becomes (— 15m2 + 60m— 57) HJac.(U, V, H)H -f(30m-54)(m-2){H Jac. (U, V, H)H+ Jac. (U, VH, H)} + (m—2)2 {9H2BO-54HOBH + 40^BH}=0, or, what is the same thing, (15m2-54m+51)H Jac. (U, V , H)H -f (30m-54)(m-2)H Jac. (U, VH, H) +(m-2)2{9H2BO-45HOBH-f40^BH} = 0. Article Nos. 18 to 27. — Fourth transformation, and final form of the condition fora Sextactic Point. 18. I write (5m-12)QBH-(3m-6)HBG=9- Jac. (U, 12, H) (J) OBH+ HB12= B(QH), and, introducing for convenience the new symbol W, -50BII+ HBO=W, 5m- 12, —(3m— 6), 9 Jac. (U, O, H) 1 , 1 , B.12H -5 , 1 , W = 0, so that PROFESSOR CAYLEY ON THE SEXTACTIC POINTS OF A PLANE CTJRYE. 553 or what is the same thing, (8m-18)W + 6&Jac. (U, O, H)+(10m-18)b(QH)=0, we have o — Q W=H50-50BH=i^f-9^Jac. (U, Q, H)— 19. We have also (8m-18)TdH-(3m-6)Hd*-SJac. (U, H)=0, (J) that is =4^9aJaC'(U’'5'’ H)+“H^ and thence 9HW+40^dH = 9H2BO-45HOBH+40^BH = -9Ji^r H5(QH) + 6-2^-)H3M' +4^=9 {-27H Jac.(U, a, H) + 40 Jac. (U, % H)}. 20. The condition thus becomes (15m2-54m-f51) (4m-9)H Jac. (U, V , H)H +6(5m-9)(m-2)(4m-9)HJac. (U, VH, H) + 3(m-2){-3(5m-9)(m-2)Hb(aH)-|-20(m-2)2Hb^} -f (m— 2)2 — 27H Jac. (U, Q, H)+40Jac.(U, % H)} = 0, which for shortness I represent by 3HH-|-(m— 2)2 —2 TIT Jac. (U, Q, H)+40Jac. (U, % H)}=0, so that we have 11= (5m2— 18m+17)(4m— 9)Jac.(U, V , H)H +2(5m-9)(m-2)(4m-9) Jac. (U, VH, H) +(m— 2){ — 3(5m— 9)(m— 2)d(QH)+20(m— 2)2S'^r}. 21. Write *,=(a', 35', C', 0, WXA, B, C)2, where (A, B, C) are as before the first differential coefficients of U, and (cl, V, c’,f, cj, hi) being the second differential coefficients of H, (£f, 15', C', Jf, 0, If)') are the inverse coefficients, viz., Q^b'c'—f'2, See. We have — (m— l)2BTr1=(3m— 6)(3?w— 7)b(OH)— (3m— 7)2B\P> [see post, Nos. 41 to 46), that is (3m-6)b(OH)=(3m-7)b^-|^^B^„ 5 p MDCCCLXV. 554 PEOEESSOE CAYLEY ON THE SEXTACTIC POINTS OE A PLANE CUEVE. and thence 11= (5m2— 18m+17)(4m— 9) Jac. (U, V , H)H -j-2(5m-9)(m-2)(4m-9) Jac. (U, VH, H) +(m_2)|(5rn2-18m+17)B^+(m~3^yr— 22. Now *=(& 35, €, jr, p, B^r1=E^1+2F^1. We have moreover Jac. (U, VH, H) =-^Et7 E'F,, 1 post, Nos. 47 to 50. Jac. (U, V , H)H=— E'F , J post, Nos. 51 to 53. 23. The just-mentioned formuke give II = -(5m2-18m+17)(4m-9)E'F — 2(5m— 9)(m— 2)(4m— 9) 3” FM^ +(m— 2)(5m2— 18m-F17)(E'vF +2FTr ) that is + (5m— 9) (m— l)2(m — 2) 3m — 7 (E^1+2F^1), n = -(3m-7)(5m2-18m+17) E'F +2(m— 2)(5m2— 18m+17) FT'1 (5m-9)(m-l)2(m-2) ■*" 3m- 7 1 2(m — l)(m — 2) (3m— 8) (5m— 9) _ - 3m— 7 * V| or, as this may also be written, (3m— 7)U=— (5m2— 18m-f-17){— 2(m— 1)( m— 2)FTr1 -f (3m— 7)2E4/ } — (5m— 9)(m— 2) { (m-l)(3m-8)F'F1+(3m-7)(3m-8)F^-( m-l)2E« +(25m2-103m+106)(m-2){ -( m-l)F^+ (3m-7)F^ }• PEOFESSOE CAYLEY ON THE SEXTACTIC POINTS OF A PLANE CUEVE. 555 24. But recollecting that Q=(a, 33, G, 4T, fcX&« Bf, S,)2H =(0, 33, C, #, 6, $X< y, d, 2 f, 2) = (-/+^2+2^)=SBaU; and in like manner and therefore Jac. (U, H, Ou)=S Jac. (U, H, U)=0, PROFESSOR CAYLEY ON THE SEXTACTIC POINTS OE A PLANE CURVE. 557 whence also Jac. (U, H, Oh) = 0; and the condition for a sextactic point assumes the more simple form, Jac. (U, H, ¥) = 0. 29. Now (former memoir, No. 32) we have *=(& 33, C, f, <3, B„H, B~H)2 = (l-j-8^3)2 (yzz3+zzxz+xzyz) +(-9 n (x*+y>+zj 5^—20^) (xz+yz+zz)xyz +(— 15Z2— 78Z5+12 la)xyz\ or observing that and xyz , and therefore the last three lines of the expression of 'P are functions of U {=xz-\-yz+zz-\-§lxyz) and H(= — lz(xz-\-yZJrzz)-\-(l-\-2lz)xyz), and consequently give rise to the term=0 in Jac. (U, H, 'P), we may write *=(1 + 8 lz)2(yzzz+zzxz+x3y3). 30. We have then, disregarding a constant factor, Jac. (U, H, SP)= Jac. (x3-iryz-\-zz, xyz, yzzz-\-zzxi-\-xzyz) = *2> y\ *2 yz, zx, xy ^(tf+z3), y%z'+x3), z%^+y3) = (y’—z‘)(z’'-x‘)(x’—y‘), so that the sextactic points are the intersections of the curve TJ=ixz-\-yz+zz+6lxyz=0, with the curve Article Nos. 31 to 33. — Proof of identities for the first transformation. 31. Calculation of (5J+105352+10^B3+15B152)U. Writing B in place of D, we have (former memoir, No. 20) But former memoir, Nos. 21 & 22 ; — B2H =(3m 6)(^_7)ho_ (m-l)2 — B2H = 558 PEOFESSOB CAYLEY ON THE SEXTACTIC POINTS OF A PLANE CTTEYE. and thence *2 ^jy4(18m2-66m+60)HO + (S?iy4(-10m+18)VH +K?iy|(Q)! whence operating on each side with Bn =5, we have (3;+10a>3,+63';3J+12313*)U= j-4 ( 1 8 m! - 6 6m + 6 0 ) ( H3 41 + <63H ) +(^ir4(-10m+18)((3-v)H+9VH> +(^ir3Q- We have besides (see Appendix, Nos. 69 to 74), 3?3,U= pli)3{(3m-6)H3+(-m+3)SH} 3^U= (^?ip(-H3+3H); and thence (43;3,+33,3|)U= ~y3{(90m-21)H3®+(-m+9)®3H} + (^{-4(3.V)H>; and adding this to the foregoing expression for (h?+10B^2+6B^3 + 12B1B2)U, we have (d\ + lOBft, + 105253 + 155 £*) U= ^Ay,{(27m!-96TO+81)H3+(17m2-56»i+51)3H} + (^T)i {(-14m+22)(3 . V)H + (-10m+18)3V . H} ci4 -J-7 — ~va5Q. 1 (to — l)4 32. Calculation of 54U51H+253U52H+252U53H. PEOFESSOE CAYLEY ON THE SEXTACTIC POINTS OF A PLANE CIJEVE. 559 We have Cj.2 1 2-^ B4U=7-— ^ |B2H+B2H -jK® SVH, 4 6 J 1 m — 1 m — 1 5 B3U=t— — TTg BH, 3 (m—iy ’ b2u= 32 (m— l)2 H, B2H=B2H, 3,H=i^T(-3»l+6)3-3H} +(^{2H(3.V)H-13HVHi. But we have, former memoir, Nos. 21 & 25, B2H= — (---~6) Hd> - — VH, m — 1 m — 1 so that the foregoing expression becomes 32 = (^ip{-(8m-16)MBH+pBHVH (3m 6)(3m_?)H^H 6m_14 QBH m— 1 1 m— 1 m— 1 - 3H$B XI - (6m - 1 2)H2d O } +^i?{2H(3.V)H-f3HVH}.; or finally B4UB,H+2B3UB2H+2B2TJB3H = (i3Tj4{(-6ms+18m-12)Hs3+(-17m,H-60m-55)H4>3H} + ^=Ij-4{(2ro-2)H(3.V)H+(8m-16)3HVH} (» • V)H, 560 PEOFESSOE CAYLEY ON THE SEXTACTIC POINTS OF A PLANE CUEVE. 33. Calculation of B2UB3U. This is •S4 (m— l)4 HBH. Article Nos. 34 & 35. — The Jacobian Formula. 34. In general, if P, Q, 14, S be functions of the degrees p, q, r, s respectively, we have identically pF, qQ, rE, sS = 0, B„Q, BJt, BXS V. V* V, B,Q, B*E, B*S or, what is the same thing, pT Jac. (Q, E, S)-#Q Jac. (E, S, P)+rE Jac. (S, P, Q)-sS Jac. (P, Q, E) = 0. Hence in particular if P=U, and assuming U=0, we have — Jac. (E, S, U)+rE Jac. (S, U, Q)-sS Jac. (U, Q, E)=0. If moreover Q=B, and therefore q—\, we have — ^ Jac. (E, S, U)+rE Jac. (S, U, B)-sSJac. (U, a, E)=0; or, as this may also be written, — B Jac. (U, E, S)+rE Jac. (U, 3-, S)-sSJac. (U, 3, E)=0; that is —3 Jac. (U, E, S)4-rE3S-sSBE=0. 35. Particular cases are (2 m— 4) op„3„3,) =(i».+Sa,+«8,, ®3,+;f3»+C3J>, p, >). Also B=(Bv — Ciw-)ba.+(C?i — Av)dy-l~(Afjti — Bx)B_ = XP -f- ftQ -f- vR, if for a moment P, Q, B=CB2,— BB*, AB,-CB,, Bdx—Adr Hence 3.v=(px+Qfl+&).(aa,+©39+®3„ i3,+u3,+Jfa=, ga.+.fa.+cajex, p, ,), viz. coefficient of X2 =P8dJf+P%d,+PGd„ and so for the other terms ; whence also in (B.V)H the coefficients of X2, &c. are (pgB.+pfcB,+p«3jH, &c. 37. Again, in Jac. (U, H, =(£1, 13, C, jf, (0, (*, v)2, the coefficients of X2, &c. are Jac. (U, H, 91), &c. ; and hence the assumed equation (B .V)IJ=Jac. (U, H, O), in regard to the term in X2, is (Pa3.+Pfc3f +M3.)H=Jac. (U, H, 3), and we have Jac. (U, H, 3)= A , B , C B,H, B^H, BZH , B, , 8 = [B.tH(CB,-BBJ+ByH(ABs-CB,)+B,H(BBx-AB,)]g[ =(B,H.P+B,H.Q+B,H.R)a; 5 G MDCCCLXV. 562 PROFESSOR CAYLEY ON THE SEXTACTIC POINTS OE A PLANE CURVE. so that the equation is P^H+Pl^H+P^JH = Pg^H + Q^H + Kgb JH, or, as this may be written, [{Bd.-Cd,)^-(Ca#-AB,)a]BfH +[{BB,-caje-(Aaf-BB#)sri^=o. 38. The coefficient of c^H is =AB.a+BB.®-C &&+*#), which, in virtue of the identity, post. No. 40, ^+^1+^=0, is =AA$+BBJj+Cd*,9)+c(d,b--d„l i) +/(-23/+3,<,+9^)+5-(3/-3,S)+A(-V+3/), PEOFESSOE CAYLEY ON THE SEXTACTIC POINTS OF A PLANE CUEVE. 563 where the coefficients of A, c, f g , A separately vanish : we have of course the system d,.(S + c^#+ d*C = 0. Article Nos. 41 to 46. — Proof of identities for the fourth transformation. 41. Consider the coefficients (a, b, c, f g , h) and the inverse set (9L B, C, Jf, • -1^ +% • -)2 =(a', . .X^r, y, z)X<&, . .X«', • •)— (3, • .X«'®+%+^> • -)2> where (91', . .fa, . .) and (91, . . \a!, . .) stand for (3', as', C', J', (S', i'X«, b,c,2f,2g, 2h) and (a 3 , C , jr , @ , » Jo!, K c, 2 If, 2^, 2A>) respectively. 42. Taking (a, b, c,f g, A), the second differential coefficients of a function U of the order to, and in like manner (a', A', c',f, g', h1), the second differential coefficients of a function U' of the order to', we have to (to - 1)U . (91', . 0C&„ ch)2U' - (to - i)2(9T, . -X^,U , 3,U , BJJ )2 i)U' . (a, . oca., cg2u — (to' — i )2(9i , . .xa.u', a,u', bjj')2; and in particular if U' be the Hessian of U, then to'=3to — 6. 43. Hence writing Q =(3, . . X*« ^)2H, ^ =(91, . -X^H, ^H, B.H)2, Q>=(a', • • X*.» ^)2U, ^=(91', . -X^U, 3,U, BSU)2, we have TO(TO-l)U01-(TO-l)2^1=(3TO-6)(3TO-7)Hn-(3TO-7)2^; or if U=0, then -(to - 1)2^=(3to- 6)(3to- 7)HQ-(3to-7)24'; whence also — (to— l)2Blr1=(3TO— 6)(3to— 7)(HBO+OhH)— (3to— 7)2Blr, which is the formula, ante No. 21. 44. Recurring to the original formula, since this is an actual identity, we may operate on it with the differential symbol ~d on the three assumptions, — 1. ( a , b, c,f, g , A), (91, B, C, Jf, (S, H) are alone variable. 2. (i a /, A', c',/', y', A'), (91', B', (S', JT, (S', $?') are alone variable. 3. ( x , y, z) are alone variable. 5 g 2 564 PROFESSOR CAYLEY ON THE SEXTACTIC POINTS OF A PLANE CURVE. We thus obtain +(«, . .Jx, y, z)2(9f, . .Jda, . .) — 2(9f, • .Jax+Tiy+gz, . .Xxba+ifbb+z^c, . .) {a,..Jx,y, Jo,..) -(d£T, . -Xax+hy+gz, . .)2 2 (a, . Jjr, y, zjdx, Sy, Sz)(9P, . •!«, . •) .Xa%+hy+gz, . XaBar+ASy+ySs, .) = (*,.. X*,y, — (hgl, . .Xa'x+h'y+g'z, . .)2, = (da',..X*, y, *)’(&.. X«', ..) +(®', . -X#, y, ^)2(9[, . -X^a', . .) — 2(91, . .Xa'x+h'y+g'z, . .Xxda'+ybti+z'dg', . =2(a', . .Xx, y, zXdx, Sy, S*)(9k . -X«', • •) -2(91, .Xdx+Ky+tfz, . •Xaftff+A'Sy+y'Sas, 45. If in these equations respectively we suppose as before that («, b, c,f, g, h) are the second differential coefficients of a function U of the order m, and (a-, b1. c',f , g', hi) the second differential coefficients of a function U7 of the order m'; and that (A, B, C), (A', B', C') are the first differential coefficients of these functions respectively, then after some easy reductions we have (m-l)(m-2)SU(9f, . Ja, . .) = . .X • •)]} — (m — l)a{S9L', • -XA, B, C)2+(&', . .XA, B, C^A, SB, SC)}=m'(m'-l) &c., viz., this is the derivative with S of the equation m(m— 1)U(9P, . .X«, • . )-(m-l)2(! 9', . -XA, B, C)2=m'(m'-1) &c. 46. Taking now U'=H, and therefore m'=3m— 6 ; putting also U=0, SU=0, and writing as before E^B =(S91, . -XA', B', C')2, FTr =(9(, . . XA', B', C'X^A', SB', SC'), E¥‘=(Sa,J ..XA, B, C)2, ?%=(%', • . XA, B, CX^A, SB, SC), EH =(S3, ..x«'> ••)> m=(9, .. x^®'* • •)> PROFESSOR CAYLEY ON THE SEXTACTIC POINTS OF A PLANE CURVE. 565 then the three equations are -2(m-l)(m-2)F^1=(3m-6)(3m-7)HEO-(3m-7)2E'F, - (m - 1)2E^ = (3m-7)(3m - 8)OBH + (3m- 6)(3m— 7)HFO -2(3m-7)(3m- 8)F^, -2(m-l)F^ =2(3m-7)QdH-2(3m-7)F% whence, adding, we have - (m— l)2(EJq + 2F'P1) = - (3m- 7)2(E^ + 2F*) +(3m-6)(3m-7){OBH+H(EQ+FO)} (that is - (m- l)*d% = - (3m- 7)W + (3m- 6)(3m- 7)B . OH, which is right). And by linearly combining the three equations, we deduce (3m— 6)(3m— 7)HEO=— 2(m— l)(m— 2) F'F, + (3m-7)2E*, (3m— 7)OBH = -(m-1) F^+(3m-7) F*, (3m- 6)(3m- 7)HFQ= (m- l)(3m- 8)F*~ + (3m- 7)(3m- 8)FF- (m-l)2E% , which are the formulae, ante, No. 24. Article Nos. 47 to 50. — Proof of an identity used in the fourth transformation , viz., Jac. (U,VH,H)=-3,^Fi'1, or say Jac. (U, H, VH)= (ST, . .JA, B, CJdA, BB, BC). 47. We have v=(0, • -IK t>, 3,. 9.) =((& & ^ »), (fi, 33, JflA, (6, f, CB. OP- 9,. 3.) : or, attending to the effect of the bar as denoting the exemption of the (91, . .) from dif- ferentiation, Jac. (U, H, VII) = (& % <£!*., [*, v) Jac. (U, H, BXH) +0£b 33, 4fB, (a, v) Jac. (U, H, ByH) + (®, f, CB, h v) Jac. (U, H, B;H). 48. Now Jac.(U, H, BxH)=^g Jac. (U, tfBxH+yByH+zB2H, BXH), and the last-mentioned Jacobian is =BXH Jac. (U, x, BxH)+ByH Jac. (U, y , BxH)-f B2H Jac. (U, 2, BXH) +y Jac. (U, ByH, BxH)+z Jac. (U, B2H, BXH), 566 PROFESSOR CAYLEY ON THE SEXTACTIC POINTS OE A PLANE CURVE. where the second line is = -y Jac. (U, B,H, d,H)-M Jac. (U, bsH, dJEI), or writing (A', B', C') for the first differential coefficients and (a', V, c', f, g\ h!) for the second differential coefficients of H, this is =-y ■y A, B, C +z A, B, C a', h', g! 9\ /', o’ V, v, f a', h', g’ = -*/(C', Jf', C'XA, B, C)+*«', 33', Jf'XA, B, C). The first line is A, B, C A', B', C' a'. A', 9' = A(B7/ - C'h') + B(C 'a' - Mg') + C(A'A' - B V), or reducing by the formulae, (3m— 7)(A', B', 0)=(a!x^h!y-\-g’z, tix+Vy+fz, g’x+fy+c’z), this is =sM-7 {H-®y+®z)+*{-tfy+®z)+c(-®y+f'*)\ =ii=7 {-?(«’. «'XA> B, C)+Z(»', S', Jf'XA, B, C)}. Hence we have Jac.(U, H, a„H)=3A6 (1+aMf) < -?(«'. JT. «PXA. B, C)+2(S', S', Jf'XA, B, C)} =3^7 { C'XA, B, C) +z(®'3', Jf'XA, B, C) } ; and in like manner Jac. (U, H, B,H)= 3m — / 1 Jac. (U, H, 3,H)=^ 49. And we thence have {-*(£', W, C'XA, B, C)+4 ^ v ) (9T, 1', C'XA, B, C), (!', 33', Jf'XA, B, C), (C', Jf', C'XA, B, C) x , y z, or multiplying the two sides by H, a, A, g K i, f 9> f> 0 PROFESSOR CAYLEY ON THE SEXTACTIC POINTS OF A PLANE CURVE. 567 the right hand side is '3m— 7 which is if for a moment =H 3m — 7 HA , HjU, , Hv X , Y , Z i— 1)A, (m-l)B, (m— 1)C. x , V 1, X, Y, Z A, B, C, x=(3', . ..XA, B, CX«, h, g), Y=(3', ..XA, B, C z =(3', • • XA, B, CX?,./, c). 50. Hence observing that these equations may be written X=(9T, . . -XA, B, CXc>,.A, B,B, B,C), Y=(sr, . . XA, B, CXB,A, B,B, B,C), Z = (&', . . -XA, B, CXB2A, B,B, BgC), and that we have B = A , f* » Bz A, B, c, we obtain for H Jac. (U, H, V, H) the value =H m — 1 ^7(a', . . OCA, B, CXBA, BB, BC), or throwing out the factor H, we have the required result. Article Nos. 51 to 53. — Proof of identity used in the fourth transformation , viz., Jac./U, V, H)H=-E^, or say Jac. (U, H, V)H=(B& . . -XA', B', C')2. 51. We have V = (($, % v), (% IS, tffk, y, v), (<§, f, CX^, 0X^« ^ ^«)> and thence B . V =((B$, B Jh Ba(§X^ *), BJ6, BjfXA, (*> d*CX*> (*, V)J$« \ d«). and (3,. V)H=((3.a, 3,®, 3.©X^ f*> *)> (3.fe 3,4fXA, ,), (3,®, 3,#, 3,CX>-, f*. »)XA', B', O 568 PROFESSOE CAYLEY ON THE SEXTACTIC POINTS OE A PLANE CURVE. with the like values for (c^ . V)H and (cL . V)H. And then Jac. (U, H, V)H= A , B , C A' , B' C' P..V)H, (3„.V)H, in which the coefficient of A'2 is =(cd,-Ba.xa> % aix, o; or putting for shortness (Cby-Bb2, AB2-C^„ B3,-Acy=(P, Q, R); the coefficient is im, m, p ft, o- 52. We have <3=(PA + Q^-f Rv), and thence coefficient A'2— d$=(P$, P$2, P(§X^> v)~ Q*3, R$X^ v\ which is = /»{(ca,-Ba,)®-(aa.-cd#)a} +» {(ca,-BB.)«-(Ba.-aB,)a}, where coefficient of p is and coefficient of v is so that =- Aa,0-BB2l+cp£+a,£) = -(A3,g+B3..i + C32©)=-^I*3,H, = +(A3„a+B3,»+C3,®)= coefficient A'!-3Sl= 53. And by forming in a similar manner the coefficients of the other terms, it appears Jac. (U, H, V)H-(3a, . . -XA', B\ C')2 1 or since the determinant is ^(A'w+3'y+Gz) A' , B' , G , (* » V a,H, bj,H, B,H. A'', B', C' , =0, a , v A', B\ G we have the required equation, Jac. (U, H, V)H=(B& . . -XA', B', C')2. This completes the series of formulae used in the transformations of the condition for the sextactic point. PROFESSOR CAYLEY OFT THE SEXTACTIC POINTS OF A PLANE CURVE. 569 Appendix, Nos. 54 to 74. For the sake of exhibiting in their proper connexion some of the formulae employed in the foregoing first transformation of the condition for a sextactic point, I have investigated them in the present Appendix, which however is numbered continuously with the memoir. 54. The investigations of my former memoir and the present memoir have reference to the operations "bg-\-dy 'd!/-\-dz dz, d2= d2xbx + d2ydy + d2zbz , d3 =d3xdx-\-d3yd2/-\-d3zdl!l, &c., where if (A, B, C) are the first differential coefficients of a function U = (#]£#, y, z)m, and X, (Jj, v are arbitrary constants, then we have dx= Bv—Cp, dy=CX—Av, dz=A(i>—B\; so that putting b=(Bf— (»b, + (Cx-Avfiy + (A^ - = A, B, C ^ , l* , v a., a„ *tt we have ch = cb The foregoing expressions of (dx, dy, dz) determine of course the values of (d2x, d2y, d2z), (d3x, d3y, d3z ), &c., and it is throughout assumed that these values are substituted in the symbols d2, b3, &c., so that dn =d, and d2, d3, &c. denote each of them an operator such as Xbr + Yc^ + ZcL , where (X, Y, Z) are functions of the coordinates; such operator, in so far as it is a function of the coor- dinates, may therefore be made an operand, and be operated upon by itself or any other like operator. 55. Taking (i a,b,c,f,g,h ) for the second differential coefficients of U, (£1, 33, C, Jf, (3, i?) for the inverse coefficients, and FI for the Hessian, I write also o> =(&... X*,^ V)\ v =(& . . 0Ca„ a„ a.), □ =(&... xa« bj, S3 =Kx-\-^y-\-vz^ Q=(a, ...xa« a„ bjh, =dh, T=(a, ...X^H, 3,H, cLH)2, T =(a, . . ."yjyidg— vbp, vbJ—Xdz, Xd^—yid^)2, 5 II MDCCCLXV. 570 PEOFESSOE CAYLEY ON THE SEXTACTIC POINTS OF A PLANE CUE YE. and I notice that we have ru=2d>, VU~H, □U=3H, 5 TO— 1 5 5 V^= O, V2U=Hd> , V.3 = 0 , the last of which is proved, post No. 65 ; the others are found without any difficulty. 56. I form the Table 3,11=0, a;u=^U 1 TO— 1 _ TT toU , , . S2U=s3T(-4>) a;u=-=^r3 1 TO— 1 $2 32 + (TO- If $2 (H), + s2 + + (to— l)2 32 (3H), a1asu=o, 3;U=^(4-) +^(-H, y, z)\a , . .\yy— v(3, m—Xy, X^-yuf — ax+hy+gz , hx+by+fz, gx+fy+cz 2 X , fo , v “ P 7 = (91, • -Xxp — vp — y§)2, (if for shortness j9=ax-^~Py-\-yz, §='kx-\-yjy-\-vz) = —2p&(8, . .J\, yj, *}>, P, V) +V(%,..ja,p,yy. 58. If in this equation we take ( a , b, c,f, g, h) to be the second differential coefficients of U, and write also (a, /3, y) = (dx, <3y, cL), the equation becomes m{m— l)Ur — (m— 1)2B2= $(xbx-{-yby-\-zbzy‘ —2 +S2D, which is a general equation for the transformation of B2(=df). 59. If with the two sides of this equation we operate on U, we obtain m(m— l)UrU — (m— l)2d2U = m(m-l)ffiU — 2(m— 1)WU +^2DU; and substituting the values FU=2d>, VU=^tH, □U=3H, we find the before-mentioned expression of h2U. 60. Operating with the two sides of the same equation on a function H of the order mf, we find m(m- l)UrH - (m- l)2b2H= -2(m'-l)WH + S2DH; and in particular if H is the Hessian, then writing m'=3m— 6, and putting U=0, we find the before-mentioned expression for d2H. 61. But we may also from the general identical equation deduce the expression for (dH)2. In fact taking H a function of the degree m' and writing (*, 1 3, y)=(3xH, 3,H, bJE), 5 h 2 572 PROFESSOR CAYLEY ON THE SEXTACTIC POINTS OE A PLANE CURVE. we have m(m-l)U(a, . vdxH-Xd,H, XdyH-{*dxH)2-(m-l)2(dH)2 =m'2$H2-2mMVII+^2(a, . 3yH, BZH)2; and if H be the Hessian, then writing m'=3m— 6 and putting also U=0, we find the before-mentioned expression for (bH)2. 62. Proof of equation 5.= -^l(*Uj5,+^)+^V. We have d2=B.d = {(Bv-C^)Bx+(Cx-A^+(A^-B^}. (*(C3S-B3.) +MA3- C3.) + »(B3.- A3,)), which is =X(Od,-B^,)+KA^-CB#)+F(B'd#-A'af), where A'=BA=«(Bi/ — Q*)+A(Cx — Av)-\-g(A(jj — Bx) =\(hC-gB)+p(gA-aC)+V(aB-hA), with the like values for B' and C'. Substituting the values (m— 1)(A, B, C )=(ax+hy+gz, hx+by+fz, gx+fy+cz), we have (m-l)A'=x((By-^+Kfy-^)+K€y-fz); and similarly (m— l)C'=x(i^:— %)+^(3S^— %y)+*($x— %), and then (w-l)(C'd,~B'B,)= \\_{%x-9iy)by +^[(33^— Ifoy^y—a&z—tfxjb^ = x[(®, 33, fx^, ^)-»(^.+y^+^.)] +»W«, 4f, ^ a.)-®(*&,+yB,+*a.)] = <8, ...B, /*, d*)— (& <^XX> v){^x-\-y^y+zbz)\ that is (Bi-lXCra,-»a.)=aV-(a, ©, ex\ p, »)(*M-3«,+sa.), and so («i-i)(A^-aaj=yv-fli, 33, jrxx, & 0(*a.+ya,+*&.), (j»-l)(Bfc.-A^)=*V-(«, jf, CXA, p, V){x-bx+ybs+z\); whence (m— l)d2=(X#+^-f^)V— (gl, . . . JX, v)2(#d,+^,+zdz) »•= • -At ^,+^,+^)+Ai v. or finally PROFESSOR CAYLEY ON THE SEXTACTIC POINTS OE A PLANE CURYE. 573 63. This leads to the expression for d2U ; we have ~{m— l)2 -(^LTfp 3>V(ffBJ+yB9+zB,) _l_ — yz . ' (m — l)sV ’ and operating herewith on U, we tind b*u= 7(ot ili&V 2 [in- 1)2 2(to — 1)S (to — l)2 ovu +(^rrpV!U; this is VU=— H, V2U=HcJ>, (to— l)2 ~(to— 1) 64. We have B,B2U=0, and thence that is (B^2+B1b3+B2)U=0, B1B3U=-B^2U-522U; or substituting the values of B2d2U and d2U, we find the value of d,d3U as given in the Table. And then from the equation (^+6B2d2+4dA+3BI+d4)U, or d4U= _(BJ + 6dft2 + 4d,d3 + 3B2)U, we find the value of d4U, and the proof of the expressions in the Table is thus com- pleted. 65. Proof of equation V.d = 0. We have v. b=v. ((b*-<»b, +(Cx-a*)b, +(a^-bx)b.) =V . (A(pB„-iB,)+B(.B#-XB„) +CQb,-ttij) = VA (pB.-iB,) + VB(jB,-xB,)+ VC(xB,-a.B,) ; and then VA=(g, ...£*■> (a, vja, h, g )=HX, VB = (& ...IX, p, Oft B,/)=Hp, VC=(a --.B, c)= H„; or substituting these values, we have the equation in question. 574 PROFESSOR CAYLEY ON THE SEXTACTIC POINTS OE A PLANE CTJRYE. 66. Proof of expression for B3. We have V; and thence operating on the two sides respectively with B1? =B, we have s>= — Al { 3(.'i3„+y3»4- zd,)+ n-V2=Hr; and then multiplying by B, and with the result operating on U, we find Now and thence and observing that OnBU— V2BTJ=HTBU. □ u=(2, B„ BJ2U =(& h, c, 2/, 2 g, 2 h); □ BU = (9[, ...Jjba, B5, Be, 2B/, 2 By, 2BA) ; *, / 9, /> c PROFESSOR CAYLEY ON THE SEXTACTIC POINTS OF A PLANE CURVE. 575 and thence that dH= d«, d^, d. , V2dU=d>dH-Hd$. 69. Proof of equation d1d2U=-7^:Yy2(OdH— IidO). We have ^2= (m- i]2^2(^d,r +ydy + zZzy — (to- i)2 ^(^df+ydj+sdJV _i_— — V2- T (m-l)2 ’ 576 PEOEESSOE CAYLEY ON THE SEXTACTIC POINTS OE A PLANE CUEVE. and thence multiplying by B1? =5, and with the result operating upon U, we find 3^u=(^l(7-2)^3u-^a^vu+^sv»u. But BU=0, and thence also V(BU)=0, that is (V .B)U + VBU = 0; moreover V . B=0, and therefore (V. B)U=0, whence also VBU=0. Therefore or substituting for BV2U its value =BH — HB<1>, we have the required expression for B^U. 70. Proof of equation B 2B3U = j~_ (( 3 m — 6)HB d> -f ( — m-f- 3)<1>BH) + ^3- { — (B . V)H[ . We have + V, and thence multiplying by B?=B2, and operating on U, B^U^-^BWU- -J- $B3U + -^(B . V)B2U. i 3 m— 1 m— 1 1 in — lv ' To reduce (B . V)B2U, we have and since B(VB2U)=VB3U+ (B . VB2)U =VB3U + [(B . V)B2+ V(B . B2)]U =VB3U + (B . V)B2U+2VBB2U, multiplying by VB, and with the result operating on U, we obtain VBB2U= - ■ VBU+ ——7 V2BU ; 2 m — 1 1 m— 1 or since VBU=0, this is VBB2U = -^-,V2BU. Hence m~1 B(VB2U)=VB3U+(B . V)B2U+~ V2BU, that is m (B . V)B2U=B(VB2U)-VB3U-~ V2BU. Substituting this value of (B . V)B2U, we find B2B3U= -^Bd>B2U- --7 $B3U m — 1 m— 1 (3(V3!U)— V3*U) +p^)2(-2V"3U), the three lines whereof are to be separately further reduced. PROFESSOR CAYLEY ON THE SEXTACTIC POINTS OE A PLANE CURVE. 577 71. For the first line we have d2U= — d3U=-— ~VgBH, and hence (m — l)2 [m-lf first line of BJB3U=^^((m-2)HB + BH). {m— 1) 72. For the second line, we have that is V(B2U)=VB2U + 2(V .B)BU =VB2U, since V . B=0, and therefore (V . B)BU=0 ; V9>U=V(yU)=v(£Y$__|_sH) or writing this is whence also Similarly =^(UVO+$VU)--^I?(^VH+2^HVa); 3 U=0, VU= — H, V^=<1> ’ m— 1 ’ {m — 2)5 VB2U= (: m — l)2 Hd>— s2 (m-iy VH, 3(V3-U)=^A|(H3+UV(3))-fS^Tp(a!V(3H)+2&Va3H); or putting U=0, VU= V&=<*>, 1 m— 1 ’ ’ and observing also that V(BH), = VBH+(V . B)H is equal to VBH, that is to BVH, we obtain V3>U= {-^I)i(mH34>-24.3H)-^i?BVH; and then from the above value of B(VB2U), we find B(V35TJ)-V3*U=^Tp(-2H34.+m4>BH)+(^~1(-3(VH)+BVH); •&2 or observing that the term multiplied by ^m_^2 is = — (B . V)H, we find second line of B2B3U=^Ip(-2HB+m$BH)+ . V)H). 5 i MDCCCLXV. 578 PROFESSOR CAYLEY ON THE SEXTACTIC POINTS OF A PLANE CURVE. 73. For the third line, substituting for V2dU its value =d>BH— Hdd>, we have 2$2 third line of d2d3U= — H<3). 74. Hence, uniting the three lines, we have 3?3»U = ^Ays((m -2)H33H) + (^( -2H34.+ + (^^53((2m-2)H34>+(-2m+2)4>aH), and reducing, we have the above-mentioned value of d2c)3U. C 579 ] XI. A Description of some Fossil Plants , showing Structure , found in the Lower Coal- seams of Lancashire and Yorkshire. By E. W. Binney, F.B.S. Received May 12, — Read June 15, 1865. Introductory Bernards. Although great attention has been devoted to the collection of the fossil remains of plants with which our coal-fields abound, the specimens are generally in very frag- mentary and distorted conditions as they occur imbedded in the rocks in which they are entombed ; but when they have been removed, cut into shape, and trimmed, and are seen in cabinets, they are in a far worse condition. This is as to their external forms and characters. When we come to examine their internal structure, and ascertain their true nature, we find still greater difficulties, from the rarity of specimens at the same time displaying both the external form and the internal structure of the original plant. It is often very difficult to decide which is the outside, different parts of the stem dividing and exposing varied surfaces which have been described as distinct genera of plants. The specimens were collected by myself, and taken out of the seams of coal just as they occurred in the matrix in which they were found imbedded, by my own hands. This enables me to speak with certainty as to the condition and locality in which they were met with. By the ingenuity of the late Mr. Nicol of Edinburgh, we were furnished with a beautiful method of slicing specimens of fossil-wood so as to examine their internal structure. The late Mr. Witham, assisted by Mr. Nicol, first applied this successfully, and his work on the internal structure of fossil vegetables was published in 1833. In describing his specimens, he notices one which he designated Anabathra pulcherrima. This did not do much more than afford evidence of the internal vascular cylinder arranged in radiating series, somewhat similar to that which had been found and described by Messrs. Lindley and Hutton as occurring in Stigmaria fcoides, in their third volume of the 4 Fossil Flora.’ In 1839 M. Adolphe Brongniart published his truly valuable memoir, “Observations sur la structure interieure du Sigillaria elegans comparee a celle des Lepidodendron et des Stigmaria et a celle des vegetaux vivants.” His specimen of Sigillaria elegans was in very perfect preservation, and showed its external characters and internal structure in every portion except the pith and a broad part of the plant intervening betwixt the internal and external radiating cylinders. Up to this time nothing had been seen at all to be compared to Brongni art’s specimen, and no savant could have been better mdccclxv. 5 K 580 ME. E. W. BINNEY ON SOME LOWER-COAL-SEAM FOSSIL PLANTS. selected to describe and illustrate it. His memoir will always be considered as one of the most valuable ever contributed on the fossil flora of the Carboniferous period. In 1849, August Joseph Corda published his ‘Beitrage zur Flora der Vorwelt,’ a work of great labour and research. Amongst his numerous specimens, he describes and illustrates one of Piploxylon cycadoideum, which, although not to be compared to Brongxiaet’s specimen, still affords us valuable information, confirming some of that author’s views rather than affording much more original information. All these last three specimens Brongniart, in his ‘Tableau de vegetaux fossiles consideres sous le point de vue de leur classification botanique et de leur distribution geologique,’ pub- lished in 1849, classes as Dicotyledones gymnospermes under the family of Sigil- larees; amongst other plants his Sigillaria elegans , Witham’s Anabathra , and Corda’s Piploxylon. In 1862 the writer published an account of specimens in the ‘ Quarterly Journal of the Geological Society’ of that year, which confirmed the views of the three learned authors above named as to Sigillaria and Piploxylon being allied plants ; he also showed that their supposed pith or central axis was not composed of cellular tissue, but of different sized vessels arranged without order, having their sides barred by transverse striae like the internal vascular cylinders of Sigillaria and Lepidodendron. These speci- mens were in very perfect preservation, and showed the external as well as the internal characters of the plants. All the above specimens were of comparatively small size, with the exception of that described by Corda, which, although it showed the external characters in a decorticated state, did not exhibit any outward cylinder of a plant allied to Sigillaria with large ribs and deep furrows so commonly met with in our coal-fields, but rather to plants allied to Sigillaria elegans and Lepidodendron. In the present communication it is intended to describe some specimens of larger size than those previously alluded to, and to endeavour to show that the Sigillaria vascu- laris gradually passes as it grows older into ribbed and furrowed Sigillaria , and that this singular plant not only possessed two woody cylinders, an internal one and an external one, both increasing on their outsides at the same time, but likewise had a central axis composed of hexagonal vessels, arranged without order, having all their sides marked with transverse striae. Evidence will also be adduced to show that Sigillaria dichoto- mized in its branches something like Lepidodendron, and that, as in the latter plant, a Lepidostrobus was its fructification. The outer cylinder in large Sigillaria was com- posed of thick-walled quadrangular tubes or utricles arranged in radiating series, and exhibiting every appearance of having been as hard-wooded a tree as Pinites, but as yet no disks or striae have been observed on the walls of the tubes. Stigmaria is now so generally considered to be the root of Sigillaria, that it is scarcely necessary to bring any further proof of this proposition ; but specimens will be described which will prove by similarity of structure that the former is the root of the latter. The chief specimens described in this memoir are eight in number, and were found ME. E. W. BINNEY ON SOME LO WEE-COAL-SEAM EOSSIL PLANTS. 581 by me in the lower divisions of the Lancashire and Yorkshire coal-measures imbedded in calcareous nodules occurring in seams of coal. Specimen No. 1, .from the first-named district, is from the same locality as the Trigo- nocarjjon, described by Dr. J. D. Hooker, F.R.S., and myself, in a memoir “ On the Structure of certain Limestone Nodules enclosed in seams of Bituminous Coal, with a Description of some Trigonocarpons contained therein” *, and the other seven specimens are from the same seam of coal in the lowercoal-measures as that in which the specimens described in a paper entitled “On some Fossil Plants, showing Structure, from the Lower Coal-measures of Lancashire ”f, were met with, but from a different locality. The position of the seams of coal in which the fossil-woods were found in the carbo- niferous series will be shown by the following sections of the lower coal-measures. In Lancashire. yds. ft. in. In Yorkshire. yds. ft. in. 1 1 0 Beeston or Silkstone seam . . 2 0 0 69 0 0 Strata 0 0 0 0 3 Eoyds or Black seam . 0 2 10 Strata 57 0 0 Strata . . 38 0 0 Seam 0 0 6 Better Bed seam . . 0 1 4 Strata 45 0 0 Strata . . 51 0 0 Upper flagstone (Upholland) 50 0 0 Upper Flagstone (Elland) . . 40 0 0 Strata 20 0 0 Strata . . 40 0 0 Seam (90 yards) 0 0 5 Seam (90 yards) . . 0 0 6 Strata 20 0 0 Strata .. 56 0 0 Seam (40 yards) 0 1 6 Seam (40 yards) . . 0 1 0 Strata 64 0 0 Strata .. 39 0 0 «*Upper Foot seam (Dog Hill) 0 1 2 Strata 15 0 0 ^Gannister seam 1 0 0 * -^Halifax Hard seam . . 0 2 3 Strata 13 0 0 Strata .. 14 0 0 Lower Foot seam (Qnarlton) 0 2 0 Middle seam . . 0 0 11 Strata 17 0 0 Strata .. 24 0 0 Bassy seam (New Mills) 0 2 6 Soft seam .. 0 1 6 Strata 40 0 0 Strata .. 56 0 0 Seam 0 0 10 Strata 10 0 0 Sand or Featheredge seam 0 2 0 Sand seam . , . 0 o 4 Eough Eock of Lancashire (Upper Millstone of Geological Survey) 20 0 0 Upper Millstone of Phillips (Halifax) . . . . 36 0 0 Strata (Eochdale or Lower Flags) 120 0 0 Strata (Lower Flagstone) 72 0 0 *Seam 0 0 6 Little seam . . 0 0 3 Strata 2 0 0 Seam 0 0 10 Strata 14 0 0 Seam 0 1 3 Upper Millstone of Lancashire. In the Lancashire coal-field all the seams of coal, from the forty yards downwards, have at places afforded the Amculojpecten and other marine shells in their roofs of black shale, and these latter strata generally contain calcareous nodules. The nodules in the seams of coal commonly known by the name of Bullions have chiefly been found in the beds marked #, ##, and ### in Lancashire, whilst in Yorkshire they have as yet been only observed in the Halifax Hard seam marked * Philosophical Transactions, 1855, p. 149. t Quarterly Journal of the Geological Society of London for May 1862, p. 106. 5 K 2 582 ME. E. W. BINNEY ON SOME LOWEE-COAL-SEAM EOSSIL PLANTS. Description of No. 1 Specimen. The first specimen intended to be described in this communication is from the thin seam of coal marked * in the lower coal-measures of Lancashire arranged in the vertical section previously given, and is from the same mine from which the specimens described by Dr. Hooker and myself were obtained. It was found associated with Calamodendron, Halonia, Sigillaria, Lepulodendron , Stigmaria, Trigonocarpon, Lycopodites, Lepidostrobus , Medullosa , and other genera of plants not yet determined in the order of relative abundance in which they have been just named. A portion of a similar specimen of fossil-wood obtained by me from the same locality, on analysis* gave Carbonate of lime . . .... 76-66 Carbonate of magnesia .... 12-87 Sesquioxide of iron .... 4-95 Sulphate of iron . . . . . . . 0-73 Carbonaceous matter . .... 4-95 The stratum lying immediately above the seam of coal in which the specimen occurred, generally termed the roof, was composed of black shale containing large calcareous nodules, and for a distance of about 2 feet 6 inches upwards was one entire mass of fossil shells of the genera Goniatites, Orthoceratites, Aviculopecten, and Posidonia. The beds in the vicinity of the coal occurred in the following order, namely, yds. ft. in. 1. Black shale with nodules containing fossil shells 0 2 6 2. Upper seam of coal enclosing the nodules full of fossil-wood .006 3. Fire-clay floor full of Stigmaria 020 4. Clay and rock 200 5. Lower seam of coal 0010 6. Fire-clay full of Stigmaria. The fossil-wood occurred in circular, lenticular, and elongated and flattened oval- shaped nodules, varying from an inch to a foot in diameter, the round and uncompressed specimens being in general small, whilst the flattened ones were nearly always of a large size. No fossil shells were met with in the nodules found in the coal itself, although, as previously stated, they were very abundant in the nodules found in the roof of the seam, which there rarely contained any remains of plants. The large nodules of 10 to 12 inches in diameter, when they occurred, swelled out the seam of coal both above and below as in the annexed woodcut, fig. 1. * Por this analysis I am indebted to the kindness of Mr. Hermann. Fig. 1. MR. E. W. BINNEY ON SOME LOWER-COAL-SEAM EOSSIL PLANTS. 583 Specimen No. 1 was originally, when first found, 6 inches in length by 7 in breadth, and of an oval form. Its exterior surface was not very well preserved, the outer bark coming off with the matrix of coal in which it was imbedded, but the inner bark showed an irregularly fluted surface marked with fine longitudinal striee. In Plate XXX. fig. 1, one half of the specimen is represented. The middle portion of the specimen in transverse section shows a central axis, marked a, having its inner portion, somewhat compressed, and composed of hexagonal-shaped vessels showing all their sides marked with transverse strise, arranged without order. Around this axis is a cylinder of hexagonal vessels, 5, arranged in radiating series of considerably less size than those of the central axis, but having all their sides similarly marked with transverse strife, and increasing in size as they extend from the centre to the circum- ference. On the outside of this radiating cylinder is a part of the specimen not show- ing much structure, but apparently having been once composed of coarse cellular tissue. Beyond this is another zone, for the most part now consisting of mineral matter, chiefly crystallized carbonate of lime, sometimes affording evidence of structure in the form of tubes or elongated utricles arranged in radiating series, and forming an outer cylinder in the plant. Figs. 2 & 3 show longitudinal and tangential sections of the natural size, taken from the lower and upper portions of fig. 1. Fig. 4 shows a part of the transverse section, magnified five diameters, where the com- mencement of the wredge-shaped masses are seen with convex ends adjoining the central axis, and parted by medullary rays or bundles extending from the centre to the circum- ference, and probably communicating with the leaves on the outside of the plant. Figs. 5 & 6 show longitudinal and tangential sections of a little more than one half of the specimen, magnified five diameters, the latter displaying the oval-shaped bundles of vessels traversing the internal cylinder of the plant from the centre to the circum ference. This specimen is evidently of the same genus as that described by Witham, and obtained by him from Allenbank in Berwickshire, from the mountain-limestone series, and named Andbathra pulcherrima , although in a much more perfect state of preserva- tion *. My specimen, however, does not show a pith of cellular tissue, it being rather imperfect in that part; but it distinctly confirms Witham’s opinion as to the occur- rence of medullary rays or bundles dividing the woody cylinder; and it appears to be nearly identical in structure with Diploxylon cycadoideum of Cord a f, with which it will be classed. This specimen is not in so perfect a state of preservation as those fossil-woods intended to he hereinafter described in this communication, especially as regards its central and external parts ; but it certainly differs from them in having a larger mass of scalariform * On the Internal Structure of Eossil Vegetables found in the Carboniferous and Oolitic Districts of Great Britain, by H. T. M. Witham, E.G.S. &c. Edinburgh, 1833. f Beitrage zur Flora der Vorwelt, Taf x. 584 MR. E. W. BINNEY ON SOME LOWER-COAL-SEAM EOSSIL PLANTS. tissue composing the central axis, and having the inner portions of the wedge-shaped bundles forming the internal radiating cylinder of a convex shape as they approach the central axis, somewhat like those represented by Brongniart in his SigiUaria elegans , and still more resembling those described by Corda in Diploxylon cycadoideum* ; but my specimen shows within those convex bundles a broad zone of scalariform tissue arranged without order and marked with transverse striae. It has been assumed, both by Corda and Brongniart, that Diploxylon had a pith composed of cellular tissue, surrounded by a medullary sheath of hexagonal vessels arranged without order, barred on all their sides with transverse striae. My specimen is evidently more complete in structure than those of the last-named authors, or even that which Witham himself described ; but although it shows the so-called medullary sheath in a very perfect state, there is nothing to indicate the former existence of a pith of cel- lular tissue. All the specimens examined by Witham, Corda, and Brongmart appear to have had their central axes removed altogether and replaced by mineral matter, or else only showing slight traces of their structure ; and these authors appear to have inferred the former existence of a pith of cellular tissue, rather than to have had any direct evidence of it in the specimens of Anabathra , Diploxylon, and SigiUaria respect- ively figured by them. Every collector of coal-plants is well aware of the blank space so generally left in the above fossil plants as well as in the roots Stigmariae. It is quite true that a little disarrangement of the scalariform vessels ( a ') in the specimen is seen ; but the part which remains undisturbed shows that the whole of the central axis was formerly composed of hexagonal vessels arranged without order, having all their sides marked with transverse striae and not of cellular tissue. This view is confirmed by another and more perfect specimen of Anabathra in my cabinet, and enables me to speak with positive certainty, and to show that these three plants had a similar struc- ture in the central axes to the specimens of SigiUaria vascularis described by me in my paper published in the Quarterly Journal of the Geological Society. My specimen clearly proves the existence of medullary rays or bundles traversing the internal woody cylinder, which originate on the outside of the central axis ; and it appears to me pretty certain that Corda’s specimen of Diploxylon cycadoideum , if tan- gential sections had been made and carefully examined, would have done the same. The exterior of the specimen is not in a very complete state of preservation, but it seems to have been covered by irregular ribs and furrows, with slight indications of remains of the cicatrices of leaf-scars. Its marked character, as previously alluded to, is the great space occupied by the central axis. This is of much larger size than in either the SigiUaria vascularis or the specimens intended to be next described. The lunette-shaped ends of the wedge-like bundles of the inner woody cylinder bear some resemblance to the form of the same parts of the SigiUaria elegans of Brongniart, but much more to those of Corda’s Diploxylon cycadoideum , with which it appears to be identical. * See M. Beongniakt’s paper on SigiUaria, previously quoted. ME. E. W. BINNEY ON SOME LOWEE-COAL-SEAM EOSSIL PLANTS. 585 The lunette-shaped extremities of the inner radiating cylinder of Diploxylo7i cycadoi- deum , as well as those in my specimen, remind us of a similar arrangement shown to occur in Stigmaria by Dr. Hooker, in plate 2. fig. 14*; and they appear to differ from those found in Sigillaria vascularis in not being divided from the central axis by a distinct line of demarcation, just as the same author’s Stigmaria fig. 5 differs from fig. 14. The exterior of the inner radiating cylinder of the former plant is more free and open, and not so sharp and compact as that of the latter plant. Indeed, from structure alone, it would appear probable that the first-named Stigmaria was the root of Diploxylon, whilst the last one was the root of Sigillaria vascularis. As Brongniart has preferred Corda’s name of Diploxylon to Anabatlira , and as the former is a more expressive generic term in my opinion, probably it is better to adopt it, and accordingly the specimen has been denominated Diploxylon cycadoideum. Description of Specimens Nos. 2, 3, 4, 5, 6, 7, & 8. The second specimen intended to be described in this memoir is from a small seam of coal about 2. feet in thickness in the lower coal-measures, marked ## in the vertical section previously given, and from the same seam that the specimens of Sigillaria vascularis , described by me in the paper published in the Quarterly Journal of the Geological Society previously quoted, came from, although from a different locality. This specimen, as well as those numbered respectively 3, 4, 5, 6, & 7, all came from the Halifax Hard seam, the Gannister coal, at South Owram near Halifax. It was found associated with Sigillaria , Stigmaria , Lepidodendron , Calamodendron, Ealonia , Diploxylon, Lepidostrobus, and Trigonocarpon, and other fossil plants not well determined in the order of relative abundance in which they have been just named. A portion of one of the specimens, a large Sigillaria , gave, on analysis f, Sulphates of potash and soda T62 Carbonate of lime 45*61 Carbonate of magnesia 26*91 Bisulphide of iron 1T65 Oxides of iron 13*578 Silica 0-23 Moisture 0*402 The stratum found lying immediately above the seam of coal in which the nodules occurred was composed of black shale containing large calcareous concretions, and for about 18 inches was one entire mass of fossil shells of the genera Aviculopecten , Gonia- tites , Orthoceratites, and Posidonia. * Memoirs of the Geological Survey of Great Britain, vol. ii. part 1. t Eor this analysis I am indebted to the kindness of Dr. E. Angus Smith, F.E.S., 'who had it done in his laboratory by Mr. Browning. 586 ME. E. W. BINNEY ON SOME LOWER-COAL-SEAM EOSSIL PLANTS. The beds occurred in the following (descending) order, namely, ft. in. 1. Black shale full of fossil shells and containing calcareous concretions 1 6 2. Halifax Hard seam with the nodules containing the fossil plants . 2 0 3. Floor of fire-clay and Gannister, full of Stigmaria jicoides . The fossil-wood is found in nodules dispersed throughout the coal, some being spherical and others elongated and flattened ovals, varying in size from the bulk of a common pea to 8 and 10 inches in diameter. In some portions of the seam of coal the nodules are so numerous as to render it utterly useless, and they will occur over a space of several acres, and then for the most part disappear and again occur as numerous as ever. For a distance of from twenty-five to thirty miles the nodules occur in this seam of coal in more or less abundance, but always containing the same plants. Fossil shells are rarely met with in the nodules found in the coal, but they occur abundantly in the large cal- careous concretions found in the roof of the mine, and are there associated with JDadoxy- lon containing Sternbergia-Yrihs, which plant has not yet been noticed in the coal, and Lepidostrobus. So far as my experience extends, the nodules in the coal are always found associated with the occurrence of fossil shells in the roof, and may probably be owing to the presence of mineral matter held in solution in water, and precipitated upon or aggregated around certain centres in the mass of the vegetable matter now forming coal before the bituminization of such vegetables took place. No doubt such nodules con- tain a fair sample of the plants of which the seams of coal in which they are found was formed, and their calcification was most probably chiefly due to the abundance of shells afterwards accumulated in the soft mud now forming the shale overlying the coal. The specimen illustrated in Plate XXXI. fig. 1, is of an irregular oval shape, 1 foot 3 inches in circumference, 7 inches across its major, and 3J inches across its minor axis. When first discovered it was 8 inches in length, and only a fragment of a much larger stem. The light-coloured disk in the middle, about an inch in diameter, shows the central axis and the internal radiating cylinder of woody tissue, while the indistinct radiating lines towards the circumference indicate the outer cylinder, formed of thick- walled tubes or utricles of quadrangular form arranged in wedge-shaped masses divided by coarse muriform tissue, increasing in the opposite direction as to their size that the wedge-shaped masses do : all of the natural size. Fig. 2 shows the outside appearance of the specimen marked with fine longitudinal striae, irregular ribs and furrows, and some cicatrices of leaf-scars, which would induce most collectors of coal-plants to class it with a decorticated specimen of Sigillaria. It most resembles Sigillaria organum. The bark of a portion of the specimen remains attached to it in the form of coal, that is united to the matrix of the seam in which the fossil was found imbedded. The reverse side of the specimen does not show the character so distinctly. Here we have a Stigmaria-like woody cylinder, with a central axis composed of barred ME. E. W. BINNEY ON SOME LOWEE-COAL-SEAM FOSSIL PLANTS. 587 vessels arranged without order, found in the inside of a stem of Sigillaria in such a position as it existed in the living plant. It is not a solitary instance, but one of more than fifty specimens exhibiting similar characters which have come under my observation. In Plate XXXII. fig. 1, is represented the light-coloured disk previously alluded to, and shown in Plate XXXI. of the natural size, but here magnified 5 diameters, exhi- biting the central axis composed of hexagonal vessels arranged without order, of several sizes, those in the middle being smaller and becoming larger towards the outside, where they come in contact with the internal radiating cylinder b , and then again diminishing in size. This latter was no doubt cylindrical, like the stem of the plant, but both parts in the process of petrification have been altered by pressure to their present forms. It consists of a broad cylinder ( b ) of about an inch in diameter, composed of parallel elon- gated tetragonal or hexagonal tubes of equal diameter throughout for the greater part of their length, obtuse and rounded at either extremity, and everywhere marked with crowded parallel lines which are free or anastomosing all over the surface. The tubes towards the axis are of the smallest diameter ; they gradually enlarge towards the circum- ference, where the largest are situated, though bundles of smaller tubes occasionally occur among the larger. This cylinder, which for convenience may be called the internal woody system of the plant, is divided into elongated wedge-shaped masses, pointed at their posterior or inner extremity, and parted by fine medullary rays of various breadths, some much narrower than the diameter of the tubes, others considerably broader, but none are conspicuous to the naked eye, except towards the outer circumference in some rare instances. Fig. 2 represents a transverse section of the central axis and the commencement of the internal radiating cylinder, magnified 12 diameters. The hexagonal vessels in the centre and at the circumference, where they come in contact with the internal radiating cylinder, are smaller in size than those seen in the other parts of the axis. The dark line across the axis, as well as the dark space in the centre, both seem to be the result of a disarrangement of the tubes during the process of mineralization, as similar appearances have not been observed in many other specimens examined by me, which in those parts are in a more perfect state of preservation. The dark and sharp line separating the vessels of the central axis from those of the internal radiating cylinder does not permit us to clearly see the origin of the medullary rays or bundles which undoubtedly traverse the latter. Fig. 3 represents a longitudinal section taken on the right-hand side of the specimen, and extending across the whole of the internal radiating cylinder through the central axis, the intermediate space between the internal radiating cylinder and the outer cylinder, and the external radiating cylinder to the outside of the stem, magnified 4 dia- meters : a a showing the smaller barred vessels of the central axis, having some ( a / a!) which appear to have been disarranged ; b b the internal radiating cylinder of larger barred vessels ; c the space occupied by lax cellular tissue traversed by bundles of vessels ; and d the external radiating cylinder, consisting of elongated tubes or utricles arranged mdccclxv. 5 L 588 ME. E. W. BINNEY ON SOME LOWEE-COAL-SEAM EOSSIL PLANTS. in radiating series diverging from certain circular openings, and divided by masses of muriform tissue which contain the medullary rays or bundles. Fig. 4 is a tangential section of the same parts of the specimen as lastly described, magnified 4 diameters ; V V showing the medullary rays or bundles traversing the inner radiating cylinder, and d' d' those traversing the outer radiating cylinder. Plate XXXIII. fig. 1 is a longitudinal section of a portion of the same specimen, exhibiting the central axis* and the inner radiating cylinder, magnified 15 diameters. Fig. 2 shows several of the vessels of the central axis as they would be if they were not ground away in the operations of slicing and polishing, magnified 45 times. Fig. 3 is a tangential section of the inner radiating cylinder, b showing the barred vessels, and b" the medullary rays or bundles, magnified 15 diameters. Figs. 4 & 5, longitudinal and tangential sections of the same specimens, showing the structure of the outer radiating cylinder, d denoting the tubes or elongated utricles of which it is composed, and d' the medullary rays or bundles which traverse it, magnified 10 diameters. Plate XXXIV. fig. 1 represents a transverse section of a ribbed and furrowed stem (No. 3), displaying similar cicatrices to that of No. 2 given in Plate XXXI., and having a like central axis, as well as like internal and external radiating cylinders and other parts, magnified 2 diameters. It is given for the purpose of more distinctly showing the tubes or elongated utricles, d , and the fusiform openings formed of very open muriform tissue, d' enclosing the medullary rays or bundles which traverse the external radiating cylinder. This it does in a very marked manner: magnified 20 diameters. In Plate XXXV. figs. 1, 2 & 3 (Nos. 4, 5 & 6), are shown the exteriors of three central axes separated from large ribbed and furrowed stems, in every respect similar to those described in Plate XXXI. and Plate XXXIV., and such as might easily be taken for small Calamites, magnified diameters. Fig. 4 (No. 7) shows the outside of the internal woody cylinder of a Stigmaria with ribbed and furrowed characters, resembling those shown on the outsides of the central axes lastly described, also magnified 2| diameters. The first three specimens, Nos. 4, 5 & 6, are from the Halifax Hard seam of coal at South Owram, but No. 7 is from the Wigan Five Feet Mine, a seam in the middle coal- measures. The tangential sections which show the medullary rays or bundles that traverse the inner and outer radiating cylinders, afford clear evidence of the different appearance of the bundles marked b " in Plate XXXIII. fig. 3, from those in Plate XXXIV. fig. 2 marked d'. Specimens Nos. 2 & 3 bear considerable resemblance to the Sigillaria elegans of Brongniart, with respect to their internal radiating cylinder and the medullary rays or bundles which traverse it, assuming that such vessels come from the outside of the central axis, and not from the exterior of the internal radiating cylinder, as that distin- * In the Plate the small tubes a' a" appear to be divided by septae. This is certainly the case in one slice, but in another of the same specimen these septae are not seen, but small barred vessels appear in their places, so the former may probably be due to the direction of the slice being cut along the dark line which traverses the central axis, as shown in Plate XXXII. figs. 1 & 2. ME. E. W. BINNEY ON SOME LOWEE-COAL-SEAM FOSSIL PLANTS. 