an eBeveoeer 1S eee easinbsancsenene Serene Peeet Fee teen tiestitsescesite SILT obey preeederte eoey: woleste sg. she ba bee htt se ste ossqu Le es betedeserameecyet ePeeeerert rer ies) one esseeonened a6 Oe paeyete SSF55534 eee eRes sees SS o> 4 ore e+ Gees sett Seedtenenes’ : sesetittstsiistisistest sa eseaaahce! sseaattbestebagyseec.taee- beep eae oats pagnopassee | 6ee.e2 peed nao 8 ote arate a3 Seis phos : pape eine ee ribiars tessaee sere : ; ae syetatets ite ; pa pera sersese Bt5 ty Titre e002 Ge pe yOR emg averse ; ; 4 sestassaatebsishaiesaionpessteessert secesatels tibiae esenes jougenentestes bates por tyecees ; 3 eobbeerriesset steer cst "iSal¢lagaghcesgoeosua aston ts pest idessacesd soterpe rer ” 4 : gene sesere: Srptriee a3 reasrabetssiaesesenssaecaste a3 posoceeas Sor bbbe tt tee ipepeshaics stesstehitiicssitettitessrss eoeaee i tor yo geean se bee - tea : 4 -sene +P soho sie been ssassepseets irs tH tiestoeressesrit es t : * t sgrziehs 5 » arts pe phadareces prose? peeseeeryes sitet Tt. sehttrite thet gue Sees etaseey: Th a5. gate Hitbesctiae fie + withstands f rs Pere ittebens tite tt : z Westeseess ; ‘ eae ; 26nd pe bee bee: te t ii ets at i sores) ; f rs 5] spits sere : triessssresets 3 st hataa rsittesgtt3 : t | H tea beets ist sostel > : , ses a eeeehrE TS tty ae thiitste arate * ; tas : be tetssst- $s ae o . + ope ae at : : Hee : Hite Steet: 33: aH bf pecsrety id iH bese ¢ . as as3 te Ne (hip r A JOURNAL OF “NATURAL PHILOSOPHY, CHEMISTRY, AND DEA ect ds VOL. X. AMustrated with Engravings. BY WILLIAM NICHOLSON. LONDON: PRINTED BY W. STRATTORD, pone: COURT, TEMPLE BAR; FOR THE AUTHOR, AND SOLD BY HIM AT NO. 10, SOHO-SQUARE 3. AND BY J. MURRAY, NO. 32, FLEET*STREET. ee Ee, 1805, My ta Pe te 4g e “oe bah > 7 ', : Fae ee RIS i + iT yath oy ‘ mB . ee ae a0 iat é biden Inszord ene abnaoeRs th) oh ete MF 22 AM AIM eh bistelgad 0 8 + oi. wOM ; eh i pig e ROT “beuow) adot, “al ous . . Pst Me oy, one ia: ee ie snoaliW am ee WON a a defgi hh PIES A BS ‘EM: «3 a TO aast shen pousmIol {2uugn) il posgnsree. | AS rt ‘bargbe oa be 5 TF, eet ee Sian qaoreatioW Hr Fg a, | : Bie. ip Sane Ai wisi ahem © aad Yuga? ae ae q, il fy aes: fe noeen oe ona ft: aye e. a y Le AOF Bi “eo eireeg i in b 7 ye i ‘c. Ree ae i a: a : ters paging a) a beciigae, a seared ai Cy ii TH — 3 # Gite eh ies MAL ict: Grd are a caer Pe igects Ths steriemiit 1, Srtei tS ped . Hoisasum ma tsb aoe, ee gener se “on * ene _ ‘sho -{. "pba a sae grea ok cami 9 68 teri’ rT suse vee enigdigh alee A Worvteartanl a tie 3 hen foknoa gariven es vain thas aang fguut! OM oamatatic of Gur # ——— ie ae per ade Prats wean Fo 398 we ve * oe gv Bem cae Henan ee Wille’ ae PREFACE. Date Authors of Original Papers in the present Volume, are Sir H. C. Englefield, Bart. M.P.F.R.S.;° Mr. H. Steinhauer; Mr. John Gough; Ra. Thicknesse, Esq.; Mr. Wm. Wilson; C. Wilkinson, Esq.; J. Whitley Boswell, Esq.; Mr. W. Brandé ; Aletes; Mr. Jobn Dalton ; Capt. J. Mortlock ; W. F.S.; Mr. Charles Sylvester ; Mr. Ezekie] Walker; T. B.C.; Jos. Huddart, eg F.R.S.; E. O.; W. B.; Mr. N. Mendelfhon; C. L.; Mr. Accum; Right Hon. Sir Joseph Banks, Bart. P. R.S. &c. &c.; Mr. R. Matthews; Mr. J. Biddle; An Old Correspondent.—Of Foreign Works, Thenard; Hesinger; Bergelius; Morozzo; Bucholz; Dartigues; Schoerbing; Boullay; Lagrange; Lus- sac; Erman.—And of English Memoirs, abridged or ex- tracted; Smithson Tennant, Esq. F.R.S.; W. H. Wollaston, M.D. F.R.S.; C. Hatchett, Esq. F.R.$.; Gregory Watt, Fsq.; Right Hon. C. Greville, V. P. R.S.; George Pearson, M.D.F.R.S.; J. Hinckley, Esq.; F.S.A.; T. A. Knight, Esq. Of the Engravings the Subjects are, 1. An ancient Egyp- tian Engraving in Symbols, supposed to be astronomical. 2. Figures to illustrate the Galvanic Charge, by C. Wilkin- son, Esq. 3. Outlines of Pendulous Measures of Time, by J. W. Boswell, Esq. 4. Figure to illustrate Mr. Gough’s Theory of the Augmentation of Sound, by communicated Vibrations. 5. Instrument for surveying, by Capt. J. Mort- lock, 6. Instrument for taking Designs from Nature. 7, Plan and Sections of an improved Air-Pump, by Mr. Men- delsshon, 8. Figures to illustrate Mr. Gough’s Theory of the PREFACE." the Speaking Trumpet. 9. Improvement in Woulfe’s..Ap- paratus: 10. Method of drawing a Line in a Circle equal to the Side of its Square. 11. po quarto Plates, exhibit- _ ing highly magnified Representations of the Parasitic Plant which causes the Blight in Corn, from Drawings by M Bauer, Botanical Painter to the King. 12. Mathematical Diagrams of the Properties of Sialic, by Mr. Gough. 13. Application of Spectacle Glasses, by Mr. E. Walker. , Soho Square, April, 1805. TABLE OF CONTENTS ng THIS TENTH VOLUME,’ ener nm SL JANUARY, 1805. Engravings of the following Objeéts: 1. Ancient Egyptian Engraving in Sym- bols, fuppofed to be aftronomioal ; 2. Figures by C. Wilkinfon Efq,. to il- luftrate the Galvanic Charge. I. Concerning the original Inventors of certain philofophical Difcoveries :, the Refle&tion of Cold; Compreffion of Water in a metallic Veflel ; the Te- lefcope; and a perfpective Inftrument formerly defcribed. In a Letter from Sir H. C. Englefield, Bart. M. P. F.R.S. &c. &e. - Page 1 II. Account of an ancient Egyptian Sculpture with Hieroglyphics, fuppofed to relate to Aftronomy. In a Letter from Mr. H. Steinheuer. With an _ Engraving. - “ - - . 3 4 MI. Extra& of a Memoir on the fuming Liquor of Cadet. By Citizen The- nard. - - - = - - - w 6 Iv. Account of Cerium, a new Metal found in a mineral Subftance from Baftnas, in Sweden. By W. D’Hefinger and J. B. Bergelius. = - 10 V. New Experiments on Abforption by Charcoal, made by Means of a new Machine. By C. L. Morozzo. - .— = - - - 12 _VI. Farther Cbfervations on the Conftitution of mixed ‘Gafes: In a Letter from Mr. John Gough. - - - - - 20 VII. On two Metals, found in the black Powder remaining after the Solution of Platina. By Smithfon Tennant, Efq. F. R.S. From the Philofophi- cal Tranfaétions for 1804. - - - - - 24 VIII. Remarks upon certain Obfervations of Mr. Wilkinfon, refpecting Galvanifm. By Ka. Thickneffe, Efq. - - - - So TX. Abftra&t of a Memoir on the Poffibility of obtaining Pruffiate of Potafh free from Iron; the Unalterability of the Pruffic Acid at high Temperatures 5 and the true Nature of the Combinations of this Acid with different Bates. By Bucholz. = - - - - - - oe X. On a new Metal, found in crude Platina, By William Hyde Wollaf- ton, M.D. F.R.S. From the Philofophical Tranfagtions, 1804. 34 XI. Letter from Mr. Wm. Wilfon, exhibiting the Electricity of Metals, without the Help of any condenfing Inftrument. - - 42 XII. Analytical Experiments and Obfervations on Lac. By Charles Hatchett, ' Ef. Partly abridged, but chiefly extracted from the Philofophical Tranf- actions for 1804, by W.N. - - - 45 XIII. Galvanic Illuftrations and Remarks. By C. Wilkinfon, Efq. 56 XLV. On the Devitrification of Glafs, and the Phenomena which happened ' during’ its Cryftallization.- By Dartigues, - - - 58 FREBRUARY., oe CONTENTS. FEBRUARY, 1805. Engravings of the following Objects: 1. Outlines of pendulous Meafures of . Time. » By J. Whitley Bofwell, Efg. 2. Figure to illuftrate Mr. Gough’s Theory of the Augmentation of Sound by communicated Vibrations ; 3. Plan for Captain Mortlock’s Method of furveying Harbours and Coafts without In- ftruments, or by fuch as are extremely fimpie; 4. A new Pocket Inftrument for mechanical Drawing in Perfpective. I. Experiments and Remarks on the Augmentation of Sounds. In a Let- ter from Mr. John Gough. - - - = « 63 BI. Obfervations on the different Degrees of Fatility with which Maffes of the fame Material admit of Changes in their Temperature; with Applications of.the Faéts, to the Conftruétion of Pendulums, and Speculations upon ‘various new Forms of pendulous Regulators of Time. In a Letter from J. Whitley Bofwell, E{q. - - : - eae .70! TI. Analytical Experiments and Obfervations on Benzoin. By Mr. William Brandé. Communicated by the Author. - - - 82 IV. On the Devitrification of Glafs and the Phenomena which happen during its Cryftallization. By Dartigues. - * - - 89 Y. Letter. from a Correfpondent, relating to the apparent, Reflection of Cold and ». the Invention of the Telefcope, as noticed by Sir H. C. Englefield in Jaft Month’s Journal, - - - - - - 92 VI. Faéts tending to decide the Queftion, at what Point of Temperature Water ‘pofiefles the greateft Denfity. Ina Letter from Mr. John Dalton. 93 WII. Analytical Experiments and Obfervations on Lac. By Charles Hatchett, Efq. ®. R.S. From the Philofophical Tranfa@ions for 1804. - 35 VHI, A fimple and accurate Method of Surveying on Shore, with fuch inftru- ments only as. are in every one’s Poffeffion. By Captain J. Mortlock.— From the Author. - - - 10S IX. Notice of an Omitiion in Accum’s Chemiftry, of the direét Produétion of Nitric Acid. By W. pe Ss =. - - - bs! 105 X. On, Galvanifm. By Mr. Charles Sylvefer qo - 106 XI. Reply to the Animadverfions and Experiments of C. L. on the Subjeét of the Horizontal Moon. By Mr. Ezekiel Walker. - : 103 MH. Defcription of a fimple Inftrument for making correét Drawings from Na- ture. By, T. B.C, - - é es - - Ml) XIN. Obfervations on Bafalt, and on the Tranfition from the vitreous to the ftony Texture, which occurs in the gradual Refrigeration of melted Ba- ‘falt; with fome geological Remarks. ‘In a Letter from Gregory Watt, Eq. to. the Right Hon. Charles Greville. V.P.R. S$. From the Philofophical Tranfactions for 1804, p. 279. - - . - - 11g XIV. Account of the Method of bleaching Cotton, as practifed at Salzburgh ; and the Art of. giving a permanent Red to Cotton and Linens By M. C. Schoerbing. - - Saal ‘3 = : 4 126 %V. Report on an artificial Production of Camphor, announced by M. Kind. Read to the Society of Pharmacy by Boullay. - ud - 13% XVI. Letter from Jofeph Hudda:t, Efy. F. R. S. on th arent Enlargement of the Moon at low Altitudes. ge ; 2! " i me , abi oy 139 XVII. A-Memoir on Milk and the La@ic Acid. By Cit. B, Lagrange. 141 MARCH. COLIN TIE NTS, tik MARC.H, 1805. Epngtavitgs of the following Obje&ts: |. An improved Air Pump with hy Barrels and Piftons of Metal, Neos ‘Veathering. By Mr. Mendlefhon; 2. Plans and Sections of the fttine Infrument;. 3. ” Ficures to illuftrate a new Theory of the Speaking Trumpet. By Mr. Gough ; 4. Improved Apparatus of Woulfe; 5. Diagram of a Method of drawing a Line ina Circle, very nearly equal to the Side of a Square, having the fame Area. I. Hiftorical and Critical Obfervations relating chiefly to the Invention of the Telefcope. Ina Letter from E..O. - - - - 145 II, Conftru&tion of a Line in a Circle, nearly equal to the Side of a Square of the fame Superficies as that of the Circle itfelf. With Remarks on, Pen- “dulums and other Olyjeéts.. By Mr. J. Whitley Bofwell. 3 154 III. Some Remarks: upon the Experiments by which Mr. Ez. Walker has endeavoured to explain the apparent Enlargement of the Moon near the Horizon; with a Statement of fome Faéts upon which that Phenomenon. ‘feems chiefly to depend. In a Letter from C. H. - - 156 IV. A - aciagaue ae Theory of ul spears Teompet: By dehe a _ Efq. - - 160 V. Obfervations on ‘Batalt; and on the ‘Tranfition from the vitreous to the ftony Texture, which oécurs in the gradual Refrigeration of melted Ba- falt; with {ome geological Remarks. Ina Letter from Gregory Watt, Efg. ‘to the Right»Hon. Charles Greville, V. P..R. S$. From the Philofophical ‘Tranfa&tions for 1804. - - - - . 165 VI. Improved Confruction of Woulfe’s Apparatus. ByW.B. + 180 WII. Obfervations on the Change of fome of the proximate Principles of ‘Wegetables into Bitumen; with Analytical Experiments on a peculiar Sub- ftance which is found with the Bovey Coal. By C. Harchetty, Efg. F. R. 8. “From the Philofophical Tranfa@ions for 1804, - - 181 VHI. Account and ili adn ge an spina Air Eeep: By Mr. N. Mendelsfhon. - > 201, IX. Letter concerning Palladium, Bi Wm. Hyde Wollafton, Efq. M. D. (B. ROS. the Difcoverer of that Metallic Body. - - - 204 X. Short Remark on Mr. Walker's lait or ie aa bias Images. By Rs Legeyi ees - - - > 205. XI. A Communication on the Ufe of Green Vitriol, or Sulphate of Iron, as ~ ea, Manure; and on the Efficacy of paring and burning depending, partly, on Oxide of Iron. By George Pearfon, M.D. Honorary, Member of the Board of Agriculture, F, R.S. From a Communication made by him to the Board, and inferted in the fourth Volume of their Tranfa€tions. - 206 XII. Letter from Mr. Accum, ee an Error tated to exift in his Prac- teal Chemiftry. - - - - - 214. KUL. Proceites for obtaining a durable and fuperior Lake from Madder. By Sir H.C. Englefield, M.P. F.R.S.. - - - - 215 xIV. The Dutch Method. of curing ‘eaeahaes extra&ted and tranflated from the German of Krinitz’s Economical ‘Bntyclopadia (Occonomifche Encyclopadie) Article Haring, by J. Hinckley, Efq. F. S.A. ~| 223 7 amt APRIL, Ww CON TIEN Ts APRODL,, 1805. Engravings of the following Objects: 1. A Quarto Plate, exhibiting magnified = Reprefentations of the deitrustive parafitic Plant which caufes the Blight in — Corn, and its Situation and Growth in the Pores or Mouths of Wheat Straw; 2. Another Quarto Plate, fhewing, by highly magnified Sections and Views, the Structure of Wheat Straw, and the Plant itfelf as it vegetates in the cellular Texture beneath the Bark., Thefe two Plates are from Drawings of the fame fize, by M. Bauer, Botanical Painter to the King; 3. Mathematical Diagrams “of fome Properties-of the Triangle, by Mr. Gough; of the Circle, by! a’ Correfpondent ; and of an Application of Spectacle Glaffes, by Mr, Ezekiel Walker. I. A thort Account of the Caufe of the Difeafe in Corn, called by. Fahne, the Blight, the Mildew and the Ruft:. Reprinted, and the Plates copied, with Permiffion, from ‘a Memoir communicated by the Right Hon. Sir Joieph ! Banks, Bart. P?R §. &c. &e. &c. »With fome additiona! Notes. . P. 225 II. Theorems refpeéting the Properties, of the Sides’ of Triangles. interfested .by Right Lines drawn from the three Angles fo as to meet in one Point. ‘By Mr. John Gough. - aPo]G 8 - - 4 2340 HI. A Communication on the Use of Green Vitrial, or Sulphate of Iron, as a Manure; and on the Efficacy: of :paring and burning depending, part- ly, on Oxide of Iron. By George. Pearfon, M.D. Honorary Member of the Board of Agriculture, F. R. 5. .#rom a Communication made by him to the Beard, and inferted in-the 4th Vol. of their Tr anfactions. 239 an On Speétacles. In a Letten from Mr. Ezekiel Walker. - 243 . Remarks on ‘certain Paffages in Dr. Thomfon’s Chemiftry, together with Vane Experiments on Sandarach and Maitic. In a Letter from Mr. R.’ Matthews. - - - . : : - 245 VI. The Dutch Method of curing Herrings, extraéted and tranflated from the German of Krinitz’s Economical Ency ig Se er: Article Haring, by J. Hinckley, Efg.:.F.S. A. ’ VII. The Denfity a ogy in its iid State afertained oF Mr. she Biddle. - = 9531 VIII. Obfervations on Mr. Bofwell’s Geometrical PiopeTRD “ An Old Correfpondeat. - - - - - 255 IX. A Memoir on Milk and the Laétic Acid. By Cit. Bouillon Lagrange. 257 X. An Analyfis of the Magnetical Pyrites ; with Remarks on fome of the other’ Sulphurets of Tron. By “Charles Hatchett, ‘Efq. $ R.S. From the Phil. Tranf, for 1804, - - - are a5 Xf. Anfwer toa Letter of C. L. with other eis on the Images formed by convex Lenfes. In a Letter from Mr. Ezekiel Walker. - 276 MI, Account of an Aecrottatic Voyage, made by M. Gay- -Luffac on the 29th _Fru&idor, in the Year, 12. Read to the National [nftitute on the 9th Ven- _demiaire, in the Year 13. - - - - - 278 XIII. Experiments and Obfervations on the Motion of the Sap in Trees. Ina. Letter from Thomas Andrew Knight, Efq. to the Right Hon. Sir Jofeph; - Banks, Bart. K. 5B. P. R. S. From the Phil. Tranf. for 1804. ' 289 XIV. Extra& of a Memoir of Mr. Erman, entitled, Obfervations and Doubts concerning Atmofpheric Electricity, - - - 294 Scientific News. - - - - - i - 301 Extraét of a Letter from Mr. J. Dalton, Lecturer at the Royal Inftitution, 303 To Correfpondents. - - - - - * 304 A. ey OUR Nv AVL - OF NATURAL PHILOSOPHY, CHEMISTRY, awp: . THE OA RS: — J ANWAR Y, 1805. ARTICTE' I. Concerning the original Inventors of certain philofophical Dif: coveries : the RefleGtion of Cold; Comprefion of Water in a metallic Vefel; the Telejcope; and a perfpectite Inftrument for- merly dejcribed. Ina Letter from Sir H. C. ENGLEFIELD, Bart... Po. FoR. 8. &c. &e. . To Mr. NICHOLSON. eis Atrsoucr abftraéiedly fpeaking, it is of no importarice Univerfal fenti-| to {cience who firft made the moft valuable experiments, or to SM rales what individuals the world is indebted for the moft ufeful dif- coveries ; yet as the fenfe-of mankind has univerfally in this, as in feveral other things, been in direét oppofition to frigid reafoning, and every one has been defirous to vindicate the fame of eminent men, by afcertaining to them the honour due to their labour or genius, I truft that the following obferva- tions will not be deemed unworthy a place in your valuable Journal. ‘1. The experiment of the reflexion of cold has been, as far Refleétion of as I know, both in converfation and in printed books, uni- baer be formly afcribed to Mr. Pictet of Geneva, Now in the collec- ; VoL, X.—January, 1805. B tion | 2 . SIR H. C. ENGLEFIELD It was before tion of experiments publithed by the Academy Del Cimento, made by the : : : ; ‘ Acad. del Ci- Of Florence, in the year 1666, the identical experiment ts mento. defcribed in the following words : *¢ Ninth Experiment. Narrative. «‘ We were defirous to try whether a concave fpeculum, expofed to a mafs of ice weighing 500 pounds, would reflect any fenfible degree of cold on a very delicate thermometer of 400 degrees, placed in it focus. The refult was, that the thermometer inftantly funk: but a doubt remained whether the thermometer was acted on more by the direét cold of the ice, or that reflected by the {peculum. ‘This doubt was re- moved by covering the fpeculum: and certain it is (what- foever might be the caufe) that the fpirit inftantly began to rife again. Yet ftill we will-not prefume pofitively to affirm, that this rife might not have been owing to fome other caufe than the taking off the refleGlion from the fpeculum, all the precautions not having been taken which might be confidered neceflary to fecure abfolute affent to the experiment.” —Saggz di Naturali Efperienze, page 176. I do not mean to affert that Mr. Pi€tet had feen this moft excellent book, or that he borrowed from it without acknow- ledging his obligation ; but the honour of having firft made the experiment is certainly due to the Florentine philofophers, Excellency of Jt may not be foreign from the fubjeét here to obferve, that their publica- : Side ; : Son, : the ‘* Saggi,” for perfpicuity, brevity, and that diffident cau- tion fo effential to the inveftigation of truth, is a model of philofophical writing, not perhaps excelled by any book writ- ten fince that time, and more admirable when we confider the diffule and obfcure ftile fo much in fafhion in the works of the learned at that period. The Acad. del 2, Scarcely any treatife on natural philofophy has failed to eae quote an experiment made by thé academicians Del Cimento, bwee compreffed on the incompreffibility of water inclofed in a globe of gold, water in a globe and {ubmitted tothe preflure,of a fcrew'prefs. Mr. Canton, ia in his experiments on the fame fubje&, publifhed in the 52d vol. of the Phil. Tranf. fo fpeaks of it. You will probably be furprifed when I affert, that the academicians did not try the The globe was €Xperiment with a gold globe, but one of filver; and that peli cog rer they give a reafon for ufing filver in preference to gold, meting, namely, that the ductility of gold was fo great that it would extend ON FPHILOS. DISCOVERIES. $ extend its dimenfions by preflure, and fo defeat the intention of the experiment. Neither was tie globe compreffed by a machine, but merely by hammering. But the honour of this experiment is not due to the Floren-Lord Bacon firft tine philofophers, but to our own illuftrious countryman ST betel Bacon, who, in the Novum Organum, Book II. Se&. 45, gives the very fame experiment on water enclofed in a large and firong globe of lead, which being firft compretfed by the hammer and then by a {crew-prefs, the water exuded through the pores of the metal, and ftood in a dew on its furface. The inaccuracy with which this experiment has been re- lated, though in this cafe of no great importance, may how- ever be an ufeful leffon, and induce thofe who wifh to attain to truth, to truft as little as poffible to information at fecond- hand, but to recur to the original authority whenever it is prac- ticable to do fo. Before I conclude, permit me to mention a curious circum- Thetelefcope was ftance relative to the wra of the invention of the telefcope, Meds Sevier Almoft all books place it in the year 1609, and the firft dif- two years before coveries of Galileo were made in 1610; yet Kepler, in his Galileo. account of the comet which appeared in September, 1607, (See Kepler de Cometis, page 25) exprefsly ftates, that though, to the naked eye, it was only equal to certain fixed ftars near it, yet, when viewed with telefcopes (perfpicillis), it ap- peared larger than thofe flars. _ Although the intercourfe between the different nations of Remarks on the Europe was at that time much lefs than it now is, it is very Riek Bah difficult to fuppofe that Galileo thould not, in upwards of two years, have heard, not only of the invention, but its applica- tion to celeftial obfervations by a man fo eminent in fcience as Kepler: and it is fcarcely lefs extraordinary that Kepler himfelf fhould not, in that fpace of time, have foreftalled Ga- lileo in fome of thofe difcoveries which rendered his name fo illuftrious ; for however imperfe@t Kepler’s telefcope might be, it is hardly poffible that it could have failed to thew him the fatellites of Jupiter, which are vifible to the commoneft opera glafs. | / Iam, Su, Your obedient fervant, . H. C. ENGLEFIELD. Tilney Street, Nov. 30, 1804. ’ B2 Pa Ss 4: EGYPTIAN SCULPTURE. Ramfden was P. S. 1 beg leave to add, that the machine for drawing in = Sea of perfpective, defcribed in your Journal for O&ober, page 122, fhedtive inftru- was (I am almoft abfolutely certain) the invention of the late mont referred to moft eminent Mr. Ramfden, and was made by him full 25 years fince, for the Right Honourable Charles Greville. iH. Account of an ancient Egyptian Sculpture with Hieroglyphics, fippofed to relate to Aftronomy. In a Letter fron Mr, H. Sternnaver. With an Engraving. - To Mr. NICHOLSON. SIR, - Fulneck, O&. 25, 1804. Porphyry fculp- Peruars the liberty that I take in fubmitting the annexed ene draught of an Egyptian antiquity, may be an intrufion upon and bearing hie- the plan of your valuable Journal, The Egyptian hieroglyphic roglyphits. infcriptions are involved in fuch impenetrable darknefs, that every trifle contributed to their elucidation cannot but be ac- ceptable, indeed equally acceptable to the antiquarian, the hiftorian, and the aftronomer; fince the greater part have pro- bably a reference to that fcience. Stones fculptured in the thape of a fcarabseus are, I believe, (for I make no preten- fions to the title of an antiquarian) well known; there are a few in the Britith Mufeum; but I never yet faw either a fac-. fimile of the infcription, or any allempt at an explanation of the fame. The drawings inclofed are taken from a ftone brought by the Swedifh conful at Aleppo to Stockholm, and there .prefented by him to a gentleman, who has favoured me with the loan and permiffion to make drawings or impreflions of it as pleafure. The upper part, of the fize of the fketch, obvioufly reprefents a fcarabzeus; probably the S. Sacer, Lin, & Fabr. though the indeytures on the head are but flightly marked, and a flight damage between the thorax and elytra render it impoflible to difcover whether a fcutellum be indi- cated or not, ‘It was perhaps the only beetle they reprefented in fculpture, and the accuracy of a modern nomenclator is confequently unneceffary to determine it. If I recolle& right, this EGYPTIAN SCULPTURE. 5 this beetle was made ufe of as a fymbol of the annual rotation Porphyry fculp- of the fun. -The under fide is flat, or flightly convex, perhaps pegs ai from wear, and bears eight lines of hieroglyphics, probably and bearing hic- referring to the change of the feafons. The drawing, made toslyphice. with the greateft accuracy from an impreffion in fealing-wax, is confequently inverted.* Should you, fir, or any of your friends, wifh for one to prove the exaétnefs of the draught, it is very much at your fervice. The ftoneitfelf is apparently afpecies of porphyry, the /erpentino verde antico, of a green mafs, with very dark green field-[par, and pale green indif- tinét ftripes. The plainnefs of the infcription, and the fame fymbol occurring feveral times upon it, led me to fufpeét, that it would be no very difficult tafk, for fuch as are verfant in - antiquities of the kind, to difcover fomewhat of its purport; _ and being con{cious of its value, I was unwilling to let it lie by me, without offering it to the attention of fuch as are more deeply interefted in it. Your wifh to promote the arts and fciences, which fo obvioufly pervades your efteemed Repofitory, makes me hope that you will excufe mine, in cafe the fubje& fhould not be admiflible into your Publi- cation. | | Tremain, Sir, Your obedient humble fervant, H., STEINHAUER. P. S. Is the carbonate of barytes a frequent Britifh mineral, Native carbonate : except at Chorly? If not, it may perhaps be interefting ee ee formation, that it is found in very large quantities near Murton in Cumberland, and fome other places of the vicinity. The mative oxide of zinc, fearcely inferior to the flowers of zinc -of the fhops, I do not recolleét to have feen mentioned. ‘It is found in one part of the Weft Riding of Yorkfhire, in cons fiderable quantities. * The engraver having followed the drawing upon the copper, our print is not inverted.—N, / Extrad Hiftory of the difcovery of Cadet’s fuming liquor, &c. Method of ob- taining it. Diftillation of CADET’S FUMING LIQUOR, iit. Exira& of a Memvir on the fuming Liquor of Capert. By Cit, THENARD.* Caper difcovered this liquor near half a century ago, in making inveftigations onarfenic. The name of its author was given to it then, which it has retained ever fince, becaufe its intimate nature and conftituent principles were unknown. The thick fmoke which this fingular produét {preads through the air, its fpecific gravity, greater than that of water, its oily ftate, its great volatility, its powerful odour, its fponta; neous inflammation in the air, obferved by Cadet and the chemifts of Dijon; in fine, all its properties, each more ex- traordinary than the other, induced Cit. Thenard to fubje@ it to analyfis. , He began by procuring feveral ounces of this liquor, by diftilling, according to Cadet’s procefs, equal parts of acetite acetite of potafh of potafh and arfenious acid, the produce of which he received and arfenious acid. Refidue. The liquid pro- dué confilts of two diftin&t flu- ids. in glafs globes, cooled with a mixture of ice and marine falt, A liquor, very little coloured, and {melling ftrongly of garlic, foon paffed into the receivers; at the fame time much gas was difengaged, which fpread the fame odour, and the receivers were filled with vapours, fo heavy that they feemed to run. like oil. When the operation was terminated, he unluted the apparatus, and broke the retort. The bottom of it was covered with a white, acrid, and alkaline fubftance of pot~ afh, arifing from the acetite employed; and the neck was lined with cryftals of arfenic, owing to the reduétion of the arfenious acid. The gafes, the quantity of which was very great, contained arfeniated hidrogen, in addition to the car- -bonated hidrogen and carbonic acid, given by all vegetable matters which are decompofed by fire. The liquid produ& was compofed of two very diftin@ flrata, holding metallic ar- fenic in folution, which was not long before it was depofited in flakes ; the upper one was of a brownifh-yellow and aque- ous, the lower one was lefs coloured, and of an oily appear- ance. He feparated them, by pouring them into a tube drawn to a point by the lamp, which allowed him to receive them * From Bulletin des Sciences, Tom, III. p. 202. in CADET’S FUMING LIQUOR. 7 in different veffels, The heavieft, as being the moft ufeful to Examination of be known, was firft examined. At the commencement he ‘ heavietts was affected by the thick vapours which it difperfes through the air, and by its extremely penetrating and horribly fetid odour. Its aGtion on the animal economy is fo powerful, that pio at le he found it impoffible to devote more than one hour in a day uu pel to his enquiries, and he was more than once tempted to aban- don them. He was in the fame ftate as if he had taken a ftrong medicine, and experienced ftupefying effects; againft which he employed fulphurated hidrogen diffolved in water, with fuccefs. ; As he had but a fmall quantity of the liquor at his difpofal, Order of the in- and it was of importance that his attempts fhould not be fruit. "840" lefs, he regulated the order of his enquiries in this manner ; He firft determined the caufe of the odour which it fpreads through the air; then he fought for that of the thick vapours which it produces, and afterwards that of its {pontaneous in- flammation; and he made ufe of the determination of thefe three points to difcover the fourth, and moft important, the conftituent principles of the fubftance. The odour could only proceed from the fubftance itfelf, Caufe of the or elfe from an elaftic fluid which it might hold. in folution, Syne and which the author fuppofed to be arfeniated hidrogen. He therefore diftilled, with great care, a certain quantity of the Jiquor in a fmall glafs retort, to which were adapted a re- ceiver and a tube for collecting the gafes. He obtained no- The liquor was thing but the air of the veffels; the liquor was entirely vola- pers cd tilized, and paffed into the receiver without having undergone any alteration, except that\ its colour was not quite fo deep. Hence the odour of the arfenical liquor is owing to its pro- perty of being volatilized, and, probably, diffolved in the air. The caufe of its vapours could only be owing to an abe Its vapour is oc- forption of oxigen, or to an ablorption of the water diffolved Setanta eal in the air, or to both thefe effeéts at the fame time. The air igen hi ayn of a flafk, into which Cit. Thenard had poured a few drops, __ immediately loft its tranfparency, and, in a fhort time, be- came incapable of fupporting the combuftion of a taper. A veffel of the fame fize, filled with carbonic acid, offered the fame phenomena, but in a lefs diftinét manner. ‘Fo guard againft the contaét of the air, he had been careful to fufpend a very thin tube, containing the liquor, to the cork of the flafk, fo 8 } CADET’S FUMING LIQUOR. 9 fo that he could eafily break it againft the fides of the vefiel. The vapours were not perceptible when he ufed carbonic acid perfe@tly dried; whence he concluded, that tlhe vapours of the arfenical liquor are owing to an abforption of the oxigen and the water contained in the air jointly, but that the firft of thefe cauies feems to be more powerful than-the fecond. Its property of | From this it fhould feem that the arfenical liquor is poffeffed inflaming {P0n- of the property of inflaming alone, It doesnot however take taneoufly is ow- : : : che ing to metallic fire at the approach ef a body in combuftion,, when it is very arfenic. pure; and it is obferved, that, in all the fpontaneous inflam-_ mations which it experiences, the combuftion always begins at the black fpecks which difturb its tranfparency, and are only metallic arfenic very much divided. Tt muft there- It now remained to determine the nature of the arfenical re contain are y- opus 8 : : AN liquor, Its odour, which refembles arfeniated hidrogen gas, ? indicated that it muft contain arfenic, and that this metal muft have great influence on the phenomena which it offers: Tis combuftibility, its confiflence, and its appearance, ind?- an oily matter, cated an oily matter; and, alihough it did not change the tinéture of turnfole, and no re-agent demonflrated immedi- and acetous acid; ately the exiftence of acetous acid, this body muft neverthe- but this was not lefs be expeéted in it. To fucceed in infulating thefe differ- indicated by al-. ent fubftances, the author tried the alkalies; but experience ae foon convinced him that he muit have recourfe to other means. Oxigenated mu- He employed the oxigenated muriatic acid with much greater riatic prigge: fuccefs. Some drops of the liquor, poured into this gas, were compofed it. E 3 E ; et inflantly inflamed, and their decompofition was complete. They were then precipitated in white flecks by lime-water, Formed a foli- and in yellow ones by tulphurated hidrogen; while, on being ated falt with faturated with potafh and evaporated, they formed a foliated tay falt, flrongly attraéting the humidity of the air, acrid, tharp, decompofable by fulphuric acid, and difengaging a ftrong odour of vinegar. The quantity of arfenic and of acetous acid obtained, being far from correfponding with the quantity of liquor which had been ufed, there muft therefore have been Its folution in another body in it which it was requifite to infulate, and this sated by Luly was sioi-aieep abi: by treating anew portion of the liquor with rated hidrogen, @ Quantity of water fufficient to diffolve it; then on decom- yielded fulphur, pofing it by fulphurated hidrogen, it yielded a precipitate, “art ai eg flightly yellow, very much divided, formed principally of containing ace : tous acid. arfenic and fulphur, which was a confiderable time in fepa- rating CADET’Ss FUMING LIQUOR. cs) tating from an oil, which was afterwards feen fwimming on the furface of the liquor. This contained a great deal of acetous acid. Its decompofition may be further facilitated by expofing it to the air; then it emits thick vapours, it is eryftallized, and becomes flightly humid. It is rendered tur- bid by lime-water, and yields a yellow precipitate with ful- phurated hidrogen. ~ From thefe different experiments it follows, that this liquor Compofition of is compofed of oil, acetous acid, and arfenic, nearly in a me- Ri li- tallic ftate; and that it muft be confidered as a fpecies of : foap, with a bafe of acid and arfenic, or as a‘fort of olco- arfenical acetite. __This analyfis was very ufeful in that of the upper liquor, The upper fluid In fat, notwithftanding the difference which feems to exifl ae cae: tos between them, fince the latter refembles water, can combine having a a with it in all proporticns, forms only a flight cloud in the at- cna mofphere, has much lefs odour, and (ddes not inflame in any water, cafe, it is eafy to prove that it only differs from the firft by its ~ greater proportion of acetous acid, and by the water which it contains; for it'reddens the tinéture of turnfole ftrongly, effer- velces with the carbonates, gives rife to acetites, and is flightly precipitated of a yellow colour by fulpharated hidrogen, which feparates a little oil from it. A very fmall quantity of oxigen- ated muriatic acid {peedily deftroys the odour, and it is then precipitated white by jime-water, and of a deep yellow by the hidro-fulphurets. [Expofure to the air produces in it, by time, the fame changes.as take place immediately with ox- igenated muriatic acid, Finally, a liquor, exaétly fimilar, is formed by diffolving a few drops of the lower liquor in very _ weak vinegar, and thus fynthefis confirms the refults of - analyfis. We can now effabiifh a theory, clear of all hypothefis, on Theory of the the phenomena offered by the diftillation of acetite of potafh procets. and arfenious acid; we fee that one part of the arfenious acid ds entirely reduced; that another is only brought near the me- fallic ftate; that the acetite of potafh is totally decompoled ; + that almoft all the acetous acid is alfo decompcfed ; and, that Component parts from thefe different decompofitions refult water, carbonated of the fuming hidrogen, arfeniated hidrogen, carbonic acid, a peculiar oil, Beg oxide of arfenic, arfenic, and potaih; that ihe poteth forms ‘the white refidue found in the veflels in which the diffillation i was iz 10 ACCOUNT OF CERIUM. was performed ; that the arfenic is fublimed, and adheres to the neck of the retort; that the three different fpecies of gas are mixed, and may be colleéted in flafks; finally, that the water, the oil, the acetous acid, and the oxide of arfenic, are condenfed in the receiver; that thefe three laft bodies, by combining in certain proportions, form a very volatile com- pound, heavier than water, and fparingly foluble in it; and that it is for this reafon that it feparates into two very diftinét ftrata; the lower of which muft be confidered as an oleo-arfe- nical acetite, and the other as a portion of the firft diffolved in water, which folution is promoted by an excefs of acetous acid. iV: Account of Cerium, a new Metal found in a mineral Subfiance from Baftnas, in Sweden. By W. D’Hesincer and J. B, BeERGELIUS. (Concluded from Page 300, Vol. IX.) With Succinic Acid, Succinate of (¢P.) At firft, fuccinic acid renders the faturated folutions cerium. of cerium turbid, but afterwards they become clear. Thus, a few drops of fuccinate of ammonia, poured into a faturated nitric or muriatic folution of this metal, occafion a precipitate, which foon difappears. On pouring in a greater quantity of this re-agent, the fuccinate of cerium is immediately depofited. This combination is white ; it is not wholly infoluble in water, fince the folution from which it was feparated ftill retains a little, as is manifefted by evaporation, or by alkalies. The falt obtained by digefting free fuccinic acid with the oxide, comports ilfelf in the fame manner. The acid diffolves it readily. Expofed to the fire, it burns with a blue flame. Since the acetate of cerium is not precipitated by the fucci- nate of ammonia, this is a certain means of obtaining the ce- rium freed from iron. . With Gallic Acid. Gallate of ceri- (2.) If cryftallized gallic acid is put into a faturated folution um. of muriate of ferium, a {mall quantity of a white precipitate ‘ is ACCOUNT OF CERIUM. 1? is formed. The alkalies augment it, and give it a clear cho- colate colour, Ifa larger quantity of alkali is gradually added, the quantity of the precipitate, and the intenfity of its colour are increafed ; in proportion as this addition is made, the pre- cipitate becomes of a reddifh brown, and at length, by expo- {ure to the light, gives a turbid, deep green folution. With Prufic Acid, (R.) The faturated folutions of cerium are precipitated Pruffiate of ce- white by the pruffiates. The voluminous precipitate has much refemblance to filver precipitated by muriate of foda, Anex- cefs of acid readily diffolves this precipitate, Oxide of Cerium with Sulphurated Hidrogen, (S.) At the commencement, the faturated folutions of ce- Hydro-fulphuret rium are precipitated of a brownifh colour by hidro-fulphuret® °™™ of ammonia; butif more of this re-agent is added, the precipi- tate is of a deep green. The muriale of cerium alone takes acleep green colour, but if an alkali is added to it, an hidrow fulphurated combination of meriate of cerium, at a minimum of exidation, is formed, which is rapidly precipitated of a bright green colour, The hidro-fulphurated cerium, well dried, has a deep green colour, almoft black. It is eafily deftroyed by heat; put into a crucible, moderately hot, it burns with a yellowifh, phofpho- ric flame, only vifible in the dark, Sulphurated Oxide of Cerium. (T.) The fulphuret of ammonia gives a fading brown pre- Sulphurated ox- cipitate with the folutions of cerium, This fulphuret, added ide of cerium. in excefs, gives a precipitate-of a grafs green, which becomes bright green by deficcation ;: it burns with a blue flame and the ' ‘pure oxide remains. The muriate of cerium at a minimum is precipitated white by fulphuret of ammonia. Oxide of Cerium with Phofphorus. (U.) A piece of pure phofphorus was put into a folution Phofphate of ce- _ of muriate of cerium contained in a clofed veffel, and kept for ™m™: feveral days ona ftove. The bottom and fides of the veffel were covered with a white precipitate, and the piece of phof- phorus 12 Aétion of the alkalies. jron or zinc do not precipitate the folutions of cerium. A&tion of gal- vanifm. Oxigen gas. GASES ABSORBED BY CHARCOAL. phorus was covered with a hard brown croft, from which the phofphorus was feparated by heating it in warm water, This cruft was tenacious, and fhining in the dark. Heated, it took fire like phofphorus, and left a refidue of a {mall quantity of oxide, which, on being melted: with borax, exhibited the charaéters defcribed above, except that the globule retained its clear green colour, after being cooled. It appears pro- bable that thefe phenomena ‘arofe from the phoiphorus con- taining cerium. But the phofphorus, kept for a month in the fame folution, flowly depofited a white powder; whence it is uncertain whether the formation of the cruft, mentioned above, was owing to the cerium. The acid was always in excels in the folution, and the white powder had all the ap- pearance of pholphate of cerium. With the Alkalies. (V.) The pure alkalies do not diffolve cerium, even by fufion, By this means it is eafily deprived of manganefe. Pure ammonia digefted with the oxide, does not diffolve .it, but renders it yellowith, The carbonated alkalies diflolve the oxide of cerium in {mall quantity. The folution is yellow, and is precipitated by the acids, They alfo diffolve it by fufion in covered veffels. In the open fire, it oxides too much to enter into folution. The folutions of cerium are not precipitated by iron or zinc. ; The eleétric pile of Volta only decompofes the falls, and the yellow oxide adheres to the conductor. V. New Experiments on Abforption by Charcoal, made by Means of anew Machine. By C. L. Morozzo. (Concluded from P. 264 Vol. IX.) On Oxigen Gas. 25th, I NEXT proceeded to the examination of the abforp- tion by charcoal in oxigen gas. I therefore extracted fome oxigen gas from red precipitate to be employed in my different experiments. Of this gas, trie ‘ GASES ABSORBED’ BY CHARCOAL. 