.X>^^ Ti^i<^ XiiL.'^t "r.at ;^^^^^^'¥rMlf^^ rN ^/\ '^^'if^ «m^^ A'>-\ r •-,>?-., m^^k^^ ,fN^H\. -^ftf^f^u^ £1:1 ^^;._'--rs^ '^s^r^- ' ^;?^.^.?^n^ WW ''"'.v;^: ^'A/^ ■^./ ■■LMvf^ •Mfmi .f\^^ >:-m«? W^<^ m^ %Mv^:' ^SsL.:^s^ mh. A 4^ /. R EXM^ .R D S ?r 1 -^.V^^^' GENERAL -SCIENCE, BY ROBERT D. THOMSON, M. D. PHYSICIAN TO THE FREE DISPENSARY, BLENHEIM STREET, AND LECTURER ON CHEMISTRY, IN THE BLENHEIM STREET MEDICAL SCHOOL. WITH THE ASSISTANCE OF THOMAS THOMSON, M.D., F.R.S.L.&E.,F.L.S., F.G.S.,&c. REGIUS PROFESSOR OF CHEMISTRY IN THE UNIVERSITY OF GLASGOW. VOL. LV. LONDON: TAYLOR AND WALTON, UPPER GOWER STREET, Booksellers and Publishers to the University of London ; and SOLD BY MACLACHLAN AND STEWART, EDINBURGH ; JOHN REID AND CO., AND RUTHER- GLEN AND CO., GLASGOW ; W. CURRY, JUN., AND CO., AND R0HERTSON AND CO., DUBLIN ; KING AND CO., CORK j GRAPEL, LIVERPOOL ; WEBB AND SIMMS, MANCHESTER ; AND BARLOW, BIRMINGHAM. 1836. Printed by W. Johnston, 13, Mark Lane. TABLE OF CONTENTS No. XIX.— J^M/y, 1836. PAGE I. Biographical Account of Sir Humphry Davy, Bart. . II. Experiments and Observations on Visible Vibration. By Charles Tomlinson, Esq., continued ...... III. On a New Oxide, similar to that of Donium. By Henry S. Boase, M.D IV. Description of a New Hygrometer, &c. By John Abraham Mason, M.D., M.R.C.S.E., &c V. Catalogue of Plants collected at Bombay. By John Graham, Esq. VI. Experiments on the heat or cold produced by dissolving Salts in Water. By Thomas Thomson, M.D., F.R.S.L. & E., &c. VII. On some Astronomical Methods of Observation. By William Galbraith, A.M VIII. On a Difficulty in Isomorphism, and in the received Con- stitution of Oxygen Salts. By Thomas Clark, M.D., &c. IX. Examination of the Water at the North Well of Scarborough. By Robert D. Thomson, M.D X. The Art of Dyeing, continued XI. Analyses of Books 1. Narrative of an Excursion to the Lake Amsanctus, &c. By Charles Daubeny, M.D., F.R.S., &c. ... 2. The Equilibrium of Population and Sustenance demonstrated. By Charles Loudon, M.D 3. Observations on the present state of Naval Architecture, &c. By J. Beamish 4. On the Theory of Ratio and Proportion, as treated by Euclid, including an Inquiry into the nature of quantity. By the Rev. Baden Powell, A.M., F.R.S., &c. 5. Vol XVII. The Transactions of the Linnean Society. part 3rd, 1836 XII. Scientific Intelligence, &c. 1. Pharmacy 2. Westminster Medical Society 3. Oxide of Zinc, antidote to Belladonna 4. Volatile Oil of Spiraea Ulmaria . 5. New Hydrate of Carbonate of Magnesia . 6. Mode of preparing Azote 7. Ice a non-conductor of Electricity 8. Residuum of Fired Gunpowder 9. Creosote as an Antisceptic .... 10. Lithotrity employed in Persia in Ancient Times 11. Calcaire grossier on the Garonne Note on Dr. Boase's paper .... Silkworms 77 British Association for the Advancement of Science . ib. Notice of New Books ib. Observations on Temperature, &c. By John A. Mason, M.D., &c. . . 78 Meteorological Journal. By the Rev. J. Wallace . . .80 12. 13. 14. 15. 16. 12 20 23 35 40 42 45 53 54 63 ib. 66 ib. 67 68 70 ib. 71 73 ib. 74 ib. ib. 75 ib. ib. 76 ib. IV CONTENTS. JNo. XX. — August. PAGE I. Biographical Account of Sir Humphry Davy, Bart., continued . 81 II. On the formation of Sulphuric Afcid. By Thomas Thomson, M.D., F.R.S.L. & E., &c 93 III. Description of a New Hygrometer, &c. By John A. Mason, M.D., M.R.C.S.E., &c 96 IV. Catalogue of Plants collected at Bombay. By John Graham, Esq., continued Ill VI. On the Chemical Composition of Human Blood. By Mr. Thomas Richardson . . . . . . .116 VII. On some Astronomical Methods of Observation. By William Galbraith, A.M., continued . . . . . .127 VIII. On the Curved Figures produced by rapidly Rotating Disks. By Charles Tomlinson, Esq., continued .... 135 IX. Analyses of Books 142 Transactions of the Linnean Society. Vol. XVII. part. 3rd, 1836 ib. X. Scientific Intelligence, &c. ....... 147 1. Pharmacy, &c. ........ ib. 2. Phenomena of Chry stall ization ..... 150 3. Uric Acid Calculi in the Biliary Canals .... 151 4. Effect of the Price of Corn upon the Population . . ib. 5. Impurity of Sulphuric Acid . . ... - 152 6. Tests for Strychnin ....... ib. 7. Fossil Flowers ib. 8. Composition of Silk ....... 153 9. Analysis of Phosphate of Lead. By Dr. R. D. Thomson . ib. 10. Effect of Alkalies, &c. on Vegetables . . . . ib. 11. French School of Pharmacy . . ... . 154 12. Death of Professor Geiger 155 13. Alpine Plants of Cote D'Or . . . . - . . ib. 14. Ozokerite, a mineral subtance ..... ib. 15. Additional Notice of an Oxide similar to Donium. By H. S. Boase, M.D., &c 156 16. Showers of Frogs ....... ib. 17. Luminous Vibrations in Diaphanous Media . . . ib. 18. Globules of the Zannichellia palustris . . . . ib. 19. White Crystalline Grains in the Intestines . . . 158 20. Two Concretions found in the Knee of an Old Man . 159 21. Analysis of Copper Pyrites. By Mr. Thomas Richardson . ib. 22. Meteorological Table .160 No. XXl.—Septemher. L Biographical Account of Sir Humphry Davy, Bart., concluded 161 II. Experiments on the Absorption of Air by Water. Bv Thomas Thomson, M.D., F.R.S. L. &E., &c. . . . ' . . 170 ni. On Manganic and Hypermanganic Acids, &c. By E. Mitscherlich 178 IV. On some Methods of Astronomical Observations. By William Galbraith, A.M., continued 183 V. Catalogue of Plants collected at Bombay. By John Graham, Esq. 194 VI. On the Differences of Temperature between the Granite and Slate in the Cornish Mines. By W. J Kenwood, F.G.S., &c. . 198 CONTENTS. V PAGE VII. The Art of Dyeing, continued 199 VIII. A Theory of Accidental and Complementary Colours. By Charles Tomlinson, Esq. . 208 IX. The Atmosphere in relation to Malaria . . . . 217 X. State of the Austrian and Hungarian Mines. By Messrs. Foy, Harle, and Gruner 221 XI. Analyses of Books . . . . . . . .224 Transactions of the Royal Society of Edinburgh. Vol. XIII. . ib. XII. Scientific Intelligence 226 1. British Association for the Advancement of Science . . ib. 2. Pharmacy, &c 229 3. Impurity of Zinc and Sulphate of Zinc .... 231 4. Utility of Carbonate of Barytes ... .' . 232 5. Adulteration of Nitrate of Silver ib. 6. Combination of Sulphuret of Lead with Chloride of Lead ib. 7. Chloro-Sulphuret of Antimony ib. 8. Gallic Acid in Crystals . . . . . .233 9. Action of Oxalic Acid upon Sulphate of Iron, &c. . . ib. 10. Ferrocyanodide of Ammonia ...... ib. 11. New method of reducing Litharge employed at Freiberg . 234 12. Absorption of Oxygen by Platinum and Iridium . . ib. 13. Compounds of Bromine and Oxygen .... ib. 14. Triple Compounds of Osmium, Iridium, &c. . . . 235 15. Carbonate of Iron of Traversella . . . . . ib. 16. Method of detecting minute quantities of Sulphur . . 236 17. Tin discovered in Brittany ...... ib. 18. Employment of Iron in Suspension Bridges. By M. E. Martin 237 19. Oil of Canella ib. 20. Table exhibiting the Comparative Weight of Sea Water at different places in Holland 239 21. Essence of Turpentine ....... ib. 22. New Books . . ib. 23. Meteorological Journal . . . . . . 240 No. XXll.'^Octoher, I. Biography of M. Le Comte Lagrange. By M. Delambre . . 241 II. Experiments on the Combination of Sulphuric Acid and Water. By Thomas Thomson, M.D., F.R.S. L. &E., &c. . . 252 III. Important Facts derived Mathematically from a General Theory, embracing many results in Chemistry, &c. By T. Exley, A.M. 267 IV. A Theory of Accidental and Complementary Colours. By Charles Tomlinson, Esq., concluded . . . . . 288 V. Economical Mode of forming Hy permanganate of Potash. By William Gregory, M.D., F.R.S.E. . . . .297 VI. Analysis of Tartar Emetic. By Mr. Thomas Richardson . . 299 VII. Catalogue of Plants collected at Bombay. By John Graham, Esq. 300 VII. Scientific Intelligence . . . . . ... 303 British Association for the Advancement of Science . . . ib. No. XXl\l.—Novemha\ I. Notice of Carburet of Potassium, and of a New Gaseous Bi-carburet VI C50NTENTS. PAGE of Hydrogen. By Edmund Davy, Esq., Professor of Chemistry to the Royal Dublin Society 321 II. On the Atomic Weight of Nickel and its Oxides. Bv Thomas Thomson, M.D., F.R.S., &c. . . . '. . 323 III. On Manganic and Hypermanganic Acids, &c. By E. Mitscherlich 331 IV. New Demonstration of the Law of Mariotte, with Corrections of a Former Paper. By T. Exley, A.M. ... 336 V. On some Astronomical Methods of Observation. By William Galbraith, A.M., concluded 341 VI. On Capillary Attraction, and on the Disposition there is in Fuids to assume a Globular Form, &c. By Paul Cooper, Esq. . 344 VII. On Internal Prismatic Reflexion. By Mr. George Dodd . 352. VIII. On some Silicates of Alumina. Bv Robert D. Thomson, M.D. 359 IX. On Resins. By Henry Rose 365 X. The Art of Dyeing, continued 371 XI. Analyses of Books 376 The Botanist, containing accurately coloured Figures of Hardy and Ornamental Plants, &c. By B. Maundy F.L.S. and Professor Henslow. 4to. No. I. . . . . . ib. XII. Scientific Intelligence ........ ib. 1. British Association ib. 2. Death of Dr. Henry, of Manchester 394 3. Artificial production of Metallic Sulphurets, &c. . . 397 4. Royal Geological Society of Cornwall ..... 398 Meteorological Journal 400 No. XXIV. — December. I. Biography of M. Le Com te Lagrange ..... 401 II. Abstract of a Letter from M. Cacciatore, Director of the Observa- tory of Palermo, respecting the Moveable Star observed in 1835 404 III. On the Minerals containing Columbium. By Thomas Thomson, M.D., F.R.S.L.&E., &c .407 IV. Experiments and Observations on Visible Vibration. By Charles Tomlinson, Esq 419 V. On Accidental Colours and Coloured Shadows. By P. Cooper, Esq. 427 VI. Notice of some Recent Improvements in Science . . . 444 VII. Determination of the Obliquity of the Ecliptic at Edinburgh. By W. Galbraith, A.M 450 IX. The Art of Dyeing 452 IX. Analyses of Books ......... 455 1 . Philosophical Transactions of the Royal Society of London for 1836. Parti ib. 2. On the Gales and Hurricanes of the Western Atlantic . . 456 X. Scientific Intelligence ........ 457 1. British Association for the Advancement of Science . . ib. 2. Belfast Museum 470 3. Pharmacy, &c. ......... ib. 4. Easy Method of preparing Spongy Platinum . . . 472 5. Temperature of Space ....... ib. 6. Acid Beer ......... ib. Books Announced or Newly Published 473 MeteorologicalJoumal 474 IFL «<>fr «»il RECORDS OF GENERAL SCIENCE. Article I. Biographical Account of Sir Humphry Davy, Bart.^ The actions of those who have stood well in the eyes of their fellow-countrymen form always subject for pleasant consideration , but when these actions have been in the highest degree brilliant, when they have conferred benefits upon society which we have no measures for precisely calculat- ing,— and have opened new channels for the improvement of society, the claims upon our attention are completely irre- sistible. Such a demand, is but an act of justice to that great philosopher Davy, whose fame is not of the ephemeral nature of those who like some flowers of other lands shoot up, bedecked with imposing beauty, and rapidly disappear — the tenants of an hour — no more to spread their buds to the refreshing dew drop. Humphry Davy, the son of Robert Davy, a Builder, and Grace Millett, was born on the 17th of December, 1778, in Market Jew Street, Penzance. The origin of his family, he appears to have been anxious to ascertain, but could not succeed in tracing it back beyond 200 years, during which period, according to the tombstone in the parish churchyard of Ludgvan, many of his forefathers occupied the respect- • This Memoir has been drawn up from the materials afforded by the able and delightful " Memoirs of the Life of Sir Humphry Davy, Bart., by his brother John Davy, M. D., &c." It is impossible to refrain from admiring the affectionate spirit which has dictated these memoirs. But it is a subject of question, whether it is consonant with that strict impartiality with which every pubhc man ought to be, and will ultimately be dealt with. VOL. IV. B 2 Biographical Account of able position in society of yeomen. His father, who was a person of some capacity and ingenuity, died in 1794, and left his family consisting of five children to the care of his widow, then in her 34th year. She lived to the advanced age of 76. She possessed a good understanding, benevo- lent disposition, and a pious mind. When she became a widow her income was about £150 a year, and it was incum- bered with a debt of about £1300, contracted by her hus- band in consequence of losing speculations in mining. Her prudence, economy, and admirable exertions speedily, how- ever, relieved her from her distressing circumstances. To aid in extricating herself she engaged in partnership as a milliner with a young French lady, who had fled from France during the revolution. The business was only car- ried on for three or four years, when she was left some pro- perty which increased her income to £300 a year. Under the fostering care of such a parent, it would have indeed been remarkable, if the subject of our memoir had not begun to shew early proofs of developement of genius, and to have imbibed some of her excellent disposition. The first school he was sent to, was kept by a Mr. Bushell, a teacher of reading and writing, and who, observ- ing the rapid progress of his pupil, recommended him to be sent to the grammar school, when only six years of age. The teacher of the establishment (Mr. Coryton) was a care- less, indiscriminating tyrant, like too many of his class at that period. In accordance with his character, he punished slight offences very severely, thus holding out encourage- ment to his pupils to commit grave offences, and quenching the acuteness of the moral principle. He was continually torturing his poor dependants by pulling their ears. Davy suffered often in this way. On one occasion, the pupil deli- cately reproached the master. The master observing him with a large plaster on his ear, asked him the nature of the disease, he replied, with proper gravity, that " he had put the plaster on to prevent mortification." At the grammar school he was not distinguished for his scholarship, although his appearance was respectable. He shone more in the facility with which he wrote Latin and English verse, and in writing valentines and love letters. He shewed an early disposition for tales and imaginative Sir Humphry Davy, 3 descriptions, and for angling, an art which is so intimately allied to the wild scenery of nature. He quitted school in December, 1793, at the age of 15, and returned from Truro to Penzance ; here he took up his abode with Mr. John Tomkin, Surgeon, who had defrayed his expenses during his twelve months, residence at Truro. In the subsequent year his time was occupied according as inclination dictated, in fishing, shooting, swimming, and in solitary rambles. His father dying in 1794, produced an alteration in his employment, and in 1795, he was apprenticed to Mr. Bing- ham Borlase, a surgeon and apothecary, in Penzance. At this period, he began to register carefully inferences from the information acquired during his reading, and some ex- tracts from his note books, exhibit the nature of the studies which interested him most. Extracts given in his brother's life of him, exhibit his idea of a plan of study. In con- sonance with the results of his after life, we find that he places mathematics at the end of the course ; a plan which has since been advocated by others. To say the least of it, however, it is one which strikes at the root of concise- ness and precision, for nothing can contribute more to these desirable, nay, indispensable objects in science than a sub- stantial mathematical ground-work. The absence of this is obvious in many parts of Davy's scientific writings, and renders his meaning sometimes very ambiguous. It would be an easy task to point out faults, from a similar defect in the writings of all those who have not been reared in the mathematical school. He did not begin to study the ma- thematics till 1796, when in his 18th year. But his more favourite study was metaphysics occasionally intermixed with poetical sallies. In 1797, he engaged in natural phi- losophy, and principally as with his other studies under his own tuition. In November or Decepaber, when just entering upon his 19th year, he turned his attention to chemistry. This was an important period of his life. Like most of his great pre- decessors his apparatus was of the most simple nature. His bed-room constituted his laboratory ; some phials, wine glasses, a few tea-cups, tobacco-pipes and earthen crucibles, his instruments. That this was the line in which he was destined afterwards to shine was soon apparent ; for in the . b2 4 Biographical account of April following, or in the short space of four months, he entered upon a correspondence with Dr. Beddoes, relative to his researches on heat and light, and a new hypothesis of their nature, to which the doctor became a convert. His results were published in 1799, in his " Essays on Heat and Light." His rapid advancement was promoted by several fortunate circumstances. In the winter of 1797, Mr. Gregory Watt, fresh from the University of Glasgow, visited Penzance, and boarded with Davy's mother. Davy speedily became acquainted wdth him, and the acquaintance soon ripened into a close and disinterested friendship. They explored the coast together, visited the most remark- able mines and investigated the natural history of the dis- trict. These were no small advantages. The acquaintance of Davy with Mr. Davies Gilbert was also of great importance to him, although the benefits re- sulting from it have been more insisted on by some autho- rities than Dr. Davy considers the facts of the case war- rant. The manner in which they became acquainted was ac- cording to the authority of Mr. John, of Penzance, as follows : Davy having requested Mr. John to witness some chemical experiment, he remarked that he did not understand these things, but that his friend Mr. Davies Giddy (now Davies Gilbert) did. An introduction was the consequence. During his medical studies his progress must have been considerable, for in the fourth year from their commence- ment he was considered competent by Dr. Beddoes, to take charge of the patients belonging to the Pneumatic Institu- tion. On the 2nd of October, 1798, he left his home to accept the office of superintendent of the Clifton Institution. This was the second grand period in his life. It was the outset on his splendid career. He had made as much pro- gress it would appear as circumstances would admit of: '* I have now made all the experiments I can make here," he observes, in one of his note books. It was in 1799, that he first appeared in the character of a scientific author ; when his Essays on Heat and Light were published, in a miscellaneous volume edited by Dr. Beddoes, termed *' Con- tributions to Medical and Physical Knowledge, principally from the North of England.'' They deserve little attention, except as being his first productions, for they consist prin- Sir Humphry Davy, Bart. 5 cipally of inferences hastily deduced from a few isolated facts. Davy himself often regretted that they had ever been published, as he fancied they had left a bad impression. Strange it is, however, that although the theories contained in them are but the rambling speculations of a youthful ima- ginative mind, some of them were actually adopted by the grave Dr. Beddoes. In 1800, he wrote his " Researches, chemical and philosophical, chiefly concerning nitrous oxide and its respiration." The discovery that nitrous oxide produces the remarkable physiological effects of exciting symptoms of inebriety, produced a great sensation, not only in Bristol, but all over the world. Fortunately, the fame of Davy does not rest upon such a deservedly fleeting and frail basis. The value of the discovery was exaggerated beyond all bounds ; according to some authorities the very nature of man was prospectively altered ; he was to breathe a new at- mosphere. But when excitement has attained a high pitch the succeeding stage is low and depressed. The discovery is now almost forgot. The action of the gas in the manner described by Davy, is actually considered by some as pro- blematical. A remarkable instance of the ambiguous nature of its effects was elicited by a distinguished chemist, who administered a dose of nitrous oxide to an Irish gentleman, who exhibited all the fantastic manipulations described by Davy. The effect, therefore, appeared de- cisive ; but unfortunately the philosopher, who was the subject of the experiment, having requested, after re- covering from his fit of gladness, that another dose should be administered, a cargo of common air was served up instead of the oxide ; the consequences were even more violent than in the previous experiment. It is obvious, therefore, that the imagination plays no' inconsiderable part in this species of simulated mania, or at least, that it is only on persons of lively imaginations that such effects can be produced. Notwithstanding his labours in the Pneumatic Institution, Davy continued to devote a considerable portion of his time to essay writing upon miscellaneous subjects, and to sonnet and poem writing. The fragments of some of these which have been published, shew, that had his mind been more closely devoted to the study of poetical refinements, he 6 Biographical account of would have figured as a poet. But more useful work was in store for him. In February, 1801, he went to London, having been appointed assistant lecturer at the Royal In- stitution, a fine establishment, founded by an American of considerable celebrity, Count Rumford. He delivered his first lecture in the course of six weeks after, and was favour- ably received. It has been asserted, that the simplicity of Davy after this time was converted into flippancy and neglect of friendships. However much this assertion may have been overstrained, it is generally understood that his demeanour underwent a change, and that his manners were not sufficiently of that open, frank, and unostentatious kind which are so becoming in the true philosopher. Davy's success was remarkable, and it would have re- quired uncommon care to have seasoned his mind against the tempting powers which were mustered around him. It has been stated, that he now " assumed the garb and airs of a man of fashion," that " the bloom of his simplicity was dulled by the breath of adulation." Dr. Davy excited by those affectionate feelings which are so delightfully apparent in every page of his life of his brother, has denied that there is any truth in these calumnies, as he appears to consider them. He has, in consequence, brought forward proofs from a number of individuals to whom he wrote friendly letters, as he considers them, that Davy was not what he has been represented to be in this respect. But, if such letters prove any thing, they only shew that towards those individuals he entertained the feelings expressed in his letters. They do not prove that he did not exhibit hauteur to other individuals, or that his notions and man- ners were not too aristocratical for a man of science. His success as a lecturer, however, was at once complete. He was received by crowded audiences, and the Institution became a fashionable resort. During the greater part of the day he was engaged with the business of the laboratory, where the powers of his ex- panding mind were applied to original research. Yet his time was not systematically occupied. When in town, he generally entered the laboratory after breakfast, about ten or eleven o'clock, and if uninterrupted remained there till three or four. Instead of returning to the laboratory after Sir Humphry Davy, Bart. 7 dinner, he was much in the habit of attending evening parties and devoting much of his time to amusement. When his duties did not keep him in town, he often made short visits to friends residing in the neighbourhood of London, or he went to some good trouting stream, and enjoyed the country and his favourite exercise of fishing. After the conclusion of the session of 1801, he visited his friends at Bristol and Penzance. In 1804, he visited Scot- land and the western islands. In the summer of 1805, he made a journey to the North of Ireland for the purpose of examining the giant's causeway, and passed through the greater part of the island, indulging, when favourable op- portunities occurred, in his favourite exercise of angling. In the mountain district of Donegal he *' met with a singu- lar race of beings, the most gifted with vague curiosity of any men I have seen. They asked questions, without consi- dering whether they were civil or uncivil, and seemed little daunted by reproof. * Where do you come from V ' Ra- melton.' * Do you belong there?' * No.' * What place do you belong V ' London.' ' Is it war or peace V ' War.' * Have the English lost any men?' 'There has been no battle lately.' ' When was the last?' * Lord Nelson's. Did you never hear of him V * No.' 'What is your name?' * It is a name you have never heard and never will hear of.' " They all agreed that there were old men who knew the history of the Finns and Finn Macoul in Gaelic, but no one could shew me the abode of these sages. His senti- ments in reference to the political state of that lovely, but unfortunate portion of our empire, is worthy of note : " All are slaves, without the probability of becoming free ; they are in the state of equality which the Sans culottes wished for in France ; and until emulation and riches, and the love of clothes and neat houses are introduced among them, there will be no permanent improvement; changes in political institutions can at first do little towards serving: them. It must be by improving their habits, by diffusing manufactures, by destroying middle men, by dividing farms and by pro- moting industry." In the note book which he carried with him, he inserted observations on the geology of Ireland. His power and deep observation were ever active, and he allowed no opportunity to escape of benefiting science, 8 Biographical account of even amid the bleakness and wildness of the least favoured of nature's scenes. For some years, he appears to have made no original discoveries, or at least, his laboratory labours were not at- tended with any striking results. Electricity constituted at the commencement of the century a fruitful field for investigation. The pile of Volta had opened the way to many curious discoveries ; but want of care led to some strange deductions ; the pile was actually supposed to gene- rate muriatic acid and alkali in water ; because these sub- stances were obviously present when water was made to complete the circuit. Our author turned his attention to this curious question. ** It was in the beginning of 1806," says he, ** that I attempted the solution of the question, and after some months' labour, I presented to the society the dissertation, to which I have referred in the beginning of the lecture. Finding that acid and alkaline substances, even when existing in the most solid combinations, or in the smallest proportions in the hardest bodies, were elicited by voltaic electricity, I established that they were the re- sults of decomposition, and not of composition or genera- tion. I drew the conclusion, that the combinations and de- compositions by electricity were referable to the law of electri- cal attractions and repulsions, and advanced the hypothesis that chemical and electrical attraction were produced by the same cause, acting in one case on particles, in the other on masses, and that the same property under different modifica- tions was the cause of all phenomena exhibited by different voltaic combinations'' The paper which developed the deductions from his ex- periments was in reality a noble one. It *' constitutes," says Dr. Thomson, '* one of the most important contributions ever made to scientific chemistry, and threw a ray of light upon chemical affinity which may ultimately produce the most important consequences." To this paper the French Insti- tute awarded the prize founded by Napoleon for the most important discoveries in galvanism. The researches de- scribed in this memoir were quite original, and were carried on without the most distant connexion with any experi- ments conducted by others. The claims, therefore, of some continental chemists to supersede him are quite futile. The observation of Dr. Davy is perfectly correct. The Sir Humphry Davy, Bart. 9 Bakerian lecture of 1806, owed nothing to the labours of these gentlemen, and it would have been in every respect as complete had they never been published ; but had this lecture been suppressed a vast accession of knowledge would have been lost to the world." But a short interval elapsed after his installation at the Royal Institution, till, at the request of the managers, he turned his attention to tanning. He set about the investi- gation with proper spirit, probed the subject to the bottom by visiting the lanyards, eliciting information from the workmen,and where their evidence was deficient in reference to the grand object of improving science, he endeavoured to fill up the hiatus by the results of original research. The consequences of his labours were published in his ** Account of some Experiments and observations on the constituent parts of certain Astringent vegetables, and on the operation in tanning," in the Philosophical Transactions for 1803. About the same time, he entered upon the study of agricultural chemistry, and gained so much information that he was requested in 1802, to deliver a course of lectures to the board of agriculture " On the connexion of Chemis- try with Vegetable Physiology." His lectures, which were afterwards regularly delivered before the board for ten years, were published under the title of " Elements of Agricultural Chemistry." Several important points were made known in these lectures, and the method pointed out by which agriculture, instead of being a mere random mis- cellany, might become a true science. His application of scientific views to practice is every where obvious in the pages of the work, but is particularly so under the head of manures; " the great object in the application of manure should be to make it afford as much soluble matter as possible to the roots of the plant, and that in a slow and gradual man- ner, so that it may be entirely consumed in forming its sap and organized parts, he connects this with the chemical principles of his theory ; viz , that the fermentation of ma- nures necessary for the solution of these soluble parts should be a regulated process, and as it is connected with decomposition it should be stopped as soon as the end for which it was instituted is attained." It is not meant to be maintained that his views were infallible, but that they 10 Biographical account of were plausible and formed important contributions to agri- culture as a science was at once obvious. He conceived, that lime was injurious in the form of quick-lime, and that it proved beneficial by accelerating the decomposition and promoting the solution of any hard vegetable matter in the soil, contrary though it be to the views of many, who con- sider that it acts as an instrument of saturation to the free ulmic acid generated in the vegetable portion of the soil. The beneficial action of gypsum on vegetables he attributes to its entering into the composition of vegetables. This opinion as stated exactly by Davy has not been corroborated by Peschier* who found that the action of this salt upon vegetables was in direct proportion to its state of solution, and that its influence is null except when it is dissolved. His experiments lead to the conclusion, that the sub- stance is decomposed by electrical powers possessed by the assimilating organs of the plant, and that the sulphuric acid is set at liberty and combines with the potash in the sap. Besides his study of agriculture, he became interested with the investigations of meteorology, and in one of the num- bers of the Institution Journal, he described his eudiometer affording a simple method for ascertaining the proportion of oxygen and azote in the atmosphere. It consisted merely of a graduated glass tube and a solution of muriate or sul- phate of iron at the minimum of oxidation, saturated with nitrous gas. He published about this time, a paper on the collision of steel and hard bodies, bearing on the question of light, in the Institution Journal. In the Philosophical Transactions for 1805, he published an analysis of Wavel- lite, and another on the uses of boracicacid. But his most important contribution to analytical chemistry, was con- tained in his Bakerian lecture for 1806. " On some chemi- cal agencies of electricity." At the conclusion of this paper he makes some interesting observations on the nature of electric chemical action in the mineral kingdom, which have since been confirmed hy the researches of Becquerel. He attributes the alteration in many of the rocky strata to the influence of electrical agency. We come now to the year 1807 the most important in his * Records of General Science, iii. 477. Sir Humphry Davy, Bart. 11 brilliant career. In conformity with his views of over- powering chemical attraction by electrical power, he in- stituted a series of experiments on the vegetable alkali. He began the investigation in September, and on the 19th of November, he delivered his second Bakerian lecture to the Royal Society. It was entitled " On some new pheno- mena of chemical changes produced by electricity ; parti- cularly the decomposition of the fixed alkalies and the exhibition of the new substances which constitute their basis, and on the general nature of alkaline bodies." Many vague notions had been formed of the nature of the vege- table alkali. Some Italian and French chemists considered it a compound of lime and hydrogen. Others supposed that it contained azote. Davy thought it might consist of phosphorus, or sulphur united to azote; for, as ammonia was regarded as a compound of hydrogen and azote, he con- ceived, that phosphorus and sulphur, much denser bodies, might produce denser alkaline matter. In his first trials, he used strong aqueous solutions of potash. ** Dry potash," says he, in one of his lectures, '* is a non-conductor ; I then employed fused potash, and in this instance, inflammable matter was developed ; then a piece of potash moistened, and to my great surprise, I found metallic potash formed. October 6th. This matter instantly burned when it touched water, and swam on its surface re-producing potash. In dry oxygen gas likewise, it burnt into perfectly dry potash. Soda was decomposed in the same manner. The earth had been suspected by the elder chemists, particularly by Boyle, Becher, and Stahl, to be capable of conversion into metallic substances though they had vainly sought for modes of effecting this important desideratum. When I had discovered in so unexpected a manner that potash and soda are metallic oxides, all the former analogies became strengthened to a degree that the question of the nature of the earths was of easy solution ; but though so much more like metallic oxides than the fixed alkalies, yet I found much more difficulty in effecting their decomposi- tion." His delight on discovering these facts was excessive ; Mr. Edmund Davy, who was present, states, that when our philosopher saw the globules of potassium burst through the crust of potash and take fire as they entered the atmos- 12 Mr, Charles Tomlinsons phere, he could not contain his joy ; he actually danced about the room in ecstatic delight. Thus was a new light thrown upon this branch of chemistry. Perhaps, the discovery has been too highly lauded, but there can be no question that it was a great discovery. The author, undoubtedly, had some strong ana- logies to conduct him in his research. It was, therefore, dissimilar to the results of Newton ; the one was the conse- quence of the action of a powerful agent, directly applied ; the other, of observation, deep reasoning, and mathemati- cal calculation. (To he continued.) Article II. Experiments and Observations on Visible Vibration, By Charles Tomlinson, Esq. ( Continued from vol. iii. page 370.^ 101. This splashing of the water can, however, be pre- vented by covering the surface with a very thin coating of lycopodium ; the vibration of the glass will dispose the curved line round its interior side and a similar line will be formed on the surface of the water, the arcs in both cases corresponding with each other ; and, in this way, by careful application of the bow, sets of figures can be obtained analogous to that which has already been given (81) as the fundamental figure when mercury is employed. These figures can be obtained from glasses of any shape or dimen- sions, and I have usually employed coloured water, sifting a light coating of lycopodium upon the surface. The follow- ing and analogous figures, however, were obtained from the conical glasses two- thirds filled with coloured water: figure 3 indicating four nodes resulting from the lowest tone. The second tone affords a figure of six curves, and from the third tone a figure of eight curves indicating eight nodes is obtained, and so on, increasing two curves in the figure for every ascending tone. The curves within the circumference represent the extent of the repulsion of the dust from the centre of vibration, which is indicated by dots placed upon the circumference, which is of course the Observations on Visible Vibration. 13 interior surface of the glass itself, and the dotted curves without the circumference may be considered as indicating the upward motion of the liquid waves against the sides of the vessel, caused probably by the rebound of the liquid after the first imj)ulse. The points of collapse of the two systems of curves are the nodes where the liquid is not dis- turbed during vibration ; thus the figure during vibration represents four, six, or eight waves, with as many corres- ponding troughs or hollows between every two waves. Fig. 3. This figure may also convey an idea of the six, eight, ten, and twelve curved figures, all of which are very perfect of their kind, and indicate correctly the divisions of a sonorous vessel necessary to produce a note of a certain pitch. 102. The perfection and beauty of the figures is much in- creased, when, instead of a slight coating of lycopodium, a thick one is applied to the surface of the water, so that the upper surface be kept dry and free to move ; thus, figure 4 represents an effect of this kind where the outer dots as before represent the vertical curves, and the surface exhibits a star of four fans, composed of the dry powder ; these fans are truncated within one-sixth of an inch of the glass, while the semicircular spaces have only a thin adhesive coat. It would appear that the first application of the bow throws the dust up the glass where it remains, while the horizontal figure is the result of many oscillatory movements of the water, the distance of the truncated ends of the fans from the glass remaining constant somewhere between a quarter and one-sixth of an inch. In some cases by close inspec- 14 Mr. Charles Tomlinsons tion the imprint of minute parallel waves between the truncated ends and the glass could be seen in action. Fior. 4. In this way a variety of pleasing figures can be obtained, all of which are in strict accordance with the note produced, whether fundamental or secondary, the former invariably producing stars of four points, or four distinct accumula- tions of the powder, and the latter increasing two for every ascending tone. By employing alcohol the funda- mental tone produces Chladni's first figure, formed by globules of the liquid ; thus in figure 5 the globules seem to be generated simultaneously at the centre of vibration as indicated by the fans, and are thrown upon the quiescent portion of the liquid and point out the nodes. Fi-. 5. This figure is of course only seen while the glass is being operated on by the bow. Lycopodium sinks in alcohol, but a film of minute particles remains on the surface, which Observations on Visible Vibration. 15 receives the impress of the figure, and from the great mobi- lity of the liquid, minute changes are by its means detected. Analogous figures have been obtained from the secondary tones, the points of the star always increasing in number as before stated. Similar results have to a certain extent been obtained when vessels of porcelain, crokery-ware, and metal have been employed ; this part of the subject will be re- sumed. 103. Another excellent method of ascertaining the num- ber of nodes for any given note on a foot glass of any shape, is by employing a limpid oil such as linseed oil.* This is incomparably superior to water when employed without lycopodium, as it does not vibrate and no splashing whatever results. The glass may be about half filled with the oil, care being taken in pouring the fluid to preserve the surface of the glass above the oil perfectly clean and dry. The note must be produced by a strong and rather sudden stroke of the bow, the pressure of the latter being increased in drawing it down, but at the same time the glass must not be shaken. The curved line under these circum- stances will be distinctly and perfectly marked round the glass by the elevation of the waves. The fundamental note will yield a line of four undulations, while for the secondary tones the lines will consist respectively of six, eight, ten, and twelve undulations. 104. A figure can also be impressed upon the surface of mercury contained in a foot glass by means similar to those employed for water. A very slight coating of lyco- podium being given to the mercurial surface, it was strongly * The peculiar whining tone produced by lowering the tension of a string during vibration is well known. This effect can be imitated by strongly vibrating a glass and suddenly pouring in water ; the note is lowered in proportion as water is added, and the whining eflfect is produced by the note passing rapidly through a series of tones to that tone produced by the whole bulk of water added, and the glass still continues to vibrate for some time after the addition of tlie water. It is a curious fact that if oil instead of water be added to the vibrating glass the effect of that fluid is to stop vibration instantaneously, but if oil heated to about 250° be added to the vibrating glass, the note continues precisely as if water had been employed. The cohesive nature of oil will explain tliis, the eflfect of heat being to overcome the cohesion of its particles so as to enable them to glide more easily over each other, and consequently not to become attached to the surface of the glass. The effect of heat upon oils has been already shewn (23 et seq.) and this experiment is analogous. 16 Mr, Charles Tomlimons breathed upon, and tlie sex-nodal division produced by the bow. In the process of vibration while the particles of dust were becoming somewhat agglutinated by the con- densing breath, the motion of the mercury underneath arranged the film into a form analogous to that which the mercury had itself assumed ; when vibration had ended and the mercury become quiescent, the film retained the figure which had been impressed upon it as in figure 6. Fig. 6. This figure assumes the appearance of having been caused by a repulsion of particles from each vibrating centre, shew- ing the inward bellying of the arc of the glass at each centre, and exposing the surface of the mercury by its vibratory action while at the nodes the powder is not disturbed. The point at which the bow is applied becomes a centre of vibration, and such, indeed, is always the case. 105. The nodes having thus been indicated by means of wires, mercury, water, and oil, endeavours were frequently made to ascertain their existence by means of a dry glass and lycopodium, as in the case of glass plates and other plane surfaces, and for a considerable time our patience has been tried unsuccessfully to accomplish on the surfaces of goblets that which is affected by such simple and easy means on plane surfaces. 106. It was obvious that the only favourable form of glass was the before mentioned conical vessel. Powder was lightly sifted upon the interior surface, and the glass then vibrated without the desired effect, the glass was vibrated and the powder sifted into it during vibration, but this was also unsuccessful, and after many such plans the following was resorted to with success. Observations on Visible Vibration. 17 107. The glass being clean and dry, and the powder also well dried, the external surface of the glass was covered with the powder by means of a fine sieve, the distribution being made equal all over the surface by giving the foot of the glass one or two gentle taps to get rid of accumula- tions in particular parts; the bow was then applied to the edge with the precaution of touching the glass at one and the same spot in all the oscillatory movements of the bow, and with an uniform pressure, so as to produce one note only ; and in the first instance this note was the funda- mental note E, first glass before mentioned. 108. When the glass began to vibrate, some of the hea- vier particles of the powder fell down from the external surface, but the lighter particles were, as we at first sup- posed, shaken from the surface, carried upwards, and hover- ing like a slight cloud over the vessel, fell into it and produced a regular quadripartite system on the inclined interior side of the vessel, the powder being collected up the nodal lines and an empty channel at the middle of each vibrating sector as in figure 7. This, however, is not the explanation of the eff'ect as I shall presently shew. Fis:. 7. 109. The above figure was produced by the glass vibrat- ing the note E, with the higher note B ; the result was the formation of six distinct trains down the interior, each train being narrower than in the former instance, and more clearly separated from the intermediate spaces. The trains did not approach so near the apex as in the former in- stance. The second glass yielded similar results ; the lowest note affording four trains, and the higher note E flat eight trains, VOL. IV. c 18 Mi\ Charles Tomlinsons thus in both instances the same in point of nodal arrange- ment as when mercury, oil, water, &c., were employed. 110. These results were obtained from a vast number of trials, all of which, except those now stated, were unsuc- cessful. It was, therefore, necessary to inquire in what consisted our want of success in so many trials, so as to obviate the causes of failure and be able to produce these effects at will. As our trials had been confined to the two conical glasses before mentioned, and having succeeded but twice, I supposed it possible that in consequence of the severe vibratory action to which these glasses had long- been subjected they had lost, in great measure, their nodal properties, if I may so speak, their particles undergoing a certain change, which though producing notes by vibration, did so without a strict and spontaneous division into vibrat- ing sectors.* I, therefore, procured other glasses and on covering the exterior surface as before with lycopodium was gratified by the production of the trains every time I attempted their formation, and found that in proportion as the glass was new so were the trains vs^ell defined and perfect in their formation. They are produced by one bold stroke of the bow, and if not produced at once it is seldom of any avail to apply the bow a second time. 111. There was also another cause which in the former trials militated against success ; the glass and powder were always kept quite dry, and after each trial the glass was well cleaned with a dry cloth and sometimes with soft lea- ther ; this produced a disturbance of electricity which inter- fered greatly with the success of the experiment which may be probably thus explained ; the surface of the glass both exterior and interior acquired positive electricity from the cloth or leather, the latter being negative, the powder being sifted upon the exterior surface of the glass partici- pated in electricity also in a positive state ; its attempts, therefore, to enter the glass would be repelled, at least to a degree sufficient to prevent a symmetrical arrangement of figure. I, therefore, found this objection obviated by pre- paring the glass with powder, &c., and allowing it to re- main several minutes at rest previous to the experiment. • It is known tliat tlie glass plates employed in Chladni's experiments by frequent use become incapable of producing the acoustical figures. Observations on Visible Vibration. 19 112. It has been already stated, that we were at first dis- posed to account for the transference of the powder from the exterior to the interior surface of the glass by consider- ing the lighter particles of the powder to be shaken from the glass, carried upwards by the current, generated in the surrounding air, and so falling into the glass formed the trains on the nodes or quiescent portions, but in the latter and successful trials I soon found that this could not be, because the trains were formed in an instant, before even the bow was taken from the glass, and, indeed, it is easy to see how the trains are formed : as soon as the glass is vibrated the powder by a sort of centrifugal force rushes upwards over the edge, falls into the interior, where a par- tial vacuum is formed by the vibratory action, arranges itself first into a series of innumerable circles distinct from each other round the whole interior surface ; they are then shaken off the vibrating parts of the glass, and accumulate in heaps or trains up the nodes, forming fan shaped figures for the lowest note, and lines for the upper notes, and all this is the result of a moment. 113. The fans and lines can be produced alternating in the same glass, provided the bow be so managed that during the first ^aZf-stroke the low note be produced, and the second half-stroke produce the high note. In such case a very pleasing figure results, which may be represented on a flat surface as in the following figure. Fiff. 8.* * This figure was copied from the glass hy my friend, D. C. Read, Esq., of SaUshury, whose Etchings are so well known in this country and appreciated on the continent. c2 20 Dr, Boase, on a New Oxide It is, perhaps, unnecessary to remark that this figure is contained within an inverted cone, and the above mode of representation has been preferred as being better capable of shewing the details. 114. These figures are seen with best effect when conical vessels made of blue or green glass are employed, the con- trast of the light coloured powder and the dark ground upon which the figures rest, appeal to the eye better than when white glass is employed. 1 15. All the experiments contained in the present paper depend greatly for their success upon the newness of the glass vessels, and the bows ; the latter should have horse hair of the stoutest kind capable of great tension, and rosin should be applied sparingly ; a few days work, how- ever, renders the hair quite useless, and active vibration has similar effects on glass vessels also. An old bow and glass that has been much employed often prevent results which with new instruments are immediately obtained.* Salisbury, March, 1836. Article III. On a New Oxide similar to that of Donium. By Henry S. BoASE, M.D., Secretary of the Royal Geological Society of Cornwall, To the Editor of the Records of General Science. Sir, — I have just read, in your last number, Mr. Richard- son's interesting account of the oxide of Donium, which he has recently discovered in Davidsonite. If I am not mis- taken, it is precisely the same substance as one which I have also found, and for which I had intended to propose the name of Treenium, from Treene the place where it was obtained. I might have announced my discovery to the public, as I • Since the date of the ahove paper, one of the methods proposed (106) for oh- taining the figures in the interior of a conical glass by sifting lycopodium into it, has been successfully adopted, the only precaution necessary to insure success, being the employment of new glasses and a good bow. By new glasses, I mean, such as hare not been employed in vibratory experiments. — C. T. Similar to that of Donium. 21 did to several friends in private, in April last — but before making it known, I was desirous of completing the exami- nation of the other ingredients of the mineral, — which, however, I have not as yet been able to accomplish to my satisfaction. The substance under examination contains a considerable portion of alumina, or rather of a substance which is so- luble in potassa and re-precipitated by muriate of ammonia, yielding crystals of alum with sulphuric acid and potassa. My attention was first called to the new substance, by ob- serving that this alumina was unusually soluble in liquid ammonia; next the pale drab colour of the precipitated alumina, and its change from white to brown by exposure, seemed to indicate the presence of iron or manganese, which, however, I could not detect : and lastly, the fluctu- ating quantities of alumina obtained, led me to examine not only the liquid in which the alumina had been sepa- rated from potassa by muriate of ammonia, but also that in which the sulphate of alumina had been decomposed by excess of carbonate of ammonia, in both of which, there was a substance, which, dissolved in nitric acid and thrown down by ammonia, gave a precipitate rapidly changing from white to pale brown. I then suspected something extraor- dinary, and the addition of hydro-sulphuret of ammonia settled the question, by giving a dense green precipitate. Then recollecting how beautifully the crystals of alum were truncated in ther angles and edges. I applied the same test, after having decomposed and re-dissolved in potassa, and with a similar result. Mr. Richardson does not allude to the fact, but my sulphuret soon changes from green to a yellowish white on exposure in a moist state, on the filter ; and the alkaline solution has a bright green colour from holding some of the sulphuret in solution, which also slowly undergoes the same change with deposition of whitish flocculi. The gr^^n precipitate readily dissolves in nitric acid, with evolution of fumes of sulphuretted hydrogen : and when concentrated by a gentle heat, it has a yellowish colour. With this solution, potassa and ammonia give white pre- cipitates changing to yellow, the carbonates of the same 22 Dr. Roase on a New Oxide, Sfc. alkalies also give precipitates. The pure alkalies re-dissolve the recent precipitates, as do also the carbonates to a cer- tain extent. Ferro-cyanate of potassa causes a slight whitish opalescence, but tincture of galls produces no change. A plate of zinc is soon covered with a slate coloured coating, which, however, does not increase, but is succeeded by drab flocculi, and if the solution be concentrated the whole is gelatinized, and in this state is not very soluble in acids. Muriate of gold does not occasion any alteration. The oxide, or the nitrate, heated with chlorate of potassa, first becomes dark brown, and if the salt be in sufficient quantity, the residue on cooling is of a bright flesh colour. Well washed, an insoluble substance of same colour remains, which soon decomposes giving out bubbles, and returning to its brown colour ; muriatic acid makes it white with evo- lution of chlorine, and nitric acid dissolves it, with extrica- tion of gas. It is probably an oxide at a higher degree of oxidation than the brown. Such is the result I had arrived at, when the oxide was laid aside for more circumstantial examination, after I had ascertained the nature of the other ingredients of the mine- ral, one of which, is an organic acid very perplexing in its composition. Should my oxide prove to be the same as Mr. Richardson's Donium, my name of Treenium must of course give place to his, as he first had the honour of making it public, and I trust that this brief note will insure to me, if not the honour, at least, the credit of also having discovered Donium. The alumina of my substance has probably been derived from decomposing granite, and I am sanguine that some of the peculiarly red granites of the Land's End district, will be found to contain this oxide ; and, perhaps, a re-ex- amination of many minerals will shew that alumina has been mistaken for this substance. By inserting this notice you will much oblige. Sir, Your obedient servant, Henry S. Boase. Penzance, Wth Jtine, 1836. Description of a New Hygrometer. 23 Article IV. Description of a New Hygrometer ; illustrated hy experiments and a comparison of its results with Sir John Leslie's, and the Dew-point Hygrometers, hy John Abraham Mason, M.D., Member of the Royal College of Surgeons, Edin- burgh ; Extraordinary Member of the Royal Medical Society, Edinburgh, Sfc. It has long been a subject of complaint among all prac- tical meteorologists, that we have no Hygrometer which com- bines the advantages of being simple in its construction, easy of application, and unerring in its results. — Persons unaccustomed to scientific pursuits are unwilling to devote their time and attention to complex instruments, and it has occurred to me that good service might be rendered to Meteorology, by devising some method of ascertaining the Hygrometrical condition of the atmosphere, which will combine simplicity with accuracy. I am fully persuaded that moisture has a much greater share in developing the effects of climate upon the human constitution than most physicians imagine ; and I believe that the following reasons have hitherto tended to impede its investigation with that precision which it merits : 1st. The uncertainty and deterioration of all Hygrome- ters made of Hygroscopic substances, and their only indi- cating relative differences. 2nd. That all the Dew-point Hygrometers occupy more time than most people are able to bestow upon them ; and that some tact is required in their application. 3rd. That ether of sufficient strength cannot be obtained in every climate, and other chemical means of producing cold cannot be always at hand. 4th. That Sir J. Leslie's Hygrometer by evaporation is considered by many to offer erroneous results, being in- fluenced by radiation, currents of air, &c., and that much calculation is required before the absolute quantity of hu- midity can be ascertained. 5th. That the degrees of humidity indicated by the dif- ferent kinds of Hygrometers cannot be easily reduced to a common standard, so as to be compared with each other. Now, the instrument which I propose is at once free from 24 Dr. Masons Description all these objections, and is so simple and easily constructed, that by mere inspection the results can be ascertained with as little diflSculty as attends the common thermometer. The form of the instrument is portable ; it may be readily used in every climate and under all circumstances ; and its graduation depends upon no arbitrary or disputed determi- nations of wet and dry ; it is liable to no deterioration from use, age, or accidental circumstances ; it acts with an un- erring fluid ; and above all things, if the thermometers be carefully selected, so as to indicate the same degree under similar circumstances, it is impossible with moderate care to obtain erroneous results ; so that the comparative varia- tions of humidity, from the point of saturation, being exhi- bited in degrees of the thermometric scale, are at once re- ferred to a known standard of comparison which every person can understand and appreciate. The only trouble which attends the use of this instru- ment is the renewal of the silk on the moistened bulb once a month ; and the addition of a fresh supply of well boiled or distilled water from time to time as it may be necessary. Description of the Instrument. Upon the outer margin of a stand M is fixed an upright rod of brass/ supporting by a semi-circular clyp the scale J J, (the clyp is seen in shadow at o, and is f of an inch in dia- meter, thus removing the scale JJ \ of an inch from the brass support/.) In the middle of the scale J J a space is left to receive a glass tube A on the principle of the bird fountain, having on each side of it two thermometers hh oi equal range from 0° to 120° Fahrenheit, firmly attached to the scale already described. The bulbs c?Jof both ther- mometers are of equal size, and covered with white persian silk ; round the stem of one, a thread of floss silk e is at- tached, which terminates in the cup of the fountain c. This fountain is easily removed and re-fixed at pleasure by turning the screw h which allows the support g to move with ease in the groove i bringing the support g to the con- tracted part of the fountain. The upper part of the fountain is kept in its place by a double clyp kk. The fountain is hermetically sealed atp ; of a New Hygrometer. 25 the size of the orifice in the cup c which is oval, is f of an inch in length by ^ in breadth. When not in use, a box or brass case covers the whole in- strument, and screws on the stand M at tiw. The scale is made of ivory and ought to be as slight as possible.* The principle which Dr. Hutton proposed I considered the best : — 1st. As by it the temperature of the shade could be ascer- tained at the same time along with its hygrometric condition. 2nd. Because it would indicate the relative dryness of the atmosphere ; and, 3rdly. That the Dew-point could be easily ascertained from the data afforded by the instrument ; whence the abso- lute quantity of aqueous vapour could also be estimated. I was led to the construction of my instrument by the following observations in the Encyclopaedia Britannica, which I accidently saw in the winter of 1834, during my detention at Portsmouth, by the S. W. gales, when on my way to Madeira; *'a more scientific instrument has been constructed on the following principle, viz. : — that as eva- poration produces cold, the effect of that process on a ther- mometer will indicate the rate and amount of evaporation, and consequently the relative moisture of the air. The more dry the air is the greater will be the evaporation ; and the greater also the cold or the depression of the mercury in the thermometer." — "The general doctrine is that the dryness of the air, under all circumstances is precisely indi- cated by the depression of temperature produced on a humid surface which has been freely exposed to its action." Not possessing either Professor Daniell's, or Sir J. Leslie's Hygrometers, I was led by these remarks to the construction of the instrument now proposed, being desirous of making a minute series of observations during my residence in Madeira, for the purpose of determining the true character of its climate ; the ample details of which will be given in • The instrument is made in the above form by Mr. Gary, Optician, 181, Strand ; and by Mr. Squire, Operative Chemist, 277, Oxford Street, London, to pack in a neat travelling case, containing spare fountain, silk, &c., with appropriate tables for the use of the instrument ; also by Mr. William McDowall, Philosophical In- strument Maker, 13, Infirmary Street, Edinburgh. Much care is requisite in the construction of the Hygrometer to ensure accuracy ; the above named makers may be depended upon as aflFording accurate instruments. 26 Dr. Masons Deacrijjtion a volume on the Medical Topography, climate, physical structure, and past and present condition of that island, now preparing for the press by my friend, Mr. Blewitt, and myself; being convinced that medical practitioners do not yet possess that precise knowledge of the climate of Madeira which is necessary to enable them to decide on the particular classes of disease to which it is adapted : — I was also convinced that an instrument which would at any time indicate with facility and precision the actual state of the air in regard to humidity or dryness, would be a valuable acquisition to science. My first idea was that the instru- ment would only serve to indicate the relative humidity of the atmosphere, or its distance from the point of satura- tion ; but after considering all the laws of evaporation, and taking a general view of my own experiments on the sub- ject, I have been able to find the dew-point by very simple calculation, and also to trace out the relation between this instrument and Sir J. Leslie's. Considering that we ought ever to bear in mind, that nature is constant in her opera- tions, and that the same causes invariably produce the same effects, it hence became easy not only to obtain all the indi- cations that I required from the instrument itself, but also to ascertain by it the results given both by the dew-point Hygrometers and by that of Sir J. Leslie, with perfect accuracy and invariable certainty ; so that it may be truly regarded as supplying the place, if not of superseding alto- gether, the more complex instruments which have pre- ceded it. I shall subsequently enter more fully into the consideration of the important fact, that any errors which may arise in taking the temperature of the shade, will in my Hygrometer give an excess of moisture, while those of the dew-point Hygrometers will indicate an equal excess of dryness ; so that when both instruments are used, if very accurate data be required in ascertaining the absolute weight of vapour in a given quantity of atmospheric air, the mean of both instruments will insure the truth. I will here state all the objections which have been ad- vanced against the principle of Hygrometers by evaporation which Dr. Hutton first proposed, the chief of which have been grounded upon the belief that the air dissolved the vapour contained in it in a chemical manner, the same as of a New Hygrometer. 27 water dissolves a saline substance, consequently all the formulae for calculating the weight of vapour in a given space have been made on this supposition, whereas if the beautiful laws developed by the illustrious Dal ton be applied to this instrument, I think every objection can be fully and satisfactorily answered. Objections which have been advanced at various times against the Hygrometer by evaporation. 1st. That evaporation is considerably increased by cur- rents of air. Thus the instrument would be affected by the wind increasing the evaporation, and consequently depress- ing the temperature, which would indicate a fallacious dry- ness. 2nd. That evaporation takes place with greater rapidity in sun-shine than in shade, also indicating a fallacious dry- ness. 3rd. That the two thermometers are more or less influ- enced by reflected light and heat, &c. 4th. That evaporation is influenced by the density of the atmosphere ; it being greater or less according to the height of the mercury in the barometer. 5th. That it is almost impossible to take the heat of the air to any degree of nicety, without the observation being affected by the power of radiation ; and if a radiant caloric be allowed to interfere, the condition of calculation fails. 6th. That more time is required, than could be bestowed by an ordinary observer, in order to make a correct obser- vation, as time must be allowed for the water to acquire the same temperature as the atmosphere. \st. Objection. In answering the first objection it will be necessary to enumerate some of the laws of evaporation, which from being vaguely understood have always operated to the disadvantage of hygrometers by evaporation. I need not here enter into any minute analysis of the composition of the atmosphere, as it would be foreign to my present purpose. The two following laws will be sufficient to elucidate the question. The first established by Mr. Dalton, " that gases, dry atmosphere air included, act as vacua with regard to vapour, 28 Dr. Masons Description and that where they happen to be mixed together, they exist as independent atmospheres." The second, that the final tension of vapour given off in the process of evaporation is determined not by the temperature of the evaporating surface, but by the elasti- city of the aqueous atmosphere already existing ; which law I will endeavour to establish in my next paper. If we take the trouble to inquire how the error has arisen with regard to this objection, I am endeavouring to remove, we shall find that evaporation has been considered to be essentially promoted by the application or presence of heat, and the agitation of the aerial medium. Mr. Dalton when speaking of this subject observes, *' that air when calm and still, merely obstructs the pro- gress of evaporation ; but when in motion it increases its effect in direct proportion to its velocity by removing the va- pour as it forms." He has fixed the extremes that are likely to occur in ordinary circumstances at 120 and 189 grains per minute, from a vessel of six inches diameter, at a tem- perature of 212°, giving 79 grains increase per minute, for the effects of a strong wind. This law would be perfectly applicable in a dry air, but will by no means hold in one containing almost its full charge of humidity. The true law, I conceive to be this, that evaporation takes place from a humid surface in direct proportion to the tem- perature and velocity of the air, diminished by the force of the vapour already existing in the atmosphere; this I shall prove by direct experiment. The agitation of the air has hitherto been conceived to perform the principle part in reducing the temperature of an evaporating surface, but I hope to prove, that it is the dryness of the air on which we shall find the effect alone to depend. For example, if air be perfectly saturated with humidity, neither the increased temperature of the humid surface equally with that of the surrounding air, nor the strongest agitation of the medium can produce further evaporation or depression of temperature ; under those circumstances, both thermometers would indicate the same degree, and show that the air was absolutely saturated with humidity ; these conditions would continue until one of the two follow- of a New Hygrometer. 29 ing circumstances occurred : either the temperature of the medium must increase so as to render it capable of receiving a further supply of vapour, which would be at once shown by the depression of the mercury in the moistened bulb, or the air must be rendered less humid by a sudden depression of temperature, or increased density of the atmosphere, which would condense the vapour already existing in the medium, and cause precipitation in the form of rain or dew, when the temperature would be again raised to a certain degree by the heat given out from the water, passing from a state of vapour to its fluid condition, it would then admit of a further portion of vapour, and the mercury in the moistened bulb would descend as before. Under either of the above conditions, were the air in motion, the rapidity of evaporation and consequent depres- sion of temperature would be found exactly equal to the velocity of the current, diminished by the force of vapour already existing in the atmosphere. From the above remarks it will be seen that the ^^ celerity of evaporation has been mistaken for its intensity, and the coldness induced on the evaporating surface has been viewed as the accumulated effect of a rapid dissipation of moisture ; whereas the fact is simply, that the quantity of particles will be carried away in proportion to the velocity of the wind : consequently a humid surface will be much more rapidly dried ; but it does not follow as a consequence of the rapid dissipation of moisture that the temperature of the evaporating surface should be proportionally depressed, for in a free atmosphere, as Sir J. Leslie has proved, vaporiza- tion proceeds with unabated energy, while the correspond- ing depression of temperature must advance by a relaxing progression ; since otherwise, the accession of an accelerated movement might push it to any extent, but the reduced temperature caused by this process under given circum- stances has a certain limit beyond which it cannot pass."* The chief objection; therefore, against this instrument, advanced by Mr. Daniell himself, is perfectly without foun- dation, viz., " that the temperature of evaporation is no longer that constant quantity which it is supposed to be if dependant only upon the temperature of the air, and is * Leslie on Heat. 30 Dr, Masons Description liable io fluctuations with every change of place and every breath of wind." In the last place, I may add, in order to prevent any misconception of my views : 1st. that the moistened bulb will cool down to a certain point dependent upon the dryness of the atmosphere, and there its tempe- rature will remain stationary. 2nd. The rapidity of a current will hasten the term of equilibrium ; but the degree of cold induced will be found still the same. I will now endeavour to prove by direct experiment, the law which I wish to establish in answer to this first objec- tion, viz., that evaporation takes place from a humid sur- face in direct proportion to the temperature and velocity of the air, diminished by the force of vapour already exist- ing in the atmosphere; and that under given circumstances, the depression of temperature induced by evaporation must have a certain limit beyond which it cannot pass ; and that this depression of temperature, does not bear the same pro- portion to the rapidity with which a humid surface becomes perfectly dry. In order to prove, that, under given circumstances, the depression of temperature induced by evaporation has a certain limit beyond which it cannot pass ; I placed two hygrometers of similar construction upon a table in the middle of a large room ; they each indicated three degrees of dryness. The one I subjected to the strongest current I could pro- duce by a large pair of double bellows, which had previ- ously acquired the temperature of the apartment, and found by repeated trials that I could only reduce the temperature 0*5 of a degree below the other. The next thing to be proved was, whether this depression bore a proportionate progres- sive increase by equal increments of dryness. To establish this fact, I waited for an opportunity to repeat the experi- ment when the hygrometer indicated six degrees of dryness. The results of several trials were, that the temperature was depressed, just 1 degree beyond which it would not pass; at 9 degrees it was depressed 1*5; after repeated trials I found this invariably the case; being convinced of the facts, I made the following table from 0 to 26 degrees, the greatest depression of temperature I had ever witnessed in a strong Leste, during my residence in Madeira ; in of a New Hygrometer. 31 order to discover whether my inferences would be con- firmed by natural phenomena. Table showing the number of degrees which it is necessary to subtract from the depression of temperature, produced by a humid surface when exposed to a strong current of air, in order to reduce the number of degrees to what the hygrometer would indicate, under the same circumstances, provided the atmosphere was perfectly calm. Degrees of 1 >— ' dryness. 1 Excess of refrigera- tion pro- duced by a strong cur- rent of air. 0-166 ^1 P • 2> Excess of refrigera- tiojj pro- duced by a strong cur- rent of air. d is 15 Excess of refrigera- tion pro- duced by a strong cur- rent of air. ll ' o Ex«ess of refrigera- tion pro- duced by a strong cur- rent of air. 8 1-333 2-500 22 3-666 2 0-333 9 1-500 16 2-666 23 3-833 3 0-500 10 1-666 17 2-833 24 4-000 4 0 666 11 1-833 18 3-000 25 4-166 5 0-833 12 2-000 19 3-166 26 4-333 6 1-000 13 2-166 20 3-333 7 1-166 14 2-333 21 3-500 I shall have occasion to describe the character of the Leste or dry wind of Madeira in the work already referred to ; and shall there give a table, the data of which will prove that this progressive increase holds good in the maximum depression, I have seen the hygrometer indicate : for in- stance, at 9 A. M., the hygrometer indicated 20 degrees of dryness; the remarks are "quite calm, sky clear, without clouds;" at 11 a.m., the hygrometer indicated 24, the re- marks are " strong wind." Then on referring to the above table for the necessary corrections to be made for a strong wind, opposite the degree of dryness 24 will beseen4°-000, which subtract from 24° =20 the degree of dryness indi- cated two hours previously, when the atmosphere was calm. Having proved that the depression of temperature has a certain and constant limit, under given circumstances, be- yond which it will not pass, I may proceed to consider the second objection. Second objection. That evaporation takes place with greater rapidity in sun-shine than in shade. The difierence in the quantity of water converted into vapour in sun-shine and in shade, I have not yet been able to ascertain by experiment, 32 JDr, Masons Description but I have proved, which is sufficient for our purpose, that the relative difference indicated between the dry and moist- ened bulb of a thermometer is equal ; or in other words, that the refrigerating process is the same under given states of dryness or humidity : whether the thermometer is in the shade or exposed to the direct rays of the sun, pro- vided the instrument be suspended in free space at some distance from the ground. This I have sufficiently proved to be the case, and can with confidence assert that the relation between two hygrometers of the above construction is constantly equal in sunshine and in shade. I may instance two observations to elucidate the matter, one under the ordinary state of the atmosphere, the other during a Leste or dry wind. The hygrometer in the shade stood as follows : Temperature of the dry bulb 75°. Temperature of the moistened bulb 68°, 7° dryness. Hygrometer in the sun. Temperature of the dry bulb 83°. Temperature of the moistened bulb 76°, 7° dryness. The thermometer on the ground indicated 142°. During a strong Leste the hygrometer in the shade stood as follows : — Temperature of the dry bulb 86°. Temperature of moistened bulb QQI^ 20. Hygrometer in the sun. Temperature of the dry bulb 96°. Tempetature of the moistened bulb 72 and 96°— 72° =24° ■ — 4° correction for strong wind =20; themometer on the ground indicated 124°. Thus the influence of the sun affects each thermometer equally, and the temperature produced by evaporation is the same in both cases, being regulated by the elasticity of the aqueous vapour already existing in the atmosphere. Mr. Daniell makes the same remark on this subject with regard to his dew-point hygrometer. I find in looking over my observations on this subject, that the maximum point of variation in the moistened bulb for the same day at Madeira appears to be about 2°; frequently it remains stationary ; but hitherto,. I have not been able to trace the cause of this variation; I may, however, re- mark, that this is greatest at the commencement of the of a New Hygrometer,. 33 rainy season ; from which we might infer, that when the temperature of the dry bulb remains the same, the moistened one rising one or two degrees, rain may be expected, or the contrary. Supposing the moistened bulb sinks 2 de- grees more than ordinary, during the same day, it would in- dicate a continuance of fair weather. Third objection. That the two thermometers are more or less affected by reflected light. By covering the two bulbs with the same substance any relative difference will be prevented, as both bulbs will be equally affected by radiant and reflected light and heat. It appears from many experiments I have made on the subject, that radiant heat from the sun, does not influence the process of refrigeration, as the temperature of both bulbs rises equally from that cause. But in stating my opinion, that the hygrometer now pro- posed is not affected by radiant heat from the sun, I wish it to be distinctly understood, that this is only the case when the instrument is suspended in free space, at some distance from the ground, and apart from bodies giving off radiant caloric ; for when the hygrometer is subjected to the influ- ence of radiant caloric given off from heated bodies, its indi- cations are no more to be depended upon as furnishing ac- curate results than those afforded either by Sir John Leslie's or the dew-point hygrometers ; the indications afforded by my hygrometer being erroneous in proportion to its proxi- mity to the source of error. However, I can with confidence assert, that the instru- ment may be used under circumstances in which it would be impossible to obtain correct data, either with Sir John Leslie's or the dew-point hygrometers. All those instruments should unquestionably be used as much as possible in the shade, but from repeated and varied experiments, I am convinced, that the hygrometer now proposed, will be less affected by this source of error, than any other at present in the hands of the meteorologist. Fourth objection. That evaporation is influenced by the density of the atmosphere, being greater or less, according to the height of the mercury in the barometer, consequently, that corrections would be required to rectify this error. This objection I consider without foundation, being in- VOL. IV. D 34 Dr. Masons Description compatible with the theory of Dalton, namely, "that the quantity of vapour, contained in a given space, is indepen- dent of the presence or density of any other elastic fluid with which it forms no intimate combination ; or that the maximum quantity of vapour which can exist in a given space is the same, at the same temperature, as it would be, did that space contain nothing else." Nothing can be more obvious, than that steam in vacuo has no concern with ex- ternal pressure ; and it is as well known, that the maxi- mum force or density of steam in air has nothing to do with the density of that air, being the same as in vacuo. From Professor Daniell's experiments, the dew-point is not at all affected by the density or rarefaction of the air, consequently, the tension of the existing vapour is the same as in vacuo ; and the refrigeration of the moistened bulb, being entirely regulated by that tension, no barometrical correction will be required ; neither Mr. Dalton nor Pro- fessor Daniell have ever thought of making corrections for the dew-point. The careful experiments of Le Roy, Dalton, Gay Lussac, Daniell, and many others, have completely settled this point and placed it for ever beyond a doubt. I have also verified this by experiment, in finding the dew-point by my hygro- meter. Since, then, air acts only mechanically over the process of evaporation ; the only difference that atmospheric pres- sure can make, will be in the time required for the moist- ened bulb to cool down to its ultimate limits, evaporation taking place almost instantaneously in vacuo ; while it is impeded in proportion to the density of the air, the rapidity of evaporation, according to Leslie, being inversely propor- tional to the height of the barometer. As the limits to the process of refrigeration are always constant in the mois- tened bulb while in action, a correct observation may at any time be made by mere inspection. Fifth objection. That it is almost impossible to take the heat of the air to any degree of nicety without the observa- tion being affected by the power of radiation, and if radiant caloric be allowed to interfere, the conditions of calculation fail. This is perfectly true both with respect to this hygro- of a New Hygrometer. 35 meter and Professor Daniell's as far as accurate calculation is concerned, but as regards the degree of dryness on the ther- mometric scale, or distance from saturation, it is undoubtedly superior ; as in professor Daniell's instrument the two bulbs are not under similar circumstances, for in the latter hygro- meter the thermometer which indicates the temperature of the air must be in the shade, and guarded from all the sources of error to which it is liable, whereas, as I have proved with respect to mine, those sources of error are of less moment, precisely the same indications being given, providing radiant caloric from surrounding objects be not allowed to interfere. Sixth objection. That more time is required than could be bestowed by an ordinary observer in order to make a correct observation, as time must be allowed for the water to acquire the temperature of the atmosphere. This objection is fully obviated by the method I have adopted, namely, by keeping the ball constantly moist by means of capillary attraction ; and no more time is re- quired than would be necessary to make similar observa- tions on two ordinary thermometers . Having answered every objection, I will for the present stop here, and in my next paper state the view I take of the manner in which the temperature of the moistened bulb is reduced, and also the method to be adopted for ' the purpose of obtaining the dew-point ; the mode of comparing it with the hygrometer of Sir J. Leslie, and the various uses to which it may be applied, both in meteoro- logy and in different manufactures. I am, Sir, your obedient servant, John A. Mason. 18, Claremont Place, Pentonvitle, December 1st, 1835. {To be continued.) Article V. Catalogue of Plants collected at Bombay. By John Graham, Esq. We believe this to be- the first attempt at communicating any information with regard to the botanical productions of this beautifufpart of the western peninsula of Hindostan. d2 36 Mr, Grahams Catalogue of Plants The catalogue constitutes the gleanings of a few occasional minutes snatched by our excellent friend (with whom we have spent many a pleasant hour in botanizing amid the sylvan recesses of India) from the ingrossing avocations of his official duties. He has set an example which those who possess more spare time would do well to imitate. — Edit. 1 . Alpinia nutans, 2. Achyranthes aspera. A common weed. 3. Asclepias gigantea. Very coinmon thoughout India. The natives apply the milky acrid juice to sores. 4. Asclepias acida. This is a rare plant; I found it last August (1834) on the plains to the south of Aurungabad j also in the neighbourhood of Poona. 5. Asclepias annulare. 6. Asclepias ybr/wo55zmma. I have only seen this species in gardens, but, I believe, it is a native of India. 7. Asclepias odoratissima. This too I have only seen in gardens, and very rare. 8. Amaryllis Zeylonica. A very beautiful plant; I do not think it is to be found within this neighbourhood. 9. Asparagus falcatus. Large bushes of this shrubby species are common in the Deccan ; it requires support and is generally found overtopping some other shrub; it i& rather a pretty plant. 10. Aloe littoralis. The fibres of its long leaves are ex- tremely tough and might be used in making cord, if not cloth ; however, I am not aware of its being applied to any economical uses. 1 1 . Anacardium occidentale. Cashew nut ; common in Salsette and on the island of Bombay, &c. The apples are seldom used, indeed they are not worth eating. 12. Adenanthera^auoTiia.* 13. Adenanthera aculeata. 14. Averhoa bilimbi. 15. Averhoa ' carambola. Both species are common in gardens, and the fruit is used for making tarts. The fruit of bilimbi grows from the thick branches and often from the stem of the tree in a singular manner, like the jack fruit. * This elegant flower (termed the peacock fiower) forms a prominent part of the htfiquet with which the Musselmans present Europeans on Sundays. — Edit. Collected at Bombay, Ml The carambola is called kurmul by the natives, a word which signifies sour or sharp tasted. 16. Argemone Mexicana. A common weed, if not a na- tive, it is, at least, completely naturalized. 17. Alangium 6-petalum. Grows on Elephanta. 18. Anona squamosa. Custard apple, very common thoughout India. The fruit is used as an article of food by the natives in times of scarcity ; it is produced in great abundance with the slightest care ; the tree seems to grow indifferently on all soils and situations. 19. Anona reticulata. Bullock's heart, so named from the shape of the fruit, which is also eaten, though it is in- ferior to the custard apple. The flowers have a very sweet smell, something like the finest flavoured pears. This species is not nearly so common as the other. It is generally to be found planted near temples along with the other species. They call them ram vhool and ceta vhool, in honour of a heathen god and goddess ; vhool means flower.^ 20. Adansonia digitata. This tree appears to be natu- ralized. Several of them grow on Bombay Island, through- out the Concan and in Guzurat. I do not think any use is made of the fruit ; the tree assumes a very fantastic shape, the trunk very short and rapidly tapering ; it attains a great size.f 21. AbTM^ precatorius. A climber common in the hedges and jungles; when the pods open and display its red bead like fruit, it looks very pretty. The natives use the seeds for weights, and call them Gooneh, 22. Artemisia Indica. 23. Aristolochia Indica. This is a rare plant, with dingy looking flowers and leaves. I have found it on Malabar hill and Cross Island in the harbour. Humboldt tells us, the South Americans use the flowers of some of their gigantic species for hats. 24. Artocarpus incisa. Bread fruit tree. I only know one tree on the island, it grows well and produces fruit, of • The author states in a letter to me that "the properties of Indian plants are little known, and no dependence whatever can be placed on native names. In fact very few have any place in their nomenclature. They are Jungle ka vhool, i.e. wild flowers." — Edit. t There is a fine specimen of this tree in Caranja Island. See Records, vol. i., 335.— Edit. 38 Mr. Grahanis Catalogue of Plants some of which I have eaten. In times of scarcity it would be an invaluable tree, and as the soil and climate appear to suit it well, it is a pity that it has not been commonly planted. Its congener the jack fruit {A. integrifolia) is in common use among the natives, who call it Plumus, and the wood of the tree is more used then any other for making household furniture. The tree attains a large size in Ma- labar; I have seen a single fruit larger than the largest turnip at home. When growing on the stem of the tree it has something the appearance of a hedgehog stuck to it. 25. Amaranthus tricolor, tristis, oleraceus, varieties, I suspect ; bajee is the native name, red, green, and varie- gated. They are extensively cultivated and eaten like spin age. 26. Arum campanulatum. Native name soorun. The root somewhat resembles a pine apple, but it is globular. It is used by the natives instead of yams ; I have tasted it ; it is rather coarse. 27. Arum esculentum. Much cultivated by the natives who make use of the tubers in their curries, &c. 28. Arum polyphyllum. Very common, springing up on waste land during the rains. 29. Acalypha Indica. 30. Areca Catechu. A very graceful looking tree exten- sively cultivated for the nuts (betel) which are chewed by the natives. 31 . Andropogon schoenanthus. Sweet lemon grass, grown in flower pots. 32. A. Ischaemum. 33. A. Nardus. 34. Adiantum lunulatum. A fern covering old walls dur- ing the rains. 36. Avidcennia tomentosa. Very common in salt marshes. I have seen it as large as a middle sized tree ; it adorns the banks of creeks and rivers, growing in the water as well as out of it. 36. Ac2^i\i\i\is ilicifolius. Sea holly. Looks pretty when in flower (dark blue colour) ; grows common among the Avidcennia plants. 37. Artabotrys odoratissimus. I have only seen it in gardens ; it is a pretty scandent evergreen plant, with very Collected at Bombay. 39 ^weet smelling but insignificant looking flowers, as all the Annonaceae have. Decandolle calls it Unona uncinata. 38. Aegiceras mqjus or candel. Found common in salt marshes ; it has pretty dark green leaves with white flowers. 39. Argyreia cuneata Sprengel. A shrub with very beau- tiful blue bell looking flowers. When near any support it is scandent and sends out long slender branches. Roxbugh refers it to genus Lettsomia. I have only found it on a range of hills about 24 miles west of Poona near Wurgaum. It is grown as an ornamental shrub in the gardens at Poona, but I have never met with it here. 40. Agave America. I have only seen it in gardens at Seroor and Aurungabad. 41 . Agrostis linearis. A common grass. 42. Anthericum tuberosum. Springs up during the rains on rocky wasteland. 43. Boerhaavia diffusa. 44. Boerhaavia erecta. Found about 30 miles N. E. from Poona. Stems woody, as thick as a man's finger. 45. Basella alba and rubra. Varieties cultivated as root herbs ; the leaves are thick and succulent, and afford an excellent substitute for cabbage. 46. Bromelia ananas. Pine apple. 47. Bambusa arundinacea. Common and well known Bamboo. 48. BryophyWrnncalycinum. Growing in cocoa-nut groves; rather pretty when in flower ; grown in flower pots as an ornamental plant. 49. B.uhinia, speciosa. 1 60. B. ,, Candida. (^ Trees with pretty flowers 51. B. ,, variegata- \ particularly the variegata. 52. B. ,, parviflora' ) 53. Bergera -STowz^w. Cultivated for its leaves which the natives use in curries. The native doctors use the bark and roots as a stimulant. 54. B. integerrima. Found near Panwell on the main land. 55. Bassia longifolia. A common tree. The intoxicat- ing spirit called mowra is distilled from the flower. Oil is also expressed from the seeds. It is a very common and useful tree. The oil obtained from the seeds is extensively used for adulterating glue. 40 Dr. Thomsons Experiments on the heat or cold 66. Bignonia 4:-locularis. Common in the jungles, and somewhat resembling the ash. The white flowers rising from the ends of the branches look showy at a distance, but cannot bear inspection. 57. Bignonia spathacea, 58. Bignonia radicans. I have only found these two in gardens; both have pretty flowers, particularly the latter; it is a shrub of very slow growth, and was brought from China, I believe. (To he continued.) Article VI. Experiments on the heat or cold produced hy dissolving salts in water. By Thomas Thomson, M. D., F. R. S. L. & E., &c., Regius Professor of Chemistry in the University of Glasgow. 1. 300 grains of crystallized carbonate of soda in powder, were thrown into 1000 grains of water of the temperature 59° in a tumbler, and the mixture was stirred till the salt was dissolved ; the thermometer sunk to 43° or 16 degrees. The water of crystallization in 300 grains of carbonate of soda is 187| grains ; which is \ of 1300 grains, the whole of the liquid and salt included. Now, the water of crystalliza- tion becoming liquid would absorb 140° of heat. Hence the temperature ought to have sunk ^ of 140 or 20°. But the fall was only 16°; the difference is owing to the quan- tity of heat given out by the glass tumbler, which of course would prevent the temperature from sinking so low as it otherwise would have done. 300 grains of anhydrous carbonate of soda in powder, were thrown into 1000 grains of water of the temperature 57°*5, and stirred with a thermometer till the temperature ceased to rise. The thermometer rose from 57°* 5 to 79°'5 or 22°. In another experiment from 61° to 82°-5 or 2r-5. There remained undissolved 7*7 grains of salt. The water of crystallization seems to be absorbed by this salt in the first place ; hence the reason of the rise of temperature. This water amounts to 182 J grains or about \ of the salt and water. Hence, the rise of temperature should be ^ of 140 or 20°. It exceeds this quantity a very little ; the reason p'oduced hy dissolving Salts in Water. 41 of which may be, that the bulb of the thermometer being at the bottom of the vessel where the salt actually dissolved, probably the temperature in that spot might have been rather higher than at the surface of the liquid. The specific gravity of anhydrous carbonate of soda is 2-640. The specific gravity of a saturated solution of carbonate ofsodaat80°is 1-2291. It is composed of water .... 1 000 Anhydrous salt 292-3 1292-3 The mean specific gravity of such a mixture is 1*1647. But the specific gravity of the solution is 1-2291. It is, therefore, a good deal denser than the means. This will explain in part the reason why the temperature is greater than it ought to be from theory. 2. 300 grains of crystallized sulphate of soda in powder, were thrown into 1000 grains of water of the temperature 67°'5, and the liquid was stirred about with a thermometer till the whole salt was dissolved. A longer time elapsed be- fore the sulphate dissolved than was requisite for the solu- tion of the carbonate of soda. The thermometer sunk to 45°-5 or 12°. 300 grains of anhydrous sulphate of soda in fine powder, were thrown into 1000 grains of water of the temperature 61°-5, the mixture was stirred about with a thermometer. The temperature rose to 65°-5. or 4°. This temperature continued unaltered for nearly half an hour, showing that the salt was giving out heat during the whole of that time. The quantity of salt dissolved was 165*8 grains. The quantity remaining solid was therefore 134*2 grains. The specific gravity of anhydrous sulphate of soda is 2-640. The specific gravity of a saturated solution of sulphate of soda at 61°*5 is 1*1549. Now the mean specific gravity of a mixture of 1000 grains water of 61°-5 and 165-8 grains of anhydrous sulphate of soda is 1-0959. The solution, therefore, is a good deal denser than the mean. 3. 300 grains of crystallized sulphate of magnesia in powder were thrown into 1000 grains of water of the tern- 42 Mr. William Galbraith, on some perature 56°*5, and stirred with a thermometer ; the solu- tion was rapid but incomplete. The thermometer sunk from 56°-5 to 51° or 5°^. 4. 300 grains of crystallized proto-sulphate of iron in powder, were thrown into 1000 grains of water of the tem- perature 58°, and the mixture was stirred till the salt dis- solved. The thermometer sunk from 58° to 53°* 5 or 5° J . So that the cold evolved by the solution of sulphate of magnesia and proto-sulphate of iron is sensibly the same. The quantities of water of crystallization in 300 grains of each of these salts are as follows : grains. Carbonate of soda . . . 187*50 Sulphate of soda .... \QQ'QQ Sulphate of magnesia . . 153*65 Proto-sulphate of iron . . 135*96 Now, the ratios of these numbers to each other are very nearly as the numbers 37 J, 33^, 30f , 21 1. While the cold produced by the solution of each salt was 16°, 12°, 5°^, 5°i. We see that these two ratios are not the same or even ana- logous to each other. It is obvious from this that the mere knowledge of the water of crystallization, and the solubi- lity of a salt, is not sufficient to enable us to foretell the degree of cold that will be induced by its solution in water. A great deal depends upon the rapidity of the solution. Hence, it happens that more cold is produced by dissolving salts in dilute acids ; because by this method the rapidity of the solution is very much increased. Article VII. On some Astronomical Methods of Observation. By William Galbraith, a. M., Teacher of Mathematics^ Edinburgh. I. ON THE OBLIQUITY OF THE ECLIPTIC. To trace the various methods of astronomical observation used by the ancients, would be a task too laborious and irk- some for our present purpose. It would not, however, be uninteresting to notice a few of their processes and instru- ments which they most generally employed. Among the latter the gnomon constructed in various ways appeared to be that in which most confidence was placed. Astronomical Methods of Observation. 43 The rudest example of the gnomon was an upright pole, placed perpendicularly to the horizontal plane by means of a plumb line, though there are instances of some of them constructed of masonry of considerable heights, but these could not properly be called instruments. The altitudes of the heavenly bodies were from these calculated by com- paring the length of their shadows with their heights. In modern mathematical language, the height of the gnomon divided by the length of its shadow, gives the natural tan- gent of the altitude of the celestial body, such as the sun, whence by means of a table of natural tangents the angular measure of that altitude becomes known in some conven- tional measure, such as degrees. Thus let the height of the gnomon be 5 feet, and the length of its shadow 10 feet, then -^Q or 0*5 being found in a table of natural tangents will give the angle equal to about 26° 30', the altitude of the sun at that time. This method was found to be inconvenient, because the length of the shadow was required to be measured each time an observation v/as made. It, therefore, occurred to the ancient astronomers to form an instrument of moderate dimensions on similar principles, like the artizan's square, having the horizontal side divided into equal parts as it was at first, and afterwards into the natural tangents called by the Arabians shadows, to the radius, and by this means the angle of elevation became known in degrees and parts of a degree by inspection, though not to any great ac- curacy. This gave place in its turn to the quadrant, divided into degrees and parts of a degree by means of a radius turning round its centre, in which were placed fine pins or sight vanes. It was with such instruments as these that Eratos- thenes and Ptolemy attempted the measurement of the figure and magnitude of the earth, and the determination of the obliquity of the ecliptic. Ptolemy states that the dis- tance between the tropics in his time was found by such an instrument to be ^ of the whole circumference, that is ^ of 360°=47° 42' 40", and the half of this or 23° 51' 20' con- stitutes what is called the obliquity of the ecliptic. The accuracy of observations made with the quadrant could not be great till the invention of the telescope and the vernier or reading microscope. The quadrant though 44 Mr. William Galbraith, on some a good instrument with these appendages, and was long so used, has, at last, given place almost universally to the circle which by means of verniers reading round the whole circumference destroy by mechanical means, probably, the small incidental errors inseparable from materials and workmanship however excellent both maybe. "With all the care that could be employed, errors to the amount of 20" or 30" were known to exist in the observations of some of the continental observatories, and even to the amount of from 5" to 10" in those of Greenwich." Indeed, Trough ton has been heard to affirm that a well divided circle of a sin- gle foot in diameter is more to be depended upon than a fixed quadrant of the largest construction. In a series of four observations made with the six inch circles of Kater as constructed by Robinson, I have never found, under favourable circumstances, the errors to exceed ten or fifteen seconds. Now, in the preface to the first volume of the Greenwich observations, published by Maskelyne in 1776, he makes the following remarks : " The sun and moon and some of the principal fixed stars are constantly observed on the meridian every day when the weather will permit ; and the exactness of the instruments is so great, and their recti- fications so nice, that the place of any heavenly body may always be found by them within ten seconds of a degree both in longitude and latitude, and generally much nearer." He then possessed a great mural quadrant of eight feet radius, by Bird, and we, therefore, see that our small cir- cles of a few inches in diameter are nearly as accurate as the old quadrants of as many feet, and they approach much nearer to perfection than we had any reason to anticipate. Such small portable circles are consequently very valuable to the amateur astronomer, as well as the scientific traveller, since in the hands of a skilful observer, they furnish results highly useful for the improvement of geography, astro- nomy, and navigation, while at the same time their mode- rate price enables many to become purchasers. In a letter from Captain Kater of the 25th of February, 1831, he remarks: *'the size I recommend, and which I use is only 3 inches in diameter, and in the latest con- struction has only a vertical circle which can, however, be placed in the plane of any two objects so as to take the angle between them, the whole contained in a box 7 inches Astronmnical Methods of Observation. 45 long, 4-^ inches wide, and 3 deep, so that it really deserves the name I originally gave, that of a pocket azimuth and alti- tude circle. With this little circle I can get, in one even- ing, my latitude to within 5" of the truth by the pole star." Such are literally the expressions of the late Captain Kater, the inventor of this instrument, and the advantages of it to scientific travellers are very obvious. , {To be continued.) Article VIII. On a difficulty in Isomorphism, and in the received constitution of the Oxygen Salts ; in a Letter to Professor Mitscherlich, of Berlin, from Thomas Clark, M. D., Professor of Chemistry in Marischal College, Aberdeen. {Concluded from vol. iii. page 443.) II. — Adopting the alternative of retaining the received views of the constitution of the Oxymanganate of Barytes, aud assimilating thereto our views of the constitution of the Sulphate of Soda, consistency compels us to adopt the following formulas : — Sulphate of Barytes, . . . Ba S Manganate of Barytes . . . Ba Mn Oxymanganate of Barytes, Ba Mn Mn Sulphate of Soda, . . . . So S S Manganate of Soda, . . . . So Mn Mn Oxymanganate of Soda, . . . So Mn Mn^ In this list, the alterations on the formulas are limited to the salts of Soda. Those alterations have given rise to the following difficulties : — 1 . The basis of all the oxygen-salts of soda is assumed to be an unknown oxide of sodium, retaining half as much oxygen as is in soda. 2. The sulphate of soda is assumed to contain, not sul- phuric acid, but another undiscovered acid having in com- bination additional oxygen, and by a like assumption, man- 46 Dr, Clark to Professor Mitscherlich gauate of soda contains, not manganic acid, but the oxy- manganic. 