589 guished savant supposed. Certainly there is no evidence in my specimens to support the latter view. A great many specimens have been broken up and destroyed for the purpose of examining the inner radiating cylinder, and in every case medullary rays or bundles were found traversing it, just as you find in the same part of Stigmaria. On the outside of the inner cylinder, at the extreme part of the zone of coarse and lax cellular tissue which bounds it, are some circular openings, from which spring the wedge- shaped masses of quadrangular, tubular, or elongated utricles which form the outer radiating cylinder. The lax cellular tissue has nearly always been displaced and dis- arranged in the process of mineralization, and sometimes the outer radiating cylinder and the circular orifices connected with it have been pushed towards the inner cylinder. This may have been the case in Brongniart’s specimen, and caused him to suppose that the medullary rays or bundles originated only on the outside, and were not joined to those which traversed the inner cylinder. So far as my large specimens show, there were medullary rays which had their origin next the central axis, passed through the inner cylinder, and after traversing the zone of lax cellular tissue outside the latter, apparently communicated with similar rays or bundles of vessels of much larger size, which are always found traversing the outer radiating cylinder, and then went on to the leaves on the outside of the stem. In Brongniart’s specimen the tubes or elongated utricles composing the outer radiating cylinder appear to have been far more delicate in structure than the thick- walled tubes in specimens Nos. 2 & 3*, but probably not more so than might be expected from the difference in size of the plants, my specimens being about twelve times as large as his, and in all probability so much older individuals. The tubes in mine might easily be mistaken for similar tubes in Pinites if their size and the thickness of their walls were merely considered, and no notice were taken of the discigerous characters of that genus. In my specimens no disks have as yet been observed on the walls of the tubes, nor have they afforded any evidence of the transverse striae which characterize the tubes of the central axis and internal radiating cylinder. It is possible that these markings may have once existed on the walls of the tubes, and been after- wards obliterated during the process of mineralization. The thick walls of the tubes in my specimens often exhibit circular dots of a yellow colour, bearing some resem- blance to coloured disks. The absence of the disks is the only reason for distinguishing the outer tissue in my specimens from the woody portion of Pinites , and this absence of disks is sometimes found to prevail on the walls of the tubes of small specimens of Dadoxylon , which are found with piths of Sternbergia inside them. The late Mr. J. E. Bowman, F.G.S., in his paper on the Fossil Trees discovered on the line of the Bolton Railway, near Manchester f, and which were in all probability old Sigillarice , at considerable length endeavoured to prove that they were hard-wooded solid timber trees, in opposition to the then common opinion that they were soft or * In the longitudinal section represented in the Plates these tubes are made more delicate than they appear in the specimens. f Transactions of the Manchester Geological Society, vol. i. p. 112. 5 l 2 590 ME. E. W. BINNEY ON SOME LOWEE-COAL-SEAM FOSSIL PLANTS. hollow stems. In my company that author first saw the trees, and he then observed to me that the roots of those fossil trees clearly indicated by their great size and strength that the trees when living had heavy tops. In all the numerous specimens of large Sigillaria which have come under my obser- vation, the outer radiating cylinder shows more or less evidence of lines of growth, and is generally divided into rectangular masses parted by straight lines of sparry matter, just as a piece of oak taken out of a peat bog and dried does at the present day. This similarity in divisional structure strongly supports the view of the late Mr. Bowman as to Sigillaria being a hard-wooded tree, which has lately been revived by Dr. Dawson, F.R.S., in his paper “ On the Vegetable Structures of Coal,” who says, “ I am even inclined to suspect that some of the described specimens of Conifers of the coal may be the woody axes of large Sigillaria?, or at least approaching quite as nearly to those plants as to modern Conifers”*. All the large specimens of fossil trees found in seams of coal give evidence of having been subject to considerable pressure when in a soft state, and this might also cause the divisional lines above alluded to, without resorting to a process like that which takes place in drying bog oak. In the specimens Nos. 2 & 3 the outer radiating cylinders are nearly an inch and a half in breadth of thick-walled tubes, or elongated utricles arranged in radiating series, and diverging from a circular opening, while in Brongniart’s Sigillaria elegans the outer radiating cylinder was not more than -j^th of that breadth. Probably my specimens may not prove to be of the same species as that of the celebrated Autun specimen, still they may be of the same genus, although of considerably greater age. But they have the greatest resemblance to the Sigillaria vascularis described by me in a paper read before the Geological Society, and printed in its Journalf. All the speci- mens described in that communication, as well as those in the present one, were obtained by me from the same seam of coal, but at different places, still the two, namely, the large ribbed and furrowed specimens and the small rhomboidal scarred stems, are always found associated together, and they can be traced gradually passing from one into the other. These facts, when taken in connexion with the similarity of structure in the central axis, the internal radiating cylinder, the space filled with lax cellular tissue between the latter and the outer radiating cylinder diverging from circular openings, clearly prove that the smaller specimen is but the young branch of the older stem, No. 2. It is true that the earlier authors who have written on these plants, would scarcely have admitted a ribbed and furrowed Sigillaria to have been so intimately connected with a rhomboidal scarred plant, but it is now generally allowed that such differences in external characters would afford no grounds for ignoring the structural similarity of the specimens. Undoubtedly the small Sigillaria vascularis was part of a branching stem ; for in my cabinet there is a specimen clearly showing two internal radiating cylinders just at the point where the branches dichotomized, as shown in woodcut (fig. 2), so often met with in Lepidodendron. * Quarterly Journal of the Geological Society, vol. xv. p. 636. f Quarterly Journal of the Geological Society for May 1862. ME. E. W. BINNEY ON SOME LOWEE-COAL-SEAM EOSSIL PLANTS. 591 Whatever evidence Dr. Dawson had for supposing a large Fig. 2. Sigillaria to have been possessed of the obtuse top and the flat main roots, as shown in his restored specimen, figured in vol. xv. of the ‘ Quarterly Journal of the Geological Society,’ it is impossible to say, but certainly in all the numerous specimens which have come under my observation nothing has occurred to warrant me in supposing Sigillaria to be such a plant. Everything has led me to believe that the leaves and branches, and probably the fructification of Sigillaria, would prove to be very analogous to those of Lepidodendron. In order to show the identity in structure of specimens 2 & 3 with Sigillaria vascu- laris, previously described by me*, in Plate XXXV. fig. 5 is a specimen of Sigillaria vascularis from the same pit and seam of coal as the larger specimen No. 2, showing a transverse section, and fig. 6 exhibiting the external characters of the plant, part being covered with its bark, and part being decorticated, magnified 4 diameters. On comparing this specimen with those figured in Plates XXXI., XXXII., XXXIII., and XXXIV., the greatest difference is seen in the external characters of the stems ; but, as before stated, these can be traced from a regular rhomboidal scar, like that of the Lepidodendron, to the irregularly ribbed and furrowed Sigillaria. When we examine their internal structure it is found that their central axes are alike. The internal radiating cylinders are the same in both, making allowance for the greater age of the large specimen, each having been undoubtedly exogenous. The space on the outside of the inner radiating cylinder, filled with lax tissue and traversed by medullary bundles, is well marked and defined in the smaller specimen, much more so than in the larger one ; but neither show the nature and position of these bundles, which will be noticed more at large in a specimen from a different locality hereinafter described. The outer boundary of this space in the small specimen is marked by a well-defined line of carbon- aceous matter. The coarse cellular tissue on the outside of the latter, with the circular openings from which proceed the bundles of vessels traversing the outer zone of tubes or elongated utricles in radiating series, forming the outer cylinder, are the same in both. The term tubes, or elongated utricles, has been previously employed to denote the structure of the outer cylinder. The inner portion of this zone is made up of what appears to be coarse cellular tissue. This gradually elongates as it proceeds outwards into utricles, which in their turn pass into tubes of a quadrangular form, of which Fig. 3. the outer part of the cylinder is composed. The accompanying woodcut (fig. 3) represents a lon- gitudinal section of No. 8, described in Plate XXXV. figs. 5 & 6. From this it is seen that the elongated utricles are more prominent and numerous in the small specimens, whilst in the large specimens, like those in Plates XXXIII. & XXXIV., the tubes are chiefly seen. * Quarterly Journal of tlie Geological Society for May 1862, p. 106. 592 ME. E. W. BINNEY ON SOME LOWER-COAL-SEAM FOSSIL PLANTS. The outer cylinder seems to surround the band of lax cellular tissue enveloping the inner cylinder, and appears something in the nature of a pith to it. The inner cylinder no doubt increased on its outside by encroaching on the zone of lax cellular tissue, as may be proved by comparing a young with an old specimen, No. 8 with No. 2. This outer zone of pseudo-wood increased externally like the inner cylinder, as is evident on comparing the younger with the older plant, the walls of the tubes of the latter being stronger, as might be expected to be the case ; and in both we have the singular phenomenon of a tree increasing externally in two different zones at the same time. As to the internal radiating cylinders described as occurring in the Diploxylon and Sigillaria , given in this communication, they are evidently like two different Stigmaria- cylinders, which afford no structure in their central axes, exactly resembling those figured by Dr. Hooker in his paper on Stigmaria jicoides printed in the ‘ Memoirs of the Geological Survey of Great Britain’*, in plate 2. figs. 14 & 5. In the latter we have the wedge-form masses of wood of a lunette shape running into the central axis, whilst in the former we have them separated by a sharp and well-defined line from the central axis. The identity of structure between Sigillaria and Diploxylon and these two Stigmarice is further proved by some specimens which have lately come under my notice. After the researches of Dr. Lindley, Professor Goeppert, Mr. Prestwich, Dr. Hooker and others, it really seemed that we had obtained almost a complete knowledge of the internal structure of Stigmaria. It is true that only Goeppert had seen the isolated bundles in the pith ; all the specimens of the other observers having been imperfect in that portion of the plant, and not giving indication of structure there f. In my own researches it has rarely fallen to my lot to meet with a Stigmaria showing any structure in the central axis, even where the small stems of Sigillaria vascularis , affording all the structure in that part, are in great abundance. Many years since, after an examination of a great number of specimens of Stigmaria in my collection, it occurred to me that an outer radiating cylinder would ultimately be discovered. In my remarks on Stigmaria % is the following passage: — “That part of Stigmaria which intervened between the vascular axis and the bark appears to have consisted of two different kinds of cellular tissue. These, in most cases, have been unfortunately destroyed, so that we cannot positively know their true nature ; but they appear to be of different characters, for there generally appears to be a well-marked division. This is often shown in specimens composed of clay ironstone which have not been flattened, and the boundary line is generally about a quarter of an inch from the outside of the specimen. Most probably the outer part of the zone has been composed of stronger tissue than the inner one, as is the case with well-preserved specimens of * Memoirs of the Geological Survey of Great Britain, vol. ii. part 1. t I liave written to Professor Goeppert for the purpose of obtaining further information as to the pith of this specimen, but I have not been successful in my endeavour. £ Quarterly Journal of the Geological Society, vol. iv. part 1. p. 20. ME. E. W. BINNEY ON SOME LOWER-COAL-SEAM EOSSIL PLANTS. 593 Lepidodendron.” It is singular that Drs. Lindley and Hooker, as well as such acute observers as Brongniart and Goeppert, had not noticed this line of division, but it was no doubt owing to the imperfect specimens which they had examined. After the discovery of the outer radiating cylinder by Witham in Lepidodendron , and the same arrangement in Sigillaria by Brongniart, it was to be expected that such outer radia- ting cylinder would be found to occur in Stigmaria , if it were the root of Sigillaria. After an inspection of a great number of specimens, the cabinet of Mr. Bussell, of Chapel Hall, Airdrie, has afforded me four or five distinct specimens which give clear evidence of the existence of this outer radiating cylinder in Stigmaria. They are all in clay ironstone, and have not been much compressed. He has kindly allowed me to slice two of the specimens, which afford decisive evidence of the former existence of both an inner and an outer radiating cylinder. The space on the outside of the inner cylinder does not distinctly show the bundles of vessels communicating with the root- lets, although there is some evidence of their former occurrence. The bell-shaped orifices from which the rootlets spring are well displayed, and the space between them is occupied by wedge-shaped masses of tubes or elongated utricles arranged in radiating series, and not to be distinguished in any way from those shown in Plate XXXY. fig. 5. Indeed the transverse section of the specimen there figured would almost do for a representation of the Stigmaria if the latter had the central axis preserved, which it unfortunately has not. There is the same internal radiating cylinder, the same space occupied by lax cellular tissue, which gradually passes into tubes or elongated utricles arranged in radiating series, apparently diverging from circular openings, and parted by large bundles of muriform tissue containing vessels barred on all their sides, extending to the outer bark. The accompanying woodcut (fig. 4) will give a much better idea of its structure than any laboured description. Fig. 4. This specimen clearly proves, by the evidence of internal structure alone, that Stig- maria is the root of Sigillaria , each of them having an inner radiating cylinder com- 594 ME. E. W. BINNEY ON SOME LOWER-COAL-SEAM EOSSIL PLANTS. posed of barred vessels, a space occupied by lax cellular tissue, and an outer radiating cylinder composed of tubes or elongated utricles. The broad space intervening between the internal and external radiating cylinders, filled with lax cellular tissue and traversed by medullary bundles communicating with the leaves on the outside of the stem, as shown in the specimens described in this paper, is the only part on which information is required to complete our knowledge of the structure of the stem of Sigillaria. Fortunately a small specimen of Sigillaria vascu- laris, kindly presented to me by Mr. Ward, of Longton, a most indefatigable collector, has enabled me to obtain considerable information on this point. This specimen shows the rhomboidal scars on the outside of the stem, the two radiating cylinders and the space between occupied by lax cellular tissue, and traversed by medullary bundles. The specimen in this woodcut (fig. 5, magnified twice) is of smaller Eig. 5. size than any previously described by me, but it is, from both its internal structure and external characters, a small Sigillaria vascu- laris in its young state, when the two radiating cylinders, especially the outer one of the plant, were only slightly developed. The medullary bundles are seen on the outside of the inner radiating cylinder, and pass, inclining upwards at a small angle, from the inner cylinder to nearly the outside of the stem. No trace of the outer cylinder can be seen, so as to enable us to see whether the smaller- sized medullary bundles coming from the inner cylinder join the larger ones in the outer cylinder, described in Plate XXXI Y. fig. 2, and there marked d'. All the tangential sections show the medul- lary bundles, both in large and small specimens, to be much greater and stronger in the outer than in the inner radiating cylinder ; but no evidence has yet been found of the junction of these medullary bundles to prove that the former run into the latter, or whether the two are distinct. They consist of hexagonal tubes, barred on all their sides, surrounded by muriform tissue, that on the outside of the specimen being of very coarse texture. Up to this time we possess little information as to the organs of fructification belong- ing to Sigillaria. In a paper many years since printed by me *, some Stigmarice were described which were found with their insides full of spores, resembling those which were found by Dr. Hooker in Lepidodendron. Similar spores are met with in great abundance in all the seams of splint coal which have been examined by me, the floors of which, it is well known, are one mass of Stigmarice. In the strata lying around the large Sigillaria found at Dixon Fold, described by the late Mr. J. E. Bowman^, that author says, “ they (the trees) lie in a stratum of soft shale about four feet thick, among which great quantities of nodules containing cones of Lepidostrobus, with pieces of Stig- marice, &c., were found.” * Quarterly Journal of the Geological Society, vol. vi. p. 17. t Transactions of the Manchester Geological Society, vol. i. p. 113. ME. E. W. BINNEY ON SOME LO WEE-COAL-SEAM FOSSIL PLANTS. 595 Goldenberg gives a description and figures of a cone and spores which he considers to be the fructification of Sigillaria *. That author, however, does not give any further evidence of the connexion of the supposed organs of fructification with the stem of Sigillaria than had been known in England for years, as previously mentioned. The spores he figures as belonging to Sigillaria are exactly the same as those found by me in the inside of Stigmaria. A specimen found in the roof of the same seam of coal in which Nos. 2, 3 & 8 were met with, but at a different place, was given to me by Mr. W. Butterworth, junior, of Moorside, near Oldham, and enables me to give evidence, equally strong with that adduced by Dr. Hooker to prove that Lepidostrobus was the fruit of Lepidodendron , to show that a Lepidostrobus was the fruit of Sigillaria. Dr. Hooker, in his excellent paper on this subject f, says, “The doctrine of morphology teaches us that the cone is nothing more than the leafy apex of a branch whose leaves are modified in form, generally to the end that they shall perform the office of protecting organs to repro- ductive bodies ; this is the case of the pine cone, that of the Lycopodium , or Club Moss, and many other plants.” This specimen is shown in the annexed woodcut (fig. 6), of its natural size, and exhibits sporangia, like those described by Dr. Hooker in his memoir previously quoted, arranged around the axis of the cone, which does not afford the rhomboidal scars characteristic of the Lepidodendron, but presents ribs and furrows, with scars, arranged in quincuncial order, like a small specimen of Sigillaria organum. Certainly, if the axis of continuation of a branch of Lepidodendron , the axis of this cone is equally entitled to be classed as the branch of a Sigillaria. The organs of fructification, which have been called by geolo- gists fossil cones, and have been classed under the genus Lepido- strobus, may not only have belonged to Lepidodendron and Sigil- laria, but it appears nearly certain in my mind that some of them also belonged to Cala- mites. In a paper published many years since, the apparent connexion of Calamitcs and Sigillarice was discussed and noticed by the author Since that time he has collected much further evidence on the structure of Calamites, which he proposes at some future time to communicate to the Society in a separate memoir. In all the large specimens of Sigillaria vascularis the outer radiating cylinder has been considerably disarranged by pressure, the original cylindrical form of the plant having been changed into that of an elongated oval. This has been more especially the case with that part of the plant composed of lax and coarse cellular tissue, forming the * Flora Saraepontana fossilis. Die flora der Yorwelt Saarbriickens, von Fa. Goldenbekg, l]tcs Heft, Tafel x. figs. 1 & 2. t Memoirs of the Geological Survey of Great Britain, vol. ii. part 2. p. 452. + Philosophical Magazine for November 1847, p. 259. MDCCCLXV. 5 M 596 ME. E. W. BINNEY ON SOME LOWEE-COAL-SEAM EOSSIL PLANTS. inner portion of the outer cylinder, as well as the thick tubes or elongated utricles, arranged in radiating series, composing the outer part next the bark. Nevertheless in the former there is nearly always some evidence left of circular openings or eyes sur- rounded by coarse cellular tissue, which gradually assumes a radiating character, and from which the wedge-shaped bundles of tubes or elongated utricles proceed and extend to the outside of the stem. The character of these circular openings, and the wedge- shaped bundles proceeding from them, is well shown in the young specimen of Sigillaria vascularis , drawn in Plate XXXI II. fig. 5, and remind us much of what is seen in Cala- modendron, except that in the latter plant the walls of the tubes exhibit oval openings, sometimes approaching the form of disks, characters which have not as yet, so far as my knowledge extends, been observed in the outer cylinder of Sigillaria. In larger and older specimens, as previously stated, the walls of these tubes or elongated utricles of a quadrangular form have become much thicker, and cannot be distinguished from those of Pinites, except by the absence of disks. The outer cylinder, as before noticed, in large specimens always presents divisional lines of a rectangular form, filled by spathose matter, in shape very like those now seen in hard-wooded trees. These appear to me as if made by pressure, but they may have been formed in the process of drying, before the mineralization of the specimen, as previously stated ; however, it is still my opinion that these lines originate from pressure rather than desiccation, as there is little evidence yet published of the subaerial decay of the vegetable matter now forming coal, while, on the contrary, nearly every seam of cannel-coal affords abundance of fish remains, and no doubt seams of soft bright coal, if equally favourable for their preservation, would yield them. My cabinet contains specimens from the Oldham coal-field of soft bright coal containing undoubted scales of Rhizodus, given to me by Mr. Wild, of Glodwick, and doubtless many more such specimens will be found if carefully looked for. In the outer portion there is always some appearance of concentric rings, no,t unlike those seen in our present hard- wooded trees, and which my friend Mr. J. S. Dawes, F.G.S., first noticed in Calamodendron *. This observation of Mr. Dawes many spe- cimens in my cabinet amply confirm, although they do not bear out that author’s statement as to Calamodendron having had a pith composed of cellular tissue, as it undoubtedly possessed a central axis composed of large vessels apparently barred on all their sides by transverse strise, and not to be distinguished from the same part of S. vascularis. Concluding Remarks. In this memoir the reader will no doubt have seen that it was intended to be more of a descriptive character than an attempt to trace the analogy of the plants whose remains have formed our beds of coal with living vegetables. The subject is surrounded with difficulties, and although the author has been singularly fortunate in meeting with specimens in a good state of preservation, when compared with most hitherto described, * Quarterly Journal of the Geological Society, vol. vii. p. 198. ME. E. W BINNEY ON SOME LOWEE-COAL-SEAM EOSSIL PLANTS. 597 still his information is confined to two plants. These, no doubt, have contributed by their remains in a great measure to form the two seams of coal in which they were found, as is evident from the abundance of Sigillaria-roots now found in floors of the beds. In addition to this fact, the Halifax Hard or Gannister seam yields the Sigillaria vascularis as by far the most common plant found in it. The large specimens Nos. 2 & 3, now described and figured, some persons may doubt as being the older forms of the Sigillaria vascularis described by me some years since in the Geological Society’s Journal previously quoted, as well as the medium-sized specimen No. 8 given in Plate XXXV. fig. 5 of this memoir; but the one has been traced gradually passing into the other so as to leave no doubt on this point, and the internal structure is unquestionably the same both in the large and small plants, after making due allowance for the greater age of the former. The general opinion of botanists and geologists, that Sigillaria was a hollow and succulent plant, no doubt arose from the flat specimens generally found compressed into thin plates in indurated clays or shales. The same view was taken with regard to Calamites , owing to their being nearly always found in a similar condition ; but it is now well known that many specimens of Calamites are nothing more than the casts of the central axis of a hard-wooded tree with concentric rings, the whole of which has in most cases disappeared and left no trace of its former existence. Now, although till the discovery of my specimens few, if any, large Sigillaria had been found exhibiting structure, it has been shown that the late Mr. Bowman, an eminent botanist, many years since pronounced the Dixon Fold fossil trees to be large Sigillarice and hard- wooded dicotyledonous trees with heavy tops, and this he inferred chiefly from the size and form of their roots. Long after the last-named author’s death, Dr. Dawson, in 1859, as previously quoted, was inclined “ to suspect that some of the described species of conifers of the coal may be the woody axes of large Sigillarice , or at least of trees approaching quite as nearly to those plants as to modern conifers.” Although my specimens do not altogether support Dr. Dawson's views as to the woody axis he no doubt refers to, namely, the internal radiating cylinder and not the outward one, which he terms a very thick cellular inner bark, his opinion is entitled to considerable weight as to Sigillarice being hard-wooded trees, he having paid great attention to the different structures found in the charcoal now met with in our coals, the floors of which so constantly testify to the presence of Sigillaria in the form of roots, and the great part it contributed to their formation. The size of the external cylinder of this plant, when compared with its internal one, is so much greater, that by far the larger portion of the coal must have been derived from the former. It is this part of the fossil tree that so generally divides into rectangular masses, and not the small internal cylinder evidently alluded to by Dr. Dawson, as any person who has examined many large specimens will well know. Specimen No. 2 probably may not be considered as so marked an example of the genus Sigillaria , owing to the small size and indistinctness of the cicatrices left by the 5 m 2 598 MR. E. W. BINNEY ON SOME LOWER-COAL-SEAM EOSSIL PLANTS. leaves, which are not so well shown in the Plate as they are generally found on speci- mens of Sigillaria organum. No doubt it cannot be regarded as a good example of the species organum , but from the ribs, furrows, and scars on its outside no one will question its being a Sigillaria , even if its internal structure did not prove its relationship to Sigillaria elegans. In all my investigations as to the origin of coal, the marine character of the water in which the plants that formed it by their decomposition grew, becomes to my mind more evident. It is now well known to all parties conversant with coal-mining, that in most deep mines where the surface water cannot get down the water found in the coal is quite salt, and contains iodine, bromine, and the usual constituents of sea-water. Any person carefully examining each of the seams of coal in which the fossil woods described in this memoir were found, placed as they are upon an under clay full of Sigillaria- roots with their radicles traversing it in every direction, will be convinced that the plants which formed the coal grew on the spot where it is now met with, and were not drifted there, while the presence of such a mass of marine shells as is found in the roof of each seam evidently where they lived and died, equally proves the salt nature of the water. Little evidence is to be obtained of the character of the dry land of the Carboniferous epoch except what is afforded by a few sun cracks on some of the rocks, but from the shallow seas more resembling marine swamps than the oceans of the present day, it was probably little above the surface of the water. Shallow seas and low lands would of course greatly influence the climate of the period. The strata found in the vicinity of seams of coal, with some few exceptions, show that they were deposited from water during periods of great tranquillity, and the vast range over the old and new worlds of the genus Sigillaria found in all their true coal-fields, indicates a uniformity of condi- tions of which we have now no parallel, and areas of such immense extent as is only equalled by some of our present oceans. In the Lancashire coal-field, probably one of the best developed in Great Britain, from the bottom to the top there are about 120 different seams of coal, great and small. These indicate 120 periods of rest or repose of the earth’s crust, when a primeval forest reared its top above the waters until the vegetable matter now forming each bed of coal was grown and deposited*. Then such forest was submerged and buried under mud and sand now found as shale and sandstone rocks. The hollow caused by such subsi- dence was silted up until it was again covered by shallow water. Then, again, a fresh crop of vegetation flourished so as to form another bed of coal. For 120 different times did this successive growth of vegetable matter, submergence and silting up go on. In some instances whole forests oi Sigillaria, standing upright in fine shale, on the top of the seams of coal are met with, thus clearly showing that they were submerged quietly and slowly, whilst at other times the prostrate stems now found lying in sandstone roofs * Although upright Sigillarice are generally found in the roof of a seam of coal, they are also met with in fine- grained shales, midway between seams, less frequently in coal floors, and more rarely still in the seams of coal themselves. — Transactions of the Manchester Literary and Philosophical Society, vol. viii. 2nd series, p. 176. ME. E. W. BINNEY ON SOME LOWEK-COAL-SEAM FOSSIL PLANTS. 599 show that the submergence was rapid, causing strong currents that tore up and drifted the trees. Every one of the floors of these coal-seams is full of the roots of Sigillaria ; so with the stems of these trees in the roof, the vegetable matter in the seam of coal, and the roots in the floor, there can scarcely be a doubt as to the remains of the vege- tables now composing coal having grown on the spots where it is now found, and that Stigmaria was the characteristic root of the plants which for the most part produced coal. The above conditions of the growth of vegetables in shallow seas very different to any state of things now existing, would require a plant suited to them and very different from any now living. After a careful investigation of the structure of Sigillaria elegans , Brongniart came to this conclusion : “ Tous ces motifs doivent nous porter a conclure que les Sigillaria et les Stigmaria constituaient une famille speciale entierement detruite, appartenant probablement a la grande division des Dicotyledones gymnospermes, mais dont nous ne connaissons encore ni les feuilles ni les fruits.” If we take particular parts of Sigillaria vascularis , as before described, we can trace resemblances to some living plants. The central axis when taken by itself might appear to connect the plant with ferns, as it certainly bears some resemblance to the root of Aspidium exaltatum, as figured by Brongniart in plate 8, figs. 10 & 11*. The internal radiating cylinder is somewhat like similar cylinders in Echinocactus and Melocactus , as figured by the same author. The vessels with barred and dotted sides in some respects resemble those of Zamia integrifolia , also noticed by Brongniart, and the outer radiating cylinder in the thick- ness of the walls of its tubes, or elongated utricles, and their arrangement, points to conifers. Although Sigillaria has resemblance in some of its parts to such widely different living plants, there can scarcely be a doubt in the mind of any one who has had the advantage of examining the fossil plant with its far extending roots and long radicles, but that it had an aquatic habitat. It attained a large size, as upright speci- mens have been traced by me nearly 60 feet in height without showing much dimi- nution in size, and the bases of others have come under my observation which have measured over 7 feet in diameter. Description of the Plates. PLATE XXX. IHploxylm cycadoideum. Fig. 1. Specimen (No. 1) of one-half of a stem of Diploxylon cycadoideum in a calcified state, found in the lower coal-measures of Lancashire, in the middle of a seam of coal, showing a transverse section : natural size. * Observations sur la structure interieure du Sigillaria elegans, p. 447. 600 MR. E. W. BINNEY ON SOME LOWER-COAL-SEAM EOSSIL PLANTS. Fig. 2. A longitudinal section of the same specimen taken across the minor axis from d to d in fig. 1 : natural size. Fig. 3. A tangential section of the same specimen taken across the upper part : natural size. Note. — The same letters indicate the same parts in this and the preceding figures, and also in the subsequent ones. a a. The middle part, showing the central axis or pith composed of large hexagonal vessels, having all their sides barred by transverse striae. a ' a'. The smaller hexagonal vessels in the central axis or pith found some- times interspersed amongst the larger ones, and divided by horizontal septae. a!’ a!'. Small vessels of very delicate elongated tissue found mixed with the other vessels in the axis or pith. b b. The vascular internal cylinder, in wedge-shaped bundles and radiating series, composed of hexagonal vessels, barred on all their sides by trans- verse striae, and divided by medullary rays or bundles, b" b". V V . Portions of the same cylinder disarranged or destroyed. b" b”. Medullary rays or bundles passing through the internal cylinder, and extending to the outside of the stem. c c. Space on the outside of the internal cylinder, composed of lax cellular tissue, and traversed by vascular bundles frequently disarranged or destroyed and replaced by mineral matter. d d. Outer cylinder of tubes or elongated utricles in wedge-shaped bundles, and radiating series of quadrangular form, divided by wide openings filled with coarse muriform tissue, which enclose medullary rays or bundles of an oval or circular form leading to the leaves. d1 d'. Medullary rays or bundles of barred vessels traversing the coarse muriform tissue. d’1 d". Elongated tissue divided by horizontal septae (muriform tissue) sur- rounding the medullary rays or bundles. Fig. 4. A transverse section of a portion of the same specimen taken across the minor axis, showing the whole of the central axis or pith, one side of the inner radiating cylinder, and the space between the latter and the outside of the stem : magnified 5 diameters. Fig. 5. A longitudinal section of the same specimen, showing the same parts of the stem as are named in the last figure, magnified 5 diameters. Fig. 6. A tangential section of the same specimen (upper part), magnified 5 diameters, MR. E. W. BINNEY ON SOME LOWER-COAL-SEAM EOSSIL PLANTS. 601 PLATE XXXI. Sigillaria vascularis. Fig. 1 (No. 2). Specimen of a stem of Sigillaria vascularis in a calcified state, found in the lower coal-measures of the West Hiding of the County of York, at North Owram near Halifax, in the middle of the Hard bed of coal, showing a front view of the upper part, containing the central axis, internal vascular cylinder, space on the outside of the latter composed of coarse cellular tissue, and external radiating cylinder : natural size. Fig. 2. Side view of the same specimen, which not only shows the upper part of the specimen like fig. 1, with the central axis, internal radiating cylinder, inter- vening space of lax cellular tissue, and external radiating cylinder, but a side view of the decorticated portion of the stem with irregular ribs and furrows, on the former of which are traces of the cicatrices left by the leaves of the plant : natural size. PLATE XXXII. Sigillaria vascularis. Fig. 1 shows a transverse section of the central axis and internal radiating cylinder of the same specimen, magnified 5 diameters. Fig. 2. A part of the same specimen, a denoting the central axis, and b the internal radiating cylinder: magnified 12 diameters. Fig. 3. A longitudinal section of the same specimen, commencing on the outside of the internal radiating cylinder passing through the central axis, the other portion of the internal radiating cylinder, the part composed of coarse cellular tissue generally disarranged adjoining to it, and the external radiating cylinder to the outside of the specimen : magnified 4 diameters. a a. Parts of the central axis composed of hexagonal vessels arranged with- out order, having all their sides marked by transverse striae. b b Parts of the internal cylinder, composed of hexagonal vessels in wedge- shaped bundles, and radiating series marked on all their sides by transverse striae parted by medullary rays or vascular bundles communicating from the outside of the central axis to the exterior of the cylinder, and probably extending on to the leaves. cc. Parts of the coarse cellular tissue, generally a good deal disarranged, traversed by large vascular bundles, most probably connected with the medul- lary rays or vascular bundles of the internal cylinder, and communicating with the leaves. 602 ME. E. W. BINNEY ON SOME LOWER-COAL-SEAM FOSSIL PLANTS. d d. Parts of the external cylinder, composed of tubes or elongated utricles of a quadrangular form arranged in radiating series, and parted by large vascular bundles surrounded by coarse muriform tissue. Fig. 4. A tangential section of a portion of the same specimen, magnified 4 diameters. b. Parts of the internal cylinder, showing a section of the medullary rays or vascular bundles, b”. c. Portions of the coarse cellular tissue, generally a good deal disarranged, traversed by large vascular bundles, most probably connected with the medul- lary rays or vascular bundles of the internal cylinder, and communicating with the leaves. d d. Parts of the external cylinder, composed of tubes or elongated utricles of a quadrangular form arranged in radiating series, and parted by large vas- cular bundles surrounded by coarse muriform tissue. Fig. 4. A tangential section of a portion of the same specimen, magnified 4 diameters. b b. Parts of the internal cylinder, showing a section of the medullary rays or vascular bundles, b". c c. Parts of the coarse cellular tissue somewhat disarranged, but showing some structure, and traversed by vascular bundles. d d. Parts of the external radiating cylinder, showing the large oval bundles of vascular tissue (d1) surrounded by coarse muriform tissue. PLATE XXXIII. Sigillaria vascularis. Fig. 1 shows a longitudinal section of a portion of the same specimen, exhibiting the central axis composed of barred vessels, a «, parted by smaller vessels divided by horizontal septse, a!, as well as portions of the internal cylinder composed of barred vessels, b b : magnified 15 diameters. Fig. 2 represents two of the barred vessels of the central axis as they would appear if not ground away in the slicing and polishing, magnified 45 times. Fig. 3. A tangential section of a portion of the same specimen across a part of the in- ternal cylinder, showing the medullary rays or bundles (b") traversing the cylinder b : magnified 15 diameters. Fig. 4. A longitudinal section of a portion of the external cylinder d, composed of tubes or elongated utricles arranged in radiating series, magnified 10 diameters. Fig. 5. A tangential section of a portion of the external cylinder, showing the large vascular bundles of an oval shape, d ', surrounded by coarse muriform tissue which traverse it : magnified 10 diameters. ME. E. W. BINNEY ON SOME LOWEK-COAL-SEAM FOSSIL PLANTS. 603 PLATE XXXIV. Sigillaria vascularis. Fig. 1. Specimen (No. 3) of a stem of Sigillaria vascularis in a calcified state, found also in the lower coal-measures of North Owram in the middle of the Hard bed of coal, in company with the last specimen described, showing a portion of the central axis divided and partly disarranged, portions of the internal cylinder composed of hexagonal vessels having all them sides marked with transverse striae, arranged in radiating series parted by medullary rays or vascular bundles ; also a part of the space on the outside of the internal cylinder, composed of coarse cellular tissue, and parts of the external cylinder, composed of tubes or elongated utricles arranged in radiating series, and parted by large vascular bundles surrounded by coarse muriform tissue communicating with the leaves. The outside of the specimen presented the same kind of ribs and furrows, with indistinct traces of cicatrices, as the specimen No. 2, described in Plates XXXI., XXXII., and XXXIII. It is given chiefly for the purpose of showing the tubes or elongated utricles of the external cylinder, traversed by the large vascular bundles of an oval form, surrounded by coarse muriform tissue which are much more distinctly represented than in the first-named spe- cimen No. 2 : magnified 2 diameters. Fig. 2. A tangential section of the same specimen, showing a portion of the outer cylinder, composed of tubes or elongated utricles, d d, traversed by large vascular bundles of the shape of a double cone, composed of very large horizontally-divided tissue, d1, and more finely divided tissue, d" d", and having an oval-shaped vas- cular bundle in the middle, most probably communicating with the cicatrices to which the leaves were attached on the outside of the plant : magnified 20 diameters. Fig. 3. A longitudinal section of the same specimen, showing a portion of the outer cylinder, composed of tubes or elongated utricles, d, arranged in radiating series, as well as a portion of a vascular bundle with the fine tissue divided by hori- zontal partitions, d" : magnified 20 diameters. PLATE XXXV. Sigillaria vascularis. Figs. 1, 2, & 3 (Nos. 4, 5, & 6) represent the external appearance of the central axes of three different specimens of Sigillaria vascularis , found in the middle of the Hard seam of coal in company with the specimens Nos. 2 & 3 described in Plates XXXI., XXXII., XXXIII., and XXXIV. They were enclosed in three stems, exactly resembling those specimens in external characters and mdccclxv. 5 N 604 ME. E. W. BINNEY ON SOME LOWEE-COAL-SEAM FOSSIL PLANTS. internal structure in every respect. The horizontal division, in fig. 1 may pro- bably owe its origin to a fissure in the stone rather than a division such as is usually seen in a Calamites, hut the outside longitudinal striae in all the spe- cimens remind us of that fossil plant, while the vascular bundles of the central axis of these specimens' bear considerable resemblance to some of the species of Medullosa: magnified 2\ diameters Fig. 4 (No. 7) represents the outside of the inner radiating cylinder of Stigmaria ficoi&es arranged in wedge-shaped bundles, showing the finely marked longi- tudinal striae with which it was furnished, but not affording any evidence of structure in the central axis : magnified 2\ diameters. This specimen is from the Wigan Five Feet seam of coal of the Ince Hall Coal and Cannel Company, in the middle division of the Lancashire coal-measures, and is the only speci- men which has come under my notice which shows the outside of the inner radiating cylinder : magnified 24 diameters. Fig. 5 (No. 8) represents a transverse section of a small specimen oi Sigillaria vascu- laris, found also in the lower coal-measures of North Owram, in the middle of the Hard bed of coal. It is in a more perfect condition, as a whole, than any of the other specimens described in this paper, and appears to be a younger individual of the same genus and species as the larger and more imperfect ones, Nos. 2 & 3, figured in Plates XXXI., XXXII., XXXIII., and XXXIV., associated with which it was found. It shows the central axis, composed of hexagonal vessels arranged without order, and having all their sides marked with horizontal striae, the internal cylinder of hexagonal vessels arranged in radiating series, and having all their sides marked with transverse striae and parted by medullary rays or vascular bundles, the space outside that cylinder occupied by lax cellular tissue traversed by vascular bundles, sections of some of which are seen as circular openings, a dark line bounding it, the zone of coarse cellular tissue outside that last named containing circular and oval openings, and passing into tubes or elongated utricles arranged in radiating series, and divided by large medullary rays or vascular bundles, forming the ex- ternal cylinder, and an outer bark enveloping the plant : magnified 4 diameters. Fig. 6 (No. 8) represents the outside view of the same specimen partly covered by a thick carbonaceous coating, probably representing the outer bark and partly decorticated, displaying rhomboidal scars, having a rib running through their major axis, in the middle of which is a cicatrix of a circular form left by the leaf. The scars and cicatrices upon them were arranged in quincuncial order. The specimen appears to be older than those described by me in the Geo- logical Journal previously alluded to, and younger than specimens 2 & 3 of this paper : magnified 2\ diameters. Phil. Tran^. MDCCCLXV. Pb.IXX. Plai&A.l. 3. J. N.Titdh.,deL.eb lith. Vincent Brooks, Imp Phil. Trans. MI) CCCLXV. PI. XXXI. PlaUA.il. J. N .Fitch., del. et Isth. Phzl. Trans. MD CCCLXV: PIXXXIL |^T:Tiwb,ariL.et Ji£h PM. Trans. MDCCCLXV. PI. I. Plate. A. V. J. N. Fitch, del.eb lith "Vincent Bro oks , Imp . Phil . Trans. MB CCCLXV. Film J . N Hitch, del.et jith . [ 605 ] XII. The Bakerian Lecture. — On a Method of Meteorological Registration of the Chemical Action of Total Daylight*. By Henry Enfield Roscoe, B.A., F.B.S. , Professor of Chemistry in Owens College , Manchester. Received November 8, — Read December 22, 1864. In the last memoir on Photochemical Measurements, presented to the Royal Society f, Professor Bunsen and I described a method for determining, by simple observations, the varying amount of chemical action effected by the direct and diffuse sunlight on photo- graphic paper, founded upon a law discovered by us, viz. that equal products of the intensity of the light into the times of insolation correspond within very wide limits to equal shades of tints produced on chloride-of-silver paper of uniform sensitiveness — so that light of the intensity 50, acting for the time 1, produces the same blackening effect as light of the intensity 1 acting for the time 50. For the purpose of exposing this paper to light for a known but very short length of time, a pendulum photometer was con- structed ; and by means of this instrument a strip of paper is so exposed that the different times of insolation for all points along the length of the strip can be calculated to within small fractions of a second, when the duration and amplitude of vibration of the pen- dulum are known. The strip of sensitive paper insolated during the oscillation of the pendulum exhibits throughout its length a regularly diminishing shade from dark to white ; and by reference to a Table, the time needed to produce any one of these shades can be ascertained. The unit of photo-chemical intensity is assumed to be that of the light which produces upon the standard paper in the unit of time (one second) a given but arbitrary degree of shade termed the normal tint. The reciprocals of the times during which the points on the strip have to be exposed in order to attain the normal tint, give the intensities of the acting light expressed in terms of the above unit. According to this method the chemical action of the total daylight (*. e. the direct sunlight and the reflected light from the whole heavens) has been determined, by means of observations made at frequent intervals throughout the day, and curves representing the variation of daily chemical intensity at Manchester have been drawn The labour of obtaining a regular series of such daily measurements of the chemical action of day- light according to this method is, however, very considerable ; the apparatus required * It is to be carefully borne in mind that no absolute measurement of the more refrangible solar rays falling on the earth’s surface is possible, except by the expression of their heat-producing effect ; and that all methods of measuring the intensity of these rays depending upon the action which they produce on any single chemical compound, give results which are only true for the particular rays affecting the compound selected as the standard of comparison. t Philosophical Transactions, 1863, p. 139. + Ibid. 1863, p. 160. MDCCCLXV. 