s>^~ JOURNAL OF NATURAL PHILOSOPHY, CHEMISTRY, AND THE ARTS. VOL. H. 1—1 I Ml MIT" 3itlustratet> t»it& Cngratimss, BY WILLIAM NICHOLSON. LONDON: PRINTED BY \V. STRATFORD, CROWN-COURT, TEMPLE-BAR; FOR. THE AUTHOR, No. 10, SOHO-SQUARE; AND SOLD BY G. and J. ROBINSONS, PATERNOSTER-ROW, 1802* I PREFACE. MEET my Readers and Correspondents at the comple- tion of this Second Volume, with the satisfaction of directing their notice to the still greater increase of communication, and the means of rendering this work most eminently inte- resting and useful. It is not necessary that I should recapi- tulate the outlines of the plan and rules of conduct by which I have endeavoured to deserve the encouragement of the Public; but I think it truly justifiable to exhibit the marks of that approval at the same time that I express the sensibi- lity with which I accept them, and the spirit they must afford to my labours. Without entering into any estimate of the quantity of ori- ginal matter in this work, which from the high value of its correfpondence is now become the authentic repository of the researches of our philosophers ; I will only notice, that the number of original writers in this Volume is more than double that of the refpectable list prefixed to the first Volume, at the same time that the value and importance of the Me- moirs from foreign and domestic publications have continued to increafe. The authors of original Papers are Mr. F. Accum ; A. B. C; John Bostock, M. D. J. W. Bos well ; Count de Bournon; H. Campbell, M. D. ; R. Chenevix, Esq. ; Mr. John Clen- nel 3 C. P. ; Mr. Wm. Close ; W. Cruickshank, Prof, at Woolwich ; John Cuthbertson ; D. H. ; J. Fletcher, Efq. G. H ; John Gough, Esq. ; Mr. Olinthus Gregory ; J. C. Hornblower; Rob. Jameson ; J.; Rev. W. Pearson; N.N. Joseph Priestley, L.L.D. F.R.S. &c; H. Sarjeant, Esq.; Mr. Tho. Sheldrake; Dr. J. H. Schroeter; Tho. Thomson, M.D.; Mr. Trevithick ; Troughton; Ez. Walker; Rev. James Wilson, D.D. James Woodhouse, M.D.; Mr. Ar- thur Woolf; Thomas Young, M. D. Prof. P. R. I.; Baron von Zach; and W. N. — Of foreign works, Carcel ; Carreau; Coulomb ; Descroizilles ; Guillot ; Guyton ; Hassel Lache- naie; Lalande; Picket; Proust; Valentine; Vaiiqnelin.— • And of English Memoirs abridged or extracted, Mr. Banks; Wm. Bullock; Sir H. Englefield, Bart.; Mr. Gilpin; J. Gough, Esq.; Ch. Hatchett, Esq.; Wm. Herschel, L.L.D. Ed; Howard, Esq.; Hulme, M.D.; E. Jones, Esq. H. Sarjeant, Esq. The novelty and excellence of the communications with which fri$ Journal has been honoured, haye been produc- tive Preface. tive of an effect which I have seriously meditated to remedy In the limited extent of every work of this nature, when the new and interesting Memoirs demand a larger portion of its capacity, a smaller must of course be devoted to less striking, though doubtless very important business of selection. Fo- reign and domestic matter must be more fastidiously sorted out ; articles must be abridged instead of being given at full length; and some must be rejected altogether that would have been highly acceptable, if the original productions could have allowed room. Two remedies present themselves. The first is to print a supplementary number to each volume; and the other to give a greater number of pages without adding to the price. I shall be happy to adopt the latter as soon as the increased fale shall have rendered it practicable, without diminishing the ordinary remuneration the Work affords; and in case the former should prove necessary or advisable, I am confident my Readers will see the advantages and approve the proceeding. In the mean time, the private recommendation of men of merit to their friends, is the best means of accelerating that circulation which will eventually benefit its patrons, by the greater quantity of them that could in that case be afforded. I conclude this Preface as usual, by mentioning the fub- jects of the sixteen Plates which illustrate the present Vo- lume. 1 . Improvements in Hydraulic Engines, by Mr. Boswell. 2. Guyton's Improvements of the Swedish Stove. 3. Mr. Sarjeant's cheap Engine for raising Water. 4. Strong framed Levers for Steam Engines, by Mr. Hornblower. 5. Dr. Young's Diagrams to illustrate the Theory of Light. 6. Mr. Gregory's Figure for Mr. Pearfon's Analogy. 7. Mr. Gough's Illustration of the Do£irine of Sound. 8. Mecha- nical Lamp of Carcel and Carreau. 9. Mr. WoolPs Appa- ratus for heating Water by waste Steam. 10. Mr. Terry's improved Mill. 11. Mr. Bullock's Lock. 12. Count Bournon's Figures of Anhydrous Sulphate. 13. Mr. Trevi- thick's Application of a temporary Forcer. 14. Lachenaie's Apparatus for claying Sugars. 15. Mr. Jameson's Illustra- tion of the Formation of Granite. 17. Mr. Banks's Instru- ments for determining the Pressures and Velocities of effluent Air or Gas. 18. The Spirit Hydrometer and Scales of Atkins. And, 19. Compound Condensers of Electricity, by Mr. Read and Mr. Cuthbertson. $iho Square, London, September I, 1302, TABLE OF CONTENTS TO THIS SECOND VOLUME. MAY 1302, I' NGRAVINGS of the following Objefts : 1. Mr. BofwelPs Improvements Jri the Hydraulic Engines at Schemnitz, of Mr. Goodvvyn, and that which a£ts by Prtilure j 2 and 3. Two Coppe,-" Plates to exhibit the economical SwediHi Stove, as conftrucled by Guyton ; 4, Mr. Serjeant's very cheap Engine for railing Water for Domeftic Purpofes. I. Improvements in the Hydraulic Engine of Schemnitz, and in that of Mr. Goodwyn ; with comparative Remarks on the moftufeful Applications of each, and fome Fails relative to the Invention, of the prerTure Engine. In a Letter from Mr. John Whitley Bofwell. - - Page I II. Remarks on the prefeilt State of Paper- making in England and France. By H. Campbell, M. D Communicated by the Author. 6 III. Remarks on CombufMon, by Thomas Thomfon, M. D. Lecturer on Chemiftry in Edinburgh. - - - - 10 IV. Some Account of a new Planetary. Body, difcovered by Dr. Olbers, on the 28th of March, 1802. - 20 V. On Bradley's Method of obferving Tr nfits, and another Method by which the Thicknefs of the Wire is rendered of no Importance. In a Letter from Mr. Ezekiel Walker. - - 22 VI. Defcription of a Stove on the Principles of the Swedifh Fire-place, with Heat-openings, by Citizen Guyton. 24 VIL A Continuation of the Experiments and Obfervations on the Light which is fpontaneoufly emitted from various Bodies ; with fome Experiments and Obfervations on Solar Light, when imbibed by Canton's Phofphorus. By. ' Nathaniel Hulme, M.D.F.^R.S. and A. S. - - - 31 VIII. Caution againft the great Danger of keeping Phofphorus in Bottles with- out particular Caution. By Deicrozilles the Elder. - 41 IX. Obfervations in Anfwer to Dr. Priertley's Memoir in Defence of the Do&rine of Phlogifton. In a Letter from Mr. William Cruickflianks. 42 X. On the new Planet Ceres. - - - 48 XI. Defcription of a very cheap Engine for railing Water. In a Letter from Mr. H. Sarjeant, of Whitehaven, to Mr. Taylor," Secretary to the Society for the Encouragement of Arts. - - - GO XII. Concerning the Indentity of Tellurium and Antimony, the galvanic Effects of Magnetifra, and other Philoibphical Subjects. By a Correi'pon- dent. - 62 Scientific News. Notice refpe&ing the Difcovery and Situation of chromateel Iron in France. - 6*4 Books of Science. A Treatife on Aftronomy, in which the Elements of that Science are deduced in a natural Order, from the Appearances of the Heavens to an Obferver on the Earth ; demonstrated on Mathematical Principles, and explained by an Application to the various Phenomena, - ib. Vol. II.— 1802. a JUNE ii CONTENTS. JUNE 1802. Engravings of the following Objects : 1. Strong framed Levers for Steam En- gines, by Mr. J. C. Hornblower, and others; 2. Diagrams by Dr. Young, to explain the Nature and Properties of Light; 3, 4. Figure by Mr. Gre- gory to demonftrate Mr. Pearfon's Analogy for deducing ths greateft Equa- tion from the Eccentricity : and another by Mr. Gough, for fhewing how we perceive the direction or' Sound. And, 5. Anew Lamp by Melfrs. Caret! and Carreau, in which the Oil is raifed mechanically. J. On the Rev. Mr. Pearfon's Analogy for deducing the greateft Equation from the Eccentricity. In a Letter from Mr. Olinthus Gregory. Page 65 II. On the Conftruclion of the Beams of Steam Engines. By Mr. J. C. Horn- blower. From the Author. - - 68 HI. On the Theory of Chemiftry. In a Letter from the Rev. J. Prieftley, L. L.D.F. R. S. &c- .... 69 IV. Experiments upon the tanning Principle, and Reflections upon the Art of Tanning. By Cit. Merat Guillot, Apothecary at Auxerre. 70 V. On the Defhuction of the Grub of the Cock-chafer. By Edward Jones, Efq. of Wepre-Hall, in Flint/hire. - 73 VI. Methods of diminifhing the Irregularities of Time-Pieces, arifing from differences in the Arc of Vibration of the Pendulum. By Mr. Ezekiel Walker. - - - - .76 VII. On the Theory of Light and Colours. By Thomas Young, M. D. F. R.S. Profeffor of Nat. Philof. in the Royal Inftitution. - 73 VIII. Remarks on Combuftion. By T. Thomlbn, M. D. Lecturer on Che- miftry in Edinburgh. - - - 92 IX. A Continuation of the Experiments and Obfervations on the Light which is fpontaneoufly emitted from various Bodies; with ibme Experiments and Obfervations on folar Light, when imbibed by Canton's Phofphorus. By Nathaniel Hulme, M. D. F. R. S. and A. S. (Concluded from page 40.) 100 X. Defcription of a Lamp upon Argand's Principle, with Improvements, in which the Oil is maintained at the lame Level by the conftant Action of a Pump. By Citizens Cared and Carreau - - 108 XI. Note upon a peculiar vegetable Principle contained in Coffee. By Richard Chenevix, Efq. F. R. S. M. R. I. A. From the Author. 114 XII. Account of fome Experiments performed upon a Scale of confiderable Magnitude, and principally by the Agency of Froft, to produce Sulphate of Soda, Carbonate of Magnefia, and Muriate of Ammonia, from Sulphate of Magnefia, Carbonate of Ammonia, and Muriate of Soda. By H. Camp- bell, M. D. From the Author. - - - 117 XIII. Note of Citizen Vauquelin refbe&ing the Boracite, called Magne- fio-calcareous Borate by the French Chemiils. - - 120 XIV. Facts and Obfervations tending to explain the curious Phenomenon of Ventriloquifm. By Mr. John Gough. - - 122 XV. An Analyfis of a Mineral Subftance from North America, containing a Metal hitherto unknown. By Charles Hatchett, Efq. - 129 XVI. Remarks on the Mamoth. By Louis Valentine, Phyfician in Chief cf the Army and Hofpitals of America, of feveraj National and Foreign So- cieties, refident in Nancy. - 138 Scientific News. Prizes of the National Inftitute of France — Afironcmical Prize — Communications to the Royal Society reflecting the Planet Ceres—* Leonardo da Vinci—Experiments to prove that all Bodies, whatever may be their Nature, are obedient to the Action of Mao-netilin, and that this Action is lulBcienny powerrih to aqmit or being meafuredj 141 to 143 JULY CONTENTS, iit JULY 1802. Engravings of the following Objects: 1. A new Apparatus for heating Water to nearly the boiling Point by Means of Wafte Steam, by Mr. Arthur Woolf ; 2. An improved Mill, by Mr. G. Terry ; 3. Mr. Bullock's Drawback Lock j 4. Chryftals of Anhydrous Sulphate, by the Count de Bournon ; 5. Applica- tion of a temporary Forcer, by Mr. Trevithickj 6. Lachenaie's Apparatus for claying Sugars. I* Compofition of Writing Ink, pofTeiTingthe permanent Colour, and other eflen- tial Properties, of the Ink ufed for Printing, In a Letter from Mr. William Clofe. ----- Page 145 JI. Of the Effects produced by the Vegetation of Plants in Atmofpherical Air. 150 III. On the Theory of Light and Colours. By Thomas Young, M. D. F. R. S. Profeflbr of Natural Philofophy in the Royal Inftitution. 162 IV. An Analyfis of a Mineral Subftance from North America, containing a Metal hitherto unknown. By Charles Hatchett, Efq. - 176 V. On the Effeft of Sound upon the Barometer. By Sir Henry C. Englefield, Bart. F. R. S. (From the Journals of the Royal Inftitution, No. 9.) 181 VI. On the Expaniion of carbonated Hidrogtn by Electricity. From a Cor- refpondent. - - - - - 184 VII. A new Procefs for claying Sugars, propofed by Cit. Haffei Lachenaie, Chief Apothecary of the Military Hofpitals of Guadaloupe, to the Agents of the Confuls of the French Republic in the Windward Iflands. 187 VIII. Defcription of the Cryftalline Forms of the Anhydrous Sulphate of Lime, with fome Obfervations on this Subftance. By M. Le Comte de Bournon, Member of the Royal and Linnasan Societies of London. Translated from the Original; communicated by the Author. - - - 190 IX. Analyfis of Natural and Artificial Anhydrous Sulphate of Lime. By Rich. Chenevix, Efq. F. R. S. M. R. I. A. Communicated by the Au- thor. - - - - - - 196 X. Abridgment of a Memoir of Mr. Prouft, on Tanin and its Species. 198 XI. Defcription of an Apparatus for heating Water by wafte Steam. In- vented by Mr. Arthur Woolf. - - - - 203 XII. Defcription of an improved Drawback Lock for Houfe Doors. By Mr. Wm. Bullock. From the Transitions of the Society of Arts, who adjudg- ed a Reward of Fifteen Gutnear, to the Inventor. - - 204 XII I. Defcription of an improved Mill for grinding hard Subftances. By Mr. Garnett Terry. From the Tranfa&ions of the Society of Arts, who adjudg- ed the Silver Medal to the Inventor. - - - 206 XIV. Remarks on Dr. Thomson's Theory of Combuftion. By C. P. (Re- ceived June 15, 1802.) - ib. XV. On certain Points of Nomenclature; By a Correfpondent. 212 XVI. Duplicate Copy of a Letter from Baron de Zach to the Right Honour- able Sir Jofeph Banks, Bart. P. R. S. &c. tranfmitted to Mr. Edw. Trough- ton, and communicated by the Rev. J. Pearfon ; on the new Planet Ceres and Pallas, with the Elements of the Orbit of the former. - 213 XVII. Method of applying a temporary Forcer to a Pump, fo as to produce a conftant Stream. By Mr. Richard Trevithick. From the Author. 216 XVIII. Experiments and Obfervations on certain ftony and metalline Sub- ftances, which at different Times are faid to have fallen on the Earth ; alfo on various Kinds of native Iron. By Edward Howard, Efq. F. R. S. * From the Philofophical Tranfa&ions, 1802. - ib. Scientific News. Dimenfions and Nature of the new Planets Ceres and Pallas. By Dr. Herfchel— Extract of a Letter from the Rev. James Wilfon, D. D. Minifter of Falkirk. - - - - 221 to 222 Recount of Books of Science, Memoirs of the Literary and Philofophical Society ofManchefter, g s ? - . 223 AUGUST iv CONTENTS. AUGUST 1SC2. Engravings of the following Objects: 1. Figures to illuftratc Mr. JamefunV Obiervations on the Formation of Granite; 2. Mr. Banks's luftruments for determining the PreflTurCS and Velocities of effluent Air or Gas ; 3. The Spirit Hydrometer and Scales of Atkins; 4. Compound Condenfers of Electricity, by Mr. Read and Mr. Cuthbertfon. I. On Granite. By Mr. Robert Jamelbn. Communicated by the Author. Page 225; }1. Obfervations on the Conversion of Iron into Steel. In a Letter from Jofeph Prieftley, L. L. D. F. R. S.&c. &c. ' - - - 233 JII. An Account of the Art of making Glue. In a Letter from Mr. John Clennel. - - - - - - 235 IV. On the Preparation of Indelible Ink. In a Letter from Mr. Thomas Shel- drake. - - - - - - 231 V. Obfervations on the Caufes why a large Quantity 0f common Salt pre-* vents Putrefaction, and a fmall Quantity haflens it. By D. H. 249 VI. Account of the Methods by which Soda is at prefect prepared for the Englifh Market j with other Obfervations. By Mr. Fred. Accum. From the Author. - - - - - 24) VII. Comparifon of the French definitive Metre with an Englifh Standard* brought from London by M. A. P idler, one of the Editors of the Bibliotheque Britannique. '- - - - - 244 VIII. On the Figure of Sulphate of Barytes, and the Formation of Man^ drcporce. In a Letter from Mr. H. Sarjeank - - 253 IX. Experiments and Obfervations on certain ftony and metalline Subfhnces, which at different Times are faid to have fallen on the Earth; alio on va- rious Kinds of Native Iron. By Edward Howard, Efq. F. R. S. From; the Philofophical Tranfaftions. 1802. - - - 254 X. An Anfwer to Mr. Gough s EfTay on the Theory of Compound Sounds. By Thomas Young, M. D. F. R. S. - - - 26* XI. Experiments on the Velocity of Air iffuing out of a VefTel in different Cir- cumftances; with the Defcription of an Inftrument to meafure the Force cf the Blaft in Bellows, &c. By Mr. Banks, Lecturer in Natural Fhilofo- phy. - - - -' 269 XII. On the Variation of Rate in a Time Piece, as indicated by the Changes in the Arc of Vibration. In a Letter from Mr. Ezekiel Walker. 273 XIII. Defcription of Atkins's Hydrometer for afcertaining the fpecific Gra- vities of fpirituous Liquors. By J. Fletcher, Efq. Communicated by the Author. - - - - 21ci XIV. An Examination of Sig. Volta's Experiments which he calls funda- mental, and upon which his Theory of Galvanifm refts; with a Defcription of a very fenfible Electrical Condenfer, and an Explanation of the Airion of the Electric Fluid in the Galvanic Inflrument. By John Cuthbertfon, Phil lofophical Inftrument Maker, No. 54. Poland Street, London. Communi- cated by the Author. - - - - 281 XV. Obfervations on the Phofphorefcence of the Tremolite, and of the cal- careous Phofphate of flow Solution, known by the Name of Dolomie. By M. Ie Comte de Bourn' n, Fellow of the Royal and Linnaean Societies. Tranflated from the Original; communicated by the Author. 290 XVI. Outline of the Hiftory of Galvanifm; with a Theory of the Action of the Galvanic Apparatus. By John Boftock, M. D. From the Author. 29§ A JOURNAL OF NATURAL PHILOSOPHY, CHEMISTRY, AND THE ARTS. MA Y, 1802. ARTICLE I. Improvements in the Hydraulic Engine of Schemnit*z, ana that of Mr. Goodwyn; with comparative Remarks on the moft ufeful Applications of each, and fome Facts relative to the Invention of the preffure Engine. In a Letter from M\\ John Whitley Boswell. To Mr. NICHOLSON. S I R, London, March 14. 1802. AVING, with much fatisfaction, found that the method Method of H of making the Schemnitz hydraulic engine work itfelf, which working engines t r , , , , . .-.'• by the bucket I gave you lor your excellent Journal in J 800, (IV. 1 17.) and fyphon. has been iince found of confiderable utility in * other works of a fimilar nature, I am induced to fend for your approbation a draft of the f application of the fame principle to Mr. Good- * Vide Mr. Clofe's papers in the fame Vol. f The paper figned L in the quarto Journal, page 343, though it profeffes to (hew how Mr. Goodwyn 's engine may work itfelf, has only hinted at this method, but has not (hewn how it may be effeaed. Vol. II.— May, 1802. B wyn's IMPROVEMENTS IN HYDRAULIC ENGINES. wvn's engine, and another of a method of caufing the Schem- nitz to raife water above the level of the prime refervoir, to- gether with a comparative view of the advantages of both engines and their powers. Concife cxpla- After a perufal of my former Paper on the Schemnitz en- Schemnitf en- ginC' ^IV' U4'^ * mCre infPeaion of the %ure given here ginc. (Plate I.) will be fufficient to fliew the manner in which this now propofed will operate. The moving power is the pref- fure of the column of water from the refervoir R, (Fig. 1.) to D in the lower air chamber A, which forces the air contained in it into the chamber B, which air fo comprefied in B will impel the water contained in it upwards through the pipe to a height, and in a quantity proportionate to the relative height of the column of water contained in the pipe R D, compared with that contained in SB, or iuppofing the length of R D given, the greater the length of the pipe S B is, (fo as not to exceed R D,) the lefs will be the quantity of water deli- vered at S, and vice verja. Mr. Goodwyn's In the draft of Mr. Goodwyn's engine, Fig. 2. I have en- *:ngl"e 5 !:on" deavoured to exhibit it as it fliould be if executed on a large ftructed for ° heavy work, fcale, and made all the pipes detached from each other, be- and made to ope- caufe though the plan of making one pipe pafs through an- tendance. other and through the refervoirs, made ufe of in Mr. Good- wyn's model, is very convenient and neat in an apparatus that may be placed on a table, yet it would be found to pro- duce an unneceflary trouble, complication and difficulty of repair in a large engine. The method (hewn in this draft of caufing the engine to work without attendance, is the fame as for the Schemnitz, and caufes the cocks G and H to open at intervals, (which may be regulated at pleafure by the hand cock I, letting the water flow more or lefs quick into the {y- phon veflel E,) while at the fame time it clofes the cock at D, and vicevcrjb. Self-moving valves are placed at the deliver- ing pipes of the chambers C and B, and alfo at the air vent of A, becaufe wherever they can be ufed they are preferable to cocks, or valves ufed by external power ; ibme doubt may arife, whether there fliould not be a palTage for the air let at intervals into A, as well as one for it to efcape : but as great quantities of air are contained in water, which the mode of working of this engine will particularly tend to feparate from it, I think it would be needlef and that the felf-moving valve IMPROVEMENTS IN HYDRAULIC ENGINES. 3 valve opening outvWs at the air vent of A will be fufficieht. The pipe at K is t< conduct water from the bucket F to that of the cock D. T.ere are two ranges of refervoirs reprefent- ed, to fhew the mithod of raifing water by this engine about thirty feet high : aore would be ufelefs, and even a fecond would in very fewinftances be found neceffary, except when the fall of water fr«m R to D was very fhort, in which cafe it would be better ttiufe fome other engine for railing water to the required heigh. In comparing tbfe two engines, it will be found that their Comparlfon of powers and capacities are nearly fimilar. the powers of 1 . In both the greater the height of the original fall of wa- g;nes 5 numeri- ter, denoted by tlfe pipe R D, and the greater the quantity eally ftated« of water which if can fupply in a given time, the greater quantity can be riifed by thefe engines in a given time. 2. Both engires can be conftru&ed fo as to raife water above the origiml level, and from below to the furface, or from a pit. I 3. By a fuccdfive number of refervoirs both engines can be brought to rife water to any height ; but as they will raife a fmaller quaniity as the height is increafed, the quantity wanted in a givsn time, and the expence of conflruclion, will limit the extent of their elevation. 4. In both engines the diftance from one refervoir to an- other, muft alvays be lefs than that of the original fall RD. The circumftanres in which thofe engines differ arife from, the difference of their manner of action. 5. The Schennitz engine operates by caufing a fall of wa- ter to comprefs ail, which re-a6ting on other water forces it to rife in a pipe to a certain height. Mr. Goodwyn's engine a<5ts by caufing a fall of water to rarify a certain quantity of air, into whofe fpace the preffure of the atmofphere forces, when permitted, a quantity of water. 6. Hence in the Schemnitz engine, the preffure acting from within outivards, tends to burfi the veffels ufed in the ftructure, and to open and extend any fifTures which may chance to be in them. 7. In Mr. Goodwyn's engine the preffure acting from with- out inwards, clofes all the parts of which it is compofed more together, tends to make its pipes and veffels more ftaunch, and in any fiflure makes its fides operate like valves to fhut it up. B 2 3* The 4 IMPROVEMENTS IN HYDRAULKENGINES. 8. The Schemnitz engine will always raife water to a. height nearly equal to that of the original all, from one refer- voir to another, fuppofing th^original fallof any height what- foever, as 100 feet. Mr. Goodwyn's engine will not raife w;ter from one refer- voir to another fo high as thirty feet in aiy cafe whatfoever, as there cannot be a complete vacuum ibrned by it in the air chamber, but only an approximation to one Mr. Go(vJwyn*s From this companion it will follow, tha wherever the on- preferable1, and 8ma* ^11 °^ water *s tefil than thirty-two fee, Mr. Goodwyn's leaft coftly in engine will be much preferable to the Scheimitz ; as, from the (mail elevations. ?th artic.e 0f the compar;fon, ft mav be mide of the cheapeji materials, of ftrong iionden cajks and ivooien pipes ; whereas the Schemnitz engine, from the 6th article, mull be made of the ftrongeft, and of courfe molt coftly materials, of caft iron at leaft, and that of confiderable thicknefs. The Schemnitz But wherever the original fall exceeds tin height of thirty greater depths. ^eefc much, and it is required to raife the waer to nearly the fame height, then the Schemnitz engine appears to be pre- ferable ; as, in all probability, the fewer lumber of parts which it will, in this cafe, require in its conftri6tion, will more than compenfate for its coftly materials. Pifton engine When it is required to raife water to a heiglt, much greater g!fat°depeths. than that of the original fall, above the firft evel, or from a greater depth ; either from the original fall beng ftiort, or the required height being great, an engine in which the preffure of the water is made to act by a pifton in an apparatus limilar to that of the fteam engine, (one of which is defcribed in your • Journal for March) will be preferable to either of the above. Comparifon of The comparison of thofe engines may be brought to this one eines.reeen" point: wherever Mr. Goodwyn's engine can be ufed, with a fingle continued pipe for elevating the water, and without a fucceflion of refervoirs, it feems to be the cheapeft. Where Mr. Goodwyn's engine cannot be ufed without viola- ting this condition, but the Schemnitz can, it promifes to be the next in point of cheapnefs, from its fimplicity, abfence of friftion, and fmall number of working parts. But when neither Mr. Goodwyn's engine nor the Schemnitz can be ufed without a number of refervoirs, then the pifton preffure engine probably ought to be preferred ; but this will much depend on the number of refervoirs, for perhaps one or two IMPROVEMENTS IN HYDRAULIC ENGINES. 5 two in addition to the Schemnitz might coft Iefs, than boring the cylinder of the pifton engine perfect, and its additional machinery : for merely raifing water the powers of each are nearly equal, depending all on the height of the original fall of water. The great advantage of the pifton prefliire engine is, not The preffiure en- as a cheap engine for raifing water, but as that in which a fall g1"® vv° » f of water can be applied without any wafte to work mills or water, machinery for any purpofe ; which is of very great confequence when the fall of water is of confiderable height, and the ftream, or fupply, fmall. Conceiving it of very great importance to have it deter- Great Import- mined in what fltuations each of the principal engines, worked a.nce of comPa- by water preilure, is to be preferred, I have commenced this rent methods of comparifon, and if this fliall be acceptable, will fend another aPP]ying water paper on a fimilar fubject ; that is, on the comparifon of the Wheel work common mill water wheel, with another mode of applying &c. the water to turn mill work, which, I think, I can demon- ftrate to be much preferable. I hope what I have thus began will excite fome others to the fame enquiry ; and that by this means the multiplicity of water preifure engines will be at laft arranged, and their comparative utility afcertained, fo that in every different cafe of fall or fupply of water, an engineer may know at once which he mould ufe. I beg leave to add here fome remarks on the pifton prefliire Mr. Trevl- engine in your Journal for March: Mr. Trevithack will, I tha?k's Prefl*ure hope, excufe my taking from him the honour of his being theCuted in 1731 firfl inventor of this mode of applying a fall of water, to giveby Denifard and. it back to MefTrs. Denifard and Deuille of France, when I im^ineTby Mr. confcfs that for a long time I was in the fame error with him, Bofwellin 1796* and thought it had firft occurred to me, and propofed it with that idea to Mr. Carnac in Nov. 1796, to draw the water from his copper mine, (by which he would have faved the daily labour of twenty men, as he had a fall of water very proper for this engine — a fact which I have Mr. Carnac's fignature to prove;) but I fince found out that in Belidor's Defcribed In Hydraulic Architecture, publithed at Paris 1739, in the fourth Belidor* book and firft chapter, there is a method defcribed at large, with very well executed plates, by which a fall of water ope- rating in a cylinder on a pifton may work a pump to force water to a greater height j and what is remarkable, Belidor 2 propofes 6 IMPROVEMENTS IN HYDRAULIC ENGINES. propofes the very fame method of working the valves by a tumbling weight, as that called the tumbling bob, in Mr. T's defcription. In Belidor's engine the pifton cylinder and pump are both horizontal, which is the molt material diffe- rence, but the principle is entirely the fame as Mr. Trevi- thack's. Mr. Belidor does not claim the honour of this invention, but only propofes the engine I allude to, as an improvement on one executed on the fame principle at Seve, between Verfailles and Paris, in the year 1731, by Denifard and Deuille, for which they obtained a patent from the king of France for twenty-one years ; of which engine there is alio a defcription in the fame chapter of the above work. Propofa! of air I beg leave to fuggeft, that it might be a conliderable im- pfftonT" ln thC Provement to tnis engine to have its aftion made elaftic, by the addition of an air chamber, on the fame principle as that ufed in engines for extinguifhing conflagrations ; fuch a one, feems to me, might be beft effected by making the pifton hollow, and of a larger fize, to ferve for this purpofe, as the air fpring would then act both on the upper and lower pref- fure of the water ; Figure 3 is a fketch of this method, in which A reprefents the hollow pifton. I hope the length of this paper will be excufed by the circumftance of my not having received your Journal for March till I had written the moft of it, and having had of courfe, to add the remarks on the pifton preflure engine to the reft. I am, SIR, &c, W. H. B. II. Remarks of the prefent State of Paper-making in England and France*. By H. Campbell, M.D. Communicated by the Author, March 26, 1802. Whether the ad- J[ HE additional duty on Paper has not been the chief caufe :iona uty on ^ ^e diminution 'm tne book and paper trades of this country. paper nas pun- * ■* •> cipally injured After book trade. * The importance and authenticity of the chemical, mechanical, and other facls ftated in this Memoir, and of the object itfelf in general REMARKS ON PAPER MAKING. 7 After eftablifhing this facl, it will be equally evident that the paper and book trades will not be effectually relieved by giving up a part, or the whole of the laft additional duty. The former administration of this country by impofing an France has fuc- additional duty, did not teach the French the new art of ceeded by im" J ' provements in paper making ; nor did it fupply them with abundance of raw the arts of paper material ; or fliew them the art of equalizing the different making and qualities of rags by ChaptaPs mode of bleaching ; — neither was any new light thrown by the additional duty upon the mode of printing and type cafting, as now practifed in France. Before the commencement of the late war, paper-making The Britifli fine in this country, ftriclly fpeaking, was a mechanical art. The ?aPer ,f?rmer,y fuperiority of Englifh paper arofe from the fuperior linen the finenefs of worn by Englifh people. Their rags were fuperior to the our llnen raSs > rags collect ed on the continent. The decency of the Englifh populace, compared with the populace on the continent, could not be better fhewn than by an exhibition of Englifh and foreign rags. Rags called London fines, the refufe of Irifh linen, &c. could fcarce be equalled in any other coun- try. The original linen of thefe rags had been highly bleached. They were confequently calculated to make the fineft and whiteft paper. Rags at an Englifh paper mill previous to the war, were forted according to their colour and finenefs. and our careful Pains were taken to cut off the feams and offal parts ; and fortmS them« thefe parts were deftined to make inferior paper. This ftate- ment alone is almoft fufficient to give a clear notion of what I am about to eftablifh. I conceive that a reprefentation of the mechanical necejfaries, Our machinery, as the dufler, the knives placed in the engine roller, the plate, the vat, the moulds, and laflly, flannels and preffes, although indifpenfible in a paper mill, are neceffary to be noticed in this account ; as an imitation of them in France, could not contribute to the prefent alarming change in our paper trade. The Englifh flaple, fuperior rags, Englifh cleanlinefs in attempted to he cutting and afforting, and better engines and knives, confli- *ransferrcd *° general to the progrefs of fcience and literature, leave no doubt re- fpecling the propriety of inferting it in our Journal, though its moft prominent feature relates to political regulation. On this laft fubjeel my conduct as a Journalift cannot be fuppofed to exprefs any opinion as an individual. «--N. tuted French rags are coarfe cotton. French paper for copper plates. New aera in paper making. The bleaching procefs by ox. mur. acid. Coarft cotton rags are brought to an equality with fine linen rags by that procefs. A plentiful and cheap fupply of cotton rags. REMARKS ON TAPER MAKING. tuted our fuperiority. About the year 1789 and 90, certain refpeclable Englifh paper makers endeavoured to take thefe advantages to France. France apparently required them ; her coarfe foul cotton rags were not made better by feparation and aflbrtment ; her engines were deficient, and her mills exhibited no mark of profperity, but every fy mptom of flo- venly neglect. One fort of paper, notwithstanding the want of colour and cleanlinefs, Aie excelled in, upon neceffity. I mean paper for copper plate prints ; the necefTarily excelled becaufe her flaple cotton rag being more bibulous, received better im- preffions from the plate. This was the ftate of her paper trade and mills in the year 1789. Before that period, (lie did not confume all her own rags. We received a confiderable part from the cellars of Dunkirk and Oftend, and from coun- tries in her fouthern vicinity, Leghorn, &c. About this time a new aera in paper making commenced. Chemiftry by her difciples, Scheele, Bertholiet, and Chaptal, from a metallic oxide, folicited and directed the concentrated and pure part of the atmofphere, oxigen, to remove with ex- pedition the colouring part of cloth, or rags made from vege- table fubfrances, fuch as flax, cotton, hemp, &c. An atten- tion to the bell: bleaching procefs ought certainly to form a material part of the confi derations in this Paper ; becaufe this object, connected with a knowledge of the forts of rags fuit- able for bleaching, and making printing paper, would give that comprehenfion of the evil from which might be drawn — not fteps of temporary and unavailing expedience, but folid foundations of relief. The bufinefs under confideration is more intimately con- nected with printing than with writing paper. The bleaching gas is much better adapted to coarfe cotton rags than coarfe linen or hempen rags ; becaufe the former is without ligneous particles, and the latter abounds with them, and thefe parti* cles, called by paper makers JJieaves, are made more confpi- cuous by bleaching. The ftaple of our opponents the French, conlifts in coarfe cotton rags. I can, if required, point out places where depots mould be eftablifhed for affording an un- limited fupply of fimilar cheap materials, and where each (hip, by way of finifhing her lading, will take on board a conve- nient number of bags. In REMARKS ON PAPER MAKING. fj In the year 1793-i, I Imported a parcel of cotton rags at foftance in 9l. per ton ; bleaching them added S per cent, to the 9l. The Point: *J* *"f t x remedy, ltatcd to bleached AufT was worth more than 461. per ton : the beauti-confift in the Ail paper produced now exifts in a public work. If paper f^P^0" of thc r x * i i • i i • improvements, makers, or ftationer-paper makers, had paid attention to this and- tne proper new and growing improvement; (or would pay attention) employ of our .,?,.,. ~ .« n i • i -i r_ ./capital and inftead of (ohcitmg a remiffion ot duties, they might be able worj-,. with their capital and mills ready formed, to counteract the French, and contribute ftill more to the ftate, than is paid at prefent. A relaxation of part of the duties, cannot be a ra- dical relief. To forego an object of finance without remedy- ing a complaint, can only be a compliance with the govern- ment, to participate in misfortune with the petitioners. The neceffity of aboltfhing improper combinations and Combinations power among journeymen paper makers, and the injury done jJintTat «?«&- to paper mills by London ftationers importing and regulating tiom by the State, the price of rags, and monopolizing mills, are evident direc- tions to relieve the fuffering part of the trade, and how to obtain revenue from the wealthy part, by way of granting licences, I fhall be happy, if required, to communicate. The arts, commerce, and navigation of this country, are General obfer- juftly conAdered by the French government, to be the Anews vatl0ns* The r t- i i /-,i i r. t iT ii »• « i arts> commerce, ot England. Chaptal, Berthollet, and other enlightened men navigation. are encouraged to affect us, and benefit their own country in thefe particulars : that they have not been unfuccefsful is ma- nifefted by the Aate of the paper trade in France. The maxim of trade finding its level, is too Alpine a maxim Level of trade, in the prefent Aate of difcoveries. Factories are altering, and markets muA vary. Goods formed by mere mixture, fuch as What manufao faline and other bodies, require neither capital, nor machi- J.°,ries ""Jj.*^ nery. Many of thefe are in a ftate of great cultivation in and what are the France. In arts reAing on capital, machinery, and aptitude !"oft Per™anent of hand, we fhalllong remain unrivalled, countrv. ' At prefent I fliall check thefe obfervations, that my remarks on the paper trade may remain diftindt and unmixed with any other matter. H. CAMPBELL. No* 11, Fleet-Street, London. III. Remarks 10 REMARKS ON COMBUSTION. III. Remarks on Combufiion, by Thomas Thomson, M. D. Lec- turer on Chemijlry in Edinburgh. Phenomenon of JJ%J O operation of nature has a better claim to our attention combuftion is very ftriking to than combustion. The irrefiflible devaftation which it every clafs of fometimes occafions is calculated to flrike the ignorant with terror; the extraordinary changes which it produces naturally attract the inquisitive eye of the philofopher, while its fubfer- viency to almofl every branch of domeflic economy renders it a familiar and neceffary agent in the hands of every indivi- dual. This familiar acquaintance with combufiion feems, however, to have retarded the invefligation of its nature ; for it was not till the feventeenth century that philofophers made Eminent invef- it a ferious object of enquiry. The labours of Bacon, Boyle, tigators of its Hooke, and Mayow are well known ; and the fuccefs with which thefe labours were attended, mufl, if we recollect the difficulties to be overcome, give us a very high idea of the genius of thefe inveftigators of nature. But the philofophers of our own age, efpecially Lavoifier, have gone far beyond their predeceffors ; and have explained fome of the moll in- tricate and important phenomena of combufiion. Lavoifier's the- Mr. Lavoifier's theory of combuftion, improperly termed ory his theory of chemijlry, is fo generally known, that it is unne- ceffary to enter into any detail concerning it. Its merit is in- difputabie, and raifes its author to the very firfl rank among philofophers. Many chemifls feem to think that it explains the whole phenomena of combufiion ; but an attentive exa- mination rnufl convince every impartial obferver, that the theory of Lavoifier, ingenious and fatisfactory without doubt, as far as it goes, leaves yet feveral parts of that very com- plicated procefs as unaccountable as ever. He has corrected the errors of his predeceffors, and made a very important new leaves much to flep; but many new fleps are flill wanting to render the the- dat^'1 ClUC1" ory comP^ete- I hope, therefore, that the following remarks will not be confidered as altogether improper ; they will at leaf! exhibit the fubject in a new point of view, and may per- haps contribute to call the attention of chemifls to certain phenomena REMARKS ON COMBUSTION. 11 phenomena which have not hitherto been claflified, nor exa- mined with that precifion to which they are entitled. 1 . Though the French chemifts have lately given the term The French combustion a new meaning, and made it ftand for the general '™ ^(lion to™ combination of a body with oxigen, I mean, for reafons which the aft of oxi- will appear hereafter, to employ it in the fenfe ufually affixed genation. to the term by the generality of mankind. Now wThen a body undergoes combuftion, in the common fenfe of the word, two things always take place. 1 . The body gradu- Ufual aceepta- ally waftes away, and often difappears altogether j it is then p™f°fr^ **r™ faid to be confumed or burnt. 2. During the whole of this fumj,tion or wafte procefs it emits heat and light ; the heat and light thus emitted jwg beat and are ufually denominated fire, and the wafte of the body is considered as the eftecft or confequence of its combuftion. If either of thefe two phenomena be wanting, we do not fay in common language that a body is undergoing combuftion, or that it is burning. Every theory of combuftion then muft ex- The theory muft plain, 1. Why the burning body is wafted and altered. 2. explain thefe Why during the progrefs of this alteration heat and light are emitted. 2. If we take a view of the different bodies which occupy Relative to com- the attention of chemifts, we fliall find, that as far as com- buftion bo*» » n- i , t 1 1 1 3re 1# SOflWOl- buftion is concerned, they may be arranged under three tibles, orz.fup- claffes; namely, 1. Combuftibles. 2. Supporters of com- porters of com- i n- „ t i n-i i buftion, or 3. bullion. 3. Incombuftibles. incombuftible. I. The combustibles are thofe bodies, which are faid in 1. Combuftibles common language to barn. During combuftion they appear or th;e bodies to emit light and heat, and at the fame time gradually wafte away. When this change has reached its maximum, the procefs of combuftion is at an end. The clafs of combuftibles / is very numerous ; but all the bodies belonging to it may be fubdivided into three fets ; namely, 1 . Simple combuftibles, 2. Compound combuftibles, 3. Combuftible oxides. The fimple combuftibles are twenty-four or twenty-five in ^^ are fim . number, namely, combuftibles j or 1. Sulphur, 3. Carbon, 2. Phofphorus, 4. Hidrogen gas, 5. All the metals *. * Except perhaps gold, filver, and mercury. The 12 REMARKS dN COMBUSTION. •—compound combuftibles, or combuftible oxides, bafe, or com- pound, having more than one bafe. Simple comb, oxides. The compound comb ujl iblcs con fid of" compounds formed by the fimple combuftibles uniting together two and two ; and are of courfe much more numerous than the fimple combufti- bles. They mav be arranged under the five following heads : 1. Sulphurets, 3. Carburets, 2. Phofphurets, 4. Alloys, 5. Sulphurated, phofphorated, and carbonated hidrogen. The combuftlble oxides are compofed of one or more fimple combuftibles, combined with a dofe of oxigen. Though the French chemifts have given to thefe bodies the name of oxides, we fhall fee afterwards that they differ cffentially from metallic and thc&h&zre oxides and from water, which is confidered at prefent as an having Thngie ox^e of hidrogen. The combuftible oxides may be arranged under two heads : 1. Thofe which contain only a tingle bafe combined with oxigen, and which therefore may be termed fimple combuftible oxides. 2. Thofe which contain more than one bafe combined with oxigen, and which therefore may be termed compound combuftible oxides. The fimple combuftible oxides are only four in number ; namely, 1. Oxide of fulphur, 3. Charcoal, 2. Oxide of phofphorus, 4. Carbonic oxide gas. Unlefs fulphur, phofphorus, and hidrogen gas, bodies at pre- fent confidered as fimple, belong to this clafs. All the fimple combuftible oxides are by combuftion converted into acids. The compound combuftible oxides include by far the greater number of combuftible bodies; for almoft all the animal and vegetable fubftances belonging to them. The double bafe is ufually carbon and hidrogen : alcohol, ether, refins, gums, &c. are inftances of compound combuftible oxides *. It was believed by Stahl and his difciples, that all combuf- tible bodies contain one common principle, to which they owe their combuftibility. But in confequence of the difcoveries of Lavoifier this theory has been laid afide. H. Supporten of II. The fupporters of combuftion are a fet of bodies which are not of themfelves, ftridtly fpeaking, capable of undergo- ing combuftion, but which are abfolutely neceffary for the procefs ; for no combuftible body can be made to burn unlefs • To this clafs of bodies alfo mnft be referred all the vegetable and animal acids* fome Compound comb, oxides. Phlogifton. REMARKS ON COMBUSTION. 23 fome one or other of the fupporters be preterit. Whenever they are excluded the procefs flops. All the fnpporters known at prefent are the following fix : 1 . Oxigen gas, 4. Nitrous gas *, 2. Air, 5. Nitric acid, 3. Gafeous oxide of azote, 6. Oximuriatic acid. There are indeed certain fubftances befides thefe, which poflefs nearly the fame properties ; thefe I flia.Il enumerate afterwards under the title of partial fnpporters. All the fupporters contain one common principle, namely, univerfally con- oxigen. The firft of them confifts of oxigen uncombined with tam 0X1Scn» any bafe ; but in the other five the oxigen is united to a bafe. It is very remarkable, that in four cafes out of five, the bafe to which the oxigen in thefe compound fnpporters is united is azote. Is it not probable from analogy, that oximuriatic N. B. acid, the remaining compound fupporter, contains azote like- wife as a component part. III. The incombuftibk bodies are neither capable of under- in. Incombufti- going combuftion themfelves, nor of fupporting the combuf-^ tion of thofe bodies that are; of courfe they are not imme- diately connected with combuftion. At prefent we are ac- quainted with about 13 incombuftible bodies, not reckoning the compounds which they are capable of forming with each other. Thefe are, 1. Azotic gas, 3. The earths. 2. The fixed alkalies, The firft: of thefe fubftances conftitutes the bafe of almoil all the compound fupporters. Some of the alkalies and earths poflefs certain properties in common with combuftibles, and are capable of exhibiting phenomena fomewhat analogous to combuftion ; phenomena to be defcribed afterwards under theSemi-combuf- title of femi-combiiftion. tion* 3. From the preceding obfervations it is obvious, that in Combuftion re- every cafe of combuftion there muft be prefent a combuftiblc^™&fomf>uf~ i -kt i ' i r>' 1 iomii twie and a jup- and a fupporter. Now during combuftion the combuitible 2\-prUr, ways unites with the oxigen of the fupporter. It is this com- bination which occafions the apparent wafte and alteration of the combuftiDle. The new compound thus formed I fhall call a product of eombuflioji. Now every product of combuftion is produ<3 of com- buftion is either * Mr. Davy firft proved that this gas is a fupporter. aawalffic either, ox;je. ]4 REMARKS ON COMBUSTION. either, 1 . water, or 2. an acid, or 3. a metallic oxide. It is true indeed, that other bodies fometimes make their appear- ance during combuftion, but thefe will be found upon exa- mination not to be products, nor to have undergone com- buftion. Thus one of the two characteriftic marks which diftinguifli combuftion, namely, the apparent wafte and alteration of the combuftible body, has been fully explained. For the expla- nation of it we are indebted to Lavoifter. It conftitutes what is ufually, but abfurdly, termed the neiv theory of die- miftry, and is the moft important ftep which has been made towards a complete theory of combuftion, Facility of com- But though the combination of the combuftible with oxigen ro ortioned to ^e a con^ant Part or combuftion, yet the facility with which the attraction combuftibles burn is not proportional to their apparent affinity for oxjgen. £or oxjgen# Phofphorus, for inftance, burns more readily than charcoal ; yet charcoal is capable of abstracting oxigen from phofphorus, and of courfe has a greater affinity for it. The combuftible oxides take fire more readily than fome of the fimple combuftibles; thus charcoal burns more eafily than carbon or diamond : alcohol, ether, and oils, are exceed- ingly combuftible, whereas all the metals require a very high temperature when the fupporter is air. This greater com- buftibility of combuftible oxides is probably owing to the But chiefly de- weaker affinity by which their particles are united. For the ^rt^of^eftroy- cone^on °f heterogeneous particles, when oxigen conftitutes ing the cohe- a part of them, is ufually weaker than the cohefion of homo- fion* geneous particles. Hence they are more eafily feparated than homogeneous particles, and of courfe combine more rea- dily with oxigen ; thofe fimple combuftibles which melt ea- fily, or which are in the ftate of elaftic fluids, are alfo very combuftible, becaufe the cohefion between their particles is eafily overcome. Hence compound It is owing to the fame inferiority in the cohefion of hete- fupperters are rogeneous particles, that fome of the compound fupporters burned. occafion combuftion in circumftances when the combuftibles would not be acted on by fimple fupporters. Thus phofpho- rus burns in air at the common temperature ; but it does not burn in oxigen gas, unlefs the temperature exceed 90°. In oximuriatic acid gas phofphorus burns rapidly at the common temperature of the air, and fo do feveral of the metals; 4 though REMARKS ON COMBUSTION. 15 though they cannot be made to burn in air except at a very high temperature. Thus alfo oils burn rapidly when mixed with nitrous acid. Nitrous gas and the gafeous oxide of azote conftitute exceptions to this rule. 4. None of the products of combuftion are combuftible &c- Produ&s of corn- cording to the definition of combuftion which I have given, h^£££™" This want of combuftibility is not owing to their being fatu- rated with oxigen ; for feveral of them are capable of combin- ing^ with an additional dole of it. But during this combination no caloric nor light is ever emitted; and the compound form- Oxygenation of a ed differs eflentially from a produa of combuftion ; for by this/"?^<* c0»verts ' r . J it into afupporter. additional dofe of oxigen the product is converted into afup- porter. Hence we fee that combuftion ought not to be confounded Difference be- with the combination of a body with oxigen, as is done by the tjonamj 0xige- Frenchchemifts. Combuftion indeed cannot take place with- nation, out the combination of oxigen ; but oxigen may combine with- out combuftion. Thus when iron is burnt, it always combines with 0.27 of oxigen, and is converted into (he black oxide, a product of combuftion, and altogether incombuftible ; capable, however, of combining with an additional dofe of oxigen, and of being converted into the red oxide. But during this laft combination, how rapidly foever it takes place, no heat nor light is emitted. Now the red oxide of iron is not a product of Detonation of ^ combuftion, but a fupporter ; as the following experiments de- \^^ ofironT1 monftrate : Mix it with phofphorous, and put the mixture into the bottom of a long glafs tube, fhut at one end, and filled with azotic gas. Clofe the mouth of the tube, and apply heat to that part in which the mixture is. At a certain temperature a violent detonation takes place, which (hatters the tube in pieces. It is needlefs to remark, that the tube muft be fuffi- ciently long to prevent the effects of expanfton in the gas in- cluded. When antimony is burnt, it always combines with 0.20 of Other product oxigen, and is converted into the white oxide. Now this white /.,..n.,f.i, mto o * ^ Jupporteri. oxide, which is a product of combuftion, and of courfe incom- buftible, is capable of combining with an additional dofe of ox- igen, and of being converted into the acidulous oxide of anti- mony. In like manner, lead, when burnt, is converted into the white oxide of lead, a product j but this product combines with J6 KEMARKS ON COMBUSTION. with additional dofes of oxigen, and is converted into the red Thfyaftbypartand bron-n oxides, both of which are fupporters. When the of their oxigen j fupp0rierS} thus formed by the combination ofoxigen with pro- duds, are made to fupport combuftion, they do not lofe all their oxigen, bat only the additional dole which conftituted them fupporters. Of courie they are again reduced to their original ilate of produ&s of combuftion. Hence it follows, that they owe their properties as fupporters, not to the whole of the oxigen which they contain, but to the additional dofe which conftituted them fupporters. We may therefore call them pen - tied fupporters, indicating by the term, that part only of their oxigen is capable of fupporting combuftion, and not the whole. It is very poffible that both azote and muriatic acid may be pro- ducts of combuftion; and in that cafe both the compound and partial fupporters would agree with each other in every re- fpect. In the prefent ftate of our knowledge, however, it is neceflary to diftinguifti them. All the partial fupporters with which we are acquainted, and are partial fpp.rters. The bafes of all known partial fupporters are metallic. Enumeration. contain a metallic bafts ; for metallic oxides are the only pro- ducts at prefent known capable of combining with an addi- tional dofe of oxigen. It is a circumftance highly deferving of attention, that when metals are capable of combining with ieveral dofes of oxigen, the product or oxide formed by com- buftion is feldom or never that which contains a maximum of oxigen. The following oxides are products of combuftion : 8. Oxide of copper *. 9. Oxide of cobalt*. 1 0. Oxide of nickel *. 11. Oxide of bifmuth*. 12. Purple oxide of gold ? I; 3. Yellow oxide of filver? 1 k Black oxide of mercury f? 1. Black oxide of iron. 2. White oxide of zinc. 3. White oxide of lead. 4. Yellow oxide of tin. 5. White oxide of antimony. 6. White oxide of arfenic. 7. White oxide of manganefe. * The particular oxide of thefe metals, which is the product of combuftion, has not been aicertained j but they are ail combuftiblc in oximuriaric acid gas. f I doubt much whether gold, filver, and mercury, be combuf- tible at all. They do not burn in air, how high foever the tem- perature is } neither do they detonate with red hot nitre, nor exhibit any appearance of combuftion in oximuriatic acid gas ; though this laft body oxidates them with great rabidity. Th« REMARKS ON COMBUSTION. ]7 The following oxides, on the other hand, are partial fup- J>orters of combuftion : !. Red oxide of iron*. 6. Red and brown oxides of 2. Yellow oxide of gold f. lead **. 3 . White oxide of fil ver £. 7 . Black oxide of manganefe. 4. Redoxideof mercury §. 8. Acidulous oxide of antimony? 5. Arfenic acid ||* 9. White oxide of tin ? This lift would doubtlefs be increafed by an accurate exami- nation of all the metallic oxides not included in either of thefe tables* Thus it appears that feveral of the products of combuftion Incombuftibility are capable of combining with oxigen. The incombuftibility °w{™ towantof of products, therefore, is not owing to their want of affinity for affinity for oxi- oxigen, but to fome other caufe. &en* 5. No producl of combuftion is capable of Supporting com* Nor can they bullion. This is not occafioned by any want of affinity forfuPP°rt combuf- combuftible bodies; for feveral of them are capable of com- they can com- bining with an additional dofe of their bafts. But by this com- bine with com- bination they lofe their properties as produces, and are Convert- ed into combuftibles. The procefs therefore differs eflentially from combuftion. Thus fulphuric acid, a product of combuf- Inftances. This tion, by combining with an additional dofe of fulphur or its combination af- oxide, is converted into fulphureous acid, a fubftance which, combuftibles, aft* from feveral of its properties, I conclude to be combuftible. ing.by Part of Thus alfo phofphoric acid, a product of combuftion, is capable of combining with phofphorated hidrogen, and of forming phofphorous acid a combuftible body. When this Iaft acid is heated in contact with a fupporter, it undergoes combuftion ; but it is only the additional dofe of the combuftible which burns, and the whole is converted into phofphoric acid. Hence we fee that it is not ^he whole bafts of thefe compounds which is combuftible, but merely the additional dofe. The compounds, therefore, formed by the union of a product and combuftible, * Fulminates with phofphorus. +• Forms fulminating gold. X Forms fulminating filver. § Forms fulminating mercury* || Occafions combuftion when heated with feveral combuitibieSc ** Occafions the combuftion of fulphur. Vot. II*— May., 1302. C may IB REMARKS ON COMBUSTION. may be termed partial combuftibles; indicating by the name, Since product that a part only of the bafe is capable of undergoing combuftion. with oxigen, but Now fince the produces of combuftion are capable of corn- never exhibit bining with oxigen, but never exhibit the phenomena of com- kTthe^be *"r-buftion excePt when they are in the #ate °f partial combuf- tial combufiibUif tibles, combuftible bodies mull: contain iome principle which combuftibles t|iey ]0fe during combuftion, and to which they owe their com- muil contain a ■' ° ,J fubftance which bulubility ; tor alter they have loft it, they unite to oxigen witn- they bfe in out exhibiting the phenomena of combuflion. Protiv&tan. Though the produces of combuflion are not capable of fup- give oxigen to porting combuftion, they not unfrequently part with their oxi- convert them in- Sen J11^ as ^uPPor^rs do, give it out to combuftibles, and con- to products j but vert them into products ; but during this procefs no heat nor they do not, hke jj i t j evolved. Water, for inftance, gives out its oxigen Jupporters, caule b , t ' b ° combuftion. to iron, and converts it into black oxide, a product ; and fulphu- ric acid gives out its oxigen to phofphorus, and converts it in- to phofphoric acid. Thus we fee that the oxigen of produces is capable of converting combuftibles into products, juft as the The oxigen of oxigen of fupportcrs ; but during the combination of the laft fupparters differs only are }iea^ an(j liorht emitted. The oxigen of fupporters from that of , J' .. r , .6 ,., . . ,. 6 , o prcduBs. then contains lomething which the oxigen or products wants. Combuftibility g. Whenever the whole of the oxigen is abftracted from produ&s on\\ by produces, the combuftibility of their bafe is reftored as com- sbmbuflibki. pletely as before combuftion ; but no fubftance is capable of abftracling the whole of the oxigen, except a combuftible or a •partial combuftible . Water, for inftance, is a product of com- buftion, whofe bafe is hidrogen. To'reftore the combuftibility of the hidrogen, we have only to mix water with iron or zinc tilings ; the metal is oxidated, and the hidrogen gas is evolved as combuftible as ever. But no fubftance, except a combuf- tible, is capable of feparating hidrogen gas from water by com- bining with its oxigen. In the fame manner phofphorus abforbs the oxigen from fulphuric acid, and is converted into a product, while fulphur is feparated in its ufual ftate of combuftibility. Thus we fee that combuftibles are capable of reftoring the combuftibility of the bafes of produces, but they themfelves lofe their combuftibility by the procefs, and are converted into produces. Combuftibility, therefore, may be thrown at plea- Doctrine of ^Lire fr°m one kocty to another. This fact was firft fet in a Scalii. proper light hy Stahl, and was the great ftep in the theory of*" combuftion Remarks on combustion. \g Combuftion for which we are indebted to that philofopher. Some miftakes into which he fell were afterwards eorrecled by Lavoifier *. From thefe fa£ts it is obvious, that the produces of combuf- When produth tion may be formed without combuftion; but in thefe cafes a wjth0ut combuf- new combufiible is always evolved. The procefs is merely an tion, a new com- interchange of combuftibility ; for the combuftible is convert- ^ftibleia evolr- ed into a product only by means of a product. Both the oxi- gen and the bafe of the product having undergone combuflion, have loft fomething which is eflential to combuflion. The procefs is merely a double decomposition. The product yields its oxigen to the combuftible, while at the fame time the com- buftible gives out fomething to the bafe of the product ; the combuftibility of that bafe then is reftored by the lofs of its ox- igen, and by the reftoration of fomething which it receives from the other combuftible thus converted into a product. There is indeed another method of forming the produces of Complicated cafe combuftion without a&ual combuftion in certain cafes; but °f produces . ii- formed by nitric the phenomena are much more complicated. 1 his method is K\i> &c, to expofe them to the aclion of fome of the fupporters diffolved in water ; efpecially nitric acid. Thus moft of the metallic oxides may be formed without combuftion by the action of that acid on the metals. But in that cafe a new fupporter is always evolved, namely, nitrous gas ; ammonia, a new combuftible, is ufually alfo formed ; and not unfrequently the produdt is converted into a partial fupporter. 7 . No fupporter can be produced by combuftion, or by any Oxigen may equivalent procefs. Now as all the fupporters, except oxieen «oml)inf w"hout ra c u- j u u r si c 11 lofing the mgre- gas, conn ft of oxigen combined with a bale, it follows as a dient which oc- confequence, that oxigen may combine with a bafe without c.afions combuf- lofing that ingredient, whatever it is, which gives occafion to combuftion. The a€i of combination of oxigen with a bafe, therefore, is by no means the fame with combuftion. If we * When fulphate of iron Is dropt into a folution of muriate of gold, nitrate of filver, or nitrate of mercury, the gold, filver, and mercury are precipitated in the metallic ftate. This is an additional reafon for fufpectfog that thefe three metals are not combuftible. Every perfon, however, muft have obferved, that the metals in quef- tion have not the metallic luftre when firft precipitated, and that they acquire it flowly when allowed to remain expofed to the light, C 2 take ele&ricity Oxigen Air, 120 ACCOUNT OF A. NEW PLANET. All fupporters fake a vievv of the different fupporters, we fhall find that all of ftraother' " ^em wmcn can be obtained artificially, are procured either fupporters, 01 by from other fupporters, or by the agency of electricity. I. Oxigen gas may be procured from nitric acid and oxi- muriatic acid, two fupporters ; and from feveral of the partial fupporters, as the black oxide of manganefe, the red oxides of lead and of mercury. The a&ion of heat is always neceffary ; but the procefs is very different from eombuftion. II. Air, as far as is known at prefent, cannot be formed ar- tificially. The gas indeed which comes over during part of the ufual diftillation of nitre and fulphuric acid to obtain nitrous acid, refembles air very clofely. But it is obtained from a fupporter. III. The gaseous oxide of aaote, or nitrous oxide of Davy, has hitherto been only procured from nitrous gas and ni» trie acid (nitrate of ammonia), both of which are fupporters. IV. Nitrous gas can only be procured by the decompo- sition of nitric acid, a fupporter. V. Oximuriatic acid can be formed by combining mu- riatic acid with the oxigen of nitric acid, a fupporter ; or with the oxigen of the black oxide of manganefe, the red oxides of lead, iron, mercury, &c. all of which are partial fupporters. Nitric acid VI. Nitric acid is formed fpontaneoufly upon the furface formed fpontane- 0f the earth by proceffes with which we are unacquainted. (To be continued.) Oxide of azote. Kitrous gas. Oximunatic acid. IV. Difcovery of a new planet. $ome Account of a new Planetary Body, di/covered by Dr. Olbers, on the 28ih of March, 1802. A LETTER from Dr. J. H. Schroeter, of Lilienthal, t# Mr. Beft, London, was lately read at the Royal Society, in which he gives an account of this remarkable difcovery of a fecond planetary body of fmall apparent magnitude, difcover- ed by Dr. Olbers, of Bremen, on the 28th of laft March, when it formed the fouth point of an equilateral triangle with the fiars Nos. 20 and 1 9 of the conftellation Virgo. During the comparifons he was induced to make, from his conviction that it was not there in January when he re-difcovered the Cere* near ACCOUNT OF A NEW PLANET. 2^ near the lame fpot, he found its change of place to be very per- ceptible. The following obfervations were tranfmitted by him to Dr. Schroeter : d. h. m. s. iS02. Mar. 28 9 25 10 M. T. App. R. Af. 184° 56' 49" Its placf, App. Dec. 11 33 30 N. 29 8 49 14 M. T. App.R.Af. 184 46 36 App. Dec. 11 52 59 N. Dr. Olbers had not the means of obferving any difc, but Dr. Schroeter, from his information, began to obferve it on the 30th with his thirteen feet reflector, while his affiftant, Mr. Harding, determined its place. With a power of 288 of this large inftrument, it appeared round and lefs hazy than Ceres, with a diameter of 4.635 feconds, which is much larger than its apparent dia- thofe of Ceres and the Georgium Sidus ; the former of which, meter larger thaa , -■ that of Ceres or on the 28th March, meafured 4.021 fee. and the latter, on the the Geo. Sidus. 20th, meafured 3.973 feconds. Its light, though pale and white Its light. in comparifon with that of Ceres, was neverthelefs more in- tenfe upon the whole, as appeared by its projection on the difc micrometer; but the Georgium Sidus was much brighter. A minute ftar was feen near it on two feveral days, which Sufpictonof a Dr. Schroeter feems to fiifpect as a fatellite. fateilite. The pofition of the Olberian planet (or comet), at March 30 d. 8 h. 20 m. 50 fee. mean time, was App. R. A. 184° 35' 52" and 12° 15' 8" app. N. declin. On the lft of April it was again obferved with the great No difc on reflector, and appeared to exhibit no difc, but was lefs in a APril *■ brighter light with the power of 288, and could not be diftin- guiihed from a fixed ftar. When it fometimes appeared with a difc, its diameter was only 3 ".244. The Doctor is difpofed to afcribe this to the heavy dew. Letter from Mr. W, Walker, LeBurer on the Eidouranion* To Mr. NICHOLSQN. 41, Conduit Street, Hanover Square, London SIR, April 26, 1802. THE account you did me the favour of inferting in your valuable Journal of the laft month, refpecling the lltuation of the planet Ceres, will be rendered additionally interefting at prertH^ front the circumftanceofa ft ill more recently obferved C 3 moving 22 METHOD OF OBSERVING TRANSITS. moving ftar being fituated very near to the fituation there pointed out as the place of the Ceres on the 23th of March. Prefent fitua- The planet or comet difcovered by Dr. Olbers, at Bremen, on tion, April *6. the 28th ult, is at prefent in a very fmall degree to the S. E. of the fituation of the Ceres on the 25th of March, and will rea- dily be feen by a night-glafs or telefcope. It is invifible to my naked eye, but appears of a definable difc with a magnifying Definable difc power of a 100 times. Its light is pale red and very faint, and with power of through the night-glafs is lefs brilliant than the Ceres, although ioo. Pale red r • .i . T r •« • u. i J and lefs brilliant no magnity nig power that I can ule will give the latter any ap- than Ceres. parent diameter. It feems probable that its diftance is about nearer theEarth. as *ar aSam as tne Earth is from the Sun, whilft the Ceres is near three times the diflance, and Mars about once and a half as far off. As my object is merely to enable any perfon to find it, I do not trouble you with any more full account at this late period of the month. I remain, SIR, With much refpeft, Your conftant reader, W. WALKER. Prefent fituation The Ceres Ferdinandia will be found a little to the north- ef Ceres. eaft 0f the flar Beta in the Lion's Tail, being the eaftermoft point of a right angled triangle formed by Beta, a double flar due north of it and itfelf. On Bradley's Method of obferving Tranfits, and another Method by zchich the Thicknefs of the Wire is rendered of no Importance \ In a Letter from Mr. Ezekiel Walker. To Mr. NICHOLSON. SIR, Dr. Bradley's 1 HE method of taking tranfit obfervations introduced by ingtranfitrbfer" ^r- 3radley is ftill ufed by aftronomers. This confifls in vations defcrjbed. noting the proportional diflance of the liar from the wire at the two beats of the clock, one immediately preceding, and the other immediately following its paflage acrofs the wire. If the wire be fo thick as to cover the itar, and the flar hap- pens to be behind it when the clock beats, the fituation oJHhe fiar's METHOD OF OBSERVING TRANSITS. 23 /lar's centre cannot be exactly known, which makes the intro- duaion of fine wires very defirable. The finefl wires ftill Spider's webs in proving too thick for very fmall ftars, an aftronomical friend f of mine hinted to Mr. Troughton that he might probably re- ceive affiftance in this delicate branch of his bufinefs from foine of his fpiders. This hint was not loft,* — and hence Bradley's method of obferving feems to be carried to the higheft degree of perfection by the affiftance of a harmlefs infect which is perfecuted without mercy by every file de clutmbre throughout his Majefty's dominions. There is, however, another method of obferving which Another method precludes the neceffity of very fine wires. This confifts in jjd°of "jJJ" ^j— noting the time when the centre of the ftar comes to the side of the wire. But before this method is ufed it is neceflary that one fide of the middle wire fhould be brought into the meri- dian; fuppofe it be that fide which appears to the weft when the telefcope is turned to the fouth, then the obfervations are to be taken on that fide of all the wires. It is a line drawn by tkejlrength of imagination down the mid- Which is a real die of the wire, parallel to the fides, which is ufed in Bradley's method, but in my method a real line is prefented to the eye of the obferver and which he fees very diftincUy, although as fine as if it had been drawn through a geometrical definition. This method of obferving feems to be more fimple than the *ts advantages, other, in confequence of its being, in many cafes only necef- fary to attend to one fide of the wire : for example : Should the clock beat when half the ftar is covered by the wire, it is evident that the centre of the ftar pafTes the fide of the wire at that time. And by making ufe of the apparent diameter of the ftar, and the thicknefs of the wire as two meafures, the fractional part of a fecond may be eftimated, by an experienced obferver to a very great degree of precifion. How far this fmall alteration in the method of ufing the tranfit telefcope may be found convenient to others experience mull determine; but for my own part, I am certain that I can obferve, not only with more eafe to myfelf, but with greater exaclnefs by this method than by Bradley's. I am, Sir, Your very humble fervant, Lj/m, April 19, 1802.. EZEKIEL WALKER. # See a further account of this invention in the laft vol. of this Journal, pa. 319, VI. Defer iption 2-fc DESCRIPTION OF A STOVE. VI. Defcription of a Stove on the Principles of the Sivedijh Fire-place t with Heat-opt nings, by Citizen Guytqn.* Fire-places in ■*• HE true principles of eonftructing fire-places, fo as to ol> France not gene, tain the greateft heat with the leaft confumption of fuel, have rally conftrucled , . to _ _ 1 . ^ , " , , . on good princi- been known for tome time in France; but they have been Ples« much lefs generally adopted, than the neceffity for economifing Often too deep, fuel demands. We fee many fire-places fo deep as to con- fume double the quantity of fuel neceffary, and yet heat the apartment but faintly, where half the expence might be fpared by altering the fire-place according to count Rumford's plan. Smoky chim- If a chimney fmoke, inflead of reducing the tunnel to pro- "y^emedied." " Per dimenfions, fo that defcending currents cannot take place in it, fcarcely any remedy is thought of but air-holes, which require the facrifice of a certain quantity of fuel,, to counter- balance the effect of the cold air continually entering. The ufe of the Swedifh ftoves is probably yet rare, from their not having been conftru&ed on juft principles, or in the beft proportions, at their firft introduction. As I have had one made, which appears to many of my friends to produce an aftonifhing effect, in compliance with their, requeft I flia.ll give an exa6l defcription of it, premising however a few prin- ciples with regard to fires. General princi- l. The heat produced is proportionate only to the air con- rLttr^^bythefuel. jneftic purpofes, 2. The quantity of heat produced by a given quantity of fuel is greateft when the combuftion is moft complete. 3. The combuftion is molt complete when the filiginous part of the fuel is retained longed in pipes in which it may undergo a fecond combuftion. 4. Of the heat produced none is of ufe, but what is dif- fufed through the fpace to be heated, and retained in this fpace. 5. The temperature in this fpace will be higher, in propor- tion as the current of air, which is to renew and keep up the combuftion, is lefs difpofed to abforb the heat of this fpace in palling through it. * Abridged from the Annales de Chimic, vol. xli. p. 79. C. Hence DESCRIPTION OF A STOYtt. 25 Hence we deduce the following obvious confequences : Corollaries dc- 1. The fire-place mull be kept feparate from all bodies that conduct heat rapidly. 2. As heat can be produced only by combuftion, and com- buflion can be maintained only by a current of air, this cur- rent mould be attracted into pipes, where it preferves the re- quifite velocity, without going away from the place to be heated ; fo that the heat it depofits in it gradually accumulates in the whole of the ifolated ilove, to be afterward given out (lowly, according to the laws of its equilibrium 3. When the wood is confumed to fuch a point as to afford no more fmoke, it is of advantage to flop the outlets of thefe pipes, to keep in the heat, which would be carried into the chimney by the continued current of frelh air, which would necellarily be of a lower temperature. 4. Wc mall obtain a higher temperature, and preferve it Apertures f« longer, under fimilar circumftances, if we conftrucl within the heated aiu ilove, or under the hearth and round the fire-place, pipes in which the air derived from without is warmed before it enters into the apartment to fupport the fire, or to replace what has been confumed. Thefe pipes are what have been called heat openings, (bouches de chaleur,) becaufe inllead of confidering their prin- cipal objecl, it is commonly fuppofed, that they are made to give a more rapid palTage to the heat produced. This is not totally without foundation, fince the temperature of the air iffuing from them is iacreafed by the heat it abforbs from the dove; and on tkis account fome might be difpofed to neglect them, as contrary to the moll elTential objecl, that of retaining the heat in it; but it is to be obferved, that we can fhut thefe outlets when we pleafe ; and that we may even cut off all communication with the external air by means of a fimple ilider; fo that every advantage may be derived from them without any inconvenience. It mull be added, that they are Neceffbrylnvery necelTary in very clofe apartments, unlefs we would expofe clofea'a'tmeaU* ourfelves to currents of cold air. Thefe reafons have induced me to employ the heat openings in the Svvedifli ilove, to which they had not been applied. The Swedifh ftoves are conflrucled flrictly according to the Swedl/h floves truell principles, and the pipes in which'the fmoke circulates *,on(*r "^ °n ,. . r \ * r the be it princi- ple dilpoled in the pelt manner for effecting its complete com- pics. buOion. am! method of ufing ihem. QS DESCRIPTION OF A STOVE. So ufeful, that bullion. Their utility has been found fo great, that they have general in Swe- become general in Sweden, where the winters are very fe- denj vere, and where they have diminifhed the confumption oi' wood one third, fo that there is no country where the incle- mency of the weather is guarded agaiuft at lefs expence. fndd"rTer«K°yCdThe>' have likewife been employed advantageoufly, with the works. neceflfary variations of form, in dye-houfes, breweries, &c. Conduction j Their conftruction is by no means expenfive ; they fave iron- work, and require only bricks or tiles. Thefe are recom- mended to be placed edgewife, and chofen as thin as poffible for the inner walls. The circulating pipes are to be placed fo, that rain falling down the chimney can never get into them. The method of uting them is fo eafy, that in the largeft pub- lic buildings one perfon is fufficient to light all the fires. All the wood that can be contained in the fire-place, which is very fmall, is to be put in at once ; it is to be fawn into pieces of equal lengths; and as foon as it is burned, the Aider that flops the communication of the circulating pipes with the chim- ney is to be thruft in. By thefe means all the heat, which the fuel is capable of producing, remains in the pipes, and ifTiies out flowly, and only to diffufe itfelf in the apartment ; while a fingle piece of wood, that had not burned at the fame time with the reft, would oblige the Aide to be left open, and the current of air neceflary for its combuftion would carry off into the chimney the greater part of the heat produced. The following is a defcription of the ftove conftrucled un-» the Swedife ftove der direaions. conftructed by J Fig. 1, Plate III. reprefents a front view of the ftove: its height is 164 centimetres (about 61 inches French), exclufive of the vale, which is a feparate ornament, merely placed on the top. Its breadth is 85 centimetres (about 31 \ inches.) Its depth 58 centimetres (about 21 \ inches.) The height may vary according to the fize of the apart- ment, and be extended without inconvenience to two metres (about 6 feet, 2 inches.) It may likewife be reduced, as I have done for floves in a laboratory, which were to fupport a fand bath as high as the hand. The other two dimenfions are determined ,by thofe of the bricks employed to form the interior circulatory pipes, which fhould be in certain proportions, that the fmoke may pafs through Defcription of Guyton Its height, breadth, depth. Height may nary. Proportions of the circulatory pipes. DESCRIPTION OF A STOVE, 27 through them freely, without fo much air entering with it as would condenfe it, or fink the temperature below the degree neceflary for combuftion. V V are the external parts of the two heat openings. Heat openings. m m Apertures of the flove, by which the air, that is to iflue through the heat openings, enters. Thefe are clofed when the air is drawn from without through a pipe paffing under the floor ; which is much more advantageous for renew- ing the refpirable air of the apartment, and prevents the dan- ger of currents of cold air attracted by the fire; and which is necefTary, as I have obferved, whenever the volume of air in the apartment is not fufficient, to fupply both the confump- tion of the fire, and the circulation in the heat pipes. Fig. 2. is a plan of the foundation of the hearth at the height of the line A B, fig. 1 . II are empty fpaces, to receive the air, and convey it into the compartments, where it is to be heated before it iflues by the heat openings, whether the air be obtained from without, or fimply by the apertures m m, fig. I. Fig. 3. pi. IV. plan at the height of the line C D, fig. I; that above the door of the fire-place, nnnn are the double plates of caft iron, forming the compartments in which the air is to receive the effect of the heat of the fire, o o The empty fpace between thefe plates. f Fig. 4. Front feclion at the line I K, fig. 3. The arrows indicate the direction of the fmoke in the circulatory pipes of the front part.