3. The oxymanganate of* soda is assumed to contain, not oxymanganic acid, but another acid, composed of manga- nese 4 atoms, and oxygen 15 atoms. Here, again, it may be supposed that material difficulties may be avoided by retaining, without alteration, the first formula for the oxymanganate of soda : — So (Mn Sln)2 But this would involve us in the new inconsistency of as- suming the soda-manganate to have, as a constituent, the same acid as the oxymanganate either of soda or of barytes, while we admit that the barytic-manganate is constituted by a different acid. I do not know whether you, or other chemists, may see any way of reconciling with the constitution commonly as- signed to the oxygen-salts, the notion that sulphate of soda and oxymanganate of barytes are analogous in constitution. I profess I can see none. The difficulties already pointed out, as consequences of admitting that analogy, have oc- curred while our attention was limited to those two, and four or live other salts ; but how would such difficulties be mul- tiplied and aggravated, were we resolutely to trace the con- sequences of that admission, throughout all the wide and varied field of chemical combination 1 Wherefore, all idea of analogy of constitution between the two salts in ques- tion, I would renounce as chimerical, did I not believe that such analogy is quite reconcilable with the constitution of oxygen-salts and oxygen-acids, according to the other and better view. I say better view, and I will give reasons ; but, wishing to be brief, I will confine my observations to what may be called internal evidence, arising from a consideration of the constitution of the oxygen-salts, according to both views, as modified by the known results of analysis. A being employed to represent an atom of any metal that may be conceived to be in the basis of any oxygen-salt, the following formulas will exemplify the constitution of sul- phates, assumed to contain bases oxidized in different de- grees, according to the view commonly taken of such salts : — On a difficulty in Isomorphism. 47 Instances, I Si Protosulphateoftin; of iron; of manganese. ^ \ Persulphate of mercury — of copper. II. A A S Protosulphate of mercury — of copper. III. A §2 Persulphate of tin. . C Persulphate of iron — corresponding sul- IV. A A S3< phate of manganese — sulphate of alumina (, — of chrome. These four descriptions of sulphates contain each one atom of oxide. The first and second contain each one atom of acid ; but, what demands most attention, the third con- tains two atoms of acid, and the fourth, three atoms of acid. But, admitting that each of these four descriptions of sul- phates contains one atom of oxide, and that the first and second contain each one atom of acid, analogy would lead us to expect that the third and fourth sorts would also contain one atom of acid in each. Sulphurous acid, on being farther oxidized, so as to become sulphuric acid, does not, in con- sequence of having acquired more oxygen, combine with more potash, in order to form a neutral salt, and, indeed, hypo-sulphuric acid, which is undoubtedly more oxidized than the sulphurous, combines, for the same sulphur, with only half as much potash. Chemists, guided, as they may conceive, only by the result of analysis, may, it is true, choose to regard, as a rule of combination, that any oxide, the basis of a salt, requires, for neutralliza- tion, as many atoms of acid, as itself contains of atoms of oxygen. But we are too apt to regard, as the result of analysis what is merely our own arbitrary expression of that result. The objection to our admitting, as a law of nature, that oxides combine with acids according to such a rule, lies in this : that not only does such a rule imply that oxides, in their combinations, observe a law different from what bodies not oxides observe, but it im- plies that one class of oxides observe a rule of combina- tion, different from another class of oxides. This will at once appear on considering the following Table, where A and X stand for any two oxidizable metals, and where the combination of the oxides of each metal is represented as taking place, reciprocally in the same number of atoms of each oxide as the other combining oxide contains of atoms 48 Dr, Clark to Professor Mitscherlichy of Oxygen. The table gives first the compound of the two protoxides (a x). X X XX X A aX A^X A^xx A^X A aX2 aX aKXX)2 A3X2 A A aXx^ (aa)2X3 Alxx A aX A little study of the structure of this table, and considera- tion of its contents, will evince, that, consistently with the rule according to which it is framed, any two oxides, in com- bining together so as to form neutral compounds — which may be supposed the simplest sort of combination that can take place between two oxides — ought to combine in such proportions only that each oxide would contain an equal quantity of Oxygen, How remote this is from the fact, it were superfluous to say. Impossible, therefore, to be gene- ral in its application, the supposed rule can only be regard- ed as partial. But partiality is unlike a law of Nature, and indeed the partiality disappears whenever we regard the Oxygen-salts as having metals, and not oxides, for their bases. The general formulas of the neutral Sulphates are then tranformed, as follows : — A S =A S AAS =A2S A"S2=A I§2 AAS3=A2S3 * When taking this altered view of the Sulphates, a strik- ing fact is is brought into light. So much of the Oxygen as the common view regards as belonging to a , always, in neutral salts, occurs exactly in the supplementary propor- tion necessary to make up the acid-radical, S. Hence, ac- On a Difficulty in Isomorphism. 49 cording to the new view, the anomaly of one class of oxides combining according to a rule different from other oxides, and from other bodies, disappears ; for, according to this view, when Oil of Vitriol, regarded as an Hydrogen acid (H2 S), acts on an oxide, it is not a simple combination that takes place, but a double decomposition, resulting in a neutral salt and water, precisely as takes place when Hydro-chloric acid acts on oxides. While, therefore, on regarding Oxygen salts as having metals for their bases instead of oxides, the anomalous aspect of such of them as are formed from oxides of high degrees of oxidation disap- pears, we do not need, in taking this view, to seek any new supposition to stand upon. Nor can it escape your obser- vation, that, regarded in this view, all the oxygen is in a state of unity ; whereas the former view presented it broken asunder, like a sphere, into two irregular parts, which, when examined apart, seemed neither of them symmetrical, but which, being joined again, conceal all that before ap- peared irregular, attesting at once the violence that had rent them asunder and the unity of the artist's design. Such unity of all the oxygen in any neutral salt, is re- markably confirmed by the action of the two Sulphates of Mercury on common Salt, in producing by sublimation, Corrosive Sublimate and Calomel. The following diagrams indicate the actions — Materials. Common salt, . . . f2Cl . Na C\H Products. -, HgCl^Corro- / sive sublimate Persulphate of mercury. „ r HgA A NaS Sulphate of Soda. r2Cl ^2HgCl Calo- Common salt, . . . . Na C\-\ / mel. L Na\ v. r2Hg' Proto-sulphate of mercury, Hg^S •< ^ \ I ^ • NaS Sulphate of Soda. VOL. IV. 50 Dr, Clark to Professor Mitscherlich, These undeniable actions appear to me to demand evi- dence, such as neveryet has been adduced, in proof of the usual explanation that, in undergoing mutual decomposi- tion by another neutral salt, every neutral Sulphate divides its own Oxygen so as to leave, with the metal it contained, one-fourth, while transferring, to the new Sulphate pro- duced, the remaining three fourths. To avoid becoming unseasonably tedious by insisting on such details, I shall draw them to a close, trusting that enough has been stated to establish, that no Chemist is obliged to reject any view, otherwise well founded, merely because that view is inconsistent with the doctrine of Oxy- gen salts having oxides for their bases, provided he per- ceive that the view in question is not inconsistent with the doctrine of Oxygen salts having metals for their bases. Accordingly, I proceed to show that the suggested analogy of Oxymanganate of Barytes and the waterless Sulphate of Soda, although inconsistent with the former doctrine, is quite consistent with the latter. Regarded as Hydrogen acids, the acids of the Salts we have been more particularly considering would be Oil of Vitriol, H«§ Manganic acid, H^Mn Oxymanganic acid, H Mn I am not sure that Chemists have taken much notice of the varying proportions of Hydrogen in its acids, so far as that element re-places the metallic bases of neutral salts. But, of the following four Hydrogen acids, the Hydrogen varies, without any doubt, in the first and second, and, with much probability, in the third and fourth — I. Hydrochloric Acid, H CI II. Sulphuretted Hydrogen, . . . H^ S III. Hydro-ferricocyanic Acid,'* . . H^ (Fe Cy^) IV. Hydro-ferrosocyanic Acid,t . . H'*(FeCy6) Sulphuretted Hydrogen, you will observe, has here, in re- spect of Hydrogen, the same relation to Hydrochloric acid • Acid that fonns With Potash the red Prussiate. t Acid that forms with Potash the yellow Prussiate. On a Difficulty in Isomorphism. 51 that I have supposed^Oil of Vitriol to have to Oxymanganic acid, assuming both of these to be Hydrogen acids. Regarded as having metals for their bases, the salts themselves would be constituted, as follows — Sulphate of Barytes, Ba S Manganate of Barytes, Ba Mn Oxymanganate of Barytes, . . . Ba Mn^ Sulphate of Soda So S^ Manganate of Soda, ...*.. So Mn^ Oxymanganate of Soda, .... So Mn* Remembering the relation of the acids, as just now ex- plained— remembering that in the salts, constituted as this table sets forth. Barium has to Sodium the same relation as Tin, in its proto-compounds, has to Tin, in its per-com- pounds — I cannot, in the view here presented, perceive any difficulty requiring elucidation, nor any obstacle to forbid our admitting, as analogous in constitution, the salts that have called for all this consideration, in consequence of their being alike in form. These, represented as analogous, are as follows — Oxymanganate of Barytes, . . . Ba Mn^ Waterless Sulphate of Soda, . . . So S^ ^ Waterless Seleniate of Soda, . . So Se^ Sulphate of Silver, Sv §2 Seleniate of Silver, Sv Se^ (Silver, in all that went before, being represented by Ag, at the usual atomic weight, but here by Sv, at double that weight.) Throughout the foregoing observations, I desire to be understood, as regarding the suggested analogy of oxyman- ganate of barytes and the other salts in question, not as a main proof, nor indeed as one of the proofs, of the doc- trine of oxygen-salts having metals for their bases, but only as a refutation of the rival doctrine, that such salts have oxides for their bases. E 2 52 Dr. Clark to Professor Mitscherlich, Thus, in its consequences, threatening to shake what che- mists have been accustomed to consider as most fixed, the dif- ficulty in isomorphism that I have pressed upon your atten- tion, is not, like some former difficulties, one of mere detail, rectified, perhaps, by adverting to the w^ater of crystalliza- tion, and, when rectified, leaving unaffected all the other details, and all former views of chemistry. Here, on the contrary, is a difficulty concerning a point, upon which, when granted, the world of chemical doctrine may be moved. Proportional to the importance of such a point at issue, will be the caution of chemists in scrutinizing the stability of the evidence. On a single point, indeed, however well established, few men will be disposed to rest all the conse- quences that the one at issue may be destined to bear. Even Archimedes, it may be suspected, had he, in answer to the enthusiasm of his wish, obtained that one stable point he desired, would, in the moment for action, have sighed for another. Content, therefore, with depicting to chemists the consequences of this difficulty, I leave the issue to be determined, as it can only be, by some future instance, equally unequivocal, of coincident form and constitution in compounds of sodium or silver, compared with compounds of barium, or strontium, or lead, or calcium, and, perhaps, I might add other metals. Such coincidence, in respect of constitution, will accord, it may be supposed, either with the received atoms of sodium and silver, or with those atoms doubled. That the coincidence shall prove according to the received atoms of those metals, is rendered little pro- bable by the fact, that, according to that standard, many coincidences in constitution are already known, without any coincidence in form having been yet observed ; whilst, according to those atoms doubled, scare any crystalline compounds of entirely coincident constitution are as yet known.* If observation, which must be the final arbiter, * Supposing that the present atomic weiglit of sodium should be doubled, the following formulas would represent, according to the received constitution of oxygen-salts, and to the "present atomic weights, some salts of soda and of barytes that might prove of coincident form : — NaA Ba A A Na A Ba A A Na A Ba A A On a Difficulty in Isomorphism. 53 shall determine one coincidence more to accord with the doubled atoms of sodium and silver ; then, for aught I can see, the doctrine of oxygen-salts having oxides for their bases must at once be abandoned ; but, if observation shall determine any coincidence to accord with the received atoms of sodium and silver ; then, if we admit coincidence in form, we must also admit discrepancy of constitution, for though barium substitute these metals in compounds, without affect- ' ing the form, it must be in the proportion, hoth of atom for atom, and of one atom for two atoms; then, too, must we seek for an explanation of all known coincidences, however striking in form and in constitution, in the emptiness of some such phrase as *' a random-concurrence in the chance- disposition of atoms;" and, then, must all the specious fabric of isomorphism, stable though it seems, vanish like a dream. Sir, I am. Yours, with sincere esteem, Thomas Clark. Marischal College, Aberdeen, April 1, 1836. Article IX. Examination of the water of the North Well at Scarborough, By Robert D. Thomson, M. D. I am riot aware that any recent analysis of this water has been published. A book was written on the subject, about the beginning of last century ; but it is scarcely necessary to say, that, the results given in that work are completely at variance with those which I obtained. In the specimen which I examined, the water was trans- parent and colourless ; a few brownish red flocks were, how- ever, deposited at the bottom of the bottle in which the water was contained. Its specific gravity was 1-003354. The presence of sulphuric and muriatic acids and of lime was indicated by muriate of barytes, nitrate of silver, and oxalate of ammonia ; litmus paper was not acted on. 1. 1000 grains of the water were placed in a phial which was laid in an inclined position on the sand bath until the liquid was evaporated to dryness. The residue weighed 64 The Art of Dyeing. 3*37 grains. Again 500 grains were treated in the same manner ; the remainder amounted to 1*68. Now 1*68 x 2= 3*37, precisely the same result as in the first trial. 2. 1000 grains of the water afforded by means of nitrate of silver '418 grains chlorine. 3. A similar quantity yielded 2.07 grains sulphate of barytes= '4028 grains sulphuric acid. 4. To a third portion oxalate of ammonia was added, by which means the lime was precipitated. It amounted to •964 grains carbonate of lime, or -269 grains oxide. 6 To obtain the magnesia and soda 1000 grains were weighed out. The lime was precipitated by oxalate of am- monia. The liquid separated from the precipitate was placed in a platinum capsule and reduced to dryness. A few drops of sulphuric acid were added to convert the magnesia and soda into soluble sulphates, which were evaporated to dryness, and heated carefully to redness in order to drive off the excess of acid. The weight amounted to 1-3 grains. This residuum was then dissolved in water, the magnesia precipitated by boiling with carbonate of soda. This car- bonate when heated gave '5028 magnesia. The soda, there- fore, amounted to 0*0100 grains. The iron being held in solution by carbonic acid was all precipitated before the water reached me, so that I was unable to estimate its quantity. The proportion, however, precipitated was not considerable. According to this analysis the solid contents in the im- perial gallon are, Sulphate of magnesia . . 105*94 Sulphate of lime . . . . 47*64 Chloride of calcium . . . 38*00 Common salt 7*23 198*81 Article X. The Art of Dyeing. {Continued from vol. iii. page 455.) YELLOW FROM QUERCITRON AND ALUM MORDANT. To obtain a light quercitron-yellow, the calico is mordanted in the manner described under berry-yellow. The same Yellow from Quercitron and Alum Mordant. 65 method is also to be adopted in procuring a dark yellow. The mordanted cloth is then cleared by immersing it in running water. The boiled powder is very rich in dye-stufF. To obtain the dark yellow, for 14 lbs. of mordanted cloth it is only necessary to employ 3 lbs. of quercitron powder, while, for 14 lbs. of cloth 7 lbs. of the fibrous matter which remains after boiling are required. The powder also gives a clearer yellow. Dyeing. — On account of the sharp nature of the fibre of the quercitron which sticks to the cloth, and is not easily separated, it is necessary, when one is about to dye with the fibrous part, to place it in a linen bag, and boil it several times with water. This decoction should then be mixed with water, and heated to 65^f . The cloth well moistened and mordanted should then be dyed at a temperature be- tween 110^1 and 122°. When the solution is formed from 15 lbs. quercitron bark and 1 lb. lime the yellow is formed very pure. The addition of bran answers still better, as it does not precipitate the colouring matter. The best pro- portion is 2 lbs. quercitron bark to 3 lbs. bran. If the boiled powder is employed, 2 lbs. quercitron powder are used with 6 lbs. bran. Clearing is not required in this colour. Properties of quercitron-yellow . — This colour is not very permanent when exposed to the air and light, but it is more permanent than many other yellow colours. Boiling soap-suds consisting of 1 lb. soap in 200 lbs. water is coloured yellow without deteriorating the colour. Solution of potash makes brownish spots which vinegar makes white. Ammonia, lime water, and vinegar produce no change on the colour. Lime juice changes the colour into sulphur-yellow ; am- monia destroys the colour again, and restores the original one. Tin mordant. No. 1, printed in a strong solution changes the colour into sulphur-yellow. Solution of chloride of lime only renders the colour brownish. If a piece of dyed calico be placed in the solu- tion for a quarter of an hour, a dark brown colour is pro- duced passing into nankeen ; so that in this space of time it does not become white. 56 The Art of Dyeing. YELLOW FROM YELLOW WOOD AND ALUM MORDANT, This yellow colour is very fleeting. Its want of per- manence can be well exhibited by dyeing a piece of calico with Persian berries and another with yellow wood. The former retains its deep colour, while the latter fades to a straw tint. VIOLET FROM ALKANET AND ALUM MORDANT. Bright alkanet violet is produced with the alum mor- dant, No. 3. Dark violet with No. 1. The mordanted cloth is cleared by immersing it in run- ning water, and then in warm water. Dyeing. — Alkanet-root has its dye-stuff, only in the bark ; therefore, much is required for a dark colour ; as 4 lbs. mordanted cloth to 10 lbs. alkanet root. The colouring matter dissolves in water only by means of spirit of wine. But it is important to use as little spirit as possible. The 10 lbs. of alkanet are therefore placed in 5 different vessels (1, 2, 3, 4, 5.) So much spirit (of 80°) is poured on the first as covers it. After 12 hours the red solution which has been formed should be poured off, and re-placed by fresh spirit. The latter should be decanted after 12 hours, and poured upon the roots in the vessel. No. 2. After 12 hours it will also be saturated with colouring matter. It should be decanted and mixed with the first red solution, and em- ployed for dyeing. Fresh spirit should then be poured on No. 2, and this is again poured on No. 3, and thus in suc- cession until the roots are deprived of colouring matter. The solution of colouring matter in spirit described, should then be diluted with water, well mixed, and the mordanted cloth dyed in this. The water must be com- pletely free from lime and gypsum, otherwise a great loss of colouring matter will be sustained by precipitation. The heat should be pushed very slowly to boiling, otherwise the spirit, which contains the colouring matter in solution, would be too rapidly volatilized. Boiling soap-suds give the colour a lilac shade. Properties of alkanet violet. — These are very remarkable. It is not altered by lime water, ammonia, vinegar, lime juice, tin mordants, nor by chloride of lime ; and the blue spot produced by potash will even after 24 hours be removed Iron Mordants. 67 by vinegar. Air and soap-suds produce scarcely any effect. Boiling in solution of 300 lbs. water and 2 lbs. soap does not deteriorate the colour ; the shades become bluer and clearer than before. VIOLET BLUE FROM LOGWOOD AND ALUM MORDANT. For bright colours, the alum mordant, No. 3, is used, or the alum solution mixed with soda in the manner described. The dark violet blue should be produced with alum mor- dant. No. 2. It is necessary to allow the mordanted cloth to hang up some days before the dyeing takes place. The mordanted cloth is cleared in running water. In order that the colour may not pass into black, bran should be added to the solution. The bran is first boiled with logwood and a little water ; then more water is added, and the heat increased and raised to boiling. For 10 lbs. of mordanted cloth, 2 lbs. logwood and 2 lbs. bran are required to produce a dark logwood blue. Hot soap-suds heightens the colour, and makes it more perma- nent to acids. Properties. — Towards light, air and soap-suds, logwood blue shews much permanence. Potash makes brown spots which are removed by vinegar. Ammonia does not change the dye, but dissolves a por- tion, and makes it paler. Lime water effects no alteration. Lime juice makes bright red spots which ammonia com- pletely dissolves. Tin mordant i No. 1, printed upon it forms a lilac. Tin mordant, No. 2, printed on it discharges a clear violet. Chloride of lime discharges a yellow like nankeen. IRON MORDANTS. Next to the alum mordants, iron mordants are of most importance to the dyer. Their affinity for the cotton fibre is, if possible, stronger than that of the alum mordants. The iron mordants bear the same relation to dark colours that the alum mordants do to light ones. For this purpose, sulphuric and acetic acid mordants are employed. 58 The Art of Dyeing, IRON ALUM. Iron alum contains no alum, but derives this name from its crystalline form which resembles that of alum, and in consequence of the similarity of its chemical constitution with alum. When the alumina is taken out of the alum, and oxide of iron substituted for it, we obtain iron alum. It may be formed by mixing 78 lbs of red oxide of iron, 117 lbs sulphuric acid combined with it, both dissolved in water, and 87 lbs sulphate of potash added while boiling, and then allowing the iron alum to crystallize. Iron alum, made on a large scale, has*a clear amethyst colour ; subsequently it becomes covered with a yellowish white crust which does not injure it. It is very soluble in water. The solution is yellow coloured and undergoes de- composition by boiling, while oxide of iron separates. The solution of iron alum is employed by itself for the production of a great many colourless grounds, variously shaded according to the strength of the solution. This so- lution acts differently from the alum ; for the stronger the solution, the more iron alum the calico takes up. A weak solution of 1 lb iron alum in 60 water with quercitron, gives a pale straw colour, while with 10 lbs iron alum and 60 water, the colour produced is comparatively very dark. In order to obtain such shades of an equable nature, it is necessary to impregnate the calico with the mordant, press it and rinse it as described. Unless very carefully dried, more of the mordant collects on the edges and faults of the calico than on other places, and produces inequalities. This is prevented by rinsing it before drying. Solutions of iron alum may be kept for a long time without losing their properties. The air does not produce any in- jurious eflfect, as occurs with the solution of sulphate of iron. Acetate of iron. — When vinegar or pyroligneous acid is poured upon heated iron, and left in contact with it for a month, a mordant of acetate of iron is formed, which when thickened with gum or starch is very useful for printing ; for mordanting colourless grounds it does not answer so well. This mordant is most readily produced by decomposing iron alum with sugar of lead. The two following formula? are in most general use. Iron Mordant. 59 Iron mordant^ No. 1 .—Dissolve 20 lbs iron alum in 80 lbs of warm water, add 20 lbs sugar of lead, and agitate the mixture until all the sugar of lead is completely dissolved. This mordant when thickened with starch is employed es- pecially for dark rust yellow ; in block printing it gives also with prussiate of potash a clear dark chemical blue. After some days this mordant becomes turbid, and oxide of iron precipitates. It is, therefore, proper not to prepare more than can be used in the course of 1 or 2 days. As the mordant clears quickly, there is no difficulty in forming it on the instant by keeping prepared solutions of 20 lbs iron alum in 40 lbs water, and of 20 lbs sugar of lead in 40 lbs water. These can be added to each other when the mordant is required. When vinegar is added instead of the water, no change takes place and no oxide of iron is precipitated. Such a mordant answers very well in place of nitrate of iron as an addition in block printing. Iron mordant No. 2. — Dissolve 10 lbs of iron alum in 80 lbs of warm water, add 10 lbs sugar of lead, and agitate until all the sugar of lead is completely dissolved. This mordant is employed for dark colourless grounds; the cloth should be dyed in the manner before discribed, and dried as quickly as possible. This mordant is also subr ject to the same changes as the iron mordant No. 1. It may be preserved by the same means, viz., vinegar adding only half the quantity of water. Calico takes up from a solution of oxide of iron and acetic acid mo^e iron than from a sulphuric acid solution, when also the proportion of oxide of iron is equal in both. If two solutions are made of 1 lb iron alum in 20 lbs water, and to one of them 1 lb sugar of lead is added, and both be employed as mordants, while two equal pieces of calico are placed in contact with them for \ of an hour, then rinsed and dyed in tannin colours are obtained of different shades. From which it is obvious that the oxide of iron can be taken up in greater proportion from the acetic acid ; solution formed by the addition of sugar of lead, than from the sulphuric acid solution ; it also appears that the acetic acid iron mordant is much more rapidly exhausted of its proportion of iron, and therefore, must always be employed in a weaker state for this purpose. It is, therefore, neces- 60 The Art of Dyeing, s2LTy when it is required to give a number of pieces of calico an equal mordanting, to add after each impregnation with the mordant a definite quantity of fresh mordant, or for the sake of great accuracy, to divide the mordant into as many portions as there are pieces of calico to be mordanted and impregnate each by itself therein. The remainder should be again collected and rinsed together. BROWN FROM QUERCITRON AND IRON MORDANT. Light quercitron brown is formed with the solution of iron alum. No. 1. Dark quercitron is produced with the acetate of iron mordant. No. 2. The mordanted cloth is purified by passing it through a cow-dung bath. To pro- duce the dark quercitron brown, 3 lbs. of quercitron powder are employed for 12 lbs of mordanted cloth. For the purpose of dyeing it, the decoction of quercitron bark is employed, being made lukewarm by the addition of cold water. The dyeing is prolonged by gradually raising the temperature to boiling. The addition of lime is unne- cessary. Hot soap-suds do not improve the colour. Properties of quercitron brown. — This colour is very per- manent ; light and air alter it very little, and soap-suds by continued action only make it a little paler, while the solu- tion itself becomes yellow. Solution of potash forms reddish brown spots which are removed by vinegar. Ammonia and vinegar produce no alteration. Lime water forms a scarcely perceptible brown spot which vinegar removes. Tinmordants, No. 1 and 2 printed in strong^solution, pro- duce (especially No. 1) a pure yellow, and may be used as dischargers. Solution of chloride of lime acts similar to lime-water, rendering the colour brown, but not destroying it. Remark. — Persian berries give a similar colour with si- milar properties, only that the yellow which the zinc mor- dants produce is more lively and saturated. BROWN FROM OAK BARK AND IRON MORDANT. Light brown from oak bark is produced with the solu- tion of iron alum ; dark brown with the acetate of iron mor- Yellow brown from yellow wood and Iron Mordant. 61 dant. The mordanted cloth is purified by passing it through a cow-dung bath. To form a dark brown from oak bark 6 lbs of mordanted cloth are to be employed for 12 lbs of oak bark. Dyeing. — When the oak bark is very finely pulverized a number of small chips (as in the quercitron bark) stick to the cloth. We should, therefore, employ a cool decoction for dyeing, and heat the solution gradually to the boiling point. Hot soap-suds effect no improvement of the colour. Properties of oak hark brown. — This colour is very perma- nent in the air, light and soap-suds. When boiled with soap-suds the colour becomes first darker, then brighter. Solution of potash makes reddish brown spots which vinegar does not completely remove. Ammonia and vinegar produce no alteration. Lime water forms a scarcely perceptible brown spot, which vinegar removes. Lime juice forms a grayish white spots, which ammonia converts into dark brown. Tin mordants. No. 1 and 2, printed in a strong solution, take the colour completely away and form a bright nut brown. Solution of chloride of lime printed upon it acts in a similar manner to the lime water, not destroying the colour, but rendering it strongly brown. Remark. — Willow bark (especially the basket willow) gives similar colours with the same properties. YELLOW BROWN FROM YELLOW WOOD AND IRON MORDANT. Light yellow brown from yellow wood is formed with the solution of iron alum. No. 1. Dark yellow brown from acetate of iron mordant. No. 2. When the cloth is passed through a hot cow-dung bath, the dark colour becomes blacker. The cloth is purified by rinsing it in running water. To produce a dark shade 8 lbs of mordanted cloth are employed w^ith 3 to 5 lbs of yellow wood.* Properties of brown from yellow wood. — In light and air this colour fades somewhat, while it acquires a bright but not disagreeable colour. ♦ With this dyestufF dark colours can only be obtained by adding a great excess. 62 The Art of Dyeing. When boiled for \ of an hour in soap-suds consisting of 1 lb soap to 200 lbs water, it loses much of its colour and acquires a light yellow brown shade. Solution of potash forms reddish brown spots, which are completely removed by vinegar. Ammonia dissolves the dye and becomes yellowish. Lime water and vinegar have no injurious action. Lime juice forms light yellow spots, which after being moistened with ammonia become greenish. Tin mordants. No. 1 and 2, printed upon it, form a pure yellow. Solution of chloride of lime printed upon it, forms a dirty brown. BROWN FROM TANNIN AND IRON MORDANT. Light tannin brown is formed with the solution of alum, No. 1 ; dark tannin brown with the acetate of iron mor- dant, No. 2. The colour is purified by passing it through a cow-dung bath. To form dark tannin brown 13 lbs of mordanted cloth are employed with 5 lbs of tannin. The dyeing is per- formed by gradually raising the heat to boiling. Soap-suds do not improve the colour. The bright tannin brown be- comes darker by being passed through hot soap-suds. Properties of tannin brown, — Tannin colours which are fixed by iron mordants are on the whole very permanent in air and light, and stand washing very well. Lime water and ammonia do not alter the dark tannin brown. Solution of potash produces a reddish brown colour, which is completely removed by vinegar. Lime juice makes yellowish white spots which are re-dis- solved by ammonia. Vinegar has no injurious action. Tin mordants, No. 1 and 2, when printed on it form a sulphur yellow, and cannot, therefore, be employed to dis- charge it. Solution of chloride of lime produces no change on the dark tannin brown. BLACK FROM LOGWOOD AND IRON MORDANTS. Light logwood black, which is a peculiar gray, like all black colours becomes gray by dilution. It is formed A nalyses of Boohs . 63 with tlie solution of iron alum, No. I. Dark logwood black is produced with the acetate of iron mordant, No. 2. Logwood colours do not stand stronger iron mordants. The mordanted cloth, as with all colours which have iron for their base, is purified in the cow-dung bath. To form the dark logwood black, 4 lbs. of mordanted cloth are required for 1 lb. of logwood. Dyeing. — For this purpose a decoction of logwood is em- ployed, which is rendered lukewarm by the addition of cold water. The cloth should be dyed in this, but the so- lution should not be boiled. The black acquires, by hot soap-suds, a deep velvet lustre. Properties of logwood black, — This colour, when it is formed with not too much iron mordant, is very permanent, while light, air and washing with soap have but little, action on it. Lime water, ammonia and vinegar have no injurious action. Lime juice produces a slight spot which ammonia com- pletely removes. Solution of potash changes the logwood black most. It makes a brownish yellow spot which completely disappears by immersion in vinegar. Tin mordants. No. 1 and 2, printed on it in a stronger solution discharge a violet colour. {To he continued.) Ayticle XI. ANALYSES OF BOOKS. Narrative of an Excursion to the Lake Amsanctiis and to Mount Vultur in Apidia. By Charles Daubeny, M.D. F.R.S., &c. {Read to the Ashmolean Society.) The localities to which this tour refers are situated in the midst of volcanoes, which have been comparatively in recent action. The author has devoted much time to the careful investigation of the chemical products of volcanoes, and on the present occasion these have not been forgot. He compares Lagoni with Amsanctus. " At the Lagoni we see pools of water in a state of absolute ebullition, from the quantity of steam which is constantly rising through them, and which imparts to them a temperature exceeding 180° of Fahrenheit. This steam seems to carry up with it boracic acid and sal ammoniac ; the former in sufficient quantities to make it worth while to evapo* 64 Analyses of Books. rate the water through which it passes in order to collect it ; the liquid being conducted into shallow troughs, where it is mixed with soda, by which addition crystals of borax are obtained from it as the aqueous portion escapes. " Now, when we compare together the eftects produced by the disengagement of steam and sulphuretted hydrogen, owing almost unquestionably to a volcanic cause, in the instance before us and in that of the Lake Amsanctus, we are naturally led to apply the same explanation to those immense deposits of sulphur which occur on the western side of Sicily. If any doubt should exist as to the fact of their having been so produced, it may be removed by reflecting, that we know of no instance of sulphur being sublimed in uncombined form by volcanic action, and that seems scarcely possible for such an event to occur, without the combustion of the sulphur taking place the instant of its comming into contact with atmospheric air. '• Hence it may be inferred, that the whole of this vast deposit in Sicily has been occasioned by a decomposition of sulphuretted hydro- gen gas, such as has taken place on a smaller scale at Lake Amsanc- tns, and has there impregnated the surrounding rocks with crystals of the same material. " In Sicily too we meet with all the combinations which sulphuric acid is capable of forming with the earths present — in the beds of sul- phate of lime, of strontian, of barytes, of magnesia, that occur — there also we see in the immediate neighbourhood warm springs impreg- nated with sulphuretted hydrogen — memorials, as it were, of the cause, which had produced these deposits. " May we not also be led to conjecture, that the gypsum so com- monly present in the tertiary clay of Volterra and the maremnse of Tuscany, has been produced by the same process, especially when we find this clay associated, as it frequently is, with beds or nests of sul- phur. " Thus the formation of the blue clay, in Sicily and in the ma- remnae of Tuscany, would have taken place, not only on the same epoch, which is generally admitted to have been the case, but under the same physical conditions, one as the other, and a volcanic action similar to that going on at the Lago d' Ansanto and at Monte Cerboli would likewise have given rise to the deposits, which the former contain, in common with the rocks found immediately round the spots, where the above operations are at present proceeding. " But there is another circumstance also worth noticing, although the inference to which it seems to point will scarcely receive admis- sion until further proof can be adduced in support of it. I allude to the association of salt springs with gypsum and sulphur both in Tus- cany and Sicily. Their occurrence in such localities as these might induce us to conjecture, that the same volcanic action, which pro- duced the sulphuric salts, and volatilized the sulphur, has been instru- mental also in separating the salts from its solution in water, and thus serve to explain, in these instances at least, the puzzling fact, that rock-salt is found associated, as is so commonly the case, with beds of gypsum. The connexion between the above phenomena may per- haps be seen more clearly by the following tabular view ; Analyses of Books. 65 fsulphuretted hydrogen, sal am- Vol canoes give out <( moniac^ boracic acid, muriatic (^ acid, steam ; , S deposits of sulphur, of sulphuric ^°^^*"^^ ( salts, of muriatic salts, &c. Moffettes, connected geographical-^ ly with volcanoes either novir in > the same principles, action, or extinct, give out . .J J ( deposits of sulphur and of sul- ^"^'^""^ t phuric salts. Many tertiary clays, some of whichl ^^^ ^^ ^^ ^^j_ are connected ffeort o ^ >* bo ^ fe u 0 •^ o I; Q M o <^ « '^^ w ^ s t 1 03 >% ^ 2 :1 * ^ s - 2 ! 1-3^ 1 Sit O »- r« I— I Q) L4 Ob.® « o ^ fl es 0) 1^ a 08 O be . ^ be % >--a ■5 « fi c ?J * i| ® 3 d 0,-2 ^ CS 5 -.>r3-"cS(53 qco—, bDaiaJcj>_ o bo M C o) C iJ £ • T^ t> bo 3 a s « > o ^ * bc^ '^ •2 bovj s--§ s ^"'H 3 2^ ^-^a; ^sj.s 63 N ^ P N « N _ 5- c fl f << !>>>0 fl O 3^ g J 2 1;J "3 '^ "^ : ^ M O S es . ^ ® . ® . o a *< o . H^5 fe^ W H H 1^ ^1^' H ^' a ;^' Ig ^ Ig ;g^' ^' ^' M ;/; !>3 ;/;• H ^ ^ pq W H ^' pj W W 'd,^:A^^f4 ^ ^ H -^=^>-.^ '■^ ;>. ""^ "^ '^■' . ^ W H H , • ^ JS r^ . ■^r" O >r5 o o IC CO -H >0 (> CO CO O Cp (N. O i{i O^ O^ Q> t?. 39 e^ IN G<( >-'5 3<>inC0S<»6-C0TH«0'59»«3*Oai'0C0 CO 'O t^ O ©* GO Tjt tH >* in 00 '3^ CO ^O >-0 CO ooiCOtCi-':io>ot>Jvcoooo^c^o^cp^ COG939&*(39C3<(!?*e9<39S^S->G9<3^39 d-. c> 6^ 39 39 09 -59 O 00 CO CO CO Ol ■'H -o •O "C O Oi Oi c^ c o^ 3Q 39 CO 39 Oi Oi -^ 00 Tf tp o en 0> Oi O CTi ^> 39 CO 39 T-4 O O 'O O o> '-O 39 O- Oi 'O -+• 00 to oi 6> 3) 39 39Tor C 'O cr, j> •Oi di 3* 3^ 'O «>. o o Oi CO o CO T? lO Tft ^ d- oi Oi d- 39 39 39 39 ^O CO 'O O 'O -n •* 'o ^3 CO TP T-> ^ O 00 CO Oi di di d. 3^ 3^1 3> ^'^^oT 1 — CO o 00 CO Oi 39 Oi CO 39 ^ 'O 00 tH O^ Oi CO h. di d. di di 3* 39 39 39 39 CO i> O to «^ T-i i> O. 0< Oi i> o o 00 to CO CO o Tf* O J^ CO 03 CO b- o ^ Oi Oi O. Oi 39 39 39 39 tH (^ O CO CO CO •<* Oi rt to O C7i iTi 39 to -r- o. o t^ Oi c -o o. t^ to '-0 CO tH in 00 to —I i-O 'O ^ 'O di di di Oi 3* 39 39 39 O -O CO •rH 00 O CO 00 Oi iiO 'O t^ ^ iO 00 tH i> Oi Oi Oi t> viSel^ t^'OOt- "^i, I C0tHS9tHi-I t-(t1'Ht-I39 -H tH — 'S -,1"* t*^3*OOCOCO -i:5c|^^^ C0C0T-C0^C0-}"TjH>jr;tOOC0C0i>.OiiCO«0rH 39 CO <0 *v t^ iO 'oO CO CO IC Tf 39 CO ©> 3^ 39 39 C *♦ CO iC ■* "iO . ■f b- O CO ^ o "O ■* >* Tf «c »c to *r> to »-o .«C -H CO 39 .S9 lO ■* r}< Tf ■* Tt< iO t: ^O lO »o »o : X*; O O 39 >»r50iTj c tHG9©<3<© ^^ p-ardens 103. ,, serratifolium. S ^ 104. Coreopsis tinctoria. Grown in pots, &c., as an or- namental plant. 105. Crataeva religiosa. Commonly to be found in the neighbourhood of temples. 106. Cactus Ficus indica, 107. Calyptranthus caryophyllata. Native name Jamb; the fruit is eaten. 108. Capparis Zeylonica. 109. ,, trifoliad, or Crataeva religiosa, 110. ,, sepiaria. 111. ,, acuminata. 112. Calophyllum Inophyllum. Avery pretty tree, com- mon in the Concan and Malabar. Oil is expressed from the seeds and used for lamps by the poorer classes of natives. 1 13. Corchorus acutangulus. Annual; common in the rains. \\^, CX^TO^Qudirum Siphonanthus, In gardens only. 115. ,, infortunatum.* * This plant occurs in Danes' I. Chjna. — Edit. VOL. IV. I 114 Mr. Graham* s Catalogue of Plants. 116. Clerodendrum/ra^rctws in gardens. 1 1 7. Cleome 6-phylla. 118. ,, viscosa. 119. CT0i\x\2ivm verrucosa, 120. Clitorea Teimalea. 121 . CitTxxsDecumana. Pummalo or shaddock, commonly cultivated. 122. Citrus Aurantium. 123. ,, Limetta. 124. Cacalia sonchifolia.* 125. Chrysanthemum Indicum. 126. Cadsuarina mwrzcato. Common in Bombay, where it is planted for ornament. It shoots up very rapidly. 127. Coix Lachryma. 128. Cicca disticha. Fruit sometimes used for tarts. 129. Cocos nucifera. 130. Caryota urens. This beautiful palm grows plenti- fully on the Ghauts. 131. Croton variegatum. This has obtained the name of laurel, and is very commonly grown in pots. The tempo^ rary bungalows on the Esplanade are surrounded with it to keep out the glare of the sun. The C. Tiglium grows in Guzurat. I have never seen it. 132. Cynanchum extensum. A common twining plant. 133. Cucurbita Citrullus. 134. ,, hispida. 135. ,, lagenaria. The melon and cucumber family are very generally cultivated, and form a common article of food with the natives. 136. Cucumis sativus. 137. ,, Colocynthis. In the Deccan. 138. „ Melo. 139. ,, acutangulus, 140. ,, Citrullus. 141. ,, Maderaspatanus. • This plant is also a native of China. I have found it abundantly on a rocky point W. of Danes Island village, Whampoa, and also on the opposite side of the river Tigris. The correspondence of the Flora .of Malabar and China is very striking, but the present catalogue shews that the same observation does not apply to the Concan coast. — Edit. Collected at Bombay* 116 142. Cylista scariosa. Scarce. 143. Cannabis sativa. An intoxicating liquor called Bhang is prepared from it. 144. Cycas circinalis. 145. Carica Papaya. Generally cultivated. 146. Cassandra undulcefolia. 147. Carthamus tenehrans. 148. Caesulia axillaris. 149. Combretum decandrum, 150. Conyza cinerea. 151. Cordia Myxa. A tree much resembling the alder. Fruit sometimes pickled. 152. Cordia angustifolia, 153. Coronilla grandiflora. Natives commonly plant this tree about their houses. It has large shovry flovrers and is of very quick growth. 154. Ceanothus Zeylonica. Elephanta. 155. Qe\i\^ orientalis. 156. Caesalpinia pM/c^erHm«. 157. Capparis aphylla. Common in the barren lands of Deccan. 158. Careya arbor ea, I have seen only one tree on Malabar hill. 159. Casearia elliptica. 160. Chloris barbata, 161. Cyperus ro^Mw _ 5-S41 Chloride of potassium -\ ' Carbonate, sulphate, and phos- ) o- ii n phate of soda \ Subsesquiphosphate of iron - - 1*021 Subsesquiphosphate of lime - - 0*056 Phosphate of magnesia - - - 0*193 Peroxide of iron 0*203 Carbonate of lime - - Carbonate of magnesia I - - 0-326 1000-000 Mr. W. Galhraith on some Astronomical, Sec. 127 Article VII. On some Astronomical Methods of Observation. By William Galbraith, A.m., Teacher of Mathematics, Edinburgh. {Continued from page 45.) II. — REMARKS ON THE METHODS GENERALLY EMPLOYED IN MAKING CIRCUMMERIDIAN OBSERVATIONS. When the smaller instruments of astronomy are em- ployed by the method of repetition, it is of importance to ob- servers to be aware of the limits within which their obser- vations ought to be restrained, so as to insure the requisite accuracy. This is the more to be insisted upon, as some authors seem unconscious of the limits to which observa- tions, under given circumstances, ought to be restricted, and unacquainted with the degree of accuracy resulting from the use of different tables in the hands of the public. The usual tables of reduction are generally formed by throwing the expression derived from the principles of spherical trigonometry into a series of two or three terms. In general, however, when it becomes necessary to embrace more than one, or at most two terms, besides the proba- bility of introducing other errors, the application of a series is more troublesome than the direct computation by sphe- rical trigonometry, and to avoid these, it becomes neces- sary to select objects which, by their situation with respect to the observer, are convenient and proper for such a mode of observation. In general, it may be remarked, that objects near the zenith, though the most eligible for zenith sectors, or mural circles, are disadvantageous for smaller instruments, such as Borda's repeating circle, or other portable altitude and azimuth circles, when the observations are repeated a considerable number of times near the meridian. For the use of the latter class of instruments, a considerable zenith distance is necessary to obtain the requisite accuracy, for it will be found, by direct calculation, that when the latitude is 30°, the declination 20°, of the same name with the lati- tude, and consequently the meridian zenith distance 10°, that even Delambre's formula embracing these terms gives results erroneous to the amount of 47" in excess, if the horary distance from the meridian, when the observation 128 Mr, William Galbiaith^ on seme is made, extend to 30 minutes of time ; though, no doubt, this error is diminished when combined with observations made near the meridian. Again, when the latitude is 40°, the declination 20°, and the zenith distance also 20°, the same formula to three turns gives results incorrect to about half a second in excess, while the first two turns, or those commonly used, give an error of about 4 " in defect. Lastly, when the latitude is so high as fifty degrees, the declination still 20°, and the zenith distance 30°, Delambre's formula to these turns gives, at 30 minutes distance from the meridian, correct results ; while two turns give a small error of about half a second in defect. Assuming different numbers somewhat analogous but with similar relations, the same conclusion would follow. It may, therefore, be concluded that when the zenith distance in mean latitudes amounts to about 30°, two terms of Delambre's formula, or their results in tables, are sufiSciently correct for practical purposes at a horary distance from the meridian of about 30 minutes, and then the calculation for the mean of a con- siderable number of repetitions is comparatively simple. Instead of Delambi'e's formula, or tables derived frOm it, some practical astronomers recommend a table given by the late Dr. Thomas Young, consisting of natural versed sines, which are nothing more than the first part of Delambre's table in a less convenient form, and requiring the additional trouble of employing a constant log within to convert them into Delambre's numbers in every opera- tion, without any equivalent advantage in any respect over the other method ;* in the words of Dr. Pearson, " Dr. Young having simplified (complicated he should have said) the preceding formula by omitting the second term," &;c. Now it has already been shown that the second term cannot be admitted unless the zenith distance be considerable, not less than 20° or 30°, at 30 minutes from the meridian, or the object to be observed be a circumpolar star not very distant from the pole, in mean latitudes, and of this any observer may easily satisfy himself. If, for example, at London circummeridian observations be made extending to 24 minutes from the meridian, (the extent to which Dr. Young's table has been carried, in a • The author of these remarks has endeavoured elsewhere to remedy this. Astronomical Metliods of Observation, 129 tract published by Messrs. Troughton and Simms,) to de- termine the obliquity of the ecliptic at the summer solstice, the first two terms of Delambre's formula would be suf- ficient, though Dr. Young's table, recommended by Dr. Pearson, and more lately approved by Mr. Simms, would, at 24 minutes from the meridian, give results erroneous to about 7", a quantity quite inadmissible, though this problem is just such a one as is, under the given circumstances, suited to the smaller class of altitude and azimuth circles, generally in the hands of astronomical students, and re- peating circles previously alluded to. If, however, the horary distance from the meridian be, under such circumstances, restricted to 12 minutes of time, which will admit of a sufficiently extensive number of re- petitions useful to exterminate casual errors of observation, reading and dividing; two terms of Delambre's formula will be fully adequate for the purpose, while the error arising from the use of Dr. Young's table will not exceed half a second. With regard to the most eligible size of an instrument, it is difficult to come at an accurate conclusion. That must, in a great degree, be regulated by the purposes for which it is intended. I am strongly inclined to think, however, that circles of moderate size, and of the most simple yet substantial construction are the most likely to give satis- faction. Very large mural circles that do not revolve in azimuth, especially when employed to make observations on the sun, are liable to suffer unequal expansions from heat on that side next the sun, being acted on powerfully if not shaded, which it is difficult to do completely, while the opposite side is slighty affected by its position in the shade of the other, and it is doubtful, in my opinion, whether a considerable number of microscopes except under peculiar circumstances will correct the errors arising from this cause. On the other hand, a much smaller instrument re- volving in azimuth, and by that means having its different sides, though as much shaded as possible, exposed partially in succession to the sun will expand much more equally, and when the mean of three or four verniers or microscopes read at each observation, which may be repeated two or three times in pairs of double observations, within the VOL. IV. K 130 Mr, William Galhraith, on some proper time near the meridian ; on the principles of the theory of probabilities, the errors arising from all the dif- ferent causes affecting the accuracy of the results must, in a great degree, destroy each other. Though this conclusion is the most probable in reference to a steady well constructed instrument, yet it must be re- ceived under certain qualifications, since too much praise has doubtless been lavished on the omnipotence of Borda's repeating circle, especially by foreigners. M. Biot, after explaining the principles of the repeating circle, says, ** Let us examine, novr, in vt^hat respect the repeated multiplica- tion of the angle proves advantageous. It would have none, if the divisions cut upon the circle were mathematically exact, and if the observer could direct the intersections of the cross wires in his telescope perfectly correct, for, in that case, one observation would give the zenith distance exact. But as these conditions cannot be accomplished in practice, the repetition of the angles supplies the defect by compen- sations. With regard to the error of the divisions, it is clear, that the arcs measured, follow without interruption upon the limb, in such a manner that the print of the limb, which is the termination of the previous observa- tion, becomes the origin of the succeeding. From this it follows," says M. Biot, " that the sum of the observa- tions, or the whole arc passed over by the verniers, com- prehends no intermediate error, but the errors of the two ex- treme readings at the commencement and termination of the observations." That this conclusion of M. Biot may be true, it is necessary that there be no, or at least an insen- sible, resistance in the centre work to the action of the tan- gent screws, and that there is no imperfection in the tangent screws in producing motion, nor in the clamping screws in securing permanent positions. Now, it is clear that if there is the least defect in all or any of these, M. Biot's conclusion will be erroneous, and such must of necessity be the case to a certain degree, since it depends upon the ma- terials of which the instrument is constructed, and cannot be removed by the abilities of the artist, or the perfection of the workmanship, however excellent it may be. Hence, it necessarily follows that a slight relative motion must take place between the verniers and the circle for each repetition, Astronomical Methods of Observation. 131 causing by that means a small error, which will he continually repeated, and which, therefore, the principle of repetition can- not cure. It is, I believe, owing to this cause th-at a con- stant error of about 5", according to Baron Zach, may remain in some instruments in a series of many hundred observations made w^ith the repeating circle when the clamping irons are imperfect. M. Biot goes on to say, that the errors of the extreme readings at the commencement and termination are much diminished, because the circle has generally four verniers that are read separately, and of which, the mean marks the commencement and termination of the total with a great probability of accuracy. Finally, the small error which still remains, notwithstanding these precautions in the extreme readings, is distributed over the entire arc measured on the limb, and therefore has an in- sensible influence on the simple value of one observation, when these observations are sufficiently multiplied. The errors of the division, then, in the repeating circle itself are also thus diminished by repetition, and the compensation of errors is not the effect of probability, but of certainty. " To estimate the extent of this compensation, it may be remarked, that our (French) repeating circles are generally about 15 inches in diameter, and the error of division cannot exceed 15". If the error would be reduced to half a second after thirty observations, what would it become after eighty or one hundred 1 What does it become after, as has often been done, the series of different days are made to succeed one another, without interruption, upon the limb, so that the two errors of the extreme readings are extended upon a total arc, which contains the simple arc many thousand times ? The errors of division, then, in this instrument become evanescent, and it is impossible they can be entirely destroyed in the largest instruments, if they are not repeaters. Never can the address of an artist equal a mathematical proceeding." But there are other errors which are destroyed by the principle of probabilities in the use of the repeating circle that still remain in other instruments. Such are, the errors of the level, which were small in the original repeating circles, and in those later constructed still less, in which the divisions of the level give immediately fractions of a K 2 132 Mr. William Galhraith, on some second. Such is also the case with the errors of pointing, or those arising from directing the intersection of the cross wires of the telescopes to the objects observed, which, though small of themselves, are destroyed like those of the level by their fortuitous compensation in many thousands of obser- vations. These errors exist also (though I may add in a less degree) in the observations made with large instru- ments, as the mural circles. For the error of pointing is still found, though diminished by the greater power of the telescope, and that of the level is represented by the error of the plumb-line. But in this case the small number of observations does not admit of a compensation as exact as in the repeating circle. If we suppose that the accuracy of mean results is in the ratio compounded of the number of observations, and of the length of the radius of the in- strument, one hundred observations made with a repeating circle of two decimetres, or about eight English inches radius, would be equivalent to one observation made with a mural circle of twenty metres radius, or about sixty-six English feet. " Could we obtain such instruments," says M. Biot, *' and, above all, could we employ them in obser- vations which require us to transport them from place to place ?" Now, though the repeating circle is in the hands of an able observer an instrument capable of great pre- cision, yet we cannot assent to the extravagant eulogium thus betowed upon it by M. Biot in his Astronomic Phy- sique, because it rests on assumptions too gratuitous to be grarxted without qualification ; and, as we have already re- marked, he has not alluded at all to the errors inseparable from its construction, and the method of using it when exe- cuted by the best artists. However perfect the damping screws may be, yet still, by repeating the observations, repeated small relative mo- tions by pressure must take place between the verniers and limbs, which remain as a constant error that no continua- tion of the process of repetition can remove, because it arises from that very principle. If, however, an equal number of observations at nearly equal zenith distances on opposite sides of the zenith be taken, then on the principles of probabilities, it may be expected that the errors from this cause will likewise have a tendency to destroy each Astronomical Methods of Observation. 133 other. Thus, by a judicious use of the repeating circle it may be employed to great advantage in all observations which require a moderately sized instrument capable of easy transportation. Still, however, the complex nature of its construction and the involved methods of observation are inherent disadvantages, which render a commodious instrument of similar dimensions but more simple in prin- ciple a desideratum to a numerous class of practical astro- nomers. The only other instruments whose prices are moderate and dimensions convenient are Captain Kater's circle some- what enlarged, and Mr. Troughton's portable altitude and azimuth circle. In these the repeating principle so much recommended in Borda's, is dispensed with for the purpose of securing stability and permanency of adjustment, which are the main desiderata in the other. Though the same principle of repetition cannot be prac- tised by these instruments as in that of Borda, yet the observations may be repeated near the meridian with suc- cess, in which the constant error arising from the imper- fection of the repeated damping on Borda's plan, is thereby avoided, while by means of three verniers carefully made, combined with the motion of the celestial body in zenith distance during the time of repetition, the errors of division and pointing will, if not entirely destroyed, be greatly dimi- nished— a proposition supported by uniform experience. In this country the use of the great mural circle perma- nently fixed in the meridian is generally adhered to, and by means of its size, the power of its telescope, and the number of its reading microscopes, its errors are supposed to be almost entirely destroyed, though the principle of repetition be abandoned. Thus by the introduction of one advantage, another is lost instead of attempting a union of both. The smaller circles possessing the property of re- peating the observations, may, therefore, approach very nearly the precision of the larger, as has been proved in the measurement of the French arc of the meridian compared with the British trigonometrical survey. It is indeed difiicult to say, whether the final results of the one or the other possess the superiority, though the former was exe- cuted chiefly with Borda's repeating circle of about 16 134 . Mr, William Galbralth, on some inches diameter, or 8 inches radius both with regard to astronomical and geodetical observations, while the latter had the benefit of a zenith sector of 8 feet radius, and a theodolite of 3 feet in diameter, both without the principle of repetition adopted by Borda. Hence, it may in general be concluded, that the principle of repetition employed in one class of instruments was nearly equivalent in securing accuracy of results to the advantage of large size, and the superior power of the telescopes in the other. Hence, we may also infer, that one of Mr. Troughton's objections to the repeating circle, namely, that when the instrument has a telescope of small power the observations are charged with errors of vision which the repeating principle will not cure, is not borne out by experience. Indeed we cannot comprehend the notion why the errors of vision as well as of division according to the usual doctrine of probabilities are, if not destroyed, at least greatly diminished, by the principle of repetition. MM. Lenoir and Fortin have lately improved the movements of the repeating circle in some respects according to Puissant, and Mr. Troughton has given some of its parts a better position for diminishing friction and insuring accuracy of motion, though on the whole it is still complex in its construction, and, so long as its peculiar repeating principle is retained, it cannot be much simplified. The late M. Reichenbach, of Munich, constructed repeating circles which for some time have enjoyed great reputation, chiefly on account of the goodness of the tangent and damping screws, and the accuracy of the division. The superior telescope is also attached to a circle turning with ease and precision within the graduated circle and having their faces both in the same plane. On the recommendation of Laplace this artist constructed a large repeating circle of this description for the Royal Observatory at Paris. Whatever properties it may possess yet it has been thought advisable to have also a large mural circle on the principles of Mr. Troughton constructed by Fortin, which the French express a hope will contribute greatly to the advancement of astronomy. From these circumstances it seems to be admitted that the powers of the repeating circle have been overrated, and that the ad- vantages derived from the repeating principle are in a great Astronomical Methods of Observation. 135 degree counterbalanced by the defects of its construction. May we, therefore, infer that the smaller class of portable circles of the constructions of Troughton and Kater which admit of repeating the observations near the meridian a sufficient number of times to insure accuracy, are, from the compactness of their structure, their stability and accuracy of motion, superior to the repeating circle. Of all these circles Kater's is the cheapest and susceptible of great accuracy when not too small. The size I would venture to recommend would be about 6 or 8 inches in diameter with telescopes magnifying 20 or 30 times and the three verniers each reading 10". To those who are willing and able to afford the expense, one of Troughton's altitude and azimuth circles of 10 or 12 inches in diameter would prove an ex- cellent instrument, though for travellers it would be rather too heavy. In that case Kater's would be a good substitute and its efficiency will be shown in the following obser- vations. (To be continued.) Article VIII. On the Curved Figures 'produced by rapidly rotating Disks. By Charles Tomlinson, Esq. ( Continued from Vol. iii., page 44. J Since the publication of the last paper, I have taken adr vantage of a visit from my friend Mr. Dodd, further to in- vestigate several additional facts on this subject. A part of the experiments before detailed, as well as one by Professor Wheatstone, was performed simply by viewing the rotating disk for one instant of time during various sudden flashes of light, the result being the resolution of the various figures on the disk (whatever they may be) into precisely their original stationary arrangement ; but the ex- periments with a slitted disk are of a more extended na- ture, a new element entering into the resulting phenomena, namely, the generation of curved lines where none pre- viously existed, and the consequent production of new figures of considerable beauty. By referring to vol. iii. page 42, the reader will find tliat 136 Mr. Charles Tomlinson, on the Curved Figures the radii of a star on the smaller disk when viewed through a slit in the larger disk, and both revolving, were curved. The nature and symmetry of these curves are dependent on several conditions, which may he thus stated : 1. The relative sizes of the disks. 2. The relative velocities of the disks. 3. The respective rotations being in the same, or in oppo- site directions. 4. The situation of the slit. 5. The part of the slit to which the eye is applied. The great variations produced by changes in these con- ditions render it impossible to convey a correct idea of the curves, unless we adhere to one ratio of proportion in each of the above particulars, and to effect this in the completest manner, the following mode of observation was adopted : Instead of employing two rotating disks, the slit is made in the disk, which is the object of experiment, and the eye, placed behind the disk, views through the slit the image of the rotating figure reflected in a stationary plane mirror, placed in front of the disk, within about two feet. Thus, by considering the revolving image as a second re- volving disk, the following conditions are fulfilled : 1. The two disks are of equal size. 2. They rotate with equal velocities. 3. They rotate in the same direction. These three data being thus constant, the effect of varia- tion in the fourth and fifth will now be described. The disk. Fie:. 1. is covered with a star, consisting of eight black and eight red radial bands. The slit A. B. occupies nearly a Produced by rapidly rotating Disks. 137 semi-diameter in the centre of one of the bands, and it may be stated, once for all, that the eye is placed behind the disk, so that the front of the disk may be seen re- flected in the mirror, which occurs once during one revolution of the disk, and if the disk perform more than six revolutions per second, an uninterrupted view of the figure can, of course, be obtained. This arrangement may be termed the mirror apparatus. Under these circumstances figure 1 assumes the form Fig. 1,«. Fig. 1 a. Which offers a general view of the figure, for the curvature of each radius varies with every position of the eye, con- sidered with reference to the inner or the outer end of the slit. When the eye is near the inner end of the slit the radii are congregated much nearer the point A., (figure 1 a) while at and about B the interval between the two upper radii is greatly increased ; but if the eye be held near the outer end of the slit the radii are less curved, and their dis- tribution more equable ; but at whatever part of the slit the eye be applied this rule is constant — that the point A, to- wards which the curves tend, is seen at the axial end of the slit, in consequence of the slit being only at one side of the axis, and the radial band occupying that positiqn is of the same colour as that which contains the slit. If, however, the slit, instead of occupying the centre of one radial band, be on a line of division between two bands, a line of division will occupy the central position, which in the former case was occupied by a band, and, in the latter case, the bands a, b, c, d, will be opposite in colour to e,/, g, h. 138 Mr. Charles Tomlinson, on the Curved Figures A beautiful, but very simple, change in the apparent figure of a striated disk is made by nxerely causing it to re- volve, and viewing it in the usual way, without the mirror apparatus. Fig. 2. represents the disk while stationary. Figure 2 a the disk when simply revolving. The law which regulates the production of the rings, figure 2 a. Fiof. 2 a. appears to be this : whatever tint predominates at any point of the disk, the rapidity of revolution causes the same tint to appear at every other point equidistant from the centre ; and, to ascertain what that tint would be, describe a concentric circle through that point, and by adding the dark portions through which it would pass into one series, and the light portions into another series, by combining the two aggregates we may ascertain beforehand what number of concentric circles will result : the outlines are, of course, not defined, but melt into each other. Produced hy rapidly rotating IHsks. 139 In this case the dark stripes form an odd number, and the proportion of white is greater than the black ; hence the rings ; but suppose the proportions of the two colours to be strictly equal ; that the disk is poised exactly on its centre, and very slightly rotated without the slightest eccentricity of motion, then the stripes, radii, chequers, or whatever figures occupy the surface of the disk (except concentric circles) blend into one uniform tint midway be- tween the two colours of the'disk, entirely free from rings. From this we may deduce : 1 . That, when a disk is so divided that with any radius a circle would pass through equal portions of the two colours, an universal blending of colour will result. 2. That if at any part of the disk a balance of colour be not observed at opposite sides of the centre, concentric rings will result. 3. That, as the wow-existence of that balance depends upon a definite principle of construction, the number and breadth of the rings can be computed ; but, 4. If the equipoise be disturbed by extraneous causes, such as imperfect division, or eccentricity of adjustment, the rings are uncertain and incommeasurable. But the disk, fig. 2, when employed with the mirror ap- paratus, assumes altogether a different arrangement, of which Fig. 2 b. will convey an idea. The surface is laid out in curved con- centric bands of the utmost symmetry, the number and breadth of which are the same as in the rectilinear striae. The centre of these concentric segments, which is at the 140 Mr. Charles Tomlinson, on the Curved Figures axial end of the slit, is either at or exterior to the edge of the disk, according to the position of the eye. This figure (2 b) is produced when the slit cuts the striae at right angles, but when it is parallel to them the figure is totally changed : the bands are all rectilinear, but their parallism is destroyed, as they all seem to diverge from a point situate at the axial end of the slit. Again, when the slit is inclined 45° to the striae, the image presents the shell-like form represented in Fig. 2 c. The same principle, but beautifully modified in its appli- cation, is perceptible on employing a chequered disk. Fi-. 3. The figure which illustrates the striated disk, when simply revolving, figure 2 a, will apply to the present, the only difterence being a more gentle blending of the an- nular tints into each other ; but when viewed through the slit, the reflected image presents the appearance of a tes- selated globe, and the illusion is so perfect that it requires an effort to preserve the idea of a flat surface. Figure 3 a. Produced hy rapidly rotating Disks. 141 These chequers, when viewed through a slit, parallel to the rectilinear division, present Fig. 3 a. Y evidently partaking in the general character of fig, 2 b, the difference being due to the division of the striae into squares. If the slit be inclined 45° to the divisions, all the diverging lines proceeding from Y, figure 3 a, cut the diagonals of the chequers instead of marking their boundaries. The same principles obtain through an endless variety of figures : thus, if the disk be diametrically divided into two, and the slit be on the line of division, the figure is alto- gether unchanged ; but if it be at right angles to that line, the half which contains the slit encroaches upon the other half by the curvature of the line of division, thus presenting the gibbous form of a three quarter moon. Nearly the whole of the experiments now detailed were performed with the mirror-apparatus, for the purpose of getting uniformity in the revolutions, otherwise no definite figures could have been given ; but the figures are the same in principle as those produced by two revolving disks, the latter arrangement presenting figures modified in every imaginable way by one or more of the five conditions before stated. When two disks, for instance, are moving with unequal velocities, the nucleus towards which the curves tend, or from which they seem to spring, oscillates to and fro, and the curves themselves vary in their number and respective distances from each other. The slitted disk is a modification of M. Plateau's Fan- tascope, the latter containing many short slits, and the 142 Analyses of Books. former only one, which consists of a radius nearly of the disk. It is capable of many amusing modifications, with one of which I now conclude this subject. Below, and at right angles to the slit, paste in large characters any word or words, such as AT REST, in an inverted position, so that when seen in a plane mirror the reflected image may be erect and in its natural position. On placing the head behind the disk the words will be seen through the slit in the mirror uninterruptedly, provided the disk perform more than six revolutions per second. In this case the words are seen in, a curved form, which is evidently due to the principle before stated, and the letters are all of the same size, whereas if the slit be parallel to the order of the letters, the latter gradually increase in size from the axis to the outer end of the slit. All the disks should be well illuminated by a direct light falling upon them ; and their backs, where the eye is placed, should be blackened all over, and the multiplying arrange- ment to which the disks are successively attached should allow of comparatively slow and very rapid rotation, Salisbury, 8th January, 1836. Article IX. Analyses of Books. C Continued from page 68. J I. — The Transactions of the Llyinean Society of London. Vol. XVII, part 3rd, 1835. Description of five new species of the Genus PinuSy discovered by Dr. Coulter in California. By Mr. David Don^ Lib. L. S. Notwithstanding the addition of seven new species to this genus, by Mr. Douglas, within the space of a very few years, we have in this paper a detail of the character of five additional species discovered by Dr. Coulter in California ; especially on the western flanks of the northern Andes, and the extensive parallel ranges of mountains which extend from south to north through that country. 1. The. P. Coulteri rises to the height of 80 or 100 feet at an elevation of from 3000 to 4000 feet above the level of the sea ; grow- ing intermingled with the P. Lamhertiana on the mountains of St. Lucia, near the Mission of San Antonio, in latitude 36"". 2. P. muricata, attains a height of 40 feet. It was found at San Luis Analyses of Books. 143 Obispo in latitude 35°, at an elevation of 3000 feet. 3. P, radiata found about Monterey in latitude 36°, near the level of the sea, and growing almost close to the beach. It affords excellent timber, which is very tough and admirably adapted for building boats. 4. P. tu- herculata, resembling in position and appearance the preceding. 5. P bracteata was found growing on the sea side of the mountain range of St. Lucia, about 1000 feet lower than P. Coulteri. The trunk rises to the height of 120 feet, not exceeding 2 feet in circum- ference and as straight as an arrow. Some account of the Galls found on a species of Oak, from the shores of tJie Dead Sea. By Aylmer Bourke Lambert, Esq., F.R.S., V.lP.L.S. This paper contains a description with figures of some galls brought from the Holy Land by the Hon. R. Curzen, and which the author considers to be the " mala insana," or apples of Sodom of history. They grow on the Q vercus infectoriaj a tree which grows abun- dantly in Syria. The insect which forms them has been named by Olivier Diplolepis. When on the tree the galls are of a rich purple and are varnished over with a light substance of the consistence of honey, shining with a most brilliant lustre in the sun, which makes them look like a most delicious and tempting fruit. Note on the Mustard Plant of the Scripture. By Mr. Lambert. The author considers this plant to be the same as that daily used among us. He conceives that the expression " less than all the seeds that be in the earth," used in Scripture was used comparatively and meant nothing more than a small seed. Captains Irby and Mangles have informed the author that our mustard plant, the sinapis nigra, grows in the Holy Land as high as their horses heads, and other travellers have seen it growing to the height of 10 feet. On several new or imperfectly understood British and Euro- pean Plants. By C. C. Babington, F.L.S., &c. 1. Herniaria hirsuta, has been found only at Colney Hatch Barnet, by Hudson, and Milne, and Gordon, but not since 1793. 2. H. glabra. Near Newmarket, Rev. Mr. Hemsted. The description under this title in Hooker's Flora applies to H. ciliata. 3. H. ciliata. Liyard point, Ray and Borrer. 4. Orepis Virens. Common on walls, &c. This plant has usually been confounded with C. tectorum, which does not appear to be a native of this country. It is distinguished from virens by its ** very long fruit, equalling the pappus : attenuated above, its ribs rough ; the margin also of the upper leaves is revolute that not being the case in C. virens." 5. C. biennis. Involucrum, ovate, oblong, both when in flower and seed, not becoming ventricose as in C. virens. 144 Analyses of Books,, 6. Erica Tetralix, Stems branched only towards the base. Leaves and sepals linear, lanceolate, downy, their margins secured so as almost to meet behind. 7. E. Mackaiana, N. S. — FoL quatern. ovat. ciliat. supra glabris, floribus capitat. pedicellatis, sepalis ovat. ciliat. glabris, pe- dicellis pilos. et comentosis, corolla oblong, ovatis, antheris anstat. inclusis, stylo exserto. — Distinguished from^. Tetralix by the form and structure of its leaves and sepals, the glabrous upper surface of the former, and its total difference in habit. It agrees with E. ciliaris in the character of its foliage, but differs from that plant by having anthers awned. Gathered by the author on Craigha Moira, Conna- mara, Ireland, in August, 1835. Mr. Mc Calla, of Roundstone, directed his attention to it, as being, perhaps, a new British heath. It is named after Mr. Mackay, of Dublin. Some botanists consider it as a variety of E. Tetralix. 8. Polygonum Maritirnum. — Christchurchhead, towards Mud- diford Borrer; Heme Bay, Jersey. Mr. W. C. Trevelyan. 9. jP. Rati, — Intermediate between P. Maritirnum and avicu- tare. The P, aviculare /3 of Hook. Brit. Flora. 10. P. dumetorum — Wood at Wimbledon : Mr. J. A. Hankey. 11. P. Convolvulus — Improved description by the author. 12. Euphorbia pilosa- — E. pilosa/3 of Hooker. 13. Euphorbia coralloxides — E pilosa a of Hooker : naturalized at Henfold, Sussex. 14. Habenaria chlorantha — Orchis bifolia a of Smith. 15. H. bifolia— O. bifolia /3 of Smith. 16. H. fornicata — A distinct species, having its anther rounded at the tip and hooded, and the cells parallel ; plant smaller than H, bifolia. Observations on the Species of Fedia. By Joseph Woods, Esq., F. L. S. This genus was originally made from the varieties of the Linnean species, Valeriana locusta, being separated from Valeriana by habit as well as by the want of a feathery crown to the seed. The name comes from Hcedus, or Foedus, a kid, and was introduced by Adanson, although not applied by him to this genus. DecandoUe divides it into four divisions. 1. Locusta: with one or two empty cells and a gibbous corky or spongy mass at the back of the fertile one. 2. Psilocoelae : the two empty cells, each reduced to a hollow nerve. 3. Platycoelae : two empty cells, nearly as large as the fertile ones. 4. Selenocoelae : section of the fruit, crescent shaped, with two empty cells. Mr. Woods suggests that the European species may be divided as follows: A. Flowers ringent. 1. F. Cornucopice: B. flowers nearly regular: A. fruit with a corky mass at the back of the seed. 2. F. olitoria. 3. F. gibbosa b. section of the fruit crescent shaped, two barren cells, a. F. turgida. 5. F. carinata. 6. F. platyloba : C. barren cells two, hardly touching in the middle ; di- visions of the calyxhooked ; flowers in globular heads ; upper leaves Analyses of Books. 1 45 generally pinnatifid at the base. 7. F. Hamata. 8. F. Coronata. 9. F. Ciliata : d barren cells two, hardly touching in the middle j prolonged into teeth or horns, but not forming a membranous calyx. 10. F. echinata. W. F. trigonocarpa. 12. F. Sphaerocarpa. 13. F. pumila : e barren cells two contiguous ; crown erect. 14. F. auricula : /barren cells four. 15. F, vesicaria : g barren cells wanting, or reduced to a mere nerve ; panicle nearly fastigiate ; the lower flowers solitary. 16. F. lasiocephala. 17. F. eriocarpa. 18. F. dentata. 19. F. puherula. 20. F. microcarpa. 21. F. truncata. The paper is illustrated by drawings. De Merchantieis Auctore Thoma, &c. Taylor, M. D., F. L. S. The species of this order of plants, although limited in number, are widely spread over the world, as we find from the Baltic sea to the Mediterranean in Europe, over all America and even the moun- tains of Nepaul. The author treats of such in this paper as have come under his notice, under the genera Marchayitiaj Fegatella, Fimbraria, Lunularia^ Hygropyla. Those who are fond of the study of this beautiful order of plants, we cannot direct to a more dis- tinct source for the solution of any difficulties which they may happen to meet with, although it would have more congenial to the acquire- ments of most botanists if the concluding remarks on each species had been couched in English instead of Latin. We approve of the use of the latter language for stating the specific characters, but to carry the use of a dead language any futher is an abuse. On the Eriogoneae, a tribe of the order Polygonaceae. By G. Bentham, Esq., F. L. S. The genus Eriogonum was first established by Michaux in his Flora B or eali- Americana. The number of plants now known which approach nearly to this genus amount to 40 species. In this paper Mr. Bentham proposes to divide these into three genera. All the species are equally distinguished by their involucrate inflorescence and absence of stipulae, at least to the lower or cauline leaves. But a considerable difference of habit has induced him, at the suggestion of Mr. Brown, not only to separate generically 5 species with uniflo- rous involucres ; but among these to isolate one {Mucronea) which has a compressed and bidentate involucre formed of two leaves instead of a triangular sexdentate one formed of six leaves as in the iowv s^eQiQS ( Chorizanthe), The latter genus is further confirmed and augmented by seven species collected in Chili by Macrae, Cuming, Bridges, &c. Observations on the Genus Hosackia and the American Loti, By George Bentham, Esq., F. L. S. The author modifying his views expressed in the Botanical Register (vol. XV. tab. 1257) in reference to these two genera, is now induced to confine the circumscription of Hosackia to the umbellate species, VOL. IV. L 146 Analyses of Boohs. and proposes to consider the uniflorous ones as belonging to Lotus of which they would form a separate section, which, with reference to the size of the flowers, might be called 3Iicrolotus. The two genera would then be characterized by the form of the flower ; and the peculiarities observable in the organs of vegetation would again be reduced to their proper level, that of subsidiary, not essential cha- racters. In the true Hosackiae the claw of the vexillura is always at some distance from those of the other petals ; the alae adhere by their margins to the carina, and usually (if not always) spread at right angles from it ; the carina is usually less rostrate than in Lotus and the stigma more distinctly capitate. In Microlotus the flower does not present any essential differences from that of our European Lotl. The author describes 11 species of Hosackia, and 5 species of Microlotus. ENTOMOLOGY. Descriptions, ^'c, of the Insects collected by Captain P. P. King, R. N., F. ' R. S., iii the Survey of the Straits of Magellan. By John Curtis, Esq., F. L. S. * A. H. Haliday, Esq., M. A., and Francis Walker, Esq., F. L. S. The collection was formed along the coast from St. Paul's in Brazil to Valparaiso. It is interesting to trace the similarity which exists between the corresponding parallels of the southern and northern hemispheres such as is afltbrded by the present collection. Thus the genus Carabus appears unknown in S. America, excepting about lat. 50° where a species of that group with a narrow thorax has been found ; the genus culex also occurs. The insects of S. America bear little resemblance to those of S. Africa. Descriptions are fiven of species belonging to 66 genera of Hymenoptera, and of 8 genera of Diptera. Characters of Emhia, a genus of insects allied to the White Ants J (Termites) with descriptions of the species of which it is composed By J. O. West wood, Esq., F. L. S. This genus is remarkable at present not only because it consists of species nearly allied to the white ants, but because it is composed of 3 exotic species, each from a difi^erent quarter of the globe, while a single specimen only of each has hitherto come under the observation of entomologists ; each possesses also characters of a higher rank than mere specific distinction, whence he has been under the necessity of considering each as a distinct subgenus ; these are Embia Savignii, Oligotoma Saundersii, and Olynthia Braziliensis. Mr. Westwood has also observed two species imbedded in Gum Copal or Anime, which he has not been able sufficiently to identify. On a new Arachnide uniting the genera Gonyleptes and Pha- langium. By the Rev. F. W. Hope, M.A., F.R.S., F.L.S. This remarkable insect with disproportionally long hinder legs, so long that it is difficult to conceive of what utility they can be, was collected in Brazil by the late Mr. Haworth, a zealous promoter of Scientific Intelligence, Sec. 147 entomology in all its branches. Mr. Hope terms it Dolkhoscelis Haworthii. i — — — '— '■ — — "X;..! "Ll'jL'oO ZOOLOGY. I. — Description of a New Species of the genus Chameleon. By Mr. Samuel Stutchburg, A. L. S., &c. Chameleon cristatus. C. Superciliari occipitalique carina elevata et crenulata, caudae anteriori parte dorsique apophysibus elongatis cristam dorsalem constituentibus : squamis fere rotundis subsequalibus. The striking peculiarity of this animal consists in its having a dorsal crest, supported by the spinous processes of the Vertebrae, by which character it approaches the Basilisks. It was brought from the banks of the river Gaboon in Western Equinoctial Africa, and was presented to the Museum of the Bristol Institution, by Messrs. King and Sons of that city. II. — The Practical Mechanic*s Pochet Guide, <^'c. By Robert WaUace, A. M., Glasgow, 1836. p. 120. This is a very neat and useful little compendium of the most im- portant rules for the practical mechanic, arranged under the heads of I. Prime movers of machinery : 1st. Animal Power. — 2d. Wind power. — 3rd. Water power. — 4th. Steam power. II. Weight, strength, and strain of materials. III. Practical tables : 1st. Weight of metals. — 2nd. Specific gravity and weight of materials. — 3rd. Steam and steam engines. — 4th. Specific cohesion and strength of materials. — 5th. Mechanical powers. The section upon steam is illustrated by a good plate of the steam engine, and a plan is appended to the work of the land which has been drained behind the town of Greenock, and of the great reservoir which is supplied by these numerous drains. We have no doubt that Mr. Wallace's book will be duly appreciated by those for whom it is intended, and we recom- mend it to the attention not of mechanics alone, but of all who are interested in this important branch of philosophy. Article X. SCIENTIFIC INTELLIGENCE. I. — Phai^macy, ^'c. 1. Quinin and Clnchonin. — Geiger has described a simple method of separating these principles from the alkaline mass which does not crystallize with acids, and which Serturner termed Quinoidin, The compound dissolved in water, saturated with an acid, should be mixed with an excess of neutral acetate of lead, by which means the resin- ous matter in combination with the basis will be precipitated in union with the oxide of lead. The solution should then be filtered and digested with freshly heated animal charcoal, until a filtered speci- men ceases to re-act on oxide of lead. The lead may then be pre- cipitated by phosphate of lime, or sulphuretted hydrogen. Potash or soda will now precipitate the Quinin and Cinchonln, and the mother L 2 148 Scientific Intelligence, Sj'c. liquor may be evaporated to separate the last portions. — (Jahreshe' Hcht, 1835.— 252.) 2. JDelphinin. — Couerbe has obtained this principle by the follow- ing process. The seeds of the Delphinium staphysagria, which are gray or brownish, but not black, the latter containing little ac- tive matter, were first subjected to the action of boiling alcohol. The alcoholic extract, after distilling over the alcohol, was treated with dilute sulphuric acid ; the filtered acid solution was precipitated by alkali ; the precipitate dissolved after drying, in boiling alcohol ; the solution treated with incinerated blood, filtered, and evaporated, when the Delphinin remained of the same nature as that which occurs in commerce. One French pound of the seeds affords 55 to 60 grains of such Delphinin. It was dissolved in water acidulated with sulphuric acid, filtered and mixed up by drops with nitric acid, which precipitated a dark brown or reddish as well as a black sub- stance, by which the colour of the solution was greatly altered. After twenty-four hours the precipitate had collected at the bottom of the vessel, when the supernatant liquor was decanted. It was precipitated with a very dilute solution of potash ; the precipitate was well washed, dried, dissolved in absolute alcohol, filtered, and evaporated, when a resinous, yellowish, stongly alkaline mass re- mains, which may be moistened with a little water, lest some nitre should still remain attached to it. Delphinin thus obtained is purer than any hitherto procured, but is a mixture of two different bodies, which may be separated by ether. This dissolves the Delphinin, and leaves another substance, which Couerbe calls Staphisain. Delphinin is a yellowish resin, but its powder is almost white. It has a burning taste, and leaves the impression long behind it. It cannot be crystallized, and melts at 248°. At a higher temperature it decomposes. It is not affected by chlorine at common temperatures, but at 302° it is decomposed, while it first becomes green, then dark brown, and disengages muriatic acid : 150 parts of Delphinin ab- sorbed 20 parts of muriatic acid gas. From which, and two other trials, its atomic weight appears to be 26*5. It consists of carbon 76-69, Azote 5-93, Hydrogen 8*89, Oxygen 7-49. Staphisain is an uncrystallized yellow substance. It melts at 312°. It is almost insoluble in water, which, however, takes up some thousandth parts, and imparts to it an acrid taste. Whether it has an alkaline re- action has not been ascertained. It is soluble in acids, but is not neutralized by them. Hot nitric acid converts it into a bitter resinous substance. It consists of carbon 73*566, Azote 5-779, Hy- drogen 8-709, Oxygen 11.946. (lb, 255.) 3. Brazilin. — Chevreul has obtained the colouring matter of Brazil wood, in the form of small yellowish red needles. — (lb. 317.) 4. Cactin. — Voget has procured 30 per cent, of a carmine red colouring matter from the flowers of the Cactus speciosus. It is taken up with alcohol of 60 to 70 per cent. It is not dissolved by ether and absolute alcohol. After the leaves have been treated with alcohol, a mixture of alcohol and etlier takes up 5 to 10 per cent, of a scarlet red colouring matter. Both are soluble in water. — (lb 318.) 5. Urticin. — According to Knezaureck, the tops of the Urtica Scientific Intelligence, ^c. 149 flioica, or common nettle, afford, in autumn when the leaves are falling off, to water a red colouring matter, which answers well as a dye. With chloride of tin it colours the solution bright red, and forms a red precipitate.— {lb. 318.) 6. Elaterine. — Clamor Marquart gives the following process for separating this alkaloid from the mornordlca elaterium. The nearly- ripe fruit was collected in July, pressed, and the juice evaporated to the consistence of extract. This was then digested with alcohol of 90 per cent., the latter distilled off, and the residue agitated in boiling water, in which, after cooling, the crystals of elaterin are observed covered with chlorophylle. The solid matter is separated from the fluid first, collected upon a filter, and separated from chlorophylle by dropping ether upon it. A colourless crystalline, almost tasteless powder remains, which by distillation leaves a product, containing ammonia. It is insoluble in water, easily soluble in alcohol. It is quite neutral, scarcely soluble in ether, little soluble in cold, very soluble in hot oil of turpentine, from which it does not separate on cooling. 7. Atropin. Brandes and Geiger and Hesse procured this alkaloid by means of ether. According to Geiger and Hesse 62 1- grains of atropin may be procured from a pound of the extract. The impure atropin should be dissolved in water containing yV of sulphuric acid. More should be taken than is necessary for dissolving the atropin, and the solution should be digested for several hours with blood char- coal (hlutlaugenkohle). The filtered yellow solution should then be precipitated with dilute caustic soda. The flocky precipitate is then to be separated from the liquid and washed with cold water, by which means it becomes pulverulent. Some more precipitate will fall down from the mother liquor and will be increased by the addi- tion of common salt. Atropin may be obtained in a crystalline state by dissolving it in the smallest possible quantity of boiling water ; on cooling it crystallizes, or when dissolved in alcohol and allowed to evaporate spontaneously it crystallizes. Atropin possesses the follow- ing properties: — When precipitated by alkali it is a pure white powder containing crystalline particles. It crystallizes from its solu- tion in needle shaped crystals. It possesses no smell but a highly bitter and acrid taste. It is not acted on by light. It has an alka- line reaction. It melts at 122°. At 212° it becomes brown. At 338° it is very brown, and a portion of it sublimes unchanged ; then follows a combustible oil and ammoniacal vapour, and the mass is decomposed leaving much carbon behind. It requires 500 parts of cold water to dissolve it, but when dissolved in 58 parts of hot water it does not separate on cooling*. 30 parts of boiling water are satu- rated by 1 part of atropin, on cooling the greater proportion crystal- lizes. On boiling the solution a small portion of the atropin appears to be volatilized with the vapour of the water ; 8 parts of cold absolute alcohol dissolve it. It is soluble in 63 times its weight of cold ether. Dilute acids are completely neutralized by atropin; concentrated acids decompose it. It gives a yellowish precipitate with chloride of gold and chloride of platinum. It is precipitated white by infusion of galls. According to Liebig 59 parts of anhy- 150 Scientific Intelligence, SfC. drous muriatic acid, saturate 312 parts of atropin which gives the atomic weight 240*6. It consists of carbon 70*986, azote 7*519, hydrogen 3*144, oxygen 13*351 ; from which the atom comes out 23*45. According to Geiger and Hesse the salts of atropin have a bitter taste, are readily soluble in water and alcohol, less so in ether. Muriate of Atropin ^crystallizes in star like needles. When prepared by saturating dry atropin with muriatic acid gas, the salt has an acid re-action, but when crystallized an alkaline re-action. Sulphate of Atropin crystallizes readily. Nitrate of Atropin dries into a clear colourless mass : j grain of this salt dissolves in a drachm of water. Acetate of Atropin crystallizes in stelliform fine needles which lose their acetic acid when completely dried, and are no longer com- pletely soluble in water. Tartrate of Atropin forms a transparent colourless mass. The discovery of atropin is a very important one, because it is to this substance that the extract of Belladonna owes its peculiar pro- perties in a medical point of view ; 1 part of a salt of atropin is equi- valent to 200 parts of extract or 600 of the dried plant. This alkaloid appears to have been first discovered by Mein in 1831. He prepared it by digesting the bruised root of Belladonna in alcohol in the proportion of 24 parts root to 60 alcohol, of 90 per cent. The clear solution was digested with slaked lime and filtered, sulphuric acid was then added which precipitated gypsum. The acid solution was distilled to more than one half, mixed with 6 or 8 parts of water and the alcohol evaporated. The remaining solution was mixed with a little carbonate of potash, which at first precipitated a resinous matter forming a gelatinous mass, when more atropin was precipitated by the addition of carbonate of potash. In from 12 to 24 hours it exhibits a disposition to crystallize, and can then be sepa- rated from the mother liquor and pressed ; it is then soluble in alco- hol and crystallizes by spontaneous evaporation. By a new analysis made by Liebig, the formula for atropin isC34 H^s 1^2 qs and its atomic weight 289*0. (Jahreshericht, 1834, 262.J II. — Phenomena of Crystallization. When the formation of crystals are observed under the microscope according to Ehrenberg, the first thing which attracts attention is a rapid action going on about the crystal ; suddenly a solid point forms in the transparent liquid, appreciable by its opalescence, and increases with astonishing rapidity, shewing that this point concentrates and condenses the saline particles previously dispersed and suspended in the water. This concentration supposes a motion towards the centre, and one is apt to think that the agregation of the atoms is of such a nature that the density will increase towards the edge. In this view it is rather surprising that there should be no motion nor agita- tion in the neighbourhood of the crystal. In order to investigate the subject more accurately, Ehrenberg examined strongly coloured crystals. He dissolved bichromate of potash and sulphate of copper in water : he could not discover in either case any visible current re- Scientific Intelligence, Sfc. 151 suiting from the concentration of the coloured |)articles, nor an agregation around the crystal, while it increased with great rapidity ; yet even by sprinkling a fine powder over the liquid which crystal- lized, no currents could be detected. Hence, crystallization isanalo- gous to the phenomena which it is generally supposed take place when masses agregate in space. A nebulous appearance first occurs, the matter of which gradually condenses in the centre, then a kernel is formed with an areola, and lastly a properly formed world is com- pleted. Ehrenberg has carefully studied some drops of a solution of com- mon salt, and has observed that hexagonal tables are formed at the limit of evaporation often very regular but frequently deposited one upon the other. In the middle of these very delicate hexagonal tables a point was suddenly formed which attracted to it the mass of tables. Immediately the observer noticed there a small tube increasing with immense rapidity and enlarging as the tables diminished. The water of the Baltic and N. Sea are particularly fitted for these observa- tions. Conceiving that the phenomena might be owing to the pre- sence of two different salts, he made an experiment upon common salt, chemically pure and dissolved in distilled water. In this case he observed the same, only not so frequently ; the cubes being gene- rally formed immediately. Mitscherlich has shown that common salt forms hexagonal plates at very low temperatures. But in the present case the temperature was that of the atmosphere. Did the cold produced by the evaporation influence it? — Poggendorff's Ann, No. x., 1835. III. — Uric Acid Calculi in the Biliary Canals. Dr. Aube in dissecting the Lucanus Capreolus found two small gray rough calculi with a crystalline appearance, which were found by Audouin to consist of uric acid. These vessels, to which the name of biliary has been given by modern anatomists, are small in- sulated canals, commonly in the Caecum, and open behind the stomach either by a single mouth or by two. Sometimes one of these extremities opens near the anus. Meckel considered that they secreted a liquid similar to the urine, while Gaede conceived that they were absorbents. The circumstance of uric acid calculi being found in them, however, supports the opinion of Meckel. — Bibiiot. Unicers., April, 1836. IV. — Effect of the price of Corn upon the Population. M. DuPiN has examined this question, by taking the average from the year 1817 to 183*2. The mean annual price of corn during that period has varied from 36 francs 16 cents to 154 fr. 49 c. per hectrolitre. Taking the average of deaths for the 6 years when corn was dear and 6 when it was cheap, we have Mean Price. Annual Deaths. 25 fr. -06 c. h 25023 16 -44 " 24950 152 Scientific Intelligence, ^c. Thus there is only a difference of 73 deaths for 1 million of in- habitants. The following shews the influence of the same cause upon the births : — Mean Price. Aunual Births. 