4 0 606 PROFESSOR ROSCOE ON A METHOD OF METEOROLOGICAL is bulky, the observations can only be made in calm weather, and the quantity of sensi- tive paper needed for a day’s observations is large. The aim of the following communication is to describe a very simple mode of deter- mining at any moment the chemical action of the whole direct and diffuse sunlight (as measured by chloride-of-silver paper) adapted to the purpose of regular meteorological registration, and founded upon the principles laid down in the memoir above alluded to. According to this method a regular series of daily observations can without difficulty be kept up at frequent intervals. The whole apparatus needed for exposure can be packed into very small space ; the observations can be carried on without regard to wind or weather; and no less than forty-five separate determinations can be made upon 36 square centimetres of sensitive paper. Strips of the standard chloride-of-silver paper tinted in the pendulum photometer remain as the basis of the more simple mode of measurement now to be described. Two strips of this paper are exposed as usual in the pendulum photometer ; one of these strips is fixed in hyposulphite-of-sodium solution, washed, dried, and pasted upon a board furnished with a millimetre-scale. This fixed strip is now graduated in terms of the unfixed pendulum strip by reading off, with the light of a soda-flame, the position of those points on each strip which possess equal degrees of tint, the position of the normal tint upon the unfixed strip being ascertained for the purpose of the graduation. The fixed strip thus becomes in every respect equivalent to the unfixed strip. Upon this comparison with the unfixed pendulum strip depends the subsequent use of the fixed strip. In order to understand how the chemical action of daylight can be measured by help of this fixed and graduated strip, let us suppose, in the first place, that we have ascertained the position of those points upon the fixed strip which possess an equal degree of tint to points on the unfixed strip situated at regular intervals, say 10 millims. from each other. By reference to Table I. of the above-mentioned memoir, given below, we then find the relation between the times of exposure necessary to effect the tints in question when the intensity of the light remains constant. Let us suppose, in the second place, that the position on the unfixed strip of which the shade corresponds to that of the normal tint has been found ; and that the time of exposure, placed opposite to this position in Table I., has been noticed. If, now, the various tints on the strip had been produced in one and the same time by lights of different intensities, instead of being effected by light of the same intensity acting for different times, the law above alluded to shows that the numbers found in the Table would represent the relation of these different intensities ; so that in order to express this relation in terms of the unit of intensity employed, it is only necessary to multiply the numbers thus obtained by a constant, viz. the reciprocal of the number found in column II. of the Table, opposite to the position in column I., giving the point on the unfixed strip equal in shade to the normal tint. An example may serve to make this calculation plain : (1) The position on the unfixed strip equal in shade to the normal tint was found to be 112 millims. ; (2) the positions on the fixed strip equal in REGISTBATION OF THE CHEMICAL ACTION OF TOTAL DAYLIGHT. 607 Table I. I. Millims. II. Seconds. I. Millims. II. Seconds. I. Millims. n. 1 Seconds. I. Millims. II. Seconds. I. Millims. II. Seconds. I. Millims. II. Seconds. 0 1-200 32 1-003 64 0-846 96 0-700 128 0-549 160 0-369 1 M93 33 0-998 65 0-841 97 0-695 129 0-544 161 0-363 0 1-186 34 0-993 66 0-837 98 0-691 130 0-539 162 0-357 3 1-179 35 0-988 67 0-832 99 0-686 131 0-534 163 0-350 4 1*1 72 36 0-983 68 0-828 100 0-682 132 0-528 164 0-343 5 1-165 37 0-977 69 0-823 101 0-677 133 0-523 165 0-336 6 1-158 38 0-972 70 0-819 102 0-672 134 0-518 166 0-329 7 1-151 39 0-967 71 0-814 103 0*668 135 0-513 167 0-321 8 1-144 40 0-962 72 0-809 104 0-663 136 0-508 168 0-314 9 1-137 41 0-957 73 0-805 105 0-659 137 0*502 169 0-309 10 1-131 42 0-952 74 0-800 106 0-654 138 0-497 170 0-300 11 1-125 43 0-947 75 0-796 107 0-650 139 0-492 171 0-291 12 1-119 44 0-942 76 0-791 108 0-645 140 0-487 172 0-283 13 1-113 45 0-937 77 0-786 109 0-640 141 0-482 173 0-274 14 1-106 46 0-932 78 0-782 110 0-635 142 0-476 174 0-266 15 1-100 47 0-927 79 0-777 111 0*631 143 0-470 175 0-257 16 1-094 48 0-922 80 0-773 112 0-626 144 0-465 176 0-249 17 1-087 49 0-917 81 0-768 113 0-621 145 0-459 177 0-240 18 1-081 50 0-912 82 0-764 114 0-617 146 0-453 178 0-229 19 1-076 51 0-907 83 0-759 | 115 0-612 147 0-448 179 0-219 20 1-070 1 52 0-903 84 0-755 116 0-607 148 0-442 180 0-208 ! 21 1-064 53 0-898 85 0*750 117 0-603 149 0-436 181 0-198 j 22 1-058 54 0-893 86 0-745 118 0-598 150 0-431 182 0-187 23 1-053 55 0-888 87 0-741 119 0-593 151 0-425 183 0-176 I 24 1-047 j 56 . 0-884 88 0-736 120 0-588 152 0-419 184 0-161 25 1-041 57 0-879 89 0-732 121 0-583 153 0-413 185 0-146 26 1-036 58 0-874 90 0-727 122 0-578 154 0-407 186 0-131 27 1-030 59 0-870 91 0-723 123 0-573 155 0-401 187 0-116 28 1-025 I 60 0-865 92 0-718 124 0-568 156 0-394 29 1-019 61 0-860 93 0-714 125 0-563 157 0-388 30 1-014 62 0-856 94 0-709 126 0-558 158 0-382 31 1-009 63 0-851 1 95 0-704 1 127 0-553 159 0-376 tint to two points on the unfixed strip situated 10 millims. on each side of this, were found to be 100 millims. and 123 millims; (3) by reference to the Table, the relation between the intensities on these two positions is found to be as 0672 to 0578; (4) these numbers, multiplied by qt the reciprocal of the intensity corresponding to 112 millims., give the intensities expressed in terms of the unit formerly employed, which acting for one second produce the tints in question. The method of observation thus becomes very simple. To each of the fixed and graduated strips an Intensity Table is attached, giving the value of the tints upon each millimetre of its length in terms of the described unit ; a piece of standard sensitive paper is exposed for a known number of seconds to the light which it is required to measure, until a tint is attained equal to some one of the tints upon the strip ; the exact position upon the strip of equality of tint to the exposed paper is next read off by the light of the soda-flame ; the number found in the Intensity Table opposite to this position, divided by the time of exposure in seconds, gives the intensity of the acting light in terms of the required unit. A detailed description of the apparatus employed, and of the methods of preparing and graduating the strips, will be given under separate headings. 4 o 2 608 PROFESSOR ROSCOE ON A METHOD OF METEOROLOGICAL The following conditions must be fulfilled in order that this method can be adopted as a reliable measurement of the chemical action of light : — 1st. The tint of the standard strips fixed in hyposulphite must remain perfectly unalterable during a considerable length of time. 2nd. The tints upon these fixed strips must shade regularly into each other, so as to render possible an accurate comparison with, and graduation in terms of, the unfixed pendulum strips. 3rd. Simultaneous measurements made with different strips thus graduated must show close agreement amongst themselves, and they must give the same results as determinations made by means of the pendulum photometer, according to the method described on pages 158, 159 of the last memoir. I. Preparation of the Standard fixed Strips. For the purpose of preparing the fixed strips, sheets of good white photographic paper are salted in a solution containing 3 per cent, of chloride of sodium, exactly according to the directions given in the last memoir (p. 155) for the preparation of the standard paper. The salted paper after drying is cut into pieces, 16 centimetres in length by 15 centimetres in breadth, and silvered on a bath containing 12 parts of nitrate of silver to 100 parts of water. After drying, one of these papers is fixed at the corners upon a board covered by a well-fitting lid of sheet zinc, so made that it does not touch the paper ; the paper is then blackened by exposure to the action of light in the pendulum apparatus. For this purpose, the thin elastic sheet of the blackened mica usually employed, is replaced by a piece of thin sheet zinc 16 centimetres broad. The frame carrying the paper is clamped on to the horizontal plate of pendulum photo- meter, and the sheet of blackened zinc placed over it ; the cover is then withdrawn, and the paper exposed by allowing the pendulum, with the sheet of zinc attached to it, to vibrate until the required tint has been attained. The cover is then replaced, the frame opened in the dark room, the paper washed to remove excess of nitrate of silver, fixed in a saturated solution of hyposulphite of sodium, and well washed for three days. As the tints of the foxy-red colour which the paper possesses after fixing can be accu- rately compared with the bluish-grey tint of the freshly-exposed paper by means of the monochromatic light of the soda-flame, the use of a toning-bath was specially avoided as likely to render the paper liable to fade. Each sheet thus prepared is cut into four strips, 160millims. long and 30 millims. broad, which are then preserved for graduation. In order to ascertain whether these fixed strips undergo any alteration in tint by exposure to light, or when preserved in the dark, two consecutive strips were cut off from several different sheets, and the point on each at which the shade was equal to that of the standard tint (see last memoir, p. 157) was determined by reading off with the light of the soda-flame, by means of the arrangements fully described on p. 143 of the above-cited memoir. One-half of these strips were carefully preserved in the dark, the other half exposed to direct and diffuse sunlight for periods varying from fourteen days to six months, and the position of equality of tint with the standard tint from time to REGISTRATION OE THE CHEMICAL ACTION OF TOTAL DAYLIGHT. 609 time determined. It appears, from a large number of such comparisons, a few of which only are given below, that in almost all cases an irregular, and in some instances a rapid fading takes place immediately after the strips have been prepared, and that this fading continues for about six to eight weeks from the date of the preparation. It is, however, seen that, after this length of time has elapsed, neither exposure to sunlight nor preser- vation in the dark produces the slightest change of tint, and that, for many months from this time forward, the tint of the strips may be considered as perfectly unalterable. (1) Experiments showing the alteration of tint ensuing immediately after preparation. Each number given below represents the intensity (see Table II., p. 159 of the last memoir) corresponding to the mean of ten independent readings on each strip upon the under-mentioned days. Sheet No. 1, prepared December 9, 1863, Intensity. 1st Reading, Dec. 16, 1863. Intensity. 2nd Reading, Jan. 7, 1864. Diminution in three weeks. Strip A, exposed to sunlight... 2*49 2-05 0*44 Strip B, preserved in the dark 2-49 2*01 0-48 Sheet No. 2, prepared December 9, 1863. Strip A, exposed to sunlight... 2-21 1-86 0-35 Strip B, kept in the dark 2-21 2-03 0-18 From these numbers it is seen that the fading which occurs immediately after pre- paration is not dependent upon exposure, a change of the same kind being observed in those strips which were protected from the action of light. (2) Experiments showing the permanency of tint after lapse of some time from date of preparation. Sheet No. 3, prepared September 21, 1863. Intensity. Intensity. Intensity. Intensity. 1st Reading, 2nd Reading, 3rd Reading, 4th Reading, Dec. 10, 1863. Dec. 18, 1863. Jan. 11, 1864. Feb. 4, 1864. Strip A, exposed to sunlight... 1*40 1-40 1-38 1-36 Strip B, kept in the dark 1-38 1-37 1*39 1-35 Sheet No. 4, prepared September 21, 1863. Strip A, exposed to sunlight... 1*45 D39 1-39 1-38 Strip B, kept in the dark 1-43 1-43 | 1-45 1-46 610 PROFESSOR ROSCOE ON A METHOD OF METEOROLOGICAL (3) Experiments showing alteration and subsequent permanency of Tint. Sheet No. 5, prepared March 10, 1864. Intensity. Intensity. Intensity. Intensity. Intensity. Intensity. 1st Reading, 2nd Reading, 3rd Reading, 4th Reading, 5th Reading, 6th Reading, Mar. 12, 1864. Mar. 21, 1864. Apr. 27, 1864. May 11, 1864. June 3, 1864. July 18, 1864. Strip A, exposed to sunlight... 2-08 213 1*93 1-99 2-03 1*89 Strip B, in the dark 2-10 2-13 1*93 1-93 1*89 1-89 Sheet No. 6, prepared March 10, 1864. Strip A, exposed to sunlight... 2-23 2*23 2-13 2-15 2-15 2-10 Strip B, kept in the dark 2-23 2*23 1-99 2-01 2-08 1-97 Sheet No. 7, prepared March 10 CO 3 Strip A, exposed to sunlight... 2-35 2-42 2-08 2-18 2-13 2-01 Strip B, kept in the dark 2-35 2*54 2-01 2-03 2-08 2-03 The above numbers show that, after the standard fixed strips have been prepared for about two months, the tints remain constant both when the paper is exposed to light and when it is kept in the dark. The small differences seen in some instances arise from unavoidable experimental errors of various kinds. II. Graduation of the fixed Strips in terms of the Standard Pendulum Strips. The value of the proposed method of measurement entirely depends upon the possi- bility of accurately determining the intensities of the various shades of the fixed strips in terms of the known intensities of the standard strips prepared in the pendulum pho- tometer. Two modes of effecting this graduation, and of comparing the accuracy of the gra- duation of one strip with that of another, were employed. The first of these methods consists in determining by direct comparison the points on the fixed strip having equal intensities to points on the pendulum strip. For this purpose the position of the standard tint upon the pendulum strip was first observed ; circular pieces of this strip, situated 20 millims. apart, were then stamped out with a punch 5 millims. in diameter, and half of each circle pasted on to the wooden reading block (fig. 4 of the last memoir), so that the centre of the paper circle came into the centre of the hole. The readings were conducted in the way described on p. 159 of the last memoir, every comparison being made independently ten times by each of two observers, and the mean reading taken as the result, whilst several pendulum strips were used for the graduation of one fixed strip. The following may serve as an example of the first method of graduation. Four pendulum strips were employed for the graduation of the fixed strip A. KEGISTKATION OF THE CHEMICAL ACTION OF TOTAL DAYLIGHT. 611 Graduation of fixed strip A. Position of standard tint upon pendulum strip No. 1 = 85 millims., from which the constant zr~ -z is found in Table I. p. 607. 0*750 A The position 20 mm. on pendulum strip =1*427 intensity, and corresponds to 67*4 mm. on fixed strip. 40 , 1-283 „ 79-8 „ 60 , 1-154 „ 83-0 „ 80 „ 1-031 „ 91-6 „ 100 0-910 „ 94-5 „ 120 0-784 „ 119-8 „ 140 0-650 „ 121-6 „ In like manner the constants for three other pendulum strips were determined. Constant for pendulum strip No. 2=0.^-- Constant for pendulum strip No. 3=^^-* Constant for pendulum strip No. 4=Q.^Q-- By comparison of each of these three pendulum strips with the fixed strip the follow- ing numbers were obtained. Column I. gives the readings on the millimetre-scale of the fixed strip ; Column II. the corresponding intensities calculated as in the foregoing example. Wo. 2. No. 3. No. 4. I. II. I. II. I. II. 26-0 2-12 49-9 1-76 34-6 2-10 35-3 1-90 60 0 1-59 40-4 1-89 55-5 1-69' 70-5 1-43 53-4 1-70 72-6 1-47 81-5 1-27 64-8 1-52 80-1 1-25 92-4 M2 82-5 1-16 90-5 1 00 103-0 0-97 93-0 0-96 121-4 0-80 123-6 0-72 131-5 0-61 In order to obtain the mean result of these numbers, the curve for each of the four graduations was drawn, the abscissae giving the positions on the fixed strip in millimetres, and the ordinates the intensities corresponding to these positions. A curve was then interpolated, lying as nearly as possible between the points determining the single obser- vations, and from this mean curve the intensity for each millimetre on the scale was calculated. The following are these tabular values for every 10 millims. Column I. gives the position in millims. on the fixed strip, Column II. the corresponding intensity, and Column III. the mean tabular error. 612 PROFESSOR ROSCOE ON A METHOD OF METEOROLOGICAL I. II. III. I. II. HI. 20 2-30 0-10 70 1-47 0-022 30 2*10 0*09 80 1-28 0-010 40 1-90 0-02 90 1-07 0-045 50 1*76 0-016 100 0-916 0-053 60 1-62 0-013 110 0-830 0-056 120 0-755 0-050 A comparison of the several curves of the graduation of strip A found in Plate XXVIII. fig. 1 shows that the determinations agree as well as can be expected from such photo- metric experiments ; the mean tabular error between the positions 40 and 80 millims. on the strip not exceeding one per cent, of the measured intensity. For the second method of graduation sheets of paper tinted by lithography of a brownish colour and of different shades are employed, and a portion of each sheet is cut out, so that the several tints differ considerably from each other, and correspond to the tints taken at definite intervals along the fixed strip. These are then gummed over half the reading block, and the value of each read off on several pendulum strips, the inten- sity of which had previously been determined by the normal tint. Having thus obtained the intensity of each of the fixed tints, the fixed strip is graduated in terms of the pen- dulum strip by determining the points on the former equal in intensity to the fixed tints. This method possesses several advantages over that just described, and is to be preferred to it, although the comparison is an indirect one, as the intensity of the fixed tints can be found with a great degree of accuracy by repeated measurements ; and when their intensities a.re once determined they can be preserved for a length of time, as they do not undergo any change of shade, and therefore can serve for the graduation of a large number of fixed strips ; the preparation of which is accordingly not dependent, as is the case in the first method, upon the state of the weather. The following numbers may serve as an example of this method : (1) Determination of the intensity of fixed tints upon pendulum strips. No. 1. No. 2. No. 3. No. 4. No. 5. No. 6. No. 7. No. 8. No. 9. No. 10. j No. 11. No. 12. Reading of normal tint on pendulum 1 strip J Reading on pendulum strip of fixed 1 tint No. I. J „ No. II. „ No. III. „ No. IV. „ No. V. 153-2 mm. 82-0 mm. 131-1 mm. 136-6 mm. 1057 mm. 17-5 mm. 121-6 19-2 mm. 51-9 mm. 131-6 mm. 119-4 mm. 98-0 40-3 90-4 115-7 297 1087 50 50-2 91 0 159-5 67-2 1007 25-4 661 50-5 125-8 990 s’i-2 120-6 93-0 1500 157 50-1 24-5 52-3 89-3 145-5 22-6 517 134-0 The intensities for each determination of a fixed tint are obtained from the above numbers by dividing the numbers found in Column II. of Table I. (p. 607) opposite the millimetre readings of each fixed tint by those found in the same Table opposite to the readings of the normal tint. REGISTRATION OF THE CHEMICAL ACTION OF TOTAL DAYLIGHT. G13 Intensity of Fixed Tints. Fixed Tint. Expt. 1. Expt. 2. Expt. 3. Expt. 4. Expt. 5. Expt. 6. Expt. 7. Expt. 8. Expt. 9. Expt. 10.! Expt. 11. Expt. 12. I. 2-336 2185 2067 1-768 n. 1-767 1-709 1-647 1-585 1-689 1-524 1-548 hi. 1-480 1-328 1-356 1-346 1-276 1-182 1-289 1-235 1-317 IV. V. 0-840 0-698 0-891 0-515 0-838 0-544 0-794 0-473 0-773 0-755 Mean Intensity. Fixed Tint No. 1 2-089 Fixed Tint No. IV 0-798 „ II 1-637 „ V 0-512 „ III 1-312 (2) Graduation of fixed strips B and C, by means of the fixed tints. The graduation of the fixed strips by means of the fixed tints is now made in the way described in the first method. Headings on fixed strip B. Headings on fixed strip C. Corresponding intensity. millims. millims. millims. Fixed tint I. 20-2 27*7 2-089 „ II 3-88 42-8 1-637 „ III 67-3 71-7 1-312 „ IV 105-1 100-6 0-798 „ V 129-0 122-6 0-512 Standard tint 96-0 97-5 1-000 The Intensity Tables for these two strips are obtained by careful graphical interpola- tion from the above numbers ; the curves are given (in black) on Plate XXVIII. fig. 2, the abscissae representing the position on the millimetre-scale of the strips, and the ordinates the corresponding intensities. In every case the normal tint (intensity =1-00) is read off on the fixed strip, serving as a control of the accuracy of the graduation. A second series of intensity determinations of the same fixed tints with pendulum strips is appended for the purpose of controlling the accuracy of the first series. The intensities of the fixed tints thus obtained are given in the 3rd column of the following Table. A new fixed tint, No. III. A, was introduced of a shade between Nos. III. and IV. This new tint was found to coincide with the positions 82-1 millims. and 82-3 millims. on the strips B and C respectively. The readings of the remaining tints are the same as in the first series. (3) Second graduation of Strips B and C. I. II. m. Headings on strip B. Headings on strip C. Corresponding intensity. Fixed tint I 20-2 27-7 1-935 „ II 38-8 42-8 1-597 „ III 67-3 71-7 1-291 „ III A.... 82-1 82-3 1-123 „ IV 105-1 100-6 0-807 „ V 129-0 122-6 0-547 Standard tint 96-0 97-5 1-000 4 p MDCCCLXV. 614 PROFESSOR ROSCOE ON A METHOD OF METEOROLOGICAL The Intensity Tables for strips B and C obtained by graphical interpolation from both the above determinations, are those used in most of the observations of daily chemical intensity about to be described. The curves of these two last graduations are given (dotted lines) on Plate XXVIII. fig. 2 ; and from these curves the close agreement of the graduations is seen. The fixed strip graduated according to the above method is gummed upon the brass drum (M) of the reading-apparatus, fig. 6, care being taken to place a thick sheet of white paper between the metal and the fixed strip. In this position it is ready for use. III. Method of Exposure and Heading. For the purpose of making the observations, standard sensitive paper is prepared, according to the directions given on p. 155 of the last memoir, by salting photographic paper in a 3 per cent, solution of chloride of sodium, and subsequently silvering on a bath containing 12 parts of nitrate of silver to 100 of water. After drying in the dark, the paper is cut into pieces 100 millims. long by 10 millims. wide, and each piece gummed upon the back of an insolation-band (fig. 4) in the position denoted by the dotted lines, so Fig. 4. that the lower half of each of the nine holes (5 millims. in diameter) stamped out of the paper 10 millims. apart, is filled up with the sensitive preparation. These insolation- bands may be easily cut out of white cartridge paper by means of an iron ruler 400 millims. long and 35 millims. broad, the holes in the paper being stamped out by a punch fitting into nine corresponding holes in the ruler. The holes in the paper are numbered, and the numbers are repeated upon the band at a distance of 87 millims. from each hole for the purpose of subsequent adjustment. The insolation-apparatus (fig. 3) consists of a thin metal slide (A) 174 millims. in length and 40 millims. wide, with space enough between the sides to allow the paper band (B) to pass through easily. A circular opening (C) 10 millims. in diameter is cut in the middle of the upper side of the slide, and the marks on the bands are so arranged that the line marked No. 1 coincides with one end of the slide when the centre of the hole No. 1 in the band coincides with the centre of the opening (C) in the slide. A thin slip of brass (E) moves easily over the slide, and when brought into the position shown by the dotted lines, effectually protects the sensitive paper from the action of the light. If the slide (A) be used alone, the cover (E) can be moved by means of a button placed at the back of the slide ; it is, however, more convenient to place the slide upon the stand (G), to which a lever handle (F) is attached, fitting into the button for the purpose of enabling the observer to cover and uncover the opening with greater ease and exactitude than is practicable when the hand alone is used. When the intensity of the light is such that REGISTRATION OF THE CHEMICAL ACTION OF TOTAL DAYLIGHT. 615 the time of insolation does not exceed 2 or 3 seconds, the error introduced by this opening and closing may become considerable ; for the purpose of diminishing this error by increasing the duration of exposure, the intensity of the acting light is decreased by a known amount by allowing the circular disk of blackened metal (fig. 5), out of which two segments, each of -^-th of the whole area, have been cut, to revolve rapidly close above the upper surface of the slide (A) ; the spindle of the disk, for this purpose, fitting into the socket (S, fig. 3) on the stand. As the rate of rotation of the disk does not affect the accuracy of the result, it is made to revolve by turning the spindle with the hand. In order that the insolation-band carrying the sensitive paper may be made to press close against the lower edge of the opening (C), a piece of cartridge paper is placed underneath it, having several thicknesses of paper pasted at the part underlying the opening, whilst the ends of the same are made fast at the back of the slide. To enable the operator to observe when the paper has been sufficiently exposed, a small piece of photographically-tinted fixed paper of the requisite degree of shade is gummed upon the surface of the permanent paper band so as to lie directly under the opening (C). When one observation has been made and the time and duration of the insolation noted, the remaining papers can be similarly exposed at any required time, by successively bringing them under the central opening (C), the right adjustment being ensured by making the corresponding mark coincide with the end of the slide. When all the nine papers upon the band have thus been exposed, it can be withdrawn and a second band prepared, as the first can be substituted without the necessity of bringing the apparatus into a dark room. This is done by means of a small black silk bag or sleeve, open at both ends ; one end can be closed round the end of the brass slide by an elastic band, and the other is left open to admit the hand. When it is required to withdraw an inso- lation-band from the slide, the end of the paper is drawn out into the bag and the band rolled up into a small coil, and thus preserved until it can be read off, whilst the new 4 p 2 616 PEOFESSOE EOSCOE ON A METHOD OF METEOEOLOGICAL band is introduced into the bag in the form of a coil, then unwound and pushed into the slide. The reading-instrument is represented by fig. 6. It consists essentially of a metallic drum 80 millims. in diameter and 37 millims. broad, upon which a piece of thick white cartridge paper, and over it the graduated strip, is fastened. The edge of the drum is furnished with a millimetre-scale, and the dark end of the strip is made to coincide with the com- mencement of the scale. The drum turns upon a horizontal fixed axis against a vertical circular plate (N), being held in position by the screw (O). The drum and vertical plate are fixed upon a pillar and foot (P). The insolation-band is held against the graduated strip by means of two spring clamps (QQ'), placed apart at a distance of 130 millims. and fixed to the vertical plate (N). By moving the drum on its horizontal axis, the various shades of the fixed strip can be made to pass and repass each of the holes on the insola- tion-band, and the points of coincidence in tint on the strip and each of the insolated papers can be easily ascertained by reading off by the light of a soda-flame in a dark room. The lens (B.) fixed upon the brass pillar of the instrument serves to concentrate the light from the flame upon the small surface under examination. If a coal-gas flame can be procured at the Observatory, the best mode of obtaining the monochromatic light is to place two beads of sodic carbonate upon fine platinum loops into the colourless flame of a Bunsen burner ; if a coal-gas flame cannot be obtained, the flame of a lamp fed with spirit saturated with common salt can be used, and beads of the more volatile sodic chloride held into the flame. The reading of each observation is made ten times, and the mean of these readings taken as the result. The following observations of the intensity of the chemical action of light on July 8, 1864, may serve as an example of the detail of the determinations. Solar time. T. Duration of exposure, Mean reading, R. Tabulated intensity of strip, Calculated intensity, n Condition of solar disk. Amount of cloud. Barom. Temperature. Dry bulb. Wet bulb. h m millims. 7 10 A.M. 18 96 1*00 0-055 Clouded over 8 7 50 15 93 1*03 . 0-068 Clouds 7 8 25 12 90 1-06 0-089 j> 9 9 0 10 76 1-20 0-12 jj „ 9 30 10 75 1-21 0-12 „ millims. 10 30 10 64 1*33 0-13 „ 765-1 18-6 C. 13-9 C. 11 0 10 76 1*20 0-12 Clouded over 10 11 30 10 67 1-30 0-13 „ „ 12 0 10 86 M0 0-11 „ 18-7 13-3 12 30 p.m. 6 107 0-78 0-13 Light clouds 9 19-3 13-5 1 10 8 73 1-24 0-15 „ 7 1 40 5 105 0-80 0-16 „ 19-3 13*7 2 15 4 93 1-03 0-26 Unclouded ... 4 19-7 13-9 3 0 4 80 1-16 0-29 » 3 20-0 14-4 3 30 21 (with disk) 99 0-93 0-26 4 0 5 86 M0 0-22 n 21-1 14-4 4 30 8 76 1*20 0-15 1 5 0 11 66 1*31 0-12 6 10 60 116 0-66 0-011 » ” KEGISTEATION OF THE CHEMICAL ACTION OE TOTAL DAYLIGHT. 617 IV. Concerning the accuracy and trustworthiness of the method. The most satisfactory mode of testing the reliability and accuracy of the method of measurement just described, is to compare the results of two series of independent determinations of the chemical action of daylight, made simultaneously at the same spot with the present arrangement and with the pendulum photometer, according to the method described in the last memoir, upon which the present mode of measure- ment is founded. For the purpose of making these comparisons, the strips of standard photographic paper placed in the pendulum apparatus (see fig. 1 of last memoir) and the pieces of the same material placed on the insolation-band in the exposing slide (fig. 3, A) were simultaneously insolated, each for a known length of time, both instru- ments being placed near one another in a position (on the roof of the laboratory of Owens College, Manchester) having a tolerably free horizon. If the varying daily intensities thus measured by the two methods are found to agree, we may conclude that the unavoidable experimental errors arising from graduation, exposure, and reading are not of sufficient magnitude materially to affect the accuracy of the measurement. The intensity with the pendulum photometer was determined exactly as described on pp. 158 & 159 of the above-cited memoir ; the time of exposure and the number of vibrations were noted, the position at which the strip possessed a shade equal to that of the normal tint was then read off, and the corresponding intensity obtained by dividing the number found in Table II. of the above memoir by the number of the vibrations. The intensity, according to the new method, was obtained by insolating the standard paper in the exposing slide (fig. 3, A) for a known number of seconds, and then reading off, by means of the arrangement shown in fig. 6, the position in millimetres on the calibrated strip equal in shade to the exposed paper. The number found in the second column of the Intensity Table, of the strip opposite to this position, when divided by the time of exposure in seconds, gives the required intensity. In this way comparisons of the working of the two modes of measurement have been made during four different days. On each of these days a large number of simultaneous observations were made, and on some of them two or more determinations were made with each instrument immediately succeeding each other. An examination of the following Tables, giving the results of these observations, shows that the agreement between the intensities as obtained by the two methods is as close as can be expected. 618 PEOEESSOE EOSCOE ON A METHOD OF METEOEOLOGICAL Simultaneous Measurements with Pendulum Instrument and New Photometer. April 29th, 1864. May 10 th, 1864. Time. Intensity. Difference. Time. Intensity. Difference. Pendulum instrument. New photometer. Pendulum instrument. New photometer. h m 9 30 a.m. 10 0 11 0 11 5 12 30 p.m. 12 32 1 30 2 0 2 30 3 0 3 0 3 30 0-210 0-160 0-073 0-064 0-200 0-210 0-068 0-105 0-124 0-136 0-117 0-157 0-180 0-160 0-083 0-078 0-210 0-220 {!«}“4 0-105 J 0*1331 [ 0-133 j 0-144 0-114 0-182 -0-03 0-00 + 0-010 + 0-014 -0-01 + 0-01 -0-04 0-00 + 0-009 + 0-008 — 0-003 + 0-025 h m 9 0 A.M. 10 0 11 15 12 30 p.m. 1 1 0 2 30 2 33 4 30 0-093 0-100 0-130 0-220 0-100 0-105 0-115 0-0125 {S2}«» 0-110 0-150 0-250 f 0 099l o-lOO \ 0-102 J u luu / 0-109 1 Q.JQO 1 0-096/ u 0-116 0-0106 -0*011 + 0-010 + 0-020 + 0-030 0-000 —0-003 + 0-001 -0-002 Simultaneous Measurements (continued). June 8, 1864. Intensity. Time. Pendulum New Difference. Time. photometer. instrument. h m h m 10 40 A.M. 0-229 0-203 -0-026 9 50 A.M. 10 42 0-232 {S}0'233 + 0-001 10 25 11 25 0-218 0-207 -0-011 10 40 11 27 0-225 0-217 -0-008 1 33 p.m. 0-205 0-231 + 0-026 2 15 0-218 0-230 + 0-012 11 45 2 17 0-224 0-233 + 0-009 3 20 0-072 0-064 -0-010 3 22 4 0 0-077 0-039 0-068 0-048 -0-009 + 0-009 12 15 p.m. 4 3 0-031 0-036 + 0-005 12 45 1 30 2 21 2 46 July 16, 1864. Intensity. Pendulum photometer. New instrument. Difference. {53} PP 0-19 °‘14 I ft - or 0-13/ 0135 { {53} 0-24 0*16 0-18 0-20 0*17 h0*21 0-17 f 0*24') J 0*20 0-19 1 0-18 , h0-20 J f0-17' ft- ^0-205 0-145 0-13^1 III 0-13 J 0-00 -0-02 + 0-02 + 0-012 -0-025 + 0-02 + 0-008 The curves on figs. 7, 8, & 9, Plate XXVIII. exhibit these results graphically for the first three days, and a glance at these curves show how closely the measurements made REGISTRATION OF THE CHEMICAL ACTION OF TOTAL DAYLIGHT. 619 by the two methods agree. The black line represents the intensity as determined by the pendulum instrument, the dotted line that obtained by the new photometer, the abscissae giving the times of observation, and the ordinates the chemical intensity in the terms of the unit above described. The mean chemical intensities, as observed on the above days by the two methods, are represented by the following numbers, for the definition of which the reader is referred to page 621. Daily Mean Chemical Intensity. Plate XXVIII. 1. Pendulum photometer. 2. New instrument. Fig. 7, April 29, 1864 . . . 62-0 62-3 Fig. 8, May 10, 1864 . . . 41-3 43-3 Fig. 9, June 8, 1864 . . , . 64-7 65-3 From these results the agreement of the two methods is well seen. As a second test of the trustworthiness and availability of the method for actual measurement, I give the following results of determinations, made at the same time and on the same spot, by two observers with two of the new instruments. These determi- nations, made with the two graduated fixed strips B and C (page 613), were conducted in every way independently, so that the results serve as a fair sample of the accuracy with which the measurements can be practically carried out. Simultaneous Determinations made independently with two Instruments by two observers. July 11, 1864. July 15, 1864. Time. Chemical Intensity. Time. Chemical Intensity. Instrument 1. Strip B. Instrument 2. Strip C. Instrument 1. Strip B. Instrument 2. Strip C. h m h m 10 30 A.M. 0-16 0-14 10 0 A.M. 0-16 0-17 0-14 0-14 10 1 0-19 0-19 io’ 31 0-14 0-15 11 0 0-049 0-046 0-12 0-13 11 1 0-049 0-046 io’ 32 0-13 0-11 11 35 0-12 0-12 y 9 0-15 0-12 99 0-12 0-12 10 33 0-14 0-12 11 36 0-12 0-13 li 0 0-13 0-12 0-11 0-11 12 0 0-31 0*27 12* 30 p.m. 0-13 0-10 12 30 p.m. 0-31 0-29 0-13 0-12 12 31 0-38 0-37 99 0-14 0-13 12 32 0*33 0-31 0-14 0-12 12 33 0-35 0-32 \ ’ 0 0-17 0-17 1 5 0-13 0-13 0-18 0-18 2 0 0-27 0-25 2 *30 0-057 0-060 0-27 0-25 0-068 0-070 3’ ’lO 0-24 0-23 3’ 30 0-059 0-057 3 11 0-21 0-24 0-067 0-062 3 12 0-18 0-23 3 *31 0-063 0-045 3 13 0-17 0-18 0-054 0-045 3 40 0-24 0*23 A 20 0*028 0-025 3 41 0-14 0-15 0-028 0-025 4 0 0-21 0-20 0-032 0-028 4 30 0-11 0-13 0-14 0-14 A 31 0-14 0-15 0-15 0-14 4’ 32 0*16 0-14 620 PROFESSOR ROSCOE ON A METHOD OF METEOROLOGICAL Figs. 10 & 11, Plate XXVIII. exhibit the daily curve of chemical intensity thus deter- mined; the close agreement of the two curves for each day shows that the errors of graduation, exposure, and reading do not materially affect the accuracy of the measure- ments; whilst the values of the Daily Mean chemical intensities obtained from each curve, viz. 42-0 and 4P7 for fig. 11, July 15, 1864 ; and 74'3 and 70'0 for fig. 10, July 11, 1864, confirm this conclusion. V. Application of the Method to actual Registration. A series of determinations of the varying intensity of the chemical action of total daylight, made at Manchester on more than forty days, at the most widely differing seasons of the year, extending from August 1863 to September 1864, serves to show, in the first place, that the daily determination of the varying chemical intensity can without difficulty be carried on ; whilst, secondly, they reveal a few of the many interesting results to which an extended series of such measurements must lead. The whole of the observations, with a few exceptions, were carried on in Manchester, upon the roof of the laboratory of Owens College. As a rule, one observation was made every half-hour ; frequently, however, when the object was either to control the measure- ments, or to record the great changes which suddenly occur when the sun is obscured or appears from behind a cloud, the determinations were made at intervals of a few minutes or even seconds. Sometimes, when the sky was overclouded, or when no great changes in the light occurred, the observations were made once every hour. On most of the days employed for observation, the temperature, atmospheric moisture, barometric pressure, varying amount of cloud, and the condition of the sun’s disk were noted. The curves given on Plate XXIX. serve to exhibit these same results graphically, the abscissae representing the hours of the day (solar time), and the ordinates giving corre- sponding chemical intensity expressed in terms of the unit above described. Consecutive observations were carried on each day for nearly a month, from June 16 to July 9, 1864 ; the labour thus incurred was found to be comparatively light, so that, when all the preliminary arrangements are made, the daily measurements take up but a small portion of the attention and time of one observer. From the results of these measurements the great difference becomes perceptible which often exists between the chemical inten- sity of neighbouring days ; examples of this variation are seen on PlateXXIX. figs. 12 & 13, for June 27th and 28th, and on figs. 14 & 15, for June 29th and 30th. The tabular results show that the amount of chemical action generally corresponds to the degree of cloud or sunshine, as noted in the observation. Irregular changes in the chemical action are, however, observed on some days (as on March 19, 1864, fig. 16), on which the sun shone continuously, and these are to be mainly attributed to the variation in the amount of cloud passing at the time of observation. In several cases, when no apparent change in the amount of light as affecting the eye could be noticed, a considerable and sudden alteration in the chemical intensity occurred. This was clearly seen on September 26, REGISTRATION OE THE CHEMICAL ACTION OE TOTAL DAYLIGHT. 621 1864, when the whole sky was apparently unclouded throughout the day; at 9h 25' a.m. the chemical intensity was found to be (M3; at 10h, without any visible change in the light, the chemical action sank to 007, and continued at this point for more than half an hour, rising again to (Ml at 11 o’clock. That this diminution of the chemical activity arises from the presence of mist, or of suspended particles of water imper- ceptible to the eye, is rendered probable by the very powerful absorptive action which a light haze or mist exerts upon the chemical rays. Thus on March 18, 1864, the action at 8l1 a.m., when a light mist obscured the sun, amounted to 00026, whereas the normal action for that day and hour, with an unclouded sky, is twenty-five times as large. It is scarcely necessary to remark that on this occasion the ratio of decrease of visible luminosity was not nearly so great. The same absorptive action of mist is well seen in the following measurements on September 27 and 28, 1864. September 27, clear sun. September 28, , sun obscured by haze. Time. Intensity. Weather. Time. Intensity. Weather. h m 10 0 A.M. 0-13 Clear sky and direct sun. h m 10 0 A.M. 0-016 Hazy. 10 30 0-17 10 30 0-039 „ 11 0 0-18 11 0 0-053 „ 11 30 0-13 11 30 0-075 „ [pearing. 12 40 p.m. 0-16 „ 12 0 0-042 Sunshine, haze gradually disap- 1 10 0-13 12 45 p.m. 0-056 1 40 0-17 : i o 0-053 „ 2 10 0-14 „ 1 30 0-10 Haze gone. 2 15 0-12 For the purpose of expressing the relation of the sums of all these various hourly intensities, giving the daily mean chemical intensity of the place, a rough, but sufficiently accurate method of integration may be resorted to. This consists simply in cutting the curves out in strong homogeneous paper or cardboard, and in determining in each case the weights of the paper enclosed between the base-line and the curve. A por- tion of the paper of given size is cut out between every four or five curves, and the small variations in weight caused by irregularity in the thickness of the paper thus allowed for. In the following Table the numbers are compared with the action, taken as 1000, which would be produced by light of the intensity 1 acting uniformly throughout the twenty-four hours. 4 Q MDCCCLXV. 622 PROFESSOR ROSCOE ON A METHOD OE METEOROLOGICAL Daily Mean Chemical Intensities at Manchester, 1863-64. (Intensity 1*0 acting for 24 hours = 1000.) Date. Intensity. Date. Intensity. Date. Intensity. 1863. 1864. 1864. August, 26 40-5 March 19 36-8 June 28 .. 26-6 27 29-8 April 19 78-6 29 26-7 Sppt. 4 41-8 20 85-3 30 64-4 16 . 30-8 June 16 100-7 July 1 61-5 23 12*4 17 47-2 19-1 24 18-7 18 118-7 4 51-2 25 18-1 20 50 '9 5 76-2 28 29'1 21 99-0 6 78-9 Dee. 21 3-3 22 119-0 7 39-1 4*7 23 81-4 8 1 72-2 25 83-0 9 83-6 ! 27 83-0 Sept. 26 48-8 The remarkable differences observed in the chemical intensity on two neighbouring days is shown on fig. 17, in which the curves for the 20th and 22nd June 1864 are represented. The integrals for these days are 50 ‘9 and 119’; or the total chemical action on the 20th and 22nd June is in the ratio of 1 to 2*34. The chemical action of daylight at Manchester at the winter and summer solstice, and the vernal and autumnal equinoxes, is clearly seen by reference to the curves on fig. 18, in which the actions on September 28, 1863, December 22, 1863, March 19, 1864, and June 22, 1864, are represented graphically. These days were chosen out from amongst the observations made near the required periods, as being days upon which the sun shone most brightly, and as therefore giving the nearest approach to the maximum actions for the several periods in question. The integral for the winter solstice is 4*T, that of the vernal equinox 36'8, that of the summer solstice is 119, and that of the autumnal equinox 29 T. Hence if the total chemical action on the shortest day be taken as the unit, that upon the equinox will be represented by 7, and that upon the longest day by 25. From these numbers, as well as from the curves (fig. 18), it is seen that the increase of chemical action from December to March is not nearly so great as that from March to June. With the small amount of experimental data which we as yet possess upon this subject, it is useless to attempt to give an explanation of the probable cause of this difference ; suffice it to say that it does not appear to be mainly produced by the absorptive action exerted by the direct sunlight in passing through the different lengths of the columns of air which the rays have to traverse on the days in question. In carrying out a regular series of meteorological observations upon the variation of mean daily chemical intensity at any spot, a fair average result may be obtained by a much smaller number of observations than is necessary when the object is to indicate the rapid changes occurring in the intensity. Thus, for instance, if determinations had been made on the following days once every two hours, viz. at 8b, 10h a.m., 12h, 2h, 4h, REGISTRATION OF THE CHEMICAL ACTION OE TOTAL DAYLIGHT. 623 and 6h P.M., instead of about every fifteen minutes, the numbers for mean chemical intensity would have been — Date. Mean Chemical Intensity. From 26 observations. From 6 observations. ] 863, August 26 40-5 43-0 „ Sept. 4 41-8 42-7 1864, April 20 85-3 96-3 As examples of simultaneous determinations made in different localities, I give the results of observations made by myself in Heidelberg, lat. 49° 24' N., on July 4, 1864, and near Dingwall in Rossshire, lat. 57° 35' N, on September 27, 1864, compared with the results of observations made in Manchester, 53° 20' N. latitude, by my assistant. The curves for Heidelberg and Manchester are given in fig. 19, those of Dingwall and Manchester on fig. 20. The integral giving the mean action at Heidelberg on July 4 is 160, that at Manchester on the same day being 51 -2; so that the chemical action at Manchester and Heidelberg was on July 4 in the ratio of 1 to 3T2. The integral for Dingwall on September 27 is 66-4, whilst that of Manchester is 49-5 ; or the ratio of chemical action at Manchester and Dingwall on the day in question was 1 to T34. From these observations it would appear that the chemical action at Manchester is smaller than accords with the latitude of the place. This is easily accounted for by the absorptive action exerted by the atmosphere of coal smoke in which the whole of South Lancashire is constantly immersed. Indeed, from the frequent occurrence in Man- chester of dull or rainy days, and of fogs or mists, it would be difficult to choose a spot more unsuited to the prosecution of experiments on the chemical action of light. From the integrals of daily intensity giving the mean chemical action for each day, the mean monthly or yearly chemical intensity of the place of observation can, in like manner, be ascertained ; so that, should this method of measurement prove capable of general adoption, we may look forward to obtaining in this way a knowledge of the distribution of the chemically active rays over the surface of our planet analogous to that which we already possess respecting the heating rays. 624 PROFESS OR ROSCOE ON A METHOD OE METEOROLOGICAL Tables giving the Results of the Measurement of Daily Chemical Intensity in 1863-64, at Manchester, Heidelberg, and Dingwall. Daily Chemical Intensity, Manchester, 1863. August 26, 1863. Barom. = 746 millims. September 4, 1863. Barom. = 756 millims. Solar time. Chemical inten- sity of light. Sun’s disk. Solar time. Chemical inten- sity of light. Sim’s disk. h m h m 7 3 A.M. 0-060 Unclouded. 7 45 A.M. 0-062 Unclouded. 7 33 0-038 Cloudy. 8 15 0-075 7 45 0-092 Unclouded. 8 45 0-083 Ditto, hazy. 8 15 0-077 9 20 0-098 Unclouded. 8 45 0-070 Unclouded, hazy. 9 40 0-097 ,, 9 15 0-086 Unclouded, haze. 10 0 0-166 99 9 45 0-97 10 30 0-115 99 10 30 0-133 10 45 0-173 99 10 50 0-187 11 0 0-165 99 11 10 0-148 11 30 0-135 Cloud. 11 13 0-191 11 42 0-079 11 30 0-229 11 50 0-128 Unclouded. 11 50 0-203 Light clouds. 11 57 0-137 ,, 12 0 0-160 12 10 p.M. 0-072 Clouded. 12 20 p.m. 0-210 Unclouded. 12 26 0-159 Unclouded. 12 40 0-075 Cloudy. 12 29 0-143 1 0 0-062 99 12 45 0-165 99 1 22 0-062 1 20 0-099 Light clouds. 1 40 0-094 Light clouds. 1 21 0-105 „ 2 20 0-069 Clouds. 2 25 0-149 Unclouded. 3 0 0-021 2 45 0-038 Cloudy. 3 30 0-016 Clouded over. 3 0 0-024 99 4 0 0-016 n 3 30 0-035 99 4 30 0-018 n 4 0 0-040 Cloudy, rain. 5 0 0-009 » 5 0 0-035 Clouds. 5 30 0-004 5 30 0-016 6 0 0-010 ” August 27, 1863. September 16, 1863. Barom. = 745 millims. Barom. = 767 millims. 8 5 A.M. 0-026 Cloudy. 9 0 A.M. 0-059 Cloudy. 8 33 0-068 Clouds. 9 35 0-120 Light clouds. 9 0 0-041 10 15 0-078 Overclouded. 9 45 0-039 10 45 0-077 „ 10 30 0-098 Light clouds. 11 15 0-041 „ 11 0 0-146 11 45 0-104 11 4 0-132 Unclouded. 12 0 0-103 t 11 30 0-115 Light clouds. 12 35 p.m. 0-080 „ 12 0 0-059 Cloudy. 1 0 0-086 „ 12 30 p.m. 0-122 Unclouded. 2 0 0-091 ,, 1 0 0-057 Clouds. 2 40 0-093 „ 1 30 0-078 Clouded over. 3 20 0-037 ,, 2 0 0-159 Sunshine. 4 0 0-027 Rain. 2 20 0-155 4 45 0-034 Clouds. 3 0 0-027 Clouded over. 6 0 0-007 „ 3 20 0-051 Light clouds. 3 50 0-066 Unclouded. 4 10 0-004 Overclouded. 4 30 0-002 Thunder-storm. REGISTRATION OE THE CHEMICAX ACTION OF TOTAL DAYLIGHT. G25 Daily Chemical Intensity, Manchester, 1863 (continued). September 23, 1863. Barom. = 738 millims. Solar time. sity of light. Sun’s disk. h m 9 0 A.M. 0-026 Overclouded. 9 30 0-054 Light clouds. 10 0 0-063 Overclouded. 10 30 0-042 11 0 0-065 Light clouds. 11 30 0-077 Sun, clouds. 12 0 0-013 Overclouded. 12 20 p.m. 0-031 12 45 0-041 1 0 0-056 n 1 50 0-062 2 10 0-038 2 30 Rain. Heavy rain. 4 0 0-01 September 24, 1863. Barom. = 744 millims. 9 0 A.M. 0-068 Light clouds. 9 30 0-069 10 10 0-105 Sunshine. 10 40 0-016 Overclouded. 11 20 0-038 Light clouds. 11 40 0-015 Overclouded. 12 0 0-033 Light clouds. 12 30 p.m. 0-046 12 45 0-087 Unclouded. 12 46 0-099 99 1 0 0-110 99 1 55 0-088 Light clouds. 2 10 0-068 Unclouded. 2 40 0-042 Overclouded. 3 0 0-021 }j 3 30 0-014 j Rain. 5 0 0-014 Overclouded. September 25, 1863. Barom. = 753 millims. 9 0 A.M. 0-042 Overclouded. 9 40 0-077 Unclouded, hazy. 10 20 0-035 Light clouds. 11 0 0-042 11 30 0-037 1 50 p.m. 0-031 Overclouded. 2 20 0-055 Light clouds. 2 21 0-075 Unclouded. 2 22 0-081 ” September 25, 1863 (continued). Barom. = 753 millims. Solar time. Chemical inten- Sun’s disk. sity of light. h m 2 50 p.m. 0-065 Unclouded. 3 15 0-050 Light clouds. 3 20 0-064 Unclouded. 3 50 0-063 3 50 0-063 5 0 0-012 Overclouded. September 28, 1863. Barom. = 755 millims. 9 20 a.m. 0-045 Light clouds. 10 20 0-108 Unclouded. 10 21 0-108 10 55 0-101 99 10 56 0-106 99 11 20 0-125 99 11 48 0-133 Overclouded. 12 20 p.m. 0-047 1 0 0-052 99 1 40 0-055 Light clouds. 2 30 0-099 Unclouded. 2 31 0-094 99 3 0 0-080 99 3 1 0-079 3 40 0-072 » 3 50 0-059 4 0 0-044 4 10 0-043 4 30 0-037 Light clouds. ” 5 0 0-019 5 30 0-004 December 21, 1863. Barom. = 760 millims. 11 0 a.m. 0-013 Clouds. 11 10 0-011 99 11 20 0-012 Hazy. 11 30 0-014 99 11 43 0-019 Unclouded. 12 0 0-003 Rain. 12 15 p.m. 0-018 Clouds. 12 30 0-010 Overclouded. 1 0 0-017 Light clouds. 1 30 0-013 Overclouded. 2 0 0-066 2 30 0-0066 3 0 0-0084 3 30 0-0017 ” 626 PROFESSOR ROSCOE ON A METHOD OF METEOROLOGICAL Daily Chemical Intensity, Manchester, 1863-64. December 22, 1863. Barom. = 761 millim-'. April 19, 1864 (continued). Barom. = 758 millims. Solar time. Chemical inten- sity of light. Sun’s disk. Solar time. Chemical inten- sity of light. Sun’s disk. h m h m 9 10 a.m. 0-0077 Hazy. 10 0 A.M. 0-29 Unclouded. 9 40 0-0057 Cloudy. 10 46 0-20 10 20 0-011 i9 11 0 0-33 11 20 0-020 12 0 0-25 99 11 40 0-025 . 1 0 P.M. 0-26 11 50 0-026 Unclouded. 2 14 0-15 11 55 0-028 2 45 0-20 12 0 0-023 Light clouds. 3 15 0-13 „ 12 30 p.m. 0-020 Hazy. 3 45 0-11 12 35 0-032 Unclouded. 4 20 0-10 „ 1 0 0-029 Hazv. 4 50 0-081 „ 1 30 0-017 Unclouded. 2 0 0-017 2 30 0-0066 ” April 20, 1864. Darom. = /oy minims. March 19. 1864. 6 50 a.m. 0-067 Hazy. Barom. = 753 millims. 7 45 0-17 Unclouded. — 8 15 0-22 Hazy. 8 0 A.M. 0-0026 Misty. 8 45 0-22 „ 9 0 0-070 Unclouded. 9 20 0-35 „ 9 40 0-120 10 0 0-26 Unclouded. 10 25 0-080 10 50 0*30 ,, 10 45 0-13 11 15 0-16 11 0 0-13 11 30 0-17 11 15 0-080 11 40 0-19 11 35 0-10 99 11 50 0-17 11 45 0-11 12 0 0-16 „ 11 55 0-10 12 30 p.m. 0-16 12 0 0-12 12 45 0-14 12 5 p.m. 0-12 1 1 0-18 „ 12 10 0-12 99 1 30 0-14 „ 12 33 0-14 2 5 0-23 1 0 0-12 „ 2 46 0-12 Cloudy. 1 35 0-045 3 13 0-11 2 20 0-11 3 30 0-10 „ 3 30 0-069 Light clouds. 4 15 0-091 „ 4 40 0-039 5 5 0-094 „ 6 0 0-007 5 30 0-060 „ 6 5 0-041 6 50 0-014 ” April 19, 1864. 7 30 0-0037 „ Barom. = 758 millims. 7 50 a.m. 0-10 Unclouded. 9 25 0-22 ” REGISTRATION OF THE CHEMICAL ACTION OF TOTAL DAYLIGHT. 627 Daily Chemical Intensity, Manchester 1864. June 16th, 1864. Barom.=758‘3 millims Mean Temp. Dry bulb 17°‘9. „ Wet bulb 12°-9C. June 18th, 1864. Barom.=761 millims. Solar time. Chemical intensity of light. Amount of cloud. Sun’s disk. Solar time. Chemical intensity of light. Amount of cloud. Sun’s disk. h m h m 6 25 A.M. 0-039 Clouded over. 7 50 A.M. 0-19 Unclouded. 7 0 0-019 99 8 40 0-30 99 7 30 0-10 Clouds breaking. 9 10 0-19 Clouds. 8 0 0-13 „ 9 55 0-19 8 30 0-15 Light clouds. 10 45 0-13 9 0 0-13 Clouded over. 11 30 0-19 99 9 30 0-24 Unclouded. 12 35 p.m. 0-33 Light clouds. 10 0 0-38 „ 1 30 0-38 99 10 30 0-29 „ 3 0 0-21 ,, 11 0 0-38 „ 4 0 0-22 Unclouded. 11 30 0-35 „ 6 30 0-033 Clouds. 12 0 0-22 Light cloud. 8 0 0-0079 99 12 30 p.m. 0-37 1 0 0-31 June 20th, 1864. Mean Temp. Dry bulb 19°-5. 1 30 0-26 „ Barom. =763-8 millims. „ Wet bulb 15°-9 C. j 2 0 0-24 1 0-23 } ” 8 0 A.M. 0-14 Light clouds. 2 30 0-17 Clouds. 8 45 0-14 Clouds. 3 0 0-13 Unclouded. 9 15 0-099 99 3 30 0-15 Light clouds. 9 55 0-094 99 4 0 0-10 „ 10 30 0-16 99 4 30 0-052 Clouded over. 11 0 0-12 5 0 0-045 „ 11 30 0-15 99 5 30 0-087 Light clouds. 12 0 0-13 99 7 15 0-030 „ 12 15 p.m. 0-13 99 8 15 0-010 „ 12 45 0-16 ' 99 8 40 0-0027 „ 1 0 0-15 99 0-11 June 17th, 1864. Mean Temp. Dry bulb 20° '5. 1 O'/ 2 10 0-074 99 Barom.=760-9 millims. „ Wet bulb 17°T C. 2 45 0-075 ,, 3 15 0-044 6 40 A.M. 0-053 Clouded over. 3 50 0-053 Clouded over. 7 10 0-086 4 30 0-031 7 50 0-18 )} 5 30 0-030 Rain. 8 30 0-11 Light clouds. 7 0 0-010 „ Q ft o. 1 1 y u 9 30 U 11 0-28 ” June 21st, , 1864. Mean Temp. Dry bulb 16°-1. 9 55 0-13 Clouded over. „ Wet bulb 11°-1 C. 10 25 0-045 }) 11 10 0-15 }J 6 40 A.M. 0-12 11 40 0-12 7 15 0-13 Light clouds. 12 10 p.m. 0-14 )} 7 45 0-074 „ 12 30 0-14 8 30 0-080 „ 1 0 0-35 9 30 0-21 Unclouded. 1 35 0-18 )} 10 0 0-27 Light clouds. 