* In this the plates of iron n n are feen in their perpendicular fituation, with the tongues which form their compartments on each fide of the fire-place. One of thefe plates is reprefented in front fig. 7. T is an opening left at the bottom of the fourth circulatory pipe, to reftore the draught of air in the fire-place, if necef- * Among the number of Swedifli ftoves defcribed and delineated in the collection publifhed by baron Cronftedt there are feveral, the circulating pipes of which pafs under the hearth. This gives them a little more extent no doubt, but as foon as the hearth is covered wjth afhes, the air paffing beneath can receive but a very flight im- preffion of heat; it obliges the fire-place to be railed higher; and it renders the conftruction more complex and expenfive. For thefe reafons I have adopted the moil fjmple plan. 4 fary, 28 DESCRIPTION OF A STOVE. fary, by burning there a few flips of paper, or other light corn- bull ible, I fay if necejfary, becaufe I have found by experi- ence, that this precaution may be neglecled, as foon as the ftove has been heated fo as to have loll all its internal damp- ncfs. The door of this fort of blower, or air-vent, ought to fhut very clofe. For this purpofe it is fufficient, to cut a piece of brick of the proper lizc, to make a hole in it to receive a han- dle, and to fatten upon it a piece of plate iron projecting a little all round it. Fig. 5. Plan at the height of the line E F, fig. 1. Fig. 6. Tranfverfe feclion at the line G H of fig. 3, which (hews the height of the fire-place, and the firft direclion of the flame. V points out the arrangement of the heat pipes. The dotted lines give the profile of. the party walls, which form the four grand circulating pipes. R the pipe which conveys the fmokefrom the circulatory pipes into the chimney, and in which is the regifter that cuts off the communication. It is a common ftove tunnel of plate iron ; but it would be better to ufe a fubftance more flowly conduct- ing heat, as an earthen tube made on purpofe, for that part in which the Aider or flop plate acls. The elbow made by this pipe to reach the chimney renders it upnecefTary to repeat, that it is a point of the full import- ance for the body of the ftove to be completely feparate from the wall. That which I have defcribed is 25 centimetres (about 9 inches) diftant from the nearer! point of the nich in which it is placed. S is an elongation of the perpendicular pipe that enters into the chimney. It is intended to receive the water that might condenfe in the upper part, to prevent it from getting into the /love. The cap at the end of this elongation allows the pipe to be cleaned without taking it down. The dotted lines forming the fquare fpace Q mark a place where a nich may be made, or a fort of little ftove, as is don© in fome of the Swedifh ftoves, and would advantageoufly fup. ply the place of the brick-work, with which it mull otherwife be filled up. All thefe figures being drawn on the fame fcale, there will be no difficulty in preferving the proportions of the parts. 2 Th* DESCRIPTION OF A STOVE. 0(J The confiruction of this ilove is neither difficult nor expen- Materials of five. For the outfide nothing is wanted but Dutch tiles, fuch is conftruae EXPERIMENTS. Thf cxdufion Experiment \ . Two frefli herrings were hung up together of armofpheric ;n the laboratory, fo as to touch each other at their flat fides ; appearance of anc* ** was obfcrved that the parts in contact remained dark, ipontaneous while thofe expofed to the open air became very luminous. *'s Exp. 2. Another frefh herring was laid upon a piece of thick Y\(h. brown paper, and placed in the laboratory. On examination, the next evening, the upper part, which was expofed to the air, was very lucid ; but the underfide, lying upon the paper, remained quite dark. Exp. 3. A luminous herring was divided tranfverfely quite through its middle flefhy part; but the inlide was perfectly- dark. On the following night, that which before was dark had become luminous. Exp. 4. At 9 P. M. apiece of frefh herring, of about three drams in weight, was introduced above water, into about eight ounces of atmofpherical air. On the fecond night it was become luminous ; on the third and fourth, it continued fhining ; and on the fifth the light was extinguifhed. This ex- periment was frequently repeated, with both the fleih of herring and of mackerel, and nearly with the fame refult. Exp. 5. The cork of the apparatus was well fmeared with the luminous matter of a mackerel, and then introduced above water. It continued to fhine finely all that evening ; and the light was not quite extinct on the fucceeding night, Exp. 6. Another cork yvas illuminated with herring-light, at half an hour paft fix P.M. and introduced above water. It remained very bright at eleven ; and retained a glimmering light the next evening. The two Iaft experiments were often repeated, and, in general, with fimilar effects. It may not, however, OBSERVATIONS ON SPONTANEOUS LIGHT. 33 however, be improper to obferve, that the illumination of the cork did not always continue fo long as twenty-four hours ; for it muft, ofcourfe, vary according to the quantity of luminous matter applied, and its degree of brilliancy. Exp. 7. A large piece of rotten wood was received from Rotten wood, the country, which fhone only in one place. The luminous portion was fawed off for ufe, and the dark part left in the laboratory. On going into the laboratory, the fecond night after this operation, I was furprifed to fee the dark piece, which had been left there, very lucid in feveral places where fmall fplinters had been broken off in fawing ; many mining fragments alfo lay fcattered on the floor. Exp. 8. A quantity of rotten wood, moderately mining, was blown upon for fome time with a pair of bellows ; but I could not perceive that this had any effect on the light, fo as to render it more vivid. Exp. 9. A fmall piece of mining wood was tied upon one of the corks of the apparatus, and introduced above water, where it continued lucid until the fifth night. In another ex- periment, the light was extinguifhed on the fourth night ; and and in a third much fooner. Exp. 10. A living glow-worm, in a fhining fiate, was Glow-worm, fubmitted to the action of a pair of bellows ; but the con- Thefe are not tinuance of the blafl did not apparently increafe its glowing excited by bcl- quality. Exp. 1 1 . A very luminous dead glow-worm was fixed upon a cork of the apparatus, by means of a fmall pin, and then put into the phial, above water. It continued to thine as vividly as it did when in the open air, forming a pure white light, of a circular ftiape. OBSERVATIONS. Obfervation. 1 . Thefe experiments prove, that objects which abound with fpontaneous light in a latent ftate, fuch as the herring, mackerel, and the like, do not emit it when deprived of life, except from fuch parts as have been fome time in con- tact with the air. Obf. 2. They likewife (how, that the blaft of a pair of bel- lows does not increafe this fpecies of light, as it does that which proceeds from combuftion. Vol II. —May, 1802. P The 34 OBSERVATIONS ON SPONTANEOUS LIGHT, oxigen gas ex hibited no difference of illumination. § 2. The Effects of oxigen Gas or vital Air* onfpontaneous Light. EXPERIMENTS. FiA, ihining Experiment I. A piece of frefh herring, of about three drams ^if?« rn^' weight, was introduced above water, into eight ounces of worms in com- o * * o mon air and in oxigen gas. On the fecond night it was obferved to be faintly luminous; on the third, the quantity of light was increafed; on the fourth, it continued nearly in the fame flate ; and on the fifth the light was diminifhed. Exp. 2. A piece of very frefh mackerel, of the fame mag- nitude, was alfo put above water. On the fubfequent even- ing it was pretty lucid, and continued the fame on the night following. Exp. 3. At 9 P. M. a cork, finely illuminated with mac- kerel-light, was introduced above water : it continued very lucid at eleven. On tke next evening it was dark. Exp. 4. Another cork, rendered luminous with the fame kind of light, was put above water at 10 P. M, The next morning, at fix o'clock, only a glimmer of light was perceived and at 10 P. M. it was extinft. Exp. 5. At 9 P. M. a fragment of mining wood was in- troduced above water ; it was obferved to be frill very lumi- nous at eleven ; but the light was not quite fo vivid, nor (o extended in breadth, as when the wood was put in. On the fucceeding night, at eight o'clock, it remained faintly lucid. Exp. 6, A little after 8 P. M. another fragment of wood, fhining very brightly, was introduced above water, into the fame air that was ufed in the laft experiment : it continued very luminous at eleven; but the light was diminifhed in quantity. On the next evening it was found to be extinguifhed. Exp. 7. The fame air was employed again at 8 P. M. with a pretty large and thick fragment of wood, uncommonly lucid : its light continued vivid and broad at half an hour paft eleven. The following night, at eight o'clock, the light was ftill fome- what extenfive and bright. Exp. 8. In three other experiments with fliining wood, in frefh oxigen gas, the light was totally extinguifhed in the fpace of twenty-four hours. * The oxigen gas made ufe of was obtained from manganefe, by means of heat 2 Experiments OBSERVATIONS ON SPONTANEOUS LIGHT. 35 Experiments were made, at the fame time, and in the fame manner, with atmofpherical air and mining wood ; but it was not very evident that the wood (hone more vividly in the latter air than it did in the oxigen gas. Exp. 9. A living glow-worm was put into a two-ounce phial, with a glafs ftopple, containing pure oxigen gas, and kept therein for fome time. It was then taken out, and ex- pofed to the open air ; but no difference, either in the brilliancy or the quantity of its light, could be difcovered. Exp. 10. A luminous dead glow-worm was then inclofed in about five ounces of the gas j but no increafe of its mining quality could be perceived. Exp. 11. At fix o'clock P. M. a fhining dead glow-worm was introduced above water into oxigen gas : it continued very lucid therein at 7 P. M. fliewing a pure white light. It was then taken out, and put above water into atmofpherical air, where it (hone, to all appearance, as fplendidly as it did when it was in the oxigen gas. OBSERVATION. It appears, from thefe experiments, that oxigen gas does not act upon this kind of light, fo as to render it much more vivid than it is in atmofpherical air ; which is quite contrary to what fome authors have alledged. § 3 The Effects of azotic Gas onfpontaneous Light, I. Azotic Gas, obtained from lean mufcuhr Flejh and diluted nitric Acid, in a very low Heat, as recommended bj/ M. 4f Fouhcroy. EXPERIMENTS. Experiment I . A piece of frefh mackerel, weighing about Azote gas does three drams, was introduced above water, into about eight not admlt of the r i • • i • • , • Jr produ&ion of ounces of this azotic gas j and it was retained therein five fpontaneous days, without emitting any light. light but Exp. 2. About the fame quantity of frefh herring was then ]™e inftaiices* put above water, into the fame gas ufed for the laft experiment, for a time if and remained in it for the fpace of three days, in a dark ftate. ^ecvjd°ufiy pr0* This experiment was repeated, and with a fimilar remit. Exp. 3. At 45 minutes paft 7 P. M. a cork, finely illumi- nated with mackerel-light, was put above water into the gas, and it was found pretty luminous at eleven. On the next even- ing, at eight o'clock, it Hill exhibited a faint degree of light. D 2 A fimilar 3(J OBSERVATIONS ON SPONTANEOUS LIGHT. A firailar experiment was made, at the fame time, in atmo- fpherical air. At 1 1 P. M. the cork was but moderately lumi- nous; and on the next evening it was dark. Exp. 4. At 40 minutes paft7 P. M. another cork, rendered very luminous with herring-light, was introduced above water. This cork, at 11 P. M. was not found fo lucid as that in the third experiment. On the next evening, a glimmer of light was Hill perceptible. Exp. 5. A fragment of very (liining wood was introduced above water, into this gas ; and it was rendered dark in about 15 minutes. Exp. 6. The experiment was repeated ; and the light was again extinguifhed in about 15 minutes. In another experi- ment it was extinguifhed in about 25 minutes. II. Atmqfpheric Air rendered azotic, by burning Spirit of Wine in it, when confined above Water Atmofpheric Exp. 7. A portion of frefh herring, of about three drams, azote. was pUt above water, into this azotic gas, at 5 P. M. On the fecond evening, a fpark of light was obfervable ; on the third, the quantity of light was increafed j on the fourth, it was again diminifhed. Exp. 8. At 3 P. M. the ufual quantity of herring was in- troduced above water. On the fecond night, it remained dark ; on the third it was moderately luminous ; on the fourth, it was lefs fo ; on the fifth, the light was extinct. Exp. 9. A piece of frefh mackerel was next put above water, at 1 1 A. M. On the fecond evening, it was found to be flightly luminous ; it remained fo on the third j on the fourth, it was dark. Exp. 10. Another piece of frefh mackerel was introduced above water, at 3 P. M. On the fecond night, it was found to be flightly luminous ; but on the third, it was dark ; and no more light was emitted, though it was kept in the gas for the fpace of four days. Exp. 1 1 . A cork, made very luminous with herring-light, was put above water, into this gas, at 20 minutes paft 8 P. M. and it continued very lucid at eleven. The next evening, at ten o'clock, the light was nearly extinguifhed. A fimilar experiment was made, at the fame time, in com- mon atmofpherical air, and with the fame remit. Exp, OBSERVATIONS ON SPONTANEOUS LIGtff. £>J Exp. 12. Another cork was introduced above water, with herring-light, at 40 minutes pad 7 P. M. and it remained pretty luminous at eleven. On the following night, it was nearly extinct. III. The lafi mentioned azotic Gas, after being tvajhed with Lime Water. Exp. 13. A piece of herring, of about three drams weight, was put above water, into this azotic gas, at 5 P. M. On the fecond night, it was dark; on the third, very lucid j and on the fourth, the fame. Exp. 1 4. The experiment was repeated, on a piece of her- ring, at 3 P. M. On the fecond evening, it was dark j on the third, pretty luminous ; on the fourth, it was lefs fo j and on the fifth, only a faint light remained. Exp. 15. A portion of freih mackerel was then put above water, at 1 1 A. M. On the fecond night, it was obferved to be moderately mining ; on the third, the light was extinct. Exp. 16. Another piece of frefh mackerel was introduced above water, at 3 P. M. On the fecond evening, it was flightly luminous ; on the third, it w as dark, and continued fo during the four fucceeding nights. Exp. 17. A cork, finely illuminated with herring-light, was next introduced above water, into this gas, at 20 minutes pafl 8 P. M. The light was much diminifhed at 45 minutes pafr. 8 ; at 1 1 the cork had become almofl dark. On the following night, a glimmer was ftill apparent. Exp. 18. Another cork, made very luminous with herring- light, was put above water, at 40 minutes paft 7 P.M. and it continued pretty lucid at eleven. On the next evening, the light was merely vifible. A fimilar experiment was made, at the fame time, in atmo* fpheric air, and with nearly the fame effect. OBSERVATION. It is a remarkable circumftance, that azotic gas, which is incapable of fupporting light from combuftion, mould be fo favourable to the fpontaneous light which is emitted fromvfiijjes, as to preferve its exiftence and brilliancy for fome tim&? iuhen applied upon a cork; yet that it fhould prevent thefe/h of the herring and the mackerel from becoming luminous, and alfo extinguifh the light proceeding from rotten wood, 38 OBSERVATIONS ON SPONTANEOUS LIGHT. § * The Effe&s of hidrogen Gas or inflammable Air* on fpontaneow Light. EXPERIMENTS. Hidrogen ga* Experiment I . At 9 P. M. a piece of frefh herring, weighing ^heVroduaion about three drams> was introduced above water, into hidrogen of light. gas. It was retained therein three days and three nights, without emitting any light. It was then taken out, and expofed to the action of atmofpherical air. On the following night it was found to be luminous ; but was dark again on the next night. Exp. 2. Another piece of frefli herring was put above water, at 6 P. M. This was alfo kept in the gas the fame length of time, without producing any light. It was then ex- pofed to the open air, and infpecled two fucceffive nights, but it remained dark. Exp. 3. The fame experiment was then made with a piece of mackerel, which was taken out on the fourth night, without producing any fhining appearance. The next evening, it emitted a very faint light, which did not continue twenty-four hours, but extinguifhes Exp. 4. A cork, brilliantly illuminated with mackerel-light, it. (Fiih) was introduced above water ; and the light was extinguished in about the fpace of an hour. Exp. 5. At 39 minutes part 9 P. M. another luminous cork was put above water ; it loft fome of its light pretty foon, but was not extinct at twelve. Exp. 6. A cork, with herring-light, was introduced above water, at 23 minutes pad 6 P. M. The light gradually dimi- nifhed, and was only faintly vifible at eleven. Exp. 7. A fragment of very fhining wood was put above water, at 9 P. M. and was dark at eleven. Common air Exp. 8. Another fragment was put above water, at 40 mi- again revives it. nutes paft 8 p# m. at 50 tne light was much diminithed, and at 8 minutes pafl 9 the fhining ceafed. The wood was then taken out, and expofed to the open air, when the light revived in a very beautiful manner. * This gas was obtained from zinc and diluted fulphuric acid; Exp. OBSERVATIONS ON SPONTANEOUS LIGHT. %Q Exp. 9. A piece of uncommonly mining wood was intro- Repetition of duced above water, at 58 minutes paft 8 P. M. it remained extin^»on an4 ' .01 refufcitation. for a fliort time very luminous, but at 25 minutes pall 9 the (Wood) light was greatly diminished ; at do paft 10 it was nearly extin- guiflied; and at 29 paft JO- was quite dark. It was then expofed to atmofpheric atr, and the light revived very brightly. Exp. 10. The fame experiment was repeated, at 35 minutes paft 8 P. M. the mining property was much diminiflied at 9 ; and at 10 it was very faint. The next evening, it continued merely vifible. The wood was now taken out, and the light foon revived very ftrongly. The following night, it was ftill moderately lucid ; but on the next evening nearly extinct. Exp. 1 1. Finding, by the above experiments, that the light of fhining wood was extinguiflied by this fpecies of gas, and rcftored by atmofpheric air, the following three trials were made, to difcover, in fome degree, how long its light might be kept in a latent ftate, and then be revived. At 9 P. M. feveral fragments of fhining wood, tied up in a piece of gauze, were introduced above water, into the hidrogen gas, and the light was gradually extinguiflied during that evening. They were kept there in that dark ftate 48 hours, were then taken Extraction for out, and expofed to the open air, when, after a little time, *• nours# the light re-appeared. Exp. 12. On the 2d of October, another fragment of ex- Three repetitions ceedingly lhining wood, two inches and a half long, and pretty ?L rf fmitton thick, was put above water in the evening, and its light was gradually extinguiflied. On the fecond night, it was taken out perfectly dark, but its light recovered by degrees, and became brilliant. It was introduced again, that evening, into the fame gas, and its light difappeared. On the third night, it was again expofed to the open air, and the light revived as before. It was then reinftated and extinguiflied, and continued in a dark ftate, from the third to the fifth night, when, being again taken out, it foon Ihone in a pretty vivid manner. It was again intro- duced and extinguiflied as ufual ; and no obfervation was made of it, from fome accidental circumftance or other, until the 10th of November in the evening, when it was taken out, and ex- pofed to the open air for a length of time, but the light did not revive. Exp. 40 No renovation after a week Three extinc- tions and reno- vations of a jlow-worra OBSERVATIONS ON SPONTANEOUS LIGHT. Exp. 13. A third fragment, fomewhat larger than the for- mer, and equally luminous, was put above water, at the fame time as the one in the laft experiment, where it was foon de- prived of its light. It was retained there, in a dark ftate, from the 2d of October till the 10th of November ; it was then taken out, and expofed to the action of atmofpherical air, for feveral days, but there was no return of light. Exp. 14. About 7 P. M. a mining dead glow-worm was introduced above water into the gas, and its light was Toon extincl. It was then expofed to the open air, where, in a very fhort time, it flione as brightly as before. Exp. 15. Athalf an hour pail 9 P. M. the fame glow-worm was again introduced above water; when its light in a fhort time difappeared. It was taken out for expofure to common air at 1 1, and its glowing property was immediately reflored. It was again replaced in the gas, where it foon loft all its light a fecond time, and was kept in that dark ftate for 24 hours ; when taken out, it continued dark for a little time, and then the infect gradually recovered its priftine fplendour. OBSERVATION. From thefe experiments we learn, that hidrogen gas, in general, prevents the emiffion of fpontaneous light, and alfo extinguifhes it when emitted ; but, at the fame time, it does not hinder its quick revival, when the fubject of the experiment is again expofed to the aclion of atmofpherical air ; although the light may have been a confiderable time in an extinguifh- ed ftate. (To be concluded in our next.) Caution AGAINST KEEPING PHOSPHORUS IN BOTTLES. 41 VIII. Caution againft the great Danger of keeping Phqfphorus in Bottles •without particular Caution. By D e s c r o z i l l e s the Elder.* I have narrowly efcaped falling a victim to an accident oc- Dangerous cafioned by the effea of the froft upon a bottle, which con- accident of 'fire , , /.,.,.i r from phofphorus. tained a hectogramme of phofphorus, with a quantity ot water fufficient for covering this highly inflamable fubftance. This morning, before day-light, fome books and a cheft fuddenly caught fire in the apartment in which I lay, and which is not occupied during the night. It was ftill fortunate that the two hours of my accuftomed fleep were long fince elapfed. Some feconds later, I mould have been fuffocated by the dele- terious vapours of the phofphoric acid. Quickly gaining the door, I called for affiftance, and we fucceeded in extinguishing the fire before it had made any progrefs. According to all appearance, the froft which had taken place How it happen- fome days before in this piece, had caufed the bottle to break ; but it was furrounded with paper, which prevented its falling to pieces. By this means, in proportion as the water ran off by the effect of the thaw, the bundle of phofphorus, expofed to the atmofpheric air, was fituated under circumftances the moifl favourable to ignition. The fides of the bottle performed the office of a fmall furnace, in which the cylinders of the combuf- tible were propped againfl one another. Soon the gradual combuftion which produces phofphorus acid was fucceeded by the rapid deflagration, the refult of which is phofphoric acid. Independently of the effects of froft and of blows, a bottle Other cautions, frequently breaks without any apparent caufe, and as it were fpontaneoufly : It appears therefore to me, that in order to ob- viate an inconvenience which in fome cafes may prove very ferious, the beft means would be to ufe cafes of copper, ftrong- ly foldered, and lined internally with paper or bran, for in- clofing the bottles filled with phofphorus and water. Cafes of tinned iron would be deftroyed much fooner by oxidation, and their foldering would be fufceptible of detaching itfelf by the effect of a moderate heat. Finally, it appears to me that this report ought to be as pub- lic as poflible. * In a letter to the Editors of the Annales de Chimie, No. 123. IX. IN 42 ON THE DOCTRTNE OF PHLOGTSTOW, IX. Ohfervatiowt in Anfiver to Dr. Priestley's Memoir in De- fence of the Doctrine of Phlogijlon *. In a Letter from Mr. William Cruickshank. To Mr. NICHOLSON. SIR, Woolxiich, March 22, 1802. 1 N your Journal published the \jl of this month, I find a letter from Dr. Prieftley, in which he (till defends the old doclrine of phlogifton, but with very little fuccefs ; for having additional difficulties to ftruggle with, he has been under the neceffity of adopting new, and fometimes contradictory opinions, in his Obfcrvations of explanations and defence ; For example, it is now his opinion that metallic tliat al* metallic calces contain water and little or nothing elfe; calces contain and that charcoal, uniting with water, forms both fixed and in- little addition flammable air ; for as this fubftance contains the elements of except water. . both kinds, nothing but water is wanted to enable them to take the form of air. It is almoft impoffible to argue againft fuch ftrange fuppofitious and loofe reafonings asthefe. However, let us fuppofe water to be the only fubftance contained in ox- ides ; if fo, heat alone ought to revive at leaft fome of them, But when re and in this cafe nothing but water mould be feparated. Now heat they Tfford **iat neat a^one revives feveral, particularly thofe of mercury pure oxigen, and the perfect metals, is a fact fufficiently afcertained ; but, toThe^rlofsof H1^ea^ of water, we obtain the pureft oxigen gas, the quantity weight, and no of which added to the revived metal, amounts, as nearly as w*ter* poffible, to the weight of the original oxide ; even from the ore of manganefe, fo difficult to reduce, a prodigious quantity of the pureft oxigen gas may be procured by a moderate heat ; and when the oxide has been previoufly reduced to powder and well dried, by a heat nearly red, no water whatever can be perceived : in this cafe, too, the quantity of the oxigen gas dif- engaged, will be found to correfpond very nearly with the lofs of weight in the oxide. If calces contain How is it poflible, then, that thefe phenomena can be ex- water only, then piameci on tnc fuppofition, "That all the calces contain little charcoal muft r rr produce the fame . ,>,.,/• , , t ,„, ' * Philof. Journal I. 131. ''or ON THE DOCTRINE OF PHLOGISTON. 43 •« or nothing etfe but water?" when not a particle of water thing by heat is to be feen during the revival, or partial revival, of the me- with calx as with tals from their oxide* in clofe veffels. Let us, however, con- fider this fuppofition in another point of view ; which is, that if water only were contained in thefe oxides, then the gas ob- tained from a mixture of them and charcoal, (hould be the very fame as that procured from moiftened charcoal ; but the con- contrary to facl, trary of this I have clearly proved to be the cafe (fee Phil. Journal, vol. v. quarto, p. 6.) ; and this was one of the princi- pal faults which led to the difcovery of the gafeous oxide. I fhall herejuft enumerate a few of the properties by which Enumeration of thefe gafes may be readily diftinguilhed, being deduced from a cificrgravity of6" number of experiments, often repeated with uniform refults. gafeous oxide of Firit, then, the fpecific gravity of the gafeous oxide of carbon ^at of hvarot is no lefs than double that of the gas obtained from moiftened carbonate j charcoal, being as 30 to 14.5. Secondly, The proportion of faturating oxigen oxigen neceflary to faturate the gafeous oxide, is to that re- very dl erent \ quired by the hydrocarbonate as 15 to 44.8, or 1 to 3, nearly eftimating by quantity. And, thirdly, which is the moft dif- and produ£s of tinguifliing property of the whole, the fame quantity of oxigen, ca.rbh°,"£ acld fuppofe 14 parts, which, when combined with the gafeous ox- tions of oxigen. ide of carbon, produces from 36 to 44 parts of carbonic acid (according to the purity of the oxide), will, when combined to faturation with the hydrocarbonate, produce only 12 parts of the fame acid, accompanied, however, with much water, pro- ceeding in part from the hidrogen in the charcoal, of which all common charcoal, it would appear, contain a certain propor- tion (fee P. Jour. No. 55. p. 210 and 211, and alfo the Table of Analyfis, &c. p. 8. No. 59.) Surely gafes having proper- ties fo eflentially different, can never be considered as the fame. Dr. Prieftley remarks, that there is a considerable difference Differences in. in the qualities of heavy inflammable air, depending not only heavy inflam7 on the fubftance employed, but alfo on the ftages or periods of by Dr. prieftley, the procefs itfelf *. Now I have found that thefe variations never take place in any remarkable degree but when charcoal are found only is employed in fome form, and that even then the differences wh*n charcoal « chiefly depend upon the imperfect ftate of the charcoal ; for if and mo'reor lefs good charcoal be expofed to a red heat in clofe veffels during 5mPure> 10 or 15 minutes, and then mixed whiht hot with the fubftance • P. Journ. No. 3. (Oa.) p. 183. to. 44 ON THZ DOCTRINE OF PHLOGISTON. to be employed, likewife hot and completely dried, the varia- tions in the qualities of the gafes will be much lefs, the princi- pal difference depending upon the proportions of tho carbonic acid and the inflammable gafes j but the gafes from pure char- coal, either alone or moiftened, never have any of the difiin- guifhing characters of the gafeous oxide, being always much lighter, yielding bulk for bulk when faturated with oxigen, not more than one-third of the carbonic acid gas afforded by the the hydrocarbo- other. What, however, diftinguifhes them ftill more com- ' Hghter than"he P*etebr' *s the large proportion of water generated by the gafeous oxide, combuftion of the hydrocarbonate in oxigen gas ; for the gaf- wate^by com-d eous ox^e wnen Pure' or Durned under the fame circum- buftion with ox- fiances, never produces the leaft fenfible quantity of this fluid. jfrer"*n In mentioning the circumftances of the production of the tation and re- gafeous oxide of carbon from the metallic calces and charcoal, marks. &c. j)r. Prieftley has fomehow mis-ftated both the meaning and words in what he calls a quotation from the firft. paper ; this paffage in his letter is as follows (fee p. 182.) : " After " repeating my experiment, which he found to be juft, Mr. M Cruickfliank did the fame with the calces of the other me- " tals, as zinc, copper, &c." and then concludes (p. 4.) " that te in all thefe cafes the air mufi come from the partial $ecompo- " fition of the carbonic acid by the calx, when raifed to a high " temperature :" Then the Dr. goes on and adds : «.« But the " inference that I think is more naturally drawn from them is, " that all thefe calces contain much water, and little or no- " thing elfe." Now the paffage from which this quotation appears to have been taken (for there is nothing in p. 4. ex- actly fimilar to it), does not follow the account of the experi- ments with the calces of the metals, &c. but is an inference drawn from the firft experiments made with the carbonates and the iron fcales. I fhall infert this paffage, and leave the philofophical reader to judge for himfelf of the accuracy of the ffatement and the juftnefs of the conclufion. " Conceiving f that in thefe experiments * the gafeous oxide muft proceed " from the partial decompofition of the carbonic acid by the ** iron when raifed to a high temperature,. I thought I (hould " fucceed better by employing iron filings in place of the grey * Aliuding to thefe made with the carbonate of barytes and iron fcales, or imperfect grey oxide. 4 ** oxide* ON THE DOCTRINE OF PHLOGISTON. 45 *' oxide, as thefe would have a greater affinity for oxigen." From the above ftatement the mifreprefentation both of the explanation and words rauft be manifeft, and the infertion of the word all is curious enough. (EfTay on Gafeous Oxide, &c. Philos. Journal, vol. v. quarto, p. 4.) In the experiments made with the mixtures of carbonate of Filings and chalk lime dried as much as poffible and metallic filings, the Dr. byaDr>' Ptfjftley conceives that the gas rauft have been produced by the water to afford a gas which, dill remaining in the carbonate, had united with the Cp^^n°tad phlogifton of the metal, and palled over in the form of inflam- water, mable gas, mixed with the fixed air feparated from the chalk. If the inflammable gafes were produced in thefe cafes by the If fo, the gas water feparating from the earth, and palling over the red-hot 7**ht£*?j?* metal in the form of fleam, then they mould be the very fame filings and water; as that obtained by pafiing the vapour of water through a red- hot iron tube ; but it is well known, the gafes thus produced are fo far from being the fame, that they are extremely differ- ent in all their properties ; for the hidrogen, or light inflam- ^ th;s is the mable air, produced by the decompofition of the water in fai^ *n& firms pafiing through the tube, is the lighten1 of all aeriform fluids, water by com- and, when combined with oxigen, there is not the lean1 ap- pearance of carbonic acid, and nothing formed but water. On whereas the ga- the contrary, the gafeous oxide procured by heat from a mix- th^Lavieft'in- ture of the drieft earthy carbonates with metallic filings, is the flammable gas, heavieft of all known inflammable gafes, and when united with an<| [ Pr?duces , . , i • • i i . • carbonic gas by oxigen, produces nothing but carbonic acid, there not being combuftion, the leaft appearance of water. It is impoflible, therefore, that witb m water* thefe heavy inflammable gafes fhould be produced by water alone, in any flate, acting upon pure metals ; for the gafes ob- tained from the decompofition of this fluid, whether from the folution of metals in dilute acids, or from their aclion on its vapour when raifed to a red heat, are always of the fame na- ture, being pure hidrogenous gas. Dr. Priefiley obferves, that before I admitted that the iron Recapitulation or its calx, raifed to a high temperature, could decompofe the ° "*e e-*pen- carbonic acid in this experiment, I fhould have tried whether carbonic acid gas it would do it in any other. This remark clearly proves that Paffe,d .over '£*" meed iron now 's ** to ^ exPe^ec^* as neat alone will not and'the attrac- * ^or l^e particulars of this experiment, and the mode of con- tion of charcoal dueling it, fee this Journal, quarto f. No. 55. p. 209. »»yi t No. 55. p. 209. do ON THE DOCTRINE OF PHLOGISTON. 47 tlo it, &c. &c. ? But here he has forgotten that the affinities of bodies are remarkably varied by change of temperature, and that, in all reductions of metallic oxides, the carbon of the as it does In all charcoal, when raifed to a high temperature, unites with the re u oxigen of the calx in confequence of increafed affinity, and forms with it carbonic acid gas and gafeous oxide. That this Red oxides of is the cafe is remarkably proved by dialling the red oxides of^^^f* mercury and lead with charcoal ; for thefe oxides we know acid and oxide, contain a large proportion of oxigen, which may be feparated J^h^exral. by heat alone, but when heated with charcoal, nothing but ments. carbonic acid and gafeous oxide come over, becaufe, in this cafe, the whole of the oxigen being in its nafcent itate, com- bines, even at a low temperature, with the charcoal, and paffes over in the form of carbonic acid gas mixed with the gafeous oxide. There are fome circumftances accompanying the dif- Dedu&ions. tillation of charcoal with thefe metallic oxides, which are eafiiy reduced, and at low temperatures, not altogether uninftructive, and, in my opinion, unanfwerable by the fupporters of phlo- gifton. In thefe procetTes the proportion of gafeous oxide to carbonic acid gas is but fmall, being in general about one-third or one-fifth of the whole, and for the molt part is obtained juft before or at the time the mixture becomes red : It is always accompanied with a torrent of carbonic acid gas. At the in- ftant the metal is revived, the gas either ceafes entirely, or comes over very flowly ; but on increafing the heat, it again makes its appearance, and is now fo far from containing ga- feous oxide, that it is peculiarly light, not mixed with any len- fible quantity of carbonic acid gas, and yields, when faturated with oxigen, but a very fmall proportion of this acid gas. The following fa6ls may be drawn from thefe experiments : Firft, It would appear that a much greater degree of heat is necefTary for the proper production of the gafeous oxide than for the carbonic acid. Secondly, That oxigen, in its nafcent ftate, may unite with carbon at lefs than a red heat, and form carbonic acid ; as is clearly proved by the procefs with the red oxide of mercury and charcoal. The galeous oxide appears like wife to be produced at a very low heat. I have now taken a view of all the arguments which Dr. Concluficn, Prieftley has brought forward in defence of his former opinions, butfliall at prefent make no further observation on this fubjecl, leaving the argument and fact to be decided by your philofophi- cal and chemical readers.— I am, SIR, &c. X, AT 48 °N THE NEW PLANET CERES. X. * On the new Planet Ceres, To Mr. NICHOLSON. SIR, Parfon's Green, April 3, IS02. The fubject re- Jl\T the conclufion of the memoir concerning the new planet Ceres, which you did me the honour to publifh in your laft number of the Philofophical Journal, a want of Ieifure, and the length of the communication, were alledged as reafons for my not concluding, at that time, the whole of the obfervations which I had to offer on the fubject : I beg leave, therefore, now to refume the examination and detail of thofe particulars which remain yet to be treated of. Difcovery of a About four years ago, when I was inventing a mechanical Sucine the great- contrivance> by which the equation of the center and true eft equation from diftance of a planet, or any number of planets, might be ex- the eccentricity, hibited in an orrery, I difcovered that the natural fine of half the greateft equation of any planet, is equal, or very nearly equal, to the decimal figures which reprefent the value of a vulgar frac- tion, compofed of the eccentricity and mean diftance of that planet : For inftance, if we take the mean diftance of the earth from the fun at 100000, and the eccentricity, according to Lar lande, at 1681,395, the fraction W-erSlI5* converted into a decimal expreflion of the fame value, is 01681395; and, omitting the decimal point and three laft figures, we (hall have 01681 for the natural fine of 0° 57' 47,6", which arc differs only about half afecond from one half of the greateft equation, as given in the tables of the third edition of Lalande's Agro- nomy. The procefs, in the form of an analogy, will be thus : As the mean diftance : is to unity :: fo is the eccentricity : to the natural fine of £ the greateft equation. Tabulated num- This analogy will apply to all the other planets, as may be ^rw^nd^ce* feen in the fuDJomed table> which I have calculated from the iu all dieplanets. mean diftances and eccentricities given in Lalande's Aftro- nomy, and copied by Mr. Vince, except in the inftance of Ceres, the data of which planet are taken from the elements of Gauls. Planets. ON THE NEW PLANET CERES. 4.9 Hanets. Vulgar Frac- tions. Decimals, or Nat. Sines. Correfpondent Arcs. Half the greateft Equation, 1750. racy of the inference I have made with refpedt to Ceres, bySjELjf^!!* means of the elliptic hypothefts of Ward, which is generally computation oa allowed to be a convenient approximation to be ufed for the e,IiPtic ^T* finding the equation of a planet, inftead of either the direct orwari. tentative methods, which are more accurate, but much more intricate. Vol. II.— May, 1802. E By 50 0X TUE NEW PLANET CERES. By the elliptic hj pothefis, the analogy for converting mean into equated anomaly is fimply this : ^.y the aphelion diftance : is to the perihelion diftance :: fo is the tangent of half the mean anotnaly : to the tangent of half the equated anomaly ; and the difference between thefe two anomalies conftitutes the equa- tion itfetf". Now, it is well known to all who are converfant in the theory of planetary motion, that in the projection of any elliptic orbit, a circle, defcribed from the focus in which the fun is fuppofed to be, with a radius that is a mean pro- portional between the major and minor femi-axes, will cut the ellipfe in two points, which (hall be the points of mean difiance ; or, which is the fame thing, the points where the equation becomes Jlationary, and confequently where it is a maximum. It is alfo equally well known to practical aftronomers, and calculators of an ephemeris, that the equation varies very flowly for many degrees both before and after the points of mean anomaly correfponding to the greateft equation ; and likewife that thefe points fall a little beyond the firft quadrant from the aphelion, or three degrees of mean anomaly, by a quantity which depends upon the eccentricity of the orbit. In the orbit of Mercury the point of mean anomaly, when the equation is greateft, is nearly at 105° from the aphelion ; in that of Venus it is between 90° and 91* ; in that of the Earth about 91° : in that of Mars about 97° ; in that of Jupi- ter and Georgian between 93° and 94°; and in that of Saturn about 94°. Hence it may be inferred, that if the greateft equation of Ceres be SQ 25', the faid point of mean anomaly will be about 92° : but that if the equation be 9° 27' 41", it will be about 96° ; namely, fomewhat fhort of that of Mars, the greateft equation of which is 10° 40' 40''. Let us try now what the greateft equation will be upon both fuppofitions iucceflively, according to the fimple elliptic hypo- thefts. Log. As the aphelion diftance (27673+825) 28498 4,45481 Is to the perihelion dift. (27673—825) 26848 4,42891 So is the tangent of 46 ° ( $£ •) £ mean anom . 1 0,0 1 5 1 6 14,44407 4,45481 To the tangent of i eq. anom. 44° 17' nearly 9,98926 Then 92°— -88° 34'=3° 26' is the greateft equation. Agaia, ON THE NEW PLANET CERES. 51 Again, fuppofing the point of mean diftance to be at 96°, wc have in that cafe, As the aphelion diftance, 28498 4,45481 Is to the perihelion dift. 26848 4,42891 So is the tangent of 48° 10,0 1556 MMaMMafert 14,47447 4,45481 To the tangent of 46° 17' nearly 10,01966 Then 96°— 82° 34'=3G 26' is the greateft equation, as be- fore. Hence it is indubitably proved, that the equation, as given The equation by Gaufs, is much too great for the eccentricity ; and it ap- f^" * t ^ pears alfo, according to what has been already afierted, that ihe eccentricity j the equation at 92° and 96° of mean anomaly is nearly the fame ; that is to fay, the difference will only be in the fecund?. But the greateft equation of a planet is ufually determined °f th.e eccentri- from a feries of obfervations antecedently to the calculation of the eccentricity : therefore the error which has been detected may be in the eccentricity, and not in the equation ; in which cafe, by reverting the analogy already ufed, we (hall have this calculation, viz. As unity : mean diftance 27673 :: natu- ral line of 4° 43' 50^" or 08247,4 : 2282,2 for the requifite eccentricity. But it will be moft eafy to determine in which J"1* tn'« W'U be of the two elements the error has been committed, when the the per^^when whole period has been accurately afcertained. determined. When it was mentioned in the former paper on this fubject, Ofervations of that oppofitions and conjunctions were of importance to be op^firions^a d obferved, the reafon was omitted to be explained ; which is, their ufe. that when a fuperior planet is in oppofition, or an inferior one in conjunction, the obferved geocentric longitudes are alfo heliocentric longitudes, without calculation or reference to diftance and eccentricity ; becaufe in fuch relative filiations there is no parallax of the orb : and it is well known to aftro- nomers, that when an oppofition happens at the place of mean diftance of a fuperior planet, half the difference between the heliocentric place, by calculation of mean motion, and of the place as obferved at that time, is equal to the greateft equation. The 1 3th of March ult. was the day on which the aftronomers on the continent predicted that an oppofition of Ceres would E 2 occur j DZ ON THE NEW PLANET CERES. occur; but it mud have happened on the 23d, as I calculate from Von Zach's little ephemeris continued forwards ; viz. when the geocentric plane was about 182°. The aftronomer who has an obfervatory, and has noted the exacl time, will do well to make the obfervation public. Application to The mean time which elapfes between two fucceflive oppo- the planet Ceres, fitions or conjunctions of a planet, as feen from the earth, is called a fynodic revolution, and is determined by dividing 360° by the difference of the mean daily motions of the earth and other planets. Thus : taking the mean daily motion of Ceres at 770,7376", according to Gaufs, and of the earth at 5 S' 8,33". according to Lalande, we have _Tf£^_. =,466,6 days nearly for the whole fynodic period, on a luppofition that the motions are both equable throughout their orbits; but their refpective diitances from their aphelia at the time of oppofUion mull be made the argument of a correction, either additive or fubtraetive, as the cafe may be, to determine what a fynodic period would be if both motions were equable. Now, if we reverfe this procefs, we can juft as eafily gain the difference of the daily motions between that of the earth and other pla- nets, and confequently the whole period of the latter, from having only the earth's daily motion, and ohferved Jj/nodic pe- riod ; for 360°, divided by this period in days, gives the dif- ference wanted at once, which, fubtracled from the daily mo- tion of the earth, gives that of the other, if it be a fuperior planet ; but if an inferior one, that difference muft be added ; and the more nearly the twro daily motions approximate to each other, the longer will be the refpective fynodic revolu- tion. In the inftance before us, if we fuppofe the whole cor- rected fynodic revolution of Ceres to be 466,6 days from ob- fervation, we fhall have £gg£ = 2777,3924" for the difference to be fubtracted from 3548,33" the earth's mean daily motion, which will leave 770,7376" for the mean daily motion of Ceres, as before ; by which if we divide 360°, we mail have the wliole tropical period = 1681a i2h 8m 49*. But it remains to be obferved what a whole fynodic period of Ceres may prove in reality, . . Suppolintr the epoch, or mean heliocentric longitude of Determination _, r , . « ..« „ r „ „ t or" the real pe- Ceres to have been 2 b. 1/36 34 on January 1, 1801, the iioH, &c. d3y of its difcovery, as is ilated by Gaufs, and the place of the aphelion 10 S. 26° 27' 38", the mean anomaly mud, on 4 this ON THE NEW PLANET CERES. this fuppofition, have been at that time 3 S. 21° 8' 56", fo that it had patted the place of mean motion about either 19° or 15°, accordingly as we make the greateft equation 3° 25' or 9° 27' 41" : therefore the daily motion was nearer a mean motion than it has been ever iince ; and it will be yet fome months before it arrives at its place of mean motion in the op- pofite half of its orbit ; which place is either 2° or 6° ftiort of the ninth iign of anomaly, accordingly as we take the eccen- tricity. Let us fuppofe now the whole period to be upwards of 1681 days, as has been, perhaps prematurely, determined; one fourth of this time had elapfed on the 24th of February laft ; on which fuppofition, the mean anomaly muft then have been advanced juft three ftgns from the original fituation ; namely, it muft have been upwards of 6S. 21°, at which rate the planet had palled the perihelion by a fpace of time aniwer- ing to 21° of mean motion, which is about 98 days: therefore the 18th of November, 1801, muft have been the day on which it was at the perihelion, or place of greateft velocity ; but at that time the planet xvas loft, and we are not in pof- feflion of any obfervation of it nearer that time than the 7 th of December following, when Baron Von Zach re-dif- covered it. The continuance of any planet in the firft quadrant from aphelion is longer than in the fecond quadrant, by a fpace of time which correfponds to the whole equation, taken at three iigns of mean anomaly; in which fituation, it has been already obferved, that the equated or apparent motion is alfo, as nearly as may be, a mean motion ; if therefore the equation at three iigns be divided by the mean daily rate of motion, we mail have a fpace of time, which, added to one fourth of the whole period, and fubtracled from another fourth, will give nearly the refpedtive times of continuance in the firft and fecond quadrants of anomaly : Hence arifes this rule for finding the two femicircles, refpeclively bife&ed by the perihelion and aphelion points, viz. divide four times the equation at three iigns of anomaly, (which may be the greateft equation where the eccentricity is fmall), by the mean daily motion, and the quotient will be the number of days that the planet continues longer in the femicircle from nine to three iigns of anomaly than from three to nine. For inftance, if we take the equa- tion 53 54 oi* THE ^Ew PLANET CERES. tion of Ceres at 3° 25', we fliall have ?° *5'** = 63,83 days 77° 7376" J for the time of continuance in the femicircle embracing the aphelion, longer than in the femicircle which is bife&ed by the perihelion : but if we take the equation at three figns =, 9° 25', fomewhat lefs than the greateft equation, in this cafe, by reafon of the increafed eccentricity, we fhall have the excefs of con- tinuance 9'x} = 175,93 days. 77 7376 Obfervations This fuggeftion may be worthy the notice of the practical from which the aftronomer : for when a variety of obfervations are taken of potion of the 5 .. ...... j, .._ J . _ . . . , apfides me de- the new planet in the different quadrants of its orbit, and duced, &c, &c, fae correfponding times recorded, it will be no difficult talk, when equidiftant geocentric longitudes are converted into heliocentric longitudes, to obferve what femicircle of the ecliptic correfponds to that half of the orbit in which the pla- net has continued longejl ; the middle of that femicircle will be the aphelion, and the two extremities will be three and nine figns of anomaly : Alfo, the excefs of duration, above the time occupied by the other femicircle, multiplied by the ?nean daily motion, will he four times the equation at three and nine figns of anomaly very nearly ; and as this equation is very little fhort of the greateft equation, the eccentricity may likewife be found by either of the methods already defcribed : Thus the Form and elementary points of the orbit may be gained by a feries of obfervations converted into heliocentric places, even by the projection propofed in the laft memoir on this fubject, and thefe determinations may be corrected by a comparifon of them with the reiults deduced from the properties of an ellipfe, which are here purpofely omitted, left a more minute and fcientific defcription of intricate calculations fiiould rather puzzle than inform the generality of readers*, Inclination of It remains yet that fome obfervations be made relative to the orbit, and the pofition of the orbit of a planet. There are many methods place of nodes. 0f afcertaining the nodes of a planet's orbit, from calculation grounded upon obfervations ; but the fimpleft, when it is practicable, is to convert the geocentric into the heliocentric place at the time when there is no latitude by obfervation, for * See Lalande's and Mr. Vince's Aftronomy ; and alfo ProfefTos ftobifon on the Geo. Sidus, in the Edin. Tranf. vol. I* 1788. the ON THE NEW PLANET CERES. [>j' the heliocentric place will be the place of the node, afcending or defcending, as the cafe may be, which will appear by a fubfequent obfervation ; but when the place of a planet, when eroding the ecliptic, cannot be obferved, the middle point be- tween two equal north and fouth latitudes, gained by obferva- tion, will give the node. The heliocentric latitude, when a planet is juft 90° from each node, is the meafure of the inclination of its orbit, and is eafily obtained from the obferved geocentric latitude, taken in that fituation, by the analogy already defcribed ; or, other- wife, the greateft heliocentric latitude may be acquired from an obfervation of a geocentric latitude and longitudinal dis- tance from the node, thus : When the earth is in the line of the nodes, the analogy will be, as the fine of the difference of the longitudes of the fun and planet feen from the earth : radius :: tangent of the geocentric latitude : tangent of the inclination. The two days on which the earth will be in the line of the Days when the nodes of Ceres will be June 12. and December 13. this year, ^lin^of^he'1 But it is beyond the propofed intention of this popular memoir nodes of Ceres. to enter into all the minutiae of calculation, were the requifite data before me ; but only to point out the methods of applying obfervations for determining the fize, form, and pofition of a planet's orbit : it may not, however, be unworthy of notice, before I conclude, to remark, that the aftronomers on the The early deter, continent, who availed themfelves of the earlieft obfervations foeain^ttaor- only for determining an approximate fet of elements of Ceres, bit of Ceres wer* were enabled to do this from noticing that this planet became ™ac!e from ltl J> ,.:.! itationary pofi* ftatwnary between the 10th and 11th of January, 1801, when tion. its elongation was known by obfervations; for it has been fhewn by writers on aflronomy, that, upon a fuppofition of circular orbits, the tangent of the elongation is equal to the ferni- diameter of the orbit, divided by the fquare root of that femU diameter -j- l . Your's, &c. W. P. APPENDIX, 56 ON THE NEW PLANET CERES. APPENDIX. April 10, IS 04. Since the preceding paper on the planet Ceres was written, Mr. Ed. Trough ton has put into my hands the duplicate of another letter, fent to him by the Baron de Zach, and ad- drefled to Sir Jofeph Banks, Bart, which I underftand has been read at a meeting of the Royal Society, and which I mall here tranferibe *", On account offome remarks which I have to make upon it. (Copy,) Set-berg Obfervatory near Gotha, Feb. 20, 1802. " Dear Sir, Letter from Ba- " I had the honour to fend to you my obfervations of the rem von Zach. new p]anet Qeres Ferdinandea made in January, here I take the liberty to fend the continuation of them made in February. Table of obfer- ■So* Mean Time Ap. Right Afcen. App. Dec. vations. in Seeberg. obferved. obferved. Feb. 3 15h 40' 35" S. 188° 42' 13,05// 12° 40' 5"N. 4 15 36 41,4 188 42 36,30 5 15 32 45,1 188 42 30,15 12 50 25 9 15 16 43,7 188 38 3,90 13 14 18 19 14 34 46,7 187 58 27,90 14 20 3 Pr. Gaufs has corrected his elliptical elements of the orbit upon my obfervations ; here is what he has found fince my laft letter to you. Elements. Epoch for the beginning of the year to the meridian of Seeberg «- £P*f»}bothfiderea,, ." ." Greateft equation of the center Inclination of the orbit Logarithm off axis major 0,4424742 Eccentricity of the orbit 0,08 1 4064 Mean diurnal heliocentric and tropical motion 769y/,7924 With thefe elements of the orbit all the obfervations made by Mr. Piazzi in Palermo, from Jan. 1, till Feb. 11, 1801, 77° 27' 36,5'' 325 57 15,0 80 58 40,0 9 20 8,0 10 37 56,6 * The letter was fent open to Mr. Troughton for the exprefs puipofe of copying and communicating the fame. W. N. agree ON THE NEW PLANET CERES. agree perfectly well, and within a few feconds ; and my ob- servations are reprelented by them thus : 57 Seebcrgobferv. R. A. calculated. Differ. Declin. calcul. 1 Differ. ' 1801, Dec. 7 178° 33' 29,2" — • 1,4" 1802, Jan. 11 186 45 47,6 — 2,3 16 187 27 38,8 —14,4 22 188 6 18,2 — 7,6 Of'/ 25 188 20 37,2 — 2,0 11 56 58,4 +35,4" 26 188 24 37,0 — 12,5 28 188 31 25,7 —12,1 12 9 55,6 + 14,3 29 188 34 14,1 — 4,0 30 188 36 38,4 — 5,5 12 19 19,8 + 19,1 31 188 38 38,3 — 7,1 12 24 15,3 Feb. 3 1188 42 7,8 — 5,2 12 39 53,6 —11,4 As thefe elements agree hitherto fo well with the heavens, the following ephemeris calculated upon them for the next month, will probablydo the fame, fo I annex it here to point out to the Englilh obfervers the place where they have to look for the Ceres. Pofition of the Ceres for Midnight Mean Time in Seeberg Ephemeris. Obfervatory. 1802. R. A. in degrees. Dec . N. R. A. in Time. March 1 186° 41' 15° 30' 12h 26' 45" 4 186 11 15 50 12 24 45 7 185 39 16 10 12 22 36 10 185 5 16 29 12 20 18 13 184 28 16 47 12 17 53 16 183 51 17 4 12 15 24 19 183 13 17 19 12 12 50 22 182 34 17 33 12 10 15 25 181 55 17 44 12 7 40 28 J81 17 17 54 12 5 7 31 189 39 18 1 12 2 37 April 3 180 3 18 6 12 0 12 6 178 29 18 10 11 57 54 This planet will come in oppofition to the fun, March 17 in the afternoon. At the fame time this heavenly body will be in its greateft proximity to the earth == 1,6025, and there- fore; 5$ ON THE NEW PLANET CERES. fore the moft favourable time to look for its fatellites, if there are any, to meaftire its diameter; and to examine its nebu- lofity. About this time, the planet will alfo be in its greateft. geocentrical latitude = 17° 9', and a little later (he will have her greateft retrograde motion, about 13 min. in right afcen- fion per day. The north declination will increafe till the be- ginning of April, and about the 9th of the fame month the Variable light of motion in declination will commence to the fouth. It ap- Cercs. peared to me that the Ceres has fome change of light ; I im- puted it at firft to our hazy atmofphere this winter,, but Mr. Schroeter of Lilienthal, and Mr. Olbers of Bremen, fent me word that they have obferved the fame, and they believe that it is the plane! which is fubject to fuch changes of light. Mr. Herfchel will tell us belt whether it is fo. I have fome hopes to find the planet in ancient catalogues of ftars. Mr. Melfier was very near it in the year 1779. The famous comet of that year ran jufl over the northern wing of Virgo, as now, and the new planet was not very far diftant. If the comet had at- tained two months fooner the completion of Virgo, Mr. Mel- fier muft infallibly have obferved the Ceres then, becaufe he determined all the little itars in the vicinity of the comet ; the planet would have been in the way of the comet, and fo of courfe he would have catched the little planet in 1799. If my obfervations are acceptable to you, dear Sir, only a Jittle hint, and I (hall continue with pleafure to give you fur- ther intelligence. I am, with the greateft efteem and regard, very refpecifuIJy, moil honoured SIR, Your obedient humble Servant, FRANCIS BARON DE ZACH. Lieut . Col. and Direclor of Seeberg Obfervatory near Gotha Saxony" REMARKS. Remarks. '• The diftance which correfponds to the logarithm of f axis major, viz. 0,44.2474-2, is 2,76996*4, the earth's radius being unity. 2. The whole tropical period from the mean daily helio- centric tropical motion, 769,7924'', is 1683d 13h 41' 56,3*. 3. The ON THE NEW PLANET CERES. &£ 3. The fynodic revolution correfponding to this motion is 456d 10h 22m. 4. The time of oppofition could not be on the 17th of March as dated in this letter, but about the 23d, as has been mentioned before, becaufe it was on that day that the diffe- rence of the right afceniions of the fun and Ceres was 1 80°, even according to the Baron's own table : the error feems to have arifen from reckoning the point diametrically oppotite Ceres to be nearly two degrees Jhort of the equinoctial point, wiftead of the fame quantity over, when the right afcenfion of Ceres was about 182°: the other circumftances alfo depen- dent on the moment of oppofition mull therefore be attributed to the 23dinftead of the 17th. 5. On receiving thefe laft corrections of Dr. Gaufs I was Caufe of the- at firft furprifed to find fuch a trifling alteration made with the g^emof" greateft equation and correfponding eccentricity, after the fome dedudions error which I was confident I had deteaed; but I have now of the author, . r P r and the element* found out the caufe of the apparent difcrepancy, which fome 0f Mr. Gaufs. ftrefs has been laid upon ; the mean diftance and eccentricity, I now perceive are, contrary to the ufual mode of expreflion, given in terms of different denominations: the mean diftance has been given in terms which fuppofe the radius of the earth's orbit to be unity, and the eccentricity is given in terms which fuppofe the radius of the orbit of Ceres to be unity, inftead of its proportional radius 2,769964. Profeflbr Robifon on the contrary, in his approximate elements of Georgian exprefied the mean diftance and eccentricity in terms of the fame deno- mination, which is alfo done by Lalande, Vince, and other eminent aftronomers with refpect to the other planets. Let us try now what the greateft equation will be by the elliptic hy~ pothefis, when unity is made the radius of the orbit : As the aphelion diftance (1+,08140) 1,08140—4,03383 Is to perihelion diftance (1— ,08140) 9186—3,96313 ' So is tang : of 46° \ mean anom : - 1 0,0*556 4,00869 To tang : \ eq. anom : 43° 20' 33,6" - 4,03383 9,97486 Then 48* 20' 33,5" + 2 = 86° 41' 72"; and 92° — 86° 41' 7,2" = 9° 18' 5,28" is the greateft equation. 2 Alfo- 60 ENGINE FOR RAISTNO WATER. Alio by the tabulated method we have T^A°5 =s 08110, which is the natural fine of 4° 40' 3,27", or half the greateii equation 9° 20' 16,51", which is not 9" above the correaion of Dr. Gaufs. 6. Hence it appears, that the eccentric point in the pro- jection of the orbit of Ceres (hould be a little lefs than -& of the radius from the central point S (Plate XIII. Fig. 1.) which reprefents the fun. W. P. XI. Defcription of a very cheap Engine for raffing Water. In a Let- ter from Mr, H. Sarjeant of Whitehaven, to Mr. Taylor, Secretary to the Society for the Encouragement of Arts.* SIR, Introduction. A AM fenfible that the little engine, a drawing of which ac- companies this letter, can lay no great claim to novelty in its principle; neverthelefs it isrefpedfully fubmitted to the con- futation of the fociety, how far its fimplicity, and cheapnefs of conftruclion, may render it worthy of their attention, with a view to its being more generally known and ufed in fimilar cafes. Height of Irton- Irton-Hall, the feat of E. L. Irton, Efq. is fituated on an Hall 6o feet a- afcent of fixty or fixty-one feet perpendicular height; at the * foot of which, at the diftance of about 140 yards from the offices, runs a fmall ftream of water. The object was toraife this to the houfe for domeftie purpofes. To this end a dam was made at a ihort diftance above> fo as to caufe a fall of about four feet; and the water was brought by a wooden trough, into which was inferted a piece of two- inch leaden pipe, a part of which is feen at A, plate 2. Defcription of The ftream of this pipe is fo directed as to run into the the engine. A bucket B, when the bucket is elevated; but fo foon as it be- bticket is fuf- J pendcd atone gms to delcend, the ftream flows over it, and goes to fupply end of ? beam the wooden trough or well in which the foot of the fortius and a counter- ~, A »' * ,, ' . , , ° weight at the pump L itands, of three inches bore. ocherend. £), is an iron cylinder attached to the pump rod, which the bucket and** Paiie^ through it. It is filled with lead, and weighs about raifi s the couu- _ , . _ ter-weight; * From the Tranfaftions of the Society, for 1801, page 255. The filver medal was given to the Inventor. 210 lbs. ENGINE FOR RAISING VVAJTER. 6"i 210 lbs. This is the power which works the pump, and forces and this laft in the water through 420 feet of inch pipe from the pump up to ^ \^£™k* the houfe. pump. At E is fixed a cord which, when the bucket comes to The bucket h within four or five inches of its loweit projedion, becomes ™^*™W itretched 3nd opens a valve in the bottom of it, through which ft,ing. the water empties itfelf. I beg leave t» add, that an engine, in a great degree fimt- kr to this, was erected fome years ago by the late James Spedding, Efq. for a lead-mine near Kefwick, with the ad- dition of a fmaller bucket which emptied itfelf into the larger, near the beginning of its defcent, without which addition it was found that the beam only acquired a libratory motion, without making a full and effective ftroke. To anfvver this purpofe in a more fimple way, I conftructed Contrivance to the fniall engine in fuch manner as to finifh its ftroke (fpeak- ftrojce% ing of the bucket end,) when the beam comes into an hori- zontal pofition, or a little below it. By this means the lever is virtually lengthened in its defcent in the proportion of the radius to the cofine, of about thirty degrees, or as feven to fix nearly, and confequently its power is increafed in an equal proportion. It is evident that the opening of the valve might have been effected, perhaps better, by a projecting pin at the bottom ; but I chofe to give an exact defcription of the engine as it (lands. It has now been fix months in ufe, and completely anfwers the purpofe intended. The only artifts employed, except the plumber, were a *' 5s wcr>' cI>eaP« country blackfmith and carpenter; and the whole coft, exclu- sive of the pump and pipes, did not amount to £5. I am, Sir, Your humble fervant, H. SARJEANT. Warwick Court, Holborn. Mr. Charles Taylor. In another letter, dated Whitehaven, April 28, 1801, Mr. With a fal1 of Sarjeant further obferves that the pump requires about eighteen fumption 0f ,'g gallons of water in the bucket to raife the counter-weight, gallons, it raifts and make a frefh ftroke in the pump; that it makes three gj jJJ^ That'?* ftrokes in a minute, and gives about a half-gallon into the cif- to fay ji parts of ■ tern. 6*2 engine rott RAiartWc water. water raife 5 tern at each ftroke. He adds, " I f peak of what it did in the parts. Its rate is , a c . l about one eighth dr)'elt Part ™ laft fummer; when it fnpplied a laige family, part of or* man's together with work-people, &C with watef for all purpofes, throws' up 24 in a Nation where none was to be had before, except fome hogfheads in the bad water from a common pump which has been fince re- moved. But the above fupply being more than fufficient, the machine is occafionally flopped to prevent wear, which is done by merely carting off the firing of the bucket valve." XII. Concerning the Identity of Tellurium and Antimony, the galvanic Efi'ecte of Magndifin, o.id other Philtfophicul Subjecla. By a Correspondent. To Mr. NICHOLSON. S I R, Hiftory of the a intelligence. xlNXIOUS to learn the particulars as well as the truth of the intelligence which I received from Moravia concerning the Tellurium and the decompaction of water pretended to have been effected at Vienna by means of the magnetic fuid,* I ap- plied to a chemical friend refiding there ; and it appears that this intelligence was not correct. Whence to prevent farther mi {information I conceive it mv duty to haften in publifhing the following extract from my correfpondent's anfwer to my letter; and to requeft you the favour of inferring it in your ex- cellent Journal, if there be room for it. I have the honour to be, Sir, Your humble fervant, N. N. London, April 21. 1802. Extract of a Letter from Vienna, dated 30lh March, 1802. " The intelligence communicated to you from Moravja concerning the Tellurium and decompofitioh of water was a little premature, and is not farther true than as follows:" Account of the " ^s *° tne ^ Pomt ^r- Tcharjky, major in the artillery, experiments that (well known by his refutation of Tondi's experiments! to- teiuier it p.oba- ble that Teiluri- * See Philofophical Journal, new Series, vol. I. pag. 234. um is antimony. ^. ^ account of this is given in Baron Borns fyftematic catalogue of the collection of foffils of Mile de Raab at Vienna. Tranfl. wards CONCERNING THE IDENTITY OF TELLURIUM, &C. (j$ wards eftablifhing the poffibility of reducing barytes, lime and magnefia to metallic reguli,) had refolved to employ his con- fiderable ftock of Tellurite and Uranite for the purpofe of fub- jecting thefe two metals to a new and clofer examination. He, therefore, firft prepared, according to Klaproth's manner % a reguks of Tellurium, weighing feveral grains. This regulus perfectly agrees with reguline antimony, only with refpect to its phyfical properties, for inftance, in the fracture, colour, hard" nefs, fpecific gravity; and fo likewife its oxyde perfectly re- fembles the anthnoniumdiaphoreticumablutum (lixiviated white oxyde of antimony by nitre.) However, it would be prema- ture, without farther experiments, in which Major Tfcharfky is at prefent engaged, directly to conclude that Tellurium is nothing elfe but reguline antimony." *' Major Tfcharfky has alfo prepared many ounces of the Uranium. oxyde of Uranium, and will in a fhort time reduce it to a regulus of confiderable fize for the purpofe of farther expe- riments." " Concerning the fecond point it relates only to an experi- Suppofrd gar- ment of ProfeiTor Jordan, who, as in the galvanic experiment JVC efl^s of for decom poling water, connected metallic wires immerfed in water with the oppofite poles of a magnet, and obferved that an oxydation of the wires was effected. But as this experi- ment wrould not fucceed in the feveral inftances in which it was repeated, Major Tfcharfky and Captain Lethenyey are at jsrefent occupied in preparing a large magnetic apparatus in order to inftitute a regular feries of experiments on this fub- jea." J. PoficripL Chevalier Landriani affirms that he has difcovered L-andriani's m»- a method of copying old writings in the fame manner, as of owmss^^"5 recently written papers, duplicates are taken by means of copy- ing-machines.— He has alfo prepared an excellent indelible Indelible ink. ink, the compofition of which he will foon publifh. J The procefs by which Klaproth eibtblifhed the Tellurium as anew metal has been given in Nichclfon's Journal, vol. II. 4to. J7J9, page 273. Tranfl. SCIENTIFIC Q^ SCIENTIFIC NEWS. SCIENTIFIC NEWS, fcta Notice refpecling the Difcovery and Situation of chromated Iron in France. Chromate of ^~/« Pontier has already found, three years ago, in the lower "on. Alps, fbme fragments of chromated iron, out of its place ; but circumftances and the war prevented him from difcovering the true pofition of this new and curious mineral in the earth. He, however, at laft found it in its natural place in a quarry near Gaffin, in the road to Cavalaire. This metal is mixed with a green ferpentine rock, which probably owes its colour to the chrome, according to C. Pon- tier's opinion. It fometimes forms maffes of five folid deci- meters each. — Bulletin des Sc. No 57. BOOKS OF SCIENCE, A Treatife on Aftronomy, in which the Elements of the Science are deduced in a natural order from the Appearances of the Heavens to an Ohferver on the Earth ; demonftrated on Mathematical Principles; and explained by an Application to the various Phenomena, By Olinthus Gregory, Teacher JL HE brilliant difcoveries which have been lately made by Interring dif- aftronomers in different parts of Europe, have naturally pro- nomy. duced a fpirit of inquiry in many perfons who have hitherto paid little regard to (bientilic fubjects, and, at the fame time, have excited an earneft and active folicitude in thofe who have made considerable advances in the caufe of fcience> that thefe inquirers be rightly directed in their purfuit. Among thofe who have thus laudably exerted themfelves in the promotion of ufeful knowledge, your ingenious correfpondent the Rev. Mr. Pear fon, of Lincoln, (now of Parfon's Green) muft cer- tainly be enumerated ; and his many able communications to your Journal demand the thanks of its numerous readers. In Mr; Pearfon'* the laft of that gentleman's valuable papers on the planet Ceres ?*P*J* de" ° * r r ducing the great- VoL.il. — June, 1802. F Ferdinandia, eft equation, 66 AVAl.OGY FOR DEDUCING THE Ferdinartdia, he mentions a fimple method of deducing the greateft equation of a planet's centre from the execntricity, which he discovered a few years ago ; and he invites your mathematical correspondents to give a demonftration of this method, refpeciing the accuracy of which he feems to have little doubt. In confequence of Mr. Pearfon's invitation, I take the liberty of addreiling you on the fubject. It will (ave Dcmonftration much circumlocution to refer to a diagram : let, therefore, accuracy?^ ^ the elliPfls A P G Q in the annexed figure ] . PI. VII. repre- fent the orbit of a planet moving about the fun S in one of the foci ; and let A N QE be a circle defcribed upon the major axis of the orbit as a diameter. Then, if P be the place of the planet in its orbit, A N will meafure the excentric anomaly ; alfo, if the arc A D be taken proportional to the time from the aphelion, it will reprefent the mean anomaly ; and, letting fall the per- pendicular S T from S upon N C continued, it is (hewn, by Ktill and many others, that AN + ST = AD. It has alfo been ihewn that, when the equation of the centre is a maxi- mum in any orbit, the diftance S P of the planet from the fun is = *J S A x S Q, and when this is the cafe, in all orbits of fmall eccentricity the point P nearly coincides with G, or the place of the planet will be near an extremity of its orbit's mi- nor axis. In this fituation of S P, it is manifeft that ST will be almoft coincident with S C, and nearly equal to it ; S D and C N will be nearly parallel ; and D C N -f- S N C nearly equal to 2 D C N ; that is, the greateft equation will be nearly equal to 2ND, or 2 S T, or 2SC. But, when GS the mean diftance reprefents the radius of a circle, as the angle G C S is 90°, S C will manifeftly reprefent the fine of an an- gle : therefore, as G S, the mean diftance, to S C, the eccen- tricity, fo is 1, or radius, to the fine of \ the greateft equa- tion, which is the fame as IVJr. Pearfon's analogy. It is merely an It is obvious from this investigation, that the (imple method approximation. p0inted out by Mr. P. is merely an approximation. It fup- pofes that the orbits are nearly circular, and will therefore produce a refult deviating moil widely from the truth when the eccentricity is the greaieft. Thus in Mr. P's table (p. 49, No. V. N. S.) the greateft error is in the orbit of mercury, where the eccentricity is '20551 in terms of its own mean diftance. The next greateft error is in the orbit of Mars, where the eccentricity is -09308. The next error in order is that CREATES* EQUATION OF A PLACET. £"7 that of Ceres, where the eccentricity is -08140, and error 4|#/. (Pa. 60. No. V.) In the cafe of the Georgian the error or difference , as ftated in the table, is much too great to corre- fpond with the eccentricity. But here I conceive there is a miftake in the determination of the eccentricity : for, accord- ing to a mean from various aftronomers [Mechain, Hennert, JDe la Place, Zach, and Robifon,) the proportional mean dif- tance of the Georgian is not 1918352, but 1908352. Hence then, we have Tir§-|||$ = -04.75824 = nat. fine of 2° 43' 38 -4", differing -5% of a fecond from the determination of La- lande. And, in the cafe of Jupiter, where the eccentricity is •04807, the correfponding difference is -j^ of a fecond; which is a little larger than the former, as it ought to be. So that it appears, as well from Mr. P's table as from the invefti* gation, that this method does not furnifli a refult fufficiently accurate except when the eccentricity is pretty fmall. Before I conclude, I would juft beg to remark, that this The converfe method, though new to Mr. Pearfon, is in reality well known. analogy^° Mr* An analogy which is, in fact, the converfe of this, though ex- known, prelled rather lefs eommodiouily, is given with a demonftra- tion, in La Caille's Aftronomy, art. 147. Vince's Aftron. art. 231. and my Aftron. art. 344. And I believe it is alfo given in the excellent work of La Lande ; but as I have not that performance at hand, I cannot now refer to the place. Another analogy precifely to the fame effect, and deduced from the fame principles, may be feen in art. 249. Book V. Robertfon's Navigation, and under the article Eccentri- city in Dr. Hutton's Math, and Phil. Dictionary. It muff afford great fatisfaction to a gentleman of Mr. Pearfon's can- dour and liberality, to find that the analogy which he acci- dentally ftruck out, is the converfe of oue which admits of a fimilar demon (Iration, and has been long ufed by aftronomers as an eafy and excellent approximation. I am, Sir, Your\s with much refpecr, OLINTHUS GREGORY. F 2 II. On 6$ THE BEAMS OF STEAM ENGINES, II. On the ConjiruStion of the Beams of Steam Engines. By ftfc J. C. Hornblower. From the Author. Dear Sir, ! Hiftortcal intra- 1 BEG leave through the means of your Journal, to lay be- fore the public an account of the framed lever mentioned at the clofe of the article Carpentry in the fupplement to the Encyclopedia Britannica, as it was originally defigned for an engine to have been ere&ed at Amfterdam in the year 1776, together with two others, potfefling every poffible advantage . of levers confiding of fmall fcantles. The fram«d le- I know not by what means the lever above referred to fcVibeTnecds no come to ^e conftm&ed with the difadvantages intimated by the hole bored in it. writer of that article, but there is no neceffity for a hole to be Other particu- bored, or a bolt to be driven in any part of the framing be- tween the arches, except for the chain ilays. The wedges a, b, Fig. 1, Plate V. thus applied, would be an improvement, for want of which a lever of this fort in the hands of a negli- gent engineman had one of its joggles forced off, the ihoulder of the tennon, which was morticed into the arch, not being a joint by the eighth of an inch, or more ; but when it met with the arch it went no further, and continued to work for many years under a great load, and much to its difadvantage in other refpecls. Dimenfions of a The length of this lever was 21 feet, the fcantles were 12 lever oF indiffe- inches by 6 ; height of the whole when put together 30 inches,. &;« and leverage on the gudgeon as 4 to 3. This laft circum- itance operated much againft its conftruction, by giving addi- tional force againft the joggle at that end, but had it been framed fix inches higher, I doubt not but it would have flood to this day under all its difadvantages. Scantlesand The fum of the fcantles is 18 by 12, area of the fecticn 2)6 Ioad' inches, column of water in four lifts 4800 lb. with 440 fathoms of rods, (pump rods) which with the appendages on the other end, added to the power necefiary to overcome the refiftance, amount to about feven tons. Another con- But a much fimpler, and in fome refpecls a more advan- ftrucTion Fig. 2, tageous mode of framing is (hewn a,t Fig. 2, and may be con- W€Ujnadc* ftruaed THEORY OF CHEMISTRY. 