13 tried with charcoal in my machine, eight inches and fix lines Oxigen gas. were abforbed: this great abforption furprized me ; for in my firft experiments, in 1783, made in clofed tubes. I had had but a very {mall one: I therefore found no difficulty in attri- buting it to my matrafs' having been melted towards the clofe of the operation, which made me fufpe@ that my gas had been fpoiled by the nitrous acid; and I repeated the experi- ment with great care. 26th. I then took oxigen gas which had been obtained from red precipitate wilh great attention, and had been prepared in the laboratory of DoGtor Bonvoifin; what was my aftonifh- ment at obferving that, in thirty-fGx hours, the abforption amounted to twelve inches and eight Imes, and that it conti- nued for feveral days; in forty-eight hours it was fourteen inches fix lines; in four days, &fteen inches two lines; in five days, fixteen inches four lines; and, finally, in three days more, the gas was entirely abforbed.. 27th, This experiment was too interefiing to omit’ repeat- ing it with the greateft pofible precifion, I therefore took fome of the fame oxigen gas, and the abi forption was twelve inches three lines in sili firft four hours ; in forty-eight hours, it was thirteen inches fix lines; in three days, fourteen inches five lines; at the end of the fourth day, il was fifteen inches three lines? of the fifth, fixteen inches; -of the fixth, fixteen inches feven lines; of the feventh, feven- teen inches two lines; finally, on ate eighth day (he gas was entirely abforbed. > 28th. I repeated the fame experiment on oxigen gas ‘ob- tained from water expofed to the fun, in which I had put three ounces of charcoal-powder*; in this gas, which was very pure, the abforptions took place in the fame manner. 29th. Thefe faéts will furprife thofe who, having made their experiments on oxigen gas in tubes clofed hermetically, and by pafling the charcoal through the mercury, obtained only very {mall abforptions, which never exceeded three inches * In the twelfth volume of the Italian Society, I have inferted a memoir on the property which charcoal mixed with water has of de- veloping one-third more of oxigen gas, of a fuperior quality to that obtained from pure water: In this memoir [ prove, that a part of this oxigen gas is produced by the charcoal, which communicates the principle of fire to the air contained in the water, three 14 Oxigen gas. GASES ABSORBED BY CHARCOAL, three lines in tubes of twelve inches in height. I am cer- tainly not miftaken; and MM. Rouppe and Van-Norder, who have repeated my experiments in their apparatufes, have. obtained the fame refults, and have found, as I did,.that, next to hidrogen, oxigen gas is that which is leaft abforbed by charcoal.* 30th. I muft not pafs over a fingular experiment, the ex- planation of which will alfo be very difficult. T examined the abforption which a piece of charcoal, that had remained feven hours in the bright light of the fun, had effeGied in the fame oxigen gas; it was only between feven and eight lines, while a fimilar piece, which had been only five hours in the folar light, produced an abforption of ten inches three lines in carbonic acid gas. It muft be obferved, that a piece of charcoal expofed to the light of the fun and placed in oxigen gas, produced only an abforption of feven or eight lines, juft like the abforption of a piece which had been expofed to the fun’s light, and placed in hidrogen gas, which gave only an abforption of fix lines: and, in this, thefe refults are perfe€tly conformable to my experiments, made in the year 1783. 31t. This difference of the refults is therefore only owing to the method either of pafling the charcoal under the mercury, or of Jeaving it in the machine. It appears that, by pafling it through the mercury, the charcoal lofes much of its attrac- tive power, which it retains in the machine. Let us endeavour to find whether thefe differences can be aceounted for. 32d. It might be fuppofed that the red-hot charcoal in- flames the oxigen gas; but fince I do not open the key until fome time after the charcoal has been inferted, it does not appear to me to be likely that the gas can be inflamed : befides, if this were the cafe, the abforption would be made at once, and it would not require eight days to be complete, 33d. It might be fuppofed that, in this cafe, the charcoal fupplied hidregen gas, which, mixing with the oxigen gas and producing. water, would caufe the abforption: but during the whole experiment there was not the f{malleft drop of water perceived in the tube. * Ann. de Chimie. - 34th, GASES ABSORBED BY CHARCOAL, 15 34th. There might be reafon to believe that the charcoal, by inflaming the oxigen gas, might convert it into carbonic acid gas, which is the moft abforbed of all the gafes; but to fatisfy myfelf of this, 1 produced an abforption of oxigen gas by a, piece of charcoal, as in the former experiments: in twenty-three hours it amounted to twelve inches, then with a fyringe of cryftal I paffed fome lime-water through the mer- cury into the remaining gas, and it did not become turbid, which proves that carbonic acid was not formed ; and, having turned up the tube, the refidual gas extinguifhed a taper: I believe it to have been azote. 35th. I was of opinion that incandefcent charcoal would abforb more than another piece which had been fuffered to cool till it no longer appeared red. Experiment fhews 2 greater abforption in the firft for twenty-four hours; but, leaving the apparatus undifturbed, in two days the abforption became equal. I operated upon atmofpheric air. 36th. I muft acknowledge my inability to give an expla- nation of thefe fingular experiments, as I have already de- clared above: were I to hazard any conjectures, they would probably be overturned by new theories, which do not {pare even the labours of the greateft chemifts in France. . $7th. I fhall therefore continue my operations as I pro- pofed, and new experiments will, at leaft, fupply the want of fyilems. On, the Difference in the Charcoals made ufe of. 38th. Having afcertained the abforptions effeéted by’ the Differencein the charcoal of beech wood in atmofpheric air and in the different (rarcoals i gafes, I proceeded to examine the variations which the char- : coals of different woods would produce in them. | -$9th. I therefore took two pieces of charcoal, the one of beech, the other of the branches of fallow deprived of bark: Charcoal of f2!- I introduced them both in an incandefcent ftate, and exa- ows mined the difference of their abforption in the fame atmo- {pheric air. That of beech gave an abforption of feven inches and eight lines in fix hours. That of fallow gave only an abforption of four inches and three lines, and there was no further abforption after fix hours, Thefe 16 GASES ABSORBED BY CHARCOAL, Thefe experiments correfpond perfeétly with thofe which T have publifhed in my third memoir, _ I thall difpenfe with the relation of feveral other experiments which I have made on™ different woods, fuch as hazle, vine-twigs, &c. all of which , gave lefs ablorptions, of box ; I afterwards tried the charcoal of box wood, although it is a very compaét wood; but fince Kirwan found that this wood contains much more faline matter than any other wood, it was de(irable to fubmit it to experiment: its abforption, how- ever, was confiderable, and equal to that produced by beech- wood. The greater or lefs quantity of faline matter in the wood of which the charcoal is made, therefore, does not con- tribute to the variations in the abforption. of corks 40th. I afterwards examined the charcoal of cork, which interefted me greatly, becaufe Cit. Odier, from the experi- ments of Dr. Beddoes, has propofed it as a medicine: I was defirous of examining whether it contained more of the prin- ciple of fire than the others. I therefore charred cork ; but it is fo light, that, after the charring, a piece of equal bulk with that of the beech which I had ufed, weighed only three grains: to bring the circumftances to an equality, it was there- fore neceflary to make the experiment with a piece of beech charcoal which weighed three grains *: it was in atmofpheric air it was tried. The following are the refults : Three grains of beech charcoal produced an abforption ef one inch and nine lines. ; The charcoal from cork abforbed only nine lines, The charcoalof 41{. According to my principlest+, the charcoal of cork cone contains muft contain the matter of fire more than any other charcoal; principle of fire thus when it is neceflary to give it as a medicine, either in- than any other wardly or outwardly, it fhould be preferred to all the others ; perce and Iam of opinion that it is by oxidating, and not by difox- idating, that it produces its aftonifhing effeéts. Befides, we have inflances of fubftances which a@ in this manner. The osigenated muriatic acid, far from abftraéting the oxigen, is. * The pieces.of beech charcoal which I ufe, and which weigh thirty-fix grains, are of the length of ten lines, and about five in diameter. ‘; See my third memoir on charcoal, fuppofed GASES ABSORBED BY CHARCOAL. 17 fuppofed, on the contrary, to adda confiderable quantity of it to fetid ulcérs, and carries off their fetidity as well as charcoal.* f Water may fometimes be ufed in the Inflrument inftead of Mercury. 42d, Although, in the courfe of thefe experiments, I have Coloured water conftantly employed mercury, in fome experiments a coloured ag et ik me water may be ufed with advantage, fince it is better feen’in mercury in the the tube; but this cannot be ufed when the gafes which are ™hine- abforbed by water are examined, nor with the carbonic acid and the other acid gafes which are much abforbed : then it is neceflary to change the tube, and to fubflitute one which, inftead of eighteen inches, is at, leaft thirty-fix in height; _without which it will be entirely filled. 43d. It was on atmofpheric air taken in my room with the windows open, that I experimented with coloured water. The charcoal produced an abforption of ten inches and a half, It has been feen, that, with the mercurial apparatus, F had had an abforption of eight inches fome lines. The preffure of the atmofphere im the water therefore aug- The preffure of mented the abforption, which ufually takes place with the the atmofphere mercury, by two inches and a half; that is to fay, one-fourth eg ihe of the height. 44th..I fhould obferve, that very frequently the fmall dif ferences of one or two lines obferved in the abforptions of the fame quality of air or of gas, are owing to the variations of the atmofphere, which I afcertained by comparing the height of the barometer during the experiment. The Pieces of Charcoal ufed in thefe Experiments, acquire Weight. 45th, After the experiments, all the pieces of charcoal The charcoal employed had acquired greater weight: this augmentation or ug was from half a grain to two grains, and appears to be de- ments; . pendent on the greater abforption. 46th. I took four pieces of charcoal which had been ufed in the experiments made with atmofpheric air, which, among them, had acquired four grains in weight: I pafled them * See the notes of M. Odier to Beddoes’s memoir. Bibl. Brit. Vols VI, p..359. Vor. X.—January, 1805, Cc under 18 GASES ABSORBED BY CHARCOAL. under water, in a tube of one inch in diameter and fix inches and yields a por-high, which was alfo filled with water. A part of the air thai , Which they contained was immediately developed, but I only is acompound obtained about two inches, (they had, however, abforbed * azote and cat-among them nearly thirty-two inches). The reftored air was onic acid gafes 5 : ‘ found to be compofed of carbonic acid gas and azote gas. In this operation a part of the air is fixed in the charcoal to be’ embodied with it, and cannot be again diflodged but by em- ploying fire. I believe thefe combinations frequently occur in nature, and the great Newton fufpeéted it. 47th, I dried the pieces of charcoal which had been wetted by which itre- in the preceding experiment, in the air: I afterwards exa- eae mined them, by again heating them to rednefs in the fire, and placing them in the machine; they abforbed the fame quantity of air as before. No water pro- 48th. I direéted all my attention, as well after as: dering aoe ee courfe of the experiments on atmofpheric air, to fee if gas under exa~ I could perceive any drops of water either in the tube or in mination, the apparatus, but I did not obferve the leaft trace of it; neither was the charcoal moift; on the contrary, its furface was covered with afhes. Experiments to be made by futurating the Charcoal with different Subfiances. Experiments till 49th, Since, during the progrefs of an inveftigation, there to be made are always new experiments which offer themfelves, I per- ceived that it would be interefting to make trial with pieces of charcoal faturated with different faline and acid fub{tances, as M. M. Rouppe and Van-Norden, of Rotterdam, had un- dertaken to do, and to fee the effeéts they would produce, with my machine, as well in atmofpheric air as in the differ- ent gafes: But my memoir being of fufficient length already, I leave the care of thefe enquiries to other philofophers ; and this the more willingly, fince it appears that one of the moft able chemifts, M. Van Mons, has engaged in this fubjeét, which, in his hands, will doubtlefs receive every degree of perfection which can be defired. 50th. I fhall only give the refult of four experiments which I made with atmofpheric air. I faturated pieces of charcoal with nitric acid, fulphuric acid, folution of potafh, and lime-water; they were not ufed until GASES ABSORBED BY CHARCOAL, 19 until they had been thoroughly dried on filtering-paper. 1 put them cold into my machine. The following are the refults : 1ft. In the firft fix hours the charcoal, faturated with nitric ran of char acid, produced an abforption of four lines and a half; after- pila as pais wards it gave back the air, and even depreffed the mercury below its level. 2d. The charcoal, faturated with fulphuric acid, effected Me in aati an abforption of nine lines, which it preferved uniformly for =” | twenty-four hours. 3d. The charcoal, faturated with folution of potafh, made ite of an abforption of three lines, and remained fo for twenty-four Baril hours, 4th. That, faturated with lime-water, made only a fmall with lime-water, abforption of a line and a half, although it was kept in expe- riment for twenty-four hours. Thefe four experiments prove that charcoal, faturated with Gane i ita different fubftances, lofes, in part, its power of abforbing : y bate Bhi probably thefe folutions, by filling the pores of the charcoal, rated with fome in fome meafure deprive it of this property. Roh eaagee Sift. No perfon can be more aware than I am, that my enquiry is far from being carried to that degree of perfeétion which I wifhed: I hope, neverthelefs, that philofophers will not be diffatisfied that I have prefented them with new expe- riments, and have made them acquainted with an inftrument, by means of which they can appreciate the effeéts of folar light and calorie on charcoal ; an inftrument which, in many cafes, will ferve them for an eudiometer, and which, when azote fhall be better known, will acquire greater precifion. I hope that, by the labours of other philofophers who may employ themfelves on this fubjeét, this interefting branch of natural philofophy will be brought to perfeétion, and an explanation of thefe furprifing phenomena be obtained, C2 Farther An apology for : this letter. Some objections ftated oy My, Da confidéred, Specific gravity of oxigenous g23. ‘ : CONSTITUTION OF MIXED GASES. VI. Farther Obfervations on the Conjtitution of mixed Gafes. In @ Letier from Mr. Joun Goucu. To Mr. NICHOLSON, + SIR, Ornre philofophers, befides Mr. Dalton, have CAR a the exiftence of free elaftic vapour in the atmofphere; but as the modification given by this gentleman to the opinion, is perhaps the laft it will receive, I am defirous of trefpaffing once more on your pages, in reply to my opponent, as well as to fhew the changes which the goer controverfy has pro- duced in his fyftem. Mr. Dalton’s laft letter begins by nak ee my ignorance of chemiftry, and Rr ate the data, by help of which air has been fhewn to be a chemical compound. Although his fufpicions may be juft in many inftances, they are wrong in this ; for the faéts ftated by Mr. D. were known to me at the time of writing that paper; and the reprobated data were adopted for the following reafons : Mr. Davy found the meet of 100 cubic inches of ae. ‘ous gas, of the temperature of 50°, to be 35.06 grains, the barometer ftanding at 30 inches: now the denfities of the fame elaftic fluid at 50° and 60°, are in the ratio of 105824 to 103744 *: but when the magnitude is given, 7. e. 100 parts, the weights are as the denfities; confequently the weight of 100 cubic inches of oxigenous gas at 60°, is 34.37 grains, the barometer fianding et 30: but 31 grains being the weight -of -an equal bulk of air in like Greduttanees: and its fpecific gravity being denoted by 1000, the correfponding fpecific gras vity of oxigenous gas is expreffed by the number 1108 ; which exceeds Mr. Kirwan’s expreffion only by five. This approx- imation to an exaét coincidence, affords the ftrongeft evidence of the correétnefs both of Mr. Kirwan and Mr. Davy, that can be expected in a queftion of the kind; and, as the former gentleman made ufe of the fame apparatus to determine the weight of air which had loft its oxigen by being expofed to * Thomfon’s Chemiftry, Vol. ey pe 342. the CONSTITUTION OF MIXED GASES, oh the martial pafte of fulphur, the fpecific gravity, drawn from his experiment, was certainly to be preferred in my calcula- tion to any other. ‘This refiduum was called by me azote, probably becaufe Mr. Kirwan called \it phlogifticated air: but it was evidently confidered as a compound in the eflay alluded to by Mr. Dalton; and certainly the advocate for a “multiplicity of co-exiftent atmofpheres will not controvert the fuppofition. The remaining objeGtions made by my opponent to the paper in queftion, are levelled at my ignorance, not at my conclufions ; they fhall therefore be, paffed over in filence, In the mean time, Mr. D. perhaps will not take it amifs if I requeft him to repeat his calculations with the fpecifie gravity of oxigenous gas when properly corrected, and to try. what will be the variation of the eudiometer, either on the data of Mr. Davy or M. Lavoifier. Permit me, Mr. Nicholfon, to conclude this part of my A new inftrue fubjec&t by obferving, that an inftrument of great ufe in pneu- i ray matics might be confiruéted on the principles of your bydro= fiatic weighing machine. The body of it fhould be of glafs, furnifhed with proper ftopples and ftop-cocks, fo that.it might be eafily exhaufted and replenifhed. The preceding is but an amperfeat {ketch of an inftrument, the mechanifm of which I : refign to your pen and His thould the idea appear worth purfuing. Mr. Dalton’s fixiGtures on my lait letter a roche to me very A mifreprefen- fingular opinions; but he negleéts to point out the paragraph ,), at pointed where the grounds of this charge may be found ; a charge which infinuates, that, readies to my notions ae things, a veffel containing a cubic foot of one gas. cannot receive an equal bulk of a different kind: Here indeed he accufes me of grofs ignorance ; for there are but few who do not know that fermenting liquors increafe the denfity of the gafes, which occupy part of the clofe veffels containing them, In reality, the charge is fo. perfeétly groundlefs, that, had it been made by almoft any other perfon, I, would not have hefitated to have pronounced my accufer guilty of mifreprefentation to conceal his want of argument, and to fecure the prejudices of the faperficial reader in his own favour. He, may court the ad- Iiration of fuch; I do not defire their applaufes, _ Mr, Dalton fpeaks with confidence of what he calls his im- Mr. D.’s impor- portant argument, 7, ¢, his affertion, that equal quantities of nt wgument no argument at vapour all, 22 CONSTITUTION OF MIXED GASES. vapour enter a vacuum and an equal fpace previoufly occu~ pied by a gas. No one would refufe its due importance to this argument, after feeing or perufing a fatisfa€tory demon- ftration ; but I know of no fuch thing in Mr. Dalton’s eflays. He afferts, indeed, that a quantity of dry air, confined ina tube, receives an augmentation of force from the prefence of water, equal to that which is produced by the fame caufe in the exhaufted tube. But this is no demonftration, unlefs the porofity of air be firft admitted ; for, without this conceffion, Mr. D. has no right to eftimate the quantity of vapour prefent by the {pring of it; this ought to be determined by weight only. But when did Mr. D. weigh an exhaufied veffel, and afterwards take its weight when filled with vapour? When has he repeated the fame experiment upon the fame veffel containing dry and moift air, and found the reful! favourable to his hypothefis? Negative anfwers to thefe queftions muft convince an impartial judge, that the porofity of the air has been again artfully introduced to eftablith its own exiftence : thus we find the fundamental datum of the fyftem to be de- monftrated by arguing in a circle, which begins and ends with the thing to be proved, On the other hand, Mr. D. is convinced that the admiffiom of vapour into an open boitle expels part of the air. This is a proof that fleam, fuppofing its exiflence in the atmofphere, finds a fpace crowded with gafes lefs convenient than a va- cuum; it, therefore, makes room for itfelf, by diminifhing the denfities of thefe gafes, and creates in them Mr. Dalton’s capacity for the reception of water, This fact being eftablith- _ed, it will alfo be evident, that, when yapour is forced into a gas confined in a clofe veffel, the former cannot make its way through the latter, otherwife than by condenfing it: Such is the nature of the pores of the air, according to Mr. D.’s own principles. The atmofphere is alfo found to oppofe a fimilar refiftance to newly developed gafes; for the gafeous compound contained in an open veffel filled in part with a fermenting liquor, is not a column of the atmofphere perme- ated by an additional body of the carbonic acid, but a mixture, in which the proportion of common air is comparatively fmall. This faét overturns Mr. D.’s general conclafion, that atmo- {pheres may be added to the compound atmofphere at plea- {ures CONSTITUTION OF MIXED GASES. QF: fure, or taken from it, without its difturbing the denfities and fituations of the remaining atmofpheres*. The free paflage of gafes through each other was once the Change in Mr. fundamental maxim of my opponent; at which time he main=2+’s °Pimions: tained, that the variations in the weight of the atmofpheric compound arife from the changeable nature of the aqueous atmofphere, not from the permanent gafes}. This dogma is effential to the fyftem; it has, however, been abandoned by its author himfelf; for Mr. D. when attempting to explain the obfervation of Mr. Kirwan, is obliged to admit the per- manent gafes to be more abundant in dry than in moift air; that is, the denfities and pofitions of thefe gafes depend upon the {tate of the contained vapour, contrary to the hypothefis, This departure from the primitive maxim is avowed openly in Mr. D.’s explanation of the experiment with the moift bottle. Here he is compelled to confefs, that fieam, at low temperatures, diftends the pores of air; and endeavours to preferve the exiftence of his aqueous atmofphere by fomething, which looks like a demonftration from the final Q. E. D.: but it ought to be remembered, that the particles of a fluid prefs equally in all dire€tions ; confequently, that the cor~ pufcles of air would act with their full force on the contiguous - corpulcles of his fuppofed vapour. Perhaps Mr. D. will perceive, by this time, that logical precifion has placed him in the circumftances of certain phi- lofophers mentioned in his third efflay, who are unable to de- fend their opinions. In faét, Mr. D.’s hypothefis is repug- nant to natural appearances in its primitive form; for, ac- cording to it, a fhower of rain is a prodigy ; feeing the drops muft difplace equal bulks of air, and this removal muft be brought about by the inadequate weight of a column of va- pour which has loft part of its fpring. JOHN GOUGH. Middlefraw, December 13, 1804, P. S. Since the publication of my paper on vegetation, I have found, by Dr. Thomfon’s Chemiftry, that M. Ingen- houz had formerly made the fame difcovery. In 1795, I read * Manchefter Memoirs, Vol. V. p- 546, + Manchefter Men «ss, Vol. V. p, 547. his 24 @ Introduction, with reference to the experi- ments made by Defcotils, and by Vauque- lin. Subftance ob- tained from the grains of platina, ON TWO METALS, FOUND IN THE POWDER his work, Sur les Vegetaux, printed at Paris, 17875; but une. doubtedly this feétion had by fome means been overlooked. All that I have to do at prefent, by way of reparation, is to thank Dr. Thomfon for his iedepvaiian and to declare that paper of no value; which in all probability will prove.a fuf- ficient apology to M, Ingenhouz. | VIL. On two Metals, found in the black Powder remaining after the Solution of Platine. By Smituson Tennant, Ey. E.R.S. From the Philofophical Tranfactions for 1804. Upon making fome experiments, laft fummer, on the black powder which remains after the folution ‘of platina, I obferved that it did not, as was generally believed, confift chiefly of plumbago, but contained fome unknown metallic ingredients, Intending to repeat my experiments with more attention during the winter, I mentioned the refult of them to Sir Jofeph Banks, together with my intention of communicating to the Royal Society, my examination of this fubftance, as foon as it fhould appear in any degree fatisfaGtory. “Two memoirs were after- wards publifhed in France, on the fame fubject; one of them by M. Defcotils, and the cthers by Meffrs. Vauquelin and Fourcroy. ‘M. Defcotils chiefly dire&ts his attention to the effe@ts produced by this fubftance on ‘the folutions of platina, He remarks, that a fmall portion of itis always taken up by nitro-muriatic acid, during its aGtion on platina; and, prin- cipally from the obfervations he is thence enabled to make, he infers, that it contains a new metal, which, among other pro- perties, has that of giving a deep red colour to the precipitates of platina. M. Vauquelin attempted a more dire@t analyfis of the Bike ftance, and obtained from it the fame metal as that difcovered by M. Defcotils. But neither of thefe chemifts have obferved, that it contains alfo another metal, different from any hitherto known. The fubftance with which my experiments were made, was obtained from platina which had been previoufly freed from the fand and other impurities generally mixed with it ; fo that it ' REMAINING AFTER THE SOLUTION OF PLATINA. O45 it matt have been contained in the fubftance of the grains of platina, Though it has fomewhat the appearance of plum- ee mae bago, it may eafily be diftinguifhed by its fuperior weight. rctanseant c. By weighing it in a phial with water, I found its fpecific gra- vity almoft 10.7. Before I deferibe the method of feparating the two metals of Phe awe ag which it confifts, it may be worth while to mention the effeéts gyal} ove of it, when combined with different metals in its entire ftate, renders lead, It readily unites with lead; but, even with ten times its own ip sly weight, the compound has not, when melted, much fluidity, cultly fufible Upon diffolving the lead in nitrous acid, the black powder was obtained, with little apparent alteration, not having been en- tirely broken down, but confifting chiefly of the fame fcaly particles as. at firft. With bifmuth, zine, and tin, the effects were nearly fimilar; but, by fufion with copper in a very firong heat, a more perfeG&t union was produced. On at- tempting to diffolve the compound by nitro-muriatic acid, me of the powder was taken up with the copper, forming with copper; a very dark folution. The undiffolved portion confifted partly of the fubftance in its original form of fcales, and partly of a blacker powder, the particles of which were too {mall to be vifible, and which had probably been completely combined with the copper. This filver or gold 5 fubftance may be eafily united, by fufion, with filver or gold; Shee by and it is particularly deferving of attention, that it cannet be - feparated from thefe metals, by the ufual procefs of refining. It remains combined with either of them, after cupellation with lead; and with the gold, after quartation with filver, The alloys retain confiderable duGtility ; and the colour of that with gold, is not materially different from pure gold. I thall now proceed to defcribe the analyfis of the black Analyfis of the powder, and the properties of the two metals which enter into oe ROPES 4 its compofition. The method which I ufed for diffolving it, two metals. was fimilar'to that employed by M. Vauquelin, the alternate aélion of cauftic alkali, and of an acid. I put a quantity of the Fufion with powder. into a crucible of filver, with a large proportion of pure dry foda, and kept it in a red heat for fome time. The Solution in wa- alkali being then diffolved in water, had acquired a dep idee eranses orange, or brownith-yellow colour, but much of the powderder; eure remained undiffolved. This powder, digefted in marine acid, which was partly gave a ‘dark: blue folution, which afterwards became of a‘if?lved in mu- riatic acidy dufky 46 ON TWO METALS, FOUND IN THE POWDER dufky olive-green, and finally, by continuing the heat, of a Fufion, &c- re- deep red colour. Part of the powder being yet undiffolved ia age by the marine acid, was heated as before with alkali; and, due. by the alternate ation of the alkali and acid, the whole ap- Silex. peared capable of folution, At each operation, fome filex was taken up by the alkali; and, as this continued till the me- tallic part was entirely diffolved, it feems to have been chemi- cally combined with it. The allt. folu- The alkaline folution contains the oxide of a volatile metal, ae ar not yet noticed, but which I fhall prefently defcribe, and alfo perates byre- a {mall proportion of the other metal. If this folution is kept pare. for fome weeks, the latter metal feparates fpontaneoufly from. it, in the form of very thin flakes, of a dark colour. The acid fol. The acid {olution alfo contains both the metals, but’ prin hee Ine cipally that which has been mentioned by the French che- ame metal, but ~ £ 4 j ’ principally that mifts. The properties of this laft metal, which they have examined by — remarked, are thofe of giving a red colour to the iriple falt of Vauguelin. é : : : = platina with fal-ammoniac, of not being altered by muriate of tin, and of giving, with pure alkali, a dark brown precipitate, M. Vauquelin allo adds, that it is precipitated by galls, and by pruffiate of potafh; but I thould rather afcribe thefe precis pitates to fome impurity, and probably to iron. The name Jri- As it is neceflary to give fome name to bodies which have dium given £0 not been known before, and moft convenient to indicate by it the metal exa- ies oe pe g mined by Vau- fome charaéteriftic property, I fhould incline to call this metal quelin. {ridium, from the ftriking variety of colours which it gives, while diffolving in marine acid. . In order to obtain the compound of this metal with marine acid in a pure flate, I tried to make it eryflallize. Cry ftals of its By flow evaporation of the folution, only an imperfeétly Muriate cryftallized mafs was produced; but this, being dried on blotting-paper, and diffolved in water, afforded, by again eva diffolved in porating as before, diftin@ o@taedral cryftals. Thefe cryftals pies diffolved in water, gave a deep red coloured folution, inclining to orange. With an infofion of galls no precipitate was formed, but the colour was inftantly, and almoft intirely, taken away. Muriate of tin, carbonate of foda, and pruffiate Precip. by alka- of potafh, produced nearly the fame effe@, Pure ammonia lis and metals precipitates the oxide ; but (poffibly from adding it in excefs) I found it retained a part in folution, acquiring a purple colour, The pure fixed alkalis alfo precipitate the greater part of the 4 é oxide, REMAINING AFTER THE SOLUTION OF PLATINA. Q4: oxide, but are capable of retaining a part in folution, be- coming of a yellow colour., All the metals which I tried, | excepting gold and platina, produced a dark or black pre- cipitate from the muriated folution, which is at the fame time deprived of its colour. ‘The iridium may be obtained in a The metal iridi- pure fiate, merely by expofing the o¢taedral cryftals to heat, ae ek which expels the oxigen and the muriatic acid, It appeared reje@s fulphae of a white colour, and was not capable of being melted, by and arfenic. any degree of heat I could apply. I could not combine it with fulphur, nor with arfenic. Lead eafily unites with it; Its habitudes but is feparated by cupellation, leaving the iridium upon the With the metalge cupel, as a coarfe black powder. Copper forms with it a very malleable alloy, which, after cupellation with the addition, of lead, left a {mall proportion of the iridium, but much lefs than in the former cafe. Silver may be united with it, and the compound remains perfe€tly malleable. The iridium was not feparated from it by cupellation, but occafioned on the furface a dark or tarnifhed hue. It appeared not to be per- fe€ily combined with the filver, but merely diffufed through the fubftance of it, in the fiate of a fine powder. Gold alloyed with iridium is not freed from it by cupellation, nor by quartation with filver, The compound was malleable; and did not differ much in colour from pure gold, though the proportion of alloy was very confiderable. If the gold or filver is diffolved, the iridium is left, in the form of a black powder. . The yellow alkaline folution, which I have already men- The alkaline tioned as containing a metallic oxide, diftin@ from the former, folution did not is confidered by M. Vauquelin as a folution of the oxide EY alia igen chrome in alkali; but I could not, by any teft, difcover the prefence of chrome. After the fuperfluous alkali had been neutralized by an acid, it produced a pale or buff-coloured precipitate with a folution of lead, and not the bright yellow which is given by chrome. But, as we are indebted to the above diftinguifhed chemift, among many other important difcoveries, for our knowledge of the exiftence of chrome, it is not improbable that fome kinds of platina may contain that fubftance, befides the other bodies ufually mixed with it. When the alkaline folution is firft formed, by adding water Jt contains the to the dry alkaline mafs in the crucible, a pungent and pe- week pie of culiar {mell is immediately perceived: This fmell, as I cai rive: wards 63 ON TWO METALS, FOUND IN THE POWDER wards difcovered, arifes from the extrication of a very volatile metallic oxide; and, as this fmell is one of its moft diftin- guifhing charaéters, I fhould on that account incline to call the metal O/imzwm. expellable from This oxide may be expelled from the alkali by any acid, and cae bY a" obtained in folution with water by diftillation. Vhe fulphuric acid,. being the leaft volatile, is the moft proper for this pur- pofe ; but as, even of this acid, a little is liable to pafs over, a fecond flow diftillation is required, to obtain the oxide per-, fedily free from it. The folution thus procured is without colour, has a {weetifl tafte, and the ftrong fmell before men- tioned. Paper ftained blue with violets, was not changed by it tored; but, by being expofed to the vapour of it ina phial, the paper loft much of its blue colour, and inclined to; gray. Asacertain quantity of this oxide is extricated during. the folution of the iridium in marine acid, that part may alfo, be obtained by diftillation. / or obtained by Another mode by which the oxide of ofmium may be ob- diftilling the sek sewaes tained in {mall quantity, but in a more concentrated fiate, is, dertiah te: by diftilling with nitre the original black powder procured from alates, ee cetdes With a degree of heat eae red, there fublimes into. the fcribede neck of the retort, a fluid apparently oily, but which, on cooling, concretes into a folid, colourlefs, femitranfparent mafs, This, being diffolved in water, forms a folution fimilar, to that before defcribed. The oxide, in this concentrated ftate, ftains the {kin of a dark colour, which cannot be effaced. Mot ftriking The moft firiking teft of the oxide of ofmium, is an infufion charaéter of fo- of galls, which prefently produces a purple colour, becoming lution of ofmi- Apis : : sit foon after of a deep vivid blue. By this means, the prefence of this, and of the metal firft defcvibed, may be obferved, Habitudes with when the two are mixed together. The folution of iridium various bodies} js not apparently altered by being mixed with the oxide of ofmium ; but, on adding an infufion of galls, the red colour of the firft is inftantly taken away, and foon afier thé purple and blue colour of the latter appears. The folution of the oxide of ofmium with pure ammonia, becomes fomewhat ° yellow, and flightly fo with carbonate of foda. It is not affeéted by pure magnefia, nor by chalk; but with lime a folution is formed, of a bright yellow colour, The folution . with lime gives with galls a deep red precipitate, which becomes REMAINING AFTER THE SOLUTION OF PLATINA. 99 becomes blue by acids. It produces no effect on a folution of platina or gold; but precipitates lead of a yellowith- brown, mercury of a white, and muriate of tin of -a brown colour. The oxide of ofmium becomes of a dark colour with — alcohol; alcohol, and after fome time, feparates in the form of black films, leaving the alcohol without colour. . The fame effeét is produced by ether, and much more quickly. ' This oxide appears to part with its oxygen to all the metals, — the metals, excepting gold and platina. Silver being kept in a folution of it for fome time acquires a black colour; but does not entirely deprive it of fmell. Copper, tin, zinc, and phof- phorus, quickly produce a black or gray powder, and de- prive the folution of all {mell, and of the power of turning galls of a blue colour. This black powder, which confifts of the ofmium in a metallic ftate and the oxide of the metal employed to precipitate it, may be diffolved in nitro-mu- riatic acid, and then becomes blue with infufion of galls. If the pure oxide of ofmium, diffolved in water, is Amalgam with fhaken with mercury, it very foon lofes its fmell; and the "7°: metal, combining with the mercury, forms a perfect amal- gam. Much of the mercury may be feparated by fqueezing it Pure ofmium through leather, which retains the amalgam of a firmer se by diftilling nae : aie off the mercury. confiftence. The remaining mercury being diftilled off, a powder is left, of a dark gray or blue colour, which is the Itis gray, and ofmium in its pure flate. By expofing it to heat with aceefs sone eh of air, it evaporates, with the ufual fmell; but, if the oxi. oxided. dation is carefully prevented, it does not feem in any degree volatile. Being fubjeGted to a ftrong white heat, in a cavity made in a piece. of charcoal, it was not melted, nor did it undergo any apparent alteration. Heated in a fimilar fitua- Alloys, tion with copper and with gold, it melted with each of thefe . metals, forming alloys which were quite malleable. Thefe compounds were eafily diffolved in nitro-muriatic acid, and, by diftillation, afforded the oxide of ofmium with the ufual properties, . The pure metal which has been previoufly heated, does not Pure ofmium feem to be aéted on by acids; at leaft I could not perceive pat im ' ny " : ; t 3 but eafily any effect produced by boiling it for fome time with nitro- with alkali. muriatic acid, By heating it in a filver cup with cauftic 3 alkali, ~*~ 30 Obfervations re~ fpecting gal- vanifm, &c. ON GALVANISM. alkali, it immediately combined with the alkali, and, with water, gave a yellow folution, fimilar to that from which it was procured. Acids expel from this folution the oxide of ofmium, which has the ufual fmell, and the power of giving to infufion of galls the blue colour before mentioned, Vill. Remarks upon certain Obferoations ef Mr. WiikiNnson, refpecting Galvanifn, By Ra. Tuicknessn, Eq. To Mr. NICHOLSON. SIR, Wigan, Dec. 17, 1804. Tue remarks of Mr. Wilkinfon (which I have not had an earlier opportunity of attending to) on my letter of the 20th September, on galvanifm, are in general founded only on mif- conception; the confequence, probably, of a hafty perufal ina public room, He attributes to me an affertion, “ that two metals are requifite to the produétion of galvanic pheno- mena ;”” but my words are, and particularly marked by italics, ““ two metals, or other fubftances ;’ and were intended to fignify two metals, or two other fubftances; or one metal and one other fubftance ; and to include even that which may be diffolved in the water. The experiment, therefore, of La Grave, with brain and mufcle, which Mr. W. adduces, is not an exception; and ‘ that a fingle metal fuffices” per- fe@tly with pure water only, he did not, I fancy, wifh to be underftood. That copper and the other negative metals are, as I ex- prefled, “‘ aGted upon by the hidrogen,” I muft refer to Mr. W. for authority, to pages 177 and 178 of your Journal ; and that particularly filver (my words are copper, or filver) is rendered more brittle, to page 85: but there cannot, furely, be fironger evidence that copper has an affinity for hidrogen, and confequently an influence in the decompofition of the water, than is afforded by the experiments in which hidrogen gas is obtained from the copper of the pile, and oxigen gas from the oxidated zinc; part of the hidrogen, and of the ox- igen, being prevented from uniting with, and borne away from the metals by the eleétricity, | Mr. ON GALVANISM. G1 » Mr. W. imputes to me alfo the miftake of having “ ob. Obfervations ree ferved that the fenfation is in proportion to the furface ated erin on;” adding, that ‘‘ the experiments of the French _philofo- phers proved, that the aétion of galvanifm on animal fub- {tances is in the ratio of the number of plates employed, and not the furfaces expofed.” This is another inftance of the inaceuracy of Mr. W.’s obfervations; for fenfation I never mentioned ; nor a€tion on animal fubftances ; not at all confi- dering the intenfity, but the quantity only of the ele@ric fluid produced ; which may not always correfpond ; for the charge of {mall plates being weak, although according to their fur- faces, the electricity meets with almoft infurmountable ob.