24 fr. 68 c. 30647 16 44 31047 In 1817, the number of marriages diminished 918 per million. — L'Institut., 164. V,— Impurity of Sulphuric Acid. It has been already stated, that English sulphuric acid contains arsenic {Records, ii. 73.) I have found it easy to prove that it con- tains muriatic acid, by placing a small portion of it in a tube with a vegetable substance, such as an oil, and applying heat ; speedily a very strong odour of chlorine is perceptible. The methods by which these two acids may be removed are sufficiently obvious. But, be- sides these, it is well known to contain nitric acid, which is more difficult of separation. Barruel (Jour, de Chim. 3fedic.y ii. 184.) proved the presence of this acid, by its power of dissolving platinum. This effect, I have no doubt, was the consequence of the action of muriatic and nitric acids, 1000 grs. of sulphuric acid dissolving 0'16 of platinum, and was not owing to the sulphuric acid assuming the function of muriatic acid as Barruel seems to think. He found also, that if 2 ounces of sulphuric acid were heated for 2| hours with 3 grammes of sulphur at a temperature of about 300°, no nitric acid could be detected on cooling the acid, shewing that it had been all decom- posed. Hence, an obvious method of removing nitric acid, which is absolutely necessary when working with indigo, especially in manu- factures. Barruel conceives that the acid may be hyponitrous and not nitric acid. — Edit. VI. — Test for Strychnin. Artus recommends sulphocyanodide of potassium as a test for stry- chnin. The resulting salt consists of fine crystals. Unfortunately, however, quinin affords a similar product; Winckler recommends, therefore, corrosive sublimate as a more distinctive test. The mercury can readily be separated from the precipitate by a current of sulphu- retted hydrogen, the muriate of strychnin remaining in solution. — Sv^hne7''s Repertorium iii., 397. VII. — Fossil Flowers. Professor Goppert, of Breslaw and Hrn-Keferstein, have obtained flowers from the brown coal of Wetterau in which the anthers and pollen are distinct. These will be described in the next number of the transactions of the Leopold Academy. — Poggendorff's Ann. xxxvi., 066. Scientific Intelligence, Sfc. 153 VIII. — Composition of Silk. Mulder of Rotterdam has lately made an analysis of silk. Some yellow Neapolitan silk was boiled with distilled water until infusion of galls no longer produced any precipitate; the solution was then evaporated, — a thick gray substance remained. When treated with water a portion of this matter dissolved ; it was gelatin : but the greater part remained insoluble ; it was albumen. The boiled silk being treated with' absolute alcohol afforded some yellow flocks, cerin. The silk was then treated with hot ether. On evaporating the latter a colourless residue remained. Digestion in weak caustic potash took up some fatty matter from this residue, and when boiled with it some resin was separated ; a red colouring matter was left undissolved. The silk was then boiled with concentrated acetic acid. Some albumen was taken up ; the remainder was fibrin of silk. When silk is distilled with dilute sulphuric acid a peculiar acid comes over in minute quantities, which Mulder terms bombic acid. The constituents of yellow silk are — fibrin of silk 53-37, gelatin 20*66, albumen 24*43, cerin 1*39, colouring matter 0*05, fat and resin 0*10. — Poggendorff's Annalen, xxxvii. 594. IX, — Analysis of Phosphate of Lead. By Dr. R. D. Thomson. This specimen was from Lead Hills. Sp. Gr. 6*631. Its constituents are- Chlorine 2-656 Lead 7*668 Protoxide of Lead .... 69*636 Phosphoric acid .... 17*626 Protoxide of iron .... 2*008 Water 0*800 Silica 0*400 100*794 X. — Effect of Alkalies (J'c. on Vegetables. The following has been forwarded by a correspondent : — " During last summer I performed a series of experiments with a view to ascertain what effect various substances had in supporting vegetable growth; for this purpose I procured several plants and placed them in vessels of water, adding to each various proportions of the alkalis, salts and other matters. Now, I found that more than one thousandth part of potassa, soda or their salts, would prove in- jurious, rendering the plant sickly or destroying it according to the strength of the solution. By adding a thousandth part I found the plant invigorated and decidedly more healthy than those parts which were in water alone ; some of these plants existed in these vehicles for six or eight weeks, and, to all appearance, would longer had I prolonged the experiment ; but they required renewing with the stimulcnts after the space of 12, 24, or 36 hours, according to the 154 Scientific Intelligence, Sfc. size of the plant ; for water rendered alkaline by carbonate of soda, for instance, to the strength above mentioned, although it would at the time turn reddened litmus paper blue and display its presence on tumeric paper, yet, after a lapse of some hours, the water ceased to possess these properties, and even the plants if cut transversely near their lower part, although the alkali had been absorbed, would de- note the presence of a free acid. Beneficial as were the alkalis, still more visible developement ensued from those vessels wherein I had placed the oxide of iron and of zinc ; these would bear a larger quantity than the former, as they are less soluble in water and not so abundantly absorbed — still, after some time standing it seemed their solubility was increased, probably from the secretion of some acid from the plant converting the oxide into salt soluble in water, consequently, more readily absorbed into the plant. That plants are capable of secreting an acid, or that water is capable of abstracting one, cannot be doubted, as the alkaline waters, after some time standing, would produce an acid effect on the tests." XI. — French School of Pharmacy. The object of this school is to teach all the sciences connected with Pharmacy, and to receive such apothecaries as in 4 trials prove that they possess the requisite knowledge for exercising this profession. Every candidate must produce certificates of his having studied for 8 years — of his having attained his 25th year, and must place in the hands of the treasurer the sum. of 1300 francs (<£54). Since 1830, a practical school has been formed, where the students admitted by competition are exercised in chemical and pharmaceutical manipula- tions. The school consists of a Director, a Joint-Director, 10 Professors, of which 4 are Joint- Professors, and a Treasurer. The chairs are Geiieral Chemistry, Bussy ; Organic Chemistry, Gaul- tier de Claubry; Pharmacy, Lecanu, Chevalier; Mineralogy, Pelletier; Natural History (Zoology), Guilbert; Toxicology, Caventou; Physics, Soubeiran; Natural History (Vegetable), Guibourt ; Botany (Organism and Physiology), Guiant ; Botany (Descriptive Botany), Clarion. The necessary examinations are two upon theory, one of which is upon the principles of the art, the other upon the botany and natural history of simple drugs ; the third and fourth on the practice of the art last for four days, and consist of at least 10 chemical or phar- maceutical operations, which the candidate must perform himself, describing the process, materials, and results. If at one of the ex- aminations he is not found competent he is remanded for three months. At the third trial the adjournment is for a year. The interval between each examination is a month. Unless two thirds of the votes are in his favour he is rejected. The examinations are public. In 1835 ninety apothecaries were received. The existence of this establishment then enables every apothecary in France to be a chemist ; while in England who ever heard of an apothecary being a chemist, or of doing any thing for the improve- ment of pharmacy ? This anomaly does not arise from the want of Scientific Intelligence, Sfc. 155 talent in our apothecaries, but from the miserable drudgery to which they are subjected (five year's apprenticeships), at the very time of life when they should be busily employed in the chemical and phar- maceutical laboratory under the eye of the scientific chemist. XII. — Death of Professor Geiger. This distinguished pharmaceutical chemist and professor of phar- macy at Heidelberg, died on the 19th of January last, in the 46th year of his age. He was the discoverer of conein and other alkaloids. By his death pharmacy has experienced a heavy loss. ^in.— Alpine Plants of Cote D'Or. The greatest elevation in this department is 617 metres (2024^ feet) above the level of the sea. The soil is calcareous and rocky. In the vallies the following plants are met with : — Swertia perennis ; Cin- eraria sibirica ; Polystichura thelypteris ; Schoenus nigricans ; ^QMn\xm carvifolia ; Gentia.n2i, germanica ; G. ciliata ; G. pneu- monanthe; Linaria alpina. On the sides and tops of the hills the fWlowing occur: — Daphne C7i C C3 > 3 -3 S^ ^ bo® • 11^ J.- i 13 bo fl ^ >. ® « <-> s: 2 rt^"^ ^ a s O) U bD JI ^ ® .S "o cu ^r OT > d k bD ;3 a> rS o ^ . 2.S o en bo r£3 P *f .Q 3 S « ® S S bo Cm > ® « ^ -g ^ g I ® . bDC3^>^^£§'- te *i H 3 S n, 1 ^ fe a f^^ w e8 .9 o tf t.D^ .2 ^ .a f^ .2 «^-S S 2i !3 i^ a=i'^ o bo"| St soh >>.a ^0^^ t3 ® C8 kT 9 C3 ^ *i- a±i -^ ZJ . Woa-^^ I « g C 22 "%- bo o ID ^ " «J W O >. QJ 22 _»!« bo b a. ^ ^ «= hl-^ ^ ^ °*^3 - ■g •5 ?. '^ ® > § ^ .. ^ .. ,>'t3 .■tS f^ tS 'O _f3 tJ ._«^ ^ g-S el b .5 0) .S .3 (3 a c a "^m rg 2 a a a a-^. S: th '^ "b! ■> 'fe ^ 'S '^ % !^ t>^ a''^ "5 13 -C 'rt "C 'C "C "C <» "S i3 ^ ^ 13 ® 13 "C « o'^.a-rrSs^ § g H g 2-S'5.a.aS O) JH . 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( Concluded from page 93.^ The week after the paper respecting the rotations of the electro magnetic wire was read, Davy communicated to the Royal Society a paper by Mr. Faraday, ** on Fluid Chlorine." This was followed by a successful attempt at liquifying several gases. The idea appears to have been suggested by Davy ; but to all who are acquainted with the ingenuity of Mr. Faraday, there can be little doubt that the suggestion to him was the utmost that was requisite. He succeeded in condensing sulphurous and sulphuretted hydrogen, carbonic acid, euchlorine, nitrous oxide, cyan- ogen and ammonia. In July, 1823, Sir Humphry made an excursion into Ireland and Scotland, in company with Dr. Wollaston, who also had acquired a taste for fishing, though at a late period of his life. From 1823 to 1826, he presented the following papers to the Royal Society :— " On the corrosion of copper sheeting by sea water, and on the methods of preventing this effect ; and on their application to ships of war and other ships." " Additional experiments and observations on the appli- cation of electrical combinations to the preservation of copper sheathing of ships and to other purposes." *' Further observations on the preservation of metals by electro chemical means." VOL. IV. M 162 Biographical Account of The Bakerian lecture for 1826, ** On the relation of electrical and chemical changes." These were important papers, having for their object the application of zinc protectors to the copper sheathing of ships, so as to prevent the latter from being corroded by the action of sea water. As the plan proposed appeared fraught with so many important consequences to ship owners, it was immediately applied to practice. Several vessels were sent on long voyages under the protecting influence of minute portions of zinc, equal together to ^J-^ or y^j^ of the surface of the copper. The copper was found to be completely protected — not a particle of it had corroded — but, in some instances, the accumulation of sea weeds and shell fish in consequence of the surface of the copper being covered with a coating of zinc (for such is the conse- quence of applying even a mere point of zinc to a sheet of copper in a saline solution) was so very great as actually to impede the sailing of the vessel. This appears to have been considered a fatal objection to the application of his impor- tant discovery — as it has never been acted on in more than two or three cases — although it is sufficiently obvious that methods could readily be contrived for removing accumula- tions of the nature in question from the bottom. If copper protectors were used, not only would a great saving accrue to the country but likewise to the interests of humanity. In June, 1824, Sir Humphry Davy made an excursion to Norway, and through Sweden, Denmark, Holstein and Hanover. During this tour he met with several distinguished men of science, whom he particularly notices. At Bremen he "dined with Dr. Olbers, and saw with much pleasure the telescope with which he discovered his two new planets, and met Gauss. Olbers gave us an excellent dinner, and is a most amiable and enlightened philosopher ; I spent a very pleasant day." *' I am rejoiced that I made the excursion to Altona and Bremen : it has given me a better idea of human nature ; for Schumacher, Olbers and Gauss appear to me no less amiable as men than distinguished as philosophers, and they have all the simplicity, goodness of heart and urbanity of manners, which ought to make us proud of their name and of the influence of intellect, and scientific pursuits upon the morals, the habits, and the Sir Humphry Davy, Bart. 163/ affections." Of Oersted he says, he ** is chiefly distinguished by his discovery of electro magnetism. He was a man of simple manners, of no pretensions, and not of extensive resources ; but ingenious and a little of a German metaphy- sician." " Berzelius was the worthy countryman of Scheele, and certainly one of the great ornaments of the age. Inde- fatigable in labour, accurate in manipulation, no one has worked with more profit. His manner was not distinguished, his appearance rather coarse, and his conversation was limited much to his own subjects," In 1826, Davy began to be threatened with symptoms of paralysis. He complained frequently of uneasy feeling and slight numbness of the right hand, and sometimes pain of his forearm, shooting up to the chest with occasional inor- dinate action of the heart, and occasional pain and weakness of the right leg. While delivering his last discourse to the Royal Society, at the anniversary dinner on St. Andrew's day, it was done with such effort that drops of sweat flowed down his countenance, and those who were near him were apprehensive of his having an apoplectic attack — and he was so unwell afterwards that he was unable to attend the dinner of the society. In December following, he was affected with a paralytic seizure, from which, however, he recovered as his strength improved. On the 22nd January, 1827, he had so far recovered as to be able to start for the continent^ in company with his brother. Notwithstanding the great severity of the winter he passed through France, and reached Ravenna in safety. In March, his brother left him for his official station at Corfu, considering that his health being so much restored he might be left with safety. There he amused himself with making observations on natural history — examining the torpedo — the double snipe — the generation of the eel. From Ravenna he retreated before the heats of summer to his former haunts among the eastern Alps ; his sufferings being very great at this period as the notices in his journal testify. His situation, however, was melancholy ; for he was in a foreign country, and had no person to exchange a word with ; moreover, he was ill, and had no physician if not to cure his complaints, at least to palliate his sufferings, M 2 164 Biographical Account of and sympathize with him amid the agonies of his disease. Yet, destitute of these comforts — nay, necessaries, as we might term them in his weakly state, his mind was sup- ported by a constant attention to the scenery around, and the noble pursuits of science. From Ravenna he proceeded to Laybach in Illyria, where he arrived on the 19th of April. During this journey, and his stay in this part of the country, he took much exercise in fishing and shooting. Amid these scenes he delighted to study the habits and nature of the various fishes which he killed. His journal, of which extracts are now pub- lished, is full of such references. But the fatigue which lie underwent appears to have acted otherwise than as a restorative, and his frequently registered expressions of sufiering exhibit too plainly what the philosopher was enduring. We find him incapable of enjoying the finest mountain scenery, such as he used formerly to delight in, and his expressions refer more frequently to the past than to the present. "Ah! could I recover," he exclaims, " any thing like that freshness of mind which I possessed at twenty- five, and which, like the dawning morning covered all objects, and nourished all things that grew, and in which they were more beautiful than in mid sun- shine, what could I not give ? All that I have gained in an active and not unprofitable life. How well I remember that delightful season, when full of power, I sought for power in others ; and power was sympathy, and sympathy was power; when the dead and the unknown, the great of other ages and of distant places were made, by the force of the imagination, my companions and friends ; when every voice seemed one of praise and love; when every flower had the bloom and odour of the rose ; and every spray or plant seemed either the poet's laurel or the civic oak, which appeared to offer themselves as wreaths to adorn my throbbing brow. But, alas, this cannot be!" Such are the sentiments expressed by Physicus in his " Last days of a Philosopher," but which are obviously the result of his own feelings. Towards the end of September his symptoms were aggra- vated. At Baden, he says, " The scenery is very beauti- ful, and for a person well, or becoming convalescent, it Sir Humphry Davy^ Bart, 165 would be a beautiful place ; but I fear my light of life is burned out." From Salzburgh, he had previously written to Mr. Gilbert, resigning the chair of the Royal Society. " I have gained strength," he observes, " under the most favourable circumstances, very slowly, and though I have had no new attack, and have regained, to a certain extent, the use of my limbs, yet the tendency of the system to accumulate blood in the head still continues, and I am obliged to counteract it by a most rigid vegetable diet, and by frequent bleedings, with leeches and blisterings, which, of course, keep me very low. From my youth up, to last year, I had suffered more or less from a slight hemorrhoidal affection ; and the fulness of the vessels, there only a slight inconvenience, becomes a serious and dangerous evil in the head to which it seems to have been transferred. I am far from despairing of an ultimate recovery, but it must be a work of time ; and the vessels which have been over dis- tended only very slowly regain their former dimensions and tone ; and for my recovery, not only diet, and regimen, and physical discipline, but a freedom from anxiety, and from all business, and all intellectual exertion, is absolutely required." He then concludes, by begging Mr. Gilbert to communicate his resignation to the Society. On the 6th of October, he returned to England in a very infirm state of health. He remained in this country till the last week of the following March. During a portion of this period, he paid two visits, one to a nobleman in Sussex, for whom he had a great regard ; the other to his friend Mr. Poole, in Somersetshire. But he did not enter into London society, to which he felt his strength inadequate. By the advice of his friends, he decided on again visiting the continent, and, accordingly, on the 29th of March, 1828, he left London, accompanied by Mr. Tobin (now Dr. Tobin), the eldest son of his early friend, Mr. James Tobin. Passing through Austrian Flanders, they crossed from the Rhine to the Danube ; and from thence to Donanworth, proceeding southward ; the season not being sufficiently advanced to enjoy the Alpine country, they travelled rapidly to Laybach, where they arrived on the 4th of May. Here, he amused himself in fishing, and pursuing his journey leisurely, he followed up the same amusement. From 166 Biographical Account of Aussee, in Styria, in June, he wrote his brother, ** Not- withstanding the long, severe, and distressing malady under which I still labour, I am not entirely without the hope of ultimate recovery, and the few pleasures that I retain in this very state of earthly purgatory have prin- cipally reference to the enjoyments and prospects of my friends, and I indulge in the idea that you are well and happy, and enjoying a life which I can say I only support, supposing that it pleases Omniscience to preserve me for some ends which I cannot understand, but which I trust belong to the great plan of goodness and mercy belonging to his divine mind." It was thus that he reconciled him- self to his sufferings. He next proceeded to Ischl, where he planned his " Consolations in Travel," a work which one cannot fail to admire, whether it be regarded as a piece of beautiful writing, or as the last efforts of a great and good man. At Wurzen he amused himself with writing a literary curiosity, viz., a romance, to which he affixed the title of *'The Last of the O'Donoghues, an Irish Story." It is a kind of historical piece, the scene, being Ross Castle on the Lakes of Killarney. On the 30th of August, he arrived at Lay bach. From thence, on the 6th of October, he went to Trieste expressly for the purpose of trying some experiments which he meditated on the torpedo. Here, through the attention of the English consul he was supplied with two recently caught torpedos. The result of this investigation con- stituted his last communication to the Royal Society. He sums up his views in it with regard to the different kinds of electricity. *' Common electricity is excited upon non- conductors, and is readily carried oflf by conductors and im- perfect conductors. Voltaic electricity is excited upon com- binations of perfect and imperfect conductors. Animal electricity resides only in imperfect conductors forming the organs of living animals, and its objects in the economy of nature is to act on living animals. Magnetism, if it be a form of electricity, belongs only to perfect conductors, and in its modifications to a particular class of them." His brother following up the investigation concluded that the electricity of the terpedo is not of a peculiar kind ; but the mode of its production he could not detect. He found that Sir Humphry Davy^ Bart, l87 the sensation imparted by this animal was similar to common electricity — that iodine was precipitated by its agency — and that its effect on the galvanometer and on steel in the spiral was similar to that of common electricity.* On the 31st October, he proceeded to Rome, where he arrived on the 18th November. Here he remained for several months in much the same state, till on the 20th February, he was seized with the severe attack which ulti- mately proved fatal. " That morning he felt better than usual, his pulse about 68, the tongue clean ; the ordinary functions of the body well performed. After breakfast he had sat some time dictatingan addition to the sixth dialogue. When he had finished it he attempted to rise to go into his bed-room, which was adjoining, but found that he could not stand, and that he had lost all power over his limbs, without pain of head or vertigo or loss of power of intellect, accompanied merely by a feeling of sickness of stomach. Medical aid was immediately had ; leeches were applied to the head as if the brain had been affected ; and a lowering (or as it is called antiphlogistic) plan of treatment was pursued, but with no good effect. He spent the night very restlessly, and the following morning the right side was quite powerless and the stomach much deranged." He now gave up all hopes of recovery, and wrote to his brother at Malta to come and see him before his death. Dr. Davy arrived at Rome on the 16th March. The account of his feelings, on this occasion, are highly affecting. " I shall not attempt to describe my feelings on receiving his last letter, making known to me the illness of a brother who had acted the part of a father to me; whom I regarded as a brother, a teacher, and most kind friend ; and to whom I necessarily owe very much of what I most valued in life. My anxiety naturally increased the nearer I came to Rome. In vain I sought for fresh letters and additional information at Naples. When I entered Rome I knew not where to find him ; for his address in that city was not sent. I in vain went from one hotel to another, making inquiries, without being able to hear any thing of him. I fortunately recollected that his friend Morichini was a physician, and a resident in Rome. He was easily found, and presently I * Records, vol. i. 306. 168 Biographical Account of had a comfortable message from him, that my brother that morning was rather better, accompanied with a direction to his lodging ; and in a few minutes I was by his bed side. Never shall I forget the manner in which he received me ; the joy which lighted up his pale and emaciated counte- nance ; his cheerful looks and extreme kindness ; and his endeavours to sooth a grief which I had not the power of controlling on finding him so ill, or rather at hearing him speak as if a dying man who had only a few hours to live, and who wished to use every moment of such precious time. With a most cheerful voice, a smile on his counte- nance, and most warm pressure of the hand, he bade me not be grieved, but consider the event as a philosopher." During their stay at Rome, Lady Davy arrived from England, bringing with her a copy of the second edition of " Salmonia," which gave him very great pleasure. His strength gradually improved under the lovely Italian climate, and by the 30th of April he was able to quit Rome for Geneva, for the purpose of removing from the increasing heat to a cooler climate. The party advanced by Florence to Genoa, where they arrived on the 12th of May. On the 28th they arrived at Geneva. Here he appeared to have improved, for on his arrival at the inn of La Couronne he merely reclined on a sofa, and occasionally walked to the window and looked out upon the lake, and ** expressed a longing wish to throw a fly, as he had been before in the habit of doing, on his favourite Rhine. Here he learned the death of his old friend Dr. Thomas Young." Dr. Davy says, " I was not present when Lady Davy made the com- munication to him, but when I returned I saw him affected, and he told me how deeply he had been affected by it even to profusion of tears, and in a manner that was almost unaccountable. In a short time he recovered his composure, and conversed on indifferent matters. At five o'clock he dined at table and made a tolerable dinner. After dinner he was read to according to his custom. At nine o'clock he prepared to go to bed. In undressing he struck his elbow against the projecting arm of the sofa on which he sat. The effect was very extraordinary — he was suddenly seized with a universal tremor — he experienced an intense pain in the part struck — and a sensation he said as if he Sir Humphry Davy, Dart. 169 were dying. He was got into bed as soon as possible ; the painful sensations quickly subsided, and in a few minutes were entirely gone." No appearance of injury could be detected on the arm. He took an anodyne draught, and about half-past nine expressed a wish to be left alone. At half-past two he was insensible, and at 3, a. m., on the 29th May, 1829, he died. His funeral took place on the 1st June, and was attended by the literary and scientific men of Geneva. His remains were deposited in the burying ground of the city, without the walls, and close to the grave of Professor Pictet. The precise cause of the complaint of which he died was never ascertained, as he made his brother promise that he should not open his body ; being of opinion, that it was possible for sensation to remain in the animal fibre after the loss of irritability. He had also a great horror of being buried alive, and desired that his interment should not take place till after ten days ; but it was found impossible to comply with his request, as it was contrary to the law of Geneva, and as signs of decomposition speedily shewed themselves. It is remarkable, that the same year deprived England of three of her most distinguished philosophers. Young, Wol- laston and Davy. The first was Foreign Secretary and the latter Secretaries of the Society — and all three foreign associates of the first class of the Institute of France. Such is a sketch of the life of one of England's greatest ornaments. He was of middle stature, about five feet seven inches high, but appeared shorter perhaps from his compact and stout make ; his countenance was very expressive — his voice was full toned and melodious — which is rather re- markable as he was destitute of a musical ear. He possessed very strong feelings; of a kind disposition with those whom he formed friendships, but latterly of an extremely irritable temper, and disagreeable bearing. He was always of a jealous disposition, which appears to have been encouraged by the fear that he should be anticipated in any of his dis- coveries ; and, unfortunately, he too often displayed by his actions what were the feelings of his mind. To point out the weaknesses in the character ought to be particularly attended to, by the biographer, for, unless this 170 Dr. Thomas Thomson* s Experiments is done, the grand end of biography is marred. But, while the imperfections of the subject of our memoir have been exhibited, we trust that the great benefits he conferred upon science have been detailed in such characters as may render them worthy of imitation ; and thus, though he no longer resides among us, that rivals may be incited to start from the point where his labours ceased, and to act in sub- servience to the growing wants of society. Article II. Experiments on the Absorption of Air hy Water. By Thomas Thomson, M.D., F.R.S.L. & E., &c., Regius Professor of Chemistry in the University of Glasgow. Not being aware of any direct experiments upon the subjects mentioned in the title of this paper, I amused myself, during the early part of the present summer, in making a few trials to satisfy myself whether the opinions at present entertained on these subjects were entitled to confidence. I shall state my experiments on each of the different subjects in order. I. — Of the quantity of Air contained in Clyde water. The city of Glasgow is supplied with water pumped out of the river Clyde, and conveyed to reservoirs in the higher parts of the town, from which it is conveyed in pipes to every house. As one of these pipes supplies my laboratory, I have only to turn a stock cock to obtain as much river water as I have occasion for. 1. I filled a retort, the belly of which held 168 cubic inches, and its throat and beak 75 cubic inches more, with river water, plunged the beak into a water trough, and placed a small inverted jar full of water over the extremity of the beak. I then boiled the water till it ceased to give out any air. I collected 5*25 cubic inches of air. Baro- meter at 29'5 inches. Thermometer 53°. In this experiment 168 cubic inches of water gave out 5*23 cubic inches (making the requisite corrections) of air, supposing the barometer at 30 inches and the thermometer at 60°. The 75 cubic inches which filled the throat and beak on the Absorption of Air by Water. 171 of the retort became hot, and no doubt gave out a little air ; but not much ; because as soon as the water in the retort began to boil briskly, the water in the throat and beak was driven out by the steam, and never boiled at all. Thus, it appears that 100 cubic inches of Clyde water contain 3*113 cubic inches of air. The experiment being repeated in precisely the same way, the product of air was so nearly the same that it seems unnecessary to state the particulars minutely. II. — Composition of the Air thus extracted. I let up 100 volumes of this air into a small jar, filled with water and standing over the water-trough, and put into it a stick of phosphorus of such a length that it reached from the bottom to the top of the jar, and traversed all the air. In 24 hours the bulk of this air was reduced to 71*48 volumes of azotic gas. Hence, the air extricated from the water was composed of 71*48 volumes of azotic, and 28*52 volumes of oxygen gas. The air extricated during the second experiment, analyzed in the same way, was composed of 70*32 volumes of azotic, and 29*68 volumes of oxygen gas. If we take the mean of these two analyses, we get the constituents of the air extracted from Clyde water by boiling as follows : Volumes of azotic gas . . . 70*9 Volumes of oxygen gas . . . 29* 1 100*0 III. — Alteration produced on this Air when left standing on the water-trough. 1. The 5*26 cubic inches of air extracted by boiling water from the Clyde, were put into a small cylindrical glass capable of holding 1 1 cubic inches, and left inverted over the water trough. Every 24 hours 1 cubic inch (or 100 volumes) of this air was taken out, and left till next day witli a stick of phosphorus passing through it. The 172 Dr. Thomas Thomsons Experiments following table shows the composition of the air after standing over the water. Azotic. Oxygen. 1. Fresh extracted of . 71-48 + 28-52 2. After one day . . 74*43 + 25-57 3. After two days . . 75-38 + 24-62 4. After three days . . 77-51 + 22-49 5. After four days . . 80*97 + 19-03 2. The 5*25 cubic inches extracted from the second quantity of water by boiling was treated in the same way; excepting that the 11 cubic inch jar containing the air, instead of standing open on the water-trough, was corked tight. The result was as follows : Azotic. Oxygen. 1. Air newly extricated composed of 70-32 + 29-69 2. After one day 72-5 + 27-5 3. After two days 73-44 + 26-54 4. After three days 73-35 + 27*65 5. After four days 77-43 -h 22-57 Here, as in the first case, the oxygen was absorbed more rapidly than the azotic gas ; but the rapidity of this absorption was somewhat diminished by corking the glass in which the air was kept. IV. — Alteration produced on Common Air by leaving it standing in a glass vessel inverted on the water-trough. Curious to know whether a similar diminution in the quantity of oxygen in common air would take place when left standing over the water trough, as had taken place in the preceding experiments with air extricated from water by boiling, I put ten cubic inches of common air, collected at the window of my laboratory on a windy day, into a cylindrical glass jar and left it standing inverted over the water-trough, analyzing every day one cubic inch by means of phosphorus, till the whole was exhausted. The follow- ing table shows the result of these analyses. Azotic Oxygen. 1 . After standing 24 hours . 79-47 H- 20-53 2. After two days .... 79*27 + 20-73 3. After three days . . . lost 4. After four days . . . . 79*65 + 20*35 Azotic. Oxygen. . . . 79-65 + 20-35 . 82-99 + 17-01 . 80-71 + 19-29 . 80 + 20 . 80-84 + 19-16 . . 82-26 4- 17-74 on the Absorption of Air by Water, 173 5. After five days . 6. After six days . 7. After seven days 8. After eight days 9. After nine days . 10. After ten days . On the ninth day, after analyzing the gas, I dissolved some sulphate of iron in the water-trough. This is the rea- son of the greater proportion of azotic gas found in the last cubic inch of the air, which was analyzed on the tenth day. If we compare these experiments with the former ones, we must be struck with the great difference between them. The air extracted from water by boiling is much richer in oxygen than common air, containing rather more than 29 per cent., while common air contains only 20 per cent, by volume. But this excess of oxygen diminishes rapidly ; so that after four days it does not contain more than common air does. Common air, on the contrary, may be left upon the water- trough for ten days without undergoing any sensible alteration in its composition. Indeed, I left nine cubic inches of air in a tube standing inverted over water, from the first of May to the 25th of that month, and found its constituents unaltered. If we take the mean of the constituents of air from the preceding table, leaving out the last term, because the sul- phate of iron had increased the quantity of oxygen absorbed, we obtain Azotic gas . . 80-32 volumes. Oxygen gas . . 19-68 ,, 100-00 Now this diff'ers very little from the composition of air. If we analyze air without removing previously the carbonic acid gas and the moisture which it contains, we always find the volume of its oxygen below 20 per cent. V. — Absorption of Air by Water. To determine the absorption of air by water I boiled a quantity of distilled water for a quarter of an hour, and 174 Dr, Thomas Thomsons Experiments filled with it, while boiling hot, a small cylindrical glass jar: the capacity of the jar was about 11 cubic inches. I determined what bulk of the boiling water would when cold constitute 10 cubic inches. This quantity was put into the glass, and the rest of it being filled with mercury it was placed inverted on the shelf of a mercurial trough. As soon as the water was cold, a cubic inch of air was let up into the glass, and the whole was left one day, then two days, then three days, then four days, and at last eight days, in order to see how much of it would be absorbed by the water during that time. The following table exhibits the residue of the air, the original cubic inch being considered as divided into 10,000 parts : Residue. 1st trial . . . . 0-8709 2nd „ . . . „ 0-9062 3rd „ . . . . 0-7207 4th „ . . . 0-8659 5th „ . . . . 0-8673 6th „ . . . 0-8566 7th „ . . . . 0-8069 8th „ . . . . 0-8178 9th „ . . . 0-7990 0th „ . . . . 0-7672 Mean . . . . 0-8278 I was very much surprised at the great discordance in these results, as every experiment was made exactly in the same way, and the air was always collected from the outside of the window of my laboratory at the commencement of each trial. The mean absorption in these trials by 100 cubic inches of newly boiled water is 1*722 cubic inches of air. The greatest absorption by 100 cubic inches of water was 2*793 cubic inches, and the least 0-938 cubic inches. But it has been stated above that by boiling 100 cubic inches of the water of the Clyde, 3-1 13 cubic inches of air could be extricated. The mean absorption found amounts only to about the half of this quantity. The greatest absorption falls short of it by almost -i^th, while the smallest absorption amounts only to about a third of it. It is obvious from this that the absorption of air by water is a very slow process. on the Absorption of Air hy Water, 175 VI. — Alteration produced in Air hy standing ovefi' distilled and newly boiled Water. We have seen that when air is left for 25 days over common river water it undergoes no sensible alteration in its composition. But the case is very different when air is left in contact with newly boiled distilled water. I analyzed the residual air in the ten trials exhibited in the last section by leaving it in each case for 24 hours over the water-trough with a stick of phosphorus in contact with it. The dimi- nution of volume was considered as the bulk of oxygen which it contained. The proper corrections being made for alterations in the barometer and thermometer which had taken place during the interval, the following table exhibits the volume of azotic and oxygen gases contained in these residues : Vol. of Oxygen. Vol. of Azotic gas. 1st 10-16 76-93 2nd 16-72 73-90 3rd 7-71 64-36 4th 6-22 80-37 5th 11 -51 75-22 6th 13-44 72-22 7th 13-37 67-32 8th 13-42 68-36 9th 10-48 69-42 10th 4-59 72-13 But, in order to be able to judge more accurately of the constitution of this residue, we shall suppose it to amount in each case to 100 volumes, and set down the number of volumes of oxygen and azotic gas of which it is composed : Vol. of Oxygen. Vol. of Azotic gas. 1st 11-67 88-33 2nd. .... 17-35 82-65 3rd 10-70 89-30 4th 7-18 92-82 5th 13-27 86-73 6th 15-70 84-30 7th 16-57 83-43 8th 16-41 83-59 9th 13-12 86-88 10th. . . . • 5-99 94-01 Mean 12-80 87-20 176 Dr. Thomas Thomsons Experiments The same diversity appears in the constitution of the residue as in the amount of the absorption. But the mean derived from the ten trials is, that the air after standing from 1 to 8 days on newly boiled water is composed of, 12*8 volumes oxygen gas, 87*2 volumes azotic gas. It is obvious from this, that a greater quantity of oxygen has been absorbed than of azotic gas, for the air before it was placed over the water (leaving out of view the carbonic acid and vapour which it contained) was composed of, 20 volumes oxygen, 80 volumes azotic gas. As the original volume of air was one cubic inch, which we suppose divided into 100 parts we will obtain the volume of oxygen and azotic gases absorbed in each trial by sub- tracting the volumes of oxygen in the table page 175 from 20, and the volumes of azotic gas from 80. The following table shows the result, and exhibits the volume of oxygen and azotic gas absorbed in each trial : Vols, of Oxygen absorbed. Vols, of Azotic gas absorbed. 1st 9-84 3-07 •^ 2nd 3-28 6-10 3rd 1^-29 15-64 4th 13-78 0 5th 8-49 4-78 6th 6-56 7-78 7th 6-63 12-68 8th 6-58 11-64 9th 9-52 10-58 10th 15-41 7-87 The want of coincidence in these trials is very surprising. But the mean of the whole is that ten cubic inches of water absorbed, •0924 cubic inch of oxygen, •0801 cubic inch of azotic gas. So that 100 cubic inches of water would absorb, 0*924 cubic inch of oxygen, 0*801 cubic inch of azotic gas. 1*725 on the Absorption of Air by Water. 177 100 volumes of the air thus absorbed would consist of, 53*57 volumes oxygen, 46-43 volumes azotic gas, 100-00 But, it has been shewn in the first part of this paper, that the air extricated by boiling from the water of the Clyde was composed of, 29*1 volumes oxygen, 70*9 volumes azotic gas. 100-0 It follows from this, that the air extricated from water by boiling differs essentially in its composition from the air absorbed by water; the quantity of oxygen in it being very much diminished. Let us suppose that water has absorbed a hundred volumes of air. They will consist, as appears from the preceding statement, of, 46*43 volumes of azotic gas, 53*57 volumes of oxygen. But, when these 100 volumes are extricated from water by boiling, they are reduced to 64-02 volumes, which con- sist of, 45*39 volumes of azotic gas, 18*63 volumes of oxygen. Two- thirds of the original oxygen gas absorbed by the water disappear, and only one-third remains. Doubtless this portion of oxygen which disappears is employed in the respiration of fishes, (if such an expression may be per- mitted,) and for various other important purposes of which we are at present ignorant. If any reliance can be placed in these statements, it will follow that the difference between the absorbability of oxygen and azotic gas by water, is much greater than has hitherto been supposed. Oxygen must be about three times as absorbable by water as azotic gas. If we compare the quantity and constitution of the air extricated from water by boiling, with the constitution of the air absorbed by newly boiled water, we shall find that 100 volumes of water absorb, VOL. IV. N 178 M. E.Miisckerlich on 2*21 volumes of azotic gas, 2*65 volumes of oxygen. 4-86 Now, let the absorbability of azotic gas by water = x and that of oxygen gas = y. We have from the constitution of the atmosphere, ^ = 2-21. Hence a: = 2-76. o I = 2-65. Hence y = 12-25. So that oxygen gas is about 4i times as absorbable by water as azotic gas. But, as two-thirds of this oxygen gas absorbed by water disappear, the absorbability of oxygen gas appears only to be to that of azote as 4*5 to 2*76, or not so much as double. Article III. On Manganic and Hypermanganic Acids, on Hypercldoric Acid, and the Salts of these Acids. By E. Mitscherlich.* ScHEELE first observed a part of the phenomena, which, as I shall immediately show, are produced by two acids formed from manganese ; and after him chemists of eminence have repeatedly turned their attention to the subject. Chevreul, Chevillot and Edwards, Forchhammer, Fromherz and Un- verdorben, have added more or less interesting facts to those previously known, although they have by no means exhausted the subject. These compounds, however, would unquestionably have been long ago completely investigated, had not the great difficulty of obtaining the pure acid in sufficient quantity rendered their examination almost an impossibility. They are decomposed very easily by a great number of circumstances; their solutions cannot be filtered, nor their crystals laid upon paper, because they are instan- taneously decomposed by organic substances. Very distinct crystals, which I obtained of manganate of potash, enabled me to determine their shape, and as it was found to agree in every respect with that of the chromate, seleniate, and sulphate of potash, this circumstance, which • PoggendorflTs Ann., xxv., 287. (The publication of this interesting paper is rendered necessary to illustrate that of Dr. Clark, printed in Records, vol. iii. 43:3, and vol. iv.43. — Edit.) Manganic and Hypermanganic Acids, Sfc, 179 is particularly interesting in the elucidation of the con- nexion of the crystalline shape of bodies with their composi- tion, induced me to investigate more closely these acids and their compounds. I. — On the action of Potash on the Binoxide of Manganese. When equal parts of potash and binoxide of manganese are ignited together, and the ignited mass treated with water, a green solution is obtained, which contains in solu- tion, carbonate of potash, caustic potash, and a compound of potash with manganese in a higher degree of oxidation, while a brown powder remains undissolved. Oxygen is absorbed when the mass is ignited in contact with the air, as Edwards and Chevillot have already shewn. But the green compound may be obtained equally well, when the binoxide of manganese is ignited with potash in a retort shut up from the air. Thus 10 grammes of binoxide of manganese, heated with potash without the access of air, and treated with water, gave a solution, which, when the acid was decomposed, and the manganese precipitated and ignited, yielded 1 gramme of the red oxide (oxidum man- ganeso-manganesicum.) In this case, the higher degree of oxidation of the man- ganese is produced in the same manner in which the brown oxide of lead is formed from red lead, when the latter is treated with nitric acid, and the brown residue which is left, when the green compound is dissolved, consists of hydrated sesqui and binoxides of manganese, but whether mixed or chemically combined, I cannot venture to decide. The manganic acid is formed by a part of the binoxide giving up a portion of its oxygen to the remainder, by which it is changed to sesquioxide, but the quantity of manganic acid formed, shows that a portion of the binoxide remains undecomposed. If we pour off the deep green solution, after allowing the brown insoluble portion to subside, and allow it to evaporate over sulphuric acid, under the exhausted receiver of an air mmp, we obtain beautiful pure crystals of a green colour, lixed with abundance of crystals of hydrate and carbonate [of potash. These crystals must belaid on porous tile or slay, which absorbs the moisture without producing decom- N 2 1 80 M. JE, Mitscherlich on position. If the solution be allowed to evaporate in contact with the atmosphere, red crystals, the composition of which, I shall attend to afterwards, may be formed by the action of the carbonic acid of the air. If the green crystals be treated with water, a red solution is obtained, which, by evaporation, yields red crystals. The green crystals consist of manganate of potash, which is isomorphous with sulphate of potash, while the red have the same form as the perchlorate of potash. Accurate analyses have shown that both the perchloric acid and the highest degree of oxidation of manganese, contain 7 propor- tions of oxygen. It appears to me, therefore, to be conve- nient to denominate that degree of oxidation of manganese which corresponds with sulphuric, selenic, and chromic acids, manganic acid, while the highest degree of oxidation of manganese may be called hypermanganic acid, and that of chlorine hyperchloric acid, following the nomenclature of Gay Lussac with respect to %/>o-sulphuric acid.* II. — Manganic Acid and its Salts. I had tried many ways of analyzing manganic and hyper- manganic acids, when at last, I met with one as accurate as it was easy. It depends on the fact, that hypermanganic acid begins to decompose at the temperature of 86° F., and at 212° is completely changed into binoxide and oxygen gas, and as the manganate of potash when treated with water changes into hypermanganate of potash and binoxide of manganese, the compounds of manganic acid may be ana- lyzed the same way. I add to the manganic or hyper-man- ganic acid, sulphuric or nitric acid, collect the oxygen in a graduated tube over quick-silver, and reduce the gas obtained to what it would be at 32° F. and when the barometer stands at 30 inches. 0*705 gramme of manganate of potash, treated with dilute nitric acid, and boiled till the solution became colourless, gave 58*9 cubic centimetres dry oxygen gas, which is equivalent to 0*0844 gr. by weight. 100 parts of the salt had, therefore, given out 8*7 of oxygen when treated with nitric acid. • In this investigation I have been greatly aided in the preparation of tlie sub- stances by my assistant, M. WolfF, a very skilful pharmaceutist. Manganic and Hyper manganic Acids, Sfc. 181 1*204 gr. of manganate of potash, decomposed by muriatic acid and precipitated by carbonate of ammonia, yielded 0*459 gr. ignited red oxide of manganese ; and the liquid evaporated to dryness and heated to redness, gave 0*882 chloride of potassium ; or 100 grains would have given 46*34 potash, and 38*12 red oxide of manganese. These 38*12 parts of red oxide are equivalent to 44*30 of the binoxide, containing 15*95 of oxygen. Therefore, the oxygen extricated by the action of the nitric acid, is nearly half that contained in the residual manganese. Now, 46*34 potash contain 7*85 oxygen, that is half that of the binoxide of manganese, or ^ of that in the manganic acid. If we calculate from this the composition of the manganate of potash, we find it to be composed in 100 parts of 47*37 potash, 52*63 manganic acid. When 52*63 parts of manganic acid are converted into binoxide of manganese, 8*03 parts of oxygen ought to be extricated ; the increase of {q in the result of the experi- ment is occasioned by the extreme facility with which the salt is decomposed, by which the potash is diminished in quantity. The hydrated binoxide of manganese has already been discovered by Berthier, and prepared by various methods, but it was not known that it could be prepared by the decomposition of manganic and hypermanganic acids. When prepared from these acids by nitric acid, its colour is so deep brown as to appear almost black, but when prepared by sulphuric acid it is somewhat lighter. An unknown quantity of this oxide was ignited in a retort and the oxygen extricated was collected ; this (the barometer standing at 30 inches and the thermometer at 32°) measured 46*2 C. C, or 0*06618 grammes. I could not succeed in converting it into red oxide in the retort, but when heated strongly in a platinum crucible, it gave out 0*049 gr. of oxygen, and became red. The red oxide obtained, weighed 0*954 gr. To be more certain of its amount, it was treated with sulphuric acid, and the solution evaporated to dryness and ignited. The sulphate of manganese weighed 1*8363 gr., corresponding to 0*9521 gr. red oxide. 0*954 gr. red oxide of manganese are obtained by igniting 1*083 gr; binoxide, as they contain 0* 129 gr. oxygen. According to the experiment, the loss in the quantity employed was 0*115 gr. 182 M. E. Mitscherlich on This discrepancy, which amounts to somewhat more than one percent., is caused by the difficulty of analyzing the binoxide ; the experiment, however, clearly shows that the powder examined was binoxide of manganese. In another experiment, 0*6525 gr. dried hydrous binoxide of manganese gave 0-4735 gr. red oxide, which is equivalent to 0'538 gr. binoxide. Consequently 0*1145 gr. water, which contain 0'1009 gr. oxygen, are combined with 0'538 gr. binoxide of manganese, containing 0*194 oxygen. The oxygen of the water, is therefore, to that of the binoxide of manganese as 1 to 2. The binoxide of manganese does not give off the last portion of its water till the oxygen begins to be extricated. I have in vain tried to find a method of distinguishing the sesquioxide and the binoxide of manganese from one another, easier than by ignition. If the hydrated binoxide be treated with a solution of sulphurous acid in water, the greater part of it is converted into the sulphite of man- ganese, but a portion, sometimes greater and sometimes smaller, becomes sulphate of manganese. I have estimated the quantity of both, the one as sulphite the other as sul- phate of barytes, and from the quantity of each have calcu- lated the quantity of oxygen supplied to the sulphurous acid. By this method also, I have ascertained that the binoxide of manganese formed by the decomposition of the manganic and hypermanganic acids, is pure, containing no sesquioxide, as the latter would have oxidized only half as niuch sul- phurous acid. This method of examining the binoxide is still more difficult than its estimation by ignition. It had already been observed by Heeren, that sulphuric acid is formed when the native binoxide is treated with sulphurous acid. The crystals of the manganate of potash have the same secondary faces, and the same composition as the sulphate, seleniate, and chromate of potash, and show even to the most trifling minutiae the same modifications with respect to the size of the faces. On account of the facility with which the manganate of potash is decomposed, no other salts of manganic acid can be made by means of it. Caustic soda, fused with binoxide of manganese, yields manganate of soda, which, however, is too soluble to be freed from the carbonated and caustic soda by crystallization. Nitrate of barytes fused with Manganic and Hypermanganic Acids, Sfc. 183 binoxide of manganese, yields manganate of barytes. If, to a solution of the hypermanganate of barytes a solution of barytes be added, and the liquid be allowed to stand a long time in ajar, which it about half fills, then green crystals separate themselves, which are manganate of barytes, and which, like the sulphate of barytes, are insoluble in water. III. — Hypermanganic Acid and its Salts. If manganate of potash be treated with a solution of caustic potash, it dissolves without decomposition, and if the solution be evaporated in vacuo we obtain again crystals of manganate and hydrate of potash, which latter, under the air pump, may be obtained of great beauty. If, on the contrary, the manganate of potash be dissolved in water, it is decomposed; a brown crystalline precipitate falls down, which appears to be a combination of binoxide of manganese with potash. This precipitate is decomposed when it is washed, the water dissolving the potash, and converting it into pure hydrated binoxide. The solution has a deep red colour, and if it be evaporated till crystals appear on the surface, and the solution poured off, from any precipitate which may have appeared into a warmed dish, then beau- tiful deep red crystals are obtained when it cools. The same thing happens when a solution of manganate of potash is exposed to the air so that it can attract carbonic acid ; as soon as the excess of alkali is saturated the solution becomes red, and at the same time a precipitate appears. Hence, we sometimes obtain a mixture of these red crystals during the preparation of manganate of potash, if the solu- tion during evaporation be so situated that it is exposed to much carbonic acid. fTo be continued. J Article IV. On some Methods of Astronomical Observation. By William Galbraith, A.m., Teacher of Mathematics, Edinburgh. {Continued from page 135.) Ill* — On the method of finding the value of the divisions on the scales of levels applied to altitude and azimuth circles, registering observations, h)C, 184 Mr. William Galbraith, on some All the more usual astronomical instruments have a level applied to them so as to insure the verticality of their axis, or to make the necessary allowance for their deviation from it. The scale of the level is so graduated as to show single seconds, or some multiple of the second, and reads most conveniently from a central zero. In those instruments that revolve in azimuth, which all the smaller, and more especially the portable circles do, (and even the large eight feet circle at Dublin, though provided with a plumb line rather inconveniently situated, and the most accurate, per- haps in principle, of any hitherto constructed,) the obser- vations are repeated several times in pairs near the meridian, reading the divisions at both extremities of the air bubble on the scale of the level each time along with the verniers or microscopes. When there are three verniers and about six observations made, it is advantageous to have a simple and convenient method of registering the observations, taking the means, and allowing for the effects of the level. The value of the divisions of the level is generally got from the maker, or it may be readily found by an instru- ment called the level trier, constructed expressly for this purppse. If the observer has not had these communicated to him, or if he wishes to satisfy himself with regard to the accuracy of the values given to him along with the instrument, he may either ascertain these by the circle itself, when the verniers or reading microscopes are competent to the purpose, or he may have recourse to the following methods, which, in the course of my experience, I have found very convenient. 1 . Put up the usual levelling rod of the best construction truly vertical, at such a distance from the circle as may be most convenient, though somewhat considerable. 2. Set the level exactly in the direction of two of the feet screws, or one perpendicular to the line joining the other two, when there are three ; clamp the verniers, and direct the intersections of the cross wires of the telescope to the mark on the sliding vane, which must be moved up or down till an exact coincidence takes place. 3. By turning one of the feet screws cause the bubble to move through a given number of the divisions of the scale, k Methods of Astronomical Observation, 185 comprehending those usually employed in recording obser- vations, while at the same time the sliding vane must be moved till its mark again coincides with the intersection of the cross wires in the telescope, still clamped to the circle, and the number of divisions on the rod which it has passed over to thousandths, or, at least hundredths of a foot, by this motion must then be recorded. 4. Measure the horizontal distance with great care between the centre of the circle and the levelling rod. These afford data for computing trigonometrically the value of the divisions of the scale of the level. 5. To investigate formulae for this purpose, let R" be the length of an arc equal to the radius in seconds, D the horizontal distance, d the distance passed up or down by the vane, A" the arc in seconds subtended by d, at the distance D then by the principles of trigonometry, A' = 5:^ (1) If L be the length of a given number of seconds, a" on the scale of the level, and r the length of the whole run in the same measure as D and d, ^ = R" X d ^^^ Indeed, if any four of the fiye quantities, D, d, r, a", and L be known, the value of the fifth may be found by trans- forming the preceding equation, thus : If n be the number of divisions in the run of the level, « = B-^n • • (4) If P be the radius of curvature of the level, R" X L R " X r ,_. p = ^^^ = -^^ (^) Examples for the use of these formulae. 1 . The cross wires of the telescope of an astronomical instrument, at the distance of 250 feet from a levelling rod, moved over two inches in a run of the bubble through an inch and a half, by turning the feet screws in the direction 186 Mr, William Galbraith^ on some of the level and rod, what was the value of the whole arc A" passed over by the bubble, and the length L, of a division of a" (10") on the scale of the level? _ R" X 6/ 206264"-8 x 2 ^__, By formula (1) A" = — g — = gQQQ = 137 bl , ^, Dx«"xr 3000x10x1-5 ^ ^^f, . By formula (2) L= ^ ^ ^ = 2062648x2 ^^'^^^ ^"^ From this last formula, a scale may be readily adapted to a level. 2. Let the length L of one of the divisions of the scale of a level be one-twentieth of an inch, the run of the bubble two inches, the distance c?one inch and a fifth, and D five hundred feet, required a", the value of one division of the scale in seconds? -D r 1 /ox '/ R"xLx6? 206264"-8x 0-05x1-2 ,..^o Byformula(3)a=-3^^ = q^^^^^ =1 ^^ 3. At the distance D = 90*6 feet, the vane of a levelling rod passed over 0*06 of a foot in a run of 25 divisions of the level, what was the value a' of one division of the scale, and the radius of curvature of the level, L being one-tenth of an inch ? ^ „ . rAs " R" X ^ 206264"- 8 x 0-06 .. ^ By formula (4) a =^=r = — — — — = 5 -5 ^ D X n 90-6 x 25 By formula (5) , = -— ^ = ^^-- =^.^^^0x12 " 206264"-8 oio^^ . — ^^- — = 312-5 feet. 660 This result &''b is nearly the value of one division of a level attached to a six-inch travelling circle of Captain Kater's construction, made by Robinson. It is obvious, that the same method may be applied to determine the value of the divisions of a level belonging to larger instruments when required, and it is susceptible of very considerable accuracy when sufficient care is taken in performing the necessary operations. II. After having determined the value of the divisions of the scale of a level, it is next proper to adopt a simple and ready method of applying its effects to observations. Let e be the eye end of the telescope next the observer, 0 the object end, a the value of one division of the level in Methods of Astronomical Observation. 187 seconds, n the number of observations, and I their effect when applied to the zenith distance. ^ = '^^' («) The sign must be changed when applied to the altitude. III. When three or more verniers are applied to a circle, and the observations are repeated and read each time, the mean result will be readily determined by the following formula in which S r is the sum of the readings of all the verniers or microscopes, n the number of observations, V the number of vierniers, and m the mean value of the whole. m = ^ (7) nv These formulae will apply with ease and certainty to any case likely to occur in practice, and are more simple than any I have seen. IV. The case to which they are now to be applied is one of a series of observations made by a small circle of Captain Kater's construction, to determine the obliquity of the ecliptic at the late summer solstice, at Edinburgh, in latitude 55° 57' 15"-67 N. It may seem to be an attempt much beyond the powers of so small an instrument, one of six inches diameter, fur- nished with three verniers, each showing 15" and a level, indicating by each division only to the accuracy of b'-b. Yet, the correctness of the final result, which differs from Bessel's by about 2'^, and from mine, obtained by a com- parison of the late observations made at Greenwich, with those of Bradley, reduced with the best tables by 1"^, shows how much may be accomplished with moderate means. With what pleasure would modern astronomers have contemplated the observations of Hipparchus and Ptolemy had they been made with such precision ! To determine the obliquity of the ecliptic in the most accurate manner, the sun's declination (daily if possible), near the solstices, must, it is well known, be observed carefully for some time, and the results, by means of appropriate formulae or tables, are reduced correctly to the moment of the solstice computed from the best solar tables, or obtained from corresponding observations. 188 Mr. William Galbraith, on some All the formulae* with which I am acquainted, and most of the tables are adapted to the sun's distance from the solstice reckoned on the ecliptic, or the difference between the sun's longitude, at the time of observation, and 90° or 270°. Now, by those possessing an ephemeris giving the sun's longitude at apparent noon, with differences to reduce to any given meridian, this is readily found. The sun's longitude, however, in the new Nautical Almanac for 1834, and succeeding years, is given to mean noon without dif- ferences or proportional parts, consequently, the distance of the sun, at apparent noon, from the solstice is not so easily obtained in terms of the longitude, as in those of the right ascension. Besides, in an observatory, the sidereal time is generally known by observation, and, therefore, on the whole, arguments depending on the right ascension are the more convenient for obtaining the reduction of the sun's observed declination to the solstice. A very convenient formula for this purpose, may be ob- tained in terms of the right ascension as follows : Let K be the right ascension at the time of observation, 3 the declination, w the obliquity of the ecliptic, and x the connexion necessary to reduce the observed declination to the solstice. By spherics, sin. /c tan. lo = tan. ^ = tan. (w — x). _, ^ ^ tan. w — tan. x . „ But tan. (w — x) = -r-rz 1 " tnereiore, ^ ^ 1 + tan . w tan . x ' tan. w — tan. x sm. K tan. w =i-— ~i : •^ l-|-tan.i(;tan.a7 which by reduction becomes, (1— sin. k) tan. w tan. X = 1— — -. '- ^p- (8) A + sin. K tan. 2 w ^ ^ This equation would give the reduction to the solstice, but it is not in a form to be readily applied. It admits of a transformation, however, from the following considera- tions, which renders it remarkably simple. Since k does not in this case differ much from 6^ or 18^, let a = 6^ — k, K — 6^, 18^ — fc, K — 18**, and a being small cos. k- = 1 — A* A* A6 ~2~ "^24 — 720 "^ If this value of COS. K be sub- ♦ There are, I have since found, formulaj, though still requiring simplification, iu some works on Astronomy for this purpose, and not free from obliquity. Methods of Astronomical Observation. 189 stituted in formula (8) it becomes, A^ A* A^ (1-1+ -2--24- + 720- ^^'^ ^^"- ^,o, tan. X = — — — (9) 1 (-+-2- + ^ ~^^-&c.)tan.^t^ Now taking w = 23° 27' 40", tan. w = 0-4340056, and tan. 2 w = 0*1883608. By introducing these values into equation (9) it becomes, _0-2170028 A ^ — 0-0180836 a^ + 0-0006028a^ ^°*^~'l-1883608-0-0941804 A 2 +0-0078483 a 4-0-0002616 a ^ tan.a;=0-18260684A2— 0-0007454 A 4— 0-00075777 A 6 &c. (10) in which A is the length of the circular arc to radius unity. It is now only necessary to adopt the co-efficients of for- mula (10) to degrees of arc or minutes of time, as these are the terms in which the right ascension of the sun is generally given, while tan. x may in like manner be con- verted into seconds of arc. This is accomplished by applying the logarithms of R,°, R", &c. to the logarithms of the co-efficients of formula, (10) and they become those for A expressed in degrees and decimals of a degree and x in seconds. I. II. III. Const, logs. 1-0596970, 5-154114, 1-64523. . (A) Similarly are obtained the logs, of the constants for minutes of time when the right ascension is given in time, and the distance from the solstice is known in minutes of time and decimals. I. II. III. Const, logs. 9-8555770, 2-745874, 8-03287* . (B) To render these co-efficients generally applicable, it is necessary to find the variation of x corresponding to a change of one second in w. For this purpose from formula (9) we get A2 tan. w 2* 5 tan. a: = j—-: ^ — = 77, A2 tan. ?^7 nearly, and thence, 5 a:= y- A2 sin. 1" tan. m? . . ... (11) * 0"»7 170955 A2 — 0"-00,00000557024 A* — &c. 190 Mr. William Galbraith, on some Differentiating equation (H) and — A^sin. 1 12 COS. 2 w 5 . ,, ^w =T-.A^ sin. 1 tan. CO. COS. ?« — —r- 12 2 COS. ^1(7 since tan. + cos. = R2 = ]. But .— * = COS. therefore sin. 5 ^ . _. COS. i^; w X sin. Y Iw I X =77-. A^sm. I tan. w x — x — =— i 12 sin. t^ cos.-^ w siu. wcos.w and since the sin. 2 ?f? = 2 sin. w cos. w, we have 2 sin. I" X ^ w Sin. 2" X d w ,,^^ d X = o = — ' — s • • • (12) sm. 2 w sin. 2w ^ Taking ^ w = 1", substituting for sin. 2 w its value when w = 23° 27 40", formula (12) will become d X = 0-0000132748a: (13) Log. of 0-0000132748 is 5-1230279 By this means the correction for the variation of w from 23° 27' 40" may be readily obtained, by adding this constant logarithm and the log. oi dw in the given case to the sum of the logs, under I, the sum will be the log. of the correc- tion of X. Example 1 . Let «; = 23° 27 43"- 76, a = 60" a m? = + 3"-76, required the reduction to the solstice. I. II. III. Const, logs. . . . 9 8555770, 2-745874, 8-03287 A = 60>" log. A2 = 3-55630-25, A^ = 7-112605, a ^ = 0-66891 1= +43' l"-54 log. 3-4118795 2=— 0-72 C.L. 5123 3=— 0-05 log. aw 0-575 0-13 9-858479 8-70178 2d = — 0"-72 3d=— 0"-05 4= + x=-\- 43 0-90 4th: 9-110 + 0"-13 A Cor.— , „ 20 001 30 0-05 40 0-15 50 0-36 65 0-54 60 0-77 65 1-08 70 1-46 75 1-96 80 2-56 Methods of A stronomical Ohsei^vation . 191 When A does not exceed 30 or 40 minutes, which will in general be sufficiently distant from the solstice, the operation by the formula, even in natural numbers, becomes remarkably simple, because in that case, the second and third terms are insensible. To render the first term applicable to every case, the sum of parts II and III may be taken from the small table in the margin, and is always to be subtracted. Example 2. Let the sun's right ascension be 7^ 16" 36% the obliquity of the ecliptic 23° 27' 32"*8 and, consequently, A = 1^ 16°" 36% h w = 7"-2, required the reduction to the solstice ? In this way, the computation assumes the following very simple form : Const, logarithm 9-855577 A = Ih 16m 36s ^ 7601.6, log. x 2 . . . = 3-768458 lstcor.= + l°10'7"-61og 3-624035 2d cor. = — 2-2 from this small table, ^ w= — 7''-21og 0-857 3d cor. = — 0-4 ^ x from calculation. Const, log. 5-123 a; = + 1 10 5-0 = red. to solstice. ^ x log. . — 9-604 Hence, it appears that by this formula, the reduction to either solstice is a very easy operation. From these preli- minary formulae it is now proposed to show their general application to one day's observations, consisting of six sets or three pairs, made on the 5th of July last, at Edinburgh, in latitude 55° 57' 15"-67 N. 1834, July 5th. Chronometer fast for mean time . 2' 40" Equation of time with a contrary sign . . . . 4 16 Chronometer fast on apparent time 6 56 Barometer, 30'°' 17, attached thermometer, 70° P., detached, or that in the open air, 68° F. Or, instead of making the 6°" 56' the error to each, it may be applied to 12^^ by subtrac- tion, thus giving 11^ 53" 4' for the time of apparent noon by chronometer, a method rather more convenient. 192 Mr. William Galbraith, on some Method of recording the Observations. Time by Observed Face of Obs. Chronometer. Level. Limb. Ver. Altitude. Circle. Er. h, m, s. ' e o 11 50 50) rA 56° 32' 15' 6 56} 19 16 G's/. IJB 30 15 [3^3 (C 31 0 11 43 54 11 53 14^ CA67 1 30 45 W, 0 45 11 53 14-) fA57 1 E. 6 56 V 13 21 e'su.lJB 3 11 46 183 (C 0 11 55 58) f A56 36 45 E. 6 56 > 23 11 e'sl.l.lB 34 45 E. rr49~23 (C 35 30 11 58 41) rA57 5 15 E. 6 56i 18 16 Q'su.L{B 3 0 W. 11 51 453 (C 4 45 12 2 31-) rA56 40 0 E. 656(20 13 e's/. Z.3b 37 45 E. ri~55~35J (.C 39 0 12 5 39-^ CA57 6 45 K 6 56(10 23 e'su.lJB 8 45 W. 11 58 43) (C 6 0 e = 103o=100MeanofDeg.56 30 0 0 = 100 2r ^ 357^5:' ^_. ^9 52-5 n V 6x3 e-o= 3&Z=^-f^=3#^=-I-33 2n 2x6 Correct mean of the whole, . . . . 56 49 51*12 Reduction to the Meridian. Times. Dist. from Mer. m n h. m. s. m. s. " " 1 11 43 54 16 6 508-77 0-62 2 46 18 13 42 368-46 030 3 49 2 10 58 236-10 0-14 4 51 45 8 15 133-63 0-05 5 53 35 4 25 38-30 001 6 58 43 1 17 3-23 0-00 1288-49 1-12 Mean, 214-49 01867 Methods of Astronomical Observation. 193 Reduction to the Meridian. Refraction. X = 55° 57 COS. 9-748123 o. ' a = 22° 50 COS. 9-964560 Z = 33 10 log. I d 1-5818 A = 56° 50 sec. 0-261952 tan. 0-1847 B = 30-17 log. 0-0025 9-974635x2=9-9493 r = 70° log. 9-9991 m = 214"-751og.2-3319337ilog. 9-2711 f = 68° log. 9-9840 Breskens, Scharrendijke, Ter Heide, Katwijk, . Kalantsoog, Zandvoort, Huisduinen, Wierum, . Makkum, Molquerum, Harderwijk, Huizen, . Enkhuizen, 1 August, 21 Sept 1025-1 1022-9 1021-8 1022-6 1023-8 1022-0 1024-5 1027-6 1021-1 1018-2 1008-3 1011-7 10140 1025-7 1024-2 1019-1 1019-4 1022-2 1021-5 1022-6 1025-4 1018-6 1013-3 1007-3 1011-4 1013-6 1 N< 1025-9 1024-9 1025-2 1024-0 1022-8 1019-6 1023-4 1022-3 1016-7 1015-3 1010-2 1012-4 1015-9 XX. — Essence of Turpentine. Dumas and Peligot infer from their experiments, that the essences of turpentine, basil {Ocymum hasilicum), and of cardamoms (^Car- damomum minus) are identical in their composition, which is repre- sented by. Carbon, .... 63-6 Hydrogen, . . . 11-4 Oxygen, .... 25-0 100-0 XXL— NEW BOOKS. Lehrbuch der Chemie und Pharmakologie fiir Aerfte und Thierarzte. Band. Von C. G. H. 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CO >fi 'O lo «o 'O 'C o u:: lO iO o 'C -^ 'O ic lO io '^ io io 'O »o "0 -T}* i-o T-liHi-lf-iT- — T-iH'HrH^JSOCMSO e 3 ^ .3 > r^ ,1- '4 3 kS ,3 > r° ,1- s 3 ^ ,- s- r= ,>^ eo » RECORDS OF GENERAL SCIENCE. Article I. Biography of M. Le Comte Lagrange.^ ByM, Delambre. Joseph Louis Lagrange, one of the founders of the Academy of Turin, Director during twenty years of the Academy of Berlin, for the physico-mathematical sciences, Foreign Associate of the Academy of sciences of Paris, member of the Institute of France and of the board of lon- gitude, Senator and Count of the Empire, Grand Officer of the Legion of Honor and Grand Cross of the imperial order of the re-union, was born at Turin on the 25th of January, 1736. His father was Joseph Louis Lagrange, Treasurer of War ; his mother, Maria Theresa Gros, only daughter of a wealthy physician of Cambiano. His great-grandfather, captain of cavalry in the service of France, had gone over to that of Emmanual XL, King of Sardinia. Through the latter he was fixed at Turin, by marriage with a lady Conti, of an illustrious Roman family : he was of Parisian extraction, and relative of one Maria Louisa, tire-woman of the mother of Louis XIV., and afterwards wife of Francois Gaston de Bethune.f These details are of no importance to the illustrious Geometer, whose renown dispenses with shewing forth a genealogy, but not so to France. She is eager to recal him, and re-establish him under her ancient sovereignty. His own name, and that of his mother also, attest a French origin ; all his works are written in French ; the city • From Silliman's American Journal, xxx. 64. t Eulogy of Lagrange by Cassali. Padua, 1813. VOL. IV. B I 242 Biography of M, Le Comte Lagrange. which saw his birth too had become French. France then, has incontestably the right of being proud of one of the greatest men who has honoured the sciences. His father was wealthy, had made an advantageous marriage, but was ruined by hazardous enterprises. Let us not hence pity M. Lagrange. He himself received this misfortune as the first cause of all what afterwards befel him most happily. S'il avait eu de la fortune, said he him- self, iln eunt prohahlement pas fait sonttat desmdthematiques. And in another career, what advantages could he have found, that had entered into comparison with those of a calm and studious life, with that brilliant train of success, uncontested in a department reputed eminently difficult, and with that personal esteem, which he saw increase till his last moment. A taste for mathematics, however, was not that which he first manifested. He had a strong passion for Cicero and Virgil before being able to read Archimedes and Newton. Soon he became an admirer no less passionate of the geometry of the ancients, which he at first preferred to the modern analysis. A memoir which the celebrated Halley had long before composed, expressly to show the superiority of analysis, had the glory of converting M. Lagrange, and revealed to him his true destination. He then gave himself up to this new study with the same success which he had obtained in synthesis, and which had been so marked, that at the age of sixteen* years he was professor of mathematics in the royal school of artillery. The extreme youth of a professor is for him but a greater advantage, when he has shown extraordinary talents and at the same time his eleves are not children. All those of Lagrange were older than himself and were not thence less attentive to his lessons. He selected some of them whom he made his friends. From this association sprang the Academy of Turin, which published in 1759 a first volume, under the title of Actes de la societt privee. We therein see Lagrange direct- ing the physical researches of Doctor Cigna, and the works of the Marquis de Saluces. He furnished to Foncenex the analytical part of his memoirs, at the same time leaving to • Others snv fifteen or nineteen. ^Biography of M. Le Comte Lagrange. 243 bim the care of developing the arguments on which his formulas rested. In effect, we notice already in these memoirs this pure analytical step which afterwards charac- terized the great productions of Lagrange. He had found a new theory of the lever. It constituted the third part of a memoir that had much success. Foncenex in return, was put at the head of the navy which the king of Sardinia was then forming. The two first parts seem of the same style and from the same hand. Are they alike from La- grange? He has not positively claimed them. What, however, can direct our conjectures to the real author, is, that Foncenex soon ceased to enrich the collections of the new Academy, and that Montucla, ignorant of what has been revealed to us by Lagrange at his last moments, is astonished that Foncenex, after being so favourably an- nounced, broke off researches that could have obtained for him a great name. Lagrange abandoning to his friend isolated solutions, published at the same time under his own name some theories which he promised to follow out and develope. Thus, after having given new^ methods for maxima and minima o^ ever J hind, after having shewn the insufficiency of the known formulas, he announced that he would treat this subject, which otherwise appeared to him interesting, in a work which he was preparing, and in which, too, are seen deduced from the same principles all the mechanics of bodies, whether solids, or fluids. Thus, at twenty three years he had already laid the foundation of great works, which have since excited the wonder of philosophers. In the same volume, he brings back to the differential calculus, the theory of recurring series, and the doctrine of chances, which, hitherto, had been treated only by indirect methods, and which he establishes upon the most natural and the most general principles. Newton had undertaken to submit to the calculus the motions of fluids : he had made researches on the propaga- tion of sound. His principles were insufficient and even defective ; and his suppositions inconsistent with them- selves : Lagrange demonstrated them to be so. Lagrange founded his new researches on the known laws of dynamics; hy considering in the air only the particles found in a straight r2 244 Biogra'phy of M. Le Comte Lagrange. line, he reduced this problem to that of vibrating cords, about which the greatest geometers were divided ; he sBowed that their calculations were insufficient to decide the question ; he undertook a general solution by an analysis new as it was interesting, since it permits of resolv- ing at once an indefinite number of equations, and since it extends even to discontinued functions : he established more firmly the theory of the mixture of the simple and regular vibrations of D. Bernouilli : he shows the limits between which this theory is exact, and beyond which it is defective; then he arrives at the construction given by Euler, a true construction, although the author had arrived at it only by calculations which were not sufficiently rigorous : he answers objections raised by D'Alembert ; he demonstrates that whatever figure we give to the cord, the duration of oscillations will be always the same, a truth of which for experiment D'Alembert had judged the demon- stration very difficult or even impossible ; he passes to the propagation of sound ; treats of simple and compound echoes, of the mixture of sounds, of the possibility that they spread in the same space without disturbing one another, and demonstrates rigorously the generation of harmonical sounds ; he announces lastly, that his object is to destroy the prejudices of those who still doubt if mathe- matics could ever shed true light on physics. Euler felt the worth of the new method, and selected it for the object of his profound meditations. D'Alembert did not coincide. In his private letters, as in his printed memoirs, he proposed numerous objections, to which La- grange has since answered, but which can at least leave this doubt ; . . How, in a science to which we grant univer- sally the merit of exactness, can it be that men of the first order are divided among themselves, and for a long time dispute ? The first answer of Euler was to cause Lagrange to be associated with the Academy of Berlin. Upon announcing to him this nomination, on the 2nd of Oct., 1759, he said to him : *' voire solution duprobleme des isoperimetres ne laisse rien a desire et je me rejouis que ce sujets, dont je metais presque seul occupe depuis Ics premieres tentatives, ait tte porte par vous au plus haut degrt de perfection. L' importance de Biography of M. Le Comte Lagrange, 245 la matter^ ma excite a en tracer a V aide de vos lumieres, une solution analytique a laquelle je ne donnerai aucune publicite jusqu a ce que vous-mtme ayez public la suitede vos recherches pour ne vous enlever aucune partie de la gloire qui vous est due. If these delicate proceedings, and the testimonies of the highest esteem should flatter a young man who was not twenty four years old, they do no less honour to a great man, who, holding then the sceptre of mathematics, knew how to receive in this manner the work which pointed out to him his successor. But these eulogies are contained in a letter : hence we might think that the great and good Euler may have suf- fered himself to go on in some of the exaggeration permitted in the epistolary style ; let us see then how he afterwards expressed himself in the dissertation which his letter an- nounced. Here is the beginning : '•After I had long and vainly fatigued myself in seeking for this integral, (postquam diu et multum desudassem nequicquam inquisivissem) what was my astonishment (penitus obstupui) when I learned that in the Memoirs of Turin, this problem is found resolved with as much ease as excellence. This fine discovery caused me the more admi- ration as it is the more different from the methods which I have given, and as it surpasses them considerably in sim- plicity." It is thus that Euler begins the memoirs, in which he explains with his usual clearness, the reasons of the method of his young rival, and the theory of this new calculus, which he has called the calculus of variations. To render more sensible all the different motives which gave birth to the admiration that Euler showed with such noble candour, it will not be useless to recur to the origin of the different researches of Lagrange^ such as he gave it himself two days before his death. The first attempt to determine the maximum and mini- mum in all indefinite integral formulas, had been made on account of the curve of the swiftest descent, and the isope- rimeters of Bernouilli. Euler had reduced them to a general method, in an original work, which exhibits throughout ►a deep knowledge of the calculus ; but, however ingenious his method was, it had not all the simplicity which we can desire in a work of pure analysis. The author himself 246 Biography of M. Le Comte Lagrange. came to the same conclusion ; he perceived the necessity of a demonstration independent of geometry and of analysis. In an appendix to the volume having for its title du Mouvement des projectiles dans un milieu non resistant, he seemed wholly to distrust the resources of analysis, and finishes by saying Si mon principe {it is that which Lagrange has since named the principle of the last action) nest pas suffisamment demontre, comme cependant it est conforme a la verite, je ne doute pasqu'au moyen des principes d'une saine metaphyssique on ne puisse lui donner la plus grande evidence, et j'en laisse le soin a ceux qui font leur etat de la metaphysique. This appeal, to which metaphysicians did not answer, was understood by Lagrange who excited their jealousy. In a short time the young man found the solution of which Euler had despaired. He found it by analysis ; and in giving an account of the way in which he had been led to this discovery, he said positively, to answer the doubts of Euler, that he viewed it, not as a metaphysical principle, but as a necessary result of the laws of mechanics, as a simple corollary of a more general law, which he afterwards made the base of his Mecanique Analytique. (See this work, page 246 of the second edition, or 189 of the first.) This noble spirit that excited him to triumph over diffi- culties regarded as insurmountable, and to rectify or com- plete theories still imperfect, appeared to have constantly directed Lagrange in the choice of his subject. D'Alembert had thought it impossible to submit to the calculus the motions of a fluid contained in a vessel, if this vessel had not a certain figure. Lagrange demonstrated on the contrary, that there would be no difl^iculty except in the case when the fluid is divided into many portions. Yet then we can determine the places where the fluid ought to be divided into many portions, of which we can determine the motions as if they were isolated. D'Alembert had thought, that in a fluid mass such as the earth might have been originally, it was not necessary that the diff*erent layers should be on a level : Lagrange shews that the equations of D'Alembert were themselves only those of strata on a level. In opposing D'Alembert with all the respect due to a Biographj of M. Le Comte Lagrange. 247 geometer, of that order, he often employed very fine theorems which he owed to his opponent ; D'Alembert, on his side, added to the researches of Lagrange. " Your problem appeared to me so fine," wrote he to him, '* that I have sought another solution for it ; I have found a more simple method of arriving at your elegant formula." These examples, which it would be easy to multiply, prove with what courtesy these celebrated rivals corresponded. Vying with each other incessantly, conquered as well as conquerors, they found at every moment, in their discussions them- selves, reasons to esteem one another the more, and each supplied for his antagonist opportunities that were to lead him to new triumphs. The Academy of sciences of Paris, had proposed for the subject of one of its prizes, the theory of the libration of the moon ; that is to say, it asked the cause why the moon, in turning around the earth, always shows the same face, with tlie exception of some variations observed by astrono- mers, and of which Cassini I. had well explained the mechanism. The point was, to find the means of calculating the phenomena, and of deducing them analytically from the principle of universal gravitation. Such a chance was an appeal to the genius of Lagrange ; one, which was held out to him of applying bis principles and his analytical discoveries. The hope of D'Alembert was not blasted. The piece of Lagrange is one of his highest titles of glory. Therein are seen the first developments of his ideas and the germ of the Mecanique Analytique. D'Alembert wrote to him ; jai lu avec autant de jjlaisir que de fruit voire belle piece sur la libration, si digne du prix quelle a remportce. About this time he turned his attention to the theorems of Fermat, on the properties of numbers. Many geometers, undoubtedly, practised upon the theorems of Fermat, but not one ever succeeded. Euler alone had made some pro- gress in this difficult path, wherein have since distinguished themselves M. Legendre and M. Gauss. Lagrange, upon demonstrating or correcting some attentive glimpses of Euler, resolved a problem which appeared to be the knot of all the rest, and from which he derived a useful result, that is to say, the complete resolution of equations of the second degree, with two unknown quantities which 248 Biography of M. Le Comte Lagrange, must be entire numbers. The memoir, printed like the preceding among those of the Academy of Turin, is never- theless dated at Berlin, the 20th September, 1768. This date points out to us one of the events, (few indeed,) vi^hich show that the life of Lagrange is not all in his works. His residence at Turin pleased him little. He saw there no one who cultivated mathematics with success : he was impatient to see the philosophers of Paris with whom he corresponded. M. de Caraccioli, with whom he lived in the greatest intimacy, had just been nominated to the em- bassy of England, and was to pass through Paris where he purposed making a short stay. He proposed this journey to Lagrange. Lagrange consented to it with joy, and as might have been expected, was welcomed by D'Alembert, Clairaut, Condorcet, Fontaine, Nollet, Marie, and other philosophers. Having fallen dangerously sick in the course of a dinner, when Nollet had served to him only dishes prepared a T Italienne, he could not follow his friend, M. Caraccioli, to London, who suddenly received an order to repair to his post, and was obliged to leave him in a fur- nished hotel, to the care of a confidential person, directed to supply all his wants. This event changed his purpose. He dreamed of nothing but of returning to Turin. He gave himself up to mathe- matics with a new ardour, when he learned that the aca- demy of Berlin was threatened with the loss of Euler, who was intending to return to St. Petersburg. D'Alembert spoke of this intention of Euler in a letter to Voltaire, the 3d of March, MQQ-, jen serais fache, added he, cest un homme peu amusant, mats un tres-grand geometre. It was of little consequence to D'Alembert that the homme peu amusant should remove seven degrees from Paris towards the pole. He could read the works of the great geometer in the Transactions of the Academy at St. Petersburg, as well as in those of the one at Berlin. What troubled D'Alem- bert was, the fear of seeing himself called upon to re-place him ; and the embarrassment of replying to offers which he was well resolved not to accept. Frederic, in fact, proposed anew to D'Alembert the place of president of his academy, which he held for him in reserve after the death of Maupertuis. D'Alembert suggested to him the idea of Biography of M. Le Comte Lagrange, 249 placing Lagrange in the place of Euler ; and if we believe the secret history of the court of Berlin (torn II., p. 474), Euler had already pointed out Lagrange as the only man apahle of following in his track. And, indeed, it was natural that Euler, who wished to obtain leave to quit Berlin, and D'Alembert who sought a pretext for not going thither, should both, without corresponding with each other, have cast their eyes upon the man most fit to sustain the glory which the labours of Euler had shed upon the Academy of Prussia. M. Lagrange was engaged with the title of director of the Academy in the physico-mathematical department. We cannot fail to be astonished that Euler and Lagrange, placed successively in the place of Maupertius, should have received but half of the salary which the king wished to give, apart from every thing to D'Alembert. The rea- son is, that this prince, who, in his leisure, cultivated poetry and the fine arts, had no idea of the sciences, which he thought himself obliged, notwithstanding, to protect as a king : the reason is, that in reality he placed little value upon geometry, against which he sent three pages of verse to D'Alembert himself. D'Alembert delayed answering him until the end of the siege of Schweidnitz, because ce serait trop d'avoir a-la-fois VAutriche et la geometric sur les bras; and, notwithstanding the immense reputation of Euler, we see by the correspondence with Voltaire, that Frederic designated him only by the qualification of his geometre horgne, dont les oreilles ne sont pas faites pour sentir les delicatesses de la poesie : to which Voltaire added ; nous sommes un petit nomhre d' adeptes qui nous y connaissons, le rest est ptrofane : a remark more witty than fair, and which Euler, in speaking of geometry, might have been able to retort against Voltaire and Frederic. We see plainly that Voltaire who had so worthily lauded Newton, sought in this expression to flatter Frederic. He entered out of courtesy into the ideas of a prince. For Frederic wished to put at the head of his Academy an individual only, who had at least some reputation in literature, under the fear that a geometer would not take sufficient interest in the direction of literary works ; and at the same time, that a man of letters would not be more out of place at the head of a society, composed 250 Biography of M. Le Comte Lagrange, in part of persons whose language he did not understand. He was then right in dividing the office in order that it might be completely filled. We must not he expected to follow Lagrange step by step, in the learned researches with which he has filled the Memoirs of Berlin, after his arrival in that city, on the 6th November, 1766, and even some volumes of the Academy of Turin, that owed to him, in all respects, its existence. But we cannot omit pointing out, at least in a few words, the most remarkable which they contain. He wrote the following Memoirs in the Transactions of the Berlin Academy : — 1 . A great memoir wherein are found the demonstration of a curious proposition that Euler could not demonstrate, a new extension given to this theorem and direct proofs of many other propositions, to which Euler had arrived only by way of induction, and in which, after having enriched the analysis of Diophantus and Fermat, the author passes to the theory of equations, with partial differences explains a striking paradox noticed by Euler, makes known an entire class of equations of which there were only some isolated examples, and puts out of sight the paradox by showing to what belong, both the complete integral of these equations, and the singular solution which is not comprised in this integral. 2. A formula for the return of series, remarkable by its generality and the simplicity of the law, of which he makes a happy application to the problem of Kepler, and thence succeeds in rendering sensible the convergency of the analytical expression of the equation of the center, a con- vergency which we had always supposed, without being able to demonstrate. 3. An important memoir on the solution of numerical equations, containing also new remarks on that of alge- braical equations. This work served as the basis of a treatise which he afterwards published, under the same title, and of which he gave two editions. 4. Another memoir, no less important, and still more original, where he reduces to operations of pure algebra, every process of the differential and integral calculus, which he separates from every idea of infinitely small, of fluxions, Biography of M. Le Comte Lagrange. 251 of limits and of vanishing, and demonstrates the lawfulness of the abreviations permitted in these two calculs, which Jae also frees from all difficulties, and from all paradoxes that had sprung up in an imperfect and suspected meta- physique. 5. The demonstration of a curious theorem on primal numbers; a demonstration that no one had been able to find, and the more difficult, as we know how to express algebraically propositions of this kind. 6. The integration of partial differences of the first order, by a fruitful principle, sufficient for the greater part of cases where this integration is possible. 7. A purely analytical solution of the problem of the rotation of the body of any figure, wherein he at last sur- mounts difficulties that had long stopped him, and by which geometers seemed to expect, with curiosity, some ulterior developments, that they hoped to find in the second volume of his new Mechanique Analytique. In addition tO these, he wrote many memoirs on the obscure and difficult theory of probabilities, wherein we admire the integral that forms its base, the number and importance of the problems it resolves ; the application that the author makes of it to the question, recurring every day in astronomy ; of the degree of confidence that can be allowed to the mean result of a great number of observa- tions ; and wherein is found this remarkable property, and so favourable to the circles of Borda, that each of the even numbers states as probable, by the odd number im- mediately above, that the error will be comprised within certain limits. M. le Comte Laplace had on his part laboured on the same theory. M. Lagrange resumed it, on his part, by means which extend to equations of all orders. Of these, they give finite integrals, and facilitate, in all cases, the determination of arbitrary functions. He made then a similar attempt for the problem of eclipses ; he found that the methods, somewhat prolix, of Dusejou, had neither the simplicity nor the facility that ought to have been expected from the actual state of analysis. He exhibits, in this work, all bis resources and all his address. (To be continued.) 252 Dr, Thomas Thomsons Experiments on the Article II. Experiments on the Combination of Sulphuric Acid andWater. By Thomas Thomson, M.D., F.R.S., L.&E.,&c., Regius Professor of Chemistry in the University of Glasgow. {Read before the Chemical Section of the British Association for the Advancement of Science, Aug. 25th, 1836.) It is well knowp, that when sulphuric acid and water are mixed in any proportion whatever, a change takes place iii the temperature, by the evolution of heat, while a chemical combination is formed between the acid and the water. The heat evolved in this case has been universally ascribed to a change in the specific heat of the compound, which, being less than the mean specific heat of the two con- stituents, requires less heat than before to maintain its temperature, and must in consequence appear hot. I am not aware of any attempt to investigate this curious subject, except the experiments of M. Gadolin published in the Memoirs of the Stockholm Academy for 1784.^ But as Gadolin no where specifies the specific gravity of the acid which he employed, and as his experiments were made upon diff'erent weights of the acid and water, without any reference to the atomic proportions, it is impossible to deduce any legimate conclusions from these experiments. This is to be regretted, as the experiments of Gadolin appear to have been carefully made, and to have been sufficiently varied. But as the atomic theory was quite unknown in 1784, it was impossible for Gadolin to select such proportions of acid and water as would throw the requisite light upon the combinations. To obtain pure sulphuric acid of the requisite strength for my purpose, I distilled a quantity of Nordhausen acid, which had been long in my possession, and which had ab- sorbed so much moisture from the atmosphere that its specific gravity was reduced to l-8375.t Nordhausen acid, • Ran och annuirkningar om Kroppars ahsoluta Varme. At' Johan Gadolin. Kong. Vetens. Acad. Handlingar, 1784, p. 218. An abstract of these experiments has been inserted in the Appendix to Crawford's Treatise on Animal Heat, p. 457. t The author stated in the Section, in answer to a question from Dr. Dal ton, that English sulphuric acid will not answer for these experiments, in consequence of its containing nitric acid. It contains also arsenious acid, Records, ii. 73 ; and muriatic acid. Ibid. iv. 162. — Edit. Combination of Sulphuric Acid and Water. 253 as is well known, is always opaque, and of a blackish colour. This is owing to the presence of some vegetable matter charred by the acid. For when the acid has been kept for some time boiling, it loses its dark colour, and becomes as colourless and transparent as the purest British acid. Suspecting at first that this dark colour might be owing to the presence of selenium or iodine, or even bro- mine, I examined it for each of these bodies, but unsuccess- fully. The only foreign body whose presence was dis- covered, was the sulphate of lime ; of which the acid I em- ployed contained y^Vo*^^ P^^^ ^^ ^^^ weight. It was suspended in the acid in white flocks, and greatly facili- tated the distillation, by preventing the violent ebullition which is apt to take place when we attempt to distill con- centrated sulphuric acid. I continued the distillation till the specific gravity of the acid which came over was as great as that of the acid in the retort. It was obviously needless to continue the process farther ; because all farther concentration of the acid became impossible.* The acid remaining in the retort had a specific gravity of 1*8422 at the temperature of 59°. It was obviously a compound of 1 atom acid, . . 5 1 atom water, . . 1*125 6-125 and its atomic weight was 6* 125. It was this acid that was employed in all the following experiments. The only im- purity which I detected in it was (as above stated) ^^oV^*^ of its weight of sulphate of lime ; a quantity so small, that it could not materially affect the results. It was impossible to get rid of this sulphate, while the acid retained its * In a first process, the acid put into the retort had a specific gravity of ;1*8376, and was composed of Real acid, . . 77*85 or 1 atom Water, . . . 22-15 1*264 atom 100*00 ^he acid that came over had a specific gravity of 1*6598 (or was very nearly a compound of 1 atom acid -f 3 atoms water.) The specific gravity of the acid jmaining in the retort was 1*8396 at 64^ J. 264 Dr. Thomas Thomsons Experiments on the strength. But after it had been diluted with a certain proportion of water, the sulphate of lime precipitated to the bottom, and the pure acid was drawn off. This hap- pended, when the acid was so much diluted, as to be com- posed of 1 atom acid, ... 5 5 atoms water, . . 5*625 10625 1. Specific Gravity of different Atomic Compounds of Sul- phuric Acid and Water. As an atom of sulphuric acid of the specific gravity 1*8422 weighs 6*125, and as it is a compound of 1 atom acid and 1 atom water, it was easy, by mixing determinate weights of this acid and water, to obtain compounds of 1 atom acid with 2, 3, 4, 5, 6, 7, 8, 9 and 10 atoms water. The follow- ing table exhibits the specific gravities of all these strengths. 1 Specific Gravity By ex- By cal- Acid. Water. periment. culation. Difference. 1 atom + 1 atom 1*8422 + 2 „ 1*7837 1-7114 + 0*0723 + 3 „ 1*6588 1*6158 + 0*0430 + 4 „ 1*5593 1*5429 + 0*0164 + 5 „ 1*4737 1*4854 -00117 H- 6 „ 1*4170 1*4389 - 0*0219 + 7 „ 1*3730 1*4006 - 00276 + 8 „ 1*3417 1.3684-0-0267 + 9 „ 1*3105 1.34101-0*0305 + 10 „ 1*2845 1*3174 - 0*0329 The third column in the preceding table was calculated on the supposition, that the bulk of the acid and water united underwent no change, but continued the same after combination as before it. By comparing this column with the second, which shows the actual specific gravities of the various compounds, we see the change of volume which actually takes place. We see that when an atom of oil of vitriol^ combines with 1, 2 and 3 atoms water, the bulk of the compound diminishes, or the specific gravity is greater * I employ this term to denote a compound of 1 atom acid and 1 atom water. Combination of Sulphuric Acid and Water. 255 than the mean. The condensation is greatest when 1 atom of oil of vitriol combines with 1 atom of water amounting to — - that of 1 atom oil of vitriol with 2 atoms water is rr-., while that of 1 atom oil of vitriol with 3 atoms water is only ^. When we combine 1 atom of oil of vitriol with 4, 5, 6, 7, 8, 9 atoms water the specific gravity of the compound is below the mean, so that the bulk increases instead of diminishing, and this increase augments with the number of atoms of water. The following table shows the amount of the expansion. Oil of Vitriol. Water. Expansion. 1 atom + 4 atoms Tir + 5 «^-T 4- 6 tV.t + 7 -A _ 5 1*2 4 8 ■h-^ + 9 tV From this remarkable change from condensation to ex- pansion it is reasonable to infer, that a change takes place in the nature or intimacy of the combinations. The com- bination of 1 atom oil of vitriol with 1, 2, 3 atoms water is probably more intimate than the remaining 6, which are accompanied by expansion. Accordingly we shall find, that most of the heat evolved, when oil of vitriol and water are united, is the consequence of the union of 1 atom oil of vitriol with 1 , 2 or 3 atoms water. These experiments were repeated two or three times; but the specific gravities were found always to vary, some- times in the second decimal place, and always in the third. This I ascribe to the great avidity of oil of vitriol for moisture. The experiments related in this paper occupied a considerable time, about two months of the summer of 1836. The first part of this summer was very dry in Glas- gow, and the latter part very wet. Now, during the weigh- ing of the oil of vitriol (which occupied at least 5 minutes) it was of necessity exposed to the atmosphere. Hence, it would imbibe moisture, and more would be imbibed when the air was damp than when it was dry. No doubt the 25G Dr, Thomas Thomsons Exjieriments on the highest specific gravities in all cases approached nearest the truth. But as I was obliged to strike a mean in all the other parts of the investigation, I thought it better to strike a mean also in the specific gravities. Because, by so doing, I exhibit the specific gravities of the very acids which correspond with the specific heats and evolutions of heat given in a subsequent part of this paper. No doubt in some cases (perhaps in all) the acid may be a little weaker than I have stated ; but the error must be too small to affect the correctness of the general results. 