2 0 0-12 10 30 0-27 2 40 0-059 )} 11 10 0-33 5 3 10 0-062 11 30 0-29 Sun shining. 3 40 0-027 12 0 0-072 8 Clouds. 4 20 Rain. 12 30 p.m. 0*22 8 Unclouded. 628 PEOEESSOB EOSCOE ON A METHOD OE METEOBOLO GTCAL Daily Chemical Intensity, Manchester, 1864 (continued). June 21st, 1864 (continued). Mean Temp. Dry bulb 16°T. „ Wet bulb 11°T. Chemical Amount Sun’s disk. Solar time. intensity of light. of cloud. h m 1 0 P.M. 0-29 6 Unclouded. 1 35 0-28 6 Clouds. 2 45 0-21 4 Unclouded. 3 15 0-24 3 Hazy sunshine. 4 15 0-13 Unclouded. 5 30 0-038 Clouds. 6 10 0-031 „ 7 40 0-012 ” June 22nd, 1864. Mean Temp. Dry bulb 17°‘6. Barom. =761 millims. » Wet bulb 13°-5 C. 8 0 A.M. 0-15 Clouded over. Rain. 8 45 0-017 10 Clouded over. 9 15 0-22 6 Clouds. 10 0 0-22 9 „ 10 30 0-21 8 „ 11 0 0-19 8 ,, 11 30 0-45 6 Unclouded. 12 15 p.m. 0-49 5 1 30 0-28 3 „ 1 50 0-27 5, 2 0 0-26 2 2 30 0-38 ,, 3 0 0-17 ’ 5 Light clouds. 3 30 0-17 o 99 4 0 0-16. 3 Unclouded. 5 0 0-15 1 6 0 0-068 Clouds. June 23rd, 1864. Mean Temp. Dry bulb 15°T. Barom. =757"6 millims. ” Wet bulb ll°-6 C. 7 0 A.M. 0-090 10 Heavy rain. 9 20 0-18 10 Clouded over. 10 10 0-18 9 11 30 0-18 9 Rain. 12 0 0-21 10 Clouds. 1 0 P.M. 0-22 7 Rain. 3 0 0-16 3 40 0-17 6 Unclouded. 4 35 0-12 8 Clouded. 5 0 0-093 9 1 ” June 25th, 1864. Mean Temp. Dry bulb 16°'7. Barom. =761-2 millims. „ Wet bulb 13°-4. 7 45 A.M. 0-055 10 Clouded over. 8 30 0-14 10 „ 10 10 0-27 10 „ 11 0 0-18 10 „ 12 0 0-27 10 „ 12 30 p.m. 0-22 ” June 25th, 1864 (continued). Mean Temp. Dry bulb 16°-7. Barom. =761-2 millims. „ Wet bulb 13-4. Chemical Amount Solar time. intensity of light. of cloud. Sun’s disk. h m 1 0 P.M. 0-16 Clouds. 1 45 0-33 Clouded over. 2 30 0-23 8 Unclouded. 3 10 0-13 10 Clouded over. 5 15 0-10 6 30 0-037 ” June 27 th, 1864. Mean Temp. Dry bulb 16°-4. Barom. =765'2 millims. ” Wet bulb 12°-0 C. 7 45 A.M. 0-15 4 Light clouds. 8 30 0-22 4 Unclouded. 9 10 0-11 8 Clouds. 9 30 0-25 7 Unclouded. 10 0 0-12 6 Clouds. 10 40 0-34 4 Unclouded. 11 30 0-11 9 Clouded over. 12 0 0-21 7 Unclouded. 115 P.M. 0-050 9 Clouded over. 4 30 0-17 1 Unclouded. 5 7 0-15 1 „ 5 30 0-092 1 „ 6 0 0-020 ” June 28th, 1864. Mean Temp. Dry bulb 15°-0. Barom. =763-2 millims. ” Wet bulb 13°-4C. 7 30 A.M. 0-031 10 Clouded over. 8 40 0-043 10 „ 9 SO 0-15 10 10 20 0-060 10 11 0 0-037 10 Rain. 11 30 0-034 10 ,, 12 30 p.m. 10 ,, 2 30 0-095 10 - June 29th, 1864. Mean Temp. Dry bulb 13o,0. Barom. =759-2 millims. Wet bulb ll°-4 C. 7 40 A.M. 0-11 10 Clouds. 8 30 0-13 10 „ 9 40 0-042 10 „ 10 20 0-044 10 „ 11 20 0-047 „ 11 35 0-026 „ 12 0 0-022 „ 12 30 p.m. 0-040 „ 1 15 0-018 „ 2 20 0-013 ,, 3 0 Rain. 4 0 0-028 Clouds. 5 0 0-014 ” REGISTRATION OF THE CHEMICAL ACTION OF TOTAL DAYLIGHT. 629 Daily Chemical Intensity, Manchester, 1864 (continued). June 30th, 1864. Mean Temp. Dry bulb 12°-6. Barom.=758 millims. „ Wet bulb 12°T. July 4th, 1864 (continued). Barom. =759-5 millims. Mean Temp. Dry bulb 20° -3. „ Wet bulb 11 °-8. Solar time. Chemical intensity of light. Amount of cloud. Sun’s disk. h m 12 0 0-065 9 Rain. 12 30 p.m. 0-070 9 „ 1 0 0-097 8 „ 1 30 0-090 8 „ 2 0 0-14 8 „ 2 30 0-14 Clouds. 3 0 0-34 Unclouded. 3 30 0-25 5 „ 4 0 0*11 7 Clouded. 4 30 0-095 7 „ 5 0 0-074 6 „ 5 30 0-072 6 6 0 0-056 6 „ 6 30 0-067 2 Sunshine. 7 0 0-043 0 Unclouded. 7 30 0-023 0 ” July 5th, 1864. Mean Temp. Dry bulb 14° -0. Barom. =761-6 millims. „ Wet bulb 10° -7. 8 10 A.M. 0-12 10 Clouds. 8 30 0-10 10 „ 9 0 0-033 10 „ 9 30 0-14 10 „ 10 0 0-11 10 „ 10 30 0-077 10 „ 11 0 0-14 10 „ 11 30 0-15 10 „ 12 0 0-18 10 „ 12 30 p.m. 0-12 10 „ 1 0 0-10 10 » 1 45 0-32 7 Light clouds. 2 15 0-13 10 Clouded over. 2 45 0-28 6 Unclouded. 3 30 0-25 6 Clouds. 4 0 0-18 6 Light cloud 4 30 0-26 6 „ 5 0 0-072 7 „ 5 30 0-093 6 6 0 0-067 4 Clouds. 7 30 0-035 4 Unclouded. July 6th, 1864. Mean Temp. Dry bulb 17°-6. Barom. =765’3 millims. „ Wet bulb 13 -4. 7 30 A.M. 0-058 1 Hazy. 8 0 0-083 1 „ 8 30 0-10 3 „ 9 0 0-077 7 Clouds. 9 30 0-20 7 Hazy. 10 15 0-13 4 „ 10 45 0-078 10 Clouded over. 11 20 0-071 6 Light clouds. 11 50 o-io . 7 ” Chemical intensity Amount of cloud. Sun’s disk. h m 7 15 A.M. 8 15 9 10 10 0 11 0 11 30 12 0 12 30 p.m. 1 45 3 0 4 0 4 30 5 20 6 10 0-021 0-10 0-21 0-060 0-37 0-12 0-46 0-077 0-090 0-061 0-075 0 054 0-010 Clouded over. Sunshine cloud. Clouds. Sunshine cloud. Clouds. Unclouded. Clouded over. Rain. Light clouds. Sun shining. July 1st, 1864. Barom. =758-2 milli Mean Temp. Dry bulb 14° -6. „ Wet bulb 11°-1. 8 15 A.M. 0-067 9 Clouded over. 9 5 0-11 4 Light clouds. 9 40 0-12 9 10 0 8 Rain. 10 30 0-17 Light clouds. 11 0 0-19 7 Clouds. 11 45 0-086 Clouded over. 12 30 p.m. 0-040 1 0 0-20 Sunshine. 2 15 0-25 5 Unclouded. 3 45 0-085 Clouded. 4 30 0-063 5 30 0-050 ” July 2nd, 1864. Barom. =752 millims. 8 10 A.M. 0-042 10 Rain. 10 0 10 Rain. 12 0 0-028 3 45 p.m. 0-071 Fair, clouded. 4 20 0-046 4 50 0-043 Rain. July 4th, 1864. Mean Temp. Dry bulb 20° -3. Barom. = 759'5 millims. „ Wet bulb ll°-8. 7 30 A.M. 0-076 8 Clouded. 8 0 0-11 6 ” 8 30 0-077 9 9 0 0-041 10 Rain. 9 30 0-023 10 Clouded over. 10 10 0-055 9 10 30 0-056 9 11 0 0-038 9 Rain. 11 30 0-034 10 ” 4 R MDCCCLXV. 630 PROFESSOR ROSCOE ON A METHOD OE METEOROLOGICAL Daily Chemical Intensity, Manchester, 1864 (continued). July 6th, 1864 (continued). Mean Temp. Dry bulb 17°-6. July 8th, 1864 (continued). Mean Temp. Dry bulb 19°-6. Barom, =765-3 millims. ,. Wet bulb 13 -4. Barom. =765*1 millims. ,, Wet bulb 13°-8. Chemical Chemical Amount Solar time. intensity of cloud. Sun’s disk. Solar time. intensity of cloud. Sun’s disk. of light. of light. b m h m 12 30 p.m. 0-22 3 Light clouds. 12 0 0-11 Clouded over. 1 0 0*21 6 „ 12 30 p.m. 0-13 9 Light clouds. 1 30 0-17 9 „ 1 10 0-15 7 „ 2 0 0*28 7 „ 1 40 0-16 2 30 0-36 7 „ 2 15 0-26 4 Unclouded. 3 0 0*15 „ 3 0 0-29 3 3 30 0-17 4 „ 3 30 0-26 „ 4 0 0-21 Unclouded. 4 0 0-22 4 30 0-24 4 Light clouds. 4 30 0-15 1 5 15 0-092 5 0 0-12 1 6 30 0-063 4 ” 6 10 0-011 ” July 7th, 1864. Mean Temp. Dry bulb 16°-4. July 9th, 1864. Mean Temp. Dry bulb 15°-5. Barom. = 764-7 millims. ” Wet bulb 13°-2. Barom. =764-1 millims. » Wet bulb ll°-7. 7 30 A.M. 0-040 10 Clouds above. 8 0 A.M. 0-060 O Hazy, 1 8 0 0-058 10 „ 9 0 0-15 8 30 0-10 10 „ 10 0 0-14 9 15 0-079 10 „ 11 0 0-18 Unclouded. 9 45 0-073 10 „ 12 20 p.m. 0-15 10 10 0-069 10 „ 1 30 0-23 „ 10 45 0-056 7 „ 2 30 0-22 11 30 0-020 7 „ 3 30 0-22 „ 12 0 0-055 9 „ 4 30 0-14 12 30 p.m. 0-021 10 „ 5 30 0-10 „ 1 0 1 45 0-12 0-064 9 „ 2 25 3 0 0-022 0-15 10 7 Light clouds. September 26th, 1864. | 3 30 4 0 0-092 0-070 Clouded over. 8 50 a.m. 0-11 Cloudless sky. 4 30 0-11 „ 9 25 0-13 5 0 0-10 Clouds. 10 0 0-070 99 7 20 0-025 10 30 11 0 11 30 0 071 0-11 0-12 99 1 July 8th, 1864.. Mean Temp. Dry bulb 19°-6. 99 99 Barom. =765-1 millims. Wet bulb 13°-8. 12 10 0-10 99 12 40 p.m. 0-11 99 7 10 A.M. 0-055 8 Clouded over. 1 5 0-15 99 7 50 0-068 7 Clouds. 1 55 0-17 99 8 25 0-089 9 „ 2 30 0-12 9 0 0-12 „ 3 0 0-096 9 30 0-12 „ 3 40 0-078 99 10 30 0-13 „ 4 10 0-056 99 ill 0 0-12 10 Clouded over. 4 45 0-038 99 11 30 0-13 ” 5 15 0-018 REGISTRATION OE THE CHEMICAL ACTION OF TOTAL DAYLIGHT. 631 Daily Chemical Intensity, Heidelberg, Dingwall, and Manchester, 1864. July 4, 1864. — Heidelberg. September 27, 1864. — Dingwall, N.B. (continued). Solar time. Chemical intensity of light. Amount of cloud. Sun’s disk. Solar time. Chemical intensity of light. Amount of cloud. Sun’s disk. h m h m 6 56 A.M. 0-072 Clouded. 10 23 A m. 0-22 Unclouded. 7 1 0-170 Unclouded. 10 30 0-18 Haze. 8 6 0-208 Clouds. 10 35 0-16 „ 8 21 0-206 Unclouded. 10 50 0-13 Cloud}-. 8 50 0-244 5? 11 25 0-16 Clouds. 9 21 0-290 „ 11 26 0-15 „ 9 40 0-394 2 „ 12 45 p.m. 0-24 Unclouded. 9 42 0-470 2 „ 2 37 0-19 „ 10 23 0-475 2 „ 2 45 0-13 Clouds. 10 35 0-590 2 ,, 2 58 0-18 Unclouded. 11 30 0-620 „ 3 57 0-066 Clouded. 11 49 0-60 12 18 p.m. 0-52 1 5 0-516 September 27, 1864. — Manchester. 2 21 0-248 Clouded. 3 5 0-300 Unclouded. 8 50 a.m. 0-13 Unclouded. 3 50 0-270 „ 9 30 0-16 4 30 0-126 Overclouded. 10 0 0-13 4 50 0-163 Unclouded. 10 40 0-18 5 25 0-124 0 ” 10 50 0-18 ” 11 30 0-13 y> September 27, 1864. — Dingwall, N.B. 12 0 0-098 Cloud. 12 40 p.m. 0-16 „ 9 16 A.M. 0-18 Unclouded. 1 10 0-13 „ 9 26 0-17 „ 1 40 0-17 „ 9 36 0-16 „ 2 10 0-14 10 0 0-17 „ 2 55 0-12 „ 10 5 0-19 „ 3 40 0-081 „ 10 10 0-19 ” 4 20 0 052 1 ” Fh£b. Irons. 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FLOWER ON THE CEREBRAL COMMISSURES Its fibres principally connect, across the middle line, the parts of the cerebral hemi- spheres forming the inner wall of the middle horn of the ventricle, especially the folded part constituting the hippocampus major. As its free edge forms the hinder boundary of the region called the “psalterium” in human anatomy, the fibres composing it may be distinguished as the “ psalterial fibres” of the corpus callosum. At a little distance behind and rather lower than the point of the rostrum of the corpus callosum, is the very distinct oval outline of the section of the white “anterior commissure” (F), and between this and the under surface of the corpus callosum, and prolonged into the con- cavity of the genu, is a portion of the inner wall of the hemisphere (G) closing the lateral ventricle towards the middle line, and with the corresponding portion of the opposite side forming the median septum which divides the two cavities from each other, as will be better seen in the transverse section. This important region Professor Huxley has distinguished as the “septal area”*. To return to the upper arched border of the ventricular aperture. The middle part, which when united to the corresponding portion of the other hemisphere constitutes the “ body of the fornix” (K), is composed of a considerable number of white fibres closely adherent posteriorly to the under surface of the body of the corpus callosum, and running in a longitudinal direction. Tracing these fibres forwards, a small round white cord (L) is seen to pass down from them behind the anterior commissure, constituting the part commonly spoken of as the “ anterior pillar ” of the fornix, but which, to avoid confusion, had better be designated as the “column” of the fornix ( Columna fornicis, Reichert). The further course of this into the corpus albicans and optic thalamus need not be detailed here. But a large portion of the fibres (I) running forwards from the body of the fornix do not pass down into these cords, being continued above the anterior commissure, and then curve downwards in front of that structure to join the inner wall of the anterior lobe of the hemisphere. For these fibres the name of “ precommissural fibres ” has been suggested by Professor Huxley. The presence of the precommissural fibres, as well as that of much grey matter, gives to the lower part of the septal area a much greater thickness than the upper part (to which the name of “ septum lucidum ” is applied) possesses. But the two divisions of the area are perfectly continuous in structure, the upper thin part also containing fibres prolonged from the fornix, radiating forwards and upwards to the under surface of the corpus callosumf . Posteriorly the fibres of the fornix, following the border of the aperture they encircle, change their longitudinal direction, and gradually turn outwards, downwards, and finally forwards, and even slightly inwards. Although in their anterior and middle portions the fibres of the fornix run at right angles with the fibres of the corpus callosum, this change of direction in their posterior part brings them parallel to, and allows them to blend with, the transverse fibres of that body. The prominent sharp free margin of the ventricular aperture formed by the “ posterior pillars ” of the fornix is called “ corpus fimbriatum ” * Lectures at the Royal College of Surgeons, Medical Times and Gazette, March 5th, 1864. t See Solly ‘ On the Human Brain,’ 2nd Edit. 1847, p. 261. OE THE MAESUPIALIA AND MONOTEEMATA. 635 (M). A little way external and parallel to this, on the surface of the hemisphere, is a deep sulcus, corresponding in direction and extent with the hinder third of the ventricular aperture. This is the “ dentate ” or “ hippocampal ” sulcus (Q). It terminates above under the posterior end of the corpus callosum. If the cortical grey matter of the hemi- sphere is traced from the external border of the hemisphere towards the ventricular aperture, it will be found to dip down into this sulcus, and rising again to the surface to terminate abruptly just external to the corpus fimbriatum. The free border in which it terminates, lying between the “ hippocampal sulcus ” and the “ corpus fimbriatum,” is called the “ fascia dentata ” (P), its surface being generally somewhat notched or indented at' intervals. The cerebral wall folded inwards at the sulcus just described, forms a cor- responding projection in the cavity of the ventricle called the “hippocampus major.” The relation of some of the parts above mentioned will be better understood by a reference to Plate XXXVI. fig. 2. It is drawn from a vertical transverse section of the human brain, at the point indicated by the line drawn across Plate XXXVI. fig. 1, viz., through the middle of the anterior commissure. B is the corpus callosum, passing from hemisphere to hemisphere, across the bottom of the great longitudinal fissure*. As its fibres pass outwards from the middle line, they curve slightly upwards before separating to radiate throughout the medullary substance of the hemispheres. Immediately under- neath the corpus callosum lie the cavities of the hemispheres or “ lateral ventricles,” com- pletely separated from each other in this section by a septum (G), attached above to the under surface of the corpus callosum, and below resting on the small transverse “anterior commissure” (F). This part, the “septal area” of the former section, may be demonstrated to consist throughout of two lateral portions, applied closely together in the middle line below, but in the upper part slightly separated, the interval constituting the fifth ventricle, or ventricle of the septum lucidum. The lower part of the septum, much thicker than the septum lucidum, contains the precommissural fibres of the fornix with much grey matter interposed. It seems never to have received any special name, or to have been sufficiently distinguished from the septum lucidum, although it is the most constant, and therefore important division of the septal area, as will be shown hereafter. The grey masses (B, R) forming the outer boundaries of the ventricles are the “ corpora striata.” The anterior commissure is seen as a small cylindrical bundle of white fibres (F) passing between the corpora striata. The true nature of these parts cannot be perfectly understood without a glance at their development. This is a subject confessedly still involved in some obscurity. I follow, however, the observations of F. Schmidt, who has given a detailed and apparently truthful account of the process^. Without entering into previous changes, it may be stated that each hemisphere consists, in a very early condition, of a hollow thin-walled body, with a fissure (O) in its inner surface, leading to the cavity within (Plate XXXVI. fig. 3, 1). * “ — the cross portion of white substance which lies between the hemispheres at the bottom of the longi- tudinal fissure,” Qttain and Shaepey’s ‘ Anatomy,’ 5th edit. vol. ii. p. 464. f Zeitschrift fur Wissenschaftliche Zoologie, vol. xi. (1861) p. 43. 4 S 2 636 ME. W. H. FLOWER ON THE CEREBRAL COMMISSURES Through this a portion of the pia mater (afterwards developed into the choroid plexus) enters. The fissure is at first perpendicular in direction. In front of it (at G) the two hemispheres are united across the middle line, immediately behind it (A) they are con- nected with the parts formed by the second cerebral vesicle, the subsequent optic thalamus and crus cerebri. The last-named point (the crus or “ hirnstiel”) forms a pivot around which the whole hemisphere curves itself as development proceeds. The fissure under- goes a corresponding change of form and direction. The anterior edge becomes its upper convex border. The upper end gradually becomes depressed until it is finally the lowest part, and the characteristic form of the ventricular aperture is already recog- nized at this early age (Plate XXXYI. fig. 3, III). The point of union between the hemispheres is still confined to the part immediately in front of the anterior end of the fissure, the “ septal area.” About this time the wall of the hemisphere commences to undergo a folding upon itself, producing certain definite grooves or sulci on the outer surface, and corresponding elevations upon the interior. At a very early period an arched sulcus (bogenfurche) appears parallel to the upper border of the fissure, marking off an arched convolution or gyrus between it and the fissure, the “ marginal arch” ( randbogen , Schmidt). It is the hinder part of this groove which afterwards forms the “hippocampal sulcus.” Into the further development of the convolutions and sulci it is unnecessary to enter. A more important subject in connexion with the present com- munication is the mode of formation of the corpus callosum, the fornix, and adjacent parts. Kolliker* has given so good an abridgement of Schmidt’s views, that I have thought it best to follow pretty closely his words. The convolutions of the hemispheres are distinctly seen from the third month to consist of two layers, an external with perpendicular fibres, which at a later period con- stitutes the grey or cortical substance of the convolutions, and an inner layer with fibres running horizontally. The fibres of the inner layer, constituting the medullary substance of the hemispheres, are found already in the third month, before the corpus callosum exists, to converge towards two points ; first, towards the crus ( hirnstiel , A), where they form the so-called stabJcranz ; and secondly, towards a point situated immediately above the place of union of the two hemispheres. This last arrangement of fibres is the first indication of the radiation of the corpus callosum ( balkenstrahlung ). It is at this spot (B) that in the fourth month the horizontal fibres break through the cortical substance and unite with the corresponding fibres of the opposite hemisphere. This is the commencement of the corpus callosum, which in its earliest form (see Plate XXXVI. fig. 3, IV) is a very small nearly cylindrical commissure, situated in the “marginal arch ” immediately above the most anterior part of the ventricular aperture. In order to indicate more closely the relation of the marginal arch to the corpus callo- sum, it is to be noticed that the former separates into two parts, a lower division imme- diately bordering the ventricular aperture, consisting only of horizontal or antero-pos- terior fibres, without the cortical layer, and an upper division possessing both layers. * Entwicklungsgeschichte des Menschen und der hoheren Thiere, p. 237, Leipzig 1861. OF THE MARSUPIALIA AND MONOTREMATA. 637 Now the corpus callosum breaks through just at the limit between these two divi- sions, and by its further growth backwards, the upper division comes to lie on its outer surface and is converted into the stria alba Lancisi and stria obtecta of the corpus cal- losum, and into the fascia dentata of the hippocampus major; whilst the inferior or inner arch, with its longitudinal fibres, forms the fornix and septum ( scheideivand ). The fornix is thus, as was known to Arnold and Retzius, a transformation of the upper margin of the transverse fissure. The lower margin of the fissure is formed into the taenia semicircularis or stria cornea, which, as is well known, is connected at each end with the extremities of the fornix. It will be seen from the preceding observations that the anterior perpendicular part of the fornix is originally united with the corresponding part of the other side, and the body of the fornix developes itself out of the uppermost part of this spot, adjoining the primitive corpus callosum. Lower down the parts sepa- rate and then resolve themselves into the columnae fornicis, or anterior crura, and the two halves of the septum lucidum, the ventricle of which is thus no primitive formation. In this part also originates, not by growing together from opposite sides, but by histological differentiation, the anterior commissure (F), which is evident a short time before the corpus callosum. The septum lucidum and body of the fornix, in the beginning very small, gradually increase in extent with the development of the corpus callosum. According to Schmidt, the opinion formerly entertained that the genu of the corpus callosum was the part first formed, and that the hinder part developed afterwards, is not correct. The rudimentary corpus callosum on its first appearance already contains the elements of all its subsequent parts, as from the very first, fibres radiate from it into the hinder and middle, as well as the anterior lobes, and the intimate connexion of the former with the posterior crura of the fornix can already be recognized. It increases, with the rest of the hemisphere, chiefly in longitudinal extent, spreading both backwards and forwards from the point of its first appearance, but principally in the former direc- tion. The curved part in front, called the genu, is not formed until the end of the fifth month, and about a month later, the thickening and extension of the hinder end over the corpora quadrigemina gives the permanent form to this part of the brain. I will next proceed to trace the modifications of the parts of the brain above indicated, in certain of the placental mammalia. The preparations from which the figures are taken were all made in the same manner as that adopted in the case of the human brain, viz., (I.) a vertical longitudinal section in the middle line, exhibiting the inner surface of a single (the right) hemisphere, the thalamus opticus and crus having been removed so as to show clearly the whole surface with the parts forming the upper boundary of the ventricular aperture; (II.) a vertical transverse section through the middle of the anterior commissure. The Sheep. — In the longitudinal section of the sheep’s brain (Plate XXXVII. fig. 1), the elongated narrow corpus callosum (B) is seen lying in a line nearly horizontal, or corresponding with the long axis of the hemisphere ; slightly concave in the middle 638 ME. W. H. FLO WEE ON THE CEEEBEAL COMMISSIJEES above, with a thickened posterior end (E) turned somewhat downwards, and a distinct genu (C) and rostrum (D) in front. The latter has a smaller proportional development than in the human brain. On the other hand, the slightly projecting posterior fold observed in the human corpus callosum is prolonged forwards as a thin layer of transverse fibres (N) arching across the under surface of the longitudinal fibres of the fornix, and ending in no abrupt edge in front. The difference in the form and extent of this part of the great transverse commissure may be clearly seen to depend upon the difference in the form, and more extensive proportions of the parts that have to be brought into rela- tion to each other by it, viz. those forming the inner wall of the descending cornu of the lateral ventricle. At a considerable distance below the anterior part of the corpus cal- losum the small anterior commissure (F) is seen, with the wide septal area (G) in front of and above it. The portion of this part to which the term “ septum lucidum ” can be applied, is reduced to a small strip beneath the anterior third of the corpus callosum, exactly defined below and in front by the extent of the rostrum of that body. The greater part of the septum is formed by a thick layer, consisting of a great development of the precommissural fibres of the fornix, associated with much grey matter. The small white column (L) of the fornix is seen passing down behind the anterior commissure. The ventricular aperture is less regularly curved than in man, being bent almost at a right angle. Above and behind it is seen a broad corpus fimbriatum (M), behind which the abrupt termination of the cortical substance of the hemisphere in the fascia dentata (P) is very distinctly seen. The regularly curved hippocampal sulcus (Q) ends beneath the hinder end of the corpus callosum, the grey matter of the fascia dentata being con- tinued superficially round its extremity into that of the next succeeding gyrus. In the transverse section (Plate XXXVII. fig. 2), at the bottom of the deep longitu- dinal fissure, is seen the corpus callosum (B), a transverse white band of moderate thick- ness, and slightly arched upwards externally, where its fibres radiate out in the medullary substance of the hemisphere. The anterior commissure (F) is readily recognized near the lower part of the section. The cavities of the lateral ventricles are somewhat tri- angular in form and bounded above by the under surface of the corpus callosum, towards the middle line by the septum, and externally by the corpora striata. The septum obviously consists of two halves, one belonging to each hemisphere, but more or less joined together in the middle line. The upper part (septum lucidum) is extremely thin, and here the absence of union between the two halves allows the existence of a minute cavity, the fifth ventricle. The lower and larger part is very thick, with rounded outer surface. It contains much grey matter, with white longitudinal fibres externally. Within it, near the middle line, on each side, can be seen two bundles of white fibres, standing nearly perpendicularly and slightly diverging from each other below ; they are the upper part of the columns of the fornix. The most essential deviations in the commissures of this brain from those of Man con- sist in the reduction of the rostrum of the corpus callosum and the septum lucidum, and the augmentation of the inferior thick part of the septal area and of the psalterial fibres. OF THE MARSTJPIALIA AND MONOTREMATA. 639 The Rabbit. — Plate XXXVII. fig. 3 represents the inner surface of the cerebral hemi- sphere of a rabbit. The corpus callosum (B) is no longer horizontal in its general direction, but, like the upper margin of the hemisphere, is elevated at the posterior end. In front it is slightly thickened, but the rostrum is scarcely perceptible. Although this commissure in its median section appears elongated from before backwards, it is very thin from above downwards. The inferior layer of transverse (psalterial) fibres are well developed, and, except posteriorly, distinct from the main part of the great transverse commissure. The septal area is large in extent. The anterior commissure is proportionally larger than in man or in the sheep. The hippocampal sulcus, corre- sponding with the large size of its internal projection into the ventricle, is deep, and prolonged for some distance beneath the hinder end of the corpus callosum. The hollow for the reception of the optic thalamus and corpora quadrigemina is very large, and the fascia dentata (P) lying in it very broad. The smooth inner wall of the hemisphere shows no other sulcus than that of the hippocampus. The transverse section (Plate XXXVII. fig. 4) shows the corpus collosum at the bottom of the longitudinal fissure, curving up at the two extremities, in consequence of the form of the lateral ventricles. The anterior commissure is of actual greater depth in the section than the corpus callosum. Between the two is the septum, now only represented by the thick lower portion, very considerably increased in develop- ment. The thin upper part, together with the fifth ventricle, has entirely disappeared with the rostrum of the corpus callosum. In the Two-toed Sloth ( Cholcepus didactylus), Plate XXXVII. fig. 5, the same parts can be recognized, though somewhat changed in proportions. As compared with the sheep especially, the whole hemisphere is greatly shortened in the antero-posterior direction, and a greater shortening still has taken place in the corpus callosum. Instead of bearing, as in the sheep, the proportion to the hemisphere of 53 to 100, it is but as 32 to 100. It rises at the posterior part, where it is slightly enlarged. The anterior end is simple and obtusely pointed, without a trace of the reflected rostrum. The anterior commissure is considerably larger, relatively to the hemisphere, than in the sheep. The ventricular aperture is nearly vertical in general direction. At the poste- rior edge of the body of the fornix there is a considerable thickening, caused by the transverse psalterial fibres of the corpus callosum. The hippocampal sulcus may be traced upwards to near the hinder end of the corpus callosum ; it then makes a sudden curve backwards, and almost immediately after another nearly equally sudden bend forwards, then arches over the end of the corpus callosum, and gradually approaching the upper surface of that body, at about its middle disappears in the lower margin of the callosal gyrus. Thus a thin portion of the dentate gyrus (fascia dentata) is continued over the hinder edge, on to the upper surface of the corpus callosum. In its principal part the gyrus itself is longitudinally grooved by a shallow sulcus, anterior and parallel to the hippocampal sulcus. The characteristic indentations are faintly indicated on the posterior edge. 640 ME. W. H. FLOWER ON THE CEREBRAL COMMISSURES The transverse section (Plate XXXVII. fig. 6) shows the corpus callosum curving up at the outer extremities owing to the upward development of the lateral ventricles, as in the rabbit, and in the foetal condition of the higher mammals. The corpora striata (K, K) are very large. The anterior commissure exceeds in vertical depth the corpus callosum. The septum, broad below where it rests on the anterior commissure, diminishes above to a narrow edge, where it touches the under surface of the corpus callosum; but there is no part which can properly be called septum lucidum. On each side of the middle line are seen the vertical white fibres, forming the commence- ment of the columns of the fornix. Plate XXXVII. figs. 7 & 8 are taken from the brain of the Common Hedgehog (Erinaceus europceus). The transition from the Sloth’s brain to this is easy, although it presents a wide difference from that of the Eabbit. The inner surface of the cerebrum shows no trace of any sulcus, except the deep one of the hippocampus (Q), which is placed very near the hinder border of the truncated hemisphere, and terminates a little way behind and below the posterior end of the corpus callosum. The last named body is extremely reduced in size, its length being but one fifth that of the entire hemisphere. Its obliquity is so much increased that its general direction is rather vertical than hori- zontal. The psalterial fibres form a distinct projection (N) in the section closer to the body of the corpus callosum than in the two previously described brains. The septal area is much reduced, and the anterior commissure increased in bulk. The great size of the olfactory ganglion is very remarkable. The transverse section shows a corresponding simplicity, and agrees in all its essential characters with that of the Sloth. The oblique position of the corpus callosum gives its section an apparent thickness, which it would not possess if divided, as in the higher mammals, at a right angle to the plane of its upper surface. These are examples of some of the modifications of the commissural apparatus of the cerebral hemispheres among the placental mammals. They might be considerably multi- plied, but they are sufficient for the purpose of affording a basis of comparison with the same parts in the Marsupials and Monotremes. Before entering upon this part of the subject, it may be desirable to give an outline of the present condition of knowledge upon it. A reference to the works of comparative anatomists who wrote before the year 1887, shows that up to that period no important distinction had been suspected to exist in the cerebral organization of the placental and the implacental mammals. In the Philosophical Transactions of that year, however, appeared the memoir of Professor Owen “ On the Structure of the Brain in Marsupial Animals,” in which was announced the absence in these animals, of the “ corpus callo- sum and septum lucidum.” A transverse commissure between the hemispheres superior to the anterior commissure is described, but called by Professor Owen “fornix” or “ hippocampal commissure.” Of this it is stated, “ This commissure may, nevertheless, be regarded as representing, besides the fornix, the rudimental commencement of the OP THE MAESUPI ALI A AND MONOTEEMATA. 641 corpus callosum; but this determination does not invalidate the fact that the great commissure which unites the supraventricular masses of the hemispheres in the Beaver and all other placentally developed Mammalia, and which exists in addition to the hippocampal commissure, is wanting in the brain of the Wombat: and as the same deficiency exists in the brain of the Great and Bush Kangaroos, the Vulpine Phalanger, the Ursine, and Mauge’s Dasyures, and the Virginian Opossum, it is most probably the characteristic of the marsupial division of Mammalia.” The relatively large size of the anterior commissure in the marsupials is referred to in the paper as worthy of notice, as also is the proportionally very large size of the hippocampi majores. The description given in this important memoir was subsequently reproduced in the Cyclopaedia of Anatomy and Physiology, art. Marsupialia, and it was shown that the same peculiarity also existed in the Monotremata, and therefore was characteristic of the whole implacental division. In the paper by the same author “ On the Characters, Principles of Division and Primary Groups of the Class Mammalia”*, the Subclass Ly encephala (“ loose” or “ disconnected” brain), equivalent to the Implacentalia, are characterized as having “ the cerebral hemispheres but feebly and partially connected together by the ‘ fornix’ and 4 anterior commissure,’ while in the rest of the class a part called ‘corpus callosum’ is added, which completes the connecting or commissural apparatus’^. The views of Professor Owen have been adopted without hesitation or qualification, in this country at least, and have been incorporated in almost every text- book on Anatomy and Physiology subsequently published. The same has been the case to a great extent upon the continent, and what is more important, they have received confirmation apparently from original dissections of several of the marsupials by the editors of the third edition of Cuvier’s ‘ Anatomie Comparee,’ MM. F. Cuvier and Laurillard (1844), and in the case of the Echidna by MM. Eydout and Laurent (Voyage de la Favorite, 1839). But expressions of dissent have also been raised. Leuret, speaking of the brain of * Proc. Linn. Soc. 1858. t [The necessity of doing full justice to the labours of one who has made this subject so peculiarly his own, will excuse my quoting the following succinct account of the distinctive characteristics of the views of this eminent anatomist, as set forth in his most recent publication bearing upon the question. “ In investigating and studying the value and application of the cerebral characters of Man in the classifica- tion of the Mammalia, I have been led to note the relations of equivalent modifications of cerebral structure to the extent of the groups of mammals respectively characterized by such conditions of brain. The Monotremes and Marsupials, which offer numerous extreme modifications of the limbs, all agree in possessing a brain in which there is no connecting or commissural mass of fibres overarching the lateral ventricles of the cerebrum. The surface of this part shows, however, a few symmetrical convolutions in Echidna and Macropus, especially the largest species ; but in the majority of marsupials the hemispheres are smooth. The £ corpus callosum,’ or great commissure, makes its appearance abruptly in the Eats, Shrews, Bats, and Sloths, which in general organization and powers are next the ‘ loose-brained ’ marsupials or Ly encephala : but this commissure is associated with a similarly smooth unconvolute cerebrum, and with so small a size of the cerebrum as leaves uncovered the cerebellum and in most the optic lobes.” — Contributions to the Natural History of the Anthropoid Apes, No. VIII., by Professor Owen, Trans. Zool. Soc. vol. v. part 4, 1865, p. 270. — April 1865.] MDCCCLXV. 4 T 642 MR. W. H. FLOWER ON THE CEREBRAL COMMISSURES the Kangaroo, says,* “ J’y ai vu bien manifestement nn corps calleux, situe entre les deux lobes cerebraux, comme chez les antres mammiferes.” Foville, in a note to p. 172 of his well-known treatise on the Nervous System (1844), says, “ M. de Blainville a toujours sontenu l’existence du corps calleux chez les didel- phes, et me l’a fait voir de la maniere la plus manifeste chez plusieurs de ces animaux. II a si peu de volume qu’on s’explique facilement comment on a pu croire a son absence.” F. J. C. MAYERf, speaking of the brain of the Common Opossum ( Didelphis virginiana), says, “Das corpus callosum betreffend, so ist dasselbe ebenfallsund namentlich bei Didel- phis vorhanden, nur schmal oder kurz, allerdings etwas schmaler oder kurzer, als bei den Nagern, allein noch kurzer ist das corpus callosum beim Igel [hedgehog] wo es ebenfalls nur ein vorderes schmales Markblatt bildet. Aber schon bei den Nagern treten der Eingang in den dritten Ventrikel und der Sehhiigel hinter dem corpus callosum zu Tage, am meisten aber bei dem Igel, und die Beutelthiere stehen nur zwischen beiden, den Nagern und dem Igel in der Mitte, und es ist somit im Gehirne derselben keine abwei- chende Organisation wahrzunehmen, welche mit der Geschlechtstheile etwa eine Parallele liefern konnte”$. The more detailed description of this structure in the brain of the same animal, given by Pappenheim § in language remarkable for its precision, deserves to be quoted in full, as it has received little attention from subsequent authors. It agrees in the main with the observations recorded in this paper. “ Mais je crois devoir m’occuper, avant tout, de la nature du corps calleux. C’est une opinion tres-repandue, que ce corps n’existe pas chez les Marsupiaux. Cependant les dessins et la description de M. Owen prouvent que ce corps a ete tres-bien vu par cet anatomiste habile ; mais que, d’un cote, il n’a pas reconnu sa marche entiere, et que, de l’autre, il a ete frappe par la situation de cette commissure, qu’il a consideree plutot comme un fornix (voute a trois piliers). Comme cet organe se trouve dessine en partie dans le paquet cachete que l’Academie a bien voulu me faire l’honneur d’accepter, je me bornerai aujourd’hui a signaler quelques faits qui, rapproches de mes observations anciennes, prouveront que le corps en question est bien un corps calleux. “ 1°. La commissure dont je parle est situee en avant des couches optiques, la ou leur * Anat. Comp, du Systeme Nerveux, t. i. p. 412 (1839). t Neue Untersuchungen aus dem Gebiete der Anatomie und Physiologie. Bonn, 1842, p. 24. t Professor Owen (Annals and Mag. Nat. Hist. vol. xvi. p. 101, 1845), in replying to Mater’s statement, says, “The great transverse band or commissure which unites the two hemispheres, spanning from one to the other above the lateral ventricle — which is plainly visible, as such, in the lowest Rodent or other placental mammal, with the smoothest, and, to outward appearance, simplest brain, — this great commissure or corpus callosum, I again affirm, after reiterated dissections, to be absent in all the known genera of Marsupials. If the narrow transverse hand, which unites together the hippocampi majores, at the front part of the fornix, be regarded, as I originally stated it might he, a rudiment of the ‘ corpus callosum,’ the comparative anatomist is at liberty to apply that name to it.” § “ Notice preliminaire sur 1’ anatomie du sarigue femelle ( Didelphis virginiana ),” Comptes Rendus, tom. xxiv. p. 186 (1847). OF THE MAESUPIALIA AND MONOTKEMATA. 643 premier developpement s’opere, au-dessus de la commissure anterieure du cerveau. Toutes ses fibres rayonnent au-dessus du corps strie, dans les hemispheres, ou elles se terminent en faisceaux paralleles aux fibres des pedoncules cerebraux. “ 2°. Elle s’allonge en avant dans un corps genouille, qui ne peut etre compare aux pedoncules du fornix, lesquels entrent dans les couches optiques, tandis que ce dernier corps rayonne dans les hemispheres. “ 3°. Les fibres de cette commissure sont purement transversales, direction qui n’a aucun rapport avec celles des fibres du fornix. “4°. Les fibres du fornix ne s’etalent jamais dans les parois des ventricules; aussi n’occupent-elles pas toute la longueur du ventricule lateral. “ Cette commissure n’est done ni un fornix, ni un melange du fornix avec le corps calleux. “ La partie posterieure est composee de fibres accumulees en un faisceau tres-epais, tandis que les fibres anterieures du corps calleux sont etalees dans une couche large, mais extremement mince et tellement transparente, que l’on voyait a travers le corps strie. Du reste, quand on ecartait les hemispheres, les fibres du corps calleux, etalees, se lais- saient detacher facilement de l’autre substance blanche, sous forme de feuillet mince, tapissant, pour ainsi dire, la paroi du ventricule lateral dans chaque hemisphere. “ Les hemispheres etaient composes d’une maniere tres-simple, savoir ; des fibres des pedoncules cerebraux, qui etaient les plus externes; des fibres de la commissure ante- rieure, en avant et en dedans, et d’un feuillet appartenant au corps calleux, situe en dedans du rayonnement des fibres du pedoncle ; tout autour, enfin, etait une couche corticale tres-epaisse et peut-etre plus considerable que toutes les fibres blanches.” Such are the main results of the researches of those anatomists to whom we are indebted for all that is known upon the cerebral commissure of the Implacental Mam- mals. I will next give an account of these structures as actually observed in several of the leading types of the group, and afterwards discuss the relation which the conclusions derived from the present examination (differing somewhat in method from those pre- viously used) bear to the opinions most generally received. Kangaroo. — Several specimens of the brains of both Macropus major and Macropus Bennettii have been examined. They agree so closely in all essential points that one description will suffice for either, unless otherwise specially stated. On looking at the upper surface of the brain (Plate XXXVI. fig. 4), the two hemi- spheres being partly separated, a transverse white band (B) is seen extending across the bottom of the longitudinal fissure, roofing over the anterior portion of the third ven- tricle, and occupying the same general position as the corpus callosum in the ordinary mammal, but developed to a smaller extent even than in the Hedgehog. In a brain of Macropus Bennettii it was found to cover, when still undisturbed by removal from the cranial cavity or contracted by spirit, about half the optic thalamus, and to measure from before backwards in the middle line, a quarter of an inch, or one-sixth of the entire 4 t 2 644 ME. W. H. FLOWEE ON THE CEEEBEAL COMMISSURES length of the hemisphere. It is situated deeply in the great longitudinal fissure, is thickened and most elevated posteriorly, where the margin, slightly and evenly concave, crosses the cavity of the third ventricle (S), the peduncles of the pineal gland (T), and the optic thalami (U). The anterior margin is also concave, but extremely narrow, the white substance being continued on each side of a longitudinal median cleft for some distance towards the front of the cerebral hemisphere, as if in this anterior part the two lateral halves of the commissure had not been joined together in the middle line. On close examination it is seen to be composed of fibres of which the general direction is transverse, but on its upper surface can be distinguished a longitudinal median raphe, and on each side of this a few longitudinal white fibres, corresponding to the “striee late- rales” of other mammals. On either side, the transverse fibres are lost beneath the overlapping grey matter constituting the margin of the convolution of the corpus callosum, the “labia cerebri” of some authors. To follow them further, the last named parts must be carefully removed with the handle of a scalpel or some similar instrument, when a delicate broad lamina formed by the lateral expansion of the narrow transverse band will come into view, passing at first horizontally outwards and then curving upwards above the precom- missural fibres of the fornix (I), the cavity of the lateral ventricle, and the corpus stri- atum (R), and finally losing themselves in the medullary substance of the upper part of the cerebral hemispheres. The fibres radiate extensively forwards and backwards but forming a continuous lamina, posteriorly conterminous with those on the surface of the hippocampus major, anteriorly becoming much more delicate, so much so, indeed, that it is not easy to make a complete dissection of them without causing some rents, like that on the left side shown in the figure, through which the cavity of the ventricle below is exposed. This expansion of the transverse commissure in the hemisphere, though described by Pappenheim in the Opossum, appears not to have been observed by Owen in any of his dissections. Plate XXXVIII. fig. 1 is a view of the inner surface of the right hemisphere of the Great Kangaroo. The hemisphere is short, and deep from above downwards, obtusely pointed in front and flattened or abruptly truncated behind. The temporal lobe is largely developed. Several well-marked sulci are seen upon the surface of the hemi- sphere. One of the most striking characteristics presented by this section is the great development of the anterior commissure (F), far exceeding that seen in any placental mammal. The form of its section is oval, with the long diameter nearly vertical, or inclining slightly forwards at the upper end. It consists of firm, white, transverse fibres, distinctly defined from the surrounding part, and forms a good landmark to the adjoining structures, as about its homologies there can be no ques- tion. At a very short distance above this is seen the section of the median part of that transverse band before described (B). This is oval, elongated from before back- wards, slightly arched on its upper border. Its anterior and posterior extremities are rounded, the former is the narrowest. To the under surface of the latter, a body of OP THE MARSTJPIALIA AND MONOTREMATA. 645 transverse fibres (N), almost equal in size to the upper portion of the commissure, is intimately united. Beneath the anterior part of this, close to the middle line, a distinct white cylindrical band of fibres is seen to pass down, behind and in close con- tact with the anterior commissure, at first directed somewhat backwards and afterwards downwards until it loses itself in the thalamus opticus. This evidently answers to one of the columns of the fornix, its position being somewhat disturbed by the immense deve- lopment of the anterior commissure. Between the superior transverse commissure (by which name I propose for the present to call the part marked B) and the anterior com- missure are some fibres continued forwards from above the anterior end of the ventri- cular aperture, and mixed in this region with much grey matter, forming the greatly reduced septal area (G). They curve forwards and downwards, encircling the anterior half of the anterior commissure, and represent, doubtless, those designated as “ precom- missural ” fibres in the higher mammals. The ventricular aperture is seen to occupy its ordinary position. Its upper margin is formed by the edge of a broad white band, corpus fimbriatum (M). On tracing this band forwards, it is found to be continuous with the hinder edge of the whole of the upper transverse commissure. The superficial grey layer (P) external to the corpus fimbriatum is readily recognized as the fascia den- tata. This is bounded on the outer side by the hippocampal sulcus ; but in respect to this sulcus a great peculiarity presents itself. On tracing it forwards, instead of stop- ping short beneath the projecting posterior rounded end of the corpus callosum, as in most, if not all placental mammals *, it is continued on, passing over the top in close contact with the upper transverse commissure, and is not lost until it reaches the inner surface of the anterior lobe, considerably in advance of both the upper and anterior commissures. The remarkable disposition of this sulcus must be particularly noted in reference to the nature of the commissure in close relation with it. In the transverse section (Plate XXXVIII. fig. 2) the immense size of the anterior commissure (F) is as conspicuously seen as in the longitudinal section. It occupies one-fourth of the whole height of the brain in the middle line. Its fibres spread them- selves outwards, the lower ones sweeping first slightly downwards, then curving up into the white medullary substance of the middle of the hemisphere. The higher fibres, taking a course more directly upwards, penetrate the grey matter of the corpora striata (R R), which they here divide into two distinct masses, and finally reach the medullary substance of the upper part of the hemisphere. Lying immediately upon the anterior commissure, close to the median line, are two bodies, which, taken together, present a surface broad from side to side, slightly concave above, nearly flat below, and rounded off at the outer inferior angles. These consist mostly of grey substance, with some white fibres, especially collected into two bands close to the median line (the roots of the columns of the fornix). These bodies are the two lateral halves of the very much thickened and depressed ventricular septum. Below they are in contact with the anterior commissure, on each side with the cavity of the lateral ventricle, above with a white * A partial exception was shown in the Two-toed Slotln 646 ME. W. H. ELOWEE ON THE CEEEBEAL COMMISSUEES transverse band. This band, lying at the bottom of the great longitudinal fissure of the cerebrum, is the one previously mentioned as the superior transverse commissure. Traced outwards, its fibres, spreading into an extremely thin layer, form the upper and inner boundary of the superior portion of the lateral ventricle. They have a regular curve, outwards, upwards, and finally inwards, losing themselves in the medullary sub- stance of the hemisphere at its upper and inner angle. Their internal concave border is in contact with a fold of cortical grey matter, surrounding a deeply penetrating sulcus, which from the very bottom of the longitudinal fissure runs outwards and then upwards in the hemisphere, and which, as shown in the previous section, is continuous with the hippocampal sulcus in the posterior part of the hemisphere. The lateral ventricle, as seen in this section, is prolonged to a considerable height in the hemisphere, but other- wise its relations are similar to those of the same part in the placental mammals. Figs. 3 & 4, Plate XXXVIII. are taken from the brain of the Wombat ( Phascolomys vombatus). In general form the cerebral hemispheres are more depressed and elongated than those of the Kangaroo, and the temporal lobe obtains a comparatively slight development. Corresponding with this general elongation, the ventricular aperture and the surrounding parts have a wider curve backwards. The essential characters are, however, precisely the same. The anterior commissure attains an equal magnitude. The superior transverse commissure has the same form and relations, and the con- tinuation of the hippocampal sulcus extends above it, though it is not prolonged to quite the same extent on the anterior lobe. Seen in transverse section, the septum is narrower from side to side. The large carnivorous Marsupial, the Thylacine ( Thylacinus cynocephalus), so widely separated in external characters from both the Kangaroo and Wombat, shows the same general peculiarities of cerebral organization, but attended with a smaller development of the superior transverse commissure, especially of its anterior part, and a greater reduc- tion of the thickness of the interventricular septum (see Plate XXXVIII. figs. 5 & 6). Dissections of the brains of Phalangista vulpina and of Didelphis virginiana have yielded similar results, so that it may be presumed that the principle upon which the cerebral commissures are arranged is uniform throughout the Marsupial Order. Of the two genera of Monotremes, I have only had the opportunity of dissecting the brain of one, the Echidna. This most remarkable brain, with its largely developed and richly convoluted hemispheres, conforms in the main with the Marsupial type in the disposition of the commissures, but in detail presents a still further deviation from the ordinary mammalian form. As seen in Plate XXXVIII. fig. 7, the anterior commissure is as large relatively as in the Marsupials. Above it is seen the section of the superior transverse commissure, very much reduced in extent, and in which the two portions, upper and lower, observed in the Kangaroo are no longer distinguishable. Its relations to the hippocampal sulcus, to the ventricular aperture, to the columns of the fornix, to the precommissural fibres, and to the lateral ventricles are however the same, so that whatever parts of the placental mammalian brain are represented by this commis- OF THE MABSUPIALIA AND MOXOTREMATA. 