- ftruétions from the interftices of the pile; which to a ftronger charge, from larger plates, are very trifling impediments: but Mr. W. thinks, himfelf, that «‘ the produétion of galva- nic phenomena is always proportionate to the degree of oxi- dation ;” and muft not the quantity of metal oxidated be in proportion to the furface expofed to the water? The French philofophers, too, have “concluded (I quote Mr. W.’s own words, from p. 207 of your laft volume) that the effeéts of a galvanic battery on metallic fubftances, are in proportion to the furfaces of the plates employed :” Muft we not then fuf- pect the experiments to have been imperfeét which led them to conclude, if they have fo concluded, that the effeGis on animal fubftances are different ? Whether I “ fet out too hypothetically as to eleétricity being a modification of caloric,” is a queftion on which many _ of the moft celebrated men of fcience would differ from Mr. “W. in opinion, “ Pars invenit utraque Caupas; yet it appears to me, that the experiment noticed by @ Correfpondent, p. 173, almoft determines it: ‘ If the gas which is produced from one of the wires communicating with the pile in the water, be united and ‘inflamed with the other in a juft proportion, the water which is common to both is reproduced, and common _ fire iw great abundance.” Thus the electric fluid, which alone conveys the oxigen and hidrogen from the water, a@tually be- comes, when differently modified by combuftion, for there is no evidence of the prefence of fire until this point of time,” aétive caloric. ‘+ But fuppofing, with Mr. W. that the'ele€tric matter and calorie are perfectly diftincét bodies, we have Mill the fame i reafon 32 PRUSSIC ACID. Obfervations ree reafon to conclude that the former is combined with wate?, {pecting gal- vanifm, &c, which we have to believe that it is contained in metals : What then becomes of it when the water is decompofed, if, as he imagines, the eleétric, or ‘ galvanic phenomena, en- tirely depend upon the metal undergoing a chemical change,” 1 muft confefs I cannot conjeéture: but, in truth, it is ens tirely the caufe of all the phenomena which take place: the quantity afforded by the metal, fo very {mail a. portion of which undergoes any chemical change, mutt be too trifling to be confidered; for if any more than the oxidated part of the metal contributed, the quantity of the metal in the plates, as well as the extent of its furface, would in fome degree have an effeét: but this, as I alledged, is not the cafe ; and, there- fore, Mr. W.’s fanciful conje@ture, that there is as it were a fpring of eleétric fluid in the metal, as a refource for a fup- ply, although very ingenious, may be regarded as a perfeét hypothefis—a fuppofition unfupported by any faét; and as an inftance, from his partiality for it on this occafion, of our " difpofition to overlook imperfeétions in our own performances, General deduce tions. whilft we obferve them in the works of others. » Jam, Sir, Your moft obedient fervant, RA. THICKNESSE, a EEE IX. Abptraé of a Memoir on the Pofibility of obtaining Prufiate of Potafhi free from Iron; the Unalterability of the Prufiic Acid at high Temperatures; and the true Nature of the Combina- tions of this Acid with different Bafes. By Bucuouz, (Concluded from p. 282, Vol, IX.) "Tusse two experiments therefore prove, that from four parts of dried blood and one of carbonate of potafh, no more pruffiated alkali can be obtained than from two of blood and one of alkali. . From what has been fo far ftated the author concludes, after varying and repeating the experiments here detailed), «. 1. That PRUSSIC ACID. 33 1. That four parts of blood to one of carbonate of potafh are Bef proportion too much, and that equal parts of blood and carbonate of potath va a ae ‘are rather good proportions for obtaining the moft poffible blood, are 1 p. quantity of pruffiated alkali. The latter proportions have, #42 > moreover, the difadvantage, that the excefs of alkalis acts upon the oxide of iron of the blood as well as upon the cru- cible, and therefore introduces new impurities. Two parts of blood and one of carbonate of potafh, appear to be a better proportion for obtaining the greateft poffible quantity of pruffiate of potafh, under like circumftances. 2. Alcalies deprived of carbonic acid, are not better than It is no advan- carbonated alkalies for the produ@tion of pruffiated alkalies can by treatment with blood; for they become reconverted into carbonated alkalies during the procefs. . . 3. No pure pruffiate of potafh can be obtained, é¢xcept care The formation be taken that the mixture of blood and alkali be neither a A much nor too little ignited. The criterion which may ferve dual heat with as a guide to the operator, is the ceffation of the flame, after xa ween a gradually increafed ignition without fufion. For if the mafs till the flume be heated fuddenly fo as to effeét a partial fufion, or if it be Ss continued after the difappearance of the flame, it will be in vain to look for pure pruffiated alkali. 4, The high colour of pruffiated alkalis is not always owing When the high to the prefence of iron, but more frequently to a minute eaeh ahah quantity of charcoal. This impurity is not capable of yielding coal, it does not refults that could miflead the chemical enquirer in the appli- Produce fallacy. cation of this re-agent. 5. The quantity of water employed for the lixiviation of Very little water pruffiated alkali from the ignited mafs, fhould be as fmall as no poacee . poffible, and heat fhould be avoided as much as poffible. For ed. if pruffiated alkalis be heated in contaét with water, part of the pruffic acid is liberated, ammonia is produced, and car= bonate of potafh formed. 6. Acetic acid cannot be employed for removing the ad- Acetic acid can- mixture of carbonate of potafh from pruffiated alkalis; for the ee ae energy of the affinity of pruffic acid is lefs than the energy of dundant potath. the affinity of carbonic acid to potafh ; the union of the pruffic acid and potath is therefore demolifhed, in preference to that of the carbonate of potath. Vou. X.—Janvuary, 1805. D On $4 NEW METAL FOUND 4N CRUDE PLATINA. X. On a new Metal, found in Crude Platina. By Witttam Hype Woxtaston, M.D. F. R.S, From the Philofophical Tranj- actions, 1804. Introduction. N OTWITHSTANDING I was aware that M. Defcotils had afcribed the red colour of certain precipitates and falts of platina, to the preferice of a new metal; and although Mr. Tennant had obligingly communicated to me his difcovery of the fame fubftance, as well as of a fecond new metal, in the fhining powder that remains undiflolved from the ore of platina ; yet I was led to fuppofe that the more foluble parts of this mi- neral might be deferving of further examination, as the fluid which remains after the precipitation of platina by fal ammo- niac, prefents appearances which I could not afcribe to either of thofe bodies, or to any other known fubftance. New metal, My inquiries having terminated more fuccefsfully than I had Robodium. expected, I defign in the prefent Memoir to prove the exiftence, and to examine the properties, of another metal, hitherto un- known, which may not improperly be diftinguifhed by the name of Rhodium, from the rofe-colour of a dilute folution of the falts containing it, ) Palladium found | fhall alfo take the fame opportunity of ftating the refult of in ore of platinas various experiments, which have convinced me, that the me- tallic fubftance which was laft year offered for fale by the name of Palladium, is contained (though in very fmall proportion) in the ore of platina. Remaining fo- | hecolour of the folution that remains after the precipitation jution after pre- of platina, varies, not only according to its ftate of dilution, but m mene Ee ita according to the ftrength and proportions of the nitric and ina, contains Fs) iron and other muriatic acids employed. This colour, though principally ing owing to the quantity of iron contained in it, arifesalfo in part froma fmall quantity of the ammoniaco-muriate of platina, that neceflarily remains diffolved, and from other metals contained in ftill fmaller proportions. Precipitable by (A. 1.) To recover the remaining platina, as well as to fe- zine or 1r00* — pharate the other metals that are prefent from the iron, I have in fome experiments employed zinc, in others iron, for their precipitation. The former appears preferable; but, when the latter hasbeen ufed, the precipitate may immediately be freed from NEW METAL FOUND IN CRUDE PLATINA. 35 + rom the iron that adheres to it, by muriatic acid, without the lofs of any of thofe metals which are at prefent the fubjeG of -iniquiry. (A 2.) indie: in one inftance diffolyved fuch a precipitate in The fame refi- nitro-muriatic beaii and precipitated the platina by fal ammo- ee Seo niac, I fuffered the remaining fluid to evaporate without heat; 3 by Wantakcote and obtained a mixture of various cryftals, very different from ¢vap- each other in form and colour. From thefe, I fele@ed for exa- mination fome that were of a deep red colour, partly in thin plates adhering to the fides of the veffel, and partly in the form of fquare prifms having a re€tangular termination. __ (A 3.) A portion of thefe cryftals being heated in a fmall Deep red cryftalg tube, yielded fal ammoniac by fublimation, and left a black ple nike refiduum, which, by greater heat, acquired a brilliant metallic 4 whitenefs, but could not be fufed under the blowpipe. Having —not platina. obtained this fubftance from a diftinétly cryftallized falt, I was’ inclined to confider it as a fimple metal; and, as I found it to be wholly infoluble in nitro-muriatic acid, I judged it not to be platina. (A 4.) The cryftals alfo, inftead of being nearly infoluble, The cryftals ‘like the ammoniaco-muriate of platina, were diffolved ina {mall aa ‘quantity of water, and gave a rofe-coloured folution. Upon which makes the mixing this with a folution of platina, the ammonia was tranf- fis of platina ferred by fuperior affinity to the latter, forming an ammoniaco- ‘muriate of platina; and the precipitate was of a yellow colour. ‘Confequently, the metal contained in the falt, was neither platina nor that which gives the red colour to the falts of platina, It would be ufelefs to detail my firft unfuccefsful experiments The bafe was the made upon the properties of this metal, in hopes of difcovering To eee means by which iis feparation from platina might be effeéted ;ticed, I fhall therefore confine mylelf to the following procefs, which appears to be the moft direét for procuring rhodium ina ftate of purity. In the fame procefs alfo palladium is obtained, fo as to afford a prefumption, that it is rather a natural fimple body, than any artificial compound. . (B 1.) Since the platina to be procured in this country, Procefs for ob- generally contains fmall fcales of gold intermixed, as well as eta portion of the mercury which tee Spaniards employ for the the platini- feparation of ihe gold, the platina uled for my experiments, 8'ains. after being by mechanical means freed, as far as poflibie, from | D2 all 36 NEW METAL FOUND IN CRUDE PLATINA. all vifible impurities, was expofed toa red heat, for the pours. pofe of expelling the mercury. It was then digefted for fome time in a fmall quantity of dilute nitro-muriatic acid, and fre- quently fhaken, till the whole of the gold was diffolved, toge- ther with any impurities that might fuperficially adhere to the grains of platina. ) Solution of the (B2.) Of the ore thus prepared, nearly 2% ounces were then roe nitro-mur diffolved in nitro-muriatic acid, (diluted for the purpofe of leaving as much as poflible of the fhining powder,) and the whole fuffered to remain in a moderate fand heat, till com- pletely faturated. Precipitation by (B 3.) Such a portion of this folution was then taken for fal amm. analyfis, as correfponded to 1000 grains of the prepared ore. An ounce of fal ammoniac was next diffolved in hot water, and ufed for the precipitation of the platina, The precipitate obtained was of a yellow colour, and, upon being heated, yielded 815 grains of purified platina. Refidwal liquor (B 4.) The water ufed for wafhing this precipitate having precipitated by been added to the folution poured from it, a piece of clean zinc ar was immerfed in it, and fuffered to remain, till there appeared to be no further a€tion upon the zinc. The iron contained in the ore (to the amount of 14 or 15 per cent.) remained in {olution. The other metals had fublided, in the form of a black powder, which I eftimated between 40 and 50 grains; but, as there was no occafion to weigh it with accuracy, I thought it better not to dry this precipitate, for, if it be heated, the rhodium is in dan- ger of being rendered infoluble. Precipitatede- (B 5.) As I had previoufly afcertained that this precipitate et ened would contain platina, rhodium, the fubftance called palladium, acid; and then copper, and lead, the two laft metals were firft diffolved in rang eee very dilute nitric acid, aided by a gentle heat. The remainder, acids after being wafhed, was digefted in dilute nitro-muriatic acid, which diffolved the greater part, but left as much as 42 grains undiffolved.* Addition of (B 6.) To the folution were added 20 grains of common ay gy Nr falt; and, when the whole had been evaporated to drynefs with muriates of | avery gentle heat, the refiduum, which I had found, from prior platina, palladi- P um andrhodiurr. * Tt was prefumed that this refiduum confifted principally of the All but the triple l-colled by MI ae : falt of rhodium ™etal called by Mr. Tennant Iridium ;, but, as it was accidentally was wafhed off miflaid, and was not examined, it might alfo- contain a portion of by alcohol, rhodium, experi- NEW METAL FOUND IN CRUDE PLATINA, Si experiments, would confift of the foda-muriates of platina, of palladium, and of rhodium, was wathed repeatedly with {mall quantities of alcohol, till it came off nearly colourlefs. There remained a triple falt of rhodium, which by thefe means is freed from/all metallic impurities. (C 1.) This falt, having been diffolved in a {mall quantity of Solution in hot water, and let to ftand 12 hours, formed rhomboidal cryf{- vere tals, of which the acute angle was about 75°. (C 2.) It was then again diffolved in water, and divided into One half pre- two equal portions, ‘Of thefe, one was decompofed by a piece “P* PY zinc. of zinc, and the other examined by the following re-agents, (C 3.) Sal ammoniac occafioned no precipitation; but, when The other half a folution of platina was added to the mixture, a precipitate was i ag : immediately formed, and the colour of this precipitate was yel- by fal-amm. i low ;_ which again proves that the metal contained in this falt, is neither platina itfelf nor that which gives the red colour to its precipitates. (C 4.) Pruffiate of potafh occafioned no precipitation, as it nor by pr. pot. would have done, if the folution had contained palladium. *” (C 35.) Hydro-fulphuret of ammonia, which would have pre- nor by hydro- cipitated either platina or palladium, caufed no precipitation of ‘Pb. of amm. this metal, , (C 6.) The carbonates of potath, of foda, or of ammonia, nor by carb. al- occafioned no precipitation ; but the pure alkalis precipitated a F#liss but by F ; . purealk. foluble yellow oxide, foluble by excefs of alkali, and alfo foluble in in acids, every acid that I have tried. (D 1.) The folution of this oxide in muriatic acid, upon being Muriatic folution evaporated, did not cryftallize; the refidaum was foluble in of shadiumt. alcohol, and of a rofe colour. Salammoniac, nitre, or common falt, caufed no precipitation from the muriatic folution; but formed triple falts, which were not foluble in alcohol. (D2,) The folution in nitric acid alfo did not cryftallize. A Nitric folution. drop of this folution, being placed upon pure filver, occafioned no ftain. On the furface of mercury a metallic film was preci- - pitated, but did not appear to amalgamate. The metal was alfo precipitated by copper and other metals, as might be pre- fumed, from the ufual order of their affinities for acids, (EZ 1.) The precipitate obtained by zinc (C 2.) from the re- The precip. bee maining half of the falt, appeared in the form ofa black powder, ans eee weighing, when thoroughly dried, nearly 2 grains, correfpond- ig a ing to about 4 grains in the 1000 of ore diflolved. | (E 2.) 4 fin.ply heated, fufible with NEW METAL FOUND IN CRUDE PLATINA. (E 2.) When expofed to heat, this powder continued black ; with borax, it acquired a white metallic luftre, but appeared infufible by any degree of heat. (E 3.) With arfenic, however, it is, like platina, rendered arfenic and with etn e; and, like palladium, it may alfo be fufed by means of © fulphour. Metallic button not malicable, unites with metals except mercury Gold and rhodi- um 4 to ¥. Gold and rho- dium 6 to one. It does not dif- colour gold. Solubility of rhodium affected by combination. fulphur. The arfenic, or the fulphur, may be expelled from. it by a continuance of the heat; but the metallic button ob- tained does not become malleable, as either of the preceding metals would be rendered by fimilar treatment. (E 4.) It unites readily with all metals that have been tried, excepting mercury ; and, with gold or filver it forms very mal- leable alloys, that are not oxidated by a high degree of heat, but become inciufied with a black oxide, when very flowly cooled, (E 5.) When 4 parts of gold are united with one of rhodium, although the alloy may affume a rounded form under the blowpipe, yet it feems to be more in the ftate of an ive than in completé fufion! (E6.) When fix parts of gold are alloyed with one of rho- © dium, the compound may be perfeétly fufed, but requires far more heat than fine gold. ‘There is no circumftance in which rhodium differs more from platina, than in'the colour of this alloy, which might be taken for fine gold, by any one who is not very much accuftomed to difcriminate the different quaitties of gold. On the contrary, the colour of an alloy containing the fame proportion of platina, differs but little from that of platina. This was originally obferved by Dr. Lewis. The “colour was ftill fo dull and pale, that the compound (five ‘*to one) could fearcely be judged by the eye to contain any gold.”’* I find that palladium refembles platina, in this property of deftroying the colour of a large quantity of gold, Whenone part of palladium is united to.fix of gold, the alloy is nearly white. (E 7.) When I endeavoured to diffolve an alloy of filver of of gold with rhodium, the rhodium remained untouched by either nitric or nitro-muriatic acids; and, when rhodium had been fufed with arfenic or with falphur, or when merely heated by itfelf, if was reduced to the fame ftate of infolubility. But, * Lewis’s Philofophical Commerce of Arts, p, 526, when NEW METAL FOUND IN CRUDE PLATINA, 89 when one part of rhodium had been fufed with three parts of bifmuth, of copper, or of lead, each of thefe alloys could be diffolved completely, in a mixture of two parts, by meafure, of muriatic acid, with one of nitric. With the two former metals, the proportion of the acids to each other feemed not to be of fo much confequence as with lead; but the lead appeared on another account preferable, as it was moft eafily feparated, when reduced to an infoluble muriate by evaporation. The muriate of rhodium had then the fame colour and properties, as when formed from the yellow oxide precipitated from the original falt, (D 1.) (£ 8.) The fpecific gravity of rhodium, as far as could be Specific gravity. afcertained by trial on fo fmall quantities, feemed to exceed 11. That of an alloy confifting of one part rhodium and about two parts lead, was 11,3; which is fo nearly that of lead itfelf, that each part of this compound may be confidered as having about the fame f{pecific gravity. F. As it was expeéted that the alcohol employed for wafhing The alcohol the falt of rhodium (B 6.) would contain the foda-muriates of ae afed ia : xu g the falts platina and of palladium, the platina was firft precipitated by examined. fal ammoniac. This precipitate was of adeep red colour; and, when it had been heated, to expel the fal ammoniac, the pla- tina which remained was of a dark gray colour. _ (G 1.) To the remaining folution, after it had been diluted to prevent any further precipitation of platina, I added pruf- fiate of potafh, which inftantly occafioned a very copious preci- pitate, of a deep orange-colour at firft, but changing afterwards to a dirty bottle-green, which I afcribed to iron contained in the pruffiate. (G2.) This precipitate, when dry, weighed 12% grains, After it had been heated, it left a metallic refiduum, in {mall prains, of a gray colour, weighing nearly 7 grains, A {mall portion of it being heated with borax, communicated a dark brown colour to the borax, as from iron, and acquired a bright metallic luftre, but could not be fufed under the blowpipe, With fulphur, however, it fufed immediately into a round globule, which, by floating upon mercury, appeared of lefs fpecific gravity than that metal. (G 3.) The whole quantity was then treated in the fame manner, and purified by cupellation with borax, tll it cooled with a bright furface. From the globule the fulphur was ex- _ pelled, 40 NEW METAL FOUND IN CRUDE PLATINA, pelled, .by expofure to the extremity of the flame; and it be- came fpongy and malleable, weighing in this ftate very nearly five grains, Palladium. (G 4.) A portion of this metal was diffolved in ftrong nitrous acid, was precipitated by green fulphate of iron, and in other refpeéts, pofleffed all the properties afcribed to the palladium offered for fale, in the printed paper that accompanied it, as well as others fince noticed by Mr. Chenevix. Its differences (G 5.) In its precipitation by pruffiate, it differs moft effen- from platinae tially from platina; and confequently is by no means difficult to be diftinguifhed, or feparated from it. . (G. 6.) The aétion of muriate of tin upon the folutions of thefe metals, is alfo totally different. A dilute folution of pla- tina, is thereby changed froma pale yellow to a tranfparent - blood-red. A folution of palladium, on the contrary, ufually becomes opaque, by the formation of a brown or black preci- pitate; but, if mixed in fuch proportion as to remain ee rent, it changes to a beautiful émerald-green. (G7.) In the formation of triple falts with the alkalis, as obferved by Mr. Chenevix, palladium may be faid to refemble platina; but the falts thus formed are far more foluble than the correfponding falts of platina, and differ entirely, in the colour and form of the cryftals, ~ (G8.) The foda-muriate of palladium is a deliquefcent falt; that of platina, on the contrary, forms permanent cry- ftals. (G9.) The triple falts of platina, with either muriate of ammonia or of potath, form o€taedral cryflals of a yellow colour, that are very fparingly foluble in water, . The corre- fponding falts of palladium, likewife refemble each other in every refpe@t. The cryftals are very foluble in water, but in- foluble in alcohol; their form is that of a four-fided prifm, and they each prefent a curious contraft of colour, that certainly is not obfervable in any known falt of platina. Curious contrat. (G10.) Although the folution is of a deep red, the cryftalg of colour in theare of a bright green when viewed tranfverfely. In the diréc- ch. palla- tion of their axes, however, the colour is the fame as that o the folution; but, on account of its extreme intenfity, it is with difficulty diftinguifhed in fragments that exceed +2, of an inch in thicknefs, One confequence of this colour is neverthelefs Vv ery N\ a NEW METAL FOUND IN CRUDE PLATINA. AJ very obfervable; namely, that in viewing any cryftal obliquely, it appears of a dull brown, that arises from a mixture of the red and green.* The charaéters of palladium that have been enumerated, un- Probability that doubtedly belong to none of the fimple fabftances that we are aang og acquainted with; and no experiment that I have made, has infer thet palla- tended to confirm the fufpicion of its being a compound, con-@%™ 's a com- : ; ; pound, from its fitting of any known ingvedients. The experiments above being found in related, fhow evidently, that the ore of platina contains a very ee {mall quantity of palladium; and it is not unlikely that this may have been a conftituent part of fome of the compounds obtained by Mr. Chenevix, and may have mifled him, by fome pro- petties which he would confequently obferve, into the fuppo- fition that he had formed palladium. It is not, however, without having repeatedly pelea to All attempts of imitate his experiments, that I have ventured to diffent from irons Goa fuch authority. I made many attempts to unite pure platina Acute with mercury, by folution, and by amalgamation; but without fuccefs, in any one inftance. From a folution of platina, carefully neutralized, as Mr. Chenevix dire@ts, with red oxide of mercury, and mixed with a folution of green fulphate of iron, I indeed obtained fuch a 2 * The change of colour above defcribed, though certainly un- common, is neverthelefs not peculiar to the falts of palladium, but may be feen alfo in fome kinds of tourmalin. “ Among thofe which come to us from Ceylon, fome are tranfparent; and one variety is of a deep red in the dire&tion of its axis, but of a yellowith green when viewed tranfverfely. ‘There is alfo a correfponding, but op- pofite contraft of colours, that has been obferved by Muller, and defcribed by Bergmann, in fome of the Tyrolefe tourmalins. The general afpeét of thefe ftones is black, and apparently opaque.— Some, however, of which the fraéture is vitreous, are found to tranfinit a yellowifh-red light when viewed tranf{verfely, but in the direétion of their axis the colour isa dull bottle green. In each of thefe tourmalins, as well as in the falts of palladium, .the colour in the direétion of the axis is at leait ten times more intenfe than in the tranfverfe dire&tion. A thin lamina, cut from the end of a Tyrolefe tourmalin for this purpofe, tranfmitted no vifible light, till it was reduced to 4, of an inch in thicknefs; and, when le{s than ,2, of an inch, it was not more ping nie ‘than another portion of the fame cryltal feen tranfverfely, =4, of an inch in thick- nefs. ee precipitate 42 ELECTRICITY OF METALS. precipitate of metallic flakes ashe defcribes; but, upon exami- nation of thefe flakes, they yielded mercury by diftillation ; and the remainder confifted of platina combined with a portion of iron, but had not any properties which I could fuppofe owing to the prefence of palladium. Other fa&s and Upon comparing the {pecific gravity of this fubftance, which dros hag was faid to be, at moft, 11,8, with that of mereury or of platina, dium isa finple I] was always ftrongly inclined to doubt the poffibility of its eval. being compofed of thefe metals. I could recollect ho one inftance, in which the fpecific gravity of any compound is lefs than that of its lighteft ingredient, and could not, without care- ful examination, admit the fuppofition, that mercury could be rendered lighter by intimate union with platina. It now ap- pears fully confirmed that this perfuafion, arifing from uniform experience, was well founded; for, if we confider the diffi- culty of producing even an imperfe& imitation-of palladium, the failure of all attempts to refolve it into any known metals, the facility of feparating -it from any mixed folution of thofe which it has been fuppofed to contain, as well as the number and diftinéinefs of its charaéteriftic properties, I think we muft ‘ clafs it with thofe bodies which we have moft reafon to confi-_ der as fimple metals, x Letter from Mr. Wom. Wixson, exhibiting the Eleétricity of Metals, without the Help of any condenfing Inftrument, To Mr. NICHOLSON. SIR, London, Dec. 22, 1804, Whether the W uen I fet about making the compound eleétrical con- San palin denfer defcribed in my laft letter to you, I intended to repeat the effeé of the the experiments of Cavallo relating to the eleétricity obtained ic ao the by the contaét of metals related in the third volume of the 4 fourth edition of his Treatife of Electricity ; but before the inftrument was finifhed, I was induced (by fome experiments I had made relative to the caufe of excitation of eleétricity) to fuppofe that it is not the contact of the meials that is the caufe of the appearance ofeleétrical figns, but the feparation of the metals 7 se: ae a? Ree ‘ ‘ | ELECTRICITY OF METALS. 43 metals from contaét. And this fuppofition was very much ftrengthened, when, upon examination, I found that all who have made experiments on this fubje@ have feparated the metals from contaé before they examined them as to their ele@tricity. If the contaé& of the two metals be the caufe of the eleétri- —determinable ’ Wor by varying the cal figns, ‘he whole effeét that one metal can have on another gece, will be communicated at the time of contact, however few the points are that form the coniaG, becaufe both the metals being conductors of electricity, if one pofleffed a greater proportion of it than the other, a part will be communicated to the other at the time of conta&, to form an equilibrium, and this will be done as well by a few points of contaét as by a great many. But if it is the feparating them from contaé, thatis the caufe of the cleéirical fign, the more exienfive the contaét is the more powerful will the figns be when the metals are feparated. To put this io the teff of experiment, I pierced a piece of Sieve of one thin fheet copper full of {mallholes, juft big enough to permit pe - filings to pafs through them two or three particles of filings of another a aeie ick metal ai a time, fo that almoft every particle muft be in con- tat with the copper before it can pafs through, and’ confe- quently the furface of contaét be very great with a compara- tively {mall quantity of metal. | I fifted through this copper fieve fome filings of zinc intoa _ tin plate laid on the cap of a gold leaf ele€trometer, and the . gold leaves diverged near an inch with pofitive ele@tricity, when about half an ounce of filings had been fifted into it. Encouraged by this ftriking refult, I procured fieves and filings of different metals. The refults of the trials with them are contained in the following table; where P ftands for pofitive eleétiicity, N for negative, and when it was not {trong enough to eifeét the electrometer, that is denoted by O. \ Filings of Sifted through Effect, Copper DO: ‘Refults of ex- 2 Tin N. ftrong periments, Copper Silver 0, Zinc P. ftrong Lead N. Copper P. ftrong < Tin O. i. 2ANC Silver P. ftrong bt Zinc P. exceeding weak Lead © O, AA Refults of ex- periments. ELECTRICITY OF METALS. Filings of —— Sifted through Copper Tin Silver Zinc Lead Copper Tin Silver Zinc Silver Copper Tin Silver Zine | Lead Steel ie fees Tin Silver Zinc Lead Lead Tin Silver Zinc Lead | Copper Bra{s Copper Tin “Silver Zinc Lead Bifmuth Copper Tin Silver Zine Lead Antimony Copper Tin | Silver Zinc Lead Nikel \ -ee Effect. a Ee, P. rather ftrong N. very weak P. ftrong O. N. weak O. N. weak O. ATS N. very ftrong ditto ditto ditto ditto ZZZz very flrong very ftrong not quite fo ftrong as with Ffilver OS P. very ftron N. firong : J P. ftrong O. N, P. exceeding ftrong O. P. exceeding ftrong P. ftrong N., O. N. very ftrong P. ftrong N. ftrong N. very ftrong P. exceeding ftrong O. P. ftron O. F P, In MR. HATCHETT’s EXPERIMENTS, &c. 45 In all the above experiments there was a large furface of contaé, and the electrometer only was ufed; but in thofe made by Cavallo and others who had a very fmall furface of contact, eleétrical figns could not be made to appear without the help of doublers, multipliers, 8c. of eleétricity. I therefore think there can be no doubt about the feparating the metals from con- taét being the caufe of their appearing. | ‘If you think the above worthy of a place in your Phliofophi- cal Journal, you will very much oblige me by inferting it therein. I am your obedient humble fervant, WM. WILSON. XII. Analytical Experiments and Obfervations on Lac. By CHARLES Hatcuetr, Eyy. Partly abridged, but chiefly extratted from the Philofophical TranfaGions for 1804, by W.N. Ir is uncertain at what time the ufeful fubftance, called Lac, Ufes of lac pe~ firft became known in Europe. It has long been ufed by the °vliar to India. Indians for purpofes different from thofe to which it is applied in Europe. In particular as Mr. Wilkins informed the author, Aqueous folution they diffolve fhell lac in water by the addition of a little borax, u eine affords and by adding lamp black or ivory black, they obtain an ink, j not eafily affe€ted by water, when dry. The natural hiftory of lac, which is the nidus of the coccus Natural hiftory or chermes|lacca, has been detailed by Mr. Kerr, Mr. Saun- ° 1¢ ders, and Dr. Roxburgh, in the Philofophical ‘Tranfaétions for 1781, 1789, and 1791. It is diftinguifhed into four kinds, Four kinds. of which, however, only three are commonly known in com- merce, viz. ftick lac, feed lac, and fhell lac; the difference of thefe, with that of the fourth, called lump lac, is as follows. 1. Stick lac, is the fubftance or comb in its natural ftate, 3, Stick Jac. incrufting fmall branches or twigs. 2. Seed lac, is faid to be only the above, which has been fe- 2, Seed Jac, parated from the twigs, and reduced into fmall fragments; but I fufpeé. it to have undergone fome other procefs, as I have found the beft fpecimens to be very confiderably deprived of the colouring matter.*: / 3. Lump * Mr. Wilkins informs me that the crude lac, as itis taken from the branches and twigs of the trees, is ufually deprived of its colour. ing AG MR, HATCHETT’s EXPERIMENTS 3. Lump lac. 3. Lump lac, is formed from [eed lac, liquefied by fire, and formed into cakes. And, 4 Shell lace 4. Shell lac, according to Mr, Kerr and Mr. Saunders, is prepared from the cells, “igual ftrained, and formed into thin (ranfparent laminz, in the following manner. How made from: ‘* Separate the cells from the branches; break them into {mall the eels. “* pieces; throw them into a tub of water, for one day; wath “« off the red water; dry the cells, and with them fill a cylindri- ‘* cal tube of cotton cloth, two feet long, and one or two inches <¢ in diameter ; tie both ends, and turn the bag above a charcoal ‘ fire; as the ~ liquefies, twift the bag, and, when a fufficient <¢ quantity has tranfuded the pores of the cloth, lay it upon a *¢ {mooth junk of the plantain tree, and witha ftrip of the plan- ‘* tain leaf draw itintoa thin lamella; take it off while flexible, ‘* for in a, minute it will be hard and brittle.” + The degree of preffure on the plantain tree, regulates (ac- cording to Mr. Saunders) the thicknefs of the thell; and the quality of the bag determines its finenefs and tranfparency. Lac is moftly Affam furnithes the ansalel, quantity of the whole of the lac had from Affam. now in ufe, ¢ Bef quality. Mr, Kerk ({peaking of hick lac) obferves, that the beft lac is of a deep red colour; for, if it is pale and pierced at the top, the value is diminifled, becaufe the infe@s have left their cells, and confequently thefe can be of no ufe as a dye or colour, but probably may be better for varnifhes. The feed lac which I have examined, contained but little of the colouring matter, and appeared (as I have already obferved) io have undergone fome procefs of purification; but; of all the varieties, fhell lac contains the-beaft of the tinging fubftance, as may well be expeéted, when the mode of preparing it is con- fidered. Chemifts have It is remarkable, that although lac has been known, and im- paid little attene Horted into Europe, during fo long a time that the date’cannot atali now be afcertained, yet it has but little attraéted the attention of chemifts. ing matter by boiling, having been previoufly reduced, by pounding into {mall fragments. In Bengal, the filk dyers are the people who thus produce what we call the feed lac, which they do for the fake of the colour. + Phil. Trans. 1781, p. 378. t Phil. Tranf, 1789, p. 109. 4, . The AND OBSERVATIONS ON LAC, 47 The firft chemift of eminence who mentions it, and the only Experiments of one who has fubjeéted it to any thing like a regular examination, vohhe re is the younger Geoffroy, whofe Paper is publithed inthe Mém. de V Acad. de Paris for the. year 1714.* In this Paper, Mr. Geoffroy feems to have been chiefly induced to examine it on account of its tinging fubftance; but he neverthclefs has not negleéted the fubftance which conftitutes the cells. This he confiders to be a fort of wax, very diftin@ from the nature of gum orrefin. But it is to be obferved, that he formed this Opinion, not fo much upon the refults of chemical experiments, as upon the cellular conftruGtion obferved in the ftick lac, which, as he juftly remarks, demonftrates it to be formed by infeéts, after the manner that the honeycomb is formed by bees; and that it is not therefore, as (ome have fuppofed, a gum or refin, which has exuded from vegetables finiply punctured by infeéis.+ Geoffroy and Lemery obtained from lac, by diftillation, —and Lemery. fome acid liquor, and a butyraceous fubftance. Moreover, Geoffroy obferves, that when ftick lac was thus treated, fome ammonia was alfo obtained, but not when feed lac was em- ployed. He alfo mentions another fort of Jac, brought from Mada- Another lac gafcar, and called by the natives Lit-in-bitfic, ‘This fubftance, nabghicae dee he fays, 1 is {earcely to be diftinguifhed from bees-wax, which it Pecia of China, much refembles in colourand odour; and that it is produced by a grayith infeét, much larger than the chermes Jacca. It is evi- dent however, from Geoffroy’s defcription, that this fubftance is very different from the common lac; and there can be little doubt, but that it is the fame as that which was, a few years ago, examined by Dr. Pearfon, under the name of white lac, a fubftance refembling the Pé-la of the Chinefe. { ' Geoffroy (as I have ftated) confidered lac as a fort of Wax ; Notions of che- ‘and fince his time it has fcarcely, if at all, been fubjeéted to a concerning _ * Obfervations fur la Gomme Lacque, et fur les autres Matiéres animales qui fourniffent la Teinture de Pourpre. Par. M. Geoffroy fe jeune. Mém. del Acad. 1714. p 121. + Mr. Kerr obferves, that as a red.fubftance is obtained by inci- fion from the plafo tree, very analogous to lac, it is probable, that the infeéts haye little trouble in animalizing the fap of thefe trees, in the formation of their cells. Phil. Trans, 1781, p. 377. ' t Phil, Trans. 1794, p. 383, chemical AS MR. MATCHETT’S EXPERIMENTS chemical examination; it is not therefore furprifing, that the opinions of chemifts concerning it have been various. Chaptah adopts the opinion of Geoffroy, and calls it a kind of wax; * but Gren + and Fourcroy j regard it as a true refin. we Chemical Experiments on Lac, Its Habitudes with Solvents. Water extrats |. Water digefted upon powdered ftick lac becomes of a ane colour fiom deep crimfon colour, and takes up about 10 per cent. Seed : lac gives out no more than 23 or 3 per cent. and fhell lac only . # per cent. by fimilar treatment. Aleohol diffolves 2. Alcohol diffolves much of the lac, taking up refin in a the refin, which clear fylution if cold; but if heated, the folution is turbid and is a large part. : {carcely to be rendered tranfparent, either by repofe or fil- tration. The refin is obtained either by evaporating the folution or by pouring it into water acidulated with muriatic or acetic acid.. The refin which is thus precipitated may be feparated by the filter. It amounts to 67 or 68 per cent. in ftick lac, and to 88 in the feed lac. Shell lac contains 81 per cent. befides 10 per cent. which is defended from the fpirit, and cannot be fe- parated but by fubfequent operation. The refin is lefs brittle _ than other refin. Vegetable When the fhell lac was in fmall fragments only, thefe after gluten. the firft feparation of the refin, retained their figure and were more bulky, porous, and elaftic. Theelafticity was deftroyed by boiling water, and the matter itfelf proved to be of the na~ ture of vegetable gluten. Ether affeéts lac. © 3 ~ Sulphuric ether aéts lefs powerfully on Jac than alcohol very little. does. Itconfiderably foftens the lac; but produces little other effect. Sulphuric acid = 4, Concentrated fulphuric acid firft a€&s on the colouring ca. ? matter; but after a fhort digeftion on the fand bath, the fluid aéts on the whole mafs, and becomes firft reddith brown, and afterwards black, fulphureous acid gas being evolved, and the chief part of the lac being at length feparated in a flate refem- bling coal. * Chaptal’s Elements ; Englifh edition’ Vol. III. p. 387. + Principles of modern Chemiftry. Vol. T. p. $88. t Syfléme des Connoifances chimiques, ‘Tome V. p. 624. Nitric m AND OBSERVATIONS ON. LAG, 49 5. Nitric acid applied to. Jac emits nitrous gas at firft, and Nitric acid by : ; -, Management and caufes the lac to fwell much at the fame time that it converts it (6 diffolves it. into a deep opake yellow brittle fubflance, which by a fufficiency of nitric acid, and continuance of the digeftion for 48 hours, is diffolved. The folution however is turbid, and when poured The folution is into a large quantity of diftilled water, depofits fome yellow-garPis pe ifh floeculi, which, being colleted, are found to be a fort ofa wax. wax. The filtrated liquor is of abright golden yellow ; and, when The filterea faturated by ammonia, changes to orange colour, but does not folution contains yield any precipitate, nor any traces of oxalic or malic acid. * sas Signi! This yellow nitric folution is converted, by evaporation, into Its propertiesy a deep yellow fubftance, which burns like refin, but is foluble ** in boiling water. The alkalis and lime, being added to this aqueous folution, do not produce any precipitate, but the yellow colour is very confiderably deepened; and, by evaporation, an orange-coloured fubftance is obtained, which is ftill eafily foluble in water, and confifts of the deep yellow fubftance above-mentioned, com- bined with the alkali or lime. 6. Muriatic acid diffolves the colouring matter and gluten ee acid of lac; but its aétion on thefe is feeble, unlefs the refin has been Enlist eel, previoufly feparated. and gluten. 