09 itrucled with or without arches. This, with little variation, is the invention of a Dutch gentleman, and was applied to the load of a .52 inch cylinder (an atmofphcrical engine) fet up with advantages, which in point of workmanihip at that time was perhaps not equalled, and therefore may be faid to have been fairly tried. This engine was calculated to raife 60,000 gallons per mi- Dimenfions and nute, and the fcantles were 1 8 by 12, and 12 by 8, and where load* lurch timber can be had, it is hardly to be expected to have a lever with greater advantages than this for a fingle ftroke, and where a double flroke is required, it may be doubled for Double con- that purpofe, retaining all its principles and properties as in lon* Fig. 3. which I fuppofe needs no explanation. Fig. 4. is a lever constructed by an eminent engineer in Strong framed Hungary fome years lince, which potFeilesa very great degree gar„ of fupport by the king poft and iron braces, but does not, in my opinion, difcover fo much fcience as the two preceding ones. I forgot to obferve, that inner arches may be attached to Fig. 1. without materially affecting its principle, if they are well let on the whole framing, and bolted to each other without palling through the fcantles, I am, SIR, Your molt obedient Servant,, J. C. HORNBLOWER. Eaft Row, City Road, Taefday, May 11, 1802. III. On the Theory of Chemiftry. In a Letter from the Rev. J.Priestley, L.L.D. F. R. S. #c, To Wm, NICHOLSON, Esq, Dear Sir, IN October laft I fent you a reply to Mr. Cruickftiank's ob- Reference to fervations on one of my arguments in fupport of the doctrine for™r letter, of phlogifton, in which I think I clearly ihewed that he fup- . ' P* ] pofed fixed air to be formed in circumftances in which it is impoflible that it mould be formed, and that it is decompofed jbv a fubfiauce which has no fuch power. Having juft re- ceived 70 THEORY OF CHEMISTRY. ccived a letter from a friend in Paris, in which I find that great account is made of the observations of Mr. Cruickfhank, fo that it is now taken for granted that I mtifl accede to the new theory, I beg you would add to my former letter, that ftanlflbindons Mr' Cruickmank himfelf abandons the- molt fundamental prin- water ?s the fole ciple of that theory, which is, that the only fource of inflam- fource of in- mable air of any kind is water ; and he makes it not neCeflary flammable air. r . . .. ^ _ _ _ ,_ . #.,..* ,, which Lavoifier purpote. Mr. Lavoifier, treating of the inflammable thought eflential a»r from charcoal and water, which is limilar to that from to his theory, charcoal and finery cinder, fays, (Elements of Qhjmifiry, p. 87 of the Englijk tranjlation) " It cannot poffibly be dif engaged from the charcoal, and mult confequently be produced from the water." According to the new theory, the union of oxigen, which is fuppofed to come from the finery cinder, with carbon from the charcoal, mull form fixed air, and not any Inference. kind that is inflammable. Mr. Cruick(hank therefore mull: abandon the new theory, in order to maintain his peculiar hypothefis. If I do not receive a better defence of this new theory from its able fupporters in France, I fliall conclude it to be inca- pable of defence, and that, as becomes ingenuous men, they will abandon it, as Mr. Cruiekfliank has virtually done. I am, dear Sir, Your's fincerely, Northumberland, Feb. 20, 1802. J. PRIESTLEY. P. S. I have not any Number of your Journal of a later date than that for April laft. IV. Experiments upon the tanning Principle, and Refections upon the Art of Tanning. By Cit. Merat Guil lot, Apothecary at Auxerre. prouft's procefs 1 HE tedioufpefs of the procefs indicated by Mr. Prouft for tL tedious^ U~ 0Dta'n'ng ^ie tanin, induced me to make fome experiments, and to endeavour to find a more fpeedy method of procuring it : the following is the refult of my inquiries : 1. I ART OF TANNING* 71 1 . I iniufed tan, in the (late of fine powder, for fome hours lnfufion of tan in water; I filtrated this folution, and treated it with Hme^^P^;- water ; I obtained a preeipitaie in confiderablc abundance, water. which I collected upon a filtre, dried, and afterwards treated with alcohol, in order to afcertain whether it were foluble in this menftruum ; but the alcohol was not even coloured by it. 2. Wifhing to afcertain whether the lime had a greater affi- Acids difengage nity for the acids than for the tannin with which it was com- a p!!lverUlen\v„ matter horn the bincd, I treated four drachms of the precipitate of which I lime; have fpoken above, with nitric acid diluted with water, with the acid of a very gentle heat ; a pretty briik effervefcence took place with a difengagement of carbonic acid gas; after four hours infufion, I filtrated the liquor, which had affumed a very deep tinge, and there remained upon the filtre a black pulverulent fubftance, brilliant, having an acerb and very flightly bitter tafle ; this refiduum weighed a little lefs than two grammes. 3. In order to afcertain whether the nitric acid had dif- by combining folved any lime, I treated the liquid which I had filtrated with the lime' with the acidulous oxalate of potath, and I obtained an abun- dant precipitate ; on which account I conjectured, that fince the nitric acid had diffolved the lime, the Jubilance which I had obtained upon the filtre muft be tanin, as the precipitate obtained by the mixture of the lime-water and of the infufion of tan, was produced by the union of the tanning principle and of the lime. In order to afcertain this point, I treated one portion of it with water, and the other with alcohol ; I let thefe fubftances infufe in the land bath for twenty-four hours : the water became ltrongly coloured, and the alcohol more fo; and thepulveru. but all the tannin (hitherto I only prefume that it is fuch) was not diffolved ; the alcohol diffolved only a little more than half of it, and the water lefs. I treated thefe two liquids, after having filtrated them, with a folution of glue, and I ob- tained a precipitate fimilar to that which is obtained by mixing infufion of tan with the fame folution, but of a much darker colour, and a little lefs elaflic. When I treated them with the muriate of tin, I obtained a precipitate which became gelatinous; when I treated them with lime-water, the tanin combined with the lime, and reproduced the tanate of lime already formed. According lent matter is, tanin, 72 ON THE ART OF TANNING. According to thefe properties, could I doubt that this was pure tanin ? certainly not* fince it prefents the fame remits as that obtained by the procefs of Mr. Prouft. How obtained If we wifh to obtain more pure tanin than that which is Purc# obtained after the folutionof the lime of the tanate of this fub- fiance by an acid, the infufion in alcohol may be evaporated, and we (hall then have very pure tanin. The muriatic acid has prefented me with the fame refult as the nitric. Cortje&ures that The rapidity with which the upper leathers of fhoes (cuir» lime water is ad- d'emptisrne) are tanned, according to the procefs of Citizen vantageous m •■., . ° . taning by the Lequin, who, in manufacturing them, contents himfelf with lime combining merely fubjecting them to 4he preparations of warning and flefliing by lime water, without fuffering them to fwell, and af- terwards tans them, led me to prefume that in this cafe a com- bination is effected of tanin with the lime contained in the fkin thus treated, befides the combination of the tannin with the gelatine contained in the fkin, which accelerates this fa- brication. May it not be probable according to this notion, that the fabrication of leather would be accelerated, if after having fubjecled the (kins to the operations of wafliing and flefliing in lime water, they were left to fwell in the fpent ooze or water in which the old bark, wThich has already ferved for tanning leather, has been infufed. In this cafe, the fmall quantity of tanin dilfolved in this water would combine with the lime with which the fkin would be charged in proportion to the working, and would form a tanate of lime. The fwel- ling would perhaps be effe&ed by this means with a little lefs celerity than by the fulphuric acid, but then it would perhaps be preferable, from the circumftance that the fkin in fwelfing would begin to charge itfelf with tanin, whereas by the ful- phuric acid, the lime with which the fkin is impregnated, when worked, — this fubftance diifolved in water, the lime, I fay, combines with the fulphuric acid employed to (well it, which, I prefume, muft give to the leather a brittle quality that it would perhaps not have if the other procefs were ufed. Perhaps alfo, after the fkins have fwelled in the ooze, this completion might be haftened by putting them firfl into the folution of tan, as Cit. Lequin does, and afterwards fteeping them alternately in lime water and in infufion of tan, always taking care to leave them but a fhort time in the lime-water, which 0*1 THE GRUB OF THE COCK-CHAFER. 73 which might aker them if they were left in it too long. In lhis ea " hypothecs, than he feems " to be aware of; the vibrations of the ether being as ufeful " and neceflary in this as in his." (Phil. Tranf. Vol. VII* p. 5087. Abr. Vol. I. p. 14-5. Nov. 1672.) " To proceed to the hypothecs : firit, it is to be fuppofed " therein, that there is an ethereal medium, much of the fame " conftitution with air, but far rarer, fubtler, and more itrongly " elaftic. It is not to be fuppofed, that this medium is one *e uniform matter, but compounded, partly of the main phlegm " matic body of ether, partly of other various ethereal fpirits, " much after the manner that air is compounded of the phleg- '* matic body of air, intermixed with various vapours and ex* " halations : for the electric and magnetic effluvia, and gravi- " tating principle, feem ;s not againft me. That fundamental fuppofition is, that of the echlreeaTy the Parts of bodies, whenbrifkly agitated, do excite vibrations vibrations. in the ether, which are propagated every way from thofe bo- dies in ilraight lines, and caufe a fenfation of light by beating and THEORY OF LIGHT AND COLOURS, g3 land dafliing againft the bottom of the eye, fomething after the manner that vibrations in the air caufe a fenfation of found by- beating againft the organs of hearing. Now, the moft free and natural application of thishvpothefis to the folution of phe- nomena, I take to be this : that the agitated parts of bodies, according to their feveral fizes, figures, and motions, do ex- cite vibrations in the ether of various depths or bignefles, Particular deve- which, being promifcuoufly propagated through that medium topemcnt j to our eyes, effect in us a fenfation of light of a white colour ; but if by any means thofe of unequal bignefles be feparated from one another, the largeft beget a fenfation of a red colour, the leaft or fhorteft of a deep violet, and the intermediate ones of intermediate colours ; much after the mannner that bodies, as "m found, according to their feveral fizes, fhapes, and motions, excite vi- brations in the air of various bignelTes, which, according to thofe bignefles, make feveral tones in found : that the Jargeft vibrations are beft able to overcome the refiftance of a refract- Various refran- ing fuperficies, and fo break through it with leaft refraction ; gl ' Ity : whence the vibrations of feveral bignefles, that is, the rays of feveral colours, which are blended together in light, muft be parted from one another by refraction, and fo caufe the phe- nomena of prifins, and other refracting fubftances; and that it Thin tranfpa- depends on the thicknefs of a thin tranfparent plate or bubble, rentPlate** whether a vibration fliall be reflected at its further fuperficies, or tranfmitted ; fo that, according to the number of vibrations, interceding the two fuperficies, they may be reflected or tranf- mitted for many fucceflive thicknefles. And, fince the vibra- tions which make blue and violet, are fuppofed fhorter than thofe which make red and yellow, they muft be reflected at a lcfs thicknefs of the plate : which is fufficient to explicate all the ordinary phenomena of thofe plates or bubbles, and alfo of all natural bodies, whofe parts are like fo many fragments of iuch plates. Thefe feem to be the moft plain, genuine, and neceflary conditions of this hypothefis. And they agree fo juftly with my theory, that if the animadverfor think fit to apply them, he need not, on that account, apprehend a divorce from it. But yet, how he will defend it from other difficulties, I know not." (Phil. Tranf. Vol. VII. p. 5088. Abr. Vol. I, p. 145. Nov. 1672.) V To explain colours, I fuppofe, that as bodies of various Repetition of fizes, denfities, or fenfations, do by percuflfion or other action the the«»7* G 2 excite $£ THEORY OF LIGHT AND COLOURS. excite founds of various tones, and confequently vibrations in the air of different bignefs; fo the rays of light, by impinging on the ftiff refracting fuperficies, excite vibrations in the ether, of various bignefs ; the biggeft, ftrongeft, or mod potent rays, the largeft vibrations j and others ihorter, according to their bignefs, ftrength, or power : and therefore the ends of the ca- pillamenta of the optic nerve, which pave or face the retina, being fuch refracting fuperficies, when the rays impinge upon them, they mutt there excite thefe vibrations, which vibrations (like thofe of found in a trunk or trumpet) will run along the aqueous pores or cryftalline pith of the capillamenta, through the optic nerves, into the fenforium ; and there, I fuppofe, affect the fenfe with various colours, according to their bignefs and mixture ; the biggeft with the ftrongeft colours, reds and yellows ; the leaft with the weakeft, blues and violets ; the middle with green; and a confuiion of all with white, much after the manner that, in the fenfe of hearing, nature makes ufe of aerial vibrations of feveral bigneffes, to generate founds of divers tones ; for the analogy of nature is to be obferved." (Birch, Vol. III. p. 262, Dec. 1675.) 94 Confidering the Iaftingnefs of the motions excited in the bottom of the eye by light, are they not of a vibrating nature ? Do not the moll refrangible rays excite the fhorteft vibrations, — the leaft refrangible the largeft ? May not the harmony and difcord of colours arife from the proportions of the vibrations propagated through the fibres of the optic nerve into the brain, as the harmony and difcord of founds arife from the proportions of the vibrations of the air?" (Optics, Qu. 16, 13, 14.) Scholium. The Scholium. Since, for the reafon here afligned by Newton, parts of the re- jt ls pr0Dabie that the motion of the retina is rather of a vibra- bTbly cap^We°o"f tory than of an undulatory nature, the frequency of the vibra- vibrating in uni- tjons muft foe dependent on the conftitution of this fubftance. mited number of Now, as it is almoft impoflible to conceive each fenfitive point colorific mo- of the retina to contain an infinite number of particles, each ca- t,ons' pable of vibrating in perfect unifon with every poffible undu- lation, it becomes necelfary to fuppofe the number limited, for mftance, to the three principal colours, red, yellow, and blue, of which the undulations are related in magnitude nearly as the numbers 8, 7, and 6 ; and that each of the particles is ca- pable of being put in motion lefs or more forcibly,, by undula- tions THEORY OF LIGHT AND COLOURS. §5 tlons differing lefs or more from a perfect unifon ; for inflance, the undula ions of green light being nearly in the ratio of 6-§, will affect equally the particles in unifon with yellow and blue, and produce the fame effect as a light compofed of thofe two fpecies : and each fenfitive filament of the nerve may confift of three portions, one for each principal colour. Allowing this it is not to be flatement, it appears that any attempt to produce a mufical cxPefted that colours C3n nsvc effect from colours, muff be unfuccefsful, or at leaft that no- a muflcai effed. thing more than a very fimple melody could be imitated by them ; for the period, which in fact conftitutes the harmony of any concord, being a multiple of the periods of the lingle undu- lations, would in this cafe be wholly without the limits of fym- pathy of the retina, and would lofe its effect ; in the fame manner as the harmony of a third or a fourth is deflroyed, by depreffing it to the loweft notes of the audible fcale. In hear- The ear not per- ing, there feems to be no permanent vibration of any part™nen ya of the organ. HYPOTHESIS IV. All material Bodies have an attraction for the ethereal Medium, Hypoth. IV. by means of which it is accumulated within their fubjiance, and o^u^"]1?- >* for a f mall Diflance around them, in a State of greater Denjity, of the ether, is but not of greater Elafticity. Sreater witl^n ° "T y and near other It has been fiiewn, that the three former hypothefes, which bodies, may be called effential, are literally parts of the more compli- cated Newtonian fyftem. This fourth hypothecs differs per- haps in fome degree from any that have been propofed by for- mer authors, and is diametrically oppofite to that of Newton ; Newton fup- but, both being in themfelves equally probable, the oppofitionPofed the con" is merely accidental ; and it is only to be inquired which is the beft capable of explaining the phenomena. Other fuppofitions might perhaps be fubftituted for this, and therefore I do not confider it as fundamental, yet it appears to be the fimpleft and beft of any that have occurred to me. PROPOSITION I. All impulfes are propagated in a homogeneous elqfiic Medium with pr0p0f. I. im- an equable velocity. pulfe is propa- tr • i • r i gated uniformly H.very experiment relative to found coincides with the ob- in an homoge- fervation already quoted from Newton, that all undulations are neous elaftic propagated through the air with equal velocity ; and this isfur- G 3 ther i 8$ THEORY OF LIGHT AND COLOURS. tlier confirmed by calculations. (Lagrange, Mifc. Taur. Vol. 1. p. 91 . Alfo, much more concifely, in my Syllabus of a courfe of Lectures on Natural and Experimental Philofophy, about to be publifhed. Article 289.) If the impulfe be fo great as ma- terially to difturb the denfity of the medium, it will be no longer homogeneous; but, as far as concerns ourfenfes, the quantity of motion may be confidered as infinitely fmall. It is furprifing that Euler, although aware of the matter of fact, mould ftill have maintained, that the more frequent undulations are more rapidly propagated, (Theor. muf. and Conject-. phys.) It is poflible, that the acluai velocity of the particles of luminife- rous ether may bear a much lefs proportion to the velocity of the undulations than in found; for light may be excited by the motion of a body moving at the rate of only one mile in the time that light moves an hundred millions. Law of the ve- Scholium 1 . It has been demonftrated, that in different me- lociciei, ha aifFer- diums the velocity varies in the fubduplicate ratio of the force directly, and of the denfity inverfely. (Mifc. Taur. Vol. I. p. 91. Young's Syllabus. Art. 294.) Undulations do Scholium 2. It is obvious, from the phenomena of elaftic not mix. bodies and of founds, that the undulations may crofs each other without interruption. But there is no neceffity that the vari- ous colours of white light mould intermix their undulations ; for, fuppoling the vibrations of the retina to continue but a five hundredth of a feeond after their excitement, a million undulations of each of a million colours may arrive in diftinct fucceffion within this interval of time, and produce the fame fenfible effect, as if all the colours arrived precifely at the fame inftant. PROPOSITION II. Prop. II. Na- 4n Undulation conceived to originate from the Vibration of a tureof undula- fingle Particle, mujt expand through a homogeneous Medium in afpherical Form, but icith different Quantities of Motion in different Parts. For, fince every impulfe, considered as pofitive or negative, is propagated with a conftant velocity, each part of the undu- lation muft in equal times have paft through equal diftances from the vibrating point. And, fuppofing the vibrating par- ticle, in the courfe of its motion, to proceed forwards to a fmall diitance in a given direction, the principal ftrength of the undu- lation tion THEORY OF LIGHT AND COLOURS. 87 ation will naturally be ftraight before it ; behind it, the mo- tion will be equal, in a contrary direclion ; and, at right an- gles to the line of vibration, the undulation will be evanefcent. Now, in order that fuch an undulation may continue its progrefs to any confiderable diftance, there mult be in each part of it, a tendency to preferve its own motion in aright line from the centre ; for, if the excefs of force at any part were communicated to the neighbouring particles, there can be no reafon why it fhould not very foon be equalifed through- out, or, in other words, become wholly extinct, fince the motions in contrary directions would naturally deftroy each other. The origin of found from the vibration of a chord is evidently of this nature ; on the contrary, in a circular wave of water, every part is at the fame inftant either elevated or deprefTed. It may be difficult to (how mathematically, the mode in which this inequality of force is preferved ; but the inference from the matter of fact, appears to be unavoidable ; and, while the fcience of hydrodynamics is fo imperfect that we cannot even folve the fimple problem of the time required to empty a veffel by a given aperture, it cannot be expected that we fhould be able to account perfectly for fo complicated a feries of phenomena, as thofe of elaftic fluids. The theory Theory of Huy- of Huygens indeed explains the circumftance in a manner to- g€ns* lerably fatisfactory : he fuppofes every particle of the medium to propagate a diftinct undulation in all directions ; and that the general effect is only perceptible where a portion of each undulation confpires in direclion at the fame inftant ; and it is eafy to fliovv that fuch a general undulation would in all cafes proceed reel il in early, with proportionate force ; but, upon this fuppofition, it feems to follow, that a greater quantity of force muft be loft by the divergence of the partial undulations, thari appears to be confiftent with the propagation of the ef- fect to any confiderable diftance. Yet it is obvious, that fome fuch limitation of the motion muft naturally be expected to take place ; for, if the intenfity of the motion of any par- ticular part, inftead of continuing to be propagated ftraight forwards, were fuppofed to affect the intenfity of a neigh- bouring part of the undulation, an impulfe muft then have travelled from an internal to. an external circle in an oblique direction, in the fame time as in the direction of the radius, and confequently with a greater velocity ; againft the firft propofition. 88 Proportion III. Lateral undula- tions explained. THtORV OF LIGHT AND COLOURS. proportion. In the cafe of water, the velocity is by no means fo rigidly limited as in that of an elaftic medium. Yet it is not neceffary to fuppofe, nor is it indeed probable, that there is abfolutely not the lead lateral communication of the force of the undulation, but that, in highly elaftic mediums, this communication is almott infenfible. In the air, if a chord be perfectly infulated, fo as to propagate exactly fuch vibrations as have been defcribed, they will in fact be much lefs forcible than if the chord be placed in the neighbourhood of a founding board, and probably in fome meafure becaufe of this lateral communication of motions of an oppofite tendency. And the different intenfity of different parts of the fame cir- cular undulation may be obferved, by holding a common tuning fork at arm's length, while founding, and turning it, from a plane directed to the ear, into a pofition perpendicular .to that plane, PROPOSITION III. A Portion of afpherical Undulation, admitted through an Aper- ture into a quiefcent Medium, willproceed to be further propa~ gated reclilinearly in concentric Superficies, terminated laterally by weak and irregular Portions of newly diverging Uiidula- tions. At the inflant of admiffion, the circumference of each of the undulations may be fuppofed to generate a partial undulation, filling up the nafcent angle between the radii and the furface terminating the medium ; but no fenfible addition will be made to its ffrength by a divergence of motion from any other parts of the undulation, for want of a coincidence in time, as has already been explained with refpect to the various force of a fpherical undulation. If indeed the aperture bear but a fmall proportion to the breadth of an undulation, the newly gene- rated undulation may nearly abforb the whole force of the por- tion admitted ; and this is the cafe confidered by Newton in the Principia. But no experiment can be made under thefe circumftances with light, on account of the minutenefs of its undulations, and the interference of inflection ; and yet fome faint radiations do actually diverge beyond any probable hV mits of inflection, rendering the margin of the aperture dif- tinctiy vifible in all directions j thefe are attributed by Newton to fome unknown caufe, diffinct from inflection : (Optics, Third THEORY OF LIGHT AND COLOURS. g£ Third Book, Obf. 5 . and they fully anfwer the defcription of this propofition. Let the concentric lines in Fig. 1. (Plate V.) reprefent the Linear explansf contemporaneous fituation of fimilar parts of a number of fuc- tl0n* cefiive undulations diverging from the point A ; they will alfo reprefent the fuccetfive fituations of each individual undula- tion : let the force of each undulation be reprefented by the breadth of the line, and let the cone of light A B C be admit- ted through the aperture B C ; then the principal undulations will proceed in a rectilinear direction towards G H, and the faint radiations on each fide will diverge from B and C a? centres, without receiving any additional force from any inter- mediate point D of the undulation, on account of the inequa- lity of the lines D E and D F. But, if we allow fome little lateral divergence from the extremities of the undulations, it muft diminifh their force, without adding materially to that of the diffipated light ; and their termination, inftead of the right line B G, will aflume the form C H ; fince the lofs of force muft be more confiderable near to C than at greater diftances. This line correfponds with the boundary of the fhadow in Newton's firft obfervation, Fig. 1 ; and it is much more pro- bable that fuch a diftipation of light was the caufe of the in- creafe of the fhadow in that obfervation, than that it was ow- ing to the action of the inflecting atmofphere, which muft have extended a thirtieth of an inch each way in order to produce it ; efpecially when it is confidered that the fhadow was not di- minifhed by furrounding the air with a denfer medium than air, which muft in all probability have weakened and con- tracted its inflecting atmofphere. In other circumftances, the lateral divergence might appear to increafe, inftead of dimi- nifhing, the breadth of the beam. As the fubject of this propofition has always been efteemed Obje&ions of the moft difficult part of the undulatory fyftem, it Will be pro- Newt°n to the per to examine here the objections which Newton has ground- ftem ofTighu" ed upon it. " To me, the fundamental fuppofition itfelf feems impofli- ble ; namely, that the waves or vibrations of any fluid can, like the rays of light, be propagated in ftraight lines, without a continual and very extravagant fpreading and bending every way into the quiefcent medium, where they are terminated by it. 30 THEORY OF LIGHT AND COLOURS. it. I miftake, if there be not both experiment and demon- stration to the contrary." (Phil. Tranf. VII. 5089, Abr. I. 146. Nov. 1672.) " Motus omnis per ftuidum propagatus divergit a reclo tra- mite infpatia immota." f< Quoniam medium ibi" in the middle of an undulation ad- mitted, " denfius eft, quam infpatiis hinc inde, dilatabit fefe tarn rerfus fpatia utrinque fita, quam verfus pulfuum rariora inter- valla ; eoque patio — pulfus eadem fere celeritate fefe in medii par- tes quiefcentes hinc inde relaxare debent ; — ideoque fpatium totujn occupabunt. — Hoc experimur in fonis." (Princip. Lib. II. Prop. 42.) u Are not all hypothefes erroneous, in which light is fup- pofed to confift in preffion or motion, propagated through a fluid medium ? — If it con lifted in preffion or motion, propa- gated either in an inftant, or in time, it would bend into the fhadow. For preffion or motion cannot be propagated in a fluid in right lines beyond an obftacle which ftops part of the motion, but will bend and fpread every way into the quiefcent medium which lies beyond the obftacle. The waves on the furface of Stagnating water, paffing by the fides of a broad obftacle which ftops part of them, bend afterwards, and di- late themfelves gradually into the quiet water behind the ob- ftacle. The waves, pulfes, or vibrations of the air, wherein founds confift, bend manifeftly, though not fo much as the waves of water. For a bell or a cannon may be heard beyond a hill, which intercepts the fight of the founding body ; and founds are propagated as readily through crooked pipes as ftraight ones. But light is never known to follow crooked paflages, nor to bend into the fhadow. For the fixed ftars, by the interpofition of any of the planets, ceafe to be feen. And fo do the parts of the fun, by the interpofition of the moon, Mercury, or Venus. The rays which pafs very near to the edge-, of any body, are bent a little by the action of the body ; but this bending is not towards but from the fhadow, and is performed only in the paffage of the ray by the body, and at a very fmall diftance from it. So foon as the ray is paft the body, it goes right on. 5> (Optics, Qu. 28.) Anfwcrstothe Now the propofition quoted from the Principia does not Newtin"5 ^ dire% contradia this propofition ; for \t does not aflert that fuch a motion muft diverge equally in all directions ; neither can THEORY OF LIGHT AND COLOURS. 91 can it with truth be maintained, that the parts of an elaftic. medium communicating any motion, muft propagate that mo- tion equally in all diredions. (Phil. Tranf. for 1800. p. 109— 1 12.) All that can be inferred by reafoning is, that the mar- ginal parts of the undtriation muft be fomewhat weakened, and that there muft be a faint divergence in every direction ; but whether either of thefe effects might be of fufficient mag- nitude to be fenfible, could not have been inferred from argu- ment, if the affirmative had not been rendered probable by experiment. As to the analogy with other fluids, the moft natural infe- Sound deflefts rence from it is this : f The waves of the air, wherein founds J™ lhan wave* " confift, bend manifeftly, though not fo much as the waves " of water;" water being an inelaftic, and air a moderately elaftic medium ; but ether being moft highly elaftic, its waves bend very far lefs than thofe of the air, and therefore almoft imperceptibly. Sounds are propagated through crooked pal- Crooked paf- fages, becaufe their fides are capable of reflecting found, juft 'aSes* as light would be propagated through a bent tube, if perfectly poliflied within. The light of a ftar is by far too weak to produce, by its faint divergence, any vifible illumination of the margin o a planet eclipfing it ; and the interception of the fun's light by the moon, is as foreign to the qneftion, as the ftatement of inflection is inaccurate. To the argument adduced by Huygens, in favour of the rectilinear propagation of undulations, Newton has made no reply ; perhaps becaufe of his own mifconception of the na- ture of the motions of elaftic mediums, as dependent on a peculiar law of vibration, which has been corrected by later mathematicians. (Phil. Tranf. for 1800, p. 116.) On the whole, it is prefumed, that this proposition may be fafely admitted, as perfectly confift ent with analogy and with expe- riment. (To be continued.) VIII. Remarks 92 REMARKS ON COMBUSTION. Kittle acid formed fponta- ncoufly i and alfo by elec- tricity, through common air, and probably by gal- vanifm j Apparently by decombuftion. Nitric acid in the procefs for compofing wa- ter. VIII. Remarks on Combuftion. By T h o m a s T h o m s on , M. D. Lecturer on Chemiftry in Edinburgh. (Concluded from Page 20 J VI. INlTRIC acid is formed fpontaneoufly upon the furface of the earth by proeefles with which we are but imperfectly acquainted; but which certainly have no refemblance to com- buftion. Its oxigen is probably furnifhed by the air, which is a fupporter ; at leaii, it has been obferved, that if azote, the inftant it is evolved, comes in contact with air, it is capable of combining with its oxigen, and forming nitric acid. Nitric acid may be formed alfo, as Mr. Cavendifti has de- monftrated, by pairing electric fparks through common air, a fupporter. In all probability it may be formed alfo by the gal- vanic pile, but this may be confidered as equivalent to eleclri- city. This formation of nitric acid by means of electricity, has been confidered as a combuftion, but for what reafon it is not eafy to fay : the fubftance acted upon is not a combuftible with a fupporter, but a fupporter alone. Electricity is fo far from being equivalent to combuftion, that it fometimes acts in a manner diametrically oppofite ; unburning, if I may ufe the expreffion, a fubftance which has already undergone combuf- tion, and converting a.produc~l into a combuftible and a fupporter . Thus it decompofes water, and converts it into oxigen and hi- drogen gas; therefore it muft be capable of fupplying the fubftances which the oxigen and combuftible lofe when they combine by combuftion, and form a product *. There is one procefs more, during which nitric acid is form- ed, which muft at firft fight appear an exception to the general rule ; I mean the formation of nitric acid, which takes place during the combuftion of hidrogen gas in oxigen gas contami- nated with air. But in this cafe it is the hidrogen only which burns, and not the air; the air indeed combines intimately, and forms nitric acid, juft as it does when electric fparks are * I do not mean to affirm that electricity never occafions com- buftion, the contrary of which is weli known, but that a combina- tion produced by it is not always the fame with combuftion. paffed REMARKS ON COMBUSTION. t#J pafled through it. But this procefs has no refemblance to combuftion. We lee, however, that a certain temperature is capable of producing this change in air. 8. Several of the fupporters and partial fupporters are ca- Supporters, &c* pable of combining with combuftibles, without undergoing de- m.ay combine r - , •, • • , r l n- t Wlth combuf- compontion, or exhibiting the phenomena ot combultion. In tibles without this manner the yellow oxide of gold and the white oxide of combuftion, and filver combine with ammonia; the red oxide of mercury with nat}ngC6i,pounjSt oxalic acid ; and oximuriatic acid with ammonia. Thus alfo nitre and oximuriate of potafh may be combined, or at leaf! intimately mixed with feveral combuftible bodies, as in gun- powder, &c. In all thefe compounds the oxigen of the fup- porter and the combuftible retain the ingredients which ren- der them fufceptible of combuftion ; hence the compound is ftill combuftible : And in confequence of the intimate combi- nation of the component parts, the leaft alteration is apt to de- ftroy the equilibrium which fubfifts between them ; the con- fequence is, combuftion and the formation of a new compound. Hence thefe compounds burn with amazing facility, not only when heated, but when triturated or ftruck fmartly with a hammer. They have therefore received the name of deto- nating or fulminating bodies. Thus we have fulminating gold, fulminating filver, fulminating mercury, fulminating pow- der, &c. 9. Such are the properties of the combuftibles, the fupport- ers, and the products j and fuch the phenomena which they exhibit when made to act upon each other. If we compare together the fupporters and the produ&s, we Supporters and fliall find that they referable each other in feveral refpeas. Pfod.uas refem* J % *■ ble in many rc- Both of them contain oxigen as an effential conftituent part ; fpcfts 5 both are capable of converting combuftibles into produces ; and feveral of both combine with combuftibles and with addi- tional dofes of oxigen. But they differ widely from each other in the phenomena which accompany their action on com- buftibles. The fupporters convert thefe bodies into produces, but they differ and combuftion, or the emiffion of heat and light at the fame ^]l in their , , , ift 1 n-ii eftedt on com- time, takes place ; whereas the products convert combuftibles buftibles. The into produces without any fuch emiilion. Now, as the ultimate f°rn"'er only pro- change produced upon combuftibles by both thefe fets oftjon, bodies is the fame, and as the fubftance which combines with the combuftibles is in both cafes the fame, namely oxigen, we 4f muft 9* The oxigen of fupporters con- tains caloric. Combuftibles and products aifo refemble each other : But the former emit fire when they combine with oxigen. Combuftibles con- tain light . When fupporters and combuftibles combine, the caloric and light fly off in the combination called fire. Combuftion will notenfue if ei- ther of thefc in- REMARRS ON COMBUSTION. mufl conclude that this oxigen in the fupporters contains fomc- thing which the oxigen of the products wants, fomething which feparates during the paflage of the oxigen from the product to the combuflible, and occafions the combuflion, or emiflion of fire, which accompanies this paffage. The oxigen of fup- porters then contains fome ingredient which the oxigen of produces wants. Many circumftances concur to render it pro- bable that this ingredient is caloric. The combujlibles and the producls alfo refcmble each other in feveral refpects. Both of them contain the fame or a fimilar bafe ; both frequently combine with combuftibles, and like- wife with oxigen; but they differ effentially in the phenome- na which accompany their combination with oxigen. In the one cafe^re is emitted, in the other not. If we recollect that no fubftance but a combuflible is capable of reftoring combuf- tibility to the bafe of a product, and that at its doing fo it al- ways lofes its own combuflibility ; and if we recollect farther, that the bafe of a product does not exhibit the phenomena of combuflion even when it combines with oxigen, we cannot avoid concluding, that all combuftibles contain an ingredient which they Iofe when converted into products and that this lofs contributes to the fire which makes its appearance during the converfion. Many circumftances contribute to render it probable that this ingredient is light. If we fuppofe that the oxigen of fupporters contains caloric as an effential ingredient, and that light is a component part of all combuftibles, the phenomena of combuflion above enumer- ated, numerous and intricate as they are, admit of an eafy and obvious explanation. The component parts of the oxigen of fupporters are two ; namely, I . a bafe, 2. caloric : The com- ponent parts of combuftibles are like wife two; namely, 1. a bafe, 2. light. During combuflion the bafe of the oxigen combines with the bafe of the combuflible, and forms the pro- duct ; while at the fame time the caloric of the oxigen com- bines with the light of the combuflible, and the compound flies offin the form of fire. Thus combuflion is a double decompo- fition; the oxigen and combuflible divide themfelves each into two portions, which combine in pairs ; the one compound is the producl, and the other the fire, which efcapes. Hence thereafon that the oxigen of products is unfit for com- buflion. It wants its caloric. Hence the reafon that combuf- tion REMARKS ON COMBUSTION. Q$ tion does not take place when oxigen combines with produces gredients of fire or with the bate of fupporters. Thefe bodies contain no light. be abfent- The caloric of the oxigen of courfe is not feparated, and no fire appears. And this oxigen ftill retaining its caloric, is capable of producing combuftion whenever a body is prefented which contains light, and whofe bafe has an affinity for oxigen. Hence alfo the reafon why a combuftible alone can reftore combuftibility to the bafe of a product. In all fuch cafes a double decompofition takes place. The oxigen of the product combines with the bafe of the combuftible, while the light of the combuftible combines with the bafe of the product. Thus when iron acls on water, the oxigen of the water combines with the bafe of the iron, while at the fame time the light of the iron combines with the hidrogen of the water, and occafions its efcape in the ftate of gas. But the application of this theory to all the different pheno- mena defcribed above, is fo obvious, that it is needlefs to give any more examples. Let us rather inquire into the evidences which can be brought forward in its fupport. 10. Now as caloric and light are always emitted during They muft combuftion, it follows that they muft have been previoufly therefore have component parts either of the combuftible, or of the fupporter, JJ ,n °he com- Or of both. buftible,thefup- That the oxigen of the fupporters contains either one or both Porter» or bot * of thefe fubftances, follows incontrovertibly from a fad already mentioned, namely, that the oxigen of produces will not fupport combuftion, while that of fupporters will. Hence the oxigen of fupporters muft contain fomething which the oxigen of produces wants, and this fomething muft be caloric, or light, or both. That the oxigen of fome of the fupporters at leaft contains References to caloric as an ingredient, has been proved, I think, in a fatisfac- fa&s : Caloric* tory manner, by the experiments of Crawford, Lavoifier, and La Place. Thus the temperature of hot blooded animals is maintained by the decompofition of air. Now if the oxigen of one fupporter contain caloric, the fame ingredient muft ex- ift in the oxigen of every fupporter, becaufe all of them are obvioufly in the fame ftate. Hence I conclude that the oxigen of every fupporter contains caloric as an effential ingredient. The light emitted during combuftion muft either proceed Light, from the combuftible or the fupporter. Now that it proceeds from the combuftible muft appear pretty obvious, if we recoi- led Q() JtKMAllKS ON COMBUSTION. left that the colour of the light emitted during combuftioft varies, and that this variation ufually depends, not upon the fupporter, but upon the combuftible. Thus carbonic acid burns with a blue flange, carbonated hidrogen with a white, and charcoal with a red ; fulphur with a b!ue or violet, zinc with a greenifli white, and phofphorus with a white. Natural forma- The formation of combuftibles in plants obviouily requires *"!!" °( c?Tbuf" *be prefence and agency of light ; for when plants vegetate in porters : Vegc- the dark, their carbon is not increafed, nor is any oily or refin- tation. ous matter formed in them. The leaves of plants emit oxigen gas when expofed to the fun's rays, but never in the fhade, or in the dark. Senebier has demonftrated that this emiffion is occasioned by the decompofition of carbonic acid. This acid, which is a product- of combuftion, is decompofed by the leaves of plants affifted by funfhine, and converted into oxigen gas and charcoal, a. fupporter and a combuftible. This proccfs is exactly the reverfe of combuftion, and mult therefore reftore the fub- ftances which had been loft during combuftion ; that is to fay, caloric and light. But the fun's rays confift of thefe two bo- dies. Thus we fee why plants require funfhine. A part of vegetation confiits in decompofing, or unburning, produces, and converting them into fupporters and combuftibles 5 but for fuch a converfion caloric and light are abfolutely necelTary . The fame effefts Befides vegetation, we are acquainted with two other mc- y "*" thods of unburning products, or of converting them into pro- ducts and combuftible ; by expofing them, in certain circum- ftances, to the agency of fire or of electricity. The oxides of gold, filver, and mercury, when heated to rednefs, are decom- pofed, oxigen gas is emitted, and the pure metal remains be- hind. In this cafe the necefTary caloric and light muft be fur- nifiied by the fire ; a circumftance which explains why fuch reductions always require a red heat. When carbonic acid is made to pafs repeatedly over red-hot charcoal, it combines with a portion of charcoal, and is converted into carbonic ox- ide gas. If this gas be a combuftible oxide, the bafe of the carbonic acid and its oxigen muft have been fupplied with light and caloric from the fire ; but if it be a. partial combuftible, it is merely a compound of carbonic acid and charcoal: which of the two it is, remains ftill to be afcertained. Electricity de- compofes water, and converts it into oxigen gas and hidrogen gas ; it muft therefore fupply the heat and the light which thefe bodies loft when converted into a producl. Thefe REMARKS ON COMBUSTION. 97 Thefe fafts, together with the exad correfpondence of the Application of . . , t r i_ /i- this theory to theory given above with the phenomena ot combuition, ren- other fafts# der it fo probable> that I have ventured to propofe it as an additional ftep towards a full explanation of the theory of combuftion. Every additional experiment has ferved to con- firm it more and more *. It even throws light upon many phenomena which have been hitherto coniidered as altogether anomalous, as will be evident from the following obfervations* II. In the year 1793, the aflbciated Dutch chemifts drew Ignition pro- the attention of philofophers to a curious phenomenon which fio^e0f fulphur" accompanies the formation of fome of the fulphurets ; a phe- with a metal, nomenon previoufly noticed by Scheele ; but which they firft defcribed in detail. When eight parts of copper filings, and three parts of flowers of fulphur are mixed together in a glafs receiver, and the veflel placed upon burning coals, the mix- ture melts, a kind of explofion takes place, it becomes fud- denly red hot, and a glow, like that of a piece of red hot char- coal fanned by bellows, rapidly pervades the whole. When this difappears, the mixture is found in the ftate of folid ful* phuret of copper. Iron, lead, tin or zinc, may be fubfti- tuted for copper. The experiment fucceeds whether the vef- fel be filled with air, or with azotic, or hidrogen gas, or even with water or mercury. What is Angular in this experiment is the glowing red heat, or the emiffion of fire which accom- panies the combination of the fulphur and metal. This emif- fion being the fame which takes place during combuftion, the procefs has been confidered as a combuftion, and ftated as fuch by the German chemifts, as an objection to Lavoifier's theory, which fuppofes that oxigen is a neceflary agent in that procefs : while other philofophers have denied that this operation is a combuftion, or that it has any refemblance to that procefs. The (ame emiffion of caloric and light> or oi fire, takes or of fulphur place when melted fulphur is made to combine with pot-ath, ™lth P°taflJ °5 •II' • mi r r "me > 0r Phof- or with lime, in a crucible or glais tube, and hkewife when phorus with lime, &c» * In the preceding enumeration of facts I have not taken notice of the modifications which the Lavoiferian theory has received from Hntton, Delametherie, Richter, and Brugnatelli j becaufe I fup- l>ofe them iufficiently known. Every one of thefe modifications agrees in fome particulars with the theory given in thi-s Paper, but differs from it in others. Vol. II.— June, 1802, H melted 9$ REMARKS ON COMBUSTION. jive out caloric and light j i. e fire. melted phofphorus is made to combine with lime heated nearly to rednefs. In all probability barytes and ftrontian exhibit the fame phenomenon when combined with melted fulphur or phofphorus ; and fome of the metals when combined with phofphorus. In general then the emiflion of fire accompanies the combination of melted fulphur and phofphorus, with fe- veral of the earths, fixed alkalies and metals, heated previ- oufly to a certain temperature. Explanation. To explain the phenomenon we have only to recollect, 1 . Fufed fulphur or That the fuiphUr and phofphorus are in the melted date, and phofphorus con- ... . ,. „,, . , tain caloric : me- therefore contain caloric as an ingredient. 2. That the al- tal. &c. contain kalies, earths and metals which produce the phenomenon in come Mid in queftion, contain light as an eiTential ingredient. 3. That combination and the fulphuret or phofphuret formed is always in a folid ftate ; thefe three points once cftabliflied, the procefs admits of a very flmple explanation. The fulphur or phofphorus com- bines with the bafe of the metal, earth or alkali ; while at the fame time the caloric to which the fulphur or phofphorus owed its fluidity, combines with the light of the metal, earth, or alkali, and the compound flies off under the form of fire. The procefs re- Thus the procefs is exactly the fame with combuftion, ex- if" cepting as far as regards the produd. The melted fulphur or ^phofphorus acts the part of the Jupporter, while the metal, earth or alkali occupy the place of the combuftible. The firft furniihes caloric, the fecond light, while the bafe of each combines together. Hence we fee that the bafe of fulphurets and phofphurets refembles the bafe of products in being defti- tute of light, the formation of thefe bodies exhibiting the fepa- ration of tire like combuftion, but the product differing from a product of combuftion in being deftitute of oxigen, we may diftinguifh the procefs by the title of femi-combuftion ; indi- cating by the term, that it polTefTes one half of the characle- riftic marks of combuftion, but is deftitute of the other half. The only part of this theory which requires proof is, that light is a component part of the earths and alkalies. But as potafh and lime are the only bodies of that nature, which I am certain to be capable of exhibiting the phenomena of femi- combuftion, the proofs muft of neceffity be confined to them. Now that lime contains light as a component part has been long known. Meyer and Pelletier obferved long ago, that when water is poured upon quicklime not only heat but light is emitted. Light is emitted alfo abundantly when fulphuric 2 acid tion except ia its product 5 termed femi combuftion. Facts to mew that potafh and lime contain light. REMARKS ON COMBUSTION. 99 Acid is poured upon lime*. In both cafes a femi-combuftion Semi-combuf- takes place. The water and the acid being folidified give JJ™ °f hme and out caloric, while the quicklime gives out light; that lime during its calcination combines with light, and that light is a component part of quicklime is demonftrated by the following experiment, for which we are indebted to Scheele. It is well known that fluor fpar (native fluate of lime) has Phofphorefcence the property of phofphorefcing ftrongly when heated, bat that plain£jr par e** the experiment does not fucceed twice with the fame fpeci- men. After it has been once heated fufficiently, no fubfe- quent heat will caufe it to phofphorate. Now phofphoref- cence is merely the emiffion of light, light of courfe is a com- ponent part of fluor fpar, and heat has the property of fepa- rating it. But the phofphorefcing quality of the fpar may be again recovered to it, or which is the fame thing, the light which the fpar had loll may be reftored by the following pro- cefs. Decompofe the fluate of lime by fulphuric acid, andreftored» preferve the fluoric acid feparated. Boil the fulphate of lime thus formed with a fufficient quantity of carbonate of foda; a double decompofition takes place ; fulphate of foda remains in folution, and carbonate of lime precipitates. Calcine this precipitate in a crucible till it is reduced to quicklime, and combine it with the fluoric acid to which it was formerly united. The fluor fpar thus regenerated phofphorefces as at firfl. N Hence the lime during its calcination mnft have com* bined with light. That potafti contains light, may be proved in the fame man- Light in potato.' ner as the exiftence of that body in quicklime. Dize has fiiown that much light is emitted when fulphuric acid is poured upon potafh, but more when it is poured on the carbonate of potaih. Now as potafti is deprived of its carbonic acid by lime, it is obvious that the procefs muft be a double decom-* pofition ; the bafe of the lime combines with carbonic acid, while its light combines with the potafh. Thefe remarks on femi-combuftion might eafily be extended much farther. For it is obvious, that whenever a liquid com- bines with a folid containing light, and the product is a folid body, fomething analogous to femi-combuftion muft take place. Hence the reafon why water increafes the violence of combuftion when thrown fparingly into a common lire. * Dize Jour, de Phyf. 49, 177. H 2 XX. A 100 OBSERVATIONS ON SPONTANEOUS LIGHT. IX. A Continuation of the Experiments and Obfervations on the Light which is fpontaneoujly emitted from various Bodies ; with fame Experiments and Obfervations on folar Light, when imbibed by Canton's Phofphorus. By Nathaniel Hulme, M.D.F. R.S. andA.S. (Concluded from page 40 .) § 5. The Efftcls of carbonic Acid Gas or fixed Air * on fpontaneous light. EXPERIMENTS. Carbonic acid £™ i.At 10 P.M. a piece of frefh herring, weighing gas extinguifhes tf- ■ _ Y . ., , , ° Spontaneous about three drams, was impended in a wide-mouthed ten- light; but it re- ounce phial, filled with carbonic acid gas, and clofed with a mon air. ° ' cor^ all(* bladder. It was retained there for three fucceffive nights ; but emitted no light. Exp. 2. The fame experiment was made with a piece of herring, which was beginning to be luminous. On the next evening, the illumination was found to be extincl: : never- theless the herring was ftill kept in the gas for three nights longer, but did not become lucid. Exp. 3. At 7 P. M. a piece of frefli mackerel was intro- duced above water, into a wide-mouthed bottle, holding 24 ounces, which was completely filled with carbonic acid gas, and fupported by a tea-faucer that held about three ounces of water. On the fecond night it was dark, and continued the fame on the third. It was then expofed to the influence of atmofpherical air, and, on the next evening, it was pretty luminous, and likewife on the fucceeding night. Exp. 4. At 9 P. M. a cork, fmeared with the luminous matter of a mackerel, was put into a five-ounce wide-mouthed phial, filled with carbonic acid gas, and then clofed with a glafs * This gas was obtained from powdered chalk, or marble, and diluted fulphuric acid, fiopple. OBSERVATIONS ON SPONTANEOUS LIGHT. 101 itopple. It continued to fhine pretty vividly for fome little time ; then the light gradually diminifhed, fo that at twelve, only a fmall fpark remained. Exp. 5. At 10 P. M. another cork, illuminated with mac- kerel-light, was introduced above water, into 24- ounces of the gas ; and its light was nearly extinct at twelve. Exp. 6. At 8 P. M. a fragment of fhiniug wood was put above water, into 24 ounces of the gas ; and it had not been long there before the light difappeared. It was then taken out, and expofed to the action of atmofpheric air, when its Alining property foon returned. Exp. 7. Another fragment of brightly mining wood was in- troduced above water, into the fame quantity of the gas, at 10 P. M. and the light was extinguifhed in the fpace of an hour. After this, it was expofed to the open air, and the light gradually revived. Exp. 8. At 8 P. M. a luminous dead glow-worm was put above water into the gas ; its glowing appearance gradually faded, and in a fhort time became quite invifible. It was then taken out, and the light, by degrees, re-appeared as vivid as before, OBSERVATION. This gas, we find, has alfo an extinguifliing property, with refpect to fpontaneous light : but, in general, the light returns, if the object of experiment be taken out, and expofed to the open air. § S The Effects of fulphu rated hidrogen Gas * on fpontaneous Light ', EXPERIMENTS. Exp. 1. At noon, apiece of a very frefli mackerel, with Sulphurated hi- a bright eye, was introduced above water, into 24- ounces dr0&fn e*tm- of this gas, and was retained therein for three fucceflive neous light more evenings, without emitting any light. It was then expofed to effeftua!]y anc* atmofpheric air ; yet it continued dark on the two following hentfrtban car- bonic acid. * This gas was obtained from fulphuret of potafh and diluted muriatic acid. nights ; ]02 OBSERVATIONS ON SPONTANEOUS LIGHT. nights : but, on the third, it was very luminous, and remained fo on the fourth and fifth. Exp. 2. The fame experiment was then made with a piece of frefh herring, which was alfo kept in the above gas, for about three nights, without being luminous. After expofure to common air, it did not emit any light during the firft 24 hours. However, on the fubfequent night, it began to fhine, had a very bright light on the following evening, and conti- nued (hining for feveral fucceeding nights. Exp. 3. A cork, fmeared with the luminous matter of a herring, was put above water, into 2 4 ounces of the gas ; and the light was extinguiflied in lefs than an hour. The experi- ment was repeated in the fame gas, and with the fame refult. Exp. 4. A cork, illuminated with mackerel light, was in- troduced into the fame quantity of gas ; and was dark in half an hour. Exp. 5. A fragment of fhining wood, being put into the gas, became dark in eight minutes. A fecond piece became dark in five minutes. They were then taken out, and conti- nued dark all that evening. On the next evening, one of the pieces was uncommonly lucid. Exp. 6. At 10 P. M. another fragment of brightly fhining wood was introduced above water, into 24 ounces of the gas, and was extinct at eleven. It was then expofed to the open air ; but there was no return of light that evening. On the following night, it was found pretty luminous. Exp. 7. A finely Alining dead glow-worm was next put above water, into this gas, and its light was quickly extin- guifhed. In a fecond experiment, in the fame gas, the light was much flower in its extinction. In both inftances, after the infect was withdrawn, and placed in atmofpheric air, the light gradually revived. OBSERVATION. It is apparent, by thefe experiments, that fulphurated iiidrogen gas extinguifhes fpontaneous light much fooner than carbonic acid gas, and that, in general, the light returns much more flowly, when the fubject is expofed to atmofpheric § 7. OBSERVATIONS ON SPONTANEOUS LIGHT. 103 § 7- The Etftfts of nitrous Gas * on fpontaneous Light. EXPERIMENTS. Exp. I. A piece of frefli herring was introduced above Nitrous gas water, into this gas, at 3 P. M. and remained there four nights, J^^L3"^^ without emitting any light : it was then withdrawn, and ex- guifhes iponu- pofed to common air, for the fpace of three nights ; but did neous h&ht* not become lucid. Exp. 2. The fame experiment was made with a piece of herring beginning to be luminous ; but its light was gradually extinguished : it was detained in the gas for three nights, and taken out dark. It was then expofed to the open air, for the three fubfequent nights ; but its fhining appearance did not return. Exp. 3. A cork with luminous matter, introduced above water, into this fpecies of gas, had its light, in general, ex- tinguifhed in from 10 to 30 minutes; and, when taken into common air, its light very feldom re-appeared. Exp. 4. Fragments of fliining wood, above water, in nitrous gas, were likewife commonly rendered dark in a very fliort ipace of time, as in three or four minutes ; fometimes a frag- ment, if uncommonly luminous, would no! be extinguished in lefs than fix or eight minutes ; and very feldom would the light revive, on expofing the wood to atmofpherical air. Exp. 5. A dead mining glow-worm being put above water, into this gas, its light was quickly extinquifhed ; but, after the infect was taken into the common atmofphere, the light gradually returned. The experiment was thrice repeated, and with the fame refult. OBSERVATION. This fpecies of gas, we obferve to have totally prevented the emiffion of light, and to have quickly extinguifhed that which had been emitted : likewife that the luminous objects which had been under its influence, (except the glow-worm) did not experience a revival of their light, when taken out, and kept for fome time in common air. * This gas was obtained from copper and diluted nitrous acid. § 8. 104* OBSERVATIONS ON SPONTANEOUS LIGHT-. § 8. The FJfecls of a Vacuum on fpontaneous Light. EXPERIMENTS. The light Is ex- £xp. I. A piece of mining wood, of a moderate fize, was tmguifhed in _ . , Al . ~ ° . . , . vacuo, but beau- Put under the receiver or an air-pump, in a darkroom; in tifully reftored proportion as the air was extracted, the light was gradually bv/dmiffionof extinguilhed, and at laft reduced to a mere point, juft vifible, owing molt probably to a fmall refiduum of air, which is al- ways left, even in the mofl perfect machine. Frefh air was then leifurely admitted, and the light was immediately revived in a very beautiful manner. This experiment was frequently repeated, and always with the like effect. Exp. 2. Some luminous matter of a herring, uncommonly bright, was fmeared upon a piece of red blotting paper, and then fubmitted to the operation of the air-pump. The light became fainter and fainter, as the inclofed air was withdrawn, and at laft nearly vanifhed ; but brightened up as before, on the influx of frefh air. The experiment was repeated, and with the fame refult. SECTION XII, Experiments and Obfervations on folar Light, when imbibed by Canton's Phofphorus. § i. Tlw Effects of Heat on imbibed folar Light. J. The imbibed Light is rendered more vivid by a moderate Degree of Heat. EXPERIMENTS. Canton's phof- E*P* 1 • Having prepared fome Canton's phofphorus, and phorus fhines expofed it to the light of the fun, it was carried into the dark Sated!1*" laboratory, to feparate the illuminated parts from thofe that remained dark. In doing which, fofne luminous fragments were placed upon the palm of the hand, and retained there for fome time, when it was obferved, that the warmth, of the hand confiderably increafed the degree of light. Exp. 2.. OBSERVATIONS ON SPONTANEOUS LIGHT. 105 Exp. 2. Some fragments of this illuminated phofphorus were put into a fmall phial, which was then doled with a cork, and fufpended, by a ftring, in a quart of water heated to about ] 26° ; by thefe means, the light was rendered much more vivid than before. Exp. 3. Some other pieces of the illuminated phofphorus were dropped feparately into a glafs tube 32 inches long, and T7^ bore, filled with water at about 120°. The light of each piece became exceedingly bright, as foon as it entered the hot water ; and they all defcended, very luminous, from the top to the bottom, fome quickly and others flowly, according to their gravity, making a very pleafing experiment. Exp. 4. A large wooden bowl, about 12 inches wide, was next filled with water heated to abput 110°, and then a quan- tity of illuminated phofphorus, partly in the form of powder, and partly in pieces of different magnitudes, was fcattered over the whole furface of the water ; all which pieces fell, with increafed fplendour, to the bottom, where they preferved their light for fome time, II. The imbibed Light is extiriguijtod by a great Degree of Heat, but too much heat extinguish. Exp. 5. Some fragments of the phofphorus, rendered lumi-es it. nous, were expofed to a greater degree of heat, namely, by cafting them into a tin veiTel containing two pints of boiling water. They flamed with increafed light, as foon as they came in contact with the water, fell precipitately to the bot- tom, in a lucid ftate, and then were gradually extinguifhed. Exp. 6. In which the degree of heat was fiill increafed. A fmall bar of iron, of about an inch fquare, was made red-hot, and laid horizontally in the laboratory, until, by cooling, it nearly ceafed to mine. Some pieces of illuminated phofpho- rus were then put upon it in fucceffion, and the light, in a mo- ment, glowed with uncommon luftre, but was quickly after totally extinguifhed *. * Solar light, when received merely on a piece of white paper, may alfobe rendered more luminous by heat, and then extinguished by it, as appears from an experiment made by the late Mr. §. Wilfon, whofe book on phofphori I had not feen before thrs Paper was drawn up. 10(3 OBSERVATIONS ON SPONTANEOUS LIGHT. Latent light is HI. The imhibed Held, after behw in a latent State, it excited excluded from , _>,, • ,, . ~ TT Canton's phof- an(i rendered luminous by the Agency of Heat. Exp. 7. Some fmall pieces of the phofphorus, after having been illuminated, were depofited in the laboratory ; when the light by degrees faded away, and became totally invifiblc. They were kept in this dark ftate for the fpace often days, and then placed one after another upon a heated bar of iron, as in the laft experiment, upon which they quickly became exceedingly luminous. From an experiment made by the ingenious Mr. Canton, I obferve, that fome of his phofphorus, contained in glafs balls hermetically fealed, and heated in the above manner, gave a confiderable degree of light, after it had been kept in a ftate of darknefs more than fix months. Phil. Tranf. Vol. LVIII. page 342. § 2. The Effects of Cold on imbibed Light, . « EXPERIMENT. Coldextinguifh- About 15 grains of the phofphorus were put into a half- of Canton's ce Pn*a*> containing two drams of cold pump water, that phofphorus, &c. had been deprived of its air by boiling. The phial was then corked, and expofed for fome time to folar light, whereby the phofphorus became finely illuminated. In this flate, it was immediately put into a frigorific mixture, compofed of fnow and fea fait, and retained there about 30 or 40 minutes, when it was taken out, and the light found to be totally ex- tinguifhed. The phial was then placed in fome water, at about 60° temperature, and the light gradually revived, and became as brilliant as before it had been expofed to the cold. This experiment was frequently repeated, and always with the fame refult, I cannot but remark, that in the courfe of experiments on this fubjeci, the fuperior power of folar over that of fponta- neous light w^s very apparent. For, the firft trials being made in fmall phials, containing only atmofpheric air with the phofphorus, the light was with fome difficulty totally extin^ guiihed ; and, after the phials were taken out of the frigorific mixture^ OBSERVATIONS ON SPONTANEOUS LIGHT. 107 mixture, the temperature of the laboratory would commonly foon revive the light, which rendered the experiments not al- together fatisfactory. Finding it thus fomewhat difficult to extinguifh folar light in air, recourfe was had to water, in the manner above described. This anfwered perfectly well ; for the water, when frozen, gave a fubftantial body, as it were, to the imbibed light of the phofphorus, lb as to enable it to retain the excefs of cold anting from the frigorific mixture; thereby making the experiments quite fatisfactory. When the phofphorus was thus furrounded by ice, only a few minutes ftay in the frigorific mixture would generally be fufficient for a total extinction. OBSERVATION. From thefe experiments, compared with thofe recited in my former Paper on fpontaneous light, it appears that folar light, when imbibed by Canton's phofphorus, is fubjeel to the fame laws, with refpect to heat and cold, as the fpontaneous light of fifhes, rotten wood, and glow-worms. P. S. In thefe experiments with folar light, the phofphorus was fometimes expofed to the direct rays of the fun, at other times to common day-light, in a northern afpect ; and it was remarked, that it became fomewhat more luminous by mere day-light, than by the rays of the fun. It may alfo be proper to obferve, that the above experi- Improved pre* ments were made with an improved preparation of Canton's Paratl°" of Can* . . r r l ton s pholpho- pholphorus. This improvement, which was firft made by Dr. rus by Dr. Hig- Higgins, confiits in omitting the pulverization of the (hells. Sins* His method was, after calcining the oyfter-fhells, to put the pieces, both great and fmall, in layers, into a crucible finv nifhed with a cover, and to fprinkle flowers of ful phur between each layer. After they had remained fome time in the fur- nace, they were taken out, fuffered to cool, and then kept in a large bottle with aglafs ftopple. For this communication, I am indebted to Mr. Lewis of Holborn, near Southampton- Dark room of ftreet, who has an extraordinary dark room, where, at times, Mr* *-*ewis» he amufes his friends with fome beautiful appearances, arifing from folar light imbibed by phofphorus prepared as above di- rected. A ltill further improvement of this phofphorus, it appears to me, may be made by fubllituting precipitated ful- phur for the flowers of fulphur ; and the experiments of this feftipn were chiefly made with phofphorus fo prepared. X. Defcription 108 DESCRIPTION OF A LAMP. Defer iption of a Lamp upon Aiigand's Principle, with Im- provements, in which the Oil is maintained at the fame Level by the conftant Aclion of a Pump. By Citizens Car c el and Careau *. Excellence of JLiAMPS with a double current of air are among the inven- gand.amP ° f* t'0ns °^ tne c'g^teenth century, which are molt honourable to the induflry of France, and of which the general ufe fufficiently befpeaks the value. But it is not enough that a great light fliould be produced without fmell or fmoke, but an objed of nearly equal utility confifls in producing the light fteadily, with economy, in the moil advantageous form, and bell adapt- ed to economical purpofes. Improved by Citizens Carcel and Careau have fucceeded in this object. £53? and Ca" We mal1 not dwel1 uPon the obflacles they muft have met with in arriving at the degree of perfection they have obtain- ed ; it will be fufficient to fhew the value of their invention, if we can prove that it furpaffes every thing of the kind which has yet been exhibited. This lamp has the double advantage of exhibiting all the good qualities of the lamp we hefore pof- feffed, without their inconveniences. The nozle undergoes no alteration by heat, neither is the wick deilroyed, but almoft conflantly preferves its whitenefs. Inconveniences The oil in ordinary lamps is liable to flow out by its expan-. otiamps of the {10n wnen heated ; but in this mechanical lamp it conflantly ufual conftruc- _ _ *, T tion. prelerves its level. By difpeniing with the relervoirs of oil in thofe lamps which are called fountain lamps, thefe inventors have fucceeded in affording light which is not fliaded on any fide. In this refpect the lamp is very economical, becaufe nearly half the light of a fountain lamp mufl neceflarily be in-. tercepted by the receiver, which requires to be placed above the level. But in thefe the refervoir is in the foot, which ren- ders them more portable ; and from this circumflance, as well as the other advantages of their conflruction, there is no dan- * From Les Annales des Arts & Manufactures, vi. 269. I am much obliged to my correfpondent C. D. for directing my atten-* tion to this article, ger DESCRIPTION OF A LAMJP. 109 ger of (pilling the oil by inclining it, which is an inconvenience of great magnitude, and hitherto conftituting one of the great- eft objections to the lamps in ufe. In other lamps the flame varies in its intenfity commonly in about two hours ; but in the mechanical lamp it conftantly preferves the fame fupply and the fame brilliancy. ' The median ifm adapted to the foot in order to caufe the General re- oil to afcend, has been reduced to the greateft fimplicily; it ismarks» firm and durable, and has no communication with the oil of the refervoir. This lamp may be ufed in diftillations and chemical prepa- rations, as well as in culinary purpofes; and in general we cannot do better than tranfcribe the report made to the Na- tional Inftitute by Guyton, Morveau, and Charles. " The Clafs having charged us to examine the mechanical Report to the lamp prefented by the Citizens Carcel and Careau, at the fit- *nr,*ute of ting of the 21ft of iaft month, as a means of adding a new de- gree of perfection to lamps with an inner current of air, as well as with regard to the intenfity of light as to economy and the convenience of daily ufe. " Lamps excited by an interior current of air, of which theHiftory of the invention belongs to Citizen Argant, and which were an- ^S^ lamP« pounced for the firft time in February 1784*, have produced a revolution in the art of illuminating which time has ferved only to confirm, as it does all thofe which, being founded on true principles, receive the daily fandion of experience. '* A fhort time afterwards Citizen Lange thought of con-The chimney trading the glafs chimney, fo as to diredthe external current improved by of air nearer to the flame, by which means he determined a ftill anse* more complete combuftion of the oil, and produced a more brilliant light, without either fmoke or fraell. The union of thefe inventions feemed to have exhaufted the fubjed, but Citizens Carcel and Careau apprehended that it was poffible to renderimprovements the lamps ftill more perfed. They confidered that the beft bv Carcel and lamps of this defcription do not conftantly afford the fame in- areau* tenfity of light, becaufe the wick not being conftantly and alike fupplied with oil, is fubjed to b-come charred; that it is ne- ceffary either to raife it beyond the proper elevation, or to *rim the lamp again after fome hours; andlaftly, that the glafs # Journal de Phyfique for that month, page 159. chimney 110 DESCRIPTION OF A LAMP. chimney not being capable of being made to that degree of accuracy as to afford the contraction always at the fame height, the effect of this contrivance could not be thebeft pof- fible, excepting when the accidental concurrence of circum- flances might render it fo. " At the fame time that they were bufied in remedying thofe inconveniences, they did not neglect the means of ren- dering the lamp more economical, convenient, and portable ; without fear of fpilling the oil ; without any confiderable effect upon the flame by motion ; without any interception of the light from a refervoir; and with the addition of an agreeable and ornamental form. 0' 228 OBSERVATIONS ON VENTRILOQUISM, unexpected quarter, in confequence of which the reflector will appear to be the fpeaker. Nature Teems to fix no bounds to this kind of deception, only care muft be taken not to let the path of the direct pulfcs pafs too near the head of the perfon who is to be played upon ; for, if a line joining the exhibitor's mouth and the reflecting body approach one of his ears too nearly, the divergency of the pulfes will make him perceive the voice itfelf inftcad of the reverberated found* Narrative of a '« The only ventriloquift I ever attended, acted in ftriCt con- but it never feemed to proceed from any part * of the wall, near the heads of the people prefent ; on the contrary, it was always heard refembling the voice of a child, who feemed to be under the benches. He flood during the time of fpeaking in a looping pofture, having his mouth turned towards the place from which the found iflued ; fo that the line joining his lips and the reflecting object, did not ap- aoifes from a proach the ears of the company. Second: advancing into the cupboard, vacant part of the room, and turning his back to the audience, he made a variety of noifes, that feemed to proceed from an open cupboard which flood directly before him, at the diflance cries from an in- of two or three yards. Third; he placed an inverted glafs verted cup. cup on ^e jian(js 0f j^js hearers, and then imitated the cries of a child confined in it. His method of doing it was this; the upper part of the hearer's arm laid clofe along his fide ; then the part below the elbow was kept in an horizontal po- rtion with the hand turned downwards, which was done by Method of ope- the operator himfelf. After taking thefe preparatory fieps, Mtmg. ^ man kent j^ kocjv forWards in a fituation which prefented the profile of his face nearly to the front of his hearer, whilft his mouth pointed to the cup ; in which pofture he copied the voice of a confined child fo completely, that three pofi- tions of the glafs were eafily diftinguifhed by as many diffe- rent tones, viz. when he prefled the mouth of the cup clofe againft the palm, when one edge of it was elevated, and when ACCOUNT OF A MINERAL SUBSTANCE. 129 when tlie veifel was held near the hand but did not touch it. The fecond and third inftances of ventriloquifm afford ftrong proofs, that this delufive talent is nothing more than the art of i ubftituting an echo for the primary found ; for, befides the change perceivable in the direction of the voice, it was found to be blended with a variety of fecondary founds ; fuch as we know by experience are produced as often as a noife of any kind ifTues from a cavity. I have already made fome remarks Remarks ani on this fpecies of knowledge ; but it would be improper to obfervatlons« difmifs the fubject without noticing the accuracy, with which the ear recognizes the finer modifications of founds, and their caufes. I have frequently obferved; that a certain waterfall makes a flatter and duller noife when the ground is covered with 'fnow, than that which it affords at other feafons. The human voice alfo undergoes a fimilar change within doors, by ftriking a multiplicity of foft bodies, fuch as a number of piles of wool, or a crowded congregation in a church. The method of preventing the vibration of the vocal organs Difficulty not from reaching the external teguments, is ftill wanting to com- folved» plete this theory of ventriloquifm ; and I prefume it can only be fupplied by an adept in the art. I mufl therefore difmifs the fubject unnniflied, becaufe I have no pretention to that character; XV. An Anah/fis of a Mineral Subjiance from North America, con* taining a Metal hitherto unknown . IfyCkARLEsHAtCHETT, Efq.