2. Heat evolved when an atom of Oil of Vitriol is mixed with from one to nine atoms of Water. To determine this point, I sometimes mixed 24 cubic inches of oil of vitriol w4th the quantity of water necessary to constitute the number of atoms required ; but in general I took 1000 grains of oil of vitriol, which was previously weighed in a glass cylinder, and poured into a small glass cylinder containing the requisite quantity of water. The bulb of a thermometer was previously inserted into the water. It had a scale ascending to 320°, which I knew by previous trials to be sufficient for my purpose. The mixture was stirred with the thermometer and the tem- perature noted. It was then set aside for 24 hours, covered with a glass plate; and the specific gravity was deter- mined next day. The following table exhibits the weights of oil of vitriol and water used in each experiment, together with the rise of the thermometer or the heat evolved. Heat evolved Weight of Acid. Water. Thermometer Oil of Vitriol. Water. Grains. Grains. rose from 1 atom + 1 atom 1000 183-6 60° to 245° + 2 1000 367-3 67 „ 286 + 3 1000 550-9 60 „ 268 + 4 1000 734-6 60 „ 263 + 5 1000 918-3 60 „ 238 + 6 1000 1102- 59 „ 222 + 7. 1000 1285-7 59 „ 207 + 8 1000 1469-3 59 „ 198 + 9 " 1000 1653- 59 » 188 185° 219 208 203 178 163 148 139 129 Combination of Sulphuric Acid and Water. 257 The greatest rise of temperature took place when 1 atom of oil of vitriol was mixed with 2 atoms water. But 1 atom oil of vitriol with 1, 2, 3 and 4 atoms water occasioned con- siderable evolution of heat. But in order to be able to judge of the real source of this heat, it was necessary to make another set of experiments. I prepared nine mixtures of oil of vitriol and water in the proportions of 1 atom oil of vitriol, and 1, 2, 3, 4, 5, 6, 7, 8, 9. These were put into nine cylindrical glass jars covered each by a small flat glass. The acid in each weighed 1000 grains. They were left 24 hours in order to acquire the temperature of the room, which happened (in most cases) to be 63°. Then a quantity of water, equivalent to one atom, was mixed with each, and the augmentation of temperature was noted. The following table exhibits the result of these trials : Mixture. Thermometer Heat Acid. Water. Water. rose from. evolved. 1.^1 itom + 1 atom) + 1 atom 60° to 245° 185° 2. (1 + 2) + 1 65 to 135 70 3. (1 + 3) + 1 64 to 110 46 4. (1 + 4) + 1 60 to 95 35 5. (1 + 6) + 1 63 to 76 13 6. (1 + 6) + 1 63 to 72 9 7. (1 + 7) + 1 63 to 70 7 8. (1 + 8) + 1 63 to 69 6 9. (1 + 9) + 1 63 to 67 4 10. (1 + 10) 4- 1 ;) 63 to m 3 It is obvious that the greatest rise of temperature takes place when 1 atom of oil of vitriol is mixed with 1 atom of water. The acid of the strengths indicated in Nos. 2, 3 and 4, also produced a considerable augmentation of tem- perature, but rapidly sinking, till the increase, when an atom of the weakest acid of all was mixed with an atom of water, was only 3 degrees. If we calculate what the specific gravities of the above mixtures ought to be, on the assumption that no alteration in the bulk takes place by the union of the acid and water, and compare it with the actual result of experiment, we shall find that an expansion takes place in all cases except the first, when an atom of oil of vitriol is combined with an VOL. IV. s 1368 .Dr. Thomas Thomsons Experiments on the atom of water. This will be made apparent by the following table : Specific Gravity Acid. Water. Water. 1 atom + 1 atom) + 1 atom 1 + 2) + 1 „ 1 + 3) + 1 „ 1 +4) + 1 ,, 1 + 5) + 1 „ 1 + 6) + 1 „ 1 + 7) + 1 „ 1 + 8) + 1 ,, 1 + 9) + 1 ,, By Expe- riment. 1-7837 1-6588 1-5593 1-4737 1-4170 1-3730 1-3417 1-3105 1-2845 By Cal- culation. 7114 6783 5807 5000 4251 3805 3430 3169 2889 Difference. + 0-0723 — 0-0195 — 0-0214 — 0-0263 — 0-0081 — 0-0075 — 0-0013 — 0-0064 -0-0044 The expansion is a maximum when an atom of acid com- posed of (1 atom acid + 4 atoms water) unites with an atom of water. It amounts to ^th of the whole. The least takes place when an atom of acid composed of (1 atom acid + 7 atoms water) unites with an atom of water. It amounts only to n^^ of the whole. 3. Specific heats of various Atomic Compounds of Sulphuric Acid and Water. The method which I employed to determine the specific heats of a compound of 1 atom sulphuric acid with from 1 to 10 atoms water, was this. I procured a thin elipsoidal flask capable of holding about 26 cubic inches of any liquid. It terminated in a narrow neck constituting its mouth. To this a perforated cork was fitted, through which a ther- mometer passed, so that its bulb was very nearly in the centre of the flask, while the whole scale was without the mouth. This flask was placed on a wooden circle which grasped it about two inches from the bottom, while all the rest of the flask was free, and surrounded only by the atmosphere. The stand was fixed on a table near a window at the western extremity of a large laboratory, at a great distance from any fire, and only two individuals were pre- sent to manage the observations. 24 cubic inches of each liquid were put into the flask. It was then either by means of a spirit lamp or a sand bath raised to a temperature 80° higher than the air of the room, and the time which elapsed, while the thermometer sunk the first 40 of these Combination of Sulphuric Acid and Water. 259 degrees, was marked by means of a watch, which pointed out seconds. Every trial was repeated three times. After the experiments were concluded, the whole results were com- pared together, and where any anomaly occurred two other repetitions took place. The numbers given in the follow- ing table are always the mean of at least three experi- ments, and four of them are the mean of five experiments. Hence, it is presumed, that the numbers given denote, with very considerable accuracy, the time which acid of each strength took to cool 40°, the commencement of cooling always taking place when the heat of the liquid was 80° above that of the room in which the experiments were made. The time occupied with these experiments was about eight weeks, from the 16th of May to about the 12th of July, and the thermometer in the room varied from 59° to 67°. Time of cooling 40°. Empty Flask, 215''-5 Water, 5720-7 1 atom acid + 1 wat -f + + ■f + + + 2 3 4 5 6 7 8 9 10 er. 3860 4837-7 4587-2 4702-7 4831-7 4967-3 5075 5164-3 5267-7 5307-5 It will be observed in looking over this table, that 24 cubic inches of a compound of (1 atom acid + 2 atoms water) took a longer time to cool 40° than acid composed of 1 atom acid H- 3 atoms water 1 „ +4 1 „ +5 This was so unexpected an occurrence, that I repeated the experiment six times and varied the acid to guard against any accidental alteration ; but still the anomaly continued. I then determined the specific heat by mixing a pound of hot glass in powder, with a pound of the cold acid, and observing the alteration of the temperature. But, not- s2 260 Dr. Thomas Thomsons Experiments on the withstanding all these trials, the anomaly continued. I cannot, therefore, consider it as a mistake in the experi- ments ; but must conclude, that it is owing to something peculiar in the nature of the compound. As the liquids experimented upon were always contained within the same flask, it is clear, that in order to obtain correctly the time of cooling of each liquid, we must sub- tract from the time as given in the above table, the number of seconds which the empty flask took to cool 40°, which amounted to 21 5 "'S. This is done in the following table : , True time Specific of cooling. j Gravity. Water, . 5505"- 7 1-0000 1 acid + 1 water 3644-5 1-8422 + 2 4622-2 1-7837 4- 3 437J-7 1-6588 + 4 4487-2 1-5593 H- 5 4616-2 1-4737 + 6 4751-8 1-4170 + 7 4859-5 1-3730 + 8 4948-8 1-3417 + 9 5052-2 1-3105 H- 10 5092 1-2845 Sp.heatsof equal wts. 5505 1978 2591 2635 2878 3132 3353 3539 3688 3855 3964 Sp. heats water= 1-000 1-0000 0-3593 0-4707 0-4786 0-5228 0-5690 0-6091 0-6429 0-6699 0-7003 0-7201 The numbers in the second column exhibiting the time of cooling of 24 cubic inches of the various liquids are obviously proportional to the specific heats of equal volumes of these liquids. If we divide the numbers in the second column by the specific gravities of the respective liquids exhibited in the third column of the table, the quotients will represent the specific heats of equal weights of these liquids. These quotients are given in the fourth column of the table. But, as the specific heat of water is usually received uniting, a fifth column has been added, representing the specific heat of the various compounds of sulphuric acid and water, on the supposition that the specific heat of an equal weight of water is I'OOOO. This column is deduced from the fourth by a simple and obvious arithmetical calculation. To put it in our power to judge how far the opinion first started by Dr. Irvine, and afterwards supported by Dr. Crawford, and, indeed, by every chemist who has since Combination of Sulphuric Acid and Water. 261 written on the subject ; namely, that the heat evolved when sulphuric acid and water are mixed, is owing to the formation of a new compound, whose specific heat is less than the mean of that of the two constituents ; we must compare the specific heats as above given with the mean specific heats of the compound, supposing no change what- ever to have taken place. This is done in the following table : Water, . , . 1 acid + 1 water + 2 j> -f 3 >? + 4 jj + 5 >5 + 6 >> + 7 5) + 8 J J + 9 J> + 10 Sp. heats by experiment 10000 0-3593 0-4707 0-4786 0-5228 0-5690 0-6091 0-6428 0-6699 0-7003 0-7201 Mean sp, heats. 0-4587 0-5326 0.5869 0-6306 0-6660 0-6952 0-7197 0-7405 0-7585 Differences. + 0-0120 — 00540 — 0-0641 — 00616 — 0-0569 — 00524 — 0-0498 — 0-0402 — 0-0384 The slightest comparison of the second and third columns of this table is suflacient to show that the hypothesis of Dr. Irvine cannot be accurate. The specific heat of a com- pound of 1 atom oil of vitriol and 1 atom water is greater than the mean by about -j^ih ; yet, if we turn to the table in page 257, we see that the heat evolved amounts to no less than 185°. Now, it is impossible that this evolution of heat can be occasioned by a diminution of specific heat when no such diminution takes place. In all the other compounds there is a diminution of specific heat, but that diminution by no means corresponds with the quantity of heat evolved. The greatest diminution takes place when 1 atom of oil of vitriol is mixed with three atoms of water. It amounts in that case to 0-0641, or very nearly ^th, and the heat evolved is 208°. But, when 1 atom of oil of vitriol is mixed with 2 atoms of water, the heat evolved is 219°, yet the diminution of specific heat is only 0*054 or about -j^th, and consequently less than when the evolution of heat is only 208°. When 1 atom of oil of vitriol combines with 5 atoms of water, the diminution of specific heat is 262 Dr. Thomas Thomsons Experiments on the 0-0569 or nearly ^th, and the heat evolved is 178°. If Dr. Irvine's theory were correct, the heat evolved w^hen 1 atom oil of vitriol is mixed with three atoms water, being 208°, that evolved when 1 atom oil of vitriol is mixed with 2 water should be 178° instead of 219°; 1 atom with 5 should be 155° instead of 178°. The same want of coincidence will be found, if we ex- amine the whole table from beginning to end. It is clear then that the heat evolved when oil of vitriol and water combine, is not the consequence of mere diminution of specific heat. It was observed, a good many years ago, by Dulong and Petit, that when the atomic weight of a simple substance is multiplied by its specific heat the product is a constant quantity. In a paper of mine published in the third volume of the Records of General Science, I have given a consider- able number of examples of this law, and showed, by a pretty copious induction, that the constant quantity is 0*375. The obvious consequence deducible from this law is, that the same absolute quantity of heat exists in com- bination with every atom of a simple body, and that the difference of the specific heats of different simple substances is owing to a difierence in the atomic weight. In the same paper I have shown that when the atomic weight of a compound body is multiplied by its specific heat, the product is always a multiple of 0*375 by a whole number, which number depends upon, or at least is con- nected with, the number of atoms of which the compound body is composed. If the number multiplying 0*375 were equal to the number of atoms in the compound body, then it would follow that every atom of the compound body retains all the heat with which it was combined when in an isolated state, or that the compound retains all the heat that existed in its constituents. If the multiple be less than the number of atoms of which the body is composed, then it follows, that the compound contains less heat than existed in its elements before combination, and the difference between the multiple and the number of atoms gives us the proportion of heat which is wanting. On the other hand, if the multiple be greater than the number of atoms, the heat in the compound is greater than in its simple elements. Combination qf Sulphuric Acid and Water, 263 and the difference between the multiple and the number of atoms is the amount of the difference. Let us multiply the atomic weights and specific heats of the compounds of oil of vitriol and water, in order to see whether this law will apply to them. Water, . . 1 acid + 1 water + + + + + + 10 Atomic Specific Product of Weight. 1125 Heat. Col. 2 & 3. 1-0000 1-125 6125 0-3593 2-201 7-25 0-4707 3412 8-375 0-4786 4-008 9-5 0-5228 4-966 10-625 05690 6046 11-75 06091 7-157 12875 0-6429 8-277 14 0-6699 9-379 15125 0-7003 10-592 16'25 0-7201 11-702 :0-375 :0-375 :0-375 :0-375 :0-375 :0-375 =0375 :0-375 :0-375 :0-375 :0-375 x3 x5-87 x9 09 X 10-68 X 13-24 X 16 12 X 19-08 X 22-07 X 25-01 X 28-24 X 31-20 The last column of the table shows to what number multiplied into 0-375, the product of the atomic weight by the specific heat, is equal. A slight examination of that column is sufficient to show that the respective multiples approximate to the following numbers. Multiples. Water, . . . 3 1 acid + 1 water. . 6 + 2 „ . 9 + 3 „ . 11 + 4 „ 13 + 5 „ . 16 + 6 „ . 19 + 7 „ 22 + 8 „ 25 + 9 „ 28 + 10 „ 31 Or there is a regular increment by 3, except in the case of (1 atom acid + 3) and (1 atom acid -f 4 water), when the increments are only 2. If we admit that these numbers multiplied by 0*375 give the true products of the atomic weight into the specific 264 2>r. Thomas Thomson's Experiments on the heat, we have it in our power to calculate the true specific heat of all these compounds. For it is clear that the pro- duct of these multiplied by the number 0-375, and divided by the atomic weight, must give the true specific heat. The following table has been calculated in that way. Water, , . , 1 acid + 1 water + 2 + 3 4- 4 + 5 + 6 + 7 + 8 + 9 + 10 True Mean p. heat. sp. heats. 10000 0-3673 0-4655 0-4925 0-5131 0-5647 0-6063 0-6407 0-6696 0-6942 07153 0-4587 0-5326 0-5869 0-6306 0-6660 0-6952 0-7197 0-7405 0-7585 Differences, + 00068 or ^3 — 0-0401 or -jL — 0-0738 — 0-0597 — 00541 — 00545 — 0-0501 — 0-0463 — 00432 The differences between the mean specific heats and the true (supposing the second column to represent these) is somewhat diminished in the first six, and somewhat aug- mented in the last four numbers ; but its nature is no where altered. Sulphuric acid is a compound of 1 atom sulphur and 3 atoms oxygen ; so that an integrant particle of it contains four atoms. There are two opinions respecting the con- stitution of water. The continental chemists, in general, consider it as a compound of 1 atom oxygen and 2 atoms hydrogen ; while British chemists, with scarcely any ex- ception, consider it as a compound of 1 atom oxygen and 1 atom hydrogen. According to continental chemists the weight of the atom of hydrogen is 0-06*25, while according to British chemists it is 0*125 or twice as great. We have no means of determining which of these two opinions is the true one. Both are supported by very plausible argu- ments. But it will suit our present views better to adopt the continental opinion, and to admit that water is a com- pound of 1 atom oxygen + 2 atoms hydrogen, or that it is a triple compound. We may draw up a table representing the number of atoms contained in an integrant particle of each of our Combination of Sulphuric Acid and Water. 265 liquids, and place beside them the multiples of 0-375, which represent the specific heat of these liquids. Number Multiples Heat of atoms of 0-375. Differences. evolvec Water, 3 3 0 1 acid + 1 water 7 6 1 + 2 „ 10 9 1 185° + 3 „ 13 11 2 70 + 4 „ 16 13 3 46 + 5 „ 19 16 3 35 + 6 „ 22 19 3 13 + 7 „ 25 22 3 9 + 8 „ 28 25 3 7 + 9 „ 31 28 3 6 + 10 „ 34 31 3 4 From this table it appears that when an integrant particle of oil of vitriol is combined with an integrant particle of water, the specific heat of the compound, instead of being 0375 X 7 (the number of atoms), is only 0*375 x 6. So that one of the atomic constituents is deprived of the whole of its heat : in other words one-seventh part of the whole heat is disengaged. This portion, by experiment, amounts to 185° ; so that the whole heat in the oil of vitriol and water before combination must have been 1295°. When one atom of (one acid + two water is mixed with one atom of water, the heat of the compound is less than 0*375 X 13 (the number of atoms) by 2. But, the com- bination of 1 oil of vitriol and 1 water is less by 1. Hence, in this second combination, the real diminution is only 1; so that the heat evolved should be ^^th of the whole. I found it only 70°. But the experiment was made upon too small a scale. When the experiment was made by mixing 24 cubic inches of oil of vitriol with the requisite quantity of water to constitute a compound of (1 atom acid + 3 atoms water), the heat evolved was 219°, Now, if this be ^\ths of the whole heat as it ought to be from the table, the whole heat would amount to 1423°*5. By the second experiment in which the heat evolved was 70°, the whole heat would amount to 1110°. Now the mean of these two numbers is 1266°, which nearly agrees with the deduction from the mixture of oil of vitriol with one atom of water. 266 Di\ Thomas Thomsons Experiments, Sfc, When an integrant particle of (1 acid + 3 water) is mixed with an integrant particle of water the heat evolved is 46°. In this the multiple of 0'375, which represents the specific heat, is less than the number of atoms present by 3. Therefore, 3 atoms of the constituents are destitute of heat. But two of these atoms are accounted for by the two pre- ceding combinations. Hence, the diminution by mixing (1 acid -f 3 water) with 1 water should be only -^ih. ; or in other words, -^th. of the heat should be evolved. But 16 X 46 = 736. TJie reason of this great diminution is, probably, the greater quantity of matter to be heated, while the absolute quantity of heat evolved is nearly the same. In the first experiment 1000 grains of oil of vitriol and 183-6 grains of water were mixed ; in the second 1550*9 grains of acid of (1 acid -f 3 water) were mixed with 183*6 grains of water. It is impossible that the sensible heat evolved can be the same when the quantity of matter to be heated is constantly increasing. It is not worth while to investigate the table farther. The preceding experiments appear to me to show, in the clearest manner, that the whole theory of Dr. Irvine re- specting the cause of the evolution of heat, when two liquids combine, is inconsistent with fact, and, therefore, erroneous. The quantity of heat evolved appears in all cases to be pro- portional to the energy and rapidity of the combination. The method which I have indicated in this paper, and a preceding one seems to lead to a pretty obvious way of de- termining what portion of the whole heat in a body is evolved when two liquids combine. But it would be requisite to vary and extend the experiments a good deal farther before we draw definite conclusions. Nitric acid and alcohol might be employed with advantage. As the avidity of these bodies for water is not so great as that of sulphuric acid, the experiments could be made with greater ease and accuracy ; while the diminished increase of tem- perature would enable us to determine the heat evolved with greater certainty than can be done when the thermo- meter suddenly rises from 60° to 286°, as it did in one of my experiments. Mr, Exleys Application of Mathematics, Sfc. 267 Article III. Important Facts derived Mathematically from a General Theory, embracing many Results in Chemistry, which are denominated ultimate facts. By Thomas Exley, A.M. (Communicated to the Chemical Section of the British Association, -Aug. 23rd, 1836.) It is not for one man to build the temple of science, many- must be employed. You, veterans in science, you have collected an immense mass of materials. Many have digged for a foundation, but every one yet examined has proved sandy. It has been my lot, through the guidance of the Great Architect, to find the rock on which you may safely build. My object is to place chemistry under the domain of mathematical science, and to establish my new theory by easy calculation and mathematical proofs. The two principles, which form the foundation, are these ; viz. 1st. Every atom of matter consists of an indefinitely extended sphere of force, which varies inversely as the square of the distance from the centre ; and that this force acts towards the centre, and is called attraction at all dis- tances, except in a small concentric sphere, in which it acts ^rom the centre, and is there called repulsion. 2nd. That there is a difference in atoms, arising from a difference in their absolute forces, or in the radii of their spheres of repulsion, or in both these respects. The theories of Newton and Boscovich agree perfectly with this, as far as regards the attraction in the first prin- ciple : after that Newton and Boscovich go together in conceiving a series of alternate spheres of attraction and repulsion, governed by unknown laws, but, as regards change of direction the forces graduate into each other. Boscovich reaches the centre with a sphere of repulsion which varies inversely as the simple distance, making the force at the centre infinite ; while Newton closes with a solid nucleus, which is only an infinite force long before we reach the centre. The new theory rejects all these hypothetical, unsubstantiated forces, and their feigned alterations; and, with the utmost possible degree of sim- plicity, admits of but one sphere of repulsion, in which, without interruption, the law of gravitation in the attractive 268 Mr. Exleys Application of sphere is invariably continued down to the centre itself, where it terminates with the infinite force of Boscovich repeated an infinite number of times. The direction changes to the opposite one, per saltum, at the surface of the sphere of repulsion : and why not? It is quite as easy and more natural to conceive that it thus changes at once, than that it is always changing continuously backward and forward ; but, which is a matter of great moment, the con- tinuity of the quantity and of the law of force remains unbroken, preserving the delightful harmony of nature. The inductive philosophy requires and demands this continuity in the law ; unless the contrary could be shown in any instance, we have as much right to say that the law of gravitation does not exist in the infinity of places where no observations have been made, as to say it does not exist in the sphere of repulsion, that important space in which che- mistry and its connate sciences produce all their phenomena. Thus since the 1st principle as to attraction has long been established completely, by induction, and beyond the power of controversy, and since we know from facts that a central repulsion exists, the same induction obliges us to admit the same force in the sphere of repulsion, especially as not a single instance of repulsion acting according to any other law can be shewn to exist, as belonging to any atom of matter. The 2nd principle is perfectly simple and natural, and is established by means of the first principle and induction from facts ; for it is known that atoms do differ from each other, and the difference stated is in complete unison with the first principle, and quite sufficient to furnish all the variety of atoms yet observed, and an infinitely greater variety. The material will of course be allowed, and we readily admit that the creator originally brought into existence, according to number, weight and measure, a quantity of every sort of atoms requisite for the purposes of his grand design in the structure of the universe. Every variety of atoms may, according to the theory, be assumed ; but to find what sorts really exist, phenomena should direct the assumptions. In my ** New Theory of Physics," it was stated that nature presents two classes of atoms ; the one comprehending the elementary substances most generally known, such as. I Mathematics to Chemistry, 269 oxygen, hydrogen, carbon, &c., which, adhering with great tenacity, may (till a better name be found) be termed tenacious atoms. The other included such matter or atoms as manifest their existence by motions and actions, under a form which has been denominated ethereal, and hence they may be called ethereal atoms ; to this class was assigned the electric fluid, caloric and light. In the same work the atoms of electric fluid were con- sidered as having a much greater absolute force, than those of caloric and light; and this has been abundantly confirmed by subsequent observations, entitling the electric atoms to the rank of an intermediate class. Hence, we have three classes of atoms, viz., tenacious, electric, and ethereal atoms. Of the 1st and 3rd classes there are many sorts, but pro- bably only one sort of electric atoms ; this division and arrangement will at least serve our present purpose. The distinction of the classes is founded in a very great difference of the absolute force; that of the sorts in a moderate difference : thus, if the absolute force of an atom of oxygen be 16, and that of hydrogen 1, they will be two sorts of tenacious atoms ; an electric atom must be con- sidered very much less in absolute force than that of either of the former, and the several atoms of light andcaloricperhaps many millions of times less than that of an electric atom. In this paper the atomic weight of oxygen is 16, that of hydrogen being 1, as the unit of comparison. It appears to me exceedingly unfortunate that the British chemists have adopted 8 instead of 16 : they tell us, which shews a want of confidence in their own arguments, that it is of no great consequence which of these opinions be adopted. This is indeed true as it regards many experimental deter- minations, but in theory it is exceedingly important. Is it of no consequence to know whether a compound contain in each particle 2, 3, 4, &c., atoms ? If oxygen be 8, a particle or atom of ether contains 10 simple atoms, but, if oxygen be \6, it contains 15 atoms : would not such a difference alter all or most of its properties I A question so deeply scientific ought not to be treated with indifference. I have not seen one argument in favour of 8 which has any great point or weight : in favour of 16 only one has met my notice which is a good one : it is this ; the simple gases hydrogen, nitrogen, and chlorine, contain an equal 270 Mr. Exley's Application of number of atoms in equal volumes, and oxygen is as much entitled to the character of a simple gas as any of them : hence, it is reasonable to conclude it is not an exception to the rule, but this would require 16 for its atomic weight. The following arguments appear to me decisive. 1. Sulphurous acid is the sole gaseous product, when sulphur is burnt in dry oxygen gas, and the resulting volume is the same as that of the oxygen consumed. 2. Carbonic acid is the sole gaseous product when carbon is burnt in oxygen gas, and the resulting volume is the same as that of the oxygen consumed. 3. Steam is the sole gaseous product when oxygen is burnt in hydrogen gas, and the resulting volume is the same as that of the hydrogen consumed. 4. Sulphuretted hydrogen is the sole gaseous product when sulphur is burnt in hydrogen gas, and the resulting volume is the same as that of the hydrogen consumed. Besides, these substances have all been obtained in the form of gases and limpid liquids ; now the striking analo- gies before us prove, that they are formed after the same manner : but, in the opinion of all parties, the first two contain three atoms each ; hence, the others contain three atoms each, and 16 is the atomic weight of oxygen. Again, take sulphurous and hypo-sulphurous acids on the one hand, and water and deutoxide of hydrogen on the other; then, 1st. Sulphurous acid is formed by burning sulphur in oxygen gas, and the volume of oxygen is not changed ; and the new gas may be passed through red hot tubes without decomposition : but, several substances which have a strong affinity for oxygen, as potassium, carbon, &c., decompose it: also by a slight pressure it becomes a limpid liquid. 2nd. Hypo-sulphurous acid con- tains twice as much sulphur as the sulphurous acid ; it is easily decomposed, and cannot remain permanent at com- mon temperatures. Now the same sentence, with scarcely any variation, may be read for the analogous substances, water and the deut- oxide of hydrogen, by merely substituting the names of these compounds and their elements. But sulphurous acid consists of two atoms oxygen and one sulphur, and hypo-sulphurous acid of one of each, which ever view of the subject be taken ; hence, water must be allowed to be two Mathematics to Chemistry, 271 atoms hydrogen and one oxygen, and deutoxide of hydrogen consists of one of each; hence, 16 is the atomic weight of oxygen. The same sentence will nearly apply to the following couple of compounds, viz., sulphuretted hydrogen and bi- sulphuretted hydrogen : these then must agree in com- position with one of the former couples, which confirms the conclusion. Many similar compounds exist and testify the same thing. One additional instance will be abundantly sufficient, taken from carbonic and nitric oxides. 1 . A volume of carbonic oxide is double that of its oxygen, and combined with another volume of oxygen, it becomes carbonic acid, without change of volume. 2. A volume of nitric acid is double that of its nitrogen, and combined with another volume of nitrogen it becomes nitrous oxide, without change of volume. It follows from these analogies, that the substances before us are composed after the same manner : now, accord- ing to both views, carbonic oxide is one atom oxygen and one carbon ; hence, nitric oxide is one nitrogen and one oxygen ; but by weight the constituents are in the ratio of 14 to 16, and 14 is the atomic weight of nitrogen, therefore, 16 is that of oxygen. The other atomic weights used in this paper are taken from Dr. Thomson's determinations, doubling some of them on account of using 16 for oxygen. They are inserted in the following table, and the numbers of Berzelius are annexed ; the substances in italics are double the numbers given by Dr. Thomson. Atomic Weight by Atomic Weight by j Name. Thomson. Berzelius Name. Thomson. Berzelius Oxygen, 16 16026 Arsenic, 38 75-329 Sulphur, 32 32-239 Boron, 16 21-793 Nitrogen, 14 14-189 Carbon, 12 12-250 Fluorine, 18 Tellurium, 64 129-243 Chlorine, 36 35-470 Titanium, 52 62-356 Bromine, 80 79-263 Silicon, 16 44-469 Iodine, 126 123-206 Hydrogen, 1 1 Selenium, 80 Mercury, 100 202-868 Phosphorus, 16 31-436 Tin, 116 117-839 Berzelius las, with great propriety, set c own the results of his very a ccurate experi ments without ( correcting them by theory ; i t would be wel I to give also 1 he resu ilts thus 272 Mr, Exleys Application of corrected. From the calculated and experimental specific gravities of 57 compounds in the table appended to the 8th proposition, it appears to me, that the numbers, as given by Dr. Thomson, are nearer the truth than those given by Berzelius ; and this more particularly seems to be the case in respect to two or three, which I have examined more at large, as may be seen in respect to carbon from the ten compounds in the following table. The specific gravities are calculated by a rule drawn from the 8th proposition, namely to multiply the sum of the atomic weights of the elements by the specific gravity of hydrogen, when the elements combine in single groups, and by half that sum when they combine in double groups. Atomic Specific Gravity ' Name. wt.of By cal- By ex- Authority and result. carbon. culation. periment Carbonic oxide 12 •9721 -9732 Thenard&Berzehus, mean; 1st 12i •9895 •0011 defect, 2nd -0163 excess. Carbonic acid 12 1^5277 15213 Thenard&GayLussaCjinean; 1st 12i 1^5451 -0064 excess, 2nd -0238 excess. Light carbur. 12 •5555 •5590 Thomson ; 1st -0035 defect, 2nd hydrogen 12i •5728 •0138 excess. Alcohol . . 12 1-5972 1-6133 Gay Lussac ; 1st •OlOl defect, 12i 1-6319 2nd -0186 excess. Etherine . 12 1-9444 1-9100 Faraday ; 1st -0344 excess, 2nd 12i 1^979li •0691 excess. Ether . . 12 2^56942^5830 Gay Lussac &Depretz, mean ; 1st 12^ 2-6388 •0136 defect, 2nd -0558 excess. Naphtha . 12 2-8472 2^8330 Saussure ; 1st ^0142 excess, 2nd 12| 2-8993 •0663 excess. Naphthaline 12 4.44444-5280 Dumas ; 1st -0836 defect, 2nd 12i 4-5312 •0032 excess. Paranaphthal. 12 6-66666-7410 Dumas ; 1st -0074 defect, 2nd 12i 6-92701 4-7222|4-7670 -1860 excess. Camphene . 12 Dumas ; 1st -0348 defect, 2nd 12i 4-8090 1 -0420 excess. In all these ten substances, if 12ibe taken for the atomic weight of carbon, the calculated specific gravity exceeds that found by experiment. In three of them it is so even when 12 is taken, and in the rest defect is very much less than the excess, except in naphthaline, which shews that 12 is much nearer the true atomic weight of carbon than \2\*\ * I have shewn from considerations connected with its specific heat, that the atomic weight of carbon must be -75 or 12* and cannot be -764. — Records, vol. ii. 38.~Edit. Mathematics to Chemistry, 273 Prop. 1 . To determine the general effect of one, two, or more tenacious atoms placed in a vessel, in which ethereal atoms are compressed by a given force, so that of any two contiguous atoms, the centre of one is within the sphere of repulsion of the other ; the tenacious atoms being separated by intervening ethereal matter. Let the ethereal matter be compressed in a spherical vessel R T N (fig. 1 .), as by a given force on the piston T, Kg. 1. and let c, a tenacious atom, be introduced. Now, for a moment, suppose the attraction of this atom not to act ; on this supposition, the ethereal matter will continue to be uniformly diffused through the vessel, quite to the surface of the sphere of repulsion h k, within which the centres of the contiguous atoms are supported against the given pressure : let now the attraction of this atom have its full and proper effect ; evidently the surrounding ethereal matter will be attracted towards it (1st prin.), and con- densed on the surface of repulsion h k, and the change of tension in the neighbouring parts of the vessel will be quickly restored to its former state by the given pressure atT: hence, an atmosphere of ethereal matter, diminish- ing in density from the surface outward, will be accumu- lated, and retained on that surface, more or less dense, as the absolute force of the atom is greater or less, or the radius of its sphere of repulsion is less or greater. When there are several sorts of ethereal matter in the vessel, those sorts which have the greatest absolute force, or the least sphere of repulsion, will occupy the lower strata of the atmosphere ; because, whenever the equili- brium is disturbed, such atoms will be most easily moved VOL. IV. T 274 Mr, Exley*s Application of among the rest, by the action of c ; hence, electric atoms, if present, will form the lowest stratum. When there are several tenacious atoms in the vessel, each will similarly retain an atmospherule on its surface. Next, let there be two tenacious atoms, a and Z>, in the vessel, and let their forces on an ethereal atom at g be each resolved into two, one in R N, passing through their centres, the other in g d, perpendicular to R N. When d is between a and b, the forces in R N oppose each other, and act by their difference ; but in other cases by their sum : again, the forces in g d always act according to their sum ; and, as these forces are supported by equal forces on the opposite side, the constant effect is to condense ethereal matter on the line R N, where the most powerful ethereal atoms, and especially the electric atoms will be chiefly collected, for the reasons assigned above. Hence, there will be an atom, as z, in a b, undisturbed in the middle, when a b are equal, in other cases, nearer to the less powerful atoms : and the atoms condensed in the line a b will be equally pressed and supported on all sides by the contiguous atoms. Cor, When electric atoms are in the vessel, they also will retain small atmospherules of ethereal matter, which, although less dense than those of the tenacious atoms, will have considerable density if the spheres of repulsion of the electric atoms be very small, which is probable. It is also manifest, that the atmospherules of both the tenacious and electric atoms will be more dense, when the ethereal atoms are more compressed or crowded together. Prop. 2. Things being as in prop. 1, the actions of any two atoms on each other, combined with the mutual actions of the whole mass on each of the two, will be a repelling force between them, inversely proportional to their distance. Let s be the centre of the vessel in which ethereal atoms of one sort are compressed by a considerable force: then, since the absolute force of the ethereal atoms is very small, the distance between their centres will also be exceedingly small, constituting points in a sphere, such as in Newton's 73rd Prop. B. 1. Prin., and by that proposition any cor- puscle or atom a, placed at any point of this sphere, will, by the mutual actions of the whole mass be attracted by a Mathematics to Chemistry. 275 force proportional to its distance from the centre s; hence, if the atom a were left to the action of this resultant, un- disturbed by any other influence or obstacle, it would move to the centre by a velocity determined by this law. The same reasoning applies to any other atom h, in the sphere ; therefore, both would, in the absence of all obstacles, or other force on each other, approach, and at the same time meet in the centre, and always their distances from each other would be proportional to that of either from the centre : but this measures their accelerating force, which is, therefore, as their distance. But, besides the mutual actions, which alone would pro- duce the above motions, the atoms a and h act independently, and directly on each other, by an accelerating force, in- versely, proportional to the square of their distance, (1st prin.) ; this must, therefore, be compounded with the former; thus, the force between them varies as the dis- tance, directly, and as the square of the distance, inversely; that is, as the distance inversely. Again, since one of the centres of every two contiguous atoms is within the sphere of repulsion of the other ; the force, here investigated is a repelling force ; which also ap- pears from this, that if the compressing force were removed the atoms would separate : hence, the proposition is true, when the ethereal atoms are of one kind. But, if any num- ber of these be removed, and their places supplied by other atoms, in such manner, that exactly the same equilibrium may be maintained, we shall still have the same conclusion. Prop. 3. If the absolute forces or spheres of repulsion of the tenacious atoms be increased or diminished, the resultant repelling force, as determined in the last pro- position, will not be altered : provided that none of the atmospherules of tenacious atoms are penetrated by the centres of others, so as to displace the atmospherules on the contiguous sides ; that is, on the parts between the two tenacious atoms. For their tendency to separate depends, not on their absolute forces, or spheres of repulsion, as is evident from the last proposition ; but on the law of force, and the given pressure, and these remaining, the repelling force between the atoms a and h will also remain unaltered. T 2 276 Mr, Exley's Application of Or thus : let one of the atoms be increased in its absolute force in any ratio; then the force between it and every other atom in the vessel is increased in the same ratio : but the repulsion between it and contiguous atoms, and, con- sequently, between all contiguous atoms, is increased in that ratio : therefore, the equilibrium continues ; that is, a variation in the absolute force produces no change of equilibrium, and their tendency to separate remains as before. The truth of the proposition is manifest, when the sphere of repulsion only is changed. Def. 1 . A single group of atoms is a collection of two or more tenacious atoms, such, that all their centres are within the sphere of repulsion of some one of them, as in fig. 4. Def. 2. A double group of atoms is two tenacious atoms, or two single groups, or one atom or single group connected by a third atom or single group, such that the connecting atom or group displaces the greatest part of the ethereal and electric atoms between the two atoms or groups which it connects, and the parts of their atmospherules on the contiguous sides, as in tig. 5 and 6. Cor. 1. Considering a single group as one atom, there will be always in equal volumes of different gases an equal number of atoms, the pressure being given. For, 1st, when the tenacious atoms are distinct, and separate, and of the same kind ; this follows from the 2nd and present propositions; since, being in the gaseous form, they are kept apart by intervening ethereal matter ; and, since they are of the same kind, they will be uniformly arranged in the vessel ; therefore, on the other hand, if two gases of two given sorts occupy equal volumes, and contain an equal number of tenacious atoms, the centres will be equi-distant ; therefore, the separating forces (by this and the preceding proposition) will be equal ; and hence, they will sustain the same, pressure ; therefore, when the pressure is given, the number of atoms is equal. 2nd. It is manifest from the same propositions, that a single group will occupy a volume equal to that occupied by a single tenacious atom ; for, since the centres of all the atoms in the group are within the sphere of repulsion of one of them, the centre of gravity of the group may be considered as the centre of a single atom, and the contout* Mathematics to Chemistry. 211 of the spheres of repulsion as a surface of repulsion of greater magnitude; hence, it will have a single distinct atniospherule, and will act as a single atom, and occupy (by this and the preceding proposition) the same volume ; hence, the cor. is manifest. Cor. 2. When two tenacious atoms are connected chemi- cally, yet so as not to form a single condensed group, they will occupy, in a gaseous body, the same volume as they did before the connexion took place. For, according to this and the last propositions, they are kept apart by the same force, as that by which they were before separated. The connecting link will be considered afterward : such may be called cohesive combinations. Cor. 3. A double group will occupy in a gaseous body exactly twice the volume of a single tenacious atom, or of a single group. For the atom or single group connecting two others, as in def. 2, displaces the ethereal atoms, and the parts of the atmospherules between them ; and, because of the given pressure, the same equilibrium will be maintained ; so that the connecting atom will perform the effects of the dis- placed ethereal matter, and, i^erefore, will not alter the distance between the connected atoms; the same argu- ments apply to single groups as to single atoms. Cor. 4. When gases are mixed, and no chemical unio», or only cohesive combination occurs, the volume is not changed. This is manifest from the proposition, since an alteration in the absolute force or sphere of repulsion does not alter the distance between the centres of the atoms, so that each still occupies the same volume. Remark. — If an objection be made to this proposition and its cors. by an appeal to fact, that the specific gravity of sulphur vapour is 96, that of hydrogen being 1, while the atomic weight of sulphur is only 32 ; it is easily ob- viated ; for there will be perfect agreement, if the vapour of sulphur consists of single groups of two atoms each ; and this is likely, since sulphur has two fusing points, and the liquid is less limpid after the second than after the first, besides other peculiarities. 278 Mr, Exleys Application of If the atomic weights of phosphorus and arsenic be 16 and 38, their vapours are in single groups of four atoms each, probably in tetrahedrons, rendering them isomorphous. It is well known that experiment bears out these mathe- matical conclusions. Prop, 4. Things being as in the preceding propositions, and the tenacious atoms in a gaseous state compressed in an inner concentric spherical vessel, which contains tena- cious atoms, but admits a perfectly free communication to ethereal atoms ; then the pressure on the exterior vessel being given, the density of the gas will vary as the com- pressing force on the inner vessel. Let the inner vessel be V W P, having the same centre s, and let the tenacious atoms in it be compressed, as by a piston, at P, such, that it shall continue to retain the gaseous form. Then the internal pressure of the tenacious atoms on a given surface, and, consequently, the compressing force on the same, as on the piston P, will be as the number of pressing atoms, and as the force of each ; but the number of atoms on the given surface is inversely as the square of their distance (geom.), and the force of each is inversely as the distance (prop. 2) ; therefore, the compressing force is inversely as the cube of the distance, but the density is in that same ratio : therefore, the compressing force varies as the density. Cor. The volume varies inversely as the pressure, be- cause it varies inversely as the density. Def. The pressure at T answers to the effect of tempera- ture, and the pressure at P to that of the usual pressure on gases ; it arises from the re-action of the included tena- cious atoms ; hence, the first at T may be called the pres- sure of temperature, and the other at P, the pressure or re-action ; or, for conciseness, simply the pressure and the temperature. Prop. 5. The pressure or re-action at P, (fig. 1.) being given ; the volume will vary, as the pressure at T, or the temperature. For the volume being given, the temperature or pressure at T, will vary as the resulting force determined in prop. 2, because that is the sole cause which brings the forces into Mathematics to Chemistry. 279 operation ; but the pressure at P also varies as that resultant, because these forces sustain each other in equilibrium ; therefore, the pressure at P varies as that at T, when the volume is given ; but the pressure at P varies inversely as the volume, when that at T is given (prop. 4. cor.) ; there- fore, the pressure at P varies as that at T directly, and the volume inversely: therefore, when the pressure at P is given, the temperature varies as the volume. Cor. If any temperature T, and its corresponding volume V, be assumed, and v be the increment of one volume, for one degree of temperature, taken at T ; also t a given in- crement of temperature taken from the same term T ; then, T : T -f T ?; ^ :: V : V + V v ^ =V (1 + v 0=the volume at the temperature T + ^ ; which is known, when V, v, and t are given. This is a well known theorem, agreeing with experiment, Example, ifT = 32° Fahr. then ^ = 4L; let V =20, i = 30; then Y {\ + v t)= 20 x ~= 21-25 = V, the new 4oU , / . V volume: had V been given we should have had V=-; -— ^ 1+ tv = >,-7r = 20, in this case, the volume at 32° Fahr. Prop. 6. If ethereal and electric atoms be compressed in a vessel, fig. 1. the pressure and temperature being given, and also the absolute force of a tenacious atom in it, while its sphere of repulsion is supposed to vary ; then there will be a certain magnitude in its sphere of repulsion, at which it will collect and retain a maximum quantity of electric atoms on its surface of repulsion. For, 1st, let the sphere of repulsion be extremely small, then the attraction at the surface is very great, (1st. prin.) therefore, the density of the ethereal matter at the surface is very great, (prop. 1.), and, therefore, the electric atoms at the surface obtain an increased atmospherule of ethereal matter (prop. 1, cor.); hence, the relative attraction of the tenacious and electric atoms is diminished, by their united actions on the adjacent ethereal matter ; and this conjoined with the extremely small surface of repulsion will operate against the firm attachment of the electric atoms, which 280 Mr, Exleys Application of will, therefore, the more readily pass oft' to other neigh- bouring tenacious atoms. 2nd. Next, let the radius of the sphere of repulsion be very large; then at the surface of repulsion, the force is very small, and the electric atoms are, therefore, loosely retained ; and, hence, will on a disturbance of the equili- brium pass off" to other tenacious atoms, having their abso- lute forces and spheres of repulsion better proportioned to retain them. From these two parts, it follows, that when the absolute force of the atom is given, there is a certain magnitude of the sphere of repulsion, at which it will retain a maximum quantity of the electric atoms. Cor, 1. When the pressure and temperature are given, there is a fixed and definite relation between the tenacious atoms of bodies, and those of the electric fluid attached to them, as to quantity. Cor, 2. When the temperature is varied, the relation between the tenacious and the electric atoms, is in some degree altered. For the densities of the ethereal atmospherules will be varied in different ratios, on account of the difference in their spheres of repulsion. Cor. 3. From this it appears, that a variation of the temperature will alter the electrical relations of elements, and, consequently, their tendency to combine. Prop. 7. When the elements of bodies combine chemi- cally ; the ratios by weight of the quantities are fixed and definite, and such as may be expressed in small whole numbers. Since tenacious atoms in common circumstances, are always situated in a compressed body of ethereal matter ; they will be encompassed by distinct atmospherules (prop. 1.) : this evidently tends to keep them apart; and, hence, there can be no combination, unless either one or more of the atoms or groups penetrate the atmospherule of the other, so as to form a single group : or that the atoms are connected by some intermediate link, as either another atom, or intervening electric atoms, which may collect between them (prop. 1, and cor.). When this change is effected, the new particle will be invested with a distinct Mathematics to Chemistry. 281 common atmospherule, (prop. 3 and I,)*- hence, if it can combine with an additional quantity of the same element, it will be with another atom or group, half an atom being impossible ; after the compound has attained a certain state or quantity, it will not in general, on account of the mu- tual actions of the combined atoms and the ethereal matter, be in a condition to enter into new combinations, except by cohesion, or by the expulsion of some of its elements: hence, the proposition is manifest. Prop. 8. Taking each elementary atom as representative of a volume ; then in all strictly chemical combinations, that is, whenever- there is a condensation, the resulting volume is always, without exception, either one or two volumes exactly, whatever number of volumes combine. For, since the volume is diminished, the centre of some atom, or those of several atoms, have penetrated the atmos- pherule of some other (prop. 3 and cors.) 1 . When the atmospherule of one atom or single group is penetrated by the centres of all the other atoms, the result is a single group, and, consequently, (prop. 3 and cors.) that result will be one volume exactly. 2. When one atom or single group combines with a single group, and all the centres do not rest within the spere of repulsion of one of them ; then one or more of the atoms will be brought, by their mutual actions, to the in- terval between the remaining atoms or single groups, "which combine, and so situated, will (prop. 3 and cors.) supply the effect of the ethereal matter which it displaces ; and the whole will form a double group, and (same cors.) will become two volumes exactly. 3. When one atom, or single group combines with a double group ; the centres of the combining atoms of the single group, or that of the single atom, will penetrate the atmospherule of the double group ; otherwise there would be only a cohesive combination ; hence, the whole when combined will continue a double group, and will form exactly two volumes (prop. 3, cor. 3) ; except when the mutual actions bring all the centres within the sphere of repulsion of one of them, in which case, (prop. 3, cor. 1) they will become one volume : hence, still we shall have either a single or double group, so that evidently no other 282 Mr. Exleys Application of case can occur : therefore, the resulting volume will be always exactly one or two, however, many volumes com- bine. Cor. This proposition embraced the theory of volumes, which it explains, simplifies, and extends. The important law contained in this proposition, in its whole extent, has not been before determined, although approaches towards it have been made in the theory of volumes : and after Gay Lussac had discovered that theory, a striking relation between the atomic weights of bodies, in the gaseous form, and their specific gravities could not long remain unobserved ; and this was particularly noticed by Dr. Prout; but the exact and remarkable law just de- monstrated, has, I believe, never been made clearly out in its generality, but many particular cases have been esta- blished. As far as experiments go they serve to confirm the above mathematical conclusion ; and this demonstra- tion would not have been the less valuable, had the law been established in its full extent by observation of facts : for even in that case, it could havebeen received only as an ultimate fact utterly inexplicable. From this proposition and the new theory, we have the farther advantage of knowing in what manner the atoms may be combined : and that frequently the combinations of the same atoms admit of different forms, producing isomeric bodies: also the manner of combining being given, the theory foretells perfectly the resulting volume. Having deduced this exact law from my two simple prin- ciples, it became to me exceedingly important to ascertain if this result is really true in fact. To determine this point, I have calculated from this law the specific gravities of a great number of compounds supposed to be in the gaseous form, having regard to the combinations as to their being only cohesive, or in single or double groups, and in doubtful cases, calculating the specific gravity both on the supposition of single, and that of double groups. I then collected all the substances I could find of which the specific gravities had been determined by experiment, and have put them to the amount of 57, in a tabular form, from which it appears that there is a complete agreement within the allowable errors of such experiments, except in boro- Mathematics to Chemistry, 283 chloric acid, which Dr. Thomson says requires farther investigation, and besides a small discrepancy in oil of turpentine, a substance not easily obtained in a perfect state; so that the rule appears to be without exception. The calculations are evidently easy and simple ; all that is required, is to add together the atomic weights of the simple elements contained in the compound, and multiply the sum by '0694 the specific gravity of hydrogen, which gives the specific gravity required, when the elements combine in single'groups, and half that product is the specific gravity, when the combination is in double groups : but when there is only a cohesive combination, the same product is to be divided by the number of elements which combine. These three are the only varieties of chemical combination which can occur. Fig. 2. ri^s. .'»•?. Fig. 5. Fig. 6. A cohesive combination is represented in fig. 3, one in single groups in fig. 4, and one in double groups in fig. 5, 284 Mr. Exleys Application of and also in fig. 6. A mixture of hydrogen and chlorine in equal parts is represented in fig. 2, the chlorine C having a dense stratum of electric atoms, and H only a few of these ; the circles denote limits of the spheres of repulsion which may be more or less ; the absolute force of C is 36 times greater than that of H, but probably its sphere of repulsion is less ; the atmospherule of C will be more dense, but the two will occupy equal spaces in the gas. While the gas is perfectly still, and not acted on from external causes, the mixture will continue a long time ; but, the equilibrium of the electric atoms not being a stable one, when caloric, or light, &c., has access, the effect will be to bring the electric atoms between C and H, (prop. 1,) and the accumulation of part of them there will increase the effect on the rest ; these electric atoms will then form an intermediate link, and hold C and H under one common atmospherule, forming muriatic acid as in fig. 3, where the centres C H' are at the same distance as before. I believe no other theory can give any rational account of these phenomena. By supposing variations in the absolute force and sphere of repulsion, fig. 3 may represent any of the first five compounds in the table. Etherine is shewn in fig. 4; there are two atoms of carbon with small, and four of hydrogen with large spheres of repulsion, the six centres being within the sphere of repulsion of the hydrogen, the whole occupies but one volume (prop. 3. cors). This is isomeric with olefiant gas, whose atom would be represented by one of carbon and two of hydrogen. Fig. 5 represents all the compounds in the table, from number 26 to 33 inclusive, by supposing only an alteration in the absolute force and sphere of repulsion. Fig. 6 represents ether, it is two of fig. 4, connected by fig. 5. The connecting atom in fig. 5, and the connecting group in fig. 6, while they retain the whole under one atmospherule, and bind them together, do not (prop. 3. cors.) alter the distance between the atoms or groups which they connect. In the original communication a figure was given for every compound in the table. Mathematics to Chemistry. 285 A Table Containing the Three Varieties of Chemical Compounds. I. COHESIVE COMBINATIONS. Elementary Atoms. Wtof comp. atom. Vol l'y& Sp. gr. air - 1. Name. Number. Weight. ByCal. By Exper. Authority. 1. Carbonic oxide 2. Nitric oxide 3. Muriatic acid C + o N-h O CI + H 12-4-16 16 + 16 36 + 1 28 30 37 2 2 2 14 15 18| •972 1-041 1-284 •973 1^037 1-248 Thenard. Ditto. Biot& Arago 4. Hydrobromic Br + H 80+1 81 2 40i 2-812 2-731 Turner. 5. Hydriodic acid I + H 126 + 1 127 2 63J 4-409 4-443 Gay Lussac. 6. Bisulphuret of mercury 7. Common air S+2M 32 + 200 232 3 77i 5-370 5-384 Dumas. OH-4N 16+56 72 5 14f 1- 1- The assumed unit. II. CHEMICAL COMBINATIONS IN SINGLB GROUPS. Name. Elementary Atoms. Wtof comp- atom. Vol l%fu Sp. gr. air— 1. Number. Weight. By Cal. By Exper. Authority. 8. Cyanogen N + C 14 + 12 26 26 1-805 1-806 Gay Lussac. 9. Bichloride of sulphur 10. Fluoboric acid S+Cl F + B 32+36 18 + 16 68 34 1 68 34 4-722 2-361 4-70 2-360 Dumas. Davy. 11. Biniodide of mercury 12. Bichloride of mercury I + Hg Cl + Hg 126+100 36+100 226 136 226 136 15-694 9-444 15-67 9-440 Mitscherlich. Ditto. 13. Bibromide of mercury 14. Olefiant gas 15. Fluosilicic acid 16. Chloride of silicon Br + Hg C + 2H Si + 2F Si + 2 CI 80+100 12+2 16+36 16+72 180 14 52 88 1 180 14 52 88 12-500 -972 3-611 6-111 12-360 -978 3-600 5-939 Ditto. Henry. Thomson. Dumas. 17. Nitrous a cid N + 20 14 + 32 46 46 3-194 3-177 Gay Lussac. 18. Hydrocarburet of chlorine Cl + (C+2H) 36+14 50 50 3-472 3-443 Ditto. 19. Etherine 20. Bicarburet of hydrogen 21. Naphtha 22. Napthaline 23. Camphene 24. Oilof turpentn. 25. Arsenious acid 2 C + 4 H 3C + 3H 24+4 36+3 28 39 28 39 1-944 2-708 1-91 2^776 Faraday. Ditto. 3C + 5H 5C + 4H 5C + 8 H 6C + 8 H 4 As + 3 O 36+5 60+4 60+8 72+8 152+48 41 64 68 80 200 1 41 64 80 200 2-847 4-444 4-722 5-555 13-888 2-833 4-528 4-767 5-013 13-67 Saussure. Dumas. Ditto. Gay Lussac. Dumas. 286 Mr. Bxleys Application of III. CHEMICAL COMBINATIONS IN DOUBLE GROUPS. Name. 26. Water 27. Sulphuretted hydrogen 28. Carbonic acid 29. Sulphur, acid 30. Chloride of sul. 31. Nitrous oxide 32. Bisulphuret of carbon 33. Borochloric acid 34. Deutoxide of chlorine 35. Protochloride of mercury 36.Bromide of mer. 37. Hydrocyanic acid 38. Chlorocyanic acid 39. Ammonia 40. Sulphuric acid 41. Inflam. gas of Dr. Thomson.* 42. Phosphoretted hydrogen 43. Arsenuretted hydrogen 44. Chloride of phosphorus 45. Chloride of arsenic 46. Perchloride of tin 47. Light carbu- retted hyd. 48. Perchloride of titanium 49. Perphosphu- retted hyd. 50. Alcohol 51. Oil gas 52. Ether 53. Muriatic ether 54. Hydriodic ether 65. Citrene 56. Paranapthaline 57.Chloro- carbonic acid. Elementary Atoms. Number. O +2H S + 2H C + 20 S + 20 S + 2C1 0 + 2N C + 2 S B + 2C1 CI + 20 CH-2Hg Br + 2 Hg H + (N+C) C1 + (N+C) N -1-3H S + 30 cC-i-2H) + 3Cl 2P-f-3H 2As+ 3H 2 P + 3 CI 2 As + 3C1 Tn + 4 CI CH-4H Ti -f 4 CI 3P+ 3H Aq + 2 olef. 3C + 6H Aq + 2 eth. M + Cl+2olef H + I+2olef. 5C + 8H 15 C H- 12 H 2Cl+(0 + C) Weight. 16+2 32+2 12+32 32+32 32+72 16+28 12+64 16+72 36+32 36+200236 80+200280 1+26 Wtof comp. atom. 18 34 44 64 104 44 76 88 68 36+26 14+3 32+48 14+108 32+3 76+3 32+108 76+108 116+144 12+4 52+144 48+3 18+28 36+6 18+56 37+28 127+28 60+8 180+12 72+28 27 62' 17 80 122 35 79 140 184 260 16 196 51 46 42 74 65 155 68 192 100 ISp. gr, Vol hyd 51 Sp.gr. air ^1 By Gal. jBy Exper 17 22 32 52 22 38 44 34 118 140 13J 31 81 40 61 171 •625 1-180 1-527 2-222 3-611 1-527 2-638 2-644 3055 3-942 •628 1-19 1-519 2-255 3-67 1-522 Authority. 70 92 130 8 98 25J 23 21 37 324 77-j 34 96 50 2-361 8-194 9-722 •937 2152 •590 2-777 4-236 1-215 2-743 4-861 6-388 9-027 •555 6-805 1-770 1-597 1-458 2-569 2-256 5-381 2-361 6-666 3-472 2-346 8-20 9-665 •947 2153 -597 3-000 4-175 1-214 2-695 4-875 6-300 9-199 •559 6-856 1-761 Gay Lussac. Thenard. Ditto. Berzelius. Dumas. Thenard. Gay Lussac. Dumas. Thenard. Mitscherlich, Ditto. Gay Lussac. Dumas. Biot& Arag( Mitscherlich Thomson. Dumas. Ditto. Ditto. Ditto. Ditto. Henry. Dumas. Ditto. 1-613 1-458 2-586 2-219 5-474 2-383 6-741 3-472 Gay Lussac, Henry. Gay Lussaci Thenard. Gay LussaCi Dumas. Ditto. Henry. • Sesquichloride of carbydrogen, a compound which Dumas, as too often happens at present, re-dis- tovered 11 years subsequent to Dr. Thomson, and hus termed its basis methylene, instead of carbydrogeu. —Edit. Mathematics to Chemistry, 287 In attending a little to the preceding table, we observe that there are combinations of 2, 3, 4, 6, 7, 8, 9, 13 and 14 atoms or volumes, occupying exactly the space or volume originally occupied by one of them : this theory shows how this can be, but it will not be pretended that any other theory can show the manner of the composition ; so many solids cannot possess the space of one of them. The cir- cumstances are still more remarkable in double groups : in etherine 15 volumes make exactly two ; in alcohol 9 volumes make two ; in camphene 13 volumes, and in paranaphthaline 27 volumes make exactly two; and in these apparently complex cases, there is the same sim- plicity of composition as in that of water ; this is seen in fig. 5 which represents water, and in fig. 6 which repre- sents ether. Thomas Exley. Bristol, September 7th, 1836. It may be added, that this theory was not formed in re- ference to chemistry, or other science, but electricity. It occured to the author while attempting to explain electrical phenomena ; and it was not till he applied it with success to explain electrical attraction and repulsion, that he de- termined to publish any thing on the subject. He soon found that these principles were sufficient to solve all the phenomena he could collect relating to common electricity. Those of galvanism yielded with the same facility when relat- ing to the excitation, the current, the quantity, the intensity, the decomposition of bodies, or the transfer of elements, &c. In magnetism he scarcely expected to overcome the diffi- culties of the subject ; his only hope was, that he knew his principles were correct; and he soon ascertained, that every phenomenon in magnetism, whether relating to that of the earth, the motion of its poles, &;c., or to that of magnetic bodies, communication of magnetism, &c. yielded to the influence of his two simple principles, which, also, with great facility applied equally to the phenomena of electro-magnetism . When he published his first treatise, or " New Theory of Physics," he had scarcely turned his attention to the modern discoveries in optics, such as polarization, &c.; and, of course, could not see the application to these subjects. 288 Mr. Charles Tomlinson on But, after studying the phenomena, he found the same principles equally available, even so much so, that they embraced all that is true, both in the theory of Nevi^ton and that of Huygens, for they include the undulatory theory when stripped of its redundancies and deficiencies. In consequence of this, the author published his ** Physical Optics," — only a fevr copies of these works remain in the author's hands. When they were published, he was not in possession of the demonstrations contained in this paper. He submits, in a special manner, that of the 2nd prop, to the notice of the mathematician ; if this maintain its ground, the theory cannot be shaken. The author is per- suaded that it is impregnable. The present application of the principles to chemistry is a farther confirmation of its truth, if such were needed ; for in this short paper impor- tant phenomena are clearly explained, which the combined efforts of all the philosophers of Europe, during the last and the present century, have not been able to solve or unfold. Thomas Exley. Bristol, September 7th, 1836. Article IV. A Theory of Accidental and Complementary Colours. By Charles Tomlinson, Esq. {Concluded from p. 217.) ON COLOURED SHADOWS. 17. Dr. Thomas Young, in his lectures on Natural Philosophy, vol. i., p. 456, states that " when the shadows of objects are placed in coloured light, the shadow appears of a colour opposite to that of the stronger light, even when it is in reality illuminated by a fainter light of the same colour." This he explains on the assumption that the eye cannot perfectly distinguish the intensity of a colour, either when the light is extremely faint or exces- sively vivid. This explanation, if such it be, I cannot adopt ; because, I think it entirely inadequate to account for the phenomena of coloured shadows. 18. Independently of the theory of coloured shadows, there is an important principle established by their investi- gation, and admitted by Dr. Young, viz., that every shadow Accidental and Complementary Colours. 289 becomes complementary in colour to the light into which it falls. I am not aware that this proposition is in any way exceptionable, for although shadows cast by the sun and by strong artificial lights are said to be black, and in some cases they certainly appear so, it is because our usual criterion is simple and imperfect, namely contrast. The unaccustomed eye is wont to view a shadow solely with reference to the surrounding light, and, as decreasing light conve3^s more or less to the mind impressions of obscurity or darkness, the depth of every shadow of course depends upon the greater or less absence of surrounding light. So far Dr. Young's remark applies, but it explains nothing of the principle that a shadow falling into coloured light assumes an opposite tint. This principle has been long recognized in practice, for the shadows in the pictures of the old masters are never black, but are variously coloured as circumstances or rather as Nature requires. The only black shadow that we ought I think to conceive is that cast by perfectly white light, passing through a perfectly transparent, colourless medium, and falling upon white ground ; the shadow, in such a case, were it possible to obtain such perfection of observation, would probably be not black but grayish, from the admixture of a small quantity of white light with the black of the shadow. The solar rays passing through the blue aether acquire a yellowish tinge, and their shadows are generally blue of indigo, unless intercepted by the splendidly tinted clouds of morn or eve, which transmit light of their own peculiar colours, and afford shadows of opposite tints to themselves, and these colours vary in intensity and hue as the altitude of the sun varies, and are again modified by the colour of the ground upon which they fall. The effect of early morn is, as artists term it, cold, when the tints and shades gradually merge from gray and pass through various admixtures of yellow, green and blue, into indigo ; which latter, during the day deepens into an apparent black, until evening brings its warm effects ; the yellow merges into orange from the abundance of red rays, and the red, dark purple and indigo, with their oppositely tinted shades always modified by the ground upon which they fall, con- tribute to impart that richness or mellowness to the land- VOL. IV. u 290 Mr. Charles Tomlimon on scape, the successful imitation of which constitutes good painting. As the shadows of evening lengthen, they will generally be found to be indigo, if received upon white ground. Twilight, assisted by moderate artificial light, is a very favourable time for observing the coloured shadows and opposite tints of nature. By night the shadows cast by artificial lights are seldom capable of being estimated as to colour on account of their intensity, but by twilight they are distinctly seen to be either blue or indigo, and sometimes purple. By the yellow light of a lamp just after sunset, the sky, as seen through the window, is of a very rich indigo : if a sheet of white paper be so arranged as to receive the light of the lamp, and at the same time the natural light from the window, and the finger or other object held so as to throw a shadow upon the paper, two shadows will be obtained, one of bright yellow and the other of a rich indigo : this is a simple and familiar instance of coloured shadows and admits of easy explanation. The paper is illuminated by the yellow rays of the lamp and at the same time by indigo rays from the sky : the former by their intensity and abundance overcome the latter and the paper appears yellow ; a shadow cast by the lamp deprives that portion of the paper occupied by such shadow of the yellow rays; the shadow is therefore illumined by the indigo rays of the sky. A converse arrangement will account for the appearance of the yellow shadow, which is cast not by the lamp but by the natural light which falls upon the ground, illuminated by artificial yellow light and natural indigo light, except where the yellow shadow appears, for there the indigo is intercepted by the opaque object. 19. The means of obtaining coloured light are various, and may be arranged into four classes ; thus. Class \st. The colours of the spectrum. ,, 2nd. Transparent coloured media. ,, Zrd. Coloured flames. ,, Ath. Light reflected from polished coloured surfaces. 20. Class Ut. On receiving a large and well defined spectrum upon a white screen, or upon the white ceiling of a room, and intercepting a portion of each of the colorific rays in succession, by means of a long narrow strip of white Accidental and Complementary Colours. 291 card, or a similar object, the resulting shadow will be com- plementary to the colour of that part of the spectrum whereon the shadow falls; mingled, however, with a small portion of natural light which imparts a grayish hue to the colour of the shadow : but the result is decided and con- clusive. The most refrangible colours are best adapted to the reception of the shadow, as the illuminating power is smaller, and the space occupied by the colour larger, so that the contrast between the fundamental and comple- mentary colours is more readily observed. In the less refrangible colours, the illuminating colour being great, and the space occupied comparatively small, the shadows appear very dark, and sometimes too deep for correct observation of their colour. If the spectrum then be too vivid, it, or portions of it, in succession, may be received upon a plane mirror, and so reflected upon the ceiling, or upon a white screen. The colours become less vivid by reflection, and the shadows consequently more appreciable. 21. Class 2nd. Coloured glass of every shade and depth of shade, provided light can be transmitted through it, may be employed. If a coloured disk be held before a lamp, or any strong source of light, and the coloured light fall upon white paper, a shadow formed by intercepting a portion of the light will be complementary to the colour of the disk. Coloured solutions contained in an oblong glass frame may be employed, and even vapours such as chlorine, iodine, nitrous acid, &c. The stains of the glass, must not, however, be too light, because, as shadows are judged of by contrast, the comple- mentary shadow will appear too dark for the observation of its colour : but this may be remedied by employing two or three thicknesses of glass. Interesting results may be obtained by transmitting light through pairs of disks of different colours, — the accidental colour of each being, of course, modified or changed by such means : thus, green glass transmits green light, a shadow falling into it is pink. The same pink shadow may be produced by passing a light through a yellow and blue disk placed the one upon the other; and so on. One of my methods of exhibiting coloured shadows to an u2 '292 Mr, Charles Tomlinson on audience is as follows : my lecture room is illuminated by a branch of two gas lights. A large screen is placed six or seven feet from, and parallel to the gas lights. One of the gas lights is provided with a small wire frame fitted for the reception of a piece of stained glass ; the screen is thus illuminated by the coloured light, and also by the other burner — two separate shadows of the body, or any opaque object, are therefore cast, the one being complementary to the other.''^ In this class may also be included coloured silks, moreens, cottons, (fee, provided they are sufficiently thin, (or the illuminating object sufficiently intense) to transmit the light either of the sun or of an argand lamp. Windows provided with red moreen curtains present favourable opportunities for observation : if the sun be shining on the window, and these curtains be drawn, a quantity of red light will illuminate the ceiling, and a shadow falling upon it will be green. So also in Mons. Meusnier's experiment, where the sun shone through a hole in a red curtain, the image of the luminous spot was green. If green, blue, yellow, &:c. curtains be employed, the spots will be red, orange, indigo, &;c. A disk of coloured glass with a hole in the centre is an interesting and useful article for experi- ments of this kind, the glass being easily pierced by means of a common awl kept well moistened with oil of tur- pentine. 22. Class 3rd. The flames employed have been the white, red, green, blue, purple and yellow fires, and signal lights ; as also the less vivid, but equally efficacious, flames obtained by solutions of the various salts in alcohol. In most cases, the colours of the flames are not homogeneous, and the complementary shadows are modified more or less, by the presence of other colorific rays ; but where one colour is in considerable excess, there is no difficulty in procuring the complementary shadows. I have adopted a very useful mode of testing the true colour of the shadow, * The advantage of this arrangement is, that the shadows are of a size sufficient for a large audience to judge of and appreciate. It is obvious, that a similar arrangement can be adopted with two lamps, or two candles. There must be two sources of light, one of which is to afford coloured light, and tlie other to illuminate the coloured shadow. Accidental and Complementary Colours. 293 by receiving it first upon white paper, and then upon coloured paper; as, for example, boracic acid in alcohol yields a fine light green flame, the shadow is pink on white ground, violet on blue ground, orange on yellow, &c. If a sheet of white paper be held before the red light from a coke fire, and the hand be placed between the paper and the fire, the resulting shadow will be green. On a dull day, or just after sunset, a coke fire or the red part of a coal fire throws green shadows in various parts of the room. A w^hite screen placed parallel with the window, the fire being between, is an excellent ground for the reception of the shadows. Chairs, or any opaque objects, the shadows of which are cast by the fire upon the screen, are strongly green. This, and most of the observations with coloured flames are most conveniently made immediately after sun- set, or in a somewhat obscure room, or part of a room, as the abundant presence of day light prevents the shadows being appreciated. A little flat dish, containing the salt in spirit, should be placed on white ground, and the shadow of the dish will be complementary in colour to that of the flame. Or, a sheet of white paper may be held between the eye of the observer and the flame, and the hand or fingers between the flame and the white paper. If very vivid flames be required, equal parts of chlorate of potassa and white sugar may be employed mingled with one part of a salt which communicates colour to the flame, such as the muriates of barytes, strontia, soda, lime, &c. The in- gredients should be well dried, and intimately mixed in a mortar. A drop or two of sulphuric acid will fire the mix- ture. This mode of impressing the eye is a pleasing one. I have found the spectra to be very different with different persons, and the impression on the retina lasts from two to three minutes. Flames may also be obtained from gases, such as carbonic oxide, equal parts of hydrogen and binoxide of nitrogen, cyanogen, &;c. The purple flame of potassium upon water may be employed, and if the metal be thrown into ajar of carbonic acid standing over water, it will yield a fine ruby, which is almost homogeneous. 23. Class ^th. When a polished coloured surface is pre- sented in an inclined position to the light, so that the coloured rays proceeding from the surface be reflected upon 294 Mr. Charles Tomlinson on white paper, a shadow formed by intercepting a portion of the coloured reflected light, will be the accidental colour of that light. Surfaces of burnished gold, polished copper, silver, steel, brass, &c., are instances, as also bright coloured varnished papers. These methods are, however, imperfect. 24. From what has been already stated of my theory, its application to coloured shadows will be readily perceived. If white ground be illuminated by coloured light, natural light being also present, a shadow introduced occupies a portion of the white ground, which would otherwise be coloured, and we see the shadow white, with the exception of the colour which illuminates the ground. Thus, if the source of coloured light be a green flame, and a sheet of paper be placed so that it be illuminated by the green flame, and at the same time by light from a second source inde- pendent of the first, an opaque object placed between the flame and the paper intercepts a portion of the former, and restores that part of the paper occupied by the shadow to its original whiteness ; but this shadow which would be white is surrounded by green, which, according to the principle of homo-chromatic attraction, absorbs green from the white shadow, and red, therefore, alone remains. 25. Coloured shadows cannot be produced, unless other light be present than the coloured light which illuminates the paper. Thus, when Brewster's mono-chromatic lamp is employed in an apartment where there are no other sources of light, no accidental shadows are obtained. The pale blue or indigo flame aff'orded by pure carbonic oxide may be made to illuminate a sheet of white paper, but if the room be deprived of all other light, it is in vain that we attempt to produce the accidental shadow. These facts eminently support, I think, the theory I have propounded. A sheet of white paper is no longer white if illuminated only by coloured light : the paper must evidently reflect rays to the eye identical with those whence it receives light, which is, we suppose, in this case, a coloured flame. A shadow formed upon the paper, by intercepting a portion of the light of such flame, is evidently a deprivation of light and nothing more. Hence, such a shadow, if not black, is, at least, very dark, and can have no colour. If now we Accidental and Complementary Colours. 295 admit to the paper light from a second source, not coloured, the paper will be again in a condition to reflect white light, were it not that the artificial coloured light overpowers the light from the second source. A shadow formed by inter- cepting a portion of the coloured light upon white ground was black, in the absence of light from the second source now becomes white from the presence of the latter ; or rather, that portion of the ground occupied by the shadow, is restored to its original whiteness. Homo-chromatic attraction proceeds between the colours of the same kind in the shadow and the coloured ground which encompasses it; while the colour or colours of an unlike kind are not attracted but repelled or reflected, and constitute the accidental impression. 26. The conditions, therefore, necessary to the production of coloured shadows are, 1st. That there be two sources of light. 2nd. That the first source of light be coloured. 3rd. That the second source of light be not coloured, and not more than equal in intensity to the first. 27. Most of the experiments in this and the preceding papers are so decided and are performed so easily and so readily, that it cannot be urged that " the diminished sen- sibility of the eye from fatigue," or from any other cause, produces the effects. I deny that it has any thing to do with the production of these eff'ects, for, I believe, that the performance of any one of the experiments contained in these papers does not occupy more than a second of time. I agree with Mr. Cooper, that *' the colours are produced with a facility which those who are not familiar with the subject are not prepared to expect." {Records, vol. ii, p. 178.) Mr. Cooper, also, in making an experiment in order to determine the shortest time in which an accidental colour could be obtained, found it to occupy less than a second. Mr. Cooper also says, *' we cannot attribute the appearance of accidental colours to insensibility of the eye arising from fatigue or exhaustion. Brewster also {Optics, p. 309) admits that a new theory of accidental colours is requisite to explain the phenomena of coloured shadows. There are no less than nine distinct theories of accidental 296 Ml'. Charles Tomlinson on colours, and if 1 include the theories which seek to explain coloured shadows, Sec, the number will be nearly doubled. It unfortunately happens, too, that each class of facts has its own theory or theories attached to it, and the great fault of all, including M. Plateau's, is the want both of simplicity and comprehensiveness. If the theory that I propose has any merit it is that of being very simple, and at the same time it comprehends all existing facts, as far as I am aware, (except those facts which belong to and are explained by polarization,) for the more these various phenomena are studied, the stronger, I am sure, will be the conviction that they are all due to one cause, or analogous causes, and must and ought to be explained by one theory. 28. In these two papers I have assumed that white light is composed of red, yellow and blue, one or more of which colours, by itself, or by combination, in various definite proportions, produce all the ordinary effects of colour. I have endeavoured to establish the following propo- sitions : 1st. That two colours are complementary to each other, when, from a combination by direct impression, white is produced ; and by superposition, black. Thus, if a disk be divided into two parts, one painted red and the other green, and the disk be rapidly rotated, the colours will combine and produce white. This is an instance of combination from direct impression. If we view red lead through a disk of green glass the red powder will appear as black as lamp black. This is an instance of combination by superposition. 2nd. That if the fundamental colour be simple, the com- plementary colour is compound ; and if the complementary colour is simple, then the primary or fundamental colour is compound ; but in certain cases both the fundamental and complementary colours are compound, but never simple, (See table 6.) 3rd. That white light in passing through coloured trans- parent media is decomposed, the second surface of such media reflecting rays of the same colour as the medium itself, and the first surface reflecting the other rays, which. Accidental and Complementary Colours. 297 combined with those of the second surface, produce white light. 4th. That an attraction and repulsion exists between colours. Colours of a like kind attract each other, and those of an unlike kind repel each other. Thus, when a coloured object is placed on a white ground, the colour of such object attracts the rays of the same colour as itself from the contiguous white ground, and leaves a portion of the latter of the complementary tint. 5th. Hence, the theory of accidental and complementary colours, which may be included in the following proposi- tion, viz. : That a coloured body has the power of decomposing white light ; of attracting and retaining rays of a like kind to itself; and the other rays, which it repels, constitute the accidental or complementary impression. Charles Tomlinson. Brown Street, Salisbury, December, 1835. Article V. Economical Mode of forming Hyper-manganate of Potash. By William Gregory, M. D., F. R. S. E., Lecturer on Chemistry, Edinburgh. {To the Editor of the Records of General Science.) Sir, — Observing in the Records of General Science, for September, 1836, part of a memoir by Professor Mitscher- lich, on the Manganic and Hyper-manganic Acids and their Salts, it has occurred to me, that your readers may like to be acquainted with the following easy and economical method of obtaining the most remarkable of these com- pounds, the hyper-manganate of potash. My process is a modification of that of Wohler, who re- commends to melt chlorate of potash along with caustic potash in a platinum crucible, and to add peroxide of man- ganese to the fused mass. There are several objections to this process. In the first place, the melted mass froths up violently when the last portions of oxygen escape, so that we can only employ a small quantity of materials, even in a pretty large crucible. 298 Dr. W. Gregory s Economical Mode of 2ndly. I find that with less than 1 atom of chlorate to 1 of each of the other ingredients, the mass cannot be kept fused, and, consequently, the mixture is imperfect. 3rdly. From the large proportion of chlorate employed, a corre- sponding quantity of chloride of potassium is left, which interferes with the subsequent purification of the hyper- mangate of potash; and, lastly, since 1 atom of chlorate of potash loses 6 of oxygen by heat, while 1 of binoxide of manganese requires only 1 of oxygen to convert it into manganic acid (the change which occurs in this stage of the process,) we lose f ths of the oxygen. After many trials, I found the following process to answer remarkably well. Take of binoxide of manganese, 132 parts (3 atoms) of fused potash 147 parts (3 atoms), chlorate of potash 124 parts (1 atom). Dissolve the potash in a very small quan- tity of water, and add to the solution the oxide and the salt, previously in fine powder. Mix intimately so as to form a thin paste, which dry up and pulverize finely. Introduce the powder into a platinum crucible, (which may be filled, as there is neither melting nor frothing), and expose the whole for half an hour to a very low red heat. By this the production of the green manganate of potash which had taken place to a considerable extent during the exsiccation, is completed; while any hyper-chlorate of potash which may have been formed is destroyed. The green mass, a mixture of manganate of potash and chloride of potassium, is easily detached from the crucible. It is to be dissolved in a very large quantity of hot water, and when the solution has acquired a pure red colour, it is to be decanted from the hydrated binoxide, the formation of which accompanies the change of manganate into hyper- manganate of potash. The clear solution, evaporated rapidly until crystals appear, deposits on cooling a number of small crystals nearly black. These are to be washed with a little cold water, dissolved in a small quantity of hot water, and this solution, on cooling, yields crystals of the hyper-manganate of potash, chemically pure, and often -\ of an inch long. They have a fine bronze colour, and metallic lustre, and their solution in water possesses the most superb purple colour. I have always obtained, by forming Hyper -manganate of Potash. 299 the above process, a quantity of crystals equal in weight to one-third of the oxide employed. The mother liquids, on the addition of sugar, yield a large quantity of hydrated peroxide, which, with that separated by decantation, is very well adapted for a new operation. In this process, while the chlorate is economized, and the quantity of hyper-man gan ate increased, that of the chloride of potassium is diminished, and only half of the oxygen is lost. I have no doubt, that, if the green mass be dissolved in a small quantity of cold water, and the solution evaporated in vacuo, the green manganate of potash may be obtained with equal facility. Where it is necessary to filter these solutions, as paper cannot be employed, I am in the habit of using a funnel, the throat of which is stopped with Asbestus, which answers the purpose perfectly. I have the honour to be, Your obedient Servant, WILLIAM GREGORY. 10, Ainslie Place, Edinburgh, September, 13th, 1836. Article VI. Analysis of Tartar Emetic. By Mr. Thomas Richardson. Mr. Phillip's analysis of this salt differing from Dr. Thomson's in the proportion of the water it contains, I was induced to repeat the experiments of the latter gentleman, employing the same specimen. The analysis was conducted in the following manner: 1. 25 grs. were heated for a considerable time, on the sand bath at the temperature of about 400° Fah. and lost 1*21 grs. or 4-84 per cent. 2. What remained was dissolved in water, and a current of sulphuretted hydrogen passed through the solution till all the antimony was thrown down. The precipitate, after being well washed and dried, weighed 13'3 grains. But 11 sesquisulphuret of antimony : 8 antimony :: 13-3 : 9*67 grs. = 11 '48 grs. oxide of antimony. 3. The liquid and washings from the above precipitate 300 Mr. Grahams Catalogue of Plants were carefully evaporated to dryness, and the residual salt weighed 13*23 grs. Knowing the composition of this salt or Bitartrate of Potash, we obtain the following result : Oxide of antimony . . . 45*92 Potash 12*80 Tartaric acid 35*25 Water . . ^ 4*84 98*81 Resolving these weights into atoms we have for the constituents of the salt, Oxide of antimony . . 4*83 = 2*26 atoms. Potash 2*13 = 1*00 „ Tartaric acid .... 4*27 = 200 „ Water 4*30 = 2*01 „ The result of Dr. Thomson's analysis was, 1*997 atom Tartaric acid. 1*92 atom protoxide of antimony. 1 atom potash. 2*139 atoms water. The mean of the two analyses as below, Oxide of antimony .... 2*12 Potash 1*00 Tartaric acid 1*96 Water 2.07 leaves no doubt as to the following being the true compo- sition of the salt : 2 atoms oxide of antimony . . 19*00 1 atom potash 600 2 atoms Tartaric acid .... 16*50 2 atoms water 2*25 43*75 Article VII. Catalogue of Plants Collected at Bombay. By John "Graham, Esq. {Concluded from page 198.) 309. Moraea ckinensis. 310. Mentha perilloides 311. Marsilea 4-folia Collected at Bombay. 301 312. Moms Indica. 313. Milhavia tomentosa. In gardens only. 314. Mesembryanthemum. ? Ditto. 315. Nyctanthes Arbor tristis. 316. Nicotiana Tabacurn. 317. Nerium Oleander. 318. ,, coronarium. -x 319. ,, coccineum. Rare. ( All cultivated as orna- 320. ,, antidysentericum. i menial plants. 321. ,, tinctorium. J 322. Nymphea lotus. 323. Nelurnbium speciosum. 324. Nauclea orientalis. 325. Oryza sativa. Common rice. 326. Ocimum sanctum. Planted at temples. 327. Ochna lucida. 328. Piper nigrum. In gardens. 329. Pladua virgata. 330. Plumbago rosea. 331. ,, Zeylonica. 332. Physalis angulata. 333. Plumeria acuminata. 334. Vev\\Aoc2i esculenta, Avery pretty twining plant; flowers during the rains. 335. VQYi\\2iOcymoides. 336. Polyanthus tuberosa. Cultivated in gardens ; worn by native women in their hair. 337. Parkinsonia aculeata. In gardens. 338. Poinciana pulcherrima. Common in gardens. It grows in abundance close to the caves of Ellora, near Aurungabad, but I suppose it has all been planted. 339. Portulaca oleracea. 340. V^i^'wim pyriferum. Grown in gardens. 341. Punica Granatum. Ditto. 342. Premna integrifolia. 343. Phlomis Indica. 344. Pedalium Murex. 345. Passiflora/(3?^i<^a. 346. „ laurifolia. r j j^^,. 347. ,, minima. ' 348. ,, alata-carnlea. 302 Mr. Grahams Catalogue of Plants 349. Pistia Stratiotes. 350. Pentapetes p^oewice«. In gardens. 351. Pterospermum acerifolium. 352. Phaseolus Mungo. 353. Polygonum glahrum, 354. Phyllanthus hacciformis 355. Pandanus odoratissimus, 356. Prenanthes sarmentosus. 357. Quisqualis Indica. In gardens. 358. Rhizophora Mangle. 359. Rosa. ? Several species in gardens. 360. Ricinus communis. 361. Ruellia Zeylonica. 362. Rottleria tinctoria. 363. Saccharum officinarum. Cultivated. 364. Smilax aspera. 365. Santalum album. 366. Solanum tuberosum. 367. ,, Igcopersicum. 368. ,, melongina. 369. ,, nigrum. 370. ,, jacquini. 371. Sterculia coZora^a. 372. ,, wre?25. 373. ,, foetida. Poon tree. Grows to a great height in Malabar ; masts are made of it. 374. Sphseranthus Indicus. 375. Sansevcera Zeylonica. 376. Sapindus emarginatus. ,, tetraphyllus. S17. Spondias Ami'a. 378. Sesamum Indicum. 379. SidsL populifolia. 380. Smithia sensitiva. 381. Spilanthes aiZ>a. 382. Salvadorapemca. 383. Stemodia ruderalis. 384. Tectona grandis. Teak tree. 385. Tamarix Indica. 386. Turnera ulmifolia. In gardens. 387. Tradescantia discolor. Ditto. Collected at Bombay. 303 388. Tradescantia cristata. 389. Triumfetta annua. 390. ThwnhQT^m grandiflora. In gardens. 391. Tamarindus //^^^c«. 392. Tagites patula. In gardens; worn by native women in their hair. 393. Trichosanthes Anguina. 394. Trophis aspera. 395. Terminalia Catappa. 396. ,, alata. 397. ,, Bellirica. 398. Tabernaemontana dichotoma, 399. Utricularia stellaris. 400. Ulmus integrifolia. Salsette. 401. Unona longifolia. 402. Vitis vinifera. In gardens. 403. Vitex trifolia. 404. Vernonia arborea. 405. Vernonia anthelmintica. 406. Verbena sativa. 407. ,, dichotoma. 408. Viscum compressum. 409. Vangueria spinosa. 410. ,, edulis. 411. Vitmannia eZZzp^zca. 412. Yucca gloriosa. 413. Zingiber officinale. 414. Ziziphus Jujuba. 415. Zinnia elegans. In gardens only. 416. Zesi Mays. Indian corn ; extensively cultivated. 417. Zapania nodiflora. Article VIII. Scientific Intelligence, &c. I. — British Association for the Advancement of Science."^ Section A. — mathematics and physics. President, Rev. W. Whewell. — Vice Presidents, Sir D. Brewster, Sir W. R. Hamilton. — Secretaries, Professor Forbes, W. S. Harris, * For these notices we are indebted to the Bristol Mirror, the Athenaeum, and other sources. 304 Scientific Intelligence, Sfc. Esq., F. W. Jerrard, l^sf^.— Committee y C. Babbage, Esq., F.R.S., F. Baily, Esq., Professor James Challis, Mr. Chatfield, Professor Me Cullagh, Robert W. Fox, Esq., William Frend, Esq., G. Jerrard, Esq., Professor Lloyd, J. W. Lubbock, Esq., Rev. Dr. Lloyd, Provost of Trinity College, Professor Moll, Rev. G. Peacock, Professor Rigaud, Professor Ritchie, John Robison, Esq., Professor Stevelly, H. F. Talbot, Esq., Professor Wheatstone. Monday, '22nd August. — 1. Report on a Rock Salt Len^. — Sir D. Brewster stated, that he had no regular report. Through the kindness of Dr. Trail he had obtained from Cheshire some large masses of rock salt, singularly transparent and homogeneous, and of great purity, likely to afford a concave lens of considerable magnitude. 2. 3Ir. LuhhocJts Report of Recent Discussions of Tide Observations. — From the discussion of the Liverpool tides, by Mr. Dessiou, he finds the diurnal inequality at Liverpool very consider- able. The errors of prediction, at Liverpool and London, being classified, the result obtained by Mr. Dessiou confirmed the influence of atmospheric pressure on the tides. The law of the intervals, when the discussion is instituted with reference to the transit immediately preceding the time of high water, whether at London, Liverpool, or Brest, depends partly on the phenomena as deducible from Bernouilli's equilibrium theory, and partly upon the law of the intervals between the moon's successive transits. The general conclusion of Mr. Lub- bock, from an adequate discussion of tide observations by Mr. Jones and Mr. Russell, is, that the equilibrium theory of Bernouilli satis- fies the phenomena nearly, if not quite, within the limits of the errors of the observations, and that it leaves little, if any thing, to be accounted for otherwise. Mr. Whewell observed, that it appeared from Mr. Bunt's calcu- lations, that though the observed laws of the tide at Bristol might be made to agree with Bernouilli's theory of equilibrium tides, by referring them to a certain anterior transit, so far as the changes due to paralax are concerned ; yet, that this anterior period is not the same for paralax as for declination ; so that there is no one anterior period which gives theoretical tides agreeing with the observed tides ; and, hence, the Bristol tides do not altogether, at present, appear to confirm the result obtained by Lubbock from the London tides. 3. Mr. Whewell reported respecting the Commitee appointed to fix the relative level of the land and sea, with a view to determin^- its permanence. He observed, that the Committee had not taken any practical steps for the purpose for which they were appointed, having found difficulties which required consideration ; but it was stated, that it was intended to prepare to re-appoint a Committee for this purpose, with instructions grounded upon the views at which the members of the Committee have arrived, namely : 1. To strike level lines for considerable distances along the land ; as, for example, from Bristol to Ilfracombe, and from Bristol to Lyme Regis, with great accuracy : the permanence of these two lines (independently of reference to the sea) would determine the permanence of the relative points. 2. To refer the extremeties of these lines to the sea at each extremity ; the tides at the extremeties being of any British Association. 305 different amount, the observations would decide whether a level line agrees with low water, mean water, or high water ; and, thus, what is the true level of the sea. 4. 3Ir. Luhboch then read a paper on the importance of forming new empirical tables for finding the moon's place. Although astro- nomical tables are sufficiently perfect for the general purposes^ of navigation, yet astronomers are not satisfied to rest here ; but desire to reach, by calculation and theory, a higher degree of accuracy, such as that obtained by the best instruments in fixed observatories. The most remarkable works on the theory of the Moon are, on account of their extent, those of M. M. Damoiseau and Plana. Those of M. Damoiseau's calculations are, howfver, in such a shape that it is almost impossible to verify them. M. Plana s work con- stitutes a new era, from the circumstance that the results are de- veloped according to the powers of the eccentricities, inclinations, _ &c., as also of the quantity in denoting the ratio of the sun's mean y[ motion to that of the moon ; otherwise the calculations are similar to those of M. Damoiseau and there exists, finally, a great difficulty, from the circumstance that the expressions for the co-efficients do not converge. Mr. Lubbock, from these aud other considerations, suggests the importance of deducing the numerical values empirically from the best observations, and so construct new lunar tables, which may serve to check the results obtained by theory. This resolves itself into a question of expense merely, since there are plenty of persons to be found adequate to the task of computing th^ proposed new tables. 5. Sir W. Hamilton was then called upon to give an account of the result of Mr. G. B. Jerrard's process for resolving equations of the fifth and sixth degrees. Professor H. reported that he conceived himself to have proved that, in that particular process it had failed ; but it was only a particular case of a far more general method in- vented by Mr. Jerrard, with admirable mathematical skill, which is adequate to effect a very curious and unexpected transformation, or rather, class of transformations, on the general equations of the M'*^ degree, though it fails when that degree is below a certain minor limit ; and that, for this and other reasons, the researches of Mr. Jerrard are highly worthy the attention of all who interest them- selves in the progress of algebra. It had not been found necessary to employ the grant voted in Dublin for an experimental discussion of the question. 6. Mr. Phillips offered a brief statement of the means taken by the Committee of the Association for the purpose of procuring regular and uniform experiments on subterranean temperature. The errors incidental to observations made in the air or water of mines had induced the Committee to recommend observers to attend simply to the temperature of the rocks themselves ; with this view 36 thermometers had been duly compared, and the errors of them ascertained ; many of these had been placed in secret situations, at the lead hills, by Professor Forbes ; at Newcastle, by Mr. Briddle ; at Wearmouth, by Mr. Anderson ; near Manchester and at North- ampton, by Mr. Hodgkinson. Within a few days Professor Phillips VOL. IV. X 306 Scientific Intelligence^ ^"c. has found means of placing thermometers in a colliery at Bedminstcr, near Bristol. The results confirm the alleged increase of tempera- ture beneath the surface. In one instance, the instrument stood at 78 degrees constantly, whilst the mean temperature of the air above was 47 degrees. 7. Mr. Craig read a paper on Polarization, with a view to show that the phenomena are referable to the division and conse- quently to the weakening of the impulse of light ; and the inability, therefore, to pass through other regular structures without ex- hibiting phenomena which arise out of the peculiarites of such structures. Tuesday, 23r^ Atigust — 1. 3fr. Russell on the Phenomena of Waves. — Mr. R. states that, in the course of his experiments on this interesting subject, he finds many different classes of waves obeying different laws. He has observed principally four classes ; 1st, the simple ripple, which is not propagated beyond the point of generation ; 2nd, oscillatory waves, such as are produced by a stone dropped into water ; these are propagated with a velocity dependent on the magnitude of the displaced fluid; 3rd, waves having a broken top, called surges ; 4th, the single, solitary wave, which is propa- gated with a nearly uniform velocity. The two last classes are those which had been principally investigated by Mr. Russell : 1st, it ^vas observed that when any addition is made to a quiescent fluid, an elevation is propagated along its surface with a velocity equal to that which would be required by falling through half the depth of the fluid ; 2nd, that the height of such wave is to be added to the depth, in order that the law may express accurately the velocity ; 3rd, that the length of the wave is closely connected with the depth of the fluid; 4th, that it varies with the height; 5th, that when the height of the wave is nearly equal to the depth of the quiescent fluid, the wave breaks ; (3th, by a canal of variable depth the deviation of surges or waves is explained, and also the formation of a tide bore ; 7th, the phenomena of weaves observed in a canal which gradually diminishes in breadth, are analogous to the phenomenon of the extremely high tides observed in narrow rivers and channels. 