7. Acetous acid, in its e¢ffeéts, much refembles muriatic 7. Acetous acid. acid. _ 8. Stick lac, feed lac, and fhell lac, are partially diffolved by 8. Acetic acid acetic acid; and, if this be heated, a confiderable portion is *8 por the whole except the taken up. Wake _ The diffolved part confifts of the colouring extraét, of refin, and of gluten; the wax being the only ingredient which is in- foluble in this menftruum ; but a portion of the former fubftances, being enveloped by the wax, are protected from the ation of the acetic acid. » The acetic folution of lac becomes turbid when cold, and depofits part of the refin; a portion however remains in folu- tion, and may be precipitated by water ; after which, the liquor retains fome gluten and colouring extraét, which may be pre- eipitated by faturating the acid with an alkali, and by fubfequent boiling. ©. : +» For the reafons above ftated, it would be dificult to efe@ a complete folution of lac by means of acetic acid; buat this may */Voui X.—Janvary, 1805, kK neverthelefs 50 MR. HATCHETT’S EXPERIMENTS neverthelefs be advantageoufly employed in analytical opera- tions, when alternately ufed with alcohol. " Boracic acid 9. A faturated folution of boracic acid in water, diffolves the fcarcely aéts on colouring extraét; but, as the effeét does not furpafs that of ox water alone, we may conclude that lac is little, if at all, aed upon by boracic acid. Borax renders it 10. It has been already ftated, that fub-borate of foda or foluble in waters borax has a powerful effect on lace, fo as to render it foluble in water; and, as the preceding experiments prove that boracic acid alone fcarcely aéts upon lac, there is every reafon to be- lieve, that the excefs of foda prefent in borax is the ative fub- {tance ; and this conclufion will be confirmed, by the refults of fubfequent experiments made with the alkalis. Proportion, &c. In order to render lac (efpecially fhell lac).foluble in water, about 4 of borax is neceffary ; and this may be previoufly dif- folved in the water, or may be mixed and added together with the lac. 3 The beft proportion of water to that of lac is 18 or 20 to 1. So that 20 grs. of borax, and four ounces of water, are, upon an average, requifite-to diffolve 100 grs. of fhell lac; but more water may be occafionally added, to fupply the lofs caufed by evaporation during the digeftion, which fhould:be made nearly in a boiling heat. This folution of fhell lac is turbid, and of a reddifli-brown colour ; when confiderably diluted with water and agitated, a weak lather is formed ; it is decompofed by acids, and the lac is precipitated in yellow flocculi, which do not apparently differ from the lac originally employed. The folution is . The general properties of the folution fhew, that it is a oa faponaceous compound, which, being ufed as a varnifh or . vehicle for colours, becomes (when dry) difficultly foluble in water, although this was the liquid employed to form the folution. . A white thick {cum or cream colleéts on the furface of this liquid, after it has been fuffered to.remain tranquil for fome time, and is found to be produced by a fort of wax, which I fhall more particularly notice when the analyfes of the va- rieties of lac are defcribed ; but, in the prefent cafe, this wax appeared in fome degree to be converted into an almoft info. luble foap by the alkali of the borax, and may be regarded as the principal caufe of the turbidnefs of the folution. 11. The AND OBSERVATIONS ON LAC; 51 11. The lixivia of pure foda and of carbonate of foda com- Soda and its cars pletely diffolve the different kinds of lac; and thefe folutions ; ig Lehi exaéily refemble thofe formed by means of borax, Saline that they are deeper coloured. Rather lefs than 4 of carbonate of foda is required to . difflolve fhell lac; and this folution, when dried, is fooner affected by damp or water than the folution prepared by borax. 12, Lixivium of pure or cauftic potafh fpeedily diffolves the Alfo potath, varieties of lac, and forms faponaceous folutions, fimilar to that in which borax was employed, exclufive of the colour, which is deeper, and more approaching to purple, Lixivium of carbonate of potafh extracts a great part of the and its carbone colouring matter, but does not form fo complete a folution 7" of the entire fubftance of lac, as when pure potath is em- ployed. The above alkaline folutions, by repofe, afford the waxen foap which has been mentioned ; and acids, being added to thefe folutions, and to that formed by borax, precipitate the lac in a flocculent ftate, and of a yellow or buff colour, which precipitate, when melted, becomes fimilar to the lac ori- ginally employed. If however an alkaline folution of thell lac (prepared, for inftance, with foda) be gradually dropped into a fufficient quantity of muriatic acid diluted with an equal portion of water, and nearly heated to the boiling point, and if after boiling the whole for about one hour the coagulum be feparated, and the clear liquor be carefully faturated with foda, and again made to boil, a {mail quantity of a flocculent precipitate is obtained, which was found to be analogous to _ precipitated vegetable gluten, combined with fome of the co- " louring extract. 13.. Pure ammonia, and carbonate of ammonia, readily a€t Ammonia a&s upon the colouring matter of lac, but do not completely diffolye P44!!y- the entire fubftance. aie Analytical Experiments on Stick, Seed, and Shell Lac. Lac, placed on a red hot iron, contraéts, melts, fmokes Produéts of lac much, and leaves a fpongy coal. Slow diftillation carried to ie ae the red heat, gave from ftick lac, 1. Water flightly acid, 10; Stick lac, E £ 2. Thick 52 MR: HATCHETT’S EXPERIMENTS 2. Thick brown butyraceous oil, 59; 3. Spongy coal, 133 ; 4, A {mall portion of carbonate of ammonia, with carbonic acid, carbonated hidrogen, and hidrogen gas, by eftimate 174. Seed lace Seed lac, by the fame procefs, gave, 1. Acidulated water, 6; 2. Thick oil, 61; 3. Spongy a 7; 4. Mixed gas as before, but without miley 26. Shell lace Shell lac gave, 1. Acidulated water, 6; 2. Oil, ‘653 : 3. Spongy coal, He 4, Mixed gas, 214. The coal of this laft gave one grain of afhes after combuf- tion, which contained a muriate, probably of foda, There was alfo a little iron, and fome particles of fand, probably extraneous. — Analyfis of Stick Lack. Powdered ftick A, 200 grains of ftick lac, picked and reduced to powder, lac gaveared ore digefted in a pint anda half of boiling diftilled water colouring extra& 5 ; 5 to water. during 12 hours. The liquor was tranfparent, and of a beau- tiful deep red; this was decanted into another veffel; and the operation was repeated, with frefh portions of watei; until it ceafed to be tinged; the lac then appeared of a pale yel- lowifh-brown colour. The whole of the aqueous folution being evaporated, left a deep red fubftance, which poffefled the general properties of vegetable extraét, and weighed 18 grains, Alcohol then B. The dried lac was digefted for 48 hours, without heat, i upmuch jy eighteen ounces of alcohol; and the clear tin@ture being cautioufly decanted different portions of alcohol were added, and the digeftion was repeated, until the alcohol ceafed to produce any effeé. "The whole of the folutions in alcohol were then poured into diftilled water, which was heated, and an attempt was made to feparate the precipitated fubflance by filtration; but, as this did not fucceed, on account of the filter fpeedily becoming clogged, the whole was fubjeéted to gentle diftillation; by which, a brownifh-yellow refin was obtained, amounting in weightto 136 grains. C. The remainder of the lac was again digefted in boiling diftilied water; by whi ch, 2 grains of the colouring ‘extract were obtained, Diluted muriatic D, The refiduum was then digefted with one ounce of mu- ge ar: riatic acid diluted with two ounces of water, which, by boil- uiainder. in Z> AND OBSERVATIONS ON LAC. al <) ing, became of a bright pale red, but changed to purple, when faturated with a folution of carbonate of potafh, A flocculent precipitate was thus obtained, which poffefled the chara@ters of precipitated vegetable gluten combined with fome of the colouring extra@; this, when completely dried, weighed 11 grains. E. There now remained 25 grains, which evidently con- The refidue was fifted of a fort of wax, mixed with {mall parts of twigs and ¥** 2%¢ foreign matters other extraneous fubftances. A part of the wax was feparated by heat and preffure in a piece of linen; and another portion was feparated by di- geftion in olive oil, which aflumed the confiftency of an unguent, - The refiduum was then boiled with lixivium of potath, and became tinged with purple, in confequence of fome of the co- Jouring extraét which had not been diflolved by the preceding. operations. The undiffolved part, now confifting only of the extraneous vegetable and other fubftances, weighed 13 grains; fo that the wax, with a {mall portion of the colouring extract, may be eftimated at 12 grains. By the above procefs, 200 grains of ftick lac afforded, Component parts - Grs. of ftick lac. A } Colouring extraét “ = te \ = 1.20 B.° Retin - s - - #136 ~D. Vegetable gluten - . - risk oe { Wax, with a little colouring extract, about - 12 * | Extraneous fubftances - = we hs et 192. Analyfis of Seed Lac. F 200 grains of very pure feed lac were fubjeGtedto oper- Component parts ations very fimilar to thofe which have been defcribed, and ®*¢ # . afforded, < Grsz Colouring extract A - - 5 ‘Refin - - = & = 177 Vegetable gluten - - - 4, ax - 2 We - - 9 195. Analyfis 54 MR. HATCHETT’S EXPERIMENTS Analyfis of Shell Lac. Shell lac boiled A. 500 grains of this fubftance were firft treated with in water gave oiling diftilled water, as Bp one and yielded of little extract. extradt only 2.50 grains. Refidue gave B. The 497.50 grains which remained, were then digefted ee with different portions of cold alcohol, until this ceafed to produce any effeét; the refin which was thus feparated, amounted to 403.50 grains. C. As the fhell lac had not been reduced into powder, but only into {mall fragments, thefe were become white and elaftic, and, when dry, were brittle, and of a pale brown colour; the whole then weighed 94 grains. Muriatic acid D. Thefe 94 grains were digefted in diluted muriatic acid ; ae took up and the acid, being afterwards faturated with folution of car- easly bonate of potath, afforded a flocculent precipitate, (refembling that obtained from folutions of vegetable alee which, when . dry, weighed 5 grains. Acetic acid, by E, Alcohol aéted but feebly on the ‘cndoie ; it was there- dae 4 fore put intoa matrafs, with three ounces of acetic acid, and wax; the latter was fuffered to digeft without heat during fix days, the veffel een _being at times gently fhaken; the acid thus affumed a pale down by alcohol ; ; brown colour, and. was very turbid. The whole was then added to half a pint- of alcohol, and was digefted in 4 fand-bath ; by which a brownifh tin€ture was formed, and at the fame time a quantity of a whitifh flocculent fyb- fiance was depofited, which, being colleéted, well wafhed with alcohol on a filter, and dried, weighed 20 grains, This fubftance was white, light, and flaky, and, when rubbed by the nail, it became glofly, like wax ; it alfo eafily melted, was abforbed by heated paper, and, when placed on a coal or hot iron, emitted a fmoke, the odour of which very much refembled that of wax, or rather {fpermaceti. and then the F. The folution formed by acetic acid and alcohol, being refin by waters fltrated, was poured into diftilled water, which immediately became milky; and, being heated, the greater part of the refin which had been diffolved aflumed a curdy form, and was partly feparated by a filter, and partly by diftilling off the liquor; this portion of refin amounted to 51 grains, Carbonate of G. The filtrated liquor, from which this refin had been sea eat feparated, was faturated with a folution of carbonate of fia, potafh 3 AND OBSERVATIONS ON LAC, potafh ; and, being heated, a fecond precipitate of gluten was obtained, which, when well dried, weighed 9 grains. The 500 grains of fhell lac thus yielded, Grs. A. Extraée - - e 2.50 B. on bRefin ° - - - 454.50 e t Vegetable gluten - — 14. BE. Wax - = i = 20 491. The mode of analyfis adopted for the fhell lac, muft un- doubtedly appear lefs fimple than that which was employed for feed and ftick lac: but, upon the whole, it was attended with advantages; for the fhell lac being in fmall fragments, and not in the ftate of a powder, confiderably facilitated the decantation of the folution in alcohol from the refiduum; and although, in this laft, a portion of the refin was proteéted from the aétion of the alcohol, by being enveloped in the gluten and wax, yet, by the affiftance of acetic acid, the remainder of the refin, as well as the whole of the gluten, were diffolved ; the wax was obtained in a pure ftate; and a feparation of the refin from the gluten was afterwards eafily effeéted, by the method which has been defcribed. As therefore acetic acid is capable of diffolving refin, gluten, and many other of the vegetable principles, it certainly may be regarded as a very ufeful folvent, in the analyfis of bodies appertaining to the vegetable kingdom. From the refults of the preceding analyfes it appears, that the different kinds of Jac confift of four fubftances, namely, extract, refin, gluten, and wax, the feparate properties of which fhall now be more fully confidered, (The Conclufion in our next.) Galvanic 55 Component parts of fhell lac. Advantages of the procefs laf ufed. ON THE GALVANIC CHARGE, &c, XIIl. Galvanic Illuftrations and Remarks. By C. Weegee Esq: To Mr. NIC HOLSON. DEAR SIR, Glafgow, Dec. 9, 1804, On the galvanic Havine, during my galvanic tour, been occafionally in- charge, &c. formed that the attempt I have made in my Elements of Gal- vanifm, to explain the laws of galvanifm on the more perfeét and imperfect condu@ors, is not fo clear as it was my with to have rendered it; I fhall therefore deem myfelf much obliged by the infertion of the following obfervations in your valuable Journal. The power of .a galvanic apparatus, formed of plates not lefs than 23 inches in diameter, on animal fubftances, is di- reétly as the number of plates; on the more perfect conduc- tors, as metals, the power is as. you have at large ftated in your laft Journal. eo _ Let us fuppofe three galvanic plates: Fig. 1, (Plate Il.) of four inches; fig. 2, of fix inches; and fig. 3, of eight inches; An arrangement of thefe in the form of a galvanic’ trough, produces equal effeéts on animal fubflances, provided the number be equal, Animal fubftance is very little fuperior to water in its con- duéting power; and the experiments of Mr. Cavendifh have proved, that the conduéting powers of i iron are a million times greater than the conducting powers of water, A metal brought into contaét with another metal difpofed to part with a quantity of its compound ele@tricity, will ‘divide the quantity thus difengaged, becaule its capacity for receiving it is equal to that of the metal under the chemical a¢tion. Animal fubftance brought into contaét with a metal fimi- larly difpofed, will only receive a portion adequate to its ca- pacity ; and as this capacity is in the ratio of its conduéting powers, it will be nearly one million times inferior in capacity* to that of a metallic fubftance ; and will, therefore, abftraé only fo {mall a proportionate part of electricity to render its intenfily equal to that exifting in the galvanic plate, B ON. THE GALVANIC CHARGE, &c. 57 By eleétrical intenfity I underftand the quantum of eleétri- On the galvanic city multiplied by the refifting powers of the fubftance to ad- sig it Kal mitit, Let us fuppofe the plates 1, 2, and 3, difpofed- to give out eleétricity on every affignable point of their refpec+ tive furfaces. A finger applied at No. 1, Fig. 1, will abftra a certain portion of eleétricity from the points of metal direétly in contaét; a certain portion of eleétricity will immediately be determined from the fquares 2, 3, 4; 5, 6, &c. from every correfponding fquare on the furface of the plate, by that mo- tion which Volta has well termed the moto-eleétrical power : there is a phyfical refiftance'in the tran{miffion from thefe re- {peétive fquares to the firft touched by the finger, and the more remoie the greater the refiftance: at whatever points this phyfical refiftance fhall be equal to the capacity of the {ubftance employed, there all further tranfmiffion muft ceafe : this refiftance in plates of 2 inches in the fquare, appears, from experiment, fully adequate to the conftant fupply of fo imperfed&t a conduétor as animal fubftances, and therefore any increafe of fize in the furface of the plate, will-produce no additional éffeéts. “When a certain quantity is thus abftraéted from the pair of plates at the extremes of the battery, in dire@ contaé with. the fingers, thefe plates and the interpofed fluid in the cells, only aét as condudiors to the next pair, and fo on; as the ve- locity of difcharges of each fucceflive pair is fo infinitely greater than the time required for the chemical ation, is the reafon why the effe€ts we experience are increafed in proportion to . ithe numbers: if we were to fuppofe that the time required for the fuccefflive difcharge of 50 pair of plates, fhould be pre- cifely equal to the time required for the chemical aétion, we fhould derive no increafe of power by an increafe of number, which is contrary to experience. Ihave a battery formed of 600 plates, each plate only ex- pofing half a fquare inch in furface: To experience equal effeéts from this arrangement, I am obliged to paufe three or four minutes between each contaét; an interval of time no ways requifite in larger plates. When fuch fuperior condu€tors as metals are employed, the phyfical refiftance of tranfmiffion from one part of the plate to another, bearing no proportion with the capacity of inact the 58 Glafs is not a cryftallization. Vitreous fufion diftin& from that of falts. DEVITRIFICATION OF GLASS. the metal, every affignable point of the galvanic plate is effi- cient at the fame time, therefore the intenfity will be as the. furface, and the powers as the fquares of the intenfities. Iam, Dear Sir, Your’s, refpectfully, C. WILKINSON. No. 19, Soho Square. XIV. On the Devitrification of Glafs and the Phenomena which hap- pen during its Cryftallization. By DarticuEs. * Some philofophers have confidered glafs as a chryftalliza- tion; and this opinion appears natural on confidering the tranf- parence of glafs or of cryftal, from the latter of which the term for defignating the regular and fpontaneous arrangement of the particles of bodies has been taken. But on clofer re- fle@tion, ‘this notion is found to be erroneous. In fat glafs never affeéts a cryftalline figure, either in its furface or its frac- ture; it never prefents chryftals of its own proper fubftance, fuch as are feen in metals flowly congealed; and whenever cryftals are formed in the mafs of glafs, they are foreign to the part which ftill continues vitrified; they may beconfidered as a ftep the reverfe from that of vitrification, as I fhall how in the courfe of the prefent paper, On the firft explanation of vitreous fufion, I muft diftinguith and feparate it from the fufion of certain other bodies which flow without addition in the heat of our furnaces, fuch as bo- rax, the phofphoric acid and others. In thefe bodies the con- * Tranflated from the Journal de Phyfique, LIX. 5, The author of this memoir, who is proprietor of the glafs-works and other eftablifhments of Voneche (Sambre-et Meufe) has under- taken to draw up for the French National Inftitute a treatife on the art of glafs-making, to ferve as a continuation to the arts and trades of the Academy: The firft part is in readinefs to appear, many of the plates being ready. The fecond part relates to the ufes of glafs inthe arts. And the third part confifts of detached memoirs upon the phyfical and chemical properties of glafs. The prefent differta- tion is extracted from one of thofe memoirs.—J. C. Delametherie. denfed a DEVITRIFICATION OF GLASS. 59 denfed heat foftens and renders them fluid, and they more or lefs continue to exhibit, when cooled, the tran{parency and fome other of the well known phyfical properties of glafs. But in the examination and defcription of that fufion to It isa folution which vitreous compounds are fubjeéted in order to fit them for PY heat the purpofes of life, it is neceflary to obferve that the effeé arifes from two phenomena. It is not fimply the refult of ac- cumulated heat, but it is jointly produced by the affinities of the fubftances which enter into the mixture. Thefe fubftances which tend to combine and mutually to penetrate each other, att according to the Jaws of their affinities as foon as ever the temperature is fufficiently elevated. Thus it is that a mixture of feveral earths becomes fufed at a temperature which could not have rendered any one of. them fluid. The common vitrification is therefore the refult of a com- Nature of the bination effeéted at an elevated temperature between different diet = and heterogenous fubftances; and the produét is a compound perfectly homogenous more or lefs tranfparent, elaftic, and breaking in a peculiar manner, from which the term vitreous fra@ture is derived. This body is a remarkably bad condu€tor of heat and of eleétricity; it is capable of becoming foft at a temperature inferior to that at which it was fufed, fo that it may be rendered pafty, duétile, &c. The phenomenon during which all thefe properties difap. Devitrification. pear is what I have called devitrification; an expreflion which may at firft feem extraordinary, but which the faéts will fhew to be perfeétly accurate. Several philofophers have before noticed this effeét; fome It is the confe~ quence of cry _ have even made obfervations upon it, and have noted various @)j;zationz - compofed of different earths, as bottle glafs is in general, circumftances fcarcely conneéted with each other; but I am not aware that any one has yet publifhed a feries of refearches proper to explain the effects, fo as to thew that it is one of the known properties of all natural bodies, being in fa@ nothing more than the produé of a cryftallization. Reaumor firft obferved that a glafs, more efpecially if it be The porcelain of Reaumur: ; ‘may be decompofed, and lofe its tranfparency and other vi- treous properties. Fully occupied in his refearches upon porcelains, he was defirous of applying this difcovery to the fabrication of potteries, and attributed the phenomenon to the fabftances in which he had cemented his glafs. The fact was 2 denomiy m 60 DEVITRIFICATION OF GLASS. denominated the cementation of glafs, and the product was called Reaumur’s porcelain: no incident could be more effeat- ually calculated to retard the true developement of the faét than {uch a denomination of this kind. Repetitions of » The labours of Bofe d’Antic upon the fame objeé were the procefs by alfo dire€led to no other purpofe than that.of obtaining a good pias, ‘a pottery by this means, and of afcertaining what cements were the beft calculated to give new properties to this body. Thus it was that by calling the procefs by the name of cementation, which depended in no refpe@ upon what was added as the ce- ment, others were mifled, who were induced to follow the courfe of experiments already began. The natural confe- quence was, that fcience gained nothing refpeéting this procefs fince the time of Reaumur. ° Many have fince attempted the cementation of glafs without perceiving any new refult in the’ produ. Obfervation of | Several perfons have fince admitted the property in glafs of cryftals in glafts affording eryftals; but thefe remarks being more efpecially made by artifts, placed by their fituation at the head of glafs- - works, have not afforded the {cientific confequences which might have been deduced from them, Thedire&tors of a great eftablifhment have feldom time to dwell upon the contempla- tion of {mall effeéts; they are obliged to attend to t60 many things at the fame time. Thefe remarks, though curious in themfelves, remained without connection; and no ohe thought or ventured to publith that the eryftallization of glafs, and ce- mentation by the procefs of Reaumur are abfolutely one and the fame thing. . Experiments of | Sir James Hall,* in his valuable experiments upon whin- Sir James Hall ftone and lava, publifhed in the 14th volume of the Biblio- ree theque Britannique, afcertained the property of thefe ftones to become fufed into glafs, and to return to the ftony ftate, ac- cording to the circumftances. He did not pure — He called this laft fa€t a devitrification. He faw that it was fag Nis a the effect of a precipitation, and explained it in amanner that artificial pro- was highly fatisfa€tory and true; but being too much occupied in ace deducing from this fat arguments in favour of the voleanic geo- logy, he negleéted purfuing the interefting philofophical confe- guences to which.the phenomenon pointed the way. This is * Firft in the Edinburgh Tranfastions, and afterwards in our Journal. N. A, the DEVITRIFICATION OF GLASS, 6] the tafk I have undertaken, andiin the prefent memoir on de- vitrification, I thall give the refults of my firft experiments. As my fituation gives me the ufe of a fire of extreme violence and continued for years together, it may have been in my power to make obfervations not within the reach of every one. The fafts I thall report do partly explain themfelves; they are the _refult of laws to which all bodies are fubje&ted. All the merit of the obfervation confifts in having feen them in fubftances, and on occafions where it was not known that thefe laws do take place. The bottom of the furnaces for fonding or fufing the glafs Itis very re _ ans ; markably feen in _ufually prefents large cavities excavated by the aétion of the giafs furnaces. fire, and of the corrofive fubftances which often flow out of the melting pots. Thefe cavities are filled with a kind of glafs _ called picadil, which is compofed of afhes which become vi- trified, ftones of the furnace which become fuled, and more particularly of glafs which falls from the pots. Care is taken to remove this at each font or making of glafs. When the fur- nace is nearly worn out, the cavities having become large, can- not be entirely cleanfed, but fome of the picadil remains. When tlie furnace is extinguifhed, this picadil undergoes an extremely flow cooling, becaufe it is furrounded with mafonry of feveral cubic fathoms, which is itfelf penetrated with heat that has continued for upwards of a year. I have always re- Cryftals in glafs. marked that it was in the glafs of thefe bottoms of the furnace that I found cryftallizations through the mafs of glafs, the reft of which was very tranfparent and pure. Thefe cryftalliza- _ tions, which were always confiderably regular and numerous, excifed my cnriofity, as they had done that of other glafs- makers before me. I colleéted many fpecimens, taking care. to chufe thofe which appeared the moft curious, and prefented the moftextrordinary characters. Soon afterwards, from comparing the pieces themfelves, and Examination of! the circumftances under which they had been produced; and ‘he fs by the combinations of remarks, trials, and experiments to imitate thefe cryftallizations at pleafure, I at laft fucceeded in diftinguifhing various claffes, all of which are produced by the nature of the different circumftances which accompany the formation of the glafs. I fhall give a rapid outline of thefe, without entering into any remarks on the devitrification which almoft conftantly takes place in the feoria of forge furnaces. This 62 The more come pounded the ; glafs the more eafily DEVITRKIFICATION OF GLASSé This laft fact muft have prefented itfelf to every one, arid witl without difficulty be referred to the obfervations I hall make. The firft remark which offers itfelf is, that the more com- pounded the nature of the glafs, the more eafily and readily it it lofes its vitre- Will become devitrified: but in the fame manner as a folvent Qus nature. Bottle glafs. Experiment in the {ma'l way. Particular exa- mination of the changes in glafs by flow cooking. Inftance of the effect taking place in a short time, loaded with a great number of faline fubftances of different kinds, fuffers them to cryftallize more confufedly, fo likewife it is found that thefe glaffes do not prefent the moft regular cry- fiallizations. A precipitation takes place through the whole of the mafs; each of the component parts obeys the laws of affinities; at the fame time the tranfparency {peedily difappears, and we no longer fee a piece of glafs, but a ftone. Through _ this contufed mafs it is neverthelefs impofible not to obferve the rudiments of cryftals. Such is the manner in which bottle glafs comports itfelf in itsdevitrific ation. Thefe approach very much to the ftate of mere earthy glaffes, having very little falt in their compofition. Every one has an opportunity of keeping a common bottle of black glafs in a fire long continued, and capable of foften- ing its pafte; it {peedily changes colour, becomes grey, and aflumes the appearance of ftone ware. In this manner we form the pottery of Reaumur, but without any procefs relem- bling cryftallization. | But inftead of obferving the phenomenon in fo fmall a mals, if we examine the bottoms of the glafs furnaces in which thefe bottles are fufed, we find that the glafs is abfolutely devitrified, and has aflumed an appearance fo completely ftony, that the molt experienced eye can fcarcely diftinguifh the bricks of the furnace from the part which has been glafs, It is only by fol- lowing the courle of the devitrification in pieces lefs advanced, that we fucceed in diftinguifhing the glafs in a granulated ftone, which has rather the appearance of coarfe pottery, or a ftrongly baked clay. , It often happens that the flow coaling of an hour or two iS fufficient to produce the entire devitrification of bottle glafs, I have pieces of eight centimetres (2} inches) thick, which I obtained at the glafs works of Mr. Saget, of La Gare. One of the pots was taken out of the furnace to be replaced; the glafs remaining at the bottom of this pot was preferved from cooling during the time the pot itfelf acquired the common temperature, and by this means the nature of the glafs was entirely ad DEVITRIFICATION OF GLASS. 63 entirely changed. It no longer exhibits the tranfparency, but is a mafs of cryftals, compofed of fmall needles, converging towards common centers. It has no longer the i iphie i of glafs. This faét fhews with what facility bottle glafs is devitrified, and always without the leaft appearance of cementation. The infinite variety of fubftances which make up the compofition of bottle glafs, greatly modifies the phenomena which take _ place during their devitrification, and muft, no doubt, influ- _ ence the form of the cryftals; but my opportunities of obferv- __ ing this kind of glafs have not been numerous. Pafling therefore to glaffes lefs earthy and compofed of a lefs Greenith glats of number of fubftances, when I make the fame examination of Sid i. the bottoms of the furnaces of glafs for windows called glaffes ded pyrene of Alfatia, or half clear glaffes, into which is put a greater ae fie ‘portion of pure fand and of alkali, I obferve nearly the fame p),34, et phenomenon; but as they are lefs fudden, they are more eafy to diftinguifh and to feparate. At the firft inftant, and in the _ mafles where the devitrification commences, we feem to ob- ferve a {mall portion of blue colour diffufed through a greenifhi liquid. | A very fingular fa€t here prefents itfelf, which I fhall here ~enly point out, with the intention of more fully examining it hereafter. This greenith glafs mixed with blue, appears, in fact, to become of an obfcure blue when confidered by re- fleéted light; but if placed fo as to tran{mit the light, it always. appears greenifh; the blue being reflected and the _ green refraéted, each fingly. By continuing to obferve the devitrification of this glafs, Second change, it is foon perceived that the blue precipitation is followed by¢ Sue white opae another more abundant, which affords a dirty white, andis — very diftiné& from the former. The colour of this glafs becomes _deeper and deeper, and at length it refembles grey horn. In thefe different bacwanne: the pafte of the glafs appears Third change, conftantly to‘remain, diftinguifhable in its polith, its fra@ture, A 2 al ga and all its other properties, except its tranfparency. But in the midft of this patte refembling horn, very diftin& cryftalli- zations are formed, confifting of nodules compofed of {mall needles, all converging towards the center. In this ftate it is no longer glafs, but a cryftal poffefling all the phyfical pro- perties of mineral fubftances left to themfelves, A An t ° G4 DEVITRIFICATION OF GLASS. An exaé analyfis made of a certain number of thefe cryftale carefully detached from the mafs, might indicate their nature and throw light on their formation. It often Spenait that thefe cryftallized nodules are enve- loped in a cruft which feems foreign to their nature, and may be compared to the cruft which envelopes flints in the middle of the chalk-banks in which they feem to grow. Speedy refrige- = Thefe are the feries of phenomenon attending the devitrifica- og basa tion of greenifh.glafs when it happens flowly ; but if the effeé non, is too rapidly produced, the appearances refemble thofe ob- ferved in the deyvitrification of boitle glafs. The window glafs here fpoken of, is of that kind which contains very little of earthy matter, except wood afhes. It muft admit of many variations according to the differences in its compofition. Clear and imple White or colourlefs glaffes are very difficultly cryftallized sly deviwiseds or devitrified. When they are well made, we may affirm that a long continued heat does not change them ; but for this pro- perty it is neceflary that they fhould be compofed merely of filex, with the precife quantity of flux for its faturation, In’ this cafe, a very long continued fire will no otherwife change them than by rendering them more yellow and hard. ~ (The Conclufion in our next.) Ee ADVERTISEMENT. Various articles of Philofophical News, Accounts of Booksy and other fuljects, have necefarily been poftponed this month, on account of illnefs with which the Editor has been affliéted. The Jame caufe has alfo unfortunately prevented his Draught/- man from completing fome Defi igns, which would elfe have ap- peared, Mr, Ezekiel Walker has been prevented, by fevere indifpofition, from anfwering the paper of C. L. in our laft, “pon the Horizon tal Moon. A note has alfo been received from C. L. in bie heel he begs leave to notice, that the 1 large lens mentioned in his experiment I. has a clear aperture of 6, 6, 1 chee in its vrame. and was fo ufed in that experiment, Philos. Tournah VotX PUL p. 64. Cgyftian é y 5 Y OF Louphey 7, hy, Saige 7 / ” (Z = ——— Mutlow ScRufseld Co” eee seks tedie J wor ns w fae be et fs Lt ees See ae Peta Mra A § ory A JOURNAL NATURAL PHILOSOPHY, CHEMISTRY, AND PEPE ARES: FEBRUAR yi Wee. AUR IbC 35; if. Axperi iments und Remarks on the Augmentation of Sounds. Ina Letter from Mr. Joun Goueu. To Mr. NICHOLSON. SIR, A FACT is mentioned in a former communication of mine Sounds heard to your Journal (od EL 41) which sgh ae your J urna (o€tavo, vol. +P ich proves, that . ended fur- a ftroke given to an extenfive vibrating furface by a flender face. rod, produces a found poffefling a high degree of force: from this it follows, that the range of a found may be extended by _ enlarging the vibrating furface, while the magnitude of the impulfe remains.the fame. The preceding maxim is of great ufe in acouftics; but as the truth of this propofition refts at prefent on the authority of a local obfervation, it may not appear fuperfluous to give a few eafy experiments in confir- mation of the faét. Experiment I.—My firft attempt endeavoured to prove, that Exp. 1. The when a found ceafes to be audible from remotenefs, the en- >&ti?g of a A - - : : : ? ~_. _ watch audible at Jargement of the vibrating furface will again render it diftinét a greater diftance at the fame diftance.. For this purpofe, a watch was ful- when in contaét with a metallic pended, on acalm day, from the branch of a tree, about 54 plate, _ feet from the ground, The clicking of it barely reached my Vou. X.——-FEBRUARY, 1805. F ear, 66 ON THE AUGMENTATION OF SOUNDS. ear, in thofe intervals of filence which were not difturbed by foreign founds, at the diftance of 52 yards; but when I re- moved half a yard farther, the ftrokes of the balance were no longer heard. A circular plate of rolled iron, one foot in diameter, was then brought into contaét with the part of the watch fartheft from me, the pofition of it being fuch as to prefent the plane of the circle to my ear. This circumftance increafed the range of the found; for every ftroke of the in- ftrument was diftin€lly perceived at the diftance of four yards, when the filence of the place remained undifturbed by other caufes. The refult of this experiment is too obvious to need a comment: and [| have only to add, that when the trial is made within doors, the range of the clicking is greatly in- creafed; becaufe the primary found receives:an acceflion of — force from a number of its own pulfes, which are reflected to | the ear by the furniture and walls. Exp. 2. The Experiment I/.—J proceeded, in the next place, to examine plate givesa the effeéts produced on the auditory organs by the vibrations confiderable 2 e i found itfelf. | communicated to an elaftic furface by a watch; the immedi- ate found of which was {mothered by art. For this purpofe, a watch was placed upon a cufhion, under an inverted por- celain cup, which was wrapped externally in feveral folds of flannel. The inftrument was heard with difficulty at the diftance of one foot in this fort of confinement; but when I placed the muffler with the watch under it, upon a fquare mahogany table four feet broad, the clicking noife imparted by it to the top of the table, reached the ear very diftin@ly at the diftance of four yards. The fame watch, covered in like manner upon the iron plate mentioned above, reached my ear at the diftance of 22 feet. The apparatus ftood in this trial upon a round oak table, 24 inches in diameter. ‘Theenlargement The preceding faét proves indifputably, that the fecondary of the furface vibrations of an elaftic furface aétually affeét the ear, in thofe augments the . Sand; cafes wherein the pulfes never reach the perfon of the hearers,. which proceed from the part that is exclufively confidered as the feat of found; in other words it proves, that the caufe of a. found is not confined to the obftacle receiving the primary impulfe, but that it is propagated from the point of impact through the contiguous bodies. The firft experiment alfo fhews, that the enlargement of the vibrating furface encreafes the force, which a given ftroke exerts upon an ear placed at ) A a given ON THE AUGMENTATION OF SOUNDS. 67 a given diftance; confequently the increafed force thus im- parted to a found, muft be afcribed to the co-operation of the vibrations communicated in the firft experiment to the plate of iron; for by uniting with thofe of the watch, they evidently augmented the power of the latter inftrument. A rational theory of the forces of founds may be formed, Pile le by help of the preceding obfervations, in the following manner : paaapehed! Firft, Suppofe the plane ABC (Plate /V.) to be one of the fur- the psig had faces of an elaftic body, and let it receive an impulfe at the ek point O; then O will recede from the ftroke in a right line body. perpendicular to ABC, drawing after it all the contiguous particles, which, in their turn, will change the place of the next circle of particles. In this manner a circular dent OMEQT F will be formed; the center of which O will be below-the plane ABC; M, the higheft part of the margin, will be above it; and the extreme circle EQ TF, ‘bounding the whole, will liein the plane. Second, Thus will a circu- lar {well be formed on the plane, refembling the circular wave produced by a ftone dropped into water. A feries of thefe {wells will follow the firft, each of which, in fucceffion, will lie more remote from the center O than its predeceffor. Third, The colleétive force of each fwell is equal to that of the firft impulfe ; and it is diftributed over the furface of a ring, having O for its center and O E forits breadth; 2, e. all the rings are of equal breadths, but unequal diameter. Fourth, The effeét of the ftroke is thus progreflively propagated from O to the more diftant parts of the plane ABC, with an uniform velo- city. Fifth, Let P be the place of the ear in the right line OP, perpendicular to ABC; alfo let GHIJK be any fwell in the fame plane; then will the effect of that {well be carried to the ear, in the conical fhell OGIJK P; and the impulfe imparted to the auditory organs, through the medium of this fhell, will be greateft when the diameter of the ring OT is leafty and the contrary. Sixth, If ABC be a concave {phe- rical furface, having P for its center, all the fwells will fuc- ceffively exert equal forces on the ear at P. Seventh, If OP be put equal to a, and f meafure the force of a ftroke at the diftance 1; then let v equal the velocity with which this force is propagated from O over the f{pherical furface, and J the breadth of the rings covered by the {wells, the force im- preffed on the ear at P in a given interval of time, is equal 2 to 68 ON THE AUGMENTATION OF SOUNDS. to 22, Eighth, Though time is infinitely divifible in a ma- a thematical fenfe, M. Euler has fhewn*,: that the ear con- ceives it to confift of indivifible or elementary particles ; con- fequently all the forces which arrive at P during one of thefe elementary intervals, make a fingle indivifible impreflion on an ear placed at that point; becaufe this organ cannot take ccgnizance of a fmaller particle of time; therefore the force of a found, produced at the center of a hollow fphere by the undulations of its furface, is truly denoted by the expref- ’ 3) 3 ‘ y A fion . Ninth, In general, the force of a found, at any in- a ftant of its duration, is equal to the fum of the forces exerted by thofe pulfes, which ftrike the ear in the elementary inter- val; Confequently, if the diftance between the hearer and the founding body be fuch, that lines drawn from his ear to every point of the vibrating furface, may be confidered as equal, the force of the found will be exprefled by at Tenth, a To thew the nature of this theorem by an example; fuppofe a bell A, the diameter of whofe mouth = 14, to be an oétave below a bell B, the diameter of which = 1: alfo let A be heard twice as far as B, when each receives an equal ftroke ; the ratio of the breadths of the {wells in A and B is required. Let V, v, be the velocities of the fwells in A and B, Z,J, the breadths of thefe {wells ; alfo let 2 and 1 be their refpetive ¥ a ranges: then fince f is given, —- —=-—, by the theorem; The principle extended to voices and other founds, Cy aw hence, as’: 4v::2:1. Now the femi-circumferences of A and B are in the ratio of 14 to 1; ‘but while the vibrations pals. over half the circumference of A, they pafs and repafs over the fame gi of B; therefore, as 7: v:: 14:2: hence alioeaswhie ws: te. OQ. Fi 4, Should the weet explained above be admitted, the fol- lowing conclufion muft alfo be received as a neceflary confe- quence of it: the voices of animals, as well as the notes of mufical inftruments, and the reports produced by blows given to lefs elaftic fabftances, derive no inconfiderable portion of their refpe@ive forces from the vibrations of parts which are * Tentamen de Mus, Cap, J. Sec. 13. , not ON THE AUGMENTATION OF “:OUNDS., 69 not dire@tly concerned in the produ@ion of the primary found. This opinion appears to be countenanced by an experiment, which I have repeated at’ different times under various forms, and of which the following is the fubftance: If a wire be ftretched by two pins fixed into a bad conduétor, fuch as a block of ftone, the found produced by it is much weaker than that of an equal wire fimilarly ftretched upon a “board, which is a better conductor. In like manner, if a circular piece of - wood be ftruck by‘a leaden ball conflantly falling from the fame height, the report will be heard at a greater diftance, when the wood is placed upon a good conduétor of found, than when it refts upon a bad one. Thefe faéts create a high degree of probability, that the leading maxim of this eflay is applicable to founds of every defcription, embracing {uch as are continuous, as well as thofe of a momentary dura- tion. Dr. Matthew Young’s Enquiry into the Phenomena of Similar theory Sounds has fallen into my hands fince the foregoing remarks al were committed to paper, and a partial perufal of the work has convinced me, that the prefent theory has not all the claim to originality-which I once fuppofed to be due to it. The juftice and neceffity of the preceding obfervation -will appear from the Doétor’s two theories of the fpeaking-trumpet and echoes; in both of which he has made ufe of my leading principle with fuccefs. The maxim, however, has been ex- “tended to a greater number of cafes by thefe obfervations ; befides which, an attempt has been made to demonfirate the truth of it by experiment, and it is on the two circumftances here flated that the merits of the prefent letter muft teft; for .