*. I N the courfe of the laft fumrrier, when f was examining Specimen of mi- and arranging fome minerals in the Britifh Mufeum, I ob- neral obferved in rved a fmdll fpecimen of a dark-coloured heavy fubftance, feUm. rhich attracted my attention, on account of fome refemblance which it had with the Siberian chromate of iron, on which at that time I was making experiments. Upon referring to Sir Hans Sloane's catalogue, I found that Hiftorical par* * this fpecimen was only defcribed as " a very heavy black ftone, cu,a"» Philof. Tranf. 1802. Vei II,— Junk, 1802, K « with ]30 ACCOUNT OF A MINERAL SUBSTANCE. " with golden ftreaks," which proved to be yellow mica; and it appeared, that it had been fent, with various fpecimens of iron ores, to Sir Hans Sloane, by Mr. Winthrop, of Maf- fechufets. The name of the mine, or place where it was found, is alfo noted in the catalogue ; the writing however is fcarcely legible : it appears to be an Indian name, (Naut- neauge) but I am informed by feveral American gentlemen, that many of the Indian names (by which certain fmall diftricts, hills, &c. were forty or fifty years ago diftinguifhed,) are now totally forgotten, and European names have been adopted in the room of them. This may have been the cafe in the pre- fent inftance ; but, as the other fpecimens fent by Mr. Win- throp were from the mines of Mafiachufets, there is every reafon to believe that the mineral fubftance in queftion came from one of them, although it may not now be eafy to iden- tify the particular mine. § I. DESCRIPTION OF THE ORE. Defcription. The external colour is dark brownifh gray. The internal colour is the fame, inclining to iron gray. The longitudinal fracture is imperfectly lamellated ; and the crofs fracture (hews a fine grain. The luftre is vitreous, flightly inclining in fome parts to metallic luftre. It is moderately hard, and is very brittle. The colour of the ftreak or powder is dark chocolate brown. The particles are not attracted by the magnet. The fpecific gravity, at temp. 65°, is 5918 *. Experiment 1. The ore was di- Some of ^e ore> reduced to fine powder, was digefted in gefted in muria- boiling muriatic acid for about one hour. tic acid. Little aftion. « rp^e f0ijow;ng refults of fome experiments which I have pur- pofely made, will fhew how much the fpecific gravity of this ore is different from that of Wolfram, and Siberian chromate of iron. Pure Wolfram, free from extraneous fubftances, at tem. 65° 6355, Siberian chromate of iron, containing fome of the green oxide 3728. Pure Siberian chromate of iron - 4355. The Siberian chromate of iron, like all other mineral fubftances which are not cryftallized, and which confequently are not always homogeneous, muft evidently be liable to confiderable variations in ipecific gravity. The ACCOUNT OF A MINERAL SUBSTANCE. 13,1 The acid appeared to have acted but flightly upon the pow^ tier ; as the former remained colourlefs, and the latter did not feem to be diminiflied. A portion, however, chiefly of iron, was found to be diflblved ; for ammonia formed a yellow floc- culent precipitate ; prufliate of potafli produced one which was blue ; and tincture of galls, when the excefs of acid had been previoufly faturated by an alkali, formed a precipitate of a rich purplilh brown colour. Experiment 2. Another portion of the powder was, in like manner, digefted In nitric acid.: with nitric acid ; but, excepting fome flight traces of iron, '" e aftlon* this acid afforded nothing worthy of notice ; the action of it upon the ore, was indeed fcarcely perceptible. Experiment 3. Some of the pulverized ore was digefted with concentrated In fulphuric fulphuric acid, in, a ftrongly-heated fand-bath, until nearly the *c' , „. whole of the acid was evaporated ; the edges of the mafs then appeared blueifli, and became white, when boiling diftilled Water was added. This acid certainly acted much more powerfully than thofe which have been mentioned ; but ftill only a fmall part of the ore was diflblved. It muft however be obferved, that a very copious blue precipitate was obtained by prufliate of potafli ; a plentiful purplilh brown precipitate was alfo produced by tine-" ture of galls, after the excefs of acid had been faturated by an alkali; and, laftly, when the yellow ferruginous precipitate formed by ammonia was diflblved in diluted nitric acid, fome white flocculi remained, which were completely infoluble in the acid, even when it was added fo as to be in considerable excefs. From thefe experiments it was evident, that the ore could lot readily be decompofed by the direct application of the lineral acids ; and I therefore had recourfe to the following tethod, which has frequently been employed with fuccefs in imilar cafes. ANALYSIS. A. A mixture of 200 grains of the powdered ore with five times Fufion with car- le weight of carbonate of potafli, was expofed to a ftrong red ^nate of potafh. K 2 heat, , 132 ACCOUNT OF A MINL'RAL SUBSTANCE, heat, in a filver crucible. As foon as the matter began to fiW,- a very perceptible effervefcence took place ; and, when this had fubfided, the whole was poured into a proper vefTel. The mafs, when cold, was grayifh-brown. ferlefta brown" BoilJnS diftiIIed watcr was poured upon it ; and the brown refidue. refiduum, which wasconfiderable, was well edulcorated upon a filter. Predp. by ni- The filtrated liquor had a flight yellowifh tinge, and, being white flakes, fuperfaturated with nitric acid, afforded a copious white floe- culent precipitate, which fpeedily fubfided ; but, although a very coniiderable additional quantity of nitric acid was poured upon the precipitate, it was not re-diffolved. The refidue did The refiduum of the ore was dark brown, and was a^ain not yield to fu- . , / ° fion bypotafh. me'ted with potafli. and treated as before ; but fcarcely any effeel was thus produced ; the alkali was therefore warned off, It was therefore and the powder was digefted with muriatic acid, which foon mm-, acid* aflunied the deep yellow colour ufually communicated to it by which took up iron. After half an hour, the acid was decanted, and the ,ron* refiduum was wathed with dift illed water. This refidue was This powder was now of a much paler colour : and, being fufed with pot- , . , n . i , , , , / ? afh, and precipi- mixed with potafli, it was melted and treated as before. A tated as before, coniiderable precipitate was again obtained by the addition of What was left n^"c ac*d > and ^ie refiduum, after being digefted with mo- was treated in riatic acid, was again fufed with potafli, by which means the ner. man~ wno*e was completely decompofed, after about five repetitions of each operation. B. The muriatic The muriatic folution was diluted, and, being faturated with te^wkii ^^o- ammon»a> afforded a plentiful ochraceous precipitate ; which nia afforded the again was diffolved in cold dilute nitric acid, and afforded a fmall quantity of a white infoluble fubftance, fimilar to that which was obtained from the alkaline folution. From thk nitric folution, I then obtained, by means of ammonia, a pre- cipitate of oxide of iron, which, being properly dried, weighed 40 grains. C. The nitric pre- The different alkaline folutions which had been made fubfo cipitates were a qUent to that which has been firft mentioned, were mixed to- gether, and, being fuperfaturated with nitric acid, afforded the fame white infoluble precipitate; the total quantity of which, obtained from 200 grains of the ore, amounted to •about 155 grains. The ACCOUNT OP A MINERAL SUBSTANCE, 133 The liquor from which this precipitate had been feparated ^^^ by nitric acid, was then faturated with ammonia, and, being more -non% toiled, afforded about two grains of oxide of iron. I obtained, therefore, from ?00 grains of the ore, Grains. Grains. Oxide of iron r ? - ^2 1 = 197. And of the white precipitated fubftance 155 3 But, as I could not repeat the analyfis without deftroving tke remaining part of the only fpecimen at prefent known of this ore, I do not wifh the above ftated proportions to be reT garded as rigidly exad; it will be fufficient, therefore, to fay at prefent, that the ore is comppfed of about three parts of the white matter, and rather lefs than one of iron. § II. PROPERTIES OF THE WHITE PRECIPITATE. A. It is of a pure white, and is not extremely heavy. The white' pre- It has fcarcely any perceptible flavour, nor does it appear tq *'P,tat? be foluble in boiling water; when, however, fome of the powder is placed upon litmus paper moiftened with diftille4 water, the paper in a few minutes evidently becomes red. B. 1 . When examined by the blow-pipe, it is not fufible per is infufible, Je in a fpoon of platina, nor upon charcoal, but only becomes of a lefs brilliant white. 2. Borax does not appear to a£t upon it ; for the white par- not affe&ed by tides are only difperfed throughout the globule, 3. It produces an effervefcence when fufed with carbonate Soluble by fufion of foda, and forms a colourlefs fait jj but, if too much of it be witil f°da> added, then the mafs, when cold, appears like a white opaque enamel. 4. When carbonate of potafli is employed, the. effects are and with potato, fimilar in every refpect to thofe of foda ; and it may here be remarked, that the faline combinations thus formed with foda, or potafli, are foluble in water ; and that thefe folutions have as in the firft the fame properties as that which was formed when the ore decompofition. was decompofed by an alkali. The portion of the white pre- cipitate which may be in excefs, fubfides unaltered, when the globules are dhTolved in water. 3 5. Phof- 134? ACCOUNT OP A MINERAL SUBSTANCE. Phofphate of 5. Phofphate of ammonia produces a very marked effect ; a"«°nbTue°r™S. for> iyhen meIted in a PIatina rPoon> if> fome of the white fub- bulc. fiance be added, a confiderable effervefcence takes place, and the two fubfiances rapidly unite. The globule, when cold, is deep blue, with a tinge of purple, but, when held between the eye and the light, it appears of a greenifh gray colour, C. It refifts nitric It is perfectly infoluble, and remains unchanged in colour, and in every other refpect, when digefled in boiling concen- trated nitric acid. D. is foluble in ful- It is dilfolved by boiling fulphuric acid, and forms a tranf- gjyy *C1|!.I parent colourlefs folution, which is however only permanent tJon kts fall a while the acid remains in a concentrated flate ; for, if a large fulphate. quantity of water be added to the folution, or if the latter be poured into a veflel of diftilled water, the whole in a few minutes aflumes a milky appearance, and a white precipitate is gradually depofited, which cracks as it becomes dry upon the filter, and, from white, changes to a lavender blue colour, and again, when completely dry, to a brownifh gray. It is then infoluble in water, has not any flavour, is femi-tranfpa- rent, and breaks with a glofly vitreous fracture, This fubftance is much heavier than the original white pre- cipitate ; and in a very flight degree may be dilTolved by boil- ing muriatic acid, or by boiling lixivium of potafli. Upon examining thefe folutions, I found that both contained the original white fubflance, together with fome fulphuric acid j fo that the precipitate obtained from the fulphuric folu- tion by the addition of water^ is a fulphate of the white matter *. The whole is not however precipitated by water ; for a part remains in folution, which may be feparated from the fulphuric acid by either of the fixed alkalis, or by ammonia. *thc fulphuric The fulphuric folution is not rendered turbid by the addition folution afforded 0f water until fome minutes at leaft have elapfed ; when, an olive precipi- tate by prufliate of potafh; # This fulphate is alfo precipitated when the fulphuric folution has been long expofed in an open veflfei to the air; and, according as this may be moift or dry, the effeft is produced fooner or later. therefore, ACCOUNT OF A MINERAL SUBSTANCE. 135 therefore, fome pruffiate of potafh was added immediately after the water, the colour of the liquor became olive green, and a copious precipitate, of a beautiful olive colour, was gradually depofited. Tinaure of galls, after a few minutes, caufed the liquor to orange by tinft. become turbid, and a very high orange-coloured precipitate ga ls> was obtained. A few drops of phofphoric acid were added to a part of the jelly by phof- concentrated fulphuric folution ; and, after about 12 hours, Pbonc acid» the whole became a white opaque fiiff jelly, which was info- luble in water. Potafh, foda, and ammonia, whether pure or in the ftate of ^te flakes by carbonates, feparate the fubftance in queftion from the ful- phuric folution, in the form of a white flocculent precipitate ; and, when thefe alkalis are added to a confiderable excefs, they do not rediffolve the precipitate, unlefs they are heated ; then, indeed, the fixed alkalis act upon it, and form combi- alkaline combi- nations which have already been mentioned, but which we nations, fhall foon have occafion more particularly to notice. E. 1. The white precipitate, when recently feparated from Muriatic folu- potafh, is foluble in boiling muriatic acid: and this folution tM?" of the. r .••■'. . white precip. may be considerably diluted with water, without any change being produced. 2. A part was evaporated to drynefs, and left a pale yellow Evap. left a yel- fubftance, which was not foluble in water, and was diffolved lowrefidue. with great difficulty, when it was again digefted with muriatic acid. 3. Pruffiate of potafh changed the colour of the muriatic olive precip. by folution to an olive-green ; the liquor then gradually became Prufflate» turbid, and an olive-coloured precipitate was obtained, fimilar to that which has been lately mentioned. But, 4. If fome nitric acid was previoufly added to the muriatic but none if ni- folution, then the pruffiate changed the liquor to a grafs-green, ]5JL?ld firft but did not produce any precipitate. 5. Tindure of galls, in a few minutes, formed an orange- Orange pr. by coloured precipitate, like that which has been mentioned j £ but, if the acid was in too great an excefs, it was neceffary to add a fmall quantity of lixivium of potafh or foda, before the precipitate could be obtained. -6. A 136 ACCOUNT OF A MINERAL SUBSTANCE. ^hof^cif" by 6' A fmal1 «luantity of Ph°rPhoric acid, being added to the muriatic folution, in a few hours formed a white flocculent precipitate. ar^d by alkalis. 7. potafti, foda, and ammonia, alfo produced white floc- pulent precipitates, which were not rediflblved by an excefs of the alkalis, unlefs the liquors were heated; and, in that cafe, part was diffolved by the fixed alkalis, but not by am- monia. Muriates of 8. The muriatic folution did not yield any precipitate, when hide, magnefia, tke muriates of lime, magnefia, and ftrohtian, were added ; andftrontian, . " • . ' .' * g^ve no precip. but muriate ot barytes formed a flight cloud. Zinc threw 9. When a piece of zinc was immerfed in the muriatic fo- down white lution, a white flocculent precipitate was obtained *. F. Acetous acid The acetous acid has not any apparent effect on the white thTw^Tteln^ PreciPitatei when lopS digefted with it. **;'" ' q. fixed alkalis The fixed alkalis readily combine with this fubftance, both, wtiiIiytcombin' in the dry and in the humid wa^- We have already feen, that the former method was em- ployed with fuccefs in the analyfis of the ore ; and the experi- ments made with the blow-pipe may be regarded as an addi- tional confirmation. In each of thefe cafes, the white preci- pitate combined with the alkali, as foon as the heat was fuffi- cient to caufe the latter to flow ; and, when a carbonate was employed, a portion of carbonic acid was expelled. The carbonic acid was in like manner difengaged? when the white precipitate was boiled with lixivium of carbonate of potafti, or of foda ; and the folutions thus prepared, refembled in every refpect thofp which were formed by diflblving in water the falts which had been produced in the dry way. It will be proper here to give a more particular account of thefe combinations. Humid folution J * Some of the white precipitate was digefted, during nearly in pota/h : a one hour, with boiling lixivium of pure or cauftic potafti : portion left, * This appears to indicate the obftinacy with which this fub- ftance retains a certain portion of oxigen; for we here fee that zinc does not precipitate it in the metallic flate, but only reduces it to an ;nfo}uble oxide. about ACCOUNT OF A MINERAL SUBSTANCE. 137 about one-fourth of the powder was diflblved ; and the re- mainder, which appeared little if at all altered, fubfided to the bottom of the vefTel. The clear folution, which contained a great excefs of alkali, affords a fcaly was decanted; and, by gentle evaporation, vielded a white ghttcnng falt > glittering fait, in fcales, very much refembling the concrete boracic acid, The fait was placed upon a filter, fo that the lixivium might permanent ia be feparated. It was then warned with a fmall quantity of the air> cold diftilled water; and, being dried, remained as above defcribed, although conftantly expofed to the open air. This fait had an acrid difagreeable flavour, and contained a acrid tafle : fo- fmall excefs of alkali. It did not diffolve very readily in cold luble in water '> water ; but, when diflblved, the folution was perfecl and per- manent. Some nitric acid was added to part of the folution, and im- precjpitable by mediately rendered it white and turbid. In a thort time, ami white precipitate was collected, fimilar to that which had been employed to neutralife the potalli : and the clear fuper- natant liquor, being evaporated, only afforded nitre. Pruffiate of potafh was added to another portion; but did Pruffiate of pot- not produce any effecl, until fome muriatic acid was dropped .. gave nfUory, Vol. IV.) and what we have related elfewhere (fee the third edition of Guthrie's Geography, in French, Vol. VI. page 225 agd 262, publifhed by Langlois at Paris), an. account has been, publifhed in the American papers in 180J, that Jylr. Wiljiam Peal, proprietor of the mufeum at Philadelphia, having, collected the bones found in the county of Orapge, in. the (late of New. York, had twelve feet high, fucceeded informing a flyeleton, the, height of which, is twelve }eVtSiThl\frfeet; the head keing f°ur feet a.nd a half -in. length, and the jong. tufks ten feet ; the other pajts being, in the feme proportion. Local fituation Almoft all thefe bpnes have been found in calcareous earth. of thefe enor- T}1C bones of the megalonix, or great claw, Qf which Mr. Jefferfon lias given a defcription, were found in caverns of lime ftone and chalk in Tennefee. The other enormous bones of the megatherium, found in fuch great quantities in the c(ov\nT ty of Ulfter, of which Sylvanus Miller, Efq. has given fome. detail SCIKNTIl'IC NEWS, 141 detail in* a letter to Profefibr Mitcbill, are found in ftrala of marl, which are dug to procure this calcareous ilibftance as a manure for land. It is, neverthelefs, fometimes remarked, TI>ey fometimes that thefe bones begin to fall in fmall portions when, after J^ to ^"^ having been from their calcareous inclofure, they are expofed to the atmofphere. Teeth, which were found and entire when extracted from the earth, become black in a fhort time, crack, itofe their enamel, and fall into fmall (cales. Without fuch a preservative we may prelume, with our friend Mitchill, that the remains of thefe animals would have been decompofed many centuries ago. SCIENTIFIC NEWS, &c. Prizes of the National Inflitute of France. JL HE clafs of mathematical and phyfical fciences having pro- Prize medal for pofed in the year 8, as the fubjea of a prize to be awarded at ^™et^rd^/"" the public fitting of the 15 Germinal, in the year 10, the fol- mentable bodiea lowing queflion : What are tfie charatters ivhich difiinguifh in ve- getable and animal matters, thofe wfuch ferve as ferments, from fuck other bodies as they put into ajiate of fermentation ? And the memoirs which have been received not anfwering the condi- tions of the program, the clafs propofes the fame fubjecl again for the year 12. The prize is of the value of one kilogramme (about one hundred and twenty-five pounds ilerling). It will be given at the public meeting of the 15 Germinal, in the year 12. Memoirs mufl be fent before the lfl Nivofe of the fame year. Afironomical Prize. — Citizen Lalande has prefented the Na- Agronomical, tional Inftitute of France with the fum of ten thoufand francs pnze" (about 400 guineas) to found an annual prize, to be given by the Inflitute to the author of fuch difcovery, obfervation, or work in aftronoiny, as fhall be thought the moft remarkable or ufeful, during the courfe of the year. The Inflitute very highly applauded this acl of generofity in one of its members, and de- creed, that thanks mould be configned in their regiflers, and commifTaries nominated by each of the three clafTes, to prefent at the next general meeting the means of execution. Communications to the Royal Society refpecling the Planet Ceres. > Dr. Herfchel fent an account of the appearance of the new Extreme fmall* planet, as viewed through his telefcopes. He had fought for "efs of the PIan€t it 142 SCIENTIFIC NEWS. it in vain, until he received Dr. Mafkelyne's determination of its place. When viewed with powers of 600 and 1200, it could not be decidedly diflinguifhed from a ftar, until it was found to change its place. Its apparent diameter was not large enough to be directly determined, but it was certainly not larger than one-fourth of that of the Georgian planet, and perhaps equal only to one-fixth., From a rough computation of its magnitude, Dr. Herfchel concludes that its real diameter is about J- of that of the moon : its light is of a reddifh hue. Mr. Gilpin alfo gave the Society an account of obfervations on the 8th and 12th of February. He found the planet's right afcenfion change from 188° 4-1' to 188° 30', while its declina- tion increafed. Mr. Gilpin obferves that its light refembles that of the planet Mars. Nebulous atmof- Thurfday, 25th February. A letter from Mr. Schroeter of Lilienthal, refpecting the planet Ceres Ferdinandia, informed the Society that Mr. Schroeter had obferved a nebulofity round the planet, fomewhat refembling that of a comet : the diameter of the true difc being 1.8", and that of the nebula 2.6", but the diftinction was not always equally obfervable. Mr. Schroeter confiders this body as of a hybrid nature, or a medium be- tween a planet and a comet ; but he imagines the apparent nebulofity to be owing to an atmofphere, and that, according to the different ftates of this atmofphere, the light reflected from the planet is either white, bluifli, or reddifh. A table of obfervations of the fame planet was alfo commu- nicated by Mr. Mechain, through Sir Henry Englefield.— XThis article is taken from the Journal of the Royal Injlitution.) Leonardo da Vinci, The lovers of the polite arts will be.pleafed to learn, a new tranflation of Leonardo da Vinci's treatife on painting (for which Pouflin made the figures) will foon be ready for publi- cation. This work has been long in the hands of Mr. Rigaud, R. A. who has paid it particular attention and care ; and has given new importance and energy to the work, by arranging the chapters iuccellively under proper heads ; by which the Itudent will be much facilitated in underflanding the precepts of this great matter in the art of painting. The reader will recoiled fome particulars of the extraordi- nary refearches and very fuperior genius of Da Vinci, by the ex- tracts given in the former feries of this Journal, from an abridge- ment of his writings, by J. B. Venturi, quarto, II. 84. Experi?nent9 SCIENTIFIC SEWS. 143 Experiments to prove that all Bodies, whatever may he tJieir Nature, are obedient to the Action of Magnetifm, and that this Aclion is fufficiently powerful to admit of being meafured. By Citizen Coulomb *. It has long ago been remarked, that platina, nickel, and feve- Magnetifm of ral other bodies, acquire a fenfible degree of magnetifm : but n!ckf'» &c. fup- r u-i r u \±\ .u- .i * J rPofed to be acci- iome philolophers attribute this property only to a portion of dental. iron not eafy to be feparated, and conclude, that by obtaining a greater degree of purity, we might fucceed in rendering them perfectly indifferent to the action of the magnetic bar. The new experiments which Citizen Coulomb has made All bodies are and repeated before the Inftitute, lead us on the contrary to magneticaJ. think, that the action of magnetifm extends through all nature ; for none of the bodies he has yet tried was found to refill this power. But however real this action may be, it is not alike in all bo- dies, and in mod of them it muft be neceffarily very fmall, to have efcaped the attention of philofophers to this time. In order^ therefore, to exhibit and to meafure thefe remits, we muft begin by placing the bodies in a fituation which fhall allow them to yield to the weakeft action. For this purpofe, Citizen Coulomb fafhioned his fubjects into Experiments the form of a cylinder or fmall bar, andin thisftate he fufpendedmadewitnbodfes them to a filken thread, fuch as is drawn from the filk worms* flngie gbre 0f cone, and in this ftate he placed them between the oppofite"Ik. poles of two magnetic bars of fteel. The fingle thread of (ilk could hardly bear the weight of a quarter of an ounce without breaking, confequently it became neceffary to form fmall bars very light and thin. Citizen Coulomb made them about feven or eight millemetres in length (or lefs than half an inch), with three quarters of a millemetre (or about an hundredth part of an inch) in thicknefs, and he gave the metals about one-third of this thicknefs. In his experiments he placed the fteel bars in the fame right All bodies af- line, their oppofite poles being five or fix millemetres farther ^"ned the direc- afunder than the length of the needle intended to ofcillate be- nets which were tween them. The refult of the experiment fhewed, that what- aPPlied» ever might be the fubftance of the needle, it always difpofed * Communicated to the French National Inftitute, and inferted in the Magazin Encyclopedique, No. 22, an 10, 4 . itfelf Subjedls of ex- periment. Extreme deli- cacy of the fuf- frenfion. 14-J SCIENTIFIC NEWS< itfelf according to the direction of the two bars; and that U they were turned from this direction, they always recovered it, after ofci Nations of which the number was often more than thirty per minute. It was therefore eafy in every cafe to determine, from the weight and figure of the needle, the force which had produced the ofcillation. Thefe experiments were fuccefTively made with fmall needled of gold, filver, copper, lead tin, fmall cylinders of glafs, a piece of chalk, a fragment of bone, and different kinds of wood. Citizen Coulomb has proved, in a former memoir; that the force of torfion of the filk thread is fo flight, that in order to draw it round through the entire circle, it would require a force fcarcely equal to the one hundred thousandth part of a grarrf (or about one feven hundredth of a grain). A quantity fo mi- nute cannot therefore fenfibly derange, the meafure of magnetic force in the different bodies, and its effe6t even, if it were ad- mitted to be of perceptible magnitude, may alfo be urged in proof of the general conclufi on of Citizen Coulomb, becaufe the magnetic power muft overcome this refiftance of the thread in order to manifeft itfelf. Our author gives, in the third vol. of the Memoirs of Natural Philosophy and Mathematics of the National Inftitute, a very fimple formula to determine the! magnetic force Of a body from the time of its ofcilations, and he means to fhew in another memoir, the method of determine ing this refult in different bodies of the fame figure placed be- tween the poles of two bars. He thinks it now proved, that: all the elements which enter into the compofition of our globe, are fubje&ed to the magnetic power, and that the whole mafs collectively forms one tingle magnet, ©bfervations. In favour of thofe who might be defirous of repeating his experiments, and rendering them very fenfible, the author re~ marks, that the method of fucceeding confifts in diminifhing the fize of the ofcilating bodies. From fome effays, of which the refults terminate this memoir, it feems to follow, that tne accelerating forces are inverfely as the maffes are very nearly in the direel proportion of the furfaces ; but Citizen Coulomb gives this rule only as a firfl deduction, which requires to btf confirmed. ERRATA. In Mr. Cruickfhank's paper, p. 43, end of the firft paragraph, for faults xtidfaSii j and p. 46, 1. 26, fcr computed read compiled. URNAL OF NATURAL PHILOSOPHY, CHEMISTRY, AND THE ARTS. JULY, 1802. ARTICLE I. Compojltion of Writing Ink, pojjejfing the permanent Colour, and other ejfential Properties, of the Ink ufed for Printing. In Letter from Mr. William Close. To Mr. NICHOLSON. S I R, Dalton, May 25, 1802. IN thefecond volume of the Philofophical Journal, at p. 63, Preliminary ad. the preparation of indelible ink is announced. Such an article may juftly be confidered a defideratum. As I have for fome time directed my attention to the composition of permanent ink, I fend you a (hort memoir on the fubject, which was drawn up previous to the perufal of the above-mentioned notice, and intended for a future communication. THE welfare of individuals often depends very much on Permanent ink the teftimony of writing. An atramentous compofition, pof-a.n,im,port^ntar" fefling a permanent colour on paper, and fuch a degree of fervation A au- infolubility, after deficcation, as not to fuffer any injury from the.ntic #eftimo- expofure to humidity, or the application of fuch chemical pre- VolII.— July, 1802. L partitions 146 COMPOSITION OF DURABLE INK. partitions as totally eradicate the traces of common ink, would certainly be ati article of confiderable value in the material compoiition of thofe writings, or legal inftruments, which are intended to evince the traniadions of the day, and to ratify the affairs of the future. •The Invention The ancients were probably more interefted in thecompofi- bjbfy'produced"^011 °^ permanently coloured ink than the moderns. When fome rcmiflhefs every book was in manufcript, it would frequently be requi- site tfink*' fiLe to tranf"cribe whole volumes, fometimes merely for the pur- pofe of procuring a copy, at other times for the preservation of the work itfelf j in either cafe, before the writer begun a procefs fo tedious, it would be of confequence to felect fuch materials as were the moll durable, in order to protract the like neceffity, and alfo for the purpofe of enhancing the value of his labour. But fince the invention of printing, the neceffity of tranferibing has been entirely fuperfeded ; the manufcripts of modern authors after publication, have been reduced to little more value than objects of curiofity ; and writers have been contented with fuch materials as are the cheapefl and eafieft to procure. Ink with vege- F°r a great number of years, the ink moft generally ufed by table infufions European writers has been the infuiion of galls, and other i"ron " P ™ ' atlringent vegetables containing gallic acid, rendered black by fulphate of iron, and thickened by the addition of a little gum or fugar. This compoiition is well adapted to the common not durable. purpofes of writing and the difpatch of buiinefs, but its colour is liable to fade: a composition of a more permanent colour is therefore defirable, for writings which are required to retain The colour may their primitive fignatures, and fuch as cannot be printed. In- bereftored while dcec^ fmce the difcovery of the method of totally difcharging iron remain* on ^ne traces of common ink "by the application of the oxigenated the paper. muriatic acid, more ferious confequences are to be apprehend- Themoftferioused f h u ;verfal f f- the common atramentous fluid, objection to its * ufe is, that it than the decay of its colour from age; for it is well known, ?fibVjtal,y that while the fulphate of iron remains on the paper, the co- lour of the writing may bereftored, by warning the manufcript withfrefh infufion of galls. Means of pre- In the quarto feries of the Philofophical Journal (Vol. IV. venting this by p 47$), there are feveral ufeful receipts for compofing ink pigments. capable of refitting the oxigenated muriatic acid. The moft material difference, however, of the compofitions there re- 2 commended COMPOSITION OF DURABLE INK. 147 commended from thofe in common ufe, confiib in the addi- tion of pigments producing an unchangeable colour upon paper. Ink of a permanent colour may be eafily obtained, by fuf- Ancient method ... . . J _ ., , , . , ofcompofirhj pending various pigments in an aqueous fluid, by the interven- ]njc> tion of gum, without the affiftance of the common ingredients; but fuch compofitions are liable to one of the greatefi inconve- niences, for the whole of the writing may be detached from the paper by wafhing the manufcript with water. Such ink, how- ever, was frequently ufed by the ancients. As a permanent colour is certainly a valuable requifite, it Speculation for appears very promifing in fpeculation for the improvement of mlntofti\\i this indiljpenfible article, according to the limpleft, and per- kind of ink. haps the moft ancient method of com pofi tion, to fubftitute, in place of the common mucilaginous fluid, as a compound vehicle for the diftribution and protection of the colouring matter, the folution of foine gum, or refinous fubftance, which can be dif- folved in only a few liquids. After the diffipation of the thin- ner part of an atramentous compound properly formed with fuch a folution> the colouring fubflance will be left on the pa- per, combined with a fufficient quantity of tenacious matter to protect it from being injured by friction, or from being dis- charged by the application of any fluid to which the writing may be expofed, without injuring the paper. Many of the more volatile kinds of oils may be ufed in writ- Ink with oil ami ing, if reduced to a proper confidence by the addition of gum refi:l• or refin. Tolerable ink may be made by diflblving .30 grains of common refin in 90 grains of oil of turpentine, and temper- ing the folution with 17| grains of lamp black, and 2| of in- digo. In a dry ftate, this composition refifts the action oflnconven nencc water, but not of fpirit. Such, indeed, will be the cafe with t0 "5* ever^, . . . , compofition will every compofition in which the colour is merely fufpended in be fubjedl where the fluid, and attached to the paper, by a fubftance of eafy fo-'!16 c.0,0"rlsT£~ -,,.,- , .. . - , . , , . , , , , chanically fuf- iubility ; the application of the article which produced the flu-pended. idity of the ink, will again penetrate and foften the dry com- pound. Thofe compofitions which contain a tenacious matter, foluble in a few articles only, and at an high temperature, will be the leaft exceptionable. A more infoluble kind of matter than refin fhould be ufed. Copal is much Copal will diffolve in only a i'ew liquids,- it appears well fuPerior to refm adapted to the purpofe of retaining a permanent colour upon fonofthe^ L 2 (he ment 5 148 COMPOSITION OF DURABLE INK. the paper, if a vehicle can be found which will diflblve a fuffi- cient quantity, and which, when the colouring matter is alfo added, {hall be fluent enough in writing. but is not alto- Oil of lavender will diflblve copal. I have made fome ex- gcther free from . . . . r . , J , , . . r . inconvenience. pe"ments with thele articles, and the combination lucceeds fo well, that I have not been inclined to ufe any other. The only inconvenience to be apprehended from the ufe of copal in the composition of ink, is, from its being foluble at a low temperature ; but whether any other kind of tenacious matter of more difficult folubility, can be ufed conveniently in writing, I muft leave to future difcuflion. The folution of a fubflance which could only be diflblved in an high temperature, would certainly be the mod proper vehicle to prevent alteration ; for, after the deliccation of the writing, it would be difficult to foften the ink in one part of a manufcript, without expoling the whole to a very injurious procefs. Compofition of Ink may be compofed of oil of lavender, copal, and lamp lavender copal D^ac^* according to the following proportions of the ingre- and lamp black, dients : Take of oil of lavender, 200 grs. copal in powder, 25 grs. lamp black from 2\ to 3 grs. With the afliftance of a gentle heat, diflblve the copal in the oil of lavender in a fmall glafs phial, and then mix the lamp black with the folution upon a marble flab, or other fmooth furface. Put the compofition into the bottle, and keep it excluded from the air. After a repofe of fome hours, the ink muft be well fliaken and ftirred with a piece of wire before it is ufed ; if it be too thick, it muft be diluted with a little oil of lavender, oil of turpentine, or alcohol. The facility of writing with this compofition de- pends much on the quantity of the colouring matter. Three grains of lamp black to two-hundred and twenty-five of the folution of copal, producing ink of a full body of colour, and is nearly as much as the copal can protect from injury after the diflipation of the oil of lavender. Two grains and an half of lamp black, and half a grain of indigo, produces ink of a paler colour, but which may be diftributed upon the paper with the facility of common ink. A piece of fponge *, or other or- ganized * The cuftom of putting cotton in an inkftand has been difufed, more particularly, I think, fince an inkftand, invented by the late worthy and ingenious Samuel More, of the Society of Arts, was 4 made COMPOSITION OF DURABLE INK. 149 ganized fubftance, muft be ufed in the inkftand, chiefly for the purpofe of cleaning the pen. Red ink may be made by tempering the folution of coPal?Jd,j"£tWpfhred with red fulphuret of mercury inftead of lamp black. Themercuri# following proportions of the ingredients produce a red ink which writes very well : Take of oil of lavender 120 grs. copal in powder, 17 grs. The recipe. red fulphuret of mercury, 60 grs. Diflblve the copal in the oil of lavender, and then mix the fulphuret with the folution upon a fmooth furface. Both thefe compofitions poflefs a permanent colour, and A manufcript i ^ • . . /.,.iri- •,• t>l '-1 written with other eflential properties of the ink uled in printing. 1 he oil thefe compofi- of lavender being diflipated with a gentle heat, the colour is tions will not be left on the paper furrounded with copal, a fubftance infoluble j^SSa of * * in water, in fpirits, in acids, or alkaline folutions. A manu- bleaching, fcript, written with thefe compofitions, may therefore be ex- pofed to the procefs commonly ufed for reftoring the colour of printed books, without the fmalleft injury to the writing; and in this manner all interpolations with common ink may be re- moved. As made and brought into faftiion about thirty years ago, by the cele- brated Wedgwood. Thefe changes appear to be both injurious. For the ink in the cotton is kept blacker by the fufpenfion of the atramentous part ; and if no more ink be prefent than perfectly to fill the cotton, the pen will always receive a fluid black ink, and may be charged at pleafure by a greater or lefs gentle preffure at the time of taking up, or difcharged by lodging the point for a moment upon the cotton. It is alio very eafy to regulate the oxigenation by the air, fo as to increafe the blacknefs without fuffering mouldinefs to come on, by the fimple expedient of turning the cotton upfide down every day. As the fibres of the cotton prevent the fluid from circulating as ufual by the change of temperature produced from evaporation, the interior mafs may be conlidered as in a clofed veffel while not in ufe. Mr. More's fountain inkftand, at prefent fo univerfally in ufe, is certainly very inconvenient. The ink, it is true, is kept in a clofed veffel \ but its colouring matter is at full liberty to fublide, and the confumer is obliged to fill his pen from the muddy bottom inftead of the furface j and what is ftill worfe, the conical veflel into which the ink flows, is fubject to all the evils of evaporation and mouldi- nefs, fo as moft frequently to afford an adhefive and clogging fluid to the pen. W. N. 150 ON THE VEGETATION OF PLANTS. Source of apprc- As copal is foluble in feveral of the efTential oils, it may be henhon. 'l he expefteci that the application of thefe will do much injury to the will (often the writing. Such an expectation is well founded. If the writing drv comp ifiuon, be rubbed with a fmooth furface dipped in oil of lavender, cannot be eafily much of the colouring matter will be difengaged, and diftri- eradicated. buted more difFufely upon the paper ; but, as fome of it will have penetrated the interior parts of the paper along with the copal, it will be extremely difficult to obliterate the traces of the pen without the erafement being perceptible. This is the principal fource of apprehenfion, but I know of no method of Amber a proper obviating the danger. The perufal of a memoir on the nature co^bTufed' and PreParation of drying oils> &c- by Mr- Sheldrake (Philof- Journal, 8vo. Vol. I. p. 259), fuggefts amber as a proper ar- ticle for the compofition of ink, if enough of it can be diflblved in any fluid fufficiently thin for the purpofe of writing. The more difficulty there is in effecting thefblution of any tenacious fubftance we ufe, the better, provided it can then be employed without inconvenience. I am, Sir, Yours refpeclfully, WILLIAM CLOSE. II. Experiments and Ohfervations on the Vegetation of Plants, wkich Jhevo that the common Opinion of the Amelioration, of the Au f/iofphere, by Vegetation in Solar Light, is ill founded. By James Wo odhouse, M. D. ProfeJJbr of Chemijlry 'in the (Iniverfity of Pennfylvania, fyc. To Mr. NICHOLSON. SIR, Pater N'ojier Row, May 27, 1802. Introductory J INCLOSE for the Philofophical Journal, the refults of va- rious experiments, made in Philadelphia in the year 1801, up- on the feeds, leaves, &c. of a variety of plants, which feem to prove, that growing vegetables, contrary to an opinion almoft univerfally adopted, do not purify atmofpherical air; and that, whenever letter. ON THE VEGETATION OF PLANTS. 151 whenever they appear to afford oxigenousgas, it is by devour- ing the coal of carbonic acid gas for food, and leaving its ox- igen in the form of pure air. I have the honour to be, Dear Sir, With the greateft refpect, Your mod obedient, And very humble fcrvant, JAMES WOODHOUSE. Firft. Of the Effetls produced by the Germination of Seeds in atmofpherical Air. On the 3d of June, twelve feeds of zea maiz were planted Germination of in earth, and confined over water in a glaft veflel, in feventy ^ds.ln ?tm°- ounce meafures of atmofpherical air of the purity of 100, and often expofed to the light of the fun. On the 1 2th, the corn had vegetated, and was from two to five inches high. The air being examined at this time, by throwing up one meafure of it, over lime water, in an eudiometer, gave -j^ parts of car- bonic acid air. Another meafure, after being freed from the fixed air, and mixed with an equal meafure of nitrous air, pro- duced an abforption of T3-0^~. On the 19th, the corn having grown confiderably, and the air being tried again, no carbonic acid gas appeared, and the purity was the fame as at firft. On the 23d, the plants died, and the airs were found to confift of y-l-g fixed, and T^ azotic gas. Similar experiments were made with the feeds of apium pe- trofelinum, Iacluca fativa, cucurbita citrullus, phafeolus fativus, fifymbrium, and raphanus fativus, and with the fame refult. The atmofpherical air, in thefe experiments, appears to be The air loft oxi- reducedin purity, by its oxigen uniting to the coal of the coty- gen bjJ unitlng ledons of the feed, or to that of fome animal or vegetable mat- wards it became ter contained in the earth in which the feeds are planted, or to morepurej ani that of fome decayed portion of the living leaves. was tota]jy ab_ Ingenhouz, Humbold, and Thomibn, have obferved, that for bed. foils have the property of abforbing oxigen; but as it cannot mould on tje proved that any pure earth, or mixture of earths, render at- air moft probably mofpherical air impure, it is certainly more philofophical to trom lts cai ou* afcribe the impuriLy of the air to the formation of the carbonic acid, the bafe of which generally exifts in all foils, II. Of 152 ON THE VEGETATION OF PLANTS. II. Of the Effecls produced by the Growth of Plants in atmofphe- rical Air. Growth of plants On the 27 th of May, twelve plants ofperficafia polygonum, inatraof. air. . . , ,., *\ . *".. F <: i • i / two inches high, growing in earth, were confined in a glals veflel in fifty-two ounce mcafures of atmofpherical air, of the purity of 100, and often expofed to the influence of folar light. On the 4th of June, they had increafed about two inches in height. The air being examined at this time, was found to contain j^jj parts of carbonic acid gas, and to be reduced in purity to 80. Several young plants of rhaphanus fativus, la- tura ftramonium, phytolacca decandra, zea maiz, phafeolus jativus, fidum telephium, amaranthus hyboidus, cucurbita ci- trullus, firymbrium, and lactuca fativa, were alfo feparately confined in from forty to eighty ounce meafures of atmofpheri- cal air, which was examined at various times, from one hour They produced to thirty days, after the plants had been placed in it. Carbo- carbon:c acid njc acjcj was preneraIly formed, and whenever this circum- gas, and dirni- " b . r ' . ,- • •„ i nifhed the purity fiance happened, the purity of the air was dimimflied. of the air. Many of the fame kind of vegetables were alfo confined in in^xigendimi- f°rtv ounce meafures of oxigenous gas, which had been well nifhiti purity by warned in lime water, and the purity of the air was very gene- car omc aci . rajj^ ]eflr-enec^ ^xe(j ajr being generated. They turned of a white or yellow colour, and foon died, after being placed in at- mofpherical air. In confined The fame effects are produced by the growth of plants as by plants the de- tne germination of feeds in common air, and by the fame caufes. ford carbon and If the leaves are confined a confiderable time, part of them de- form acid, which cay, and the coal of the dead portion, uniting with the oxigen Lcompofes!/11 °f the atmofpheric air, generates carbonic acid. This acid is decompofed by the living leaf. Its coal is abftra&ed, while its oxigen is left in the form of pure air. But when the When the oxigen unites to the coal of the animal or vegc- formation is tab]e matter of the foil in which the plants vegetate, or to the cjuiclcer than the „ r to . decompofiti on, coal of the decayed parts of the leaves, and makes fixed air the plant dies, quicker than the living parts can decompofe it, the plants will fpeedily die. When the foil When a plant in ] crfecl health, growing in a foil which con- contains but tains tittle vegetable or animal matter, is confined in atmOfphe- izcVi^rnainT" r'ca^ a'r* '*■ W*W nve a l°ng time, without producing any change the included in it. Many of the vegetables which were the fubje&s of thefe Plan!7,ilivc experiments, much longer. r ON THE VEGETATION OF PLANTS. 153 experiments, did not affecl the air in five days : fome diminifh- ed its purity in three hours; and others altered it in a mod flow and gradual manner, caufing little change in it in twenty days. III. Of the E feels produced by the Leaves of Plants in atmofphe- Leaves expofed rical Air impregnated xvith Carbonic Acid Gas, and expofed to ^xtmz^i at> * the Light of the Sun. mofphericand carbonic acid gas. A handfull of the leaves of mimofa virgata, euphorbia picla, digitalis purpurea, franklinia altamaha, afparagus officinalis, coryllus avellana, rhus glabrum, ariftotochia fiphoe, and peri- ploca graeca, were feparately expofed feven hours to the light of the fun, in thirty-fix ounce meafures of atmofpheric air, im- pregnated with four ounce meafures of carbonic acid gas, from the carbonate of lime and fulphuric acid. The fixed air difap- The carbonic peared, and the atmofpheric air was fo much increafed in purity, *™d ^^"0*-' as to devour two meafures of nitrous air. tion of oxigen in The leaves of thefe plants, kept over night in the fame air, ^ ™*^e was gave carbonic acid gas in the morning ; and its purity, in every in the dark the inftance, was confiderably diminifhed. leav<* produced _, , ■'- . - _ f , . . . _ carbonic acid The leaves of mimola virgata and amygdalus perfica, were gas, alfo feparately expofed nine hours to the influence of folar Other leaves ex- light, in forty ounce meafures of atmofpherical air, in which ^ith th0e ffrm'er fixed air had been formed by leaving a fungus to putrefy it. refult. The carbonic acid gas disappeared, and the purity of the at- mofpherical air was increafed from SO to 80. IV. The following Tables ivillfheto the Quantity and Purity o^Table of experi- oxigenous Gas, obtained by expofing a fmall Handful of themtntson leaves Leaves of Plants to the Light of the Sun, in forty Ounce Mea- ^j. umier fares of Pump Water. pump water. This water was taken from a well funk within a few yards of a neceflkry, from which it was impregnated with carbonic acid gas, as appeared from an analyfis. The leaves were feparately expofed in glafTes arranged near each other, and from eight to thirteen comparative experiments were made at one time. Leaves 154- ON THE VEGETATION1 OF PLANTS. Leaves of 0 Si? B * If ■c ° ? u fi- lls s z 0 * •s % A | ! - c a P h .-. c AS Time when expofed. Alcea rofea « 19} 122 146 96 July 2, 1802. Zea maiz - 16 116 140 51- The day was very clear. Amaranthus fpinofa 15 120 140 68 'a Melifla officinalis - Hyfopus 2 Oh C 13 16 120 120 130 138 50 70 c a Convolvulus purpureus - 8 110 110 0 o o Malva rotundifolia - 0 Li 17 120 140 86 c Lavendula - 16 118 130 55 O . Rofa centifolia 15 112 130 46 Mirabilis dichtoma - 16 110 130 4-0 Convolvulus purpureis - 13 110 120 10 July 3. Anthemis nobilis - 12 111 120 32 Day clear. Hibifcus Syriacus - — - 12 118 130 6b 9* Polygonum aviculare 5 0 18 114 130 50 O Amygdalus Perfica 00 E 10 i li- 112 12 5 o Pyrus malus - ? 16 ne 120 20 Platanus occidentalis 12 120 140 20 Tilia Americana - 10 120 138 t-0 -; Leaves ON THE VEGETATION OF PLANTS. 155 Leaves of § ■c < i a 35 2 ~ .fit*, ^- c 1 12 2 I Time when expofed. cJ.E 14 120 25 1 E Siriodcndron tulipilia July 4, 1801. Populus dilatata 11 no 132 60 iE (cuius pavia 13 no 1*0 60 Day generally clear. Apium petroCelmum 12 115 132 55 2 Convolvulus purpureus - :> 120 120 30- Helianthus annuus - ad M 112 132 62^ ? Ruta graveolens 10 120 130 io ; Trifolium paluitri - 13 120 140 55$ 1 } Datura firammonium 14 112 130 80 - Hyfopus - 7 12 112 112 132 130 65 Blattari verbafcum - 45 July 5. Chelidonium majus - IS 112 136 80 Day clear and cloudy. Chryfanthimumlndicum - 1 I 120 142 63 Twelve ounce mea- Acer glaucum 1 ! 120 139 63 fures of this oxigenous Phytolacca decandra 11 120 140 80 air, after being wafhed Antirrhinum linaria- OS IS 120 140 65 o * in lime water, to free it Arclum cappa £ 12 120 140 53 c J from the carbonic acid Syringa vulgaris X s 120 132 40 gas', being expofed to a Helianthus altiffimus 12 120 140 55 mixture of iron filings and Polygonum Perficana 12 120 140 80 fulphur, were found to Cercis Canadenfis - 12 120 140 60 confift of eight ounce Sonicera capri folium 12 120 140 60 meafures of oxigenous, 10 120 120 30 and four of azotic gas. Diofpyros Virginiana July 6. Franklinia altamaha 1!) 120 102 0 Chionanthus Virginica - B 120 100 0 Day clear and cloudy. Arundo gigantia 10 120 130 32 Afclepias Syriaca - 9 120 80 0< / Thefe leaves were ga- Annona triloba 6 10 120 130 4o;' « thered in the evening, Magnolia glauca - 10 110 102 oj ~ and kept until morning, tripetala - 0 If; 116 13C 40i ^ in a cool place. Xanthoriza tin&oria QO 8 120 13C (501 o Conferva civularis - 10 120 12C )30 CTi Alcearofea - 5 11C 7C ) 0 Sophora indica 7 lie 8( ) 0 I Laurus faflafras It 12C ) 92j 0 1 We |^5 ON THE VEGETATION OF PLANTS. Opinion that We are indebted to Dr. Prieftley for the difcovery, that FgeiTtod-ie at-X" P^ants expofed to light yield oxigenous air; and ever fince it mofphcrc, has been made, an opinion has been adopted, that growing vegetables fupply the oxigenous portion of atmofpherical air, of which there is a conftant confumption, by combuftion, fer- mentation, refpiration, and the calcination of metals. ill founded; If this fubjectis attentively examined, it will be found that plants have no effect in rendering the air of the atmofpherc pure", becaufe they af- Firfi. Whenever oxigenous gas has been obtained from ve* ford none unlefs getayes carbonic acid gas has been prefent. carbonic acid be G _. ' . n1 r & i r i • •• i • , prefent. Expe- Dr. Pneitley expoted plants to atmofpheric air, in which riments of fpirit of wine and wTax and tallow candles had burned out ; to proof; a^r which had been vitiated by the death or putrefaction of mice and fifhes, and to air which had been frequently taken into his lungs. He alfo obferved, that there was a flower and lefs pro- duction of air from rain and diftilled, than from pump and ftag- nant water, and of the au- ^he difference between the quantity and quality of the gas, thor; tabulated, obtained from river water and the fame water impregnated with carbonic acid, by expofing plants in it to the influence of folar light, will be feen by the following table : Leaves ON THE VEGETATION OF PLANTS, 157 Leaves of f 4 j 3 0 So 3 • | 21 F 1^ Time When expofed. If ;;•: II. fa fj •g | f! u £.%< 4 s <] •1 :i 88 E Siriodendron tulipifera T> 55 July 7, 1801. Cercis Canadenfis - 70 Tilia Americana Q 50 Day very clear. Salix Babylonica - u 32 Polygonum Perficaria 5 30 The leaves were ex- Phytolacca decandra 4) ~ 94 pofed in the water of Platanus occidentalis 3 2 90 O the river Schuyltril. Alcea rofea - 2 & 84 — Helianthus annuus - fi 83 Amygdalus Peril ca - et 82 Conferva fontinalis - il 80 Zea maiz - • JS 15 Acer glaucum g 5 u. 90 Seriodendra tulipifiera B 6 120 130 40 JulyS, 1801. Cercis Canadenfis - •. 3 6 116 124 30 Day a little hazy, al- Tilia Americana S a 5 110 160 0 though the fun ihone Salix Babylonica - Polygonum Perficaria O PL, 5 10 120 120 100 140 0 70 conftantly. The leaves of the Phytolacca decandra § s 6 120 140 42 . fame plants, in the Platanus occidentalis > *i 3 110 60 Q o O fame river water, im- Alcea rofea - - g s 6 120 132 40 — pregnated with four Helianthus annuus - SI 10 120 110 50 quarts of the water, faturated with carbo- Amygdalus Perfica- o 6 120 138 10 Conferva fontinalis - a b 5 o 4 120 134 50 nic acid gas, from car- Zea maiz - 4- 115 125 20 bonate of lime and the Acer glaucum 6 120 140 ,0 fulphuric acid. It appears from this table, that the leaves of thirteen differ- ent plants, feparately expofed in forty ounce meafures of the water of the river Schuyltrill, produced about ten drachm meafures of air, the principal part of which was azotic gas ; whereas the fame kind of leaves, expofed in the fame quan- tity of the fame water, impregnated with carbonic acid, yielded feventy-feven drachm meafures of oxigenous air, of* a very high degree of purity. Count Remarks on Prieftlcy's and Count Rumr'oriTs ex- periments. ]58 ON THE VEGETATION OF PLANTS. Count Rum- Count Rumford made an attempt, in the year 1787, td ments to Wain overthrow the doctrine of the purification of the air by plants, oxigeo from wa- His arguments were, that leaves confined in water were in ter y olarhg t. unnaturai circumftances, and that pure air could be obtained from other bodies, as fine (pun glafs, raw filk, common cot- ton, and that of the poplar tree, expofed in water to the light of the fun*. | The ingenious author of Phytologia alfo fays, it may be fuf- peded that, in many of the experiments of Prieftley and In- genhouz, the production of vital air might be (imply owing td the action of the fun's light on the water in which the vege- tables were immerfed, like that from the filk in the experiments of Count Rumford; and that the fine points or (harp edges of thefe bodies, contributed only to facilitate the liberation of it when expofed to the fun fhine, which thus dilbxigenated the water by their united effect. The experiments of Count Rumford are far from being fatisfactory. Thirty grains of raw filk, at the end of three days, yielded him but 3J cubic inches of air, and fometimes four days elapfed before a fufficient quantity could be collected for an experiment. Dirrft experi- In order to find how much air could be obtained from the xncnts a £ne points or ftarp edges" of certain bodies acting upon water, the following fubftances were expofed one day to the action of folar light, in forty ounce meafures of pump water. with fibrous bo- Filaments of afbeftos, baked horfe-hair, common cotton, and dies, which gave ^ ^ p t|ie afcjep|as Syriaca, the flower panicles of rhus cotinus, air lefs in quan- * J . r . tity and purity the fine hairy plumes of chmatis crifpa, the ipikes of panicum than leaves. glaucum, and charcoal in powder. From each of thefe fub- ftances, from two to four drachm meafures of pure air were obtained, which devoured nearly two meafures of nitrous air 5 confequently it was lefs pure than that procured from leaves expofed in the fame water. There was alfo a much fmaller quantity of it; for from eight to nineteen drachm meafures may be obtained in a few hours, by immerfing. the leaves of any plant in the fame water, and expeiing theci to folar light. Other fourcss of Some water, without any mixture, will yield ovigenous gas air- by the combined action of light and heat; and many fubftances placed in water, appear to act merely by railing its temper- ature. * Tranfaflions cf the Royal Society for 1787. The b ON THE VEGETATION OF PLANTS. 159 The green vegetable matter, which forms on all bodies, im* mcrfed a confiderable time in water, might alfo have been one of the fources of pure air, in fome of the experiments of Count Rum ford. Secondly. Many philofophers fuppofe, that vegetables yield Plants donotde- oxigenous gas by the decompofition of water. Its hidrogen f°™Ph°ey d*a*"t' is faid to enter into plants, while its oxigen is fet at liberty in operate in pure the form of pure air. water. If this opinion was true, oxigenous gas fhould be obtained y expofing leaves in boiled, rain, diitilled, river, or lime water, but this cannot be done. Thirdly. Some fuppofe that vegetables give oxigenous air to Plants do not animals, and that the latter yield them azotic gas in return, ^ h0afgd^c^-t which they devour for food. oxigen and ab- If this hypothecs were juft, atmofpheric air would be in- forb azote > creafed in purity by confining leaves in it when it contained no fixed air; and its purity might alfo be increafed, after be- ing previoufly diminished, by an additional quantity of azotic air, in the fame manner. A handful of the leaves of euphorbia pida, nicotiana tobacco, for fefli leaves t>uxus vulgaris, cinna glauca, mimofa julibrefcens, jaxus pro* do "°* a?e P™" •o i ii r • duced no cftett. pitta and coryllus avellana were feparately confined in forty ounce meafures of this air, and expofed to the influence of a bright folar light rive hours. No carbonic acid gas was gener- ated, and the purity of the air was exactly the fame as when firft tried. No decayed portion could be obferved upon thefe leaves. As it is acknowledged that the leaves, items, and roots of Leaves do not plants, feparate the oxigen from carbonic acid, it may be faid, ?m?l the,at- , , , . r r , \ mofphere by de- that the oxigenous portion of atmolphenc air is fupplied by the compofing its decompofition of this gas, as it is always found in the atmo- carbon)C Sas> fphere, and often in water in which vegetables grow. quantity of this The quantity of carbonic acid gas in atmofpheric air, is gas is verv mi- reckoned to be about one part in an hundred. It mult, how- nU e' ever, vary in different places. We would expect to find the moft of it in cities, where it is formed by combuftion, refpira- tion, fermentation, and putrefaction. If one meafure of the air of any large city is thrown up over lime water in an eudio- meter, no milky appearance will be produced, fo that the quan- tity of carbonic acid in this air muit be extremely fmall. As this gas is alfo feized upon by alkalis, earths, and metals, and abforbed by water, the quantity floating in the atmofphere may be lefs than one part in ten thoufand. When we confider likewife, that the oxigen is never fepa- and plants dete- rated from the carbonic acid by leaves, but when they are ex- «orate *• a'ir pofed, in contaa with it, to the light of the fun ; and that every mUCh m°re# perforation made in a living leaf, however minute, by an in- fect, caufes the part to decay, and abforb oxigen by day and by night ; and that, in the autumn in fome countries, all leaves fall on the ground, ferment or putrify, and thus diminifh the purity of common air ; and that the petals and fruit of vege- tables have the fame effect, we muft pronounce, that the oxi- genous portion of atmofpheric air cannot be fupplied by vege- tation. Vol.11 — July, 1802. M Dr. 162 THEORY OF LIGHT AND COLOURS. Air bladders of Dr. Darwin fuppofes, that the air in the air bladders of vc- contaia ai^worfe £etables (erve to oxigenate the feed. Tlie air of the air blad- than that of the ders of cardiofpermum halicacabum, ftaphylia trifoliata, coin- atnco p ere. tea arDOrefcens> ancj fophora auftralis being examined, was found to be a little worfe than the air of the atmolphere. III. On the Theory of Light and Colours, ify Thomas Young, M. D. F. R. S. Profeffor of Natural Phihfophy in the Royal Infiitution. (Concluded from page 90.^ PROPOSITION IV. Prop. IV. Tar- When an Undulation arrives at a Surface which is the Limit of undubUong°at0 Mediums of different Denjities, a partial Reflection takes place, the confine of proportionate in Force to the Difference of the Denjities. mediums differ- JL HIS may be illuflrated, if not demonflrated, by the ana- logy of elaftic bodies of different fizes. " If a fmaller elaftic body ftrikes againft a larger one, it is well known that the fmaller is reflected more or lefs powerfully, according to the difference of their magnitudes : thus, there is always a re- flection when the rays of light pafs from a rarer to a denfer ftratum of ether ; and frequently an echo when a found ftrikes againft a cloud. A greater body ftriking a fmaller one, pro- pels it, without lofing all its motion : thus, the particles of a denfer ftratum of ether, do not impart the whole of their mo- tion to a rarer, but, in their effort to proceed, they are re- called by the attraction of the refracting fubflance with equal force ; and thus a reflection is always fecondarily produced, when the rays of light pafs from a denfer to a rarer ftratum." (Phil. Tranf. for 1800, p. 127.) But it is not abfolutely ne- ceffary to fuppofe an attraction in the latter cafe, fince the effort to proceed would be propagated backwards without it, and the undulation would be reverfed, a rarefaction returning in place of a condenfation ; and this will perhaps be found moft confident with the phenomena, PROPOSl- THEORY OF LIGHT AND COLOURS. 1§3 PROPOSITION V. When an Undulation is tranfmitted through a Surface terminating Prop. V. Law different Medium*, it proceeds in fuch a Dire&Mb that the Sines fn^?^n of of tlie Angles of Incidence and Refraclion are in the conjlant tranfmitted Ratio of the Velocity of Propagation in the two Mediums. coXVfdif- (Barrovv, Left. Opt. II. p. 4. Huygens, delaLum. cap. 3. ferent mediums. Euler, Conj. Phyf Phil. Tranf. for 1800, p. 123. Young's Syllabus. Art. 382.) Corollary 1 . The fame demonftrations prove the equality of the angles of reflection and incidence. Corollary 2. It appears from experiments on the refraction of condenfed air, that the ratio of the difference of the fines varies (imply as the denfity. Hence it follows, by Schol. I» Prop. I. that the excefs of the denfity of the ethereal medium is in the duplicate ratio of the denfity of the air; each particle co-operating with its neighbours in attracting a greater portion of it. PROPOSITION VI. When an Undulation falh on the Surface of a rarer Medium^ fo Prop. VI. Total obliquely that it cannot he regularly refracted, it is totally re-^e?e^lon/.of.un" /, . , , , I . . r • t ,™ -, diction falling fiected, at an Angle equal to tliat oj its Incidence,, (Phil, obliquely on the Tranf. for 1800, p. 128.) furface of a rarer medium. Corollary. This phenomenon tends to prove the gradual increafe and diminution of denfity at the furface terminating two mediums, as fuppofed in hypothefis IV; although Huy- gens has attempted to explain it fomewhat differently. PROPOSITION VII. If equidiftant Undulations be fuppofed to pap through a Medium, Prop. VI. Un- of which the Parts are fufceptible of permanent Vibrations Come- dulat,ons are re* i n i 7 r r j 7 • i • m • ,. , „ tarded by pafling what/lower than the Undulations, their Velocity will be fome- through a me- ivhat leffened by this vibratory Tendency ; and, in the fame dium vibrating Medium, tlie more, as the Undulations are more frequent. ^ency/ For, as often as the ftate of the undulation requires a change in the actual motion of the particle which tranfmits it, that change will be retarded by the propenfity of the particle to continue its motion fomewhat longer : and this retardation will be more frequent, and more conliderable, as the diffe- M 2 renc« 164 THEORY Or LIGHT AND COLOURS. rencc between the periods of the undulation and of the natu- ral vibration is greater. Doftrint of heat Corollary. It was long an eftablifhed opinion, that heat con- vftratJoni'" flfts in vibrations of the particles of bodies, and is capable of being tranfmitted by undulations through an apparent va* cuum. (Newt. Opt. Qu. 18.) This opinion has been of late very much abandoned. Count Rumford, Profeflbr Pi&et, and Mr. Davy, are almoft the only authors who have appeared to favour it ; but it feems to have been rejected without any good grounds, and will probably very foon recover its popu- larity. Suppafe the Let us fuppofe that thefe vibrations are lefs frequent than tovibrate ■ '" *n°fe of light ; all bodies therefore are liable to permanent vibrations flower than thofe of light ; and indeed almoft all are liable to luminous vibrations, either when in a ftate of ignition, or in the circum fiances of folar phofphori; but much lefs ea- fily, and in a much lefs degree, than to the vibrations of heat, then the more It will follow from thefe fuppofitions, that the more frequent frequent lumi- iuminous undulations will be more retarded than the lefs fre- nous undula- tions will be quent ; and confequently, that blue light will be more refran- rnuft retarded, orible than red, and radiant heat leaf! of all; a confequence Blue light will « . ' , n- be mod refraft- which coincides exactly with the highly lntereftmg experi- ed, and radiant ments Qc Dr. Herfchel. (Phil. Tranf. for 1800, p. 284.) It ' may alfo be eafily conceived, that the actual exiflence of a ftate of flower vibration may tend flill more to retard the more ana refractive frequent undulations, and that the refractive power of folid power will in- bodies may be fenhbly increafed by an increafe of tempera- creafe with the . J - .. J . ' , • t- i > temperature. t»re> as li 'actually appears to have been in Euler's experi- ments. (Acad, de Berlin. 1762. p. 328.) Scholium. If, notwithfianding, this propofition fhould ap- pear to be infufficiently demonftrated, it mufl be allowed to be at leaf! equally explanatory of the phenomena with any thing that can be advanced on the other fide, from the doctrine of Thispofition projectiles; fince a fuppofed accelerating force mufl act in explains the phe- fome other proportion than that of the bulk of the particles ; TeaftaswelTas and, if we call this an eleaive attraftion, it is only veiling the projectile under a chemical term, our incapacity of afiigning a mecha- hypothefis. nica] caufe> Mr Shortj when he found hy 0bferv'ation tlie equality of the velocity of light of all colours, felt the objec* tion fo forcibly, that he immediately drew an inference from it in favour of the undulatory fyftem. It is affumed in the , propofitiop. THEORY OF LIGHT AND COLOURS. 165 propofition, that when light is difperfed by refraaion, the corpufcles of the refrading fubftance are in a date of aftual alternate motion, and contribute to its tranfmiflion ; but it mud be confefled, that we cannot at prefent form a very de- cided and accurate conception of the forces concerned m maintaining thefe corpufcular vibrations. PROPOSITION VIII. When tzvo Undulations, from different Origins, coincide either Prop. VIII, perfeaiy or very nearly in Direaion, their joint Effect is a JJj^^J^1 Combination of the Motions belonging to each, region will Since every particle of the medium is affected by each un- dulation, wherever the directions coincide, the undulations can proceed no otherwife than by uniting their motions, fo that the joint motion may be the fum or difference of the fepa- rate motions, accordingly as fimilar or diffimilar parts of the undulations are coincident. I have, on a former occafion, infifted at large on the appli- cation of this principle to harmonics; (Phil. Tranf. for 1800, p. 130.) and it will appear to be of ftill more extenfive uti- lity in explaining the phenomena of colours. The undulations Effe&s when which are now to be compared are thofe of equal frequency, fal^cy. When the two feries coincide exactly in point of time, it is obvious that the united velocity of the particular motions muft be greateft, and, in effect at leaft, double the feparate velo- cities ; and alfo, that it muft be f mailed, and if the undula- tions are of equal ftrength, totally deftroyed, when the time of the greateft direct motion belonging to one undulation coin- cides with that of the greateft retrograde motion of the other. In intermediate ftates, the joint undulation will be of inter- mediate ftrength ; but by what laws this intermediate ftrength muft vary, cannot be determined without further data. It is well known that a fimilar caufe produces in found, that effeel The beat in which is called a beat ; two feries of undulations of nearly foun<1- equal magnitude co-operating and deftroying each other alter- nately, as they coincide more or lefs perfectly in the times of performing their refpective motions, Coroll ar y 1 . Of the Colours ofjlriated Surfaces, Boyle appears to have been the firft that obferved the co- Colours of ftri- lours of fcratches on polilbed (urfaces. Newton has not no- atcd fj?6"* ticed explained, 166 THEORY OF LIGHT AND COLOURS. ticed them. Mazeas and Mr. Brougham have made fome ex- periments on thefubject, yet without deriving any fatisfactory conclufion. But all the varieties of thefe colours are very caiily deduced from this propofition. by the greater Let there be in a given plane two reflecting points very near (oHiw rf"n- each other' and let the Plane be fo fixated that the refleded duiation) from image of a luminous object feen in it may appear to coincide the deprefled with t{)e jntg then ^ fe obv;ous (h t tj j th f fa { • rortion of (ur- j ace, dent and reflected ray, taken together, is equal with reipect to both points, confidering them as capable of reflecting in all directions. Let one of the points be now deprefled below the given plane; then the whole path of the light reflected from it, will be lengthened by a line which is to the depreflion of the point as twice the cofine of incidence to the radius. Fig. 2. Plate VI. which will occa- If, therefore, equal undulations of given dimensions be re- oHnttnCitY anT ^e^e<^ fr°m two points, fituated near enough to appear to remiflion in the the eye but as one, wherever this line is equal to half the compound undu-breadth f h j undulation, the refledion from the de- lation ; accord- . .-'/.' . ingly as the de- preffed point will fo interfere with the reflection from the preffion caufes fixed p0U1t that the progreflive motion of the one will coin- the undu ations . , . V , i • r ^ i . . -,i of the fucceed- C]de with the retrograde motion or the other, and they will ing ray to coin- both be deftroyed ; but, when this line is equal to the whole pofe thofe of the Dreadth of an undulation, the effect will be doubled; and preceding ray. when to a breadth and a half, again deftroyed ; and thus for a confiderable number of alternations : and, if the reflected undulations be of different kinds, they will be varioufly af- fected, according to their proportions to the various length of the line which is the difference between the lengths of their two paths, and which may be denominated the interval of retardation, Experiment by In order that the effect may be the more perceptible, a parallel ftrokes j number 0f pajrs 0f points muil be united into two parallel lines ; and, if feveral fuch pairs of lines be placed near each other, they will facilitate the obfervation. If one of the lines be made to revolve round the other as an axis, the depreflion below the given plane will be as the fine of the inclination; and, while the eye and luminous object remain fixed, the difference of the length of the paths will vary as this fine, fuchas the fine The belt fubjects for the experiment are -Mr. Coventry's micrometers of eXqUifite micrometers ; fuch of them as coniift of parallel lines drawn THEORY OF LIGHT AND COLOURS. >-j7 drawn on glafs, at the diftance of one five hundredth of an cTftance of one inch, are the moft convenient. Each of thefe lines appears fiw hundredth under a microfcope to confifr of two or more liner lines, ex- actly parallel, and at the diftance of fomewhat more than a twentieth of that of the adjacent lines. I placed one of thefe when theangu- fo as to reflect the fun's light at an -angle of 45°, and fixed it l*r poliiion of - r , , • . • , , r i i- thefe 1S variC(l in luch a manner, tnat while it revolved round one ot the lines they produce as an axis, I could meafure its angular motion ; and I found, colours, that the brighteft red colour occurred at the inclinations 10^°, 20^°, 32°, and 45 y ; of which the fines are as the numbers ], 2, 3, and +. At all other angles alio, when the fun's light was reflected from the furface, the colour vanifhed with the inclination, and was equal at equal inclinations on either fide. This experiment affords a very ftrong confirmation of the which ftrongly theory. It is impoffible to deduce any explanation of it from *^fi^tu£vdy any hypothecs hitherto advanced; and I believe it would be theory. difficult to invent any other that would account for it. There is a ftriking analogy between this feparation of colours, and the production of a mufical note by fucceflive echoes from it is analogous equidiftant iron naliiades : which I have found to correspond *> the mufical ..... . r r i it ech° fr°m lron pretty accurately with the known velocity ot iound, and the raii8% diftances of the furfaces. It is not improbable that the colours of the integuments of Verfatile colours tome infects, and of fome other natural bodies, exhibiting in of fome Mtf*&*» different lights the moft beautiful verfatility, may be found to tnis' nature. be of this defcription, and not to be derived from thin plates. In fome cafes, a tingle fcratch or farrow may produce fimilar effects, by the reflection of its oppofite edges, Corollary 2. Of the Colours of thin Plates. When a beam of light falls on two parallel refracting fur- Colours of thin faces, the partial reflections coincide perfectly in direction ; P!ates explained and, in this cafe, the interval of retardation, taken between the furfaces, is to their diftance as twice the cofine of the angle of refraction to the radius. For, in Fig. 3, Plate VI. draw- ing A JB and C D perpendicular to the rays, the times of paf- fing through B C and A D will be equal, and D E will be hair" the interval of retardation ; but D E is to C E as the fine of DC E to the radius. Hence, that D E may be conusant, or by the greater that the fa:ne colour may be reflected, the thicknefs C E mnft length of ray re- vary as the iecant of the angle of refraction Q E D : which pofteriorfarface! agrees which muft pro* ° duce an effect 168 fimilar to that of the ftriated fur* faces; namely colours, which will be tranfmitted and reflected by- turns if t e thicknefs gra- dually vary, as in the Newto- nian rings. Breadth and duration of the colorific undula tions deter- mined, and compared with thofe of found. THEORY OF LIGHT AND COLOURS. agrees exactly with Newton's experiments ; for the correction is perfectly inconiiderable. Let the medium between the furfaces be rarer than the fur- rounding mediums ; then the irrfpulfe reflected at the fecond furface, meeting a fubfequent undulation at the firft, will ren- der the particles of the rarer medium capable of wholly flop- ping the motion of the denfer, and deftroying the reflection, (prop, iv.) while they rhemfeives will be more ftrongly propelled than if they had been at reft ; and the tranfmitted light will be increafed. So that the colours by reflection will be deftroyed, and thole by tranfmiflion rendered more vivid, when the double thickneffes, or intervals of retardation, are any multiples of the whole breadths of the undulations ; and, at intermediate thickneffes the effects will be reverfed ; accord- ing to the Newtonian obfervations. If the fame proportions be found to hold good with refpect to thin plates of a denfer medium, which is indeed not impro- bable, it will be neceffary to adopt the corrected demonltra- tion of prop. iv. but, at any rate, if a thin plate be inter- pofed between a rarer and a denfer medium, the colours by reflection and tranfmiflion may be expected to change places. From Newton's meafures of the thickneffes reflecting the . different colours, the breadth and duration of their refpective undulations may be very accurately determined ; although it is not improbable, that when the glaffes approach very near, the atmofphere of ether may produce fome little irregularity. The whole vifible fpectrum appears to be comprifed within the ratio of three to five, or a major fixth in mufic j and the un- dulations of red, yellow, and blue, to be related in magni- tude as the numbers 8, 7, and 6 ; fo that the interval from red to blue is a fourth. The abfolute frequency expreffed in num- bers is too great to be diftinctly conceived, but it may be bet- ter imagined by a comparifon with found. If a chord found- ing the tenor c, could be continually bifected 40 times, and fhould then vibrate, it would afford a yellow green light : 41 40 this bring denoted by c, the extreme red would be a, and the 4. 