2. Mr. Powell on Refractive Indices. — The determination of the refractive indices for definite rays of the solar spectrum, marked by the dark lines, from the direct observation of their deviations produced by prisms of different substances, first proposed and exe- cuted by Fraunhofer, for ten media solid and fluid, was carried on by M. Rudberg for ten more cases. The necessity of an extended series of such determinations was pointed out by Sir J. Herschell and Sir D. Brewster, and was further urged by a special recommen- dation of the British Association. Mr. Powell, by a simple and most ingenious apparatus, has ascertained the refractive indices belonging to each of the standard primary rays for various media, which may be considered as a most valuable contribution to this branch of science. 3. Sir David Brewster on the Polarizing Structure of the Crystalline Lens, of the eyes of Animals after Death. — These inquiries, which form the subject of this paper, were made by com- British Association. 307 paring the changes which take place in the polarizing structure of the crystalline lenses of animals in old age, with those after death, the lenses being placed in distilled water, as being the only fluid which did not affect their transj)arency. From these investigations Sir D. Brewster has been led to conclude that there is in the crystalline lens a capability of being developed by the absorption of the aqueous humour ; that a perfect structure is not produced until the animal frame is completely formed, and that, when it begins to decay, the lens changes its density and focal length, and sometimes degenerates into that state called hard and soft cataract. Sir D. Brewster is led to entertain a hope that these researches may furnish a means of preventing or curing this alarming disease. 4. The Rev. Mr. M^Gauley having been called on by the President to read a paper in continuation of the one which he gave last year, respecting the theory of the Application of Electro- Magnetism to Mechanical Purposes, began by stating that he had met with many practical difficulties, as might be expected, in preparing for the Section a small model of a machine, intended to act with effective power ; one of the most serious of these was, that the crank and fly-wheel could not be made to move along with the primary moving pendulum. He then proceeded to give his views of the theory of electro-magnetic influence, and the best modes of constructing the several parts of the apparatus, so as to produce the greatest effect, and illustrated the whole by copious extracts from a most laborious course of experiments. WednesdaT/, 24th Avgust. — 1. The business was commenced by 3Ir. Harris, " On some Phenomena of Electrical Kepulsion." The author endeavoured to show in this paper that, from the disturbing force of electrical induction, the indications of electricity, operating by repulsion, are often anomalous and irregular, and do not, under all circumstances, indicate the quantity of electricity with which the repelling bodies, either one or both of them, are charged ; he deter- mined the nature of the cases in which the disturbing influences of induction may be supposed to arise. The author further gave the results of some inquiries on the nature of the tangent disc, and was led to believe that it may be greatly influenced by position on the charged body ; intensity of the charge, thickness, or other exten- sion, and the like, without any reference to electrical distribution on the body touched. The author conceived that the present theories did not account for the phenomena of electricity satisfactorily, and that we may eventually find electrical action reducible to a system of undulations set up in the finely attenuated medium between the surface of bodies. 2. Professor Challis' Supplementary Report on the Mathe- matical Theory of Fluids. — This report gives an account of the application of mathematics to problems in the equilibrium and motion of fluids, which had not been touched upon in the author's previous reports. These were principally the mathematical theory of clastic fluids, as bearing on the determination of the heights of mountains, and the barometer, and the amount of astronomical X 2 308 Scientific Intelligence^ Sfc. refraction, and the theory on the determination of the velocity of sound. The bases on which these theories rest were stated, and a comparison made of the theoretical results with experiments. 3. Professor Stevelly on the Interpretntion of the Doubtful Sign in (pertain Ahjebraical Formulce.—^lr. Stevelly stated that he had some years since been led to see the importance of a correct interpretation of the doubtful sign, in certain formulee, in algebraic geometry, by observing that in the transformation of co-ordinates, it was requisite sometimes to use the positive sign for a perpendicular upon a plane, and sometimes the negative sign, in a manner which to him appeared to admit of no infallible rule to guide the choice. This induced him to consider the origin or meaning of the doubtful sign, and he found it to be the value of a perpendicular upon a line, given in position by its equation from a point given by its co- ordinates, the perpendicular in one position of the given line being^ assumed as a position ; if you cause the line to revolve one half round in the plane of the axes of co-ordinates,, when it arrives at its new position the same equation will again belong to it, but the law of continuity will now compel you to use the negative sign for the same perpendicular from the same point. 4. 3Ir. M' Cullagh on the Laws of Double Refraction of Quartz. — The object of the author was to show how the various phenomena presented by quartz in its action upon polarized light, which are altogether different from those of any other known crystal, and which had never been explained by any theory, may all be grouped together by means of a very simple mathematical hypothesis. Besides explaining all the laws already known, this hypothesis leads to a new and very remarkable one, which has been for some time a desideratum in optical science ; and this new law enables us to con- nect together two classes of phenomena between which there was no connexion whatever previously, though experiments upon both had been made by different observers, M. Biot and Mr. Airy. The law is of such a nature that the experiment of Mr. Airy can be computed solely from the data furnished by those of M. Biot, and a very close agreement is to be found between the results of calculation and experiment. 5. Mr. Addams made a communication on the interference of sound. From the lateness of the hour, and having left home quite unprepared, he should merely explain the nature of a subject which, at a future meeting, he should be happy to go into at a greater length. He then proceeded to make some pleasing experiments with a tuning fork and a small glass tube, one end of which was closed. Whan the fork was held over the latter, the air propagated into it produced a sound which increased or diminished according to the distance between tham. With two tubes, one placed horizontally the other perpendicularly, a curious phenomenon was observed : when the tuning fork was put in vibration in a certain position between the two unclosed ends of the tubes, no effect was observed, but when this position was changed, or the mouth of one of the tubes closed, a very audible sound was produced. With a tube of 14 inches long, open at either end, tones were only obtained by stopping British Association. 309 a small hole in the centre ; but on inserting into this a glass tube of three inches in length, the effect was reversed, the sound being only heard when the glass was unclosed ; upon increasing this small tube to seven inches, being half the length of the larger one, no sound was produced. Mr. Addams said he would not attempt to explain the cause of this phenomena, but leave it to Professor Wheat- stone and other abler hands. Thurmay^ 25f/i August. — 1. Mr. Talbot's Researches on the In- tegral Calculus. — Mr. Talbot had succeeded in assigning an algebrai- cal value to the sura of three or more integrals of functions, whose denominators are not merely quadratic radicals of entire functions of the fifth and higher degree, such as constitute the ultra elliptic integrals furnished by Abel's celebrated theorem, but also of others whose denominators are cubic, and other radicals of similar functions which that theorem does not contemplate ; thus effecting a very great extension of one of the most difficult and interesting depart- ments of the integral calculus. 2. Dr. Apjohn on the Specific Heat of Gases. — All gases have not, under equal volumes, the same heat, as is conceived by Haycraft, Marcet, De la Rive, and others. Neither is this law true of the simple gases, as supposed by Dulong. The specific heat of hydrogen, under an equal volume, is nearly one and a half that of atmospheric air. The author's numbers come nearer those of De la Roche and Berard than any other. No simple relation appearing to exist, according to the author, between the specific heats of gases and their specific gravities or atomic weights. 3. Professor Hamilton on the Calculus of Principal Rela- tions.— By this method, the author proposes to reduce all questions in analyses to one fundamental equation or formula. Its principle depends on the fact, that he had discovered the following relation to subsist between all differential functions, no matter how numerous — I d s c s h dx~ d x' 4. The Rev. W. Scoreshy on Two Magnetical Instruments. — The first instrument depends on the influence of an extremely sus- ceptible bar of soft iron, on a magnetic needle ; so susceptible that by merely passing it roughly through the hand, a deviation of many degrees of the needle may be obtained. By means of an appropriate contrivance the bar is set at any given angle to a common compass, and by this the dip may be obtained to within a very small error. The other consists of a needle of about 16 inches long; it is con- structed of several thin lamina? of steel, united at their extremities, and separated in the centre by a block of wood, supporting the agate> upon which it rests ; the weight of this needle, which is not great, is relieved from the point supporting the agate by sus[)ension silk. There are at the extremities silver verniers. It is intended to apply this instrument to the measurement of magnetic powers generally, and to the distances between inaccessible points, as in the case of the thickness of rocks and walls. 5. Professor Forbes on the ^Ter rest rial Magnetic Intensity at carious heights. — Professor Forbes, in this communication, has gone 310 Scientific Intelliyence, ^c. far to determine an important but disputed question in physics, viz., the change in magnetic intensity at different altitudes above the earth's surface. He stated briefly the results of 45 series of obser- vations with Causteen's intensity needles at 13 stations in the Alps and Pyrenees, from six to 1000 feet above the level of tlie sea, and compared with the intensities observed in the intermediate valleys. The general result at which he arrives is, that there is no general decisive vindication of diminished intensity with height, at least within the limits of error of the instrument, and certainly, if it exists, the diminution must be exceedingly much smaller than M. Kuppfer has proposed. 6. A paper, by Sirl}. Brewster, on the action of crystallized sur- faces upon light was read, and gave rise to some discussion on the part of Sir W. Hamilton and Mr. M'Cullagh; but the statements of the paper do not admit of abridgement. 7. Dr. C. Williams gave an account of an improved ear-trumpet, by which sounds are rendered audible at three times the usual dis- tance. The Section then adjourned. Evening Meeting. — 8. Mr. G. W. Hall on the Connexion of the Weather with the Tides. — Mr. H. observed, that the baro- meter undulates at the changes of the moon, but more commonly sinks than rises ; the weather is then generally unsettled, with high winds; as the weather settles, it not unfrequently remains in an indeterminate state. These variations apply to all the changes of the moon. 9. Mr. Ettrick on an Instrument for observing Terrestrial Magnetism. — This instrument consists simply of a common Coulomb's balance, substituting for the needle a magnetic bar, to which is screwed a finely divided graduated circle. The degrees of deviation are read off by means of a telescope with cross wires placed perpen- dicularly to the plane of the circle. The author described and exhibited to the Section a new kind of cushion ; which, being constructed of distinct pieces, and acted on by springs, could apply itself to a cylindrical glass of any irregular sur- face. He also described an improved rubber for the plate machine, by which the author supposes an increased power is obtained ; it is not very different from the form of the rubber as usually employed. The same gentleman described a New Instrument for trying the effect of jElect7'ical Discharges in Rarefied Air, or in different kinds of Gases. — He finds the bar usually observed on sending a shock through a card quite uninfluenced by the state of the medium in which it is placed ; it also remains the same in gases of different kinds. 10. 3Ir. Addams on the Vibratio7i of Bells. — The author, in this paper, endeavours to explain a peculiar beat frequently heard in the sound of a clock or tower bell, which he considers to arise from unequal thickness of the metal ; this he illustrated by some striking experiments on a glass bell. 11. 3Ir. Rootseyo7i the higher order of Grecian Music, and on Mnemonic logarithms. — The first of these papers relates to some kinds of musical chords, rejected by some j)ersims as being ini- British Association. 31 1 practicable, but which the author thinks may be used with consider- able effect. The second paper relates to a system of logarithms, which may be used with great advantage in calculations. The Section the adjourned. Friday, Awjust 2{}th. — 1. Mr. Whewell gave an account of his anemometer, which he described last year at Dublin, in an unfinished state. — See Records, vol. ii. 218. 2. Mr. Stevelly, on Mathematical Rules for constructing com- pensating Pendulums. The author having found the rule given by Kater erroneous, he endeavoured to lay down the true formulae. 3. Mr. Phillips stated the results of his experiments, " On the direction of the Isoclinal Magnetic lines in Yorkshire," to be, that the lines of equal dip were not straight, but had considerable flexures distinctly related to the elevation of the ground, the bcndings taking place rapidly to the south, on two elevated ridges by which Yorkshire is intersected. 4. Sir JDaoid Brewster, *'0n a very simple contrivance for tracing lines in the Solar Spectrum, which were invisible by other means." This contrivance consisted merely in introducing a cylindrical re- fractor between the eye and the eye-glass of the telescope. The effect of this refractor was to give a linear form to the most irregular image 5. Dr. Hare, on " Electrical Attractions and Repulsions, and upon the Electric Spark. The object of this paper was to support Franklin's theory, and to refer repulsion to the action of surrounding bodies. 6. Dr. Carpenter, on the method of teaching the blind to read. 7. Mr. Russell, on " Some of the Elements of the resistances of fluids." The laws of the resistances reduce themselves to, 1st, The law of the emersion of the floating body from the fluid, which is related to the velocity alone ; 2nd, The relation of the resistance of the wave ; 3rd, The relation of resistance to a certain form of the body. 8. il/r. Hodghinson gave an account of his experiments on the comparative strength of iron made with the hot and with the cold blast. In most cases the hot blast iron seems to be somewhat but not greatly weaker. Its specific gravity is also rather less, except at the Devon works. The fracture of the cold blast was white, that of the hot blast gray. No. 1 and 2 had less tenacity when prepared by the hot blast. The opposite, however, was the case with the Devon iron. No. 3, which by the hot blast was less hard but greatly stronger. Section G. — mechanical science. President, Davies Gilbert, Esq. — F?ce Presidents, M. I. Brunei, Esq., John Robison, Esq. — Secretaries, T. G. Bunt, Esq., G. T. Clark, Esq., William West, Esq. — Committee, Captain Chapman, G. Cubitt, Esq., J. S. Enys, Esq., William Hawkes, Esq., E. Hodgkinson, Esq., Dr. Lardner, Professor Moseley, M. he Play, 312 Scientific Intelligence, ^c. Sir John Rennie, George Rennie, Esq., John Tavlor, Esq., Rev. W. Taylor. Monday y 227id August. — Professor Moseley, " On certain points connected with the theory of Locomotive Carriages." The author commenced by stating, that there were many gentle- men present acquainted with the practical working of steam-engines, but the relations between the theory and practice w^ere not perfectly understood. The piston of a locomotive engine was pressed on either side by two forces ; one resulting from the friction on the road, and the other from the passive friction of the engine itself. If it was lifted from the ground, a person endeavouring to move the wheels would find a resistance equal to 150 lbs. ; the cause of the resistance was this, that the traction upon the engine induced additional friction of the machinery, and that probably was one-fifth of the whole amount of friction. If the carriage moved without a train, there would be a passive resistance ; if a train were attached to it, there would be induced a considerable friction of machinery. There were, in fact, three causes of resistance ; the friction of the carriage, the passive resistance, the additional friction by the train ; the first and last varying according to the weight of the train. On the other side there was the expansive force of the steam. The quantity of work done was greater as the velocity w^as less. He would chiefly apply himself to inclined planes. Great power was required in drawing a train up an inclined plane, but when the train came down the in- clination, no additional power was gained, because the steam evapo- rated through the safety-valve. On this account, in addition to the loss of time, inclined planes on railways were highly injurious, and should be avoided. Dr. Lardner would make a few observations . in consequence of his having given evidence on this subject before Parliament. In all inclined planes, which were more steep than the angle of repose, there would be an unfavourable loss of power. The portion of mechanical force used in ascertaining the inclined plane was not repaid in the descent. If you could take advantage of the accumu- lation of power in the descent, there might be a perfect mechanical confirmation, but that was not the case in practice, because you were obliged to check the velocity in the descent. It had been stated that in his evidence he had said that inclined planes were not of im- portance, as the friction in the ascent was given back in the descent. That was an error ; he had not so said. Inclined planes were injurious. All the experiments led to the conclusion that every effort should be made to attain as level a line as possible. Every departure from a level, though it saved a quantity of capital in the construction of the road, entailed an everlasting expense. After a number of experiments "he had made, the results were these ; that in the ordinary state of the roads, the pressure necessary on a level was 71bs. to a ton, but he had found an extraordinary difference depending on the state of the rails ; a difference amounting, in some instances, to such an extent that the friction was reduced to 41bs. ; this occurred when it rained, and the rails were wet, but as soon as. the rails became dry the friction again increased to7Ibs. He, there- ^ British Association. 313 fore, should consider that it would be a good thing to place watering- pots before the wheels of the carriages, which would give an additional power in the proportion of nearly 50 per cent. 2. The next paper was on the application of our knowledge of the phenomena of waves to the improvement of the navigation of shallow rivers and canals. Mr. Russell, of Edinburgh, regretted he had not had time to put his observations on this subject into writing. To gentlemen connected with railways he would say, that where canals did exist there could be no man who did not wish that the traffic upon them should be conducted in the most favourable manner. The result of various experiments he had made confirmed the law of Sir Isaac Newton, that the resistance was in proportion to the square of the velocity. The difference of resistance between a horse drawing a vessel trotting and cantering was 108 to 130. He had made a table which was the result of 2400 experiments. In going at a velocity of 4 miles an hour the resistance was . . 33 lbs. 6 91 7i 265 8^ 215 9'' 235 11 246 12 352 15 444 But at the velocity of 20 miles an hour the vessel apparently sailed along the surface of the water, and the resistance was very trifling. They would observe that at 8^ miles an hour the resistance was not so great as at 7 or 9. When a vessel was propelled at a certain velocity and she stopped, it had t\\^ effect of giving an impetus to the water, and produced a wave varying in its form according to the mass of the water, and he had followed such a wave no less a dis- tance than a mile and half; the velocity of the wave was uniform and independent of the velocity of the vessel ; for if a vessel was going 4 miles an hour the wave would go at the rate of 8 miles, and he had seen a large wave overtake a small wave and pass it ; waves never exceed in height the depth of the quiescent water. If the velocity of a vessel did not exceed eight miles an hour, it did not divide the water but pushed it forward in the shape of a wave, but beyond that velocity the water was divided. It was possible to increase the velocity and get upon the wave and then the resistance was nothing. Where a canal had a depth of 3 feet there might be a velocity of . . 6 miles an hour. 5 8 9 11 So that the greater the depth of water the greater velocity might be attained. The resistance was less above 6 miles an hour, but 4 and 6 miles an hour the velocity was unfavourable, beyond 11 miles an hour you had high velocity and comparatively little resistance. Where it was intended that the velocity should be great he recom- 314 Scientific Intelligence , Sfc. mended rectangular canals. To make canals wide with sloping banks was an evil. Mr. Whewell considered these observations to be of the highest value and of the greatest importance. It must be recollected that although the wave travelled, the current was not increased. He was very anxious to have the velocity of waves at sea discovered. Pi'ofessor Mosely considered this might be adopted by taking the velocity of a wave made by a steam vessel. Mr. Russell proi)osed that the wave should be measured in this way. Let two vessak go out, and one of them be anchored ; have a line attached from one to the other when the vessels were each on the top of a wave, let the rope be drawn tight, and that would give the width of the wave ; then when the vessels were both in the bottom, a sight taken from the mast would give the height of the wave, and by these means you might almost make a map of the bottom of the sea. The farther vessels went the less would be the resistance, and the Atlantic might thus easily be traversed by steam vessels. The Chairman said the experiments were most important, and the gratitude of the country was due to the young man who had made them, Mr. Russell. Tuesday, 237'd Augxist. — 1. Mr, Hawkins read the following paper on an Improvement upon Neper's Rods, for facilitating the multiplication of high numbers, with little liability of error ; the invention of J. N. Copham, Esq., of Bristol. — The invention consists in cutting each of Neper's rods into cubes, and in stringing the cubes together by means of pins passing through two perforations in each cube, made at right angles from each other, parallel to the figured side. By this arrangement the cubes may be readily placed in such positions, in respect to each other, that the product may be obtained by addition only, without the necessity of transcribing the figures from the rods previous to the addition ; thus avoiding a great liability to error, and effecting a great saving of time in the calcula- tion. The pins are in two sets, with heads of two different shapes. On the heads of one set of pins are marked 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, respectively, the same pin having the same number on each side of the head, but the number on one side of the head is inverted in respect to the position of the number on the other side. The heads of the other set of pins are also numbered 0, 1, 2, 3, 4, 6, 6, 7, 8, 9, but the pin having 0 on one side of the head has 9 on the other side, that having 1 on one side has 8 on the other, &c. The figures in this set also are inverted in respect to those of the opposite side of the head. The cubes are kept strung on those pins which have the same figures on each side of the head, ten cubes on each pin repre- senting one of Neper's Vods. On the pin marked 0, all the cubes are marked 0 on both sides. On the pin marked 1, the cubes are marked 0, 1; 2, &c., on one side, and 9, 8, &c., on the other side, the two sides of each cube, on being added together, make 9 : on the pin marked 2, the cubes are marked 0, 2, 4, &c., on one side, and 18, 16, &c., on the other side : the numbers on the two sides of each cube, on being added together, make 18 ; and thus the numbers on British Association. 315 the cubes of each pin are all consecutive multiples of the number on the head of the pin, and the two numbers on each cube, on being added together, make the number on the head multiplied by 9 ; the numbers ascending on one side and descending on the other. 2. Dr. Daubeny explained the properties of an instrument he had contrived for obtaining sea water at great depths. 3. Mr. Braham explained an improvement he had made in the mariner's compass. It was found, that in consequence of the vibra- tory motion in steam vessels, the compass got out of order ; he, there- fore, proposed to put a fluid in the box of the compass, so that the card might float upon the fluid. It was obvious, that a card on a fluid would be liable to injury and decay ; he had, therefore, caused the points of the compass to be painted on porcelain, which he had affixed to a flat piece of cork, and thus it was kept floating upon the fluid, and the motion of the steam vessel had no effect upon it. JEvening 3Ieeting. — 4. Mr. Wliewell delivered a brief lecture on Tides, and stated, that at the last annual meeting of the Association, a sum of i£'250 had been voted for the purpose of making experi- ments and observations relative to the subject, which sum had been expended, but the report of the results had not yet been published. He also produced a machine which had been used in the Avon, with a view of ascertaining the variation in the tides, and the result had been, that one of the theories on this branch of science had been proved to be practically correct. 5. Steam Communication with Iridia. — Dr. Lardner then pro- ceeded to deliver a lecture on this question. The subject, which it was wished should be brought under the consideration of the Section, was one of very considerable importance, but of peculiar importance to this particular city ; taking it in its whole extent, it was the solution of a problem, how far the present powers of steam were capable of being extended in their application to navigation. The moment this question was proved, two grand commercial problems would suggest themselves, namely, the connexion by steam of Great Britain with our colonial possessions, and the connexion by steam of Great Britain with the United States of America. These two questions embraced a great variety of topics of much interest ; he, therefore, proposed, with the approbation of the general council, to present at present all the more popular and more intelligible parts of the subject, reserving for the morning meeting the more technical details. The subject to which he wished more par- ticularly to address himself this evening, was the application of steam to a communication between Great Britain and India. There were several routes by which a communication could be effected ; the only route which was in a continued line of navigation was by the ordinary voyage by the Cape. That had been already tried by steam, but if it had not, they were sufficiently conversant with the properties of the present steam engine to know that it was incapable of being worked profitably. That voyage was attempted by the Cape by the Enterprize, and it was performed in 113 days, but only 64 days were worked by steam ; it afforded evidence, that to establish a line of stpam communication by that route was out of the question. 316 Scientific lutellvjence, Sfc. The other routes were partly by land and partly by water. One from Great Britain, across Germany by the Danube, the Black Sea, across Turkey to the river Euphrates, descend to the Per- sian Gulph, and then pass on to India. But ttis route was out of the question, from the difficulties to be encountered. The real practical courses then which presented themselves were only two, and these would come to a certain point. They proposed starting from Falmouth, to proceed up the Mediterranean; indeed, we did that already to Malta, therefore, it was not necessary to discuss the prac- ticability of that route. From Malta they would adopt either of two courses — one would be to proceed to Alexandria, a distance of 800 miles, and quite within the present limits of steam power, as 1600 miles had already been performed ; they then proceeded to Syria, and descended the Euphrates. So far as Alexandria was concerned there was no practical difficulty ; they then proceeded to the Red Sea by land, or partially by the Nile, to Cairo. If they would refer to the plan of the Isthmus of Suez, the road to Cairo followed the banks of the Nile ; the only difficulty they had to encounter here was the Isthmus ; they would have to proceed to Suez by a sandy desert ; but about the centre of it there were springs of fresh water, and the distance did not exceed 70 miles, and was now per- formed in less than 24 hours. It was, however, suggested, that a canal might be cut across, and the idea had been thrown out that a railroad might be constructed. Now, there were other modes of crossing the Isthmus, which were deserving of notice. The general character of the Isthmus, between the Mediterranean and the Red Sea, was very peculiar ; when we proceed due north, we pass over three miles of land very little elevated above the surface of the Red Sea ; we then come into a narrow valley bounded on each side by hills, and in the centre of those valleys we found the distinct trace of a canal, which was known to have existed in former times, and with the history of which they were all acquainted ; this canal now, in many places, is in as perfect a state as many of the old canals in this country ; but one of the remarkable peculiarities was this, that a great portion of its surface was not only below the level of the Red Sea, but still more remarkable, was below the level of the Mediterranean — now the valley, which from the point is three miles towards the Mediterranean, was below both. That this valley was at some time or other filled with water, connecting the two seas, was rendered probable by the fact, that it was lower than the level of both the two, and that the water which remained was in fact salt, and was called the bitter lake. — That portion of water was, in fact, a part of the ancient canal ; coming to a point midway between Suez and the Mediterranean we find two other lines of hills. The canal was conducted into the hill near Cairo ; one-third of that canal now existed, and only required to be cleaned out ; and the other portion could be restored. This canal was begun by Sesostris, and was the channel by which European commerce was conveyed to the East. But this stupendous work could be used only two months out of ten, for the ancients were unacquainted with our contrivance of locks. Nevertheless, during those two months the trade of British Association. 317 Europe passed in this canal to Suez. During the other ten months, the commerce passed up the Nile, and then to an ancient port, where theyembarked on the Red Sea. Now, it was proposed to open that canal, and to lo^ it as far as Suez, if no physical obstacle arose. The Red Sea was the next point for consideration, and much had been said about the difficulties which existed in the transit through this sea, owing to the beds of coral ; but they were confined to the coasts, and were well known to the local pilots, and created no more difficulties than the rocks which existed on our own coasts. The steam navigation of the Red Sea was practicable and convenient, and there were several safe harbours. Proceeding downwards, they came in a run of about 300 miles, to Corsair, from whence they would go 300 or 400 miles, from thence to Jedda, on the opposite side of the coast, which was the port of the city of Mecca.* There was another town, Mocha, where there was a safe road-stead. On the coast of Arabia there were two or three harbours, all of which were convenient ; so far there was no practicable difficulty. He should state, however, that the voyage from North to South of the Red Sea was more easy than from South to North ; for ten months the North wind blows so violently, that no steam packet could face it. They now came to the real difficulty in the case ; when they pro- ceeded from the ports on the Arabian coast, they had a long run to get to the nearest port in India, namely, Bombay, that being 1200 miles : now, when they had to encounter a run of this kind, which approached very near the extreme limit of our present power of steam naviga- tion, it became a question of the last degree of importance, whether or not they should have average weather : now, the seas between Arabia and Africa and India were subject to periodical vicissitudes, which were unknown in our climate. There was a periodical wind which blew as regularly as the sun rose and set, and blew with an intensity with which we were little accustomed, they were known by the name of the north-east and south-west monsoons ; the south- west blew from June to September. They would readily perceive there could exist no steady atmospheric current of that kind, without passing some counter current to produce an atmospheric equilibrium ; accordingly, they found the counter current flowing in the opposite direction between November and IMarch ; but, although they blew about equal time, they were very different in intensity, and in their effects on the water. The north-east monsoon was a wind against which a steam vessel could go without any difficulty ; consequently, during the months from June to September, the navigation was im- practicable from Bombay, but it was practicable during all the year from Europe to Bombay ; the swell for 800 miles from Bombay was such, that if they attempted to use sufficient power to propel the vessel, it would drive her into the sea. The other route was from Malta to any part of Syria, and was without difficulty from these ports to the banks of tlie Euphrates ; but then there were some other difficulties ; the passage was not across a sandy dessert, but it was infested by savage tribes, who were • See these various distances, Records, i. 474. 318 Scientific Intelligence, ^"c. not professed robbers, but would not stop much to consider the pro- priety or impropriety of robbing you. The town, which had been suggested as the point of departure, was Birr, 1200 miles from the mouth of the river; now, this river was one which presented many circumstances extremely questionable for the application of steam navigation. The average speed of the current of the river was no greater than three miles an hour, at certain points, however, it rose to seven miles an hour. The magnitude of this river they might form a notion of, when he told them, that at Birr, the breadth was something like the Thames at Lambeth, and down as low as Babylon, it flowed like the Thames at Deptford. The depth of the river was quite sufficient for safe and speedy navigation; but this river is subject to a low season, during which, there were some difficulties^ — it existed only in part of the river. Passing Babylon and Bagdad, you come to a village called Elkain, a distance of about 170 miles, and in these 170 were included all the physical difficulties. There were 15 or 16 shallows and rapids, which, in the low season, were diflScult ; but it did so happen, that the low season of the Euphrates was the very season during which the north-east monsoon blew ; the impracticable season of the one was during the practicable season of the other. It was proposed to navigate by iron vessels, and coal might be obtained from Wales, at a cost of about £2 a ton. In ancient times the communication between England and India was by the Euphrates, and step by step the very route they were now thinking of resuming, and it was a remarkable circumstance, for the progress of civilization seemed to sport with our endeavours ; before the discovery of the Cape, our merchants found their way to India by the Euphrates, and a Portuguese was immortalized for the discovery ; but another discovery was made by means of the steam engine, and that sent us down the Euphrates again in the old way to India. The voyage by either route, from Falmouth to Bombay, might be done in seven weeks. The Section then adjourned. \\ ednesday, 24th August. — The Chair was taken by Davics Gilbert, Esq., at eleven o'clock. 1. The Chairman read a paper on Naval Architecture, sent by Mr. Henwood, of Portsmouth Dockyard. 2. 3Ir. Price exhibited a model of a new construction of paddle wheels ; he had them placed on his vessel, and could now do 108 miles in eight hours and a half. The paddle rose vertically and the water ran off", and it was also a saving of one-third in fuel and time. These paddle wheels were adopted by the Ordnance. 3Ir. Russell would state that in Scotland they had had great experience in steam vessels, and he would state some circumstances which were within his knowledge, and he would address himself par- ticularly to the encrustation on the boiler, produced by the salt water ; he had found out, when on board a steam vessel, a simple and beautiful expedient for remedying this, and it had been kept a perfect secret. He would take a boiler of a cylindrical shape ; that which was most dense in the water would of course fall to the bottom, and therefore, as the cold water came in at the top the salt would descend to the bottom below the furnace, and then came the secret, British Association. 319 there was a pipe with a stop cock, and the engineer filled the boiler a little too full, he then opened the stop cock and got off the salt. The boiler was worked for nine months, and a man was then sent into it for the purpose of clearing it out, and he found he had nothing to do for there was no encrustation. With regard to the engine, he was not one of those who expected any very great radical improve- ment in the construction of the steam engine ; Watt, in his opinion, had left them but very little to do. In Scotland they had adopted the plan of the Cornish engine. An engine was worked on the high pressure system, and it worked expansively, and with this engine at the top of high water, with a cargo of 150 passengers, in its ordinary rate he had gone 14| miles an hour ; the great thing to be attended to was the precise place of fixing the engine ; he believed that with the ordinary boilers well made, and every thing being of the best kind, every effect they could reasonably expect would be obtained. With regard to paddle wheels, he considered those pro- duced by Mr. Price of great value, where the engine v/as not properly proportioned, or where the vessel was not a good one ; but he was convinced, from a long train of circumstances, that in a well- built vessel, with properly proportioned engines, the common paddle wheel was not only the simplest, the cheapest, the most secure, but was the best in theory as well as in practice. Mr. Price maintained that the patent paddle wheel was very far superior. He had laid out ^1000 in putting them to his vessel, and he had found that he could beat all the other vessels of the same size. Thursday, 26th August. — 1. Mr. Chatjield read a very long essay on Naval Architecture. 2. Mr. Enys gave a long account of the working duty on the Cornish Steam Engines. 3. Steam Communication with Distant Parts. — Dr. Lardner in making his remarks on this subject said, he would beg of every one, and more especially of those who had a direct interest in the inquiry, to dismiss from their minds all previously-formed judg- ments about it, and more especially upon this question to be guarded against the conclusion of mere theory ; for if there was one point in practice of a commercial nature which more than another required to be founded on experience, it was this one of extending steam navigation to voyages of extraordinary length. He was aware, since the question had arisen in this city, it had been stated that his own opinion was adverse to it ; that impression was totally wrong ; but he did feel that as steps had been taken to try this experiment, great caution should be used in the adoption of the means of carrying it into effect ; almost all depended on a first attempt, for a failure would much retard the ultimate consummation of their wishes. With regard to the power of steam engines, practical men considered that for short trips the best proportion was to give the vessel the power of one horse for every two tons ; that as the length of the trips increased they must have a smaller })roportion of power, this should be three tons for every horse power, and for the longest trips to which steam could be applied, about one horse to four tons. to o >^ £- § s^^' * ^ <» bo's "2 ' ea bD M -=3 w G 0 '^ o aim "-a ".So ^?2 ^.S'^' S? 5! "> bo^ u- ^ ry) C ^ VJ t- > oD .." rt (8 CO O O), . O fl ® .5 *J 3 I bog •S.S '^3 O -S I— t fl t: «^ 5 3 « boS o boo 'S «^^ d^l «'^i « " « ^ S ?^, d « >-.'^ G 'n O 3 o o c o -^^ ;g g ^ 3^*^ '§'§'"' — ee « G OJ m O! , „ s.^ N N N ® OJ ^*^ ® Q^ 0^ ;3 -2 > a> oi Q) bo bo rt'i rt\ .^ P •S ; 2 u^ d '-a "<: §0-2 .-o . « ^ 1/3 CC K -. iCS!Scse8c3e««cB«©^,CesG •So ^ So r*i OJ l^m H M ^ W ^ ^ ^ 00 Z W ro W ^ ^ V5 ^ r/j r/J ^ I? !^* c» ^ ^ ^ c/5 c/? -^^^^^ 4.. 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Notice of Carburet of Potassium, and of a New Gaseous Bi-carhuret of Hydrogen. By Edmund Davy, Esq., Professor of Chemistry to the Royal Dublin Spciety. (^Communicated to the British Association, ^6th August, 1836.) In January last, the author made different experiments to obtain the metal of potash on a large scale, by exposing to a high temperature, in an iron bottle, a mixture of previously ignited tartar and charcoal powder, in propor- tions of the latter varying from about ^^^th to ^^ih of the whole mass. In one experiment, a substance was obtained of a dark gray colour, rather soft to the knife, though adhering with tenacity to the iron, and inclining to a granular structure. This substance, when put into water, decomposes it with great facility, carbonaceous matter is disengaged, and gas copiously evolved, with occasional inflammations on the surface, as is commonly the case with potassium under similar circumstances. The gas, when examined, was found to consist of hydrogen, and a new bi-carburet of hydrogen, (noticed in a subsequent part of this communi- cation), in nearly equal volumes. The author regards the substance in question as a mixture of potassium and car- buret of potassium ; the former, by its action on water fur- nishing the hydrogen, the latter, the new gas. In collect- ing gas from the substance, by the action of water over mercury, a novel and interesting case of combustion was observed. A little of the substance being placed in a tube VOL. IV. Y 322 Professor Davys Notice of Carburet of Potassium, filled with mercury, on letting up a few drops of water, gas was copiously disengaged, and as the mercury descended along the tube, small portions of the substance became ignited, exhibiting the appearance of bright sparks of fire in continued succession. In another experiment with the iron bottle, the author procured no potassium, but a small quantity of a substance partly in powder, and partly in small lumps, of a dense black colour. This substance the author regards as car- buret of potassium. It exhibits no appearance of crystal- lization to the naked eye ; but when viewed with a glass of high magnifing power, the author thinks he has observed congeries of exceedingly minute four-sided prisms, trun- cated at their solid angles. When the carburet is exposed to the air, it soon undergoes changes, oxygen and water appear to be absorbed, and caustic potash and carbon remain. When the carburet is put into water, both substances are decomposed, one portion of the carbon unites with the hydrogen of the water to form the new bi-carburet of hydrogen, which is the only gaseous product, the remainder being disengaged, whilst the oxygen of the water and the potassium form potash. Alcohol and turpentine act feebly on the carburet, acids strongly. The carburet undergoes partial decomposition at a dull red heat in close vessels, potassium slowly rises from it, whilst the carbon remains of a deep and bright black colour. The author regards the pure carburet as a binary com- pound of one proportion of carbon and one of potassium. New Bi-carhuret of Hydrogen, This gas was obtained by the action of carburet of potas- sium on water. It is highly inflammable, and when kindled in contact with air, burns with a bright flame, apparently denser and of greater splendour than even olefiant gas. If the supply of air is limited, the combustion of the gas is accompanied with a copious deposition of carbon. When the new gas is brought in contact with chlorine gas instant explosion takes place, accompanied by a large red flame, and the deposition of much carbon, and these effects readily and of a New Gaseous Bi-carburet of Hydrogen. 323 take place in the dark, and are, of course, quite indepen- dent of the action of the sun's rays or of light. The new gas may be kept over mercury for an indefinite time without undergoing any apparent change ; but it is slowly absorbed by water. Recently boiled distilled water, when agitated in contact with the new gas, absorbs about its own volume of it ; but, on heating the aqueous solution, the gas is evolved apparently unaltered. The gas is absorbed to a certain extent by and blackens sulphuric acid. The new gas detonates powerfully with oxygen, especially when the latter forms three-fourths or more of the mixture, and the only products appear to be water and carbonic acid gas. It requires for its complete combustion 2J volumes of oxygen gas, two volumes of which are converted into carbonic acid gas, and the remaining half volume into water. From the author's analysis by different methods, the new gas appears to be composed of one volume of hydrogen and two volumes of the vapour of carbon con- densed into one volume. Its density is therefore less than that of olefiant gas by the weight of a volume of hydrogen equal to that of its own bulk. It is, in fact, a bi-carburet of hydrogen composed of two proportions of carbon and one of hydrogen, and may be represented by the formula C* + H, or 2C + H ; and its constitution seems to differ from that of any other known gas. From the brilliancy with which the new gas burns in contact with the atmosphere, the author thinks it is admir- ably adapted for producing artificial light, if it can be pro- cured at a cheap rate. Article IL On the Atomic Weight of Nichel and its Oxides. By Thomas Thomson, M. D., F. R.S. L. & E., Regius Pro- fessor of Chemistry in the University of Glasgow. In a paper entitled " Observations on the Atomic Weights of Bodies," published in the third volume of the Recoi'ds of General Science, I adopted (see page 255) 3*625 as the atomic weight of nickel, because that number agreed better with the specific heat of that metal, stated by Dulong and Petit, at 0-1035, supposing the law that the atomic weight Y 2 324 Dr. Thomas Thomson on the Atomic Weight multiplied by the specific heat amounts to the constant quantity 0*375 to be correct. My atomic weight for nickel deduced from a very simple experiment, which I still con- sider as susceptible of greater accuracy than anyanalysis whatever, was 3-25. Now, 3*25 x 0-1035 = 0-337 ; while 3-625 X 0-1035 = 0-375. At the same time I stated, that I had never been able, by the most careful experiments, to obtain any number for nickel ever approaching to 3*625, which would make the atom of nickel higher than that of iron. I made a hasty experiment in the month of January last, which I have stated in a note. — Records of General Science, iii. 255. But it was unsatisfactory; and my numerous occupations, at that busy season of the year, in the college of Glasgow, put it out of my power, at that time, to prosecute the experiment. I, therefore, left the investigation till summer should arrive, and give me leisure to resume the subject. I have just finished the experi- ments which I had projected (July 10th, 1836), and pro- pose in this paper to state the results which I obtained. In my First Principles of Chemistry , vol. i. p. 358, I have stated the experiments from which I deduced 3*25 to be the atomic weight of nickel. I found, that when a solution of 17-125 grains of pure crystals of sulphate of nickel is mixed with a solution of 13*25 grains of chloride of barium, a double decomposition takes place, and after the sulphate of barytes has fallen to the bottom, the supernatant liquid, tested by solutions of sulphate of soda and chloride of barium, remains transparent, and, consequently, contains no appreciable quantity either of sulphuric acid or barytes. This experiment I still find to be perfectly correct. I employed in repeating it sulphate of nickel, which had been purified by five successive crystallizations. The crystals were small but well formed, and they were rendered as dry as possible without losing any of their water of crystalliza- tion by pressure between folds of bloating paper and ex- posure to the air. The chloride of barium was prepared on purpose for the experiment. It was perfectly pure, and rendered anhydrous by exposure to a red heat in a platinum crucible. The conclusion which I drew from this experiment was, that 17*125 grains of crystallized sulphate of nickel con- of Nickel and its Oxides. 325 tains exactly five grains of sulphuric acid. Dr. Turner has objected to this conclusion, that I employed 13'25 grains of chloride of barium instead of 13 grains, the quantity containing the exact proportion of barium that is necessary to saturate 5 of sulphuric acid. It would seem at first sight, that my experiment indicated the presence of 5*096 of sulphuric acid instead of 5. But I find that in practice we must always employ 13*25 of chloride of barium to throw down 5 of sulphuric acid. If we employ less, the whole sulphuric acid is not thrown down. In consequence of this curious fact, I found it impossible to determine the atomic weight of barytes by mixing sulphate of potash and chloride of barium. The result always gave 9*75 for the atomic weight of barytes. I succeeded in obtaining 9*5 only when I substituted carbonate of barytes for sulphate, and employed re-agents, which were dissipated by a red heat. Many an experiment on this subject has been made by my practical pupils, and some of the most accurate among them have been so much struck with it as to be inclined to adopt 9*75 for the atomic weight of barytes. But I satisfied myself many years ago (as I have elsewhere stated) that 9*5 is the real number; but, that owing to some curious combinations which take place, we never can precipitate the whole sulphuric acid from a solution without employing a slight excess of barytes. The above experiments (which any person may easily repeat) leave no doubt on my mind, that 17*125 grains of pure crystallized sulphate of nickel contain exactly 5 grains of sulphuric acid. The determination of the water of crystallization of this salt is a very difficult thing. For if we heat the salt too high, we drive off'not merely the water, but also a portion of the acid. The heat should be applied very slowly and equably, and it should be raised higher than 600°, but not so high as a red heat. If the salt after this exposure be still soluble in water, it is a proof that none of the acid has been driven off. In a very cautious experiment I drove off 7*8 grains from 17*125 of the crystals, and the salt was still soluble in water. In another, I drove off 8 grains ; but the salt did not dissolve completely in water. From these trials 1 concluded, that the water of crystallization lies 326 J9r. Thomas Thomson on the Atomic Weight between 7*8 and 8 grains. Now, 7 atoms of water weigh 7-875, which is within one per cent, of 7*8, the quantity actually got. I concluded from these facts, that sulphate of nickel contains 7 atoms water ; nor do I think any doubts can be entertained on the subject. It is clear, then, that 17*125 grains of crystals of sulphate of nickel contain Sulphuric acid, . . 5* Water, 7-875 What is wanting to complete the sum, must be the weight of an atom of protoxide of nickel. Now, this quantity is 4-25. Therefore, 4-25 is the weight of an atom of pro- toxide of nickel, and, consequently, 3*25 is the atomic weight of metallic nickel. Such are the results which I still continue to obtain, when the experiment is made in the way above stated, however pure the sulphate of nickel and chloride of barium which are employed. But, when we subject crystallized sulphate of nickel to analysis, the results which we obtain are different. The result, however, of this analysis is quite incompatible with the atomic weight of nickel as stated by Berzelius, which he makes 3-69675. I do not know on what data this number is founded ; for I am not aware of any experi- ments which he has made on the subject. He quotes Rothoff^s experiments, the result of which only, so far as I know, has been published by Berzelius himself. Accord- ing to RothofF's experiment, protoxide of nickel has an ash-gray colour, and is composed of 100 nickel and 26-909 oxygen. This is equivalent to Nickel, . . 3-716 Oxygen, . . 1- So that it does not appear upon what authority Berzelius has made the atomic weight of nickel 3*69675. We have an analysis of sulphate of nickel by Mr. Richard Phillips, well known for the accuracy of his experiment&. According to him, it is composed of Oxide of nickel, . . 26*30 or 4-669 Sulphuric acid, . . . 28*16 or 5* Water, 45*54 or 8*08 10000=^ Annals of Philosophy (2iul Series), vi. 440. of Nickel and its Oxides. 327 According to this analysis protoxide of nickel has an atomic weight of 4'669. This is lower than the number assigned by Berzelius, and still lower than that which results from the experiments of RothoiF's. But it is so much higher than my number, 4*25, that I was desirous of discovering, if possible, the cause of the difference between us. I dissolved 50 grains of crystals of sulphate of nickel, purified by 5 successive crystallizations in water, and threw down the sulphuric acid by chloride of barium, purified on purpose. The sulphate of barytes, after thorough edul- coration and ignition, weighed 42-41 grains = 14*62 grains of sulphuric acid, or 29*24 per cent. Fifty grains of the same salt, being dissolved in water, were mixed with a solution of caustic soda. The oxide of nickel, after thorough edulcoration and ignition, weighed 13*79 grains, or 27*58 per cent. According to this analysis sulphate of nickel is composed of Oxide of nickel, . . 27-58 or 4*716 Sulphuric acid, . . 29*24 or 5* Water, 43*18 or 7*38 100*00 This analysis was repeated with almost the same result. According to this analysis the atomic weight of nickel is 4*716, the very same as stated by Rothoff* to be the result of his experiments. But a little consideration must satisfy us, that the oxide of nickel obtained by this analysis is not the oxide which exists in sulphate of nickel. For the water in the salt (if the oxide weighs 4*716) is only 43*18 grains. But I actually separated from it (as has been already stated) 45*54 grains of water, which is more than could have existed if the atom of protoxide of nickel were 4*716, or even 4*69675 as Berzelius makes it. For the component parts of this salt would be Oxide of nickel, . . 27*58 Sulphuric acid, . . 29*24 Water, 45-54 102*36 giving a surplus of 2*36 per cent., which must be owing to 328 Dr. Thomas Thomson on the Atomic Weight some change in the oxide of nickel. For there can be no mistake either respecting the sulphuric acid or water. This circumstance induced me to turn my attention to the oxide of nickel, which was obtained by mixing sulphate of nickel with caustic spda, edulcorating the precipitate, and exposing it to a red heat. The oxide of nickel obtained in this way is a beautiful black matter concreted into small lumps, having considerable lustre, and easily reduced to powder. It is tasteless and insoluble in water. But it dissolves slowly in sulphuric and nitric acids. During the solution an effervescence takes place, and oxygen gas is given out in abundance. This remarkable evolution of gas, which uniformly took place, led to the conclusion, that the oxide was not the protoxide, but the peroxide of nickel ; and that it had been peroxidized during the pro- cess of ignition. To determine this point, I put 10 grains of it into a small ball blown in a green glass tube. This tube was attached to another, containing fragments of fused chloride of calcium, connected with a small Woulfe's bottle, in which hydrogen gas was evolved by the solution of zinc in dilute sulphuric acid. After all the common air had been expelled, and the tubes filled with hydrogen gas, a spirit lamp was placed under the oxide of nickel, and kept under it till it was gradually raised to a red heat. During the whole pro- cess a current of hydrogen gas was passing through the tube, and it continued to pass till the experiment was finished and the apparatus cold. It is well known, that under these circumstances, the oxide of nickel is rapidly reduced to the metallic state. The object of the experiment was to deter- mine the loss of weight which the oxide of nickel would sustain when reduced to the metallic state. The experiment was made thrice successively. The following table shows the results : Oxygen. 1. 10 grains oxide when reduced, lost 3*33 grains. 2. 10 2-95 3. 10 • . . 3-57 Mean 328 of Nickel and its Oxides. 329 The oxide of nickel obtained then is a compound of, Nickel . . . 6-72 or 3-25 Oxygen . . . 3-28 or 1-58 10-00 It is obviously the peroxide of nickel obtained by RothofT, and which he showed to be a compound of 1 atom metal and 1^ atom oxygen/'^ If we were to consider the result of this analysis of sulphate of nickel and peroxide of nickel as perfectly accurate, the atomic weight of nickel would be only 3-085. But, I consider my original number, 3*25, founded on the determination of the sulphuric acid in a given weight of the sulphate by double decomposition as susceptible of far greater precision, and, therefore, more to be depended on. Meanwhile, the preceding experiments leave no doubt about the cause of the different atomic weights given to nickel by Berzelius and myself. He has adopted the numbers derived from the experiments of Tupputi and of Rothoff, and these chemists have mistaken the peroxide of nickel for the protoxide. It may be worth while to correct my analysis of sulphate of nickel, by changing the peroxide of nickel obtained into protoxide. Reducing the peroxide, on the supposition that • As a further corroboration of this constitution I may mention another expe- riment. 10 grains of the same black oxide were mixed with 17-63 grains of a sulphuric acid, composed of 1 atom acid, . .' 5* 3 atoms water, 3'375 8-S75 and, therefore, equivalent to 10*525 grains anhydrous acid. The solution took place slowly and with effervescence, but was complete. It was placed under the exhausted receiver of an air pump over sulphuric acid. It crystallized to the very last drop. It was left under the receiver till the crystals had eflEloresced, all except a few large ones in the centre, which continued green and translucent in the middle, though tlie surface had effloresced. The salt weighed 27*5 grains. It was composed of Acid 10-525 or 5* Oxide of nickel 8-947 or 4-25 Water 8-028 or 3*813 Had the large crystals not retained too much water, it is obvious that there would have remained exactly three atoms water ; so that four had escaped. The excess amounted to about two-fifths of an atom. This does not prove the oxide to be protoxide, but it shows that the atomic weights of the oxides of nickel are 4*25 and 4*75. 330 Dr. Thomas Thomson on the Atomic Weight, Spc. an atom of protoxide of nickel weighs 4*25, and an atom of peroxide 4*75, we have, Protoxide of nickel . . . 24-67 or 4-218 Sulphuric acid 29-24 or 5* Water ....... 46-09 or 7-881 100-00 The water of crystallization, in this case, is very near seven atoms, exceeding that number by only 0*006 or only y-Lpth part of an atom. I think the reason of this small anomaly, making the atom of protoxide of nickel 4-218, instead of 4-25, is probably, that a small portion of the oxide of nickel examined, may have existed in the state of protoxide. For I find that by long exposure to an intense red heat, the oxygen in the black oxide of nickel is sensibly diminished. I once succeeded in getting an oxide by intense heat of an ash gray colour, with a very sliglx^ tint of green, which was reduced by means of hydrogen gas in the way above described. 5-05 grains of it sustained a loss of 1-19 grains. Hence, it was composed of. Nickel 3-86 or 3-25 Oxygen 1-19 or 1-001 5-05 so that it was very nearly in the state of protoxide. But, a strong and long continued heat is requisite to bring it to this state. From the experiments stated in this paper, which were made with every possible attention to accuracy, no doubt remains on my mind that the atomic weight of nickel is, as I long ago stated, 3*25, and thatRothoff's number 3-716 is the consequence of his having taken the peroxide of nickel for the protoxide. I must, therefore, retract the statement made in the Records, (vol iii. p. 255,) and admit that the error lies not in the atomic weight of nickel, but in the number given by Dulong and Petit for the specific heat of that metal. If the specific heat of nickel be 0-1 15, instead of 0*1035, then the law of Dulong and Petit would apply with accuracy to that metal, supposing its atomic weight to be 3*25, as I believe it to be. M, JE, Mitscherlich on Manganic Acid, Sfc, 331 Article III. On Manganic and Hypermanganic Acids, on Hyperchloric Acid and the Salts of these Acids. By E. Mitscherlich. {Concluded from page 183.) If hy permanganate of potash be dissolved in a solution of potash, and the solution evaporated under the air pump over sulphuric acid, the red crystals of hypermanganate of potash again make their appearance, only a very small quantity being decomposed. A very dilute solution of hypermanganate of potash is converted by caustic potash, in the cold gradually, but when heated more quickly into manganate of potash.* The solution must, however, be so dilute, that the liquid is sufficient to absorb the oxygen which is extricated. If the decomposition happens slowly, the quantity of the green increases gradually, the red at the same time diminishing till at last the liquid becomes quite green, and, during the change, a succession of colours is observed, produced by the mixture of the green and red in different proportions. From these alterations of colour this solution has been called chameleon mineral. If an acid be added to the green solu- tion it becomes again red, binoxide of manganese at the same time being formed, and precipitated in the form of a brown powder. One grain hypermanganate of potash, treated with nitric acid, and heated till the acid was completely decomposed, gave out 105*9 C.C. dry oxygen gas, or 0*1518 gr. oxygen. The filtered hydrated binoxide when ignited was converted into 0*4785 gr. of red oxide, which consists of 0*348 gr. manganese, and 0*1305 gr. oxygen. 0*348 gr, of man- ganese acquire 0*196 gr. oxygen to be converted into binoxide. Now, 0*196 : 0*1518 :: 4 : 3*1. Hence, hyper- manganic acid contains 7 atoms oxygen and 2 manganese. According to another experiment, 0*5 gr. hypermanganate of potash yielded 52*5 C. C. oxygen gas. In a third, 2 grs. of the salt gave 0*985 gr. of red oxide, which corresponds with 1*42 gr. of hypermanganic acid, and 1*295 gr. nitrate * According to HopfF (Central. &fa«, September, 1836), carbonate of manganese answers better for the preparation of manganate of pota^ than the binoxide. — Edit. 332 M. E, Mitscherlich on of potash containing 0*6077 gr. potash. Hence, 100 parts of hypermanganate of potash contain Oxygen, Hypermanganic acid, . .71* 35*2 Potash, 30-135 5-1 The oxygen of the potash is, therefore, to thai of the acid in this experiment as 1 : 69, whence, it follows that the true proportion is as 1 : 7. The composition of the hyper- manganate of potash calculated after these data, is Hypermanganic acid, . . 70*53 Potash, 28*47 Several experiments, which were made before I determined the best method, agreed very nearly with this result. The hypermanganate of potash is little soluble in water, 1 part requiring, at 59° F., 16 parts of water to dissolve it. All the other salts of this acid are much more soluble, except the hypermanganate of silver, 1 part of which dis- solves in 109 of water. I have not observed any insoluble salt which it forms. Hypermanganic acid has so great an affinity for potash, that it will, when combined with it, unite with no other base by double decomposition. For example, a solution of hypermanganate of potash may be mixed with a solution of chloride of barium, and the mix- ture evaporated. The hypermanganate of potash will crystallize along with the chloride of barium without any interchange of the acids taking place. Hence, the salt which hypermanganic acid forms with oxide of silver is the only one convenient for combining it with other bases. If a warm solution of nitrate of silver be added to a warm solution of hypermanganate of potash, the hypermanganate of silver separates as the solution cools, in large, beautiful, easily measurable crystals. These crystals may be dis- solved in water and re-crystallized, but the solution must not be boiled, or it will be decomposed, which does not happen if it be cautiously evaporated. By means of the hypermanganate of silver the other salts of this acid may be formed, by adding to the crystals of this salt as much of the solution of any chloride as is necessary to decompose them. The crystals must previously be reduced to a fine powder, and they must be stirred for a long time with the solution of the chloride. The chloride Manganic and Hypermanganic Acids, ^c. 333 of silver must be washed by decantation, and if any of it get mixed with the solution, it must be allowed to sink to the bottom, for we cannot, as has already been mentioned, filter any of these compounds ; we may, in this manner, obtain compounds of hypermanganic acid, which is a very powerful acid, with all the bases, except oxide of lead, pro- toxide of manganese, and protoxide of iron ; but these bases deprive it of its oxygen, and become more highly oxidized. Most of the salts of hypermanganic acid are very soluble in water, and deliquescent. Such, for example, are the hypermanganates of soda, lime, strontian, magnesia, zinc, copper, and many others. The hypermanganates of am- nionia, potash, lithia, and barytes are the only salts which can be obtained in good and measurable crystals ; which I shall immediately notice. If the hypermanganate of barytes be dissolved in water, and a sufficient quantity of sulphuric acid be added to pre- cipitate the barytes, we obtain free hypermanganic acid in solution in water. The solution has a deep red colour similar to that of the salts. It being summer when these experiments were made, I could not succeed in concentrating the hypermanganic acid. It is decomposed, though very slowly, even at the common temperature of the air, and with great rapidity at a tem- perature from 86° to 104°, binoxide of manganese being precipitated, and oxygen making its escape. It is, as follows from what has already been said, not volatile. This acid excels even the deutoxide of hydrogen in the facility with which it gives off oxygen. The different vegetable and animal pigments are immediately bleached by it. The salts have also the same effect, although in a less degree. Hypermanganate of ammonia, is not liable to decompo- sition, but may be dissolved and evaporated to dryness. If, however, an excess of ammonia be added to any salt of hypermanganic acid, azote is immediately extricated, the ammonia and the acid being decomposed. I tried to deter- mine the composition of the acid from the quantity of azote extricated, but I could not succeed, because there is also pro- duced by the decomposition a compound of oxygen and azote. What has previously been considered as manganic acid, was either hypermanganate of potash or of barytes. 334 M, E. Mitscherlich on 4. Analysis of HyperMoric Acid, and Hyperchlorate of Potash. As the salts of hyperchloric acid promised very important results respecting the connexion between the crystalline form and the composition of substances, I had prepared them long ago in considerable quantity. Hyperchlorate of potash is easily formed, by placing a vessel with sulphuric acid in the open air, and throwing into it, in small quanti- ties at a time, fused chlorate of potash in fine powder, at the same time heating the sulphuric acid slightly. If one part of chlorate of potash be added to one part of sulphuric acid, both are completely decomposed, sulphate of potash, perchloric acid, and chlorous acid being formed. The chlorous acid is extricated either undecomposed or as chlo- rine and oxygen, and there is no danger to him who per- forms the experiment, if he take care not to breathe the gas which is extricated. The hyperchlorate of potash is not very soluble in water, while the bi-sulphate of potash is very soluble ; hence, these salts may easily be separated by crystallization. In determining the crystalline shape of the hyperman- ganate of potash, which, at the commencement of my experiments, I considered as an acid manganate of potash, I had convinced myself that it was the same as that of the hyperchlorate of potash. From this I suspected at first that hyperchloric acid contained only six atoms of oxygen. At any rate, it was evident that the experiments of Stadion, in which he found this acid to contain seven atoms of oxygen, would require to be repeated, as this proportion had never been observed in any other compound. This induced me, even before I had analysed the hypermanganate of potash, to investigate the hyperchlorate of potash. The hyperchlorate of potash may be freed entirely from mechanical water by heat, particularly if it has previously been pounded. Only a low red heat is required to decom- pose it, but towards the end of the ignition it must be raised slightly. The chloride of potassium is at this temperature very volatile, and is partially carried away in vapour along with the oxygen, and carried with it out when it cools. To prevent this as much as possible, the operation must be conducted very slowly, and a long barometer tube, with a Manganic and Hy permanganic Acids ^ 6fc. 335 bent tube attached to it, employed instead of a retort, to allow the chloride of potassium to be deposited. 0*600 gr. hyperchlorate of potash, yielded in one experi- ment 192*1 C.C. oxygen gas, or by weight 0*275 gr. The same quantity in another experiment gave 191*9 C. C. or 0*2749 gr. oxygen. Now, (600 - 275) : 275. :: 100 : 84*73 If the hyperchloric acid contain 6 proportions of oxygen, then for every 100 parts of chloride of potassium there would be 75*04 of oxygen ; but if it contain 7, then each 100 parts of chloride of potassium would be combined with 85*76 parts of oxygen. The same proportion was obtained by weighing the residue after the ignition of the perchlorate of potash. And, although this experiment from the escape of a small quantity of the chloride of potassium, can never be so accurate as the former, yet it agrees with it very well. 2*7155 gr. ignited lost 1*2515 in weight, so that for 100 parts of chloride of potassium there were 85*5 of oxygen. 5. Crystalline form of some Hypermanganates and Hyper- chlorates. It follows from these experiments, that Stadion's result is correct. The experiments on hypermanganic acid show that it also contains seven proportions of oxygen. The same difficulty which exists in the preparation of the hyper- manganates, interferes also with that of the hyperchlorates. The hyperchlorate of potash is the most difficult to decom- pose of all the salts of that acid, so that the others can only be formed by means of fluosilicic acid. I precipitated the hyperchlorate of potash with the fluosilicates of am- monia, copper, lead, and several others, or else I decom- posed the salt by the fluosilicic acid, and then combined the acid with a base. All the hyperchlorates, except those of potash and ammonia, are very easily soluble in water. Most of them are volatile, as for instance, the hyperchlorates of soda, barytes, lime, copper, lead, and some more. The crystalline form of the salt of silver, which is also very soluble, is distinguishable, but not sufficiently so to measure. It is soluble in ammonia and forms with it a crystallizable com- pound. The only salts whose crystalline shape I have been able to measure accurately, are the hyperchlorates of 336 Mr, Exleys New Demoiistration ammonia and potash, which are isomorphous with the cor- responding hypermanganates. The primary form is a right rhombic prism. The crystal of the hypermanganate of silver is an acute rhombic prism. The form of the hyper- manganate of barytes is completely similar to the anhydrous sulphate or seleniate of soda. The same correspondence which exists between the cry- stalline shape of the hyperchlorate and hypermanganate of potash and ammonia, and that of the sulphates of barytes, strontian, and lead, is to be found also between the crystal of the hypermanganate of barytes and that of the sulphate of soda or silver. It would seem that the law of this cir- cumstance, of which I have already given several examples at different times, lies very deep, and that its discovery will, perhaps, enable us likewise to calculate the crystalline form of compound substances from that of their elementary constituents. The isomorphism of the compounds of hypermanganic and hyperchloric acids is an important fact with respect to the connexion between the crystalline form and chemical composition of substances, because it enables us to compare the greater part of the metals with several simple gaseous substances. Manganese in its lowest degree of oxidation being isomorphous with lime, oxide of copper, protoxide of iron, &c. The sesquioxide of manganese being isomorphous with the peroxide of iron, the oxide of chromium, and alumina; manganic acid being isomorphous with chromic acid, sulphuric acid, and selenic acid ; and hypermanganic acid being isomorphous with hyperchloric acid, we may compare the above mentioned metals, sulphur and selenium, with oxygen, iodine, bromine, and chlorine. Article IV. New Demonstration of the Law of Mariotte, with Corrections of a former 'pa'per . By Thomas Exley, A. M. {To Br. R, B, Thomson.) Dear Sir, — I find there is a fault in one of the steps of the demonstration of the 2nd prop, relating to the com- position of the forces, which I did not perceive till it was particularly pointed out to me by my friend, Mr. Horner, of Bath : I, therefore, wish to substitute another proof; I of the Law of Mariotte, with Corrections^ Sfc. 337 had one which showed, that the prop, is true in general, if it is so in any particular case, and that case could easily be derived from experiment. However, in re-considering the subject, I discovered the true demonstration, first proving, from the theory, Mariotte's law, or the 4th prop, in the paper, and then the 2nd as a corollary ; therefore, instead of the 2nd and 4th propositions please to insert as the 2nd the following, which, with the 1st cor., includes them both : the rest of the paper will then remain good, making only one or two very obvious changes in the references. Before introducing the new proof, it maybe observed, that in fig. 1, p. 273, the inner concentric spherical vessel V P W is supposed such as to confine the tenacious atoms, but to admit a perfectly free communication to those of the ethereal class. Now, it will easily be seen, that a certain number of tenacious atoms in the inner vessel will form a concentric spherical mass; and, when the number is such, that this sphere has a less radius than that of the vessel, there will be no compression of the tenacious atoms by the re-action of the surface V P W, the density of the tenacious atoms, at that surface, being in this case nothing. But when a greater quantity is introduced, there will arise a compression from the re-action of the surface, preventing the extension of the sphere of tenacious atoms. Prop, 2. (prop. 4 of the paper.) If the pressure atT on the exterior vessel, fig. 1 , be given, and a body of tenacious atoms in the inner vessel be compressed by a force, as at the piston P, but such, that the tenacious atoms may be kept apart by intervening ethereal matter ; then, the compressing force at P will vary as the density of the body of tenacious atoms. For, suppose the increment of density produced by an increment of the compressing force to be divided into a number of equal parts, and the increment of pressure into the same number of parts, such, that taken in order from the beginning, each shall produce one of the equal parts of the increment of density : let the number of these parts be increased, and, consequently, their magnitude diminished without limit. Then, taking u for the compressing force, and X for the density, the ultimate, or nascent ratio of the d u increments will be -, — in which d x is constant, since all d X VOL. IV. 2 338 Mr. lExley*s JVev) Demonstration the parts of the increment of a; are equal. Again, because the pressure at T is given, and there is a perfectly free communication of the ethereal atoms between the two vessels, and the tenacious atoms in the inner vessel are separated by intervening ethereal matter, the initial resist- ance to any increment of density, that is, the re-action of the ethereal atoms between those of the tenacious class is always the same, being in equilibrium with the given pressure at T, therefore d u is constant ; hence, it follows, d u that T— = a, where a is a constant ; therefore, u = a x, dx which needs no correction, because when the compressing force is nothing, the density at the surface V P W is nothing, as shown above : therefore, u is proportional to x, or the compressing force to the density is a constant ratio, which was to be shown. Cor. 1. (prop. 2 of the paper.) The resistance between two tenacious atoms, which opposes an additional com- pressing force on the inner vessel, is inversely as the distance between the two atoms. By this proposition the compressing force varies as the density, and the density varies inversely as the cube of the distance between adjacent atoms ; therefore, the com- pressing force varies as the same cube ; but it also varies as the number of atoms on a given surface and the force of each ; now, the number of atoms on a given surface is inversely as the square of the distance ; therefore, the force of each is inversely as the distance. Scholium 1. It might, perhaps, at first seem strange to. some, that the limit of the ratio of the compressing force and the density should always be the same, and yet, that the actual resistance to a definite additional compressing force should vary : but the difficulty will vanish by a little atten- tion to the 1st prop., which shows that the tenacious atoms are invested with atmospherules of ethereal matter in- creasing in density to the surface of repulsion ; hence, as these approach nearer together up to a certain term, there will be a denser and greater portion of ethereal matter to be acted on, and pressed against the spheres of repulsion, and forced out from between the tenacious atoms, than when these tenacious atoms are at a greater distance; hence, of the Law of Mariotte, with Corrections^ Sfc. 339 the reason for a variation is manifest, and its law is seen from the above corollary, which is the proof of the 2nd prop, in the paper. Cor, 2. During an increase of compression, ethereal atoms will be continually given out from the inner vessel, and during a diminution of pressure they will be absorbed. Cor, 3. After a certain limit of pressure, two adjacent tenacious atoms will enter at once into union. For, although the atmospherules of the tenacious atoms are more dense as we approach the surfaces of repulsion, yet, when these surfaces, after contact, intersect each other, the atmospherules will begin to be repelled from the line immediately between the centres ; hence, a limit to an increase of assistance from intervening ethereal atoms will be attained, and union of the tenacious atoms will occur on a small additional pressure, for this effect will be pro- moted by the pressure, and the greatly increasing attraction of the atoms. Cor. 4. Hence, when a gas liquifies by compression, the main body of the gas will become liquid at once. For, in common circumstances, since the pressure is nearly the same throughout the vessel, the point of equi- librium will be attained very nearly at the same time in every part of the vessel. Cor, 5. A little before liquifaction the ratio of the com- pression to the density will diminish. For, when the equilibrium is just attained, the operation of the law ceases, since the ethereal atoms begin to be removed from the line joining the centres, and the resist- ance diminishes. Cor, 6. The resistance to compression will be much greater in liquids than in gaseous bodies, and will follow a different law. For, the repulsion between tenacious is vastly greater than between ethereal atoms; and the resistance in this case does not depend on the pressure at T. Cor, 7. When a gas becomes a liquid, abundance of ethereal matter will be evolved ; and the converse. Cor, 8. The compressing force varies inversely as the volume, because the density varies in that ratio. Scholium 2. That the density of air varies as the com- z 2 340 Mr. Exleys New Demonstration, ^c. pressing force, within certain limits, has been long estab- lished : it was usually called the Boyleian law, but now the law of Mariotte. Sir I. Newton, in the Principia, b. ii. p. 22, Sch., says, " But, as to our own air, this is certain from experiment, that its density is either accurately or very nearly as the compressing force." Modern philo- sophers have removed some sources of error, and verified the truth of the proposition through a very extensive scale of compression. Now, it must be considered as a strong evidence of the defects of every received theory, that none afforded a solu- tion of this simple phenomenon, not even when applied by the powerful mind of Newton, or Laplace, or the host of great names which have graced the annals of science since the times of Boyle and Newton. Hence, this proof of the pro- position must be considered as sufficient of itself to stamp a character of truth on the theory from which it is obtained. The corollaries are added as easy deductions, and because most of them are experimental results, not previously demonstrated from theory, the pressure at T may be con- sidered as representing temperature ; for it is very probable that ethereal matter at rest is insensible caloric and absorbed light ; and the same in motion is sensible caloric, or light according to its velocity : see my Treatise on ** Physical Optics." The terrestrial atmosphere, according to this theory, consists of tenacious atoms separated by ethereal matter, which extends, perhaps, several hundreds of miles above the highest stratum of tenacious atoms ; and this ethereal matter will produce a pressure similar to that of T in common circumstances ; while the same augmented or diminished by local causes answers to the same pressure exerted in a greater or less degree. According to this rational view, cors. 2, 4, 5, 6 and 7, are theoretical proofs of well known experimental facts, which, I presume, cannot be explained on any other general principles. With jny best respects, I remain, dear sir, yours truly, Thomas Exley. Bristol, Oct. 7th, 1836. Errata in last Number, page 277, line 4 from bottom, for two read three. „ 28.0, "„ 6 from top, for 16+16 read 14-f 16. Mr, W. Galbraith on some Astronomical Methods, Sfc. 341 Article V. On some Astronomical Methods of Observation, By William Galbraith, A.M., Teacher of Mathematics, Edinburgh. {Concluded from page 194.) The following pages contain the methods of registering the indications of the level. The first is that generally adopted by the French mathematicians, such as M. Puissant, and the other the method practised by the writer of this paper, which he thinks more simple, and is that employed in the preceding example, the first instance so far as he is aware of the obliquity of the ecliptic, being determined at Edin- burgh, and that to a very great degree of accuracy by observation. In these means no errors or discrepancies amount to more than one-third of those in Rumkers obser- vation of the latitude of the observatory of Paramatta, under Sir Thomas Brisbane, where it is stated, in Phil, Mag,, vol. i. new series, p. 302, that differences to the amount of 15" are to be found between observations on /3 Argus and those on the solstices and Zodiacal stars. See also the Brisbane Catalogue of Stars just published. Method of M. Puissant, Traite de Geodesic, T.I. p. 165. MARCHE DU NIVEAU FIXE. | Object. difF. Observateur. + difF. Observateur _^ a Object. h 527 49i~~ ^ 5^ I 3 55 \ ^ 5U . 50^- ^ 53 \^.. 54-5) ^^ .51) 54 I , 55 \ ^ ^1 1 ~ 2 49/ ^ 54 \ 56 5 ^ 49^ ^ 56 \ ^ Somme des a — — 8 Somme des h = — 8*5 Inclination du axe de rotation = —r. — = — 0*825 2 n Factem constant, 11*51 Product ou correction du niveau = — 9"*50 342 Mr. William Galhraith on some Method of W. Galbraith. FIXED LEVEL. e 0 49 52 52 55 50 51 53 54-5 50 51 54 b^ 49 51 54 56 49 50 55 6Q e t= 515 531-5 0 = 531-5 e — o = '/ __ (g -— o) a - 16-5 ' — 16-5 X ir^-51 20 = — 9 '-496 = the correction of the level with its proper sign. This last method is very easy when the divisions of the level read from a central zero, but cannot he so well prac- tised by a scale having two zeros. The preceding is the commencement of a series of obser- vations on the obliquity of the ecliptic, which it is intended to be continued for some time, to ascertain the accuracy of a circle of very moderate dimensions. By the facility of repeating the observations, and the general stability of the instrument from the nature of its construction, much more accurate results may be obtained than is generally supposed. It is well known that the latitudes of different points in the trigonometrical survey were determined by a zenith sector of eight /6fe^ radius, while those of the French arc of the meridian were observed with one of Borda's repeating circles of about eight inches radius, and it is at least doubtful, which of the two is, on the whole, the more correct, the accuracy arising from the facility of repeating the observations in the latter case being nearly equivalent to that derived from the greater dimensions of the instru- ments in the former. Astronomical Methods of Observation, 343 Determination of the Time of the Equinox Z>y Observation. A B Let w A be the ecliptic, w B the equator, and the angle A w B the obliquity of the ecliptic, w /3 the motion of the sun in one day from the equinoctial point w, and a /3 the correspond- ing change of declination , which at the present time is 23' 40" at the vernal equinox, and 23' 24' at the autumnal, which it has been and will continue to be for some time, on account of the slow motion of the perigee and the action of the planets being nearly insensible, or at least very small. By similar triangles, «/3 : /3 w :: A B : Bo, or 23' 40'' ; 1'':: AB : B w in March. 23 24 : l^'riAB : B w in September, the time from the equinox in days and fractions, depending upon the observed declination A B. The first analogy gives 1"^-014085, and the second l°^-02564 for each second of arc in the declination A B. For days and decimal we would have, I., const, log. 6-847712, II., 6-852633. It would be a little more accurate to take the change of declination from observations, by good instruments or from accurate astronomical tables, on account of the slight change in the daily variation, which we have assumed to be constant for a few days before and after the equinox. Ex. September 25th, 1835, in latitude 555656'4 and lon- gitude 12' 44" W, the observed zenith distance by Kater*s inch was 56^ 37' 5"-4 S Lat. of 54 South Bridge • 55 56 56-4 N Sun's declination South 40 90 S II. Constant logarithm 6*852633 Dec. 40' 9 " = 2409" log 3.381837 Time after eq. 1^^-7158 log 0-234470 344 Mr. P. Cooper on Capillary Attraction, Day of Obs. 25 Equinox 23-2842 = Sept. 23** 6»» 49" at Edinburgh, or 23d 7h2m at Greenwich. In this manner were determined, 1. Sept. 18th, by observation . . . 23'^-2785 2. „ 23 -2692 3. „ 24 -2806 4. „ 25 -2842 5. „ 26 -2699 Mean 23-2765 h. m. s. On Sept. 23rd, at 6 38 10 Longitude in time ...*... -f- 12 44 W Time at Greenwich ...... 6 50 54 By Nautical Almanac 6 57 6 Difference — 612 which might arise from an error of 5" or 6" in the aggregate of the latitude and observed declinations, and on account of the unfavourable state of the weather in Sept. last. William Galbraith. 54, South Bridge, June I, 1836. Article VI. On Capillary Attraction, and on the disposition there is in Fluids to assume a Globular Form; with introductory observations upon some galvanic combinations connected with the explanation of these subjects. By Paul Cooper, Esq. I HAVE lately published a sketch of a system of natural philosophy, which appears to me to connect the operations of nature upon general principles ; and wishing to obtain the opinions of philosophers as to the correctness of my views, before I publish the work from which the abstract is taken, I beg to submit the following paper to your readers, although the subjects, I trust, are sufficiently im- portant to claim their attention, partly for the purpose of illustrating the principles upon which it is founded. It is assumed in this theory, that bodies are formed of and the Globular Form of Fluids. 345 matter, consisting of globular atoms of different sizes, having an attraction for each other in the direct proportion of their bulk, or quantity of matter, and inversely as the square of their distance ; and of light, consisting of globular atoms, constantly separated by a repulsive force, regulated by the same law of distance, uniform in size, and much smaller than the atoms of matter ; for which they have an attraction, also regulated, both with regard to distance and dimensions, by the laws already mentioned. The light under the influence of these laws must sur- round the atoms of matter, forming what we have called an atmosphere about each atom, and this atmosphere will be held in its position by various degrees of force, which will draw the atoms of light nearer to each other as they approach the atom of matter, and thus give it greater in- tensity. The atmosphere, it is supposed, will be divided into strata of different intensities, forming concentric spheres ; every atom of light at equal distances from the centre, being held in its position by equal forces. The point of saturation, under ordinary circumstances, will be when the repulsive force of the light is sufficient to counteract the attraction of the central atom of matter ; when, with the exception of the attraction of the atoms of matter for each other, forming the force of gravitation, the atoms will be neutral ; the two opposing forces of attraction and repulsion being equal at all distances. If, under these circumstances, an unlimited number of atoms of equal size are brought together, although every atom of light will act upon every other atom of light, agreeably to the law of distance, precisely as if it were unattached, it is evident that the atmospheres of the atoms of matter will continue uniform, because the forces which surround each of these atoms are every where equal. But, if atoms of different sizes, and, consequently, with different forces at the points of contact, are introduced to each other, the superior force of the light of the positive atom will repel the light of inferior force upon the negative atom, and both classes will acquire positive and negative surfaces on the opposite sides of the several atoms. If, for example, we bring an equal number of atoms of oxygen and hydrogen together, the oxygen being positive 346 Mr. P. Cooper on Capillary Attraction, when compared with hydrogen, the superior force of the former will repel the inferior force of the latter, so as to render the surface of the hydrogen in contact with the oxygen still more negative ; while, on the other hand, the light which forms the atmospheres of the oxygen will flow towards the hydrogen, and thus render the surface of the oxygen in contact with the hydrogen still more positive. In this state there will be an attraction between the oxygen and the hydrogen ; because the reciprocal attraction of the light of contiguous atoms is only neutralized by the repulsive force of the same light when the atmospheres of the atoms are uniform ; for the attraction being as the sum of the forces upon the contiguous surfaces, every atom of light attracting every atom of matter, remains unchanged by an unequal distribution between them; whereas the repulsion being as the forces multiplied into each other, every atom of light repelling every other atom of light, is lessened by inequality, although the force taken from one surface be added to the other. In consequence of this attraction, the oxygen will have an affinity for the hydrogen, and the atoms will alternately unite with each other ; the positive surface of the atom of oxygen with the negative surface of the atom of hydrogen, and the positive surface of the atom of hydrogen with the negative surface of a second atom of oxygen, which will leave its positive surface ready to unite with another atom of hydrogen -* as in the annexed figure. OH OH OH — OH 0+ — »H 0+ — OH OH- &c. &c. A B CD E F Bodies which consist of single proportionals, whether solid or fluid, are formed upon the same general principles. The dissimilar atoms are united by the positive surface of the positive atom, and the negative surface of the negative * If we suppose the atoms of oxygen and hydrogen to be united by cohesion, this will form two particles of water. These two particles of water will be united to each other by the positive surface of the hydrogen of one particle, and the negative surface of the oxygen of the other particle ; a very inferior force to tliat which unites the atoms to form the particles ; and as a second atom of oxygen is held by an atom of hydrogen, to form a particle of oxygenated water, by tJie same force, as may be seen from the above description, it accounts for the ease with which the combination thus formed sufl'ers decomposition. and the Globular Form of Fluids, 347 atom to form particles ; and the particles thus formed are united by the positive surface of the negative atom, and the negative surface of the positive atom to form lines of particles ; which are again united, in the same order, in two directions perpendicular to each other and to the first line, to give to its length, breadth and depth. So that each atom must have three positive and three negative surfaces; and as the electrical forces by which they are generated are precisely equal, the atom of oxygen being in contact with an atom of hydrogen, and the atom of hydrogen in contact with an atom of oxygen at three points equidistant from each other, the polar forces produced by their action must also be equal ; and, in th6 absence of other polar forces or disturbing causes, at right angles to each other.* There are some circumstances attending arrangements of this description, in which polar forces are generated by the action of contiguous surfaces in different electrical states, that deserve our attention. Whatever may be the nature of the bodies A B C D, &c., whether they consist of atoms of oxygen and hydrogen, or plates of zinc and copper, or of any other bodies, provided the alternations are different in electrical force, they will form a galvanic series with properties which, iu many respects, are common to all. It is evident, that however we extend the series ABC, &c., there will be a positive surface at one end, and a nega- tive surface at the other unconnected. These surfaces, if in contact with the air, or with any other inferior conductor of derangement, will resist the electrical force of the bodies O H, O H, &c., and this resistance, re-acting upon every part of the series, will prevent the full derangement of the different surfaces which their inductive influence upon each other disposes them to acquire. If, then, we connect the negative surface of A with the positive surface of F, by means of an equally good conductor, with the bodies ABC, &c., the resistance being removed, these bodies will assume a state of derangement in equilibrium with the forces ; to complete which, the light will flow, • This arrangement forms the three directions perpendicular to each other, ■which Fresnel calls axes of elasticity ; and, as in the formation of water, by which it is here illustrated, the force is the same in all three directions, the light transmitted by this fluid is free from double refraction. 348 Mr. P. Cooper on Capillary Attraction^ simultaneously, from the negative surface of A, through the conductor, to the positive surface of F, from the negative surface of B to the positive surface of A, from the negative surface of C to the positive surface of B, from the negative surface of D to the positive surface of C, from the negative surface of E to the positive surface of D, and from the negative surface of F to the positive surface of E ; so that the actual quantity of light between these bodies will be constantly the same, but differently distributed upon the contiguous surfaces. This is the foundation of galvanism ; if we suppose the series ABC, &c., to be formed of alternate plates of zinc and copper, the zinc supplying the place of the atoms of oxygen, and the copper those of the atoms of hydrogen, upon connecting the positive surface of F with the negative surface of A, the light will flow through the conductor from A to F to complete the increased derangement of these surfaces, arising from the removal of resistance and their inductive in- fluence upon each other. But the light which flows through the conductor, so far from circulating through the whole of the series, is only what is required to produce an equi- librium between the exterior surfaces of the first section of atoms upon the surfaces of the end plates ; every other section of atoms in the interior of these plates, and through- out the series, being brought into the same state by an equal transfer between contiguous surfaces, in the manner we have already described. Upon breaking the communi- cation between A and F, the plates return to their previous state, and are thus prepared to repeat the operation when the conductor is re-placed. The great disparity in the lifting and sustaining power of electro-magnets arises from the reduction of the derange- ment of the magnet, when the circuit is interrupted by the removal of the armature, upon the principles here stated. In consequence of the great increase of force derived from the completion of the polar circuit, bodies in a state of derangement are constantly disposed to produce the necessary communication between their opposite surfaces, through the medium of intermediate bodies, although they may be very inferior conductors. The magnetic curves formed in the air, and rendered visible by means of iron and the Glolular Form of Fhiids. 349 filings, are of this description. These curves in the air continually endeavour to bring the two ends of the com- pass-needle together, to form a magnetic circuit by a more direct communication ; and it is the predominant force of these curves, when their equilibrium is destroyed by the interposition of a magnet, that gives motion to the needle in obedience to its distant force. These curves, or rather curves formed upon this prin- ciple, which can only give motion to the solid needle as a whole, acting in the same manner, produce the actual union of the unconnected surfaces of a line of fluid par- ticles, such as are described in the figure, by bending the line so that the two ends may meet. All bodies having polar forces are disposed to unite their terminating surfaces in this manner, and would do so if they had freedom of motion. But there is a force op- posed to it, even in fluids ; and it arises from the position of the poles, which being opposite to each other upon the several atoms, disposes the particles to form right lines ; when, therefore, the line is bent so that its two ends may be united, this force brings it into a circle by the equality of its resistance. It is, in fact, in the state of an elastic rod, the two ends of which are brought together; and the forces that give to both a circular form are similar. The union of circles of particles formed in this manner, which intersect each other upon the principle we have already described, produces globules, or drops; and it is the same arrangement, which is liable to unlimited increase from concentric layers of particles, that gives the rounded form to fluids generally, when they are not attracted by the con- taining vessel, and which is more particularly observable in mercury, and other metals when reduced to a fluid state by fusion ; the latter case differing from the former, only in the flattened form of the larger quantity by the force of gravitation, from which globules are exempted by the greater force required to bend the lines which form their surfaces; upon the same principle that a rod of great length in proportion to its elastic force will bend by its own weight, when formed into a circle and placed in a vertical position ; whereas a small part of the same rod, 360 Mr. P. Cooper on Cajnllary Attraction, brought into the same form, will, in addition to its weight, resist a considerable pressure.* The disposition which is found in fluids to assume a globular form, cannot be derived from any central force ; for if there were any such force in one particle, from their exact similarity, there would be the same force in every particle ; and these equal forms, disposing each of them to be the centre of its own system, would destroy each other. It is only, however, in the absence of bodies with sur- faces favourable to a union with the positive and negative terminating surfaces of the lines of fluid particles, that this circular arrangement is made ; we have already observed that there is a force constantly opposed to it, and the mo- ment such surfaces are presented, this force urges the fluid particles to resume their rectilineal position to form a union with them. In this state, the inductive influence of the positive and negative terminating surfaces of the fluid particles, produces a considerable degree of attraction be- tweeen the fluid and the surface of the solid to which it is by these means united, and the lines of particles, which, for instance, stretch from one side of the containing vessel to the opposite side, adhere to these surfaces with con- siderable force. In consequence of this adhesion, when the two surfaces to which the lines are attached are very near to each other, as in capillary tubes, the weight of these lines of particles is in a great measure removed from the surface of the fluid and transferred to the sides of the capillary aperture, like ropes stretched between two opposite walls ; the included column, in consequence, presses with less weight upon the liquid surface than similar surrounding columns, and to • It is probable, that water in a gaseous form is divided into particles, consist- ing of an atom of oxygen and an atom of hydrogen ; that, when it forms a visible vapour, whether under the appearance of clouds, or in steam, or dew, these particles are united into globules, varying in size under different circumstances, until they become too large for their external atmospheres of light to support them ; and they descend in rain, or when frozen in this globular state, in the form of hail. Snow, on the other hand, and all those efflorescent incrustations of ice which are formed by the progressive crystallization of water floating in the atmosphere, are probably produced by the union of particles in right lines, the terminating surfaces of which being unconnected, are constantly prepared to unite with any other particles that approach within the sphere of their attraction. and the Globular Form of Fluids. 