~ Iam far from defiring to rob the celebrated author of the enquiry of the honour due to his fagacity. JOHN GOUGH. Middlefhaw, Jan. 4, 1805, Observations 70 DEGREES OF FACILITY WITH WHICH BODIES II. Obfervations on the different Degrees of Facility with which Mages of the fame Maiteriql admit of Changes in their Tem- perature; with Applications of the Fucts to the Conjfiruction of Pendulums, and Speculations upon various new Forms of pen- dulous Regulators of Time. Ina Letter from J. WHITLEY Boswe.t, L/y. To Mr. NICHOLSON. SIR, 7 Compound pen- ‘Tue fatisfaétory communication on an ingenious improve- dulums. ment of the compound pendulum, in your Journal for De- cember, has reminded me of fome ideas which occurred to me on fimilar fubjeéts. In hopes that they may be of fome ufe in a matter fo interefting in itfelf, and fo important in its tae cation, I fend them for your opinion. A very material point feems to have been omitted in all the confiderations | have met with on the expanfion of bodies by heat ; pyrometrical experiments being direGted to that merely of different fubftances of the fame fize, but none being made on bodies differing in bulk. Bodies aremore “hough various bodies differ in their degree of expanfion or lefs fpeedily by heat according to their materials, yet all are fubje@ to eee oertaln laws on this point, depending on their dimenfions ; their dimenfions for as bodies receive or communicate heat by their furfaces, and fips, and retain it in proportion to their bulk, it follows, that their mutability of temperature muft depend on the ratio of their folid contents to their furfaces ; and that the greater the fur- face in proportion to the bulk, the more readily will a body change its temperature; and on the contrary, the greater the bulk in proportion to the furface, the lefs will it be affected by the fluétuating heat of the furrounding medium. Deduétion of the Lhe proportion which the furfaces of bodies bear to their effects. bulk may be varied, either by altering their fhape or changing their fize. In the firft refpe@ it is {ufficient to note, that the flatter and longer any body is, the greater will be its furface in proportion to its mafs of matter, and vice ver/w: the dif- ference caufed by the variation of bulk can be more eafily. caleiataed, as in bodies of fimilar figures their furfaces are exactly ADMIT OF CHANGES IN THEIR TEMPERATURE. vr exactly as the {quares, and their folid contents as the cubes of their diameters. From this, and what has been already pre- mifed, it will follow, that in bodies of different fizes, fimilarly fhaped, and of the fame fubftance, the capacity for heat will be as the cubes, and the mutability of temperature as the fquares of their diameters or fides; and that, therefore, the degree of the tendency of thofe bodies to maintain an equality of temperature, may be eftimated as their folid contents minus the relative value of their furfaces: Bodies whofe fhapes are diffimilar, will in fome degree be fubje& to the fame rule; but it is not material to the prefent fubje& to take them farther into confideration. The following table of the proportion of four cubes in the Table of the ra- above refpeéts, whofe fides are reciprocally as 1, 2, 3, and ie da will exemplify what has been above afferted, and thew how greatly the retention of temperature of bodies is increafed by adding to their bulk. Bide.|-Surface.| co" e°.| Bulk. |e tho lof Heat of Heatas for Heat.| .- eftimated. Feet. {Square Feet. Cubic Ft. Ae itiead Ga a ] ] 1 1 B Z 243: 4 i 8 8 4 es ot 2. 9 9 27 27 18 D | 4 IGn: VG 16 o4 64 48 From thefe confiderations the following inferences may be Inferences, drawn: If, That the greater the bulk of any body, the lefs will be its mutability of temperature in proportion, and of courfe the lefs will it alter its degree of expanfion: 2d, That a large globe in the firft place, or a cylinder, whofe height was equal to its diameter, in the next place, or in the third place a large cube, would have its dimenfions very little changed by the flu€tuations of atmofpherical temperature. To apply thefe principles to the regulation of horological Application of movements may appear difficult, as the firft idea that would Lae tg occur is, that it would be neceflary to put thofe large bodies in motion for this purpofe; but this is by no means needful, and it may be effeGually performed by conftruéting and fixing up a pendulum in fuch a manner, that its variations in length fhall be correéted by, and depend on, thofe of the large body. There 72 Pendulums of Crofthwaite and Pine. Their miftake. Ufe of a large block of ftone for fixing a pen- dulum and clock, DEGREES OF FACILITY WITH WHICH BODIES There is no need of much inveftigation to difcover the mode of doing this; as either the pendulum invented by Mr. Crofthwaite, of Dublin, or that contrived by Mr. Pine, will fully anfwer this purpofe, though they will by no means per- form that for which they were intended,---of effeéting a com- penfation of themfelves, in the manner of the gridiron pen- dulum. The error of thefe gentlemen, in this refpe@t, is very fully pointed out in a paper figned A. B, publithed in the feventh Volume of the Repertory of Arts, which would have been much more creditable to its author, had he not triumphed fo much in his fuperior penetration on the occafion, which has led him to forget himfelf fo far as to defcend to the illiberality of national refleétion on the part of Mr. Crofthwaite: for which reafon I own I am happy to have it in my power to give thefe gentlemen the fatisfaétion of feeing an error pointed out in his paper in return; whichis, where he afferts that a fmall rod of mahogany muft have the fame contraction and dilation, from change of heat, as a jolid plank of the fame wood, or words to that effe€t, the fallacy of which opinion appears from what has been here laid down: It would be eafy to dif tinguifh this philofophy by an appellation of the fame flamp as that which A. B, has beftowed on Mr. Crofthwaite’s in- vention, and the more unfortunately for his infinuation on this occafion, as the Irifh method happens to be the beft of the two; for Mr. Crofthwaite fupported his pendulum by a - folid wall, which would be much lefs affeéted by change of heat in the air than the back of the clock-cafe to which Mr. Pine attached his. The beft method of applying the foregoing fas to the regulation of clocks appears to me to be, to procure a large cylinder, or o€tagonal prifm, of ftone, the diameter of whofe bafe is equal to its height, and exceeds the length of the pen- dulum by fome inches at leaft, and as much larger as it could be got the better: one of a cubic fhape would alfo do, if its mafs of matter exceeded that which could be got of the other forms; for this purpofe granite {tone feems preferable, and in the next place Portland ftone, as they can be eafily had in large blocks ; “but it is probable that {tones which grow damp ° in moift weather would not be fo proper for this purpofe.. To this block of {tone a pendulam fhould be attached with a fingle compenfating ~ ADMIT OF CHANGES IN THEIR TEMPERATURE. he compenfating rod added to it, in the fame manner as that con- ftru€ted by Mr. Crofthwaite or by Mr. Pine: the clock itfelf fhould alfo be faftened to the ftone, particularly if Mr. Crofthwaite’s pendulum is ufed. The block of ftone may be farther fecured from change of Defence of the temperature, by being furrounded on every fide by brick-work serenatet: ’ change of tem~ except where the pendulum and clock are fixed, and having perature, &c. dry faw-duft rammed in between it and the brick-work. {t is probable that a block thus fitted up, would vary little from changes in the heat of the air; and in thofe fituations where large blocks of ftone are found* naturally, this might be done at a fmall expence: where a large block of ftone could not be procured, a piece of dry ftraight-grained red deal balk, or folid mahogany, might be ufed to good effe@, if well painted, and inclofed as before directed : and for common ufe, it is probable that a large glafs tube, filled with femen lycopodii, if to be had, or finé dry faw-duft, well clofed at either end, and covered with oiled filk, would form a pendu- lum-rod little affeGted by heat or cold; but if metal is pre- ferred, then a tube of metal, fitted up as laft dire@ted, would be preferable_to the {mall wires now ufed for this purpofe. The advantages to be expeéted from the principal method Advantages. above-mentioned, of fitting up pendulums, is, that it affords an unlimited mode of approximation to perfe@ compenfation ; and that, as it requires no great refinement of workmanthip in its conftruétion, it can be ufed in many fituations where it - would be impoflible to have a tubular compenfating, or com- mon gridiron pendulum made; which, notwithftanding the late improvements, are extremely dificult to conftru€t with accuracy, as may be feen in the paper publifhed in your Jour- nal for December laft, where many of the impediments to their perfeGtion are pointed out, and more ftiil remain to be no- ticed, of which the following deferve fome’attention, i The metals of which gridiron pendulums are compofed, Imperfedions of are both of them mixed metals, and of courfe every different (pean pen- parcel of them made, muft vary in fome degree in the rela- aM aged ape tive quantities of their component ingredients, and from thence i and not in their degree of expanfion by heat. It may appear ftrange eee to call fteel a mixed metal; but when it is confidered that charcoal forms a confiderable part of it, the juftice of efti- mating it as fuch will be evident; and in this metal the pro- portion $$$ 74 ON PENDULUMS,. portion of charcoal in different parcels of it, is much more various than that of zinc is in brafs: perhaps, for this reafon, it might be better to ufe fome of the fimple metals in the place of thefe, in their conftruétion. ( Difficulty of ad- Another difficulty in forming thefe pendulums with accu- — Bea racy, arifes from the want of a good method of proving them: The adjuftment by the going of a clock is fhewn to be imper- fect in the paper on the tubular pendulum, and that propofed | in its place, the ufe of the pyrometer, is equally defective, for the following reafons : Defects alledged Pyrometers are unfit for meafuring the effets of the heat > pyrometerse and cold of the atmofphere on any fubftance, becaufe their own machinery, and particularly the part fupporting the fub. ftance under trial, is liable to be affeéted by the fame caufes : and in this cafe the index will fhew the fum of the alteration of the fubftance, the part of the apparatus between its two extremities, and the machinery of the pyrometer, inftead of that of the fubftance alone: and in applying artificial heat to ihe matter under trial, itis extremely difficult to communicate that heat equally to all its parts at the fame time, and fo as not to operate on the pyrometer.itfelf, without which the ex- actnels of a compound pendulum could not juftly be tried by it. Laftly, another error is produced in the computation of the aberration of all pendulums, from not taking into account the dilation and contra¢tion of the {mall fteel {pring by which they are ufually fufpended. Other pendu- As all the ofcillatory pendulums yet made public are influ. ae enced in their notation of time by the expanfion of their fub- ftance, and as the beft contrivances to compenfate this are only an approach to perfe@ion, an increafe of probability but no certainty, it is therefore an objeét worthy attention to in- veftigate other methods for effeétng the fame purpofe: for which reafon I fhall here beg leave to fugeeft the reconfider- ation of a fpecies of POSH of a different nature, which has never been condemned on any juft ground that I could hear, and which in faé is fo little known, that the application of a fimilar movement to other purpofes, is by many fuppofed to be a late invention. The pendulum which_I allude to, ‘is that treated of in the fifth Part of the Horologium O/villatorium of the well known Huygens, publifhed in 1673, which he calls ON PENDULUMS. 715 calls the circular pendulum, and which much refembles the Circular pendu- centrifugal apparatus, ufed frequently about fteam-engines to !¥™ of Huygens. regulate the aperture of the {fteam-damper, of which it pro- bably fuggefted the firft idea. To form the circular pendu- lum, a fpindle (HD, fig. 1, Plate /11.) proceeds perpen- dicularly from the clock-work, from whence it receives a cir- cular motion round its own axis; to this is affixed a lamina (BGA) of fome breadth, bent according toa paraboloidal line, by the evolution of which (after it is joined to a certain right line) a parabola is formed, the conftru€tion of which is _ fhewn in the eighth propofition of the third part of the above work: This lamina caufes the ball of the pendulum (F), at- tached by two threads to its upper extremity (as it circulates), to perform all its revolutions (which will be of greater or lef{s extent as the axis moves with greater or lefs force) in the fur- face of a conoidal parabola (F E). Huygens declares, that all the circles performed by the pendulum thus conftru€ted, will be ifynchronous, and then fhews how to proportion the parts of the apparatus, fo as that each of its revolutions fhall be performed in a fecond, or in half a fecond: He fays, the only reafon which caufed the ofcillatory pendulum to be pre- _ ferred to this was, that this laft was more difficult to conftruct. : As this circular pendulum feems to poffe(s the valuable pro- | perty of correcting the alterations caufed in it by expanfion, or of rendering them of no confequence, the difficulty of con- ftruétion is a matter of no confequence, efpecially as there are now to be found artifts fo much more excellent in works of this kind than formerly. Huygens gives the following chara@ter of this pendulum, which I tranfcribe in his own words: “ Plura tamen, hujus » quoque generis de quo nunc loguimur, nec ine fucceffu, confiructa fuere: efique in Ins fingulare illud, quod continuo atque equa- ‘bili motu circumferri cernitur index poftremus, qui fecunda feru- pula defignat, cum in omnibus aliis horologiis fubfultum quafi feratur : > Item hoc quoque, quod abjque finepiin Sonoque omni ‘moveantur hoc ratione confiructa automata.” He concludes the ‘book with thirteen theorems, De vi centrifuga ex motu circu- lari, feveral of which prove this kind of pendulum to have moft valuable qualities: the fixth of thefe, being very remark- able, I copy for your readers, who may not have an oppor- oan of feeing the work which contains it, as follows : “« THEOREMA. 76 ON PENDULUMS. « THEOREMA. “In cava fuperficie conoidis parubolici, quod axem ad per- | pendiculum erectum habeat, circuitus omnes mobilis, circumfe- \ rentias horizonti parallelas percurrentis, fice parow five magne | JSuerint, aqualibus temporibus peraguntur : qua tempora fingula | aquantur binis ofvillationibus penduli, cujus longitudo fit dimi- | dium lateris reétz parabola genitricis.” | | From the above theorem, and what has been already laid | down on the fubje€, it is evident that the circular pendulum is well worthy of a fair trial, and fhould be recommended to |} the attention of all fcientific conftru€tors of horological move- |) ments. ! As this circular pendulum will take up more room -than a | common one, when this is any confiderable inconvenience, one of the following conftruétions on the fame principles (which have occurred to me while writing this communication), may be ufed in its place. Various cc>- The firft is as follows: Toa fhort fpindle afcending from ie the clock, as before defcribed, let there be attached a glafs or lem. iron tube, bent in the form of the conoidal parabola before- | mentioned, and placed as EF in Fig. 1: into this tube let there be poured a fufhcient quantity of mercury to ferve asa centrifugal weight. It appears to me that the mercury rifing in the Satie, as it | circulates, by, the centrifugal force, along its’ parabolical curve, will have the fame effeét as the weight in Huygens’s conftruction, caufed by other means to move in a fimilar line. The tube fhould be fufficiently large to admit the air to pafs freely above the mercury as it moves along its cavity, or elfe a {mall aperture fhould be made in the upper furface of the tube near the fpindle, for the fame purpofe: to prevent alfo the error which might otherwife be caufed by a varied re- fiftance to the motion of the circulating tube from the muta- bility of almofpherical preflure, the tube may be inclofed in a circular veflel covered at top, made of as light materials as. | poffible, and very fmooth externally, through whofe axis the fpindle fhould pafs, and to which it fhould be united fo as to revolve with the tube. A fecond method of effeGiing the fame purpofe is, to havea femi-cylindrical trough fhaped and placed - in fame manner as the above tube, in which fhould be put a | metallic {phere of {maller diameter than the trough, that the — fphere ON PENDULUMsS., 77 _Afphere might move in it without fri€tion; for, being thus “ formed, it follows, from the 13th of the third book of Euclid, that the {phere could never touch the trough but in one point alone at the fame time. A third method of conftru@ion is, te place a cylindrical metallic rod, or thick wire, bent into the parabolical curve before direéted, in the fame pofition as the above tube and trough; with a f{pherical weight put on it fo as to move freely along it, which laft might be effe€ted by a fri€tion-roller, either let into the upper part of the weight, or placed above it, whofe furface fhould be formed into a cir- cular groove of larger diameter than the rod. Thofe laft conftru€tions feem to me to have befides the far- ther advantage, that any dilation of their parts from change of temperature, could only lengthen the tubes or rods, but would not alter their fhape, on which alone their properties depend ; which circumftance might perhaps make them even more ex- aét than that propofed by Huygens, the ftrings, or appending part of which, would certainly vary in length; which, though, from the before-recited theorem, it appears to be a matter of little confequence, yet Huygens feems to hint that it would be of fome, by recommending the ufe of fine chains inftead of ftrings (that their length might vary the lefs), in thefe words: In locum fili catenulam tenuem exauro, aliove metallo, adhi- bere licebit, quo melius invariata fervetur longitudo.” \ There has alfo occurred to me a {pecies of ofcillatory pen- An ofcillatory or dulum; which, as it appears to have the fame property as thofe “Ny pendu- laft mentioned, (of nat being affected by the expanfion of its _materials,) I fhall bere defcribe: It confifts of a cylinder of hard metal, A (/%g. 4) turned very true and fmooth, placed fo as to roll back and forwards alternately, in the cycloidal ca- vity B, cut in a block of hard metal alfo, and well polifhed : the communication of motion between the rolling cylinder and the clock work to be effeéted by the rod C, fulpended by its upper extremity, and conneéted with each extremity of the axis of the cylinder by the joints DD: The diameter of the generating circle of the cycloid being half the length of a _ pendulum rod, which vibrates in the feauired time, and the cycloidal part well levelled and firmly fuftained. It feems to _ me that the cylinder A, when put in motion, will ofcillate equal times on its cycloidal fupport; and, (as the expanfion of the fatter will not alter its fhape, on which alone its properties de- pend,) ~ 18 ON PENDULUMsS, pend,) that the refult will be the fame in every different tem- perature; Bmay alfobe formed of two cycloidal plates, having circular grooves hollowed on their edges, and A have two projecting circles turned on it to run in thofe grooves; the me- thod of conne@ting A with the clock-work may alfo be varied many other ways. Concerning fric- | Before I conclude, I beg leave to obferve that the method, tion, &c. before mentioned, of preventing friction in the motion of the {phere in the parabolical trough, might be applied very bene- ficially in the:conftruction of rail roads, by forming the upper part of the rail of a femi-cylindrical fhape, and making in the edges of the wheels, (which were to run on them,) circular grooves, whofe diameters fhould each exceed that of the rail; in the ufual way of forming rail-roads, the lateral fri€étion to the wheels is very confiderable, whether they have flanches to them, and the rails are made plain, as in the Swanfea roads; or the rails are formed with rifing ledges, and the wheels plain, as in the Croydon road. The circular I hall alfo requeft permiffion to mention, in addition to your pendulum agood note on Prony’s condenfer of forces, that a regulator might be regulator of firft pada eis z : eee hgs, formed on the principles of the circular pendulum, as Fig. 3, which would temper the motion of wind-mills, or other en- gines, and reaét on them in return, (as well as the fly wheel), ina much more fimple and effe€tual manner than the very com- plicated apparatus defcribed by Prony for the fame purpofe, and which feems to me moreover peculiarly liable to be broken by any fudden increafe of velocity in the mill, unlefs formed of nioft cumberous ftrength. T requeft the favour of having the following typographical errors noted in the paper on my tallow lamp. November, 1804, page 147, line the eighth, for the word fre/h, read freely; and line the 25th, fame page, between the words means and korizontal, infert the letter P. In the plate alfo, the pan fhould be deeper and larger than there reprefented, and the tallow holder more central. lam, Sir, Your very humble fervant, J. WHITLEY BOSWELL. Reference =X © ON PENDULUMS, Reference to the Figures. Fig. 1. Anexaét copy of the figure of Huygens’s circular pendulum, from the Horologium. BG A, the edge of the paraboloidal lamina: F E, the parabola produced by its means: F, the ball. Fig. 2. The firft conftru€tion propofed in place of Fig. 1. AC, the parabolical glafs tube: A, the mercury: C, the air- vent: BB, the enclofing circular veffel reprefented in fe€tion, Fig. 3. The third conftruétion propofed inftead of Fig. 1. AC, the metallic rod bent into a parabolical figure: B, the {pherical weight: V, the roller on which it moves along AC: the parts in this figure are reprefented double, to fhew the beft method of adopting this plan as a regulator for wind-mills and other engines. Fig. 4. The propofed conftru@tion for an ofcillatory pendu- lum, which, it is imagined, will not be affeted by change of temperature. A, the ofcillating cylinder: B, the cycloidal fupport. Fig. 5. A feGtion of the {rough mentioned in the fecond pro- pofed conftru@tion, with thefphere in it. Annotations W.N. Pyrometers, p. 74.] The common pyrometers of the fhops are The beft pyro- indeed liable to the obje€tions of our author; b ut ingenious Diet ioc fallecions have long ago obviated them in their experiments. Deluc, in refults. the Philofophical Tranfaétions for 1777, gives a method of af-Deluc’s method. certaining the relative expanfions of two different metals by heat. He fufpended ‘one of the bars to an arm proceeding horizontally from an upright deal plank, and he fupported the other bar by refting its lower end upon a {mall cock or ftage proceeding from the lower end of the former. A microfcope was attached to the plank in fuch a manner that, while it was conftantly fupported by an horizontal arm, it could be moved _ fo as to keep the laft mentioned or ftanding bar in the focus of radiation for diftin@ vifion. Heat was applied to the bars, and the microfcope was dire€ted to a point on the ftanding bar. When by repeated fhifting the microfcope a point was- found which was neither raifed nor depreffed by the changes of tem- perature, the refpeétive lengths of the bars were inverfely as their expanfive powers. There was no mechanifm, and the plank would remain at the fame temperature during the expe- oye riments, = ; 80 ON PENDULUMS. riments, or might be kept fo by means fimilar to thofe pointed out by our ingenious author, or his block of ftone itfelf might have been ufed. Ramfden’s That great artift Ramfden, whofe mechanical {kill and cee clearnefs of intelleét were fo varioufly difplayed in his works, and ftill more in his converfation to thofe who remember and regret that he has recorded fo little of the refults of his labours; this artift firft availed himfelf of microfcopes for afcertaining the terminal points of the fubjeét under examination by his pyro- meter; and the interval between one microfcope and the other was rendered permanent by fixing them to’arms proceeding at right angles from a bar of iron, kept at 32° by furrounding it with melting ice. Phil. Tranf. Vol. LXXV. Methods of Lajily, another error, p.74.] [believe the {mall fpring and fim- examining grid- ple bar part, if any beneath the gridiron, are always taken into iron pendulums. 41,4 account. Thefe pendulums have not unfrequently been a ,.:. fubjeéted to a€tual examination. An old friend of mine, Mr, . agellan’s ine Q . Speen firument. J. H. de Magellan had an apparatus of tin, (Anno 1784) in which he inclofed the gridiron when to be examined. . It was hung by its {pring to an arm fixed in an upright plank of deal wood, again{t which plank were attached thermometers to fhew its fleadinefs of temperature; and from the center of ofcilla- tion proceeded a (temporary) rod, the end of which pre- fented a dot as the object to be viewed through a microfcope duly attached to the plank. Without dwelling minutely on this apparatus, I need only obferve that neither the arm of fuf- penfion, nor the fupport of the microfcope, nor the rod from the center of ofcillation had any parts but fuch as were paral- lel to the horizon, while the pendulum itfelf was perpendicu- Jar to it, and confequently that no error could arife but from expanfion inthe plank, which remained at the common tem- perature; and that the tin apparatus which covered and enclofed the pendulum bad only three openings, one at the bottom, one. at top, and one through which the rod from the center of ofcillation paffed, without touching the fides. In the experi- ment, fteam from boiling water was admitied below, and when the heat was fo raifed, and the fupply kept up, that uncon. denfed {team efcaped above the pendulum was judged to be at 212°, and if the center of ofcillation continued before the microfcope without either rifing or falling, the compenfation was confidered as complete. : , Mr. ON PENDULUMS, 8} Mr. Troughton’s apparatus, alluded to in his paper is differ- Troughton’s ent from thofe, and when he fhall favour me with the account humic of it, and the experiments he is making, the world will fee that it anfwers its purpofe with fuch facility and precifion as do ho- nour to his great (kill in thefe fubjets. Circular Pendulum of Huygens.] The difficulties attending Remarks on the conftruction of this pendulum feem to be principally in the pres cr ‘ y ; ; : B pendulum, firing or chain. Perhaps fine metallic wire might deterve the preference. It would not probably be difficult to bring the curve A B fufficiently near the true figure to anfwer its general purpofe, through the changes of force in the firft mover, and of refiftance in the air, Praétical men have not thought the cycloidal cheeks applied by Huygens, and fince him by others, to the common pendulum, of any utility; but have rather di- reted their attention to fmall vibrations, or an equalizing of the firft mover by periodically detaching the train. Huygens himfelf alfo propofed this expedient. It is generally admitted to be an advantage that the rezulating inftrument, whether pen- dulum or balance, fhould perform the greateft part of its mo- tion unconneéted with the train, The circular pendulum is conftantly fo connected, As the ingenious author has not detailed his reafons for Whether it-bre thinking that pendulums of this kind will not be affeéted by pati jae change of temperature, [ would fimply remark that it does not temperature. appear to me why an expanfion of the ftring fhould not canfe the pendulum of Huygens to revolve more flowly, or that an expanfion of the curves in the other figures would not dimi- nifh their curvature and produce the tutte retardation. The tube may be enclofed in u circular vegel.] As the refift- On pie ance of the air will vary no lefs than a tenth or a fifteenth part mnbesrinony Isiy according to the ftation of the barometer, we might expeét time pieces to be confiderably affected by its irregularity. In aftronomical clocks, with heavy pendulums and fhort vibra- tions, this quantity is extremely minute, as is proved by their very correé&t performance. But there are fads attending the performance of our belt portable chronometers, which thew that it is not in them an inconfiderable objeét, Several years ago | entertained a notion that the refiftance of the air might be rendered equable, or in fact done away, by boxing up the balance, as is here propofed by our author. But from his osyn excellent paper on the blaft ventilator inferted in the Vou, X,—Fuesruary, 1805. “@ fourth 82 Benjamin or benzoes little examined. Mr. Hatchett’s experiments. Benzoin is ob- tained from the Atyrax benzoe. Two kinds: viz, benzoé amy gdaloides, and ANALYTICAS. EXPERIMENTS AND fourth volume of the quarto feries of this Journal, as well as from thofe of Profeflor Venturi, inferted in the fame work, 1 learned how greatly the lateral reaétion of the air, which is put in motion by bodies pafling through it, muft affeét their movements. From this caufe the value of the contrivance will undoubtedly be diminifhed, but I think not done away. I believe the famous pocket time-piece made about the year 1784, by Emery of Charing-Crofs, for the Prefident Saron at Paris, had its balance boxed up; but as I fpeak only from recollection, it is quite as probable that the whole movement was enclofed ina cap or cafe fhut up by a fecret catch. Il. Analytical Expériments .and Objervations on Benzoin. By Mr, Wiriitam Branve’. Communicated by the Author.* ‘Vue fubftance which forms the fubje&. of the following experiments, and which is generally termed Gum-Benjathin‘or Benzoes, may be enumerated, among-thofe obje@s, which till lately, have but little engaged the attention of chemifts. Weare indebted to Mr. Hatchett for almoft all'that is as yet known, as to the chemical properties of the refins, gum-refin’ and balfams; and as the fubftance in ‘queftion, had not been examined by that gentleman, I was induced to make the fel- lowing attempt. BGS Benzoin ts obtained by incifions made in the tree called Styrax Benzoe +, from whence the balfam flows, ope tree fearcely ever yielding more than three, or at the moft four pounds. Benzoin is generally divided into two kinds; the one is formed of whitifh yellow tears, refembling almonds, ‘united - * The following experiments were made merely with a. view of afcertaining the etfeéts of different menftrua on benzoin; but as,the aétion of fome of the acids, &c. would have been much lefs. in- terefting, without a knowledge of the component parts of the bal- fam, I was* induced to make fome analytical experiments, which, though I fear they are by no means fo accurate as they ought | to be, will, I hope, ftill be found of fome ufe. +Dryander has given a defcription and drawing of this tree, ‘wilde ‘Phil. — 1787. p. 307. uit ~~» together OBSERVATIONS ON BENZOIN.! « 83 iogether by a brown fubftance of the fame nature, and is dif- . 40 tinguifhed by the name of benzoé amygdaloides. The other isa brown fubftance, fomewhat refembling com-¢ommon ben- mon refin, but poffefling in other refpeéts, the fame qualities as” the former; it is called common benzoin. The difference between thefe two {pecies is faid to arife from Caufe of this the latter having been expofed, for a length of time, to the “ence. fun, which converts the white benzoin into the brown. The benzoin, of the fhops is ufually in very large brittle Benzoin of the » mafles, and fuch as is whiteft, and free from extraneous fub-™°P* ftances is the moft efteemed. It grows in Sumatra, and is brought from the Eaft Indies only. , | When chewed, it impreffes a flight {weetnefs on the palate; Tafte. it has however but little tafte.. Its {mell is fragrant and very smell, agreeable,, becoming much more perceptible when gently heated. When thrown on hot coals it firft fufes, then takes fire, emit- Effeéts of heat ting at the fame ‘time a ftrong penetrating odour. Its fpecific ET gravity, according to Briffon, is 1,092. Gren, enumerates it among the refins*, as do moft other authors of his time; it is however more properly denominated a balfam, fince it is a combination of refin and benzoic acid. Compofed of We fhall firft examine the effeéts of different menftrua on '¢9 and benzoic benzoin, and then proceed to its analyfis, together with the methods of obtaining benzoic acid, 9 i “E iffecis of different Menftrua on Benzoin. _ 1. Cold water has but very little effeét on benzoin; boiling Effeéts of water water however extracts a part of its acid. on benzoin. 2. Alcohol diffolves the whole of benzoin when digefted Of aeorals with it in a very gentle heat, the impurities remaining behind. j The folution is of a deep yellow colour, when newleGiy fatus rated, inclining to reddifh brown, and poffefling in fome degree the fragrant {mell of the balfam, which may be obtained pure, either by gentle evaporation of the folution or by the additign of water, when a white powder precipitates, formerly known by the name of magiftery of benzoin. _ The aétions of the acids on the folution of benzoin in alcohol, Aion of the are very deferving of attention. aciay 0p this folution. * Handbuch, § 1174. 2nd edition, 1794, G2 A. Muriatic R4 ANALYTICAL EXPERIMENTS AND Of muriatic acide A. Mutiatic acid being added, a white curd is formed, and when three parts of acid and one of the folution are heated to- gether, a very fmall part of the balfam is rediffolved, which feparates as the mixture cools, while the remainder is converted into a black brittle fubftance when cold, part of the benzoic acid having been diffipated by the heat and part diffolved, fome of which feparates in the form of a white fcum, as the mixture cools, together with the benzoin. Of fulphuric B. Two or three drops of fulphuric acid added to the al- acid, coholic folution, occafion a white precipitate, which difappears on the addition of a fmall quantity more of acid, the mixture affuming the appearance of port wine, If however equal parts of the folution and of fulphuric acid be mixed together, a dark pink precipitate is formed, the fluid becoming likewife of the fame colour, but the addition of water changes the whole to a lilae colour. On evaporating a mixture of equal parts of folution of ben- zoin and fulphuric acid, the liquid retains its beautiful red co. tour till towards the end of the procefs, when it becomes gra- dually darker, and if the evaporation be carried on to dryne{s, a black coaly fubftance remains, a decompofition of the balfam having taken place. OF nitrie acid. ©. Nitric acid added to the folution of benzoin in alcohol forms a dark red fluid, and when equal quantities are mixed, a violent effervefcence takes place, attended with the emiffion of much nitrous gas. It muft be obferved that in this inftance, no precipitate is formed, which proves that the balfam is folu« ble in nitric acid, Of acetousacid. PD. The effects of acetous acid do not exceed thofe of water, Of acetic acid. E, Acetic acid forms a precipitate when added {o this fo- lution of benzoin. The effeéts produced by acetic acid on benzoin will be noticed hereafter. Of the alcalies. © F. The alealies form no precipitate in this folution of ben-. zoin, ‘although the mixture in fome cafes becomes fomewhat turbid, Agtion of 3. Ether diffolves benzoin with great facility, the balfam ether on bengoin. being feparated, when this folution is agitated with water. Effects of ths“ The effe@s of the acids on this ethereal folution, fo nearly tel this coincide with thofe produced on the folution in alcohol, that there will be no need of a detailed account of them. 4, Nitric = : OBSERVATIONS ON BENZOIN. 85 4, Nitric acid produces a violent effervefcence when poured Effedts of nitrig upon powdered benzoin, the balfam being at the fame time Sadia converted into an orange coloured mafs. Six ounces of nitrous acid, of the fpecific gravity of 1.36 Solution. being poured on one hundred grains of very pure benzoin re- duced into powder, the mixture being gradually heated in a fand bath till it boils, a folution of a light yellow colour is formed. The folution thus obtained, depofits a {mall quantity Sepzration of of benzoic acid, as it cools: this quantity gradually increafes, Pengale acid till after fome days, the whole of the benzoic acid appears to have been feparated. This faét was firft obferved by Gottling; he does not how- firft obferved by ever feem to have obferved that the wffale of the balfam is fo. Ct!" luble in nitric acid. A. When the above folution, recently made, is poured into senkes of water water, the benzoin 1s precipitated, apparently unaltered. Pee bigs B. Sulphurie acid caufes.no alteration in this folution. of fulphuric C. Muriatic acid forms a white precipitate which is re. Se ae dilfolved on the application of heat, forming a bright yellow acid. liquid, which is a folution of benzoin in nitro-muriatic acid, Sol. of benzoin and in which no precipitate is formed either by water or the Tiles: alcalies. Its colour is converted into dark brown, when ex- Effeéts of water cefs of potath is added. or 5. When fulpharic acid is poured on pulverifed benzoin, an mur. folution, efferve(cence takes place; part of the benzoin is diffolved ; ab hr forming a deep red liquid, and at the fame time a coaly ib. gage i {tance remains on the furface. Sulphureous acid gas is difen- gaged during the folution. A. The alcalies form no precipitate in this folution, till after aes of fome hours ftanding, when a dark coloured precipitate is formed, Bien i B. Water produces a lilac precipitate in the recent folution, of water. 6, Neither muriatic nor acetous acids have any effeét on Effedts of mu- benzoin a eli 7. Acetic acid duinlyes benzoin, even in the cold. The benzoin, folution formed by the affiftance of heat becomes very turbid of #¢ctic acid. on cooling, owing to the feparation of the benzoic acid, A. The alcalies form a white precipitate in this folution.— Effects of the The precipitate formed in the alcoholic folution, (page 11 ) ee a is re-diffolved after fome hours ftanding. 8. Acetic ether diffolves benzoin, without the affiftance of Effeés of acetic h eat ether on ben- ZOiNs 9. When roms, 86 Effeéts of foda and potafh on benzoin. Effeéts of the acids on thefe folutions. Effeéts of am- monia on ben- ZOiN. ANALYTICAL EXPERIMENTS AND 9. When a boiling lixivium of pure potafh is poured on benzoin, a folution is immediately formed; the fame effect is " produced when pure foda is made ufeof. Thefe folutions are of a dark brown colour, and become turbid after fome days expofure to the air. Precipitates are formed in them by the acids, which are re- diffolved on the application of heat, when nitric or acetic acids are added in excefs. Ammonia likewifle diffolves a {mall quan- tity of benzoin, from which folution it is precipitated by the acids. Effeéts of water No alteration is produced when the alcaline folutions are on the alcaline folutions. Diftillation of benzoin. Component parts of bene goin. largely diluted with water.* : § IL _ ANALYTICAL. EXPERIMENTS ON BENZOIN. Difitilation of Benzoin. One hundred grains of very pure benzoin were put into a glafs retort, to which a tubulated receiver, and pneumatic ap- paratus were adapted; a very gentle heat was firft applied, which was afterwards gradually increafed, till the bottom of the retort became red-hot. The produéts thus obtained were as follows. Grs. Benzoic acid - - > - - - 9. Acidulated water - ~ - - wigeh ied Butyraceous and empyreumatic oil - - 60. Brittle coal - - - - - os ~ 22. And a mixture of carbonated hydrogen and car- bonic acid gas, which may be computed at = (13.5 100.0 The quantity of benzoic acid above mentioned is that which may be feparated by fublimation only, for on treating the oil, (which amounts to 60 grains) with water, five grains more of acid may be obtained, fo that 100 grains of benzoin contain Oil “wireeyhe $6 Acid - - 14 * For an account of Mr. Hatchett’s experiments on the refins, gum refins, and balfams, fee Thompfon’s Syftem of Chemiftry, 2d edition, Vol. IV. page 305. for the refins and balfams to page 328. And from page 341 to 347 for the gum refins. 