1 blue d. The abfolute length and frequency of each vibration is expreffed in the table; fuppofmg light- to travel in 8-J mi- nutes .500,000,000,000 ket Colours. THEORY OF LIGHT AND COLOURS. 169 Length of an Undulation Number Number of Undulations Colours. in parts of of Undu- in a Second. an Inch, in lations in Air. an Inch. Extreme .0000266 37640 463 millions of millions. Red - - .0000256 39180 4S2 Intermediate .0000246 40720 501 Orange - .0000240 41610 512 Intermediate .0000235 42510 523 Yellow - - .0000227 44000 542 Intermediate .0000219 45600 561 (= 24S nearly) Green .0000211 47460 584 Intermediate .0000203 49320 607 Blue - .0000196 51110 629 Intermediate .0000189 52910 652 Indigo .0000185 54070 665 Intermediate .0000181 55240 680 Violet - - .0000174 574901 707 Extreme - .0000167 597501 735 Table of colori- fic undulatiout of the ether. Scholiwn. It was not till I had fatisfied myfelf reflecting Quotation from all thei'e phenomena, that I found in Hooke's Micrographia, Robert Hooke r » exhibiting a fi- a paflage which might have led me earlier to a fimilar conclu- mijar doctrine, lion. ff It is moll evident that the reflection from the under or further fide of the body, is the principal caufe of the pro- duction of thefe colours. — Let the ray fail obliquely on the thin plate, part therefore is reflected back by the firft fuperfi- cies, — part refracted to the iecond furface, — whence it is re- flected and refracted again. — So that, after two refractions and one reflection, there is propagated a kind of fainter ray—/' and, '*. by reafonof the time fpent in palling and repafling, — - this fainter pulfe comes behind the" former reflected " pulfe ; fo that hereby , (the furfaces being fo near together that the eye cannot difcriminate them from one,) this confufed or du- plicated pulfe, whofe ftrongeft part precedes, and whofe weake ft follows, does produce on the retina, the fenfation of a yellow. If thele furfaces are further removed afunder, the weaker pulfe may become coincident with the" reflection of the fecond," or next following pulfe, from the firft furface, " and lagg behind that alfo, and be coincident with the third, fourth, fifth, fixth, feventh, or eighth — ; fo that, if there be a thin tranfparent body, that from the greateft thinnefs requU fite, J70 THEORY OF LIGHT AND COLOURS. fite to produce colours, does by degrees grow to the greateft thicknefs, the colours (hall be fo often repeated, as the weaker pulfe does lofe paces with its primary or firft pulfe, and is co- incident with a" fubfequent ** pull!'. And this, as it is coin- cident, or follows from the firft hypothecs. I took of colours, fo upon experiment have I found it in multitudes of inftances which wa» that feem to prove it." (P. 65 — 67.) This was printed vewTbefav* about feven years before any of Newton's experiments were Newton made made. We are informed by Newton, that Hooke was after- hi« experiments. wards Jifpofed to adopt his " fuggeftion" of the nature of colours ; and yet it does not appear that Hooke ever applied that improvement to his explanation of thefe phenomena, or inquired into the neceflary confequence of a change of obli- quity, upon his original fuppofition, otherwife he could not but have difcovered a flriking coincidence with the meafures laid down by Newton from experiment. AH former attempts to explain the colours of thin plates, have either proceeded on fuppofitions which, like Newton's, would lead us to ex- pect the greateft irregularities in the direction of the refracted rays ; or, like Mr. Michell's, would require fuch effects from the change of the angle of incidence, as are contrary to the effects obferved ; or they are equally deficient with refpect to both thefe circum fiances, and are inconfifient with the moil moderate attention to the principal phenomena. Corollary 3. Of the Colours of thick Plates. Colours of thick When a beam of light paflfes through a refracting furface, plates explained efpecially if imperfectly polifhed, a portion of it is irregularly length of fuch Mattered, and makes the furface vifible in all directions, but rays of fcatceredmoft confpicuoufly in directions not far diftant from that of the Sthrprinct1^^^1^ and> ^reflecting &** be placed parallel to pal ray) as pafs the refracting furface, this fcattered light, as well as the prin- through the firft ci j be wij| be refle&ed, and there will alfo be a new dif- furface, and are r , ' reflected from npation of light, at the return of the beam through the refract- the fecondwith jng furface. Thefe two portions of fcattered light will coin- cide in direction ; and, if the furfaces be of fuch a form as to collect the iimilar effects, will exhibit rings of colours. The interval of retardation is here, the difference between the paths of the principal beam and of the fcattered light between the two furfaces ; of courfe, wherever the inclination of the fcattered light is equal to that of the beam,, although in diffe- 2 rent THEORY OF LIGHT AND COLOURS. 171 rent planes, the interval will vanifli, and all the undulation? will confpire. At other inclinations, the interval will be the difference of the fecants from the fecant of the inclination or angle of refraction of the principal beam. From thefe caufes, all the colours of concave mirrors obferved by Newton and others are neceffary confequences : and it appears that their production, though fomewhat fimilar, is by no means, as Newton imagined, identical with the production of thole of thin plates. Corollary 4. Of Blacknefs. In the three preceding corollaries, we have confidered the Bhcknefs pro- refracting and reflecting fubftances as limited by a mathema- ^"y^J"^ tical furface; but this is perhaps never phyiically true. The tions at the con- ethereal atmofpheres may extend on each fide the furface as £ne of ^ fu£ far as the breadth of one or more undulations ; and, if they be ether gradually fuppofed to vary equally in denfity at every part, the partial var'es «« denr reftedions from each of the infinite number of i'urfaces, jw^gtofwhkhit.that the denfity changes, will very much interfere with each other, the undulations and deflroy a confiderable portion of the reflected light, fo^ro"neach that the fubftance may become pofitively black ; and this ef- other, and con- fed may take place in a greater or lefs degree, as the denfity [*JJJ2oa of of the ethereal atmofphcre varies more or lefs equably ; and, light. in fome cafes, particular undulations being more affected than others, a tinge of colour may be produced. Accordingly, M. Bouguer has obferved a confiderable lofs of light, and in fome inftances a tinge of colour, in total reflections at the fur- face of a rarer medium. Corollary 5. Of Colon rs by Jnflcchon . Whatever may be the caufe of the inflection of light pailing Colours by inn through a (mall aperture, the light near e It its centre mud befle is the fine of the inclination of the incident ray to the radius, where it meets this circle; therefore by the proportion quoted, the an- gle defcribed is in a given ratio to the angle at the centre, 1 which is the difference of the inclinations. Making xx 7* s •or — radius, the fi-ne, inilead of y} becomes .?, and the cofine VOL. — ss, or —y/l -~yy, and, when y = .?.?, x/ 1 — as; yy y therefore the line intercepted is to the difference of the fluents as r to r — 1 . (See alfo Young's Syllabus, Art. 372.) PROPOSITION IX. -Radiant Light confijls in Undulations of the luminiferous Ether . Conclusion. Ra- This propofiiion is (he general conclufion from all the pre- SS'ia^StaET ceding ; and it is conceived that they confpire to prove it in as tions of the fatisfa&ory a manner as can poflibly be expecled from the na-ether* ture of the fubjeft. It is clearly granted by Newton, that there are undulations, yet he denies that they conftitute light ; but it is -mown in the three firft Corollaries of the laft Propofi- iion,. that all cafes of the increafe or diminution of light are referable to an increafe or diminution of fuch undulations, and that all the affections to which the undulations would be liable, are diftindtly vifible in the phenomena of light ; it may there- fore be very logically inferred, that the undulations are light. A few detached remarks will ferve to obviate fome objec- tions which may be raifed againft this theory. 1 . Newton has advanced the fingular refraction of the Ice- Remarks. New- land cryftal, as an argument that the particles of light mull be Fon with°ut g',v' projected corpufcles ; fince he thinks it probable that the dif- jeaed the law of ferent fides of thefe particles muft be differently attraded by Huygens in ex- the cryftal, and fince Huygcns has confeflbd his inability to Jhenomeiuof account Iceland cryftal. 174? TH/iORY OF LIGHT AND COLOURS. account in a fatisfactory manner for all the phenomena. But, contrarily to what might have been expected from Newton's ufuaJ accuracy and candour, he has laid down a new law for the refraction, without giving a reafon for rejecting that of Huygens, which Mr. Hauy has found to be more accurate than Newton's; and, without attempting to deduce from his own fyftem any explanation of the more univerfal and linking ef- fects of doubling fpars, he has omitted to obferve that Huy- gens's mod elegant and ingenious theory perfectly accords with thefe general effects, in all particulars, and of courfe derives from them additional pretentions to truth : this he omits, in order to point out a difficulty, for which only a verbal folu- tion can be found in his own theory, and which will probably- long remain unexplained by any other. MicheiPs expe- o. Mr. Michell has made fome experiments, whioh appear momentum of to mow ^iat tne rays °f nSnt nave an a&ual momentum, by lightexphined, means of which a motion is produced when they fall on a thin ZSfjT *ni-l PIate of coPFer delicately fufpended. (Priefliey's Optics.) tion. But, taking for granted the exact perpendicularity of the plate, and the abfence of any afcending current of air, yet fince, in every fuch experiment, a greater quantity of heat mult be communicated to the air at the furface on which the light falls than at the oppofite furface, the excefs of expanfion mutt ne- ceffarily produce an excefs of preffure on the firft furface, and a very perceptible receflion of the plate in the direction of the They did not light. Mr. Bennet has repeated the experiment, with a fucceed with mUch more fenfible apparatus, and alio in the abfence of air ; and very juftly infers from its total failure, an argument in fa- vour of the undulatory fyftem of light. (Phil. Tranf. for 17.92, p. 87.) For, granting the utmoft imaginable fubtiJity of the corpufcles of light, their effects might naturally be expected to bear fome proportion to the effects of the much Iefs rapid mo- tions of the electrical fluid, which arc fo very eaiily percep- tible, even in their weakeft ftates. latent light and 3. There are fome phenomena of the light of folar phof- fiftTnrwkhCthc" Pbon*' which at firft fight might feem to favour the corpufcular do&rineofvi- fyftem; for inftance, its remaining many months as if in a brations. latent ftate, and its fubfequent re-emiffion by the action of heat. But, on further confideration, there is no difficulty in fuppofing the particles of the phofphori which have been made to vibrate by the action of light, to have this action abruptly fufpended THEORY OF LIGHT AND COLOURS. 175 fufpencled by the intervention of cold, whether as contracting the bulk of the fubftance or otherwife ; and again, after the reftraint is removed, to proceed in their motion, as a fpring would do which had been held faft for a time in an interme- diate ftage of its vibration ; nor is it impoilible that heat itfelf may, in fome circumftances, become in a fimilar manner la- tent. (Nicholfon's Journal, Vol. II. p. 399.) But the af- fections of heat may perhaps hereafter be rendered more in- telligible to us ; at prefent, itfeems highly probable that light differs tfrom heat only in the frequency of its undulations or Light and heat vibrations; thofe undulations which are within certain limits, fj! ^^y 0£ C e with refpect to frequency, being capable of affecting the optic undulation or nerve, and constituting light ; and thofe which are flower, Vlbrat,0n> and probably ftronger, conflicting heat only ; that light and heat occur to us, each in two predicaments, the vibratory or permanent, and the undulatory or tranfient ftate j vibratory light being the minute motion of ignited bodies, or of folar phofphori, and undulatory or radiant light the motion of the ethereal medium excited by thefe vibrations ; vibratory heat being a motion to which all material fubftances are liable, and which is more or lefs permanent ; and undulatory heat that motion of the fame ethereal medium, which has been mown capable in both by Mr. King, (Morfels of Criticifm, 1786, p. 99,) and M. ££* jJjjJS^. Picket, {Ejfais de Plu/fique, 1790, alfo in Saulfure's Voyage tions. dans les Alpes, 1786.) to be as capable of reflection as light, and by Dr. Herfchel to be capable of feparate refraction. (Phil. Tranf. for 1800, p. 284,) How much more readily heat is communicated by the free accefs of colder fubflances, than either by radiation or by tranfmiflion through a quiefcent medium, has been mown by the valuable experiments of Count Rumford. It is eafy to conceive that fome fubflances, permeable to light, may be unfit for the tranfmiflion of heat, in the fame manner as particular fubflances may tranfmit fome kinds of light, while they are opaque with refpect to others. On the whole it appears, that the few optical phenomena This theory ex- which admit of explanation by the corpufcular fyftem, are Plains ,ail that 1S .,,., i • f t • i i°!vec| by the equally confident with this theory ; that many others, which corpufcular fyf- have long been known, but never underflood, become by tem» and much thefe means perfectly intelligible ; and that feveral new facts are found to be thus only reducible to a perfect analogy with other facts, and to the fimple principles of the undulatory fyftem. J76 THEORY OF LIGHT AND COLOURS. fyftem. It is prefumed, that henceforth the fecond and third books of Newton's Optics will be confidered as more fully underflood than the firft has hitherto been ; but, if it mould appear to impartial judges, that additional evidence is want, ing for the eftablifliment of the theory, it will be eafy to enter more minutely into the details of various experiments, and to fhow the infuperable difficulties attending the Newtonian doc* trines, which, without neceffity, it would be tedious and in- vidious to enumerate. The merits of their author in natural philofophy, are great beyond all conteft or comparison ; his optical difcovery of the compolition of white light, would • alone have immortalifed his name ; and the very arguments which tend to overthrow his fyftera, give the flrongeft proofs of the admirable accuracy of his experiments. Experiment In Sufficient and decifive as thefe arguments appear, it cannot which the cor- De fuperfluous to feek for further confirmation: which may pulcular theory . , - \ ' V , r ~,ir • ought to exhibit with connderable confidence be expected, from an experiment diftortion. verv ingenioufly fuggefled by Profeflbr Robifon, on the re- fraction of the light returning to us from the oppofite margins' of Saturn's ring ; for, on the corpufcular theory, the ring mull: be confiderably diftorted when viewed through an achro- matic prifm : a fimilar diftortion ought alfo to be obferved in the difc of Jupiter ; but, if it be found that an equal deviation is produced in the whole light reflected from thefe planets, there can fcarcely be any remaining hope to explain the affec- tions of light, by acomparifon with the motions of projectiles. IV. An Analyfis of a Mineral Subftance from North America, con* taining a Metal hitherto unknown. 5j/CharlesHatch ett, ( Conclu dedfrom Page 1 3 3 . ; H. The white pre- A HE white precipitate, when diftilled with four parts of c£'^V?s,!^lefulphur, remained pulverulent, and, from white, was only affected by dif- , „ tiilation of the changed to a pale a(h colour. fulphuric and Nitric acid was digefted on the powder, and, being heated, afforded fome nitrous gas; after this, the powder became white., and in every refpect recovered its original properties. Before ACCOUNT OF A MINERAL SUBSTANCE. 177 I. Before I conclude this fection, I muft obferve, that when The precipitates the olive-green precipitates, obtained by pruffiate of potafti, ^g^ompoffd weredigefted in an alkaline lixivium, they were decompofed ; by humid alkali, for the alkali combined with the pruffic acid, and with afmall f lich tou}\ UP, part of the white matter; but the greater part of the latter a |jtt]e 0f the remained undiilblved, in the fame white flocculent ftate which white matter, was noticed when the alkaline combinations were mentioned. The orange-coloured precipitates, formed by tincture of galls, were alfo decompofed when digefled in boiling nitric acid ; and the white matter was recovered in its original ftate. § III. REMARKS. The preceding experiments mew, that the ore which has Obf. The ore been analy fed, coniifts of iron combined with aiv unknown ^ree^'arts of iubftance, and that the latter conftitutes more than three- the white mat- fourths of the whole. This fubftance is proved to be of a Jjf* . M . 1 ... The latter is me- metallic nature, by the coloured precipitates which it forms tallic; for it is with prufliate of potafli, and with tin6ture of galls ; by the P/eciP- ^ Pruf* eflects which zinc produces, when immerfed in the acid folu- g^^ and by lions ; and by the colour which it communicates to phofphate zinc> anJ itcp- of ammonia, or rathor to concrete phofphoric acid, when melt- by fufionl ed with it. Moreover, from the experiments made with the blow-pipe, It is of difficult it feems to be one of thole metallic fubftances which retain redu"10n> oxigen with great obftinacy, and are therefore of difficult re- duction. It is an acidifiable metal ; for the oxide reddens litmus and acidifiable. paper, expels carbonic acid, and forms combinations with the fixed alkalis. But it is very different from the acidifiable me- tals which have of late been difcovered ; for, 1. It remains white when digefted with nitric acid. Differs from all 2. It is foluble in the fulphuric and muriatic acids, and able^meulT/in ' forms colourlefs folutions, from which it may be precipitated, the properties in the ftate of a white flocculent oxide, by zinc, by the fixed ^f^™™' alkalies, and by ammonia. Water alfo precipitates it from the fulphuric folution, in the ftate of a fulphate. 3. Pruiliate of potafh produces a copious and beautiful olive- green precipitate. Vol II.— July, 1802. N 4. Tin&ure 178 ACCOUNT OF A MINERAL SUBSTANCE. 4. Tinfture of galls forms orange or deep yellow preci- pitates. 5. Unlike the other metallic acids, it refufes to unite with ammonia. 6. When mixed and diftilled with fulphur, it does not com- bine with it fo as to form a metallic fulphuret. 7. It does not tinge any of the fluxes, except phofphoric acid ; with which, even in the humid way, it appears to have a very great affinity. 8. When combined with potafh and diffolved in water, it forms precipitates, upon being added to folutions of tungftate of potafh, molybdate of potafh, cobaltate of ammonia, and the alkaline folution of iron. Thefe properties completely diftinguifh it from the other acidifiable metals, viz. arfenic, tungften, molybdena, and chro- mium; as to the other metals lately difcovered, fuch as ura- nium, titanium, and tellurium, they are (till farther removed from it. The colours of the precipitates produced by prufliate of pot- afh and tincture of galls, approach the neareft to thofe afforded by titanium. But the pruffiate of the latter is much browner ; and the gallate is not of an orange colour, but of a brownifh red, inclining to the colour of blood. JBefides, even if thefe precipitates were more like each other, ftill the obftinacy with which titanium refufes to unite with the fixed alkalis, and the infolubility of it in acids when heated, fufficiently denote the different nature of thefe two fubftances. The iron Is in The iron in the ore which has been examined, is apparently ftatt of brown jn ^e fame ftate as it is in wolfram, viz. brown oxide; and this oxide is mineralized by the metallic acid which has been defcribed, in the fame manner as the oxides of iron and man- ganefe are mineralized by the tungftic acid or rather oxide. For, from feveral experiments made upon a large fcale, I have reafon to believe that in wolfram, the tungften has not attained the maximum of oxidation. Several facls in the courfe of the experiments lately defcribed, feem to prove, that this new me- tal differs from tungften and the other acidifiable metals, by a more limited extent of oxidation ; for, unlike thefe, it feems to be incapable of retaining oxigen fufficient to enable the total quantity to combine with the fixed alkalies. In § II. G. 2, this. ACCOUNT OF A MINERAL SUBSTANCE. 179 this is very evident ; for, from the experiment there defcribed, it appears, that when the metallic acid or oxide was digefted with lixivium of potafh, only a part was diffolved ; and that the remainder was infoluble in the fame lixivium, till it had received an additional portion of oxigen, by being treated with nitric acid ; alfo that feveral of thefe alternate operations were re- quired, before any given quantity of the metallic oxide could be completely combined with the alkali. Now there is much reafon to believe, that in this cafe, when the metallic oxide or acid was digefted with potalh, the portion which was diffolved received an acceffion of oxigen at the expence of the other part, which of courfe was thus reduced to the ftate of an info- luble oxide, and therefore required to be again oxidated by nitric acid, before it could combine with the alkaline folution ; but ftill it appeared, that an adequate proportion of oxigen could never be fuperinduced, fo as to render the oxide totally and immediately foluble in the alkalies by one operation, or even by two. We may, therefore, regard this as an inftance of the effects refill ting from difpofing affinity, and as very fimilar to thofe obferved in refpecl to copper, which have been noticed by my ingenioits friend Mr. Chenevix, in his valuable analyfis of the arfeniates of copper and of iron *; My refearches into the properties of this metal, have of From the limited courfe been much limited by the fmallnefs of the quantity "Marches on the 1-ttii i /-i/>i fmall quantity or which I had to operate upon ; but I flatter myfelf that more 0re, the only de- of the ore may foon be procured from the Maffachufet mines, du&»°n as to particularly as a gentleman now in England (Mr. Smith, Se- utility is, that cretary to the American Philofophical Society), has obligingly the precipitates offered his affiftance on this occafion. We (hall then be able *re fine colours' more fully to inveftigate the nature of this fubftance ; and (hall be more capable of judging how far it may be applicable to ufeful purpofes. At prefent, all that can be faid is, that the olive-green pruiliate and the orange-coloured gallate are fine colours ; and, as they do not appear to fade when expofed to light and air, they might probably be employed' with advantage as pigments. I am much inclined to believe, that the time is perhaps not The new metals very di/tant, when fome of the newly difcovered metals, and are probably compounds. * Phil, Tranf. for 1801, p. 2o3, N 2 other. ]80 ACCOUNT OF A MINERAL SUBSTANCE. other fubftances, which are now confidered as fimple, primi- tive, and diftinct bodies, will be found to be compounds. Yet I only entertain and ftate this opinion as a probability ; for, until an advanced ftate of chemical knowledge fhall enable us to compofe, or at leaft to decompofe, thefe bodies, eacn mult be clafled and denominated as a fubftance fui generis. Conii- dering, therefore, that the metal which has been examined is fo very different from thofe hitherto dilcovered, it appeared proper that it fliould be diftinguimed by a peculiar name; and, having confulted with feveral of the eminent and ingenious chemifts of this country, I have been induced to give it the name of Columbium. POSTSCRIPT. It appears proper to mention fome unfuccefsful attempts which I have lately made to reduce the white oxide. Rrilu&ion. The Fifty grains were put into a crucible coated with charcoal; w ^on^black- anc^ De'ng covered with the fame, the crucible was clofelv ened by the luted, and was expofed to a ftrong heat, in a fmall wind fiir- ftrong heat with nace during about one hour and an half. When the crucible caaicoal. ° was broken, the oxide was found in a pulverulent ftate ; and, from white, was become perfectly black. The phofphuret. In order to form a phofphuret, fome phofphoric acid was poured upon a portion of the white oxide ; and, being eva- porated to drynefs, the whole was put into a crucible coated with charcoal^ as above defcribed. The crucible was then placed in a forge belonging to Mr. Chenevix, and a ilrong heat was kept up for half an hour. The inclofed matter was fpongy, and of a dark brown; it in fome meafure refembled phofphuret of titanium. After this we wiflied to try the effect of a ft ill greater heat ; but in this experiment the crucible was melted. The above experiments fhew, that the white oxide, like feveral other metallic fubftances, may be deoxidated to a cer- tain degree, without much difficulty, but that the complete re- duction of it is ftill far from being eafily effected. V. On EFFECT OF SOUND ON THE BAROMETER. ]$1 V. On the Ejfi& of Sound upon the Barometer. By Sir Henry. C. Englefield, Bart. F. 11. S. (From the Journals of the Royal Inftitution, No. 9. J , •JDuRING the time I fpent at Bruflels in the year 1773 and Whether the ba- 1774., it occurred to me, that the effect of found on the barome- JJgJjL fon^ ter had not, to my knowledge, been attended to ; and that it rous undulation. was by no means certain, whether that inftrument was capable of being fenfibly affected by thofe elaftic vibrations caufed in the atmofphere, by the perculfion of a fonorous body. I thought the idea worthy of being purfued, and the means of making fatisfactory experiments were moft opportunely in my power. The found of a very large bell appeared to me the mod The bell prefer- powerful, and at the fame time to be approached with the red for exPen" greateft fecurity and eafe to the obferver. The explofion of artillery, belides the very difagreeable fmokeand danger of the xecoil, might be objected to, on account of the fudden produc- tion of elaftic and heated vapour, which might, independent of the found, inftantaneoufly alter the ftate of the atmofphere, and thereby lead the obferver into very great and unavoidable errors. Every one who has been in the Low Countries muft know, Large bells In the that very large bells, and immenfe numbers of them, are the Netherlands» pride of their churches ; and that they are rung' quite out, not tolled, on every great feftival. The great bell of the collegiate church of St. Gudula, at Bruflels, weighs, as I was told, fix- teen thoufand pounds, and on this I determined to found my experiment. Two objections only could be made to the refult of this ex- Whether thefe periment, the one, that the motion of the bell might caufe a vi- would produce jrrc£u]ariCY dv bration in the walls of the building, which would hinder the agitating the placing the barometer in a ftate of repofe ; the other, that the building or the twinging fo large a mafs with a confiderable degree of velocity, might of itfelf agitate the air fo as to caufe vibrations in the mercury totally independent of found. The ftrength of the walls of the fteeple, and the manner of Obfemtibns, hanging the bell, which was contained in a frame of limber, founded Preparation for experiment. 152 EPFECT OF SOUND ON THE BAROMETER. founded on a ftrong vault, and totally independent of the wall of the fteeple, might alone have anfwered the firft of thefe ob- jections; but happily a moft complete and fatisfaclory anfwer to both of them, was furnifhed by the manner in which the bell was rung. As the bell was to ring out full in an inftant, at a fignal given from below, it is neceflary to have it in motion fome time beforehand; and during that time, the clapper is fixed to one fide by a ftrong ftick croffing the mouth of the bell, which, at the fignal, is pulled out by the hand of a perfon placed for that purpofe. If then, our barometer fhewed no variation during all this time, we were abfolutely certain that whatever motion was perceived afterwards, was wholly owing to the found. Mr. Pigott, who was then at BrufTels, was kind enough to lend me one of his barometers, made by Ramfden, and his fon made the following obfervations jointly withmyfelf ; At two o'clock in the afternoon of the lit of November 1773, we went into the north weft tower of St. Gudula's church, and having fixed the barometer firmly in the opening of a window, not above feven feet from the bottom of the bell, we waited quietly for its ringing. The height of the mercury before the bell began to fwing, as obferved by Mr. Pigott, was 29.478 inches. The bell be- ing in full fwing, no alteration whatever was perceptible. The inftant that the clapper was loofed the mercury leaped was elevated by up anj continued that fort of fpringing motion, at every ftroke the found of a *\ , . . , , , . r, . • ri , „ krge bell. °* the clapper, during the whole time ot the ringing of the bell, Thefe were our obfervations : During the ringing of the bell, Mr. P. - 29.469 During the ringing, by myfelf. Higheft 29.480 Loweft 29.474 Higheft 29.482 Loweft 29.472 Narrative, The mercury Thefe obfervations were made with the greateft attention ; and, confidering their delicacy and the difficulty of obferving, agree very nearly. They appear to give from 6 to 10 thou- fandths of an inch for the effect of this found on the barometer. It is to be obferved, that Mr. Pigott, in general, cftimated the EFFECT OF SOUND ON THE BAROMETER. 183 the height of the mercury about 5 thoufandths lower than my- ielf, which brings our obfervations to a very near agreement. The following obfervations prove this : On the top of the tower, Mr. P. - «■ 29.424 Ditto, by me 29.430 At the foot of the tower, Mr. P. - 29.639 Ditto, by me - - - - - 29.642 In the court of the Englifh Nuns, by Mr. P. 29.676 Ditto, by me 29.682 And I mould think that the difference of eyes may frequently caufe fuch a variation among different obfervers; at leaft in delicate obfervations, it will be always prudent to make the experiment. NOTE BY DR. YOUNG. THESE obfervations appear to agree too well with each Obfervations by other, to allow us to doubt of their accuracy. It therefore be- Dr* Youn6* comes neceffary to inquire into the caufes of the different heights of the barometer. It is indeed barely poffible, that a fudden ftroke of the clapper on the bell might produce a greater agitation of the building than the preceding alternate motion of the bell itfelf: but this explanation cannot be called fatisfaclory. It is certain, that there was neither more nor lefs air in the tower while the bell was founding, than while it was filent; the mean denfity of the air could therefore not have The mean den* been changed; and if the alternate motions of the particles of flty of theair air which constitute found, had taken place by equal degrees, changed, and with equal velocities, in each oppofite direction, there is no reafon to fuppofe that the increafe of prefTure on the furface of the mercury, at one inftant, could have tended to raife it, more than the decreafe of preffure, in the oppofite irate of the undulation, would have depreffed it. But the fame confe- If the motion of quence does not follow, if we conceive the motion of the air, more ra Tddian in advancing, to be more rapid, but of fhorter continuance, of return in the than its retrograde motion. For if the wind blew for one hour undu|atl0ns> » . ,. , i r • i-i r w°u!d have the with a velocity ot 4, and the lame air returned, in the courfe effect of a pref- of two hours, with a velocity of 2, an obftacle upon which it fure« had acted in both directions would not be found in its original • place; for the action of the wind upon an obftacle is as the fquare JS41 EXPANSION OF CARBONATED HtDROGfcN. fquare of the velocity, and the time would not compenfatc for the difference of force. It is therefore eafy to fuppofe, that the law of the belPs vibration was in this experiment fuch, that the air advanced towards the barometer with a greater velocity than it receded, although for a (horler time; and that hence the whole effeel: was the fame as if the mean prellure of the air This law might had been increafed. Such a law might eafily refult from a from^uTbordinate C0mDmatl0n of a more regular principal vibration with one or vibrations, com- more fubordinate ones, in different relations ; and fimilar cafes b;ning with the mav fornetimes De obferved in the vibrations of chords. Here principal. J we find a flight degree ofrepulfion, in confequence of the un- Slight repulfions dulations of an elaflic medium. Dr. Hooke attempted to ex- from thIS caufe pj j tj phenomena of attraction by means of fimilar undula- in elaflic medi- \ . , ums. tions of an ether, which he fuppofed to be the medium fcrving Whether gra- [QV ^e communication of heat: but it mull be confeffed, that vuybefocaufed. . . _ . ., , r , ..,., the conjecture has little appearance ot probability. VI. On the Expanfion of Carbonated Hidrogen by Eleclricitj/. From a Correfpondent, To Mr. NICHOLSON. S I R, Expanfion of A VENTURE to trouble you with a few remarks on a phe* b'arbj «d.r°?en nomenon in chemiftry, the expanfion of carbonated hidrogen not yet explain- gas on the electric fpark being paffed through it. None of the cd. explanations of this circumftance which I have met with, ap^ pear to me to be fatisfactory ; and I have ffated a few objec- tions which occurred to me on confidering them. If you think them of fufficient weight to fill a corner of your ably-conducled Journal, fome correfpondent of greater abilities may perhaps give a new explanation of the facl. But if you think them beneath your notice, and unworthy of a place among the ex- cellent communications with which your numbers are filled, I have only to beg that you will pardon the prefumption of a very young ch mill, who, by this firff attempt, has perhaps only expofed his own ignorance. I am, Sir, Your's with much refpeel, Edm. JuneS, 1802. G. H. On tricity, EXPANSION OF CARBONATED HIDROGEN. J35 On the Expanfwn of carbonated Hidrogen Gas. This fact was firft obferved by Dr. Aufen. On pafling the Dr. Auftin fiift electric fpark through a quantity of carbonated hidrogen gas, ^^^-^ he found that the gas was permanently dilated to more than 1S expanded to twice its original bulk. He concluded that this remarkable doubl2 by elcc- expanfion could only be owing to the evolution of hidrogen gas. Upon burning the air thus expanded in oxigen gas, he found that it required more oxigen for its combuftion than an equal quantity of carbonated hidrogen gas, which had not been expanded by the electric fpark. An addition therefore had been made to the combujiible matter ; for the quantity of oxi- gen neceflary to complete the combuftion of any body, is al- ways proportional to the quantity of that body. He con- His theory that eluded from thefe experiments, that he had decompofed the carbon }' hidro" r ill gen and azote. carbon which had been diflblved in the hidrogen, and that carbon was compofed of hidrogen and azote, foine of which was always found in the veflel after the combuftion. If Dr. Auftin had more attentively conftdered the circum- Objcftlons. ilances of thefe experiments, he would probably been pre- "^^"not* vented from drawing this conclufion. The quantity of comb uf- more combufti- tible matter had been increafed. Now, if the expanfion of the ble than carbo" : 9 . ill and tlie Produ& carbonated hidrogen gas was owing merely to the decompo-js not mere fition of carbon, no fuch increafe ought to have taken place, ™ztc\ and azote» , . -,-!/• but alio carbonic but rather the contrary ; for the carbon, which was ltielt a ac;d gas. combuftible fubftance, was refolved into two ingredients, hi- drogen and azote, only the firft of which burnt on the addi- tion of oxigen, and the application of heat. And befules, if the carbon had been refolved into hidrogen and azote, the product of the combuftion could only have been a greater quan- tity of water, with a refiduum of azote; for the hidrogen evolved by the dilatation of the carbonated hidrogen gas, com- bining with the additional oxigen, muft have formed an addi- tional quantity of water. But it is a fact, which the Doctor does not feem to have attended to, that befides water, carbo- nic acid gas is produced from the combuftion of the expanded carbonated hidrogen. Whence, then, comes the carbonic acid gas ? Air. Henry *, who repeated Dr. Auftin's experiments with Mr. Henry great accuracy, found that he was correct with regard to the ^waiLa ii & * Philof. Tranfaft. 1797. 4 increafe 186 EXPANSION OF CARBONATED HIDROGEN. produced by hi- increafe of combuftible matter. He alfo found, that the ex- confotaTattr" Panfion C0llId not be carried beyond a certain point, about twice the original bulk of the gas. Upon burning feparately by means of oxigen, two equal portions of carbonated hidro- gen gas, one of which had been expended by electricity to twice its original bulk, the other not, he found that each of them produced precifely the fame quantity of carbonic acid gas ; a proof, that the carbon in both remained the fame, and that the hidrogen could not have been produced from it. He concluded therefore, that the evolution of the hidrogen is pro- duced from the decompofition of the water with which hidro- gen is always more or lefs impregnated ; to prove which, he took hidrogen gas, from which he expelled as much water as poflible, and found that the eleclric fpark produced a very fmall dilatation ; but on admitting a drop or two of water, the expanfion went on as ufual. It is eafily feen how this de- compofition is effected. Carbon at a high temperature has a greater affinity for oxigen than hidrogen gas ; when the tem- perature is raifed, therefore, by the electric fpark, the carbon unites with the oxigen of the water, forming carbonic acid gas, and the hidrogen is evolved. As to the azote, it mud have been produced from the admifiion of atmofpheric air into the procefs. But tliis difco- Although this theory of Mr. Henry feems to prove the pro- very does not duclion of hidrogen from the decompofition of the water con- greater quantity tained m tne gas J ftflt however, it is no more able to ac- of oxigen re- count for the increafe of combuftible matter than that of Dr. thcx 'anded™ Auftin. When the gas is dilated, hidrogen and oxigen are gas. evolved from the water. The hidrogen goes to increafe the bulk of the gas, and the oxigen unites with the carbon. Ex- panded carbonated hidrogen gas, then, contains hidrogen, carbon, and carbonic acid gas. In combuftion, the evolved hidrogen, in order to form water, requires a quantity of ad- ditional oxigen, precifely the fame as that with which it was combined before decompofition of the water : and on the other hand, the carbon requires precifely the fame quantity lefs, as part of it is already rendered incombufiible, by being com- bined with the oxigen of the water. Therefore, according to Mr. Henry's theory, a quantity of expanded carbonated hidrogen gas requires the fame quantity of oxigen for its com- buiiion, as an equal quantity that has not been expanded : and NEW PROCESS FOR CLAYING SUGARS. 187 and confequently they both contain the fame quantity of com- buftible matter ; for in proportion as the combuftible matter is increafed by the formation of hidrogen, in the fame pro- portion it is diminifhed by the formation of carbonic acid gas. But this is obferved to be contrary to fact; for carbonated hi- drogen gas when expanded does actually contain more com- buftible matter than before its expanfion. It would appear then, that a fatisfa6tory explanation of this increafe of com- buftible matter has not yet been given. G. H. VII. A netv Procefs for claying Sugars, propofcd by Cit. Ha pel- La c hen a ie, Chief Apothecary of the .Military Hofpitals of Guadaloupe, to the Agents of the Confuls of the French Repub* lie in the Windivard //lands *. JjEING called upon by the fcientific million confided to me Introdudtion* by the Government, to employ myfelf in every kind of re- fearch which may prove interefting to the cultivation and pro- ductions of this colony, I have thought it my duty to endea- vour to difcover a fimple, eafy, and cheap method of dif- penfing with the pottery which is ufed in the fabrication of clayed fugars. There was even an urgent neceffity that I fhould direct my Want of Pans attention to thefe objects, becaufe moft of the proprietors of for c!ay»"g fu- thefe colonies, being at this moment in want of the forms and mingo, pots hitherto confidered as indifpenfibly neceflary for the clay- ing fugars, are obliged to wait till the fmall number of pots they poflefs (hall be cleared of the fugar they contain before they can fabricate more. The delays occafioned by this inconvenience are the more obvioufly pro- prejudicial to the inhabitants in general, becaufe they are Jj n of great obliged, on this account, to defer cutting their canes when at the moft advantageous time of their growth ; and as they can- not perform this at the moft favourable feafon, their lofles are incalculable by fuffering the canes to grow old, and flnifiiing * From the Annales de Chimie, XL. 73. their 188 NEW PROCESS FOR CLAYING SUGARS'.- their gathering in the feafon when they afford very little fugar, in companion with what they would have yielded if they had been cut in time. While this retardation diminifhes the immediate product, it has an influence on the vigour of the fucceeding (hoots, as I have obferved, and renders their advancement lefs fpeedy. And by this means it expofes the farmer of national planta- tions to fail in payment of the terms of their location. Experiments for I {hall not dwell upon the various experiments I made be- e * fore my fuccefs was complete, but (hall confine myfelf to thofe means which have befl fucceeded with me, and to which I have confined myfelf in the fubfequent pradice in my fugar- work. furarto°beSthe This Procefs confifts In difpofing the fugar in receptacles of clayed in large 12,937 cubic feet, each containing 26 ordinary forms, and to veflels. clay it in thefe fame receptacles, of which I fliall proceed to give a defcription : Firft ufedby fhe priority of the method which I propofe belongs to Cits. Citizens Bou- „ ,. irni i • • i • - r£ cherie at Paris, tfoucnene, who hrlt adopted it in their refinery of Bercy near Paris, They were, as far. as I know, the firft who conftructed veflels to clay the raw fugars they received from our colonies previous to their refining them. But though this invention is and improved by undoubtedly theirs, I alfo have a claim as to the degree of the Author. . J . b improvement which their vefiel did not pofTefs, but which I have given them by rendering them more convenient, advan- tageous, and economical *. Defcnption of The veflels of Citizens Boucherie were, as nearly as I can Citizens Bou- recollect, about 15 or 18 inches deep, and five feet wide, cherie. They were fquare, and the bottom of each was perforated with a great number of fmall holes for the difcharge of the fyrup, which fell into a fecond vefTel lefs deep, but of the fame dimenfions as the others as to their width. This fecond vefTel was lined with thin metallic plates, of an alloy invented by Mr. Hifkerdeau, a Spanifh chemift. The upper veflels * I attended their operations in the year 1784, before I came to this colony. I had alfo the advantage at that time of giving feveral leftures in their eftablifhraent to feme cultivators of St. Domingo and other fugar iflands, to facilitate their knowledge of the doc- .trine and procefTes of that interefting manufa&ure which they fre- quently vifited. were NEW TROCESS FOR CLAYING SUGARS. Ig9 werefupportcd on their edges by a level and firm framing, the inferior veflels Hood on the floor. The upper veflels were rilled with raw fugar intended to Charged with be clayed, which was firfl well divided or crumbled in order raw fu6ar- to its equal distribution. This was levelled and comprefTed as equally as poflible, to form what we commonly call, the bottom (ksfonds). Upon this mafs the diluted and prepared earth, properly adapted to the operation, was very carefully poured. Though this procefs may appear verv fimple at firft fight, This fimple pro- i • r e ,t ,f- i - i u r i u cefs is liable to it neverthelels preienls difficulties which could icarcely be ob:e(^jonSt overcome in that manufactory, and which would be almoft impollible to furmount in ours, where the men employed in this bufinefs have neither the underftanding nor the Ikill of thofe of Citizens Boucherie ; and it was not till they had practifed for fome time that they became able to perform it without difficulty. The hrrt operation in which a failure may be made for want it is difficult to of ikill, is that of levelling with a trowel an elaftic furface of level and prefs i • r r the fugar in the 25 fquare feet. The fecond is to comprels equally that iur- iarge veffels. face in order to give folidity to the bottom, that the diluted earth may extend to the fame thicknefs on all fides, and find that furface fo clofe as to admit the penetration of the water only. All thofe who are engaged in the manufacture of fugar mud Mifchievous be aware, that if any inequality exifts in the levelling of the badtvelhng'or^ bottom, the water which gradually leaves the earth naturally ptefllng. flows to the loweft place, where, if the compreffion be not every where the fame, the water infinuates itfelf into the moil porous part ; and in either of thefe cafes, this fluid being con- The water flows du&ed with the earth towards a {ingle point, is collected in t0 the l°we#ft fufficient abundance to diflblve the fugar at that place, and f0^ves ^ fu'g~r . form what is called a fox [un renard.) When this happens the while the reft is Operation of claying fails, for it is known that the portion of not u pun earth retained at the furface acts little upon the reft of the mafs of fugar. This inconvenience, which occafions a great lofs in the product, is alfo found to change its quality, which is worfe on this account. In the conftruction of the cafes or vefTels of Citizens Bon- The fugar is not cherie, which cannot be removed, other inconveniencies are ea% takcn out* found which do not exift in mine. One of thefe is the diffi- culty 190 OF TltE ANHYDROUS SULPHATE OF LIME. ciilty of taking out the fugar after its drainage. A fecond h, that the holes in their bottom are too fmall, which renders them liable to be obitructed, and the procefs to be greatly retarded. (To be concluded in our next*) VIII. Defer iption of the Crystalline Forms of the Anhydrous Sulphate of Lime, mthjbtne Obfervations on this Subjlance. By M. Lc Comte de Bournon, Member of the Royal and Linnaan Societies of London. Tranjlated from the Original, commu- nicated by the Author *. LUn?ain?ng°nome GrYPSOM, or the fulphate of lime deprived of water, is a water is a new new object in mineralogy : fcarcely has the fcience as yet objea in mine- caft a glance upon this fubftance, and none of its cryftalline forms have hitherto been determined. Having had opportu- nities of examining fome of thefe forms, and at the fame time of comparing a number of fpecimens of this fubftance, pro- cured from different countries, I felt myfelf induced to lay before the Public my obfervations upon this fubject, thinking they might contribute to throw fome light upon the nature of feveral (tones, with which we are not yet perfectly ac* quainted. Its primitive The primitive form of this fubftance, which has beendelig- prifm with reft- nated by the name of Anhydrous Sulphate of Lime by the angular bafes. Abbe Hauy, is a rectangular paralelopiped, as had been pre- sumed by this able mineralogift ; but it does not appear that this paralelopiped can be the perfect cube, as is indicated by the habitual form of the cryftals, which when molt fimple, is always a right prifm with rectangular bafes, having two op- pofite fides broader than the two others (Fig. 1, Plate XL), and feems equally to be indicated by the circumftances which Eafily divided, accompany this form. The mechanical divifion is very eafy upon all the faces of this cryftal ; but the longitudinal ftraight faces prefent, in this refpect, a little more refinance than the others. And a fterwards revifed by him. The OF THE ANHYDROUS SULPHATE OF LIME. 191 The broad faces, as well as thofe which terminate this fec-Luftre. tangular prifm, have generally a very brilliant luftre ; the lon->- gitudinal narrow ones faces are duller, and very frequently ftri- ated in the direction of their length. The broad fides are be- fides characterifed by a pearly reflection, fimilar to that which is peculiar to the zeolite ftilbite, and this brilliancy remains even after thofe faces have been divided : they alfo habitually exhibit the interferon ((entrecroiffement) at right angles of the joints belonging to the other faces. This cryftal prefents, along its longitudinal edges, a decreafe Secondaryforms. which replaces each of thefe fides by a plane unequally in- °«ahedral clined upon the adjacent faces : it forms with the broad fides of the prifm an angle of 130°, and of 14-0° with the narrow fides, (Fig. 2.) The prifm is therefore o&ahedral, and has four edges of 130°, and four others of 140°. Thefe new planes frequently join each other, upon the nar- Hexahedral row (ides of the prifm, and they then convert the octahedral Prlfm» into a hexahedral form, having four edges of 130°, and the two others of 100° (Fig. 3.) The pearly fides frequently then continue to be the broadeft ; in other infiances, the fix fides of the prifm are equal, or nearly equal with each other. I have not yet feen any fecondary faces placed upon the ter- minal edges. The cryftals upon which this defcription is founded are of confiderable magnitude : fome are more than an inch in length. They are of a fine flefii colour, and formed part of one of the fpecimens brought from the Tyrol, in which the anhydrous Foreign admix- fulphate of lime is mixed with muriate of foda or common '»« of muriate fait ; but as this fait is intirely foreign to it, and only inter- pofed between its parts, frequently even in a manner that is very perceptible to the eye, the form of thefe cryftals ought to be confidered as being really that of the pure anhydrous fulphate of lime. Befides, 1 have feen in Mr. Greville's ca- binet at London, a fpecimen in which this fubftance prefents exactly the fame afpeet, and the fame colour, and which at the fame time is totally defiitute of fait. In this, the anhy- drous fulphate of lime is confufedly intermingled with a&inote of a pale green colour, with fome parts of cupreous pyrites, and of the black and very magnetic oxide of iron. The loca- lity of this interefting fpecimen has not been preferved; but there is every reafon to prefume that it came from Sweden. In ]92 0F THE ANHYDROUS SULPHATE Of LIME, Groups of cry- In the Tyrolefe fpccimens, fimilar to that which afforded ftai9» the cryftals which I have juit defcribed, thefe are for the moil part ftrongly engaged and applied againit each other, eroding each other in different directions ; fome of them, how- ever, are infulated. But as many of them are united by their broad i ih or pearly faces, they have no very (hong adhefion, and it is always fufficiently eafy to feparate them with the eafily fcparated. edge of a knife. Thefe fpecimens frequently exhibit in their mafs more or lefs confiderable portions of pure common fait; feveral of their cryftals are conliderably transparent. Peculiarity. A piece of this fubftance which I procured for Mr. Chene- f hSf r afwiti- V^ for the purpofe of analyfmg it, exhibited a peculiarity mouy and which deferves to be remarked. On breaking fome of its quartz. cryftals, fmall needles of fulphuret of antimony were per- ceived within it, adhering for the moil part to fmall groups of cryftals of quartz. Not a trace of either of thefe two fub- flances was found in the other parts that were Subjected to analyiis : the tame was the cafe with the carbonate of lime, which Mr. Klaproth has indicated at Tyo- of the analyfis which he made of it, and which, undoubtedly, was likewife only an extraneous or interpofed fubftance. Quarts in an- In like manner, in the i'ione of Vulpino, obferved and de- or.hev fpecimen. ^j^j s^ accurately and carefuHy by Meffrs. Fleurieu and Bellevue, in the 2d Vol. of the journal de Phyfiquefor 1798, the anhydrous fulphate of lime is mixed with interpofed par- ticles of quartz, which, according to the analyiis made of it by Mr. Vauquelin, are in the proportion of -l^-6 to its whole mafs. I am indebted to the friendfhip of Mr. Fleurieu for two fpecimens, which prefent two diftinci varieties of this interesting flone. One of them is of a good blue colour, is partly of a very fine fandy grain, and partly coarfer and lamellated : it greatly refembies the carbonate of lime known by the name of faline marble. An immenfe number of fmall lam inas are obfervable in it, which crofs each other in different direct ions, and are found by the magnifier to be perfect ly rectangular. The other is of a darker afli coloured grey ; it is lefs pure than the former : fome portions of a true gypfeous eaith are obferved in it, containing a fmall quantity of argill and of carbonate of lime. Its fubftance is more compact than that of the ON THE ANHYDROUS SULPHATE OF LIME. \9$ the preceding fpecimen ; its lamboc are larger, their rectan- gular form is more perceptible, and feveral of them have a pearly reflection. Of two other pieces of the fame fubftance, in the cabinet of Otherfpeclmens. Mr. Greville at London, which appear to me to belong to the anhydral fulphate of lime of the falt-works in the canton of Bern, and both which are perfectly pure, the one is white with a little of a blueifh caft, the other has the fame blueifh tinge, but deeper, and greatly refembles in colour the pale blue fapphire, known by the name of water fapphire. Both have a coarfe granulated texture, and are. compofed of a com- bination of rectangular lamina, which crofs each other in dif- ferent directions, as may eafily be difcerned with the naked eye. But the laminae of that in which the blueifh colour is the molt intenfe, prefent befides fo lively a pearly reflection, that it might eafily, at firft fight, be miftaken for a mafs of zeolite ftilbite. Rectangular laminse, of fome thicknefs, may be feparated from it, which, like the cryftals before defcribed, are eafily divided in every direction. The fpecific gravity of the anhydrous fulphate of lime, Specific gravity, mixed with common fait, proved to be 2940. That of the fpecimens which I mentioned in Mr. Greville's cabinet, namely, that in which the laminae had the flrong pearly re- flection, was 29.57, and the other 2929. Of the two of Vul- pino, the moft compact was 2951, and the other 2933. The hardnefs of this fubftance, in all the fpecimens, Is fome- Hardnefs. what fuperior to that of the carbonate of lime ; in all of them alfo the anhydrous fulphate of lime is fufible by the blow-pipe without ebullition, and affords an opaque glafs. There is a marked difference between them, with refpect to phofphoref- the phofphorefcence, upon an heated fhovel. The anhydrous cence» fulphate of lime of Vulpino, gives a pretty flrong orange-co- loured light ; that mixed with common fait, affords a very faint bluifh light ; that of the falt-works of Bern, none at all j and laflly, that which I mentioned as containing actinote, with attractive oxide of iron, &c. gives a light fomewhat more red- difh than that of Vulpino. Gypfum deprived of water, or anhydrous fulphate of lime, The abfence of therefore, poffeffes characters altogether different from thofe ^ater renders of the fulphate of lime which contains that liquid; and as in altogethe/dWer- thefe two ftones the fulphuric acid and the lime exift in theent. Vol. II.— -July, 1802. O fame I9i> ON THE ANHYDROUS SULPHATE OF LIME. ftances. Arfeniates of copper. Time proportions, it cannot be doubted but that the prefence of the water totally changes the nature of the combination of acid and earth when it comes to be joined with it, which, it appears to me, can only take place (b far as this water becomes itfelf an eflential component part of theftone. Remarks In This is not the only fubftance which enables us to afcertain proof that water that the water which formerly was confidered as a part fo- is eflential to ' • , • , i« the compofition reign to the ltones which contained it, becomes m reality, m any fub- feveral of them, an ingredient eflential to their nature. The analyfis which Mr. Chenevix has made of the different fpecies of arfeniates of copper, have prefented us a ftriking example of this, efpecially in that variety of the third fpecies of my de- fcription (fee Philofophical Tranfactions, 1801) to which I have given the name of Hematiform. A movement of decom- pofition, which is confined to the gradual lofs of their confti- tuent water, totally changes the colour of thefe arfeniates, and at laft completely difcolours them, at the fame time that it ren- ders thofe that before had fome feeble tranfparency, perfectly opaque. This lofs of the water always commences at the ex- terior, and in this cafe the interior part preferves all its tranf- parency as well as its colour, whiJft the exterior part is difco- loured, and exhibits by the fhrinking of its furface, fometimes to a very confiderable degree, fenfible marks of the lofs which it has fuftained ; the water amounting to about one-fifth of its mafs *. * In my defcription of the arfeniates of copper quoted above, I have confidered this hematiform arfeniate, as well as thofe which I have deiignated by the terms of indeterminate, capillary, and ami- anthiform, only as being varieties of the fpecies in the acute octa- hedral form •- the copper and the arfenical acid are in fact contained in them in the lame proportions j but the water, which adds a new conftituent part to them, and which did not exift in thofe varieties of this third fpecies, which are in perfectly determined cryftals, forms with them a real hydrate of this third fpecies. I therefore think that it would be proper to feparate thefe varieties, in order to form with them a fifth fpecies perfectly diftinct from the third. The arfeniate of copper is one of the rood aftonifhing productions of the mineral kingdom, by the immenfity of the afpects under which it prefents itfelf, all which, neverthelels, have certainly a particular caufe, which I am very far from pretending to have afcertained. In ON THE ANHYDROUS SULPHATE OV LIME. 195 In the fame manner it is, that, in the blue carbonate of copper, Blue carbonate which, according to the inveftigations of Mr. Prouft, appears of C0PPeu to contain a contiderable quantity of water, far fuperior to that which exifts in the green carbonate, the cryftals feem to pafs, at their furface, into the ftate of green carbonate, by the mere lofs of a certain portion of their conftituent water. This fpecies of decompofition is fometimes even fo considerable in them, that it exifts, for example, amongft the fpecimens in large and fuperb cryftals which come from Siberia, cryftals, of which the form having undergone no change, belongs to the blue carbo- nate, but which have entirely paffed, throughout their whole fubftance, into the ftate of green carbonate. I am fully perfuaded, that when water is once confidered Water «s of great ii.. a. ■ • .1 />,• c importance as an and admittted as a conftituent part in the compohtion ot nu- jngredient which merous mineral fubftances, it will foon be acknowledged to modifies the pro- contribute greatly, by its prefence or its abfence, to the differ- Perties ° ence which fubfifts between feveral ftones : thus I am ftrongly inclined to believe that the carbonate of lime of flow folution, the hardnefs and fpecific gravity of which are fo much fuperior to the fame characters in the ordinary carbonate of lime, differs from this latter perhaps only by a difference in the water of compofition. Moll certainly this difference cannot proceed either from the prefence of argil, or from that of magnefia. I know fome dolomies which certainly do not contain any trace of argil, whilft, at the fame time, I know carbonates of lime, which are highly charged with magnefia, and which, never- thelefs, are very fpeedily diffolved in the acids : Of the num- ber of thefe latter are, for example, mod of the calcareous fpars with a pearly reflection and greafy afpecl. - I am much inclined alfo to think, that the fpecies of Chalce- Cacholong pro- dony, named cacholong, may owe its difference from the com- pJcu^Wpc*0pe*r, noon chalcedony only to the circumftance, that the latter con- ties to the ab- tains water of compofition of which the chacolong is deftitute ; fence of water* and that the tranfition of the chalcedony into this ftate, and fubfequently into the hydrophanes, depends, in a great meafure, upon the lofs of this water. The probability of this opinion remains to be fettled by future obfervations. O 2 IX. Awlyfis 196 ANALYSIS OF SULPHATES OF LIME. IX. Analyfis of Natural and Artificial Anhydrous Sidphate of Lime, by Rich. Chenevix, Efq. F.R.S. M.R.J, A. Communi- cated by the Author. Component parts J/HE proportion of the elements in common fulphate of of common ful- /• i i ' o i • ... phateoflime. lime, fuch as I have ftated them in the Tranta&ions ot the Royal Irifti Academy, are fomewhat different from thofe given by former chemifts. Monf. Fourcroy, in his " Syftcme " des ConnoiJJances Chimiques," and in his " Synoptic Tables/' has determined them in the following order: fulphuric acid 45, lime 32, water 22. If we deduct the quantity of water, and reduce the remainder to the quintal, we fliall have the following proportions : fulphuric acid 58,5, lime 41,5. As the object of the prefent Paper is merely the Anhydrous ful- phate, I fliall not take further notice of the quantity of water that may be contained in common fulphate of lime, whether natural or artificial. Limediflolvedin I took one hundred parts of lime, prepared with the great - and^ulphurlc e^ care> anc* diflblved them in muriatic acid. I then poured acid added, and fulphuric acid into the folution, and heated the whole in a the whole ex- p}atina crucible, at firft gently, but afterwards to violent ig- ignition, left dry nition. The augmentation of weight in the lime and the cru- fulphate of hme ciDie (which had been weighed before the operation) amount- containing 56,3 l ° ; ~ lime, and 43,6 ed to 78,5, and was combined lulphuric acid. This experi- acid. ment therefore indicates, that ftrongly calcined fulphate of lime is compofed of lime 56,3, and 43,6 of fulphuric acid. Sulphate of ba- I then took one hundred parts of calcined fulphate of lime, rytes contains an(j decompofed them by oxalic acid, to render them more 24 acid in the , *, , ' • , *• . . . . .. 100 parts. ioluble, and then dillolvea them in muriatic acid. I precipitated the folution by muriate of barytes, and ob- tained 1 82 of fulphate of barytes. Hence it is evident that 182 of fulphate of barytes, and 100 of calcined fulphate of lime contain the fame quantity of fulphuric acid = 43,6 ; which proportion gives 24 as the quantity of fulphuric acid, in 100 of fulphate of barytes. This quantity is nearly inter- mediate between that given by Thenard, and that which I had already ftated. By this experiment I eitablifhed a ftand- ard, to which I might refer every kind of fulphate of lime. 4 It ANALYSIS OP SULPHATES OF LIME. 157 It is evident that calcined fulphate of lime, or artificial an- hydrous fulphate of lime, contains 43,6 of fulphuric acid. It remains to prove its chemical identity, with the natural an- hydrous fulphate. I took one hundred parts of this fubftance, in as pure a The natural an- nate as the Count de Bournon could procure it, and fubmit j£?™\J^phate ted it to the fame experiments. I obtained from this experi- treated like the ment 187 of fulphate of barytes, which announces 44 88. I artificial, and. y. n ./,-.. r gave 44> 8 8 acid, inall never expect more uniform remits m two analyies, even of the fame fubftance, and do not hetitate to pronounce, that the two fulphates are, chemically fpeaking, one and the fame thing. The Abb6 Hauy in his late work has given the proportions Vauquelin's ex- in anhydrous fulphate of lime, according to an analyfis of Per,™ents S3^ i/r r rr i- r™ • „ , -o r , . t much more acid j Mom. Vauquehn. This excellent chemift found its elements to be nearly in the inverfe order of my ftatement, and fuch as Fourcroy has eftablifhed them for the artificial fulphate, de- ducting the water of cryftallization. I fliould ftill have doubted the accuracy of my experiments, if I had not difcovered a caufe that may explain the difference which exifts between his refults and mine. The French chemifts have mentioned two varieties of ful- mod probably phate of barytes, one of which contains 13 per cent, of ful- f~™ high^*" phuric acid, and the other 35. If therefore we eftimate the proportion of quantity of acid contained in fulphate of lime, by the fulphate ^atiofb^te's. of barytes containing 33, and not by that containing 24 per cent, we (hall have a much greater quantity of fulphuric acid, as a conftituent part of fulphate of lime. Among the fpecimens which the Count de Bournon gave Some fpecimens me for trial, there were fome which contained muriate of °f the anhy- foda. This fait was eafily extracted by water alone ; and the contained muri- proportion of it differed in different fpecimens. Klaproth had ate or"f°da » fome fpecimens in which he found carbonate of lime, and even filica. But as I have examined fome in which I can po- but it was acci- fitively affert that there was neither the one nor the other, dental* thofe fubftances may be looked upon as merely accidental. X. Abridgment J<3$ ON TANIN AND ITS SPECIES. Abridgment of a Memoir of Mr. Proust on Tanin and its. Species *, Uncertainty of A HE procefs which Mr. Prouft has given for feparating feparating 'tanin Tanin ty muriate of tin is fubjeft to confiderable uncertainty by muriate of when it is ufed, as an Englifh Chemift has lately done to fix the proportion of this principle in vegetable juices. He thinks, therefore, that it may be of utility to announce thefe caufes of error, in order that philofophers, who are engaged in this department of refearch, may place lefs confidence in it, and turn their thoughts to fome more perfect method. To thefe remarks he adds an account of certain varieties which he thinks he has perceived in the genus of Tanin. When the oxide 1. When this muriate is faturated with an aftringent juice, by the unTrTthe ** naPPens tnat; the muriatic acid takes up in folutiona portion muriatic acid of the tannate of tin, fo that what is collected on the filter re- inftead of being prefents, in truth, only a part of the tanin principle contained diflblves part of in the plant. This effect is fimilar to what happens in the. the tannate. preparation of ink, the black dye, and in every cafe where a dyeing principle can deprive an acid of the oxide which it held in folution. The affinity oft his acid not being capable of remaining inactive exerts itfelf upon the coloured oxide. This tannate When fmall dofes of alkali are added to the liquor the re* may be thrown f]Cjue 0f ^e tannate may be made to precipitate without even. down by careful ...-., r* * v •/* i • •'" •■ additionof alkali, touching the gallic acid if it be prefent ; and if this point be exceeded it may foon be perceived by the green colour which the fluid receives from contact of the air. In that cafe a few will beovearnnatCdroPs of acid wiH be fufficient to difPeI the cloud by'feizing charged with the excefs of alkali and fetting the gallic acid at liberty. But oxide if too as^ on ^e 0ther part, it is neceflary at firft to employ an ex- much of the _ ._ . * , . ." . ~ , . Z v , , muriate has been ce*s °* muriate to allure the precipitation or the whole of the ufed. tanin, there is danger of loading the tannate with a certain excefs of oxide of tin. The muriate 2. The prefence of tanin does not exclude the extractive precipitate* ex- principle in the juice of a plant, and as the muriate precipitates and perhapsother this laft as well as the former, the extractive principle will principles along therefore become a new fource of miftake in the eftimate of with the tanin. * From the Annalcs de Chemie XLII. 89. the OT TANIN AND ITS SPECIES. J99 tfie quantity of tanin. It may alfo happen that the vegetable juices may contain many other fubftances capable of decom- pofing the muriate either direclly or indirectly, fo that this re-agent can never be depended upon with confidence. There are befides earthy falts in thefe juices as Vauquelin When earthy has fliewa, Some, as for example Sumac contain fulphate of vae*gt"jf '"^ lime in abundance. If therefore we ufe the alkali to complete will Jet fall their the reparation of the tannate, the precipitate will alfo be kfes when the r \ r r alkali 1S addcd. charged with an earthy depofition. 3. On reflecting upon the means of avoiding the errors caufed If the pure maxi- by the muriatic acid, Mr. Prouft tried a procefs which he had ™%£££eof da fuccefsfully ufed to feparate the colouring principle from the agitated with gelatinous mucilage which accompanies it in cochineal. It F|°[*" com"' confifts in heating, or even limply agitating, the aftringent piace and> mu_ juice with the oxide of tin prepared by nitric acid, and kept cilage, if prefent, under water. The oxide in fact, becomes loaded with tanin in a few days. But if the juice of a plant which is not aftrin- but this proeefa gent, or a diluted extrad, be treated in the fame manner, it ^eextf^T will alfo become deprived of the whole of its extractive matter : matter, and the gum and the fait will remain alone in the fluid. This method cannot therefore lead us to our object. 4. What appears moft furprifing to this chemift in the pre^ Singular event fent experiment is the destruction of the gallic acid, or pro- l,"^^ e ^j, bably its transition into a State in which it cannot perform the gallic acid is d*. fundions of that acid. The fluid in fad when cleared of the ftr°yed' tannated oxide by the filter has no longer either colour or taSte, and makes not the Slightest impreffion on the folutions of iron, nor even upon turnfol. When examined by every trial the fluid is found to be mere water. $. Sufpecting, neverthelefs, that this acid might be com- When the tanatc bined with the oxide of tin, he patted the tannate of the laSt conJ2Jj £y defcribed procefs into potafh. The product was a coloured potato no gallic fluid, in which he found no fign of the gallic acid : for it did™d^fo™dof not afTume by expofure to the air that green (hade which it tanin. always indicates when faturated with an alkali. He pre- cipitated the tanin by a diluted acid, a portion remaining in folution, as happens in this cafe and he proceeded to examine that which remained upon the filter ; but he foon perceived that it had alfo advanced towards a Mate in which, a_s we (hall fhew, he found infinitely lefs tanin than before, C Boiling OOO ON TANIN AND ITS SPECIES. Thetanin that &• Boiling water cannot totally dilTolve it. Its folution no is feparated is longer precipitates glue; it has neither the harfli tafle nor the not totally folu- , . . . . ble in boiling odour of tanin. With the red fulphate of iron it affords only waterj neither a whitifh grey precipitate, and laflly it does not afford a does it precip.tate ..? .f • . c .. .. . ... . , , . glue, nor has it magroa with the muriate or tin; it is precipitated merely in the tafte or fmell the manner of extracts, to the tafle of which it in fome meafure It refembles'ex- aPProacnes though it does not poflefs their bittemefs. Thefe traces. are the alterations to which the taning principle is fubject when combined as before mentioned with tin oxided to the maximum. It was fufpecled 7. From thefe changes he fufpecled that the tin might have Silken ox\%n }'ieldecl t0 lt that Portion °^ oxigen which conflitutes the from the oxide ; difference between the oxide at the maximum and the oxide but experiments at tne minimum, as happens with the oxide of iron in ink, nor feem toindi- hermetically clofed. In order to afcertain this he diffolved in cate this lofs. muriatic acid the oxide what had been deprived of tanin by potafh ; but he difcovered no indication of that kind. The folution produced no change in that of gold, nor in corrolive fublimate. It was at the maximum* It is true that with re- fpedt to the oxide of tin at the minimum, as well as that of iron, warning and'expofing to the air fpeedily bring it to the maximum. Theory of this Whether by oxidation or by whatever other procefs, the converfion yet tanin principle did at length pafs to the flate of ordinary ex- tract. Tanin precipitates glue, but extra6t does not; this is the difference between them, The influence of fome affinity, which the author has not fufficiently developed, muff have changed its radicals in their primordial arrangements or in their proportions ; and it may be fuppofed that the gallic acid like wife after having been fubje&ed to thefe changes became aflimilated in trie fame Hate and by the fame caufes. Concerning the Varieties of Tanin. The genus tan'm If in the feries of immediate principles which compofe the compofed of wnole of vegetable matter we confider the tanin of galls as a genus, becaufethis in fact poffeffes the qualities in the higheft degree, it is eaiv o form a notion that this genus may have its fpecies, and may, as well as fugar, gum, ftarch, &c. affect different modifications. There are various fjecies of fugar, refin, gum &c, and there may be alfo various fpecies of tanin. Mr. Prouft thinks that he has found this to be the cafe. Cachou ON TANIN AND ITS SPECIES. 201 Caelum, or Terrajaponica. Cachou is an aftringent : it is foluble in alcohol and Qualities of the in water. It precipitates glue abundantly and forms with itof^anin/ a vinous (q.) magma which has neither the confidence nor Cachou or Terra the infolubility of the tannate of galls. japonica. It reduces muriate of gold, it precipitates the muriate of tin and affords a violet coloured ink with red fulphate of iron. It is a tamnfui generis. It dyes filk. Dragons Blood. That which is pure and comes to us in calebafhes is foluble Dragon's Blood, both in water and in alcohol ; its tafte is harth ; it dyes filk of a bad wine colour. It abundantly precipitates glue, the muriate of tin, the red fulphate, and difoxides gold ; it is alfo a fpecies of tanin. Sumach. The tanin which this fubftance contains, abundantly pre- Sumach* cipitates glue, and affords a white magma without confidence. Like tanin it is feparated from the decoction of fumach by the carbonate of potafh ; its curdled depofition is again foluble in hot water with the exception of a fmall quantity of chalk. Barites and the oxalic acid demonftrate the exiflence of abundance of lime and fulphuric acid ; but it will be neceflary to afcertain by experiments On the green fumach whether fulphate of lime be one of its principles, or an adulteration. The author is not furprifed at finding it, lince he obtained this fait in confiderable quantity from the juice of cabbage, and of folanum lycoperficon, which is cultivated in the gardens under the name of Iomates. This juice alfo contains gallic acid ; it becomes green in the air when faturated with potafh. It reduces gold, decompofes muriate of tin and the red ful- phate, with which it affords a thick ink. Yellow Wood, or Fuflic. It contains a fpecies of tanin. Like tanin it precipitates Yellow wood or the folution of glue ; a folution of fait is fufficient to precipi*tu*rtlc* tate it. It is foluble in water and in alcohol. It reduces gold, decompofes muriate of tin and the red fulphate, by means of which it dyes filk of a greyifh yellow. Fujict }202 «N' TANIN AND ITS SPECIES. Fujlet. Fuftet, It is a pure dyeing extract foluble in water as well as in af- cohol. It contains a fmall quantity of gallic acid, but does not change the folution of glue. It reduces gold, precipi-. tates the metallic falts, and has no gummy portion. Grains of Avignon, or French Berries. Gr. d'Avignon, They afford a dyeing extract of the fame nature, without ma. '" £um or tamn« J1 reduces gold, &c. Brazil Wood, Braxll wood. Affords alfo a dyeing extract foluble in alcohol without tanin, or gum, reducing gold and precipitating the metallic falts. Rrduaion of Mr. Proufl has remarked, that the reduction of gold has five ch£#erof ceafed to be a chara«eriftic quality, fince he obferved the tanin. muriatic folution abandpn this metal tp all the tinging fub- fiances, fuch as anjfe, cochineal, gum guttae, gallic acid, verjuice, wine, vinegar, the juice of all fruits, manna, gum, and fugar, though fqmewhat flowly. Concluding ob- The author concludes by ohferving, that tanin has its va-, rieties }ike the other immediate products; that the property of precipitating glue is the generic indication, by which they are diflinguifhed from extracts, which do not alter that tub- fiance ; and laftly, that the different fpecies of tanin, parr Tan'mg matters ticularly thofe which have been difcovered in the barks of re?"