647 sure in the Kangaroo, are also represented by it, though in a reduced degree, in the Echidna. Perhaps the greatest change is in the extreme reduction of the septum, as best seen in the transverse section (Plate XXXVIII. fig. 8). In dissecting the brain from above, the fibres of the superior commissure are found to spread out into a delicate layer roofing in the ventricles quite to the anterior part of the hemisphere, as described in the Kangaroo. Having described the actual condition of an important and well-marked region of the cerebrum in several members of the two great groups of the Mammalia, it now remains to trace out the relation that the several structures entering into the formation of this region bear to one another in each of the two groups. It will be necessary also to inquire how far the results brought out by the present method of examination are in accordance with the views generally received. At the outset a distinct confirmation is afforded by the dissections recorded in this paper, of the great fact, first observed by Professor Owen, that the brains of animals of the orders Marsupialia and Monotremata present certain special and peculiar characters, by which they may be at once distinguished from those of other mammals. The appear- ance of either a transverse or longitudinal section would leave no doubt whatever as to which group the brain belonged. In the differentiating characters to be enumerated, some members of the higher section present a considerable approximation to the lower ; but, as far as is known at present, there is still an interval between them unconnected by any intermediate link. The differences are manifold, but all have a certain relation to, and even a partial dependence on, each other. They may be enumerated under the following heads : — 1. The peculiar arrangement of the folding of the inner wall of the cerebral hemi- sphere. A deep fissure, with corresponding projection within, is continued forwards from the hippocampal fissure, almost the whole length of the inner wall. In other words, the hippocampus major, instead of being confined as it is, at least in the higher forms of placental mammals, to the middle or descending cornu of the lateral ventricle, extends up into the body of the ventricle, constituting its inner wall. 2. The altered relation (consequent upon this disposition of the inner wall) and the very small development of the upper transverse commissural fibres (corpus callosum). 3. The great increase fin amount, and probably in function, of the inferior set of transverse commissural fibres (anterior commissure). These propositions must now be considered a little more closely. Arguing from our knowledge of the development of the brain in placental mammals (for of that of the marsupials we have at present no information), it may be supposed that the first- named is also first in order of time in the gradual evolution of the cerebral structures. Before any trace of the budding out of the fibres which shoot across the chasm sepa- rating the two hollow sac-like hemispheres, before the differentiation of a portion of the 648 MR. W. H. FLOWER ON THE CEREBRAL COMMISSURES septal area into the anterior commissure, that remarkable folding of the inner wall, indi- cated by the deep furrow on the surface and the corresponding rounded projection in the interior, has already become distinctly manifest, and the future form of the ventri- cular cavity, with its elevations and depressions, has been sketched out. Now the first rudiment of the upper transverse commissure is found undoubtedly at the spot after- wards situated near its middle — that part to which in the lowest placental mammals it is almost entirely confined. This spot is situated a little way above and in front of the anterior end of the ventricular aperture, at the upper edge of the region of adherence of the two hemispheres (the future septal area). In the placental mammals this part is in direct relation to the great mass of the internal medullary substance of the hemispheres, which have to be brought into communication. In the Marsupial, on the other hand, the prolonged internal convolution or hippocampus extending up to and beyond this part, forms the inner wall of the hemisphere from which the fibres pass across, and it is necessarily through the medium of this convolution, and following the circuitous course of its relief in the ventricle, that the upper part of the hemisphere alone can be brought into connexion. Can this transverse commissure, of which the relation is so disturbed by the dispo- sition of the inner wall of the hemisphere, be regarded as homologous with the entire corpus callosum of the placental mammals 1 or is it, as has been suggested by Professor Owen, to be looked upon as only representing the psalterial fibres or transverse com- missure of the hippocampi'? Undoubtedly a large proportion of its fibres do come under the latter category. But even if they should nominally be all so included, it is important to bear in mind that we have still a disposition in the marsupial brain very different from that which would remain in the brain of any placental mammal after the upper and main part of the corpus callosum had been cut away. In the latter case the commissure of a very small part of the inner wall of the hemisphere alone is left, that part folded into the hippocampus. In the former there is a commissure, feeble it may be, but radiating over the whole of the inner wall, from its most anterior to its posterior limits. Granted that only the psalterial fibres are represented in the upper commissure of the marsupial brain, why should the name of “ corpus callosum ” be refused to it 1 These fibres are part of the great system of transverse fibres bringing the two hemi- spheres into connexion with each other ; they are inseparably mingled at the points of contact with the fibres of the main body of the corpus callosum, and are only separated from it in consequence of the peculiar form of the special portions of the hemisphere they unite. Indeed, as mentioned before, they are not more distinct than is the part called “ rostrum ” in front. And although they blend at each extremity with the fibres of the diverging posterior crura of the fornix, they certainly cannot be in any sense confounded with that body, the essential character of which is that it is a longitudinal commissure consisting of two halves closely applied in the middle, but each composed of fibres belonging to a single hemisphere only. But is the main part of the corpus callosum of the placental mammal not also repre- OF THE MAKSUPIALIA AND MONOTEEMATA. 649 sented by the upper and anterior part of the transverse band passing between the hemi- spheres of the marsupial brain 1 The most important and indeed crucial test in deter- mining this question, is its position in regard to the septum ventriculorum, and especially the precommissural fibres of the fornix. Without any doubt in all marsupial and monotreme animals examined (sufficient to enable us to affirm without much hesitation that it is the character common to all) it lies above them, as distinctly seen in the trans- verse sections. Moreover, passing outwards into the hemispheres, it overarches or forms the roof of the lateral ventricles of the cerebrum. This is precisely the same relation- ship as that which occurs in Man and all other mammalia. The defective proportions of the part representing the great transverse commissure of the placental mammal, which appears to me to result from, or, at all events, to be related to the peculiar conformation of the wall of the hemisphere, must not lead to the inference that the great medullary masses of the two halves of the cerebrum are by any means “disconnected.” The want of the upper fibres is compensated for in a remarkable manner by the immense size of the anterior commissure, the fibres of which are seen radiating into all parts of the interior of the hemisphere. There can be little doubt but that the development of this commissure is, in a certain measure, comple- mentary to that of the corpus callosum. That it is not simply correspondent with the large size of the olfactory ganglion, as Professor Owen has suggested, is shown by the fact that in the Hedgehog and some other placental mammals this ganglion attains a far greater proportionate volume than in many marsupials, and yet the commissure is very considerably smaller. In descending the series from Man to the Placental Mammals of lowest cerebral organization, the great change in the condition of the corpus callosum has been seen to be, the disappearance of the rostral portion, and the coincident greater development of the posterior folded or psalterial portion ; the latter being connected with the relative increase of the hippocampal region of the cerebrum. In the brain of the marsupial a change of precisely the same nature is carried to an excess. There is, however, as far as my observations show, no structure characteristic of the higher group which is absent in the lower. The step from the marsupial or monotreme brain to that of an animal belonging to one of the lower vertebrate classes is very great. Indeed it is difficult to see in many of the peculiarities of their brain even an approach in the direction of that of the bird. We may allow that the diminution of the volume of the corpus callosum leads on to its entire absence ; but in the great development of the anterior commissure is presented a special characteristic of the lowest group of mammalia, most remarkable because it is entirely lost in the next step of descent in the vertebrate classes. The same may be said of the cerebral folding constituting the hippocampus major. Plate XXXVI. figs. 5 & 6 are views of the brain of a Goose, corresponding to those given of the various mammals. The smooth, thin, inner wall has no trace of that folding upon itself which gives rise to the hippocampus major in the mammal. In this respect mdccclxv. 4 u 650 MR. W. H. FLOWER ON THE CEREBRAL COMMISSURES there is a vast difference from the brain of the marsupial. The ventricular aperture (0 0) is extremely reduced. Its upper border may be properly compared to the fornix, and the thickened part of the inner wall (G), above and in front of the small anterior com- missure (F), evidently corresponds to the lower part of the septal area and precommissural fibres, as well seen in the transverse section. The walls of the hemispheres are in close apposition at this part, as the two lateral halves of the septum are in the mammals; but a distinct band of fibres passing across the middle line from one hemisphere to the other, above the anterior commissure, has never yet been satisfactorily demonstrated. The homology of the minute and delicate transverse lamella of nerve-substance, described by A. Meckel as situated above the ventricular aperture posterior to the anterior commis- sure, is very questionable. Great as is the difference between the placental and implacental mammal in the mode and extent of the connexion between the two lateral hemispheres of the cerebrum, it is not to be compared with that which obtains between the latter and the oviparous verte- brate. Description op the Plates. All, except fig. 3, Plate XXXVI., are from original dissections. For convenience of comparison the cerebral hemispheres are reduced to the same absolute length. PLATE XXXVI. Fig. 1. Inner surface of the right cerebral hemisphere, Human brain. Fig. 2. Vertical transverse section (through the anterior commissure), Human brain. Fig. 3. Development of the Human brain (after F. Schmidt). I. Sixth week. II. Eighth week. III. Tenth week. IV. Sixteenth week. V. Sixth month. Fig. 4. Brain of Kangaroo ( Macropus Bennettii) dissected from above, natural size. A portion of the extremely delicate great transverse commissure (B) has been removed on the left side to show the structures lying beneath it. Fig. 5. Brain of Goose. Inner surface of right hemisphere. Fig. 6. Brain of Goose. Vertical transverse section. PLATE XXXVII. Fig. 1. Brain of Sheep. Inner surface of cerebral hemisphere. Fig. 2. Brain of Sheep. Vertical transverse section. Figs. 3 & 4. Brain of Rabbit. Figs. 5 & 6. Brain of Sloth ( Cholcepus didactylus). Figs. 7 & 8. Brain of Hedgehog (Erinaceus europceus). OF THE MARSUPIALIA AND MONOTREMATA. 651 PLATE XXXVIII. Figs. 1 & 2. Brain of Kangaroo ( Macropus major). Figs. 3 & 4. Brain of Wombat ( Phascolomys vombatus). Figs. 5 & 6. Brain of Thylacine ( Thylacinus cynocephalus). Figs. 7 & 8. Brain of Echidna ( Echidna hystrix). Explanation of the Letters used in all the Figures. A. Crus cerebri, divided between thalamus opticus and corpus striatum. B. Body of corpus callosum. C. Genu of corpus callosum. D. Rostrum of corpus callosum. E. Splenium of corpus callosum. F. Anterior commissure. G. Septal area. H. Septum lucidum. I. Precommissural fibres. K. Body of fornix. L. Columns of fornix. M. Corpus fimbriatum. Edge of posterior crura of fornix. N. Psalterial fibres of corpus callosum. O. Ventricular aperture. P. Fascia dentata. Q. Hippocampal sulcus. R. Corpus striatum. S. Third ventricle. T. Peduncles of pineal body. U. Thalamus opticus. V. Corpora quadrigemina. Bub. Tig Tig. 3. WS1 ?. ad.-nat. 3 eL ( wMpt/lv). 3) EdmaM.WEams.I’.L.S. Sc. Bui. Trane. MDOOCI ^T.BLaJx,7£mi. ^g-2. Fig. 4. Fig. 6. Kg. 8. HTH.T. adaiat. dA. IEc3wiiiM.T,BIli£aiis,P.L.S. Sc. Fh£U. Trane. MDCCCEXF. Rales WX HL Tig.Z. Tig'. 4 Tig. 6. Tig.7. 'VOTE: SLti.Tiab. deL Ectmia M.TOEa:mslT'JJ.S. 8c. [ 653 ] XIV. On the Sextactic Points of a Plane Curve. By William Spottiswoode, M.A., F.B.S., &c. Received June 15, — Read June 15, 1865. The beautiful equation given by Professor Cayley (Proceedings of the Royal Society, vol. xiii. p. 553) for determining the sextactic points of a plane curve, and deduced, as I understand, by the method of his memoir “ On the Conic of Five-pointic Contact ” (Philosophical Transactions, vol. cxlix. p. 371), led me to inquire how far the formulae of my own memoir “ On the Contact of Curves ” (Philosophical Transactions, vol. clvii. p. 41) were applicable to the present problem. The formulae in question are briefly as follows : If U=0 be the equation of the curve, H=0 that of its Hessian, and V =(a, b, c,f g, h)(x, y, zf= 0 that of the conic of five-pointic contact ; and if, moreover, a, /3, y being arbitrary constants, b=ux-\-fiy-\-yz, □ = (y^U - U)d, + («B,U -- yBJJ)^ + (,3d,U - «d,U)b2, J ' then, writing as usual BJJ=w, bJJ=w; ^H=^, B,H=r, ^i=vlw1—u'2, . . Jf=v'w'—u1u', . . vy — w(3=X, wot — uy—gj, u\ 3 — vu—», the values of the ratios a : b : c :f : g : h are determined by the equations v=o, □ v=o, □2v=o, □3v=o, n4v=o. . . . Now, if at the point in question the curvature of U be such that a sixth consecutive point lies on the conic V, the point is called a sextactic point ; and the condition for this will be (in terms of the above formulse) □5Y=0. From the six equations Y=0, □ Y=0, . . D5Y=0, the quantities a , b, c, f, g , h can be linearly eliminated; and the result will be an equation which, when combined with U = 0, will determine the ratios x:y:z, the coordinates of the sextactic points of U. But the equation so derived con- tains (beside other extraneous factors) the indeterminate quantities a, (3, y, to the degree 15, which consequently remain to be eliminated. Instead therefore of pro- ceeding as above, I eliminate a, (3, y beforehand, in such a way that (W=0 repre- senting any one of the series Y=0, □V=0, . . from which a, (3, y have been already mdccclxv. 4 x (1) (2) (3) 654 ME. W. SPOTTISWOODE ON THE SEXTACTIC POINTS OF A PLANE CURVE. eliminated) the equations W= 0, □ W = 0, □ 2W = 0 are replaced by ^W==VV=BfW = AW (4) where ts is a numerical factor, and a=(b, & c, #, e, ** (5) To this preliminary transformation the first section of the paper is devoted *. The second section contains the actual elimination of the constants of the conic, and the reduction of the resultant to six forms, 3£=0, JH=:0, =j^,=0, %!= 0, JH'=0, of which % and 01 and 4jW, and ffl! differ respectively only by one and the same numerical factor, viz. (n— 2)3. All these forms, however, contain extraneous factors, the determination of which is the object of the remainder of the paper. The third section is devoted to the establishment of some formulae of reduction, the demonstra- tions of which are rather too long to be conveniently inserted in what would otherwise be their more natural place (§ 4). Besides these I have established many others of a like nature ; but the specimens here given will doubtless suffice to suggest the mode of proof of the rest to any one desirous of pursuing the subject further. In the fourth section it is shown that all six forms are divisible by the Hessian of U, and that %, %! are also divisible by u3, 01, 0\! by v3, and by w3, and that the result of these divisions is a single expression of the degree Yin— 27. § 1. Preliminary Transformation. The first two equations of the system (3) are, as is well known, equivalent to the following, viz. U V w (6) where 0 is indeterminate. The third equation, viz. □2V=0, when written in full, is o= □?a,v+ n^y+ □^zy+x2h2y+^2y+^2Y+2(p^,y+ABAV+^^v). (7) Noww being the degree of U, we may without difficulty establish the following formulae given by Cayley (Z. c. p. 381) : (n—l)u2=—$$z2-\-lJfzy—&y2, (n—l)v2 = — €x2-j-2(Bxz— Qz2, (n—l)w2=— %2 +■ 2^yx — B#2, (n— 1 )vw = — $x2 — zx, (n— 1 )vw= — fzx—=(a, b, c,f, g, h)(u, (3, y)2, we may derive (n-l)X2 =-^ + 2 to(Zlu-hW+y)-x2A =— + Jf/3 + Cy)+^(S a +H/3+#y)— (w — 1 )Kfb = — h2$ + fy(&a + W + 7 ) + Ml «+Bf3+Jy)— But, as will be found on calculating the expressions, (n— l)DX=^(9[a + ^/3 + #y)— x$>, 1 (n— l)DiM-=^0|a+B^+4fy)— y®, 1 (n—l)Uv =&(#a+4f/3-|-Cy)--:s< I>, J so that (w-l)2X2 =-^a+2(w-i>nx+^, (n—lfgJ1 = — §2^3 + 2(w— l)yn(A-\-y2®, (n— 1)V = — £2C + 2(w— l)z CH -|-z2, (w— l)2p =— &tf+(n— l){yUv +znp)+yz, (n—Yfvk =— h20-\-(n— l)(z Wk-\-xnv)-\-zxQ, (n-l)\gj = —l2$l+(n—l)(x Dp+y □ x)+^. , Hence, if m be the degree of V, (9) • (10) (11) (12) (^-i)2{A2B2y+iy/b2y+v2B2v+2(pB^2y+^3,Y+^^y)} = -S2(<3, 33, C, f, 0, l)a, 3„ B JV+2(%-l)(m-l)(n^,V+ D^V+ D^2V), whence, substituting in (7), and bearing in mind that (n— 1)S1w+D + ^w)=H^, 1 (n—l)^u+Mv+fw)=B.y, i (13) (n— l)#M+Jfy + Cw)=H2, j we have (»- 1 )! (i +2ar) ( □ *3,v+ □ j»a,v+ O -3.-V) - 8*(a, Ji.i.jr. 6, ® )(3„ 3,, a,)5v= o. But □ aV + □ i«aV + □aV=^(wDX+'yD1M/+^(;Dv) = ,7^1 ( (&u + D + + (Ifou + 33fl + fw)(3 + {<&u + tfv + €w)y } 4x2 656 ME. W. SPOTTSWOODE ON THE SEXTACTIC POINTS OE A PLANE CURVE, so that (7) finally takes the forms (a wB,y)=^B> ^v- wB,v)=^s a(v zzv- w^v) ] ^B>^y-MB,y)=^y(wB,v-MBzv)=:^,(wB,v-w5,y)=^|IA(wb,v-wS,y) . ldz(u dyV-v *.V)=\b,(u t, JfV)=^« dyV—v dzV) A(« B,V). (20) 658 ME. W. SPOTTISW OODE ON THE SEXTACTIC POINTS OF A PLANE CUEVE. 2 (n j =8. Also since BZV, B^V, BZV are But since W is of the degree n, ^,=1 + linear in x, y, z, it follows that AB,Y=0, AB^Y = 0, ABzV=0; hence, applying the formulae (17), (18), AflB,Y=£d,V+2(a. • JT. • )« Vi, W)(dJdzV, B„B,V, B*V). But since 9lw' + %)vt + 0u!= 0, + (Bu' = H, Bw' -\- Jfrv1 + Cm' = 0, it follows that Similarly, so that (20) become A«B,V=2B,V+2HB,B,V. AwB,y=rB,V+2Hd„B,V, qdzY—rdpY ■■ 3H :YT< 3H fBzY — v' B^Y+2^ —2wh)= . . rBzV— pBzV= =— («/ BZY— w1BzV+2wa— 2ug)= . . _pByV-jB#V=^(«1BfV-w,d#V+2«^-2m)= . . , whence, multiplying by p, q, r respectively, and adding, we have 0 = p ux B*Y +2 JP 2 w' a,v , (22) b P u 2a— 6u =0; 2 V 2 h—6w' r w 2 y— to' u a v h w g (23) takes the form vr—wq=X , wp—ur= Y, uq—vp=Z , w.X+w'Y+t/ Z=P w'X+^j Y+w' Z=Q «/X-f«i' Y-j-w1Z=R, ] 2(aX+AY+yZ)-4P=0; (21) (22) (23) (24) or finally substituting 2 (ax-\-hy -\-gz)=6u, and forming similar equations in Q and R, we have the system a(uK—x P ) + h(u Y — yP ) +g(uZ — zP ) = 0 k(vX— xQ) -j- b(v Y — y Q) -f- g(v Z — zQ) = 0 g(wX—x R) +f(wY — yR) + c(wZ — sR) = 0, (25) ME. W. SPOTTISWOODE ON THE SEXTACTIC POINTS OE A PLANE CTJEVE. 659 which may be regarded as the three forms by any one of which □3Y=0 may be replaced. Before proceeding farther, it will be convenient to notice that the quanti- ties uX— #P, . . are capable of being transformed in a manner which will be useful hereafter, as follows : — TlX = Xuxx + (ww' — vv')jjx -\-(v'q— w'r)ux =Xu1x + ( ww ' — vv’)( 3n—2ll—qg—rz)—(v'q— w'r)(vy — wz) = Xfax + w'y + v'z) + 3 (n — 2)H (ww' — vv') =(n—l)uX-\-3(n—2)~H.(ww'—vv'), i. e. — uX+x¥=(n— 2){uX— 3H(W — ww')} 1 -wY+^P=(w-2){mY-3H(ww1-W )} l (26) — vJL -\-z¥=(n— 2){uZ — ■3H(W — vux )}. J Returning to (25), and taking any one of the three as W, we shall have for □3V=0, □ 4V=0, □5V=0, a~bJ(uX Kbx(uY —yF)-\-gdx(uZ — ^P) — 02u =0 1 ddy(uX-xF)-\-liby(uY—yF)-{-gby(uZ—zV) — 02v =0 | adz(uX—xV)-\-Jidz(uY—yV)-\-g'bs:(uZ—zF)— 02w =0 a A (uX — x~P) + A A(wY — yP) + gA(uZ-zT) - ^11= 0 ; , and similar groups may be formed from the other two equations of (25). Now as (27) contain only three out of the six constants a, . . fx . . , and the single indeterminate A,, they are sufficient for the elimination in view, and give for the equation whereby the sextactic points are to be determined, B,(mX-^P) B/«*Y-yP) B>Z-zP) a, d>X-tfP) B/*Y-yP) B/wZ— zP) u =0, j i B>X-#P) B/uY-yP) c)z(uZ—zP) w r J> 1 % A(WY-yP) A(uZ-zF) „2H i which, in virtue of (26), may also be written in the form (^{wX— 3H)w/— vow')} 'bx{uY—‘YSi(wul—uv')} B*{>Z— 3H(W— vux)} dy{wX— 3H)W— ww')} 'by{uY—oH.(wul—uv')} ~by{uZ— 3H(W— vuj} BJ.{wX— 3PI)W— ww’)} Bz{wY— 3H(«nq — uv ')-} ~bz{uZ— 3H(W— vux)} A{wX— 3H)W— ww1)} A{wY— 3H(mq— uv')} A{uZ— 3H(W— vux)} =0, v w G3r2H with similar expressions in v, Q ; w, R. Calling (28) and (29) %, %' respectively,' we may designate the entire group of six forms, three of the form (28), and three of the form (29) by 1=0, ifl=0, #=0, 31' =0, iH'=0, $,=0. (30) 660 ME. W. SPOTTISWOODE ON THE SEXTACTIC POINTS OF A PLANE CUEYE. And as %, differ only in respect of a numerical factor, any other factor that can be predicated of % may he affirmed of %!, and vice versd ; and similarly for the other pairs § 3. Formula? of Reduction. The degree of the expressions (28) or (29) is 18w— 36; it remains to show that existence of certain extraneous factors, which when divided out will reduce the degree to 12 n — 27, and at the same time render the three forms identical. But before entering upon this, it will be convenient to premise the following formulae, the first group of which are easily verified. y7j —zY =3(w— 2)Hm 1 zX—x Z = 3(n— 2)Hy xY-yX=3(n-2)Hw ybxZ — zB^Y — (3n—7)up—(n—l)wp -\-3{n—2)FLux ydyTi —zdyY =(3n—7)uq ~{n — 1 )vp -\-3{n— 2)Hw' y~bzZ — zdeY =(3n—7)ur -(w-l)wp+3(rc-2)IR/ zbxX-x'bxZ =(3n—7)v]) -(n-l)uq + 3(n-2)Hw' ^ zbyX.—x'byZ =(3n—7)vq — ( n — 1 )vq +3 (n — 2)11?;, zB2X— x'dJZ =(3n—7)vr —(n—l)wq-\-3(n—2)11u! x~b^Y —ybzX=(3n—7),wp—{n—\)ur -\-3{n— 2)HV x~by Y —ydfL =(3n-7)wq—(n—l)vr-\-3(n— 2 )Hu' #B2Y —ydzX=(3n—7)wr — (n—l)wr + 3(n—2)Hw,. > And writing -P1=^>I+Yr'+Z2' | -Q-Xr' +Yq1 + Zf (32) — R^X#' + Yf-^-Zr^ j then also Y^Z-Zd,Y=-(i?P+wP1) ZB.X-XB^-feP+flPJ XB2Y — YB ^X = — (rP + wP, ) 1 YByZ-ZbyY=-(i?Q-fwQ1) ZB.X-XB^-^Q+uQ,) XB^-YB^-^Q+wQ,) 1(38) YB2Z-ZB2Y=-(^R+wR,) Zh2X— XBzZ= — (g'R+'yRj) XB2Y-YB2X=-(rR+wR1)J Moreover, writing with Professor Cayley, (& b, c, jr, 0, i)(B„ b„ hz)2H=o 3$, C, f, 0, fc)(B„ B„ B.ft, B yQjj= . . , BsQy= . . BA=(B,a B,£, B2c, Bjf, dx0, BJ>)(B„ B„ dJH, B,Qh= • • ME. W. SPOTTISWOODE ON THE SEXTACTIC POINTS OE A PLANE CIIEYE. 661 and noticing that X-dj-Ou-}-!! ByQu-{-/3zQu — Jac. (U, H, Qu), . . . (35) and that AX= vdzQv—wds O0 1 AY -wdx£lv- dd., OrJ 1 AZ = wd^Qu— wb^Ou, | . . . (36) then we have YAZ -Z AY —u Jac. (U, H, tjAZ -z AY=(5w-12)Qm 1 Z AX— XAZ s=v Jac. (U, H, Qn) zAX-xAZ =(5n-l2)Qv i. . (37) XAY— YAX=w Jac. (U, H, QD) ®AY— yAX=(5»-12)Qw.' I Again, if 33', C', 4F, 0', be the same quantities with respect to H that 3, 33, C, jf, 0, are with respect to U, i. e. if Q!=qlrl— p'2, . . jfl=q'r'—plp', . . , and if ©=($', 33', C', f, 0', H')(w> wf ] _ ^ ^=(& 33, C, f, 0, H)(ih q , r)2, then Uy c^Z=Jac. ( u , Yr, Z,)=w, if p — ux r + wpx — uqf w' ^Z w' dp—w'r-\-wif —up1 if dzY dsZ «/ Wy p—v' r-\-wq' —urx =Hp2 — Hp2 — Qpu + (%{p j + $|r' + 0#' )pu — (!?*' +33^1 +Jfp')pw + (11^1+33/ + Jfy' )pv +(<®Pi+$rr' +€q')wp +(0^i+ + CV )ww -(02' +4^ +Cr» )pt* +(91'mi +Hfw'+0V)w2 + (H'^i+33V+ f'v')uv +(Hih + 33/ +jf2/)jw +(0Pi +4^ 4-C^' +(&'%, +^V + 0V)m2 +(H'wi+35 V -j-ffi'v'juv + (0'w i + 4f V + C )mt? Similarly, Jac. (w, Z, X)=wt ■w/p+wr' — w'r—v1 q-\-vq’ — wr' ■y' w' ^ — dp + up' —vq' dr — Wjy-f- Wj — wp1 4 Y MDCCCLXV. 662 ME. W. SPOTTISWOODE ON THE SEXTACTIC POINTS OF A PLANE CUEVE. =Hjpff 3^ 7 = — Op — (0/ + + <&p’)up — H pq — Qpv + $t>d,0D + %| — (<%' + Jfjp' + Cr, )vp — 0fyr' +36#, +$p')uq \udy"tyv + (W +ffql +€/ )wp —(<3r' +fqx +Cy )ur -(W +33$'i +tfp')uq + (9'Mj +^'w'+(B'v')uv + (#i>i +4^ +C^ )w +(fe+^' +4^ >2 + (3^'te, +2SV + fv'y + (&ut +4fV +CV)w Hence • -(r +(9^ +{W + +(#/ +4f2i+Cp')wp +($P1 +(?%L+23/ +4^')^ +(%i+ JV +C£')n> Jac. («, Y, Z)=%^Hp! -(Qi)-ia,©u)M Jac. («, Z, X)=i£=f> Hp?-(Qp-i3.,0o>+J«9^„-iM9,^u Jac. (w, X, Y)=4^’i_12) Hpi — (Qp — ja,0„)w+iw3t'I,n— 4 (72 — 2) Jac. («, Y, H#p— (Gj— J9y0u)«+^B,^u— Jac.(t>, Z,X)=i^Hf-(O2-i3,0„)» l . (39) Jac. (v, X, Y )=~~ H(?r— (O^— 4(n~2) 1 Jac. (tv, Y, Z)=-^rr; Hrp-(Qr-pz0u>+i^^u-iw^u Jac. (w, Z, X)=^rHi-2-(Q,— p,0„)*+i«3,^„-iw3,^o Jac. (w, X , Y)=^|^Hr! -(Qr-|a,0,)w. Again, •r Jac. 0, Y, Z)+?/ Jac. (v, Y, Z)+z Jac. (w, Y, Z)=(»— 1) Jac. (U, Y, 7) ; whence, bearing in mind that ^»+?3,^u+*3.^o=2(3»- 7)¥„, ^*0o+y3»0tI+23,©„=2(K-l)0u, ME. W. SPOTTISW OODE ON THE SEXTACTIC POINTS OF A PLANE CTTEVE. 663 because in the differentiations £5, . . . SI', . . are supposed constant, it follows that Jac. (U, Y, ] Again, 12 (n Jac. (U, 3 n — 7 3(n — i Jac. (U, X, Y)=^ Mi d*Y ~dxZ=ux w' ByY a,z «/ i/ d2Y s2z (40) =^2H —(%rr +43?! +Jfp')wp +(<3'u1+$r,w'+€lv')wu +(®p, +#/ +C?')wp+($'w1 +?I)V +<§V)w2 — ((Bq1 +fj>'+^rl)uj) +(W?L+4$V +4fW)w> +(li>i+43r' +#?>?> . . JT, . .)(**, v, w){u„ w', v')u. Whence Jac. (u, Y, Z)=^£^ Hp2 -O Mp + (g', . . jf', . .)(««, w)(%„ w', v')u Jac. (m, Z, X)=^^ Hp?-1%+(ST, . . 4f', . .)(«, v , w)(«/, w> Jac. (m, X, Y)=^^ Hpr-Qwr +(3', . . jf', . .)(«, «, w)(®*, < w>. (41) A similar process of reduction conducts to the relation Jac. (X, Y, Z)=— (A, . . f, . .)(p, q, r)(p„ r', ?')X— (£', . . f:. . .)(u, v, w)(u„ w\ t/)X — (3, • • S, • -)(JP» A* r)(^ )Y— ($', . . JT, . .)(w, V, w)(w\ w')Y —(SI, . . JT, . •)(?> ^)(?',i>', )Z— (S', . . jT, . .)(«*, «, w)(+ w,)z = — Jac. (U, H, ^u)— Jac. (U, H, ©„). Whence also Jac. (wX, %Y, u7i)=v? Jac. (X, Y, Z)+w2{X Jac. (w, Y, Z)+Y Jac. (X, u, Z)+Z Jac. (X, Y, u)\ = -w3Jac.(U, H, ^D). 4 y 2 664 MB. W. SPOTTISWOODE ON THE SEXTACTIC POINTS OF A PLANE CURVE. $4. The resultant equation which, when combined with that of the original curve, will determine the sextactic points, was exhibited in § 2 under six different forms, there designated by 1=0, iH=0, #=0, £'=0, iW=0, #=0. Now since % and %!, i'H and XW, iX and -ffij respectively differ only by the numerical factor (n— 2)3, we shall, in seeking to discover the extraneous factors, employ either S., . . or ■%!, . . as most convenient for the purpose. And in the first place it will be shown that H is a factor of all these expressions. Putting H=0, %! becomes oxuX bxuY bxuZ u — 0 ; byuY byuZ • v ....... (43) bzuX bzuY bzuZ w A uX AuY AuZ gt2H also AwX=j)X+mAX+2HB#X I AmY=jpY+wAY+2HB,Y (44) AuZ =pZ -\-uAZ +2HdxZ ; | so that the above equation, written in full, is uYX +wb^X UjY -f-wdxY w,Z -\-ubxZ u w'X +wb?X w'Y +mc^Y w'Z -f- ubyZ v v’X+ubzX v'Y +ubzY . v'Z+nbzZ iv p X +uAX+2HbxX p Y +mAY+2HBxY p Z +uAZ + 2llbxZ ar2H. Although this expression contains terms explicitly multiplied by H, which might on the present supposition be omitted, it will still perhaps be worth while to develope it completely. Expanding in the usual way, it becomes u*X ux <3,Y bJZ u +w2Y ul bJZ bxX u +u2 Z u, bxX bxY u +u3 bxX bxY bxZ u V) ' b,Y byZ V W' byZ ^ ,X V ^ b,X V d,X b y Y V v' bzY bzZ w v' bzZ bzX w v' bzX bzY w bzX bzY bzZ w p AY AZ *t2H p AZ AX st2H p AX AY sr2Ii AX AY AZ +H u^X-\-ub^X MjY+wB^Y u{L-\-iib^L u w'X+wc^X w’Y+ubyY w'Z-\-ubyZ v P X + wbzX v'Y-\-ubzY v'Z-\-ubzZ w 2 b,X 2bxY ' 2bxZ sr2. ME. W. SPOTTIS WOODE ON THE SEXTACTIC POINTS OF A PLANE CUEVE. 665 In this the coefficient of — p =±{d„X Zb,Y-Yd,Z u +B,Y X^Z-Z^X u +d„Z Y^X-X^Y u) ^X Z^Y-Y^Z v d,Y Xd,Z-Zd,X v ~byZ Y^X-Xd.Y v d,X Zb.Y—Y'dJZ w b,Y X^Z-Z^X w ~dzZ Yd*X-X^Y w =±{p'bxK+qdieY+rdxZ P u +udxK+v'bxY+w'd;Z P, u}= P, P u pbyK+qbyY +rdyZ Q v ubyX-\-vb^-\-wbyZ Q, v Qt Q v jpdzX-j-^dzY-j-rdzZ R w ub^X-\-vbzY -\-wbzZ R, w R, R w. Now « «. P, = ^I{2(»P,+SQ,+4rEl)-y(1gP,+jrQ,+CE1)} v w' Q, w t/ R, « »' P.=^{*(@P,+4fQ,+CE1)-z(aP,+®Q,+®R,)} V v , Q, w v! R, « »' P. = ~ i{y(aP,+®Q1+©R1)-*(®PI+33Q1+JrK,)} w id Q, w ro, R, ; so that multiplying these equations by X, Y, Z respectively, and adding, » P P, =^T{(aP,+BQ, + ©E,)(yZ-2Y) » QQi +(lP1+SQ,+JrE1)(zX-xZ) w R R, +(eP,+^Q,+CK,X«Y-yX)} = 3tx2> H { a»+®» + ®ro)P, + ( J) « +33» + Jfw)Q, + (i6k+ jfo + C»)E, } = f^H’fp-*+9'?+E-*) = ~ vi(i"r ^(Xp+Yg+Zr) (45) = 0. 666 MR. W. SPOTTISWOODE ON THE SEXTACTIC POINTS OE A PLANE CURVE. Hence the whole expression =zz2{zz, zz YB,Z-ZB,Y B^+zz, zz ZB.X-XB.Z B^Y+zz, zz XB.Y-Y B,X B,Z} w' v YB,Z-ZB,Y B,X w' v ZB.X-XB.Z ByY zy' v XB,Y-YB,,X B,Z V1 w YBaZ-ZB*Y B*X v' w ZB2X-XB2Z B*Y v' w XB, Y-YB*X B*Z . W.2H YAZ-ZAY AX . st2H ZAX-XAZ AY . sr2H XAY-YAX AZ -fzz3B;X B*Y B,Z u B,X B^Y B,Z v* B2X B2Y B2Z zy AX AY AZ tir2H ; or in virtue of (33), — ZZ2{ZZ, ZZ — (^P+ZzP,) B^X+zz, zz -(jP+yPJ B^Y+zz, zz — (rP+zyPj) 3.Z} zy' y — (pQ+zzQ,) ByX zy' v — (ffQ+yQi) B,Y zy' y — (rQ+zyQ,) 3,Z y' zy — (^zR+zzR,) B2X y' zy — (^R+yR,) B2Y y' zy — (rR+zyR,) 3,Z w2H zz Jac.(U, H,Ou) AX . et2Hz; Jac.(U,H, Oy) AY . ®2Hro Jac. (U, H, 00) AZ +zz3B.,X B*Y B,Z zz B^X B^Y ByZ v B,X B2Y B2Z zy AX AY AZ *t2H =2zz2ot2H zzj Pj P+zz2Jac. (U, H, Q^zz, zz P +zz2 Jac. (U, H, Ou) zz, zz P+zz3B*X B2Y B,Z zz zy' Q, Q zy' v Q zy' v Q B^X B^Y B^Z z; z;' Ej R y' zy R y' w R B,X B2Y B2Z w AX AY AZ kt2H. But *1 P. P=Z(lP1+BQI+4TPi)-Y((gP1+4fQ1+CB1) zy' Q, Q y' R, R =zz(a 33 C jf # i?)0 2 r)(P1Q1R1)-^(9[ 33 € f 0 Mu v ^XP.Q.R,) =«(a 33 c # e Mp 2 rXPABi), (a 33 C jr <§ £)(«. y, «)P1Q1RI)= J^TH(P1af+Q1y+B1*)=0, (a 33 c jr - (a . .)(? ? ^ »•' , -(w-2)(3HK+5P>, _(w_2)(3HK+5P> respectively ; and consequently the whole expression = — (w — 2)(3HK-f-5P2) { (^>X— A#P -f 2Hb^X)% +Q>Y-AyP+2Hd#Y)t> +(_pZ - As P + 2Hd,Z )w + ^2HP } = -(?*— 2)(3HK + 5P2){—2HP—2(a. .)(«, % w)(b,P, byP, B,P)-f-«raHP} = _(„_2)(3HK+5P){-2-^=S+-!}HP. 2) But ro-2=l-f- — * so that above expression =(rc-2)(3HK + P2)HP. Now -(w-2)(3HK+P2)=w u p a,p byp v w n\J w' v' (n—l)(u—u) q r , ‘6{n— 2)H 5(w— 2)P. u w xu -\-yv -\-zw w' v' xut -\-yvo' -\-zv' p q r xp -\-yq -\-zr b,P ByP BJP a?a.P+yBrP+*a,P = — (n — 1 )u u p b^P v q dyP w r d,P : —u u i-l> • (48) so that the whole expression is divisible by u. Similarly, it might be shown that M, or M' is divisible by v, and N or N' by w. It follows from what has gone before that %, are all divisible by H, that %, are divisible by u, iPT by v, by w, and consequently dividing ME. W. SPOTTIS W OODE ON THE SEXTACTIC POINTS OE A PLANE CURVE. 669 out those factors, the three expressions %, JB, ^ are of the form Am2 +B,w +C1=0,| Kv2 +B2v + C2=0,1 (49) Aw2-fiB3w+C3=0,j in which the coefficients of u2, v2, w2 are the same, viz. the expressions given in (46). From these equations it follows that BjW + Cj B2W + C2 BgW -f Cg ~77 7 77 • { } But as u, v, w do not in general vanish simultaneously, these relations can hold good only in virtue of B, being divisible by ux and C, by u2 ; B2 by v, and C2 by v2 ; B3 by w and C3 by w2. Whence, finally, % is divisible by H u3, JB by Hw3, ^ by Hw3; and yhe degree of the equation is reduced to (18»-36)-3(»-2)-3(»-l)=12»-27. Also, since the ratios (B^+Cj) : u2, (B2-y+C2) : v2, (B3w+C3) : w2 are in virtue of (50) equal (say =B), it follows that JB, %!, JB', all lead to the same result, viz. A+B=0, which it was our object to prove. 4 z MDCCCLXV. ’ [ 671 ] XV. On the Marsupial Pouches , Mammary Glands , and Mammary Foetus of the Echidna Hystrix. By Professor Owen, F.B.S., &c. Beceived February 18, — Bead March 2, 1865. In the year 1834* it was known that the ovum of the Ornithorhynchus paradoxus left the ovarium with a spherical yelk or vitellus about If' (lines) in diameter, and that, having reached the uterine portion of the oviduct, it had acquired a smooth subtransparent chorion or outer tunic separated from the proper membrana vitelli by a clear fluid. Such ova, usually two in number, had been detected in females killed in the month of October, in the left uterus, of sizes ranging from to 3^"' (lines) in diameter, without any sign of organization of the chorion, or of preparation for placental adhesion on the uterine wall. The increase of size in the uterine over the ripe ovarian ovum was due to increase of fluid between the chorion and vitelline tunics. This fluid, homologous with the albumen of the egg of oviparous vertebrates, did not coagulate in alcohol, and the only change presented by the vitellus of the largest observed ovum was a separation from the “ food-yelk ” of a “ germ-yelk ” in the form of a stratum of very minute granules, adhering to part of the membrana vitelli. There was no trace of decidua in such impregnated uteri ; the smooth chorion was firmer than that of uterine ova of Bodentia ; whence, and for other reasons given in the paper above cited, it was inferred “ that the Monotremata are essentially ovo-viviparous.” In the same year (1834) I received a young of the Ornithorhynchus paradoxus from a nest of that animal, discovered by Lieut, the Hon. Lauderdale Maule in the banks of the “ Fish Fiver,” Australia. This progeny, Plate XLI. fig. 5, measured in a straight line about 2 inches (other admeasurements will be subsequently given) ; it was naked, blind, with short, broad, flexible, and softly labiate mandibles ; the tongue was proportionally large, and reached to near the end of the mandibles ; the mouth was not round, as in the mammary foetus of marsupials, but in the form of a wide transverse slit ; a pair of small nostrils («) opened upon the upper mandible, and between them was a small prominence ( e ), resembling the knob on the beak of the newly-hatched chick, but softer, and lacking the cuticle which had been torn off. There was no trace of navel or umbilical cicatrix f. The mouth of this young Platypus, or Ornithorhynchus , was adapted to be applied to the flat teatless areola upon which the numerous lactiferous ducts of the parent opened J, * “ On the Ova of the Ornithorhynchus paradoxus ,” Philosophical Transactions, vol. cxxiv. p. 555. t “ On the Young of the Ornithorhynchus paradoxus,” Zoological Transactions, vol. i. p. 221. X “ On the Mammary Glands of the Ornithorhynchus paradoxus,” Philosophical Transactions, vol. cxxli. p. 517. MDCCCLXV. 5 A 672 PROFESSOR OWEN ON THE MARSUPIAL POUCHES, MAMMARY GLANDS, and it was inferred that thus it received the lacteal nourishment with the aid of the com- pressor muscle of the large mammary gland. The principal points in the generation of the Monotremata which remained to be determined by actual observation were — 1st. The manner of copulation. 2nd. The period of gestation. 3rd. The nature and succession of the temporary structures developed for the support of the foetus during gestation. 4th. The exact size, condition, and powers of the young at the time of birth. 5th. The period during which the young requires the lacteal nourishment. 6th. The age at which the animal attains its full size. “ Notes ” of these desired facts, with indications of the times and places most likely to supply them, have been sent by me far and wide, through Australia and Tasmania ; and after the lapse of thirty years, I have been favoured with materials for making some further advance in this interesting physiological problem — a small one, it is true, but such as seemed to me worthy of being submitted to the Society as an addition to former records on the subject contained in the Philosophical Transactions. For these materials I am indebted to my friend the accomplished botanist, Dr. Fer- dinand Mueller, F.R.S., of Melbourne, Australia. They consist of a female Echidna ( Ornithorhynchus Hystrix of Home, Echidna Hystrix of Cuvier, the “Porcupine Ant- eater” of the colonists) and her young one, or one of her young, which was observed, as the captor supposed, suspended to a nipple when the animal was first secured. After five days’ confinement the young was found detached and dead, was put into a bottle of spirits, and, with the mother still living, was transmitted from “Colac Forest,” Victoria, the place of capture, to Melbourne. Here the female Echidna was examined by Dr. Mueller and Dr. Rudall of Melbourne, and was then transmitted to me, together with the young animal, and the following “ Notes” of their dissection. “ Brief Notes on the Generative Apparatus of the female Echidna. “ The animal being excessively difficult to handle it was immersed in cold water, and by these means and the additional use of hydrocyanic acid its life was extinguished. A longitudinal incision was made from the orifice of the cloaca upwards to the length of about 5 inches. Five larger and some smaller ovules were found arranged in a grape- like manner, the largest measuring from l1" to If' ” [lines] “ in diameter. Fine vessels expanded reticularly over the surface of the ovules. We vainly endeavoured to trace an opening at the ovarian end of the oviduct. Oviduct about 2" ” [inches] “ long ; its upper extremity expanded and attached to the ovarium. As a probable sign of recent functional activity, were noted a number of large distended veins lying between the layers of the peri- toneum. Numerous oval mesenteric glands were seen. ‘ Meatus urinarius ’ lying in the inferior wall of the cloaca about f from the orifice. The ureter terminates in a con- spicuous conical protuberance from 3'" to 4'" long. No other exit for the urine from the AND MAMMAET FCETUS OF THE ECHIDNA HYSTRIX. 673 bladder being found but the point into which this conical protuberance fits, the ingress and egress of the urine, as far as we believe, takes place at the same aperture. In close proximity, and lateral to it, the oviducts terminate by slit-like openings. The mucous membrane of the thick walls of the oviducts are, at least in the lower portion, longitudi- nally folded. The oviducts are suddenly narrowed for about from the lower orifice, offering some resistance to the passage of an ordinary sized probe. “The upper portion of the oviduct seems of a structure capable of considerable ex- pansion during gestation. The upper portion was dilated and thin, and a probe could be passed to near one of the ova. The lower portion of the rectum is so large and so capable of distension as to admit of the periodical inclusion of the young animal, in case its great size should possibly be provided for that purpose, as it is a receptacle large enough for a young animal twice the size of that found now with the mother. The foetal young may possibly have been extruded prematurely after the capture of the animal. We found no cicatrix of an umbilical cord on the abdomen of the young animal. ^ “A rough sketch of the young as seen by us is appended (fig. 1). It was of a pale colour* ; no apertures for the eyes were yet visible in the skin, nor were any tegumentary appendages formed. The finder contends that he saw the young external to the mother and alive. We purposely abstained from the internal examination of the young one, so as not to mutilate the only specimen available. The four mammary glands at this time are apparently quite rudimentary ; they are destitute of nipples, as are those of the Orni- thorhynchus. N or was there the least appearance of milk in these glands. From the imperfect means of judging we had, we incline to the opinion that Young Echidna, the Echidna cannot be oviparous. (Signed) “ James T. Rudall. “ Feed. Mueller.” “ Melbourne, August 25, 1864.” On receiving the specimens I proceeded to examine the female Echidna, and was gra- tified by finding unmistakeable evidences of marsupial structure. On each side of the abdominal integument, about two inches in advance of the cloaca, and about three inches and a half from the base of the tail, there was a semilunar pouch, with an aperture lon- gitudinal and directed towards the median line, half an inch in depth and two-thirds of an inch in length of aperture, forming a symmetrical pair with their orifices opposite each other (Plate XXXIX. a, b). These pouches were not at first apparent, being concealed by the hair which covers the under part of the body. It was in turning over this hair in quest of any rudiment of nipple, that I came, to my surprise, upon one of the pouches. The first doubt was whether it might have been produced by an accidental pressure of the end of a thumb or finger in the previous dissection of the animal, which depression had afterwards got hardened in the spirit ; and to solve that doubt I proceeded to examine the opposite half * “ Said originally to be bright red. — F. M.” 5 A 2 674 PROFESSOR OWEN ON THE MARSUPIAL POUCHES, MAMMARY GLANDS, of the ventral integument, when a pouch or inverted fold of precisely similar shape, depth, and dimensions appeared, but with the opening turned the opposite way ; the folds were closer and less conspicuous on that side, the cavity of the pouch being flatter (see section, Plate XL. fig. 3), whence I inferred that the more open pouch (ib. section, fig. 2, c) had been the seat or nest of the very small and probably recently-born animal, whose position there, as in the figure, Plate XXXIX. a , had naturally led the original captor of the Echidna to conclude that it was hanging by a nipple. No such projection, however, presented itself in any part of the inner surface of either pouch ; but at the fundus of each was an “ areola ” or elliptic surface, about four lines in diameter (Plate XL. fig. 4), on which, with the pocket lens, could be discerned the orifices of about fifty ducts of a gland. The canals or roots of fine scattered hairs and several minute white papillae (ib. fig. 5,^?, p, magn.), about one or two lines apart, on which opened sebaceous follicles, were all the appearances characterizing the otherwise smooth and even surface of these inflexions of the abdominal integument. The contrast which this pouch presents with that of a true marsupial quadruped con- taining the mammary foetus* is great; for even in the uniparous species, e. g., the larger Kangaroos, two, if not four, long slender nipples are conspicuous, to one of which the foetus hangs, closely embracing the pendulous extremity of the nipple by its small, round, terminal, tubular mouth. My next step was to test the statement in reference to the number and condition of the mammary glands. I found, as in a former dissection of a younger unimpregnated female Echidnaf , that these glands were two in number, forming, like the pouches, a symmetrical pair (Plate XL. fig. 1). Each gland (a, a!) was of a flattened, subelliptic form ; the left (a) being 1 inch 10| lines, the right (a!) 1 inch 8^ lines in long diameter, the left 1 inch 5 lines, the right 1 inch 3 lines in short diameter across the middle, and both glands about 5 lines in thickness at the middle part (figs. 2, 3). Each gland consists of about 100 long, narrow, flattened lobes, obtusely rounded at their free ends, and beginning, at about half- way towards the opposite side, to contract gradually to the duct which penetrates the corium (Plate XL. figs. 2 & 3, 5), to terminate on the mammary areola (ib. c ) at the fun- dus of the pouch. From the small size of the areola compared with that of the gland, the lobules have a convergent arrangement thereto, each terminating in its own duct, without blending with the substance of a contiguous lobe ; and, as a general rule, with- out anastomosis of contiguous ducts to form a common canal. Each gland is enclosed in a loose capsule of cellular tissue (fig. 1, e, e) and lies between a thick “ panniculus car- nosus” (figs. 1, 2, 3, d, d1), adherent to the abdominal integument (f,f) and the “ obli- quus externus abdominis ” muscle, on a plane exterior or “ lateral ” to the pouch. The glands had not been exposed or disturbed by any dissection in the preliminary examina- * For the signification of this term see “On the Generation of the Marsupial Animals,” Philosophical Trans- actions, vol. cxxiv. p. 333. f “On the Mammary Glands of the Ornithorhynchus ,” Phil. Trans., tom. cit. p. 537, PI. XYII. figs. 2 & 3. AND MAMMARY FCETUS OR THE ECHIDNA HYSTRIX. 675 tion of the animal at Melbourne. The lobules of each gland converge toward the mesial line, in their course to terminate in the fundus of the pouch. Each lobe is a solid parenchymatous body ; the duct is more directly continued from a canal which may be traced about halfway toward the fundus of the lobule; the canal gives otf numerous short branches from its circumference, which subdivide and terminate in clusters of sub- spherical “ acini ” or secerning cellules. The structure is on the same general plan as that of the mammary glands in higher mammals, but the cellules are proportionally larger ; it closely resembles the structure of the lobes of the same glands hi the Orni- thorhynchus, and in neither Monotreme can the elongated lobes be properly termed “pyriform cgecal pouches.” The converging termination of the lacteal ducts at the fundus of a pouch, or inverted fold of the skin, resembles the disposition of those parts in the Cetacea ; save that here the ducts terminate on a prominence or nipple projecting from the fundus of the pouch into its cavity ; whilst in the Echidna they terminate in the smooth and even concave surface of the fundus of the pouch. Calling to mind Mi'. Morgan’s observation of the concealed nipple in an inverted sac of the tegument at the fundus of the pouch in the young or non-breeding Kangaroo, where, instead of a nipple, there was seen only “ a minute circular aperture, resembling in appearance the mouth of a follicle” *, I made sections of both the marsupial or mammary pouches and glands (Plate XL. figs. 2 & 3) satisfactorily demonstrating that no inverted or concealed nipple or any rudiment or beginning of such existed ; and, indeed, had any such arrangement like that of the Kangaroo been characteristic of the mam- mary organization of the Echidna, the glands being functionally active and well deve- loped in the female dissected, such nipple would have been everted, and would have served, as the first observer of the young animal in the pouch believed, to have attached and suspended it to the parent. But it is evident that the young simply nestles itself within the marsupial fossa, clinging, it may be, by its precocious claws to the skin or hairs of that part, and im- bibing by its broad, slit-shaped mouth the nutritious secretion as it is pressed by the muscles acting upon the gland from the areolar outlets of the ducts. The skin of the abdomen, where it begins to be inverted, loses thickness, and at the fundus of the pouch (ib. fig. 1, b, fig. 3, c) is only half as thick as where it overspreads the abdomen (ib. fig. 1 ,f). This modification, and the relation of the pouches to the mammary glands, prove the structures shown in Plate XXXIX. a, b , and Plate XL. figs. 2 & 3, c, to be natural, not accidental. The pair of lateral folds or clefts into the bottom of which the lacteal ducts open, in the Echidna are homologous with those similarly related to the mammary glands in Cetaceans, and also to the more developed folds or pouches in Marsupials. In Ceta- ceans the pair of tegumentary clefts have exclusive functional relations to the mam- mary organ ; in Marsupials the superadded office of receiving and protecting the young * “ A Description of the Mammary Organs of the Kangaroo,” Linn. Trans., vol. xvi. p. 62, pi. 2. fig. 1, 5. 676 PROFESSOR OWEN ON THE MARSUPIAL POUCHES, MAMMARY GLANDS, is associated with so great a development of the inverted tegumentary fold, as to make the mammary relation seem a very subordinate and reduced one. But in the Marsu- pial series there is a gradation ; and both in Thylacinus and in the small dorsigerous Opossums of South America ( Didel'phys dorsigera, D. murina , D. pusilla , &c.), the mar- supial structure, if shown at all, is represented by a pair of shallow semilunar fossse, with their concave outlets opposite to each other, as in Echidna. In this comparison the distinctive peculiarity of the parts in the terrestrial Mono- treme is the absence of a teat, or of any rudiment of such : no part of the fundus of the pouch is again everted, produced, or folded about the terminal ducts of the mammary gland, so as to form a pedicle by which the young could take hold with the mouth, and so suspend itself and suck. The question remains, whether the marsupial pouches of the Echidna increase with the growth of the young 1 It is certain that they commence with the growth or enlargement of the mammary glands preliminary to birth. In that young specimen of female Echidna in which the glands were first discovered*, their ducts opened upon a plane surface of the abdominal integument. In a nearly full-grown unimpregnated female, preserved in spirits, which I examined and com- pared with the breeding mother here described, there is also a total absence of inflected folds of the integument where the mammary ducts terminate. Some movement, perhaps, of these ducts in connexion with the enlargement of the mammary lobes, under the stimulus of preparation for a coming offspring, may, with associated growth of the abdominal integument surrounding the areola, be amongst the physical causes of the first formation of the pouch. It has already been remarked that the integument of the pouch, especially as it approaches the fundus, is thinner than that covering the abdominal surface of the body, from which the pouch is continued. Such tegumentary growth, continued with the pressure of the part of the growing young within, may lead to a marked increase of size ; to he reduced, perhaps, by absorption and shrinking of the skin concomitantly with reduction of the mammary glands after the term of lactation has expired. I much doubt, however, whether the increase of size of the pouch would ever be such as to include and wholly conceal the young animal ; it more probably, at the later period of lactation, serves only to admit the head or beak. Thus the ordinary condition of sucking would be reversed in these Australian Mammals ; instead of the excretory ducts on an everted process of integument being taken into the mouth, this is received into an inverted pouch into which the milk is poured. I have not hitherto met with any trace or beginning of such abdominal pouches in the various Ornithorhynchi in which I have had occasion to note different phases of the development of the ovaria and mammary glands f. * Philosophical Transactions, 1832, p. 537, PI. XVII. figs. 2 & 3. t “On the Mammary Glands of the Ornithorhynchus jparadoxus ,” Philosophical Transactions, 1832, p. 517. PI. XY.-XYIII. AND MAMMARY FOETUS OF THE ECHIDNA HYSTRIX. 677 A warm-blooded air-breather, compelled to seek its food in water, could not safely carry the progeny it had brought forth in a pocket beneath its body during such quest ; and all observers have noted the nest-making instinct of the Platypus , in which tempo- rary and extraneous structures only the young have hitherto been found *. Mr. George Bennett states that the nest “ appears to be found about the time of bringing forth the young, and consists merely of dried grass, weeds, &c.” f Whether the Echidna prepares any extraneous nest is not known. The specimen transmitted to me by Dr. Mueller was caught in the hollow of a prostrate “ cotton tree.” Being a terrestrial animal, she can carry her young about habitually concealed or partly sheltered in her pouches ; and the present observations show the nearer affinity in this respect of the Echidna to the marsupial Ly encephala. The Echidna may further mani- fest this relationship by the more minute size of the young when born and transferred to the pouch, as compared with the Ornithorhynchus ; but the size of the new-born or newly-excluded young of that monotreme is unknown. The smallest specimen of a young Ornithorhynchus which I have yet seen is that (Plate XLI. fig. 5) to which allusion has been already made as being about two inches in length in a straight line. The following are the comparative dimensions of this, and of the young of the female Echidna (ib. fig. 3 (magn.), Plate XL. figs. 6-10 (nat. size)), the subject of the present communication : — Young Young- Ornithorhynchus. Echidna. in. lin. in. lin. Length from the end of the upper jaw, over the curve of the back, to the end of the tail .... 