351 produce an equilibrium, more of the fluid is forced into the aperture ; this is suspended upon the same principle, until, by a succession of these supplies, the height of the column above the level of the surrounding fluid, gives it an addi- tional weight, suflicient to counteract that which is trans- ferred to the sides of the aperture. When, instead of a capillary tube, the fluid occupies a vessel of considerable dimensions, the same adhesion to the sides takes place ; but from the length of the lines they fall in the centre by the force of gravitation, and only ex- hibit the eff*ect of lateral suspension near their termina- tions ; where it is rendered evident, by causing the fluid which is thus connected with the sides of the vessel, to rise above the general level. If the capillary aperture be formed by two parallel plates, placed at a little distance from each other, the experiment will include both cases ; the lines suspended by the plates will be crossed by lines running in a transverse direction to the sides of the vessel which contains the fluid, and as the weight of the latter must be supported by the former, the rise will be only half what it would be in a tube with a square or circular aperture equal to the distance between the plates. Light bodies floating upon any liquid which is disposed to adhere to them in this manner, are drawn together by the lines of particles which are formed between them, upon the same principle that the opposite poles of two magnets are drawn together : this is efiected, not by their direct attraction, which is extremely small, but through the me- dium of intermediate bodies brought into a magnetic state by their inductive influence, the particles of which, when in a gaseous or fluid state, are displaced by their greater attraction for the magnets than for each other. The principles here developed are of great importance in the economy of nature ; but as the operations to which we more particularly allude, include the decomposition of fluids by electrical currents, a subject not now before us, their consideration will be deferred to some other opportunity. It will be observed, that in this theory oxygen is con- sidered positive, and hydrogen negative, and of course, all other bodies which are separated at the zinc surface are 352 Mr, G. Docld on included in the former class, and all which, are separated at the copper surface in the latter class. If we refer to the figure, and suppose the atoms of oxygen to be plates of zinc, and the atoms of hydrogen plates of copper, and that the former are united to the latter in the usual manner, so as to form a galvanic series of three alter- nations of the metals ; it is evident, that the zinc will pre- sent a negative, and the copper a positive surface in the cells between the plates B and C, and between D and E ; and also, that when a conducting communication is made between A and F, the light will flow from the negative surface of the zinc plate A, to the positive surface of the copper plate F. It therefore appears, that although zinc is positive and copper negative, when water is decomposed by the galvanic action of these metals, its oxygen is evolved at a negative, and its hydrogen at a positive surface. This arrangement derives considerable support, from its agreement with the refractive force of the different bodies which are thus placed in the positive and negative classes ; the former being known to repel, and the latter to attract the light, when it falls obliquely upon their several surfaces. It may be supposed that the subjects of this paper are not sufficiently prominent to become distinct objects of investigation ; but it is by attention to minute particulars that we arrive at general conclusions ; and to prove the soundness of such conclusions, we are frequently called upon to retrace our steps, by producing particular cases to which they are applicable ; the magnitude of the subjects, under these circumstances, is not measured by our usual views of their importance, so much as by the ease and simplicity with which the theory applies to their explana- tion, and the opportunities they offer for its general illus- tration. P. Cooper. Weston Super Mare, Oct. 6, 1836. To the Editor of the Records of General Science. Article VII. On Internal Prismatic Reflexion, By Mr. George Dodd. {To the Editor of the Records of General Science.) Sir, — The ingenious and interesting papers of your corre- spondent, Mr. Cooper, on the nature of white light, contain Mr. G. Dodd on 353 many views and suggestions which merit careful considera- tion, inasmuch as they clash in many points with opinions which have received the stamp of age, and the support of great names. This opposition to received opinions, so far from being viewed with distrust, ought to obtain for the writer a larger share of attention, as, in science, it is almost always neces- sary, before we can make real additions to our knowledge, to eradicate some previous notions, either ill formed or incomplete. The principles endeavoured to be established by Mr. Cooper, appear to be these : — 1. That White Light consists of three colours , Red, Green, and Violet. 2. That there are but three indices of refraction in any given substance, viz., one for each colour. 3. That the two preceding principles are sufficient to explain the phenomena of diffraction. 4. That, supposing the 2nd proposition to be correct, the dark intervals which would necessarily residt in the prismatic spectrum, may probably be filled up by multiplied reflexion within the body of the prism. It is not my intention, at present, to offer any remarks on the general nature of the experiments contained in Mr. Cooper's papers, nor upon the evidence which he adduces in support of the three first propositions ; I will merely confine my attention to the 4th, with a view to draw Mr. Cooper's notice to a few circumstances, which seem to militate against the correctness of his deduction. The extent to which multiplied reflexion can be carried in the body of a prism, without exhausting the luminosity of the ray, appears never to have been made the subject of experiment ; but I will endeavour to show, that be that extent great or small, it can never produce the effect sur- mised by Mr. Cooper. In order the more clearly to shew this, I will at once assume, for the sake of argument, that the two first pro- positions are true : that white light consists of red, green, and violet, and that each colour has but one index of re- fraction : I will then detail reasons for believing that the VOL. IV. 2 A 364 Mr. G. Dodd on multiplo-reflected rays could not fill up the dark spaces which would result in the prismatic spectrum. In most Optical works, the relative proportions between the different coloured spaces of the spectrum are given for two or more substances : but neither the refracting angle of the prism, nor the point of the side at which the ray- enters, are stated as modifying the proportions between the colours : the spectrum may be longer or shorter according to the angle of the prism and the obliquity of the ray's passage, but the relative proportions are not altered : now, the points at which the internal multiplied reflexions take place, depend almost entirely on these three conditions : 1. The refracting angle of the prism. 2. The parallelism or obliquity of the central ray's path, with respect to the base. 3. The point of immersion, whether midway between the apex and the base, nearer to the base than to the apex, or nearer to the apex than to the base. Let us suppose the prism to be of flint glass : the spectrum is then of a certain nature, nearly, if not quite, equal in its proportions, however the prism be held : that is, any mode of using it which would lengthen or shorten one coloured portion, would do so equally to the others : but, supposing there to be three colours and three indices of refraction, the rays, after multiplied reflexion within the prism, would emerge at every imaginable position with respect to the primary rays : the violet emersions, for in- stance, might be all on their proper side of the green in one experiment, while in another, they would be largely mingled with the red on the opposite side, and this with the same prism : the difference being due to a variation of the point at which the light enters, or a variation of the angle at which the primary ray passes through. Mr. Cooper has shewn in a diagram that the effect which he attributes to internal reflexion may be produced, or at least, that all the emersions of any one colour may be parallel; but, I beWeve, he will find that that can only take place when these three conditions are observed : 1. The prism to be equilateral. 2. The point of immersion to be midway between the apex and base. Internal Prismatic Reflexion. 355 3. The central ray to pass through parallel to the base. Now, if any one of these conditions were altered in the slightest degree, the relative points of emersion would be changed, and the appearance of the spectrum altered. In order to shew this more clearly, I will trace the pro- gress of a homogeneous ray (for the sake of simplicity) through an equilateral prism, under six different circum- stances, three depending on the point of immersion, and three on the direction of its passage with respect to the As we do not know to what extent these reflexions may go, I have traced them to twenty in each experiment ; now, out of these twenty about seven will occur at the posterior fece, and, as there is an emersion at every reflexion, there are at the posterior face seven emersions, which form the sub- ject of the following table ; the object of which is to shew the difference in the direction and the intensity of the ray occasioned by the six variations of the conditions before stated. By intensity I mean priority in transmission or emersion, for the numbers in the table denote the number of reflexions which have preceded the respective emersions, and a ray must obviously retain more luminosity after two or three, than after twelve or sixteen reflexions. 1 . Impinge equidistant from apex and base. jnclined in its passage 5** towards base. ;o")inclin direct ray, & 6= 5° (.^„^„\ 3&9= 5°)i,"'=""- Inclined 5° from base. "linclin. 3, 13, 19=5° [toward 3 base. ,. , ^ . ^inclin. "^T'lfi^ =5° (from 2. Impinge nearer to apex than to base by ^th. Inclined 5° towards base. "^inclin. direct ray, 6, 16= 5° Vtoward 3 base. ■Jinclin. 3,9,13, 19 = 5°Sfrom 3 base Inclined 5** from base. "Jinclin. 3, 12, 18=5° [toward 3 base. direct ray 6) ^5o>'f;:^J;,"- ^' '^> 3 base. 2 A 2 366 Mr. G. Dodd on 3. Impinge nearer to base than to apex hy ^th. Inclined 5** from base. "Jinclin, direct ray 6 > =50 /toward 1">1'5* Jbase. Sinclin. 3,13, 19=5°Sfrom 3 base. Inclined 5° towards base. "Jinclin. 3,9, 13, 19=5° [toward 3 base. ■Jinclin. direct ray, 6, 10=5° Sfrom 3 base. Thus, it appears, that if a homogeneous ray, red for instance, were traced through a prism, the positions of the different emersions with respect to each other would be most materially altered by any variation in the point of its entry, or the direction of its passage. Having treated of a simple homogeneous ray, I will now proceed to a ray of white light, under circumstances more consonant with general experiment. Let us assume, as before, that there are but three colours, and three refractive indices : — then let the prism be equi- lateral and of flint glass, with the refractive indices of the mean, and the two extreme rays, respectively 1*620, 1*600, 1*580 (which is about a mean between Fraunhofer's table and those of other observers) : then, let a ray of white light impinge midway between the apex and the base, and at such an angle, that the central ray shall pass parallel to the base : with these data I have traced the progress of all the three rays through twenty reflexions, and fig. l.(a) repre- sents the points at 'which all the emersions would take place at the posterior face ; in fact, it would be the form of the spectrum immediately on leaving the prism. Let the white ray now impinge at a point nearer to the apex than to the base by J^th, but let the central ray still pass parallel to the base : it will now be found that the spectrum immediately on leaving the prism would be shorter than before, and not only so, but the relative disposition of the colours very different, as in fig. 1 {h). Let the case be now reversed, and the ray impinge nearer to the base m the same proportion, the parallelism being still preserved : the same process of tracing the ray through twenty reflexions would give us a spectrum as in fig. 1 (c). Internal Prismatic Reflexion. Fig. 1.* 357 («) vl9 rl6 rl3 r-10 r4 |;'4 r*l3 r'16 r-19 C^') r-4 r-13 r-16 «-19 r-10 g.4 vl3 rl6 D*4 t;-7 r'l9 v'13 wl9 wis V.7 r.l6 G R 10 r'7 r.l3 ^.4 v4 rl9 vlO V.16 I next traced all those three spectra to a distance from the prism equal to six times the breadth of its face, and fig. 2 will give an idea of the great difference which this short distance would make in the nature of the spectra. Fig. 1 {a) and fig. 2 («) are the same spectrum at two different distances, one close to the prism, and the other a few inches from it ; so likewise are fig. 1 {h) and fig. 2 (J), as are also fig. 1 (c) and fig. 2 (c) : fig. 2 is reduced to save * Fig. 1 represents tlie comparative length and chromatic distribution of the spectra immediately on leaving the prism ; v, r, g, denote the colours violet, red, green ; (the capitals V, R, G, being the primary or direct rays) ; and the numbers denote the number of reflexions which have preceded each individual emersion : ia some few points two emersions coincide. 358 Mr. G. Dodd on room, the principal object being to shew the relative con- struction of a, h, c. Fig. 2. (a) (c) . V.19 '■^v t;-19 . r-l6 t;-l3 . V.13 (6) v-r i;-19 ■ r4 . r.lO • r-10 rl6 . W.7 ■ r.l3 r . r*4 • ■ r-16 v'7 r-10 . F ■ r G r*4 . G • t,'4 , G ■ R • rl9 . K • v-10 r.7 ■ rl3 5-4 . v4 R , rl6 . t;'10 O ^.7 rl3 . r-13 t;-4 . Vie r-19 . r-19 VIO i;-18 Now, the question is, sir, are these discrepancies ever observed in practice 1 Do the mere facts of changing the point of incidence, changing the direction of passage, or varying the distance at which the spectrum is observed, make such great changes in the chromatic distribution of the spectrum ? I think not. It is generally thought desirable that the central ray shall pass parallel to the base ; but I am noi aware that in any of Newton's, Fraun- hofer's, or Brewster's experiments the mere position of the point of incidence, with respect to the apex and the base, was any matter of moment : as I am aware that parallelism to the base is generally sought for in practice, I have con- Internal Prismatic Reflexion. 369 ceded that in these six figures, but still find abundant changes in the spectra by the other means which I have detailed. I have another objection to Mr. Cooper's supposition : if in the course of twenty reflexions seven emerge from the posterior face, the others must emerge from the other two faces of the prism, and thus form faint spectra from the hori- zontal and anterior faces, as well as the principal spectrum from the posterior ; but this, neither reading nor experi- ment induce me to believe to be the case. I will again observe, sir, in conclusion, that I do not now enter into the general question, whether the indices of refraction be three or innumerable? but merely attempt to shew, that if the former be the case, the requisite filling up of the spectrum cannot be produced by multiplied reflexion within the prism, because whether those reflexions be five, twenty, or one hundred, the discrepancies which I have described would still appear. I am, sir, your obedient servant, G. DODD. 52, Myddelton Street, Clerkenwell, August 31st, 1836. Article VIII. On some Silicates of Alumina. By R. D. Thomson, M.D. To the compounds of silica and alumina great interest is attached, in consequence of the frequency of their occur- rence, the diversity of their external characters, even when closely allied by chemical composition, and their utility in manufactures. Notwithstanding the care which Berthier has bestowed on the subject, the arrangement of this class of minerals labours under great disadvantages, and it is questionable, whether our present knowledge is adequate to enable us to introduce that precision which has been applied to other bodies possessing analogy of chemical composition. I was led to the investigation of the composition of these simple compounds, from having lately met with three species of minerals, which appeared to possess distinctive external characters; and could not be referred by these features with certainty to uny described species. They were all 360 Br. R. D. Thomson on found in rocks connected with a red sand-stone, which is deposited in horizontal strata along the hanks of the Tweed, in the neighbourhood of Melrose, and appears to be re- ferable to the old red sand-stone series, or transition for- mation, being occasionally interrupted by dykes of green- stone and clay-stone porphyry. In the latter of these trap rocks, two of the minerals alluded to are found in con- siderable quantity, while the third, seems to occupy a place in the sand-stone itself. I shall describe their characters and composition, and compare them with the simple compounds of silica and alumina which have been examined. The first of these minerals, I have termed Tiiesite,^ from Tuesis the river Tweed. It occurs in veins in porphyry, or indurated sand- stone slate, which is intimately connected with the old red sand-stone. Its colour is milk white, opaque ; lustre dull ; sectile. Hardness 2*5. Specific gravity from 2*434 to 2*558. Before the blow-pipe per se, it becomes blue and brittle, fusing with carbonate of soda into an opaque bead, and with borax and salt of phosphorus into a transparent glass. It forms an excellent slate pencil. A portion of the mineral was finely pulverized and fused with carbonate of soda. The silica being separated in the usual manner, the alu- mina was precipitated by caustic ammonia in the form of beautiful white flocks, which after determining its weight, was dissolved in sulphuric acid, with the addition of potash. Regular crystals of potash — sulphate of alumina were the result of the gradual evaporation of the solution. The liquid remaining after separating the alumina was preci- pitated by oxalate of ammonia. The product was a small quantity of lime. The residual liquor was evaporated to dryness, the dry salts heated to redness, dissolved in pure water and boiled with carbonate of soda; a precipitate of magnesia ensued. This precipitate being weighed, was dissolved in dilute sulphuric acid. The whole of it dis- solved, with the exception of a minute portion of silica, scarcely appreciable, and which produced an amber coloured bead when fused by the blowpipe with carbonate of soda.f The water in one trial amounted to 13*5 per cent, in another to 13*2. * See description, Thomson's Mineralogy, vol. i. 214. t This is a peculiar state of silica well known to chemists as occurring in the latter stage of analyses, which has frequently been mistaken for Titanic acid. some Silicates of Alumina. 361 The constituents are Silica, . . . 44-300 4 atoms Alumina, . . 40-400 3 „ Lime, . . . 0-755 Magnesia, . . 0-500 Water, . . . . 13-500 2 „ 99-455 The formula, to represent its composition, which I am disposed to adopt, is 2 Al S + Al S« + 2 Aq. According to Berthier's view it would be, 2 Al S^ + Al Aq. If, however, the lime and magnesia were taken into account, and supposing them to re-place alumina, we should have, according to the formula of Professor Thomson, 3 Al S + 2 Al S2 + 3 Aq. Corresponding with this composition, we find several analyses ; especially one by Boussingault, of a Halloysite, as he terms it, from Guatequa in New Granada, found in carbonaceous schist with anthracite, of a soft consistence with a cheesy fracture, becoming transparent in water ; and two of Kaolin by M. Berthier. Halloysite from Kaolin. Guatequa.* St. Yriex.f Schneeberg.t Silica, . . . 45 46-8 43-6 = 4 atoms Alumina, . . 40-2 37-3 37-7 3 „ Potash, . . . 2-5 Peroxide of iron, 1-5 Water, . . . 14-8 13- 12-6 2 „ 100-0 99-6 95-4 It is quite obvious that these correspond with the formula which we have already given. The halloysites of Berthier differ essentially in their external character from tuesite The specimen from Anglar, near Liege, possesses a density of 1-8 to 2-00, or, according to Ingelspach Lariviere, from 1-82 to 2-09.§ Fracture compact, waxy, conchoidal, pure white or blueish, scratched by the nail, taking a polish under the finger. It is found in veins of hydrate of iron ♦ Ann. de Chim., liii. 439. t Traite des Essais par la Voie Seche par M. Berthier, i, 58. § Ann. des Mines, v. 3l0. tib. 362 Dr. R. D, Thomson on mixed with galena, carbonate of lead and calamine, which traverse a transition limestone, in masses varying from the size of the fist to that of a cubic metre. Two specimens afforded,* Anglar. Hall. Silica, . 39 39 4 atoms. Alumina, . . 34 35 3 •„ Water, . . 26 25-5 5 „ 99 99-5 Their formula is, 2 Al S + Al S2 -f 5 Aq. If then the lime and magnesia be considered foreign to the composition of tuesite, we shall have halloysite forming with it a sub-species of the same mineral, but possessing decidedly distinct characters, apparently occasioned by the addition of 3 atoms of water. And it seems necessary that the term halloysite should be restricted to those compounds, consisting of silica and alumina, in the proportion of 4 atoms to 3, with 5 atoms of water, while tuesite contains the same proportions of solids but possesses only 2 atoms of water. 2. Bisilicate of Alumina or Fuller s Earth. — This mineral is found in round masses in the bed of a stream, associated with clay-stone porphyry, near Maxton. Sp. Grav. 2*394. With nitre, soda and salt of phosphorus, fuses before the blowpipe into an opaque mass. With borax, fuses into a transparent bead, pale amber coloured when hot, colourless when cold. Colour yellowish white ; fracture earthy, soft, soiling the fingers ; scratched by the nail, tuesite and sul- phate of lime ; adheres to the tongue like halloysite ; con- tains crystals of decomposing felspar interspersed through the mass. Its constituents I ascertained to be. Silica, . . . 57-105 4 atoms. Alumina, . . 31*850 2 „ Magnesia, . . 2*615 Water, . . . 7*280 1 „ 98*850 and its formula 2 Al S^ + Aq. * Traite des Essais, i. 5B. some Silicates of Alumina, 363 Berthier has included a mineral possessing exactly the same composition, with less water, under halloysite, and another under kaolin, as is exhibited in the following table :* Halloysite. Kaolin. Fahlun. Normandy. Silica, .... • 46-8 50 2 atoms. Alumina, . . . . 26-7 28 1 „ Peroxide of iron. . 50 &5 Magnesia, . . . 0-4 •7 Lime, .... . 3-0 5-5 Water, . . . 135 9-5 1 „ Potash, . . . 2-2 95-4 101-4 Berthier considers these two specimens as affording instances of felspar in different states of decomposition, and, although he states no circumstances which tend to establish his supposition, yet it is possible his conjecture may be correct. I could observe no fact, however, which could give the slightest countenance to the idea, that Tuesite or Fuller's earth, but more especially the former, are in any way connected with felspar. 3. In the sand-stone, which has been already described, a soft whitish substance occurs. It is smooth, yielding to the finger, containing greenish streaks, and answers to the description of lithomarge or rock marrow. The specific gravity is 2*457. Its constituents are, according to my analysis, Silica, . . . 56-850 19-0 atoms Alumina, . 25-000 7-5 Potash, . . 6-178 1- Lime, . 3-492 5 Magnesia, . . 2-640 •5 Water, . . . 5-840 4- 99-900 Its composition, including the lime and magnesia with the alumina, is expressed by the formula, 8J Al S2 -f K S2 + 4 Aq. Berthier analyzed two Kaolins which approach litho- • Traite des Essais, i. 60. 364 Dr. R. D. Tliomson on marge in composition, magnesia taking the place of the potash. Kaolin from St. Tropez, 3 Al S^ 4- M S^ -f- 2 Aq. Kaolin from Mende, 4 Al S^ + M S^. For the sake of greater precision, I shall give a view of the composition of the various Halloysites and Kaolins analyzed by Berthier and Boussingault, including along with them the minerals analyzed by myself, and expressing their constitution by formulae. 1. ] . Tuesite, 2 Al S 4- Al S^ h- 2 Aq. Under this species are comprehended Halloysite from Guatequa analyzed by Boussingualt, and two Kaolins from St. Yriex and Schneeberg, examined by Berthier, and Clay of Angleur. 2. Halloysite, 2 Al S + Al S^ +5 Aq, including the Halloysites of Anglar and Hall, and, perhaps, Nontron. II. Bi-silicate of Alumina or Fuller's earth, 2 Al S^ + Aq, and Al S^ -f Aq, expressing the composition of Halloysite from Fahlun, Kaolin from Normandy, and Fuller's earth from the Tweed. Kaolin from Meissen possesses less water = 3 Al S" + 2 Aq. III. Linzinite is the name which John originally gave to the Halloysite of Hall. It may, with propriety, be applied to the ter-silicates of alumina, whose composition is denoted by Al S3 + 3i Aq. Berthier analyzed two Halloysites from St. Sever and Confoleus possessing this constitution, besides clays from Hoeganas, Forges, Montereau, Cymolite, Cologne, with less water. IV. Lithomarge, 8J Al S^ -f- K S^ + 4 Aq. Under this species, we may, perhaps, include the Kaolins from St. Tropez and Mende whose expressions have been already exhibited. In presenting the preceding arrangement, it is only my intention to assist in simplifying the study of these interest- ing compounds ; for it appears more beneficial to classify minerals, not according to theoretical views, but according to their actual nature. M. Berthier, whose analytical accuracy none will dispute, has thrown all the simple some Silicates of Alumina, 365 silicates of alumina into one class. But, it may be asked, are none of these compounds as much true species as other minerals with which we are acquainted, or, if they are different states of decomposing felspar, are they not in this respect analogous with many species, which have been pre- sumed with considerable probability, to be the products of decomposing rocks ? Article IX. On JResins, By Henry Rose.* The remarkable phenomena of isomerism are observed in much greater abundance in organic than in inorganic bodies. The laws, however, which regulate isomeric modifications among inorganic substances, can, from the small number of atoms of which they are composed, be more easily determined, than is possible with respect to organic substances, which contain a greater number of atoms; though these are probably more constant than analysis has hitherto determined them to be. It is also possible that this great number of elementary atoms may occasion many discoveries on the laws of isomerism. At all events it appears to me that the investigation of isomeric organic substances, and their relations to other bodies, belong principally to organic chemistry. In this point of view the experiments of Blanchet and Sell,t on volatile oils, are incontestibly very valuable. They found that a great number of those volatile oils, which contain no oxygen, have the same composition, and the experiments of other chemists, made at the same or a later period, have increased the number. According to Blanchet and Sell the following volatile oils are isomeric : 1st and 2nd, the two oils which compose oil of turpentine, and which they have named Dadylsmd Pencyl: 3rd and 4th, the two oils called by them Citronyl and Citryl, which form oil of lemons. To these may be added oils of turpentine and lemons themselves, unless, as is very probable, we consider them as mixtures. From the experiments of Blanchet, it appears that we must add to the above the * Translated from PoggendorfF's Annalen, xxxiii. 33, t Pogg. Ann., xxixi 133. 366 M, Henry JRose on Resins. following, 5th, the oil of the balsam of copaiva ; 6th and 7th, the two oils which compose the oil of juniper, extracted from unripe fruit;* according toEttlingt 8th, oil of cloves, and 9th oil of valerian have also the same composition, when they are separated from the acids with which they are combined. The most of these are certainly not mixtures of several substances, for they have been united with muriatic acid so as to form crystalline compounds, some of which have been often examined. The compounds which they form with oxygen have been much less frequently examined than they deserve, since they belong in part to the most common kinds of resins. Blanchet and Sell have examined colophonium, and found that it might be considered as an oxide of oil of turpentine. But when the experiments of Unverdorben and of Ries determined colophonium to be composed of two resins, one of which could be obtained in crystals, they considered that substance as a mixture of isomeric resins. Besides that which exists in colophonium, several other crystalline resins have been detected, and their investigation is peculiarly interesting, as they are pure compounds, and are not formed of a mixture of several different substances. Now, as resins appear usually to be formed by the oxida- tion of volatile oils, it appeared to me to be important to ascertain the relation in composition which exists between the resins obtained from isomeric oils. This investigation can be carried farther than that of the oils themselves, because the most of the resins formed from oils, as Unver- dorben has long ago shown, behave as acids, and are capable of forming saline compounds with inorganic bases. I have examined a few crystalline resins of both these kinds, and though they might undoubtedly have been increased, I have here communicated my results. RESINS WHICH HAVE THE PROPERTIES OF ACIDS. Resin from Balsam of Copaiva. No resin can be obtained in such beautiful crystals as this. Schweitzer first gave a method of obtaining it in the * Ann. der Pharmacie, vii. 154. Pogg. Ann. xxxi. 526. t Ann. der Pharmacie, ix. 68. Pogg. Ann., xxxi. 526. M» Henry Rose on Resins. 367 crystalline state, and he at first believed that it was a com- bination of copaiva with ammonia,* but he afterwards found that the ammonia was only formed during the pro- cess, and that crystallization from alcohol alone was required to obtain the resin in a state of purity .f The crystals are combinations of two oblique 4-sides vertical prisms. Parallel to one of the faces, there are traces of cleavage, which, however, are difficult to detect from the extreme softness of the crystals. These are pure white, the smaller transparent, the larger translucent, or only so, at the edges ; they are all very soft. This crystalline resin is more soluble in strong boiling alcohol than in cold. The spirituous solution reddens litmus paper. This resin combines with inorganic bases, and the compounds which it forms have all the properties of salts. 0*509 grammes of crystallized resin were put into Leibig's apparatus with oxide of copper. They yielded 0*464 grms. of water and 1*459 of carbonic acid. Hence, their com- position is the following : Carbon, ..... 79*26 Hydrogen, . . . . 10*15 Oxygen, 10*59 This composition agrees with that which Blanchet and Sell have found for common resin, which, according to them contains 79*65 carbon, 10*08 hydrogen, and 1027 oxygen. Colophonium is an oxide of oil of turpentine. Now, since the composition of this last agrees, according to Blanchet, with that of volatile oil of copaiva, we must also consider resin of copaiva as an oxide of this oil. We see also, that isomeric bodies, when oxidized, yield isomeric oxides. The composition of copaiva resin as well as that of colo- phonium may be expressed by the formula, 10 C + 16 H + O ;.}: calculating from this, its constituents would stand thus, carbon 79*275, hydrogen 10*355, oxygen 10*37. If we mix a solution of copaiva resin in alcohol with ammonia, there appears, as is usual with all solutions of the acid resins, no precipitate. If the resin be thrown * Pogg. Ann., xvii. 487. t lb., xxi. 172. t Rose considers the atom of hydrogen one-sixteenth of that of oxyg«n. — Edit. 368 M, Henry Rose on Resins. down from the solution by means of water, the precipitate is easily dissolved by the addition of ammonia. A solution of potash in alcohol produces no change in the alcoholic solution of the resin. In like manner, the alcoholic solu- tion of the resin may he mixed in any proportion, with a concentrated aqueous solution of potash without any pre- cipitation ; but, if water be added to the solution, then the combination of the resin with the potash separates from the excess of potash. An alcoholic solution of resin is not precipitated by solu- tion of nitrate of silver in alcohol. But if some ammonia be added, a combination of the resin and oxide of silver falls down, which is easily soluble in an excess of ammonia. The solution of the resin behaves itself towards a solution of oxide of silver exactly as an acid, which forms with it a difficult soluble or insoluble compound, but soluble in free acid, and in free ammonia. The precipitate is crystal- line, and retains its shape after drying. It is not absolutely insoluble in alcohol, though it is very slightly soluble in that liquid. By the action of light it is blackened like the other salts of silver. At a moderate heat, it melts like a resin ; at a higher, it is decomposed, and leaves after the combustion of the cinder metallic silver. In three experiments, I obtained from quantities, which were prepared at different times, by combustion, the follow- ing quantities of silver. I. 0*308 grammes of the compound gave 0*081 grms. silver II. 0*321 0*082 111.0*376 0096 Hence, the composition per cent, was as follows : I. II. III. Oxide of silver, . . 28*25 27*41 27-40 Resin, 71*75 72*59 72*60 100*00 100*00 100*00 ^ If the resin combines, without decomposition, with the oxide of silver, tl;pn it contains in this compound four times as much oxygen as the oxide of silver, for, in the above table, the mean proportion of oxygen contained by the oxide of silver is 1*9, and by the resin 7*5. A com- pound of the resin and oxide of silver, in which the oxygen M, Henry Rose on Resins* 369 in the one and other are as 4 : 1, would have the following composition per cent. 28-42 oxide of silver, 71-58 resin. This agrees with the result of the first analysis; in the others a quantity of resin was probably precipitated along with the compound.''^ 0-3575 grammes of the compound of the resin with oxide of silver, from the portion which was used in the third analysis, and which contained 0*2575 grm. of resin, gave, when burnt with oxide of copper, 0*243 grm. of water, and 0-757 grm. of carbonic acid, proving the existence of 10*40 per cent, of hydrogen, and 80*65 per cent, of carbon. It follows from this experiment, that the resin combines with the oxide of silver without decomposition. A solution of acetate of lead in alcohol produces im- mediately, in the alcohol solution of copaiva resin, a copious precipitate of a compound of the resin with oxide of lead. The precipitate is less crystalline than when the case is oxide of silver. When dried and heated, it melts like a resin. It may be analyzed, by cautiously burning it in the open air, after which, a mixture of lead and oxide of lead remains ; the last of which may be dissolved out by dilute acetic acid. In two experiments, there were obtained, I. From 0*455 grm. of the compound 0*074 oxide of lead & 0*048 lead II. 0*5755 00415 0108 Hence, its constitutents are, I. II. Oxide of lead, . . 27*63 27-42 Resin, 72-37 72-58 100-00 100*00 ' * The mean of the composition of the compound of resin and oxide of silver given in the text makes the atomic weight of the resin amount to 38-5 ; but, for the reasons assigned in tlie text, the true atomic weight is probably only 38. Comparing this atomic weight with the composition of the resin, as determined by M. Rose, it is obvious that the true constituents of the resin are, 40 atoms carbon = 30 32 atoms hydrogen ^ 4 4 atoms oxygen ^^ '4 38 = atomic weight of the resin. — EniT. VOL. IV. 2 B 370 M. Henry Rose on Resins. In this compound, also, there are four times as much oxygen in the acid as in the base. A compound of copaiva resin and oxide of lead, in which the proportions of oxygen are as 4 : 1, would be composed of 26-56 oxide of lead, and 73-44 resin. The quantity of resin, in the portions of the compound which were examined, is rather less than it ought to be from this calculation, because a small quantity of carbonate of lead easily falls down from the alcoholic solution of the acetate, unless atmospheric air be entirely excluded. The alcoholic solution of copaiva resin gives no precipitate with a solution of chloride of calcium in alcohol. But, if the solution be diluted with water, a white precipitate separates, which cannot consist of pure resin, because it is insoluble in alcohol. The lime which this precipitate con- tains can be separated by long continued washing. But a more permanent compound of this resin and lime can be obtained by adding ammonia to a mixture of the alcoholic solution of copaiva resin with an excess of the alcoholic solution of chloride of calcium, and allowing to precipitate, which appears to fall down in a corked vessel, so as to pre- vent its being mixed with carbonate of lime. It must afterwards be filtered in such a manner as to prevent the access of air, and washed with water as long as it does not act upon lime. 0*4195 grms. of this precipitate were cautiously ignited; the residue, when treated in the usual way, with a solution of carbonate of ammonia, weighed 0-0§2 grammes, and was carbonate of lime. Hence, the compound of the resin with lime contains per cent. Lime, .... 8-32 Resin, .... 91-68 100-00 This compound agrees with the former analogy, the oxygen in the base is one fourth of that in the resin. Such a compound of copaiva resin and lime would contain per cent. 8-45 lime, and 91-55 copaiva resin. Now, since the three described and examined combina- tions of copaiva resin with oxide of silver, oxide of lead, The Art of Dyeing. 371 and lime are analos^ous in composition, although they were prepared in quite different ways, this resin would appear to form only one set of saliform compounds with hases, and in this set the oxygen in the resin is four times as great as that in the base. It appears to follow from this, that the atomic weight of the resin is four times as great as it is made by the formula given above. The right formula, for the composition of the resin, is, therefore, not 10 C -f- 16 H + O, but 40 C + 64 H + 4 O. It appears to me to be con- venient, and, probably, also correct, to express the last formula as follows, 4 (10 C + 16 H) + 4 O. ( To he continued.) Article X. The Art of Dyeing. {Continued from page 208.) This mode of mordanting is very suitable for the pro- duction of a saturated logwood blue, which is more per- manent than logwood violet ; as logwood colours contain- ing copper are far more permanent than those containing simple alum mordants. BROWN AND BLUE FROM ALUM MORDANTS, AND COPPER MOR- DANTS, WITH WILLOW BARK AND LOGWOOD. 1. Brown from Alum and Copper Mordants and Willow Bark. — The process of mordanting cotton for willow bark brown has been already given. The colour is darker in proportion to the length of time that the calico remains in the copper mordant. The bark of the basket,^ or also the crack -f- willow should be first boiled in a little water; then the proper quantity is added, and the dyeing performed without allowing the solution to boil completely. By boiling with soap-suds the dye loses its powdery appearance, and becomes still darker. PROPERTIES OF WILLOW-BROWN. Light and air, as well as washing with soap, produce no considerable change upon this colour. * Salix viminalis. — Edit. t Salix/?-agi7is. — Edit. 2 B 2 372 The Art of Dyeing, Solution of i^otash forms a yellowish spot. If the whole piece is immersed in a weak solution of potash the shade becomes light. Lime water has no action. Ammonia renders the colour brown. Vinegar produces spots of a light brown colour. Lime juice forms light brown spots which ammonia does not completely remove. Both tin mordants discharge a light brown. Solution of chloride of lime, when printed on it, has no action. It produces a scarcely perceptible brown shade. Remark, — In the use of this dye, a gummy matter is formed in the solution, by which it will be weakened. It is necessary, therefore, to employ an excess of willow bark. With birch bark a similar colour is obtained possessing analogous properties. 2. BLUE FROM ALUM AND COPPER MORDANT WITH LOGWOOD. The method of mordanting for logwood blue has been already given. The blue is darker in proportion to the length of time that the mordanted calico remains in the copper mordant. An excess in dyeing is proper for giving a clear colour. A greater proportion of bran is also useful. The following proportions may be used : — 12 lbs. mordanted calico, 3 lbs. logwood, and 30 lbs. bran. The dyeing solution, which, after the dyeing, still con- tains much colouring matter, may be again employed for the production of the same colour, while yet logwood and bran are added. The dyeing should be operated slowly, and the tempera- ture of the solution should not exceed 167°. If it is raised to a boiling heat a violet hue is produced. When 32 lbs. of cloth are boiled with 1 lb. soap in 2000 lbs. water the dye takes up soap and becomes darker, and the solution of soap becomes only slightly reddish. If the proportion of soap is increased, it acts upon the dye, and the calico becomes paler as with 4 lbs. soap to 32 lbs. cloth. PROPERTIES OF LOGWOOD BLUE, This colour is, as formerly stated, pretty permanent to light and air in consequence of its containing copper. EmploymeTit of Copper Mordant after Dyeing. 373 When boiled with soap-suds (1 soap and 200 water) for a quarter of an hour, the violet blue colour of the dye is converted into a greenish blue. This withstands for a long time soap-suds. Solution of potash makes green spots, which after being treated with vinegar remain white. Lime water has no action. Ammonia, diluted with water, forms a purer blue. Lime juice produces orange-yellow spots, which vinegar only so far removes as to make the places approach nearer to a light blue. Tin mordant. No. 1, discharges a purple. Tin mordant. No. 2, acts in the same way, only the colour is less clear. Solution of chloride of lime (1 to 40 water) has no action. EMPLOYMENT OF COPPER MORDANT AFTER DYEING. As the ammoniuret of copper combines with the mor- danted calico, in the same way it combines with the dyed cloth, and in this respect affords an unlimited field to the dyer for varying his shades. No shade is produced which is not altered by immersion in the copper mordant, No. 2. Copper mordants having alumina grounds, act quite differently upon logwood colours. They change the log- wood violet blue to a disagreeable colour ; while the blue after some time acquires a gray hue. Compounds also of alumina, with substances containing tan, as the brown from birch, alder, maple, oak and willow barks, undergo various changes by the use of copper mordant. Madder-red imparts to the copper mordant a purple colour, which is equal to that produced by the addition of logwood ; being, however, much more permanent. Berry yellow is not much altered. It remains yellow but loses all lustre. Quercitron yellow assumes a greenish hue. Tan yellow produced with acetate of alumina mordant, as well as yellow wood yellow becomes brownish yellow. On the contrary, fernambuc red acquires a scarlet colour, which is more durable than the pure red. To what has been already stated, it may be added, that the colours cleared or shaded by ammoniuret of copper, 374 The Art of Dyeing. are not destitute of lustre, and earthy as is frequently the case when it is employed as a mordant before dyeing. They retain their lustre much more ; but no pulverulent oxide of copper collects on the surface. Therefore, the copper mordant, No. 2, requires no mor- dant to be added to it. The copper mordant exhibits here also remarkable pro- perty. It makes the colours light and prove permanent to soap. The logwood blue formed with copper mordant, No. 2, remains after 60 hours exposure to the sun at Berlin, in June, completely blue, while the violet blue at the same time changes to a dirty brown red. The mode of using the copper mordant is here the same as above described, except that in order to render it per- manent the cloth should be well moistened before it is placed in the mordant, otherwise spots will be formed. ACTION OF SALTS OF TIN UPON CALICO IMPREGNATED WITH ALUM MORDANT. If calico impregnated with acetate of alumina mordant. No. 1, and well rinsed, be passed through a solution of 1 part salt of tin in 200 water, allowing it to remain as short a time as possible, and washing it afterwards in water, we obtain, after dyeing 9 parts cloth with 12 madder and 36 bran, the usual madder-red of such a lustre as cannot be obtained in any other way. But the dye only succeeds on a small scale. It is an important point that the calico shall remain for as short a period as possible in contact with the salt of tin. If it remains longer, the acid of the salt of tin dissolves the alumina, and the madder-red will be much deteriorated. This cannot be avoided on a large scale. Diluting the solution of tin with water does not remedy this defect, as it is accompanied with the precipitation of oxide of tin, and consequently with an acidification of the solution. Alkaline solutions of tin do not succeed better. A solution of salt of tin in caustic lye is not at all practi- cable, as it dissolv.es the alumina, and takes it away so completely from the calico that on dyeing with madder a madder- red is not produced, but only an indistinct pink. The solution of salt of tin in ammonia does not act upon the alumina of the calico, but it has no advantageous action Action of Iron Mordant upon Copper Mordant. 376 upon the madder- red, as some oxide of tin precipitates from the milky solution upon the calico fibre and injures the lustre of the red. ACTION OF THE ALUM MORDANT UPON THE IRON MORDANT. The action of calico impregnated with acetate of alumina is not less remarkable than that of the copper mordant. Let the mordanted calico which has been hung up several days and well washed, be placed in a solution of 10 lbs. iron alum in 1200 lbs. water, and remain there for a quarter of an hour, it acquires a dark rust yellow colour, while a piece of unmordanted calico, treated in the same way, becomes only slightly yellow. As the sulphuric acid of the iron alum is in a state to dissolve the alumina of the calico, it is rather remarkable that this does not occur in the present instance. The alumina rather forms with the oxide of iron, a double combination on the calico. This more especially takes place when a solution of iron alum several months old is employed, as by the precipitation of much oxide of iron it has become acid. Since the iron alum solutionis colourless, it is interesting when two pieces of calico are placed in the solution, to observe the one impregnated in the alumina becoming gradually dark rust yellow, while the other (an unmordanted piece of calico) remains quite white. Numerous experiments have already proved the affinity existing between the earths and oxides, but it is impossible to shew it more clearly by experiment than as in the present instance by means of calico. This affinity of alumina for oxide of iron explains the utility of previously boiling the cotton with alum, when for the purpose of dyeing it with prussiate of potash it is impregnated with iron salts. It is convenient for the dyer to employ alum mordants mixed in different proportions with iron mordants. ACTION OF IRON MORDANT UPON COPPER MORDANT. A piece of cotton impregnated with iron mordant. No. 2, and well rinsed, alters by being placed in copper mordant, No. 2, only a little while ; it loses the deep yellow lustre of the rust colour and appears paler yellow. ( To be continued. J 37(j Scientijlc lulellii/ence, ^'c. Article XI. ANALYSES OF BOOKS. The Botanist ; containing accurately coloured Figures of tender and, hardy Ornamental Plants, with Descriptions. Conducted by B. Maund, F. L. S., assisted by Professor Henslow, 4to., to be continued Monthly, No. I. As it is the province of this journal to take cognizance of every thing tending to promote science, we hold such a work as the above-named to come legitimately within the sphere of our notice. An occasion for commencing a new publication of this kind presented itself at the present time, as a blank in the illustrative series of botanical works, had been created by the cessation of the Messrs. Loddiges' Botanical Cabinet — a blank which seems likely to be ably filled up by this its successor, for we perceive, that these gentlemen, with their cha- racteristic liberality, and zeal to forward science, have thrown open their splendid collection to the conductors of " The Botanist :" so that the beauties of that sanctuary, by being reflected in the faithful mirror of these plates, will give pleasure to thousands to whom the originals are unapproachable. Many other proprietors, both of public and private collections, and cultivators of plants appear to have given extensive facilities for the selection of subjects, to the artists engaged in it. The skill and ability of these seem to render vain and nugatory the lamentation of the poet ; that nothing can give back the hour of splendour in the grass, of glory in the flower ; for the pencil of the artist can give permanence to the former, and endurance to the colours of the most delicate and transient of the off"- spring of Flora. Nor is this all, the productions of every region of the earth are here brought together, and made to ornament our drawing-rooms and libraries, and in a state too, in which, unlike the originals, they require little space, and no care. Such a manual, cannot but be acceptable to many already engaged in the study or cultivation of plants ; while, for those who have yet to begin these interesting pursuits, let them take this as their com- panion, and as soon as they enter upon the domain of the goddess of flowers, they will see numerous vistas open up, and extend before them " In long; perspective of delight." If the succeeding numbers of this work equal the first, in the selec- tion and treatment of the subjects, and interesting nature of the infor- mation in the descriptive part, we cannot doubt its utility or success. Article XIL scie^^tific intelligence. 1. — British Association for the Advancement of Science. Section C. — geology and geography. Prcsidcnty Rev. Dr. Buckland. — Vice-Presidents, R. Griflitli, Esq., G. B. Greenough, Esq., {For Geograjyhy) R. J. Murchison, British Association. 377 Esq. — Secretaries, W. Sanders, Esq., S. Stutchbury, Esq., T. J. Torrie, Esq., (^For Geofjraj)htj)F. Harrison, Rankin, Esq. — Com- 7nittee, H. T. De la Beche, Esq., M. Van Breda, — Came, Esq., Penzance, Edward Charlesworth, Esq., Major Gierke, Lord Cole, Rev. William Conybeare, Rev. William Hopkins, Robert Hutton, Esq., Boscowen Ibbotson, Esq., Rev. T. T. Lewis, James Macadam, Esq., Sir George Mackenzie, M. Van der Melen, Lord North- ampton, Professor Parigot, Professor Phillips, Professor Sedgwick, William Smith, Esq., John Taylor, Esq., Dr. William West, Samuel Worsley, Esq., Rev. James Yates. Monday/, 227id Aug^ist. — 1. The first paper at this Section was read by Edward Charlesworth, Esq., entitled " A Notice of the Vertibrated Animals in the Crags of Norfolk and Suffolk." The author's principal object in bringing forward this subject, was to establish the fact, of the remains of mammiferous animals being associated with the mollusca of the tertiary beds above the London clay, in the Eastern Counties of England. These remains are con- fined to a part of the Crag formation, which appears to extend from Cromer in Norfolk, to within a few miles of Albro', in Suffolk. The bones of fish, and a large proportion of the testacea, that are met with in this stratum, differ widely from those in the coralline beds, and from that part of the clay deposit which skirts the southern coast of Essex and Suffolk. Among the mammalia, which the author stated really to belong to the Crag, is the Mastodon angus^ tidens, of which several teeth have recently been obtained in^Norfolk, from localities adjoining the parish of Withingham, the spot in which Dr. W. Smith states the specimen to have been found, which is figured in his " Strata identified." The author next noticed the discovery of the mineralized remains of birds, which he had obtained from several Crags in the same district. Among the fish, the most remarkable is the Charcarias Megalodon, the teeth of which are found in Suffolk, equalling in size the speci- mens brought from the tertiary formations of Malta. No traces of the existence of Reptilia have yet been detected in the clay, which would rather support the opinion, that the climate during the Crag epoch was analogous to that of the Polar regions. It appeared to him, that the whole town of Cromer stood on a chalk pebble. He hesitated to name the circumstance to any geolo- gist, but some time afterwards he submitted it to Dr. Buckland, who confirmed his view of it. He should be glad to know if any gentleman had paid attention to the subject ; and should any one visit Norfolk, it would be desirable to ascertain if there was any con- nexion between the town of Cromer and the stratum, or whether it stands on a detached mass. Mr. Murchison, said he had come to a different conclusion, as to the great pebble on which the town was supposed to stand. In LyelT's book there are two little sections of that district, by which it is clearly made out, that the chalk rises up from the stratum in immense masses. In conclusion, he begged to compliment Mr. Charlesworth on his interesting paper. 378 Scientific Intelligence, 6fc. 2. Cefn Caves. — Mr. Bowman described the Cefn Caves in Denbighshire. They are situated in limestone. Their roofs are covered with stalactites, and their floors with animal matter, princi- pally the elytra of beetles, bones, and teeth. Tuesday y ^rd August. — On the Classificatio7i of the old Slate Hock of Devomhire, with an explanation of the true position of the Culm Deposits of the central portion of that County, by Professor Sedgwick, and R. J. Murchison, Esq., V. P. R. S., &c. Mr. Murchison began by observing, that he was about to submit a mere outline of a more detailed memoir on the physical structure of Devonshire, which, in conjunction with Mr. Sedgwick, he pur- posed to lay before the Geological Society of London. One object they had in view was, to remedy the defects in existing geological maps, as to colouring sub-divisions of formations ; and another, to ascertain by actual sections, the true position of successive deposits, and their natural sub-divisions, so as to bring them into comparison with other con*esponding deposits, and to determine their true place in the succession of British formations. By help of a section, the following succession of deposits in the ascending order was deter- mined : — 1. A system of slaty rocks, containing a vast abundance of organic remains, generally in the form of casts ; these rocks sometimes pass into a fine glossy clay slate, with a true transverse cleavage — some- times into a hard quartzose flag-stone, not unusually of a reddish tinge, sometimes into reddish sand- stone, subordinate to which are bands of incoherent shale. In North Devon, they are very seldom so calcareous as to be burnt for lime, but in South Devon, rocks of the same age appear to be much more calcareous. This series is finely exposed in the Valley of Rocks, and the Valley of the Lyn, but its base is no where visible in this line of section. 2. A series of rocks, characterized by great masses of a hard thick- bedded red sand-stone and red flag-stone, subordinate to which are bands of red, purple, and variegated shales ; the red colour occa- sionally disappears, and the formation puts on the ordinary appear- ance of a coarse silicious gray wacke, subordinate to which are some bands of slate, but too imperfect to be used for roofing. This system contains very fine organic remains ; it is several thousand feet in thickness, occupying the whole coast from the west end of the Valley of Rocks in Combmartin, being thrown back by a dip into the cliffs between Porlock Bay and Linton ; it re-appears in North Hill and the Quantock Hills. 3. The calcareous slates of Combmartin and Ilfracombe, of very great aggregate thickness, abounding in organic remains, and con- taining in a part of its range, at least, nine distinct ribs of lime- stone, burnt for use. This lime-stone is prolonged into Somerset- shire, and is apparently the equivalent of the lime-stone on the flank of the Quantock Hills. 4. A formation of lead-coloured roofing slate of great thickness, and occupying a well-defined zone in North Devon, its up])cr bed alternating with, and gradually passing into a great deposit of green, gray and purple, or red sand-stone, and silicious flag-stone. These British Association. 37^ silicious masses alternate with slates, and are in some places sur- mounted by great masses of red unctuous shale, which, when in a more solid form, generally exhibit a cleavage oblique to the stratification. 5. The Silurian System, resting conformably on the preceding, of great thickness, on the western coast of North Devon, occupying a zone several miles wide, and containing many subordinate beds and masses of lime-stone. In its range towards the eastern part of the county, it gradually thins off, but its characters are well preserved, and throughout it contains an incredible number of characteristic organic remains. 6. The carbonaceous system of Devonshire. This system is very greatly expanded, stretching in a direction east and west across the county, occupying the whole coast from the neiglibourhood of Barn- staple to St. Gennis, in Cornwall, and on its southern boundary ranging so close to Dartmoor, that its lower beds have been tilted up and mineralized by the action of the granite. This great formation, is, therefore, deposited in a trough, the northern border of which rests partly in a conformable position upon the Silurian system, and partly upon older rocks, partly of the division, No. 4. Its southern border rests on the slate rocks of Cornwall and Launceston, and on the north flank of Dartmoor. From one side to the other, it exhi- bits an extraordinary succession of violent contortions, but its true place in the ascending section, admits of no doubt whatever. In some places, it is overlaid by patches of green sand, and in one part of the coast, west of Bideford, it is overlaid by the conglomerates of the new red sand-stone, which are seen for half a mile resting un- conformably on its edge. The lowest portion of this vast deposit is generally thin-bedded, sometimes composed of sand-stone and slate, with impressions of plants— sometimes of indurated compact slate, both in an earthy and crystalline state. These beds are surmounted by alternations of shale and dark-coloured lime-stone, with a few fossils. Subordinate to these beds, there are on the west side of the county many thin veins and flakes of culm and anthracite. On the eastern side of the county the coal is wanting, and the cal- careous beds are much more expanded. On the south side of the great trough, the calcareous bands and dark shales are well exhibited, but near Oakham j)ton are, as above stated, mineralized by the action of the granite. The higher beds of this deposit are well exhibited on the coast west of Bideford, and consist of innumerable alternations of ferruginous sand-stone, flag-stone, and shale, containing in several places concretions of iron-stone, very often exhibiting impressions of plants ; and one extended tract of country, containing at least three beds of culm or stone coal, associated with shales, contains many plants of species not known in the true coal measures. Though in a state of greater induration than the ordinary coal measures of ling- land, and in most })arts almost destitute of any trace of coal, yet even in these respects, it differs not from a great unproductive tract of the coal-field of Pembrokeshire. Wednesdai/ , 24th AuyKst. — Mr. Stutchbury read a paper on some newly discovered Saurian remains, from the muguesian oonglo- 380 Scientific Intelligence, Sfc. merate of Durdham clown. They were found in the magnesian conglomerate which rests upon the lime-stone, and must have been deposited upon the spot upon which they were found, without vio- lent action ; they are often injected with rocky paste. The struc- ture of their vertebrae resembles strongly that of the crocodile. Mr, Hopkins submitted his views on the phenomena of eleva- tion. In reference to the mineral veins of Derbyshire, he had ascertained, that the direction of the axis of dislocation which had caused the fissure was true north and south, while that of the structure of the rocks was inagnetic north and south ; hence, shewing the connexion between magnetism and the theory of mineral veins. Thursday, 26th August. — The Ancient City of Memphis. — The Marquis Spinetto read a paper, entitled *' a report of the attempts made to ascertain the latitude of the ancient city of Memphis." The details of this communication are of importance to geographers, as tending to elucidate a point on which Pocock, Shaw, Bruce, and other travellers, have differed. The question may now be considered to be set at rest, it having been clearly ascertained that it was in the present bed of the Nile, in latitude 29° 46' North, and longitude 31° 30 East from Greenwich. The Chairman congratulated the Section on having heard these satisfactory details, and observed that the same process which had buried the ancient city of Memphis in the bed of the Nile — an accu- mulation of mud and drifted Lybian sands, in consequence of the demo- lition of the dykes, which once turned aside the water — had already sunk the beautiful fossil beds of Purton beneath the Severn. Dr. Buckland stated that he had received engravings, prepared under the direction of M. Agassiz, of some of the splendid fossils in the Bristol Institution : and he also placed upon the table a copy of his own work on Geology, forming one of the Bridgewater Treatises. The next paper was on the Change in the Chemical Character of Minerals Induced hy Galvanism. — Mr. Fox mentioned the fact, long known to miners, of metalliferous veins intersecting different rocks containing ore in some of these rocks, and being nearly barren or entirely so in others. This circumstance suggested the idea of some definite cause ; and his experiments on the electrical magnetic condition of metalliferous veins, and also on the electric conditions of various ores to each other, seem to have supplied an answer, inasmuch, as it was thus proved that electro-magnetism was in a state of great activity under the earth's surface, and that it was independent of mere local action between the plates of copper and the ore with which they were in contact, by the occasional substitu- tion of plates of zinc for those of copper, producing no change in the direction of the voltaic currents. He also referred to other experi- ments, in which two different varieties of copper ore, with water taken from the same n>ine, as the only exciting fluid, produced con- siderable voltaic action. The various kinds of saline matter which he had detected in water taken from different mines, and also taken from parts of the same mine, seemed to indicate another probable source of electricity ; for can it now be doubted, that rocks impreg- nated with or holding in their minute lissures different kinds of British Association. 381 mineral waters, must be in different electrical conditions or relations to each other ? A general conclusion is, that in these fissures metalliferous deposits will be determined according to their relative electrical conditions ; and that the direction of those deposits must have been influenced by the direction of the magnetic meridian. Thus we find the metallic deposits in most parts of the world having a general tendency to an E. and W. or N. E. and S. W. bearing. Mr. Fox added that it was a curious fact, that on submitting the muriate of tin in solution to voltaic action, to the negative pole of the battery, and another to the positive, a portion of the tin was determined like the copper, the former in a metallic state, and the latter in that of an oxide, shewing a remarkable analogy to the relative position of tin and copper ore with respect to each other, as they are found in the mineral veins. The Chairman said it had been observed to them last evening, that the test of some of the highest truths which philosophy had brought to light was their simplicity. He held in his hand a blacking pot, which Mr. Fox had bought yesterday for a penny, a little water, clay, zinc, and copper, and by these humble means he had imitated one of the most secret and wonderful processes of nature, her mode of making metallic veins. It was with peculiar satisfaction he con- templated the valuable results of this meeting of the Association. There was also a gentleman now at his right hand, whose name he had never heard till yesterday, a man unconnected with any Society, but possessing the true spirit of a philosopher. This gentleman had actually made no less than 24 minerals and even crystalline quartz. He (Dr. B.) knew not how he had made them, but he pronounced them to be discoveries of the highest order ; they were not made with a blacking pot and clay, like Mr. Fox's, but the apparatus was equally humble ; a bucket of water and a brick-bat had sufficed to produce the wonderful effects which he would detail to them. Artificial Crystals and 3Iinerals. — Mr. Cross then came for- ward, and stated that he came to Bristol to be a listener only, and with no idea that he should be called on to address a section. He was no geologist, and but little of a mineralogist ; he had, however, devoted much of his time to electricity, and he had latterly been occupied in improvements in the voltaic power, by which he had succeeded in keeping it in full force for twelve months by water alone, rejecting acids entirely. Mr. C. then proceeded to state that he had obtained water from a finely crystallized cave at Holway, and by the action of the voltaic battery had succeeded in producing from that water, in the course of ten days, numerous rhomboidal crystals, resembling those of the cave ; in order to ascertain if light had any influence in the process, he tried it again in a dark cellar, and produced similar crystal in six days, with one-fourth of the voltaic power. He had repeated the experiments a hundred times, and always with the same results. He was fully convinced that it was possible to make even diamonds, and that at no distant period every kind of mineral would be formed by the ingenuity of man. By a variation of his experiments he had obtained gray and blue carbonate of copper, phosphate of soda, and 20 or 30 other specimens. If any 382 Scientific Intelligence, 8^c. members of the Association would favour him with a visit at his house, they would be received with hospitality, though in a wild and ' savage region on the Quantock hills, and he should be proud to repeat his experiments in their presence. Professor Sedgwick said he had discovered in Mr. Cross a friend who some years ago kindly conducted him over the Quantock hills on the way to Taunton. The residence of that gentleman was not, as he had described it, in a wild and savage region, but seated amidst the sublime and beautiful in nature. At that time he was engaged in parrying on the most gigantic experiments, attaching voltaic lines to the trees of the forest, and conducting through them streams of lighting as large as the mast of a 74-gun ship, and even turning them through his house with the dexterity of an able charioteer. Sincerely did he congratulate the Section on what they had heard and witnessed this morning. The operations of electrical phenomena, instances of which had been detailed to them, proved that the whole world, even darkness itself, was steeped in everlasting light, the first-born of heaven. However Mr. Cross may have hitherto con- cealed himself, from this time forth he must stand before the world as public property. Professor Phillips said the wonderful discoveries of Mr. Cross and Mr. Fox would open a field of science in which ages might be employed in exploring and imitating the phenomena of nature. Coal Fields of South Wales. — The Chairman then called on Mr. Conybeare to read his paper on this subject, but that gentleman said that the subject would now be so uninteresting after the splendid discoveries that had been detailed to them, that he should only point them to the map, and request them to imagine that he had read his paper, and that they had been asleep all the while. Mr. Murchison read a j)aper " On the Geological Relations of certain Calcareous Rocks near Manchester ;" after which the Section adjourned to the evening. Evening Sitting. — The River Severn. — Mr. Murchison made a communication respecting the ancient Hydrography of the River Severn, and entered into statements respecting the drifts, in the course of which he expressed an opinion that the River Severn had been thrown into a southern direction by a convulsion of nature. Friday, 2Qth August. — 1. Lord Nugent described the sea rivulets at Argostoli, in Cephalonia, referred to by Mr. Babbage at Dublin. They flowed from the sea into the land, and one of them had been employed to drive a mill. Some persons accounted for this pheno- menon, by supposing that there was a difference of level on difterent sides of the island, and that the streams flowing through a subterra- nean tunnel restored the equilibrium. Others thought that it was connected with volcanic action. Dr. Daubeny considered it a con- firmation of the first vokanic theory of Davy. 2. Mr. Charlesworth expressed some doubts with regard to the correctness of the views of Mr. Lyell, as to the proportion of recent and extinct species in tertiary strata. M. Agassiz could detect no recent species of shells or fish in the Norfolk crag. 3. Professor Forbes stated, that he had traced a remarkable con- British Association. 383 nexion between the hot springs of the Pyrenees and the geology of the district. lie had found that the granite of that country had acted upon the other rocks, in such a manner as to shew extreme cases of disturbance, and that round the lines that marked the con- nexion of these rocks with granite, these springs were uniformly found — mineral springs also abounded in the same situations. He stated, that he had examined the temperature of a spring, whose heat had been taken 100 years ago, and had found it exactly the same. Section D. — zoology and botany. President^ Professor Henslow. — Vice Presidents, Rev. F. W. Hope, Dr. I. Richardson, Professor Royle. — Secretaries, John Curtis, Esq., Professor Don, Dr. Riley, S. Rootsey, Esq. — Com-, mittee, C. Babington, Esq., Mr. R. M. Ball, J. E. Bowman, Esq., Rev. Mr. EUacombe, — Eyton, Esq., Hon. Charles Harris, Mr. Hewitson, Dr. Jacob, Mr. G. J. Jeffrys, Rev. Mr. Jenyns, I. L. Knapp, Esq., T. Mackay, Esq., Professor Nilsson, Rev. Mr. Phelps, Professor Scouler, Colonel Sykes, Richard Taylor, Esq., Professor Wilson, William Yarrell, Esq. Monday, 22nd August. — 1. North American Zoology. — Dr. Richardson read the introductory portion of his report on North American Zoology, comprising remarks on the physical geography and climate of the country. He noticed three distinct mountain chains, the principal one extending under the name of the Rocky Mountains, from the elevated plains of Mexico to the Arctic sea, rising within limits of perpetual snow, and affording on its declivities inclined zones of equal temperature, running nearly north and south. He next mentioned the comparatively low range of the Alleghanies running near the Atlantic coast, and the more broken Maritime Alps of California and New Caledonia, from which several lofty peaks arise. It was remarked that in these Maritime Alps in three ranges recent or active volcanoes exist, which it was suggested might be one of the causes of the higher temperature of that coast. The great valley lying eastward of the Rocky Mountains, and extending from the Gulph of Mexico to the Arctic sea, and watered by the Mississipi, Missouri, Saskatchawan, and the Mackenzie, was also noticed as exerting a manifest influence on the migrations of herbi- ferous quadrupeds, some tribes of birds, and fish. In the remarks on climate, the various ways in which the configuration of the land may contribute to influence the temperature of the atmosphere, were glanced at. The Arania or Mygale Avicularia. — Mr. Rootsey exhibited a living specimen of this animal, which is of the spider tribe, and made some observations on the subject. It was not uncommon to meet with them in collections, and he had been informed by Mr. C. Babington, that one of them had been found in the London Docks. The animal in question was brought in a cargo of logwood, from the bay of Campeachy, but it was not known how it had sub- sisted, for, though pieces of meat had been near it, it had not eaten it; but it was supposed to have sucked the meat. The speaker 384 Scientific Tntelligencp^ Sfc alluded to the statements made as to its poisonous qualities, it being more venomous than the serj^ent, and the extraordinary tales which were related of it; perhaps, however, tliey might be enlightened on this head by some gentleman better acquainted with the West Indies. With regard to its mode of procuring food, he stated, that it dropped from the branches of trees into the nests of birds, and preyed not only on the birds but on the eggs ; in consequence of which it derived its name. The Rev, Mr. Hcrpe stated, that it was not the true avicularia described by Spix and Martius, but that it was named after Spix. [The insect has been deposited at Mr. Miller's Nursery, Durdham Down, that it may have the advantage of stove heat.] Mangel WurzeL — Mr. Rootsey mentioned the result of various experiments he had made in extracting sugar, spirit, &c., from mangel wurzel, and converting the plant into malt, specimens of which were exhibited to the Section. The sugar was obtained in strong crystals, and the refuse of the plant was dried on a malt-kiln at a proper temperature, where it required the flavour and properties of common malt, and afforded an excellent beverage. The molasses were fermented into a spirit, the flavour of which was comparable to the peach brandy of America. Forty tons of the plant, which were sometimes raised upon an acre of land, afforded three tons of malt, and three and a half tons of molasses. Mr. Rootsey then exhibited a specimen of the Haltica nemorum, or turnip fly, which he stated was the only insect which attacked the plant. Some discussion took place as to the best means of pre- venting the ravages of the insect, and it was thought, that by steep- ing the seed the insect would be destroyed ; it was stated, that this was already done by farmers, but it was of no avail, as the eggs of the fly were not only deposited on the root, but in the hedges, and on the lands.* On the Acceleration of the Growth of Wheat. — Mr. G. W. Hall said, that the object of the present paper was to call attention to a statement of facts connected with the acceleration of the growth of wheat. The average length of time required for the growth of wheat was about ten months, but observations had led to the con- viction, that much of this time might be saved, and the result has shewn, that five months has sufficed to produce an abundant crop of wheat (a sample of which was exhibited to the Section) by adapting the plant to the soil. The lighter silicious soils, when manured, possess a warm and stimulating character, and conduce to very rapid growth of plants, but they soon became exhausted ; and it must be evident that an acceleration of the growth and ripening of the plants committed to a light soil, and a diminution of the time required for perfecting its crops, must not only be congenial to its character, but tend to economize and prolong its productive powers. These cir- cumstances had been observed and acted on with the most beneficial results in various ways. The paper then touched at length on the means to be employed in accelerating the vegetable growth, and the evils attending it, and concluded by alluding to the benefit of the • The plan wljich has been adopted in Scotland is to sow the seed very thick. — Edit. British Association. 385 existence of the Society, met together to accelerate the progress of important truths. After some discussion on this paper, Dr. Daubeny stated to the Section the result of some experiments which he had made on the eiFects of arsenic on vegetables. A friend of his, Mr. Davies Gilbert, residing in Cornwall, had stated to him, that the soil in the neighbourhood of mines, being impregnated to the amount of fifty per cent, with arsenic, had a great effect on the vegetable kingdom. He had, therefore, tried some experiments at Oxford, and he found that the plants, which were barley and beans, did not suffer till nearly one-half the soil was composed of the sulphuret of arsenic. This proves that the statement of Mr. Gilbert was correct. Mr. Stephens stated, that the fish in some trout streams in the vicinity of mines were destroyed in consequence of the water drained from the mines having been turned into them. A coachmaker of this city had informetl him that his horses had suffered very much in. consequence of grazing in a field near spelter works. Tuesday^ 2Zrd August. — Dr. Richardson read a second portion of his paper on North American Zoology, embracing the Mammalia, his observations on the species having reference generally to the similarity of the North American Zoological division to that of Europe, and its comparatively small connexion with that of South America, notwithstanding their geographical approximation. Of the order Quadrumana, of which many with prehensile tails belong to South America, none range southwards of the Isthmus of Darien, while one has located itself in the southern extremity of Europe. Of the Cheiroptera, the North American species, are analogous to those of Europe, and very distinct from those of the southern division of either the old or new world. The North American Insectivora, on the contrary, differ greatly from those of Europe, the only genus common to both sides of the Atlantic ocean being sorex, or the shrews. Of the Marsupiata, three species are found within the limits of the United States, and they may be considered as ranging so far north, for their head quarters, in the southern zoological province of the new world. The existence of this order in America connects its zoology with that of New Holland, and dis- tinguishes it from that of all other portions of the globe. To the family Carnivora, most of terrestrial quadrupeds, common to the new and old world belong, and a similar remark may be made of the birds of prey, for exclusive of the Phocse, which, like the Amphibia > and Cetacea, may be looked upon as belonging properly to the waters, the Falconidae, of all birds, have the species most widely distributed. The American Seals are, without exception, also found on the shores of either Europe or Asia. The Gnawers, or Rodentia, serve to characterize the North American zooh)gy from the great number of the species, exceeding those of any other quarter of the world, and the many peculiar forms they include. The small order Edintata, wliich forms a very characteristic and almost peculiar part of South American Zoology, is scarcely to be considered as belonging at all to North America, though three or four species cross the dividing line of the two provinces in Mexico. In former times the case was different, as the remains of very large and re- YOL .IV. 2 C 386 Scientific Intelligence, ^"c. markable animals of this order are much seen in many parts of North America, viz. — of Megatherium and the Megalonix. The order Pachydermata is remarkable at once for the size of the animals it includes, the number of extinct species, which more than double that of the living ones, and the small number that the new world now nourishes. Fossil Elephants and Mastodons have, however, been dug up in various distant parts of North America, and the bones of horses were procured by Captain Beachey under the cliffs of Kotezbue's Sound. The Ruminantia form an important and interest- ing part of North American Zoology, but only two, or at least three species are common to the new and old world. On the Longevity of Yew Trees. — Mr. Bowman read a paper on the mode of ascertaining the age of yew trees, by counting the rings and lines of the trunk, and instanced several experiments which he had made. The mean average of the number of lines which a tree increased in a year was two, or ^th. of an inch, and the result of his experiment went to prove that Decandolle was wrong in his experiments in this respect ; that he made the old trees too young and the young ones too old. With respect to the growth of yew trees in churchyards many reasons have been assigned for it, but it occurred to him that the longevity, the indigenous nature of the tree, and its being an emblem of immortality, led our forefathers to deck the place of the dead with them in lieu of cypress. This was one of the many customs which were engrafted on Christianity at its introduction, and it would be a barbarism to destroy an emblem that we might meet again hereafter. In conclusion, the paper urged on the scientific world the admonition of Decandolle, to pursue the subject by interrogating the annual rings of trees. Account of a new Species of Seal. — Mr. Ball said that when young he was in the habit of observing seals, and he had only seen two species for a considerable time, but at length he found another seal, which he believed was the true phoca vitulina. Mr. Ball then exhibited sculls of several seals, and Dr. Riley also exhibited the skeleton of one which was caught near Weston-super-Mare. Professor Nillsson described the animal exhibited by Mr. Ball, and gave it as his opinion that it was a specimen of a distinct species, forming a distinct genus from the vitulina, with which Linnaeus has confounded three. He terms it Heliochcerus griseus. Dr. Riley exhibited the stomach of the seal caught in the Severn, and stated that on preparing the skeleton of the animal he found from thirty to forty pebbles contained in it, which fact he mentioned, to point out the manner in which it is said seals catch fish. It is a prevalent opinion, that the seal when fishing attaches its legs to the bottom, and remains in a vertical position, and when a fish passes over its head it darts up anil strikes it transversely. Now, according to the depth of water, it takes in a quantity of pebbles as ballast, as it is obliged to sink itself. Dr. Riley also exhibited the venous system of the seal, by which it was enabled to dive so admirably. It col- lected a quantity of blood on the right side, the same as they found was the case with those persons employed in diving for pearls. New Species of Scandent Norantea. — Dr. Hancock exhibited a new species of this plant, which is a native of America, in form like British Association, ^ 387 a withy, frequently of the thickness of a man's body, and growing round and to the top of trees, which it frequently destroys and pulls to the ground. Hermaiphrodite Lucanus. — The Rev. Mr. Hope exhibited an Hermaphrodite Lucanus, which called forth some discussion. On Certain Notions of Antiquity derived from, the Ancients. Mr. Hope then read an interesting paper on this subject. In the course of it, he said, that from the waters of the Nile spring into life myriads of insects, and with annual fertility the Egyptians were plagued with flies. It was curious that five out of the ten plagues of Egypt were from insects, viz., the plague of the waters of the Nile being turned into blood, which might have arisen from the insects contained in it, of lice, (fpom the soil,) of froes and of fiies, probably generated from the heaps of putrid frogs. Cleanliness not being much esteemed in Egypt, flies multiplied exceedingly, which led the people to erect and worship gods, who might be able to rid them of their tormentors. It was the general opinion in ancient times, that spontaneous generation was caused by fire, earth, and water ; this opinion was prevalent so late as the 16th century, and was still held in Africa and Asia, and also by one class of naturalists in Europe. He should say thaL reasoning from analogy, there was no such thing as spontaneous generation. Mr. Hope also referred to the transmigration of souls ; the belief in this he thought originated from the changes in the animal kingdom, which he concluded by describing. Wednesday 24th August. — Fruits of the Deccan. — Colonel Sykes said, that his duty, as statistical reporter in Deccan, had led him over the whole of that country, and he had, therefore, oppor- tunities of observing, as, indeed, it was his duty to do, the products of the country, whether mineral or agricultural. The drawings which he would present to the notice of the meeting were executed with great care by a draughtsman in his service, who, having failed in that capacity in England, had enlisted in the Company's Artillery, and, on his landing in India, he fortunately was able to engage him, He w^ould also remark, that these drawings were made from actual measurement of the plant, and as they were accompanied by a scale, it was only necessary to use a pair of compasses, and the real dimen- sions of any part of a flower or plant might be ascertained. The account of the subject which he intended giving, was derived from the sacred books of the Hindoos, five of which were in his possession, and the contents were extremely curious, the language used being Sanscrit ; they were very ancient, and, in short, were a complete materia medica, and complete encyclopsedia of agriculture, &c. The Colonel then read an elaborate and complete list of the wild and cultivated plants of the Deccan, stating their form, size, use, medicinal, and other properties, &c., and illustrating them with the drawings which are before mentioned. He noticed the Golden Plantain, which is a tree of great luxuriance, and was remarkable for its bearing fruit but once, and becoming quite useless and exhausted, immediately after doing so. It had given rise to some adages among the natives, such as the 2 c 2 388 I Scientific Intelligence, 6fc. lioness litters but once, the plantain bears fruit, and a woman marries but once, (this being the custom of the country), and a brave man never retreats but once, meaning, that he loses his life in doing so. On the Geographical Distribution of Plants in lrela>id and the West of Scotland. — Mr. J. T. Mackay read a report which he had drawn up in accordance with a suggestion thrown out by a member of the British Association at its last meeting. Caoutchouc. — Mr. Royle in visiting the manufactory of the elastic web from caoutchouc or India-rubber, which is now applied to a variety of purposes, was informed there was a difficulty in obtaining, from South America, a sufficient quantity of caoutchouc, or India-rubber for the purposes of the manufacture, and was, there- fore, led to point out the variety of plants and countries from which the same substances might be obtained. A communication was first read from Mr. Sevier, the sculptor, who has made the principal dis- coveries in the properties of caoutchouc, and the commerce of caout- chouc, by which it appeared, that, since the removal of the duty, the importation of it had increased from 10 to 500 tons annually, and is soon expected to be 2000 or 3000 tons a-year, from its various uses as articles of dress, and ligatures of every kind, as well as for elastic ropes for the breaching of guns, a^d bands for driving machinery. The earliest accounts, by Condamine, Aublet, and Priestley, were alluded to, and the South American tree, yielding caoutchouc, was mentioned under the name Siphonia elastica, that of Penang as Urceola elastica, and the Indian as Ficus elastica, while other plants yield it in Madagascar, Mauritius, Singapore, and China. The natural families of plants, to which all those yielding caoutchouc belong, were stated to be Cichoracece, Loheliacew, Apocynece, Asclepiadece, Euphorbiacece, and Artocarpew, all of which have milky juice, and are in considerable quantities in tropical countries ; there could be but little doubt, that many other plants of these families might be found to contain this useful substance, as well as those which are already known to do so. Besides these general results, it was observed, that many of the plants of this family were remark- able for the tenacity of their fibre, which fitted them for the purposes of rope-making, and that it was singular, that in the attempts to find substitutes for the mulberry-leaf in feeding the silk-worm, so many of the plants, which they prefer, next to the mulberry-leaf, should belong to the families which yield caoutchouc, as the lettuce- leaf, the leaf of Ficus religiosa, the Artocarpece, and the Castor Oil Plant. Considering that these facts were not likely to be accidental, the author was led to infer, that something of the same kind must be contained in the juice of the mulberry, especially, as it belonged to the family of Artocai'pece, and, having requested Mr. Sevier to make the experiment, the author was informed, that he was perfectly correct in his indication, as the mulberry juice also contained caoutchouc, whence it was inferred, that the silk-worm requires some portion of this tenacious substance in its food to enable it to spin its silk, and the fact was communicated, as probably of some practical value, as well as of scientific interest. Mr. Hope subsequently remarked, that the dandelion, which had been previously noticed as yiehling caoutch(uic, was one of those British Association. 389 employed as a substitute for feeding the silk-worm — a striking instance of the utility of men of different pursuits meeting and dis- cussing subjects of this nature together. On the Luminosity of the Sea, — Mr. Duncan said, that he brought this subject forward more for the purpose of gleaning in- formation than giving it, with regard to this beautiful phenomenon. The communication arose from a conversation which he lately had with a physician residing at St. Leonard's, and he described the appearance which the sea presented, when illuminated by certain animalculflB, with observations. On the 28th October, the sea presented a most splendid spectacle, every wave appearing as a rolling mass of phosphorus, when the gentleman in question obtained some of the water, and 18 hours after, on being put in the least motion, it emitted phosphorescent sparks, which, however, it did not while remaining in a state of quiescence. When the water was still, innumerable disc-shaped animalculae collected on the water, like minute drops of oil, on an average to the number of 60 or 80 on each square inch of water. They become more visible in placing a piece of black silk beneath them, and then they appeared almost white, or some transparent, except at one point which was opaque, and always situated at the margin of the disc, and they differed much in size. The water was kept for six days, at the end of which, the light was still perceptible, in the dark, on agitating the water, but gradually became less brilliant. It has been supposed, that the animalculae float constantly on the surface of the water, and their presence in particular situations depends on certain winds, and cir- cumstances over which they themselves have no control. Reasoning from analogy, he supposed that their appearance did not depend altogether on fortuitous causes ; but, that, as a certain condition of the atmosphere seduces the glow-worm to venture from her obscure retreat, that so these animalculae have been taught to rise only during certain states of their element from the depths beneath. This was the substance of the communication from his friend ; but, what was singular, was that they could not observe any light from animalculae till the water had been shaken ; it, therefore, favoured the supposition, that it was necessary for them to imbibe oxygen to enable them to emit the same. Colonel Sykes said, that in tropical countries he had himself seen the animalculae, which were very minute; gelatinous masses, he stated, emit light without being agitated. Remarhs on the Cow Fish., or River Cow (^manatusjluviatilis.) By Dr. John Hancock. Mr. Rootsey read a paper describing this animal, a specimen of which was exhibited. The animal was now only found in the lakes far away from the European settlements, and the name chosen was very inappropriate. Some authors asserted that the animal frequently weighed 8000 lbs., and measured 28 feet in length, but he (Dr. Hancock) having seen many, and examined them, thought they very seldom exceeded 600 lbs. in weight, and six feet in length. The flesh of the animal is very good, very much resembling veal, very easy of digestion, and the soup made from it was delicious, and equal to turtle, though not so gelatinous ; the flesh woidd also keep 390 Scientific Intelligejice, ^"c. wholesome without salt for many months. The bones were highly esteemed by the natives, and when taken in a powder were highly beneficial in complaints of the kidneys. It was also believed to bellow like a bull, and to fight desperately on some occasions. It moved through the water with great rapidity, not, however, by moving the tail laterally, as other fish, but vertically, up and down. It had been asserted, that this animal could not live on shore; but this he doubted, as it was unable to breathe like a fish, the respirative organs being nearly the same as those of terrestrial animals, and it was, therefore, obliged to come to the surface to respire, and always slept with its nose above water, under shielding banks. Indeed, nature seemed to have placed it in an element which it was not fitted to ; it was unable both to breathe and procure food under water, and it was thought that had it legs to walk on shore it would abide there. It was also suggested, that it would be desirable to find pasturage for these animals connected with small pools of water, and thus droves of the sea cow might be found ; a case was instanced of a sea cow being kept in a small lake, in one of the West Indian Islands for 26 years, which became so tame as to be pleased with the human voice, to come when called, and to swim across the lake with children on its back without plunging beneath the surface of the water. The upper part of the body approximated to the human form, and the posterior to the fish, and when it rose out of the water to gather food from the banks, it had much the appearance of what is called the mermaid ; and, from it probably the fable of mermaids and the tritons originated; particularly as the Indians usually had painted on the sterns of the canoes a figure similar to that which the cow fish presented, when in the position described, which they styled, " the man of the waters." On the 3Iode of preserving Animal and Vegetable Substances. Dr. Macartney read an interesting paper on this subject; in the course of which he stated, that by washing insects, skins of animals, or flowers in essential oil of cloves, or, indeed, in any essential oil, they might be preserved for a great length of time without injury. The Kev. Mr. Hope read a communication from Mr. Raddon, On the MeaJis of obtaining Insects from Turpentine, and exhibited two cases, containing a vast number of very fine specimens. Mr. Hope observed, that in future it would not be necessary to proceed to America to procure insects, as it was only necessary to go to the warehouses of those merchants who imported turpentine, and by searching through it when boiling, they might very shortly obtain sufficient specimens to form fine collections at a few shillings' expense. Thursday, August 26th. — Before proceeding to business, the President announced, that the Sectional Committee had made arrangements for a "holiday on Friday, in order that the Section might proceed on either of the excursions fixed for that day. Zoology of North America. — Dr, Richardson read the conclud- ing part of his report on North American Zoology, which treated principally of birds and fishes. He also incidentally referred to a small fish which drummed at the bottom of vessels on the North American Coasts, and so loudly as to shake the vessel, and to render utterly impossible for persons unaccustomed to it, to sleep. The British Association. 391 thanks of the Section were voted to Dr. Richardson for Ins valuable report. Criteria of Species. — Mr. Carpenter read an elaborate commu- nication on this subject, founded on the views of Dr. Prichard. This called forth a discussion, in which Mr. Vigors, Mr. Carpenter, the President, and Dr. Prichard took part. Section E. — mbdical science. President, Dr. Roget. — Vice PresidentSj Dr. Bright, Dr. Macartney. — Secretaries, Dr. Symonds, G. D. Fripp, Esq. — Committee^ Dr. O'Beirne, Dr. Bernard, Dr. James Bernard, S. D. Broughton, Esq., R. Carmichael, Esq., Dr. Carson, Bracey Clarke, Esq., E. Cock, Esq., J. W. Cusack, Esq., H. Daniel, Esq., J. B. Estlin, Esq., Dr. Evanson, W. Hetling, Esq., Dr. Hodgkin, Dr. Houston, Dr. Howell, Dr. James Johnson, R. Keate, Esq., O. King, Esq., Dr. Prichard, O. Rees, Esq., Dr. Riley, Richard Smith, Esq., J. C. Swayne, Esq., N. Vye, Esq., Dr. Yellowley. 3Ionday, 22nd August. — " A Report of the Dublin Committee on the Pathology of the Nervous System, by Dr. O'Beirne," was first read. " The Committee feel compelled, on the present occasion, to con- fine themselves to an analysis of the cases of nervous affections which have come under their observation, during the short period which has elapsed since they have considered themselves to be regularly appointed. They are of opinion that, in order to arrive at accurate pathological conclusions on a subject so extensive and complicated, and upon which the most eminent authorities are found to disagree, a very great number of cases should be first submitted to their examination ; then the symptoms of each case carefully registered, and subsequently, accurate post mortem examinations made in the presence of the committee, to ascertain the structural lesion or lesions with which the symptoms co-existed. As far as their investigations have as yet extended, they see that the subject, if considered in all its details, will require a considerable length of time before they can accumulate such a number of cases and matured observations, as would justify them in drawing general conclusions. Further, they have to state, that they have collected some valuable facts, relating to injuries and diseases of the nerves, which seem to throw. light upon disputed points of the physiology and pathology of this portion of the nervous system. They are of opinion, however, that more extended observations on this branch of the subject are required to be mjide. They would also submit the necessity of repeating those experiments on animals, upon which so many authorities rely as a foundation for their doctrines. *' The Committee, influenced by the above considerations, have decided on avoiding, for the present, any attempt at drawing general conclusions. They consider it more judicious to collect and arrange for a future report, should they be re-appointed, the abundant materials which their opportunities enable them to supply. " In furtherance of this object, they have been for some time 392 Scient/Jic Intelliyence, 6fc. engaged in registering the history and symptoms of cases of nervous affections in the wards of the House of Industry, Dublin, and the different hospitals connected with it. This institution contains, independently of cases of paralysis (estimated at about 150), the following cases of mental and nervous affections, arranged as follows : — Males. Femules. Chronic Insane ... 74 179 Epileptic Insane ... 21 33 Congenital Idiots ... 69 02 Epileptic Idiots ... 14 20 178 294-Total, 472. '' The number of cases which the Committee have hitherto been enabled to examine with sufficient accuracy amounts to 41. Of these they have made an analysis which is attached to their report. They also affix an index referring to 17 cases of affections of individual nerves, but regret that they have not had sufficient time to make it either as full or accurate as they could wish. « Dublin, August 17th, 1836." The second paper read was by Dr. O'Beirne, of Dublin, which was an " Abstract of an unpublished work on Tetanus." The reading of this abstract, which was very lengthened, excited much interest among the profession. The points of discussion which ensued were, first, as to what constituted the substantive disease of tetanus, and what was merely pseudo-tetanus. Dr. O'Beirne contending that treatment of cases of the latter kind, as detailed by Dr. Wallis, Dr. Hetling, Dr. King, and others, was not to be received as evidence of the presence of the real disease of tetanus. During the peninsular war, Dr. O'Beirne stated, that he had had frequent opportunities of observing the disease, and at Brussels, he had the sole charge of the officers wounded at Waterloo, among whom several cases of tetanus occurred, which invariably terminated fatally. The result of his experience was, that tobacco, injected by a tube into the bowels, was an anti-tetanic, removing constipation, and affording relief ; and he was really at a loss, such had been the effect of the insertion of the tube in affording relief, to know whether to attribute more to the tobacco or the tube. There had been no disease which had been so confounded with tetanus as old cases of rheumatism, and paralysis was the very antipode of tetanus. The third paper read was entitled *' Aneurism of the Arteria innominata, by Sir David I. H. Dickson." Tuesday, 23rd August. — On the Treatment of some Diseases of the Brain, by Dr. Prichard. — It has been said in former years that the art or practice of medicine has made much more rapid advances than the theory or science. It will hardly be disputed that the reverse of this observation holds good in the present time. For many years past, and especially since more precise investigation than was before pursued, has been practised by means of necroscopy, into the exact nature of organic changes, much accurate knowledge has been acquired, which is perhaps scarcely applicable to practical purposes. There is no class of morbid aflections to which this British Association. 