!rf t0 *' trees, cannot be compared together as to their force and their preparation of ufeful qualities, but by obfervations upon fkins which have leather. been fubmitted to their action. Sulphate of lime Note. Plafter mufl be infinitely common in vegetables. VCry CbiT,r°n ^ ^r* ^rou^ bas found it in verjuice, grapes, apples, goofe. berries, &c. B. L. XI. Dcfcription APPARATUS FOR HEATING WATER, 2Q3 XI. ftefci'iption of an Apparatus for healing Water hj ivajle Steam* Invented by Mr. Arthur Woo l f . A HE following apparatus was ere&ed at the extend ve Engine for heat, brewery of Meffirs. Meux and Co. in Auguft, 1800, and has ^f" hy been in ufe ever fince. I law it work a few weeks ago, and obferved with great pleafure the facility and precifion with which it operates, and I have .great fatisfaction in prefenting it to the reader as a very judicious and ufeful combination. Plate IX. A reprefents a fteam pipe from the brewing Particular de- copper, fcription. B a valve with its weight. C the veflel in which the fteam is condenfed. D a pipe that conveys the cold water from a refervoir. E a conical valve through which the water is injected. It is connected with the lever F. G is a bended pipe to prevent any of the fteam from efcap- ing with the hot water. H a fmall receiver from which the hot water may be con- veyed to different fituations by means of pipes and cocks. I a pipe open to the receiver to prevent a vacuum in cafe the water fliould be made to defcend in any of the pipes. K a fmall pipe to convey the fteam into the regulator. L the regulator which is compofed of three cylinders, the outfide and infide being clofed together at bottom, leaving a cavity between, which is filled with water ; the middle or moving cylinder is inverted and clofe at top. It fcrves for a pifton, and is connected to the lever M, on which is a Aiding weight N, by which the quantity and heat of the water may be varied at pleafure. O is a valve through which the fteam is let out when not iifed for heating water. TJm effect of this engine may be eafily underftood. The Explanation ofj weight of the inverted hollow pifton L pretfes down the valve the manner in r> i V i t i i • >• i , which it acls. L by means ol the levers, and this preilure may be regulated by fixing the weight N nearer or farther from the centre of the upper lever. When the fteam through A has acquired a cer- tain degree of ftrength in the veifel C, it raifes the pifton by its action through K, and confequently opens the valve E. A fheet of water immediately dalhes throngh, as reprefented 3 in 20& IMPROVED LOCK TOR HOUSE DOORS. in the figure, and by condenfing the fleam, fufFers L again to defcend ; and, after a vibration or two, the effect of the fleam to raife the pifton and of the inje&ion to deprefs it, balance each other, i'o that the levers remain nearly motionlefs. It is evident that the injeclion will be lefs, the fleam flronger, and the water which pafTes off through G hotter the nearer the weight M is to the centre of motion. And in this refpect the apparatus is fo effectual that the water may be heated to 210 degrees, and the quantity that pafles off is from 100 to 180 barrels per hour, according to the temperature, as governed by the pofition of the weight M. XII. Dejrription of an improved Drawback Lock for Houfe Doors. By Mr. Wm. Bullock. From the Tranfaclions of t/te Society of Art*, zcho adjudged a Reward of Fifteen Guineas to the; Inventor. Copy of a Letter to the Secretary of the Society Mr. Charles Taylor. SIR, Inconveniences } HAVE herewith fent, for the infpecVion of the Society, an the common improved Drawback Lock for Houfe Doors, &c. which im- drawback. lock, provement is in latching the door ; for it is well known, par- ticularly in damp weather, that the air drawing through it, rufls the head or bevel of the bolt, by which means it requires great force to fhut the door, and occafions a difagreeable noifc, betides fliaking the building. It has frequently happened that the houfe has been expofed to robbery from the door being left unlatched, when fuppofed to be fail. This improvement removes all thofe inconveni- ences, as it lets the bolt flioot into the ftaple immediately when the door clofes, but not before ; and the reliever works fo very cafy, that the door is made fall with one twenty- fourth part of the force requirecLwith locks upon the common conflruclion. By IMPROVED LOCK FOR HOUSE DOORS^ 20o> By an experiment with the lock fent herewith, it will be Advantages of proved that two ounces added to the reliever, wiil ihoot the the improved lock with more eafe than three pounds will do, applied to (he bevel bolt ; and if the lock is rufty, the advantage will be much more in favour of the new method. I natter myfelf it will be of great utility to the public, as its conftruclion is fim- ple and cheap. It may be added to any old lock, as may be feen from that now fent. It may be advantageoully applied to French windows and glafs doors, as it prevents the door from being drained, or the glafs broke, by the force applied to (hut them. I have fixed feveral locks, upon this new prin- ciple, which anfwer well ; and if the invention meets with the approbation of the Society, I hope to be rewarded ac- cording to its merit. I remain, with refpect, , SIR, Your mbft obedient Servant, WILLIAM BULLOCK. No. 6, Portland Street, Soho, May 5, 1801, Plate X. Fig. 2. A. Is the new iron latch here affixed to Defcription , an old common drawback houfe lock. B. An iron pin at one end of the latch, on which pin it is moveable. C. A projecting part of the latch, which, when the com- mon fpring bolt D of the lock is drawn back, in the ufual manner, is forced into the nick on its higher part at E, by the fpring F, underneath the latch. The bolt D then remains within the lock, until, on clofing the door, the reliever G gently prefles on the lock box, fixed in the common way on the door cheek ; which preflure draws the projecting part C out of the nick E, and permits the end of the bolt D, by the force of the fpring G, to Hide into the lock box, and fatten the door. XIII. Ptfcripiion <2Q6 DESCRIPTION 01^*Atf IMPROVED MlHi XIII. description of an improved Mill for grinding hard Suhfiances. By Mr. Garnett Terry, from the Tranfaciions of the Society of Arts, who adjudged the Silver Medal to the Inventor. Fn SProved°f ^R* Teri> wh°fe refidence is No- 20* City Road> Finf- mill. ^ury Square, has conftructed this mill on a large fcale, and there is alfo a model deposited in the Society's collection. Plate X. Fig. 1. A. The hopper, or receptacle of the articles which are intended to be ground. B* A fpirai wire, in the form of a reverfed cone, to regu- late the delivery of them. C. An inclined iron plate, hung upon a pin on its higher end : the lower end refts on the grooved axis D, and agitates the wire B. D. The grooved axis, or grinding cylinder, which acts againft the channelled iron plate E. F. A fcrew on the fide of the mill, by means of which the iron plate E is brought nearer to or removed further from the axis D, according as the article is wanted finer or coarfer. G. The handle, by which motion is given to the axis. H. The tube from whence the articles, when ground, are received. %* The front of the mill is taken off, in order to fliow its interior conftruction. XIV. Remarks on. Dr. Thomfon's Theory of Combajlion. By C. i?. (Received June 15, 1802.> General remarks JL HE fcientific world are fo highly indebted to Dr. Thom- fon's Vheorv"1" ^on ^or manv original communications, and for the very per- and the diftinc- fpicuous manner in which he has explained many of the phe- ti on between nomena of chemiirry, that every thing that is prefented to the combufhon and . J_. . * . . . , , •xigenation. world under the ianction of his name, is intitled to much con- fideration : if in ibme inftances we are induced to hefitate in the yielding of our aflent, we cannot but do juftice to the in- genuity of his reafonings, and at the fame time acknowledge the ON THE THEORY OF COMBUSTION* £07 the very luminous manner in which he conveys information, en every fubject that he treats. , The Paper under con fidera* tion is particularly an inftance in point, and if we cannot go the full length with the author, we mutt at leaft acknowledge, that in the chief, his diftinctions are accurate, and his reafon- ing juft. Nothing can be more evident than the difference which in numberlefs inftances prevails, between the act of oxigenation in bodies, and that of combuftion, inafmuch as neither the phenomena attending them, nor the refults ari- fing therefrom, are the fame. The French chemifts, how- ever, feem to have been miffed, in their confining the term combuffion to the act of oxigenation, by conlidering, that all bodies during their combuffion combine with oxigen, without at the fame time recollecting, that this latter effect may be produced without any of the phenomena ufually attendant on combuftion, and that though certainly all combuffion prefup- pofes the combination of oxigen with a bafe, yet this combi- nation may, and repeatedly is effected where no combuftion can poflibly take place. That a diftinction therefore prevails between the two is ob- vious, and the Doctor offers us a theory, which he confiders as fufficient to explain the different phaenomena produced. — This theory it is the purpofe of the following lines to fliew however ingenious, aud apparently falisfactory it may appear to be, is not wholly adequate to Ihe talk that is affigned to it. It will be neceffary very fhortly to ftate here the outline of the Outline of the theory under confideration. In all cales fays Dr. Thomfon *, Jeof.y*t T!?at when heat and light are extricated during combuftion, it will combuftion is be found, that the light is furniihed by the combuftible or ■fi»«ufl>ejl by the burning body, and the heat by the decompofition of the oxi- and the 'h^ \* gen, which forms a component part of the fupporter, and the oxi-en of which is effential to the combuftion, and that the diftinction uppor that prevails between the two proceffes of combuftion, and of oxigenation, arifes from the difference of the phaenomena, which accompany the action of iupporters and products upon other combuftibles. " The iupporters convert thefe bodies but that produces into products, and combuftion, -or the emiffion of heat and co"ver.c combuf" ..«,/. tibles into pro- bght at the fame time take place ; whereas, the products con- duels by mere ox- vert combuftibles into products, without any fuch emiffion. kenftwn ™Mout copibuftiort, * Fhilof. Journal, New Series, II. 10 and 92. Now 1208 0N THE THEORY OF COMBUSTION. Now as the ultimate change produced on combuftibles by both thefe fets of bodies is the fame, and as the fubftance which combines with the combuftible is the fame, namely oxi- gen, it is evident, that the oxigen of the fupporters contains fomething, which the oxigen of the produces wants," and this fomething the Do&or fuppofes to be caloric. " In the fame manner the combuftibles and products referable each other, the chief difference between them conn* fling, in the phenomena which accompany their combination with oxigen, in the one cafe fire is emitted, and in the other not." Now fays the Doctor, " if we recollect, that no fubftance but a combuftible is capable of reftoring combuftion to the bafe of a product, and that at the time of its doing fo, it always lofes its own combuftibility, and further, that the bafe of a product does not exhibit the phenomena of combuftion even when it combines with oxigen, we cannot avoid concluding that all combuftibles contain an ingredient, which they lofe when converted into products, and that this lofs contributes to the fire, which makes its appearance during the converfion." This ingre- Leading pofitfons dient the Doctor fuppofes to be light. It is evident, that the i! thltligh^'s tvvo leadi"g pofitions of this theory are, 1 . That during com- originally an in- buftion, all combuftibles emit light, which previoufly formed buftbl11 °f C°m" a ncce^rJ ingredient to their own compofition ; and fecondly, and heat of oxi- That the heat which is evolved during the procefs of combuf- £en« tion, proceeds from the oxigen of the fupporter, of which it Many reafons likewife originally formed an efTential ingredient.— That the muVco hCfC ^eat g*ven out during combuftion comes from the decompofi- the oxigen of the ti°n of the oxigen of the fupporter, there are many reafons for fupporter. concluding. We know very well that no combuftion will take place without the prefence of oxigen, and that the greater the quantity of oxigen abforbed in a given time, the greater is always the heat that is evolved. Now if the heat be not fup- pofed to come from the oxigen, why fhould the degree of heat given out, be always proportional to the quantity of oxigen that is abforbed, and upon what other principle can we fo fatisfactorily explain the effects that are produced by the Argand lamp. Thefe confiderations, combined with the argument drawn from the maintenance of the temperature of hot blooded animals by the decompofition of air, feem fuffieiently to efta- Difficultics as to blifh the truth of the foregoing pofition. There arc, however, t!on0tthr Ptlfl~ man^ difficulties tnat Pre^s againft our implicit adoption, of the light invariably Other ON THE THEORY OF COMBUSTION. 209 other part of this theory, viz. that the light emitted during proceeds from combuftion invariably proceeds from the burning body, and the burning that confequently it forms no part of the fupporter. It of courfe then follows from this theory, that light is no eflential part in the compofition of oxigen gas. Let us however fee whether this be the cafe. Many fafts it will be found concur to prove that the contrary is the truth. If nitric acid be ex- pofed to the light, after fome time we find that it changes colour, it becomes yellow, green, and then red, and oxigen gas is difengaged, the nitric at the fame time being converted into nitrous acid. Now it is evident, that as this decompo- for the light fition is of a chemical nature, the light that occafions it, ei- whjch decom- i , • . , , n • .lL pofes nitric or ther combines with the oxigen to form oxigen gas, or with ox# mim ac;d i3 the acid to form nitrous acid : as we find no diffimilarity be- concluded to tween the nitrous acid procured by this means, or that by any wjththe difen- other, we are neceflitated to conclude that the light has com- gaged oxigen* bined with the Oxigen, and that the latter by the fame means is converted into, oxigen gas. Again, it is well known, if oxigenated muriatic acid be expofed to the rays of the fun in a tranfparent bottle, there is difengaged from it oxigen gas * in proportion as the gas is feparated the acid lofes its colour and odour, and returns to the ftate of fimple muriatic acid. — Here it is evident, that the oxigen has paned from a concrete into a gafeous ftate from the combination of light, and we muft therefore conclude that light is a component part of oxigen gas. Ifphofphorus be inferted in nitric acid, the latter is de- when phofpho- compofed, and a product of combuftion, namely phofphoric rus lsac,dlfiedm • , . ,. II- i-i r • i 1 i-i nitrous aciJ, acid is formed, during which procels neither heat nor light wriat becomes of are given out. This procefs Dr. Thomfon confiders as an the light of the act of oxigenation, and not of combuftion, becaufe, fays he, though a product of combuftion is formed, a new fupporter, namely nitrous gas is evolved, and the formation of a combuf- tible, or new fupporter, conftitutes one of the characleriftic differences between the two procehes of combuftion and oxi- genation. Now it is faid, that in all cafes of oxigenation a double decompofition takes place, the oxigen of the product combines with the bale of the combuftible, while the light of the combuftible combines with the bafe of the product. The queftion then naturally prefents itfelf,—- what during this procefs becomes of the light which made a component part of the Vol II. —July, 1802. P phofphorus 210 W THE THEORY OF C0.KBl7STrotf . phofphorus previous to its conversion into a product ? It can- not combine with the new fupporter that is evolved, becaufe it is a part of this theory, that light is no conflituent part of fupporters, but only of combuftibles ; it fhould therefore have been made evident to the fenfes, which we do not ever find to be the cafe, nor is any heat evolved ; this latter effect is no doubt very eafily explained, but what becomes of the light yet remains to be (hewn. Sulphurous and Sulphuric acid, fays Dr. Thomfon, is a fubftance which fulphuric acids, from many of its properties I conclude to be a combuftible, and not a product. This conclufion, however, does not ap- pear to be perfectly confiftent with the definition the Doctor has given of combuftion, for when fulphur is heated in the air to the temperature of 302 degrees, it gives out light and heat, and is converted into an acid, viz. fulphurous acid : this ac- cording to the theory under consideration is a complete act of combuftion, and therefore only a product of combuftion, and not a combuftible body ought to be formed. Sulphurous acid, according to La Grange, combines flowly with oxigen, and is converted into fulphuric acid, but as no light and heat are rendered vifible, ought it not in this cafe rather to be confi- dered as an act of oxigenation ; for if light and heat were evolved in this procefs, it fhould appear that combuftibles are capable of giving out a part only of their light in fome cafes, arid the whole in others, which does not appear very proba- ble, for it cannot be doubted but that in fulphurous acid, the oxigen and the fulphur mutually faturate each other, and that fulphuric acid is only fulphurous acid combined with an addi- Dceompofition tional dofe of oxigen. Though the Doctor apparently recon- . of water by iron cjjes tiiC decompc.fition of water by iron or zinc with his the- ory, it yet appears to be atte$d$j$ with fome difficulties which are not eafily explained. — " Whenever, fays he, the whole of the oxigen is abftracted from products, the combuftibility of their bafe is reftored as completely as before combuftion, but no fubftance is capable of abftracting the whole of the oxigen from fuch products, except a combuftible, or partial combuf- tible. Water, for inftance, is a product of combuftion whofe bafe is hidrogen ; to reftore the combuftibility of the hidrogen, we have only to mix water with iron or zinc filings, when the metal is oxidated, and the hidrogen gas is evolved as com- buftible as ever." Let us here attend to the phenomena which ok THE THEORY OF COMBUST ION". '211 Which mould take place according to the Doctor's theory; water, which is a product of cbmbuftion, is hidrogen without Numerically its light, in union with oxigen, without its heat ; by adding ™" ^fitton of iron (a combuftible containing light) we decompofe the water, precifely ade- that is to fay, 73 parts of iron unite with 27 of oxigen. Now jKC{^^f as to every 27 parts of oxigen in water there are about four buftible to com- ofhidrogen, ofcourfe thefe four parts of hidrogen are libe- buftible, &c rated ; but as it does not appear probable that combuftibles fliould be capable of combining with light in all proportions, it may be aiked> if the 73 parts of iron which are oxidated contain juft light enough, and no more, to reftore the com- buftibility of the four parts of hidrogen ; for if there be too much for that purpofe, the fuperabundant quantity ought td become vifible, and if too little, a part only of the hidrogen fhould recover its combuitibility, and be converted into gas. And the fame reafoning may of courfe be urged with regard to the deeompofition of water by zinc : for it cannot but be acknowledged, that the fact is fomewhat fingular, that the product of combuftion mould always contain and give out the precife quantity of light which is fufficient to reftore combuf- tibility to the bafe of the product, and in no cafe either more or lefs. Thus it appears that there are many difficulties that Conclufion. attend our implicit affent fo the prefent theory, and many of the phenomena of combuftion that do not apparently admit from it of an eafy interpretation. Whether Dr Thomfoh can reconcile thefe apparent anomalies to it, remains to be feen 5 but if it is found equal to their folution, there, could then it fhould feem be little objection to its adoption. At all events, Dr.T. has ho one will be inclined to difpute, that the Doctor has *™wn Sr*at > thrown much light on a fubject> which before its inveftigation fcure fubjeft, by him, was considerably more obfcure: and that he has placed it in a new point of view, which bids fair to enable us to approximate much nearer to a true theory with regard to the phenomena of combuftion, than any other that has hi- therto prevailed. G. P.- tf£ XV, On 212 ON CERTAIN POINTS OF NOMENCLATURE. XV. On certain Points of Nomenclature. By a Correfpondent* To Mr. NICHOLSON. SIR, fnlfoKh?* APPREHENDING that your mode of writing certain the Greek newly impofed names of fubftances in chemiftry, arifes from Vowel v. inattention, and being milled by the French, I take the liberty of a friend to remind you, that, in Engliih, it is not ufual to write the vowel i for the v of the Greeks, but y ; hence, in our language, we do not write oxfgen, hydrogen, oxz'genifed, &c. but oxygen, hydrogen, oxygenited, &c. : you write, how- ever, properly, oxz'de inftead of oxj/d, as fome perfons fpell the word ; becaule ox/de fhews the etymology in ofa and e»3os better than oxz'de. Your's ever faithfully, A. B. C. ANSWER, I DO not profefs to have directed much attention to the fub- ject of nomenclature; though I am well aware of its impor- tance to the acquifition, as well as the communication of knowledge. It is, therefore, with confiderable diffidence that I ftate my apprehenfion, that neither ufage in a language, nor the motive of precifely indicating the derivation of a term, are very cogent arguments for adopting any particular mode of ftructure, if other motives prefent themfelves. To me it feem- ed at leaft as forcible a reafon for the ufe of i inftead of^, in the words alluded to, that, together with their derivatives, they are fo very numerous, as to make it defirable to accommodate them to the general ufage of the modern languages ; and this appeared to be promoted by following the change propofed by the framers of the chemical nomenclature. XVI. Duplicate ON THE NEW PLANETS CERES AND PALLAS. 213 XVI. Duplicate Copy of a Letter from Baron de Zach d Decl. Palla* ON THE NEW PLANETS CERES AND PALLAS. 215 Pallas and Ceres are now too near to the fun, and the twi- Thefe planets light permits no meridian obfervations. But aftronomers who twjU . u are provided with equatorials of great perfection, as, for in- ftance, thofe of Greenwich, Oxford, Richmond, and of Sir George Shuckburg, will be able to follow thefe two planets a longer time. The obfervation of Pallas will chiefly be of a very great value, as the feries of meridian obfervations is not for above five weeks. If more obfervations are not procured, it will be with fome difficulty we (hall find Pallas again next year ; for the elements of an orbit calculated upon fo fmall an arc as 7|°, may give an error of feveral degrees in January 1803. You will do, molt honoured Sir, a great benefit to icience in general, and to aftronomy in particular, if you en~ gage the Englifli aftronomers, who have fo very excellent and fixed equatorial feclors, to follow Pallas out of the meridian as far as they can. For this purpofe, I take the liberty to fend you here an ephemeris of this planet's motion, calculated by Mr. Gaufs, which will enable aftronomers to find it, and pur- fue their obfervations. Ephemeris of the Pofition of Pallas for Midniglit, in Seeberg Ephemeris of Obfervatory. *aUas« 180*. R. Afcenf. Dectfn. May 24 181° 57' 21° 1' N. 27 182 18 21 0 30 182 41 20 57 June 2 183 6 20 52 5 183 34 20 46 8 184 5 20 38 11 184 37 20 28 J4 185 12 20 17 17 185 48 20 5 20 186 27 19 52 23 187 7 19 37 26 187 49 19 22 29 188 32 19 6 I am, with the greateft efteem and regard, MOST HONpUKED SIR, Your moft humble and obedient fervant, FRANCIS BARON DE ZACH. XVII. Method 215 ON STONY AND METALLrNE SUBSTANCES XVII. Method of applying a temporary Forcer to a Pump, fo as to pro- duce a conftant Stream. By Mr. Richard Trevithick *'. From the Author. Additional forcer JL HIS contrivance which, on feveral occafions, may prove pumpOIproducing u^eU1^ confifts in fixing a barrel with a folid pifton alongfide a conftant of the common pump, in fuch a manner, that the lower fpace ftream. Qf ^e additional barrel may communicate with the fpace be- tween the two valves of the pump, and laftly, by connecting Defcription. the rotjs f0 that they may work together. This is (hewn in f\g. 4, plate XI. and the effect is, that when the piftons are raifed, the fpaces beneath, A and B, become filled by the preffure of the atmofphere, at the fame time that the upper column flows out atE. But again, when the piftons defcend, the valve C fhuts, and, confequently, the water driven by the pifton in B muft afcend through A, and continue to produce an equal difcharge through E in the down ftroke. XVIII. Experiments and Obfervations on certain fiony and metalline Subftances, which at different Times are /aid to have fallen on the Earth ; alfo on various Kinds of native Iron. By Edward Howard, Efa. F. R. S. From the Philofophical Tranfaclions, 1802. Stony and J[ jjg concordance of a variety of facts feems to render it ftances havcun- rnoft indifputable, that certain ftony and metalline fubftances doubtedly fallen have, at different periods fallen on the earth. Whence their origin, or whence they came, is yet, in my judgment, involved in complete obfcurity. The accounts of thefe peculiar Subftances, in the early annals, even of the Royal Society, have unfortunately been blended with relations which we now confider as fabulous ; and the more ancient hiftories of flones fallen from heaven, * This Gentleman's name was, by miflake, printed Trevithack, in Vol. I. 161. from FALLEN ON THE EARTH, <2\1 from Jupiter, or from the clouds, have evidently confounded fuch fubflances with what have been termed Ceraimia, Why thefe fa£U Bxtilia, Ombria, Brontia, &c. names altogether unappro- have : b"n dl*" priate to fubflances fallen on our globe. Indeed fome miflead, and others are inexpreilive. The term Ceraunia, by a mifnomer, deduced from its fup- pofed origin, teems, as well as Bcetilia *, to have been an- ciently ufed to denote many fpecies of Hones, which were polifhed and fhaped into various forms, though moftly wedge- like or triangular, fometimes as inflruments, fometimes as oracles, and fometimes as deities. The import of the names, Ombria, Brontia, &c. feems fubject to the fame uncertainty. In very early ages, it was believed, that Hones did in reality, fall, as it was faid, from heaven, or from the gods ; thefe, either from ignorance, or perhaps from fuperflitious views, were confounded with other flones, which, by their compact aggregation, were better calculated to be fhaped into different inftruments, and to which it was convenient to attach a fpecies of myfterious veneration. In modern days, Thunderbolt. becaufe expiofion and report have generally accompanied the defcent of fuch fubflances, the name of thunderbolt, or thunderflone, has ignorantly attached itfelf to them ; and, becaufe a variety of fubflances accidentally prefent, near buildings and trees flruck with lightening, have, with the fame ignorance, been collected as thunderbolts, the thunder- bolt and the fallen metalline fubftance have been ranked in the fame clafs of abfurdity. Certainly, fince the phenomena of lightening and electricity have been fo well identified, the idea of a thunderbolt is ridiculous. But the exiflence of peculiar fubflances fallen on the earth, I cannot hefitate to affert : and on the concordance of remote and authenticated facts, I fhall refl the affertion. Mr. King, the learned author of Remarks concerning Stones Ancient author?. faid to have fallen from the Clouds, in thefe Dam and in ancient Ve,fot fto"es „,. , 11. • r i n fallen on the Times, has adduced quotations of the greateft antiquity, de- earth. King fcriptive of the defcent of fallen flones ; and, could it be Faico«et> &c. thought neceffary to add antique teflimonies to thofe infianced by fo profound an antiquarian, the quotations of Mons. Fal- conet, in his papers upon Boetilia, inferted in the Hifloire des Infcriptions et Belles- Lettres ;\ the quotations in Zahn's * Mercati, Metallotheca Vaticana. page 241.. f Tom. VI. P. 519. etTom. XXHI. P. 228. fpecufo 2IS oyr STONY AND METALLINE SUBSTANCES Specula Phgfico-mathematica Iliftoriana ;* the Fifica Sotterranea of Giacinto Gemma ; the works of Pliny, and others might be referred to. Dr. Chaldni on Doctor Chaldni, in his Obfercatiom on the Mafs of Iron the Siberian hoaj-omd ,-„ Siberia, and ou other Mafes of the like kind, as well as in his Obfervations on Fire-balls and hard Bodies fallen from the Atmnfpherc, has collected almoft every modern inftance of phenomena of this nature. M« Southey a Mr. South ey relates an account, juridically authenticated, tfone wt. 0j- a ftone weighing 10 lb. which was heard to fall in Portugal, Feb 19, 1796, and was taken, ftill warm, from the ground. f Abbe Bachelay The firft of thefe peculiar fubftances with which chemiftry ?768» has interfered, was the ftone prefentedby the Abbe" Bachelay to the Royal French Academy. It was found on the 13th of September, 1768, yet hot, by perfons who faw it fall. It is defcribed as follows : " La fubftance de cette pierre eft d'un gris cendre* pale ; P lorfqu'on en regarde le grain a la loupe, on appereoit que f« cette pierre eft parfem£e d'une infinite de petits points bril- f Jans metelliques, d'un jaune pale ; fa furface exterieiire, " celle qui, fuivant M. PAbbe Bachelay, n'etoit point en- " gag£e dans la terre, etoit couverte d'une petite couche tres- " mince d'une matiere noire, bourfoufflee dans des endroits, " et qui paroiffoit avoir ete fondue. Cette pierre, frappee •f dans Pinterieur avec Pacier, ne donnoit aucune etincelle ; U ft on frappoit, au contraire, fur la petite couche exterieure, £< qui paroiflbit avoir £te attaquee par le feu, on parvenoit " a en tirer que'ques-unes." The fpecific gravity of this ftonewas as 3535 to 1000. Analyzed. The academicians analyzed the ftone and found it to con- tain. Sulphur - - - - 8| Iron , 36 Verifiable earth 55% 100. * Fol. 1696, Vol. I. p. 385. where a long enumeration of ftone» fallen from the flcy is given. + Letters written during a fliort refideuce in Spain and Portugal,, p. 239. Of FALLEN ON THE EA"RTH. 219 Gf their mode of analyfis, I (hall have occafion to fpeak Conjeaure thai hereafter. They were induced to conclude, that the ftone, [f miSht. hava •' been pyrites, prefented to the Academy by the Abbe Bachelay, did not ftruck in pre- own its origin to thunder : that it did not fall from heaven ; *e«-ence by light- that it was not formed by mineral fubftances fufed by light- ning : and that it was nothing but a fpeoies of pyrites, without peculiarity, except as to the hepatic fmell difengaged from it by marine acid " Que cette pierre, qui peut-etre £toit t* couverte d'une petite couche de terre ou de gazon, aura *' e'te frappee par la foudre, et qu'elle aura ete ainfi mife en " evidence: la chaleur aura 6t6 alfez grande pourfondrela ■" fuperficie de la partie frappee, mais elle n'aura pas etc- afiez f* long-tems continuee pour pouvoir penetrer dans Pinterieure " c'eft ce qui fait que la pierre n'a point 6t6 decompofee. f* La quantite de mati^eres m^talliques qu'elle contenoit, en u oppolant moins de reTiftance qu'un autre corps au courant M de matie're ele&rique, aura peut-etre pu contribuer meme a H determiner la direction de la foudre/' The Memoir is however concluded, by obferving it to be Sufficiently fingular, that M. Morand le Fi Is had prefented a Another ftone fragment of a ftone, from the environs of Coutances, alf0fromCoutances, faid to have fallen from heaven, which only differed from that of the Abbe Bachelay, beeaufe it did not exhale the hepatic fmell with fpirit of fait. Yet the academicians did not think any conclufion could be drawn from this refemblance, unlefs that the lightening had fallen by preference on pyritical matter.* Mons. Barthold, Profeffeur a PEcole centrale du Haut- Barthold's ej$- Rhin, gave I believe the next, and laft, f analytical account ^^^S * of what' be alio denominates Pierre de Tonnerre. He defcribesit thunder ftone thus : *' La maffe de pierre connue fous le nom de Pierre de we,gning two , | . • . quintal^. H Tonnerre d'Enfislieim, pefant environ deux quintaux, a la " forme exte>ieure arrondie, prefque ovale, raboteufe, d'un f afpecl terne et terreux. " Le fond de la pierre eft cPune couleur grife bleuatre, Defcriptlon. (' parfem£e de criftaiix de pyrites, ifoles, d'une criftalifation f4 confufe, en quelques endroitsecailleufes, ramaffes, formant * See Journal dephyfique, Tom. II. p. 251. + A very interefting detail of a meteor, and of ftones fallen in July 1790, was given by Profeffeur Baudin, in the Magaxinfiir fas Neuefle aus der ?byfikx by PrqfefTqr Yoigt. ff des 220 Frafture. Composition. ON STONY AND METALINE SUBSTANCES, &C. " des noeuds et des petites veines, qui Ie parcourent en tout " fens : la couleur des pyrites eft dore* ; le poli leur donne un a ^clat d'acier, et, expofees a l'atraofphere, elles terniffent " et bruniflent. On diftingue de plus, a Poeil mid, de la mine f« de fer grife, (Scailleufe, non fulfureufe, attirable a l'aimant, •' diffoluble dans les acids, peu oxid£, ou s'approchant beau* " coup de l^tat meHallique. " La caflure eft irr^guliere, grenue, d'un grain un peu " ferr£ : dans l'interieur on voit de tres petites fentes. Elle ne " fait pas feu au briquet : fa contexture eft ii lache quelle fe y laifle entamer au couteau. Enlapilant, elle fer^duit aflez " facilement en une poudre grife bleuatre d'une odeur terreufe. *' Quelquefois il fe trouve de petits criftaux de mine de fer, " qui reiiftent plus aux coups du pilon." The fpecific gravity of the piece in ProfefTor Barthold's pofleftion, was 3233, diftilled water being taken at 1000. The analyfis of Mons. Barthold, of which I mall alfo have occaiion to fpeak hereafter, gave in the 100. Sulphur Iron Magnefia - Alumina Lime Silica - 2 20 14. 17 2 42 97 From the external characters, and from his analyiis, the Profelfor confiders the ftone of Enfifheim to be argillo-ferru- ginous ; and is of opinion that ignorance and fuperftition have attributed to it a miraculous exiftence, at variance with the firft notions of natural philofophy.* Sir W. Hamil- The account next in fucceflion is already printed in the ton's account of Tranfadions of the Royal Society ; but cannot be omitted, as ftones that fell . . ' J J ' T , '. during a thunder it immediately relates to one of the lubltances 1 have examm- ftorm. ej# J allude to the letter received by Sir William Hamil- ton, from the Earl of Briftol, dated from Sienna, July 12th, 1794. " In the midft of a moft violent thunder-ftorm, " about a dozen ftones, of various weights and dimenfions, " fell at the feet of different perfons, men, women, and " children. The ftones are of a quality not found in any part * See Journal de Phyfique. Ventose, An. 8. p. 16$. of SCIENTIFIC NEWS. 221 «« of the Siennefe territory ; they fell about eighteen hours €t after the enormous eruption of Mount Vefuvius : which «' circumftance leaves a choice of difficulties in the folution " of this extraordinary phenomenon. Either thefe ftones " have been generated in this igneous mafs of clouds, which «* produced fuch unufual thunder ; or, which is equally incre- " dible, they were thrown from Vefuvius, at a diftance of at •' leaft 250 miles; judge then of its parabola. The philofo- " phers here incline to the firft folution. I with much, Sir, " to know your fentiments. My firfl objection was to the " fa6t itfelf ; but of this there are fo many eye witnefles, it " feems impoffible to withftand their evidence." (Phil. Trans. for 1795. p. 103.) Sir William Hamilton, it feems, alio received a piece of one of the largeft ftones, which weighed Weight, upwards of five pounds ; and had feen another, which weighed about one. He likewife obferved, that the ouitfide of every ftone which had been found, and had been afcertained to have fallen from the clouds near Sienna, was evidently frefhly vitrified, and was black, having every fign of having pafled through an extreme heat; the infide was of a light grey colour, mixed with black fpots and fome finning particles, which the learned there had decided to be pyrites. (To be continued.) SCIENTIFIC NEWS, &V. Dimenfions and Nature of the New Planets Ceres and Pallas. By Dr. Herschel. Dr. HERSCHEL's obfervations on the two lately dif- covered celeftial bodies were read before the Royal Society, 6th of May. Dr. Herfchel begins with ftating the refult of his attempts Obfervation of r r it r i n it i i ™ K the diameters of to mealure the diameter or the ltars dilcovered by Piazzi and Ceres and Pallas. Olbers. He employed the lucid difc micrometer, which con" lifts of an illuminated circle viewed with one eye, while the other compares with it the magnified image formed by the te- lefcope; and he concludes, that the apparent diameter of Ceres was 22", and of Pallas 17'' or 13", at the diftance of nearly 1.634, and 1.187 from the earth refpeclively, whence the apparent diameters at the diftance of the earth from the fun would be .35" and .2 1'' or . 16" refpe&ively, and that their -real 222 SCIENTIFIC NEWS. Ceres about 163 real diameters are about 163 and 95 or 71 Englifh nftfctf.' m/iSS^ oiThere ■ no Probability that eit"er of thefe ftars can have ft 71. latellite. The colour of Ceres is more ruddy than that of Pallas. They have generally more or lefs of a hafcinefs, ol- eoma, but fometimes, when the air is clear, this nebulofity fcarcely exceeds the fcattered light furrounding a very fmall ftar. From a view of all thefe circumftances, Dr. Herfchel proceeds to confider the nature of the new itars. He think* that they differ from the general character of planets, in their diminutive dimenfions, in the great inclination of their orbits, in the coma furrounding them, and in the mutual proximity of their orbits ; that they differ from comets in the want of ec- Attempt to con- centricity, and of a confiderable nebulofity. Dr. Herfchel clafs of celeftial therefore, willies to call them afteroids, a term which he de*- bodies. fines as a celeftial body, which moves round the fun in an orbit either little or confiderably eccentric, of which the plane may be inclined to the ecliptic in any angle whatever, the motion being either direct or retrograde, and the body being furrounded or not by a confiderable atmofphere or a very fmall coma. This definition is intended to include fuch other bodies of the fame kind as, Dr. Herfchel fuppofes, will, in all pro*- bability, be hereafter difcovered. Some additional obferva- tions (how, that the apparent comas furrounding Ceres and Pallas, fcarcely exceed thofe which are caufed by aberration round the images of minute fixed liars. JT. of the Royal Injlitution. ExtraS, of a Letter from the Rev. James JVilfon, D. D. Minijier of Falkirk. Falkirk, Stirling/hire, June 18th, 1802, Durability of A few weeks ago the fexton of this parifh, upon opening *hk kun-!d m a Rrave m tne cnurcn yard, found a ribband wrapped about the bone of an arm, which upon being wafhed was found to be entire, and to have fuffered no injury, though it had lairt for more than eight years in the earth; and had been in con<* tact with a body which had paffed through a ftate of corrup- tion, and was reduced to its kindred dull. By what means did the filk refiit the putrefactive procefs ? it is not a compact fubftance like hair, horn, or bone, which are frequently found in graves after every other fubftance is completely changed. As filk is deprived of the gummy matter by the act of clean- ing and fcouring, and as this feems to be the chief animal fub* ftance ACCOUNT OF BOOKS. £23 fiance which it contains, may noc the remaining fibrous part be the better prepared to withftand the power of putrefaction ? Accurate experiments tending to illuftrate this enquiry might be both amuiing and inftructive. ACCOUNT OF BOOKS OF SCIENCE. Memoirs of the Literary and Philofophical Society of Manckejler, Vol. V. Part 11. 06tavo, 700 Pages, with 9 Plates. Cadeli and Davies, London, 1802. A HIS publication of the refpectable Society of Manchefter is no Jets interefting than the former volumes of which the fcien- tific world well knows the value ; it contains the following me- moirs : — I. On tragedy, and the intereft in tragical reprefenta- tions: An Effay. By the Rev. George Walker, F. R. S. and Profeflbr of Theology in the new College, Manchefter. — 2. Experiments and obfervations to determine whether the quantity of rain and dew is equal to the quantity of water car- ried off by the rivers and railed by evaporation ; with an in- quiry into the origin of fprings. By Mr. John Dalton. — 3. Experiments and obfervations on the power of fluids to conduct heat; with reference to Count Rumford's feventh effay on the fame fubject. By Mr. John Dalton. — 4. Experi- ments on the velocity of air Hilling out of a veffel in different circumftances; with the defcription of an inftrument to mea- fure the force of the blaft in bellows, &c. By Mr. Banks, Lecturer in Natural Fhilofophy. Communicated by Mr. Dalton.- — 5. Eflay on the beautiful in the human form ; and enquiry whether the Grecian ftatues prefent the moft perfect beauty of form that we at prefent have any acquaintance with. Communicated to the Society from a Correfpondent, through the Rev. George Walker. — 6. A defence of learning and the arts, againft fome charges of Roufleau : In two effays. By the Rev. George Walker, F. R. S. — 7. Obfervations on the nervous fyftems of different animals ; on original defects in the nervous fyftem of the human fpecies, and their influence on fenfation and voluntary motion. By John Hill, M. D. — 8. Experiments and obfervations on the heat and cold pro- duced by the mechanical condenfation and rarefaction of air. 224* ACCOUNT OP BOOKS. By Mr. John Dal ton. — 9. Account of fome antiques lately found in the river Ribble. By Mr. Thomas Barritt.— 10. Ex- perimental eflays on the conftitution of mixed gafes ; on the force of fleam or vapour from water and other liquids in differ- ent temperatures, both in a torricellian vacuum and in air; on evaporation; and on the expanfion of gafes by heat. By Mr. John Dalton. — 11. A review of fome experiments, which have been fuppofed to difprove the materiality of heat. By Mr. William Henry. — 12. An inveftigation of the method where- by men judge, by the ear, of the pofition of fonorous bodies relative to their own perfons. By Mr. John Gough. Com- municated by Dr. Holme. 13. On the theory of compound founds. By Mr. John Gough. Communicated by Dr. Holme. — 14. Meteorological obfervations, made at Mancheiler. By Mr. John Dalton.— Appendix, I. Explanation of a Roman infeription, found in Cattle-field, Manchefter. By Mr. Thomas Barritt. With a note on the fame fubjecl, by Dr. Holme. — II. Koie to Mr. W. Henry's paper on heat. THE Rev. Thomas Falconer, A. M. of Bath, propofes to print by fubfeription, the Geography of Strabo, in feventeen books : tranflated from the Greek text ; illuftrated by maps, coins, inferiptions, &c. accompanied with the notes of the older editors, and of the later ; thofe of Thomas Falconer, Efq. of Cheller, the Oxford editor, entire; of Siebenkees, and Tzfchucke, of Germany ; and thofe of the tranflator. The conditions are — 1 . The work will be printed in a hand- fome manner, with foot notes: 2. It will be contained in three volumes quarto, if pofiible: 3. The price will depend upon the Rate of paper when the work (hall be put to prefs ; but it is hoped that four guineas will be the largeft eftimate : 4. Two guineas to be paid at the time of fubferibing, for which a re- ceipt (hall be given, and the remainder when half the work is delivered to fubferibers : 5. The work will not be fent to prefs till three hundred copies are engaged, and only five hundred will be printed . Subfcriptions received by Meflfrs. Cruttwell, and Bull, Bath ; Cooke, Hanwell, and Parker, Oxford ; Cadell and Davies, London ; and Manners and Millar, Edin- burgh. ERRATA. In Mr. Chenevix's paper, p. 114, for futyburated read every where fulpkuntted. — ■ — —."■•—■■■ ,•'■■"" • A JOURNAL OF Natural philosophy, chemistry, AND THE ARTS. AUGUST, 1802 ARTICLE I. On Granite. JBj/ Mr. Robert Jameson. Communicated by the Author. Sheriff Bra:; Leith, July 10, 1802. JL HE primitive rocks, of which granite is the otdeft, were Primitive rocks formed during that period which Werner terms the chaotic, f°rme.d dur'"s i Au . the chaotic ftate when the earth was lull covered to a great height with water, by depofmon and before organization had commenced. Their ftructure f™m an aqueous fhews that they have been depofited from a ftate of chemical folution *> and the diminishing level of the newer ftrata, that * To the idea of all foflil fubftances having been in a ftate of chemical folution in water, it has been objected, that many of them are intirely infoluble in water. To this, without adducing any of the numerous geological proofs, I anfwer, that we know not the original ftate of the different earthy and metallic fubftances ; the artificial means we employ to procure them, may, and certainly has altered many of them from their original ftate.-— J. It may alfo be remarked, that many infoluble compounds are de- pofited by the chemical action of bodies which were foluble before they met. Our earths may be fuch compounds. ---N. Vol. II.— August, 1802. Q the 226 ON GRANITE, t*a On the name granite. the water has funk gradually and calmly. They ufually oc- cupy the higher parts of the globe, but when covered with newer ftrata may form the loweft. The rocks which Werner considers as belonging to this great clafs are, granite, gneifs, mica flate, primitive flate, porphyry, and fienite. As granite is in many refpecls one of the moil important of thefe formations, I fhall here detail feveral interefting particu- lars refpecling it. Fliny, and the older writers, defcribe this rock under dif- ferent names j the term granite appears to be of modern date, as Montfaucon is the firft writer who ufes it. This will not furprize us, when we confider, that it was not until the re- vival of letters when the remains of antiquity began to be flu- died, that the different rocks received particular denomina- tions. To Werner we are indebted for the molt exacl: defcrip- tion ; before his time it was confounded with fienite and grunftone, two rocks that differ both in their oryctognoftical and geognoftical characters. Granite is an aggregate, granular, primitive rocky which is com- pofed of felfpar, quartz, and mica. Aggregate com- Felfpar is generally the prevailing, and mica the leaft con- sent parts of fiderable ingredient. The felfpar has a confidcrable range of granite; felfpar, to. r j j r quartz, and colour; the principal colours are white, grey, red, and tome- mica# times, though rarely, green : it is found in all the intermediate ftates, from very great to very fine grain. The quartz and mica are generally grey, and the firft has fometimes a black colour. Several foffils occur in granite befides thofe we have juft mentioned ; thefe are fhorl and garnet : fuch varieties have received particular names, but the geognoft views them as accidental, and does not take particular notice of them. The topaz, which is diftinguiftied from all other precious ftones (excepting the emerald and garnet) by its occurrence in primitive mountains, is found accompanied with apatite in the tin beds which lie in granite at Ehrenfredersdorf. Itsjiruclure is -not fubjeel to much variety. When cryftali of felfpar are immerfed in a bafts of fine grained granite, it conftitutes what is termed porphyritic granite. Of this there are fine examples near to Carllbad in Bohemia, and in many places in the north of Scotland. If fometimes occurs in glo- bular Structure. Por. pbyritic. Globular, Ott GRANITE. 227 fcnlar diftincl concretions *, and thefe are again composed of Concentric lamellar, diftincl concretions. This ftru&ure of granite is only to be difcovered, after the fofter granite has Weathered out ; then thefe concretions which are vaftly harder, and are only feparated from each other by the loofer granite, make their appearance. Upon the road between Drefden and Bautzen I obferved many fine examples of this ftru&ure of granite : Mr. Barraud, in his interefiing defcription of the Cape of Good Hope, mentions feveral globular diftincl con- cretions of immenfe fize. In Scotland the ifland of Arran af- fords inftances of this kind f. It is frequently obferved diftinclly ftratified : in other in- Diftinclly h™. fiances owing to the thicknefs of the ftrata, this ftru&ure istlfied% difficultly obfervable, and has given rife to the opinion that fuch granite is not ftratified. The Riefengebirge, which fe- parate Silelia from Bohemia, are for 150 miles compofed of granite, difpofed in horizontal ftrata. Laft fummer I exa- mined thefe mountains along with a confummate mineralogifr, Dr. Mitchell, and we convinced ourfelves of the truth of this obfervation. I have obferved fimilar Gratification in Saxony and Lufatia. It is an interefting fa£t in the natural hiftory of granite, that It feldom con- it feldom contains extraneous beds, and Werner remarks, that fai"s extraneous the frequency of fuch beds increafes with the newnefs of the formation : thus gneifs contains fewer beds than mica flate, and mica flate fewer than primitive flate. Limeftone, which accompanies all the newer primitive No limeftone. formations, is intirely wanting in granite. Metals which occur in Granite. This rock is not fo rich in metals and their ores, as the pri- Metals which mitive rocks of newer formation. It contains, however, a occur in granite; confiderable variety, and fome of thefe have been as yet only difcovered in granite. Iron, which is remarkable on accountiron% of its occurrence in every period of the earth's formation, is found interfperfed in the oldeft granite. Red iron ore occurs * Thefe globular diftinft concretions ufed formerly to be con- fidered as bowlded ftones, and afforded an invaluable opportunity for the framing of extravagant hypothefis. t Mineralogy of the Scottifh Ifles, vol. i. p. 42, Q2 in 22S OS GKANITE. in veins in granite, alfo the brown iron ore, but this is fa? Molybdena hi- fddomer than the red. Molvbdena has as yet only occurred therto found . . . _ \ . . / ' only in granite. ,n gramte, either lnteriperled, or in veins of the oldeft forma- tion, as at Schlackenwalde, Geya, and Altenberg. Bifmuth, cobalt, Bifmuth, cobalt, blende, galena, and feveral ores of cop- and particularly Per nave Deen found in granite. Of all metals, however, tin ^n« h the one moft frequently found in granite, and in the great mining field of Cornwall, it is ohferved, that copper occurs frequently in primitive flate, but the tin in granite. The preceding obfervations refer principally to the old gra- nite, which, as far as our experience goes, is the moft elevated part of the auernating with Riefungebirge, which is about 5000 feet above the level of gneifs. the fea> granite alternates with gneifs, and hence Werner confiders it a diftind formation *. containing flate. 2d. At Greifenftein in Upper Saxony, Werner obferved granite which contained pieces of flate lying over ftrata of pri- mitive flate, hence he juftly reckons it to be a diftinft forma- tion, which is newer than either of the preceding. Wm& of granite 3d. At Auerfberg, near Eibenftock in Saxony, and at of muriate™13 Faftenberg near Johangeorgenftald, Werner difcovered veins and primitive of granite traverfing ftrata of mica flate and primitive flate, "ate* and this he is at prefent inclined to confider a new formation. In Scotland granite veins are very common, and feveral cir- cumftances lead me to believe, that thefe and the Aueriberg are the fame formation. They are probably both connected Characters of with the Greifenftein formation. Werner mentions a few par- the newer gra- (_jcu]ars vvhich he confiders as chara&eriftical for the newer nitej ulually low, red, fine granite formations. grained, &c. j# Granite, which occurs in low filiations, may be fuf* peeled to belong to the Greifenftein formation. 2. The newer granite has generally a deep red colour, is more frequently fine than coarfe grained, contains garnets, and is not porphyritic. * I was fo fortunate as to have the opportunity of examining this formation in company with Dr. Mitchell. We obferved the granite alternations three times with the gneifs* The ON GRANITE. C2l23 The late Dr. Hutton of Edinburgh has given us a very dif-. Dr. Hutton con- fcrent geological view of granite from that contained in the £*£" sr*mi* preceding pages. In my outline of the mineralogy of the Scottifti ifles, I endeavoured to fliew the fallacy of Dr Hut- ton's opinions. Profeffor Playfair, however, in his illuftra- tions of the Huttonian theory lately publifhed, has ftated a number of fafts, which he coniiders as fully confirming Dr. Hutton's ideas refpe&ing granite. I therefore take this op- portunity to ftate, more fully, the reafons that incline me to differ intirely from thefe gentlemen. Profeffor Playfair is of opinion, that the diftindion of granite profeflbr Play- into different formations is hypothetical. To this I can by no fair's opinion means affent ; on the contrary, I am fully convinced, that the ing diftincYions" granite formations are well afcertained, and this will be evi- are hypothetical, dent from the following obfervations : it is a polition, the The order of truth of which is acknowledged by every geognoft, that of date in granite two feries of rocks, the neweft, is that which covers the [j^ted from'^heir other. The Greifenftein granite formation lies over the primi- filiations. tive Hate, and is consequently newer than the old granite, gneifs, mica Hate, and primitive flate. To rende rthis intelli- gible to thofe unacquainted with the Wernerian geognofie, I have reprefented this formation in the (ketch, Fig. 1. Plate XIII. From this fketch it is plain, that after the depofition of the old granite, gneifs, mica flate, and primitive flate, the water had again rifen, and depoiited over the ends of thefe ftrata, this newer granite formation. The fienite formation, which has been often confounded with sienite ftyiiv the old granite, lies over the four older primitive formations, tion. and has, interpofed, a layer of breccia, compofed of fragments of thefe rocks. This demonftrates, as we have already re- marked, that the water muft have rifen and depofited firft the fragments of the older flrata, (which it had tore off in its ri- sing) and upon this the fienite. The fketch illuftrates, thele. appearances, Fig. 2, Plate XIII. Thefe facts and explanations, which are drawn from the Wernerian geognofie, I fliall now contrail with thofe of Dr. button, and Profeffor Playfair. Profeffor Playfair remarks, p. 309. " Veins of granite are Remarks of alfo frequent in Cornwall, where they are known by the name Profeffor Play- ^ lodes, the farne name which is, applied in that country Mrf^fc/ki metallic Cornwall. 230 ON GRANITE. metallic veins. The granite veins frequently interfecl; the me, tallic, and are remarkable for producing fhifts in them, and for throwing them out of their natural direction. The mine* ral veins, particularly thofe that yield copper and tin, run nearly from eaft to weft, having the fame direction with the beds of the rock itfelf, which is very hard fchiftus. Thegra- nite lodes, as alfo thofe of porphyry, called elvan, in Corn- wall, are at right angles nearly to the former ; and it is re- marked that they generally heave the mineral veins, but that the mineral veins feldom or never heave the crofs veins. In this country, therefore, veins of granite and porphyry are pof- terior in formation to the metallic veins. Thefe veins of gra- nite may perhaps be conneded with the great granitic mafs that runs longitudinally through Cornwall, from Dartmoor to the Land's End. This much is certain, that their directions in general are fuch, that if produced, they would interfecl that Ifluing like roots mafs, nearly at right angles." Further, at p. 317. he re- chad's Mount mar^s> " The laft inftance I have to mention from my own into the fchiftus, obfervation, is at St. Michael's Mount in Cornwall. That mount is intirely of granite, thruft up from under a very hard micaceous fchiftus, which furrounds it on all fides ; at the bafe of it a great number of veins run off from the granite, and fpread themfelves like fo many roots fixed into the fchiftus : they are feen at low water. In the fmaller veins, the granite is of very minute, though diftinft parts ; in the larger, it is j more highly cryftallized, and is undiftinguifhable from the mafs of the hill." I agree with Profeffor Playfair, in believing that the Cornifh veins may ftand in connection with the gra-r nite of the country, but fhould this be proved, the Cornifh referable to the granite muft then be referred to the Greifenftein or Sienite tion.'te f°rma* f°rmation- The appearances obferved at St. Michael's Mount demonftrate, that it belongs to one of the formations I have juft mentioned ; and I have no doubt that if Profeffor Playfair had examined the fituation of the primitive flate, with re- gard to the granite, he would have found it covered by the granite. Other granite Again at p. 316, Mr. Playfair informs us, "that another vans in Ga o- fer;es 0f granite veins is found in Galloway, which were firft: difcovered by Dr. Hutton, and his friend Mr. Clerk, and af- terwards more fully explored by Sir James Hall and Mr. Douglas, the prefent Earl of Selkirk. The two laft traced 3 the ON GRANITE^ 23 \ *he line of feparation between a mafs of granite and the fchif- tus incumbent upon it, all around a tract of country, about eleven miles by feven, extending from the banks of Loch Ken, wefiward ; and in all this tra& they found, " that wherever the junction oi the granite with the fchiftus was vifible, veins of the former, from fifty yards to the tenth of an inch in width, were to be feen running into the latter, and pervading it in all directions, fo as to put it beyond all doubt, that the granite whichMr. Hay- of thefe veins, and confequently of the great body itfelf, which {^^wed'toa was obferved to form with the veins one uninterrupted mafs, fofc ftate to their *nuft have flowed in a foft and liquid ftate into its prefent po- prefentfitua- fition *. I have only further to add, that fome of thefe veins are remarkable for containing granite, not fenfibly different, in any refpect, from the mafs from which they proceed." The The author ob- Criffle in Galloway, which is one of the moft confiderable por-^dfi^rifte tions of what Dr. Hutton confiders as the granite of that country, I found to be fienite, confequently it has no relation to the old granite formation. ProfelTor Play fair, who exa- mined the appearances at Loch Ken, believes with Dr. Hutton, that fienite and granite, in a geognoftic point of view, are to be confidercd as the fame f . From this I draw the and infers that conclufion, that at Lock Ken we have a portion of the fame ' J' ot er gra ' * nites are a por- lienite as that which forms the Criffle. tion of the fame. It appears then evident, that wherever granite, in the form The fame infc- ©f veins is to be obferved iiTuing from granite into the con- j,en" £encral:X tiguous ftrata of gneifs, mica Hate, &c. it nmft belong to a newer formation, and probably to that of Greifenflein. Many of the inftances where fuch appearances have been ob-* ferved, certainly belong to the fienite formation. It is therefore demonftratedt that Granite is the oldeft Rock zvith and that granite which ive are acquainted. £*e oldeft of Before I conclude thefe remarks, I fhall notice two objec- tions which have been urged againft the poffibility of granite veins having been filled from above. Mr. Play fair obferves at page 313, " that a ftrong objection to the fuppofed origin of To Profeflbr granitic veins from infiltration, and indeed to their formation Playfair'sremark , . , r r -r r i , ^tnat fragments jn any way but by igneous funon, antes trom the number of 0f fchiftus couid be iniulated in * Tranfaaions of the Royal Society of Edinburgh, vol.iii. p. 8. grfirLe *eins r oiuy by igneous f Illuftration of the Huttonian Theory, p. 312. fufion j fragments 232 ON GRANITE. " fragments of fchiftus, often contained, and completely infu- lated in thefe veins. Hqw thefe fragments were introduced into the fifiures of the fchiftus, and fuftained till they were furrounded by the matter depofited by water, is very hard to be conceived ; but if they were carried in by the melted gra- nite, nothing is more eafily underftood." To this objection, It is anfwered, it is only neceflfary to anfwer, that the apparent infulation of. infulated.arC n° ' maffes °? ^one & veins, is occasioned by our only feeing part of the mafs ; for when the whole is feen, we invariably find, that it refts upon another fragment, or upon the fides of the veins. At p. 31 4, when defcribing the junction of the granite with the other primitive ftrata in the ifland of Arran, Profeflbr And with regard Playfair remarks, " Along this line, particularly on the fouth, tot e granitic wnerever the rock is laid bare, and cut into by the torrents, veins or nume- . . . jousmaflesin innumerable veins of granite are to be feen entering into the "nhlffUAn ^ fchiftus, growing narrower as they advance into it ; and being directed in very many cafes, from below upwards, they are precifely of the kind which the infiltration of water could not produce, even were that fluid capable of diflblving the fub- ftances which the vein confifts of. From the fouth face of this mountain, and from the bed of a torrent which interfe&s. it very deeply, Dr. Hutton brought a block of fchiftus, of fe- veral hundred weight, curioufly penetrated by granite veins, including in them many infulated fragments of the fchiftus." it is remarked In the iiland of Arran I have had frequent opportunities of that they are examining thefe kind of veins; they are generally found in and have other gneifs, are very much incorporated with it, and often both figns of being extremes of the vein are to be obferved in the fame bed. nearly coeval ' . . . . ' , _ , ' , with the gneifs. From this it is evident that thele cannot be conndered as gra- nite veins, fince they are nearly of coeval formation with the gneifs, and have no communication with any formation, older or newer than that in which they occur *. Werner remarks, that veins which are nearly coeval with the vein rock, are * Although we find in gneifs veins filled, and layers compofed of a rock which, ory&ognoftically confidered, has every character of granite, yet the geognoft juftly views them as varieties cf gneifs. It often happens in a mountain of gneifs, that ftrata occur which are not to be diftinguifhed from mica flate; thefe, however, are merely accidental, and the whole is therefore to be referred to gneifs. This admirable mode of inveftigation, which was firft dif- covered by Werner, has been of the greateft utility in geognofia. very I ON THE CONVERSION OF IRON INTO STEEL, very much incorporated with it, have no falband, far lefs an interpgied layer of clay, (belteg) and the vein mafs differs very little from the vein rock. On the contrary, the newer the veins, the fewer are the points of their agreement, fo that at kill there is not the leaft refembiance. Thefe old veins he fuppofes to have been immediately filled out of the fame folution from which the rock had been precipitated : the contents at leaft of this fluid had not undergone any confide^ rable change. R. JAMESON. II. Obfervations on the Converfwn of Iron into Steel. In a Letter from Joseph Priestley, L.L.D. F.R.S. fyc. SfC To Mr. NICHOLSON. SIR, Northumberland, America, May 22, 1802. 1 OUR giving the following article a place in your valuable Journal, will oblige Your's, &.c. J. PRIESTLEY. ACCORDING to the antiphlogiftic theory iron becomes Antiphlogiftic fteel by imbibing carbon; to this is laid to be owing the addi-the.°yy of ftcei" i • • • iii making. tion to its weight in the procefs of cementation ; and the flakes of black matter which remain undiifolved after a folution of lieel in diluted acid of vitriol are laid to he plumbago, or carbon united to iron. I cannot, however, help concluding from fome late expe- Obje&ion from ments, that iron is converted into Heel by imbibing only phlo-lat(: exP«'ments J & J * and phlogiitic gifton from the charcoal, and that the addition to its weight is theory. not from carbon, but hom finery cinder. Having made a quantity of iron filings perfectly pure, by 120 gr. of iron firfl expelling from them all the air that they could be made fi.;inSs clea,ed of to yield by heat, then warning out of them any carbonaceous Wafhed were matter they might contain, and expoling them again to heat, heated in in- I took 120 grains of them, and heating them with a burning lens in inflammable air, found that they imbibed IS ounce meafures 234. which they Im- bibed and be- came bright. Thefeleftin vitriolic acid a black matter as fieel does. Its habitudes were thole of finery cinder. The black mat ter from pure fteel was affect- ed in the fame manner. It was therefore finery cinder, and not carbon. Bright needles afforded much lefs black mat- ter than watch fprings, of which the fur- face was blued or oxided. ON THE CONVERSION OF IRON INTO .St-EE£. meafures of it. In confequence of this, from being of a dark colour, they became exceedingly bright; and I concluded that they were now become fteel, though I was not able to afcertain it by a direct experiment. But after diflblving thofe bright filings in diluted vitriolic acid, a quantity of black mat- ter, as after the folution of fteel, remained unaffected* by it* This being heated in inflammable air imbibed a confiderable quantity of it, and then, by means of diluted vitriolic acid, gave inflammable air very copioufly. This black matter had evidently the properties of finery cinder. I then diflblved- 200 grains of broken watch /pipings, which are undoubtedly pure fteel, and collected from the folution' three grains of black matter. Heating this in inflammable air, a great proportion of it was imbibed ; and then, by means of the diluted acid, it gave out inflammable air as copioufly as iron or fteel filings would have done. This black matter, therefore, from the folution of fteel was finery cinder, and not carbon, or plumbago. And as iron acquires weight by be- coming finery cinder, and this addition of weight, I think I have proved to be from water, it can hardly be doubted, but that the addition of weight to iron, in being converted into fteel, is from the fame caufe. Indeed, I believe it to be im- poffible to expofe iron to a red heat in circumftances in which there is any poffible accefs of wrater, or of air, which always contains water, without a partial calcination of it; that is without its becoming fuperficially at leaft finery cinder. This was evidently the difference between the refult of the folution of the watch fprings, and that of an equal weight, viz. 200 grains of broken polijhed needles, which had not undergone any calcination. For the black matter that remained from the folution of them would not have weighed a quarter of a grain. Giving colour to fteel, which is done to watch fprings, is al- ways a partial calcination of the metal ; and this appears from the preceding experiments to be the converfion of a part of it into finery cinder, which is the reverfe of plumbago ; being, according to the new theory, an oxide in the higheft degree ; whereas if plumbago contain any oxigen, it is in the loweft degree. UL.Au ART OF MAKING GLCE. 23$- III. An Account of the Art of ?naking Glue. In a Letter from Mr. John Clennel. T dear sir, Nezvcajllc,June 21, 1802. HE following attempt to develope the " art and my fiery" Great advantage* of glue-making is at your fervice, if you think it worthy a ^j report of0'* place in your very valuable mifcellany. The improvement of manufa&crics* any manufacture depends upon its eafy accefs to men of fcience, and a prudential theorift can never be better employed than in attempting to reduce to regularity or to fyftem the manufac- tures that may fall under his attention. In conformity to the fir ft principle, I made fome notes whilft vifiting a glue manu- factory a few years ago iri Southwark, and thofe, interwoven with the remarks on that fubject of fome chemifts of the firft refpeclability, I take the liberty of fending you: at the fame time I muft beg of you, or your correfpondents, that where it may be corrected in any manner, it may be done, and I thai! feel my f elf obliged by the attention. Glue is an infpiffated jelly, made of the parings of hides or GIue »« made horns of any kind, the pelts obtained from furriers, and theh^™ re&c* hoofs and ears of horfes, oxen, calves, fheep, &c. quantities of all which are imported in addition to the home fupply, by many of the great manufacturers of this article : thefe are fnii digeft- Cleaned from ed in lime water, to cleanfe them as far as it can from the gre* c by, lime~ ' water j then greafe or dirt they may have contracted ; they are then fteep- fteeped in dean ped in clean water, taking care to ftir them well from time to)va.t;crJ\ciraincd> • r 11 i -, • , , r i boi,ed 'n water j time ; afterwards they are. laid in a heap, and the luperabun- clarified by alum dant water preffed out; then they are boiled in a large brafsor ,,me3 ftain- caldron with clean water, (kimming off the dirt as it rifes, and fubfidence • further clean fed by putting in, after the whole is difTolved, aaSain- boiled to little melted alum or lime finely powdered, which, by their de-^J^y-'poured terfive properties, flill further purge it : the (kimming is con- into moulds ,* tinued for fome time, when the mafs is firained through bafkets, ^.ut ' V°,r~ . . ' , .... t,ons » and dncf and fuffered to fettle, that the remaining impurities, if any, on a net. may fubfide ; it is then poured gently into the kettle again, and further evaporated by boiling a fecond time, and ikimming, until it becomes a clear but darl^im brown colour: when it is thought 23$ Character of jood glue. Judgement of the tikes. AJtT OF MAKING CLUE,. thought to be ftrong enough (which is known either by the length of time a certain quantity of water and materials have boiled, or by its appearance during ebullition), it is poured into frames or moulds of about fix feet long, one broad, and two deep, where it hardens gradually as the heat decreafes: out of thefe troughs or receivers it is cut when cold by a fpade, into fqnare pieces or cakes, and each of thefe placed within a fort of wooden box, open in three divifions to the back; in this the glue, as yet foft, is taken to a table by women, where they divide it into three pieces * with an inflrument not unlike a bow, having a brafs wire for its firing ; with this, they ftand behind the box and cut by its openings, from front to back : the pieces thus cut are taken out into the open air, and dryed on a kind of coarfe net work, fattened in moveable (beds of about four feet fquare, which are placed in rows in the glue- maker's field (every one of which contains four or five rows of net work) ; when perfectly dry and hard, it is fit for fale. That is thought the belt glue which fvvells confiderably without melting, by three or four days immerfion in cold water^ and recovers its former dimenfions and properties by drying. GIqe that has gotfroft,, or that looks thick and black, may be melted over again and refined, with a fufficient quantity added of frefli to overcome any injury it may have fuftained ; but it is generally put into the fettle after what is in it has been purged in the fecond boiling. To know good from bad glue, it is neceflary for the purchafer to hold it between his eye arid the. light, and if it appears of a ftrong dark brown colour, and free from cloudy or black fpots, the article is good. I am, Sir, With great refpecr, Your's, &c. JOHN CLENNELL, * When the women, by miftakc, cut only two, that which is tljuble the fize is called a Bifliop, and thrown into the kettle again. IV. On *HEPAKATI0N OF INDELIBLE INK. - *>37 IV. On the Preparation of Indelible Ink. In a Letter from Mr. Thomas Sheldrake. To Mr. NICHOLSON. S IR, x\S your correspondent, Mr. Clofe, has alluded to my me- moir on the nature and preparation of drying oils, it may not be unpleafant to receive fuch information as I ara able to give refpecling the object of his purfuit. By experiments repeated and varied every way that my iina- Amber is not gination can fuggeit, I am convinced that amber is not fo- ^1"^!e |" j! 'jf01 luble in alcohol or any eflential oil : it is foluble in exprefied oils, by the procefs defcribed in Lewis's philosophical com- merce of the arts, but that folution does not dry well, and The folution in therefore will not anfwer Mr. Clofe's purpofe; but when dif- n*fgC00j f°rink* folvedby the * well-known procefs for making amber-varnifh, but the folution it is likely to anfwer extremely well. for varnifh is * J y good. There is another fubftance which feems likely to anfwer his Afphaltum pro- purpofe very well, f Afphaltum is a bituminous fubftance, mifes t0 be.a, ,._,,,. . . , . r . . , r good material, perfectly black when viewed m a mals, but a dark transparent brown when diifolved : it is foluble in fpirit of turpentine at a * The following is the moft convenient method : Put fmall pieces Procefs for the of amber into an iron ladle, fet it on a fire till they are melted, then 0'ty foluton w timber add fo much of the beft drying oil as will make it liquid, ftir them well together, and, when cold, add fo much fpirit of turpentine as will make it thin enough to flow from the brufh. The object in making varnifh is to difcolour the amber as little as poffiblej there- fore it is but little roafted, and the lighteft coloured drying oil is ufed } but if this folution of amber was ufed for making ink, the darknefs of the colour would be an advantage, therefore the amber fhould be thoroughly melted, and the darkeft drying oils ufed in preference to the others. •f- Within thefe few years good afphaltum may be procured in pood afphaltum many (hops in London : before that period it was unknown j the 1S now *a y beft of what was fold, and is fill fold in fome places, was the caput mortuum of amber j other compofitions of pitch and various refms Were likewife fold for afphaltum. If it were ufed for Mr. Clofe's I ink, care mould be taken to feleft the beft. low U3S PREPARATION OF INDELIBLE fN#. low heat, and when difiblved runs freely from the pen: I have known fome artifts draw with this in preference to ink, becaufe its colour harmonizes better with other materials alfo ufed in drawing, and becaufe it is indelible, as it itrikes immediately into the paper, and if it is not thick, will ftrike through it: by this means every ftroke made with it is vifible through every colour that is waflied over it. .Afphaltum in It feems then that if a folution of afphaltum was made in ipint of turpen- ^pjrjt 0f turpentine, and fo much of the folution of amber was confiftent with added as would give it due confidence, and the fineft lamp Solution of am- black to give it colour, a perfect ink would be formed, and loured with lamp poffeifing thofe properties Mr. Clofe feems to defire; for, fup- biack, would pofmg the other materials could be removed, fo much of the colour as depends on the afphaltum would be indelible, except by fuch means as would deftroy the paper or parchment. The drying oil Even the fmall quantity of drying oil introduced into the m 'Sdincreafc varmfll' would be ufeful in this refpeft; for it is well known, the difficulty of that if oil is dropped upon white paper, though the mark is chiitcration. fcarcely vifible at firft, in a year or two it will become a dark yellowifh brown : it feems as though the oil changes the paper fo much that its colour can never be recovered, at leaft thofe who undertake to reftore the white colour of old prints, always make an exception to fpots of oil. If this hint fhould be thought deferring any notice, you will have the goodnefs to make what ufe you pleafe of it. I am, Sir, Your's, &c. T. SHELDRAKE. JVb. 50, Strand, July 6, 1802. Copal would ^' ^' * believe Mr. Clofe will find himfelf miilaken as to probably be dif- the iniblubility of copal when ufed in his ink. So powerful is charged from ^ jnfluence 0f camphor upon it, that if copal be reduced to paper by cam- x . ... fhorated fpirit. powder, and a little camphor is rubbed into it, it immediately begins to foften, and the whole foon becomes a coherent mafs; and though copal is not foluble in alcohol alone, if camphor is added, it diflblves as eafily in the compound as the fofteft refin would. It is therefore extremely probable, that, if a paper written with his ink was waflied with camphorated fpirits, the writing would be removed with very little difficulty. V. Ohfervations ! OBSERVATIONS ON SALT. ^39 V. Obfer rations on the Caufes why a large Quantity of common Salt prevents Putrefaclion, and a fmall Quantity hajlens it. By D. H. To Mr. NICHOLSON. S I R, JL HERE are few phenomena of nature more interesting, and Remarkable op- at the fame time more involved in obfeurity, than the twooppo- P°!itl0Il of ef" fl «. P • . r r , i-i-i i fectsof common lite actions or muriate or ioda, which is known to have very con- fait jn prcvent- fiderable effect, both in accelerating and in retarding putrefac- jnS or accelerate tion. The antifepiic property of this fait has been known from as jts quantit* & the earlieft ages. It was difcovered, however, by Pringte, more or lefs. Macbride, and Gardane, (hat putrefaclion may be haftened by fprinkling the animal fubflances with water holding a fmali quantity of muriate of foda in folution. This difcovery excited much furprife; and the celebrated chemifts who obferved it feem to have been fully aware of the difficulties attending its explanation, as they have offered no theory to account for it. Jt would doubtlefs appear a prefumptuous undertaking, to attempt the folution of a queftion which has baffled the inge- nuity of to many philofophers, did not the fubfequent difco- veries in chemiftry and phy liology enable us to fpeculate on the fubjeci with fome degree of probability. It feems neceffary for the decomposition of an animal fub- Putrefaclion re- ftance, \ft, that it be in contact with atmofpheric air ; 2dly, that J^l]^' j it be expofed to a moderate degree of heat ; and, 3dly, that it moifturej be impregnated with, humidity. It muft neceflarily follow, that whatever removes thefe conditions will check the progrefs of putrefaction. Of this we have many inftances, as in thean(j ;s checked effects of cold ; in covering the fubftances with fugar, refins, by fold and co- &c. and in preferving them in fpirit of wine. I conceive with a^?"2 f°m Gren, that muriate of foda acls only in this way, by abftracling Crude common the moifturc, and removing the fubftance from the contact of falt fappofed to oxigen; and not by a peculiar innate, and as it were hidden ?ngYndcovcrPg (vis occulta) antifeptic power *. the body it is applied to. * Grtn's Cherniftry, Chap. VIII. With *24?Q OBSERVATIONS ON SALT. PutrcfaaioH is With regard to thcfeplic property of muriate of foda; it muft haftencd by de- fe referred to another caufe. The deflruaion of mufcular ir- ftroymg irritabi- ..... . . . 2 r c . , c jity. ritability appears to be a chief cauie ot accelerating putrefac- tion. This was afcertained by Mn John Hunter, who found, that when death is occafioned by an electric (hock, by violent exercife, by a blow on the llomach, or by any thing that de- liroys the irritability of the mufcular fibre, putrefaction quickly enfues. Fontana found that the fame effects were produced by the poifon of vipers. It has been alio found by experiment, that the compounds of potafh and foda deftroy mufcular irrita- Commonfakin-bility. Now, is it not a fair inference from thefe premifes, !ba1tecfi^r.