4 The \ OBSERVATIONS ON BENZOIN, $7 .' The greateft quantity of benzoic acid is obtained by Chap- ees a tals method, which confifts in diftilling all the produéts over are ole i together, and feparating the,acid by means of boiling water. The acid, however, thus obtained, is by no means fo pure Scheele’s pro- as that procured by Scheele’s procefs *, which is ceriainly far pees preferable in many refpects. Another way of obtaining the benzoic acid, is that recom- Gottling’s pro- mei ‘ed by Gattling. It confifts in digefting the balfam, in a cefs for obtain- , " i wee) ing benzoic gentle heat with carbonate of potafh and precipitation by ful- acid. phuric acid. (Gren made ufe of carbonate of foda: but it muft Gren's procefse be obferved that in both thefe proceffes, the acid is by no means fo pure as that obtcined by Scheele’s method, becaufe afar larger proportion of the benzoin itfelf is foluble in the fixed alcalies, than in lime water, (the latter only diffolving a very {mall portion, to which its brown colour is owing) and * Scheele’s procefs is as follows: ** Upon four parts of unflacked lime pour 12 parts of water, and after the ebullition is over add 96 parts more of water; then put 12 parts of finely powdered benzoin info atin pan; pour upon it firft about fix parts of the above milk of lime, mix them well together, and thus fucceflively add the reft of the mixture of lime and water. If it be poured in all at once, the benzoin inftead of mixing with it, will coagulate and run to- gether into a mafs. ‘This mixture ought to be boiled over a gentle fire for half an hour, with conftant agitation ; then take it fromthe “fire, let it ftand quiet for an hour, in order that it may fettle; pour off the fupernatent limpid liquor into a elafs veflel. Upon the re- mainder in the pans pour 96 parts of pure water, boil them toge- ther for half an hour, then take it from the fire and let it fettle; : add the fupernatent liquor to the former; pour upon the refiduum fome more water, boil it as aforefaid, and repeat the fame proceis once more. At laft put all the refiduums upon a filter, and pour hot i water feveral times upon it. During this procefs, the calcareous éarth combines with the acid of benzoin, and feparates it from the refinous particles of this fubftance. A fmall quantity of the refin is diffolved by the lime water, whence it acquires a yellow colour. All thefe clear leys and deco&tions are to be mixed together and boiled down to 24 parts, which are then to be ftrained into another glafs veffel. After they are grown cold, muriatic acid is to be added, with conftant ftirring, till there be no further precipitation, or till the mafs taftes a little fourith. ‘The benzoic acid which was before held in folution by the lime, precipitates in the form of a fine powder.” Vide Thomfon’s Chemiltry, Vol. II. page 123. whiel S$ > ANALYTICAL EXPERIMENTS AND which is precipitated by the diluted fulphuric acid. The fol- lowing table thews the quantity of benzoic acid, obtained by the different proceffes, from one pound of benzoin. Oz. Dr. Scr. Grs- Scheele’s procefs a AIO Re RES ME: A Chaptal’s) > - - - - ~ 2 Oe IG By boiling benzoin with water —- Oe Hare By Gren’s and Gottling’s proceffes - ete e® The acid of Benzoic acid is defcribed by Blaife de Vigenere, as long ago benzoin, firft 45 the year 1608, in his treatife on fire and falt; he called it defcribed by M f f ® c Blaife de flowers of benzoin, becaufe it was obtained by fublimation. Vigeneres We are indebted to Tromfdorf and Lichtenftein for many faéts relating to this acid. Properties of the Acid of Benzoin, This acid when obtained according to Scheele’s procefs, is Tate of the 2 light yellowith powder. Its tafte is hot and rather bitter. acid. It poflefies a fomewhat fragrant fmell, arifing from a fmall por- _- tion of the aromatic oil, which ftill adheres to it, it has how- ever been obtained without any fmell by Giefe. Properties in It reddens tin@ture of turnfole. It is volatilized by a gentle general. heat, being converted into, a white fmoke, which excites a very difagreeable fenfation in the throat. When melted, it becomes as fluid as water, and affumes a radiated furface on cooling. Its {pecific gravity is 0.667. Decompofition. When diftilled in clofe veffels, a part of it is decompofed, which is converted into oil and carbureted hidrogen gas.— Effe&s of oxigen Tromfdorf + found that it was not altered by oxigen gas, nor gas, &c. on this 4 : sad ma. by the fimple combuttibles or incombuftibles. Of fulphuric It is foluble in fulphurie acid, which it converts into a brown ced liquid, and from which it is feparated by the addition of water. Of nitric and The fame effeéts are produced by nitric acid, and by fulphu- kee agg reous and nitrous acids. It is not aéted upon by muriatic, ox- > Effeéts of mu- ymuriatic, or phofphoric acids. It is eafily foluble in alcohol, matic acid, &¢- from which it is precipitated on the addition of water. Its * Of pure acid, obtained by treating the precipitate with boiling water. + See Tromfdorf’s experiments on the benzoic acid, in his Journal der Pharmacie. -affinities OBSERVATIONS ON BENZOIN. 89 affinities appear to be as follows:*—White oxide of arfenic, Its affinities, potafs, foda, ammonia, barytes, lime, magnefia, alumina. ~ Properties of the Oil of Benzoin. f The oil obtained by the diftillation of benzoin poffeffes a ftrong empyreumatic odour; but when reétified by a fecond diftillation, its {mell is exceedingly fragrant and pleafant. Its Smell and tafte, tafte is acrimonious and very difagreeable. When diftilled with water, it imparts fome of its tafte to imparted to that fluid. It is perfetly foluble in alcohol, the folution be- Water. . : i Solution In coming turbid when water is added. stualed, Sulphuric acid decompofes it in part, when the mixture is 4 @ion of ful- heated. Nitric acid acts on it as on the effential oils in gene- Phuric acid. avy tae ; OF nitric acid. ral, converting it into 2 refinous fubftance. It is not affected Of muriatic acid, by muriatic acid, but 1s partially foluble in acetic acid, Jt and the alcalies. finks m water; and forms faponaceous compounds with the alcalies, - Such are the general properties of the acid, and oil of ben- zoin, much more might undoubtedly be faid concerning them ; but as the foregoing experiments, were not made with a view of inveftigating their properties, it would be unneceffary to give a long account of them in this place. It muft be obferved that the pureft benzoin has been made ufe of throughout; and laftly, that no traces of alcali, were found in the coal which remains afier diftillation. Arlington-Street. IV. On the Devitrification of Glafs and the Phenomena which hap- pen during its Cryftallization, By DaRTIGVES. (Concluded from Page 64.) W uen clear glaffes contain a certain quantity of a neutral Imperfeét falt which the fire has not had time or force to diffipate, it peers often happens, during flow cooling, that the appearances called greafe, threads, bubbles, and {pecks, are {pontaneoufly and fuddenly formed. * This table of affinities was formed according to the experiments of Tromfdorff. Vide Thomfon’s Syftems of Chemiftry, Vol. II. pege 126. 2nd edition. Thefe 90 DEVITRIFICATION OF GLASS. _ Thefe accidents, their different caufes and remedies, are ‘treated at length in the firft part of my work, where I {peak of the fonding of glafs; but though the explanation of thefe faGis entirely belongs to the theory of devitrification, it will be fufficient in this place to mention the phenomena which arife from the prefence of the different earths. Cryftallization Colourlefs glaffes contain more or lefs of lime, for the rea- of lime in glaf’y fons which I have mentioned in {peaking of the different com- pofitions of glafs. This lime, when in excefs, gives cryftals very well, as Adby fel remarks: they are eafily known, and fo abundant, that they abfolutely 1 impair the tranfparency: they are prifms, which feem to float in the midft of the pafte of glafs, and tend to unite in {tars differently figured: thefe prifms are al! nearly of the fame thicknefs, and two or three millimetres in length (about one-tenth of an inch), in large moffes. , When this cryftallization takes place fpontaneoufly upon \ large maffes at the bottom of the furnace, the colour of the glafs becomes darker, and inclines to black, by the mixture of a certain quantity of the afhes. The ftriated ftars here fpoken of, become more numerous, the more ‘remote they are. from the fide in contaét with the fire. Cryftallizations at firft infulated, are {oon fucceeded by a mafs entirely cryftallized, in which the vitreous character is no longer diftinguifhable. Modified cryftal-, Thefe are the moft common characéters of cryftallization ; lizations in glafs. rieties*, I have fome pieces of glafs in which cryflals are difc ace fo fine, that they can fcarcely be feen with a mag- nifier. ‘They are prifms divergent from the fame center, and forming ftars, which frequently-do not exceed one millimetre (or half a tenth of an inch) in diameter: ‘their union refembles a flight mift in the pafte of the glafs. Some pieces have the afpeét of a faline cruft applied to a foreign body, againft which the glafs was in conta@. In iene" of thefe this cruft being compofed of ftriated protube- rances, appears to advance more and more into the glafs itfelf. Laftly, there is another variety perhaps more curious than all the reft, in which centers, or cryftallizations refembling * Mr. Sage poffeffes a piece of elafs cryftallized in fix-fided ba- faltic prifms, totally devitrified, peasy but others are frequently feen, which are certainly owing to, accident, and well deferve notice on account of their va-- DEVITRIFICATION OF GLASS. Gs peas, and almoft fimilar to grain, are feen in the midft of the pafte of glafs. They are fmall {pheres flattened at each end with an indentation in the middle of each depreffion. The fides have facetts, like the grain of Indian nafturtium, and thefe faffetts are always fix in number. I intend, when I fhall have procured a fufficient number of this fingular fpecies of cryftal, to analyze it, in order to de- termine which of the earths it is that effects fo extraordinary a form. I have thus given a fhort account of the principal faéts which charaAerize the precipitation and cryftallization of glafs. It is evident that they are of the fame nature as thofe produced by the cementation pointed out by Reaumur; and that this cementation is always a more or lefs abfolute devitrification of the glafs. When the glafs is devitrified, it has no longer a vitreous Recapitulation, but a granulated fra€ture ; it bas no tranfparency, and perfectly refembles a {tone ; it becomes a lefs bad conduétor of heat and of eleétricity ; laftly, it is no longer fufceptible of fufion at the fame degree of heat; and in order to reftore it more eafily to Revitrification. the vitreous flate, it. muft firft be pulverized, to bring into contaét thofe fubflances which, during, the cryfiallization, had become feparated from each other, and could no longer ferve as fluxes to each other. a i I hope the novelty of many of the fa@ts I have here indicated, General conclu and the confequences I have drawn from them, may be fuffi- £02 24 applica~ ciently interefting to philofophers to have fome claim to Merc on isi attention. I have no doubt but that other general induétions will prefent themfelves to them which may have efcaped me, or which could not be introduced in a fhort memoir. The refemblance of my fpecimens of devitrified glafs with thofe of certain lavas; the poflibility that other lavas may have under- gone a more complete devitrification by a much flower cooling beneath the volcanic currents which are known to have flowed, or to have remained fluid for whole years beneath congealed crufts ;—every faét leads me to think, that thefe phenomena may afford a folution of many geological events, concerning which no general opinion has yet been adopted, becaufe there was no reafon to believe that flones may have formerly pof- fefled the vitreous ftate. Letter 92 Apparent reflece tion of cold. Kepler did not invent or know of the telefeope before Galileo. ON PHILOSOPHICAL DISCOVERIES. V. Letter from a Correfpondent, relating to the apparent Refle&can of Cold and the Invention of the Telefcope, as noticed by Sir H.C. Encuerizrp tn laft Month’s Journal. To Mr.. NICHOLSON. SIR, In juftice to Profeffor Pictet, I traft you will have the good- nefs to infert in your next number the words of a note in his Egui de Phyfique, p. 81, where he defcribes his experiment on the apparent refle€tion of cold: «*« Les Académiciens del Cimento avosent effuyé de concentrer le froid au foyer d’un miroir concave; mais ils avouent eux- mémes, que leur expérience avort été futte d’un manieére trop in- exade pour qu’on put en rien conclure de certain.” Perhaps Profeflor Pigtet {peaks too lightly of the experiment of the Academicians; but fo far was that experiment from being forgotten, that the account of it has been very lately reprinted in the firft volume of the Journals of the Royal Inftitution, p. 224; a work to which your correfpondent, who has revived the fubje€t (page 1 of your laft Number), has himfelf contributed fome valuable papers. With refpeét to the invention of the telefcope, give me leave to obferve, that perfpicillum means fimply the fight of an aftronomical initrument, having a fmall perforation, If the comet in queftion was furrounded by a fmall round and well- defined nebulofity, fuch a fight might eafily produce the effect attributed to it, A telefcopic fight is ufually called perfpi- cillum vitreum. Galileo fays, in a work publifhed in 1610, that he was informed of the invention of telefcopes about nine months before. Kepler wrote, in 1611, a valuable work on the theory of dioptrics, in which the conftruétion of the aftro- nomical telefcope is defcribed. Had he been the original in- ventor of the Galilean telefcope, he would not omitted this opportunity of fubftantiating his claim to fo important 4 dif- covery, : Iam, Sir, . Your very obedient fervant, ALETES, Faas GREATEST DENSITY OF WATER. Qs VI. Faas tending to decide the Quejtion, at what Point of Temperature Water pofejes the greateft Denjity. In a Letter from Mr. Joun Dacron. To Mr. NICHOLSON. SIR, —Accorpine to the doétrine in moft of our books treat- ees. notion ing of the elements of chemical fcience, it is confidered as a peerieegh decided faét, that water is of the greateft denfity at or near &c. 40° of temperature of Fahrenheit’s fcale ; and that, above or below that temperature, it expands alike by heat or cold for a certain number of degrees. I have taught a different doc- he ——- . trine for fome time og which is, that water is denfeft at pst © tie pits 322, or the freezing point, and that it expands alike above Per den- and below that point for at leaft 25° (provided it does not “*Y freeze), and that the quantity of expanfion is as the fquare of the temperature, reckoned from 32°, up or down; that is, if the expanfion from 32 to 42° be denoted by 1, that from. 32 to 52° will be denoted by 4, and that from $2 to 62° by 9, §c. or nearly fo; the deviation from ftriét accuracy being, as I conceive, occafioned by the mercurial thermometer not being an exact meafure of temperature: the expanfion at 22° is likewife 1, at 12° itis 4, and at 2° it is 9, &c.; the fame below as above the freezing point. In confequence of. this, Experiments a gentleman of profeflional eminence has undertaken to exa- a pita og » mine the fubject anew; and has been led, by an ingenious conclufion. train of experiments totally different from the following, to decide in favour of the common notion, that water is denfeft about 40°. Thefe experiments of his will foon be publithed, The author re- I am ftill, however, decidedly convinced, that my opinion ia poet re above itated is true, and that principally from the fa€ts I am vites ‘other exepes about to ftate, which thofe who adopt the common opinion ™¢?t mutt fee the abfolute neceflity of explaining upon their prine ciple, or otherwife, of controverting the faéts themfelves, As this feafon of the year is moft convenient for experiments of this nature, I am the more folicitous to have the faéts an- nounced, leaving all explanation for the prefent. They are of a very fimple naiure, and may be inveftigated with little trouble and expence. ’ A number 94 GREATEST DENSITY OF WATER. Inftruétions for A number of water thermometers are to be procured, the Sorkaenaet containing veffels of which are of different materials, as earth- rocure large : bulbed thermo- en ‘ware, glafs, and various metals. Each of thefe fhould meters, of earth- contain one or two ounces (from 4 to 800 grains), more or ew” lefs, of water, Common brown inkftands, which go by the name of Nottingham ware, anfwer very well for one fpecies, but they require to be well painted without, as they are not otherwife water-tight. I have a few of Queen’s ware, made purpofely in Staffordfhire, which conftitute another fpecies ; of earthen ware; fome of them are glazed in and out; others ‘ unglazed, but thefe being painted without are made water- tight, and expand the fame by heat as. glazed ones: Of glafs, common thermometer tubes, with larger bulbs than ordinary, are fufficient. I have the metallic veffels made in the fhape of cylindrical tin canniflers, conical towards the top, and at the fummit a fmall cylindrical tube, fuch as te take a ther- ™ mometer tube. The glazed earthen ware and the ‘me- tallic, require moftly to be painted before they are quite tight. . Fillthem with ‘The veffels being thus prepared,. they are (o be filled with boiled water. © water previoufly boiled to expel the air; a thermometer tube with cement is then fuddenly plunged into the veffel and ce- mented faft; the water may then be driven out of the tube by heat, or more may be put into it by a fmall wire; it is then fit for ufe, and a fcale of equal parts may be applied to the tube ; or it may be divided, and marks made with a file or paint.” Some of the refults of my experiments with inftruments of this kind, are as follow : , Water Water the fame loweft. height. Experimental 2. Brown earthen ware, No. 1, at 36° .- . at 32% and 40° refults noted = 9.,s Brown earthen ware, No.2, - 38 - - 32 and 44 with three » Ate earthen, one | 3+ Qlueen’s ware, - - - 40 -) «= 320and 48 glafs, twoiron, 4, Flint-glafs, - - ~ - 414 - .= 32 andSt. is ane chee 5. Iron, thin plate, - + + 423 -- = 32 and 53 ter, andone 6. Tinned iron, - - ~ 422 « = $2 and 53 re 7. Copper, - oe - - 452 .= | - 82 and 59 8, Brafs,. = * - “ «46 «= | +. 32. and 60 9. Pewter, - ™ - - - 46 - «=: 32 and GO. 10. Lead, ° ~ - - - 49% - -- 82 and 67 Another MR. HATCHETT’S “EXPERIMENTS ONY LAC. \ Another phenomenon in thefe inftruments is obfervable ; Phenomenon of it is not new, but it deferves a marked attention in the:prefent enquiry: If the apparent expanfion of water for the firft 10° of temperature, reckoned from the loweft point in any of the above inftruments, be denoted by 1;, then if the inftrument, taken at any temperature, be fuddenly plunged in) water ‘of .10° higher temperature, the water inftantly inks a confider- able way, occafioned no doubt by the veffel being extended by the heat before the water it contains has time to expand. The quantity of depreffion in the different inftruments. was found as under: Sie Brown earthen ware finks by being dipped in water of 10° higher temperature, = Be Queen’s ware, - - - Sti Flint-glafs, —- - - “ (25 Tron, - - - - - 66 Copper, oq al yle - aitstied Brafs, if - - 2c] Pewter, - - - = 0 - Lead, ) sci? ~ - - 28. 29100 I fubmit thefe faéts to the confideration of thofe who feel interefted inthe enquiry ; and defire that they may be parti- cularly inveftigated by thofe who maintain that water is denfeft rat 40°. , I remain your’s, } aif J. DALTON. Manchefter, Jan. 10, 1804. | ~ tavne & : ’ Vil. fi « , Analytical Experiments and Objervations on Lac. By CHARLES _ Harcuert, Ly. fF. RS. From the Philofophical Lranfac- __ tions for 1804. ‘ (Concluded from p. 54.) nay) 19) * ©. «Properties of the colouring Extraa of Lac. the depreffiow of a thermometrica} fluid when the intrument is fuddenly heated, » Table of this de. preffion in the . different ther- thometers. Ad. W uen dry, it is.of a deep red colour, approaching to Colouring ex- purplifh crimfon. _ 2. Being put ona red-hot iron, it emits much fmoke, witha fmell fomewhat refembling burned animal matter, and leaves avery bulky and porous coal. 3. Water, tract of lac. 96 Colouring ex~ tract of lac. MK, HATCHETT’S EXPERIMENTS 8. Water, when digefted with it in a boiling heat, partially diffolves it; but the refiduum was found to be abfolutely in- foluble in water, 4. Alcohol aéts but flowly on it; and, in a digefting heat, diffolves lefs than water. The colour of the folution is alfo not fo beautiful ; and a confiderable part of the refiduum left by alcohol was, when digefted with water, found to be foluble, although this was not the cafe, when the refiduum left by water was treated with alcohol. 5. It is infoluble in fulphuric ether, excepting a very {mail portion of refin, which appeared to be accidentally mixed with it. ' 6. Sulphuric acid readily diffolves it, and forms a deep brownifh-red folution, which, being diluted with water, and faturated with potath, foda, or ammonia, becomes changed to a deep reddifh-purple. 7. Muriatic acid diffolves only a part: the folution is of the colour of port-wine, and, by the alkalis, is cae toa deep reddifh-purple. 8. Nitric acid fpeedily diffolves it: the folution is yellow, and rather turbid; but the red colour is not reftored by the alkalis, for thefe bilby deepen the yellow colour. This nitric folution did not afford any trace of oxalic acid. 9. Acetic acid diffolves it with great eafe, and forms a deep brownifh-red folution. 10. Acetous acid does not diffolve it quite fo readily, but the folution is of a brighter red. Both of the above, when faturated with alkalis, are changed to a deep reddifh- purple. 11. The lixivia of potafh, foda, and ammonia, a€& power- fully on this fubftance, and almoft immediately form perfeé folutions, of a beautiful deep purple colour. ¥2. Pure alumina, put into the aqueous folution, does not immediately produce any effe€t; but, upon the addition of a few drops of muriatic acid, the colouring matter {pee- dily combines with the alumina, and a beautiful pace is formed. 13, Muriate of tin produces a fine crimfon precipitate, ‘when added to the aqueous folution. 14, A fimilar coloured precipitate is alfo formed, by the addi- tion of folution of ifinglafs. 2 Thefe / AND OBSERVATIONS ON LACs, Thefle properties of the colouring fubRance of lac, efpes cially its partial folubility in water, and in alcohol, and its infolubility in ether, together with the precipitates formed by alumina and muriate of tin, indicate that. this fubftance is vegetable extract, perhaps flighily animalized by the cocs cus, | | ) The effeéts which it produced on gelatin, allo demonftrate the prefence of tannin; but this very probably was afforded by the fmall portions of vegetable bodies, from which the {tick lac can feldom be completely feparated. Properties of the Refin of Lac. 97 This fubftance is of a brownith-yellow colour; and, when Refin of lace put on ared-hot iron, it emits much fmoke, with a peculiar {weet odour, and leaves a {pongy coal. It is completely foluble in alcohol, ether, acetic acid, nitric acid, and the lixivia of potafh and foda. Water precipitates it from alcohol, ether, acetic acid, and partially from nitric acid; and it polfefles the other general characters of a true refin. Properties of the Gluten of Lac. It has been already obferved, that when fmall pieces of fhell Gluten of lac. Jac have been repeatedly digefted in, cold alcohol, they become white, bulky, and elaftic. By drying, thefe pieces become brownith and brittle; the elafiicity is alfo defiroyed by boiling water, exa@ly as when the gluten of wheat is thus treated, If the pieces of fhell lac, afier the digeftion in alcohol, be, digefted with diluted muriatic acid, or with acetic acid, the greater part of the gluten is diffolved, and may ibe precipitated, in a white flaky ftate, by alkalis; but, if thefe laft_ be added to excels, and heat be applied, then the glue tinous fubftance is rediffolved, and may be precipitated by BGidsy wile If the pieces of fiell lac, after digeftion in alcohol, be treated with alkaline lixivia, then the whole is diffulved, and forms a turbid folution. But, when acids are employed, the chief part of the gluten is alone acted upon, and a confiderable refiduum is left, confifting of the wax, fome Vou. X.—Feprvuary, 1805. H of 98 Wax of lac. MR. HATCHE’TT’S EXPERIMENTS of the refin, and a portion of gluten, which has been pro- teéted from the aétion of the acid by the two former fub- ftances. The above properties indicate a great refemblance between this fubftance and the gluten of wheat; I therefore have ealled it gluten, but, at a future time, I intend to fubjeét it to a more accurate examination. Properties of the Wax of Lac. If fhell lac be long, and repeatedly digefted in boiling nitric acid, the whole is diflolved, excepting the wax, which floats on the furface of the liquor, like oil, and, when cold, may be collected; or it may be more eafily obtained in a pure ftate, by digefting the refiduum left by alcohol in boiling ‘nitric acid. The wax thus obtained, when pure, is pale yellowith white, and (unlike bees wax) is devoid of tenacity, and is extremely brittle. It melts at a much lower temperature than that of boiling water, burns with a bright flame, and emits an odour fome- what refembling that of fpermaceti, Water does not act upon it, neither does cold alcohol ; but this laft, when boiled, partially diffolves it, and, upon cooling, depofits the greater part; a fmall portion, however, remains in folution, and may be precipitated by water. idk Sulphuric ether, when heated, alfo diffolves it; but, upon cooling, nearly the whole is depofited. Lixivium of potafh, when boiled with the wax, forms a milky folution; but the chief part of the wax floats on the furface, in the ftate of white flocculi, and appears to be con- verted into a foap of difficult folubility; it is no longer in- flammable, and, with water, forms a turbid folution, from which, as well as from the folution in potath, the wax may be precipitated by acids, Ammonia, when heated, alfo diflolves a {mall portion of the wax, and forms a folution very fimilar to the former, Nitric and muriatic acids do not feem to a€&t upon the wax ; ihe effeéts of fulphuric acid have not been examined. When the properties of this fubftance are compared with thofe of bees-wax, a difference will be perceived ; and, on the contrary, AND OBSERVATIONS ON LAC, 99 contrary, the moft ftriking analogy is evident, between the wax It greatly re~ of lac’‘and the myrtle wax which is obtained from the Myrica ,. cet ida cerifera. An account of the latter fubftance has been publifhed by Dr. Boftock, of Liverpool, in Nicholfon’s Journal, with comparative Experiments and Obfervations on bees-wax, fpermaceti, adipocire, and the cryftalline matter of biliary calculi, * The properties of the myrtle wax, as defcribed in Dr. Boftock’s valuable paper, fo perfeétly coincide with thofe which I have obferved in the wax of lac, that I cannot but con- fider them as almoft the fame fubftance; indeed I think they may be regarded as abfolutely identical, if fome allowance be made for the flight modifications which have been produced by the different mode of their formation. ‘From the preceding experiments and analyfes we find, that Component parts the varieties of lac confift of the four fubftances which have ° been defcribed, namely, extraétive colouring matter, refin, gluten, and apeculiar kind of wax. Refin is the predominant fubftance ; but this, as well as the other ingredients, is liable, ina certain degree, to variation in refpe& to quantity. According to the analyfes which have been defcribed, one hundred: parts of each variety of lac yielded as follows: ; Stick Lac. i a : - = 68. Colouring extrait - - ts 10. Wax - - ~ sities 6. Gluten “ - : 4 5.50 Extraneous fubftances a Serie 6.50 9.60. Seed Lac. Refin = mogud 71s z 88.50 Colouring extraét - . - 2.50 Wax = = - - 4,50 Gluten’ - - - - 2 97.50. * Nicholfon’s Journal for March, 1803, p. 199. H a Shell 100 MR, HATCHETT’S EXPERIMENTS Shell Lac. Refin - - 2 - 90.90 Colouring extraét - - - 0.50 Wax - - 3 4 4, Gluten ° = - 2.80 98.20. The proportions of the fubftances which compofe the varie- ties of lac, muft however be fubje& to very confiderable va- riations; and we ought therefore only to confider thefe ana- lyfes in a general point of view. Hence we fhould ftate, that lac confifts principally of refin, mixed with certain pro- portions of a peculiar kind of wax, of gluten, and of colous- ing extract. The relative quantity of the two latter ingredients, very con~ fiderably effect the charaéters of the lacs; for inflance, we may obferve, that the glutinous fubftance, whe prefent in fhell lac in a more than ufual proportion, probably produces the defe&t obferved in fome kinds of fealing wax, which, when heated and burned, become blackened by particles wy coal ; for the gluten affords much of this fubftance, and does not melt, like the refin and wax. From what has been ftated, therefore, lac may be denominated a cera-refin, mixed with gluten and colouring extract. § III. GENERAL REMARKS, Lac has thechae From the whole of the experiments which have been re- ratters of vege- Jated, it appears that although lac is indifputably the pro- et du&tion of infeéts, yet it poffeffes few of the charaters of animal fubftances: and that the greater part of its aggre- gate properties, as well as of its component ingredients, are fuch as more immediately appertain to vegetable bodies. It is very ufeful; Lac, or gum lace, as it is popularly but improperly called, is certainly a very ufeful fubftance; and the natives of India furnifh full proofs of this, by the many purpofes to which they apply it. for rings, beads; According to Mr. diese it is made by them into rings, beads, and other female ornaments: Wher AND OBSERVATIONS ON LAC. 101 When formed i fealing wax, it is Siplowéd 4 28 a japan, fealing wax, and is likewife manufaGtured into different coloured war. ¥#%¢ss nifhes. | The colouring part is formed into lakes for painters: a fort lakes, dying 5 of Spanith wool for the ladies is alfo prepared with it: and, as a dying material, it is in very general ule. The refinous part is even employed to form grindftones, by grindftones, and melting it, and mixing with it about three parts of fand. For Polithers ; making polifing grind{tones, the fand is fitted through fine muflin; but thofe which are employed by the lapidaries, are formed with powder of corundum, called by them Corune., * But, in addition to all the above ules to which it is applied the Hindé ink ; in India, as well as to thofe which caufe it to be in requeftt in Europe, Mr. Wilkin’s Hinda ink occupies a confpicuous place, not merely on account of its ufe as an.ink, but becaufe it teaches us to prepare an aqueous folution of lac, which probably will be found of very extenfive utility. This folution of. lac in water may be advantageoufly em- water varnith : ployed as a fort of varnifh, which is equal in durability, and other qualities, io thofe prepared with alcohol; whilft, by the faving of this liquid, it is infinitely cheaper. I do not mean however to affert that it will anfwer equally well in all cafes, but only that it may be employed in many. It will be found likewife of great ule as a vehicle for colours ; for, when dry, it is not eafily affected by damp, or even by \ water. With a folution of this kind, I have mixed various colours, The tetter very fuch as vermillion, fine lake, indigo, Pruffian blue, fap green, «fal. : and gamboge; and it is remarkable, that although the two laft Carus are of agummy nature, and the others had been previoufly mixed with gum, (being cakes of the patent water-colours,} yet, when dried upon paper, they could not be removed with a moiftened fponge, until the furface of the paper itfelf was rubbed off. . In many arts and manufactures, therefore, the folutions of lac may be found of much utility; for, like mucilage, they -may be diluted with water, and yet, when dry, are little if at all affecied by. it. We * Phil. Tranf. 1781, p. 380. + The alkaline folutions of lac are evidently of a faponaceous natures and, like other foaps, may be decompofed by acids. The entive 102 MR. HATCHETT’S. EXPERIMENTS ON LAC. Refins ated on = We find, from the experiments on lac, that this fubftance is Le and ale ¢jyble in the alkalis, and in fome of the acids. But this faét ; (confidering that refin is the principal ingredient of lac) is in oppofition tothe generally received opinion of chemifts, namely, that acids and alkalis do not aét upon refinous bodies, Some experiments, however, which I have made on various refins, gum-refins, and balfams, fully eftablith, that thefe fubftances are powerfully aéted upon by the alkalis, and by fome of the acids, fo as to be completely diffolved, and rendered foluble in water. Z , Field of inquiry. It will be a very wide’and curious field of inquiry, to difeover what changes are thus produced in thefe bodies, efpecially by nitric acid. Each fubftance muft form the fub- jeét of a feparate inveftigation ; and there cannot be a doubt but that much will be learned refpeéting their nature and properties, which hitherto have been fo little examined by chemifts. ) Utility of refine The alkaline folutions of refin may be found ufeful in fome ous folutionss of the arts; for many colours, efpecially thofe which are metallic, when diffolved in acids, may be precipitated, com- bined with refin, by adding the former to the alkaline folu- tions of the latter. I have made fome experiments of this kind with fuccefs; and perhaps thefe proceffes might prove ufeful to dyers and manufaéturers of colours. It is. probable alfo, that medicine may derive advantages from fome of this - extenfive feries of alkaline and acid folutions of the refinous fubftances. entire fubftance of lac is not however completely diffolved, as ap- pears from the turbidnefs of the liquors. Three of the four in- gredients, namely, the refin, the gluten, and the colouring extra, appear to be in perfect folution; whilft the wax is only partially combined with the alkali, and forms that imperfectly foluble fapo- naceous compound which has been formerly mentioned, and which remains fufpended, and difturbs the tranfparency of the folution. © From various circumftances, it does not feem improbable, that the long fought for, but hitherto undifcovered vehicle employed by the celebrated painters of the Venetian School, may have been fome kind of refinous‘folution, prepared by means of borax, or by the alkalis. A fanple SURVEYING WITHOUT INSTRUMENTS. 103° VU. A finple and accurate Method of Surveying on Shore, with fuch Lnjiruments only as are in every one’s Poffefion, By Captain J. Mortiocx. from the Author. To Mr. NICHOLSON. 28, Surry Place, Kent Road, SIR, 7th January, 1805. Amos all our treatifes on nautical furveying begin with Introductory the explanation and defcription of what are called the neceffary ae inftruments, which are defcribed fo numerous, and the price fo confiderable, that very few can procure them: Thus dif- couraged, they abandon every idea of making plans of fuch ports as they touch at, for want of what they conceive to be the neceflary inftruments. To obviate this difficulty, and to render nautical furveying more general, I have, in the annexed paper, attempted to fhew the mariner How to furvey any port or place he may touch at, with great accuracy, little trouble, and without any expence for inftraments. Should you find this fimple method deferving of a place in your valuable Journal, I fhall feel my- {elf honoured by your inferting it. lam, Sir, Your moft obedient humble fervant, J. MORTLOCK. stati FIRST make an eye-{fketch of the place to be furveyed, as Nautical furvey- the annexed figure, numbering all the points, bays, rocks, alias in- fhoals, &c. Choofe two ftations, as A and B (fig. 1, PlateV), ; whence all the rocks, points, &c. may be feen from, and fo. fituated from each other, that the bearings of the points, &c. as taken from A and B, fhall interfeét at angles at leaft greater than 10 degrees, but the nearer 90 degrees the better, + Having chofen the ftations, proceed to one of them as A, _ and place the paper intended to receive the plan horizontally before you, extended by pins, or otherwile, on a board fe- curely fixed, to prevent it fhifting its pofition while the bear- ings are drawing. Stick 104 Nautical furvey- ing without in- firuments. SURVEYING WITHOUT INSTRUMEDTS. Stick a pin through the paper firm into the board, at the part meant to reprefent the ftation A, and lay a ruler with a perfect ftraight edge on the paper, touching the pin at A. and pointing towards the ftation B, and draw the line AB: in like manner draw lines from A towards all the points, rocks, bays, &c. numbering the lines as the points, rocks, bays, &c. are numbered in the eye-fketch: Proceed next to the ftation B, and place the board horizontally before you, fo that the line A B fhall point back towards A, and fecure the board with the fame precaution as at A, to prevent its fhifting: then, in the line A B, ftick a pin firm through the paper into the board, in that part meant to reprefent the ftation B; from which point draw lines pointing towards the different points, rocks, &c. as was done from A, numbering them in like manner. Now, where the lines drawn from B interfeét thofe of the fame number drawn from A, will be the place of the points, rocks, &c. to which the lines were direéted to from the ftations. Sketch in the fhore between the sti &e. and the plan is completed. The meridian-line may be found by compals, or more cor- reGtly, by drawing the line of the fun’s bearing from one of the ftations, and taking his altitude at the fame time, Then with the latitude, altitude, and declination, compute the azi- muth, and lay it off to the left or right of the line of the fun’s bearing, according ‘as the fun was to the right or left of the meridian, and it will give the true north and fouth, or meri- dian-line. ) If the diftance between any two points on the fhore be meafured, it will give you a feale for the plan ; but it may often be found more convenient to meafure off a bafe, as AC, from one of the ftations, in a dire€tion nearly perpendicular to the line AB; and let it be in length equal to fome part of a geographical mile, as 380 feet = 3, or 760 =4, or 1520 = 4, or 3040 = 3, or any part of a mile; then will the line AC be a f{cale to the plan, I have fuppofed any common board and ruler to illuftrate the fimplicity of this method of furveying: but to fuch as are provided witha drawing frame, it will be found convenient to extend the paper on; and if a ruler has fights perpendicular to its edge, it will be found commodious, and require lefs trouble, I hope the eafe and expedition with which the whole 1§ WITRIC ACID. 105 is performed, will induce fea-faring people to amufe them- felves by taking plans of the places they touch at: for it is by the improvement of geography that the dangers of navigation are diminifhed, and, confequently, the lives and property embarked in our fhipping are lefs expofed to danger. ) J. MORTLOCK. IX. Notice of an Omiffion in Accum’s Chemifiry, of the direct Pro- duétion of Nitric Acid. By W.F.S. To Mr. NICHOLSON. SIR, Lincoln’s Inn, January 7, 1805. Havinc in your Philofophical Journal fpoken very hand- Nitre and nitric fomely, and not undefervingly fo, of Mr. Accum’s Treatife acid in Accum’s on Chemiftry, it would not perhaps be improper in one bree your enfuing Numbers, either to elucidate or correét a {mall difficulty, or rather error, in that book. In defcribing the mode of producing nitric acid, in the fecond volume of Mr. A.’s work, p. 286, he puts as a principal ingredient nitrate of potafh: Now, on referring to the mode of obtaining nitrate of potash in page 287, and following page, it is defcribed as being produced by neutralizing the carbonate of potath with nitric acid: Now, Sir, it is pretty evident, that the means of preparing either nitric acid or nitrate of potafh is not given, or rather it is {tated by implication, as incapable of being pro- duced by art. : Very refpeétfully your’s, W.Fe. P. 8. As this error can only be re&tified by a fabfequent edition, it would, with fabmiffion, be extremely beneficial to the holders of the .prefent edition, that you fhould introduce the emendation in your Journal. On 106 ON GALWANISM. Xs On Galcanifn. By Mr. Cusnures SYLVESTER, To Mr. NICHOLSON. SIR, Difficulties ree You did me the honour of inferting in your valuabie Oe kee. Toarhal, fome experiments tending to illuftrate the theory, of fition of water; galvanifm. Ido not know who originally propofed the idea Cath pa of the combination of electricity with hydrogen (the truth of switeg. which my experiments were intended to eftablifh), though I am now bound to acknowledge the ingenuity and importance of the thoughts Such an idea would perhaps never have been fuggefted, had it not been for the very paradoxical appear- ances attending the decompofition of water by galvanifm, The appearance of the hydrogen at fo great a diftance from the oxigen, both of which muft have been produced from the © fame particle of water, was very fatisfaétorily accounted for by this conjeéture. The continental philofophers, and Dr, Gibbes of Bath, did not fo well account for the phenomena by their hypotheiis, though it appeared fo formidable, as to threaten the theory of modern chemiftry with diffolution. Hypothefis of Another hypothefis of the decompofition of water, was Mr, Wilkinfon siven by Mr. Wilkinfon, in his Elements of Galvanifm, and eenfured., tage of all his very gratuitous data in accounting for the. de- compofition of water, the contradiétion with which they abound, will totally render his hypothefis invalid. Remarksinde- Mr. W. begins by fuppofing a particle of water analogous tailon Mr. W.’s to the Leyden phial, which is the fame thing as to fuppofe that hy pothefis, ity Ul é é : water, a conduétor of eleétricity, is compofed of particles in them(felves non-conduétors. Mr. W. is of opinion, that the decompofition takes place in the middle of the liquid between the points of the wires. The way in which he fuppofes the feparation to be effected, is fomething like the idea the an- cients had of the folutions of metals in acids, viz. that the metal was fplit into very minute particles (capable of being fufpended in .the liquid) by the wedge-like particles of the acid, After the decompofition is effected, he tells us that the capacity of the hydrogen is diminifhed for eleétricity, while in your 36th Number. If we even allow Mr. W. the advan-~ ee e, ¢ ON GALVANISM. 