3 9 1 10 Length from the same points in a straight line along the abdomen 2 1 1 1 Greatest circumference of the body .... 2 9 1 o x Length of the head 0 8i 0 4 Length of the upper mandible from the gape . 0 3 0 1* Breadth of the upper mandible at the base 0 4 0 1 Length of the tail from the vent 0 4± 0 1 Breadth of tail at the root 0 4 0 X. Length of the fore foot 0 3 0 2 Breadth of ditto 0 0 H Length of the hind foot 0 4 0 l Breadth of ditto 0 3 0 H The circumstances under which this young Echidna was obtained are given in a letter by the captor, Mr. G. O. Harris, to Dr. Mueller, dated “ Colac Forest, August 31, 1864.” * Tom. cit. p. 533. f Trans. Zool. Soc. vol. i. pp. 247 & 253. + This might have been more before the body had become somewhat dried, or shrunk in rwt*, 678 PROFESSOR OWEN ON THE MARSUPIAL POUCHES, MAMMARY GLANDS, It appears that Mr. Harris, being in Colac Forest, Victoria, on the 12th of August, 1864, his attention was attracted by his dogs to a fallen tree, in the hollow of which the Echidna had taken refuge. “ On examining her I found the young one attached to one teat, presenting the appearance of a miniature Porcupine *, with an absence of quills, partially transparent, of a bright red colour.” The mother was placed in a porter-cask with earth containing ants. “ On Wednesday the 17th of August it still remained attached to the teat, presenting the same appearance as when first captured, evidently in a living state. I avoided handling it more than necessary, as it evinced signs of terror by a protrusion of the vagina and frequently emitting urine. •“ On Thursday, 18th of August, I emptied the earth out of the cask, to replace it with fresh earth containing ants, and to my surprise found the young one removed from the teat. I ‘ panned off’ the earth, as for gold, and found the young considerably shrunk.” Mr. Harris thereupon placed it in a bottle of spirits, and transmitted it, with the mother alive, to Dr. Mueller, Botanic Gardens, Melbourne. Mr. Harris concludes his letter by stating, “ My dates are correct, as I keep a diary, and you may rely upon what I have stated being authentic.” The condition in which the young Echidna has reached me accords with the above account. It is naked, devoid of prickles, the integument thin, but with its transparency affected by the action of the alcohol, and somewhat wrinkled from contractions of the tissues through the same action. The new-born Kangaroo, of similar size and con- dition, described in the Philosophical Transactions for 1834, p. 344, Plate VII. fig. 5, was also red, like an earthworm, “ resembling it not only in colour, but in the semi- transparency of the integument.” Mr. Harris’s observation of the young Echidna closely accords in this character with my own on the new-born living Kangaroo. Mr. Harris observed the young Echidna attached to the mother, and he concluded from analogy that the mode of attachment was as in the other land-quadrupeds of the colony and in mammalia generally ; whereas it was kept in situ by the duplicature of the skin, and by clinging with the precociously-developed claws of the fore feet to the interior of the pouch. There was most assuredly no nipple : in that particular my own scrutiny accords with the results of the examination of the recent animal by Drs. Mueller and Rudall. What appearances suggested to them the idea of four quite rudimentary mammary glands I have been unable to discover; the pair of large mam- mary glands, together with the pouches into which they pour their secretion, had escaped their observation. The youn ^Echidna (Plate XLI. figs. 3 & 4), of which the admeasurements have been given, resembles the young Ornithorhynchus (ib. fig. 5) in the general shape and curvature of the body ; it also resembles the new-born Kangaroo above cited in the proportions of the limbs to the body, in the inferior size of the hinder pair, in the degree of development of the digits, and in the feeble indication of eyes or eyelids. * The name by which the Echidna is commonly known to the settlers and gold-seekers of the colony. AND MAMMAEY FCETTTS OF THE ECHIDNA HYSTKIX. 679 But the mouth is proportionally wider, and has the form of a transverse slit (Plate XL. fig. 9, Plate XLI. fig. 4, n) ; it is not circular. Upon the upper lip (ib. fig. 4, m), in the mid line between the two nostrils (a), is a small protuberance (e), corresponding to that in the young of the Ornithorhynchus paradoxus (ib. fig. 5, e), and wanting the cuticle. The tongue (ib. fig. 4, l) is broad and flat, extending to the “ rictus oris,” but very short in proportion to that of the parent, and of a very different shape. The traces of ears are less conspicuous than in the young Kangaroo, the conch being little if at all developed in the mature Echidna. The tail is much shorter than in the young Kangaroo, and shows as much proportional size as in the full-grown Echidna, in which it is a mere stump (Plate XXXIX. c) concealed by the quills and hair. The head is proportionally longer and more slender in the marsupial foetus of the Echidna than in that of the Kangaroo, and already, at this early period, foreshows the characteristic elongation and attenuation of that part in the mature animal. The form of the mouth as a transverse slit, in Echidna as in Ornithorhynchus , is a good monotrematous character of the young at that period, since in all true or teated marsu- pials the mouth of the mammary foetus has a peculiar circular and tubular shape. A scarcely visible linear cicatrix at the middle of the lower part of the abdomen is the sole trace of umbilicus (Plate XL. fig. 9). A bifid, obtuse rudiment of penis or clitoris (Plate XLI. fig. 3, d) projects from the fore part of the single urogenital or cloacal aperture, and in advance of the base of the tail-stump (ib. c). The brain, of which the largest part is the mesencephalon, chiefly consisting of a vesicular condition of the optic lobes, has collapsed, leaving a well-defined elliptical fossa of the integument indicative of the widely open “ fontanelle ” at the upper part of the cranium (Plate XL. fig. 10, Plate XLI. fig. 3, o ). The skin of the shrunk body shows folds indicative of the originally plump, well-filled abdomen. The fore limbs (Plate XL. figs. 11 & 12), in their shortness and breadth, foreshow the characteristics of those of the parent, which may be said, indeed, to retain in this respect the embryonic character with superinduced breadth and strength. The digits have already something of the adult proportions, the first or innermost of the five (fig. 12, i) being the shortest, the others retaining nearly equal length, but graduating shorter from the third to the fifth. The characteristic disposition of the digits is better marked in the hind limb (ib. figs. 13 & 14), the second (ii) already being the strongest and longest, the rest more rapidly shortening to the fifth ( v ) than in the fore leg ; the innermost (i), agreeably with the law of closer retention of type in the embryo, though the shortest of the five, is less disproportionately so than in the adult. It thus appears that the exterior characters of the young animal, figured in Plates XL. & XLI., accord with what might be expected, from the correspondingly immature characters in Macropus and Ornithorhynchus , in the offspring of the species alleged. In a question of this kind, as the liberal transmitters of the specimens were not them- selves the captors or original observers of the young with the mother, every possibility mdccclxv. 5 B 680 PEOEESSOE OWEN ON THE MAESUPIAL POUCHES, MAMMAEY GLANDS, of error had to be considered. But I know of no pentadactyle ecaudate marsupial animal which could have afforded a mammary or marsupial foetus with the characters of that which Mr. Harris affirms to have discovered attached to the female Echidna, and which he transmits to his correspondents in Melbourne as the young of that monotreme. The condition of the mammary glands, and the presence of heretofore unobserved mar- supia, accord moreover with her alleged maternity and with the state of development of her offspring. It occurred to me that an additional test might be afforded by the more essential parts of the female organs of generation. These had been examined in a general way by Drs. Mueller and Rudall, whose “ Notes ” have been already quoted. I proceeded, therefore, to remove these organs (Plate XLI. fig. 1), with the rectum (ib. m), urinary bladder (r), urogenital canal (u), and cloacal vestibule (ml). The left ovarium (o), as in the Ornithorliynchus paradoxus , is of an oblong flattened form, developed from the posterior division of the ovarian ligament ( i ) and corre- sponding wall of the ovarian capsule (c) ; it consists of a rather lax stroma invested by a smooth, thin, firm “tunica propria,” which glistens where stretched over the enlarged ovisacs. Of these there were five, of a spherical form, most of them suspended to the rest of the ovarium by a contracted part of the periphery, not stretched into a pedicle. The largest had a diameter of 1^ line, the least of the five had a diameter of rather less than one line. In the recent state, very fine vessels were spread reticularly, according to the original dissectors, over the ovisacs. Beneath these, or nearer the ovarian liga- ment, was a cluster of smaller ovisacs, the largest not exceeding ^rd of a line, the rest so small as to give a granular character to the part. External to this, at the end of the ovarium nearest the bifurcation of the ligament, was an empty ovisac (g% 2f lines in length, and 2 lines in diameter, of a flattened pyriform shape, with a somewhat wrinkled exterior, attached by the base, with the apex slightly tumid, and showing a trace of a fine cicatrix. This is a “corpus luteum” or ovisac from which an ovarian ovum had been discharged. The oviducal branch of the ovarian ligament passes, as in the Ornithorliynchus , to the outer angle of the wide oviducal slit or aperture (e), which occupies or forms the margin of the ovarian pouch ( c ), opposite to that to which the ovary is attached. The ligament spreads upon the inner wall of the infundibular part of the oviduct, and rejoins the ovarian division of the ligament, to be continued along the oviduct, puckering up its short Convolutions into a small compass. The “ fallopian” aperture of the infundibulum (e), is a longitudinal slit of 9 lines in length, with a delicate membranous border extending about a line beyond the part where the muscular and mucous tissues of the oviduct make the thin wall of the infun- dibulum opake ; its transparency against a dark ground, contrasting with the opake beginning of the proper tunics of the oviduct, which nevertheless are here very thin. No part of this delicate free margin is produced into fimbriae ; in this respect the AND MAMMAEY ECETTTS OF THE ECHIDNA HYSTEIX. 679 Echidna accords with the Ornithorhynchus, and equally manifests the character by which the Monotremes differ from the Marsupials*. The infundibular dilatation suddenly contracts about an inch from the opening into a “ fallopian tube,” about a line in diameter, which is puckered up into four or five short close coils. The oviduct, after a slight contraction, suddenly expands into the uterus (ib. d ). This is about 2 inches long, and appears to have been about 6 lines in diameter, before being cut open. It commences by a short well-marked band, convex outwards, and then proceeds nearly straight, the pair converging to the urogenital compartment, slightly contracting at its termination, which projects, as an “ os tincse ” (ib. s'), into the side of the fundus of that division of the cloaca. The tunics of the uterus are, externally, the peritoneum (ib. fig. 2, a), which is attached by a lax cellulosity to the “ tunica propria” (b) ; this, with its fibrous or muscular layer, is thin, not exceeding ^th of a line in the present specimen. The inner layer of the uterine wall ( c ) is the thickest, and chiefly composes it, consisting of delicate vascular lamellae stretched transversely between the fibrous layer and the fine smooth lining membrane ( d ), the whole being of a pulpy consistence, and doubtless in the recent animal highly vascular, especially in the impregnated state. The lining membrane was thrown into delicate irregular rugae, which assumed the longitudinal direction at the “cervix” or contracted terminal part of the uterus. It is laid open in the left uterus ; a style (s) is passed through it in the right uterus. The orifice in the 44 os tincae” was a puckered slit, about a line in extent ; below it, on a produced or papillose part of the prominence, was the small circular orifice of the ureter; a fine hair is passed through each of these tubes in fig. 1, u, Plate XLI. The right ovarium (o'), was proportionally more developed and larger than in the Ornithorhynchus paradoxus \ three ovisacs were enlarged and attached to the stroma, as in the left ovarium ; and there was also a compressed ovisac (g), similar in size and shape to that in the left side, and exhibiting an apical cicatrix; whence it is to be inferred that, in this instance, the right as well as the left ovarium had furnished an impregnated ovum ; and the near equality of size and close similarity of structure and condition of the right oviduct and uterus equally evinced that they had participated in the last operations of the season of generation. Figure 2 gives a magnified view of the structure of the right uterine walls, as seen in transverse section. The urinary bladder (r), opened into the middle of the fundus of the urogenital com- partment, as indicated by the stylet (r, fig. 1, Plate XLI.), the uterine orifices intervening between the vesicular one and those of the ureters, as in the Ornithorhynchus paradoxus. * See Philosophical Transactions, 1834, Plate YI. fig. 1- — “fimbriae” of Kangaroo” ; and art. Marsupialia, Cyclop, of Anatomy and Physiology, vol. iii. fig. 137, “fimbriae” still more remarkably developed in the Wombat ( Phascolomys ). The absence of these fimbriae, and the resemblance of the true abdominal orifice of the oviduct to that of the ovarian pouch, or to an ordinary duplication of membrane, appear to have prevented its recognition by Drs. M. and R. 5 b 2 682 PROFESSOR OWEN ON THE MARSUPIAL POUCHES, MAMMARY GLANDS, The urogenital canal is 1 inch 4 lines in length, and about 9 lines in diameter : its inner surface shows by some coarse wavy longitudinal rugae its capacity for dilatation. The rectum was here of great width ; it terminated by a contracted puckered aper- ture (m'), in the back part of the beginning of the vestibule, behind the aperture of com- munication of the urogenital with the vestibular canal. The distal half of the vesti- bule is lined by a denser and less vascular epithelium than the proximal one. I conclude from these appearances that the present Echidna had produced two young, of which one only was secured ; and that, either, one was left in a nest in the fallen hollow tree, while the other was imbibing milk from the pouch ; or that, if she had carried a mammary foetus in each pouch prior to her capture, one had fallen out in the scuffle that drove her from her place of shelter and concealment. The slight difference in size between the right and left mammary glands may relate to the longer continuance of the left one in functional activity, after the loss of the young from the right pouch. The chief points in the generative economy of the Monotremes which still remain to be determined by actual observation are — 1. The manner of copulation. 2. The season of copulation. 3. The period of gestation. 4. The nature and succession of the temporary structures for the nourishment and respiration of the foetus prior to birth or exclusion. 5. The size, condition, and powers of the young at the time of birth or exclusion. 6. The period during which the young requires the lacteal nourishment. 7. The age at which the animal attains its full size. In respect to the second point : as Mr. Harms caught the female Echidna with the young, about an inch in length, on the 12th of August, she may be impregnated at the latter end of June or in July. Females killed in the last week of July and the first week of August, in the Province of Victoria, would be most likely to afford the capital facts noted under the fourth head ; viz. the impregnated ovum in utero showing some stage of embryonal development in the spiny terrestrial Monotreme. As to the hairy and aquatic Ornithorhynchus , the impregnated females in which ova were found in the uterus, of small size, and prior to the formation of the embryo, were caught on the 6th and 7th of October*. Young OrnithorJiynchi , measuring in length in a straight line 1 inch and ffhs, were found in the nest on the 8th of December. The period of im- pregnation is, therefore, in this species, in the locality of the Murrumbidgee River, probably the latter end of September or beginning of October. Females captured in the latter half of October and in the month of November, would be most likely to have ova in utero exhibiting stages of embryonal development. On this point I have been favoured with the following letter, one of a kind including most which reach me from Australia on the subject, exciting, instead of allaying, curiosity. * See figure of the impregnated specimen in Philosophical Transactions, 1834, Plate XSY. a, a'. AND MAMMARY FOETUS OF THE ECHIDNA HYSTRIX. 683 “ "Wood’s Point, September, 21st, 1864. “ To Professor R Owen, “ Sir, — I have great pleasure in being able to inform you of a very interesting disco- very in the economy of the Ornithorhynchus paradoxus, and one which I have no doubt you will hail with delight. About ten months ago, a female Platypus was captured in the River Goulbum by some workman who gave it to the Gold-Receiver of this district. He, to prevent its escape, tied a cord to its leg and put it into a gin-case, where it remained during the night. The next morning, when he came to look at it, he found that it had laid two eggs. They were about the size of a crow’s egg, and were white, soft and compressible, being without shell or anything approaching to a calcareous covering. “ I had an opportunity of examining them externally, and I found no evidence of their having had any recent vascular connexion with the maternal organs ; but I am sorry to say that I never had a chance of examining their contents, as, on inquiring for them a day or two afterwards, I found they had been thrown away, much to my chagrin and disappointment. “ The animal itself was afterwards killed (next day), and I was told that numerous ova [in the words of my informant ‘ eggs’] were found in it, in various stages of develop- ment, which in the aggregate somewhat resembled a bunch of grapes ; but this I can- not personally vouch for. “ It may appear to you a matter of surprise that I did not examine more minutely this most interesting animal ; but I am sorry to say that the same spirit that dictated the throwing away of the eggs, prevented me making a more detailed investigation. “ I am in hopes that I shall be able to get another pregnant specimen, if so, I shall have much pleasure in sending it to you for your inspection. I have the honour to be, Sir, “ Your obedient Servant, “ Jno. Nicholson, M.D., &c.” Wood’s Point, Victoria, Australia.” By a following mail I was favoured by my esteemed correspondent, Dr. Mueller, with a letter from the “Gold-Receiver” referred to by Dr. Nicholson, in reply to inquiries which vague reports of the occurrence had induced Dr. Mueller to make. “ Wood’s Point, September 25, 1864. “Dear Sir, — In reply to your inquiries relative to the Ornithorhynclius paradoxus, I must in the first place correct an erroneous impression which the newspaper paragraph has conveyed. “ The Platypus is not now in my possession, and the eggs were layed the day after its capture. The animal was captured in the Goulburn and given to me. It was then fastened by a cord in a gin-case, and on examining it the next morning the two eggs were found in the bottom of the box, both of them having undoubtedly been laid 684 PROFESSOR OWEN ON THE MARSUPIAL POUCHES, MAMMARY GLANDS, during the night. In the course of the day the creature was killed by a would be scien- tific friend of mine, with the intention of preserving its skin ; and on opening the body the ovaries were found to be clustered with ova in different stages of growth ; but none of them so large as the eggs which were laid. These eggs were white, soft, and with- out shell, easily compressible, and about the size of a crow’s egg. “ Not being sufficiently versed in the subject I am not prepared to say whether these eggs might not have been abortions caused by fear, but there was no appearance on the surface of their ever having been vascularly connected with the maternal uterus, and reviewing all the facts observed I should undoubtedly say that the animal was oviparous. “ I am, dear Sir, “ Yours faithfully, (Signed) “ Geo. J. Rumby.” Dr. Mueller, in transmitting me the foregoing copy of the Gold-Receiver’s letter, writes (November 25th, 1864), “ Since writing to you by last mail I have received the enclosed letter respecting the Ornithorhynchus having proved to be ‘ oviparous .’ How are all these statements to be reconciled]” Assuming the fact of the oviposition, in the month of December 1863 (Dr. Nicholson writes of the occurrence as having happened “ about ten months” before the date of his letter, September 21, 1864) by a female Ornithorhynchus , of two ova, about the size of a crow’s egg, “ white, soft, compressible, without shell or anything approaching to a calca- reous covering,” the question is — What did they contain 1 Had the unvascular chorion been cut or torn open, an embryo or a yelk might have been seen. Better still would it have been if both ova had been at once immersed in a bottle of whatever colourless alcoholic liquor might be at hand. Probably no medical man had ever an opportunity or a chance of settling a point in Comparative Physiology of more interest, and with less trouble, than the gentleman who was privileged to be the first person to see and handle the new-laid eggs of the Ornithorhynchus paradoxus. For the reasons given in my Memoir of 1834*, I concluded that the Monotremes were not “ oviparous” in the sense of the author of the memoir in the ‘ Annales des Sciences Naturelles,’ vol. xviii. (1 829)*^, but that they were ovo-viviparous, and in a way or degree more nearly resembling the generation of the Viper and Salamander than occurs in the Marsupialia. The young Viper is provided with a specially and temporarily developed premaxillary tooth for lacerating the soft, but tough, shell of its egg, and so liberating itself J. From this analogy I imagine that the young Monotremes may be provided with a horny or epidermal process or spine upon the internasal tubercle, for the same purpose. This temporary tubercle is obviously homologous with the hard knob on the upper mandible * “ On the Ova of the Ornithorhynchus paradoxus ,” Philosophical Transactions, vol. cxxiv. p. 555. f R. E. Grant, “ (Eufs de l’Ornithorhynque,” Ann. des Sciences Nat. 1829. + W einland, in Muller’s Archiv fur Physiologie, 1841. AND MAMMARY DCETTJS OF THE ECHIDNA HYSTRIX. 685 of chelonians and birds, by which they break their way through the harder calcareous covering of their externally hatched embryo. Some modification of epiderm has been removed from the tubercle in the young Echidna (Plate XLI. fig. 11, e ), as in the young Ornithorhynchus *. Desckiption op the Plates. PLATE XXXIX. *> Female Echidna {Echidna Hystrix , Cuv.), two-thirds nat. size. a. Left “ Marsupial ” or “ Mammary ” pouch, with young as seen therein. b. Right ditto empty. c. Tail-stump of Echidna. d. Outlet of cloacal vestibule. e. Young or “ mammary foetus,” as removed from the pouch ; two-thirds nat. size. PLATE XL. Fig. 1. Section of abdominal integument, with mammary glands of the Echidna exposed from the inner side. a. Left mammary gland ; a'. Right mammary gland. b. Ducts converging to fundus of mammary pouch. d, d'. Part of “ panniculus carnosus ” acting as compressor of the gland. e. Fascia forming a capsule of the gland, reflected. f Skin of abdomen. Fig. 2. Section of abdominal integument, and left mammary gland and pouch. Fig. 3. Section of abdominal integument, and right mammary gland and pouch. c. Cavity of pouch ; the other letters as in figure 1. Fig. 4. Orifice of mammary pouch, expanded to expose the mammary areola. Fig. 5. Mammary areola magnified to show the orifices of the lacteal ducts, and p, seba- ceous papillse. Fig. 6. Young or “mammary foetus” of Echidna Hystrix : nat. size: side view. Fig. 7. Ditto : front view. Fig. 8. Ditto : back view. Fig. 9. Ditto : under view. Fig. 10. Ditto: upper view. Figs. 11 & 12. Ditto : fore-foot magnified. Figs. 13 & 14. Ditto: hind-foot magnified. * Transactions of the Zoological Society, vol. i. pi. xxxiii. fig. 8. 686 PEOFESSOE OWEN ON THE ECHIDNA HYSTEIX. PLATE XLI. Fig. 1. Female organs of Echidna Eystrix ; letters explained in the text. Fig. 2. Section of uterus : magnified ; ditto. Fig. 3. Young of Echidna Eystrix: twice nat. size; ditto. Fig. 4. Ditto: mouth and end of upper jaw: five times nat. size: — «, nostril; inter- narial tubercle ; m, upper lip ; n, lower lip ; Z, tip of tongue. Fig. 5. Young of Ornitliorhynchus paradoxus: — a, nostril; b , eye-orifice; c, ear-orifice; e, internarial tubercle ; relatively smaller than in fig. 3, as being in progress of disappearance in a more advanced young one. Fkol. Trans. MDCCCLXV TlateXXX IX J.WcJf del Pful. Trans . MD CCC13CV, PlateY, L R-Owen.F.RS. del. Edwin H. Williams, El.S. Sc. Phil. Trans. MDCCCL Tf, Plate XL1 Pig. 5 Fig.4< Fig 3. R. Owen,F.R.S. del. Edwin M Williams F.L.S^Sc, [ 687 ] XVI. On the Influence of Physical and Chemical Agents upon Blood ; with special reference to the mutual action of the Blood and the Bespiratory Gases. By George Harley, M.D. , Fellow of the Boyal College of Physicians , Professor of Medical Jurisprudence in University College , London. Communicated by Pro- fessor Sharpe y, M.D., Sec. B.S. Received March 3, — Read March 10, 1864. In order to prevent repetition, as well as to facilitate the understanding of the researches about to be described, it is deemed advisable at once to give a brief explanation of the manner in which the experiments were conducted. In the first place, it may be men- tioned that all the gas-analyses herein detailed were made in strict accordance with the justly celebrated method of Professor Bunsen, so ably explained in his work on Gasometry. In the second place, the blood employed in the experiments was always obtained from apparently healthy animals, and with the few exceptions, presently to be alluded to, operated upon while still perfectly fresh. In the third place, the apparatus used in the majority of the experiments consisted of a graduated glass receiver of the shape represented in the accompanying figure (A), the neck of which was drawn out to a fine capillary tube, upon the end of which was placed a piece of caoutchouc tubing. mdccclxv. 5 c 688 PROFESSOR HARLEY ON THE INFLUENCE OF After a certain quantity of blood (usually 62 cubic centimetres) or other fluid was introduced at the mouth (b), the latter was firmly closed with a tightly fitting cork, and the remaining opening (f) secured by a ligature, so that all communication between the external atmosphere and the gas confined with the blood was effectually interrupted. When the experiment was completed, the gas was obtained from the receiver by plunging the lower end of the vessel into mercury, and carefully removing the cork, while it was still retained in that position, so that neither the contained gas could find an exit, nor the external air obtain admittance. A tube (B) partly filled with mercury was now carefully adjusted to the mouth of the receiver by a well-fitting cork ( d ); the receiver was next removed from the mercury trough, and a fine capillary glass tube (C) inserted into the free end of its piece of caoutchouc tubing ; the end of this tube was dipped under the surface of mercury and the ligature at f removed. The mercury in B immediately descended and forced the atmospheric air out of the tube C, which in its turn became filled with gas from the receiver. The end of the tube C was then brought under an inverted eudiometer filled with mercury, and more of that liquid poured into B until sufficient gas was obtained from the receiver for analysis. In the fourth place, the temperature of the human body was imitated by employing an artificial digesting apparatus which could be readily kept at a constant heat of 38° C. Lastly, the experiments were performed in a gas-laboratory, the temperature of which varied but slightly during the twenty-four hours, and their performance was thereby greatly facilitated. For the use of this laboratory I am deeply indebted to the President and Council of University College, London, who most liberally placed it at my entire disposal during a period of three years. As indicated by the title of the paper, the series of researches about to be detailed is devoted to the influence of some physical and chemical agents on the blood with refe- rence to its action on the respiratory gases. For the sake of convenience, the communi- cation is divided into two parts. The first includes the influence of the following physical agents. a. The effect of simple diffusion in producing a change in the mixture of gases con- fined with blood. b. The influence of motion on the changes reciprocally exerted upon each other by blood and atmospheric air. c. The influence of time on the interchange of the respiratory gases. d. The effect of temperature on the same, from 0° C. to 38° C. e. The influence of the age of the blood, including the effect of the putrefaction. The second part of the communication is devoted to the consideration of the influence of chemical agents, especially such as are usually denominated powerful poisons. These agents are selected from the three kingdoms. a. Animal. b. Vegetable, and c. Mineral. PHYSICAL AND CHEMICAL AGENTS UPON BLOOD. 689 In relating the experiments, I have sedulously avoided advancing any theories with regard to the mode of action of any of the agents studied, and on one or two occasions only has even as much as a hint been given that the results obtained might in any way tend to the elucidation of the action of remedies or the mode of death by poison. The reticence in this instance has arisen from the circumstance that several of the results are so novel and at the same time so pregnant with material for theorizing, that the indi- vidual facts might soon be lost sight of in a sea of speculation. It appears to me there- fore that the ends of science will be much better served if I confine myself to a descrip- tion of the bare data, rather than propound the numerous theories which the different results suggest, and which, although they might make the paper more interesting, could not in reality add to its true value. I may also mention that the material is so arranged as to be easily accessible, each fact having been made as far as possible independent of its associates, in order that future inquirers may find no difficulty in isolating any particular result they may desire specially to investigate. Moreover, the progressive details of each experiment are given in the form of an appendix, so that the initiated investigator can follow it with facility through its different stages, either for the purposes of comparison or verification *. Past I. — INFLUENCE OF PHYSICAL AGENTS. (a) The effect of Diffusion in modifying the composition of atmospheric air confined with fresh blood. The influence of both venous and arterial blood was studied. 1st. As regards arterial blood. A certain quantity of arterial blood was allowed to flow directly from the femoral artery of a healthy dog into a glass receiver, and after being carefully secured along with 100 per cent, of atmospheric air, was placed aside in a warm room during forty-eight hours. At the end of this time the receiver was opened in the manner already described, and a certain quantity of its gas removed for analysis. * The Appendix is deposited for reference in the Archives of the Loyal Society. The first analysis only is given in detail as a specimen. 5 C 2 690 PROFESSOR HARLEY ON THE INFLUENCE OF No. 1. — Air from arterial blood of Dog. Volume. Barometric pressure. Temperature. Vol. at 0° C. and 1 metre pressure. For carbonic acid. Air employed 140-3 718-7 7-7 98-08 After absorption of carbonic acid 139-0 719-4 5-8 97-91 For oxygen. Air employed... 244-2 359-0 6-2 85-72 After addition of hydrogen 331-8 449-9 6-1 146-00 After explosion 258-0 372-9 4-5 94-64 No. 1. — In 100 parts of air. Oxygen . . Carbonic acid Nitrogen . 1 9-928'> 0 ^g0>Total oxygen 20-111 79-889 2nd. As regards venous blood. A certain quantity of venous blood was allowed to flow directly from the jugular vein of an apparently healthy dog into a glass receiver. It was then secured along with 100 per cent, of atmospheric air, and kept, as in the previous case, in a room of moderate temperature during forty-eight hours. The gas from this blood gave the following result : — No. 2. — In 100 parts of air. Total oxygen 20-557 Oxygen . . . 18-400 Carbonic acid . 2-157 Nitrogen . . . 79-443 As the composition of ordinary atmospheric air is supposed to be : — l 100 parts. “}TM oxygen 20-962 79-038 it appears from the results of these experiments that both arterial and venous blood act in precisely the same manner, the amount alone of their action being different. As might have been expected, the venous blood has yielded by simple diffusion a much greater amount of carbonic acid than the arterial blood. Moreover, under the same circumstances it has absorbed a much larger quantity of oxygen. Oxygen . . Carbonic acid . Nitrogen . PHYSICAL AND CHEMICAL AGENTS UPON BLOOD. 691 In 100 parts. Oxygen. Carbonic acid. Nitrogen. Total oxygen. Atmospheric air operated upon 20-960 0-002 79-038 20-962 Air after forty-eight hours’ contact with — Arterial blood 19*928 0-183 79*889 20-111 Venous blood 18-400 2-157 79-443 20-557 The total amount of oxygen is in both cases slightly diminished, and with this diminu- tion the proportion of nitrogen, which is calculated by “ difference,” is necessarily increased. (b) Effect of Motion on the action of blood on atmospheric air. The mere effect of motion was attempted to be ascertained in the following manner. Two portions of the same blood of a calf, after being thoroughly arterialized by being repeatedly shaken with renewed portions of air, were confined in receivers with 100 per cent, of air, and treated in a precisely similar manner during forty-eight hours, except that one blood had a small quantity of quicksilver added to it in order to render its agitation more complete. The following were the results obtained. Pure blood of calf, forty-eight hours’ action with 100 per cent, of atmospheric air: — No. 3. — In 100 parts of air. Oxygen Carbonic acid . Nitrogen . . ^.Jgj-Total oxygen 18-22 81-78 Same blood shaken with quicksilver, forty-eight hours’ action with 100 per cent of air, yielded the following result : — No. 4. — In 100 parts of air. Oxygen . . . Carbonic acid . Nitrogen 4-11) 7*63/ 88-76 •Total oxygen 11-64 Oxygen. Carbonic acid. Nitrogen. Ox-blood 15-14 3-08 81-78 Ox- blood plus quicksilver... 4-1 7*53 88-76 The difference between these results is very striking, so much so, that it was thought advisable to discover if the mercury had not exerted some undefined chemical action, either on the air or blood, in addition to its mere mechanical influence in facilitating their thorough mixing. With the view of solving this question, other two portions of blood were taken, and while to one a small quantity of quicksilver was added, the other 692 PROFESSOR HARLEY ON THE INFLUENCE OF had an equal amount of powdered glass mixed with it. Both receivers were put aside in a place where the temperature never exceeded 7° C. At the end of five days, during which period they were repeatedly shaken, the air was analyzed for carbonic* acid. No. 5. — In 100 parts of air. Carbonic acid from blood, plus quicksilver . . I- 72 „ „ „ „ „ glass . . . T30 As it appeared from this and the foregoing that the action of the mercury was some- thing more than merely mechanical, in order to ascertain the influence of motion alone, two equal portions of the same fresh venous blood from an ox were placed in receivers with similar proportions of atmospheric air (1 vol. of blood to 3 vols. air) and kept at a temperature of 30° C. during six hours. In each receiver was placed a small quantity of powdered glass, in order the more effectually, when the receivers were shaken, to mix the blood. The first receiver was shaken only three minutes at a time, the second five. In all other respects they were treated exactly alike*. Air after being enclosed during six hours at a temperature of 30° with venous blood shaken with glass, three minutes at a time. Result : — No. 6. — In 100 parts of air. Oxygen . . . Carbonic acid . Nitrogen . . J^j-Total oxygen 18-20 81-80 Same blood as the preceding, under precisely the same circumstances, but shaken during five minutes at a time. Result : — No. 7. — In 100 parts of air. Oxygen .... Carbonic acid . . Nitrogen . . . It thus appears that the mere effect gases interchanged. 1 4.40} 4-44) Total ox^en 18'93 81-07 of motion has an influence on the amount of (c) Influence of Time on the interchange of gases between the blood and air. It was found from a series of experiments (as might have been expected from our knowledge of the respiratory process) that the longer air is retained in contact with blood, the greater is the change worked in its chemical composition. Thus it was found * It may be bere mentioned that during tbe course of these experiments it was found necessary, in order to arrive at anything like correct results, not only to use (in the comparative experiments) the blood of the same species of animal, but of the same bleeding ; as for some cause or other, the state of the digestion or the health of the animal, different bleedings invariably gave slight differences in result. PHYSICAL AND CHEMICAL AGENTS UPON BLOOD. 693 that if the ordinary respiratory act was imitated as closely as possible, by simply passing a current of pure atmospheric air through a series of twenty-four blown glass bulbs, partly filled with defibrinated arterialized ox-blood, kept in a digestive apparatus so con- structed as to be capable of being retained at the temperature of the human body, the air underwent the following change. Air after passing through twenty-four bulbs half filled with blood, at a temperature of 38° C., gave the following results: — No. 8. — In 100 parts of air. Oxygen . . . Carbonic acid . Nitrogen . 20-61) 0-96/Total °Wn 21-57 78-43 It is thus seen that the blood out of the body exerts a similar chemical action upon air brought in contact with it as it does in the lungs of the living animal, at least so far as the interchange of gases is concerned. The next point being to retain the air longer in contact with the blood at the same temperature, the following experiment was per- formed. Defibrinated fresh ox-blood, after being well arterialized by shaking it with renewed portions of air, was kept during 1| hour in contact with 100 per cent, of pure atmo- spheric air at a temperature of 38° C. No. 9. — In 100 parts of air. Oxygen ... .19 76)^^ 0Xygen 22-68 Carbonic acid . . 2-921 Nitrogen . . . 77’32 Another portion of the same blood as the preceding was heated in precisely the same manner, but instead of being kept only 1^ hour in contact with the air it was retained 34 hours. No. 10. — In 100 parts of air. ^ [-Total oxygen 22-87 Oxygen. . . . 18-80 Carbonic acid . Nitrogen . . . 77-13 The effect of time is well illustrated in these three examples, for with the single exception of the period during which the air was in contact with the blood, all the other factors were identical. By placing the results in a tabular form, the influence of time is more easily appreciated. Oxygen. Carbonic acid. Nitrogen. Air employed 20-96 00-00 79-04 After a few seconds’ action by blood 20-61 00-96 78-57 After 1^ hour’s action 19-76 02-92 77-32 After 3^ hours’ action 18-80 04-28 76-92 694 PROFESS OB HARLEY ON THE INFLUENCE OF It is here seen that the reciprocal action of blood and air is gradual, and one requiring time, a fact which supports the view that the inspired air gradually combines with the constituents of the blood in the torrent of the circulation. (d) Influence of Temperature. 1st. As regards the amount of carbonic acid exhaled. Three equal portions of freshly-defibrinated ox-blood, after being well arterialized by repeated agitation, were put into receivers with 100 per cent, of air, and kept at the following different temperatures during 3J hours : — 1st. At 0° C. 2nd. At 26° C. 3rd. At 38° C. No. 11. — The results when calculated yield in 100 parts of air, — 1st. Temperature 0° C.=0-00 carbonic acid. 2nd. „ 26°C. = 3-08 3rd. „ 38° C.=4-07 Thus the higher the temperature, up to a certain point, the greater is the amount of carbonic acid exhaled. In order to see if the same rule is applicable to the oxidation of the constituents of the blood, other three portions of defibrinated ox-blood were taken, and after being treated in the usual way, were kept at different temperatures during twenty-four hours. (a) In an ice cellar. (b) In a room at 12° C. (c) In an artificial digesting apparatus heated to 38° C. (a) Ox-blood with 100 per cent, of air, twenty-four hours’ action at 0° C. Result No. 12. — In 100 parts of air. Nitrogen . . . 81-98 This experiment was made in foggy weather. (b) Ox-blood with 100 per cent, of air, twenty-four hours’ action at 12° C. Result No. 13. — In 100 parts of air. Oxygen. . . . 12‘54lm , „ ^ Carbonic acid. . 2.77}Total oxygen 15-31 Nitrogen . . . 74*69 PHYSICAL AND CHEMICAL AGENTS UPON BLOOD. 695 ( c ) Ox-blood with 100 per cent, of air, twenty-four hours’ action at 38° C. No. 14. — In 100 parts of air. Oxygen . . . Carbonic acid . Nitrogen . . 22-4o}T°tal oxygen 22'40 77-60 Result : — The amount of carbonic acid exhaled in this case seems very extraordinary, neverthe- less I believe that it is perfectly correct, for another portion of the same blood, used as a controlling experiment, yielded to within a fraction of the same amount of carbonic acid. The fraction of difference, too, was an excess, being 22-6 instead of 22*4. Thus 24 hours at 38° C. Result: — No. 15. — In 100 parts of air. Carbonic acid =22* 6. As the weather was exceedingly foggy at the time these experiments were made, it was deemed advisable to analyze the fog in order to ascertain how much carbonic acid it contained, lest the extraordinary results obtained in the last two experiments might be due to that cause, or to some disease in the blood. No. 16. — Result of an analysis of fog in 100 parts of air. Carbonic acid =0-52. This is the greatest amount of carbonic acid 1 ever obtained from London fog, and large though it be, it is still far too small a quantity to account for the results in the last two cases. By placing the different effects of temperature in a tabular form, the influence exerted by that factor over the chemical changes occurring in blood will be still better appreciated. Defibrinated ox-blood. Oxygen. Carbonic acid. Nitrogen. Temperature 0° C. 24 hours 17*43 00-59 81-98 „ 12° C. „ 12*54 02-77 74-69 „ 38° C. „ 00-00 22-40 77-60 The influence of temperature on the interchange of gases is equally well illustrated by comparing the results of experiment 13 with that of experiment 10, when it will be seen that 3J hours’ action at a temperature of 38° C. (the temperature of the animal body) yields much more carbonic acid than 24 hours’ action at a temperature of 12° C. 100 per cent, of air with ox-blood. Oxygen. Carbonic acid. Nitrogen. 24 hours’ action at 12° C 12-54 2-77 74-69 3i „ „ 38° C 18-80 4-07 77-13 The effect of temperature on the individual constituents of the blood was also studied, mdccclxv. 5 D 696 PROFESSOR HARLEY ON THE INFLUENCE OF but only with red coagulum was it found sufficiently well marked to merit being noticed here. Three equal portions of coagulum from fresh ox-blood were confined with 100 per cent, of atmospheric air during six hours at the following temperatures. (a) At 21° C. ; ( b ) at 30° C. ; (c) at 36° C., with the following results: — Amount of carbonic acid in 100 parts of air in No. 17. ( a ) 6 hours at temperature of 21° C.=2-34 carbonic acid. No. 18. (b) „ „ 30° C.=5T8 No. 19. (c) „ „ 36° C.=7-29 It is thus seen that the amount of carbonic acid exhaled by red-blood coagulum in- creases with the temperature as far as the experiment went, namely from 21° to 36° C. 2nd. As regards the influence of cold in retarding the reciprocal chemical changes which occur between atmospheric air and blood, a striking proof of which is to be found in the result of the following experiment. Two ounces of arterial blood were allowed to flow directly from the carotid artery of a dog into a glass receiver, which in order still further to ensure its being thoroughly oxi- dized, as well as to prevent its coagulating into a solid mass, was shaken with renewed por- tions of air during two hours ; a small quantity of fluid mercury being also employed to prevent the coagulation. After this treatment the receiver was firmly corked and kept (with occasional agitation) in a room the temperature of which never exceeded 7° C. during five whole days. Dog’s arterial blood five days at a temperature under 7° C.* Result: -In 100 parts of air. 12-62] ^9|Total oxygen 14*34 No. 20.- Oxygen . Carbonic acid . Nitrogen . . . 85-66 On its removal from the receiver, the blood, although dark in colour, had a perfectly fresh odour. The diminished temperature not only retarded the chemical changes, which for the sake of convenience we may term “ respiratory,” but also those decompositions and transformations so intimately connected with oxidation, to which the name “ putre- faction” has been given. (e) Influence of the age of the blood. The putrefactive changes occurring in blood are exceedingly curious, and perhaps it may not be out of place if some of them be here alluded to. The following series of experiments were made on sheep’s blood. The first began within two hours after the blood was withdrawn from the animal, the last after it had stood 688 hours. * The first part of this experiment has been already given, but it is here again repeated in order to save the time of the reader in referring back to it, and so it is occasionally done with some others. PHYSICAL AND CHEMICAL AGENTS UPON BLOOD. 697 Two ounces of well defibrinated sheep’s blood, after being arterialized by constant agi- tation with renewed portions of air during twenty minutes, were put into a receiver with 100 per cent, of atmospheric air and kept during twenty-four hours in a room the tem- perature of which varied from 6° to 12° C. Result : — No. 21. — In 100 parts of air. Oxygen . . . Carbonic acid . Nitrogen . . ^.QgjTotal oxygen 15*81 84*19 A similar portion of the same blood as the preceding, after being exposed to the air in an open glass vessel during sixty hours, was treated in an exactly similar manner, and then placed in a receiver with 100 per cent, of air. The temperature of the room during the time of the experiment varied, as before, from 6° to 12° C. The blood after the sixty hours’ exposure had become of a dark venous hue, but it still arterialized readily on being agitated with fresh portions of air. It smelt slightly, as if putrefaction had begun. Under the microscope the red blood-corpuscles were perfectly distinct. Result : — No. 22.- Oxygen . . . Carbonic acid . Nitrogen . -In 100 parts of air. 2*88 3-69J 93*43 Total oxygen 6*57 This blood, which was of a bright arterial hue when put into the receiver with the air, at the end of the twenty-four hours had again resumed the venous colour. On shaking the vessel the blood looked as if it were decomposed. It remained of a dark purple colour on the sides of the glass, although the blood was at this time eighty-four hours old. On removing it from the receiver, and shaking it with renewed portions of atmospheric air, it again assumed the arterial tint. After the sheep’s blood was 136 hours old it was of a dark purple colour, and when a thin layer was spread over a white plate it looked quite granular. When examined with the microscope, the blood-corpuscles were still found perfectly distinct in their outline, and on being measured they averaged 4ijo millim. (j oTo 6 o inch) in diameter. The blood arterialized readily on being shaken with fresh air. A third portion of this blood was taken and subjected in every respect to precisely the same treatment as in the two preceding cases. Result : — No. 23. — In 100 parts of air. Oxygen. . . . 1*01' Carbonic acid . . 4*31, Nitroeen . . . 94*68 Total 0XJi 5*32 A fourth portion from the same blood, after it was 184 hours old, still became of an 5d2 698 PROFESSOR HARLEY ON THE INFLUENCE OF arterial hue when well shaken with air, although it had a film of fungi on its surface, and smelt strongly as if it were putrid. When once arterialized it looked exactly like freshly-drawn blood, and when examined microscopically it showed the red blood-corpus- cles as well as if it had only been a day old. Indeed, by its previous history, and smell alone, could a stranger have had any idea of its having been drawn from the animal more than a few hours. The fourth portion was treated in a similar manner, and for the same length of time as the others. In this case, for some cause or other, no explosion could be obtained, even after the addition of 50 per cent, of explosive gas. Result : — No. 24. — In 100 parts of air. Oxygen .... OOO Carbonic acid . . 4-91 Nitrogen . . . 95'09 The blood after 304 hours’ exposure still arterialized when well agitated with air. On using the microscope, the corpuscles were found to be distinct, though not so numerous as at first. They were best seen without adding water. Indeed the addition of water almost totally destroyed them by instantly dissolving their attenuated walls and allowing their contents to escape. A fifth portion of this blood was treated precisely as the preceding examples with 100 per cent, of air in one of the usual glass receivers, the temperature of the room varying, as before, from 6° to 12° C. The oxygen, if there was any, was not estimated. No. 25. — In 100 parts of air. Carbonic acid . . 4’99 The blood after being kept 688 hours still arterialized on being thoroughly shaken with renewed portions of air. It was fearfully fetid, and contained numbers of living animalcules of the Vibrio class. The red corpuscles were still distinct, though in greatly diminished quantity, from numbers of them having become broken up and dissolved *. The usual quantity of this blood was put into the receiver with 100 per cent, of air and treated during twenty-four hours in the ordinary manner. No. 26. — In 100 parts of airf. Carbonic acid . . 5T1 * This series of experiments was performed in the winter months, but in one conducted during the months of April, Hay, June, and July, I was able to detect blood-corpuscles in the putrid fluid after it was three months and seven days old ; so that blood-corpuscles appear to be much more persistent bodies than is in general imagined. t The oxygen was also estimated in this case, but unfortunately without a controlling experiment being at the same time performed, so it is of little value. The following is the result of the analysis. PHYSICAL AND CHEMICAL AGENTS UPON BLOOD. 699 No. 27. — In 100 parts of air. Oxygen . . 2'10 The analysis of the gas after twenty-four hours’ contact with the blood therefore stands thus : In 100 parts of air. Oxygen .... 2TCh n , . ., r n ITotal oxygen 7*21 Carbonic acid . . 5T1J Nitrogen . . . 92*79 As it is rather troublesome to carry the results of these analyses in the mind, I shall now give them in a tabular form, when it will be at once evident to any one who has given attention to the subject, that the chemical changes exerted upon air by putrefac- tion, in so far as they are here studied, are very different from the true respiratory ones previously alluded to. In 100 parts of air. Oxygen. Carbonic acid. Nitrogen. 1st portion of fresh blood 13-76 2-05 84-19 2nd same „ 60 hours old ... 2-88 3-69 93-43 3rd „ „ 136 „ 1-01 4-31 94-68 4th „ „ „ 184 0-00 4-91 95-09 5th „ „ 304 — 4-99 — 6th „ „ „ 688 — 5-11 — It is here seen that the process of putrefaction exerts, up to a certain extent, the same effect on the absorption of oxygen and exhalation of carbonic acid by the constituents of the blood, as was observed to be exercised by an increase of temperature. Thus we find that the older the blood becomes the more oxygen it extracts from the air, and the more carbonic acid does it at the same time yield. Here, however, the analogy stops. For we find that while in those cases where the normal respiratory action is such as to have produced the exhalation of more than 5 per cent, of carbonic acid, the oxygen does not entirely disappear from the air (see experiments 35 and 58, Part II.), and in those again where the oxygen has been entirely taken up by the blood it is again all returned to the atmosphere, as seen in the results of experiment 14 related at page 695. During the putrefactive process, on the other hand, the amount of oxygen absorbed is exceedingly great in proportion to the quantity of carbonic acid exhaled. Part II.