°dUCC that a fma11 qilailtity ot" muriate of foda fliould poflefs a feptic quality ? Upon thefe grounds, it will not be difficult to reconcile Mucbfah re- the two oppofite actions of muriate of foda. When a large tards putrefac- qUantity of this fait is applied to an animal fubfiance, it acts and covering, merely by removing the indifpenfible conditions of putrefac- more than it ac- ^on> an- and moifture. The particles in contact with the fub- hftmentioneT fiance may indeed a& in deftroying the irritability of the muf- quality. cular fibre; but this being only a fecondary caufe of putrefac- tion, cannot operate unlefs in conjunction with air and moil- Little faltacce- ture. On the other hand, when a Imall quantity of this fait in lerates it for thef0]uljon js applied, it is inefficient either to exclude the air, or «on raryreaon. ^ akftra& themoifture; its peculiar property, therefore, acts in conjunction with the other caufes, and thefe caufes united accelerate the putrefactive procefs much more than any of them Separately. Such is the explanation of thefe phenomena which occurred to me. Although it may be imperfect in many points, yet it appears to involve no hypothefis, but to be a Uriel deduction from facts. Should this attempt have the good fortune to meet with your approbation, its infertion in the Philofophical Journal may at leaft have the eflect of drawing the attention of fome more eminent chemiit to this too much neglected fubject. I am, Sir, Your's refpectfully, Edinburgh, July 12, 1802. D. H. VI. Account METHODS BY WHICH SODA IS PREPARED. 24J VI. Account of the Methods by which Soda is at prefent prepared for the Englijh Market ; with other Obfervations. By Mr. Fred. Accum. From the Author. UlNCE the late new duty on fait, the manufacturers of foda Soda obtained by avail themfelves of the method of decompofing the fulphate of fu^^o? the foda *, by means of what is called American potafh. Though bleachers with this kind of potafh contains lefs pure alkali than the Ruffian f^erican pot" or German potafh, it is imported in a Irate of perfect dry- nefs, whereas the other is always met with in a moift flate ; fo that the ab fence of water appears to compenfate for the deficiency of the alkali. The American potafh fells now from 48s. to 54s. per cwt. it has been confiderably higher, until lately it fluctuated between 54s. and 56s. I have been employed in a foda manufactory in which the Particular de- following method anfwered exceedingly well. ' Five hundred mlnuheL\xx\nz pounds of fulphate of foda were introduced into an iron boiler procefs. containing a fufficient quantity of Thames water. 560 lb. of American potafh were likewife diffolved in as little water as poffible in an iron boiler fixed near the former. The potafh was always previoufly tried, and if indifferent the quantity taken was 10 lb. more. The folution, as near as I recollect, was made with about A boiling folu- thirty pails of water to the alkali here mentioned. Both folu- tl0n of P°tafll . . i,t-i i r i i it- • was added to ac- tions were then made to boil, and as loon as the ebullition other of fulphate took place the folution of potafh was ladled into the boiler o{ foda» containing the fulphate of foda. The mixture was agitated during the transfufion, and the fire raifed as expeditioufly as poffible. As foon as the fluid boiled it was ladled into a then boiled, wooden gutter, which conveyed it into a cittern of wood lined with fheet lead nearly half an inch thick, which was fixed in a cool place. Sticks of wood were then placed acrofs the ciftern, from which flips of fheet lead two or three inches wide were hung into the fluid at four inches diftant from each * Sulphate of foda is fold cheap by the bleachers, who have it as the refidue of decompofing common fait by fulphuric acid with manganefe. In February, 1801, it was worth from lis. to 14s. per cwt. but I have not the prefent price.-— A. Vol. II.— -August, 1802. R other. 242 METHODS BY WHICH SODA IS PREPARED*. and drawn oft* to other. When all was cool, which in the winter was gene* Stfciftcm! rall}' the cafe m threG ***** a pIu& in the bottom of the cif- tern was drawn in order to let off the fluid, and the cryftal- lized fait was taken from the flips of lead. The bottom exhi- bited a rock of fait, which was detached by chiflel and mallet. On this account it is that the lead which lines the ciflern muft be thick, in order to guard againft accidents. For if the metal be perforated, the faline folution creeps between it and the ivood, and in a very fliort time detaches the lining, and it is befides extremely difficult to find out the place where the de- at a temperature feet really is. The temperature where the foda is left to cry- Thefoda is then ft^h'ze ought not to exceed 55° Fah. In this ftage of the pro- walhed with cold cefs the whole of the fait is wafhed in the fame cittern with water> cold water, to clear it of impurities ; after which it is trans- then diflolved ferred again into the boiler, diflblved in cleas water, and eva- tfl toJhSt? Porated Dy heat- As r°on as a ftronS pellicle is formed, it is furlercd to cool fo far that the hand may be dipped in the fluid without injury, and the heat is kept at that temperature Pellicles of fal- as long as effectual pellicles continue to be formed over the are* formed ^nd wno*ie furface of the boiler, and then fall to the bottom, fall downj When no more pellicles are formed, or at leatt only by blow- ing with the mouth upon the furface, the fire is withdrawn, and the fluid is ladled out into the cittern to cryftallize. The fulphate of potath, &c. which had been deposited, is then which ceafing, taken out of the boiler and put afide. If the fluid be fuffered llrawnofftocrv- *° C00^ Pretty l°w before it is fuffered to run into the ciilern, ftallize. very little fulphate of potafli is found in the foda ; but in ge- neral the rocky mafles of foda met with in the market contain 100 parts of ful- a confiderable quantity. By this procefs from 136 to 139 lb. afford ttltf 0f foda ma^ be obtained from 100lb- of fulphate of foda, if carbonate. the foda be eryftallized in large cryftals ; if fmall eryftallized it yields lefs ; it fells now at 52s. or 54s. per cwt. and is retailed at 8d. per lb. The two cryftal- We might be inclined to fuppofe that the firft operation was hzationsare unneceflary, and that the foda might be feparated at once ceffary. from the fulphate of potath at the inftant of its formation ; but practice will convince the operator otherwife. A confiderable lofs is mantfefted if the procefs be not conducted in this man- ner ; though the difcovery of the caufe may perhaps be not fo S&ii\y accompliflied as the proof of the fact. Other MfeTHODS BY WHICH s6DA IS PREPARED. 54"3 Other manufacturers grind together 500 cwt. of Glauber's Another procefs. fait of the bleachers, and 100 cwt. of charcoal; they expofe 5^^^ this mixture in a reverberatory furnace refembling a baking decompofed and oven, till the matter when ftirred with a rake becomes pally. exP*lleJ ft h'at , , . , /it Wltn charcoal, It is then withdrawn and transferred into large calks; each provided with a double bottom. Water is then fuffered to ftand one inch high over it for 24? hours ; the cock is then and the foda ex- opened, the folution runs through the perforated bottom, over £aaed b? water» which a ftratum of ftraw had been previoufly placed ; and is thence conducted into the boiler for evaporation and Cry (la l- lization *. It is a curious fact, that iron plates are abfolutely neceffary The heat muft to conftitute the furface on which thefe articles are expofed to .be aP?licd cn aa r iron, and not a heat : fire bricks do not anfwer. It feems as if the iron affifted i>rick hearth. the union j though neither iron filings mixed with the articles nor pyrites are found of advantage* This method of making foda is extremely uncertain. If the t/ncertainty of heat be not raifed gradually, or if the mixture be not fufed thjs method* enough, or a little too much, it does not fucceed. Theworft event is, that when the mixture has been made too hot; ful- phuric acid is produced, and fulphate of potafh is formed. The quantity of foda which may be obtained by this procefs, it is (aid to be is faid to be equal to that obtained by anv other method. profitable if well -. . . » -A managed. I have been lately informed, that in Germany foda is made Third method. by decompofing the fulphate of foda by means of acetite of Sulphate of foda J , • • , - i, • i r ^ / r r , decompofed by lime ; the acetic acid is obtained tor that purpole trom wood, acetite of lime,'. and the charcoal is found to pay the cofts. of which the The method recommended by feveral chemifts, of obtaining dialling w»ZL foda by decomposing Glauber's fait by acetite, or the oxide's The method re- of lead, does not anfwer in this country. The iriafs is by far aSoftJ? too bulky ; and requires too much time, attendance, arid fuel or elfe oxides of to reduce it to a narrow compafs. I have been informed by tIJ^un^tal lsf men well (killed in this department, that it is nearly impracli- lofs in this cable in the large way. The muriate of lead which is pro-^,untry# i j. ? r a LV • . . r The muriate of duced cannot be ufed as a white pigment, as the inventors lead thus ©b- pretend. tf,ned *s not a In Pruffia they mix muriate of foda and quick lime together ; pfujfun method then flake the lime, and form the whole into a thick pttfp, Dy quicklime; then flaking and ^ «,-, • , /. ,i /. , , .:, ,onS expofure to * This was the procefs at the fait works.— N. the air. Product R0 fulphate of lime 1 Which and carbonata of foda. 244 Comparison of the french metre which is extended about two inches thick over a large furfaccj, and left in that fituation for three months. Carbonate of foda is then formed, which is warned out and cryilallized in the ufual manner. The foda obtained by this procefs always has a yellowifli caft. VII. Comparifon of the French definitive Metre with an Englijh Stand- ard, brought from London b\j M. A. Pictet, one of the Editors of the Bibliothcque- Britannique *. Short hiftory of J[ HE meafurement of the earth, and the inveftigation of of the earth. *ts figure, were the fubjects, at various times in the courfe of the eighteenth century, of the labours of a number of philoso- phers of the firfl eminence in different countries. Some Swe- difii aftronomers are now employed in a fecond meafurement of the fame degree which was meafured fixty years ago by the French Academicians in Lapland, under the polar circle. In France, when the idea of feeking in the dimensions of the globe itfelf the unit to which all meafures and weights might be referred, had once been conceived and adopted, it was ne- ceflary to make an effort proportional to the importance of an particularly that undertaking which was thus become national. In the midft btely made in Qf a jong anc| fangU;narv war, together with difficulties of every other kind, a chain of triangles has been formed between Dunkirk and Barcelona, comprehending the tenth part of the arc of the meridian which extends from $e Equator to the pole, and which is equal to one fourth of the circumference of the globe ; and the ten millionth part of this arc, thus de- termined, has been adopted for the unit of the metrical fyf- tern : it has been fixed by the conftruclion of flandards made of fubftances proper to refill the attacks of time ; and by a careful examination of the precife relation of the length of the metre and the ftandard to that of the pendulum vibrating feconds, on the level of the fea, in a given latitude, the determination of this unit has been rendered independent of any accident that might deftroy or meafure thence deduced * From No. 148 of the Bibiiotheque Britanique. I avail my- felf of the free tranflation given in the Journal of the Royal Inftitu- tion j but have very carefully read the proof with the original.-— N. 4 impair WITH THE ENGLISH STANDARb, £>4'5 impair the ftandards reprefenting it ; while in the formation of thefe ftandards all the precautions have been employed that could be fuggefted by the prefent improved ftate of natural philofophy, and of the arts. In England, on the other hand, operations have been car- Operations of ried on for thefe five and twenty years, which are to be the [JcE^nf^m- examination of the Royal Society, to which he has the honour t-,fh ftandard. " of belonging, but he did not remain long enough in Paris to be able fo fucceed in this attempt'. He took advantage of his longer ftay in England, in procuring from the hands of Mr. Troughton, an artift celebrated for his accuracy in the con- ftruclion and divifion of geometrical and aftronomical inftru- ments, a ftandard rigoroufly conformable to that which he had made for Sir George Shuckburgh, and with which this philo- fopher had compared the principal Englifh ftandards. Our Apparatus by colleague procured alfo from the fame artift the comparative ^r0USbt°n for apparatus of Sir .George Shuckburgh, compofed of two ex- meafures. cellent microfcopes, the one bearing a micrometer which di- vides 24(5 COMPARISON OF THE FRENCH METRI vides the Englifh inch into ten thoufand equal parts. Upon his return to Paris he made hafte to exhibit thefe inftruments to the Minifter of the Interior, and to the National Ioftitute, .Comrr.Iffion of This learned body nominated three of its members, in order the French Na- . , . x, y , .r r A. 7 - 7, tionallnftitutc to proceed to the regular companion of the definitive metre for comparing, with the Englifh ftandard. The undertaking, by no means fo eafy as it at firft appeared, occupied the committee in five /different meetings, of nearly four hours each ; and it was per- formed with all the care and precaution that the nature of the i~ubje<5t required. Mr. Prony, who, as the tranflator of Ger neial Roy's memoir on the firft trigonometrical operations in England, was particularly interefled in thefe refearches, acted as fecretary to the Committee, and it was at his houfe, and with the afliftance of a comparative apparatus belonging to him, that the principal experiments were made. He has been fo obliging as to furnifh us with an authentic copy of the reV port made to the Inftitute, which was deemed of fufficientf confequence to be read at the public fitting of the laft quarter. He adds, that " This report will foon be followed* by a mer moir, in which he will enter into more circumftantial details of all the obfervations that he has made ; and in which he will give a defcription and a figure of his comparative inftrument." We /hall bear in mind this promife, and in the mean time we Jhall give our readers a copy of the report ; informing them that we have beftowed on the correction of the proofs of this important paper all the attention neceflary to enable us to af- firm that no typographical error has been committed in the numbers. National Inftitute of Sciences and Arts. 6 Nivofe, Year 10 (21th December, 1801 J Report of the A member read, in the name of a committee, the follow- Inftitute. jng report on the comparifon of the ftandard metre of the Inftitute with the Englifh foot. M. Piftet, Profeflbr of Natural Philofophyat Geneva, fub- mitted to the infpeclion of the clafs in the month of Vende- miaire, an injerefting collection of objects relative to the fci- ences and arts, which he collected in his journey to England. Engfift ftandard Among them was a ftandard of the Englifh linear meafure, • finches, engraVed on a fcale of brafs, of 49 inches in length, divided by very fine and clear lines into tenths of an inch, * ■ ■ ■ It WITH THE ENGLISH STANDARD. 24,T It was made for M. Pi&etby Troughton, an artiit in Lon- made by Trough- don, who has defervedly the reputation of dividing inftru-Mru ments with fingular accuracy ; it was compared with another ftandard made by the fame perfon for Sir George Shuckburgh, aad it was found that the difference between the two was not greater than the difference between the divifions of each ; that is, it was a quantity abfolutely infenfible. This ftandard may therefore be confidered as identical with the ftandard defcribed by Sir George Shuckburgh in the Philofophical Tranfactions for 1798. M. Pi&et alfo exhibited to the Inftitute a comparer, or an Inftrument of inftrument for afcertaining minute differences between mea- j^^J^ m]Crof- fures, conftrucied alfo by Mr. Troughton. It confifts of two copes, microfcopes with crofs wires, placed in a vertical (ituation, ihe furface of the fcale being horizontal, and fixed at proper diftances upon a metallic rod. One of them remains ftation- ary at one end of the fcale, the other is occafionally fixed near to the other end ; and its crofs wires are moveable by means of a fcrew, defcribing in its revolution -j-^ of an inch, and fur- niihed with a circular index, dividing each turn into 100 parts ; fo that having two lengths which differ only one tenth of an inch from each other, we may determine their difference in ten thoufandths of an inch. The wires are placed obliquely with refpecl to the fcale, fo that the line of divifion muft bifect the acute angle that they form, in order to coincide with their interfeciion. General Roy has defcribed, in the 75th volume of the Philofophical Tranfactions, a fimilar inftrument made by Ramfden, for meafuring the expanfion of metals. M. Pi&et offered to the clafs the ufe of the ftandard, with the micrometer defcribed, for the determination of the com- parative length of the metre, and the Englifh foot : the offer was accepted with gratitude, and M M. Legendre, M^chain, and Prony, were appointed to co-operate with M. Piclet in the comparifon of the ftandard metre of platina and the Englifh foot. The firft meeting was on the 28th Vende'miaire (21ft of Firft meeting of Oftober,) at the houfe of Mr. Lenoir. the commiflion. At firft a difficulty occurred from the different manner in Difficulty to which the meafures were defined : the Englifh fcale was gra. compare the duated by lines ; the French ftandards were fimply formed tograduated by the length of a metre ; hence the length of the metre could not h^es, and the ri French, which ea% is of the prscife 248 COMPARISON OF THE FRENCH METRE length without graduation* Method by an intermediate piece. eafily be taken by the microfcopes ; nor could the Engliih. fcaJe be meafured by the method employed for making new flandard metres, which confifts in fixing one end againft a firm fupport, and bringing the other into contact with the face of a cock or Aider, adjufted fo as barely to admit the original ftandard between it and the fixed furface. Mr. Lenoir attempted to overcome this difficulty by reducing to a thin edge the terminations of a piece of brafs of the length of a metre ; fo that it was compared with the flandard metre in the ufual manner, and its extremities, when placed on the Engliih fcale, confhtuted two lines parallel to thofe which were really, engraved on the fcale, and capable of being viewed by the microfcopes. The flandard metre of platina, and another flandard of iron, belonging aifo to the Inflitute, were thus compared with the Englifti foot ; each of thefe two meafures being equal, at the temperature of melting ice, to the ten millionth part of the quadrant of the meridian. At the temperature of 15.3° of the decimal thermometer, or 59.5° of Fahrenheit, the metre of platina was equal to 39.3775 Englifh inches ; and that of iron to 39.3788, meafured on M. Picket's fcale. Thefe firfl experiments, fhowed, however, that the method employed was liable to fome uncertainty, arifing from the dif- ficulty of placing the crofs wires precifely at the extremity of the thin edge of the plate of brafs employed in the comparifon ; a reflection or irradiation of light, which took place at that extremity, prevented its being diftinctly obferved if the opti- cal axis of the microfcope was precifely a tangent to the fur- face exactly at the termination. Accurate method In order to remove this inconvenience, another arrange- of comparifon ment was propofed by one of the Committee. (It was Mr. a^ufe^cfrrving Pronv that frggefled this ingenious method, and M. Paul of a line was caufrd Geneva, who happened to be prefent, that executed it. B.B.) them0rVccifer0U8h A line was traced on a fma11 metalIic ruler> perpendicular to length of the its length ; the end of the ruler was fixed againft a folid ob- metre;.unlcr the flacle, and the crofs wires made to coincide with the line: the flandard metre was then interpofed between the fame ob- flacle and the end of the piece, and the line traced on it, which had now obvioufly advanced the length of the metre, was fubjecled to the other microfcope. To the microfcopes thus Experimental comparifon by this method. Refult, in fome refpe£ts uncertain. microfcopes. WITH THE ENGLISH STANDARD.. 249 thus fixed, the graduated fcale was transferred ; one of the divifions was placed exactly under one of the micrpfcopes, and the micrometer fcrew was turned in order to meafure the fraction, exprefling the diftance of the other microfcope from another divifion. The comparifon was repeated in the fame manner the 4th Precife refult at Brumaire (26th Odober laft) at the houfe of one of the Com-^t#ofF'hrcn" mittee, and after feveral experiments, agreeing very fatisfac- torily with each other, it was found that at the temperature 12.75° centigrade, or 55° of Fahrenheit, the ftandard of pla- tina was 39.3781, and that of iron 39.3795 Englifh inches. The two metres being conitru£ted to be equal at the tempe- Reduction to the rature of melting ice, thefe operations may be verified by re- ten?p.erat.ure of ducing their refults to that temperature. For this determina- tion we are provided with the accurate experiments made by Borda, and the committee of weights and meafures, on the dilatation of platina, brafs, and iron ; from which it appears, that for every degree of the decimal thermometer, platina ex- pands .00000856; iron .00001156; and brafs .00001783; (for Fahrenheit's fcale thefe quantities become 476, and 642, and 990 parts in an hundred millions.) From thefe data we find that, at the freezing point, the ftandard metre of platina was equal to 39.38280, and that of iron to 39,38265 Englifh inches of M. Pi&et's fcale. The difference is lefs than the 500th of a line, or the 200000th of the whole metre, and is therefore wholly inconfiderable. The refult of the whole comparifon is therefore this. Sup- Standard metre pofing all the meafures at the temperature of melting ice, each at 3* ls — of the ftandard metres is equal to the 10000000th part of the lift inches. quadrant of the meridian, and to 39.38272 Englifh inches of M. Pidet's fcale. At the clafs of mathematical and phyfical fciences of the National Inftitute, 6 Nivofe, year 10. Legendre, Mechain, and Prony, Reporter. This report is approved, and its conclufions adopted by the clafs. Certified in conformity with the original by Delambre. Paris, 26 Nivofe, year 10 (16th January, 1802). [The reft of this Paper if by the learned Secretary to the Royal Inftitution, Dr. Young.] On examining the reduction of the ftandards of platina and Revifion by Dr, iron to the freezing point, it appears that they differ fomewhat YounS» lefs 250 COMPARISON OF THE FRENCH METRE lefs than is ftated in the report, and that they coincide within an unit in the laft place of the decimals exprefhng their magni- tudes, or one ten thoufandth of an inch. The ftandard of pla- tina at the freezing point becomes equal to 39.37380, and that of iron to 39.37370 Englifh inches on the fcale of brafsat 55°, and the mean of thefe to 39.37100 Englifh inches at 62°, which is the temperature that has been univerfally employed in the comparifon of Britifh ftandards, and in the late trigo- nometrical operations in particular. This refult agrees fur- prifingly with Mr. Bird's determination of the lengths of the toifes fent by Mr. Lalande to Dr. Mafkelyne, of which the mean was 76.734 inches : hence the metre, having been found to contain 36.9413 French inches, appears to be equal to 39.3702 Englifh inches : or rather to be either 39.3694 or 39.3710, accordingly as the one or the other of the two toifes happens to have been the more correct ; we may therefore give the preference to that which meafured 76.736 inches. Allowing the accuracy of the French meafurements of the arc of the meridian, the whole circumference of the globe will be 24855.43 Englifh miles, and its mean diameter 7911.73. Taking the ellipticity at ^\^, the axis will be nearly 7893§, the equatorial diameter 7928, and the diameter of a fphere of equal folid content about 7916 miles ; the brafs flandard being at the temperature of 62° of Fahrenheit. Standard metre As long, therefore, as the Englifh flandard continues to be at 620. reduced to this temperature, we rauft confider the metre as equivalent to 39.3710, and not to 39.3827 Englifh inches. Upon thefe joint authorities it may be of ufe to reprint here a table of the principal meafures and weights now ufed in France, with the very flight corrections which this laft com- parifon has introduced into it. In tranflating the French terms into Englifh, we are fully at liberty to refcue them, in fome meafure, from the barbarifms in orthography which have been committed in forming them. Meafures of length, the metre being at 32°, the foot at 62°. Englifh inches. French meafures Millimetre .... .03937 ofIcngth' Centimetre .39371 Decimetre ----- 3.93710 Metre WITH THE ENGLISH STANDARD. 251 Metre - 39.37100 Decametre - - - 393.71000 Hecatometre .... 3937.10000 Chiliometre .... 39371.00000 Myriometre - - - 393710.00000 M. F. Y. Ft. In. A decametre is - - - 0 0 10 2 9.7 A hecatometre - - - -00109 11 A chiliometre 042131 10.2 A myriometre .... 61 156 O 6 8 chiliometres are nearly 5 miles. Meafures of capacity. Cubic Inches E. Millilitre - - - - - - .06103 of capacity. Centilitre .61028 Decilitre - - - - - - - 6.10280 Litre, a cubic decimetre - - - ' - 61.02800 Decalitre - -". - - - 610.28000 Hecatolitre - - - - - 6102.80000 Chiliolitre - - - - - - 61028.00000 Myriolitre - - - - - 610280.00000 A litre is nearly 2-f- wine pints. 14- decilitres are nearly 3 wine pints. A chiliolitre is 1 tun, 12.73 wine gallons. Weights. A gramme is the weight of a cubic centimetre of pure Weights, water at its maximum of denfity. It has been found equal to 18.827 French grains, of which 576 made 472.5 Englifh; and 489.5058 grammes make a pound of the itandard of the mint at Paris. » £. grains. Milligramme - - - » - • .0154 Centigramme . - - - .1544 Decigramme ------ 1.5444 Gramme .---.«.- 15.4440 Decagramme ..--«- 154.4402 Hecatogramme - - - - 1544.4023 Chiliogramme ------ 15444.0234 Myriogramme - 154440.2344 A deca- 252 COMPARISON OF THE FRENCH METRE A decagramme is 6 dwts. 10.44 gr. tr. ; or dr. iifl. gr. 4.41- apoth. ; or 5.65 dr. avoird. A hecatogramme is 3 oz. 8.5. dr. av. A chiliogramme is 2lbs. 3 oz. 5 dr. av. A myrio- gramme is 22!bs. 1.15 oz. av. 100 myriogrammes are 1 ton wanting 32.8lbs. Agrarian meqfures. Agrarian mea- Are, 1 fquare decametre - 3,95 perches. Hecatare 2 acres, 1 rood, 35.4 perches. lures, for fire-wood. Deciftcre, Yl- flere » T^ Money. Stere, 1 cubic metre Centime, 1 gramme 5 centimes, or fous - Decime 2 decimes For jire-icood. ... 3.5317 cub. f. E. - 35.3171 cub. f. oney. Copper. E. grains. - 15.4 - 77.2 - 154.4 . 308.8 Silver -j% or I4./&*. Franc, 5 grammes, .... 3 dwts. 5.2 gr. 6 francs, - 16 dwts. 2.1 gr. The franc is nearly the fame with the livre tournois, and worth about lOd. Bolton's penny weighs 435 gr. ; his half- penny 165 ; a milling nearly 93 gr. and is |£ fine. Length of It appears from Mr. Borda's experiments, that in latitude pendulum, &c. 450^ a pendulum of the length of a metre would perform in a vacuum 861 16.5 vibrations in a day : the length of a pendu- lum being fuppofed to increafe with the latitude, in the pro- portion of the fquare of the fine of the latitude, multiplied by £)Q0567, while the time of its vibration remains unaltered. Y. VIII. On ON THE FIGURE OK SULPHATE OF BARYTES, &C. 253 VIII. On the Figure of Sulphate of Barj/tcs, and the Formation pf Mandreporte. In a Letter from Mr. H.Sarjeant^ To Mr. NICHOLSON. SIR, I F the following mineralogical notices appear to contain any thing worthy of attention, they are at your fervice, from Your humble fervant, Kefwich,July 16*, 1802. H. SARjEANT. THE barytes, or ponderous earth, occurs in a great variety of forms : one of the rareft is defcribed as " refembling a nnm- , faw it fall, near Wold Cottage, in Yorkfhire, at about three o'clock in the afternoon. It had penetrated through 12 inches of foil and 6 inches of folrd chalk rock ; and m burying itfelf, had thrown up an immenfe quantity of earth, to a great diftance : as it fell, a number of exploftons were heard, about as loud as piftols. In the adjacent villages, the founds heard were taken for guns at fea ; but, at two adjoin- ing villages, were fo diftinc~t Of fomething lingular paffing through the air, towards the habitation of Mr. Topham, that five or fix people came up, to fee if any thing ex- traordinary had happened to his houfe or grounds. When the ftone was extracted, it was warm, fmoaked, and fmelt very ftrongly of fulphur. Its courfe. as far as could be col- lected from different accounts, was from the fouth-weft. The day was mild and hazy, a fort of weather very frequent in the Wold hills, when there are no winds or ftorms ; but there was not any thunder or lightning the whole day. No fuch ftone is known in the country. There was no eruption in the earth ; and, from its form, it could not come from any building ; and, as the day was not tempeftuous, it did not feem probable that it could have been forced from any rocks, the neareft of which arethofe ofHamborough Head, at a diftance of twelve miles.* The neareft volcano, I believe to be Hecla, in Iceland. The exhibition of this ftone, as a fort of fhow, did not tend to accredit the account of its defcent, delivered in a hand-bill at the place of exhibition ; much lefs could it contribute to re- • Extracted from the printed paper delivered at the place of exhibition. move FALLEN ON THE EA-RTtf. 255 move the objections made to the fall of the ftones prefented to the Royal French Academy. But the Right Hon. prefident of the Royal Society, ever alive to the intereft and promotion of fcience, obferving the ftone fo exhibited to refemble a ftone fent to him as one of thofe fallen at Sienna, could not be miflecl by prejudice; he obtained a piece of this extraordinary mafs, and collected many references to defcriptions of fimilar phe- nomena. At length, in 1799, an account of ftones fallen in the Eaft Indies was fent to the prefident, by John Lloyd Wil- liams, Efq. which, by its unqueftionable authenticity, and by the finking refemblance it bears to other accounts of fallen ftones, muft remove all prejudice, Mr. Williams has fince drawn up the following more detailed narrative of facts. Account of the Explofion of a Meteor, near Benares, in the Eaft Explofion of a ladies; and of the falling of fome Stones at the fame Tinte,™^'™™^ about 14 Miles from that City. By John Lloyd Williams, falling of fome Efq. F. R. S. ftones at the fame time. A circumftance of fo extraordinary a nature as the fall of nones from the heavens, could not fail to excite the wonder, and attract the attention of every inquifitive mind. Among a fuperftitious people, any preternatural appearance is viewed with filent awe and reverence ; attributing the caufes to the will of the Supreme Being, they do not prefume to judge the means by which they were produced, nor the purpofes for which they were ordered ; and we are naturally led to fufpect the influence of prejudice and fuperftition, in their defcriptions of fuch phenomena ; my inquiries were therefore chiefly di- rected to the Europeans, who were but thinly difperfed about that part of the country. The information I obtained was, that on the 19th of De- Narrative, cember, 1798, about eight o'clock in the evening, a very lu- minous meteor was obferved in the heavens, by the inhabitants of Benares and the parts adjacent, in the form of a large ball LarSe .bal1 °f of fire; that it was accompanied by a loud noife, refembling ^g thunder. thunder ; and that a number of ftones were faid to have fallen from it, near Krakhul, a village on the north fide of the river Goomty, about 14 miles from the city of Benares. The meteor appeared in the weftern part of thehemifphere, and was but a fhort time vifible ; it was obferved by feveral Europeans, as well as natives, in different parts of the country. In 25G ON STONV AND METALLINE SUBSTANCES. In the neighbourhood of Juanpoor, about 12 miles from the fpot where the Hones are faid to have fallen, it was very dii- tin&Iy obferved by feveral European gentlemen and ladies who defcribed it as a large ball of fire, accompanied with a loud rumbling noife, not unlike an ill difcharged platoon of mufquetry. It was alfo feen, and the noife heard, by various Degree of light, perfons at Benares. Mr. Davis obferved the light come into *c- the room where he was, through a glafs window, fo ftrongly as to project fliadows, from the bars between the panes, on a dark coloured carpet, very diftinclly; and it appeared to him as luminous as the brighteft moonlight. Investigation on When an account of the fail of the ftones reached Benares, DwiiT ^ Mr' Mr* Davis' the JudSe and magiftrate of the diftria, fent an intelligent perfon to make inquiry on the fpot. When the per- fon arrived at the village near which the Hones were faid to have fallen, the natives, in anfwer to his inquiries, told him, that they had either broken to pieces, or given away to the Tefleldar (native collector) and others, all that they had picked up; but that he might eafily find fome in the adjacent fields, where they would be readily difcovered, (the crops being then not above two or three inches above the ground,) by obferving where the earth appeared recently turned up. Following thefe directions, he found four, which he brought to Mr. Davis : molt of thefe, the force of the fall had buried, according to a meafure he produced, about fix inches deep, in fields which feemed to have been recently watered ; and it appeared, from the man's defcription, that they mufl: have lain at the diflance of about a hundred yards from each other. Account by the What he further learnt from the inhabitants of the village, concerning the phenomenon, was, that about eight o'clock. in the evening, when retired to their habitations, they obferved a very bright light, proceeding as from the Iky, accompanied with a loud clap of thunder, which was immediately followed by the noife of heavy bodies falling in the vicinity. Uncertain whether fome of their deities might not have been concerned in this occurrence, they did not venture out to enquire into it un- til the next morning; when the firfl circumftance which at- tracted their attention was, the appearance of the earth being turned up in different parts of their fields, as before mentioned, where, on examining, they found the fiones. The FALLEN ON THE EARTH. $>5 7 The affiftant to the colleaor of the diitricl, Mr. Erfkine, a Inquiries by Mr. Very intelligent young gentleman, on feeing one of the ft ones, brought to him by the native fupermtendant of the collections, was alfo induced to fend a perfon to that part of the country,, to make inquiry ; who returned with feveral of the Hones, and brought an account fimilar to that given by the perfon fent by Mr. Davis, together with a confirmation of it from the Cauzy, (who had been directed to make the inquiry) under his hand and feal. Mr. Maclane, a gentleman who refided very near the vil- and Mr« Mac- lage of Krakhut, gave me part of a ftone that had been brought to him the morning after the appearance of the phenomenon, by the watchman who was on duty at his houfe ; this, he faid, had fallen through the top of his hut, which was clofe by, and buried itfelf feveral inches in the floor, which was of confoli- dated earth. The ftone mutt, by his account, previous to its having been broken, have weighed upwards of two pounds. At the time the meteor appeared, the Iky was perfectly fe- State of the wea- rene; not the fmalleft veftige of a cloud had been feen fince the 11th of the month, nor were any obferved for many days after. Of thefe (tones, I have feen eight, nearly perfect, betides Stones of this parts of feveral others, which had been broken by the pofTelTors, description to diftribute among their friends. The form of the more per- feen by tjle au_ feci ones, appeared to be that of an irregular cube, rounded tn<>r. off at the edges ; but the angles were to be obferved on mofl of them. They were of various fizes, from about three to Some account of upwards of four inches in their largcft diameter; one of them, t efame' meafuring four inches and a quarter, weighed two pounds twelve ounces. In appearance, they were exactly fimilar: externally,, they were covered with a hard black coat or in- cruttation, which in fome parts had the appearance of varnifh, or bitumen; and, on mod of them were fractures, which, from their being covered with a matter fimilar to that of the coat, feemed to have been made in the fall, by the ftones ftriking againft each other, and to have palled through fome medium, probably an intenfe heat, previous to their reaching the earth. Internally, they confided of a number of fmall fpherical bodies, of a ilate colour, embedded in a whitim gritty fubftance, interfperfed with bright fhining fpiculae, of a metallic or pyritical nature. The fpherical bodies were much Vol. IL— August, 1802. S harder *£5$ t>N STONY AND METALLINE STJBSTA#CI$ harder than the reft of the ftone: the white gritty part readily crumbled, on being rubbed with a hard body ; and, on being broken> a quantity of it attached itfelf to the magnet, but more particularly the outfide coat or cruft, which appeared almoft wholly attractable by it. The author de* As two of the more perfect ftones which I had obtained, as jefture^ COn" ^c^ as Parts °^ ^orne otners, have been examined by feveral gentlemen well verfed in mineralogy and chemiftry, 1 (hall not attempt any further defcription of their conftituent parts ; nor (hall I offer any conjecture refpecling the formation of fuch lingular productions, or even record thofe which I have heard of others, but leave the world to draw their own inferences from the facts above related. I fhall only obferve, that it is well known there are no volcanos on the continent of India; and, as far as I can learn, no ftones have been met with in the earth, in that part of the world, which bear the fmalleft refemblance to thofe above defcribed. Iron in the Bar- IT remains for me to fpeak of a fubftance mentioned in the {^tTh^hStnLithoPhyluchm B°™***W> Parti, page 125, defcribed thus i. m Bohemia. M Ferrum retra&orium, granulis nitentibus, matrice virefcenti " immixtis, (Ferrum virens, Linn.) cujus fragmenta, ab unius " ad vigenti ufque librarum pondus, cortice nigro fcoriaceo ** circumdata, ad Plann, prope Tabor, circuli Bechinenfis Bo- " hemiae, paflim reperiuntur." The iron thus defcribed, is moreover made remarkable by & note *, which obferves, that credulous people aflert it to have fallen from heaven during a thunder ftorm, on the 3d of July> 1753. The collection of Baron Born, it is well known, has a place in the cabinet of the Right Honourable Charles Greville, who, from the effect produced by comparing the hiftories and ftruc- ture of the Italian and Yorkfhire ftones with the defcription of this iron, was induced to fearch the collection of Born, where he difcovered the very fubftance aflerted to have fallen on the 3d of July, 1753. How far thefe four fubftances have refem- blance to each other, it will foon appear not to be my province to anticipate. * Quae (fragmenta) 3 Julii, anni 1753, inter tonitrua, e ccel* jpluiffe credulioies quidam aflerunu The FALLEN ON THE EARTH, 259 *The President having done me the honour to fubmit his Other ftones of L . , „ , L . , T ,. n • firailar origin, fpecimens of the Yorkfhire and Italian (tones to my examina- tion, I became indebted to Mr. Greville and Mr. Williams for a fimilar diftindtion : and, being thus, pofleffed of four fubftances, to all of which the fame origin had been attributed, the neceffity of defcribing them mineralogically did not fail to prefent itfelf. To execute this tatk, no one could be more eager, and certainly no one better qualified, than the Count de Bournon. He has very obligingly favoured me with the fol- lowing defcriptions. Mineralogical Defcription of the Various Stones /aid to have fallen upon the Earth. By the Count de Bournon, F. R. S. THE (tones I am about to defcribe, are not of any regular Count Bournon'* Hiape; and thofe which were found in an entire (tate, that is, tne varjous thofe which had not been broken, either by their fall or other- ftones. wife, were entirely covered with a black cruft, the thicknefs of which was very inconfiderable. The (tones which fell at Benares, are thofe of which the mineralogical characters are the mod linking : I (hall therefore begin the following defcription with them ; and (hall after- wards make ufe of them, as objects of companion, in defcribing the others. STONES FROM BENARES. Thefe (tones, as well as the others defcribed in this paper, Stones from whatever may be their fize, are covered over the whole extent b]er^res'>. . a of their furface with a thin cruft of a deep black colour : they rough like fifh have not the fmalleft glofs; and their furface is fprinkled over * with fmall afperities, which caufe it to feel, in fome meafure, like (hagreen> or fifh (kin. When thefe (tones are broken, fo as to (hew their internal Frafture ; coarfe appearance, they are found to be of a greyifh afh colour ; and SjTcoio'u?" of a granulated texture, very fimilar- to that of a coarfe grit- compofed of none : they appear evidently to be compofed of four different £)"# fubftances i fubftances, which may be eafily diftinguifhed, by making ufe of a lens. One of thefe fubftances, which is in great abundance, appears Opake gray glo- in the form of fmall bodies, fome of which are perfe&ly glo- cho!aat°ft^attft bular, others rather elongated or elliptical. They are of various and flight luftre, fizes, from that of a fmall pin's head to that of a pea, or nearly j^fwUhte"! k 2 fo : and abrading gbfej 260 Pyrites, not magnetical« Metallic malle- able iron* Whltifh gray, crumbly earth. The cruft Is probably black oxide of iron. ON STONY AND METALLINE SUBSTANCES fo : fome of them, however, but very few, are of a larger fize. The colour of thefe fmall globules is gray, fomclimcs inclining very much to brown: and they are completely opaque. They may, with great eafe, be broken in all directions : their fracture is conchoid, and fhews a fine, fmooth, compact grain, having a fmall degree of luftre, refembling in fome meafure that of enamel. Their hardnefs is fuch, that, being rubbed upon glafs, they act upon it in a flight degree; this action is fufficient to take off its polifh, but not to cut it: they give faint fparks, when ftruck with fleel. Another of thefe fubftances, is a martial pyrites, of an inde- terminate form : its colour is a reddilh yellow, ilightly inclining to the colour of nickel, or to that of artificial pyrites. The texture of this fubftance is granulated, and not very ftrongly connected : when powdered, it is of a black colour. This pyrites is not attractable by the magnet ; and is irregularly diftributed through the fubftance of the ftone. The third of thefe fubftances confifts in fmall particles of iron, in a perfectly metallic ftate, fo that they may eafily be flattened or extended, by means of a hammer. Thefe particles give to the whole mafs of the ftone, the property of being attractable by the magnet ; they are, however, in lefs propor- tion than thofe of pyrites juft mentioned. When a piece of the flone was powdered, and the particles of iron feparated from it, as accurately as poffible, by means of a magnet, they appeared to compofe about -^q of the whole weight of the ftone. The three fubftances juft defcribed, are united together by means of a fourth, which is nearly of an earthy confiftence. For this reafon, it is eafy to feparate, with the point of a knife, or even with the nail, the little globular bodies above mention* ed, or any other of the conftituent parts of the. ftone you may wifh to obtain. Indeed the ftone itfelf may readily be broken, merely by the action of the fingers. The colour of this fourth fubftance, which ferves as a kind of cement to unite the others, is a whitifh gray. The black cruft with which the furface of the ftone is coated, although it is of no great thicknefs, emits bright fparks, when ftruck with fleel : it may be broken by a ftroke with a hammer ; and feems to pofTefs the fame properties as the very attractable black oxide of iron. This cruft is, however, like the fubftance of the ftone, here and there mixed with fmall particles of iron in FALLEN ON THE EARTH. 26\ in the metallic ftate : they may eafily be made vifible, by patting a file over the cruft, as they then become evident, on account of their metallic luftre. This is more particularly the cafe with refpecl to the cruft of thofe ftones which remain to be mentioned, they being much more rich in iron than that I have juft defcribed; a circumftanee I think it needlefs to re- peat, in the following defcriptions of them. The ftone now treated of, does not, when breathed upon, emit an argillaceous fmell: the fame remark may be applied to all the others. The fpecific gravity of this ftone is 3352. STONE FROM YORKSHIRE, This ftone, the conftituent parts of which are exactly the Stone from fame as thofe of the ftones from Benares, differs from them, compofed'like however, the former; Firft. In having a finer grain. but. of finer t> o grain: Secondly. That the fubftance defcribed as being in the form The globules are of fmall globular or elliptical bodies, is not fo conftantly in thofe lefs reSular : forms, but is alfo found in particles of an irregular fhape; a circumftanee that is not met with in the other ftones: thefe bodies are likewife, in general, of a fmaller fize. Thirdly. The proportion of martial pyrites, which has pre- The pyrites in cifely the fame characters as that in the ftones from Benares, ^ th^ meuUic is lefs; on the contrary, that of the iron in a metallic ftate, is iron more, much greater. The quantity I was able to feparate by means of the magnet, appeared to me to compofe about eight or nine parts, in one hundred, of the weight of the whole mafs. I obfervedmany pieces of this iron, of a pretty considerable fize; one of them, taken from a portion of the ftone I had powdered, in order to feparate the iron, weighed feveral grains. The part of the ftone which is in an earthy ftate, and which Its earthy part h ferves to connect the other parts together, has rather more conftftence than that of the preceding ftones; and its appear- ance does not differ much from that of decompofed felfpar or kaolin. The ftone itfelf, therefore, although by no means hard, is rather more difficult to break with the fingers. The fpecific gravity of this ftone is 3508. It is denfer. STONE FROM ITALY. This ftone was in a perfectly entire ftate; confequently, its Stone from Italy, whole furface was covered over with a black cruft peculiar to all - 2(52 coarfe grained j compofed nearly like the others. It contained a yellow tranfpa- rent globule, fofrerthancalca reous fpar. Stone from Bo- hemia. Com- pofed like the preceding } but its pyrites very minute ; the quantity of metallic iron much greater j ON STONY AND METALLINE SUBSTANCES all ftones of this kind. As the ftone was of a very fmall fize.^ it became neceflary to facrifice the whole of it to the inveftn gation of its nature. Its grain was coarfe, fimilar to that of the flones from Benares: in it might be perceived the fame gray globular bodies, the fame kind of martial pyrites, and the fame particles of iron in the metallic flate. The proportion of thefe laft: was much lefs than in the ftone from Yorkshire ; but rather greater than in the ftones from Benares. The fame kind of gray earthy fubftance ferved to connect the different parts together; and nothing more could be perceived, except a few globules, which confifted wholly of black oxide of iron, attractable by the magnet, and one {ingle globule of another fubftance, which appeared to differ from all thofe we have • already defcribed. This laft fubftance had a perfectly vitreous luftre, and was completely tranfparent : it was of a pale yellow colour, flightly inclining to green; and its hardnefs was rather inferior to that of calcareous fpar. The quantity of it, however, was too fmall to be fubmitted to fuch an inveftigation as might have determined its nature. The black cruft which covered the ftone, was rather thinner than that of the ftones already defcribed ; and feemed to have undergone a kind of contraction, which had produced in it a number of fiflures or furrows, thereby tracing upon the furface the appearance of compart- ments, fimilar in fome meafure to what is obferved in thq ftones called Septaria. The fpecific gravity of this ftone was 3-HS. STONE FROM BOHEMIA. The internal ftruclure of this ftone is very fimilar to that of the ftone from Yorkshire. Its grain is finer than that of the ftones from Benares : in it may be obferved the fame gray fub- ftance, both in fmall globules and in particles of an irregular fhape; alfo the fame particles of metallic iron. The fame kind of earthy fubftance likewife ferved to connect the other parts together. This ftone, however, differs materially from the others. Firft. The particles of pyrites cannot be (een without a lens. Secondly. It contains a much larger quantity of iron in the metallic ftate ; infomuch, that the proportion of that metal, feparated from it by means of the magnet, amounted to about 1$ To-5 of the weight of the whole. This FALLEN ON THfi EARTH. g$3 This ftone has alfo (owing perhaps to its having remained a31*^0*60*^*^ much longer time in the earth than the preceding ones, all of which were taken up nearly at the very inftant of their fall) another difference, viz. many of the particles of iron in a metallic ftate, have undergone an oxidizement at their furface ; a circumftance that has produced a great number of fpots, of a yellowifii brown colour, and very near to each other, over a part of its internal fubftance. This oxidizement, by adding to the bulk, and to the force of action, of the part we have de- fcribed as ferving by way of cement to the other conftituent parts of the ftone, has occafioned a greater degree of adhefion between thefe parts, and has rendered the fubftance of the ftone more compact. The great quantity of iron in a metallic ftate which this It is harder, ami ftone contains, added to its greater compaclnefs, makes jtad!?!£s a fllgh* capable of receiving a flight degree of polifii ; whereas it is im- poffible to give any polifh to the others. When polifhed, the iron becomes very evident, in the polifhed part; appearing in the form of fmall fpecks, almoft clofe to each other, which have the colour and luftre peculiar to that metal ; thefe fpecks are, in general, nearly of an equal fize. The black cruft of this ftone is fimilar to that of the others. The fpecific gravity of the ftone is 4281. It is eafy to perceive, from the foregoing defcription, that Thefe floras are thefe ftones, although they have not the fmalleft analogy n"c in the fmalu with any of the mineral fubftances already known, either of a gous with any " volcanic or any other nature, have a very peculiar and ftriking ot.Jler know« analogy with each other. This circumftance renders them truly worthy to engage the attention of philofophers ; and naturally excites a defire of knowing to what caufes they owq iheir exiftence. (To be continued.}, X. 4* 2G4f THEORY OF COMPOUND SOUNDS, An Anfiuer to Air. Cough's llffay on the Theory of Compound Sounds, fij/ Thomas Young, M. D. F. R. S. To Mr. NICHOLSON. SIR, nmkf a°ryrC" •* HAVE already made public, through the medium of your ufeful Journal, one vindication of my remarks upon Dr. Smith's Harmonics ; and I fhall now beg you to infert fome further obfervations upon a fubject nearly fimilar. I do not think myfelf bound to reply to all the arguments that may happen to be advanced again (I any of my opinions; but when they come from perfons of literary refpeciability, and efpecially when they convey an imputation of having detracted from the me- rits of others, I cannot forbear attempting to anfvver them; and in the prefent inflance a very few words will be fufficieni for the purpofe. Mr. Gough has published in the .lad volume of the Manchester Memoirs, a paper in which he profeffes to defend Dr. Smith's opinions againft mine : but he has unfor- tunately fo far miftaken the queftion between us, thai with refpect to the principal circumftanees, while he imagines he is confuting me, he is completely on my fide. The author's in- Proceeding upon the grounds. of the well known facls rela- itrerices from ^lVQ ^Q ^e o-rave harmonics, or the third founds produced by coalefcence of O in. undulations as the coalelcence of two others, as well as upon the allowed to the do&rmes principles of the compofition of motion, I had drawn a num- ligbt, fcarcely De*" °f inferences, which appeared to be of fome importance to be called a jn the firft place with refpect to the do&rine of found, and ory* which have fince furnifhed me with ft ill more interefting con- clusions with regard to light, I was not aware that there was any probability of the juilice of my inferences being difputed, or that there was fo much novelty in the mode of obtaining them, as to deferve the name of a theory or an invention : but if it be deemed otherwife, I (hall always be ready to ac- knowledge the invention with fatisfaction, and to fupport the theory with alacrity. Dr. Smith jma- I fhall now quote the words of Dr. Smith, which gave rife undulations in " t0 m^ animadverfions ; and this Statement is the more necef- fary, THEORY OF COMPOUND SOUNDS. 265 *ary, as I before omitted to detail the particulars of that au- air or in water trior's mifconception, and as Mr. Gough appears wholly to "°fs each otherj i 111, ^-^ • i r i • different part j- have overlooked the paflage. " Different particles ot the air cies 0f the nl,;,i at the ear" favs Dr. Smitth, " will keep moving conftantly were at the fame /». * A & r ,. a a • i* n -i • tlme moved inter oppofite ways at the tame time. And m lo rare a fluid as airye> accor{jing t0 is, where the intervals of the particles are eight or nine times the refpedtivc greater than their diameters, there feems to be room enough un u aaons* for fuch oppofite motions without impediment : efpecially as we fee the like motions are really performed in water, which in an equal fpace contains eight or nine hundred times as many fuch particles as air does. For when it rains upon flagnating water, the circular waves propagated from different centres, appear to interfecl, and pafs through, or over each other, even hi oppofite directions, without any vifible alteration in their circular figure, and therefore without any fenfible alteration of their motions." Harmonics, 1759, p. 105. It certainly would have " coft me an effort of ftudy" to de- Whereas the monftrate this, although I could not exadly confider it as the f*™j^f' °uual " intuitive conclufion of a comprehenfive mind." Such a fluid receive and mind appeared to me to comprehend with equal eafe the dif- trar>fait both tinct and the confuted ; and I am only at a lofs to conceive how the writer of this paflage could ever have compofed a valuable treatife on optics. Mr. Gough's theory differs as widely from this flatement as mine does. My remark on it was this ; " It is furprifing that fo great a mathematician as Dr. Smith could for a moment have entertained an idea, that the vibratious conftituting different founds, fhould be able to crofs each other in all directions, without affecting the fame individual particles of air by their joint forces : undoubtedly they crofs, without difturbing each other's progrefs ; but this can be no other wife effected than by each particle's partaking of both motions. If this affertion flood in need of any proof, it might be amply furnifhed by the phenomena of beats, and of the grave harmonics obferved by Romieu and Tartini, which Mr. Lagrange has already confidered in the fame point of view." Phil. Tranf. 1800, p. 130. I have no objection to admitting the whole of Mr. Gough's Sounds may coa* propofitions, in the particular cafes which he has confidered • k.ice wh'ch ar" r r ' l " rive at the ear but when he fays that the coalefcence of two founds is impof- in the fame dU fible on mechanical principles, he thinks proper to omit the rectionj only cafe in which I had afferted its exifience, that is, when 2 the C2GG THEORY OF COMPOUND SOUNDS. ihc founds arrive at the ear " in the fame direction." p. 1:31. Surely Mr. Gough will not deny the poflibility of fuch a co- incidence in direction, fo far at leaf! that the phyfical effefi may be the fame as if the coincidence were perfect : when, for in fiance, we Men to two or more founds palling through a long tube, or to the various fubordinate founds of the fame chord or pipe. If he be actually difpofed to deny the perfect coincidence in practical cafes, I (hall only appeal to experi- ence, which (hows that the effect of a third found is raoft dif- tinctly heard, whenever the theory leads us to expedt it ; but there will always be a much greater portion of each found fo reflected from the furrpunding objects as not to coincide in direction fufficiently for coalefcence, and hence the original notes will always be much more audible than the new com- pound. The ear indeed appears to have greater powers of analyfis than one would naturally have expected, it decom-, pofes a " compound" juft as if it were a mere M mixture/' not only in this cafe but in many others : how it performs this not by lofmg operation, I do not pretend to determine. When Mr. Gough their refpeftive reprefents me as maintaining that two mufical firings, differ-. tones in one fin- ... . r . . .. . , . . ., g!e found; but i.ng in, the times of their vibration, and happening to vibrate m by producing an concert, do no.t occafion two diftinct founds, and that the Jr found. * waves of air are compelled by their mutual interference ta coalefce, thereby producing a new fucceffion of pulfes, con- fiituting a fmgle found in the place of the former ; his expref, lions tend to impute to me an opinion which could only be. maintained by a perfon who had never heard a fingle mufical compofition, or ever been prefent a,t the. converfation of a, mixed company. All imperfe£l I am not folicitous for the application, of the term compound by coalefcence, to the human Voice ; but Mr. Gough can fcarcely form to himfelf a diflinct conception of it, very dif- ferent from mine. A mixture of imperfect uniibns would in- evitably be accompanied by the production of beats; and if he alfert that the imperfection is too fmall to produce this effect, I will only requeft him to. affign any reafonable limit to its. magnitude, and by producing the note long enough, I will (how that a beat muft neceflarily enfue. Perhaps a wifh to retain the Newtonian theory of the law of the undulations may. have led him into thefe fuperfluous refinements, M unifons muft produce beats COMPOUND SOUNDS, &0. 2(57 If Mr. Gough will take the pains of examining the pheno- The phenomena plena of the grave harmonics, which he feems to have hitherto monjcs ^ew ** thought beneath his notice, he will be convinced that the coa- that mufkal lefcence of mufical founds is not only poflible, but of very fre- j^nn^ous^ quent occurrence, and that the compound found does actually fiances. " acquire fenfible properties peculiar to itfelf;" and if he will explain, in any other manner than I have done, the indubita- ble fa6t of the audible impreffion of the prefence of the fourth below the key, in confequence of the coexiflence of the fouuds conftituting the interval of a major third, even when both the notes are freed from their harmonics, and when all echo is avoided ; I (hall then liiten to him, with the attention due to a perfon who endeavours to regulate his arguments by there? fclts of accurate obfervation. I am, Sir, with great refpeft, Your obedient humble Servant, XHQMAS YQUNG. Royal Inflitution, May 30, 1802. CORRECTION. In your fifth volume (quarto) p. 166, 1. 20, for " a better third than that," read, " equal to the third." The following CORRECTIONS made by Dr. Young in his Paper on the Meehanifm of the Eye, which is injcrted in our fifth volume (Quarto Series) ivere omitted to be mqfr in their proper places. Page 256, line 6, Prop. III. after e, infert the. bafe being unity.. Page 257, line 15, Cor. 10. for ntu, read n 1 1 j line 16, for produft &c. reqd fquare of the collne of incidence. Page 258, line 2, Cor. 1 1 . for 1 -f u7- — 2 «+, read 2 muu. Page 258, Prop. V. Cor. See the note in p. 299. |>age 259, Prop. VIII. By a miftake of a fign, the eighth propo- fition is rendered erroneous ; no ufe having been made of that pro- pofition, it has been inferted without proper revifion. It ought to $and thus, with its demon ftration : Proposition VIII. Problem. To find the path of a ray of light falling obliquely on a fphere, of a refractive denfity varying as any power of the diftance from the <#ntre. The 2 of which r the fluent is — -^- Y,_y being the fine of the arc Y ; and the angle correfponding is Y. The value of that angle being found for any two values of xory, the difference is the intervening angle de- fcribed by the radius. This angle is therefore always to the dif- ference of the inclinations as r to r — 1, and the deviations is to that difference as 1 to r — 1 . Corollary. Hence, in the paffage to the apfis, and the return to ♦he furface, the deviation is always proportionate to the arc cut off by the incident ray produced : therefore fuch a fphere could never collect: parallel rays to any focus, the lateral denfity being too fmall towards the furface. Page 259, line 9, for but the two laft, &c. read the feventh may either be deduced from the eighth, or may be demonftrated inde- pendently of it. Page 264, laft line, after internally, infert Or, if a lens of equal mean dimenfions, and equal focal length, with the cryftalline, be fuppofed to confift of two fegments of the external portion of fuch a fphere, the refractive denfity at the centre of this lens mull be as 18 to IT. XI. Experiment* ON THE VELOCITY OF A I It. 2'79 XI. Experiments on the Velocity of Air iJJ'uing out of a Vejfel in different Circumjlances; teith the Defcription of an lnjlrumenl to meafure the Force of the Blafi in Bellows, Syc. By Mr .Banks, Lecturer in Natural Fhilofophy *. JL HE object of this inquiry may be announced in the fol- Propofitlon. To lowing; proportion: If an elaftic fluid is generated in a given determi|ie ,tne m i • ... .„. . mechanic tores veflel, or any way contained in it, and at liberty to mueout of the er reaction of aa laid veflel through a given aperture/ to determine the refi fiance ^Ia.ftic Spouting which the veflel meets with from its action, or the power which it has of communicating motion to the veflel, as in a (ky-rocket, Sadler's fieam engine, &c. Before we proceed to relate the experiments, it may be All uniform proper to premife certain principles deduced from theory. If ^ l^^ow f't0m a tube be filled with any kind of fluid, as air, ivater, mercury, the fame velocity &c. and placed in a vacuum, every fluid will flow out with the* .vff*^ lf the* fame velocity. For though the preflure of a column of mer- however differ-' cury of a given altitude be much greater than an equal column enc their denfi- of water, yet the weight of the particles to be projected is greater in the fame ratio. On the other hand, if air is lighter than water, the particles projected are alfo lighter in propor- tion. If a tube of 16 feet high be filled with air of any den- fity, that air, like water, would flow into a vacuum with a velocity of 32 feet per fecond, no corrections being made for reflftancef. And if we take the gravity of air to water as 1 to 840, then Equal velocities a column of one foot of water comprefling air, will produce as™111 be produced great a velocity in that air as a column of air 840 feet high, ^^ by the fuppofing it was of uniform denfity. preflure of an- If we take the whole preflure of the atmofphere equal tonight of the 53 feet of water, or its height (fuppofing it to be equally denfe, former to that of the latter, » From the Manchefter Memoirs, Vol. V. p. 398. ^ JjJJJ1*3' as T In the fuppofition of a perpendicular tube open at the top, filled with air or any elaftic fluid, the author takes the denfity of the co- lumn at the bottom, or where the aperture is made, to arife folely from the weight of the elaftic column j and the altitude to be that which would be if the whole column were reduced to the denfity of that at the bottom. which 270 ON THE velocitV of air The atmofphere which in this cafe will make no difference) equal to 33 muUi- preijes equal to Iied fa g4Q QJ. 2?72() feefc thfe aJ. th f rQot f J g • £ 3 3 feet of water, r . ' ' ~ or 27720 feet of 32, the velocity at the depth, fo is the fqiiare root of 27720 to air. It would j 332 feet per fecond, the initial velocity df the atmofphefe iri- therefore propel l J * air into a va- lo a vacuum. cuum with the To prove whether air cdmprefled by 33 feet of water wduld thisfaU: viz. De impelled into the atmofphere with the above velocity, I ^/i6 ^27720 have made, amongft many more, the following experi- :: 32 feet: 1332 ments . feet per fecond. • . ^ j,. ^ r i ' ' «J Experiments. A> plate xiv. fig. 1 *> is a veflel of a known capacity, into Air is cdmpief. ^he top of which is fcrewed an aperture of a known area. by a known The tube 7V/, recurve at d, is foldered or fcrewed into the height of water : top of the faid veffel. The hole a is flopped, and water poured into the tube at T till it is full, at which time a quantity of water will have palled out of the tube ate?, and condenfed the air in the veflelj more or lefs as the tube T d is longer or fhorter. and fuffered to At this time a perfon who has clofed the aperture at a with iflue through an a finger 0f one hand, and held a half fecond pendulum in the known dimen- other, removes both at the fame time, while at the fame mo- fions. Its ve- ment an atfiftant opens a cock over the tube T, which fupplies fron?the quan" ** w*tn water as ^ as ^ can defcend into A. The moment tity and the that the water appears at a, the time-piece is flopped, and the time of expelling the air is noted, from which, by knowing the capacity of the veflel, the velocity may be obtained. If the tube Td fliould be continued near the bottom of the veflel A while it was filling with water, the length of the com- pelling column would be gradually diminifhing, and of confe* quence the preflure would be conftantly changing; hence the open end of the tube is as near the top of the veflel as is confif- tent with a free paflage for the water. EXPERIMENTS. The veflel A contained 15 lb. 6 oz. of water, from which we find its capacity is 425.088 cubic inches. The area of the aperture a, through which the air is expelled, .0046 inches. * There being no figure in the Tranfa&ions, I have inferted the drawing referred to. N, Expert EXTRUDED BY PRESSURE. <£-j t Pa per. I. The altitude of T above the veflel is 30 inches. Experiment I. Time of expelling the air, by feveral trials, is 33 feconds. £««£ a &U of 33 Exper. II. The altitude of T is fix feet. The time of filling, Experiment II* by feveral trials, is 21 .3 feconds* with a fail of 7* In the firft experiment, 425.088, the folidity of the vefifeI>' Compl'tation of divided by .004-6, the area of the hole a, gives 92410.4- inches the firft experi- for the length of the dream of air driven out in 33 feconds ; mef 8»™ ac- o tual velocity per divide that length by 33, and we (hall have 233.3 feet, the ve-fec. = z^ locityper fecond, communicated by 30 inches of water. feetJ The fecond experiment by the fame procefs gives 361.6 feet amj 0f the (tcmM per fecond. If we would compare thefe together, we mayg»ves 361.6 per fay, as the fquare root of 30, the head, is to 233.3, the velo- city ; fo is the fquare root of 72, the fecond head, to 361.8 feet, the velocity per fecond. Again : — As the fquare root of 6 feet is to 361*6, fo is <-heWhence h fquare root of 33 feet to 845.2 feet per fecond, the velocity locity of air fro in produced by that head, or the initial velocity with which thefhe atmofphere J J . '"to a vacuum i$ atmofphere would enter a vacuum. This velocity, found by computed, and experiment, is 487 het per fecond lefs than has been affigned *urns out t0 De . \T b 845.2 inftead of by theory. 133* feet, as by It appears however that the refults, as determined by the- theory, ory and experiment, do not differ more than in the cafe of efflu- correc^ed1!^ the ent water. For, if we would reduce the velocity of effluent multiplier given water found by theory, to that which experience gives, we^gjj*"16"06 muft multiply it by .634. Accordingly, if we multiply 1332 ter, proves to be feet} the velocity of the atmofphere entering a vacuum as cal-ver^ corre&« culated above, by .634, the product is 844.5 per fecond, differ- ing but T7^ of a foot from that juft found by experiment. I have alfo made experiments by finking veffels in water, till Experiments their tops were even with its furface, and opening the aperture Wltn rilinS wa* that the rifing water might expel the air, by which I obtained the fame velocities as above; but the method of computing is much more intricate, for which reafon I lliallnot infer t them. From the above it appears, that a preffure equal to 33 feet General refults of water, will expel air out of the bellows into the atmofphere with a velocity of 845 teet per fecond ; that one foot of water in depth will produce a velocity of 147 J feet, and one inch a velocity of 42 feet per fecond, or 20 miles an hour. Hence we may conftruct a table fhewing the velocity com- applied to the municated to air by any head of watery for as the fquare rootconftru till, when in its proper pofition, it is vifible at D. It is now ready for ufe, and the end A may be fixed in a hole made in the upper board of the bellows, and the water will rife in the glafs tube, in fmith's bellows, generally from 9 to 12 inches, furnace bellows, generally four feet or more. But where the compreflion is great, quickfilver may be ufed inftead of water, only in this cafe the inftrument fhould be made of iron, as quickfilver caufes the fcrews of brafs to fcreak. Or, inftead of quickfilver, the tube E D may be fealed at the top E, and then a length of 12 or 18 inches will be enough for any blaft. The glafs tube needs not be more than one-eighth or one-tenth of an inch in diameter. Whatever compreffion there may be in the bellows, there will be the fame in the upper part of the tube B, which will force the water into the glafs tube DE, and make the air in its upper part of the fame denfity, deducting from the compreffing force the altitude of the water raifed above D, which however will be of little or no importance; if the gauge is placed in a horizontal pofition, with the glafs tube downward, there will be no difference of denfity. the tub- may The computation for the force in the cafe where a tube her- be hermetically metically fealed at the top is adopted in the inftrument, will be cIofed* effected by confidering that the fpace occupied by any elaftic fluid is inverfely as its force. Thus, let the tube be 12 inches long, and fuppofe the water to be raifed one inch, then it will be 11 : 12 :: the force of the atmofphere : the force of the air in the tube : ; 1 : 1 TfT. Hence a fcale may be adapted to the inftrument, VARIATION OF RATE IN A TIME-PIECE* 27' 3 inftrument, to exprefs the force of condenfation over and above the common atmofpheric preflure; which force is (ignified in the inftance above, by the fraction TTT, unity being the atmo- fpheric preflure. If we denote the atmofpheric preflure by 30 inches of mercury, or 32 feet of water, then the force ^ in the above example, will be exprefled by 2.727 inches of mercury, or 2.9 1 feet of water ; and the like for any other inftance. If a mercurial inftrument of the above conftru&ion be pre- If mercury be ferred, it becomes neceflary to add the height of the mercurial ufed» lts denfitjs J ° . muftbeconfi- column to the force found as above : thus, if the condenfation dered in the of air be from 12 into 9 inches, then the addition to the force fhort inftru- of the internal air in the tube is equal to -j-, or 10 inches of mer- cury, to which muft be added the three inches raifed in the tube, and the whole force will be 13 inches of mercury, exclu- five of that of the atmofphere. This fort of inftrument or gauge ferves equally well for find- General apply- ing the expanfive force of any kind of elaftic fluid, as for mea- tl0n t0 a11 safes* furing the velocities with which they iflue out of the place of their confinement. It may be applied to all kinds of bellows, to condenfed fteam, and to the air pump. XII. On the Variation of Rate in a Time-Piece, as indicated by ths Changes in the Arc of Vibration. In a Letter from Mr. Ezekiel Walker. To Mr. NICHOLSON. S I R, Lynn, July 20, 1802. J? ROM what I have already mentioned in a former paper *, Expediency of it follows, that in clocks ufed in making aftronomical obferva- frcquent obfer rr r * m r vat,Qn of the < tions, it is neceflary to oblerve the arc or vibration very fre-0f vibration quently, and when it is found different from that generally de- clocks« fcribed by the pendulum, the rate of the clock muft on this ac- count be corre&ed. To determine this correction, let x denote the time which a Rul.e for de* pendulum, vibrating in an arc exceedingly fmall, will lofe ationln time"* when made to vibrate in a larger arc of the fame circle, T the from' that of the arc. * See pa. 76 of this vol. Vol. II.— -August, 1802. T number arc, in 274< VARIATION OF RATE IN A TlMfc-PIECE, number of feconds in 24 hours (864-00), and D the number of degrees defcribed on each fide of the^erpendicular *. D* Then x = T x nearly. Confequently x as D* x 524*80 1 .64-63 nearly. From the above theorem the following table was computed, which fliews the time loft by a pendulum in 24- hours, by in- creating its femi-arc of vibration in the fame circle T of a degree. TaMe of vibra- tions, and corref- pondentlofsfrom their increafe. Half the. arc of vibration of a pendulum in a circle. 0P o i of 0| 1 I i I I 1 i 2 2 i 'i 3 3 i 3 f 3 i Lofes per day of a pendulum vi- brating the leaft arc poffible. o,"o 0, 1 0, 4 0, 9 h 6 2, 5 3, 7 5, 0 6, 6 8, 3 10, 3 12, 4 14, 8 17, 4 20, 2 23, 2 2.6, 3 Difference. 0,"l 0, 3 0, 5 0,7 0, 9 1,2 1,3 1,6 1,7 2, 0 2, 1 2, 4 2,6 2,8 3,0 3,2 Lofes per day on increasing its fe- mi-a'c of vibra- tioni'of a degree. ,006 ,020 ,033 ,046 ,060 ,080 ,086 ,107 ,113 ,133 ,140 ,160 ,173 ,187 ,200 ,213 * Simpfon's Fluxions, Art. 464, The DEPENDANT ON THE ARC OF VIBRATION, 275 The ufe of this table will be eafily underftood by the follow- ing examples. EXAMPLE I. Suppofe a clock goes mean folar time when the pendulum Examples* Vibrates 2° on each fide of the perpendicular, what will it lofe per day when the pendulum vibrates through an arc of three degrees ? Againft 2° and 3° in the firft column, we have 6,"Q and 1 4/8 refpeftively in the fecond column. Then 14,"S — 6/6 = 8,''2 = the time loft per day. EXAMPLE II. Suppofe a clock gains l" per day, when the pendulum vi- brates 1° 49' on each fide of the perpendicular, what would be its rate when the pendulum vibrates 1 ° 5 1 '? Between 1°J and 2° in the firft column, we have /'107 in the fourth column. Then 1''— ,"107 x 2 =.0/'786 = tli« daily rate of the clock gaining. I am, with refpect, Sir, Your humble fervant, E. WALKER. ANNOTATION. The arc of vibration in clocks is likely to be affected in Whether theory practice by changes in the dcnlity of the air, in its tempera- can be#aPP].iedto tin engine io ture, and in the action of the firft mover; and thefe caufes will compounded as a moft probably afford refults confiderably different from thofe clock> &c* inferred from the fimple pendulum in vacuo. I take it to be experimentally afcertained by the regifters of the performance of aftronomical clocks very firmly fixed, that the gridiron pen- dulum, with a very flexible fpring fufpenfion, is not fenfibly affected during the different ftations of the barometer and ther- mometer ; and I apprehend that the firft mover, if a weight * muft operate either with a conftant force or with periodical variations, occafioned by the train or mechanifm through which its action is tranfmitted, the influence of oil, &c. which periods are rendered fhorter by the well known methods of difengaging the efcapement, or parts neareft the pendulum. Many other confiderations will offer themfelves to the learned author, as to T 2 the 276 DESCRIPTION OF ATKINs's HYDROMETER. thofe parts of the vibration to which the maintaining power may be applied fo as to increafe the arc, while the time may be either lengthened or fhortened according to the circumftances, the general nature of the efcapement, &c. and thefe will pro- bably lead to a conclufion, that the corrections of time to be applied to a clock, which either in its arc of vibration or otherwife gives fymptoms of irregularity, can be gained only from direct: obfervation. W.N. XIII. Defcription of Atkins's Hydrometer for qfcertaining the fpecific Gravities of fpirituous Liquors. By J. Fletcher, Efa. Communicated by the Author. Utility of de- AMONGST the various papers which are to be found ia fcriptionsorphi- . , _ . r . v ' i r • n lofophicalin- tne works ot thole journaliits who have fo materially contn- ftrumcnts. buted to the advancement of our knowledge, there are perhaps but few which have been more effectually conducive to this end than thofe which are appropriated to the defcription of the internments of fcience. It is indeed much to be lamented, that the merchant, the manufacturer, and the artizan, thou Id continue to be fo generally deprived of the advantages to be obtained from the ufe of fuch of them as are adapted to their purpofes, for want of the necefTary information with regard to the mode of applying them. The inftrument which is here intended to be defcribed, is one of thofe which Hand in a great meafure in this predica- ment; and as it appears very well to deferve a defcription, it is conceived that, imperfect as the following one is, it will not be unacceptable. Spec. gr. only It is now univerfally acknowledged, that the fpeciflc gravi- ftrenr'thof fuf- ties of 'Pirituous liquors afford the only tolerable criterion of rits. their ftrength, and confequently of their comparative values. Toafcertain the fpecific gravity of a liquid with a confiderable degree ofprecifion, is an operation of no great difficulty. The mod accurate method of performing it is perhaps that which is alfo the fimpleft : to weigh the fluid in a veflel in which its bulk is capable of being nicely meafured. Much more, how- ever, DESCRIPTION OF ATKINs's HYDROMETER. 