393 remark is more truly applicable, than it is to diseases of the brain, and its investing membranes. Nobody is less disposed than myself to estimate, at a low rate, the value of information obtained through the medium of researches, similar to those of Sir Charles Bell, Drs. Abercrombie, Bright, Hodgkin, Sims, and others in this country ; and of M. M. Rostan, Foville, and many others on the continent. Knowledge of the precise nature of morbid changes has its value, even in a practical point of view, if not by directing us always to remedies, at least, by making us aware what we are to expect in particular cases, as the final results of disease, and as pointing out the limits of what is possible, or what ought to be attempted with reference to cure. Still we ought not to lose sight of the fact, that the recovery of patients, and not merely accurate pathology and diagnosis, is the ultimate object. Perhaps all curative attempts in cases of disease affecting the brain, resolve themselves into the modifications which medical art is capable of effecting in the vascular state, of parts within the skull. We can promote by various means either fullness or inanition of the blood vessels in the brain. Whether anything beyond this is in our power is very uncertain. Besides general and local bleeding, all those means belong to the same class, which act by refrigerating or heating the surfaces either of the head or of other parts. Refrigerant applications to the head have the effect of contracting the calibre of the arteries, and thereby diminishing the quantity of their contents. Pediluvia, or other means of applying warmth to the lower extremi- ties, produce a similar result by augmenting the capacity of vessels remote from the head, and causing a greater quantity of blood to be determined into them. All these means plainly owe their efficacy, to the modification which they bring about in the state of the vascular system of the brain. The only class of remedies respecting the " modus operandi" of which, any question can be raised, is those which produce what is termed counter-irritation, and perhaps the doubt which exists in this instance, arises from the obscurity of the subject. It is generally supposed, and perhaps correctly, at least, it is very difficult to find any other hypothesis on the subject that is more probable, that the means of counter-irritation, such as rube- facients, vesicatories, and issues, produce their effect by lessening a hyperplethoric state of the vessels in internal parts, and that they bring this to pass by increasing the fullness of the vessels in surfaces to which they are immediately applied. There are facts which it is very difficult to reduce under this sort of explanation, as for example, the relief obtained in cases of pneumonia or of bronchitis, by means of blisters applied to the parietes of the chest, there being in these instances no continuity of structure that might render the proposed explanation in some degree intelligible. On the other hand, there is little doubt that such remedies are most efficacious when they are applied over surfaces nearly in juxta-position with the seat of disease, and this fact, if not called in question, goes far towards establishing the notion before alluded to, as to their mode of operation. As the means which are within our reach for treating disorders of the encephalon are so circumscribed, it appears so much the more necessary, to endeavour to a])ply in the most efficacious manner such 394 Scientific Intelligence, ^c. « resources as we possess. I am not disposed to believe that any material improvement can be made in the ordinary rules for the use of evacuants or measures of depletion, but I have no doubt, that an important advantage may be gained, by directing in a particular manner, the mode of counter-irritation, and it is chiefly with the view of recommending this attempt that 1 have premised the foregoing remarks. Long experience has convinced me that the most efficacious way of applying counter-irritation in diseases of the brain is a method not often practised in other places, which has been for many years in almost constant use at the Bristol Infirmary. An objection would probably arise in the minds of those who have not witnessed the application of this remedy, on account of its apparent severity. I hope to convince the medical section, and through this opportunity, to make more general than would otherwise be done, the persuasion that the method of treatment to which I refer is by no means so painful or severe a remedy as it might be supposed to be, and that it greatly exceeds in efficacy any other means by which physicians have attempted to relieve diseases of the brain on a similar principle. The application I recommend is an issue produced either by means of a soft caustic, or what is much better, by an incision over the scalp. The incision is most frequently made in the direction of the sagittal suture, from the summit of the forehead to the occiput. The scalp is divided down to the pericranium. The incision, when that method is used, or the aperture left by the slough, when caustic is employed, is kept open by the insertion of one or two, or in some instances three rows of peas. The discharge thus occasioned is con- siderable, and it obviously takes place from vessels which communicate very freely with the vessels of the encephalon. It would appear, a priori, very probable, than an issue in this particular region, just over the sagittal suture, would have a greater effiict on the state of the brain, than in any other situation, and the result of very nume- rous trials has abundantly established the fact. I can venture to assert, that in all those cases of a cerebral disease in which counter- irritation is at all an available remedy, an issue of the kind now described is, next to bleeding, by far the most important of all the means which have yet been, or are likely to be discovered. The kinds of cerebral disease in which counter-irritation is beneficial, include, according to my experience, all those complaints which are accompanied by stupor or diminished sensibility, excluding all affec- tions, attended by over-excitement, such as maniacal and hysterical diseases. In the latter, I believe all such measures to be for the most part highly injurious. A case has lately occurred in my practice at the Bristol Infirmary, which strongly exemplifies the efficacy of the treatment which I have recommended, and which I have fortunately an opportunity of bring- ing before the Medieal Section in the most convincing way. A youth aged about eighteen, came into the Infirmary labouring under complete amaurosis, which had been coming on gradually for a week or ten days before his admission. At that time it had become so complete that vision was entirely lost, and the pupils were totally insensible to light even when the rays of the sun were suffered to fall immediately into the open eyes. At first he was freely and repeatedly Scientific TntelHf/ence, ^c. 395 bled from the arm and temporal artery, had leeclies applied to the scalp, blisters to the nape of the neck, and took calomel so as to render his gums sore. Finding that no eff'ect whatever was produced by these measures, I gave up the expectation which I had at first enter- tained of his recovering sight, but was resolved to give the remedies a complete trial. I ordered him to be bled, ad deliquiuin. This took place after a small quantity of blood had flowed from his arm while he was in an erect posture. After a few days, he was still perfectly dark. An incision was now made over the sagittal suture ffom the forehead to the occiput. It was filled with peas. In three or four days, precisely at the time when suppuration began to take place, the patient declared that he perceived light, but was scarcely believed, since the pupils were still widely dilated and quite insensible to a strong light. In the course of a few days it was quite evident that he saw, as he could tell when two or three fingers were held up. For some weeks, the iris was still quite irritable, though vision had become in a great degree restored. The subsequent treatment of the case consisted chiefly in occasional leechings, purging, and low diet ; when the issue healed which was not till it had been kept open some months, a seaton in the neck was substituted ; under this treatment the case has terminated in a com- plete recovery of the blessing of sight. I shall not detain the medical section longer upon this topic, but have procured the presence of the patient, and any gentleman who wishes to examine him, either as to the accuracy of what I have related, or to the degree of suffering occasioned by the remedy, or to observe the slight vestiges which it has left, will have an opportunity. II. — Death of Dr. Henry of Manchester. It is with painful feelings that we announce the death of this excel- lent man — more particularly from the melancholy circumstances under which it took place, and from the daily communication which those interested in chemical pursuits held with him, during the meeting of the Bristol Association, where he took an active part. Dr. Henry finished his education in the university of Edinburgh. To this College he manifested through life a great attachment. During his studies in that celebrated establishment, he was exceed- ingly fortunate. He attended the lectures of the illustrious Dr, Black, one of the fathers of chemistry ; and he was the associate and friend of Brougham, of JeflPrey, of Mackintosh, and a number of others, who have since attained, like himself, a high degree of celebrity. Lord Brougham in his address to the Manchester Me- chanics' Institution, in 1835, referred to Dr. Henry in the most respectful terms as a fellow student. " I met," says he, '* an old and worthy friend of mine, a man of great ability and learning, your townsman. Dr. Henry. We were fellow Collegians, and learned Chemistry together — though, God wot, he learned a great deal more than I did." Dr. Henry was intended for the medical profession; but very delicate health, and the necessity of his co-operation in his father's lucrative pursuits, which he subsequently so greatly extended, in- duced him, after some practice, to relinquish that arduous and har- 396 Scientific Intelliyence, ^'c. rassing occupation. A taste for chemical research had also, no doubt, its influence upon his determination. In private life, Dr. Henry had qualities calculated to excite and to rivet esteem and admiration. His conversation was peculiarly attractive and insinuating. Pregnant with varied and extensive information, he knew how to impart it in the most alluring manner. His anecdotes, of which he had a copious selection, were always aptly introduced, and felicitously narrated. Intended to enliven or to illustrate at the time, they generally left upon the memory impres- sions worthy of subsequent reflection. He was a master of the science of conversation. He was never overbearing or dogmatical ; and no one, how humble soever his talents, was in private intercourse made to feel an inferiority, except by a silent comparison, which was, in many cases, almost unavoidable. He never appeared to speak for the purpose of display. He always seemed to talk for others, not for himself. He was always anxious to inspire the most difladent with confidence. He had no repulsive airs, but many admirable graces ; and no one, it is believed, ever enjoyed his conversation without feeling that, high as was his reputation, it aifor^ed a very inadequate estimate of his merits. It might justly be said of him, in the words of an eloquent statesman, that " he was the life and ornament of polished society." In all the relations of private life he was most exemplary. As far as the writer can judge, no man was more highly regarded and more warmly beloved by his relatives. The combination of kindness with mental superiority was his most marked characteristic ; and it attached to him every one who came within the sphere of its influence. Occupying a splendid establishment, he displayed commensurate hospitality. He was particularly distinguished for the liberal and active patronage which he readily afforded to those aspirants in science who attracted his attention. In such cases, he required no solicitation. The encouragement was on his part spontaneous. It was the emanation of his nature. When he formed a favourable opinion, he was very unlike an ordinary patron. His kindness never ebbed and flowed. It was always equable. Any one who tried to deserve it might calculate upon it, at any time, with absolute cer- tainty. He not only possessed high talents himself, but he was almost a creator of talent in others. The younger members of the Literary and Philosophical Society of Manchester will deeply lament the loss of him who peculiarly encouraged and stimulated their earliest efforts. That association will, in all its ramifications, mourn the absence of him who has been " as water which was spilt upon the ground, which cannot be gathered up again." Dr. Henry has conspicuously shewn that a due and regular atten- tion to business, is not incompatible with very high success in science. Soon after the termination of his collegiate education, he delivered in Manchester, several courses of lectures on Chemistry. These lec- tures were illustrated by a very expensive apparatus, and contained experiments of a very highly interesting character. The notes of these courses ultimately led to the publication of a small volume on the science, which has, in successive editions, gradually become a detailed and excellent treatise on the subject. This work has long Scientific Intelligence^ Sfc. 397 been remarkable for the precision of its information, and for the characteristic elegance of its style. Besides this publication, he has contributed to the Transactions of the Royal Society of London, to the Memoirs of the Literary and Philosophical Society of Manchester and to several periodicals, a number of papers of a very interesting and important character. When coal gas was applied to the purpose of illumination, he was one of the first to determine its constitution ; to point out the best mode of analysis ; and to suggest the most effective methods of ob- viating the inconveniences, to which, in its early applications, it was liable. His papers on this subject present a fine specimen of induc- tive research. His investigations on the combinations of the gases by volume ; the absorption of different gases by water ; the applica- tion of Doberiener's spongy platina to gaseous analysis, and a great number of other interesting subjects, have exhibited great philoso- phical acumen, and unsurpassed precision in manipulation. Never was there a more careful, a more impartial, a more accurate experi- menter. It may be mentioned, as an instructive illustration, that on one occasion, when a young friend was assisting him in his opera- tions, the former proceeded, before the termination of an experiment, to calculate the result. ^' Stop," said the Doctor emphatically, '' don't try what the result should be, or there will be danger o{ coaxing the experiment so as to make it to correspond with the estimate." As a literary character, Dr. Henry deserves a much higher reputa- tion, than he has in this respect, yet obtained. His character of Priestley, of Davy, and of WoUaston, are some of the finest speci- mens of that species of composition in the English language. The discrimination which they manifest, and the elegance and accuracy of the style, will render them models of the highest value to those who are required to exercise their powers upon such topics. To the death of Dr. Henry it is necessary to refer. In ancient times, to shorten the natural period of life was, in certain cases, re- garded with applause ; Cato, Brutus, Seneca, and others were lauded by their countrymen, for an act, which has received from modern times unqualified censure. Yet, even in modern times, illustrious instances have occurred. Romilly, Whitbread, and others fixed the limit of their own earthly existence. Such an act cool reflection cannot justify ; but we should not be disposed to admit the right of erring human beings to dictate to Providence in presumptuously assigning a penalty for the offence. In the case of Dr. Henry there was every circumstance w^hich might preclude or could mitigate con- demnation. Months had elapsed during which he had not slept, his ever active mind was perfectly exhausted ; and he was himself con- scious that, as others too clearly observed, his mind was acquiring, by perpetual excitement and want of repose, a tendency to " wander from its dwelling." It is, perhaps, in the very constitution of superior intellects, too continuously exerted, that they should be peculiarly liable to be shaken from their equilibrium. Kven New- ton's transcendent mind was repeatedly subjected to this condition of humanity. The pious and amiable Cowper was also a martyr to mental alienation. It has been so with very dissimilar disj)ositions and characters. The last days of Tasso, of Collins, and of Swift, 398 Scientific InteWgence^ ^"c. were obscured by the same mysterious visitation. The human intel- lect may be, to a certain extent, compared to the dew-drop in the sun-beam, — the brighter it shines, the more rapidly it fades away ! Dr. Henry was 61 years of age. He died on the 2nd, and was interred on Wednesday morning the 7th of September, 1836, in the burial-ground of the Chapel in Cross Street, Manchester, and his coffin was deposited upon that of his distinguished father. This very hurried and equally imperfect tribute has been drawn up by one who has reason to cherish Dr. Henry's memory with mingled feelings of gratitude and admiration. At a period when the pressure of his loss is so heavily felt by those who could appreciate his talents and estimate his worth, it is impossible to do justice to his character. When the agitation of grief shall have subsided, his career and his virtues will, we trust, be detailed by an abler pen, under more favourable circumstances. III. — Artificial Production of Metallic Sulphurets, <^'c., by Electrical Action. The Geological Section of the " British Association for the Advance- ment of Science," having received as novelties some communications on this subject, we think it due to M. Becquerel to state, that he obtained by this means a very considerable number of substances, above seven years since. His apparatus consisted of a tube bent into a syphon shape U, the curved portion being filled with moistened clay, (I'argile pumectee,) and the legs with solutions of the substances of which combinations were sought, and connected by a wire. The crystalline metallic bodies which he obtained were. Metallic copper. Red oxide of copper. Vitreous copper. Grey copper (fahlertz). Metallic silver. Vitreous silver. Chloride of silver. Sulphuret of lead. Carbonate of lead. Sulphate of lead. Oxy-sulphuret of antimony (kermes). Besides a considerable number of alkaline sulphurets, chlorides, bromides, and many double sulphurets, salts, &c. Full details will be found in M, Becquerel's work '' de I'Elec- tricite et du Magnetisme, Tome i., 332 — 350." IV. — Royal ^ (reological Society of Cornwall. Twenty-third Annual Report of the Council. During the past year considerable additions have been made to the Museum and Library, and the funds of the Society continue in a prosperous state : but the council have the painful duty to report that the quarterly meetings have been discontinued in consequence Scientific Intelligence, S^c. 399 of the uniform non-attentlance of the members. This is the more to be regretted because these meetings, if properly supported, might have been the means of exciting a more general taste for geological pur- suits; and it is to be hoped that the attempt which will be made, during the ensuing year, to revive them will be more successful, as your council feel assured that such meetings will greatly tend to promote the welfare of the Society. The publication of the transactions in annual parts has been again brought before the council, and has been strenuously advocated as a measure which would insure the more frequent communication of valuable memoirs. The papers already laid before the Society will appear in the fifth volume, which it is expected will be finished against the next anniversary : and the council recommend the imme- diate publication of such as may be hereafter presented, in the hope that such a regulation may elicit a more abundant supply of scientific communications than has been received on the present occasion. The council, however, whilst regretting the inactivity of the Society during the past year, have great satisfaction in being able to state that considerable progress has been made towards the attainment of a more accurate knowledge of the geological structure of Cornwall, by the able and indefatigable labours of Mr. De la Beche, who has kindly acceded to their request of giving the members some informa- tion concerning the result of his investigations. By order, HENRY S. BOASE, Secretary. September '2,nd, 1856. The following papers have been read since the last report : — I. A chemical examination of a peculiar substance incru sting the roof of a cavern in Cornwall. By Henry S. Boase, M.D., Secretary of the Society. TI. On Slikensides, and whether they afford evidences of mechani- cal origin. By W. J. Henwood, F.G.S., Lon. and Paris, Hon. M.Y.P.S., Assay Master of Tin in the Duchy of Cornwall, Curator of the Museum. Til. On a granite vein and the phenomena which accompany it at Polmear Cove. By Henry S. Boase, M.D. IV. On periodical variations in the quantities of water afforded by springs. By W. J. Henwood, F.G.S. Cor. Mem. Plymouth Insti- tution. V. An account of the Quantity of Tin produced in Cornwall and Devon, in the year ending w^ith the Midsummer Quarter, 183(3. By Joseph Came, Esq., F.R.S., F.G.S., M.R.I.A., &c.. Treasurer of the Society. VI. An account of the Quantity of Copper produced in Great Britain and Ireland, in the year ending the 30th June, 183G. By Alfred Jenkin, Esq. OFFICERS AND COUNCIL FOR THE PRESENT YEAR. President, Davies Gilbert, Esq., D.C.L., F.R.S., &c., &c.— Vice Presidents, Robert Were Fox, Sir W. Molesworth, Bart., M.P., F.R.S., Rev. Canon Rogers, John Scobell. — Secretary, Henry S. Boase, M.D. — Treasurer, Joseph Came, F.R.S. — Curator, W. J. Henwood, F.G.S. — Librarian, Richard Hocking. c^ ^ i ^d d IS ® ^ I 4^ o RE.MARKS. Brisk wind, A.M. rain, cumuli on blue sky with occasional showers, evg. calm- Gentle wind, A.M. cloudy, P.M. cumuli on blue sky, evening calm and clear- Gentle wind, A.M. nearly cloudless, P.M. sky overcast, evg. rain, wind rising. Gentle wind, A.M. overcast, P.M. continued rain and fog. Brisk wind, A.M. cloudy, slight showers, P.M. cumuli on blue sky, evg. clear. Calm, A.M. cloudy, P.M. partially clear, evening hazy clouds rising in the N. Brisk wind, frequent and heavy showers, evening calm and cloudy. Brisk wind, A.M. cumuli abundant, P.M. gradually overcast, evg. calm, rain. Calm, A.M. fleecy cumuli and cirri abundant, 4 P.M. heavy shower, evg. clear. 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O ■r- 30 GO "* 'C 'O t^ CO C> O T-I so GO ■* lO O t^ CO Oi C 1 ,— 1 ^H vi aj <'. — -^ .— :-^ CO c/"^ <; H r- pH ;i- r/^ y. < H r' .— ^ VD :/.■ r". r-< -^ ■-< i^ b ^ RECORDS OF GENERAL SCIENCE. Article I. « Biograi^hy of M. le Comte Lagrange. {Concluded from page 251.) During his residence in Berlin, M. de Lagrange married, not so much for any inclination for the state, it is said, as because it was customary for the academicians to be married. This union was followed by several misfortunes. M. de Lagrange had a child, who died, we are informed, while young. His wife died, likewise, after a tedious and painful disease. M. de Lagrange took care of her during her illness with the most inviolable attachment, hardly ever leaving her, and contriving new methods for her cure. This second loss rendered his abode in Berlin disagreeable : besides, he was afraid that the tranquillity of Prussia would be inter- rupted. These motives caused him to listen to the offers which were made to induce him to go to France, where he hoped to enjoy greater tranquillity. He reached that country in 1787, and was soon after surprised by the Revolution. He passed through it without experiencing any personal misfortune. About this period his Mecanique Analytique appeared. M. de Lagrange had sent the manuscript from Berlin, and had entrusted the publication of it to one of the most celebrated French mathematicians. It had been printed for two years before Lagrange even thought of opening it ; and when a gentleman, to whom he communi- cated the circumstance, expressed his astonishment at so much indifference, *' I was disgusted," said he, *' with these VOL. IV. 2d 402 Biography of M. le Comte Lagrange. kinds of combinations, and I set myself to learn chemistry, which I now find easy, for it may be learned in the same manner as algebra." It is necessary to be a Lagrange to seek in algebra a model of fticility. It is remarkable, that the taste for mathematics may be thus destroyed, and revive again. D'Alembert seems to have undergone the same kind of change. In 1792, M. de Lagrange married, a second time, a young and beautiful lady, daughter of M. Lemonnier, one of his fellow members of the Academy. She rendered his life very happy. He observed in his last moments, that he found death easy, and that his regret in leaving an excellent wife could alone make it painful. When, after the events of Thermidor, public instruction was again re-established, M. de Lagrange was named Professor of the Normal School. The lectures which he there delivered have been printed. When the Polytechnic School was formed, he was likewise one of its first Professors ; and those who had the happiness to hear him know with what respect he was listened to. It was then that he published his Calcul des Fonctions Analytiques, his Traitt des Fonctions, and his Resolution des Equations Numeriques. These works com- posed for the Polytechnic School, were not one of the least causes of its celebrity. When the Institute was formed, M. de Lagrange was necessarily named the first member in the section of Geometry. When the Board of Longitude was established, he was appointed one of its members; and till the very last period of his life, nobody was more exact than he in his attendance at the meetings of both these learned bodies. At the epoch of the 18th Brumaire, he was named Senator, and successively Grand Officer of the Legion of Honour, and Grand Cross of the Order of Reunion. The eclat of rank and fortune did not seduce him for a moment. He retained always the same mode of life, the same habit of study, the same simplicity. This wise conduct was the more necessary for him, because he had always been of a feeble constitution ;"and it was to this extreme moderation, in every thing but study, that we must ascribe the length of his life and his old age free from infirmity. He had likewise the rare good fortune to preserve his genius to the Biography of M. le Comte Lagrange. 403 end of his life. Indeed, if we examine the whole of his works, we shall find in them marks of the progress of the science, but no indication of old age. He had undertaken, at the latter period of his life, to give a new edition of the Mecanique Anahjtique considerably augmented. He pub- lished the first volume, in which, among other remarkable additions, we admire his fine investigations of the most general questions of astronomy and mechanics. He laboured with the most indefatigable industry at the two remaining volumes, in which he intended, it is said, to treat of the great phenomena of the system of the world ; but this labour hastened the period of his death. It is said, that the manuscript of the second volume exists, written entirely with his own hand. It is to be wished, for the good of the sciences, that the publication of this precious monument be committed to persons who will acquit themselves with promptitude and fidelity. The character of the genius of Lagrange has been exactly appreciated by a philosopher whose name in the sciences has been long associated with his own. If we durst add any thing to that judgment, it would be to confirm it, by recalling to memory the impression made upon the mind by the perusal of the works of Lagrange. It is not only the pleasure that results from a clear and accurate arrange- ment, it is a ray of light which darts upon the mind, removes the obscurity from the most complicated objects, and discovers to your astonished eyes the certain and direct road which leads to the object that you wish to obtain. When we have once read and understood a memoir of Lagrange, we have never any occasion to recur to it again ; we have learned the whole, and never can forget it. In this generality of his views he rises above Euler. Euler, indeed, possesses other advantages : in the immense variety of his works, he lays open a multitude of extraordinary means, and a fertility of invention, which nothing can stop. Mathematicians, by reading him, learn all the secrets of the science of mathematics; but M. de Lagrange alone can offer them the model of that perfection, almost ideal, which we ought to endeavour to attain. Notwithstanding what we have said, we should leave a very imperfect character of Lagrange, if we did not notice 2 D 2 404 M. Cacciatore on the Moveable Star his wit. He possessed it in such perfection, that it alone would have raised the reputation of any other person but M. de Lagrange. What a turn of thinking must he have had, who, by way of relaxation from the most abstract studies, made choice of the history of religion and of medicine! It is true, tliat in consequence of this investiga- tion, he lost all confidence in medicine ; but this scepticism was so simple and tolerant, that if it was an error, it was impossible not to forgive it. This philosopher, who knew so many things, was exceedingly ready to acknowledge his ignorance. These simple words, / do not know, were his favourite expression. He generally began and finished in this manner the statement of his doubts. He was not apt to be satisfied with words, nor to stop at the surface of things. He deprived opinions and things of the envelope with which they are usually covered ; and when he had thus exposed them naked, he gave his thoughts respecting them, usually in an original and lively manner, as remark- able for depth of sense, as for fineness of expression. Many of his sayings are well known. One of his friends was speaking to him of an opinion which, alternately adopted and rejected, admitted and modified, by philoso- phers, had become at last, a popular prejudice. *' What!" said M. de Lagrange, " are you astonished at that? It is the very thing which always happens. Prejudices are nothing else than the cast clothes of philosophers, in which the rabble dress themselves." We state this anecdote because it points out well the nature of observations. Though his figure was good, he would never permit his portrait to be drawn. He thought, that the productions of the mind were alone entitled to survive. If his face remains unknown, the remembrance of his genius will last as long as civilization continues to dwell upon earth. Article II. Abstract of a Letter from M. Cacciatore, Director of the Observatory of Palermo, respecting the Moveable Star observed by him in 1835. The author began, in 1835, a series of observations on stars, which he proposed to follow out four evenings in succession, observed by him in 1835. 406 with Ramsden's moveable vertical circle, in order to deduce corrected observations of the error in the line of collima- tion. These observations were principally on stars, which had peculiar motions, because he thought, that by com- paring them with such as he had made before, much pre- cision and accuracy might be attained. For, although the interval of time between the observations did not exceed 45 years at most, and was often 40 or 30 only ; yet, as they were made with the same instrument, by the same methods of observations, calculation, and by the same eye, their differences were not subject to the small inequalities, which might effect observations made with different instru- ments and observers. The nature of the great circle of Rams- den, in his possession, not enabling him to make precise observations on the revolutionary movements of the double and triple stars, he was confined to the investigation of their peculiar motions. According to this method, it is. easy to observe other stars which occasionally accompany, in the field of the eye-glass, the star under examination. Caccia- tore is in the habit of noting the difference in their passage of the vertical wire, and the difference in their zenith dis- tance. When there are several stars in the field, he is in the habit of estimating these differences at sight, and experience has fully shewn, that his estimate is never far from the truth. He had in vain, during several evenings in the month of May, 1836, prepared his instrument for observation, until the 11th, when he began his series of observations. Among the stars, which he observed, was the 503rd of Mayer, which is the 17th of the 12th hour of Piazzi ; it is of the 7th or 8th magnitude, and has, according to the catalogue, a peculiar angular motion in right ascension — 0"-33. Near it he saw another star of less lustre, and a little smaller, which followed it at a distance of about two seconds of time to its passage, and which was about 2^ minutes farther . to the south. This constituted the whole of the observa- tion ; the star was noted, and no more was thought of it. Next day the weather was unfavourable, and it was only on the 14th, that the observations were resumed. When his assistant read to him the note which he had made relating to the small star, he was surprized at not finding it — he feared that he had committed an error — he diminished 406 M, Cacciatore on the Moveable Star the light of his glass, and quickly perceived a star of the 8th magnitude preceding the principal by 8 seconds in right ascension, and only IJ minute to the south. He noted these facts, and left off his observations, resolved to leave, on the following evening, the star of Mayer for the purpose of following the new one. But unfortunately the sky became more unfavourable than on the preceding night; it continued constantly in a cloudy or rainy state till the end of the month, and, when on the evening of the second of June he resumed his research, the twilight was so strong, that he could do nothing* He had hopes, that in the course of the present year, he might be able to ascertain something of a satisfactory nature ; but from the month of September, 1835, to March, 1836, the season continued so remarkably unpropitious, that he was able to make but a very limited number of observations, even on Halley's comet. For 38 years that he has resided in the Observatory, he states, that he never knew of a similar occurrence. He had made, however, during some morn- ings in the month of January, all possible observations, being strongly encouraged by the circumstance, that near the 503rd star of Mayer, there was no other star. He pur- sued his investigations in those regions which appeared most convenient^ abandoning, for this purpose, all his other labours, in order to devote himself entirely to this research, to prevent any of the rare intervals from the covered state of the sky from being lost ; but all in vain. Disappointed by such loss of time, and fruitless labour, he conceives, that he would be wanting in his duty, if he did not invite astronomers to look out for the new star, which, from the facts described, undoubtedly exists in the heavens. He has given up all idea of discovering it himself* But who knows if some more fortunate astronomer may not discover quickly, near the constellation of the Virgin, this star which presented, in three days, a motion less than a minute of a degree in right ascension, and less than half a minute of declination. If we consider it placed beyond Herschel, as appears natural, it ought to have a semi great axis double of that of Herschel, as Cacciatore pointed out in his memoir on the return of Halley's comet, published in May, 1835, at the time when he was in full hope^ of observed by Idm in 1835. 407 again seeing the new star. Cacciatore has addressed these observations to the Bibliotheque Universelle, for the purpose of attracting the attention of astronomers ; and we have inserted them here, in order that the scientific men of this country may be aware of the facts. Article III. On the Minerals containing Columbium. By Thomas Thomson, M. D., F. R. S., L.&E., Regius Professor of Chemistry in the University of Glasgow. The minerals containing columbium are so scarce, that I am not aware of any attempt hitherto made to draw up a mineralogical description of them ; far less to subject them to a chemical analysis. Dr. Torrey of New York, was kind enough during the course of the present summer to send me several specimens of columbite, from a new American locality, together with a request to subject the mineral to a chemical analysis. It turned out on exami- nation to be a new species, not hitherto mentioned by mineralogists. This led me to examine the Bohemian columbite, a specimen of which, liberally presented to me more than 20 years ago, by Mr. Heuland, I have in my cabinet. This last is the variety to be found in mineral collections, and seems to be the same with the specimen of columbite in the British Museum, originally examined by Mr. Hatchett. From a statement in Haidinger's edition of Mohs's Mineralogy,* it appears that this mineral has been analyzed by Vogel and Count Borkowski, the results of whose analyses are given ; though I do not know where they were published.f The tantalite from Kimito in Finland, originally exa- mined by Ekerberg, and afterwards analyzed by Berzelius, constitutes a third species.:}: While another specimen from * Vol. ii. p. 392. t These results are as follows : — Columbic acid, 75 74 Oxide of tin 1 0-4 Oxide of iron 17 20 Oxide of manganese . ... 5 4*6 98 99 X Afliandlingar, iv. 262. 408 Z)r. Thomas Thomson on the the same locality discovered by Nordenskjold, and likewise analyzed by Berzelius, constitutes a fourth species.* I pro- pose in this paper to give a short account of the characters and chemical constitution of these four species. 1. Torr elite. I give this name to the new species, which I have just received from New York, by the liberality and kindness of Dr. Torrey. I haVe been induced to name it after my much respected friend, as a slight acknowledgment to him for the many interesting and new minerals with which he has from time to time favoured me.f Torrelite has been found lately in a granite rock at Middleton, in the state of Connecticut, where it is occa- sionally disclosed by the workmen, who are blasting out felspar for a porcelain manufactory. It occurs most commonly in irregular masses about the size of a filbert ; though occasionally, as appears from a fragment of a crystal in my possession, it is crystallized. The figure in the margin represents this fragment. It is a four sided prism, the base of which, P, is so rough and irre- gular, that we cannot decide whether it forms a right angle with the faces of the prism. The longitudinal faces of the prism are sensibly equal. The edge between M and T is re-placed by a narrow face a. The only measurements that I could make are the following : M M on T (mean of 5 trials) T on a (mean of 3 trials) M on « (mean of 3 trials) 84° 20' 152° 110° 20' * Afhandlingar, vi. 237. t The name Torrelite has.been already given by Professor Ren wick to a mineral of a Vermillion colour, which he subjected to analysis, and which he found to contain oxide of cerium , but which was afterwards examined by Mr. Children and Mr. Faraday, without their being able to discover any cerium (see Annals of Philosophy, 2nd series, ix. 217 and 221). Ten years having elapsed since these experiments were made, and no mineralogist, so far as I know, having noticed Mr. Renwick's torrelite, I take it for granted that its claims to rank as a new species have not been admitted. Minerals containing Columbium. 409 The longitudinal faces of the prisms are quite smooth. It is probable, from this crystal that the primary form of torrelite is a right oblique prism terminated by a rhombic bar, whose angles are 84° 20' and 95° 40'. The trianglar face o is too rough on the surface for measurement. It is sensibly an equilateral triangle, and its inclination to the adjacent edge, is about 143° 45' from a mean of several trials. The colour is black, or at least much darker than that of columbite. The surface is iridescent, with a play of blue and red colours. Lustre imperfectly metallic, almost resinous, being very similar to that of cherry coal. In one direction (parallel to face M) it is imperfectly foliated. Cross fracture gra- nular. Opaque. " * Hardness 4-25. Specific gravity 4-8038. Before the blow-pipe both with carbonate of soda and borax, it fuses into a dark red bead, shewing the presence of iron. With a great excess of carbonate of soda, the green colour characteristic of manganese makes its appear- ance. When reduced to a fine powder the colour is dark chocolate brown. 1. 100 grains being exposed to a red heat, lost 0*35 grains of weight, which was considered as water. 2. 20 grains of the mineral in fine powder were mixed with 160 grains of crystallized bi-sulphate of potash, and gradually heated in a platinum crucible, over an Argand's spirit lamp. Care was taken to keep the heat moderate till the ebullition of the salt was at an end. It was then raised to redness, and the whole was kept in fusion for, at least, a quarter of an hour. 3. The red mass on cooling became white with an ex- ceedingly slight tint of slate blue. It was softened in water and finally digested in muriatic acid for 24 hours. The whole was then thrown on a filter, and the white powder collected on the filter was thoroughly washed with boiling hot water. It was then dried in the open air, and digested for 24 hours in a solution of caustic ammonia. 4. The ammoniacal solution was then filtered off, and saturated with muriatic acid. A white flocky precipitate fell, which, after ignition, assumed a shade of brown, and weighed 009 grain. 410 Dr. Thoinas Thomson on the Tested by the blow-pipe, it fused with effervescence, with carbonate of soda forming a very white opaque bead. With borax and bi-phosphate of soda, it fused into transparent beads, the latter of which, had a very slight tint of yellow. From these phenomena, I considered it as columbic acid very slightly contaminated with iron. It was evidently not tungstic acid, in order to discover which, I had been induced to digest the columbic acid in ammonia.''^ I was not aware before that columbic acid is soluble in ammonia; but verified the fact by subsequent trials. The quantity dissolved, however, is always very small ; and after ignition columbic acid becomes quite insoluble in ammonia. 5. The residual columbic acid being ignited, weighed 15*24 grains. AVhile red hot, it had a distinct tint of yellow, and when allowed to codl it retained a perceptible brownish tinge. It was therefore, mixed with six times its weight of anhydrous carbonate of soda aud fused. The fused mass, when coldj had a light green colour shewing the presence of manganese. It was softened with water, digested in muriatic acid, and the whole thrown on a filter to collect the columbic acid ; which was thoroughly washed with boiling water, dried and ignited. It weighed after ignition 14*69 grains. Thus, making the whole columbic acid 14*78 grains (adding what had been dissolved in ammonia). It was beautifully white, and apparently pure. The muriatic solution, containing the soda and impurity from the columbic acid, was boiled with an excess of car- bonate of soda in a flask. A dark brown matter fell, which being edulcorated, dried, and ignited, weighed 0*55 grain, and was red oxide of manganese. 6. The muriatic acid solution (paragraph 3) was as nearly neutralized as possible, and then mixed and digested with benzoate of ammonia. The iron was thrown down in the state of benzoated peroxide. After ignition, it weighed 3*48 grains = 3*13 grains protoxide of iron. 7. The liquid thus freed from iron was mixed with an excess of carbonate of soda and boiled. The precipitate that fell, after edulcoration and ignition, was red oxide of manganese, and weighed 1*23 grains: making, with the * Tungstic acid liad been discovered by Ekeberg in lantalitc, and hii discovery had been confirmed by Berzelius. Minerals containing Columbium, 411 0*55 grain, (of paragraph 6) 1*78 grains of red oxide of manganese =s 1*6 gr. protoxide. Thus, the constituents of torrelite are, Columbic acid, .... 14-78 73-90 Protoxide of iron, . . . 3*13 15 65 Protoxide of manganese, . 1*60 8*00 Water, 0-07 035 19-58 97-90 To determine the atomic constitution of this mineral, we must recollect, that the atomic weight of columbic acid is 25-75, of protoxide of iron 4*5, and of protoxide of man- ganese 4-5. If we divide the preceding numbers by these atomic weights we obtain. Atoms. Columbic acid, .... 2*87 or 1-6 Protoxide of iron, . . . 3*48 or 1-96 Protoxide of manganese, . 1*77 or 1* These numbers leave no doubt, that the true constitution of the mineral is, 1 J atoms columbic acid 2 atoms protoxide of iron 1 atom protoxide of manganese The atoms of the bases being twice as many as those of columbic acid, we see that torrelite is composed of dicolum- bates : and, as there are twice as many atoms of protoxide of iron as of protoxide of manganese, it is obviously com- posed of 2 atoms dicolumbate of iron 1 atom dicolumbate of manganese So that the formula indicating its constitution is, 2/2 .q\ •f mn^ CI. 2. Columhite. The name columhite^ given by Mr. Hatchett to the original specimen in the British Museum, may with propriety be applied to the Bohemian specimens ; because, there are strong reasons for considering the constitution of both as very nearly alike.* I do not know who was the discoverer of it at Bodenmais, in Bohemia. But as I have already mentioned, I got a specimen of the Bohemian columbitc • This, indeed, has already been done by M. Gustav Rose. 412 Dr. Thomas Thomson on the about 22 years ago from Mr. Henland, and I think it pro- bable, that it was about that time, or not long before it, that this mineral was discovered. No allusion is made to it in Klaproth's paper on the analyses of the Finland Tan- talite written in 1809.* And, what is more singular, Hoff- man in the last volume of his Mineralogy, published in Freiberg in 1817, makes no mention of the Bohemian columbite, and says, that the specific gravity of the tanta- lite, as stated by Wollaston and Klaproth is too low,t shewing clearly, that at that time he was ignorant of the existence of the Bohemian columbite, though, before that period, I had a specimen of it in my cabinet. Hauy in his Traite cle Miner alogie, 2nd edition, published in 1822, (tom. iv. p. 391) notices the Bohemian columbite, which he calls tantalite, and which, he says, had been recently discovered at Bodenmais, in a granite which contained also beryls, iolite and oxide of uranium. But it is obvious from his statement, that he was not aware that any difference existed between the Bodenmais columbite and the tantalite of Finland. For he gives 6*5 as the specific gravity of tan- talite, shewing that he had never seen, or, at least, never examined the Bohemian columbite. Mr. William Phillips, in the third edition of his Minera- logy (page 270), published in 1823, notices the Bohemian columbite. But he gives its specific gravity 6*464, and states its primary form to be an oblique four-sided prism of 94° and 86°. A statement inconsistent with the measure- ments of a crystal in possession of Mr. Brooke, and which he himself gives on the authority of that eminent crystal- lographer. A comparison of these measurements with those given in Haidinger's translation of Mohs's Mineralogy (vol. iii. p. 390), leaves no doubt, that Mr. Brooke's crystal was from Bodenmais, and that it is specifically different from the Finland tantalite. M. Gustav Rose, in his Elemente der Krystallographie, published in 1833, has divided the minerals, previously confounded together on the continent of Europe under the name tantalite, into two species. The one, consisting of the specimens found at Bodenmais and the Massachuset specimen in the British Museum, he calls coliimhite: the * Beitrage, v. 1. t Hoftman's Handbuch iler Miiieralogie, iv: i?, IP.'i. Minerals containing Columhium. 413 other, consisting of the specimens from Finland, discovered by Nordenskjold, and which give a cinnamon brown powder when pounded, he calls tantalite. He mentions a fine cry- stal of columbite in the Royal Collection at Berlin, in which the faces on both sides of the crystal are exposed ; but he was not able to measure its angles, nor to determine its structure. The specimen of Bohemian columbite in my cabinet is a portion of a crystal about an inch in length, and wanting both the terminations. Its length was originally about 1^ inch ; but I broke a fragment off it to enable me to subject it to a chemical analysis. Its colour is black, but it is lighter than that of torrelite. And, when reduced to a fine powder, it still retains its black colour. But, when the powder is heated to redness, it changes to chocolate brown like that of torrelite ; though it loses only ^(jVoth of its weight. The structure is foliated. Only two faces of the crystal, which is a flat four-sided prism, are smooth enough for measurement. They meet at an angle of 90^, shewing that the prism is rectangular; and Mr. Brooke has ascertained, that the primary form is a right rectangular prism. The faces of the prism are streaked longitudinally. The following are the measurements by Mr. Brooke of a crystal in his possession : P on M or T . . . 90° MonT. . . . . 90 P on a^ or d^ . 136 30' P on c . . . . . 120 Tonrfi ... 156 30 Tonrf2 . . . 114 30 T on c 150 414 Dr. Thomas Thomson on the Opaque. Lustre semi-metallic, inclining to resinous. Fracture imperfect conchoidal. Hardness 6 or 6-25. Specific gravity by my trials 6-0380. This is exactly the specific gravity given in Haidinger's translation of Mohs's Mineralogy, shewing that his descrip- tion is of the same mineral with that in my possession. The phenomena, before the blow-pipe with columbite, are the same as with torrelite. The presence of iron and man- ganese being indicated. I analyzed 20 grains of Bohemian columbite precisely in the same way as I had already analyzed torrelite. But as my quantity was limited, I was at more pains to prevent any loss. The consequence was (as is frequently the case under such circumstances), that I obtained a slight excess. It is proper to mention also, that when the peroxide of iron extracted from the mineral was ignited, and then digested in muriatic acid, it left 0*2 grain of columbic acid. Thus, shewing that columbic acid, before ignition, is not only slightly soluble in ammonia, but also in muriatic acid. The result of my analysis was as follows : Columbic acid, .... 15-93 79*65 Protoxide of iron, . . . 2*80 14*00 Protoxide of manganese, . 1*51 7*55 Oxide of tin, 0*10 0*50 Moisture, 0*01 0*05 20*35 101*75 Dividing these numbers by their atomic weights, we obtain. Atoms. Columbic acid, 3*09 or 1*987 Protoxide of iron, . . . . 3*11 or 2* Protoxide of manganese, . . 1*67 or 1*07 These numbers approach very nearly to 2 atoms columbic acid 2 atoms protoxide of iron 1 atom protoxide of manganese which evidently shews the constitution of columbite to be 1 atom dicolumbate of iron 1 atom columbate of manganese The formula indicating its composition is, f- CI -f mn C\. It differs from torrelite by containing half an atom of columbic acid more. Torrelite consists of li atom columbic acid united to 3 atoms of oxides of iron and manganese. Minerals containing Columhium. ' 415 while columbite consists of 2 atoms columbic acid united to 3 atoms of the same bases. Dr. Wollaston analyzed 5 grains of the original specimen of columbite in the British Museum, and obtained, Columbic acid, .... 4* or 80 Protoxide of iron, . . . 0*75 15 Protoxide of manganese, 0-25 5 5-00^ 100 This approaches pretty nearly to my analysis. We cannot expect minute accuracy in an analysis conducted on so small a scale. But it is near enough, I conceive, to leave no doubt about the identity of the columbite in the British Museum and that found at Bodenmais. This is farther corroborated by the specific gravity of the British Museum specimen, vrhich Mr. Hatchett found to be 5'918. 3. Tantalite. The specimens of tantalite from Finland, by the examina- tion of which Ekeberg discovered the metallic substance to which he gave the name of tantalum, were sent him by M. Geyer ; and it is not accurately known from what part of Finland they came. Berzelius conjectures that they had been found at Skogsbole, in the parish of Kimito, where an attempt had been made to obtain tin, for the oxide of which tantalite had been taken. At Ekeberg's death, his mineral collection was purchased by Dr. Mac- michael, who was liberal enough to give to Berzelius all the specimens of tantalite which it contained. One of these consisted of a small piece, labelled by Ekeberg as having a specific gravity of 7*236. The rest had been reduced to powder, obviously for analysis Berzelius gives no description of this tantalite, and the quantity of it was so small, that he was able to use only one gramme or 15*433 grains ; and, though some anomalies occurred in the analysis, it was not in his power to remove them by repeating it. Klaproth obviously employed the same mineral in his analysis of tantalite. He gives the following short description of it : Colour, iron black, amorphous. Lustre, semi-metallic, ^ Phil. Trans. 1809, . p. 248 416 Dr. Thomas Thomson on the hard, brittle. Colour of streak, grayish black with a shade of brown. Specific gravity 7*300.''^ Its constituents, as determined by the analysis of Berze- lius, are Columbic acid, .... 83*2 Protoxide of iron, . . . 7*2 Protoxide of manganese, . 7*4 Oxide of tin, 0*6 98-4t Dividing these numbers by the atomic weight of each, we obtain. Atoms. Columbic acid, .... 3*23 or 2-018 Protoxide of iron, . . . 1*6 or 1- Protoxide of manganese, . 1*64 or 1*025 These numbers leave no doubt, that the constitution of tantalite is 2 atoms columbic acid 1 atom protoxide of iron 1 atom protoxide of manganese Thus, the number of atoms of the acid and of the bases is equal. It is composed obviously of 1 atom columbate of iron 1 atom columbate of manganese So that the formula indicating its constitution is /CI 4- mn CI. It differs from columbite in containing 1 atom less of protoxide of iron, united with the same proportion of columbic acid and columbate of manganese. 4. Ferrotantalite. Among the specimens of tantalite found in Ekeberg's collection, there was one in powder, which had the colour of rust, and which was marked as obtained from a single tantalite cryslal, whose specific gravity was 7-936. This powder Berzelius attempted to analyze in 1815; but the result was unsatisfactory. In 1818, he received from Nor- denskjold a specimen of a tantalite from Kimito, which, when pounded, gave a cinnamon brown power, which he • Beitrage, v. 2. t Afhandlingar, iv. 262. Minerals containing Columbium. 417 subjected to analysis.* This variety, or rather, this new species, I distinguish by the name ferrotantalite ; because it consists almost wholly of columbic acid combined with protoxide of iron. Colour black. In irregular masses, with some indications of crystalline faces ; though it is impossible to make out the shape of the crystal. Lustre metallic, and, in general, greater than that of common tantalite. Internal lustre often less, owing to large rents in the mineral, the surfaces of which exhibit a rainbow tarnish. Fracture uneven. Hard enough to scratch glass. Specific gravity 7*655. Powder dark reddish brown, becoming lighter the more finely it is pounded. Not acted on by acids. Before the blow-pipe, ^erse, not altered. With borax, when in solid pieces, it dissolves very slowly, or not at all. In fine powder, it dissolves very slowly. The glass has a green colour, in which white particles float : and it does not become milky by flaming. In bi-phosphate of soda, it dissolves much more easily, and the glass has the same colour as when common tantalite is employed. The addition of saltpetre indicates a small quantity of manganese. With carbonate of soda it does not dissolve. But when it is heated with a mixture of carbonate of soda and borax on charcoal, and exposed to a good reducing heat grains of tin are obtained. Being subjected to analysis by Berzelius, he obtained, Columbic acid, .... 85*85 Protoxide of iron, . . . 12*97 Protoxide of manganese, . 1*61 Oxide of tin, 0*80 Lime, 0*56 Silica, 0*72 102*51t * Afhandlingar, vi. 237. t Afhandlingar, vi. 243. The excess is probably owing to over-rating the quantity of columbic acid in the mineral. Had the amount been 83-43, the atoms of acid and bases would have been the s;une. Now, the difference between 8/)'85 and 83*43 is 2*42, which is very nearly the amount of the excess. VOL. IV. 2 E 418 Dr. Thomas Thomson on the Dividing these numbers by the atomic weig-lits of the bodies, we obtain, Atoms. Columbic acid, .... 3-33 or 1* Protoxide of iron, . . . 2*88^ ^p o-97 Protoxide of manganese, . 0*36 S obviously, 1 atom columbic acid 1 atom protoxide of iron and manganese. The difference between it and common tantalite is, that instead of 1 atom protoxide of iron and 1 atom protoxide of manganese, united with two atoms of columbic acid, it consists of 2 atoms of columbic acid, combined with 1-777 atoms protoxide of iron, and 0*223 atonjs of protoxide of manganese. Or, which comes to the same thing, we may consider it as composed of 9 atoms columbic acid 8 atoms protoxide of iron 1 atom protoxide of manganese So that the formula indicating its constitution is, 8/ CI + mn CI. Such are the characters, and such the constitution of the four species of minerals composed of columbic acid, united to protoxide of iron and protoxide of manganese. The formulas indicating their constitution are as follow : 1. Torrelite, . . . 2p CI + mn^ CI. 2. Columbite, . . . /^ CI + mn CI. 3. Tantalite, . . . fC\ + mnC\. 4. Ferrotantalite, . 8/Cl + mnC\. Let us now compare their specific gravities with each other. 1. Torrelite, . . . 4-8038 2. Columbite, . . . 6-0380 3. Tantalite, . . . 7-3000 4. Ferrotantalite, . 7-6550 Thus, as the columbic acid increases, the specific gravity increases, shewing the high specific gravity which must belong to columbic acid. The crystalline shape of torrelite and columbite is dif- ferent. It is probable, that tantalite and ferrotantalite have each a peculiar crystalline shape, although, from the variety of their minerals, and the imperfect state of the crystals, that point has not been ascertained. Minerals containing Columbium. 419 Torrelite and columbite differ in their hardness, that of the former being 4*25, of the latter 6*25. Tantalite and ferro tan tali te are described as hard ; but we know not the exact amount. From the preceding observations and analyses, I con- ceive, that no doubts can remain either with mineralogists or chemists, that the four minerals described in this paper constitute four different species. Article IV. Experiments and Observations on Visible Vibration, By Charles Tomlinson, Esq. {Continued from page 20.) on the vibration of porcelain and earthenware vessels. 116. The investigation of the vibratory action of vessels of other material than glass has been purposely deferred until now, because, from a few phenomena already alluded to (76), it would seem, that the vibration of porcelain, earthen, and wedgwood-ware vessels is peculiar, and, there- fore, deserving a separate inquiry. It has been said (75), that two tones can be produced from earthenware mugs, &c., and Mr. Dodd found that with a common blue cylindrical cup, two notes D and E were produced separately, and alternated four times during one revolution of the finger : that is, there were four points producing D, and four other points producing E. The additional phenomena noticed (75) are not very precisely stated, as the mode of vibration of these vessels, then adopted by Mr. Dodd, **by striking the edge gently with a quill," is a very imperfect one, and not capable of pro- ducing the decisive results, which the judicious application of a well rosined bow effects. I, therefore, propose in this paper, to commence a statement of the results of my inquiry into the vibratory action of vessels of porcelain, china, earthenware, metal and wood. The very curious results which I have obtained, may, probably, be thought sufficiently important to allow me to state them somewhat fully. 2 E 2 420 Mr. Charles Tomlwsons Experiments 117. The circumstance of two notes so near together as D and E, being produced from one vessel, is, at first view, by no means in accordance with the principles en- deavoured to be established in my last paper on the funda- mental and secondary tones, and nodal divisions of a glass goblet (95 to 115). With earthenware vessels, Mr. Dodd states, that between the two notes produced, he never obtained an interval of more than three semi-tones : — that these two notes occurring alternately at eight distinct points of the vessel, led Mr. Dodd to suppose the existence of eight vertical nodal lines, each of which, separated two vibrating arcs, which produced different notes (75). I have shewn, that in glass vessels, the fundamental tone is always due to a quadripartite division, and that eight divisions produce a note generally in the second octave above the fundamental note : the octopartite division is, in fact, my second secondary tone, and as I could not think but that a certain harmonious relation, both in theory and practice must exist between the modes of vibration in glass and porcelain, &;c. I suspected some fallacy in the theory, which sought to explain the production of the two notes D and E above referred to. I, therefore, proceeded as follows : 118. I procured a circular block of wood, from the centre of which rose a short cylinder of the same material, two inches in length and one inch in diameter : the top of this cylinder was covered with soft leather, and a female screw passed down it. I then procured a thin wedgwood- ware evaporating dish with a flat bottom and a lip : — the dish was five inches in diameter, and about one inch deep. In the centre of the dish I drilled a hole, through which a thumb screw with a leather collar was passed, and so fixed the dish to the top of the wooden cylinder. In this way the dish was quite firm and secure, and vibration produced no jarring or unsteadiness, and being held in the centre, the tones of the vessel were not damped. 119. Matters being thus arranged, I vibrated the vessel at four equidistant points of the rim by means of a bow, and obtained E within the stave, and at four other points midway between, I obtained the third below, namely, C. This note C was produced at the lip, at the point opposite. and Obsei'vations on Visible Vibration. 421 and at the two points midway between. I then poured coloured water into the dish, which reduced the notes to B flat and D sharp : each of the notes produced four fans, thus distinctly indicating a quadripartite division in each case, and presenting the apparent anomaly of two funda- mental notes from the same vessel. 120. Analogy led me to suppose, that the secondary tones would be doubled also ; that is, that I should get two secondary tones due to sex-nodal division, each producing six fans on the surface of the water ; two secondary tones due to octo-nodal division, each producing eight fans, and so on. I was not long in producing the first secondary tone, which was D sharp in the second octave producing six fans, and I also obtained another note G in the third octave also producing six fans; thus, offering another apparent anomaly of two first secondary tones. The D sharp was produced at six equidistant points on the rim of the basin including the lip, and the G was produced at six other points midway between, and which did not include the lip. I was not able to produce more than one octo- nodal tone, the vessel not being sufficiently elastic, and the lower notes tending to prevail. 121. I then procured another wedgwood-ware basin, and mounted it in a manner similar to the last. The dimensions of this basin were larger, its diameter being 6J inches, and depth IJ inch. When empty, this vessel at four points of the rim gave F, and at the other four points B flat, both within the octave, shewing an interval of a fifth. It also yielded two secondary tones, E and G, in the first octave, thus shewing an interval of a third. Contain- ing water, the two fundamental notes gave four fans each ; and the two first secondary tones six fans each, and thus the agreement with the former wedgwood-ware basin was complete. 122. I have submitted to experiment a great number of tea cups, both of china and earthenware, and also common blue cylindrical half pint cups, &c., and have always obtained from each two fundamental notes, the interval between which, has varied from a second to a fifth, and where I have been able to get secondary tones of the first kind due to sex-nodal division, I have always obtained two. 422 Mr. Charles Tomlmsans Experiments the interval between which has been a second or a third ; but with small vessels it is difficult to obtain secondary tones. 123. The explanation of the above phenomena, where vessels with lips and handles had been employed, appeared very easy; but if the same phenomena were producible from vessels of china-ware, &c., without lips or handles, such as saucers, basins, plates, &:c.y then the theory would be very obscure. I, therefore, vibrated a variety of such vessels as were not furnished with lips or handles, and in no case produced more than one fundamental note, and one secondary tone of each kind ; that is, I could procure the first and second secondary tones, but neither these latter nor the fundamental were ever doubled.* In these cases every thing agreed with my past experience, and the views before detailed (99), which I then stated, I believed would apply to vessels of porcelain and crockery ware, as well as of metal. 124. The cause, then, of the production of two funda- mental notes, and of two secondary tones of the same kind from the same vessel, is to be found in the lip or handle, and a reference to the two following figures will at once explain the whole cause. Fig.l. Fig. 2. * I have examined basins of many kinds, where the rims are plain, and where they describe waving lines ; also basins where the rim is turned down, and pre- sents a horizontal surface, as a wash-hand basin, and in none of these cases was the notes of each kind double. and Observations on Visible Vibration. 423 Whenever a note is produced, where the centres of vibra- tion include the lip or handle, the lower fundamental note will be produced, as in Figure 1 ; but where the centres of vibration do not include the lip or handle, then the upper fundamental note will be produced, as in Figure 2. The difference between these two cases is, that in Figure 1, where a centre of vibration is in the lip, the velocities of the vibrations of the vessel are diminished, the lip clogging the whole vessel : the result is, therefore, a lower note than in Figure 2, where the lip occupies the place of a node, and the four vibrating arcs being scarcely impeded by the lip, the result is a higher tone. A similar explana- tion applies to the production of the two secondary tones of the first kind, except that, with the lower note of the two, one-sixth part of the vessel is damped by the lip or handle instead of one-fourth, as in the former case. A vessel with both a lip and a handle does not alter the result, double fundamental notes and secondary tones being pro- duced. If a common blue cylindrical cup with a handle be employed, my theory can be proved in an interesting manner. Such a cup will yield two fundamental notes with an interval of about a third between them ; but if the handle be struck off, the lower fundamental note ascends nearly, and in some cases, quite to the upper, and the two first secondary tones merge into one. It is necessary that the handle be removed carefully : — a small saw moistened with turpen- tine effects the purpose best, and the part where the handle was affixed must be filed down smoothly, and on a level with the exterior surface of the cup. In one case, where this amputation was nicely performed, an interval of a fifth between the two fundamental notes of the cup with a handle, was reduced to unison when that appendage was removed, the upper note of the two, of course, always being the one fundamental note remaining. 125. Supposing this explanation to be correct, I saw no reason why, a priori^ vessels of glass, provided they were lipped or furnished with handles, should not yield similar results. In this supposition I was not disappointed, for, on vibrating a small lipped chemical test glass 1^ of an inch in diameter containing coloured water, I got two fundamental notes, each producing four fans. One note 424 Mr. Charles Tomlinsons ExjpeHments was C sharp in the second octave, and the other D in the third octave ; and although, this result obtained with a variety of small lipped glasses, and only an interval of half a tone was obtained, yet this interval was decided, and tended to confirm the theory of these curious pheno- mena. On extending the inquiry to large glass vessels with lips or handles, I obtained intervals varying from a second to a fifth between the two fundamental tones, and thus, the agreement between vessels of glass, and of earthenware, &;c., was complete. 126. Another result was interesting. A wedgwood- ware funnel, fluted on the inside, gave two tones with an interval of not quite half a tone between each. This funnel had neither lip nor handle, and the results obtained from it appeared at first to contradict the explanation before given; whereas, they confirm it: — thus, it often happens, that an apparent exception to a rule, if viewed in a proper light, becomes as strong a confirmation of its truth as a direct experiment does, and in this case, the ribs or flutes of the funnel being so many bulgings which in- crease the thickness of the funnel at those parts, act in a similar manner to lips and handles in the other vessels. When the funnel contained water four fans were produced on its surface from each note, and the lower note was pro- duced when the bow was applied to a point of the rim of the funnel immediately above a rib or flute ; the upper note was produced when the bow was applied at a point of the rim between two ribs. Another funnel not ribbed, but containing on the exterior near the rim a thick ornament for the maker's name, afforded similar results ; this orna- ment performing the part of the handle or lip in other vessels. 127. The wedgwood-ware basins above referred to, have each yielded one second secondary tone due to an octo- partite division of the vessel ; but in consequence of their high pitch, I could not determine their value. In each case, the eight fans jvere well marked, and on applying the bow between two fans with a view to elicit a different note also due to octo-nodal division, the four lower notes always so prevailed, that I could only with difficulty get one second secondary tone. and Observations on Visible Vibration. 426 128. Thus far I had proceeded with vessels with lips and handles, when it occurred to me, that the very same pheno- mena could be produced from glass goblets, provided one portion of the rim of these vessels were damped. I, there- fore, procured a damper (made of steel), which was screwed firmly upon the upper part of the glass goblet, pressing both surfaces, and the points of contact were covered with leather. Upon vibrating the glass containing coloured water, I obtained two fundamental notes : — two secondary tones of the first kind, and two secondary tones of the second kind. Thus, the analogy with the lipped vessels was complete. I need only describe here the production of the two funda- mental notes. If we take the whole rim of the glass, and call that part to which the damper is fixed zero, the bow applied at 90°, 180°, and 270°, produces a note about a fifth lower than the fundamental note of the glass without the damper, because in this case, the damper is on a centre of vibration. But if the bow be applied at 45°, 135°, 225°, and 315°, the fundamental note of the glass is unchanged, because the damper in such case, occupies the place of a node. When two or more dampers are employed, interesting results are obtained, which will be stated hereafter, as they do not belong to the immediate subject of this paper. 129. A disk of glass 12 inches in diameter, and fixed in its centre in a horizontal position had a damper screwed to its edge. The surface of the plate was covered with a layer of water, w^hich latter was retained on the disk by means of a ridge of bees' wax passed round the disk a little within its circumference.* This disk afforded two funda- mental notes, and double secondary tones of the first and second kinds. The results, then, as obtained from a glass goblet with a damper, and a glass disk similarly furnished are precisely the same, as when vessels with lips and handles are employed. 130. From what has been already stated, it will be seen that it is easy to determine, previous to experiment, the exact points on the periphery of a lipped vessel, or on a * In this way a disk of glass exhibits most of the phenomena of a goblet con- taining water. Indeed, the disk may be^considered as a very shallow glass vessel. 426 Mr. Charles Tomlinsons Expei'iments vessel with a handle, as well as on a glass goblet or disk furnished with a damper, where the lower fundamental tone can be produced, and where the upper. Thus, suppose a cylindrical china cup with a handle be chosen. The vessel may be about half filled with coloured water, and the point of the rim exactly opposite to the handle, and at 90°, on each side of the handle will yield the lower funda- mental tone, and four fans will be seen upon the surface of the water, the fan which proceeds from the quadrant which contains the handle being smaller in size, and more feeble in action than the other three fans. At the two points 45° on each side of the handle, and at two other points 45° on each side of the point diametrically opposite to the handle, the upper fundamental tone is produced, the handle and the three points, whence the lower fundamental tone was ob- tained, now forming the nodes in the upper fundamental tone, when it will be observed, that the four fans are all equal, because there are four vibrating arcs in action un- impeded by lip or handle ; whereas, with the lower funda- mental tone unimpeded action pertains to three only of the vibrating arcs, the fourth containing the lip or handle. With the same vessel two secondary tones of the first kind may be produced. Each one of these divides the vessel into six vibrating sectors. To produce the lower secondary tone, the handle must, as before, be included in a vibrating sector, and from the handle a radius of the circle described by the rim of the cup will divide the peri- phery into six equal parts, so that if one leg of a pair of compasses rest on the point at the handle, and the space between the two legs be equal to a radius, the second leg will extend to a centre of vibration, from which the lower secondary tone can be produced, and so on all round. The upper secondary tone due also to sex-nodal division will be found at the two points situate 30° on each side of the handle, and at four other points from these, the length of a radius being between any two points. 131. I have employed the term points in order to give a precision to my meaning, but it must not be understood literally, because as a vibrating sector always includes 90° for the fundamental tone in any circular vessel with a lip or a iiandle ; and 60° for the first secondary tone, the bow and Observations on Visible Vibration. 427 may include a range of so much, and produce the same note from any part of the sector ; but the centre of vibra- tion is always the centre of a sector, and the part to which the bow is applied, becomes, therefore, both a centre of vibration and the centre of a sector. It will, therefore, be seen, that, with vessels with lips or handles, the bow may be allowed considerable range, provided, that in producing the lower tones, the handle or lip be included in one of the vibrating arcs, and in producing the upper tones care must be taken that such be not the case. 132. In glass vessels, or, indeed, in vessels of any material, the extent of a vibrating arc can always be de- termined by a very simple rule : — Let the vessel contain water, and for any given note count the number of fans produced on the surface, and divide 360 by this number, and the quotient will give the extent of each vibrating arc. Thus, from a glass goblet, suppose a very acute note be produced, and 12 fans be seen upon the surface of the water proceeding from equidistant points of its inner cir- cumference ; 360 divided by 12 will give 30°, the extent of each vibrating arc producing a dodeca-nodal note. Salisbury, 2&f/i July, 1836. Article V. On Accidental Colours^ and Coloured Shadows. By Paul Cooper, Esq. The following remarks upon the paper of your correspon- dent, Mr. Tomlinson, published in your Numbers for September and October, are made chiefly with a view to promote the discussion of the interesting subjects to which he has directed our attention. The investigation of opinions thus introduced, appears to me, the likeliest method of arriving at truth ; and, as this is the common object, when the discussion is conducted with the good feeling which such an object is calculated to inspire, it must be indifferent to the parties on which side it is found. The point at issue seems to be, whether light produces a continued sensation of uniform intensity ; or, whether it gradually declines after the first impression, so as to render 428 Mr. P. Cooper on Accidental Colours, the eye less sensible to its influence, when long exposed to its action : for, if the latter be the case, the various pheno- mena of accidental colours are necessary consequences ; and, independently of the objection to the introduction of a new principle, which has not been traced to any other purpose, it would be contrary to the rules of philosophy to admit two unconnected causes to account for one effect. Mr. Tomlinson objects to a comparison between the functions of the eye and the palate, because the senses are fitted for such opposite uses ; (7) but, when the analogy is so general, and so complete, as in the present case, though it may not furnish conclusive evidence, it is entitled to some consideration. — ^Every person must have observed, that the most nauseous smell in a short time becomes less offensive ; and, that those who live in situations, which expose them to nuisances of this kind, soon become quite insensible to them. The same principle prevails with scents of a more agreeable character ; we are frequently delighted with the fragrance of a flower, but if we attempt to prolong the passing gratification, it quickly degenerates, and, if not intermitted, soon becomes insipid. — The sense of feeling is liable to the same gradual decay after the first impression ; the points of the fingers, which at first are very susceptible of its influence, soon cease to convey any sensation, unless the contact be intermitted, or otherwise renewed ; the blind, whose sense of touch is very delicate, when they endeavour to ascertain the qualities of bodies through this medium, may be observed to keep their fingers in constant motion. — The sense of hearing is also subject to decay ; and most persons will recollect instances in which sounds long continued have become almost, if not quite inaudible. — The sense of taste exhibits this principle in a striking manner ; and, from some few experiments which I have made on the subject, I think it probable, that the flavour of bodies, when their composition is not too complicated, may be analyzed by means of it, upon the same principle that we analyze compound light, by render- ing the palate insensible to the different ingredients of which it consists in succession : thus, strong tea sweetened, so that neither flavour may prevail, will alternately become sweet and astringent, if we render the palate insensible to and Coloured Shadows. 429 the opposite flavour, by means of strong tea without sugar in one case, and sugar without tea in the other, continued for a sufficient time to produce the effect. — Epicures have generally some acquaintance with this branch of philosophy, and they would be enabled to add to their gratifications by studying it further ; if we wish to make the most of our pleasures, discretion and moderation must regulate their enjoyment. It appears, then, that if the sight preserves an uniform state of intensity, it is an exception to a general law ; but, that this anomaly has no existence may be proved by the most direct evidence. I have noticed in a former paper, the very striking ex- periments of going from a strong to a weak light, with which all of us must be well acquainted ; the total insen- sibility of the eye, under these circumstances, proves more than is at present required of us ; we are now only called upon to shew, that the sensibility of the eye is lessened by the continued action of light of the same intensity. Much confusion has arisen among writers upon the subject of accidental colours, in consequence of their having made no distinction between pure red and the different shades of colour produced by a mixture of red and violet, which approach, more or less, to crimson, and, when diluted with white light, to pink : these mixtures produce accidental colours of the various shades of green, approaching the nearer to blue as the proportion of violet is less in the primary colour; whereas the red of the spectrum, when pure, constantly produces a blue accidental colour. — When red is diluted with white light, it forms the various shades of pale red, some of which are frequently mistaken for orange, and thus furnish another source of confusion. — There is also a want of distinction between the various shades of blue ; and, I mention it here, because it is probable, that it led to that part of the theory adopted by Mr. Tomlinson, which makes violet a compound of blue and red. —The blue which forms white light with red is the bright shade of this colour which adjoins the white central light, when the spectrum of the sun is received upon a screen placed at a short distance from the prism ; but, besides this blue, which is rather of a light colour, it 430 Mr, P. Cooper on Accidental Colours, is well known, that the different shades of dark blue and indigo, including all the colours formed by a mixture of the blue of the spectrum with various additional portions of yiolet, are also called blues ;* when, therefore, red is added to any of these colours, it converts the green, with the proper proportion of violet, to white ; leaving the superfluous portion of violet, if the red has been added in the proper proportion to neutralize the green, free from any other colour.f — If the red be added in too large a proportion, it gives to the violet a tinge of purple, and, if in too small a quantity, it leaves it a little inclined to blue. The experiment with which Mr. Tomlinson commences his paper, and which I sliall have occasion to repeat to shew the gradually diminishing sensibility of the eye, furnishes an instance of this want of distinction ; he says, that if we view a sheet of white paper through a disk of green glass, the sudden removal of the disk from the eye will cause the paper to assume a bright red appearance. Now, upon repeating this experiment, I find the accidental colour is pink, which, as it increases in intensity, approaches to crimson. If the glass be a blue green, the accidental colour will be nearer to a red, in the same proportion that the disk is nearer to a blue. I make this statement with the less reserve, because, in a subsequent experiment (22) Mr. Tomlinson has himself corrected the error. He says, " I have adopted a very useful mode of testing the true colour of the shadow, by receiving it first upon white paper, and then upon coloured paper; as, for example, boracic acid in alcohol yields a fine light green flame, the shade is pinlt on white ground, violet on blue ground, orange on yellow, &;c." — I could not * The accidental colours of these dark blues are various shades of orange, which rapproach the nearer to yellow as the blue approaches to violet. t I observe, that some of your pages have been lately occupied in giving a practical account of the art of dyeing ; it is a subject to which I some years since devoted considerable attention, both upon a large scale and experimentally, and I am convinced, that there is no theoretical principle of greater importance to the art, from which it removes many anomalous appearances, than the discovery of simple colours by the neutralization of one of the constituents of compound colours, in the manner mentioned here and in my former paper, (vol. ii. p. 113.) In adding ingredients during the process, to produce an exact shade of colour, a knowledge of this principle is absolutely necessary to insure success. and Coloured Shadows. .431 have given an experiment more completely in accordance with my theory ; the diminished sensibility of the eye to green light, renders the white ground pink (violet and red diluted with white); the blue ground (violet and green) violet ; and the yellow ground (red and green) orange, the eye not being wholly insensible to green light, which would be necessary to produce an accidental colour of pure red. But if blue and yellow are simple colours, from what source is the violet produced on the blue ground ; or the red, to form the orange on the yellow ground ? The accidental colour is always the complement of the colour to which the eye has been previously exposed, with reference to the ground upon which it is seen ; or, more definitely, the colour of the ground, minus the colour with which the eye is impressed, in the degree to which it has been rendered insensible to this colour. If we look at a sheet of white paper through a piece of green glass, in the manner Mr. Tomlinson has directed, (1) the paper appears upon the first impression to have a decidedly green tint ; but if we continue our view, this tint quickly declines in intensity, until, at length, it becomes gray with only a slight tinge of the colour of the glass. — If we suddenly remove the glass from the eye in the different stages of this experiment, we shall find that the intensity of the accidental colour will be inversely in pro- portion to the intensity of the primitive colour; if, for instance, we remove the glass after the first impression, the paper will appear white ; the following moment it will have a slight tint of pink, and this tint will increase, as the eye becomes more impressed, precisely in proportion to the decline of the primitive colour, until, under favour- able circumstances, it becomes crimson. Here, then, we have a direct proof, that the sensation produced by light declines immediately after the first im- impression ; but we have no reason to apprehend the evils which Mr. Tomlinson supposes must result from it ; (7) for the transition from one state to the other is made with such rapidity, that the motion of the eye from one colour to a difierent, adjoining colour, gives sufficient time for the recovery of its functions ; and even the short intermission caused by the motion of the eye lids, which is probably 432 Mr, P. Cooper on Accidental Colours, intended for the purpose, must be conducive to the same important object. If we can prove the existence of the arrangement, we may safely rely for its utility upon the wisdom and benevolence which made it part of the general scheme. I admit, however, that as philosophers it is our duty to trace the arrangement to its object. Mr. Tomlinson very properly objects to the want of com- prehensiveness in the different theories which have been advanced to account for accidental colours ; (27) and I fully agree with him, that no theory is entitled to our confidence that does not embrace the whole of the phenomena within its circuit ; but there may be a question, whether the fault is not in the application of the theory, rather than in the theory itself; and this is the question which I shall now endeavour to decide. If the prevailing colour of light disappears in the manner we have been led to infer from the preceding experiment, and which will be still more apparent, if, instead of looking at the white paper, we view the stronger light of the atmosphere through the same, or any other coloured glass, it is evident, that we can have no fixed standard for white light; the light, which, under different circumstances, we recognize as white, may be formed of the coloured rays in very different portions. That this is the case, we have abundant evidence ; the light of the sun, and the light of a lamp, or a candle have been proved, by numerous experiments, to be very different in colour, and, of course, to be composed of the coloured rays in different proportions ; yet, objects which appear white in one of these lights, are recognized as white in the other, and we only discover the difference by bringing them into contrast. — The method of doing this by suffering the light of the sun, reflected by the atmosphere, and the direct light of a candle, to fall upon different parts of the same white paper, is well known. — I lately observed a pleasing variety of this experiment : while holding a sheet of thin writing paper before a fire, the back of the paper being rather obscurely illuminated by the light from an opposite window, I observed the whole of the writing, which was black and turned towards the fire, appeared of a beautiful light blue. I readily discovered that the ink and Coloured Shadows. 433 had rendered the written part of the paper opaque, while the remainder of it transmitted the red light from the fire; of course, the former reflected the atmospheric light only, and the latter, together with this reflected light, trans- mitted the direct light from the fire ; the eye, turned to- wards the fire, had recognized its light, particularly with regard to the paper, as the standard for white, and, con- sequently, the reflected light of the sun produced the im- pression of blue ; as it would have done, if the eye had been prepared by looking through a piece of red glass. — Another variety of the experiment may be made, by ad- mitting the light of the moon, through a small aperture, into an apartment illuminated by a candle or a lamp; the light of the latter being the standard, the former, of course, will appear blue. If the light of the sun and the light of a candle, when reflected by an object usually considered white, give the impression of white light separately, we may readily sup- pose, that, when mixed together, they produce the same impression. In the first of the experiments we have just noticed, the white paper is illuminated with both the light of the sun and the light of the candle, and the reflexions from the mixed lights form the standard for white ; when, therefore, any part of the paper is seen illuminated with one of these lights only, it appears to be of the prevailing colour of this light compared with the mixed light ; thus, the light from the atmosphere appears blue, and the light from the candle red. The same explanation applies to all other cases of coloured shadows ; but to produce the full effect, it is necessary, that the intensity of the two lights should be nearly equal, and that they should fall upon the screen in such different directions, that the shadows of any opaque object, formed by the different lights, may be separated. — In the last of the experiments before noticed, the light of the moon was admitted by a small aperture, and, consequently, the light of the apartment, which formed the standard, was not per- ceptibly affected by it ; but, if the two lights had been brought to nearly an equal state of intensity, the mixed light would have formed the standard, and an opaque object, at a proper angle to tbeir different directions, would VOL. IV. 2 F 434 Mr, P, Cooper on Accidental Colours, have produced a red and a blue shadow, upon the principle already explained. But we may procure light of different shades, without having recourse to artificial means for its production ; the fact is, that the light which is reflected towards us in all directions is never uniform in colour, and it sometimes varies so much, particularly in the morning and the even- ing, as to produce very distinct shadows ; these shadows, when they are only two, are always complementary, because the standard for white is formed by the mixed sensations produced by their joint action. I have usually slept, during the last six months, in a room with a west aspect overlooking the sea, the window being considerably elevated ; and in the morning, I have uniformly observed, that the reflexion of the light of the rising sun, from the atmosphere, and from the water, pro- duced upon the white blind, which performed the part of a screen, two distinct shadows of the horizontal window bars ; the upper shadow being a pale blue, and the under shadow a faint red. — In this experiment, the standard for white is formed by the light which enters the window from both reflexions, and, as these reflexions form a large angle, the shadows produced by the window bars diverge rapidly, and fall upon the blind quite distinct ; that formed by intercepting the light reflected by the atmosphere being red, and that by intercepting the reflexion from the water blue. I have frequently observed the same appearance in the shadows formed by window bars, both vertical and hori- zontal, under other circumstances, particularly, when the light came directly from the atmosphere in one direction, and was reflected from an opposite building in the other. I shall mention only the following instance : — An apartment obscurely lighted by a single window, having a north aspect, receives its light in three different directions ; through an avenue of evergreens in a direct line, by re- flexion from the atmosphere from the right, and by reflexion from the yellow front of a building nearly opposite on the left; this mixed light produces the usual sensation of white, but the window bars, and all opaque objects within the apartment either form distinct shadows of violet. and Coloured Shadows. 436 yellow, and green, or, when the shadows are not separated, they are fringed with these colours : the green is obscure, but the yellow reflected from the opposite, and the com- plementary violet reflected by the Atmosphere are remark- ably distinct. The following experiment, which will lead to the ex- planation of another class of these phenomena, will throw further light upon the subject. If we look through the green glass with one eye, as before, and after observing the complementary colour upon the removal of the glass, open the other eye, we shall find, that the paper seen with both eyes approaches nearer to its proper colour, than when seen with the impressed eye only ; if we then close the impressed eye, and view the paper with the eye which was previously closed, we shall observe that its colour is a pale green ; and by opening and closing the different eyes in succession, it will b* discovered, that the alternations produce colours complementary to each other. In this experiment, the standard for white is formed by the mixed sensation pro- duced by the impressed and the unimpressed eye, as may be readily perceived by viewing the paper with both eyes open; and, of course, the paper is seen in complementary colours with reference to this standard. If we impress the eye, by looking through a crimson instead of a green glass, the effect will be reversed, and the accidental colour will be green. If, in this state of the eye, we hold a narrow strip of white paper vertically, about a foot from the eye, and fix both eyes upon an object at some distance beyond it, the impressed eye will see the paper of a pink colour, while to the other eye it will appear green. If the two images are made to overlap each other, the overlapping parts will appear white. This experiment, which varies only in form from that which precedes it, is similar to Mr. Smith's, as stated in Brewster's Optics, page 310, with only this difference, that in Mr. Smith's experiment, one of the eyes is strongly impressed by the light of a candle placed near it, from which the other eye is protected, instead of being impressed by the light trans- mitted by the crimson glass. It appears from this investigation, that these phenomena may be divided into three classes; in the first, the eye 2 F 2 436 Mr. P, Cooper on Accidental Colours, being impressed with the light by which it is surrounded, adopts it as the standard for white, and, consequently, sees light varying from it in the proportion of its different rays, of the colour of that ray which predominates, when compared with the standard to which it is referred. — In the second class, the standard is formed by the surrounding light as before ; but this light, being composed of light, the different parts of which are differently proportioned and differently directed, forms different shadows ; and these shadows must necessarily be complementary, because, when the lights, by which they are respectively formed, are mixed together, they form the light which is referred to as the standard. — In the third class, the standard is formed by the mixed sensation produced by the two eyes under the influence of different impressions, which are, therefore, complementary to each other, with reference to this standard. In the first class is included, in addition to some of those already mentioned, the experiment of M. Meusnier ; (21) the standard in this case, is formed by the light admitted through the curtain, which refuses transmission to light of certain colours ; the beam of the sun's light, therefore, which is admitted in its original state by a hole a quarter of an inch in diameter, must appear to an eye thus im- pressed, of the colour or colours which the curtain refuses to transmit. The azure colour of the atmosphere is also included in this class. The surrounding light, which forms the stan- dard, is deprived of part of its more refrangible rays, by being reflected from coloured objects in which the less refrangible colours prevail, as well as by the greater depth of atmosphere which it must traverse before it meets the eye, the red light being known to penetrate with greater facility than the other colours ; the direct light of the atmosphere, therefore, appears blue when compared with this reflected light, upon the same principle, that the beam of light, in the preceding experiment, appeared green. The second class includes the experiment, in which the light of the sun and the light of a candle fall upon different parts of the same white paper ; and also, the various and Coloured Shadows. 437 coloured shadows, whicli are complementary to each other, whether formed hy light different in colour, in the different directions in which it arrives, or rendered so by the coloured objects that reflect it within the apartment in which the shadows are seen. The third class is not often produced except by artificial means. The effect in the experiments belonging to this class, to which we have before referred, may be consider- ably heightened, by looking at the same time, with the dift'erent eyes, through two glasses complementary to each other, green and crimson, for instance ; the distinguishing- colours will quickly be followed by an uniform gray, more or less dark, as the glasses exclude more or less of the coloured rays; but upon removing the glasses, and looking at a white object alternately with the eyes thus differently impressed, the complementary colours will be very distinct: or a still greater effect may be produced, by quickly chang- ing the glasses after the eyes have been sufficiently im- pressed, when the gray will be converted to its vivid com- plementary colours ; which, however, will soon be lost in the uniform appearance they previously presented. Nothing can more clearly prove the gradually lessened sensibility of the eyes, when exposed to any prevailing colour, than these experiments. I shall now make a few remarks upon some other subjects adverted to in Mr. Tomlinson's paper ; but having already very far exceeded the limits I had prescribed to myself, I shall confine them to such points as are connected with the explanation of my own views. Mr. Tomlinson, in his first experiment, states, that if the green disk be instantly re-placed, after looking at its accidental colour upon a sheet of white paper, the eye will be unable to distinguish any thing for a second or two previously to the re-appearance of the green ; and he accounts for this, by supposing that the super-position of the three primitive colours produce black. I have never been able to observe this interval of dark- ness, although I have been led to expect it upon theoretical principles. When the eye is impressed with green, so as to be rendered insensible to this colour, and then turns to a white surface, its sees only the colours reflected by it, 438 Mr. P. Cooper on Accidental Colours, which are complementary to green, viz., violet and red; the crimson image, then, formed by these colours, is as much an original or primary image, as the image formed by the green light transmitted by the glass, and, therefore, if this image be of sufficient intensity, it ought to produce in the eye a lessened sensibility to the colours by which it is formed; but the eye was previously insensible to the complementary colour, green, and, consequently, when the glass is instantly re-placed, the eye, under the influence of both impressions, insensible to the three colours, or to the whole of the light reflected by the white paper. This brings us to an explanation of the experiment of M. Plateau; [6]^ which is introduced by the rather para- doxical statement, that while two real complementary colours produce, together, white, two accidental comple- mentary colours produce, together, black. — In this experi- ment the eyes, by viewing the complementary colours in succession in the manner he has directed, become insensible to both these colours, which, together, constitute white light, when it is presented to them in the weak state to which it must be reduced in penetrating to the eyes closed and covered ; and it produces a black accidental image, precisely as it would have done if the colours had been viewed together upon a white surface. The complementary colours are seen on the right and left of the black image, because these parts of the eyes have been exposed during the progress of the experiment to one colour only. I have discovered only one difficulty in the theory which I have been endeavouring to support, and that difficulty is found in the present experiment. When the light is ex- cluded from the eyes in the manner described by M. Plateau, it appears difficult to conceive, that it can be present to form the accidental colours which he afterwards observed ; but the following experiment will at least render it probable, that by some means, which we cannot explain, it still penetrates to the eyes, though in a state of very low intensity. If, after looking at a coloured surface, we close the eyes, we see the complementary colour of the previous impression : if we then pass the hand before the eyes, so as to intercept the light which falls upon the eye lids, the • Records of General Science, vol. ii. p. 282. and Coloured Shadows, 439 colour disappears while the hand is before the eyes, and re-appears when it has passed beyond them, and this may be repeated several times ; but if we suffer the hand, or any other object which intercepts the light, to remain for some time before the eyes, the accidental colours will re- appear after a short interval, though much lessened in brilliancy and distinctness. Now, with such evidence before us, that in every other instance the accidental image is dependent upon the light which has access to the eyes, and that in many cases it is modified by the character of this light ; and this evidence being brought up to the very point at which the difficulty occurs, it would, in my opinion, be contrary to the rules of sound philosophy to introduce any other cause to account for it ; particularly in our present state of un- certainty with regard to the ultimate destination of the light which disappears when it is intercepted by opaque bodies. M. Plateau's theory appears to be founded entirely upon this single fact. [2] The hypothesis by which he endeavours to explain it, that the retina spontaneously assumes an opposite state after the cessation of direct impressions, [3] has no other support ; and the numerous experiments in which the accidental image is modified in colour by the colour of the surface upon which it is formed are so decidedly opposed to it, that it appears to me to be quite untenable. He states, " that the accidental colours of impressions destroy direct corresponding impressions ;" [5] and in the experiment which is brought forward to support it, con- cludes that the direct impression of a small piece of red paper, upon a black ground, is destroyed when. the eye is directed to a larger piece of paper of the same colour, by the accidental impressions, green. According to our theory, no accidental green image can be formed upon a surface where the only colour present is red : but the part of the eye impressed with the small piece of paper of the same colour, being in a great measure insensible to red light, the image of the paper will appear somewhat black, when seen in contrast with the surrounding paper of the same 440 Mr. P. Coopei' on Accidental Colours, colour, which falls upon a part of the eye, not previously brought into action.