— INFLUENCE OF CHEMICAL AGENTS ON THE BLOOD. Effect of Animal Peoducts. Snake Poison. For the purpose of studying the effect of animal poisons upon the reciprocal action of blood and atmospheric air, I obtained, through the kindness of the late Mr. Mitchell, 700 PROFESSOR HARLEY ON THE INFLUENCE OF Secretary to the Zoological Gardens, the loan of two African Puff Adders. They were 3 feet in length, and about 8 inches in circumference at the thickest part. The physiological action of animal poisons being as yet imperfectly understood, before alluding to the special action of the poison on the blood, I shall briefly relate the history of one of the experiments. The experiments were performed at University College, in the presence of my col- leagues, Professors Sharpey, Ellis, and Williamson. The serpents had eaten nothing during eight days, so it was supposed that their poison-bags were well charged with venom. A large dog was bitten by one of the snakes over the right eye. The immediate appearance of a drop of blood indicated the position of the wound. In three minutes the dog became very restless, and gave a low whine as if in pain. After moving about the room for ten minutes searching for a comfortable place to lie down on, he placed himself in the coolest part of the chamber, and laid his head on the cold stones, as if to relieve headache. He moaned as if in distress. In a quarter of an hour after he received his wound the pulse had fallen from 100 to 64 per minute. As the effects of the poison passed away the pulse gradually recovered, and in twenty-five minutes it was again as high as 96 per minute. In one hour after being bitten the dog had so far got over the effects of the poison as to be able to run about. The serpent was once more allowed to bite him. The same train of symptoms again appeared, but in a more intense degree, and within twenty-five minutes he had become insensible. He looked as if in a profound sleep, from which he could not be roused. The respirations were 40 per minute, and the pulse so feeble in the femoral artery that it was found impossible to count it. The pupils were dilated. Half an hour after being bitten the second time convulsive twitchings began to appear in the fore limbs and in the muscles of the neck. In ten minutes more the whole body became convulsed. The limbs were stretched out, and the head jerked backwards. During the convulsions the respirations rose to 90 per minute ; but they subsided to 40 in the intervals. The temperature of the rectum gradually fell in the course of one hour and a half from 38° to 35° C. In two hours the respirations were reduced to 9 per minute, the animal temperature at the same time being 34° C. The pulse was com- pletely imperceptible ; even the heart’s action could not be felt through the ribs. In two hours and a quarter the animal appeared to be dead; but on making an incision into the thorax he gave a gasp. After waiting some time, without observing any further sign of life, another incision was made, when he again gasped, but only once. On opening the thorax the heart was found pulsating at the rate of 60 per minute ; it was, however, more like a quivering than a true pulsation. The tissues of this and of the other animals killed by the puff adders presented a very strange appear- ance, namely, numerous extravasations of blood throughout the body, some small, some large. For example, in this animal there was an extravasation of blood into the ante- PHYSICAL AND CHEMICAL AGENTS UPON BLOOD. 701 rior mediastinum, and into the tissue of the pericardium, but no effusion into the peri- cardium itself. There were extravasations along all the great veins, into the cellular tissue of the pancreas, throughout the diaphragm, beneath the peritoneum, and all over the abdomen. The interior of the latter, indeed, looked exactly as if it had been sprinkled over with blood. A similar condition also existed in the subcutaneous cellular tissue. In fact, had the history of the case not been known, it would have been supposed that the animal had laboured under a severe form of purpura hsemor- rhagica. In the neighbourhood of the wounds there was great swelling, as well as an extrava- sation of brownish putrid looking blood. Everything pointed to blood poisoning. The state of the spleen merits special attention. It was of a dark bluish olive tint ; quite peculiar. I have never met with a similar hue in any other case of poisoning. On exposure to the air the blood became arterialized, and the organ then lost the strange appearance. The muscles were darker than usual. In the course of a few hours they passed into a state of rigor mortis, which was quite distinct seventeen hours after death. The brain was very anaemic, and showed no signs of extravasation. In the course of a few weeks after this experiment was made three of the puff adders died and were sent to me for examination. They were in exceedingly good condition, and beyond having fatty livers there was no apparent disease. On removing the poison from their poison bags and allowing it slowly to evaporate on a glass slide, beautiful crystals were observed to form in it similar to the specimens represented in the accom- panying figure. Fig. 2. Crystals from puff-adder poison. This crystalline body seems to be peculiar to this species of snake, as I failed to obtain it from the common adder, as well as from two specimens of Cobra, one from Morocco, and one from Egypt. 702 PROFESSOR HARLEY ON THE INFLUENCE OF Examination of the Blood. Under the microscope, the red corpuscles were in general normal in appearance. There were, however, a number of three-cornered ones to be seen, like what is some- times met with in the half-putrid blood of fish. There was also an excess of white corpuscles, which might have been due to the animal being in full digestion. After the blood had stood for some hours in a glass vessel, although not coagulated, it had deposited the corpuscles and left a layer of serum on the top*. Shaken with air it arterialized readily. It contained 0*235 gramme (3-64 grains) of urea per ounce. No sugar could be detected in it, yet after standing a couple of days it became quite acid. A quantity of this blood, after being thoroughly arterialized, was put into a receiver with 100 per cent, of air, and in order to make the experiment as exact as possible, a healthy dog was sacrificed, and a similar quantity of its blood treated in exactly the same manner. As this experiment was performed during the season of the year when the days were short, and I could not work in the laboratory after four o’clock, I carried the receivers home with me, and repeatedly agitated them during the evening, and pretty far on into the night. After twenty-four hours’ action the analyses of the gases gave the following results - 1st. Blood of healthy dog. Result : — No. 28. — In 100 parts of air. Oxygen . . . 19'TOOWj 20.109 Carbonic acid . 0*409J Nitrogen . . . 79*891 2nd. Blood of dog poisoned by puff adder. Result : — No. 29. — In 100 parts of air. Oxygen Carbonic acid Nitrogen . 17*09 1*09. •Total oxygen 18*18 81*82 It is here observed that there has been a marked difference in the action of the two bloods. The puff-adder poison seems to have accelerated the transformations and decompositions upon which the absorption of oxygen and the exhalation of carbonic acid by the blood depend. By placing the results in the form of a Table, this fact is rendered still more apparent. Oxygen. Carbonic acid. Nitrogen. Total oxygen. In 100 parts of atmospheric air 20-960 0-002 79*038 20-962 Ditto, after being acted on by pure blood 19*700 0-409 79*891 20-109 Ditto, after being acted on by poisoned blood.. 17*09 1-09 81-82 18-18 * On opening the other animals some hours after death the blood was found to he fluid, hut it coagulated after its withdrawal from the body. It formed a jelly rather than a clot. There seemed to be a marked dimi- nution in the amount of fibrin, as well as a thinning of the blood, in all the cases. PHYSICAL AND CHEMICAL AGENTS UPON BLOOD. 703 As these results are probably different from what most persons may have expected, it may be advisable briefly to relate the controlling experiments, at least so much of them as refer to the exhalation of carbonic acid. They were performed in a precisely similar manner, except that the proportion of blood to that of air was as one to three. 1st. Healthy dog. 1 volume of pure blood to 3 volumes of air. Twenty-four hours’ action at temperature under 12° C. Result : — No. 30. — In 100 parts of air. Carbonic acid . . . . O' 38 2nd. Blood of dog poisoned by puff adder. 1 volume of blood to 3 volumes of air. Twenty-four hours’ action at temperature under 12° C. Result : — No. 31. — In 100 parts of air. Carbonic acid . . . . 0-78 Here too it is seen that, although treated in every respect alike, the blood of the poisoned dog exhaled more carbonic acid than that of the healthy animal. Uric Acid. As uric acid, although a normal constituent of the animal body, may be regarded in the light of an animal poison, inasmuch as it is an effete product, it was experimented with in the following manner. Two portions of well defibrinated sheep-blood, after being thoroughly arterialized, were placed in receivers with 100 per cent, of atmospheric air. To one of them was added 0-2 gramme (3T grains) of pure uric acid prepared from human urine (the uric acid was thoroughly pounded in distilled water and then mixed with the blood in a mortar ; 62 grammes of blood was the quantity employed). The pure blood was treated in the same way, but with distilled water alone. After twenty-four hours’ action under identical circumstances, the air of the receivers was analyzed. Air after being in contact with pure blood of sheep during twenty-four hours. Re- sult : — No. 32. — In 100 parts of air. Oxygen . . . aS-901Total i5.85 Carbonic acid . 1*95 J Nitrogen . . . 84 T5 Air after being in contact with sheep’s blood to which uric acid was added. Result : — No. 33. — In 100 parts of air. Oxygen . . . 13-171Total oxygen 15-79 Carbonic acid . 2*62 J Nitrogen . . . 84-21 5 E MDCCCLXV. 704 PROFESSOR HARLEY ON THE INFLUENCE OF It is thus seen that the presence of an abnormal amount of uric acid in blood hastens the chemical decompositions and transformations upon which the absorption of oxygen and exhalation of carbonic acid depend. Animal Sugar. As an illustration of the action of animal sugar upon blood, the following experi- ment may be cited. To a third portion (62 grammes) of the same blood as was used in the two preceding experiments, 04 gramme (6 -2 grains) of sugar obtained from the urine of a diabetic patient were added. The sugar was first made into a syrup with a small quantity of distilled water, and then mixed in a mortar with the blood. In order to avoid all possibility of error, the pure blood, as before stated, was treated in the same way with distilled water alone. Result : — No. 34. — In 100 parts of air. Oxygen ... 15 01 j/potaj oxygen 16-62 Carbonic acid . 1*61 / Nitrogen . . . 83-38 It is here seen that the animal sugar had the effect of retarding the respiratory changes produced in atmospheric air by blood, less carbonic acid being exhaled, and a smaller amount of oxygen absorbed ; just the opposite effect as was observed to follow the addition of uric acid to blood. The subjoined Table shows this more distinctly. Sheep’s blood. Twenty-four hours. 100 per cent, of air. Oxygen. Carbonic acid. Nitrogen. Total oxygen. Pure blood 13-90 1-95 84-15 15-85 Blood plus uric acid 13-17 2-62 84-21 15-79 Blood plus sugar 15-01 1-61 83-38 16-62 Action of Vegetable Products on Blood. Hydrocyanic Acid. The following are examples of the influence of hydrocyanic acid on the action of blood on the respiratory gases. A quantity of perfectly fresh ox-blood was taken and carefully switched until freed, as far as possible, of its fibrin. After being thoroughly arterialized, it was then divided into several portions of 62 grammes each, and treated in the usual manner in a room of moderate temperature during twenty-four hours. Pure defibrinated ox-blood with 100 per cent, of atmospheric air. Twenty-four hours’ action. Result : — PHYSICAL AND CHEMICAL AGENTS UPON BLOOD. 705 No. 35. — In 100 parts of air. Oxygen . . . 10-42jTotal oxygen 16.47 Carbonic acid . . 5-05 J Nitrogen . . . 84"53 Defibrinated ox-blood with 6 drops (20 per cent, strength) of hydrocyanic acid. 100 per cent, of air. Twenty-four hours’ action. Result : — No. 36. — In 100 parts of air. Oxygen . . . 16-321Total 18.23 Carbonic acid . 1*91 J Nitrogen . . . 81-77 It is thus seen that the effect of hydrocyanic acid is to retard those transformations and decompositions upon which the interchange of the respiratory gases depend. The effect is well marked in this case, but it is even more so in a case of poisoning in the human subject, which I shall immediately refer to ; meanwhile the results of these two analyses are — Oxygen. Carbonic acid. Nitrogen. Total oxygen. In 100 per cent, of air from pure ox-blood 10-42 5-05 84-53 15-47 Ditto plus hydrocyanic acid 16-32 1-91 81-77 18-23 Action of Hydrocyanic Acid on Human Blood. A quantity of blood was removed from the heart and great vessels of a healthy well- developed young woman, aged 19 years, who died within half an hour after swallowing a couple of drachms of bitter almond oil. The blood was still fluid forty-eight hours after death, and yielded a small quantity of hydrocyanic acid by distillation. A portion of the blood, after being thoroughly arterialized by agitation with renewed portions of air, was put into a receiver with 100 per cent, of atmospheric air, and kept twenty-four hours (with occasional agitation) in a room of an average temperature of 15° C. At the end of the twenty-four hours the air confined with the blood was analyzed, with the subjoined result : — No. 37. — In 100 parts of air. Oxygen 19-56 Carbonic acid .... O'OO Nitrogen 80-44 It is here seen that the effect of hydrocyanic acid is the same in the body as out of it, namely, to arrest respiratory changes. 5 e 2 706 PROFESSOR HARLEY ON THE INFLUENCE OF Nicotine. Various experiments were performed with nicotine, and it was invariably found to produce the same result ; namely, to retard the normal oxidation processes in blood, and at the same time to diminish the exhalation of carbonic acid. The following expe- riment may be quoted as an illustration of the fact. Two portions (62 grammes) of defibrinated ox-blood, after being thoroughly arte- rialized, were placed in receivers with 100 per cent, of atmospheric air, and both were treated during twenty-four hours exactly alike, except that to one was added 6 drops of chemically pure nicotine. Gas from pure ox-blood after twenty-four hours’ action with 100 per cent, of atmo- spheric air. Result : — No. 38. — In 100 parts of air. Oxygen . . .14 66 0Xygen 17*04 Carbonic acid . . 2-38.1 Nitrogen . . . 82-96 Gas from ox-blood after twenty-four hours’ action with 6 drops of nicotine. 100 per cent, of atmospheric air. Result : — No. 39. — In 100 parts of air. Oxygen . . . 19-601 Carbonic acid . 1*49 J Nitrogen . . . 78-91 Total oxygen 21-09 It is thus seen, as was before said, that nicotine diminishes the power of the blood to take up oxygen and give off carbonic acid, and thereby become fitted for the purposes of nutrition. Oxygen. Carbonic acid. Nitrogen. Total oxygen. In 100 per cent, of air from pure ox-blood 14-66 2-38 82-96 17-04 Ditto plus nicotine 19-60 1-49 78-91 21-09 Woorara Poison. Two portions of defibrinated sheep’s blood, after being thoroughly arterialized, were placed in receivers with 100 per cent, of atmospheric air, and kept, with occasional shaking, at a temperature of 15° C. during twenty-four hours. The treatment of the two portions of blood only differed in this respect, that to one nothing was added, while 0-01 gramme of woorara was put into the other. The amount of blood in each case was 62 grammes. PHYSICAL AND CHEMICAL AGENTS UPON BLOOD. 707 Air from pure sheep’s blood. Twenty-four hours’ action. Result : — No. 40. — In 100 parts of air. 100 per cent, of air. Oxygen . . . Carbonic acid . Nitrogen . . 12-42) o-7o}Total oxysen 13-12 86-88 Air from sheep’s blood plus woorara. Twenty-four hours’ action, air. Result : — No. 41. — In 100 parts of air. Oxygen . . . Carbonic acid . Nitrogen . . ^TGo}^0^ oxy§en 81-72 100 per cent, of It is thus seen that woorara has the peculiar effect of diminishing oxidation, and at the same time increasing the exhalation of carbonic acid gas. Oxygen. Carbonic acid. Nitrogen. Total oxygen. In 100 per cent, of air from purel sheep’s blood J 12-42 0-70 86-88 13-12 Ditto plus woorara 16-68 1-60 81-72 18-28 For the purpose of studying the action of woorara upon the blood of the living animal, I injected under the skin of a dog an aqueous solution of five grains of the poison*. The animal soon became paralyzed and died, as is usual in those cases, from the cessation of the respiratory movements. The heart’s action continued vigorous for some time after apparent death : a portion of this dog’s blood was then taken and thoroughly arterialized by repeatedly shaking it with renewed quantities of air. The blood was then enclosed in a receiver with 100 per cent, of atmospheric air, and treated in the usual way during twenty-four hours. The result of the analysis was as follows : — No. 42. — In 100 parts of air. Oxygen . . . Carbonic acid . Nitrogen . . 1 glj-Total oxygen 20-19 79-81 If we compare this result with the analysis of air from the blood of a healthy dog (No. 28) already given (page 702), we shall find that the effect of the woorara has been like that of snake poison, to increase the chemical decompositions and transformations in the blood, upon which the exhalation of carbonic acid depend. * For the woorara employed on this occasion I am indebted to the liberality of Charles Watertox, Esq., of Walton Hall, the well-known author of the ‘ Wanderings.’ He obtained it in Guiana in 1812, and though it is consequently half a century old, it is still an exceedingly active poison. 708 PROFESSOR HARLEY ON THE INFLUENCE OF In 100 parts of air. Oxygen. Carbonic acid. Nitrogen. Total oxygen. Healthy blood of dog 19*700 0-409 79*891 20-109 Blood of dog poisoned with woorara ... 18-680 1-510 79*810 20-190 It will be observed that there is a slight discrepancy between the amount of oxygen absorbed in this and the other experiment on the action of woorara out of the body ; for here the oxidation has been greater than in the healthy animal. This most pro- bably arises, however, from some accidental cause, due to the blood being taken from different animals and not operated on in the same day. Unfortunately it is impossible to operate on both healthy and poisoned blood of the same animal at the same time, so that all our experiments of comparison on the blood of living auimals are liable to the source of error arising from the state of the body and the constitutional peculiarity of the animal. My former statement regarding the action of woorara, namely, that it diminishes oxidation and increases the exhalation of carbonic acid, at least in sheep’s blood, is I have little doubt correct, as I have invariably found it to be so. I might here quote other experiments in proof of this assertion, but in order to prevent unneces- sary repetition, shall delay doing so till the action of woorara is compared with that of other substances. Antiar and Aconitine. For the sake of brevity I shall take these two poisons together. As is well known, their physiological action on the animal body is, as nearly as possible, identical. They are both powerful cardiac poisons. So powerfully, indeed, do they act in this way, that when given to frogs they stop the action of the heart while the animal is otherwise sufficiently well to be able to spring about. This is the reverse of woorara, which allows the heart’s action to continue long after the rest of the body is dead. Hence arises the saying that we may have a dead heart in a living body with antiar and aconitine, and a dead body with a living heart with woorara. The result of the following experiment forcibly illustrates the truth of the latter statement. A healthy full-grown frog was pricked with the point of a poisoned arrow, and in the course of a few minutes its limbs gradually became paralysed. The paralysis soon extended itself over the body, the animal ceased to breathe, and in the course of a few minutes more was dead. On examining the heart about an hour afterwards, that organ, and that organ alone, was found still alive. Death could not be said here to have usurped its power, for it slowly and regularly pulsated as in life. On the following day the heart still continued to beat although the tissues surrounding it had assumed the appearance of death. Forty-eight hours after the animal had been poisoned its heart still continued to act regularly, and even seventy-two hours afterwards the action of the ventricle and auricles, though feeble, was yet distinct. On the fourth day (ninety-six hours after death) part of the heart died, the left auricle alone continued to pulsate. But now, not only was the frog dead, but its lower limbs were already shrunk PHYSICAL AND CHEMICAL AGENTS UPON BLOOD. 709 and withered. I then made an attempt at resuscitation, and exactly 100 hours after the animal died I put it into a moist warm atmosphere, and there retained it till the temperature of its body was slightly raised. This treatment had the effect of restoring the irritability of the heart, and on touching the ventricle with a point of my pen it resumed its pulsations, and during several minutes the contractions, first of the auricles and then of the ventricles, continued rhythmically ; even the pulsations in the large vessels attached to the heart also became distinctly visible, and continued so with regu- larity for upwards of a quarter of an hour. The chemical action of antiar and aconitine on the blood, like their physiological action on the nervous system, are as near as possible alike. First, as regards their influence on the exhalation of carbonic acid. Two portions of thoroughly defibrinated and well arterialized sheep’s blood, 62 grammes each, were put into receivers with 100 per cent, of air. To the one 0-01 gramme of antiar dissolved in water was added ; to the other a similar quantity of pure aconitine dissolved in faintly acid water. After twenty-four hours’ action "the air in the receivers was analyzed with the following results. Antiar'*, twenty-four hours’ action, 100 per cent, of air. Result : — No. 43. — In 100 parts of air. Carbonic acid . . . 2 '05. No. 44. — Result of analysis of air from blood with aconitine in 100 parts of air. Carbonic acid . . . 2*02. It is thus seen that the influence of antiar and aconitine on the exhalation of carbonic acid is very similar. I shall now quote a series of experiments in which the influence of these substances with that of woorara is compared. A quantity of defibrinated sheep’s blood was taken seventeen hours after the death of the animal, and after being completely arterialized it was divided into four portions, each of which was put into a receiver with 100 per cent, of atmospheric air. They were all treated precisely alike, except that to one 0-092 gramme of antiar was added, to another 0-092 gramme of aconitine, and to a third 0-092 gramme of woorara. The fourth portion was retained pure in order to form a standard of comparison. After twenty-four hours’ action the air was analyzed, with subjoined results. 1\ o. 4b. — Air from pure Oxygen . . . Carbonic acid . Nitrogen . 12-05}Total oxygen 15 '81 84-19 * For the antiar employed in these experiments I am indebted to the kindness of Professor Shakpey. 710 PROFESSOR HARLEY ON THE INFLUENCE OF No. 46. — Air from blood plus woorara, in 100 parts of air. Oxygen . . Carbonic acid . Nitrogen . . 12.gg}Total oxygen 19-83 80-17 No. 47. — Air from blood plus antiar, in 100 parts of air. Oxygen . . . Carbonic acid . Nitrogen . . 1 2-98} 1 oi rTota-l oxygen 13-99 86-01 No. 48. — Air from blood plus aconitine, in 100 parts of air. Oxygen . . . Carbonic acid . Nitrogen . . o!!} Total oxygen 12-96 I’oU J 87-04 By placing these results in a tabular form the comparative value of each of the factors will be made more apparent. Oxygen. Carbonic acid. Nitrogen. Total oxygen. In 100 parts of air from pure blood 13-76 2-05 84-19 15-81 Blood plus woorara 16-85 2-98 80-17 19-83 „ „ antiar 12-98 1-01 86-01 13-99 „ „ aconitine 11-66 1-30 87-04 12-96 The similarity in the action of antiar and aconitine, and the dissimilarity between their action and that of woorara, are well illustrated in the above Table. The woorara dimi- nishes oxidation and increases the exhalation of carbonic acid. Antiar and aconitine increase oxidation and diminish the exhalation of carbonic acid gas. Strychnine. In order to ascertain the influence of strychnine, a quantity of fresh calf’s blood was shaken with renewed portions of atmospheric air until it had become thoroughly saturated with oxygen. It was then enclosed in a receiver with 100 per cent, of ordi- nary air, corked up, and kept in a room of moderate temperature during twenty-four hours. A second portion of the same blood (62 grammes) was similarly treated in every way except that it had 0-05 gramme of strychnine added to it. During the twenty-four hours the receivers were as usual frequently agitated to favour the mutual action of the blood and air. At the end of this period the composition of the gas in the receivers was found to be — PHYSICAL AND CHEMICAL AGENTS UPON BLOOD. 711 Gas from pure calf’s blood, twenty-four hours’ action with 100 per cent, of air: — No. 49. — In 100 parts of air. Oxygen . . . Carbonic acid . Nitrogen . 12-10) 5-94) 81-96 ■Total oxygen 18-04 Gas from calf’s blood plus strychnine, dissolved in a minimum of very dilute hydro- chloric acid, twenty-four hours’ action with 100 per cent, of air : — No. 50. — In 100 parts of air. Oxygen . . . Carbonic acid . Nitrogen . . 17*82) 2<7gjTotal oxygen 20-55 79-45 Thus it is seen that strychnine is one of those substances possessing the strange pro- perty of preventing the chemical decompositions and transformations of the constituents of the blood upon which the absorption of oxygen and exhalation of carbonic acid depend. Oxygen. I Carbonic acid. Nitrogen. Total oxygen. In 100 parts of gas from pure calf’s blood 12-10 5-94 81-96 18-04 Ditto plus strychnine 17-82 2*73 79-45 20-55 The next point to determine is, does strychnine act in the same manner on blood in the living animal as out of it \ The results of the two following experiments seem to indicate this, but as they were performed with the view of solving an entirely different question not requiring any con- trolling experiments, they had none made with them, and therefore they can only be taken for what the results of single experiments are worth. Into the peritoneal cavity of a healthy full-grown cat was injected a solution of -^tli of a grain of strychnine. In five minutes the animal became convulsed, and in four minutes more it died. On opening the body eight minutes after death, some of the blood was found already coagulated in the greater vessels, and the portion that was fluid coagulated as soon as it flowed into a capsule. The blood had a dark purple colour, and when shaken on the sides of a glass looked almost grumous and granular, as if the corpuscles were broken up, and had allowed their contents to escape. Under the microscope plenty of healthy red corpuscles were seen, many of them running into rolls ; but besides these, although there were no broken-up cells to be seen yet there were an unusual number of small granules in the field. The animal was fasting, never- theless there were also a considerable number of white corpuscles present. The blood contained 0-22 gramme of urea to the oz. (0-709 per cent.) and abundance of sugar. Gas from blood of cat poisoned with strychnine, twenty-four hours’ action with 100 per cent, of air in a room of moderate temperature : — mdccclxv. 5 F 712 PROFESSOR HARLEY ON THE INFLUENCE OF No. 51. — In 100 parts of air. Oxygen . Carbonic acid . Nitrogen . . 10-6o}Total 0xygen 17'63 82-37 It is thus seen that the blood of the poisoned animal yields even a smaller quantity of carbonic acid than the blood to which strychnine has been added out of the body, while the quantity of oxygen that has disappeared is the same in both cases. Brucine. Besides strychnine the alkaloid brucine is also obtained from nux vomica, and the following experiment was made with the view of testing if it had a similar action upon blood. The experiment in this case, however, was somewhat extended in order to com- pare its action with that of two other substances, namely, quinine and morphia, and as the results obtained form rather an interesting series, I shall give them consecutively. A quantity of perfectly fresh calf’s blood, after being defibrinated and thoroughly saturated with oxygen by repeatedly shaking it with renewed quantities of air, was divided into several portions of 62 grammes each. To the first nothing was added ; to the second 0-005 gramme of brucine ; to the third 0-005 gramme of quinine ; and to the fourth 0-005 gramme of morphine : these alkaloids were all dissolved by the aid of a minimum quantity of hydrochloric acid. The different portions were then enclosed in receivers with 100 per cent, of air, and treated in the usual manner, with occasional agitation, in a room of moderate temperature during twenty-four hours. At the expi- ration of that period the air was analyzed, with the following results : — No. 52. — The air from pure calf’s blood contains in 100 parts of air — Oxygen . . Carbonic acid . Nitrogen . . o ^j-Total oxygen 10-11 89-89 The air from the calf’s blood plus brucine contained — No. 53. — In 100 parts of air. Oxygen. . . . 11-631 n_ , . . , _ _ . ITotal oxygen 13-97 Carbonic acid . . 2*34 J Jb Nitrogen . . . 86-03 It is thus seen that brucine acts like strychnine, but in a much less marked degree. Quinine. As has just been said, to another portion of the same blood as was employed in the two preceding cases, 0-005 gramme of quinine was added. PHYSICAL AND CHEMICAL AGENTS UPON BLOOD. 713 No. 54. — In 100 parts of air. Oxygen . . . Carbonic acid . Nitrogen . . 12-05}T°tal oxygen 16'77 83-23 Morphine. To the fourth portion of the same blood 0-005 gramme of morphine dissolved in water acidulated with hydrochloric acid was added, and the result was as follows : — No. 55. — In 100 parts of air. Oxygen . . . Carbonic acid . Nitrogen . . 17 J7J.Total oxygen 18-17 81-83 It is thus seen that these different substances, Brucine, Quinine, and Morphine, with hydrochloric acid as their solvent, have all acted on the blood in the same manner, retarding oxidation, and decreasing the exhalation of carbonic acid, but in very different degrees. By placing them in a tabular form, the difference in their respective results will be still better appreciated. Oxygen. Carbonic acid. Nitrogen. Vol. at 0° C. and 1 metre pressure. In 100 parts of air: — After being acted on by pure blood 6-64 3-47 89-89 10-11 Ditto by blood plus brucine 11-63 2-34 86-03 13-97 „ „ quinine 14-72 2-05 83-23 16-77 „ „ morphine 17-17 1-00 81-83 18-17 Composition of atmospheric air employed \ in the experiments J 20-96 0-002 79*038 20-962 It ought not to be forgotten that the blood in all of these cases was not only taken from the same animal, and the product of one bleeding, but in every respect, both before and after being put into the receivers, subjected to precisely similar influences, under identical conditions. The difference in the results must therefore be regarded as entirely due to the effect of the alkaloids upon the blood. Action of Anesthetics on Blood. Chloroform. From the fact that of all anaesthetics at present employed chloroform holds the first rank, its action upon blood was carefully studied. The results obtained were exceedingly uniform and all tending to one conclusion, namely, that this substance has a powerful effect in retarding those chemical transformations and decompositions upon which the process of respiration depends. 1st. As regards the visible effect of chloroform upon blood. If 5 per cent, of pure chloroform be mixed with the freshly-drawn blood of a healthy 5 f 2 714 PROFESSOR HARLEY ON THE INFLUENCE OF animal, it will be found that within half an hour the blood will assume a brilliant scarlet hue. If the vessel containing it be now agitated, so as to mix the blood with atmospheric air, a quantity of colouring-matter adheres to the sides of the glass, and on allowing it again to stand for a few minutes, a red somewhat flocculent precipitate is deposited. This precipitate is not hsematin alone. On the contrary, it consists of a dirty red-coloured protein substance, whereas the dissolved or suspended pigment has a vermilion hue. If the blood be kept at rest for some hours — laid aside during the night — it will to a certain extent lose its brilliant colour, and assume that of the red precipitate previously spoken of. At the same time it will be found to solidify into a gelatinous sticky paint-like mass. If instead of 5 per cent., 50, or still better 100 per cent, of chloroform, be added to venous blood either defibrinated or non-defibrinated, it causes it at once to assume the arterial hue, and this is still more marked if the vessel be well agitated. The blood rapidly solidifies and retains its vermilion tint for many hours, even days. It not unfrequently happens that blood to which chloroform has been added crystallizes on solidifying, more especially when only 5 per cent, of chloroform is used. Serum is not solidified by chloroform in the same way, but it deposits a white preci- pitate. 2nd. Microscopical appearances presented by blood after being acted upon by chloro- form. If 5 per cent, of chloroform be added to blood, and the mixture well shaken, it will be found on examining it with the microscope that, although very many of the red corpuscles have disappeared, their walls having been dissolved, and their contents escaped, the great majority of them remain intact. Even 100 per cent, of chloroform fails to destroy totally the blood-cells. Great numbers of the red cells are, however, destroyed, and their contents diffused throughout the liquid. It is indeed the contents of the red corpuscles that crystallize. The crystals are in many cases quite red. They are prismatic in shape, and about four times as long as they are broad. The crystals are always most readily obtained from the blood of animals that have been poisoned with chloroform, but only after an additional quantity is added. They are insoluble in chloroform, ether, alcohol, and water. 3rd. Chemical action of chloroform on blood. Two equal portions of defibrinated and arterialized ox-blood, equal to 62 grammes each, were placed in receivers with 100 per cent, of atm os pheric air, and kept in a room of moderate temperature during twenty- four hours. Both bloods were treated precisely alike, except that while the one was kept in its normal state, the other had three drops of chloroform added to it. Gas from pure ox-blood, twenty-four hours’ action with 100 per cent, of atmospheric air : — No. 56. — In 100 parts of air. Oxygen. . . . 10-42} Carbonic acid . . 5-05}T°tal 0X^en 1547 Nitrogen . . . 84-53 Fig. 3. Crystals obtained from blood by means of chlo- roform. PHYSICAL AND CHEMICAL AGENTS TJPON BLOOD. 715 Gas from ox-blood plus chloroform, twenty-four hours’ action, 100 per cent, of atmo- spheric air : — No. 57. — In 100 parts of air. Oxygen . . Carbonic acid . Nitrogen . . 1 Q.7Ci 1, a are the coordi- nates of the ray : two of them, r, s, indicating its direction, the remaining two, §, " - instead of r, s. It may be sufficient here to state that a configuration of rays, if represented by three linear equations, in which the coordinates r, s, g, a are replaced by t, u, vx, vy, becomes a hyperboloid. 9. A configuration of axes represented by three linear equations would be a para- boloid if the coordinates x, y , zt, zu were employed, but becomes a hyperboloid if these coordinates are replaced by p, q, ar, z. We shall here consider the last case only, and may for that purpose directly replace the equations (6)-(ll) by the following ones: — ap +bq = 1, (12) ca +d»= 1, (13) a'p +c'ar =1, . (14) Vq +d'x= 1 (15) a"p-\-d"z= 1, (16) b"q+d,B = 1 (17) Any three of these equations, involving six constants, are sufficient to determine the con- figuration. If, after having replaced^?, q, ar, z by _£?, _£^, i, I, x y x y we regard x, y, zt, zu as variable, (14) and (15) may be written thus, x=a!z-{-c', y=b'z+d\ representing within the planes XZ, YZ two right lines (AA, BB') which are the locus of points (A, B) where the axes of the configuration meet the two planes. In regarding vr and z as coordinates of a right line, the equation (13), being written thus, ct-\-du=l, represents a given point (E), x=c, y=d , enveloped within XY by the projections of axes. Therefore all axes of the configura- tion intersect a third right line (CC') parallel to OZ and meeting XY in E. Hence we conclude that the configuration represented by the three linear equations is a hyperboloid. Its axes meet three given lines, two of which, AA', BB', fall within XZ, YZ, while the third, CC', is parallel to OZ. 730 DE. PLUCIvEE ON A NEW GEOMETEY OF SPACE. The plane BOA passing through O and an axis AB is represented by the equation The equation (12) being with regard to p and q of the first degree, indicates that all such planes, containing the different axes of the configuration, intersect each other along a given right line DD' passing through O. Hence all axes meet a fourth right line, itself confined within the hyperboloid. The complete determination of the hyperboloid presents no difficulties. We may for instance find its centre and its axes by determining the shortest distance of any two of the axes generating it. 10. Let a congruency either of rays or axes be represented by two linear equations. In adding to these equations two new ones, likewise of the first degree, there exists only one ray or axis the coordinates of which satisfy simultaneously the four linear equations. Two new equations of this description are obtained if, among the rays or axes of the congruency, we select those either passing through a given point, or confined within a given plane. In the case of rays, let (fi, ?/, z') be a given point, then we get %!=rz,Jr%, y'=sz'~ J-<7 in order to express that all rays meet in that point. Let t'x+u'y+v'z+ 1=0 be the equation of a given plane, then we get ir-\-u!s-\-v— 0, t'g-\-u'(r- {-1=0 in order to express that the rays lie within that plane, Again, in the case of axes, let (if, u', v ') be a given plane, then we get the new linear equations t'x + v'zt = 1 , —pv' -f- sr, or u'x-\-v'zu= 1, u'=qv'-\-z, in order to express that the axis is confined within that plane. Let in regarding x/, y\ zr as constant, t, u, v as variable, 1 = 0 represent a given point, then we get a?p+tfq+z!= 0, odvs-\-y'x,-\- 1 = 0 in order to express that the axes pass through that point. Hence In a congruency represented by the system of two linear equations , there is one single ray or axis passing through any given point of space, as there is one single ray or axis confined within a given plane. DE. PLUCKEE ON A NEW GrEOMETEY OF SPACE. 731 11. In order to represent a congruency of rays, we shall here make use of the coor- dinates t, u, vx, vy. Let At +B u +0^ +Dyy +1=0, At + B'm + C'vx + D'Vy +1 = 0 be its two equations. By successively eliminating each coordinate, we get four equations of the following form, at -\-bu ~{-cvx +1 = 0, dt -\-b'u -\-dvy +1=0, a"t-\-c'vx+d'Vy +1=0, b"u + dvx-\- d"Vy +1=0, any two of which involving six constants may replace the two primitive equations, the remaining two being derived from them. The first two of these equations, if t , u, vx and t, u, vy be considered as plane coordi- nates, represent two points (U, V) the coordinates of which are x=a, y=b, z—c , . (U) x=za', y—b\ z=d, (V) Consequently the six constants upon which the congruency depends, if referred to the three axes of coordinates OX, OY, OZ, are determined by means of the two points U and Y. Hence is derived the following construction of rays of the congruency. Trace through the two points U, V any two planes which intersect each other along a right line confined in the plane XY, and meeting OX, OY in the points D, F. Let E, G be the points where the two planes meet OZ. We shall get within the planes XZ, YZ the projections of a ray of the congruency by drawing DE, FG. The ray (AC) thereby completely determined will intersect the plane XY in the point C, the coordi- nates of which are x=]=OD, y=l= OF. If a plane be traced passing simultaneously through both points U, V, both intersec- tions E, G falling into one point A', the corresponding ray of the congruency A'C' intersects OZ. If the right line UV be projected on YZ, XZ, the projections meet OZ in two points A", A!". In these points OZ is intersected by the rays of the congruency parallel to OX, OY. The ray parallel to OZ is obtained by the point C" where it meets XY. The coordinates of C" are x=OB", Y=OF", D" and F" being the points where the projection of UV intersects OX and OY. Thus occurs to us the construction of rays passing through any point of OZ and any point of XY. We cannot go further into detail here. 732 DE. PLUCKEE ON A NEW GEOMETEY OE SPACE. 12. Again, let a congruency of axes be represented by the equations Atf+By +C zt -\-~Dzu +1=0, A'x + B'y + C % + B'zu + 1 = 0. By successively eliminating zu and zt we may replace these equations by the following two, ax-\-by -\-czt +1 = 0, dx-\-b'y +<+M+l=0, the six new constants of which are derived from the primitive constants. In regarding x, y, zh zu as point-coordinates (where z may be written instead of zt and zu), the last equations represent two planes. The six coordinates of both planes, t=a, u=b, v=c, t=a', u=V , v=d, are the six constants of the congruency, consequently the congruency is determined by means of these two planes and the axes of coordinates. Suppose both planes to be known. Draw any right line meeting them in M and M7, project M on XZ and M' on YZ. The right line joining the two projections B and A is an axis of the congruency. If we project on>XZ and YZ any point of the right line JK along which both planes intersect each other, the right line joining both projections, B', A', is an axis parallel to XY. All axes obtained in that way meet, within XZ and YZ, both projections of JK. Hence the axes of the congruency parallel to XY constitute a paraboloid. The ray within XY is obtained by projecting the point where the traces of both planes meet on OX and OY and joining both projections, B" and A", by a right line, See. 13. After these preliminary discussions we shall now proceed in a more systematic way, and henceforth exclusively make use of the coordinates r, s, g, +(B-DZ>+(l+IV+Dy)=0 (3) This equation being of the first degree with regard to the remaining variables r and s, shows that all corresponding rays are parallel to a given plane, and therefore confined DR. PLtJCKER ON A NEW GEOMETRY OF SPACE. 733 within the plane of that direction and passing through the point {x\ y\ z'). By replacing in the last equation r and s by and j~j, we obtain, in order to represent that plane, the following equation, (A-E^-^)+(B-D^(y-y)4-(lH-E^+Dy)(2-^)=0. ... (4) 14. Again, this equation being, with regard to (x1, y\ z1), of the first degree, proves that, conversely, all rays confined within a given plane meet in the same point of that plane. 15. A complex the rays of which are distributed through infinite space in such a way that in each point there meet an infinite number of rays constituting a plane, and, conversely, that each plane contains an infinite number of rays meeting in the same point, may be called a linear complex of rays. We may say, too, that, with regard to the complex, points and planes of the infinite space correspond to each other ; each plane containing all rays which meet in the point placed within it, and each point being tra- versed by all rays which are confined within the plane passing through it. 16. A linear complex of rays is represented by the linear equation (1), but it is easily seen that this equation is not the general equation of a linear complex. The following considerations lead us to generalize the preceding developments and to render them by generalizing more symmetrical. Hitherto we determined a ray by its two projections within XZ, YZ, x—rz- f§, y=sz+a, whence its third projection within XY is derived, ry—sx—ra—s% (5) This equation furnishes the new term (r+F(5§— r+(B+r^-D2,>+(C+Ea/+Dy>=A^+By+C/, . . (9) and reduced also to the following symmetrical form, A(x — x') + B (y — y ) -f C(z — z') + D (y'z — z'y) + E (a/z — z'x ) + F(x!y —y'x) = 0 . (10) 18. We may directly prove that all rays confined within a given plane meet in the same point. The equation of this plane being t'x-\-u'y-{-v'z-\-,w'= 0, . (11) we get, in order to express that a ray falls within that plane, the following three equa- tions, i}r-\-v!s-\-v' =0, 1j Q ?{/ = 0, w's—v'a—{rG—sq)t'= 0, each of which results from the other two. Between these equations and the equation of the complex (r + C^-Aw'-Ew'=0, . . . (12) being linear with regard to the two remaining variables s and -Ez=0.J Accordingly these equations represent the planes corresponding to points moved to an infinite distance along OZ, OY, OX. By combining each of the equations (18) with (17), we get the rays conjugate to the axes of coordinates OZ, OY, OX, forming a triangle, the angles of which fall within the three planes of coordinates, XY, XZ, YZ, into the corresponding points. 24. By putting w — 00, the equation (15), representing a point corresponding to any given point d), becomes D£+Ew— Fw=0, and then indicates that the point corresponding to the infinitely distant plane of space falls itself, at an infinite distance, along a direction which may be represented by the equations x y z D — E=F’ (19) while, if rectangular coordinates were supposed, D^+E x= Z~E==Z«’ B A z = 0, x= P = 5 y=Y=yv, whence may be derived the following relation, xvyt2u_ _ j In putting C= — 1, the right line conjugate to OZ, if regarded as an axis, may be determined by its four coordinates [5], j)=A, c[— B, bt=D, ^=E. These coordinates therefore are four of the constants of the complex Ar-f-Bs+D•••••••• (23) D<7+Eg+F(sg — r, and B' its projection on XY. The double area of the triangle POP' divided by P'P is a constant, and equal to Jc. 33. In order to generalize, we may start from the equation Ar+Bs+C-t-D)) Bt—Au—Fw ? V B3-D$ + F£ — C t -f- A u -f- >1 u > ip 1 1 Cm — Bv — Dw — £ t = — (AD— BE+CF). } 34. In starting again from the equation (26), sg — ro)(5°f0— r°G°) =k\ Not any two conjugate right lines intersect each other; if congruent they belong to the complex. 35. A linear complex depends upon five constants, four of which fix in space the position of its axis. In the case of the equations (23), this axis falling within an axis of coordinates, there remains only one constant. The position of the axis of the com- plex and its remaining constant may be determined by means of the five independent constants of the general equation (7). For that purpose we shall make use of the transformation of coordinates. If the axes of coordinates be changed, the coordinates of a ray change at the same time, and we get formulae analogous to the formulae in the case of ordinary coordinates, in order to express the coordinates of one system by means of the coordinates in the other. 36. Let x=rz+<>, y=sz+( 7 be the equations of a ray referred to the system of coordinates ( x , y, z ). If referred to another system ( x y\ z'), its coordinates will be replaced by new ones (r', s', q, sma— — rff =— : • cos a + r sin a «§ g — § . . . . (42) • • • • (43) In order to pass from the first system of coordinates to the second, r, s, g, ', d are to be replaced by one another, while the sign of a is to be changed. Thus we get the following formulae : — sin ci -f- r1 cos a i — 7 ’ cos a — r sin a § = a = cos ci — r sin a V cos ci — r sin ci (s' g' — r'a') sin « + c' cos « cos u—r1 sin « (44) ( s'p 1 — rl + F(sf — r] E2 cos2 0 cos2 0 D2 By making use of the formulae (34), the equation of the complex (7) becomes (A cos 05 -|- B sin a)r'—( A sin 05— B cos a )s' + (E cos 05 + D sin u)g' — (E sin 05 — D cos oo^o^ — C F — rV)=0, and may be written thus, AV+B's+C'+D'<7+F(s£-r— F sin CQ + D'((slf'— /'— rV) cos a’ sin £) = 0, and may be written thus, AV+ B"s + C" + F"(sg—rc) = 0, (48*) on omitting the accents of the coordinates and putting D' cos £=F' sin A"=(A'F-C'D')^, B"= — B', C"=(A'F'+A'D')^, (49) F"=(D'2+F2)C-^. 42. Finally, the origin may be moved within XY to a point the coordinates of which are #° and Accordingly the equation of the complex, on replacing f and c r by g-\-x° and +(CH-D^+E^)=:0. 748 DE. PLUCKEE ON A NEW GEOMETEY OF SPACE. If there exist a point (x, y, z) where all rays of the complex meet, this point will be determined by means of the following three equations, A— Fy— Es =0,j B + F^-D2=0,i (56) C+Eff+Dy=0.J These three equations can subsist simultaneously only in the case where (55) is satisfied. If this condition be satisfied, the locus of points, where all rays of the complex meet, is a right line, the projections of which are represented by the last equations (56). 46. Such rays as belong to both linear complexes, Q,z=zAr + Bs + C 4-D +F(s§ — 0'=A !r + B's + C' + DV + E 'g -f F'(s? -r =0,1 Q'=AV H-B's-f O' +D'r+(B —~Dz' )y+(EF -{-By' )z=Ax' +B y', | (A'-EV>+(B'-DV)y+(EV+Dy>=AV+B^'./ ‘ In order to express that both corresponding planes are the same, we obtain the fol- lowing relations, (A — Es') : (B —Hz') : (Ex' +Ey') : {Ax' +By')=l Q (A'-EV) : (B'-DV) : (EIx'+E'y1) : (AV+B'y). J } Since both planes pass through the given point, any two equations, hence derived, are sufficient in order to determine the locus of points having, in both complexes, the same corresponding plane. From any two of the following six equations where the accents are omitted, the remaining four may be derived ; DR. PLUCKER ON A NEW GEOMETRY OE SPACE. 751 (D'E-E'D>2-[(B'E-E'B)— (A'D-D'A)>- (A'B-B'A)=0, . (B'D - D'I%2 + [(B'E - E'B) + (AD - D'A )~\ccy + ( A'E - E'A)^= 0, (AD — D' A)y + (A'E — E' A)ar + (D'E — ED )yz =0, (BD-D'B)y-(B'E-E'B)#-(D'E-ED).r2=0, (A'B — B'A)y + (A'E — E'A)#2 — (B'E — E'B)y2= 0, (A'B - B'A> - (AD - D'A)xz + (BD - DB>2= 0 * (65) (66) (67) (68) (69) (70) 53. According to the first two equations (65), (66), the locus in question is a system of two right lines both intersecting OZ. These lines are confined within two planes parallel to XY and determined by (65) ; their direction within these planes is given by (66). We shall call them the “ directrices” and the characteristic section parallel to both and equidistant from them, the central plane of the linear congruency. Both “directrices” intersect at right angles the axis of the congruency, as the axes of all complexes do. 54. We may distinguish two general classes of linear congruencies ; either both direc- trices are real or both imaginary. In a particular case the two directrices are con- gruent. Finally, one of the two directrices may pass at an infinite distance. 55. If the directrices are real, and the plane XY be conducted through one of them, the following condition, A'B— B'A— 0 (71) is derived from (65). In order to determine within XY the direction of that directrix, we get from (67), by putting 2=0, (A'D-D'A)y+(A'E-E'A>=0 (72^ There is among the infinite number of complexes containing the congruency, which are represented by 12-f-jO«Q'=0, one of a particular description. It is obtained if, starting from (62), we put whence A B . (AD - D'A)* + (A'E - E'A)g = 0. (73) All rays of that complex, and therefore all rays of the congruency, meet within XY a fixed right line, represented by (72), on replacing g and a by x and y. This line there- fore is the axis of that complex, and one of the two directrices of the congruency. In the same way it may be proved that likewise all rays of the congruency meet the other directrix. Hence All rays of a congruency meet its two directrices. * We may observe that any equation which, like those above, is homogeneous with regard to (A'B— BA), A'C — C'A) . . . will not be altered if the complexes 12 and 12' are replaced by any of the complexes (12+jul2'). 