107 -while the capacity of oxigen is increafed for the fame fub- / ftance; two faéts for which I fhould be glad to know Mr. W.’s authority. He now fuppofes the oxigen to be attraéted by the pofitive wire, where it faturates itfelf with the eleétricity neceflary to conftitute its gafeous form. The hydrogen, on the other hand, is attraéted to the negative wire, to which it mutt give its excefs before its elaftic form can be effeéted. After ail the labour Mr. W. has beftowed to bring the hydro- Obje€tion, gen to one wire, and the oxigen to the other, he does not appear, in my opinion, to have fucceeded ; for the excefs of eleétricity in the hydrogen would be given to the deficient oxigen, and the gaffes would be given out in the middle of the liquid, and not at the ends of the wires. Mr. W. mentions the curious faét of water not being de- Water not de- compoled in a very {mall tube, and alfo, that no decompo- ‘°mpofed in a : 5 . air he very fmall tube. fition takes place when the wires in the liquid are as much as eight inches diftant from each other. I have long been in polfeffion of thefe faéts: I have varied thefe experiments by Satine folutions ufing, inftead of pure water, different folutions of falts, with are decompofed, a view to increafe the conduéting power of the liquid me- dium: I found a folution of carbonate of potath to anfwer Carbonate of very well: I placed the wires in the ends of a tube of more ae than a yard in length: The decompofition went on very ra- pidly : I foon theniéa the pofitive wire coated with beau- tiful carbonate of copper, at the fame time I obferved a ga- ~ feous fubftance difengaged: I found it, by the teft of lime- water, to be carbonic acid gas. I obferved the difengage- Pure potahh. ment of this gas, after I had rendered the potafh very cauftic by lime. I afterwards ufed a tube of th of an inch in diameter, Common falts and five feet long, into which J introduced a faturated folu- tion of common falt. After the wires were introduced, and the communication made, I obferved bubbles of hydrogen upon the negative wire, in about a minute after *. “IT remain, Sir, Fours, occ. _ CHARLES SYLVESTER. Sheffield, Jan. 20, 1805. * This corroborates the faét of the hydrogen pailing invifibly through the liquid. i 4 Reply 10s HORIZONTAL MOON, Xl. Reply to the Animadverfions and Experiments of C. L. onthe Sub- Jje& of the Horizontal Moon. By Mr. Ezex1en WaLkeER. To Mr. NICHOLSON, Dear Sir, W aat can have induced your correfpondent C. L. to attempt to confute my paper relating to the horizontal moon, with fo much invidioufnefs, is beft known to himfelf. For my own part, I believe that he is perfonally unknown to me, and that I am equally fo to him. Whether the The firft ftep that this faftidious writer takes to difprove the telefcope be pro- truth of my pofition is a falfe one. He fays, that * if Mr. PE iW. Walker’s pofition were true, the magnifying power of the theory, fame telefcope would vary with its aperture.” * C. L, has been very unfortunate in mentioning the telefcope, for the properties of that infirument will confute every argu- ment which he has ufed againft my theory, and fhow that his ill conducted experiments, like an zgnis fatuus, tended only te miflead him. The want of a I thall drop this fubje& for the prefent, {o examine his next ftandard would affertion in the fame paragraph. The apparent magnitude of ioe ae the paper before the eye may become larger, when the candle lefs ight gives a js fhaded with the hand, for any thing that C. L. knows to aia pee the contrary, as the increafe is too fmall to be perceived by our fenfes; and even if it were ten times larger than it is, it could not be known, becaufe every other object before the eye would increafe in apparent magnitude at the fame time, and in the fame ratio; and confequently leave no ftandard to com. pare the paper with. To elucidate this in a familiar way, permit me, Sir, toafk how would C, L. determine the number of miles between Trofton in Suffolk, and Soho-Square in Lon- don, without fome ftandard meafure, with which to compare that diftance. ie Stri@tures on Then follow his ‘‘ correct experiments of the fame deferip- C. L.’sexperi- tion as mine.””—My experiments were made to imitate the eye, - np: upon alarge feale. Let us fee how C, L. has imitated nature in his experiments, ) * Philof. Journal, Vol. IX. p. 235. ; n HORIZONTAL MOON. 109 In his firft experiment, ‘* from the flame to. the lens the dif- Exp. 1. The tance was 493 inches, and from the lens to the image it was yma $8 inches.”” Thefe numbers being reduced to the {cale of the human eye, it will appear that the diftance between the cry- ftalline lens and the retina, is nearly twice as great as be- tween the cryftalline lens and the object ;, confequently, if we take the diftance between the cryftalline and the outward fur face of the cornea into the calculation, thé objeét muft nearly touch the eye. This, I think, may be called @ jhort-fighted experiment. The conclufion of C. L.’s paper contains.a number of par- ticulars, in which he fuppofes I have erred, and then modeftly ** fubmits it to yourfelf and readers, whether I have acted con- fiftently with the rules of philofophical inveftigation,” &c. But as it will appear hereafter, that none of thofe errors had any exiftence, except in C. L.’s own mind, his conclufion can ferve no other purpofe than to fhew the temper and difpofition of the writer. In my paper which was honoured with a place in the 9th A more partica- vol. of this Journal, page 164, I only gave an abftraét of a A ee bee feries of experiments, on which I founded my general con- mer experiments. clufion; but it now appears neceffary to give a more particular account of them, to thew that they are entitled to more credit than C. L. has thought fit to give them. After having prepared my apparatus as defcribed in my paper above-mentioned, with a long mould candle of fix to the pound, placed in an inclined pofition, I began with mea- faring the focal image of the whole lens. The length of this luminous piéture upon the fcreen, was determined by a pair of compaffes, and a diagonal fcale of inches, This meafure was entered on page 1 of a book, pre- pared for that purpofe. The card No: 1. was then placed before the lens; the luminous picture meafured in the fame manner as before, was entered on page 2 of the fame book. The mealure of the piéture given by the aperture, No, 2. was entered on the 3d page. And the meafure of that given by No. 3. was noted down on the 4th page. As foon as thefe four experiments were finifhed, I began again with the whole lens, and entered a fecond meafure on page 1. under the firft, and continued till I had obtained two meafures 110 HORIZONTAL MOON. meafures on each page: and in this manner, I continued my experiments until I had-obtained five or fix meafures to each aperture. This mode gave me an opportunity of feeing how much the flame of the candle altered in its length, during the time that I was making the experiments, which alteration was too {mall to be regarded. The meafures on each page being added up, and divided by the number of them, gave me thofe numbers which were inferted in my paper. 2 But I did not ftop here, for fets of experiments were re- peated in the fame manner, on feveral évenings, to afcertain the faé& more clearly, But to come more immediately to the point; when the fun or moon was ufed initead of a candle, the fame refult was obtained, viz. the Breall aperture gave the greatefi luminous piéture. . Principles of The truth of this property in optics, however, does not optics brought wholly reft on my experiments, the fame conclufion ‘may be in fupport of ‘ Lae the author's derived from other principles. theory. | It is a well known property of the telefcope, that ‘as the The pencils of 2 : ; tight that enter aperture is contraéted, the flender pencils or cylinders of rays \ the eye are that emerge from the eye-glafs into the eye, are alfo contraéted Sa ae in the fame proportion,” * tureof thevb- © Fhe magnifying power, of the objeét glafs of a telefcope EEE is not increafed by increafing its aperture ; but by increafing itsaperture, you increafe the magnitude of the pencil of light in its focus: for as the eye-glafs remains the fame, the increafe in magnitude of the emerging pencil of rays, muft depend upon an increafe in magnitude of the pencil in the focus of the —whence itis Objeétglafs. Confequently, when the moon is viewed, if the inferred that the anerture of the objeét glafs be increafed, the piéture of the el tecpeal moon within the telefcope, will be increafed in the fame ratio; changed in fize. but without increafing the magnifying power of the inftru- ment. For the liga power is == the diameter of the aperture of the objeét glafs divided by the diameter of the emerging pencil, Demonftration. Let A =the diameter of the aperture of the objeé glafs, B =the diameter of the emerging pencil, C = the focal dii- * Elementary Parts of Smith’s Optics, page 93. ~ : tance — PERSPECTIVE INSTRUMENT, lit tanice of the object g wits and D the focal diftance of the eye- Grae Then-~ =a the ricbaklvine power. ButC:D::A:B. (Smith’s Optics, p.93.) And by di- vifion <= -. Therefore the enlargement of the pidure of an objeét within the telefcope, does not viper its mag- nifying power. Hence thefe properties of the telefcope prove to a demon. Conclufion, ftration, that the conclufion which I have drawn from my experiments is a law of vifion; and this law fhows us, that no concavity of the {ky; no terreftrial perfpective, nor even the painting of the waves under Black-Friar’s Bridge, can explain the phenomenon in que(ftion *. The caule lies wholly within the eye. > It isa moft unpleafant tafk to enter into controverfy, but I Refpecting cone cannot fee how I could avoid it in this inftance. It-appears oo ine, Sir, that you inferted C. L.’s paper fer me to anfwer, and I have complied; hoping, however, that this is the la{t time of my having occafion to ufe my pen, againft an anony- “mous writer, Common juftice feems to demand the names of thofe who undertake the examination of fuch papers as are owned by their refpeétive authors. Iam, Dear Sir, Your moft obedient fervane, ne EZ, WALKER. Lynn, Jan. 18, 1805. ; XII. aa of a fimple Inftrument for making corre Drawings from Nature. By T. C. B. \ To Mr. NICHOLSON. SIR, January 22, 1805. SIH fctiption of two infruments for facilitating dand- fcape drawing from nature given in the firft volume, page 281, of your Journal, has fuggefted to me the conftruction of * Philofophical Journal, vol. IX, page 237. : another, 112 Inftrument for making correct drawings fron: mature. PERSPECTIVE INSTRUMENT. another, which feems to unite the accuracy of the firft of thofe inftraments with the fimplicity and portability of the fecond. As I conceive it may be of fome fervice to thofe who are in the habit of fketching landfcape, I fend you a defcription of one which I have had made, that you may, if you think pro- per, publifh it in your Journal. Let AB, Mig. Il. Plate 5. be a flat rule, fuppofe twelve inches long, having at its ex- . tremities two arms B D and AF turning upon a joint at Band ‘A; and in each arm a circular joint at Cand G: let the length of each arm B D and A F be ten inches: a handle to fix on E, and a thread pafling through two holes equidiftant from the handle, making any length, according to the angle under which the view may be beft feen. To ule the inftrument, take the end of the thread in the mouth, and hold the inftrument upright before the eye, then move either or both of the arms till the points D and F are brought in a line between the eye and any point in the land- {cape you may with to delineate; lay the inftrument upon the drawing paper, and you will have the true fituation of fuch part of the fubjeét.—Proceed in like manner, taking care al- ways to keep the bafe line in the fame place, till you get as many points as you require, by which means any landfcape or building may be drawn very expeditioufly, and with a great degree of accuracy. To make the inftrument as portable as poffible, there is a joint in AB, which the handle covers, and the pieces DG and C F are made of thin brafs, to fold into the pieces AC and BG; fo that the inftrument, when folded up, need oc- cupy no more room in the pocket than a fall fpeétacle cafe. It is perhaps unneceflary to add that this inftrament may be ufed for the purpofe of copying, and anfwers the purpofe of a triangular or quadrangular compafs. Lee Lam, Sir, Your moft obedient and humble fervant, i ie if the rough inclofed fketch of the inftrument is not fuffi- ciently intelligible, Mr. Nicholfon may fee one at Mr. Frazer’s, Optician, in Bond-Street, Obfervations OBSERVATIONS ON BASALT, &ece 113 Xl. Obfervations on Bafalt, and on the Tranfition from. the vitreous to the fiony Texture, which occurs in the gradual Refrigeration of melted Bafult ; with fome geological Remarks. In a Leiter from Grecory Warr, E/y. to the Right Hon. Cuarves Greviirte, V.P.R.S§. From the Philofophical Tranfuétions ie for 1804, p, 279. STR, Soho, April 1804. Tur important geological confequences that feem de- Sir James Ha'l’s ducible from the changes of texture developed, by Sir a1 A aE Hall’s very judicious experiments on the regulated cooling of lation of fufed melted bafalt, induced me to attempt a repetition of them, >aflt fome time after the publication of his interefting and ingenious paper. * I believe that formerly I had the honour of fhowing you fome of the refults of my imperfe&t and diminutive ex- periments, which only ferved to afford additional proofs of the tranfition from the vitreous to the ftony texture, which takes place in the gradual refrigeration of glafs. Circumftances have prevented my refuming thefe inveftigations, till it lately occurred to me that fomething might be learned, by expofing to the ation of heat; a much larger mafs of bafaltic matter than, as far as I am inforn:ed, had ever at one time been fub- jeGted to experiment, . One of the common reverberatory furnaces ufed in iron The experiment founderies for the fufion of pig-iron, was ftrongly heated by {ge meh fire maintained for feveral hours. About feven hundred weight rag. eh _ of amorphous bafalt, here called Rowley Rag, was broken into fmall pieces, and depofited gradually on the elevated part of the interior of the furnace, between the fire and the chimney, from whence, as it melted, it flowed into the deeper part, in which, in ordinary operations, the melted iron is colleéied, It was obferved by the perfons attending, that it did not re-1t was eafily quire half the quantity of fuel to fufe the bafalt, that would Pen gs have been neceflary to melt an equal weight of pig-iron. when quickly | When the whole was melted, it formed a liquid glafs, rather‘ooled. © Publithed in the Tranfa&tions of the Royal Society of Edin- burgh, Vol. 'V. and in our Journal, Vol. V. quarto feries. Vou. X.—Fesruary, 1805. I tenacious, 114 OBSERVATIONS ON BASALT, &e. \ tenacious, from which a large ladle-full was taken, which, on being allowed to cool, retained the characters of perfeét glafs. The fire was maintained, though with gradual diminution, for more than fix hours; after which time, the draught of the chimney was intercepted, the furface of the glafs was covered with heated fand, and the furnace was filled with coals, which Slow congela- were confumed very flowly. It was eight days before the ar mafs in the furnace was fufficiently cool to be extraéted, and even then it retained confiderable internal heat. Appearance of = The form of the mafs, being given by the bottom of the rs furnace, was confiderably irregular, approaching to the fhape of a wedge whofe lower angles were rounded. It was nearly three feet anda half long, two feet and a half wide, about four inches thick at one end, and above eighteen inches at the other, From this diverfity of thicknefs, and from the unequal aétion of the heat of the furnace, too great an irregularity had pre- vailed in the refrigeration of the glafs, to permit its attainment of a homogeneous texture. ‘Thefe circumftances might proba- bly have been counteraéted by better devifed precautions; but the inequality of the produé is not to be regretted, fince it has fortuitonfly difclofed fome very fingular peculiarities, in the arrangement of bodies pafling from a vitreous to a {tony ftate, which might have remained unobferved, if the defired homo- geneity of the refult had been obtained. I fhall now endeavour to defcribe the various products of this operation ; and I fhall alfo fubmit to your confideration, fome remarks which appear to me to arife naturally from the phenomena I have obferved ; premifing that, except where my opinions are fupported by the unequivocal demonftration of faéts, I offer them with the utmoft deference to the decifion of more experienced and judicious mineralogifts and geologitfts. External charace Lt may be proper to give a concife defcription of rowley rag ters, &c. of — itfelf before I confider the produéts which it yields by igneous rowley 128. fufion. This fpecies of befalt is fine-grained, of a confufed cryftallized texture ; its fraéture uneven in fmall pieces, con- choidal in large pieces. Its hardnefs fuperior to common glafs but inferior to feldfpar. Its tenacity confiderable. Its aétion on the magnetic needle firong, but without figns of polarity, Its fpecific gravity, according to my trials, 2.868. “Its general colour iron gray, approaching to black, Itis opaque; and it 4 reflects OBSERVATIONS ON BASALT, W&c. 115 _refie&ts light from a number of brilliant points, fome of which feems to be teldfpar, and the others hornblende. * 1ft. This fubftance is eafily fufed into glafs, whofe texture is Its glafs. completely vitreous, with few air-bubbles. Its fra€ture undu- lated conchoidal. Its hardnefs fuperior to feldfpar, but inferior to quartz. It poffeffes fcarcely any ation on the magnetic - needle. Its colour is black: it is nearly opaque, being tranf- lucent only in very thin fragments, Its {pecific gravity ap- pears to be 2.749. 2d. The tendency towards arrangement in the particles of eae appearance the fluid glafs, is firft developed by the formation of minute Boal eke globules, which are generally nearly fpherical, but fometimes appear in the elongated, and which are thickly diffeminated through ther mafs. The colour of thefe globules is confiderably lighter than that of the glafs; they are commonly grayifh-brown, fome- _ times inclining to chocolate brown, and, when they have been formed near the interior furface of the cavities in the glafs, they projeét, and refemble a clufter of fmall feeds. Their diameter rarely exceeds a line, and feldom attains that fize, as, in general, they are fo near to one another, that their furfaces touch before they can acquire confiderable magnitude. In the procefs of cooling, they adapt their form to their con-~ fined fituation, fill up every interftice, and finally prefent a - * ¢¢ The ragftone has been accurately analyfed by Dr. Withering, Analyfis of row- who found that 1000 parts of it contained 475 parts of filiceous ley rag by Dr. earth, 325 argillaceous earth, and 200 calx of iron; but this iron Withering, feems to me to be in a very fimall degree of calcination, from the dark blue colour of the ftone, from the rufty colour it affumes on _ being expofed to a farther ftate of calcination by air and water, and _ from the magnetic property of the mountains, which, as Dr. Plot obferved, turned the needle 6° from its proper direé&tion. This magnetic property has fince been obferved in feveral bafaltic moun- tains, particularly in the Giant’s Caufeway in Ireland, and very remarkably in a bafaltic columnar mountain called Compafs Hill, in the ifland Cannay, one of the Hebrides, defcribed by George Dempfter, Efq. in the Tranfaétions of the Society of Antiquaries in Scotland, Vol. I.” See Mineralogy of the South-weft part of. . ‘Staffordfhire, by James Keir, Efq. F. R. S. pene in Shaw’s Hiftory of Staffordfhire, Vol. I. "Mr. Kirwan ftates the fpecific gravity of rowley rag, which he calls ferrilite, at 2.748; and affigns its melting point at 98° of Wedgwood’s pyrometer. cn : 12 homogeneous 116 OBSERVATIONS ON BASALT, &e. homogeneous body, wholly unlike glafs, and equally unlike. the parent bafalt, When the union of the little globules has. been imperfe@ly effeGed, the fra€ture of the mafs indicates its flru€tare, by numerous minute conchoidal fraétures, which difplay the form of each globule. But, if the arrangement has extended a little farther, all thefe fubdivifions are entirely loft; the mafs becomes perfectly compact, has an even or a flat con- choidal fraéture, is nearly of the fame hardnefs as the glafs, is commonly of a chocolate colour, graduating into a brownith- black, and the intenfity of the colour increafes in proportion to It refembles jaf- the degree to which the arrangement has extended. Its afpeét on enendte is rather grealy ;, andit much refembles fome varieties of jafper action. in the‘compactnels of its texture, and in its opacity. Its mag- netic aétion is extremely feeble. Its fpecific gravity appears: to be 2.938, Y More advanced 3d, If the mafs were now rapidly cooled, it is obvious that ag eaeie the refult would be the fubftance I have juft defcribed; but, ture. if the temperature adapted to the farther arrangement of its particles be continued, another change 1s immediately com- menced, by the progrefs of which it acquires a more ftony texture, much greater tenacity, and its colour deepens as Darker coloure thefe changes advance, till it becomes abfolutely black. Sometimes this alteration is effected by a gradual tranfition, the limits of which cannot be affigned, but more generally by the formation of fecondary fpheroids, in the heart of the compact jafpedeous fubftance. Thefe fperoids differ effen- tially from thefe firft defcribed ; the centres of their formation are more remote from each other, and their magnitude is pro- portionably greater, fometimes extending to a diameter of iwo inches, and feeming only to be limited by contaét with Large {pheroids the peripheries of other fperoids. They are radiated, with omen ‘X= diftin@ fibres; fometimes the fibres refemble thofe of brown hzematites, and fometimes they are fafciculated irregus _ larly, fo'as to be very fimilar in appearance to the argilla- ceous iron ores rendered prifmatic by torrefaGtion. They are’ generally well ‘defined, and eafily feparable from the mafs they are engaged in; and often the fibres divide at equal diftances from the centre, fo as to, detach portions of the fperoid in concentric coats. The tfanfverfe fra@ture of the fibres is compaét and fine grained; the colour black; and the hardnefs.fomewhat inferior to that of the bafaltic glafs. When two OBSERVATIONS ON BASALT, &c. 117 two of the fpheroids come into contadt by mutual enlargement, no intermixture of their fibres feem to take place; they ap- Contact with pear equally impenetrable, and, as neither can penetrate, Poe both are compreffed, and their limits are defined by a plane, drons. at which a feparation readily takes place, and each of the fides is invefted with a rufty colour. When feveral fpheroids come in contaét on the fame level, they are formed by mutual preffure into pretty regular prifms, whofe divifion is perfeétly _ defined ; and when, a fpheroid is furrounded on all fides: by others, it is compreffed into an irregular polyhedron. 4th. The tranfition from this fibrous ftate to a different ar- Third arrange- rangement, feems to be very rapid; for the centre of moft of tony ee the {peroids becomes compact, before they attain the diameter great tenacity, of half an inch. As the fibrous ftruture propagates itfelf by arse cian aa a ‘ genetic radiating into the unarranged mafs, the compact nucleus which a@ion, fupplies its place gradually extends, till it finally attains the limits of the fpheroids; and the fame arrangement pervades the matter comprehended between them, The mafs has now afflumed a compaét {tony texture, and poffeffes great tenacity. _ Its hardnefs is fomewhat inferior to that of the glafs from which it was formed. Its aétion on the magnetic needle is very con- fiderable. Its fpecific gravity is 2.938. Its colour is black, inclining to fteel gray: it is abfolutely opaque, and only re- - fle&s light from a few minute points. Though the divifions between the {pheroids are rendered imperceptible to the eye, they are not obliterated, and their rufty furfaces are often dil- clofed by an attempt to fracture the mals. _3th. A continuation of the temperature favourable to ar- Granular texe rangement, {peedily induces another change. The texture ‘’* of the mafs becomes more granular, its colour rather more gray, and the brilliant points larger and more numerous: nor is it long before thefe brilliant molecules arrange themfelves into regular forms; and, finally, the whole mafs becomes per- vaded by thin cryftalline lamin, which interfe@ it in every Cryfaliine lami- direGtion, and form projeGing cryftals in the cavities. The hardnefs of the bafis feems to continue nearly the fame; but the aggregate action of the bafis, and of the imbedded cryf- tals, on the magnetic needle, is prodigioufly increafed. It Polarity, appears to poflefs fome polarity; and. minute fragments are fafpended by a magnet, Its fpecific gravity is fomewhat in- Increafed den- Greafed, as it is now 2,949. The cryftals contained in it, #*Y bs when 118 OBSERVATIONS ON BASALT, &c. when examined by a microfcope, appear to be fafciculi of flender prifms, nearly re€tangular, terminated by planes per- pendicular to the axis; they are extremely brilliant; their colour is greenifh-black; they are harder than glafs, and fufible at the blow-pipe; they are fufpended by the aétion of a magnet. They are arranged nearly fide by fide, but not accumulated in thicknefs, fo that they prefent the appearance of broad thin lamin ; they crofs one another at all angles, but always on nearly the fame plane; and the lamina thus formed is often three or four lines Jong, and from a line to a line and a half broad, but extremely thin.* It feems obvious, that an equalized temperature would have rendered the whole fimilar to the fubftance laft defcribed; and it may be fairly inferred, that by a continuance of heat, the minute cryftals would have been augmented in their dimen- fions, by the acceffion of molecules ftill engaged in the bafis, or by the union of feveral cryftals, till they acquired fufficient magnitude for their nature to be abfolutely determined by the ufual modes of inveftigation, It is probable, however, if fuch “precautions had been taken as might have fecured this degree of perfection in the ulterior refult, that the mafs would only have exhibited an uniform afpeéct, and that the interefting ini- tial phenomena would not have been difcovered.+ There * It may be obferved, that the cavities which exifted in the glafs are not obliterated during the fubfequent proceffes, though their interior furfaces undergo fome change. The minute globules firft formed often become prominent, and projeét into the cavities. Thefe minute points are foon obliterated by the large curves of the fibrous {pheroids, which give a mamellated form ‘to the interiors of the cavities; and, when the cryftals are generated in the mafs, they fhoot into fome of the cavities, and line them with their bril- liant laminz. _ +t Inthis and the fucceeding paragraphs, the word molecule is ufed in the fenfe affigned to it by Hauy and Dolomieu, and is un- derftood to reprefent the peculiar folids, of definite compofition and invariable form, the accumulation of which, forms the cryftals of mineral fubftances. Such molecules, preferving their form and their effential charaéteriftics, may be extracted from moft cryftals by mechanical divifion, and may be fubdivided as far as our fenfes can recognife them. Though we cannot by mechanical means di- rectly divide them into their elementary particles, we are enabled _ to OBSERVATIONS ON BASALT, &c. J19 There are fome confiderations which appear to offer a par- Explanation of - tial explanation of the formation of the globules, and of the a Fee abe radiated {pheroids. It is well afcertained that heat is emitted fpheroids ;) from by all bodies, in their change from a gafeous to a fluid ftate, aa Greece 5 . : : 4 . heat during con- and alfo in their change from a fluid to a folid ftate. It is gelation. reafonable to {uppofe, that heat may alfo be emitted in thofe ehanges of arrangement which affeét the internal texture of a body, after it has attained an apparently folid ftate. That a fucceffion of fuch changes does a€tually take place, appears to me demonftrated by the appearances I have defcribed, and by the increafe of fpecific gravity, which feems to keep pace with the internal changes of the fubftance. It would appear, that thefe changes are caufed by a gradual diminution of tem- perature, which permits certain laws to induce peculiar ar- rangements among the particles of the glafs. When feveral of thefe particles enter into this new bond of aflociation, they muft form a minute point, from which heat muft iffue in every direétion. ‘That heat will gradually propagate itfelf, till the temperature of the glafs is equalized; and then the recur- rence of the circumftances which induced the firft particles to arrange, will caufe other particles to arrange alfo, which the attraction of aggregation will, difpofe round the point firft formed. =>=*=0—_0_0$S999M0MSmMmS XVI. Letter from Joseru Huppart, Eg. F. R. 8. on the apparent Enlargement of the Moon at low Altitudes, To Mr. NICHOLSON, Dear Sir, 139 Ir was not until yefterday that I received your Journals, tntroduGion. Nos. 36 and 37; In the former, reading a letter from C. L. occafioned my referring to No. 35, page 164, of the Journal, for Mr, Walker’s letter refpe&ting the fenfible magnitude of the e 140 APPARENT ENLARGEMENT OF THE MOON, the horizontal moon above what it has in the zenith; and therefore prefent you with the idea I have entertained upon the fubjeét. . Eftimate of mag- I am of opinion that the magnitude of any objeét can only nitude conbnet -be eftimated (as to fenfe) according to the {pace or magnitude see duct the be eftimated (as to fenfe) according Pp image on the of its image upon the retina. The eye muft (if this is ad+ tis mitted), therefore, be the fole caufe of the illufion, for the moon’s apparent magnitude increafes as fhe rifes towards the zenith, : Theeyeisform- The eye by the power of the mufcles can, at the will of the sniial et obferver, not only be direéted towards the obje@, in order to but alfo its focal receive its image upon the ufual part of the retina, but acquire eae of 2 Proper convexity for diftinét vifion, or focus of the refraGted the eye will en- rays upon the retinas and alfo to contraét or extend the area bree Pas of the pupil according to the quantity of light. This admi- ae hese rable property may be obferved by every one in pafling out of remains unal- a light room in the night, and alfo in the eyes of the brate se creation; but I conceive, that while the area of the pupil is enlarged in order to receive a greater quantity of light, the eye is protruded, or the focal diftance between the pupil and retina is increafed, which increafes the fenfible magnitude of the object, as the image upon the retina conveys it to our fenfes, when viewed by the naked eye. This I diftinguith from apparent magnitude, which we ufe when actually inea- fured by an inftrument. A Variation of the Fhe variation in the magnitude of the image upon the pupil, or of the yetina, certainly cannot arife from the variations in the dimen- ene frons of the pupil, which is contrary to the law of dioptrics; alter the image. for, on oblerving the fun, I do not admit light through one-twentieth part of the area of the objeét glafs, which ts 3.8 inches in diameter, and yet there is not any difference .m the apparent diameter; or, whether the rays are admitted at the center or any other part of the object-glafs, the obferva- The elongation tions are equally good, But I confider itas natural confe- of the eye is fup- quence, that when the pupil of the eye is enlarged, the focal oa saa diftance is increafed, and which conftantly arifes from a dimi- the pupil isen-. nation of light, even without our attention; but thereby our farged 5 fight is affifted in confequence with more light and power, which is fome compenfation. and as this takes. Lhe light from a celeftial obje@ near the horizon, is dimi+ place when the nifhed by paffing a long diftance through a grofs atmofphere ; ynoon is leaft lu- 5 hence LACTIC ACID. 141 hence a fenfible enlargement takes place in the moon as'well minous, it then as other bodies, which diminifhes as (the altitude shevadesy eo wert: and the light lefs interrupted. Tam, Sir, 4 Your moft obedient, J. HUDDART. Highbury Terrace, fan. 28, 1805. XVI. A Bho 3 on Milk and the Laétic Acid, By Cit. BourrtoN s LaGRANGE™*, SEC TIO N + ) The prefent State of ow Knowledge refpecting the Lagtic Acid. SCHEELE and Deyeux, and Parmentier, are the chemifls Hiftory of expe- who have moft contributed to our knowledge of the acid of i oe milk. of difcoveries, The experiments made before the time of thefe fkilful phi- ** lofophers, are thofe of Hoffman, Boerhaave, Homberg, Geoff- roy, Rouelle the younger, and Baumé. But the analyfis of animal matters was then in fuch an imperfeét ftate, that little can be gathered from their experiments. Sch bere direéted his labours with very different views. His Scheele. wellconduéted experimentsled him to determine the charaéters and properties of an acid afforded by the ferum of milk But : “not withftanding the labours of this celebrated man, we have -fome fubjeéts of inquiry left for examination. . Befides the great number of its faline compounds, as ree Imperfe&t Rate croy remarks, which are ftill wanting to the fcience, Lehale has of 0u" know- ledge of the i i lactic acid. * *® Annales de Chemie, No. 150. vol. 50. _JaStic, aide ' The author in a note mentions his haying learned on the even- ing when his Memoir was read, that Meflrs. Vauquelin and The- nard had each been feparately employed on the fame fubjeét: and - on that occafion he then finds its neceflary to fay, that’ molt of the experiments he defcribes, are the refult of obfervations made by ‘ feyeral pharmacian s, at the fitting of the fociety of pharmacy, the 15 Nivofe, in the year 12. The verbal procefs of that day, figned_ by Parmentier, prefident, Mig Delunel, fecretary, of which an ex-_ tract was fent to the Philomathic Society, a{certains the experiments he had then made, and the obfervations of of the feveral members of the fociety of Pharmacy. not 142 LACTIC ACID. not pointed out the ation of fire upon this acid, nor its fpon- taneous alteration in the air, the manner in which it comports itfelf with the nitric acid, &c. It is not known whether it be totally decompofed by this laft, or converted into fome other acid, particularly the oxalic acid. We are entirely un- acquainted with the nature of its compofition. Though it prefents properties which refemble thofe of the acetous acid, and lead to the probability that it nearly refembles it; we cannot yet rank it with the vegetable acids. On the other hand, nothing decifive can be afferted with refpeé to its ani- mal nature, becaufe no experimgnt has yet indicated the pre- fence of azote, and it is yet unknown, whether it may afford ammonia in its decompofition ; whether.it be putrefcible, or convertible into pruffic acid, &c. This general ftatement while it gives us a view of our knowledge of the laétic acid traces, as it were, the fteps ne- ceffary to be purfued in determining the place which this acid ought to occupy, as to the number of well eftablifhed chemical facts. : SECTION II. Concerning Milk and the cafeous Matter. On milk, andits Before I proceed to defcribe the experiments I have made Rondicucnt on this article, it will be ufeful to prefent fome refieétions pres on milk, and its conftituent parts. Guiton, in the Encyclopédie Methodique, offers two quef- tions refpeéting the exiftence of an acid in milk, He ex- preffes himfelf thus : Whether whey Does the whey exift in milk fuch as it is found after the fe. exifts ready = paration of the other conftituent parts? Does it manifeft acid vanes oer properties on any other account, than becaufe it holds, falts in folution, as all the analyfes fuppofe ? Milk cannotbe If whey, adds the fame chemift, exifted in milk, in the ftate reproduced by it exhibits after the feparation of the butter and eheefe, we the mixture of its partss fhould be able to reproduce milk by mixing thefe three prin- ciples again inthe fame proportions. But as this is not the cafe, he concludes, that whey is the produé of a true fermen- tation. f The examination of this firft queftion founded on experi- ment, ought, I think, to prove that it will not be fufficient to fhew whether whey exifts in milk, that we fhould mix the three principles in the fame proportions, and re-produce that. fluid ; firft, becaufe thefe principles are no longer the fame; and LACTIC ACID. 143 and fecondly, becaufe whey formed by the ufual procefs, is more or le{s acid. Experiment 1. Recent milk gives a red colour to the paper Exp. 1. Milk and the tinéture of turnfole. Lat eeeoars Experiment 2, If milk be diftilled in clofe veffels, and the at erreien product feparately taken, the firft is not acid; the fecoend tillation, end reddens turnfole, and flightly precipitates the nitrate of filver ; omtiaues acid, and the third has no aétion on the tin€ture. At this period, the milk is not yet decompofed, but ftill reddens turnfole, It appears that the remaining aeid is no longer volatile, but, is retained either by the animal matter, or hy fome other fub- fiance, _ Experiment 3. If milk be coagulated with a mineral or ve- Exp. 3. Whey _ getable acid, the whey is emakated, Wilhvut retaining a par- ee nad ucle of the acid made ufe of. retains none of ” I muft however obferve, that fome deception would fol- ‘Be 20! itl low, if the ferum only were examined, which is obtained. by the fulphuric acid, or by allum, becaufe the precipitate afforded by barytes, is not entirely re-diffolved by the nitric acid. I am fatisfied that this arifes only from a {mall quantity of ful- phurate of potafh contained in the ferum, as is evidently proved, when the whey is feparated by any other fubftance not of an acid nature. ‘It is not true therefore as many chemifts have ndudiibed: that Exp. 4. Whey ° the acid feparates the cafeous matter, by uniting with the ferum, 70" mille fpon- taneoufly de- Experiment 4. If milk be expofed tothe air at the tempe- compofed, is ale rature between 12 and 20 degrees (about 66° Fahrenheit) the, 2“ feparation takes place in inenty ale hours. The curd has amore acid flavour than that of experiment 3. Hot water caufes it tolofe its four tafte, and acquires the property of reddening turnfole, We here find nearly the fame properties in the cheefy mat- ter, when fpontaneoufly formed, and when feparated by acids, Experiment 5. The fame experiment being made with the Exp, 5. Milk .. pneumatic apparatus, was attended with no abforption of air, oe or difengagement of elaftic fluid. The only difference was, neither abforbs that the feparation of the cheefy matter did not take place for P°" ives out air. feveral days. Part floated on the liquid, and the other occu- pied the bottom of the veffel. Experiment 6. A bottle was filled with frefh milk, and well Exp. 6. Mit corked. Some days afterwards, the cheefy matter had fepe- Aa: 4 tated. Asfoon as the feparation was complete, the cork was bottle, gives car- utended tobe extraGted, but it flew out with violence and bonic acid. noife, 144 LACTIC ACID. noife, indicating the prefence of an elaftic fluid. Upon fhaking the bottle, a greater quantity of gas was difengaged, which being colle€ted and examined, had the fame chara@ers as carhuhiies acid, The fluid as well as the curd had a fharp acid tafte, aibich became iefs pungeut, as the carbonic acid was difengaged by agitation. The duid, after having been heated, did not appear to be more acid than ferum, obtained by expofing milk fot the fame time to the air. » The fame experiment. was made with milk which had been boiled about half an hour, and the refults were the fame. Exp. 7- Quali- Eperiment’7, The cheefy matters of the third, fourth, and ties of the fifth experiments, differ effentially in tafte and confiftence. Chenin That of No, 3. is dry and firm; that of No. 4, is more divided, lefs dry, and partly foluble in water; and laftly, that obtained in the experiments No. 5 and 6. is not clotted, but is more light, and does not unite into a mafs, till after feveral hours. The cheefy matter, therefore, requires particular proper- ties, according to the fubftances and the procefles employed to feparaie the ferum. Deduétions from Thefe firft experiments lead us to the following refle@ions, shel that, 1. Milk does not require to be decompofed, in order to manifeft the prefence of an acid, 2. That this acid is mixed with falts, fugar, and animal matter. 3. That the acid in milk is difengaged, though it is not very perceptible, but by re-agents. 4. That the contaé of the airis not neceflary for feparating the conftituent parts of milk. 5, That the coagu- lating {ubftances merely facilitate the feparation of the cheefe, either by forming a new compound, or by more immediately condenfing the particles together, when the cheefy matter re- quires new properties: or lafily, by expofing the milk to the air. By degrees, a part of the fugar of milk is decompofed ; carbonic acid is formed, of which one part is difengaged, and the other facilitates the feparation of the curd; caloric alfo favours the attra€tions of coagulating matters for the curd. They all a@ differently, for alcohol, which alfo poffeffes: this property, affords other refults; the curd being to a certain point foluble in water. We cannot therefore as chemifts have ‘ aferibed thefe effeéts to the folution of thofe fubftances in water, and their greater attra€tion for the i bn than is- ex~ erted by the cheefy matter itfelf, (To be continued.) 