* Mr. Tomlinson, in order to establish his hypothesis that the superposition of complementary colours produce black, appears to have fallen into a similar mistake. He. says, ** if we view red lead through a disk of green glass, the red powder will appear as black as lamp black. "(28) But in this experiment, the only colour reflected by the powder is red, and this colour the green glass refuses to transmit ; so, that instead of a superposition of complementary colours, it is the absence of light of all colours which produces black.* If accidental colours are produced by rays reflected by the surface upon which they are seen, the images formed by these colours are to all intents and purposes as com- pletely primary as the images which arise from the colours that produce the first impressions ; and, as we have already observed, if they are of suflRcient intensity, and their action upon the eye be continued for a sufl^icient time, they ought to produce accidental colours complementary to the colours of the images by which they are formed, and, therefore, corresponding with the original impressions. This view of the subject is illustrated and supported by the experiments of Newton, Aepinus, Brewster, and others; in which they impressed the eye with the image of the sun, and then, by directing it to a white ground, produced an accidental spectrum, which was invariably surrounded with a border, the colour of which was generally complementary to the centre. t I have observed in a former paper, that when we look at any object with a view to impress its im^ige upon the retina, with whatever determination it may be opposed, there is an involuntary motion of the eye. apparently of vibratory character, which brings a part of the retina surrounding the image into the alternate directions in which it sees the * These explanations must be modified, if we take into consideration, the white light wliich usually accompanies the prevailing colour reflected by coloured sur- faces ; but this would not effect the general principle. t It may be remarked, that these complementary colours, as observed by Sir David Brewster, and given in his Optics, p. 308, exactly correspond with our fheory of primitive colours. and Coloured Shadows. 441 edge of the object and a narrow border of the ground upon which it is placed, in succession. These alternations in the direction of the eye produce the accidental colour which appears to play about the edge of the object, and, also, by the intermissions which they occasion, preserve the colour of this part of it from being impaired. If, for instance, the eye be directed to a red seal upon white paper, after a little time there will be observed a faint blue border surrounding the seal, which will increase in inten- sity as the colour of the seal declines ; and the edge of the seal to a depth nearly corresponding with the breadth of the blue border, will be found to preserve its original strength of colour. When the eye is impressed with any moderately illumi- nated object, such as the seal in the last experiment, the complementary colour surrounding it, which is seen upon the white ground, is not of sufficient intensity to produce a corresponding accidental colour, and the image formed by directing the eye to a different part of the ground is not surrounded with any border; but when the eye is im- pressed with the strong light of the sun, the accidental colour, formed at the same time upon the edges of its image by the white surrounding atmosphere, corresponds in intensity with the original impression, and the accidental colours of both are seen together. There is an interesting paper on Coloured Shadows, by Count Rumford, published in the Philosophical Transactions for 1794, and also in the 1st volume, quarto series, of Nichol- son's Journal ; and a memoir on the same subject, by Citizen Hassenfratz, published in the Journal de L'Eole Polytechnique, tom. iv.; and a translation of it in the 6th and 7th volumes, octavo series, of Nicholson's Journal. This paper was written when I had no opportunity of consulting these works; but, upon since referring to them, I do not find it necessary to make any alteration. In one of Count Rumford 's experiments, he prepared two Argand lamps, and by intercepting their light at a proper angle, by means of a flat ruler, he procured two broad shadows which were projected upon white paper and found to be perfectly colourless. He then directed a tube about twelve inches long, and an inch in diameter, lined 442 Mr. P. Cooper on Accidental Colours, with black paper, against the centre of one of the broad shadows, while an assistant repeatedly interposed a sheet of yellow glass before the lamp whose light corresponded to the shadow he was looking at through the tube; when, ** so far from being able to observe any change in the shadow upon which his eye was fixed, he was not able even to tell when the yellow glass was before the lamp, and when it was not ; and though the assistant, often exclaimed at the striking brilliancy and beauty of the blue colour of the very shadow he was observing, he could not discover in it, the least appearance of any colour at all. But, as soon as he removed his eye from the tube, and contem- plated the shadow with all its neighbouring accompani- ments, the other shadow rendered really yellow by the effect of the yellow glass, and the white paper, which had likewise from the same cause acquired a yellowish hue, the shadow in question appeared to him, as it did to his assis- tant, of a beautiful blue colour." The standard to which both shadows are referred in this experiment, is the mixed light from both lamps, one coloured and the other white. M. Hassenfratz discovered by numerous experiments, that the light reflected by the atmosphere, and the direct light of the sun is always different in colour ; and that the shadows produced by the separation of these two kinds of light, vary with the state of the atmosphere, the latitude of the place, the season of the year, and the hour of the day. He noticed that in coloured rooms, *' when several lights direct or reflected concur with the light of the atmo- sphere to enlighten the plane on which the shadow is observed," the number of shadows is almost always two or three, sometimes four or five, and it has even happened, that six were distinguished. There are some interesting experiments in this memoir, on the colours of the shadows produced by the separation of two lights procured from different sources, when com- pared with each other ; from which it appears, that the light reflected by the atmosphere is blue, when compared with all artificial lights ; and that the light from hydrogen or other combustibles in which it abounds, is blue, com- pared with those in which there is a larger proportion of carbon. In all these experiments, the shadows are com- and Coloured Shadows. 443 plementary, generally different shades of blue and red, and in every instance, strictly in accordance with our theory, as it relates to the primary colours. Mr. T. Smith, in a note added to the paper in which the experiment we have already noticed is described, (London and Edinburgh Philosophical Magazine, vol. i. p. 255.) has given some experiments with coloured tubes, which nearly correspond with those of Mr. Tomlinson ; these experi- ments shew the facility with which the eye may be im- pressed, of which the proofs are very numerous. One of the most delicate tests of this with which I am acquainted, is produced by looking for an instant at a white surface through a coloured glass with one eye only, then at the same surface, but without the glass, with both eyes, and afterwards with the eyes alternately ; when the comple- mentary colours will be seen, in a slight degree, although they arise from an impression made almost instantaneously. Perhaps, an improvement upon this might be made, by looking with both eyes, after the impression has been made upon one of them, at a strip of white paper held at the dis- tance of about a foot, the eyes being directed to a distant object; when the overlapping parts of the complementary colours would exhibit the standard, while one of these colours would be seen at the same time on each side of it. I have confined myself in this paper to the generalization of known facts: at some future time, it is my intention to proceed a step farther, by shewing the connexion of these facts with others which have been traced to general prin- ciples; but at present, this paper is too long to admit of the extension which it would require, and there will be less danger of its being considered hypothetical, when my theory of light has been more fully explained. It would be found, however, that light whatever may he the circum- stances attending it, is transmitted upon the most general and invariable principles.* P. Cooper. Bowlish, November 7th, 1836. (To the Editor of the Records of General Science.) * See Abstract, paragraph 28. 444 Notice of some Recent Article VI. Notice of some Recent Improvements in Science. ELECTRICITY. Electricity hy Contact.— M, Karsten, in a letter of 150 pages addressed to Humboldt, has discussed this subject. The paper has excited much attention in Germany, but it contains few new facts, and many speculations. -His conclu- sions are, 1st. The metals, and perhaps, all solid bodies become positive when plunged into a liquid ; the latter becomes negative. 2nd. When the body is not wholly im- mersed, its two ends take opposite electrical states. 3rd. Solid bodies differ much in regard to their electro-motive force with the same liquid, and it is in this difference that the electrical activity both chemical and magnetic of the pile depends. 4th. When two electromotors of different forces are plunged into the same liquid without being in contact, the feeblest takes the opposite electricity to that of the strongest, and becomes consequently negative. 5th The feeblest part of the solid electromotor, placed out of the liquid, possesses equally the opposite electricity to that of the part immersed. 6th. The electromotive energy of a liquid depends on its power of acquiring by the presence of two dissimilar solid electromotors, a state, by virtue of which, it yields more or less readily electricities opposite to the same electromotors. All bad conducting liquids possess in general this property, but it belongs neither to perfectly isolating liquids, (such as oils, &;c.,) nor to very good conducting liquids, (such as mercury and liquid metals.) The electro-motive energy of a liquid, does not, however, depend only on its conducting power, but also apparently on several other conditions not yet properly known. 7th. The electro-motive effects of two metals forming with a liquid, a closed circuit, result from the dis- engagement and re-combination of opjoosite electricities in the liquid. These effects are excited by the electro-motive relation of the two unequal electromotors to the liquid ; they are favoured by the electro-motive relation of the strongest electromotor to the weakest, and are accelerated by the immediate contact of the two electromotors, accord- Improvements in Science. 445 ing as they are good conductors of electricity. 8th. The che- mical changes in the pile are certainly allied to the re- combination by means of the solid bodies in the pile of the electricities set free, but there does not exist between these phenomena any dependence as cause and effect. 9th. In a re-union of the elementary piles (pile of Volta) the opposite electricities are completely neutralized, by the solid bodies of each element, and there is no transmission of electricity from one element to the other.* 2. Action of nitric acid on the oxidizahle metals. — This curious subject has been well illustrated by the experiments of Herschel and Schonbein, as well as by those of Keir, Wetzlar, Fischer, Fechner, and Faraday. The deduction from their researches is, that iron wire is often exhibited under certain circumstances, as a metal easily acted on by acids, and that sometimes on the contrary, in consequence of slight modifications of the experiment, it resists oxida- tion with the greatest obstinacy. Schonbein accounts for this curious fact, by supposing, that a peculiar action is induced by which the natural affinity of the metal is altered, while Mr Faraday ascribes the cessation of action to the presence of a thin layer of oxide, which, however, is not perceptible to the eye. M. Mousson not satisfied with these explanations, considers the following more satisfac- tory : 1 . It is not necessary in order to explain the pheno- mena of the action and passiveness of iron to have recourse to a new hypothesis. 2. That the phenomena in different metals only differ in degree, not in the nature of the action. 3. That they depend essentially on the incapacity of con- centrated nitrous acid to attack several metals, (perhaps even any) and of the double mode of decomposition of which it is susceptible. 4. That the commencement of the state of passiveness is always accompanied with an oxida- tion and corresponding current. 5. That the same current, according to its action on the acids, according as it favours or prevents the formation, and close contact of a layer of nitrous acid produces electro-chemical changes which the metals present in the same nitric acid.f 3. Negative more readily dissipated in the air than jwsitive electricity. — Professor Belli has made several interesting * Bibliotbeque Uuiverselle, September, 1036. p. 165. t lb. \bi. 446 Notice of some Recent experiments which go to prove this position. Having placed an electrometer upon an isolated horizontal con- ductor, he found by a mean of 3 trials, that after having electrified the conductor with positive electricity, the electrometer took 10 minutes and 2 seconds to descend from 20° to 10°. With negative electricity, the electro- meter only required 4 minutes and 30 seconds to pass over the same number of degrees, under precisely the same cir- cumstances. He infers, that the force generally less which negative electricity furnished by a machine possesses, com- pared to that of the positive electricity which the same machine furnishes, does not depend alone on the less ad- vantageous disposition of the conductors destined to collect the first electricity, but also on the more ready loss which it sustains."*^ Electric spark obtained from the Torpedo. — The attempts which Dr. Davy made to obtain a spark from the torpedo were not attended with success {Records, vol. i. 306.) M. Matteucci has, however, been fortunately successful in his trials. He employed for this purpose an apparatus perfectly similar to that employed by Mr. Faraday for obtaining a spark by means of a single voltaic pair. The principle object of this arrangement is to prevent the electricities from being neutralized directly by the medium of the conducting body which developes them, and of forcing them to unite ex- teriorly across the thin layer of air where the spark is pro- duced. Matteucci has also succeeded in magnetizing steel needles in the same manner."^ In a letter from Matteucci, read by Donne before the Institute, we learn that an elec- trical discharge may be obtained from the torpedo, although the skin of the organ be removed, and, even when portions of the substance of the electrical apparatus have been cut away. When the torpedo does not discharge electricity, it is impossible to obtain, even in the interior of the organ, the least trace of electricity in any point whatever, either with the galvanometer or condenser. The intensity of the shock is reduced by diminishing the number of nervous filaments which go to the organ. In the act of discharging, the electrical current always passes from the back to the belly. Three grains of muriate of morphin introduced * JJibliotheque Universelle, June, 1836. Improvements in Science. 447 fnto the stomach of a torpedo killed it in ten minutes ; its death is accompanied with stronger shocks than usual, and with convulsions. When the torpedo has ceased to give electrical shocks, even when irritated, if we lay bare the brain, and touch gently the posterior lobe of the brain which gives nerves to the electrical organ, stronger shocks than usual (3 or 4) are produced, but having the same direction from the back to the belly. If, in place of simply touching the surface of the brain, it is wounded without taking the same precaution, then very strong shocks are renewed, but without having the same constancy in the direction of the current. These facts, and especially the latter, are sufficient to shew, Matteucci thinks, that the electricity of the torpedo is not produced in the organs situated on each side of the animal ; that the current receives its direction from the brain, and that in the electrical apparatus, the electricity is only condensed as in the Leyden jar. Developeinent of Electricity. — M. De La Rive has pub- lished some very elaborate memoirs, in which the question is discussed at great length. How is voltaic electricity developed ? He has drawn the following conclusions : — 1. That in his memoirs he has endeavoured to corroborate by new facts the deductions which he had formerly drawn relative to the necessity of a chemical action for the pro- duction of voltaic electricity, and the impossibility of developing electricity by simple contact. 2. The attention which he has paid to the effects of current, and the dyna- mical effects have led him to observe, that the quantity of electricity accumulated at the poles under the form of tension is greater in proportion as the two electrical prin- ciples have less facility in uniting through the pile itself, and as the pile contains a greater number of pairs. In the same manner, it is necessary for the dynamical effects, that the pile be little of a conductor, and contain, conse- quently, a sufficient number of pairs, in order that the two electrical principles may re-unite in greater proportion, by the medium of conductors placed between the poles than through the pile itself. 3. Having found that the quantity of free electricity disengaged in a given time from each pair of plates exercises no sensible influence on the tension of the poles of a pile, since this kind of effect is not instantaneous. 448 Notice of some Recent while it exercises a very great influence upon the intensity of the dynamical effects, and so much the stronger in pro- portion to the goodness of the conductors ; he has deduced some practical consequences applicable to a more advan- tageous construction of a voltaic pile in each particular case. 4. The examination which he has made of the influence of metallic diaphragms, placed either on the track of a current between the poles of a pile, or in the interior of a pile itself, has shewn that this influence is very different according to the nature of the conductors placed between the poles, and may be explained by a greater or less altera- tion in the conductibility of the homogeneous conductors in which the diaphragms are placed. 5. In endeavouring to appreciate in all its extent, the influence of a number of pairs, De La Rive has observed, that the number sometimes increases, sometimes diminishes the intensity of the effects of a pile, and that these variations depend on several circum- stances belonging, some to the pile, others to the nature of the conductors interposed between the piles. He infers from the study of these circumstances, that the phenoniena to which they give birth are a consequence of the chemical theory of the pile.* CHEMISTRY. Composition of atmospheric air . — M. T. de Saussure has taken advantage of the property which small shot pos- sesses of absorbing oxygen when moistened and agitated with atmospheric air at common temperatures, to analyze common air. He employed a matrass possessing a capacity of from 150 to 250 centi-metres cubes closed hermetically with a metallic stopper, which is fastened with screws to a firm socket at the end of the neck of the matrass. The lead shot ought to contain 80 to 100 shots to the gramme, (15*438 grs.) Its weight is nearly the fifth of that of the water which the matrass contains. The water for moisten- ing the shot should be equal to the seventeenth of its weight. A larger or smaller quantity retards the oxida- tion. Three hours of constant agitation are sufficient to deprive the air of its oxygen. Saussure measures the quan- tity of oxygen absorbed by the weight of the water which * Ann. de Chim. Ixii. 206. Improvements in Science. 443 the atmospheric pressure causes to enter the flask. He affirms, that the lead takes up all the oxygen from the air which undergoes a diminution of volume of 21-05; but as lead absorbs carbonic acid also, amounting, in his experi- ments, to -0004 ; it follows, that the quantity of oxygen in the atmosphere is 21*01 per cent. Gay Lussac has suggested another eudiometer, viz., a plate of copper moistened with sulphuric, muriatic or acetic acids.* Molecular composition of bodies. — Persoz, in a paper read before the Institute, has come to the following conclusions on this subject, 1. Chemical atoms are only molecular groups, the relative value of which is expressed by the atomic weight. 2. These groups are all divisible by a constant number (70), which expresses the volume of vapour, that the atomic weight of a body furnishes. 3. If we multiply this number (70) by a factor corresponding to the volumes of a molecular group, and take the product as the divisor of the relative weight of this group, the quotient will be the weight of a litre of the vapour, by means of which we may deduce at pleasure (taking into account only the molecular change which supervenes in its passage from the solid to the gaseous state) the density of a body compared to that of air or water. 4. The density being intimately connected with the relative weight of the atoms, we can, by means of the specific gravity of a body, verify the analytical results obtained by chemists. 5. By a knowledge of the density, we may establish the molecular composition of bodies, and distinguish that of certain gases with the composition of the molecular groups which produces them. This would lead to the knowledge of the laws of the dilitation of gases. We are glad to find, that important views like these, which, in many respects, are just those advocated in the pages of this Journal, and previously in the " First Prin- ciples," are beginning to attract attention in France.-f- Solubility of some Carbonates, ^c. in Sal Ammoniac. — According to Vogel, carbonate of lime, when newly pre- cipitated, Iceland spar, white marble, carbonates of barytes and strontian, precipitated from these solutions, and also witherite are all soluble in sal ammoniac. Hence, a sub- • Ann. de Cbim. Ixii. 219. t L'Institut, 181. VOL. IV. 2 G 444 Notice of some Recent stance must not be considered carbonate of magnesia as is usually done, because it is soluble in this salt. The solu- tion of these earthy salts may perhaps be attributed to their decomposition, by the formation of carbonate of ammonia and earthy muriates.* Action of Anhydrous Sulphuric Acid on Metallic Chlorides. — When the vapour of this acid, either with or without water, is brought in contact with common salt at an elevated temperature, the sodium is oxidized by the sul- phuric acid, while chlorine with sulphurous acid gas is disengaged. The result, according to Rose, is different when the chloride is finely pulverized, and placed in a vessel surrounded with a freezing mixture. The vapour of the acid is then rapidly absorbed without decomposing it. The whole is transformed into a transparent mass, which is a compound of chloride of sodium and anhydrous sulphuric acid. When heated, it decomposes, being re- solved into sulphate of soda, while chlorine and sulphurous acid are disengaged. Chloride of potassium, muriate of ammonia act in the same way ; but the chloride of copper and barium in the anhydrous state do not. The same acid unites with the nitrate and sulphate of potash, and with sulphate of ammonia, all of them anhydrous salts.f Decomposition of Copper Salts by Phosphorus. — Accord- ing to Vogel, when a stick of phosphorus is kept in a solution of sulphate of copper, the liquid gradually loses its blue colour and become colourless. In this state, the solution does not contain even a trace of copper. On evaporating the fluid, and heating the residue strongly, sulphuric acid flies off, and phosphoric acid remains. The phosphorus which is covered with a metallic coating of copper becomes partly black in the space of a short time. Below these leaves of copper, there is observed, on the surface of the copper, another thin layer in plates of a black colour without metallic lustre easily detached from the phosphorus and very fragile. It possesses the properties of phosphate of copper. In a solution of nitrate of copper the same phenomena occur. The green solution of chloride of copper becomes at first black when phosphorus is placed in it, and then nearly colourless in a concentrated * Journ. flir prak Chim. vii. 453. t Journ. de Cliim. Med. Oct., 522. Improvements in Science. 445 solution ; quite colourless in a dilute solution, the copper being wholly thrown down. A solution of acetate of copper becomes pale coloured, and gradually becomes a whitish powder by the action of phosphorus. This powder is phosphate of copper, which is not re-dissolved by the free acetic acid.''^ Reduction of Mercurial Salts by Copper. — If we plunge a plate of polished copper into an aqueous solution of corro- sive sublimate, the copper becomes blackish gray, the solution milky, and shortly afterwards a white powder is deposited, which is sub-chloride of mercury, or calomel mixed with some globules of mercury. This was observed by Fischer of Breslaw. But Vogel has since noticed, that the copper plate, instead of presenting a silvery appearance, is covered with a black layer destitute of all metallic lustre. He left a plate of copper for 24 hours in a concentrated solution of corrosive sublimate ; the liquid had become green, and a quantity of calomel had been formed which rendered the liquid milky; the greater part was, however, deposited at the bottom of the vessel. The surface of the copper was covered with a very thin black coating, and with small globules of mercury which did not adhere, but fell on the slightest touch. The plate of copper was washed with water and dried. The black layer adhered so strongly to the copper, that it was difficult to remove it by friction with paper. This black matter dissolved in muriatic acid without effervescence, and the liquid decanted from the copper contained deuto-chloride of copper, in which some flocks of calomel were observed to swim. The copper, after digestion in the acid, was white, and acquired the lustre of mercury by friction. Solutions of sublimate in alcohol and ether, act upon copper in the same way. Calomel, though almost insoluble in water, may be de- composed by copper. If, when suspended in water, a plate of copper be immersed in the liquid, copper soon begins to be dissolved, and the plate becomes black. The decom- position of calomel is still more rapid, if the water in which it is suspended be kept in a boiling state. The copper is soon covered with a black coating, beneath which there is a metallic layer. • Phann. Central blatt, Oct., 18S6, p. 628. 2 G 2 446 Notice of some Recent It, therefore, appears that the action of copper upon the chlorides is different from that upon the nitrates of mercury. In the latter case, the mercury is reduced and deposited on the copper plate.'^ Solubility of Oxide of Lead in Water. — According to Bonsdorff, the oxide of lead when prepared either by the wet way, viz., the action of water containing air upon metallic lead, or by the dry way, from nitrate of lead, is completely soluble in water. One part of lead requires 7000 of water for solution, which is not so inconsiderable when we remember that 1 part of magnesia requires above 5000 parts of water to dissolve it. The solution of oxide of lead in water possesses a strong alkaline re-action, both on fernambuc and violets, and is an excellent test for carbonic acid.f New compounds of Platinum^ — The potash cyanuret of platinum of Gmelin, obtained by mixing together solu- tions of chloride of platinum and ferrocyanodide of potas- sium, evaporating and procuring long fine rhomboidal prisms, which are sometimes yellow and sometimes blue, according as they are viewed, and consisting of K Cy + Pt Cy + 3 Aq, forms with protonitrate of mercury a beautiful smalt blue precipitate. This powder may be washed with cold water, acidulated with nitric acid, and then dried without altering its colour, but if boiled with water it becomes quite white. If a solution of protonitrate of mer- cury be now poured on this bleached precipitate, and be allowed to remain in contact with it for several hours at the usual temperature, it becomes as beautiful as before. When heated on a platinum plate the coloured precipitate detonates, throwing out sparks and smoke. It dissolves in muriatic acid when heated, giving out nitrous and prussic acids. The colourless precipitate burns when heated with- out detonating, and leaves about 38 per cent, of spongy platinum. It dissolves in muriatic acid without disengage- ment of gas. The solution is precipitated by potash, and leaves a residue which decomposes into prussic acid, chloride of mercury, and cyanodide of platinum. When the white precipitate is heated in a small glass retort, it is resolved into cyanogen, running mercury, and cyanodide of platinum. • Pharm. Central blatt, Oct. 1836, p. 629. t lb. Au^. 1836, p. h^O. Improvements iu Science. 447 It consists of 48 cyanodide of platinum and 52 of cyanodide of mercury, or Pt Cy + Hg Cy. The Cyanodide of Platinum left by the decomposition of the hydrargyro cyanodide of platinum, is a beautiful olive coloured powder, insoluble in water, acids and alkalies ; combustible, leaving by combus- tion 79 per cent, of pure platinum ; giving with oxide of copper and heat, carbonic acid and azote, in the proportion of 2 to 1 volumes, and consequently composed of Pt Cy. If the hydrargyro-cyanuret of platinum diffused in water be treated with sulphuretted hydrogen, sulphuret of mercury is produced, and a colourless strongly acid liquid, which contains in solution a combination of cyanodide of platinum with hydrocyanic acid. If the water is driven off by evapo- ration, this new combination appears in the form of a greenish yellow substance, with the metallic lustre, pre- senting on its surface the colour of gold and copper, which deliquesces in the air ; is very soluble in water and absolute alcohol, and combines with the alkalies to form the double cyanurets of platinum. Dobefeiner, who is the discoverer of these facts, terms this substance hydroplatinocyanic acid. It consists of Pt Hg Cy^. When dissolved in absolute alcohol, and allowed to evaporate, peculiar crystals are ob- served, with a fine play of colours similar to the chameleon. If the dry acid is allowed to deliquesce in a moist atmos- phere, and then allowed to evaporate in dry air or in the solar light, extremely beautiful crystals are formed, grouped in the form of stars, with the metallic lustre, of sometimes a golden and sometimes a copper colour. This acid undergoes no change below 212° ; above this it is decomposed into prussic acid and cyanodide of platinum. If its solution in alcohol be mixed with a little nitric acid, a liquid is pro- duced, which when evaporated on a plate of glass and heated strongly, forms a very beautiful platinum mirror. There is also a hydriridiocyanic acid possessing similar pro- perties.* Analysis of iron ores. — Berzelius states the following to be a rapid mode of analyzing these ores. He boils them with chloride of copper slightly acidulated w^ith muriatic acid, then on boiling the residue with carbonate of soda, washing the result, drying and weighing, its weight indi- cates that of the carbon .+ * Poggendorffs Ann, xxxvii. 545. t L'Institut, 170. 448 Notice of some Recent Add Salts. — In a memoir by Mitscherlich, it is observed that soda and potash unite in two proportions with sul- phuric acid in order to form acid salts, which may be con- sidered as compounds of hydrous sulphuric acid and neutral salts, as was suggested by Mr. Graham. In well formed crystals we have acid sulphates of potash and soda, in which the sulphuric acid in a hydrous state is in the same proportion as the sulphuric acid in the neutral salts ; then an acid sulphate of soda NO, SO^ + ^ HO, SO^ and lastly a sulphate of potash, in which the hydrous acid is only the 4th of the sulphuric acid of the neutral salts. Ammonia unites with sulphuric acid (NH^ HO, SO^ + ^ HO, SO^) as potash does with manganic acid, (KO, MnO^ + -J HO MnO^) but only in a proportion to form an acid salt. The acid salts of chromic acid, are on the contrary, only com- pounds of chromic acid and a base ; the acid chromate of potash contains in the same quantity of base twice as much as another acid salt, which is obtained by dissolving the first acid salt in nitric acid, and collecting the crystals pre- cipitated in the solution. The acid seleniate of potash (KO Se O^ + HO, Se O^) has the same form as the cor- responding acid sulphate. The acid sulphate of potash has the same form as sulphur ; after being fused it assumes a form similar to that assumed by melted sulphur. The acid manganate of potash and sulphate of ammonia have the same form and composition.^ Decomposition of Iodide of Mercury by Light. — The iodide of mercury, when dried in the light of the sun, becomes dark olive coloured. According to Artus, there is no free iodine separated ; but hydriodic acid is given out, so that the combination, formed by the light, consists of protoxide of mercury and iodide. Water must, therefore, be neces- sarily present. Iodide of mercury dried in the water bath is, however, almost indifferent to light.f Preparation of Antimony free from Arsenic. — According to Artus, this may be effected as follows : mix one part of finely powdered crude antimony with two parts of common salt. Digest the mixture in a retort with five parts con- centrated sulphuric acid and two parts water for six or eight hours; boil it then for one hour; dilute the solution with an equal volume of rectified spirit of wine, or with as * L*Institut,170. t Journ. fiir prakt Chemie, viii. 6^. Improvements in Science 449 much water as it can take up without decomposition ; allow it to stand at rest for some time ; filter ; precipitate the filtered liquor with water ; filter again ; wash and edulcorate the filtered basic chloride of antimony ; press it gently, and dry it at a gentle heat. This basic chloride is, when properly prepared, completely free from arsenic, and it is only necessary to heat 100 parts of it with 80 parts of carbonate of soda and 20 parts of carbon powder for a quarter of an hour, to obtain 61 J parts of antimony com- pletely free from arsenic* Separation of Basic Phosphate of Lime from the Ammonia Phosphate of Magnesia by Acetic Acid. — Thismethod has been proposed in consequence of the insolubility of the former, and the solubility of the latter salt in acetic acid. Du Menil found, that acetic acid of the specific gravity 1*04, when digested for foiiV hours with one-sixth of its weight of phosphate of lime acquired no trace of lime, when the salt was heated ; only a very slight trace, when it was dried at 212° ; but a great quantity, when precipitated fresh, and acted on when moist. Ammonia phosphate of magnesia, dried at 212°, dissolves rapidly in six times its weight of acetic acid. When the solution was heated, a portion of the salt separated in the form of a crystalline crust. A similar effect was produced by doubling the quantity of acid.f Adulteration of Succinic Acid with Succinate of Lime. — Schwenke has procured as much as 15 per cent, of lime from a specimen of succinic acid. J Cochineal of Ararat. — In that part of Armenia which is now incorporated with the Russian empire, in the province of Erivan and in the vallies of the Araxes, a species of cochineal insect is found, which, according to M. Hamel, appears to be unknown to naturalists. It is met with principally in the villages of Schorly, Sarwanlar, Nedschely, Hassan Abad, &c. M. Hamel, by giving a view of the different authorities who have mentioned it, shews that it enjoyed an important rank in commerce until the period when the American cochineal shut it out of the market. It is very distinct from the cochineal of Poland. A pound * Pharm. Central blatt, Oct. 1836, 638. t Arch, der Pharm. vi. 73. t Pharm. Central blatt, Auj,'ust, 1836, 558. 450 Mr. W, Galbraith's .Determination of the of Armenian cochineal contains only from 18 to 23 thou- sand insects, while that of Mexico contains 20 to 25 thousand, and that of Poland 100 to 130 thousand. It contains also more colouring matter in an equal weight than the Polish. It is found abundantly on the roots of the JEvolupiuf laevis, (Trinius,) a plant which grows abundantly in Erivan. Brandt proposes to call it Porphyrophora Hamelii.* Inferiority of English to China Ink. — The directors of the Bengal bank lately refused payment for a number of bank notes, in consequence of their containing no signature. It appeared that they belonged to a Hindoo, who had kept them in a copper box. He asserted that they originally possessed the signatures of the director, comptroller, cashier, &;c., but that they had been effaced. The notes on which the signatures had been written with China ink remained uneffaced, but all the writing with English ink had com- pletely disappeared. Mr. Princep, in order to determine the question, placed a paper covered with writing in English ink between two plates of copper. After a short space of time he found that the copper had decomposed the ink, and that the writing was completely effaced. He concluded that the account of the Hindoo was correct, and that the bank ought not to refuse payment.f Article VII. Determination of the Obliquity of the Ecliptic at Edinburgh. By W. Galbraith, A.M. (To Dr. R. D. Thomson.) Edinburgh, Wth November, 1836. Dear Sir, . As -a continuation of my former paper' on astronomical observations, I hereby send you the results of my recent determination of the obliquity of the ecliptic in June, 1836, with a new circle somewhat improved. It has three ver- niers, each showing 10", the scale of the level is divided so as to indicate 3" and a third, or at base, a half of each division may be readily estimated. The diameter of the * L'Institut, 183, 374. t Asiat. Society Journal, and L'lustitut, 182, 368. ^ Obliquity of the Ecliptic at Edinburgh. 451 circle is like that used in the former observations, six inches, having a telescope provided with eye glasses possessing magnifying powers of 20 or 30. The circle seems, however, to have a small bias or irregularity on inverting the tele- scope after reversing the circle, amounting, at a maximum, to about 5", and proportional to the sine of the zenith distance, which has been allowed for. Further observations will enable me to investigate this more exactly. 1836. Mean obliquity for January 1st, from observations made, June 14th 23 27 297 „ 15 27 35-3 „ 16 27 31-3 17 . , 27 32-4 j> „ 20 27 40-2 „ 21 27 46-8 „ 23 . 27 50-2 „ 24 . 27 54-6 „ 25 . 27 32-6 „ 28 27 36-1 Meanof the whole of these . 23 27 38-9 Bessel gives 23 27 38-4 My general tables give . . 23 27 39-4 Though there are considerable discrepancies in the pre- ceding observations, yet they are not greater than might be expected, from the size of the instrument and power of the telescope, especially in such unfavourable weather as we had last June. They were reduced by the formulae given in my last paper, in which there are one or two errors of copying, and some typographical, but these com- monly do not affecifc the accuracy of general formulae or final results. I was able to get only two or three rather unsatis- factory observations on the late equinox, which I conse- quently think scarcely worth transmitting you. I am, dear Sir, Yours sincerely, WILLIAM GALBRAITH. 54, South Bridge. 452 The Art of Dyeing , \ Article VIII. The Art of Dyeing. (Continued from page 375.) When calico printed with iron and copper mordant is dipped in a solution of 1 lb. ferro-prussiate of potash and 40 lbs. water, it acquires a dark brown colour, from the production of ferro-prussiate of copper. Except in the case of logwood colours there appears to be no advantageous action from this relation of cotton mordanted with iron mordant to copper mordant. Its influence is rather deteriorating. Thus a cochineal blueish gray, with iron alum is not obtained, but a violet colour, when the calico is treated with copper mordant in the manner described, before dyeing with the cochineal. When lighter grounds which have iron for their basis, after dyeing are immersed in copper mordant, No. 2, various shades of colour are obtained of greater permanence, although with most of the dark colours of compounds containing iron, the changes are not so remarkable as in the colours with alum mordant. ON THE ACTION OF DIFFERENT ADJUNCTS IN DYEING WITH MADDER, QUERCITRON, AND LOGWOOD. 1. Madder with starch, flour and bran. — When the alum mordant to be printed is thickened with starch, the madder red produced by it comes out clearer than when the thick- ening medium is gum. This fact might lead us to the suspicion that the clearing action of bran depends on the proportion of starch in it. Starch was therefore added to a solution of madder, and dyeing performed as on the addition of bran. The result was different from what ♦might have been anticipated. The addition of starch deteriorated the action. In the proportions of 1 lb. starch, 12 lbs. madder, and 12 lbs. mordanted cloth, the colour produced was much the same as when no starch was added. With 3 lbs. starch to 12 lbs. madder, the colour was considerably paler. On the edge of the dye pot a pasty looking matter was deposited, and much red varnish swam on the surface of the solution. As the red varnish is neither produced by the use of bran Madder with Starch, Flour and Bran, 453 itself nar by the proportion of 3 bran to 1 madder, it is obvious that bran does not receive its efficacy in dyeing from the starch contained in it, but from some other con- stituent. Wheat flour acts with as little advantage but less disad- vantageously than bran. In the proportion of 1 lb. flour to 6 lbs. madder and 6 lbs. mordanted cloth, the colour is only a little more red than madder-red dyed without an adjunct. When the quantity of flour is increased to 3 lbs. it acquires a similar action to the bran, but which is not stronger than is obtained by 4 lbs. bran, 6 lbs. madder, and 6 lbs. mordanted cloth. It follows, therefore, from this, that the action of the bran in madder dyeing, is not to be ascribed to the flour which is still contained in the wheat bran. These results led Runge to make the inquiry, to which of the constituents of bran does it owe its well known property, since it is neither due to the starch nor to the flour containing gum. He first examined the husks of the bran. To obtain these in a state of purity, wheat bran was washed so long with cold water as it continues to dissolve and remove starch or flour, and then the remaining brown coloured husks were added to the madder solution. It was then found that the husks of bran had a stronger action upon avignon madder than the same quantity of unwashed bran. From what was said formerly, the action of bran appeared very doubtful. It seemed to redden brownish madder-red, and to distribute the madder-red over a greater surface. By the first action of the bran, a clearer red is obtained than usual ; but the second, the production of a very saturated red is prevented. In respect to the husks of bran, they afiect a distributive action. They equally hold the colour- ing matter, and render it difficult to combine with the mordanted cotton. The following experiment shews this : In a solution consisting of 12 Avignon madder, and the husks of 36 bran, 3 of mordanted cloth were successively dyed three times with an increasing, and at a boiling temperature. The result of the first dyeing with 3 cloth was a clear red not half so dark as the first dyeing with madder and bran, noticed in a former part of this treatise. In the 454 The Art of Dying . second and third dyeing, the colours were lighter, so that from this it appears, that the husks of 36 bran keep back the half of the colouring matter of 12 madder, while the corresponding quantity of bran in its natural state gives it up and deposits it on the calico. This seems to shew, that by washing the bran with water, substances are removed which by the use of unwashed bran are precipitated simul- taneously with the colouring matter upon the mordanted calico, and assist in forming the madder- red. This also explains the higher shade of the madder-red dyed with bran. It yet remains to be explained, why cloth mordanted with alum mordant, by boiling with bran, acquires the property, after proper washing, of becoming blue in solu- tion of iodine. This property of becoming blue certainly only demonstrates the presence of starch in the calico ; but it renders it highly probable, that other constituents of the bran also combine with the calico. To ascertain this last point, the relation of the washings of the bran to madder in dyeing were also tried. The milky washings, but free from husks, of 36 bran were mixed with 12 madder, and therein 3 of mordanted cloth were three times dyed in succession. Colours were obtained, which were equal, though, when closely inspected, scarcely so clear as those obtained in the usual way with bran. The last circumstance induced the following trial to be made. The milky bran washings at 68° deposited, after standing for two or three hours, a white mealy sediment, and the solution assuming a dirty yellow colour. Both the mealy deposit and the cold bran infusion were tested as to their relations to madder. The action of the mealy deposit, when well washed and dried, was similar to that of wheat flour. Hence, it appears that the cold infusion of bran exhibits the same action as frequently appears in dyeing. For its employment, two lbs. of sifted bran wree stirred for the space of an hour with 20 lbs. of water, then the solution was let off, and after filtration added to the solution of madder in different proportions instead of the bran. It gave in the proportion of 3 lbs. of the cold infusion to 6 lbs. of Avignon madder in the first dyeing with 3 lbs. of mordanted cloth, a very clear light red. The 3 lbs. of Madder with Starch, Flour and Bran, 455 cloth, by the second dyeing, obtained a dark very clear pink colour, and the 3 lbs., by the third immersion, was not half so dark. Unfortunately, it is not possible to give more depth to this red by altering the proportions. The cold infusion acts in this case like the husks. It prevents the formation of a dark saturated colour. When the pro- portion is diminished, 1 to 2 lbs. of infusion to 6 lbs. madder, the red is so much darker, that one can scarce distinguish whether bran alone was employed. In the last place, the chemical properties of this solution were tested, especially the white precipitate, which a clear solution of sugar of lead produces in it. This was after proper edulcoration with water precipitated by hydro- sulphuric acid ; the solution was clarified by heating it, and, after filtration, added to the madder solution. In this experiment its advantageous action on the madder-red was exhibited, although in a less degree than when common bran is employed. Although the bran prevents the formation of very dark madder colours, this property, in certain circumstances, is a means of lightening the power of the madder colours in a considerable degree. An addition of bran causes a definite quantity of madder to give out more colour than happens when there is none present. This remarkable action, which occurs with no other matter yet known, goes so far, that solutions which already, in the usual way, are exhausted to such a degree by mordanted calico, that they produce only a reddish yellow colour, are rendered capable, by the addition of bran, of dyeing red again. Article IX. Analyses of Books. I. — Philosophical Transactions of the Royal Society of London for 1836. Part I. Mathematics and Physics. Discussion of Tide Observations made at Liverpool. By J. W. Lubbock, Esq., F. R. S. Researches on the Tides. 4th Series. On the Empirical Laws qf the Tides in the Port of Liverpool. By the Rev. W. Whewell, M. A., F.R.S. In a previous paper, the author endeavoured to obtain the mathe- matical laws of the inequalities of the tides from the results of the 456 Analyses of Boohs. London tide observations for 19 years. A similar table of the Liver- pool tides having been published since, he uses these results in the present paper to test and improve the formulae, to which he was led by the London observations. He shews, in a very satisfactory manner, that the Liverpool observations have confirmed his formula?, the results of the means of large masses of observation agreeing with them, with a precision not far below that of other astronomical phenomena, as for example, a fraction of a minute in the times, and a fraction of an inch in the heights. Researches towards establishing a theory of the Dispersion of Light, By the Rev. Baden Powell, M. A., F. R, S. In a paper, inserted in the last part of the Transactions, the author commenced a comparison between the results of M. Cauchy's system of undulations, expressing the theoretical refractive index for each of the standard rays of the spectrum, and the corresponding index found from observation in different media. This comparison is there carried on for all the results obtained by Fraunhofer. But these include only a limited range of transparent bodies ; and close as is the accordance in these instances, the theory cannot be considered as fully verified until we shall have extended a similar examination to a greater number of media, and especially to those of higher dis- persive power. The author is at present engaged in this research. But has submitted a portion of his results to the public in the present paper. He compares them with Rudberg's experiments, which closely approximate. The substances examined are calcareous spar, quartz, aragonite, and topaz. From these researches it appears, that the hypothesis of undulations assigns the law and cause of dis- persion in ten new cases in addition to the ten considered in his former paper. Reseai'clies in the Integral Calculus. Part I. By H. F. Talbot, Esq., F. R. S. The first inventors of the integral calculus observed, that only a certain number of formulae were susceptible of exact integration, or could be reduced to a finite number of terms involving algebraic, circular, or logarithmic quantities. When the result could not be attained, they were accustomed to develope the integral in an infinite series. But this method is inadequate in an analytical point of view to supply the place of the exact integral. Fagnani, about 1714, made a great improvement. Euler further improved this branch of mathematics. Abel carried the improvement still further; and the author, in the present paper, details his interesting additions, and the steps of the processes by which he was conducted to make them. {To he continued.) TI. — On the Gales and Hurricanes of the Western Atlantic, By W. C. Redpield, Esq., of New York. The object of this pamphlet is to shew, that the violent gales which so frequently visit the Western Atlantic are not of an erratic and abnormal character, and to demonstrate, that they are guided by comparatively great regularity. The author, after a careful ex- Analyses of Boohs. 457 amination of the evidence of various storms, states, that he has found them to pursue generally a uuiform course, which is always north- westerly in the tropical latitudes, and till they approach the latitude of 30^ N. "In the vicinity of this parallel, the storms turn to the northward, and then their course becomes north-easterly on a track which appears to incline gradually to the east as they sweep over the higher latitudes of the Atlantic. The course thus pursued is entirely independent of the direction of wind which the storm may exhibit at the different points over which it passes ; the wind in all such storms being found to blow after the manner of a whirl- wind around a common centre or vortex during their entire pro- gress, in a circuit which is commensurate with the lateral extent of the storm; and in a determinate direction or course of rotation, which is from right to left (that is, in the direction from west to south) horizontally." The direction of these gales would appear, therefore, to be that of the Gulf stream. The remainder of the paper is occupied with important details relative to particular storms, and will be found of great interest to meteorologists and nautical men. Article X. Scientific Intelligence. I. — British Association for the Advancement of Science. Section E. — medical science. {Continued from page 395.) The second paper read this morning was by Dr. Houston, descrip- tive of a Twin Fcetus, born without Brain, Heart, Lungs, or Liver. The placenta was double, and there were separate membranes and cords for each foetus. The umbilical vein of the imperfect infant opened directly into the vena cava, from which branches, totally devoid of valves, passed to all parts of the body. The arterial system, commencing from the venous capillaries and gradually running into larger trunks, formed a sort of aorta, like that in fishes, from which the umbilical arteries arose. No communication existed any where between the arteries and veins except at the capillaries ; so that by whatsover vessels the blood entered the body, by the same it must have been distributed. A round tumor, which existed in the substance of the cord, outside the umbilicus, had produced effects on the vessels calculated to throw light on the course of the circula- tion— the vein was varicose from the tumour as far back as the placenta, and the arteries were dilated on the side next the body of the foetus. There is much difference of opinion respecting the course of the blood in abnormal foetuses of this nature, and such distinguished individuals as Sir Astley Cooper, Sir B. Brodie, Ticdemann, xMonro, Blandin, Breschet, &c., have been engaged in the controversy. Sir A. Cooper has lately made a discovery, that there is a free anas- tomosis in the placenta, between thevesels of the cords, from which 458 Scientific Intelligence, Sfc. he concludes that the circulation in the imperfect foetus is carried on by the action of the heart of its companion in utero. Some of these authors argue that the blood proceeds from the placenta to the infant by the veins, and is returned therefrom by the arteries ; others, that it passes in the same course by the arteries, and is returned again by the veins. Dr. Houston's observations go to establish, as a fact, that the course of the blood in the cords and placentae of the two infants is the same, but that in thin bodies it is different ; he considers that while the blood enters both bodies at the same time by the umbilical veins, it is transferred in the perfect infant to the aorta, through the foramen ovale of the heart, and is thence distributed in the ordinary manner ; whereas, in the imperfect infant, it is conducted all through the body, without such transfer from vein to artery, and is thus made to take an inverted course — the veins of the body assuming the function of arteries, and, vice versa, the arteries that of veins. Dr. Houston considers that the presence of anastomoses between the cords should rather lead to the inference, that the blood traverses both placenta in the same course, than that it takes a direction in the one different from that which it follows in the other. The accidental effect, produced by the tumour in the cord of the foetus examined by him, proves to demonstration, that, in that instance at least, the blood entered the body by the veins, and returned by the arteries ; and the absence of valves in the veins accommodated these vessels for the reception of the blood, and for its transmission in a retrograde direction through them. Dr. Houston suggested several good reasons in support of his opinion, that the heart of the perfect foetus can exert very little influence in propelling the blood into the vessels of the imperfect one ; and considers that we must look to some other cause than a vis a tergo for the accomplishment of this object. He is of opinion, that the theory of " vital attractions and repulsions," though con- veyed in terms which may be considered rather as expressive of the facts than as explanatory of them, approaches more nearly to the true one than any other which has been yet broached. Dr. Houston suggested arguments to prove that the placenta possesses the same vital powers of attraction and repulsion as the living foetus itself, and considers, that by such powers in mutual and reciprocal operation, the blood may be carried to and fro along the vessels of the cord without any farther mechanical influence what- soever. Several drawings of the foetus were exhibited ; and the reading of the paper led to a discussion, in which Dr. Prichard, Dr Carson of Liverpool, Dr. O'Beirne of Dublin, Mr. Carpenter, and Dr. Macartney took part. It was a conceded point, that the circulation in the capillary vessels was independent of the action of the heart, and it was stated, that there was no case on record, in which a monster foetus existed without a perfect foetus ; nor had there been ever any case discovered in which a single child had been found without a heart. The third and last paper which occupied the attention of the Section this day was one by R. Carmichael, Esq., on Tubercles. British Association. 459 The reading of this paper, many of the propositions of which were illustrated by preparations in a high state of preservation, occupied one hour and a quarter, and commanded much attention. The following abstract will give our readers an outline of its contents : — Mr. Carmichael commenced his paper on Tubercles with some remarks upon the great prevalence of these formations, and then proceeded to detail their appearances according to the descriptions of Leennec and Carswell. He adverted to the use of the term scro- phula, which he considers a cloak for ignorance ; and having stated, that Drs. Todd, Clark, and Carswell believe in the identity of scrophula and tubercle, disputed this position, and likewise their opinion, that tubercles are inorganizable deposits. Among other objections, he urged the inconsistency of representing enlarged cervical glands, and pulmonary tubercles as identical, since it is well known that the former may be injected, but not the latter ; and of main- taining the non-inflammatory origin of tubercles, together with the view that these bodies are lifeless matter ; since, if such is their nature, they must excite inflammation in the tissues which contain them. He allows, however, that the scrophulous constitution dis- poses to tubercles, but only in the same manner as to cancer. Mr. C. next adverted to the generally recognized connexion between scrophula and disordered digestion, and claimed the priority of this observation, by reference to a work which he published in 1810. He then proceeded to argue, at considerable length, in favour of the parasitical origin of tubercles, pointed out the absence of vascular com- munication between these bodies and surrounding parts, and observed, that so long as the former retained their vitality no inflammation takes place. The author declared his opinion, that carcinoma must likewise be arranged among the entozoa, and having indicated the division of a cancerous formation into a medullary and a cartilaginous portion, assigned to the former an independent vitality, the latter being only a barrier which nature sets up against the parasite ; and showed that the containing cyst belongs to the surrounding tissue. The cartilaginous portion, he stated, might be injected, but not so the medullary. Tubercles he considers more allied to carcinoma than to scrophula. Having spoken of a difference between fungus medullaris, and fungus haematodes, he proposed to arrange the formations which had passed under review, as constituting four species of entozoa: — 1. Turbercles found in the lungs; 2. Tubercles found in the abdominal organs; 3. Fungus medullaris and haematodes; 4. Carcinoma. The author concluded by stating, that the doctrines of the inde- pendent vitality of tubercles was making considerable progress among the physicians of Germany. It was the business of the profession to point out the means of prevention rather than the cure of this disease. Wholesome nourishment, pure air, temperance and exercise, were the great preventatives. It was remarkable that the agricultural popula- tion were comparatively free from these affections — a circumstance which he accounted for, by the digestive organs being in a more healthy state, and furnishing the alimentary canal with fresh supplies of nourishment to supply the waste which was constantly VOL. IV. 2 H 460 Scientific Intelligence^ ^c. going on in the system. Multitudes, it was true, came into the world with this disease entailed on them ; but this he considered a result of the breach of the moral laws of the governor of the universe, and a punishment inflicted on children reflected back from the parents, until, according to the statement in the decalogue, in the third or fourth generation, it ceased to propagate its contaminating influence. Wednesday, 24:th Amjitst. — The first paper read was by Dr. Hodgkin, on the connexion between the veins and absorbents. ]3r. Hodgkin observed that the Committee appointed to make inquiries into this sul)ject had been very fortunate, in the opportunities afforded them of examining the bodies of subjects in whom the lymphatics were much develo})ed. There was great difficulty in injecting the lymphatics, it requiring a sharp eye and a delicate hand to be anything like successful. Mercury injected into the lymphatics will sometimes pass off by the veins, and some are disposed to admit a natural communication between these structures. In injecting subjects at Guy's Hospital, it was found that the mercury passed easily from the glands into the veins, in very recent subjects. The idea of transudation through the sides of the vessels must be rejected in mercurial injections, though it may happen when water is injected. Mr. Bracy Clark, in injecting the vessels in a horse, found a direct communication between the receptaculum chyli and tlie lumbar veins. Breschet is inclined to adopt the opinion that in the villi of the internal canal, the lacteals communicate by minute openings with the veins. If water is thrown into the arteries, it will almost imme- diately fill the lymphatic vessels. Dr. li. has seen lymph flowing in the thoracic duct tinged with blood. Mr. King has observed the fact that the thyroid gland contained a number of small cells, which were filled with a fluid differing from any other, and it is almost proved that there is a communication between the internal surfaces of these cells and the lymphatics of the organ. The most remarkable observations on the lymphatics have been made on the inferior animals. Dr. Hodgkin observed, that he believed the communication of the veins and lymphatics occasionally happened, but that they were not found at will. Dr. II. then explained the construction of the valves of the veins of the different vessels, and illustrated his description by diagrams. Dr. Read then read his paper, entitled '^ A short Exposition of the Functions of the Nervous Structure." Dr. Gayward then read to the Section a paper, by Mr. Alcock, containing some particulars on the Anatomy of the Fifth Nerve. Dr. Macartney exhibited to the members a portable probang. Dr. M. also read two short papers; one, an Account of the Organs of Voice in the New IloUand Ostrich, and the other on the Structure of the Teeth. The last paper was by Mr. Walker, on the Nerves and Muscles of the Eye Ball. Thursday, 25th Avr/ust. — The papers were— First, " A report of the Dublin Committee, appointed by the British Association, on the Motion and Sounds of the Heart," read by Dr. Macartney. British Association. 461 Secondly, " A report of the London Committe on the same sub- ject," read by Dr. Clendinning. Dr. Symonds read a letter from Dr. Spittal, of Edinburgh, stating that by reason of the death of Professor Turner, and in the absence of one of the members on the continent, the Committee of the Asso- ciation had not been able to make any report on the same subject, the investigation of which was committed to them at the last meeting of the Association ; but that it was their intention to go into the subject. The third subject introduced was — *^ On the Gyration of the Heart, by Mr. Greeves." The following is an abstract of the paper : — 1. Muscular fibres can act as levers without a solid fulcrum, if there be another set of fibres set at an angle, and contracting simul- taneously. 2. A hollow organ may be dilated by the construction of such an arrangement of fibres, if in contracting they become more parallel to a plane passing longitudinally along the axis of the organ. 3. That there are two spiral, two longitudinal, and one diagonal set of fibres in the heart, interlacing each other. 4. The ventricles gyrate incessantly to and fro upon their axis. a. In systole, or involution, as the left hand pronates. b. In diastole, or evolution, as the left hand supinates. 5. The double spiral curve of the two great arteries forms a com- pensating and regulating movement, causing 6. i. A diminution of friction. 7. ii. Steadiness and celerity of motion, on the principle of the tilt hammer. 8. iii. An isochronous action, on the principle of the balance- wheel and spring. 9. iv. The progression of the whole heart. 10. That the function of the auricle is to maintain the equilibrium of the venous system. 11. The first sound is produced by the sudden tension and sudden change of gyration occasioning vibration of the ventricular walls. The second sound is from flapping of the sigmoid valves. 12. The impulse is partly caused by the progression, partly by the atmospheric pressure, and chiefly by the left ventricle, first gyrating into the proper position to do so, carrying the apex against the thorax, with a force equal to the difference of strength between the right and left ventricles. 13. Bruit de sotiflet in the heart, is the result of increased fric- tion on the pericardium. The author said he was aware his views on this subject were sto very different to those generally entertained, that he appeared, as it were, on his trial before the philosophy of the kingdom, as to whether they were true or erroneous. Dr. Carson, of Liverpool, after combating some of the propo- sitions of Mr. Greeves, said, he saw nothing to induce him to resort to gyration, when dilatation seemed so natural. It was evident, on grasping the heart of an ox, for instance, that it expanded with great force ; and he had heard nothing to induce him to alter his notion of the dilatation of the heart. 2 H 2 462 Scientific Intelliyence, §'c. Dr. Williams said, he believed the elasticity of the heart was sufficient to account for the phenomenon of its dilatation. A paper " On the Polarization of Light observed in the Crystal- line Lens, by Sir David Brewster," was read by the President ; as was also a letter from the same gentleman on the subject of cataract, which, if resisted in its early stages, the author believed might be overcome. This disease, which generally manifested itself between the ages of forty and sixty, when persons begin to require spectacles, Sir David gave a receipe for detecting, which he had done in his own case; and though, perhaps, induced by an impaired state of health, yet, by attention to diet and regimen, and taking care not to study by night, he found in about eight months he was cured. If the affection had not been checked in time, he entertained no doubt it would have ended in cataract. The last paper read was On Absorption, by Dr. Carson, of Liverpool. Friday, 2Qth August. — Mr. Adams stated the appearances he had observed in Chronic Rheumatism, viz., as in the arm, enlargement of the glenoid cavity and head of the humerus, and loss of the tendon of the biceps. He described several other morbid appearances, and shewed specimens. Mr. Hetling read a paper " On a New Instrument for the removal of the Ligature of Arteries at pleasure." Mr. Gordon exhibited some Anatomical Models. The last paper read, was " On the Chemistry of the Digestive Organs," by Robert D. Thomson, M. D. The author began by drawing attention to the necessity of admitting chemical action as an important agent in digestion, because, inasmuch as every change in the position of the ultimate particles of matter is a chemical or electrical change, so the conversion of food into chyme and its assimilation must fall under this head. Dr. Thomson divided the consideration of the subject into — I. Chemical state of the stomach, first, in health ; and, secondly, in disease. II. Chemical state of the mouth and cesophagus, first, in health ; and, secondly, in disease. I. First, He remarked, that our most eminent physiologists had completely overlooked the experiments of Dr. Prout and others, which establish the fact, that in health the stomach contains a quan- tity of free muriatic acid. He referred to the recent experiments of Braconnot, who had found a great quantity of this acid in the stomach, and who had determined by very satisfactory experiments that no lactic acid was present. The author detailed an experiment, in which he had succeeded in converting muscular fibre into a substance exactly resembling chyme, by digesting it in dilute muriatic acid, on the sand-bath, during ten hours, taking care to keep the mixture as nearly as possible at a temperature equal to that of the human body. He, therefore, drew the conclusions : — first, that the stomach, in a state of health, when excited by stimulants, contains a quantity of free muriatic acid; and, second, that dilute muriatic acid is capable of pro- ducing by digestion with animal matter, at the temperature of the human body, a substance similar to chyme in its physical properties. From which it may be inferred, that free m.uriatic acid is an important British Association. 463 auxiliary in the process of digestion. Second, with reference to the state of the stomach in disease. Dr. Thomson observecl, that the most common form in which chemical re-agents were affected, was by a redundancy of acid, occasioned by the introduction into that viscus of acid fruits and vegetables, which gave rise to fermenta- tion, and the symptoms of heart-burn, a very familiar complaint. He next proceeded to describe the only other form of disease of the stomach, which was indicated peculiarly by the action of re-agents, by an alkaline state occurring in the disease commonly termed porosis or water-brash. Having investigated this disease very carefully with regard to its chemical nature, he showed that it pro- ceeded from the diseased state of the secretion in the stomach, — alkali having taken the place of the free acid. By chemical analysis he found that the alkali was ammonia, and probably, also, a little soda was present. Having observed this very remarkable and important fact, the practice consequent upon it was evident, and the result proved of the most satisfactory nature ; he found that the administration of acid gave immediate relief. If the case was of a chronic nature, he prescribed also anodynes, — asconium and hyoscy- amus, in order to act directly upon the nerves, should they have been long subjected to the action of the diseased secretion. The author detailed the particulars of several cases. In one instance, a female had become greatly emaciated, in consequence of the disease having existed daily for three months, — the patient ejecting by the mouth, in the course of the day, not less than a pint of tasteless fluid. Dr. Thomson immediately prescribed for her an acid mixture, and in the course of two days, when he next saw her, the disease had entirely disappeared ; nor was she again affected by it. The author stated that he had been unable to detect any general laws, which would seem to regulate this complaint. He had met with it in all constitutions and ages, and equally as abundantly in England as in Scotland. Butter and all oleaginous substances were liable to pro- duce it, as well as the simultaneous use of apples and porter, at least in some individuals. II. First, The author next proceeded to detail the results of his experiments upon the chemical state of the fluids of the mouth during health, which, in confirmation of the experiments of Donn^, of Paris, he had found to be alkaline, and sometimes neutral. He noticed the experiment of Donne, which would appear to prove that the mucous membrane of the alimentary canal (which is alkaline) and the skin (which it is well known is acid) constitute a kind of voltaic pile ; for when one of the poles of a delicate galvanometer is placed in contact with the mouth, and the other with the skin, very distinct electric currents are produced, which cause the needle to deflect 15°, 20"^, and sometimes 30°. Second, the author stated that he had found the mouth indicating an acid re-action whenever inflammation existed in any of the mem- branes in connexion with it, as in laryngitis, pleuritis, bronchitis, gastritis, and enteritis, and in other diseases of an inflammatory nature. He directed the attention of medical men to this fact, as a most important feature in the diagnosis of such diseases. He stated 464 Scientific Intelligence, Sfc. that he had extended his observations to many inflammatoiy diseases, and had found, uniformly, that inflammation of mucous and serous membranes in all parts of the body, is attended by the secretion of free acid. Hence the scientific method of removing this source of irritation in such diseases, viz., by the local application of alkaline solutions, as in erysipelas, inflammation of the urethra, &c. He stated also that he had examined the chemical composition of the membrane deposited in croup, and had found its principal constituent to approach nearer the character of albumen than any other animal substance, which would add some weight to the opinion of Donne, that morbid products derive their origin from the free acid secreted on the surface of the membrane upon which the product is deposited. Additions to the different Sections, We are indebted for the following reports to their respective authors. On a method for ascertaiyiinfj the strength of spirits, by Mr. William Black. (The author of this paper is well known by his valuable '' Practical treatise on Brewing and on Storing of JBeer, deduced from forty years experience.") I believe it has for long been a desideratum with government to find a more scientific and accurate mode of ascertaining the strength of spirits than that now in use. A very slight inattention in the method of using the hydrometer may make a difference of at least five })er cent., and when the spirits are adulterated with sugar or salts, that instrument is totally useless. It is a well known fact that when equal quantities of proof spirits and water are mixed together at a temperature of between 50" and 60° (Fahrenheit), the thermo- meter, if immediately immersed in the mixture, will rise 9^ degrees. I do not, however, think it is so generally known that the thermo- meter rises more or less, according to the strength of the spirits, and that it does so apparently in very regular progression, when the spirits are between the strengths of 45 per cent, over and 45 per cent, under proof. When spirits, 45 per cent, over proof, are mixed in equal quan- tities with water, both being of the same temperature, i. e. between 50® and 00°, the thermometer, if immediately immersed in the mixture, will rise 14° degrees ; but with the strongest alcohol, also mixed with an equal quantity of water, it will not rise above that temperature ; no further concentration therefore takes place, unless more water be added, shewing, I should think, that alcohol can only combine with water in atomic proportions, and that a certain portion of that spirit must remain in the first mixture in an uncombined state. Every degree on the thermometer appears to indicate a difference in the strength of the spirits of about 10 per cent ; thus if we mix equal quantities of spirit, 10 percent, over proof, and water, both at equal temperatures of about 55°, the thermometer will rise 10J° ; with spirit 20^ over proof, mixed as above, it will rise 11 2°; and so on — one degree for every 10 per cent, over proof, until it reaches about from 40 to 45 over proof, when no further increase is apparent, unless, as I have before stated, more water be added. British Association. 465 The thermometer seems to act in a similar manner with spirits under proof; thus, with spirits ten per cent, under proof, mixed with water as above, it will rise about 8^,°, and one degree less for every 10 per cent, under proof, until we get to 45° under proof; after which, although a rise does take place, the indications do not seem to be so regular. When the spirits are mixed with sugar increasing the specific gravity so as to falsify the hydrometer 20 or 30 per cent, or more, the indications of the thermometer are precisely the same, making allowance for the slight difference in volume caused by the mixture of sugar. Jf the mixtures be made at higher temperatures, the indications of the thermometer are proportionally a lesser number of degrees, according to the temperature ; I think when between 70° and 80° nearly 2 degrees less, but the progressions appear to go on regularly as before. I do not, however, presume to give the above as accurate results, but merely to state that the thermometer appears to indicate a regular progression according to the strength of the spirits, and the tempe- ratures at which they may be mixed with the water. My only desire at present is to draw the attention of men of science to the subject, who may discover some mode of application which may render it available, and perhaps accurate, in ascertaining the qualities of spirits or acids. Abstract of a Paper read before the 3Iembers of the JBritish Association^ at Bristol, August 20, 1836, entitled^ *' On some Fallacies involved in the Kesults relating to the comparative Age of Tertiary Deposits obtained from the Application of the Test recently introduced by Mr. Lyell and M, Deslmyes." By Edward Charlesworth, Esq., F. G. S. During the author's investigation of the fossiliferous strata above the London clay in Suffolk and Norfolk, some facts have come under his observation, which appear to him to point out sources of error to a considerable extent in the application of the test recently proposed by M. Deshayes and Mr. Lyell, and which is now so generally made use of in the classification of tertiary formations. The crag has been referred by Mr. Lyell to his older jdiocene period, on the authority of Deshayes, who identified among the fossil testacea of that deposit 40 per cent, with the existing species. The correctness of this result has been called in question by other eminent conch ologists, particularly by Dr. Beck, of Copenhagen, who has examined the crag fossils in the author's collection, and considers that the whole of them are extinct. In this opinion Dr. Beck is supported by Mr. G. B. Sowerby, who states, that he has only met with two or three crag shells, which may, perhaps, be identified with existing species. Professor Agassiz has inspected an extensive series of ichthyological remains, collected from the crag by the author, and pronounces them all to belong to extinct genera or species; while a precisely similar result has attended Dr. Milne Edwards's examination of the corals. Professor Phillips, in his introduction to geology, has placed the 466 Scientific Intelligence, Sfc. crag in the miocene division ; while Dr. Fleming, who, for more than a quarter of a century, has been an indefatigable collector of British shells, considers that the proportion of recent species in the fossils of that formation has been rather 'under than over rated by Deshayes ; and among the corals of the crag he has detected a large proportion of living forms. The particular one of Mr. Lyell's divisions to which a geologist will refer any given deposit must therefore depend upon his own estimate of the characters which constitute specific distinctions, and which is evidently liable to the greatest possible amount of variation. The author next enters upon an enquiry respecting the course which should be adopted in obtaining the relations of analogy pre- sented by the fossils of different deposits to one another, or to the races in existence at the present period. The effect of the method now made use of is to class as contemporaneous those deposits which respectively furnish the same per-centage of extinct forms, without the slightest reference to the greater or less degrees of approximation which these forms exhibit, when compared with living types. The conchologists who agree with Dr. Beck cannot, by means of the per-centage test, express the difference in the amount of approxi- mation presented by the testacea of the crag and London clay to those now existing, because they would consider all the fossils of both these formations extinct, and, consequently, refer them both to the eocene division. In this instance, the relations of analogy can only be obtained by a general estimate of the amount of resemblance borne to existing species by the entire series of crag or London clay fossils, taken collectively. This mode of procedure may, at first, appear only a different adaptation of the numerical plan adopted by Mr. Lyell. It will, however, be found an important modification of his principle; for, when applied to the fossils of those formations which, from the presence of living species, can also be subjected to the per-centage test, it will, under some circumstances, furnish results that clearly establish a fallacy in one of the two methods. For instance, the red and coralline crag are supposed by Deshayes to contain the same number of extinct species ; and, by the per-centage test, they, therefore, present an equal approximation to the existing organization. But if the shells, which Deshayes thinks he can identify with those now inhabiting the German Ocean, are rejected, and the extinct testacea alone compared with living types, the forms most remote from existing species will be found to occur in that series which has been derived from the coralline crag. The author then changes his line of argument, and, assuming that there is a general agreement among conchologists as to the characters which should be depended upon in discriminating species, and also, that the per-centage test is the true method of obtaining relations of analogy, he proceeds to inquire whether the association of organic remains in fossiliferous deposits implies their previous contempor- aneous existence. The evidence drawn from this source appears to the author to be by no means so conclusive as it has been generally considered ; and his opinions have been formed principally from an attention to the causes now in operation upon the earth's surface. British Association. 467 * " The small part of this island, occupied by the crag formation, is intersected in one spot with several estuaries, which have com- pletely removed this generally superficial fossiliferous stratum, the bed of the estuary being formed in an older formation. Along the banks of the Deben, which flows through a part of the coralline crag, in some spots the fossil shells line the shore in gi-eater numbers than the recent testacea; and, during the period in which this estuary has been formed, prodigious numbers of these fossils must have been swept down into the German Ocean, and there indis- criminately mingled with the reliquice of existing species of MoUusca. It is not merely the extent of surface at present occupied by these estuaries which has thus been denuded of the crag, but considerable tracts of marsh land formerly connected with them, but from which the water has since been shut out, have also lost this original covering. Within a very short distance of the Deben, another estuary, the Stour, flows through a lacustrine deposit belonging to the newer pliocene period ; and here, in addition to the shells, is a considerable stratum of mammalian remains, which, at one period, evidently extended as far as the opposite bank of the river, a distance of about a mile and a half or two miles. '■' I must now look forward some few thousand years, and antici- pate the time when, by the recession of the sea, or the elevation of the land, the deposits forming at the mouths of these estuaries has become accessible, and is made the subject of geological investigation. I must also assume, that the geologists of that remote period have followed the same course of induction that has recently been pursued, and have arrived at similiar conclusions respecting the course to be adopted in ascertaining the relative antiquity of tertiary deposits. The age of the formation in question, then, is about to be tested by comparing its organic remains with the then existing species. Of what will these fossils consist, and whence will they originally have been derived ? The bones of such animals as are now drifted down the rivers Deben and Stour will be mingled with those of the extinctMam- malia of the newer pliocene period. The living species of Mollusca now inhabiting the German Ocean, will be found associated with the extinct Testacea of the newer pliocene, older pliocene^ and, perhaps, even miocene epoch. Yet this deposit, in which the organized beings of different geological periods shall be found thus indiscrimi- nately mingled, will be one exhibiting every appearance of regular stratification ; a deposit in which a large portion of Testacea will be found naturally grouped, and, in which, there will be the clearest evidence of their having become entombed on the spot which they had long previously inhabited. That the influences of causes now in operation is resdly producing such an effect as the one now described, admits of almost actual demonstration ; for the fossil shells of the crag are thrown up along various parts of the Suffolk coast, several miles from the spots in which they have been carried down. '' It may be said, that these older shells, entering into the new deposits, carry with them evidence of the stratum from which they • The portion between inverted commas is given at full length. 468 Scientific Intelligence, Sfc. have been derived ; or that, at all events, their worn appearance would distinguish them from the more recent MoUilsca with which they are associated. This is so far from being the case, that con- siderably finer and more perfect specimens of the Voluta Lamberti can be picked up on the sea shore, where they have been dashed by the waves upon a shingly beach, than can ever be obtained from the beds of the crag formation itself. In fact, this gradual process of degradation appears, in many instances, to be of all others the most favourable for detaching organic remains from the matrix in which they are embedded ; and, with respect to the evidence that might possibly be supposed to arise from a difference in lithological character, it should be remembered, that even if such indications did exist, by the time these new deposits become accessible, every vestige of the crag will have disappeared. There will, consequently, be nothing to excite the slightest suspicion that the crag species are not con- temporaneous with all the organic remains associated with them. In adopting this line of argument, I am, of course, supposing that the geologists of a future epoch have the same amount of information respecting the history of the tertiary deposits of those days that we have of our own, and not that a geological record of events has been continued up to that period. '* To a certain amount, then, this admixture of fossil with recent shells, even in regular stratified deposits, cannot be denied ; but it may be urged that it takes place only under peculiar circumstances, and to such a limited extent as would never interfere with the accuracy of general inductions founded upon extended research and careful practical observation. '^ If, however, we enlarge our field of observation, we shall find that a process has been going forward, attended with similar results, over a tract, the superficial extent of which far exceeds that occupied by the whole of the crag formation. The bed of the ocean, all along the coasts of Norfolk, Suffolk, and Essex, and probably as far as Kent on the one side, and Yorkshire on the other, is strewed with multitudes of the bones of extinct Mamm^ia. These remains have been taken up twenty miles from ^he shore ; and, in dredging for oysters, the fishermen have suffered considerable inconvenience from the number of elephants' bones and teeth which become entangled in their nets. Mr. Woodward supposes that the grinders of at least 500 elephants have been fished up off the oyster-bed at Happisburgh;* and, from the numbers which I have seen, I have no reason to think this calculation is exaggerated. I do not now propose enquiring whence this prodigious accumulation of fossils has been derived, or to what geological epoch they should be referred : it is sufficient for my present purpose to feel satisfied that they are the remains of beings belonging to a remote era, which are becoming entombed, covered with the balani and zoophytes that now inhabit the German Ocean. These are facts which, I presume, will not be disputed ; and yet so entirely has the operation of existing causes in this respect been overlooked, that Mr. Lyell fully concurs in the assumption that, • A village on the Norfolk coast, between Cromer and Winterton. Scientific Intelligence, Sfc, 46^ in undisturbed stratified deposits, the embedded organic remains must necessarily have existed contemporaneously; and upon this evidence^ solely, important conclusions have been drawn respecting the bones of elephants, associated with the shells of existing species of Mollusca, in a deposit in Yorkshire."* The next point adverted to in the paper is the presence of secondary fossils in the upper or red crag. During the formation of this deposit, causes similar to those now in existence appear to have been in operation ; and effects have there been produced which exactly correspond with the author's deductions as to the nature of the formations at this time in progress round some parts of the British coast. This introduction of secondary shells in the tertiary beds of Norfolk and Suffolk has been detected solely by an attention to lithological characters ; and the evidence derived from this source is no longer available when there is reason to suspect an admixture of organic remains helon^ng exclusively to rocks of the supra-cretaceous series. The species which are common to the chalk and red crag are very few when compared with those which are common to the red crag and to the subjacent tertiary strata. In the latter case, however, we have no means of ascertaining whether those individual species which occur in separate formations existed throughout distinct periods, or, like the fossils of the chalk, were, by the natural process of degradation, removed from their original matrix, to be again entombed with the races of a more recent epoch. Unless this diffi- cult problem is solved, it is clear that the application of the per- centage test may be attended with the most fallacious results. To what extent erroneous conclusions may already have been formed, from the neglect of those considerations so obviously necessary in the examination of the crag, must be a subject for future investigation. The author lastly notices some questions which have already been discussed by Professor Phillips in the Encyclopcedia Metropoli- tana.'\ The most important of these is the physical relation existing between any one fossiliferous deposit, and the locality in which the living types of its fossil species occur. II. — Belfast 3fuseum. The eighth public meeting of the Natural History Society was held in the Museum, on Wednesday, the 25th of May; about one hundred and twenty members and visitors being present. After several donations had been presented, one of the Secretaries read the follow- ing Report of the Council : — • " That these quadrupeds, and the indigenous species of Testiicea associated with them, were all contemporary inhabitants of Yorksliire (a fact of the greatest importance in geology), has been established by unequivocal proofs, by the Rev, W. V. Vernon, who caused a pit to be sunk to the depth of more than 200 feet through undisturbed strata in which the remains of the mammoth were found embedded together with tlie shells, in a deposit which had evidently resulted from tranquil waters." (LyeU's Geobgy, vol. i. p. 96. edit. 1.) t Vide Article Geology. 470 Scientific Intelligence ^ Sfc. The council of the Society, according to the usual custom, have now to lay before the members a general report of the proceedings of the present session. It is one whose course has been attended by the same unanimity among the members, and the same progressive increase of their number, which have so justly formed a subject of congratulation on former occasions. But it is one which has not been marked by any unusual or remarkable event, such as distinguished the two preceding sessions. In one of these, a debt of nearly £800 had been discharged : in the other, the unfinished portions of the building had been completed. Our history, during the past session has not been of embarrassing circumstances overcome, or of serious difficulties surmounted, but is one of cheerful and prosperous advancement, less eventful, but not less gratifying, furnishing less to record, but not less on which to frame our pleasing recollections of the past, and our happy anticipations of the future. The grounds on which this con- clusion rests, it will now be the duty of the council to lay before you, with that brevity which is most befitting when communicating to their fellow-members an abstract of occurrences, of which many of them are already cognizant. During the past year, an opinion has been gaining ground among many of our townsmen, that an extension of lectures, an extension adapted to the increasing commerce and manufactures of the town, would be highly beneficial. The council of the Society, while they felt unwilling to introduce any changes in the course they had hitherto pursued, and which had been so eminently successful, were, at the same time, most desirous of extending, as widely as possible, the utility of the Museum, and of interesting a still larger number of their townsmen in its prosperity. They, therefore, agreed that for the present session, papers on Natural Philosophy and Statistics should be admissable, in the same manner as those on Zoology, Botany, Mineralogy, and Topography, and that when a sufficient number of persons were enrolled, as desirous of reading exclusively on these subjects, particular nights should be set apart for the purpose. By this arrangement the original constitution of the Society remains unchanged, and preparation has been made for adapting it to the altered situation of the community among which it has been estab- lished. _ ^ III. — Pharmacy, ^'c. 1. Adulteration of Iodine. — Stieren has detected several adultera- tions of iodine, by dissolving the latter in spirit. The impurity remains undissolved, consisting sometimes of iron, silica, and alu- mina, at other times of iron, containing carbonaceous matter. Buch* ner has found glance coal. — Buchjier's Repert, v. 230. 2. Volatile Oils. — Volter and Dann have made a set of experi- ments to determine the relative produce of oils to the raw material employed. The following is the result. We use the German measures, which approach nearly our own, the Nuremberg pound being equal to -9592(36 lb. Troy, the lb. or civil pound consisting of l6 ounces. Multiplication by this number gives the equivalent in English. Scientific Intelligence^ ^c. 471 1. Oil of Bitter Almonds. — 26 lbs. of almonds pressed cold, and then distilled with water, gave 10^ lbs. of fat, and 2 ounces of volatile oils. 2. Ol. Anisi aeth. — 16 lbs. of anise seeds gave 7 ounces of volatile oil, and 10 lbs. 2| ozs. of the same, spec. grav. 0*984. 3. Ol. Anisi stellati. — 10 lbs-- of the seeds gave 22 drs. volatile oil. 4. Ol. Calami aromat. — 14 lbs. of dry roots left 20 ozs. volatile oil; 118 lbs. fresh roots were peeled, and the 45 lbs. of bark left by- distillation 3| ozs. of oil ; the roots, when dried, weighed 13 i lbs. 5. Ol. Carvi. — 15 lbs. of the seeds gave .7 ozs. oil; 10 lbs. gave 7 ozs. of spec. grav. '915 6. Ol. Caryophyl. aromat. — 1 lb. gave 20 to 21 drs. 7. Ol. Caryophyl. — 6^ lbs., when distilled three times, gave 18| ozs. oil of spec. grav. 1*232. 8. 01. Cerae. — IJ lb. Cer. flav, gave, by dry distillation, 5 ozs. 5 drs. of oil. 9. 01. Coriandri. — 32 lbs. of the seeds gave 2 ozs. 7 drs. oil. 10. Ol. Cynae sem. — 165 lbs. of the seeds left 14 ozs. 3 drs. oil. 11. Ol. Oynae. — 5 lbs. seeds of Cyn. levant, gave 4 drs. 1 sc. oil ; I lb. seeds of Oyn. lev. gave 10 drs. Ext. Cyn. aeth. ; 2J lbs. Sem. cyn. barh. gave 3 drs. 50 grs. oil; 13 lbs. Sem. cyn. natur. left 2| lbs of an earthy powder effervescing with acids. 12. 01. Foeniculi. — 12 lbs. seeds gave 5 drs. oil. 3 lbs. seeds gave 14^ drs. oil spec. grav. 0*968. 13. OL Junip. bacc. — 21 lbs. of fresh berries left x6 drs. clear oil. 14. Ol. Macis. — 1^ lb. mace gave 18^ drs. oil of spec. grav. '920. 15. Ol. Ma7'joranae. — 82 lbs. left 11 ozs. oil. 16. Ol. Menth. piperit. — 374 lbs. of the plant gave 49| ozs. 17. Ol. Petroselini. — 4 lbs. seeds afford 1^ oz. of an oil sinking to the bottom of water. 18. Ol. Sinap. Sem. — 35 lbs. gave 11 drs. of oil, and by other experiments, 15 lbs. gave 6 drs., and 50 lbs. gave 31 drs. The greatest product was 8 drs. oil from 10 lbs. 19. Ol. Aether Tanacet. — 20 lbs. of the tops gave 1 oz of oil. 20. Ol. Valer. aether. — 10 lbs. of the root gave 12 drs. oil, and 22 lbs. gave 18^ drs. of oil spec. grav. -960. — Central, blatt., June, 1836. 3. Morphin in Native Green Poppy Heads. — According to Du Menil, morphin exists in common poppy heads, but in small quantity. He evaporated the expressed juice of the poppy head in a water bath to the consistence of honey, exhausted the residue with spirit of 80 per cent, slightly rendered acid by sulphuric acid, dis- tilled the greenish solution, added water to it, filtered it, neutralized the solution with ammonia, although not completely, precipitated it by a solution of galls, collected the precipitate, washed it, digested it with lime water, dried the mixture in a water bath, pulverized it, digested it with spirit and distilled. The residual solution left behind a very small quantity of a resinous matter (3 lbs. poppy heads gave I gr.), which taste^l somewhat bitter, and was coloured scarlet by concentrated nitric acid, and blueish by chloride of iron. — Ibid., August, 1836. 472 Scientific Intelligence, Sfc. IV. — ^a.sT/ Method of preparing Spongy Platinum. If native platinum is fused with double its weight of zinc, the result- ing alloy reduced to powder, and treated first with dilute sulphuric acid, and then with dilute nitric acid, in order to oxidize and dissolve all the zinc, an insoluble residue is obtained, consisting of platinum in the form of a grayish black powder mixed with an osraiuret of iridium, which not only possesses the same properties as platinum after it has been properly purified by washing with caustic potash and water, but has such an oxidizing power that it converts formic acid into carbonic acid, alcohol into acetic acid, and even the osmium contained in it into osmic acid. This plan was pointed out by'Descotils more than 30 years ago ; but he was not acquainted with its powers. He did not inquire into the cause of its detonating like gunpowder, and the effect of taking away this property which muriatic acid possesses. Berzelius supposed that it was combined with hydrogen ; but Dobereiner's experiments have shewn this opinion to be quite erroneous. If platinum, separated from zinc, is slightly moistened with alcohol, it inflames, or rather becomes incan- descent, and disengages osmic acid ; but if the alcohol is mixed up into a paste with it, the circumstances are altered, and acetic acid alone is formed. This is the simplest'method of purifying the air of a room, and of removing the odour of nicotine. — Aim. der. Pharmacie, January, 1836. V. — Temperature of Space. At Fort Reliance in N. L. 62^ 46.i, W. L. 109^ 0' 39", Captain Back observed the spirit of wine thermometer to sink as low as — 70 F. Arago concludes from this that the temperature of space must certainly be under — 70° '6. Poisson, however, does not admit this conclusion, for according to him the temperature of the upper stratum of air is considerably lower than that of space. — Poggen^ dorjfs Ann., xxxviii. 235. VI. — Acid Beer. A PATENT has been taken out by Mr. S to well, in America, for pre- venting beer from becoming acid in hot weather, or between the temperatures of 74° and 94°. To every 174 gallons of liquor we are directed to apply one pound of raisins, in the following manner. " Put the raisins into a linen or cotton bag, and then put the bag containing the raisins into the liquor before fermentation. The liquor may then be let down at G5^ or as high as 70°. The bag containing the raisins must remain in the vat until the process of fermentation has so far advanced as to produce a white appearance or scum all over the surface of the liquor, which will probably take place in about 24 hours. The bag containing the raisins must then be taken out, and the liquor left until fermentation ceases. The degree of heat in the place where the working vat is situated should not exceed 66 ' nor be less than 60°." To prevent distillers wash from becoming acid, two pounds of raisins should be put into 150 gallons Scientific Intelligence, Sfc. 473 of the wash, the raisins being chopped and put in without a bag, and 1 lb. of hops should be put into the wash vat for every 8 bushels of malt at the time of mashing, and ^ of a pound of hops for every bushel of malt brewed, to be boiled in the liquor in the copper.— Journal of the Franklin Institute j Sept., 1836. BOOKS ANNOUNCED OR NEWLY PUBLISHED. Just Published, The British Annual and Epitome of the Progress of Science, Edited by Robert D. Thomson, M.D. The plan of this work is similar to that of the Annuaire jjar le bureau des longitudes, which has gained great popularity in France. The first part of the British Annual is occupied with a calendar for the year 1837. This is followed by Divisions of Time, Tables of the Elements of the Solar System, Positions of Observatories, Heights of Mountains, &c.. Complete tables of English, Swedish, French, German, and Portu- guese Weights and Measures ; principal foreign Commercial Weights and Measures ; Tables of the Coins of different Countries, with their Weights ; Tables for calculating the Altitude of Mountains from Barometric Observations ; Tables of the Specific Gravity and Atomic Weights of Bodies; Universities of England, Scotland, France, Denmark, with the incomes of the Professors ; American Colleges ,- Lists of the office bearers of the different learned societies, with the fees ; Statistics of Glasgow, for 1832, by Dr. Cleland, &c. The second part of the Annual contains, Recent Progress of Optical Science, by the Rev. Baden Powell, M.A., F.R.S., Savilian Professor of Geometry, Oxford. Experiments and Observations on Visible Vibration and Nodal Division, by C. Tomlinson, Esq., &c. History of Magnetical Discovery, by Thomas Stephens Davies, F.R.S., L. & E., F.R.A.S., of the Royal Military Academy, Woolwich. ReccJit Progress of Astronomy, by W. S. B. Woolhouse, Esq., F.R.A.S., Head Assistant of the Nautical Almanac Estab- lishment. Recent Progress of Vegetable Chemistry, by Robert D. Thomson, M.D. The original edition of the Antiquities of Athens, by the celebrated Stuart, is now in course of publication, so arranged that each Edifice is complete in one Part, with brief explanations of the Engravings, by this means the Student may consult the first authority in any particular order of Grecian Architecture, separate from the rest of a work of twenty-four guineas value, and now very scarce. The Report of Sir David Barry and Dr. Corrie, on the Medical Charities of Ireland, is now published. These gentlemen were appointed by Government, Commissioners for investigating the Ma- nagement of Hospitals and Asylums. o .•Sdl bo O > (C 9 .s is ^' ' s C3 ,§ a>^ > •2S-gja S s o o .5 .5 a> k O . 11 . 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