752 DE. PLUCKEE ON A NEW GEOMETEY OF SPACE. Accordingly, both directrices being real and known, we may immediately draw through any given point the only corresponding ray of the congruency. 56. In that peculiar class of congruencies indicated by the condition D'E— E'D = 0, (74) one of the two directrices passes at an infinite distance. By putting simultaneously A'B-B'A=0, we get, in order to represent the only remaining directrix, now confined within XY, the same equation as before (72). But among the complexes, 0+^=0, there is, besides the complex (73), the axis of which is the directrix, another complex, represented by DOf-D'Q=(AT)-DA)r+(BT>-DE>=0, the rays of which are parallel to a given plane. Its equation may be transformed into Ar+Bs=0; (75) accordingly the equation of the plane becomes Aa’+B^=0. Hence in this peculiar case All rays of the linear congruency meet the only directrix , and are parallel to a given plane. 57. From the last considerations we conclude that among the complexes intersecting each other along a linear congruency, and represented by O+^O'=0, (76) there are in the general case two, of a peculiar description, all the rays of which meet their axes. These axes, the directrices of the congruency, are two conjugate right lines with regard to each of the complexes (76). Generally there is only one ray of the congruency passing through a given point, as there is only one ray confined within a given plane. But each of the two directrices may be considered as the locus of points, from which start an infinite number of rays, constituting a plane which passes through the other directrix. It may be likewise regarded as enveloped by planes, confining each an infinite number of rays, which con- verge towards a point of the other directrix. 58. We may represent any two complexes O, O' in any position whatever by equa- tions depending only upon the position of their axes and their constants. Let A be the shortest distance of the two axes from each other, and S- the angle between their directions. Suppose that OZ intersects at right angles the axes of both complexes. Let OX be the axis of the first complex O, k its constant, OX perpendicular to XZ. The equa- tion of the complex will be 7 1 <7= AT. DR. PLUCKER ON A NEW GEOMETRY OE SPACE. 753 If the axis OY be turned round O till, in its new position OY', the angle Y'OX becoming 9, the plane ZOY' passes through the axis of the second complex, the last equation, by putting . <7= sin 9+(Mf sin29-A£ sin 9- cos 9), . (78) A fy\ 2 (k'—k) cos — A sin y k 754 DR. PLtjCKER ON A. NEW GEOMETRY OE SPACE. On denoting the roots of these equations by z' sinS, z" sin $•, and (^j , (^j , we obtain (k—k1) cos $ + A sin 3- sin S' 4 M'+ [(A: — k1) cosS — A sin S]? sin2 S {z'-z'J (y\ ( y\" (A‘ + #)cos5 — AsinS ay\' fy\"\2 4^'+ [(A — A') e°s ^ — A sin •&] *) " w ) ~ The roots of both equations are simultaneously either real, or imaginary, or congruent. In the last case we have (k—k') cosS — A sin$-=2v^ — kk/, whence (f)'-(5W4- The central plane of the congruency is represented by ( k — k') cos S — A sin S 2 sin S (SO) In two peculiar cases this equation becomes z—\ A, either if &=**■, or, whatever may be if k=U. Hence the axes of any two complexes selected among those intersecting each other along a given congruency are at equal distances from its central plane if their directions are perpendicular to each other, or if the constants of both complexes are the same. 60. Without entering into a more detailed discussion of the last results we may finally treat the inverse problem : a congruency being given by means of its two direc- trices, to determine the complexes passing through it. On the supposition of rectangular coordinates, the two directrices may be represented by the following systems of equations, y—ax— 0, z=d,. y-\-a%=0, z=—0. These directrices are the axes of two complexes of a peculiar description, ranging among the infinite number of complexes which intersect each other along the congruency. The two complexes, if moved parallel to themselves till their axes fall within XY, are represented by the equations <7 — ag= 0, 0 1 + tan2 « tan co tan « 1 + tan2 co „ sin co cos co = 0- sin « cos sc . sin 2co = 4 • 0 , sin ‘Jet ’ Jc—6 tan2 a — tan2 co tan «(1 + tan2 co) ] sirr a cos^ co — sin‘ co cos^a sin a cos a ^sin (a + co) sin (a — co) sin a cos a (86) (87) The expression of z° shows that the axis within the central plane is directed along one of the two right lines bisecting, within this plane, the angle between the directions of the two directrices. These two right lines, having a peculiar relation to the congru- ency, may be called its second and third axis. The three axes, perpendicular to each other, meet in the centre of the congruency. In order to express the angle a by means of 2°, we get the following equation, 2° sin 2cy= - sin 2a, 0 indicating two directions perpendicular to each other, and corresponding to any value of 2°. 61. By replacing in the expression 0 tanw sin « cos a 1 + tan2 w tan a by v- , we obtain on omitting the accent of 2°, z(f+x*)= sin « cos cl xy. (88) The axes of all complexes constituting the congruency are confined within the surface represented by that equation. But this equation remaining unaltered if the axes OX and OY are replaced by one another, it is evident that the same surface contained the axes of two different series of complexes ; one of the two series constituting the given congruency, while the other constitutes a strange one, obtained by turning the given congruency round its axis through a right angle. DR. PLUCKER ON A NEW GEOMETRY OE SPACE. 757 62. In representing any three linear complexes by O =A r +Bs +C 4-Do- +E§ +E (sg— rc)=0,j a,EEAV+B's+C,+D4+E'g+F(sg-rff)=0,i (89) 0"=A"r+Bs" + C"+ D"Q"=0, but the three congruencies vary, and their directrices and the three diameters of the hyperboloid. The directrices may be either real or imaginary ; accordingly the three mdccclxv. 5 M 758 DE. PLUCKEE ON A NEW GEOMETEY OF SPACE. diameters either intersect the hyperboloid or do not meet it. In the intermediate case, where both congruencies are congruent, the corresponding diameter falls within the asymptotic cone of the surface. 65. Conversely, starting from the hyperboloid and any three of its diameters, we may revert to the three corresponding congruencies and the series of complexes by means of which these congruencies are determined. If especially the three diameters are the axes of the hyperboloid, the axes of the three congruencies meet in the same point, the centre of the surface, and are directed along its axes. There is a double way of reverting from a given hyperboloid to the congruencies, and further on to the complexes. The right lines constituting each of its two generations may be considered as its rays, while the right lines of its other generation will be found to be the directrices of the congruencies passing through the surface. 66. It might be desirable to support in the analytical way the geometrical results explained in the last numbers. For that purpose we may select in order to determine the configuration, three complexes of that peculiar description where all rays meet the axis. Accordingly the axes of the three complexes O, O', Q" are three of the six direc- trices, P, Q, E for instance, confined within the planes j?, q, r. In assuming these planes as planes of coordinates XY, XZ, YZ, the three complexes, constituting the con- figuration, are represented by equations of the following form, O =C +Do- -f-Eg>=0, j Q'<;=B's +DV +F (sq — r/ + E#) =0, which, by the disappearance of terms of the third order, becomes A"B'C+A,,(B'E+CF)^+B,(A"D-CF")3/-C(A"D'+E"B'>' + A'T'Etf2— B'F"D^2+ CE'TO + (A"FD-B,F,E)^-(A"D'E+CE"F)^ I - * (91) +(CF"D'-B'E"D)y2=0. j After dividing by A"B'C and replacing E 3) IP _F E" F C’ C5 B'’ B'’ A"’ A" by I, ?i, £', l', 71", the last equation assumes the following symmetrical form, +1 fit'+wy+w** | (92) +(^+iv')^+(r?"+r)«+w+>/'?v=o.| In order to represent the configuration this equation replaces the three equations (90), which may be written thus, vr+!g — 1 = 0, £'/ty+£"2=l,j the directrices within them by 2=0, g'jF+V'y =1,1 y= 0, gar +$"*=1,1 : (95) *=0, ny+?z= 1.1 The points of contact, being within each plane the intersection of the ray and the directrix, are easily obtained. The rays within the three planes of coordinates which form one edge of a circum- scribed parallelopiped meet the directrices within the planes forming the opposite edge. 5 m 2 760 DE. PLUCKEE ON A NEW GrEOMETEY OF SPACE. II. — On Complexes of Luminous Rays within Biaxal Crystals. 1. A single ray of light when meeting the surface of a doubly refracting crystal is divided into two rays determined by means of their four coordinates, r, s, g, a. All inci- dent rays constituting a configuration, especially all rays starting from a luminous point and forming a conical surface, constitute within the crystal a new configuration, repre- sented by the system of three equations between ray-coordinates. All incident rays constituting a congruency, emanating, for instance, in all directions from a luminous point, constitute within the crystal, after refraction, another congruency. Finally, a complex of incident rays, all rays, for instance, emanating in all directions from every point of a luminous curve, constitute within the crystal another complex of refracted rays. The congruency of refracted rays is represented by two, the complex by a single equation between ray-coordinates. 2. But before entering into the discussions indicated by the foregoing remarks, a short digression on double refraction might be desirable. A biaxal crystal being cut along any plane whatever, we may suppose that this plane is congruent with xy , and that the point where an incident ray meets it is the origin of coordinates O. Let /n x x=pz, y=qz (1) be the equations of the incident ray, whence (2) P 9 the equation of the plane of incidence. In the moment of Incidence the front of the corresponding elementary wave, perpendicular to the ray, will be represented by z+qy+px = 0 (3) After the front of the wave has moved in air through the unit of distance, its equation becomes , ... z+qy+px=w (4) on putting At this moment the front of the wave intersects xy along a right line, which we may denote by HR, the equation of which is qy+px=w (5) If the optical density of the surrounding medium increases, the value of w decreases in the same ratio. 3. Around the point O, where the incident ray meets the section of the crystal, let the wave-surface be described as it is at that moment when the front of the elementary wave intersects xy along RR. The position of the axes of elasticity of the crystallized medium being known with regard to the axes of coordinates, the equation of the wave- surface only depends upon three constants a, #, c, which are to be referred to the same DE. PLUCKEE ON A NEW GEOMETEY OF SPACE. 761 unit as w. If both systems of axes are congruent, the wave-surface is represented by the well-kndwn equation («V+%2+cVX^+^+^)-[«2(^+c>2+^«2+c2)/+^K+J2K]+aW=0’ • (6) which, for simplicity, may be written thus, 0=0. 4. The wave-surface is intimately connected with three ellipsoids, the equations of which are 2 2 2 ^2 +£2 =1j (?) «V+5y+cV= 1, (8) 2^ h +£ +r* =1 (9) By means of the first and the second ellipsoid the wave-surface may be obtained most easily. The third ellipsoid has been introduced by myself on account of the following remarkable property. With regard to this ellipsoid the wave-surface is its own polar surface, i. e. the polar plane of any point of the surface touches it in another point, and vice versd, the pole of any plane tangent to the surface is one of its points. The wave-surface and the three ellipsoids depend upon the same constants. When the crystal turns around the point of incidence O, both the surface and the three ellip- soids simultaneously turn with it. In the new position their equations involve three new constants, indicating the position of the axes of elasticity with regard to the axes of coordinates. Now the wave-surface may be represented by O'=0, and the third ellipsoid in the corresponding position by A#2+B#;y+Oy2d-2D#z+2%;s+F;s2---l=E=0 (10) From the six constants of this equation, which may be regarded as known, you may derive the six constants of the wave-surface by determining both the direction and the length of the axes of the third ellipsoid. Within the plane xy , supposed to be any section whatever of the crystal, OX and OY may be directed along the axes of the ellipse along which this plane is intersected by the third ellipsoid. Accordingly the constant B disappears from the last equation. Besides, if OZ be directed along that diameter of the ellipsoid which is conjugate to the plane xy, and cease therefore, in the general case, to be perpendicular to it, both constants D and E likewise disappear. 5. According to Huyghens’s principle, we obtain both rays into which an incident ray is divided, when entering the crystal, by the following general construction. Con- struct the two planes passing through the trace RR and tangent to the wave-surface described within the crystal around the point of incidence O. Let H and H' be the 762 DR. PLUCKER ON A NEW GEOMETRY OE SPACE. points of contact within these planes. The two right lines OH, OH' drawn through the point of incidence O and the two points of contact H, H' will be the refracted rays. By means of the theorem referred to in the last number I have replaced this con- struction by the following one, much easier to manage. Construct with regard to the third auxiliary ellipsoid E the polar line of the trace HR. This polar line, which may be denoted by SS, meets the wave-surface within the crystal in the two points H and H', OH and OH' being, as before, the two refracted rays. The plane HOH', containing both refracted rays OH, OH', may be called the plane of refraction. There are, generally speaking, four tangent planes passing through RR, as there are four points where the wave-surface is intersected by SS. We get therefore four rays, all confined within the plane of refraction, but two of them, not entering the crystal, are foreign to the question. 6. The plane of refraction may be constructed solely by means of the third ellipsoid E. The details of this construction depend upon the well-known different modes of determining the polar line SS. On proceeding in this way we meet some remarkable corollaries concerning double refraction *. 7. The poles of all planes passing through the trace RR, represented by qy-fpx=w . . (5), are points of SS. All right lines passing through the point of incidence O and these poles fall within the plane of refraction confining SS. These right lines may likewise be regarded as diameters of the ellipsoid E conjugate to diametral planes passing through the trace along which the surface of the crystal, i. e. the plane xy, is inter- sected by the wave-front in its primitive position, the trace being parallel to RR and represented by Hence qy+px= 0 (11) The plane of refraction is that diametral plane of the ellipsoid E, the conjugate dia- meter of which is perpendicular to the plane of incidence in O. * In concluding a former paper, “Discussion de la forme generale des ondes lumineuses” (Crelle’s Journal, No. xix. pp. 1 & 91, Mai 1838), I gave the following construction: — “ Construisez, par rapport a l’ellipsoide directeur, la ligne droite polaire (SS) de celle qui est perpendiculaire au plan d’incidence en O'. Elle coupera la surface de l’onde, decrite autour du point 0, en deux points. Les deux lignes droites qui vont du point 0 aboutir a ces points seront les deux rayons refractes ; tandis que les deux plans, qui, contenant la perpendiculaire en 0' (RR), passent par ces deux m ernes points seront les fronts des deux ondes planes correspondantes. Enfin il a ete demontre, dans ce qui precede, que les deux plans de vibration sont ceux qu’on obtient en conduisant par les rayons lumineux (refractes) des plans perpendiculaires aux fronts des ondes correspondantes.” At the present occasion I resume the discussion, announced by myself twenty-six years ago, of a part of this construction. More recently, in the eighteenth Legon of his valuable work, ‘ Theorie mathematique de l’Elasti- cite’ (1852), M. Lam£ reproduces the curious relation between the wave-surface and the third ellipsoid. He presents in the following Legon a remarkable theorem, “ which is one of those immediately derived from this relation.” [8] DE. PLTJCKEE ON A NEW GEOMETEY OF SPACE. 763 Accordingly the plane of refraction, conjugate to (6), is represented by the equation dE dE dxQ- dy$>’> (12) which may be expanded into the following one, (Ax+By+T>z)q=(Bx+Cy+'Ez)p, (13) or {Aq— Bp)x-\-(¥>q— Cp)y+(Dq— Ej?)z=0* (14) 8. These equations remain unaltered if p and q vary in such a way that the ratio ^ remains the same, i. e. if the angle of incidence vary while the plane , of incidence remains the same. The same equations do not contain w, the value of which depends upon the density of the surrounding medium. Hence All rays of light confined within the same plane of incidence, after being divided into two by double refraction , are confined again within the same plane — the plane of refrac- tion. This plane remains the same if the surrounding medium be changed. 9. The plane xy, i. e. the surface of the crystal, containing the trace (11), its conju- gate diameter, the equations of which are or «-0 (15) Atf+B.y+D^O, | B#+Qy+E;z =0, j (16) is confined within the plane of refraction, whatever may be the incident ray. The same may be proved analytically by observing that (12) is satisfied by means of the two equa- tions (15). Hence A ray of light of any direction whatever meeting the surface of a biaxal crystal in a fixed point is so refracted that the plane containing both refracted rays passes through a fixed right line (15). * On representing any one of both refracted rays by the equations x=rz, y=sz, the last equation, written thus, (A2-Bi>>+(B2-Cp)S.+(D?-Ep)=0, (1) indicates a relation between the direction of the incident ray, determined by the constants p and q, and the direction of the refracted one, determined by r and s. This equation will not be altered if the incident ray, moved parallel to itself, meet the section of the crystal in any point x=?> y=r. If r and s be regarded as variable, and = 0, which, after eliminating p and q, may be written thus, (AE-DB>+(BE-DC)y=0 (19) In this case the plane of refraction is perpendicular to xy and passes through OZ. The plane of incidence perpendicular to xy, or its trace within this plane, is represented by I (20) It is easily seen that this trace is perpendicular to the trace of that diametral plane which, with regard to the ellipsoid E, is conjugate to OZ. Indeed this plane is repre- sented by “=»H-%+F*=0, and its trace within xy by Rr-f Ey=0. Each ray within the plane of incidence (20) is divided by double refraction into two, both confined within the same vertical plane of refraction. That is especially the case with regard to the ray incident at right angles ; the corresponding plane of refraction, represented by (19), contains the incident ray and both the refracted rays. 13. Besides the vertical ray, there is in each plane of incidence one ray confined with both refracted rays within the same plane. After eliminating p and q between the general equations of the planes of incidence and of refraction, qx—py, (Ax + By + ~Dz)q=(Bx +Cy+ E z)p, the following equation is obtained, B(y—x*)+(A-C)xy + (-Dy-Ex)z=0, (21) representing a cone of the second degree, the locus of incident rays which are confined within their corresponding planes of refraction. This cone passes through the vertical OZ, and intersects xy within two right lines perpendicular to each other. These lines are congruent with the two axes of the ellipse Aa-2+2B^4-Oy2=l, (22) along which the plane xy is intersected by the ellipsoid E. (That is instantly seen by putting B=0 [4].) Hence both rays, grazing the surface of the crystal along the axes of the ellipse (22), are confined with both corresponding refracted rays within the same plane. MDCCCLXY. 5 N 766 DR. PLUCKER ON A NEW GEOMETRY OE SPACE. If especially the crystal be cut in such a way that xy become a circular section of the ellipsoid E, each ray grazing the surface of the crystal will be contained within the cor- responding plane of refraction. This plane therefore is easily obtained by means of the trace of the plane of incidence and the diameter OZ' of the ellipsoid E conjugate to its circular section xy. 14. In the preceding numbers the plane of refraction has been determined without determining SS confined within it. This right line, passing through the infinitely distant pole of xy, is parallel to the diameter OZ' conjugate to xy and represented by the equa- tions (16), which by eliminating successively y and x may be replaced by the following ones, (B2— AC> + (BE— CD>=0,1 • (B2-AC)y+(BD-AE>=0.j [ } The direction of SS being known, any one of its points, i. e. the pole of any plane passing through RR, will be sufficient to construct it. If the plane be parallel to the diameter just determined, its pole will fall within the plane xy, and may be also regarded as the pole of RR, with regard to the ellipse (22) along which this plane is intersected by E. The trace RR being represented by qy-\-jpx=w, where the two lines, the equations of which are (A^+By) ~ = 1, (Bx+Cy) ^=1, will meet in the pole mentioned. Hence, on denoting its coordinates by x° and y°, By-Cp 1 , X ~ B2-AC w PrAg.l. [ y B2— AC w J (24) Finally, the equations of SS thus obtained are x—x° y—y° z CD— BE=AE — BD B2— AC (25) In order to complete the construction of the two refracted rays, the points (M, M') in which SS meets the wave-surface O within the crystal are to be joined with O by means of two right lines OM and OM7. 15. If rays of every direction meet the crystal in O, the corresponding wave-fronts in that moment when, within the crystal, the wave-surface O is formed, will envelope a sphere, DE. PLtiCKEE ON A NEW GEOMETEY OF SPACE. 767 the radius of which is equal to unity. The locus of poles of the wave-fronts, if taken with regard to the ellipsoid E, is a new ellipsoid, which, referred to axes of coordinates directed along the axes of all auxiliary ellipsoids, is represented by the equation !2c2~^a262 = 1, aV+%2+cV=aW (26) Its axes are obtained by multiplying the axes of the second auxiliary ellipsoid (8), to which it is similar, by abc. 16. The new fourth auxiliary ellipsoid (26) is fitted to connect the constructions of the refracted rays if, the section of the crystal remaining the same, the direction of the incident rays vary. Indeed a right line (MM') drawn through any point Y of the fourth ellipsoid (26) parallel to OZ', i. e. to the diameter conjugate to xy with regard to the third ellipsoid E, meets the wave-surface O, within the crystal, in two points M and M'. OM and OM' will be the two refracted rays corresponding to that incident ray which is perpendicular to the plane conjugate to OY. 17. After this digression we resume our subject. Let xy be the section of a biaxal crystal and OZ perpendicular to it. Let a ray of any direction starting from any point of OZ meet the section of the crystal in a point the coordinates of which are Let x-%, y—a. x=pz+q, 1 y=qz-\-a J (27) be the equations of the incident ray. obtain the following relation, Let P—t q a- In order to express that this ray meets OZ we (28) (29) x=rz+g, 1 y=sz+)s + (D) = 0, (31) and then represents a complex of refracted rays. As no supposition is made regarding the position of the luminous point on OZ, the corresponding incident rays may start in every direction from all its points. They ’constitute therefore a complex of rays emanating from OZ, perpendicular to the section of the crystal, and considered as a luminous right line. This complex of incident rays, after entering the crystal, passes into the complex of double refracted rays represented by the last equation. 19. By admitting that OX and OY, within the section of the crystal, were directed along the axes of the ellipse, along which xy is intersected by the ellipsoid E, the constant B disappears from the equation of the complex, which then may be written thus, (Ar+D) (32) We have hitherto supposed OZ to be perpendicular to xy , and will continue to do so for incident rays without the crystal ; but for the refracted rays entering it (the axes OX, OY, perpendicular to each other, remaining the same) the direction of OZ may be changed by replacing it by the diameter OZ' of the ellipsoid E, conjugate to xy. Then the constants D and E likewise disappear, and the equation of the complex assumes the most simple form, Arc=Csg. 20. On denoting by a0 and b0 the two semiaxesof the ellipse along which xy is intersected by the ellipsoid E, we get A=-2> b=4- ao K We may suppose, too, that a0 falling within OX, is greater than bQ falling within OY, a?—b 2 whence the square of the excentricity of the ellipse e\ becomes 0 2 0 • ao After having introduced the new constants, the last equation may be written in the following ways, (34) sg — r and )s=0, indicating that the hyperbola of the general case degenerates into two points, falling within OY, one at an infinite distance, while the distance of the other (Q') from O is OQ'=,= -tz«- = i^OQ. (46) Accordingly the hyperbolic cylinder degenerates into two right lines, met by all refracted rays. One of the two lines within the plane xy along which the crystal is cut is parallel to OX, and intersects OY in Q ', the other is infinitely distant. Hence all rays within a plane intersecting xz' along a trace (QZ'0) parallel to OZ' are divided into two sets. The rays of one set being parallel to the plane xy may be here omitted. The rays of the other set meet in a fixed point of that same plane along which the crystal is cut. If the plane turns round its trace QZ„ the fixed point moves, within xy, parallel to OX, describing a right line Q'X0. Each ray meeting both right lines QZ'0 and Q'X0 is a ray of the complex. DE. PLUCKEE ON A NEW GEOMETEY OE SPACE. 27. If, in the second instance, the trace (45) is parallel to OY and intersects OZ' in E, OE being equal to the equation (44) becomes ws=j32w, representing a point of OZ', the distance of which from O is OE'=-j = -i2“ = pOE. (47) The hyperbolic cylinder therefore degenerates into a right line (EX0) within xz' parallel to OX and passing through E'. Hence All refracted rays of the complex confined within a plane intersecting yz' along a trace (EY0) parallel to OY converge into a fixed point of the plane xz'. If the plane turns round its trace, that point describes, within xz', a right line EX0 parallel to OX. Each ray meeting both lines EY0 and E'X0 is a ray of the complex. 28. The axes of coordinates OX and OY may be interchanged by writing a0 instead of b0, and reciprocally. Then we get analogous results if, instead of traces within YZ', we consider traces within XZ'. Especially we may immediately conclude from the last equation "written thus, ^.OE'=«;-.OE, (48) that the relation between the two right lines E'X0 and EY0 is a mutual one. 29. All rays intersecting two fixed right lines constitute a linear congruency , the fixed right lines being its directrices (Sect. I., 55). Consequently the complex of refracted rays may be generated in three different ways by a variable linear congruency. In each case the two directrices of the congruency move parallel to any two of the three axes of coordinates OX, OY, OZ', intersecting the third axis in two points, the distances of which from O are in a given ratio. 30. Hitherto we have supposed that the plane xy is any section whatever of the crystal. Let us now, in particularizing again, admit that the crystal is cut along one of the two circular sections of the third auxiliary ellipsoid E, then represented by A(x2+y2)+Fz2=l; /3 being equal to unity, the equation of the complex becomes ra—sg (49) In this peculiar case therefore all rays of the complex meet the diameter OZ', conju- gate with regard to E to its circular section xy. Hence all refracted rays of the com- plex intersect OZ' as all corresponding incident rays start from OZ. Both the diameter of the third auxiliary ellipsoid E perpendicular to its circular section xy, and its diameter conjugate to that section, fall within a principal section of the ellip- soid containing its greatest and least axis, and consequently also its two optic axes. The rectangular axes of coordinates OX and OY may, without changing the equation of the complex, turn round O within the section xy. If one of them, OX for instance, become DE. PLUCKEE ON A NEW GEOMETEY OF SPACE. 773 the vertical projection of OZ', the plane xz! is a principal plane of the ellipsoid E, con- taining the two optic axes, and OY the mean axis of the ellipsoid E. 31. If the plane xy is a principal section of the third auxiliary ellipsoid E (and there- fore of all auxiliary ellipsoids), the axis OZ', becoming perpendicular to xy, is congruent with OZ. Then the equation of the ellipsoid E, referred to rectangular coordinates, becomes ,;2 w2 ,2 i-jjL. i_— = 1 bc'ac'ab ’ and may be written thus, ax'2 -f- by 2 cz2 = abc. Hence the equation of the complex is arc=bsg (50) If the crystal be turned round OY through an angle %, we get, after replacing x and z by x cos a, — z sm a, x sin k-\-z cos a, the following equation of the ellipsoid E, (a cos2 a-\-c sin2 ot)x2-\-by1— 2(a— c) sin a cos a . xz-j-(a sin2 a + c cos2 u)z2=abc. . (51) The axes of the elliptic trace within xy being always directed along OY and OX, the equation of the complex assumes the form of the equation (32), which, after putting E=0 and A : C : D = (« cos2 a — c sin2 a) : b : — {ci— c) sin a cos a, passes into the following one, (a cos2 a — c sin2 u)rc—bsg—(a—c) sin a cos a . , v, the following relations are obtained : I. (uv1 —u'v ) : — (tv1 —t'v ) : (tv! —t'u) : ( tw' — Hw ) : (uw'—v!w) : (W— v'w) II. —(xtz'—x'ts) : (yJ—y'm) : (zn'—z'n) : (yz1 —y'z) : —(xz! —x’z) : (xy'—ody) III. = cos a : cos/3 : cosy : hcosX : ticosy, : Scosv. 5. Hence we conclude that cos (3, cos y, § cos x, 5 cos p, c> cos v cos a, DE. PLtJCKEE ON A NEW GEOMETEY OE SPACE. 777 may likewise be regarded as line-coordinates. Here the equation of condition between the six coordinates becomes cos a cos X -J- cos j3 cos cos y cos v=0, which, added to the two following ones, cos2a+ cos2]3-f- cos2 y=l, cos2 X cos2jU/+ cos2v = l, reduces to four the number of constants upon which the position of the line depends. 6. The two sets of ratios I. and II. retain the same generality after putting w—w' — + 1, ot = gt'= + 1. If we suppose, again, that both planes and both points, by which the line is determined, are coincident, we get, choosing the under signs, two new sets of equal ratios, IV. —{udv—vdu) : —(tdv—vdt) : ( tdu—udt ) : dt : du : dv V. = dx : dy . dz : (ydz— zdy) : — {xdz— zdx) : {xdy— ydx). Thus we obtain two systems of differential coordinates, dx , dy , dz indicating the direction of the line, dt , du , dv the direction of the normal to the plane passing through it and the origin of coordinates. We may regard x, y, z, t, u, v as functions of time. 7. We can represent the direction of a force by the right line, and its intensity by the distance of the two points by which the position of the line is fixed. In denominating the projections of the force on OX, OY, OZ by X, Y, Z, and the projections of its moment with regard to the origin on YZ, XZ, XY by L, M, N, we obtain the following new set of equal ratios : VI. =X : Y : Z : L : M : N. Therefore X, Y, Z, L, M, N may also be considered as six line-coordinates. The equa- tion of condition between them becomes XL+YM+ZN=0 (6) 8. The six coordinates of each system range into two groups of three, to each coordinate of one group corresponds one of the other. By exchanging the three axes of coordinates, the three couples of corresponding coordinates are exchanged, both groups remaining the same. We may, in order to pass from the six coordinates of a right line to its five absolute coordinates, divide any five of them by the sixth. Here we meet two cases, in dividing either by a coordinate of the first or the second group. 9. Let us divide the first two and the three last terms of the ratios I. by the third (tu1 — t'u). In putting uv' — v!v tv 1 — t'v tu! — t'w uw' — u'w vw' — v'w tv!— t'u tu' — t'u tu' — t'u <7’ tu! —t'u tu! — t'u Yh where, according to the equation of condition (3), n=ra—sg, 778 DE. PLUCKER ON A NEW GEOMETRY OE SPACE. p, s, ( — , q, ( — «), 7r, and ^ will be the Jive new coordinates. We meet four of them in the last two of the four equations (4), representing the two points where the planes XZ and YZ are intersected by the right line. These equations assume the following form, t =pv-\-7 rw, u=qv-\-xw , and may, in denoting the coordinates of the points within their planes by xy, zy, and yx, zx, be written thus, (vyt+z9v+w= 0, yxu+%jv ’±w= 0 ; whence We may add to the former six sets of equal ratios the two following: VII. = r : 8 : 1 (—a) : q(==,r?]= 0, F[(— *)» ^p, q , 1]=0, represent the same complex ; F being supposed to indicate always the same homogeneous function of the different groups of line-coordinates. The complex is said to be of the nth. degree , and represented by if its equations are of that degree. 12. Starting from the first equation, Qre=F[(W— u'v), —{tv'—t'v), {tu'—t'u), {tw'—t'w), {uw'—u'w), {vvJ —v'w)~\= 0, . (1) t, u, v, w and t', u', v', w' are to be referred to any two planes passing through any line of the complex. Let one of the two planes {t1, u', v', w') be any given one. Then the last equation, in regarding t', u', v', w' as constant and t, u, v, w as variable, represents within the given plane a curve enveloped by tangent-planes {t, u, v, w). The lines of the complex, confined within the plane, also envelope the same curve, the class of which is the same as the degree of the complex. Hence A complex of the nth degree being given, in each plane traversing space there is a curve of the nth class enveloped by lines of the complex. The equations of such curves fully agree with the general equation of the complex itself. We have only to consider in this equation t' , u', v' , w' as constant in referring them to the given plane, while t, u, v, w are regarded as variable plane-coordinates. If %=1, the curve in each plane is replaced by a point; each line within the plane passing through that point belongs to the linear complex. If n= 2, the curves enveloped are conics, which may degenerate into systems of two real or imaginary points. 13. If, in the second equation of the same complex, xnn=F[{x-x'), {y-y'), (: z-z '), {yz'-y'z), -{xz'-x'z), {xy'-Ay)~\— 0, . (2) where we put &'=■&=. 1, and X denotes a constant, x', y' , z' are referred to any given 780 DE. PLUCKEE ON A NEW OEOMETEY OE SPACE. point in space and therefore regarded as constant, while x, y , z are the variable coordi- nates of the points of any line of the complex, that equation represents a cone of the nth. order, the geometrical locus of lines of the complex passing through the given point. Hence A complex of the nth degree being given , each point of space is the centre of a cone of the nth order into which lines of the complex converge. In linear complexes the lines meeting in a given point constitute a plane. If n— 2, the cones are of the second order, and may degenerate into two real or imaginary planes. 14. The right lines constituting a complex may be distributed either within planes traversing space, or according to points into which they converge. We hitherto con- sidered as a complex of right lines, the number of which is oo3. We may as well regard it either as a complex of curves, or as a complex of cones, the number both of curves and cones being oo2. Therefore we may say that O„=0 represents at the same time as well in each plane a curve of the nth class as cones of the nth order having each point of space as centre. The curve in a plane revolving round a given line, or moving parallel to itself, gene- rates a surface. The cone the centre of which describes a given right line envelopes a surface. The number of surfaces both generated by the curve and enveloped by cones is co. There is one of each kind of surfaces corresponding to any given line, all sur- faces will be exhausted if that line turns in all directions round any of its points. Accordingly we may likewise consider as a complex of surfaces, either described by curves or enveloped by cones. 15. In denoting by g> any constant coefficient, O„+^Om=0 (3) represents an infinite number of complexes. The lines congruent in any two of them belong simultaneously to all. All these congruent lines constitute a congruency (Q„, Qm), which we say is represented by the equations of the two complexes. • Each plane traversing space confines a curve of each of the two complexes, the mn tangents common to both curves belong to the congruency. All curves within the same plane belonging to the different complexes (3) which pass through the congruency, touch the same mn of its lines. Again, each point is the centre of a cone belonging to the different complexes (3). All such cones meet along the same mn[ lines, likewise belonging to the congruency. Therefore in a congruency (Q„, Qm) there are mn lines confined within each plane as there are mn lines passing through each point. The num- ber of lines constituting a congruency is oo2. If m— 1, there are in each plane n lines of the congruency (£2„, OJ passing through the same point, as n of its lines converging into each point fall within the same plane ; plane and point corresponding to each other. DE. PLUCKEE ON A NEW GEOMETET OF SPACE. 781 1 6. In denoting by y and v any two constant coefficients, Q=Q'+pQ''+»Q'w=0 (4) represents an infinite number ( oo2 ) of complexes. All these complexes meet along the lines which simultaneously belong to any three of them, especially to O'=0, O"=0, O'"=0 (5) By means of these equations the position of such a line is determined, after having arbi- trarily assumed the value of one of the four constants upon which the line depends ; in other terms, three of these four constants are functions of the fourth, varying each by an infinitely small quantity if this one does. Hence we conclude that a line the coordi- nates of which verify the three equations (5), generates a surface in passing successively into all its positions. This surface (O', O", O'") is said to he represented hy the system of the three equations (5). 17. Any point of space being given, there are three cones described by lines which belong to the three complexes (5) and pass through the given point. Generally the three cones (11) do not intersect along the same line. In certain positions only of the point they do. In this case their common intersection belongs to the surface (O', O", O'"), and therefore the point itself also. Put X' O' =F \_(x-x'\ (y—f), (z-z'), (yz'-y'z), -(xz'-x'z), (xy'-x'y)~\= 0, X"0" =F" [(x—x’), (y-y'), (z-z'), (, yz'-y'z ), -(xz'-x'z), (xy'-x'y)]=0, • X'"0" ' = F"' \_(x—x'), (y-y'), (z-z'), (yz'-y'z), -(xz'-x'z), (xy'-x'y)]=0. (6) If x', y' , z' are referred to any arbitrary point, and x, y, z regarded as variable, these equations represent the three cones, (x’y'z') being their common centre, and their gene- rating lines belonging to the three complexes (5). Without changing the conditions of mutual intersection, the three cones may be moved parallel to themselves till the origin of coordinates becomes their common centre. After that displacement their equations are transformed into the following ones : F' \x, y, z, (yz'-y'z), -(xz'-x’z), (xy’-x'y)'] = 0, F" [x, y, z , (yz'-y'z), -(xz'-x’z), (xy’-x’y)]=0, (7) ¥"[x, y, z, (yz'-y'z), -(xz’-x’z), (xy’-x’y)] = 0. j These equations being homogeneous with regard to (x, y, z), will, in the general case, not be simultaneously verified by the three variables. In order to express that they subsist simultaneously, we obtain, after having eliminated x, y, z, =0, (12) fn indicating a new function. By eliminating p and q between the three equations (11) and (12), we get an equation of the form W,y',z')= 0, (13) representing, if at, y\ z' be regarded as variable, a developable surface , the locus of those points through which double lines of the congruency pass, or, in other terms, the locus of the double lines themselves. In supposing that three intersecting lines of the two cones (11) fall within the same line (p, q), the following new equation of condition is obtained dj_ df dp* \dq) dpdq dq dp dq9- \dp) dp dq dtf(dfY_ o d?f df df dj1 / df'\ > = df-7f dp* \dq) dpdq dq' dp ' dq 2 \dp) dp dq which again may be expanded into an equation of the form f"(p, q,x',y', z')= 0 (14) This equation, combined with the three former equations (11) and (12), furnishes a new equation of condition, t(x',y',z')= 0 (15) The system of the two equations (13) and (15) gives, as locus of points through which triple lines of the congruency pass, a curve of double curvature. In pursuing the same course a new equation of the same form as (13) and (15) is 5 p 2 784 DE. PLUCKER ON A NEW GEOMETRY OE SPACE. obtained, which, combined with these, indicates that there is a certain number of points into which quadruple lines of the congruency converge. In congruencies of a peculiar description only we meet quintuple lines. 21. In quite the same manner we may determine the position of planes within which two, three, four of the mn lines of the congruency (Q„, Om) coincide. In that case both curves within the plane, enveloped by lines of the complexes Q,n and Qm, touch or osculate one another on a common tangent. In operating on the first two equations (9) as we did on the first two equations (6), we get, in order to represent in plane-coordinates the locus enveloped by planes con- fining a double line of the congruency, the following equation, \p(t, u, v)= 0, (16) which, as the remarks of No. 19 here likewise hold, is derived by a mere exchange of constants from (10). Each plane passing through a double line being an enveloping tangent plane of the represented surface, this surface degenerates into a curve of double curvature. Another equation may be derived from (15) in the same way. Let it be vj /(#, u, v)=0, (17) the system of the two equations (16) and (17) representing a developable surface , the tangent planes of which confine the triple lines of the congruency. Finally, there are certain tangent planes of the developable surface which confine the quadruple lines of the congruency. These planes, as well as the points of the curve of double curvature through which the quadruple lines pass, are determined by associated plane- and point- coordinates, both being functions of the constants of the congruency, and are obtained one from another by the above-mentioned exchange of these constants. 22. The double lines of a congruency constitute a surface , degenerated into a deve- lopable one, as they envelope a surface, degenerated into a curve of double curvature. The developable surface is represented in point-coordinates by a single equation (13), in plane-coordinates by the system of two equations (16) and (17). The curve of double curvature is represented in plane-coordinates by a single equation (16), in point-coordi- nates by the system of two equations (13) and (15). The tangent-planes of the surface , confining triple lines of the congruency, osculate the curve ; the points of the curve , through which these triple lines pass, are osculating points of the surface , in which three consecutive tangent planes meet. The curve , in certain points where the tangent is an osculating one, is osculated by a plane in four points. Through such a point pass four consecutive tangent planes of the surface , the common intersection of which is a line of inflexion of the developable surface . The quadruple lines of the congruency pass through such points, and are confined within such planes*. * In two remarkable papers “ On a New Analytical Representation of Curves in Space,” published in the third and fifth volume of the Quarterly Journal of Mathematics, Professor Cayley employed before me, in order to represent cones, the six coordinates of a right line, depending upon any two of its points. Having lately DR. PLtJCKER ON A NEW GEOMETRY OE SPACE. 785 III. On a new System of Coordinates. 23. We have hitherto determined the position of a right line in space in making use of the ordinary system of three axes OX, OY, OZ intersecting each other. The new question is whether we may substitute for this system another, by means of which we are enabled to fix immediately the position of a right line without recurring to points and planes. In the ordinary system of coordinates, (1) the position of a point is determined by means of three planes parallel to the planes of coordinates and meeting in that point, (2) the position of a plane by a linear equation between the three coordinates of a point, regarded as variable ; both point and plane depending upon three constants. In an analogous way a right line is determined by the intersection of four linear complexes. Such a linear complex depends upon the position of its axis and a con- stant (paper presented, No. 29). A right line, regarded as the direction of a force , belongs to the complex, if the moment of rotation of the force with regard to the axis, divided by its projection on the axis, be equal to the constant. Accordingly any four axes in space being given, the position of a right line is fixed by means of four constants, obtained by dividing the four moments of rotation with regard to the four axes by the four corresponding projections on the same axes. The four axes of the complexes constitute the new system of coordinates ; the four constants are the four coordinates of the given right line. The right line intersecting the four axes is the origin of coordinates, its four coordinates being equal to zero. In the new system of coordinates a right line is determined in the most general way by its four coordinates ; but an equation between the four coordinates is not in a general way sufficient to represent a linear complex, depending as it does on five constants. We may ad libitum increase the number of coordinates of a right line. 24. Let P, Q, R, S, T, U . . be the axes of any number of complexes, and p, q, r,s,t,u.. the corresponding coordinates of a given right line (according to the last number). Let QP = Up—p=0, = q=0, £l=*r-r=0, £ls = as— s=0, £=0, QM=E„ — u—0... be the equations of the complexes. In order to express that the complexes meet along the same line, the following equations of condition are obtained, only seen the papers, I hasten to mention it now. But, besides the coincidence referred to, the leading views of Professor Cayley’s paper and mine have nothing in common. On this occasion I may state that the prin- ciples upon which my paper is based were advanced by me, nearly twenty years ago (Geometry of Space, No. 258), but this had entirely escaped from my memory when I recurred to Geometry some time since. 786 DE. PLUCKER ON A NEW GEOMETRY OE SPACE. where we may suppose that P, Q, E, S are the former four axes of coordinates ; x, x!, x, X', I&&, v , v' indicate any constant coefficients. In putting the coordinates q, r, s, t, u. . equal to zero, the general equations of the complexes become These new equations represent complexes of a peculiar kind, the lines of which inter- sect their axes ; they may be said to represent the axes themselves. In order to satisfy the equation (18), we put whence H p 4- X'H? + gJ ar + v' as, J (19) t —xj) -f-X^ -f -[hr +w, 1 u=xp+'k'q+[A'r-\-v's. j (20) The equations (19) require that the origin met by the axes P, Q, E, S be likewise met by the new axes T, U . . . Therefore q, r, s, t, u. . may be regarded as coordinates of the right line along which all complexes meet ; the axes of the complexes intersecting the same right line being the axes of coordinates. A right line being completely determined by the first four coordinates, those remaining depend upon them by linear equations (20). The system of four axes of coordinates depends upon 16, of five axes upon 19, of six upon 22 constants. Having thus established a system of coordinates which, independently of points and planes, fixes the position of a right line in space, we are enabled, by regarding right lines as elements of space, to reconstruct the whole geometry without recurring to the ordi- nary system. Here we are guided by analogy. As far as I may judge, the task is a most grateful but at the same time a long and laborious one. IV. Geometry of Forces. 25. In recapitulating the contents of the first three paragraphs of this note, new con- siderations have been suggested to me, which seem calculated, while greatly increasing again this kind of inquiry, to put the key-stone to it. Hitherto, when I borrowed technical terms from mechanical science, the only intention was to simplify the expression. But force may be regarded as a merely geometrical notion, and there is only one step more to be taken in order to arrive at a “ Geometry of Forces ,” as there is a geometry based on the notion of right lines. Forces depend upon five independent constants, four of which indicate their position, while the fifth indicates their intensity. We may call these constants the five coordi- nates of the forces. DR. PLIJCKER ON A NEW GEOMETRY OF SPACE. 787 In order to fix the direction of a force, we may employ line-coordinates and choose the following, X, Y, Z, L, M, N, indicating the projections of the force on the three axes of coordinates OX, OY, OZ, and its three moments of rotation with regard to these axes. Between them the following equation of condition holds good, XL+YM+ZN=0 (see No. 7). The quotients obtained by dividing any five of them by the sixth are the absolute values of coordinates. From these quotients the intensity of the force has dis- appeared. The same six constants , reduced by the last equation to five independent ones, may he regarded as the absolute values of the coordinates of the force. Instead of homoge- neous equations between them, if regarded as variable, representing complexes of lines (of directions of the forces), we now get ordinary equations between the same variables representing complexes of forces. The extension of all former developments thus indicated immediately occurs to us. A single instance may be referred to here. Forces constituting a linear complex are such passing in all directions through each point of space as have their intensity equal to the segments taken on their directions from the point to a certain plane corresponding to it. Forces common to two linear complexes and passing through a given point are confined within the same plane, the distance from the points where their directions meet a given line within the plane being then intensity. Forces, the coordinates of which verify simultaneously three linear equations, are distributed through space in such a manner that there is one force of a given intensity passing through each point of space, or, as we may add, confined in each plane. The general contents of this note (except § IV.) were in a verbal communication pre- sented by me at the last Birmingham Meeting of the British Association. As they concern the principles on which the original paper is based, giving to them a symmetry and a generality I was not before aware of, I thought it necessary to add the note to that paper. At the same time I also endeavoured to give an idea of the great ferti- lity of the method developed. But as I am now preparing a volume for publication on this subject, I do not think it suitable to enter here into any details. The work will embrace the theory of the general equation of the second degree between line-coordi- nates, requiring no means of discussion but those employed by me in the case of equa- tions of the same degree between point- or plane-coordinates. The complex of lines represented by such an equation may be regarded likewise as a complex of curves of the second class, one of which is confined in each plane, or as a complex of cones of the second order, each point of space being the centre of such a cone. In reducing the number of constants upon which the complex depends from 19 to 9, we pass in parti- 788 DR. PLUCKER ON A NEW GEOMETRY OF SPACE. cularizing step by step from the general complex to a surface of the second order and class, determined by its tangents. I intend resuming the consideration of the mechanical part of this note. Then a last generalization will occur to us, the equation of condition, hitherto admitted between the six coordinates x, y, z, L, M, N, being removed. CONTENTS. I. On Linear Complexes of Might Lines. Preliminary explanations. — Point-coordinates. Equations between them representing surfaces by means of their points. Plane coordinates. Equations between them repre- senting surfaces enveloped by planes, 1. Double definition of right lines, either by means of their points or by means of traversing planes. Pays. Axes. The two pro- jections of a ray within two planes of coordinates depend upon four linear constants, which may be regarded as ray-coordinates, r, s, g,