277 ever, remains to be done in order to the eflimation of the Correftlons ne- ' „ r r ceiiary to be ap- tfrengths of fpirtuous liquors: the contradion ot the mals ot aplied compound of alcohol and water on their mixture, and the va- for concentration . ... ,. «» i rand temperature. nation in its meaiure in refpecl of temperature, are each ot them of fufficient practical importance to render their apprecia- tion neceffary when the value of the fpirit is to be difcovered. Thus for example, 18 gallons each of alcohol and water will afjaa^Ter °f produce only 35 gallons of the compound, and a difference of produce only 35 30° in temperature of Fahrenheit's fcale, occafions fuch a °/the mixturf* r . .c . 1 A variation or change in the fpecific gravity of proof fpirit, as, if omitted to 300 of temp, oc be taken into consideration, would render the dealer liable to cafions a change an error of upwards of ten per cent, in the efiimation of its in t^e app rrenj ftrength and confequent value. ftrength of In commercial tranfa&ions withrefped tofpirituous liquors, Commercial eMr it is neceffary to appreciate their ftrength by comparing it with mation of value that of fpirit of a certain fuppofed quality in this refpeft as a ^'^J"* ftandard. This ftandard-fpirit (which is called proof-fpirit) is of fuch a degree of ftrength that its fpecific gravity is about .920 at 60° of Fahrenheit's thermometer ; and the object of enquiry in all cafes is with regard to the quantity of this proof hl companfon fpirit which would be equivalent to a given quantity of any fpirit. fpirit under examination. The language of the fpirit-dealers Definition of with refpect to their terms of ** over-proof" and " under-proof" (i pr00p ■ an(j has in all cafes this kind of reference to commercial value. " under-proof.'* When they fay that a certain kind of fpirit is 30 per cent, over proof, they mean that if 100 parts by meafure be increafed to 130 by the addition of water, it will become of proof ftrength ; and when they fay that it is 30 per cent, under proof, they mean that 70 parts by meafure of proof-fpirit will become, when increafed to 100 by the addition of water, of equal ftrength to that of the fpirit in queftion. If therefore a gallon of proof fpirit be worth 8s. 4-d. the fame quantity of the former kind of fpirit will be worth 10s. lOd. and of the latter 5s. lOd. It is not therefore fufficient for the purchafer of a fample of fpirit, or the officer who is to collect the duties on it, to be in- formed of its fpecific gravity at a given temperature : it is ne- The defideratum ceffary for him to afcertain the quantity of proof-fpirit which is Is ^lelt^uan- capable of producing, or being produced, by the fpirit in queftion tity of proof- by the addition of water only, and which is confequently equi- *Pirit* valent to it in value. The 278 DESCRIPTION OF ATKINs's HYDROMETER; Calculation in- The folution of this problem being almoft impoflible by any pPup^.lCt°thlS application of mathematical formulas, itisofcourfe defirable to be enabled to obtain it infirumentally, or by infpeclion of Jfubl«.niCnCC tableS Previoufly laid down from experiment; and the ufe of the latter, under fuch circumftances as thofe in which opera- tions of this kind are generally performed, having been found JoluSon'prefer- ^nconvement> its infirumental folution has been univerfally pre- able. ferred. This has been attempted principally in two ways: by with hya^rometer the hydrometer, with a multiplicity of weights adapted to the weights, various corrections for temperature; and by the fame infiru- ment more fimply conftru&ed, fo as to indicate merely the with a Hiding- fpecific gravity of the liquor; the necefTary corrections being applied by a fcale or Hiding-rule. The latter moft The infirument here to be fpoken of is conftrucled on this latter principle, which appears for many reafons to be the befi : 5tWnrt°h dro- Th(? Mrometer A B (P1- XV %• 3) is of brafs. It is eight meter. inches in length, with an elliptical bulb an inch and a half in Square : ftem, diameter, and two inches long. The ftem is fquare, each fide of the alphabet being about \ of an inch wide, and, when the infirument is in- ©n one face, tended for fuch liquors only as are fpecifically lighter than water, is engraved only on one face with the 26 letters of the alphabet, and an Q, or zero, at the top and bottom ; oppofite to each, and between every two of which, is a divifion for mark- ing the point of the ftem which is cut by the furface of any liquor in which it floats, the whole number of divifions being 55, as fhewn in the plate. The weight of the infirument is and four about 400 grains, and it is provided with four weights, mark- ed 1, 2, 3, 4, weighing refpe&ively 20, 40, 61, and 84 grains, to be applied as occafion requires on the thank of the infiru- ment C, on which they are retained by the button or fixed to Ae bulb w?tK weiSht B- Thefe weights are fo adjutfed, that when with any one weight, the one of them, as for infiance No. 2, the ftem of the infirument, next heavier -when floating in a given liquor, juft emerges to the lower divi- finks it to the _ • . ° ■ ° , ? ■ / | 7°r . . fc top of the ftem. "on O, it will, on changing the weight for the next heavier, No. 3, become immerfed exactly to the other divifion O, to- |!!m SuVhl^ wards its fuperior extremity. The fiem is by this means virtu- effect multiplied ally extended to five times its real length, and the number of With the divifions in effect augmented to 272. Thus without any weight weights finely at all, as reprefented in the figure, it would fink in a liquor applied, indicates wnofe fpecific gravity was .806, exactly to the upper divifion Specific gravities pj from .806 to V, S.COOJ DESCRIPTION OF ATKINS's HYDROMETER. 279- O, and in one whofe fpecific gravity was .843, to the lower divifion O ; the intermediate divifions anfwering to interme- diate fpecific quantities. With No. 1, it indicates fpecific gravities from .843 to .880; with No. 2, from .880 to .918 ; with No. 3, from .918 to .958 ; and with No. 4, from .958 to 1.000; the furface of water in which the inftrument is made to float with the latter weight, exa&ly coinciding with the lower O, at 55* of temperature. The whole interval from .806 to 1.000, comprehending the fpecific gravities of all fpirituous compounds, is in this manner divided into five nearly equal portions, each of which, com- prizing from .038 to .040, is meafured by the whole length of each length of the ftem ; fo that each of the 54 intervals on its face corref- [bc?e mum{""' ing to about .04J ponds to considerably lefs than an unit in the third place of the and each divi- i'pecific gravity, and indicates a difference of about one halffion to left than . . .0011nfpec.gr. per cent, or two quarts in 100 gallons, in the quality of the or i percent, in compound, and the inftrument is therefore abundantly fen- ft«nfith. iible to very minute variations in thefe refpeds. With regard to the application of the weights, no error can poflibly be committed. If the inftrument floats in any liquor, fo that its furface cuts any part of the ftem, it is properly- loaded. Any weight but the proper one will either fink it entirely, or fuffer the ftem to rife totally above the fluid. The fpecific gravity indicated by any divifion on the ftem Spec. gr. indi- of the hydrometer, is feen inftantly by reference to a Hiding- cated by the di- rule belonging to it, whofe two faces are (hewn, plate XV. ften^compared fig. 2 and 3, on which the lines of divitions A A, A A, marked w'th the rule.' with the letters of the alphabet, reprelent thofe on the inftru- ment when loaded with the weight, whofe number is marked over the O at the commencement of each feries, and the exte- rior lines of divifions B B, B B, near its edges, fhew the corres- ponding fpecific gravities compared with that of water at 55°. In order, however, to afcertain the ftrength and value of the Correction for fpirit, it is neceifary to examine its temperature and apply the temperature ap- proper correction, which is done with extreme accuracy by the p 1C ' fame fliding-rule, by an ingenious application of two fcales of unequal parts to each other, viz. the lines C C, C C, marked *' Atkins/* and the lines A A, A A, marked with the letters of the alphabet. The mode of doing this is as follows : the tem- by fettjng an ;n_ perature of the liquor being taken by the thermometer accom- clex on the Aider panying the inftrument, the afterifk or index, plate XV. fig. 1, ternpertu^f on fliewn by the thermometer. 280 DESCRIPTION OF ATKINs's HYDROMETER. on that part of the Aider oppofite to the thermometrical fcale D, is to be fet to the degree of temperature fo found, and the Divifion on Aider divifion on the line C, marked "Atkins," which then corref- •nfwering to the ds Qn ejther flde of the ruje w;th that letter and divifion on letter on the ftera r gives perccn- the alphabet line A, at which the flem was cut by the furface t38e* of the liquor, indicates the ftrength and value in commercial Example from terms. Thus fuppofe the temperature to be 68° (at which the the plate." * *nc*ex appears fet in the plate), and the hydrometer, when loaded with its weight No. 1, to float with the furface, cutting the divifion I on the flem (correfponding to a fpecific gravity of about 854f ), we find, on fetting the Aider of the rule to 68° on the thermometer fcale, that 46 over proof correfponds to that letter and divifion, and is confequently the ftrength and value of the liquor. Ufes of the other The lines marked " Dicas" and " Clark" on the rule, are flScr00 e ^or £*vmS *ne appreciation of the values and ftrengths as (hewn by the inftruments invented by thofe artifts, and are intended for the ufe of fuch as have been in the habit of employing them ; the latter being perhaps inferted principally on account of the ufe of Clark's inftrument for the purpofes of the re- venue. Of the concen- The figures on the line marked " concentration" amongfl tration-line. ^e over.proofSf indicate the diminution in volume which takes place on reducing the given compound to proof; and amongft. the under-proofs, the diminution which takes place on reducing Concentration proof-fpirit to that ftrength. This raufl in the firft cafe be de- to be deduced rfu&ed from the quantity marked on Atkins's line (C), in order from the per , i- . «» centage. to obtain tne accurate per centage according to the eftimation Example. Di- of commercial men. For infiance, 50 over-proof on Atkins's roinut on of 3 line indicates, that if to 100 parts of fpirit of the ftrength which Soofwate^to5 anfwers to this divifion, we add 50 of water, we (hall get iooof5oover- proof-fpirit, of which, however, the quantity will be only 147 proof' parts ; the concentration or diminution of bulk by mixture be- Concentration ing 3 parts. With regard to the fpirit which is under-proof, on mixture of ^e florUres on the concentration line indicate the diminution of pr •">f-ipiric and ....'* ,nn 11 /• ,i • , -r r water. volume 10 pints for every 100 gallons ot the mixture: it, for inftance, 70 gallons of proof-fpirit be combined with 30 of water, we get a compound whofe ftrength is that which is marked on the line C, 30 under proof; but the concentration being feven pints, we (hall get only 99} gallons. 4 When EXAMINATION OF VQLTa's EXPERIMENTS, &C. 281 When the hydrometer is intended only for fpirituous com- Applicable to pounds, the weights are applied lingly as beicre-mentioned : J^rJhe wefuhu' if, however, in addition to the weight No. 4, the others are doubly, fucceffively applied, it becomes applicable to the examination of worts and other liquors, whofe fpecific gravities are from 1.000 to 1.109, or, in the language of the brewery, up to Spec. gr. of „ , , , . ° ° T , . ., ., ,, worts defignated 40 lbs. per barrel heavier than water. In this cale the other by lbs# per bar_ three (ides of the flem are alfo graduated, and another rule re!. with an ivory Aider, carrying a thermometrical fcale for com- for tbe brewery# paring worts at different temperatures, is included in the cafe with the inftrument. The writer of this paper having made a confiderable number of experiments with this inftrument, on the fpecific gravities of a variety of fpirituous liquors, had originally intended to have given their refults ; but it has already run to fuch a length, that they mud be deferred to a future communication. The errors, Errors in refultt even including thofe which mud neceffarily arife from the va- v"y fmall> *n<* & ■> advantage of rious temperatures of the compounds, and the different quanti- facility ofufe ties of foreign matters with which thefe fluids, in an impure very confider- fiate, may be fuppofed to be charged, appear to fall within very narrow limits ; and the extreme facility and expedition with which it refolves the, queftions to the folution of which it is applicable, cannot fail to render it very highly valuable to thofe for whofe purpofes it is principally intended. XIV. An Examination of Sig. Volta's Experiments- which he calls fundamental, and upon which his Theory of Galvanifm refts ; with a Defcription of a very fenfibk Elecliical Condenfer, and an Explanation of the Action of the Eleclric Fluid in the Galvanic Inftrument. By John Cuthbertson, Philo- fophical Inftrument Maker, No, 54, Poland Street, London* Communicated by the Author, In Vol. I. 8vo, page 136, paragraph three, of this Journal, ^'con^of^ Sig. Volta affirms, " If two infulated difes, one of copper andinfulated difesof " the other zinc, be applied together for a moment and then coPper .and ^,1C. , , . , producing + el. " leparated, the zinc will be pofitive and copper negative." in the zinc, and I have always had the fame refult, but fome times much~"e1, ,n the weaker than at others. Succeeds. Page 232 EXAMINATION OF VOLTA's EXPERIMENTS, &C. Expt. of copper Page 137, in the laft paragraph, it is faid, " If a piece of and zinc joined, tt zinc to vvhjcn js joined a piece of copper, and the zinc held and ihe copper to , J. \ , i • touch a zinc by two fingers or in any other manner, and the copper made condenfer, and « to touch the fuperior difc of the condenfer, which is zinc, afford — el. in „„,.,,./... . . . , , , this laft. while the interior is m communication with the ground, a " moment afterwards railing the upper difc in the air, it will Did not produce*, De negatively elearified." This I have always found the — el. but + el. to. ' contrary, i. e. pofitive. Expt. of zinc page 133^ paragraph three, it is alfo faid, " If the fuperior per condenfer, " difc °f tne condenfer be copper, and a piece of zinc be made and affording no « to touch it immediately without any intervening fubftance, •f nothing will be obtained, becaufe the zinc being then in 0 contact at the two oppofite ends with copper and copper, " two equal forces act in oppofite directions, and by that Did notfucceed." means deftroy or counterbalance each other." If the fupe- rior difc was copper, I always found it negative, and if it was zinc touched by a piece of copper, it was pofitive; both con^ trary to Sig. Volta's aifertion. We find then that only one experiment out of three fucceeds, which he calls fundamental, upon which his theory of galvaii* ifm is founded. The foregoing Knowing Sig. Volta's abilities both as a philofopher and ex- expts. were perimentalitf, I own I mention the refult of the foregoing ex- •ften repeated. r . .... x . , ° , penments (though it is after numerous repetitions) with much diffidence ; but the experiments are fo fimple, that it is almoft impoffible that I can have erred. By reafoning upon the phenomena, when copper and zinc are made to touch each other, it becomes eafily explicable by the old known laws of electricity. EXPLANATION. Explanation. In the firfl experiment, where zinc and copper are made In expt. I. either to touch each other, we find, on feparation, that the zinc has or the copper r*- acquired a greater (hare of electric fluid than it had before the felled the elecl. touch, and the copper lefs, by virtue of their mutual action upon while in contact. each othef when ^ conta^> So that the zinc mult have either attracted the electric fluid out of the copper, or the copper muft have repelled it from itfelf into the zinc ; and that the firfl is • the true caufe may be proved by connecting the copper difc with conductors, and then touching it by the infulated zinc, which will be found, on feparation, to be much more ftrongly pofitive EXAMINATION OF VOLTAY EXPERIMENTS, &C. 283 pofitive than when the copper was infulated. For whatever The effect is quantity of electric fluid may be drawn out of the copper by the ftr°nger when ,,.,,. . ~. • i ,• , the zinc alone is zinc, is recovered by its being in connection with continued infuiated anrium • • , , • i ■ ■ i r i • of electricity ; copper has given and the zinc has received luch a quantity of the zinc + and electric fluid as their mutual action upon each other required ; the C0Pper — • and in confequence of this property, they prefent a mutual re-, fiftance to any further change being produced upon them. If Chemical action then any menftruum be added to the oppofite fide of the metals, trical propertyof capable of producing a change in their metallic property (fuch that part of the as the fluid contained in the wet cloth), a change in their elec- ta^Q% 'pi^0 trical property mufl of courfe follow. But as this change in the metallic property is only fuperficial, it will only be there that its electric property is changed. The other parts of the two metals in contact will remain unaltered, and maintain their property of refinance. The change produced by the action of * When the atmofphere is in a favourable ftate. In this as well as all other experiments where fo fmall quantities are to be made evi- dent, the atmofphere has great influence, the "288 EXAMINATION OF VOLTa's EXPERIMENTS, &C This changed the menftruum, with refpect to its electrical property upon that afertedtobe of t on« Qf thc metal wnereon jt j]as a^ed, is exactly the re- an oppoute na- ■ J J ture to the dec- verfe of that of the parts not acted upon. The part of the trie ftateof the z[nc thus a&e(j upon, muft confequently be difpofed to throw and therefore 'off its electric fluid, and would give to that part of the copper, produces eleftric which by a like action is difpofed to abforb it) fo that the two furfoees oppefite ^ates or tne furfaces acted upon would unite and counterba- $o thofe of the lance each other imperceptibly) if it were not oppofed by drh'Tdonot tne ^ exifting property and mutual action of the two metals pafsfrom zinc to in their parts not a£ted upon by the menftruum ; hence it fol- copper through Iovys that the eieftrjc fluid is propelled forwards from the zinc the metals and . .. , . ., become quief- through the menftruum to the next adjoining copper in the pile cent; but from or trough ; but this can only happen in a progreffive manner, through the fluid, on account of the menftruum being an imperfect conductor, this paffage be- which appears to be an indifpenfible condition to the maintain- '%£& gal- ™S any electric intenfity. 'wanic current: The fhock or fen fation felt on touching the two oppofite which is progre-encjs 0f the galvanic inftrument, depends upon the menftruum, fluid cannot per- together with the refifting property of the two metals in ccn- feclly conduft ta£# -phe flll;ti muft be adequately proportioned between be- the eleancity as . n /f r M!l c A faft as it is extri- lng an electric and a perfect conductor. It it were a perfect cated. conductor, the electric fluid would pafs from the zinc through The fhock from the menftruum to the next adjoining copper, as quick as it is fuddenw'tra^f-11 g*ven or^ ky tne altered part of the zinc ; no accumulation mitted. would enfue, and confequently no fenfation of fhock or dis- charge would be perceived. If it were an electric, the electric fluid given off by the altered zinc would be ftopped, and accumu- late till it become pofTelTed of fufficient force to overcome the mutual reiiftance of the two metals in contact, and pafs through by a reverie motion to the copper ; confequently no fenfation would be felt by forming a communication between the two oppofite ends. For though there would be an accumulation, yet it cannot be united ib as to act in concert with that of the other combined metals; being (hut off by the interpofed electric menftruum, and too feeble of itfclf to affect our fenfes. ANNOTATION. W. N. Short hiftory of At page 396, vol. I. of the quarto feries of this Journal, an inftruments for outline • ;ven of the hiftory of all the inftruments for (hewing (hewing minute % p r \ n • • 1/1 quantities of or meafunng minute quantities or electricity, with a itatement electricity. 0f their advantages and defects. With regard to the condenfer difcovered fcXAMiNATiotf of Volga's experiments, &c. 289 di (covered by Volla in 1780*, and uf'ed for atmofpheric elec- tricity and in the grand difcovery of the electricity produced by chemical changes, it was applied very early by Cavallo in the compound form; that is to fay, by charging a fmaller in- liniment with the contents of a larger. Mr. Bennet before 1787 f, added the condenfer to his electrometer, and invented the method called - oubling, which had before been ufed with the eleftrophore by Lichtenberg % and Klinoock §. Our elec- tricians, particularly Mr. Cavallo and Mr. Bennet, were at this time fully aware of the fpontaneous electricity of the doubler, and the evils to be apprehended from the varnifh and the actual contacts. I think it was Mr. Cavallo who fubfti- tuted fmall knobs of fealing wax Mead of varniih, which I faw adopted in a mechanical doubler by Dr. Darwin in 1787 ^ and in the year 1788 I communicated to the Royal Society |f the revolving doubler, in which the plates approach and re- cede without touching ; and foon afterwards I made the fpin- ning inftrument, confiding of a condenfer and anelectrical well. In the fame year Mr. Cavallo publifhed ** his colle&or of elec- tricity, which is a condenfer having two uninfulated plates, which feparate like plate a, fig. 2, on each fide of b, without contact; and in the third vol. of his " Complete Treatife on " Electricity/' 1795, he defcribes his multiplier, which confifts of two condenfers, equally perfect; one of which is made to charge the other by repeated alternations of the compen fating plate. The above fliort (ketch will enable the reader to afcertain to what extent the ingenious contrivers of the inftruments in plate XV. have availed themfelves of the labours of former operators. * Journal de Phyfique for May and Auguft 1783, and Phil, Tranf. LXXII. p. 237. f Phik Tranf. LXXII. p. 32. % Journal dePhyf. Jan. 1780, p. 20. § Phil. Tranf. LXVIII. p. 1029. II Phil. Tranf. LXXVIII. ** Phil. Tranf. LXXVIII. Vol. IL— August, 1802. U XV, QbfervatioT* 2#0 OBSERVATIONS ON THE TREMOLITE, XV. Obfervatiom on the Phofphorefcence of the Tremoliie, and of the calcareous Phofphate of Jlow Solution, known by the Name of Dolomie. By M. Le Comte de Bournon, Felloiv of the Boi/al and Linnaan Societies. Tranflaied from the Original ; communicated by the Author. The pfcofpho- £ EW refearches have yet been made concerning the phof- ncrals has been phorefcence of the bodies of the mineral kingdom. No iatis- Jitde inquired faclory explanation has yet been given of this phenomenon, though this knowledge would undoubtedly throw new light upon the ftudy of minerals, and prove a great acquifition to natural philofophy and chemillry. The methods of This property of emitting light, which daily observation byVi'alor ' a ^ievvs to belong to many more minerals than had formerly been by heat. iufpccled, requires particular management. In fome foffils, iuch as quartz, blende, corundum, &c. &c. it becomes fen- fible only by friftion. In others it exhibits itfelf only when the mineral is placed upon a red hot coal, or upon any other body heated to a fitnilar temperature. This is the cafe with the carbonate of ilrontian, ofbarytes, &c. In others again, the phofphorefcence is developed both by friclion and by heat, as is the cafe with the phofphates and filiates of lime, as well as with a great number of carbonates of the fame earth, particu- larly thofc of a brown or yellowifli colour. Thefe fads give occafionfor feveral questions, the folutionof which would be extremely intereft ing. Does it arife Do thefe two kinds of phofphorefcence depend upon the from combined fame caufe ? In all the ftones which exhibit them, and are at the lame time coloured, the colour diminifties in proportion to the difengagement of the phofphorefcence by the action of heat : and when they ceafe to be phofphorefcent, they at the fame time intirely ceafe to be coloured. Does this phenome- non proceed from the difengagement of the combined or inter- pofed light ? Does the colour in thefe Hones always belong, in reality, to metallic oxides, particularly thofe of iron ? May it not rather belong' limply to the combined light? In this cafe, may it not be fuppofed that the light is decompofed, by com- bining with thefe Hones, and that it then entered into their 4 compofitioK OBSERVATIONS ON THE TREMOLITE. 291 Compofition only by infulated rays, or by combination of two or more, and not the whole of the rays ? We are, however, The phofphoric enabled to make an obfervation with refpea to this fubjeft, ^°eu[nFsalffteone9 namely, that thefe ftones conftantly exhibit by the action of0f the fame fpe- heat, a phofphorefcence of the fame colour, whatever may be *[es> however , r v in themfelvei may the colour of their proper fubftance. For inftance, the fluates be coloured. of lime which exhibit the moft lively and variegated colours, conftantly give a light inclining to the violet, with the -tingle exception of the Siberian variety, which has been named the Chlorophane, and which, though of a violet colour, gives a phofphorefcence of a beautiful emerald green. In others, as in Ibme carbonates of fime, in thofe of barytes, of ftrontian, &c. though thefe ftones are perfectly colourlefs, the phof- phorefcence is conftantly reddifh, or orange yellow. What may be the caufe of thefe contrafts ? In fome cafes the caufe which produces the phofphorefcence It may arjfe of the ftones feems to belong to an efleniial part of their fub- from aPerma- o r \ tm • nent cau*c> or itance, which is never completely expelled from them. This from fome por- is the cafe with the calcareous fluates and phofphatea, &c. tl™ tha* can be . • , n ■> abftra&ed. In others it appears to be purely accidental in the ltone, and thews itfelf only in a certain number of individuals belonging to the fame fpecies. In the firft cafe, this property ouglit to be indicated amongft the fpecific characters of the ftone ; in the fecond, it cannot ferve as character of the fpecies, but can merely be ufed to designate one of its varieties. Such is, for example, that which exifts in the tremolite and in the dolomie, refpecting which I intend here to offer fome obfervations, which appear to me to deferve the attention of mineralogifts. M. de Sauffure and Profeilbr Blumenbach were, as far as I The tremolite is know, the firft who obferved the two kinds of phofphoref- notin fJG*- . r mens pholpho- cence in the tremolite ; and, fince them, all the works of mi- refcent. neralogy have placed this property amongft the distinctive cha- racters of this ftone. Many tremolites, indeed, are endowed with this double phofphorefcence ; but this is by no means the cafe with all, nor can this character, be confidered as efiential to its nature. The tremolite, both that which is found in different vallies Thofe which are of Mount St. Gothard, and that which is brought to us from a 5n a phofphoref- , c . . .7; irj- cent gangue are great number ot other places, is generally mcloled in a granu- themfelves phof- laled carbonate of lime, the grains of which are of various de- phorefc » ; and grees of finenefs, and their adhefion more or lefs confiderable. ^hen the gangue U 2 Among is not phofpho- 292 OBSERVATIONS ON' THE TRKMOLllR. refcent the tre- Among thefe carbonates of lime, which conititute the gangiflfc mo e is no o. Qp ^Q tremolite, and very frequently belong to the fpecies. which is called dolomie, a great number are endowed with the double phofphorefcence ; but, on the other hand, we meet with feveral, in which not the flighted trace of this property- can be found. The tremolites inelofed in the firfr partake^ though in rather an inferior degree, of their phofphorefcence, whereas thofe which are inelofed in a non-phofphorefcent car* bonate of lime are equally void of that property. That the phof- From the very firll moment when I obferved this fact, it oc- frhor!nterpoL°de curred to me> that the phofphorefcence of the tremolite might carbonate of very probably proceed merely from that of the carbonate of {|m^k^^0uved lime, which undoubtedly is interpofed between its parts. I by nitric acid, therefore (elected fome cryilals that were inelofed in phofpho- ■which deftroyed relcent carbonate of lime, and after having fatisfied myfelf • uality. that they were themfelves phofphorefcent, both by friction and by the aclion of heat, I digefted them for fome time in ni- tric acid. When I took them out, their furface was perfo- rated with fmall cavities, occafitJfWd by the folution of the por- tions of carbonate of lime, and friclion was then incapable of making them difplay the flighted phofphorefcent light. This light, however, was emitted, at the point immediately after ignition, though in an extremely weakened degree. I afterwards reduced fome of the fame cryftals to a coarfe pow- der, and this powder having remained again for fome time in the acid, was intirely deprived of all its phofphorefcent pro- perty. This quaKty I could no longer doubt that the carbonate of lime, inter- therefore belongs p0fed between tile particles of the tremolite was the real caufe and not the fpe- of the phofphorefcence of this fubftance, when its gangue was cIes* endowed with the fame property. It therefore appeared to me to be at the fame time perfectly proved, that phofphoref- cence cannot be ranked amongft the characters of the fpecies in this fubftance, and that it ought to be confidered merely as diftinelive of one of its varieties. Whether the A new doubt, which was a very natural confequence of this large portion of obfervation, now prefented itfelf. Could it be true, that the in tremolite can h'me which chemifts have reckoned to amount to ^6\ amongft be admitted as a the conftituent parts of the tremolite, does exift in it in fo wjlitutntfart? Jarge a proportion. In orfjer, ifpoflible, to fatisfy this doubt, I fele&ed fome cryftals of non-phofphorefcent tremolite, which 2 - had OBSERVATIONS ON THE- TR?MOLI^E. £Q$ liad only an argillG-qnartial fubftance for their gangue, and; re- queued Mr. Chcnevix, vvlio has already rendered fuch ufeful ier vices to mineralogy, to examine them by analyfis. I like- wife gave him fome cryftals from amongft thofe phofphoref- cent ones which I had broken,, and afterwards deprived of their phofphorefcence, by digefting them for fome time in nitric acid. My fufpicions were verified: Mr. Chenevix found only -y^ Probability that of lime in each of thefe two analyfes. 3u.t what at the fame gj^^^ time ftruck me, was that the tremolite taken from the phoi- lime or argil, is phorefcent variety, having for its gangue a carbonate of limti tr.urfferfed m the of the fpecies called the dolomi.e, which is likewife phofpho- refcent, but whofe calcareous part had been taken away by the nitric acid, gave by analyfis only T-J^- of argil, whilft that which was taken from an abfolutely argillaceous gangue gave tVz? °f ^e ^amc earth. Mr. Klaproth having found no argil at all in the analyfis which he had before made of this fub- ftance, it is probable that its exiftence in it, like that of the calcareous carbonate, proceeds merely from its fimple inter-, pofition. Thefe two observations appeared to me to be very intereft- Hence it is of ing to the ftudy of mineralogy, efpecially to that part of it chemicaUna-* which relates to analyfis ; fince it fliews with what care the lyfes of any mi- chemift ought to avoid confounding, with the true conftituent neral Aou,d be o • • ... . repeated upon parts of a fubftance, thofe which are foreign to it, and only fpecimens taken interpofed between its parts. It is extremely common to find from dlfferent the parts of a mineral, even in the ftate of cryftallization, en- velope more or lefs of the portions of that fubftance which conftitutes its gangue ; and what may likewife contribute much to miftakes in this refpect, is the kind of conftancy with which, (whatever may be its caufe, has hitherto been little attended to) the fame fubftance, placed in fimilar circum- ftances, admits this interpofed extraneous fubftance, in equal, or nearly equal proportions. It is not therefore fufficient that the chemift mould felecl for his analyfis, amongft the cryftals of a fubftance, thofe which appear to him to be the moft pureA (and the perfection of their form and tranfparency is the ftrongeft prefumption which he can have in this refpect ;) but he fhould alfo repeat the fame analytical procefs upon the fame fubftance taken from totally different gangues. ' When 294 The phofphoref- ceace of tremo- litc being ad- mitted to arife from intetfperfed ca: bonate of lime, will ac- count for the differing obfer- vations of au- thors. Though the phofphorefcence of tremolife cannot b*. ad- mi ttedas fpeci fie, yet the f.iriiity with which this very hard mine- ral is crulhed by preflure with the hammer and its elaftic refift- ance, are pecu • liar ipecific cha. rafters. Tremolite is found in Scot- land, at Mount Vefuvius, and in Bengal. Defcriptinn of the tremolite of Scotland. OBSERVATIONS ON THE TREMOLITE. When it is once admitted that the tremolite is phofphorcf- cent only in proportion as this property is contained in the carbonate of lime interpofed in its fubftance, the variations which fome authors have found in its phofphorefcence, will be eafily accounted for. It muft, for example, be the more eafily obtained by friction, as the hardnefs of this ftone is lefs confiderable ; becaufe the friction, by breaking its furface, will fucceffively arrive at the interpofed particles of carbonate of lime. And hence it is quite natural that the fibrous varie- ties fhould be more phofphorefcent than the others, and that thefe fhould be the lefs fo in proportion as they are harder. As this character, which was reprefented as fpecific in the tremolite, muft no longer be confidered as fuch, there is one which has been overlooked, and which, in my opinion, ought to be added to thofe which have been already obferved in it ; I mean the great facility with which, notwithstanding its hardnefs, which, in the pureft fpecimens is fuch that it eafily cuts glafs, it is cruihed by the mere preflure of the hammer, and the kind of flexibility which it then exhibits. If, in break- ing it, the preflure be moderate, the cryftals of tremolite di- vide, pretty generally, according to the length of their prifms, into fmall fibres, which are frequently as fine as thofe of the amianthus, to which, in this ftate, they have much refem- blance. We may then even increafe the preflure without breaking the fibres, which in this cafe afford by their refi fi- ance the fame fenfation as is felt from a flightly elaftic body. This effect, as well as the reduction of the tremolites into fmall fibres, is more diftinct the lefs pure the mineral. Both properties however are obferved, but in a much lefs degree in the pureft tremolites, and confequently in thofe whofe hardnefs is the moft confiderable. With a view to add as much as poffible to the knowledge already acquired refpecting this fubftance, I fhall add to the lift of places which have been indicated as the native coun- tries of the tremolite, Scotland, Mount Vefuvius, and Ben- gal. Mr. Greville's rich cabinet in London contains fpeci- mens from each of thofe different places; a defcription of thefe will probably be acceptable to mineralogifts. The tremolite of Scotland is in the fibrous ftate, its fibres being very fine and clofe, part of which is difpofed in diver- gent OBSERVATIONS ON THE TREMOHTE. 2.95 gent rays, tranfverfely crofied by other fibres, fo as to repre- sent a kind of texture, as is fometimes the cafe with the zeo- lite mezotipe. This trernolite is of a greenifli white colour: it adheres to a granulated but very compacl mafs of carbonate of lime, mixed in almoft equal proportions with the fame tre- rnolite, alfo in a granulated flate, on which account it ftrikes fire with fteel. This carbonate of lime pouefles both kinds of phofphorefcence, but the light which it gives is of a (lightly blueifh colour ; the fame is the cafe with the trernolite which it contains. This carbonate does not belong to the dolomie, and it diflblves in acids in the fame manner as the common carbonate of lime. The trernolite of Vefuvius is likewife in the fibrous ftate, Trernolite of with fine and clofe fibres ; its colour is a greyifli white, it Mount Vefu- adheres to a gangue compofed of carbonate of lime, of an im- menfe quantity of very fine fmall fibres of the fame trernolite, and of a great number of very fmall cryftals of pyroxene, of a beautiful green colour and tranfparent. Some portions of ido- crafe are alfo obfervable, of which there is a group at one of the extremities of the fpecimen in pretty large cryftals. The carbonate of lime does not belong to that of flow folution ; it poflefles both kinds of phofphorefcence, and the light which it emits is of a very lively deep orange colour. The trernolite exhibits abfolutely the fame phofphorefcence. We owe our knowledge of the trernolite of Bengal to Sir Trernolite of John Murray. It is in pretty large cryftals of a greenifli grey Bengal* colour, bedded feparately in a granulated carbonate of lime, the very fine grains of which have a ftrong adhefion to each other j a character which, joined to the great whitenefs of this ftone, caufes it very much to refemble a piece of double re- fined fugar. This carbonate of lime belongs to the fpecies of the dolomie; it is even one of thofe in which I have obferved the folution to be the flowed and moit infenfible, but it is ne- verthelefs completely dilfolved in the nitric acid, leaving only a light whitifh and clouded refidue, which difappears when the acid is diluted with water. Its hardnefs, which is much fuperior to that of the ordinary carbonate of lime, is rather inferior to that of the fluate of the fame earth ; and this is the cafe with all the dolomies, not excepting thofe whofe grains have the leaft adhefion with each other. This dolomie is not phofpho- 296' HISTORY OF GALVANISM. phofphorefcent cither by friction or by the action of heat, and the tremolite which it contains is intirely in the fame ftate. There are many other dolomies alio which poiTefs no phofpho* refcence, as has been alio obferved by the Abbe" Hauv. This character therefore Hill belongs to the variety, and not to the fpecies. XVI. Outline of the Hiftory of Galvanifm : with a Theory of the Action of the Galvanic Apparatus. By John Bostock, M. D> From the Author. To Mr. NICHOLSON. SIR, Tntioduaory XAAVING been lately employed in fome experimental in- lctter» quiries on the fubjecl of galvanifm, I found it commodious to arrange the numerous difcoveries that have been made in this department of fcience into the hiflorical form. The fads, which have been fucceffively developed begin to aflume fo elevated a rank among the branches of natural philofophy, that a fketch of the mod important and beft eflablifhed amongft them fecms defirable, in order that the experimenter may be eafily enabled to fee what has been done by his pre- deceflbfs, and may thus be prevented from wrafting his time and exertions upon points which have been previoufly inves- tigated. From reflecting upon the labours of others, and com- paring them with my own experiments, I have been led to form a theory of the action of the galvanic pile, which feems to explain in an eafy manner mod of its Angular properties, I am indeed well aware of the undue attachment which every one feels for the offspring of his own imagination, and I fhall not be furprized if you perceive in the hypothefis many ble- mifhes which have efcaped my notice. I have however fent you both the hiftory and the theory, in order that you may infert them in your Journal, if you think them deferving of a place there. I am, SIR, Your obedient Servant, JOHN BOSTOCK, M. D, jAterpool, June \, 1802. HISTORIC HISTORY Of GALVANISM. 297 HISTORIC SKETCH OF GALVANISM. THE firft publication * upon the fubject is the work of Firft publication Galvani himfelf, which appeared in 1791 . It begins by giv- °n ga vanifm b^ zng an account of the following accidental difcovery. A frog Legs of a frog, had its hinder legs feparated from its body, except that tin. { 'plated from 1 if i- 'J j 1 1 1 1 -J the body, were crural nerves were left undivided, and was by chance laid upon convulfed by ex- a table on which ftood an electrical machine. It was obferved tremeiy minute 1 1 1 1 1 1 ■ o • 1 r n~ ' portions of elec- that when the animal was placed in contact with, or luflici- tricity. ently near to, an extent! ve furface of a conductor of the elec- tric fluid, if a fpark were taken from the machine in any di- rection, the legs of the animal were fpafmodically contracted. When the frog formed part of the electric circle, fo that the fluid palled immediately through it, a quantity almoft imper- ceptible was found to excite contractions of the mufcles. A much fmaller quantity of the electric fluid produced the effect, when the animal was prepared in the manner defcribed above, than when the body was left intire, becaufe in the former cafe the fluid was confined to the r-yow track of the nerves in its. paflage along the circuit. A prepared frog appears therefore to be a moll delicate electrometer, as it exhibited contractions where no marks of electricity could be difcovered by the in- struments either of Bennet or Cavallo. Galvani afterwards found that contractions could be produced in the limbs of pre- pared frogs by the electricity of the atmofphere, and it was in confequence of fome arrangements which he made for this purpofe, that he was led to his great difcovery of animal elec- tricity. He found that he was able to produce contractions Proper galva- in the limbs of frogs without the aid of any foreign or artificial $*' or."ntracf , . . / ft . °" 0ons without excitement, merely by the application of a conducting fub- excited eleftri- ftance from the nerve to the mufele. Thefe contractions were*"*' capable of being produced, of whatever fubfiances the circuit of communication was compofed, provided only they were all conductors of the electric fluid. The effects were found to be much increafed by applying a metallic coating to the nerve. He found this peculiar fpecies of electricity to exift in a great variety of animals, and that the contractions may be excited * Sultzer in his Theorie des Plaifirs, quoted by Fabbroni, Philof. Journal, quarto JV. 120, mentioned the tafte by contaft of two metals.-- ~N, either 29S Theory of Gal- vani j that the interior of the muicle is charged plus, and the nerves form a commu- nication with the outfide. Gain's Letters on Animal Electricity, J793- Volta's Letters to Cavallo, 1793' "No charge in the animal. but electricity from the con- tact of different metals applied to the nerves. Thegalv. aftion fuppofed to exift in nerves only. HISTORY O!1 GALVANISM. cither in the whole body or in particular parts of it, as long as the animal pofieffes any remains of vitality. Galvani fuppofed thefe phenomena to be analogous to the effects of the Leydcn phial ; that there is an ejtcefs of electric fluid in the interior of the mufcle or in the nerve, and a deficiency on the outfide, or vv. The nerve he conceived to aft the part of the wire in the Leyden phial. Soon after the publication of Galvani's work, Valli's Letters on Animal Electricity appeared in the Journal dePhvfique, vol. 41. & feq. In the Tranfactions of the Royal Society for 1796, Volta's letter to Cavallo was publifhed, which befides giving an ac- count of Galvani's difcovcries, contains many original experi- ments and obfervations. The analogy of the Leyden phial he (hows is without foundation, for he found that he could excite fimilar contractions in the limbs, when the conducting circuit only touched two parts of the nerve, two mufcles, or two parts of the fame mufcle ; in order to accomplifh this, it is however neeeflary to ufe two different metals. He fuppofes that in thefe cafes the mufcular contractions are produced by a fmall quantity of electricity which is excited by the action of the metals upon each other ; this he conceives to depend upon a general law of the electric fluid, and that its effects are vi- fible in the experiments of Galvani only becaufe the prepared animal is the moit delicate fpecies of electrometer. Volta endeavours to prove by experiment, that the action is always in the firft inftance upon the nerves, and that the mufcles are only affected through their medium. He imagines that it is not neeeflary that a communication fliould exift between the nerve* and the mufcles according to the opinion of Galvani, he ima- gines that the contractions will be produced in the limbs, if the influence be only made to pafs from one part of a nerve to another part of the fame. But we (hall find that in this idea Volta is probably miftaken, as in his experiments the moifture adhering to the nerve formed a communication between it and the mufcle. He found that if different parts of a nerve, or indeed if the body of the animal in general, be laid upon two different metals, and thefe metals be made to communicate by a conducing fubftance, mufcular contractions are produced. Thefe experiments fucceed with more certainty when the fkin is removed ; this precaution is more elpecially requifite if the animal have a dry fkin, as is the cafe with birds and quadru- peds. HISTORY OF GALVANISM. 299 peds. In a fecond letter which is printed in the fame vol. of the Phil. Tranf. Volta purfues his experiments and obferva- tions upon the fubject of galvanifm. If a (ingle mufcle, or a part of it be armed with coatings of two different metals, and thefe be made to communicate by a conductor, the contrac- tions will be excited, but no effect will be produced if two coatings of the fame metal be employed. Worms and fnails Of the various he found could not be excited by this influence ; but flies, «»n»ls, thofe r », only were fauna beetles, grafshoppers, and butterflies, he found were lubject to beaffeaed to its action. Upon the whole it appears that thofe animals which have dif- only which have diitinct limbs, with flexor and extenfor muf- and thofe ^uf-C* cles, are excitable by animal electricity. In thofe animals cles only which which are acted upon by the galvanic influence, Volta found ^ ^^ that it was only the mufcles which are under the direction of the will that can be made to retract ; in his experiments he never perceived that the heart was affected by the two metals, though this organ is thrown into ftrong contractions by the flighted chemical or mechanical ftimulus. The two metals which were found by their union to perform the moil power- ful effects were zinc and filver. Volta placed thefe metals Zinc and filver. one on each furface of the end of the tongue j when they were brought into contact no motion was produced, but a ftrong fenfation of tafte was excited. When the metals were applied to the root of a tongue cut from the mouth, contractions were produced. In the fame year in which VoIta\s leiters appeared in the Fowler's Effay, Phil. Tranfactions, Fowler publifhed aneflay on Animal Elec- I7?3» Whether r J galvanifm be tricity ; thefe works muft therefore be confidere as equally ele&ricity. original. The extracts given above from Volta's letters, prove that he confidered the phenomena of galvanifm *-o de- pend upon the operations of the electric fluid; other experi- menters however conceived it impoflible to reconcile the new difcoveries with their previous ideas of the nature of electri- city, and Fowler commences his treatife by this enquiry. In order to afcertain this point he inveftigates the circumftances which are neceffary to the production of the mufcular contrac- tions. Thefe he found to be the contact of the two metals Conditions of with each other, and their communication with the animal ; the e,.!L : ' . ' two different the contractions may alfo be produced by bringing the metals metals fhould in contact with each other in water, without either of the touch each other metals touching the animal. When the metals are applied to v\z, the nerve' the and mufcle j £00 HISTORY OF GALVASlS^f. either imme- the nerve alone, Fowler dill confiders it rcquifite that fliers ^mediately by ^ a conne^'°n between the nerve and (he mufcle ; in orcli- water. nary cafes this connection is effected by the moidure which adheres to the nerve, a circumfhmce which Volta feems to have overlooked. Valli had endeavoured to form a theory of animal electricity founded upon the idea that the eleclric fluid was unequally difperfed through the body, and that the appli- Attcmpttodif- cation of the metals produced an equilibrium; Fowler per- prove the theory formed a number of experiments to difprove this idea, and of an electric . i ' l , * ■ "h charge in the apparently with luccels. He concludes the tint part of his *nima! iyftcm j efFay by giving it as his opinion, that the phenomena of galva- and to fjicw that -r , -i Cl * 1 1 i f 1 \o • 5- garfyanifm is not mmi are not reconcileable to the known laws or electricity, electricity, becaufe for the excitement of the eleclric fluid, motion between an eleclric and a condu6tor appears to be neceflary, whereas in thefe experiments two metals only are the fubi!ance& em- ployed. He alfo failed in caufing charcoal to conducl this influence, though it is a better conductor of eieclricity than the animal fluids ; in this particular, however, he appears to Torpedo-. have been miltaken. Pie confiders the influence as very dmi- lar in its effecls to the action of the torpedo* though not alto- EfFecl on worms, gether the fame. He was unable to produce the mufcular and on the m- contraclions in worms, yet he found that when a worm or a voluntary mui- J , clcs. leech lying uponfllver, put its mouth upon zinc, it appeared to differ great uneafinefs. Dr. Fowler in the fecond place proceeds to enquire, whether all the mufcles of the body be iubjeel to this new influence. He found it difficult to excite any contraclions in the heart, though at length, by ufing pro- per precautions, he fucceeded ; but he was not able to excite Difcovery of the contraclions in the domach or intedines. He difcovered that flain » Wb when the nerves of vifion were acled upon by the two metals, a fenfation of a flalh of light was perceived in the eye. When inflammation was excited in a limb, it appeared to acquire additional fenfibility to the galvanic influence. Fowler's work Profefibr Robi- concludes with a letter from Profeffor Robifon, who made ion makes a fome new obfervations upon the produclion of the galvanic pile of zinc and . iilver. flafh, and fird noticed the effect produced by applying the tongue to a number of pieces of diver and zinc alternately piled upon each other. Darwin in 1794 In 1794- the fird volume of the Zoonomia was publiflied ; confiders galva- j}arwm fpeaks of the phenomena of galvanifm, and confiders eity. them as eleclrical. The mufcular contraclions he fuppofes depend HISTORY OF GALVANISM. 301 \lepend upon the fenfibilify of oar nerves (o fmall quantities of the electric fluid. Bennet difcovered by means of his electro- Bennet's early meter, that zinc, when feparate from other metals, always is .'^"J °f c c in the minus ftate, and filver in the plus ftate ; when therefore zinc (1789.) they are brought nearly together, a fmall plate of air is charged like a Ley den phial ; when the metals are brought into con- tact this is difcharged. In the Phil. Tranf. for the year 1795, is a Paper by Dr. Dr. Wells, Wells on the t abject of gatvanifm. He propofes for confide- J^JJJjf. ration the three following enquiries; Do the contractions ob-ments thatani- ferved by Galvani depend upon any property peculiar to the"™'5 are afte&- livingbody? What are the conditions necelfary for the ex-means of humi- citement of the influence? Is it electrical? With refpect todit'/i that the .1-^ n. . r r 1 -lrti ftate °* t'15 me* the nrft queltion, he luppoles that animals act only on account taib ;s nnt aj_ of their moifture. With refpect to the fecond, he found thatteied by contact; one metal and charcoal excited the contractions as readily as phenomena^re two metals; in this he corrects the miftake of Fowler noticed electrical. above. He however found that all charcoal will not act as a conductor of the influence, in which opinion Volta agrees with him. Wells does not agree in the hypotheuY adopted by Volta and others, that the contact of the metals produces an alteration in the difpofition of the electric fluid, for he very properly a(ks, why mould not the natural moifture of the animal afford a communication between the two metals before they are connected by any other conductor ? He farther difcovered, that. contractions could be excited by one metal only when it had been rubbed upon another metal, or even upon the hand. Charcoal may by the fame means be made to produce the fame effect ; he proved by a variety of experiments that the fric- tion does not in thefe cafes communicate electricity to the metal or the charcoal; we may conjecture that an incipient . oxidation, or feme other chemical change was produced upon the fur face of thefe fubftances. With refpect to the third queftion, Wells is decidedly of opinion, that the phenomena are electrical ; the influence being conducted by all conductors of electricity, and by them alone. Keiides the works here mentioned a number of communi- Various other cations appeared in the different fcientific journals of Italy, Fa?jrs,DHuQa" France, and Germany, and feveral diftinct treatifes were Monro, the In • publiflied on the fubjeft of animal electricity. Humbolt par- Jitute ofc J '■ • , , France, &c. tieularly 302 HISTORY OF GALVANISM. ticularly diftinguifhed himfelf by his afliduity in varying the experiments. Dr. Monro wrote upon the fubject, and the National Inftitute of France publiflied an elaborate report, drawn up by a Committee compofed of feveral of its moft learned members. As however thefe works do not appear to contain any facts which materially illuftrate the nature of the galvanic influence, or lead us to form any more accurate no- tions refpecting its operations, we fliall in this brief fketch FabronI: that only notice the papers of Fabroni, of which an account may merely a^he- *)e f°und m tne 4tn Vo*- °f Nicholfon's Journal. He deduces mical phenome- from his experiments that galvanifm is intirely a chemical phenomenon ; he finds that metals become oxidated when in conta6twith each other in circumflances where this would not take place if they were kept feparate. This idea he confirms by many obfervations and experiments, and fuppofes that when the galvanic influence is excited by the action of two metals that a chemical affinity is exerted ; he does not how- ever point out very clearly in what manner the chemical ac- tion which is exerted by the metals can be connected with the phenomena of galvanifm. Hiftoryofthi* In the year 1789, Cavallo publiflied a new edition of his JJ^EIearicit31," Eleftricitv> and hc added a good account of the principal and the Supple- facts in galvanifm ; an ample hiilory of this fcience m3y be ment to the En- a[f0 f0Upd \n the Supplement to the Encyclopaedia Brilannica. cyclopaedia Bn- \ , , , r i V tannica. -1" "lis itate our knowledge of galvanilm continued until Grand difcovery the beginning of the year 1 800, when Volta made his difco- VoIta.P,e ^ verv °f tne apparatus ufed called the Galvanic Pile. In the Phil. Tranf. for that year is a letter from Volta containing an account of the pile, and a detail of many curious experiments Defcription. which he had performed with it. This inftrument confifts of a number of circular pieces of two different metals, laid alter- nately upon each other, with a piece of moiflened pafieboard or fkin interpofed between each pair. The metals which anfwer the belt for this purpofe are zinc and filver, which were found to be the moll powerful in exciting the mufcular contractions in the former experiments. If the two pieces of metal which form the extremities of the pile be grafped firmly Galvanic /hock, in the hands previoufly moiflened, a fhock will be felt through the hands and arms, more or lefs powerful in proportion to the fize of the pile. This /hock may be repeated a^ long as the' UISTORY OF GALVANISM. 303 the pafteboard between the metals retains its moifture. Volta, conceives that this apparatus in every refpect refembles the electric organ of the torpedo and gymnotus electricus. As foon as this difcovery became known in England, a va- riety of experiments were performed with the new apparatus, and many very interefting and important facts were difcover- ed : thefe are for the moft part detailed in Nicholfon's Journal, Vol. IV. & feq. In the 4th vol. p. 17 4, is a paper written by Mr. Nicholfon Carlifle andNi- himfelf. He begins with a defcription of Volte's pile, and S^^ then relates the remits of fome experiments which were per- city of the pile, formed upon a fimilar one by himfelf and Mr. Carlifle. By *]^j*/Jer. its ufing the revolving doubler they found that the electricity was and the decmp» minus in the filver end of the pile, and plus in the zinc end.J!t'07iof'lv*ter» Mr. Nicholfon piopofed that the influence. mould be permitted to pafs from one end of the pile to the other through a tube of water; for this purpote a divifion was made in the conducting wire, which was compofed of copper, and the two ends of it were terminated in a fmall tube of water. Immediately the wire connected with the filver end of the apparatus began to produce a gas, which was found to be hidrogen, while at the fame time the wire connected with the zinc end became oxi- dated. Recourfe was then had to a wire of platina which is into hidrogen not oxidable, and immediately gas began to be evolved from and ox'Scn' both ends. Upon examining the gafes feparately, that from the filver end was hidrogen, that from the zinc end oxigen, and they were generated nearly in the proportion requifite to produce water. This experiment, as well with refpect to its importance of immediate effects, as with regard to the confequences which th»s experiment, may be deduced from it, may, I think, be juftly confidered as the moft important that has occurred iince the difcovery of ox- igen by Dr. Prieftley . The electric fpark was diftin&ly vifible Electric fpark in thefe experiments. vifible. Mr. Cruicklhank relates his experiments, in which he made Cruickmank. life of the interrupted circuit after the manner of Mr. Nichol- Efteclonche- fon ; he caufed the influence to pafs firft through diftilled water tinged with litmus, and afterwards through water tinged with Brazil wood. In the firft cafe there was a rednefs produced by the zinc, and in the fecond by the filver wine. By fubmit- ting a portion of water for a long time to the action of the pile, a fenfible diminution was obferved in its bulk. He obferved the SO'h HISTORY OF GALVANISM. the production of hidrogen and the oxidation of the zinc end when he ufed a communication of copper ; and when he em- ployed a wire which was not oxidablc, he obtained both hidro- den and oxigen according to the obfervation of Mr. Nicholfon. Redu&ion of He permitted the influence to pafs through a folation of a me- thcir ablution. tumc ^y an^ found after ibme time, that the metal began to be revived at the filver end of the apparatus. Mr. W. Henry Mr. William Henry, of Manchester, fubmitted concentrated phuric and nitric folphuric acid to the influence of galvanifm : he made ufe of a acids, but not wire of platina. Not only the water which always enters t e muriatic. mtQ ^Q comp0fi*ion 0f this acid, but alfo part of the acid itfelf, appeared to be decompofed, as the oxigen which he procured was in a larger proportion to the hidrogen obtained than is fuf- ficient to compofe water. Nitric acid was alfo decompofed, Oximuriaticwasand the water of muriatic acid. When oximuriatic acid was oxigena e . fUDjeftec} to its influence, the water was decompofed, and the Gafes could not ac^ was deoxigenated. Gaffes do not appear to be conduc- be fubjccled to r , . . n° r . ■ __ TT rr ,, \tm tors ot this influence, to that Mr. Henry was not able to try its Ammonia was effects in decompofing muriatic acid gas. It alfo appears to ecompo e . jiave ^e power of decompofing ammonia. (To be continued.) * On account of the great Quantity of original Communi- cations, the Scientific Nexus and Account of Books is neceffa- fily deferred* X. Y. Z. is informed that the derivation of chrome or chromiwn is from xpw/ua, color ; and was adopted by Vauquelin, becaufe its co?npounds vjiih oxigen are coloured. See Pldlof. Journal, quarto, 11. 444. g 1'tiLK* Journal I'ol. II. H. I. p. So. i //. _ *Jo3U v -//.* / w/t'Niffuh //// nt //tt nydutuue f >», Fig. 3. Pi'efsure Engine . Fig .l.at Schemnitz K fig . 2 . M'Goodwyns T \timm Mu&ow Sc. Ritfsdl G>? fhilos Journal Vol.JI.J'L.JL.p.do. Mmtbw SoJfotftm Co'. Ftl£L>J Journal 1 W . //. Ft . Ill . /> . So . ' Thilos Journal lot . 11. PI . llr. p . 80 . <^/£c/um a/ //tc - //err 0/ ////tMati Fig. 7. >»»»/»»* wwm/////w//m. W/MMWMMmn »>»»»»»»»»»?>/»>. r%.4 \f«MMff{f{(f/UmfMMftr. Fig. 6. Sr. Rufsrll Cc* -PhiLos Journal Vol. II. PI .Kp.144 Iron Cradle . Fig. 2 Fig. 3. Fig. 4 Mtrilow Sc. Hu////,/ (>// ////' //N'o'/y "/ .~J/y/// /■> ro//;?/ '/, Fy.Z. Fy.l. iy.3 Fig. 4 Midior Sc Ku,:,rll Cn*. Thilos Journal Vol. IT.TL. PTLp. /y^t. 1 fr. f/fV^AWJ y '■ 'fJUt/i>t/ //, (\r. » Fig. 7. ^ £*^ / __G^V_// p\\ #^ ! A Pr i i ^y*1 o / \ ^^ c \ / / L • /H y*^~ ^N^Y / E/ S y^ JjV / / IP / tAa O BA/ /L^^_-^ \K mdow Sc.&u/iell Cf Philot Journal Vol. II. PI. VHLp.144.. Ili/. .fcJtyfitii * 2>hdo.> Journal Pel II Fl.lX.p. «*. T/uA> s Journal Vol. IT. PI X . p. 224-. Mi '€&&$^i5fi&.< U ^ra^/^A, lUUt PiO •-• tfnlas .fcurruzl Tbl. IT. PI. J7>. es / . //' / r^i. , /fry <^4Y» « tkev-t //f/c^y. 3fr2 J^. 3. LJZlI.p.zt4.. Elevatvon on die line AB . ip- m ffl : Seeti/jrt on the lute CD. i« Plan ■ 1 — — — ■ ^. .................. ft ; jy m| j=5 ~^F=,~Tft tt:L j lb o c o .0 OLJa 3 5 ....... -35 1 O 0 O 0 Oj r . \

\\ a ft |p 0 0 0 0 | e o o o on 1 0 0 0 O Oj !| s I lo 0 0 0 0 j'"j] '"" .'" 8 0 o 0 ol 1 V H- ■■> "--*y^ -■?? H-t-H-1- 'IMI, ^ ,»'iyeA» of Metrrs BEE S a,,/.*// 7;-' I'hil.s.Jrum.,/ Vol .II .VI. XIII .p. 304 <>/i ///< * S(>r//// f/'ftfUf/r/J. Fig.l. Gnefensteift (l mn iff Shil< SUitr Fiq. 2. Trtm. Mica Cneijs State SUtfr n m Wfr 'Rai hi Thilos. Joumul Vol . II. PI . XIV. p. 304- /// i/)s//t/>\).) (>./•///'/////////.) <"/< ///<■ r//. W/^r I ThtTos.Journal Vol. IE. PI. XVI. p. 304. Cwfy±y%(\^Lccd/ and/, MC r;«M/*AJ3-rrn/y. Fig. 3. ^\ Fuj.l. *,J> 16aio- ScRufiretl G'C 1 INDEX, A. AcCUM, Mr. Fred, on the methods by which foda is at prefent prepared for the Englifh market, 241 Air, obfervations on the velocity with which it iflues out of veffels in different circumftances, by Mr. Banks, 269 Ammonia, experiments on the'production of the muriate of, by Dr. Campbell, 117 Anhydrous fulphate of lime, defcription of, by Comte de Bournon, 190.— Its analyfis, by R, Chenevix, Efq. 196 Atkins, defcription of his hydrometer, by J. Fletcher, Efq. 276 Auftin, Dr. 185 B. Bachelay Abbe, 219 Bacon, 10 Banks, Mr. on the velocity of air iffuing out of a veffel, 269 Barometer, remarks on the effects of found upon the, by Sir H. C. Engle- field, 18 i Barraud, Mr. 227 Barthold, 219 Barton, Dr. 139 Barytes, obfervations on the figure of the fulphate of, by Mr. H. Sarjeant, 253 Belidor'3 hydraulic architecture, 5 Bells, inftance of the fudden changes of direction of the found of, 125 Bennet, 174, 285 Berthollet, 8 Beft, Mr. 20 Blumenbach, Profeffor, 291 Borda, 252 Bolton, 252 Vot. II. Boracite, note refpecting the, by Clt# Vauquelin, 120 Boftock, Dr. his hiftory of galvanifm, 296 Bofwell, Mr.. John Whitley, 1 Boucherie, 188 Bouguer, 171 Bournon, Comte de, his account of ftones fallen on the earth, 259. — On the an- hydrous fulphate of lime, 190. — On the phofphorefcence of the tremolite and Dolomie, 290 Boyle, 10 Boyle, 165 Bradley, Dr. Ez. Walker on h'rs method) of obferving tranfits, 22 Brazil wood, its qualities, 202 Brougham, 166 Bullock, Mr. James, 77 Bullock, Mr. William, his drawback locfc for houfe doors, 204 C. Cachou, its qualities, 201 La Caille, his aftronomy, 6f Caloric, its effects on imbibed folar light, 104. — Its exiftence in the oxigen of fupporters, 94 Camac, Mr. Campbell, Dr. H. on the art of paper making, 6.— His experiments on the production of fulphate of foda, carbonate of magnefia, and muriate of ammonia, If J Camphor, its action on copal, 238 Canton, Mr. 106 Carbonic acid gas, fimple method of de» compofing it, 46.— In atmofpheric air, 161 Carcel, his improvements in a lamp upon Argand's principle, 10S b Careau, INDEX. Careau, his improvements in a lamp upon Argand's principle, 10S Carlifle, Mr. 303 Cavallo, 289 Cavendifh, Mr. 92 Ceres, the new planet, 20, 48, 54. — Account of, by the Baron de Zach, 56, a 1 3. —Elements of its orbit, 57. — Dr. HerfchePs communications refpecting it, 141, 221 Chladni, 218 Chaptal, 8 Chemiftry, theory of, obfervations on the, by the Rev. J. Prieftley, 69 Chenevix, Richard, Efq. 192, 293.— His account of a peculiar vegetable principle contained in coffee, 114.— Analyfes of the different fpecies of arfeniates of cop- per, 194.— Analysis of anhydrous ful- phateoflime, 196 Clennel, Mr. John, on the ait of making glue, 235 Clofe, Mr. 1, 238. — On the compoii- tion of writing ink, 145 Cockchafer, obfervations on the deftruc- tion of its grub, by Edward Jones, Efq. 73 Coffee, on a peculiar vegetable principle contained in, by R. Chenevix, Efq. 114 Cold, its effects on imbibed light, 106 Colours, obfervations on the theory of, by Dr. Tho. Young, 78, 16a Coir.buftibles, 1 1 Combuftion, Dr. Tho. Thomfon's eluci- dations of, 10, 92.— -Supporters of, their analogy to the products, 93. — Remarks on Dr. Thompfon's theory of, 206 Condenfer, defcription of Mr. Read's compound electrical, 284.— Method of applying them to the galvanic inftru- ment, 286* Copal, advantage of, in the compofition • of ink, 147 Copper, blue, carbonate of, 195 Coventry, his micrometers, 166 Coulomb, his experiments on rr.agnetifm, 143.— Formula to determine the mag1* netic force of a body, 144 Crawford, 95 Cruickmank, 70. — His anfwer to Dr, Prieftley's memoir in defence of the doctrine of phlogifton, 42 Cuthbertfon, Mr. John, on Volta's -ex- periments, upon which he founds his theory of galvanifm, 281 Cuvier, Mr. 140 Darwin, Dr. 162.— His zoonomia, 30a Davis, Mr. 256 Davy, 116, 164 Denifard andDeuille invented the preffure engine in 173 1, 5 Defcroizelles, on the danger of keeping phofphorus without particular caution, 41 Deuille, one of the inventors of the pref- fure engine in 1731, 5 Dize, 99 Dolomie, obfervations on its phofphoref. cence, by the Comte de Bournon, 290 Dragon's blood, its qualities, 201 Drawback lock for houfe doors, by Mr. Wm. Bullock, 204 E. Echos, deceptions from, 124.— Effect of undiftinguifhed, upon the voice or an inftrument, 126 Electric fluid, explanation of its action in the galvanic pile, 287.-— Atmofpheric, 286. — Expanfion of carbonated hidro- gen by, 184 Engine, defcription of a cheap, for raifing water, by Mr. H. Sargeant, 60 Engines, hydraulic, improvements of, 2 Englefietd, Sir Henry C. on the effect of found upon the barometer, 181 Engliih ftandard, comparifon of an with the French definitive metre, 244 Erfkine, Mr. 257 Ether, INDEX. Ither, table of Its colorific undulation, 169 Ethereal medium, attraction of bodies for the, 85 Euler, 79, 86 F. Fabroni, 302 Falconer, Rev. Tho. his geography of Strabo, 224 Finery cinder, 234 Fire, Thomfon on, 98 Fiih, luminous, 34 Fletcher, J. Efq, on Atkins's hydrome- ter, 276 Fluor fpar, its phofphorefcence explained, 99 Fourcroy, 197 Fowler, 299 French and Englilh paper, their relative qualities, &c. 7 Froft, its ufe in the cryftalli jation of falts, 119 Fuftet, 2,02 JFuftic, 201 Gallic acid, 199 Galvani, his work, 297 Galvanifm, hiftory of, by Dr. Boftock, 296 Gafeous oxiee of carbon, its fpecific gra- vity, 43. — Its production from metallic calces, 44 Gaufs, 51, 59 Glauber's fait, method of obtaining it, 118. — Its ufe in the preparation of foda, 243 Glow-worm, experiment on its light, 33 Glue, account of the art of making, by Mr. J. Clennel, 235. — Its characters when good, 236 Goodwyn, Mr. his hydraulic engine im- proved, 2 G,pugh, Mr. John, on ventriloquifm, 122— Anfwcr $0 Jjis eflay on the the- ory of compound founds, by Dr. Tho- Young, 264, 267 Graham, Dr. 139 Grains of Avignon, their qualities, 202 La Grange, 210, 265 Granite, account of, by Mr. R. Jamefon, 225 Gregory, Mr. Qlinthus, his treatife on aftronomy, 64. — Obfervations on Mr. Pearfon's analogy for deducing the greateft equation,1 65 Gren, 239 Greville, Rt. Hon. Charles, 258 His, fpecimen of anhydrous fulphate of lime, 191 Gulllot, Cit. Merat, his reflections npon the art of tanning, 70 Guyton, Cit. his ftove, 24 H. Hall, Sir James, 230 Halley, Dr. 49 Hatchett, Charles, Efq. his analyfis of a mineral fubftance from North America, 129, 176 Hah"y, T74, 197 Hearing, phenomena of oblique, explained, 124 Henry, Mr. 185, 186, 304 Herfchel, Dr. 164; — His obfervations on the new planets, 221 Hidrogen, carbonated, obfervations on its expanfion by electricity, 184 Hidrogen gas, fulpburated, its effects on fpontaneous light, 10 1 Higgins, Dr. 107 Hifkerdeau, 188 Hooke, 10, 169. — His explanation of in- flection, 172 Hornblower, Mr. J. C. his obfervations on the beams of fteam engines, 68 Howard, Edward, Efq. his experiments on ftony and metalline fubftances fup- pofed to have fallen on the earth, 216, Hulme, Dr. Nath. on fpontaneous light, 31, 100 b 2 Humbold, Humbold, 151 Hunter, Mr. John, 240 Hutton, Dr. 67, 229, 331 Huygens, 76, 87, 91, 173 Hydraulic engines, 1 Hydrocarbbnates, its combuftion in oxigen gas, 44 Hydrometer, defcription of Atkins's, by J. Fletcher, Efq. 276 IncombufHbles, 11 Ingehhouz, 151, 158 Ink, ancient method of composing, 147. — Obfervations on the competition of, by Mr. W. Clofe, 145. — Preparation of indelible, by Mr. T. Sheldrake, 237. — Receipts for the compofition of, 146 Iron, chromated, its difcovery in France, 64. — Native malleable, 260.— Obfer- vations on its converfion into fteel, by Dr. Prieftley, 233 Inftrument, defcription of an, to meafure the force of the blaft of bellows, 272 Instruments, hiftory of, for fhewing mi- nute quantities of electricity, 288 Jamefon, Mr. Robert, on granite, 225 Jefferfm, Mr. 140 Jones, Edward, Efq. on the deftru&La of the grub of the cockchafer, 73 Jordan, Profeffor, 63 K. King, 175, 217 Kite, incident of a, deftroyed by a weazel, 75 Klaproth, 192, 197, 293 L. Lachenau, Haflel, his new procefs for claying fugars, 187 Lalande, 48, 52. — His aftronbmical prize, 141 Lamp, defcription of one upon Argand's principle, by Citizens Carcel and Ca- ieau, 108 3 INDEX. Landriani, Chevalier, 63 Lange, Citizen, 109 Lavoifier, 10, 70, 95 Lenoir, 248 Lethehyey, Captain, 63 Lewes, Mr. 107 Light, emitted from bodies, Dr. Hulme on, 31. — Obfervations on the theory of, by Dr. T. Young, 78. — Anfwer to Newton's objections to the undulatory fyftem of, 90. — Its exigence in com- buftibles, 94. — Experiments on the fpontaneous emifiion of, from various bodies, by Dr. Nathaniel Hulme, ioo„ —Remarks on the theory of, by Dr. Young, 162 Lime, its precipitation by an infufion of tan, 71 Lithophylacium Bornianum, 258 M. Maclane, Mr. 257 Mageas, 166 Magnefia, experiments on the production of the carbonate of, by Dr, Campbell, 117 Magnetifm, its galvanic effects, 62.— f Experiments on, by Citizen Coulomb, 143 Mamoth, remarks on the, by Louis Va- lentine, 138 Mandreporae, formation of, 253 Mayow, 10 Meafures, tables of the French, 250 Melfier, 58 Metal, new, 178, 180 Meteor, account of the explofion of a, near Benares, 255 Metre, comparifon of the French defini- tive, with an Englifli ftandard, 244 Meyer, 98 Michell, 170, 174, 227 Mill for grinding hard fubftances, by Mr. G. Terry, 206 Mineral fubftance, analyfis of a new, by Charles Hatchett, Efq. 129 Mineral, analyfis of a, from North Ame- rica, by Charles Hatchett, Efq. 176 Mineral, INDEX. Mineral, from North America, its compe- tition, 177 Moles, their general habits, 74 N. Newton, 79, 168 — His objections to the undulatory fyftem of light, 89. — Prin- cipia, 88. — Theory of the law of un- dulations, 266 Nicholfon, 304. — On Volta's pile, 303 Nitrous gas, its effects on fpontaneous light, 103 Nomenclature, remarks on, 21a O. Olbers, his difcovery of a new planetary body, 20, 58 Ore, from North America, defcriptionof, 130, 13a Oxigenation is not the fame act as combuf- tion, 11 Oxigen gas, tables to fhew the difference in the quantity and quality of, obtained from plants expofed to folar light in ri- ver water, and water impregnated with carbonic acid, 154, 156 Pallas, the new planet, remarks on, by Baron de Zach, 213. — Elements of the orbit of, 214. — Ephemeris of the pofi- tion of, 215. — Di mentions and nature of, by Dr. Herfchel, 221 Paper-making, remarks on by Dr. H. Campbell, 6 Pearfon on the new planet Ceres, 48.— ' his analogy for deducing the greateft equation, obfervations on, by Mr. O. Gregory, 65 Pelletier, 98 Phlogifton, anfwer to Dr. Prieftley's de- fence of the doctrine of, by Mr. W. Cruickfhank, 42 Fhofphorefcence, caufe of, in the tremo- lite and dolomie, 292 Phofphorus, caution againft the ufual me- thod of keeping it, 41. — Experiments on Canton's, 105.— Its acidification in nitrous acid, 209 Piazzi, Mr. 56 Pictet, 164, 246, 248 Pigott, Mr. 182 Pifton, elaftic, 6 La Place, 95 Planet, new, difcovered by Dr. Olbers, 20 Plants, experiments on the vegetation of, by James Woodhoufe, M. D. 150.— Effects produced by their growth in at- mofphericai air, 152. — By their leaves, expofed to folar light in a mixture of atmofpheric and carbonic acid gas, 153. — Objection to the hypothetic of their emiffion of oxigen and abforption of azote, 159.— Tables to fhew the effects of their leaves when expofed to folar light, 160 Playfair, Profeffor, 229, 23 1 Pontier, 64 Pre/Ture engine of Trevithick, 5. —In- vented in 1 73 1, ib. Prieftley, Dr. his method of decompofing carbonic acid gas, 46 Prieftley, Rev. J. his obfervations on the m theory of chemiftry, 69, 136, 158. — 1 On the converfion of iron into fteel, *33 Prony, Mr. 246 Proof fpirit, its fpecitic gravity, 277 Prouft, 72, 195, 116. — On tanin, 198, 200 Pump, method of applying a temporary forcer to a, by Mr. Richard Trevi- thick, 216 Putrefaction, obfervations on the caufes why a large quantity of fait prevents, and a fmall quantity haftens, 239 Pyrites, account of the, found in the ftone from Benares, 260 Rags, for paper, valuable obfervations on, 7 Read, INDEX. Read, Mr. John, his condenfcr, 383 Robertfon, 67 Robifon, Profeflbr, 59, 300 Boy, Genera!, 245 Rumford, 158, 164, 175 Sarjcant, Mr. H. his cheap engine for railing water, 60. — On fulphate of ba- rytes, 253 Saufl'ure, M. de, 291 Schcele, 8, 97 Schemnitz, hydraulic engine of, improved, 1. — Compared with Goodwyn's, 3 Schroeter, Dr. J. H. his letter refpeding the new planet of Olbers, 20, 58, 142 Science, account of books, 223 Seeds, effects produced by the germina- ; tion of, in atmoipheric air, 151 Seguin, 116 Selkirk, Earl of, 230 Senebier, 96 Sheldrake, Mr. Tho. on the preparation of indelible ink, 237 Short, 164 Shuckburgb, Sir George, 245 Silk buried in the earth, remarks on, by the Rev. T# Wiiftn, 222 Smith, Mr. 179 — Dr. 265 So;ia, experiments on the production of fulphate of, by Dr. Campbell, 117. — Account of the method by which it is at prefent prepared for the maiket, by Mr. Accum, 241. — Its value, 242. — Method of preparing it in Pruffia, 243 Sound, deflection of, 91. — Diagram to fhew the effects of, on the head, 123. Its effects on the barometer, by Sir H. C. Englc field, 181 Southey, Mr. 218 Spedding, James, Efq. his engine for raif- jng water, 6i Stahl, 18 Steam engines, obfervations on the beams of, by Mr. J. C. Hornblower, 68 §ieam, apparatus for heating water by means of, by Mr. Arthur Woolf, 203 Stones, experiments on, foppofed to ha^e fallen on the earth, by Edw. Howard, Efq. 216, 254 Stove of Guyton, 24 Stromager, Mr. 121 Sugars, new procefs for claying, by Cit. Haflel Lacbenaie, 187 Sumach, its qualities, 201 Supporters of combuftion, n Tanin, Memoir on, by M. Prouft, 198 Tanning, obfervations on, by Cit. Merat Guillot, 70 Tellurium, account of, 62 Terry, Mr. Garner? his improved mill for grinding hard fubftances, 206 Thumfon, Dr. Tho. his improvements in the doctrine of combuftion, 10, 92, 151.— Remarks on his theory of com- •buftion, 206 Time Pieces, irregularities of diminished, by Mr. Ezckiel Walker, 70. — On the variation of rate in, by Mr. E. Walker, 273 Tremolite, on its phofphorefcence, by the Comtc de Bournon, 290 Trevithick, Mr. Richard, 5. — His me- thod of applying a temporary forcer to a, pump, 216 Troughton, his ufe of fpider's webs in the foci of tejefcopes, 23. — His comparer, 24.7 Tfcharfey, Major, 63 Vacuum, effects of on fpontaneous light, 104 Valentine, Louis, his remarks on the Ma- moth, 138 Valli, 298 Vauquelin, 192, 199.— On the boracite, 120 Ventriloquifm, obfervations on, by Mr* John Gough, 122 Vibrations, table of, 274 Vince INDEX. Vince, hi* aftronomy, 67 Vinci, Leonardo da, his treatife on paint- ing, 142 Volta, examination of his experiments, by Mr. J. Cuthbertfon, 281, 298 U. Undulations, lateral, 88, 163 W. Walker, Mr. W. on the new planets, 21 Walker, Ez. his method of obviating the effects of the wire in tranfits, 22.— On the irregularities of time pieces, 76. — On the variation of rate in a time piece, 273 Ward, his elliptic hypothefis, 49 Water, apparatus for heating, by wafle fteam, by Mr. Woolf, 203 Weights, tables of the French, 251 Wells, Dr. 301 Werner, 228, 232 Williams, Mr. 255 Wilfon, Rev. James, on filk buried in the earth, 222 Winthropp, Mr. 130 Wiftar, Dr. 139 Wood, rotten, its luminous appearance, 33 Woodhoufe, Dr. James, his experiments on the vegetation of plants, 150 Woolf, Mr. Arthur, his apparatus for heating water by wafte fteam, 203 Y. Young, Dr. Thomas, on light and colours, 78, 162.— Obfervations on the effect of found upon the barometer, 183. — His revifion of the compaiifonof the French metre with the Englifh ftandsrd, 249, Anfwer to Mr. Gough's efiay on the theory of compound founds, 264.-— Corrections in his paper on the mecha- nifmof the eye, 268 Z. Zach, Baron de, his obfervations on the new planet Ceres, 56.— And Pallas, 213 END or THE SECOND YOLUMI, Printed by W. Stratford, Crcwn-Court, Temp!e-Bar. s