2 * AS, ba eyed W * ig Bef ale! a) Sete ot liao Doe ee a ; Ay P Mhutley pel Cag | “ 4 fo < ae - “= nN | : B D | -j le us we Su 7 ae i THI : ae l > tei ' ' | a Oy i . :. 2 os ti / ; be i 4 | pes ee NS ca a Miutlow Se Rupedl ee Philos. Journal Val XPUWp dd. “ Miuttow Se. Rafiedl Be — Fry ses EMR ees he, MOL eR CRS Ria. VPN is 4 a oT, TN oe ky) Ee nD Ae Ee i Are ’ me x : ay Pen ya! toa Philos. Journal.Vo.X. PU. Vp. 114. 2 Cpt Mortlrck:i Matheds ‘lk. aime Yel. Merllocks Sa | | , re ; ? . ° fmwying, a oT sn) ele ee | [oy ee ‘ oe | -~ i " B | 3 , 2 | can = Uj bo ly ty ry : 9X in | m 3m om | of - ¥ | . ea Mi i A Pexcee | ” oe ‘ | aa + f N ae | &. A [i i \ | | ee | iS | CUrstrument for lahing . , Cy \ CRA , ; OM no Jeon " ioe Volare: - = er i See So Rufreii @t 5 ‘ we sy Stas AL wl ,A JOURNAL OF NATURAL PHILOSOPHY, CHEMISTRY, AND THE ARTS. MARCH, 1805.- ARTICLE I. Hiftorical and Critical Objervations relating chiefly to the In- vention of the Telefcope. Ina Letter from E. O. : To Mr. NICHOLSON. : SIR, Aruoucu I was aware that the experiment on the in- Incompreffitility compreflibility of water was to be found in Lord Bacon’s ° ter work, yet I was happy to feethat Sir H. Englefield had taken - ' the trouble of reminding your readers of the original inventor of it. Iam always glad when I fee any thing which may re- call our attention to the works of our illuftrious countryman. | They abound with inftru€tion, and, in many inftances, his con- jeétures may be compared to the Queries of Sir I. Newton, which contain the foundations of the greateft difcoveries. In the fame paper Sir H. Englefield has given us a very cu- Remarks on the rious paflage from Kepler; and although I cannot perfuade cee myfelf that he is accurate in his interpretation of it; yet I Englefield and think the argument has been by no means LR ftated Aletes. _by Aletes*. I fhall therefore beg your permiffion to infert fome additional remarks on a fubjeét, which certainly poffeffes aconfiderable fhare of intereft, I muft beg leave; likewife; * Vol. X. p. 92, Vor, X.—Marcu, 1805, L pres 146 ON THE TELESCOPE. Obfervations previoufly to remark that SirH. Englefield has not afferted relating to the telefcope. \ ~~ eae that Kepler was the original inventor of the telefcope. The invention of the 5 only inference which can be juftly drawn from his words, is that they were invented as early as the year 1607. No one, indeed, who had attentively read Kepler’s dedication of his Dioptrice, could have entertained fuch an opinion. He pre- cifely ftates * that fince *‘ ad magnum cumulum inventionum hujus ultimi fseculi acceffiffet Arundo Dioptrica, nequaquam inter valgares commemoranda machinationes, circaque eam, alii de palma primz inventionis certarent, alii de perte€tione inftrumenti fefe jaGtarent, . . . . Galilzeus vero fuper ufu pa- tefaéto in perquirendis arcanis Aftronomicis fpeciociffimum tri- umphum ageret; . .. . Ego duétushonefla quadam zemulati- one novum mathematicis campum aperui.... . caufarum lege geometrica demonftrandarum quibus . . . effe€tus inni- terentur.” Before the invention of telefcopes, aftronomical obferva- tions were fometimes made with tubes, but more generally with rods (regula) which had fights fixed at each end. Thefe inftruments were generally called Dioptra, and the apertures in the fights were called foramina dioptrorum, not perfpicilla. Ptolemy in his Almegift +, deferibes the inftrument, which is generally*known by the name of his Triquetrum. Ithad fights at each end, with apertures in them, which Georgius Trape- zuntius, the tranflator, calls foramina: he mentions, indeed, no particular name for this part of the inftrument, but Theon in hiscommentary x defcribes the conftruétion of it to be fueh, that the whole moon would appear through the fights #7 diorlaz, Proclus Diadochus, in his Hypotypofis A ftromica- rum Potitionum,** mentions the Dioptraof Hipparchus, which was an inftrument of the fame kind: fee Riccioli Almegiftum Novum, vol. 1. B. 3. C. 10. § 4. But we can have no fur- ther doubt upon the fubject, if we turn to Flamftead’s Hiftoria Celeftis, vol. III. p, 97. He there fays that ‘* haud pauci * Pp. 53, 54. Lond. 1653. + Book 5, chap. 12. + P.258. Bafil, 1538. Notwithftanding what Harduinus-fays, T have no doubt, but that the Dioptra mentioned by Pliny in his Natural Hiftory, B, 2 C.69. was an inftrument of this kind; but no defeription of itis given, and therefore I cannot argue upon it in this place. ** P, 399. Bafil, 1544. obfervationum “ ON THE TELESCOPE, iy, 147 obfervationum Tychonicarum ervores ex nudorum Dioptrorum Obfervations ufu neceffarie confequuntur.” Now itis only neceflary to a ig amine the Aftronomiz Inftauratcze Mechanica, and we fhall feetelefcopes that almoft all the inftruments, which Tycho Brahe ufed, are fitted with fights, which were fome perforated with fmall holes, and fome divided by narrow flits: this part of the in- ftrument he called dioptra, the perforations he called foramina, and the flits rimule. I could quote further proof that thefe words were commonly ufed in the fenfes which I have affixed to them, but it would be not only unneceflary but tedious. It muft, therefore, ré- main with Aletes to produce as good authorities for the al- _ ledged difference between per/picillum and per/picillum vitrewm. Icannot help thinking, however, that the very title-page of Kepler’s Dioptrice will be fatal to his explanation; for there we find that mention is made of the difcoveries of Galilzxo, made ‘* ope per/picilli” after the publication of the Siderius Nuntius. Here the word perfpicillum is undoubtedly ufed for the telefcope itfelf, and before I conclude what I have to fay, J fhall quote a paflage from Galilzo, which is ftill more con- tradictory to the ideas of Aletes. Although I differ from your correfpondent with refpeé& to the arguments, which he has ftated to you, ftill I agree with him in his general conclufion, that Kepler did not mean a te- lefcope by the word per/picilla, We learn, indeed, from _Borelli’s book de vero inventore telefcopii, that * one account makes the invention as early as the year 1590; but when we compare this with the depofition of Sara Gedarda + and what is ftated by Galilzo in (p. 10 of) his Sidereus Nuntius, it feems moft probable that telefcopes were not known before the year 1609. If Zachary Jaufens was acquainted with them before ‘that period, he feems not to have publithed his difcovery to the world. Now Kepler, in the place above quoted from the dedication of his Dioptrice, takes an opportunity of praifing the invention in the higheft terms, and as he did this, when it was public, it is probable that he would have done fo ftill “more warmly, if he had been the firft who publifhed an ac- "count of obferyations made with them; but there is nothing - ‘of this kind in the paflage alluded to in his book de cometis. *P.25. + p.3i. This makes the invention about 1611 or 1613, but “ de certo prefixo tempore non potuit dicere,” | | L2 . He 148 Obfervations relating to the invention of the tclefcope. ON THE TELESCOPES,” He was looking at the ftars with a friend on the bridge at Prague, and they obferved one in particular, ‘ Vidi’ * he fays, “ ftellam fub urfa, majorem czteris per perfpicilla intu- itus, que zquale ceteris fixis lumen mihi fine perfpicillis diffundere videbatur.” It is not likely that the perfon, who mentioned the firft ufe of fuch an inftrument as a telefcope, would contine himfelf to fo dry an account of the effeéts pro- duced by it. But there is another argument, which may be drawn from the book itfelf, and that is, when Kepler is giving an account | of his obferving a comet in the year 1618, he ufes the word telefcopium and not perfpicillum, ‘‘ 6 Sept. jam nulla amplius cunda vifu nudo potuit obfervari et telefco- pio infpectus fatis magnus apparuit.” ‘* Sept. 23. Planitudo major fine tele{copio, quam per illud.” ¢ But what puts it beyond doubt that Kepler was. not in pof- feffion of a telefcope fo early as the year 1607, is that we hear of no great difcoveries which he made about that time by ob- ferving the heavens. Monfieur de Moutucla, indeed, fays § that ‘“ Uniquement appliqué a determiner avec precifion les mouvemens celeftes, cet homme celebre faifoit peu d’ufage du telefcope.” He probably thought himfelf juftified in this, when others were employéd in the more mechanical labour of obfervation, When he had no fuch fellow-labourers, it isim- poilible that a man like Kepler could have negleéted an oppor- tunity of obferving, or have concealed the means of doing fo; and if he had not done both, we muft have had fome notices remaining either in his own writings or thofe of others. We muft recolleé likewife, that he was the firft who under- ftood the theory of telefcopes and the combination of lenfes, and we mutt not forget, that thefe difcoveries being once made, the greateft difficulty was overcome ; it was only neceffary to — ufe ihe telefcope and mark the objeéts which it pisiawed to the fight. From what I have ftated there feems to be non files dif-, ficulties attending either of the ways, which have been pro- pofed for interpreting the word perfpicilla. But there are fome paflages in the Sidereus Nuntius, which feem to affift us in affixing a meaning to the word, lefs exceptionable han the one hazarded by Aletes. * = Sept. 1607. +P. 48. +P; § Hiftorie des Mathematiques, vol. II. p. 254. ; ni ON THE TELESCOPE. 149 Obfervations ee ‘ : ‘ wie - 5) relating tothe ravi, in cujus extremitates vitrea duo perfpicilla. . . aptavi.” jrvention of the Again in p. 12. he fays ‘* dum nulla in tubo adeffent perfpi- telefcope, cilla,” the rays pafs in one direétion, but ‘ appofitis perfpi- cillis,” they will pafs in another. Hence it appears that Ga- lilao makes no difference between per/picilla and vitrea per- Jpicilla, but ufes both indifcriminately for the glaffes of his te- lefcopes. [am inclined indeed to believe that the original meaning of perfpicillum was like that of con/picilium a mere lens; that when lenfes were combined in telefcopes it was ufed both for the glafs and the inftrument, until the word ¢ele- fcoptum became common. Iam not, however, prepared to bring forward f{ufficient authorities for this account of the word, and IJ have not leifure at prefent to fearch for them. It is fuf- ficient for my purpofe that we are juftified in underftanding the word as meaning a mere lens; for if we confider it as fuch in the paffage under confideration all the difficulty vanifhes. Kepler complains in this very book de cometis * of the weak- nefs of his fight; he might, therefore, have probably ufed a fimple lens to affift it. Monfieur Dutens + has clearly proved that the convex lens was known to the ancients, and at the fame time t that Borelli calls Zachary Janfens, ‘« confpicilio- rum artifex peritiffimus,” he fpeaks of his concave as well as convex glaffes. There is one circumftance attending the obfervation itfelf, which feems to give fome fupport to my interpretation, which is, that it was not made at a time when Kepler was carefully examining the heavens for any new phenomena; but ina walk which he accidentally took with his friend. Now he may eafily be fuppofed to have carried about with him a fimple lens to correét any fault of his eyes, but it is fearcely probable that he would have had with him a telefcope, made, poflibly like Ga- lilazo’s, of a long leaden pipe. I fearcely need add, that whatever clears and ftrengthens the fight will diminith the ap- parent diameter of a fixed ftar, and confequently increafe the relative magnitude and light of the comet. In p. 11. Galileo fays * tubum primo plumbeum mihi pa- * P. 30. Inftrumenta Tychonica, &c. &c. et oculos vegetos re- quirunt, qu omnia mihi defuerunt, 1607, and in p. 48. Debili fum vifu, 1618. + Decouvertes des anciens, Partie 5, chap. 10. §.278. ft P.25. lam 150 ON THE TELESCOPE. Obfervations I am confcious, Sir, that what I now fend you, is put to- relating to the : . invention of theSether in a very hafty manner. Were my time at my own tclefcope. difpofal, I would endeavour to make it more fit fo meet the public eye; but I am induced to fend you thefe hints in their prefent {tate, becaufe I rely as much upon the candour as on the learning and abilities of Sir H. Englefield.. If Iam mif- taken, he will fet me right; and if I have any foundation for my opinion, he can éafily illuftrate my hypothefis by the paf- fages which agree with it, in the old writers on optics and aftronomy. Jam, Sir, Your obliged humble fervant, E.+83 Oxford, Feb. 10, 1805. P. S. Since I finifhed the letter, which I fent to you on the 10th inft. I have met with a paflage, which appears to me to decide the queftion on which I wrote to you. It is in Kepler’s book, which he publifhed at Francfort in 1604, under the title of Afironomie pars optica. The beginning of it is entitled Paralipomena in Vitellionem, He difcuffes the nature of the eye, and at p. 178. he begins a fet of propofitions on the man- ner in which it aéts as the organ of vifion. The 28th of thefe propofitions is: that which makes moft immediately for my pre- fent purpofe; itisat p. 200, and he,enumerates it in the fol lowing words. *¢ Qui remota diftin@é vident, propinqua confufé; iis per- « fpicilla convexa profunt. Qui vero confulé vident remota, ** juvantur concavis perfpicillis.” The mere quotation of thefe words is fuficient for the proof of what I have afferted; butas it may afford fome amufement to your readers, I wil] add his remarks upon them as fhortly as poflible.—‘‘ Quanta admiratio” he fays, ‘rei tante tam Jate propogatum ufum: & tamen caufum ignorari haétenus.” J. B. Porta, he adds, profefies to give tne reafon in his op- tics: but this book he was never able to meet with. Kepler then yery ably refutes the opinion of thofe, wao fuppofe this effe&t to be produced by the increafing or diminifhing of the apparent magnitude of the objeét. He offers with confider- able diffdence his own method of accounting for the pheno- -menon. He fuppofes that in the cafes mentioned in the pro-- pofition the vifion is imperfeét, in as much as without the in- : tervention * TO CONVERT ROUND MEASURE INTO SQUARE. 151 tervention of convex or-concave lenfes, the apices of the dif- ferent cones of rays would fall either before or behind the “retina. He fupports his theory by experiments which he tried on fhort and long-fighted perfons ; and quotes the paffage from Ariftotle, in which he points out the difference between the my ops and the prefbytes. Feb. 12. II. Confirudtiion of a Line in a Circle, nearly equal to the Side of a Square of the fame Superficies as that of the Carcle ttfelf. With Remarks on Pendulums and other Oljeéts. By Mr. J. WauTLey Boswetu. To Mr. NICHOLSON. | SIR, Feb. 9, 1805. Wavinc often found a difficulty in computing the preffure Introdu€ion, of fluids in tubes and cylindrical veffels, from all the calcula- tions relative to the gravities of different bodies, which I was acquainted with, being adapted for cubic meafure, it appeared a very defirable matter to find am eafy method cf converting round into fquare meafure, which induced me at different — times to attempt it, and as often to lay it afide, from not being able to arrive at any fatisfa€tory refult. But lately having had occafion to refume this fubjeét, I have difcovered a method of coming fo very near the truth, that if it fhould turn out to be in reality not fo exaét as it feems to me, it will ferve fo well for common computations, and promifes on that account to be of fuch utility, that I am induced to fend it to you for publi- cation, if you approve of it. As this fubjeét has been by many looked on as fomewhat To convert chimerical, it may be therefore not amifs to mention, for thofe si? ian of ‘your readers who are not very converiant in geometrical aaa, ftudies, that a mechanical method of computing fquare mea- fure from round is a very ancient and well-known problem ; but this method being difficult to apply to the infide of tubes, and not-capable of being ufed in diagrams or drawings, has made another method dofirable: mine for this purpofe is as follows :— 152 TO CONVERT ROUND MEASURE INTO SQUARE, To find a right Line, the Square of which fhall be equal to a given Circle. Problem. Draw two diameters (IF and C T) bifeéting each other at ray Saas right angles in the center (O) of the given circle; bifeét one fide of a fquare of the radii fo formed (O T) in W, and from the extremity ({) equal to a circle. of the next adjoining radius, through W draw the right line (IB) to the circumference: This line ([ B) is the line re- quired. Proof. Proof by trial, Let a fquare be formed equal to the given circle by the third corol. prop. fifth, of Archimedes; then take afquare formed by the line I B, and place it on this other fquare, fo that one angle and the fide adjacent to it of one, fhall fall on one angle and the fide adjacent to that angle of the other; then will it be feen that all the other angles and fides of each. will coin- cide, and the whole of one be equal to the whole of the other. This kind of proof is nearly the fame as that of the fourth prop. firft book of Euclid, on which fo many other propofi- tions depend ; and having often tried this method in the above manner, I could never perceive any difference between the two fquares: In thofe trials I ufed circles of card paper for the more exaét meafurement of the circumference in the mechani- cal procefs direéted in the method of Archimedes,* To the above I have to add the farther proof which follows of the exaétnefs of my method, which may make it appear ftill more certain. Sometime after I difcovered the above, looking into a work of the learned Kircher for a ready method of defcribing a pa- * In order to fhew how near Mr. B.’s conftruction approaches to the truth, we may obferve, that when the diameter is = 1, the area is = 0.7854, and the fide of the equal fquare = 0.8862. But in the figure, I W is found by adding the fquare of the radius to that of the half radius, and extracting the {quare root; and then by the property of fimilar triangles, as the radius is to I W, fo is the diameter to IB, which will be 0.8944 when the diameter is = 1. But this line exceeds 0.8862, or the true fide of the {quare, by 0,0082, or nearly one hundredth part. 4 ~ gabola ON PENDULUMS. 153. rabola which I knew was inferted in it, I perceived therein alfo a geometrical method of finding a right Jine equal to any given portion of the circumference of a circle; and having by this method drawn a right line equal to the fourth of the circumference of a circle, and with it and the diameter formed a parallelogram equal to the circle, and then a {quare equal to this parallelogram, in the ufual manner : I afterwards formed another fyuare equal to the fame circle, according to my me- thed before defcribed, and found no perceivable difference be- tween it and the former fquare. The difcovery of a faét in geometry often leads to another ; one of this kind I have to add here, which is, that a right line (BE) drawn from the extremity B of the line IB, at right angles through the oppofite diameter (IF) to the circum- ference, will be equal toa fourth of the circumference. The problem of Kircher above mentioned, may be found in the Ars magna Lucis et Umbre, prop. 3, lib. 3, pars 2, page 239, and the two following pages. As the circles which I ufed were under three inches diame- ter, it is poffible on fo {mall a {cale a minute error might not be vifible; but even in this cafe it muft be very inconfiderable, SEE I take the opportunity of forwarding the above to fend an Properties of explanation in reply to the annotations on my paper on pen- Pendulums, é&ce dulums, which I hope you will do me the favour to infert, as . you have in fome degree called on me for it. © I beg leave to obferve, that in that paper I have endea- voured to put a marked diftinétion (though perhaps not fuffi- ciently forcible) between the obfervations which admitted of proof, and {peculations on new fubjeéts: The latter may be confidered to commence with Huygens’ pendulum; and the others on fimilar principles, along with this, were merely de- figned as objects propojed for experiment, not as things proved, and. nothing is inferted about them but what was intended to _be noted as conjectural by the mode of expreffion. I confider it ufeful to propofe experiments (exclufive of my partiality to this mode of afcertaining faéts), becaufe among _ your numerous readers there might be fome who, with little trouble or expence, have opportunities to make trials of this kind, 154 Properties of pendulums, &c. GON PENDULUMS, kind, from the nature of their employments furnifhing them with all the materials neceflary ready at hand, and who have fuflicient intereft in the fubjeé to induce them to undertake them. I acknowledge that (as you obferve) I did not ftate all my reafons for thinking that Huygens’ circular pendulum, and the others propofed on the fame principles, would not be fo liable to alter their notation of time, as thofe in common ule, from a change of temperature; but this was caufed by the other fubjects contained in that paper having extended it to fuch a length as to oblige me to curtail this and other matters, and leave out part of what I had written relative to pyrometers alfo, My reafon for thinking well of Huygens’ pendulum pro- ceeded partly from my refpeét for his opinion, founded on the high idea I have of his mathematical erudition; and be- caufe it appeared to me, that the fize of the circle produced -by the gyration of the ball, depending on the impulfe of the moving power more than on the length of the fufpending ftring; that if the ftring lengthened a little, the circle would not be thereby increafed; and even if it was increafed, that the effe&t of the paraboloidal lamina would prevent its altering the time of each revolution of the ball (granting the theorem oi Huygens, which I inferted, to be true); for though I was .aware that the parabola generated would, by the lengthening of the ftring, become of fomewhat lefs curvature, yet I thought this change would be fo minute as not fenfibly to affe@t the time, efpecially as a change apparently greater had. not af.’ fe@ed it in a fimilar.cafe, which will be mentioned a little farther on, but of this I bad doubts then, as appears from what is remarked in page 77, where I mention that I thought the other conftruGtions which I propofed might be better on ac- count of the firing of that of Huygens being-liable to lengthen. ‘I reconymended the other pendulums, on fimilar principles, for trial, becaufe though the expanfion will increafe the di- menfions of the parabolical and cycioidal curves, yet ftill they will not ceafe to be thofe curves, which Huygens has proved to have fuch remarkable properties for the regulation of pen- — dulams; and as it has been found by experience, that a pen- duium vibrating ina {mall are of a large circle, has the fame accuracy as when moving in a cycloid, I imagined that there could not at leaft be more difference between the effe&ts of } two — ON PENDULUMS, Y55 two cycloids or parabolas a little differing in fize, than be- Properties of ‘tween the cycloid and large circle; and befides, as the cy- si cloidal cheecks ufed by Hig gens (which he found to fucceed fo well) were liable to the fame alteration by expanfion, I looked on his numerous experiments as confirmations of this opinion. In reply to the obfervation relative to the fuperior effect of pendulums detached as much as poffible, I beg leave to ob- _ ferve, that a movement interrupted or inlermitting (fuch as - more or lefs takes place in clocks with ofcillating pendulums), is fo very different from one which continues equally without any interruption (as that of the circular pendulum), that it does not {eem to me conclufive to argue from the effects of one to thofe of the other. In the note relative to the circular veffel enclofing the mer- -_curial tube, Iam inclined to imagine you were not aware that ' this veffel was direéted to be faftened to the {pindle fo as to _ revolve with it, by which means there would be no lateral : motion given to the air but by the friction of the outfide of : the cafe; for which reafon I mentioned that it fhould be made very {mooth externally: I alfo direGed it to be covered, to prevent the effe@ of the current of air, which would otherwife pafs through it, caufed by the centrifugal impulfe of the cir- cular motion. _ As‘to what I obferved about the fufpending fpring, I per- \haps expreffed myfelf too generally: I ftill think, however, I could point out feveral inftances of gridiron pendulums, where the compenfations were made of one bar againft an- _ other only, without allowing any compenfation for this {pring. I think it neceflary to mention among the emendations of my former paper, that the cycloidal hed of the rolling pen- dulum, propofed in it, fhould be formed of the fame thick- nefs in every part, as it might expand unequally if made thicker in one part than another: As a trial of this fort of pendulum may be made with a common clock at a {mall ex- pence, I hope it will induce fome one better {killed in fuch experiments than I am, to make it, even if the others fhould not be tried: and asa farther reafon for expectation of fuccefs . in the trial, it- fhould be confidered (in addition to what has | been advanced in fupport of the opinion, that the effeé of the cycloidal bed would be but little altered by its expanfion), ia - that, 156 Properties of ON THE HORIZONTAL MOON. that, on account of the fhortnefs of this bed, it could not pof- pendulums, &c+ fbly expand as much in length as the 39 inches of wire con- tained in a common pendulum-rod ; and that, as the greateft expanfion of the wire is certainly in the direétion the moft in- jurious to the effect of the pendulum, which is not the cafe with that of the cycloidal bed, it is probable that the rolling pendulum would be found fuperior to that in common ufe. With regard to the obfervations on pyrometers, I own I never faw that of Deluc; but as your defcription of it is not fufficiently minute to enable me to perceive how the ftandard in it for meafuring the different bars, could efcape expanfion in an increafe of temperature of the atmofphere, I {till can conceive no method by which the flandard for meafurement in any pyrometer, could be prevented from altering its length from the above caufe, but by keeping it artificially at a fixed temperature, by fome means diftinét from the apparatus, fimi- Jar to thofe of Mr. Ramfden, which you have mentioned. What I wrote on this fubje&t was intended as a caution in future experiments, and if it has produced the more extended publication of means to avoid the error I pointed out, or hall hereafter do fo, my view will be fully anfwered. Your very humble fervant, J. WHITLEY BOSWELL. Ili. , Some Remarks upon the Experiments by which Mr. Ez, WALKER Mr. Walker's experiments ad- verted to, has endeavoured to explain the apparent Enlargement of the Moon near the Horizon: with a Statement of fome Faéts upon which that Phenomenon feems chiefly to depend. In a Letter From C. H, To Mr. NICHOLSON. SIR, if SHOULD, with your permiffion, be glad to point out to your correfpondent, Mr. Ezekiel Walker, a theorem in op- ties, to which, it appears to me, that he has not paid fufficient a(tention in the courle of his ftudies. Rays | ON THE HORIZONTAL MOON, 157 Rays from a diftant obje@ which pafs through a convex $k Ontical tecurem- near its center, will have their focus more diftant from the Rca hay lens, than thofe rays which pafs through it nearer to its cir- the larger the cumference; and, confequently, the image formed by the 2Perture, and the image of courfe central rays, will be as much larger than that formed by the fmalier. rays of the circumference, as the focal diftance of the former , fhall exceed that of the latter. With a given aperture, the focus will be that puint in which the greateft number of rays coincide, for, there, will the image appear moft diftin@; and, confequently, as we enlarge the aperture of the lens, the central rays muft be combined with others more convergent, the new focus will approach the lens, and the image be, of courfe, proportionably di:minifhed, ; The total difagreement of this theorem with the refalt of This is contrary Mr. W.’s experiments, I can only account for by fuppofing ae pierre this gentleman, while he enlarged the aperture of his lens, he was probably not to have paid attention to the increafing brightnefs of the be aaa image, which, by making a ftronger impreffion on the retina, brightnefs. would appear to increafe in magnitude with every enlargement of the aperture. If I might be allowed to offer my advice to Propofal that he Mr. W. I thould recommend him to repeat. his experiments, #9"!4 vary and ‘ s 2 repeat the expee and fubftitute, for the flame of the candle, a fkreen having a fees bes - circular opening covered with thin paper. This, with a light behind it, may reprefent the horizontal moon. Some cha- ra¢ters fhould be marked upon it, in order to determine, with more facility, when the image is moft diftin@. ‘The precau- tion of reducing the different images, as nearly as poflible, to the fame degree of brightnefs previous to meafurement, muft not be negleGted. I am furprized indeed, that the ftruéture of the eye, which Mr. W. proteffes to have kept in view in the courfe of thefe experiments, did not point out to him the importance of this circumftance, which is fo admi- rably anfwered, in the natural organ, by the contraétion and expanfion of the pupil. As the phenomenon of the horizontal moon has of late Phenomenon of much engaged the attention of feveral of your correfpondents, re iw cafioned I will avail myfelf of the prefent opportunity to add a few in part by the remarks on that fubjeGt. It appears, at firlt view, that the MPpoftien of ee, i : ‘ . greater diftance, moft obvious method of accounting for the phenomenon, isby the aerial the following: We believe the moon more diftant from us P&rpettives and when in the horizon than when in the meridian; but we fe@ nasccapntie it, 158 , but thefe have not the greateft fhare in pro- ducing it. New explana- tion. The moon js rarely feen in the horizon. Small objects eclipfe the moon at confiderable altitudes. The elevated clouds are alfo large, becaufe near 5 and the moon feems {mall, be- caufe compared with them. But in or near ON THE HORIZONTAL MOON, it, in both cafes, under the fame apparent angle, and, ac- cording to our ufual habits of judging of the magnitudes of , objects, neceffarily refer the idea of greater magnitude to the greater diftance. The aerial perfpeétive, and various other circumftances, which combine to make the horizontal! diftance appear the greateft, have been fo well and fo often defcribed, that it would be fuperfluons to repeat them here. I muft ob- ferve, however, that this appearance of greater diftance in the horizontal moon, though the firft and moft obvious cir- cumftance which prefents itfelf to explain the illufion, is not, in my opinion, that which has the greateft fhare in pro- ducing it. After having confidered the fubje& with much attention, I am of opinion that the chief ftrefs ought to be laid on the” following particulars : We may be faid rarely to fee the moon in the horizon. Our habitual acquaintance with it is at fome confiderable alti- tude. Hence it follows, that all the objects with which it comes in apparent contact, and with which we occafionally compare its difk, are near to us, and fubtend angles propor- tionably large. Thus, for inftance, we often fee the moon lofe a large portion of her face behind the branch of a tree or a weather-cock, and totally dilappear behind a chimney. The clouds, too, which fleet before her, appear, from their proximity to us, on a gigantic feale. Thefe are the circum- ftances under which we have infenfibly formed our general ideas of the moon’s magnitude. Let us how furvey it in the horizon. The cafe is widely altered. We have now an op- portunity of comparing it with various large objeéts, which the horizon, the perhaps, being themfelves on the verge of a diftant horizon, clouds, build- ings, and other large objects, will appear imall, and hide but little of the moon’s dife 5 which will therefore, by comparifon, be feen on a grand and enlarged fcale. Thefe are the principal cir- eumftancese will be reduced to very trifling dimenfions; and thus the caftle and mafly cathedral will hide but a fmall part of that globe, which we have commonly feen half eclipfed by a fpout or a weathercock. The clouds too, reduced by diftance, appear on a much fmaller fcale when compared with the moon. In fhort, it is no longer the fame moon we were acquainted with in the meridian, but a much larger and more majeftic {phere, the novel appearance of which ftrikes moft of its fpeétators with a degree of awe and amazement. Though it appears to me that the circumftance I have pointed out, of our habitual comparifon of the moon with objeats ON THE HORIZONTAL MOON. 159 objeéts of known magnitudes, has the greateft thare in pro- ducing the illution by which it appears largeft in the horizon, I would by no means be underftood to reje@ the principal cireumfiances, long fince noticed as contribuling towards the fame effet. Different circumftances will neceflarily have more or lefs influence with different perfons, according to the tenor of their previoufly acquired habits and obfervations. : I remain, Sir, Your obedient fervant, . C,H, Taviftock Place, Feb, 15. wan ANNOTATION. W.N. THIS very ftriking and perfpicuous explanation of the Experiment enlargement of the moon near the horizon, will bring to the pichaaa st reader’s recolleétion a great number of facts, where the ab- hielo folute magnitudes of objects, of which the diftances are im- 24 moon appear ‘ .p__ of different mag- perfeétly known, are erroneoufly eftimated by comparifon nitudes, accord- with other objeéts lying in the fame dire@ion. Navigators ing to the ob- muft have been often ftruck with the extreme minutenefs co neepibetsa 8 the image of the fun or moon, when brought down by projected, Hadley’s quadrant fo as to be feen projeGted upon the near objeéts below the horizon, Since the perufal of this com- munication, I have repeated the experiment on thofe lumi- naries. Ifthe image of ‘the moon be removed a certain num- . ber of degrees from the direét ray, it is eafy, by altering the poktion of the quadrant, to obferve that image in the horizon to the right or left, or upon the pavement before us, or at a great elevation in the heavens. In thefe cafes its apparent magnitude, while the angular fize and brightnefs remain un- altered, is found to be fmall at the great elevation, large in the horizen, and moft fo when projeéted upon diftant obje@s, and it becomes a minute fpeck when feen depreffed among the objeéis clofe to the obferver. The fame experiment may be made with a pane of glafs, but lefs objectionably, becaufe ‘ it might be urged that the quantity of illumination is different - according to the obliquity of refleétion, 4A Mathe- 160 Theory of the {peaking trum- pet. SPEAKING TRUMPET. IV. A Mathematical Theory of the Speaking Trumpet. By Jouw Goueu, Ly. To Mr. NICHOLSON. SIR, ‘Tur {peaking trumpet is a conical tube, which receives the human voice from the mouth, and encreafes the range of it. The ftru€ture of thefe inftruments, and the materials of which they commonly confift, teach us to refer this fingular faculty to two caufes, In the firft place, the zriel pulfes undergo cer- tain modifications in the cavity of the trumpet; the nature and effets of which I am going to inveftigate. Secondly, the metallic fhell of the inftrament augments the power of the voice, by its aptitude to conduct thofe impulfes; which are impreffed upon it, partly by the pulfes of the included air, and partly by the direét ation of the Larynx, tranfmitted through the medium of the face to the mouth-piece of the inftrument. Before I enter upon the inveftigaticn of the effeéts refulting from the firft caufe, it will be neceffary to premife follow- ing lemma : Article 1, Let OR Sr ¢Fig. IV. Plate 7) be an evanefcent {phere of air, which is agitated by two or more pulfes, be- ginning and ending together, and radiating from the points P p, &c. the vibatory motion of OR Sr, in any dire€tion what- ever is equal to the joint fum of the forces, which the pulfes ~ would imprefs upon it feparately. Join PO, O p; and draw the lines ROr, SOs perpendicular to PO, Op; now as_ thefe lines are evanefcent, every point of each of them is equally preffed at any inftant by its refpeétive pulfe. But the force imparted to ROr by P, agitates the fphere ORSr equally in all direétions, Principia, 422; the fame holds true of the force of p uponSOs. Now thefe forces cannot co- alefce or be compounded fo as to act ina fingle direétion,— Manch. Mem. V. 5. p. 660; confequently they a@ with their joint powers in all direétions. Art.2. This being premifed, let the fruftum A BC D (Fig. 3.) reprefent a trumpet, the thell of which is a non-conduétor of found, After a pulfe of the voice has paffed through the aperture . SPEAKING TRUMPET. ~ . Jé6l aperture A B, it is- bounded in front by a fpherical furface, Theory of the having O, the vertex of the cone DOC, for its centre, and ere et feddiindinn the plane angle AO B; in other words, Jet fuch a furface be defcribed- any where in the frufttum A BCD, and the variable denfity of any one particle of air in conta@ with it, will be equal to the cotemporary denfity of any other par- ticle in the fame furface. For as foon as the motion is propa gated into the internal air, the pulfe will expand as far as-the fides of the tube will permit: Princip. 42.2: after which, the motion will be continued to the oppofite aperture C D, in right angles, 43 2bid, therefore it will be propagated along the lines A D, BC with equal celerities, fuppofe to T and V.— On the plane TV defcribe the furface T N V, in which the denfity of the air is every where equal at any inftant: Now | every point of fuch a furface aéts upon the air externally in contaét with it, and is re-aéted upon by the fame perpendicu- larly to itfelf, in {uch a manner that equal portions of the fur- face f{upport equal degrees of preffure.. Let Uu be an eva- nefcent particle of the curve T N V, draw UK, wk perpen- dicular to NO; then. the fuperficial ring between the planes UK, wk isasUK x Uu; but this ring is as the preffure upon it; which is alfo inverfely as the radius of curvature at -U, therefore if UKxU u be conftant, the radius of curvas ture is conftant ; confequently it is equalto O T, and the truth of the propofition is manifeft. Art. 3. Let f, be the force of a pulfe in the aperture AB; and let the internal air of the cone be agitated with an equal and fimilar impulfe at the point O; then the effeét thus pro- duced in the trumpet, will be the fame with that of the voice acting at A B, (by Art. 2.) But had the cone been out of the way, the fame force at the diftance O A, would have been uniformly diffufed over the furface of the hemifphere, having O for its centre. Art. 4, Put AOz=r; the variable apRabbe O T=2; the ra- dius of an evanefcent circled; the verfed fine of half the angle AOB=p; 3.1416=c. Then as the force f is diffufed over the hemilphere whofe radius=r, in free air by, Art. 3. that part of it which refides in an evanefcent point of the fame a, d2 -furface oA. | Qy e * Vou. X.—Marcuy, 1805. M Art. 162 Theory of the fpeaking trum- pet. / SPEAKING TRUMPET. Art. 5. The magnitude of the furface TN V =2cpa?: but the force f is diffufed over this fegment by Art. 3. con- fequently that part of it which is confined to an evanefcent fq Dep et xy Art. 6. Since the f{pherical furface T N V is convex to the plane CN D (4rt. 2.) the agitation of the air in the latter will commence at the centre N, and extend thence by the ap- plication of fucceffive circles of the fphere T N V_ to equal circles of the plane C D, having N for their centre; which operation will continue until F and V fali upon C and D.— Now as CN D isin conta& with unconfined air, each point of it, upon being ftruck, will become a centre, from which a pulfe willradiate freely. (Princip. 42.2.) Art. 7, Let P be fuch a phyfical point, and let its area = q; then if an evanefcent plane = q be drawn through P perpen- dicular to O P or x, the force impreffed upon it by the trum~- fy 2 cp a? the fame time to the equal phyfical point P in the plane (Art. 1.) Art. 8. Let L be the place of an ear, in O N produced, or more properly of a minute {phere of air, Put NP=y; PL ==w. Now the pulfe proceeding from P will have due effeé& upon the point L ¢Manch. Mem. v. V. p. 662. cor. 1); which effet is as —- f4 DQ dip he 2 Art. 4) rig : — fe ped als ; aa r Pe Rp Sey! ep ae acting upon the fphere L having d for its radius, But the num- _ | [pace g = pet will be CArt. 5) but the fame force is imparted at (Arts. 6 and 7): hence we have (by » for the force 2cyy! ber of points which aét together = teddy (Art. 6.)$ confe- | 7 x 43 1 i D fa* y y’ a ——en © t. J, quently thsiremisd forces ipl Gant iJ 52 Mr OPP Eee es N OS e:'O'C Hay CL 20; ane | ‘ d® the correét fluent of the precading expreflion is mes 3 drawn into the hyp. log. of —} when g and e are unequal. But if CD bife&’ OL; put CN =4, and the correé fluent fd? k2 becomes aperer Art, 10. SPEAKING TRUMPET. 163 Art. 10. Though the foregoing fluents have received one Theory of the : : > _ » fpeaking trume= correction, each of them requires a fecond, arifing from pets certain cireumftances peculiar to this problem. For it is evident, that the commencement of the agitation at N is _ prior to that. at C, by a part of time, whichis as CO—ON; confequently the completion of the former pulfe at L, will _ precede the termination of the latter at the fame point by a fimilar interval; which isas LC+-CO—OL. © Put this time = ¢, and the duration of one vibration of the larynx =/; alfo let the indivifable interval, or 4 of a fecond according to Eyler be denoted by m; then multiply the expreflions in Art. 9 mt ; by the fra&tion ; -° Art. 11. The force determined in the preceding paragraphs, is that which a non-conduéting tube imparts to an evanefcent {phere of air. This circumftance affords a plaufible obje€tion to the prefent theory; becaufe the fenfe of hearing is not con- fined to a phyfical point. But as the feat of this fenfation is of a given extent, at leaft in each perfon, the number of thefe vibrating points, in contact with the fenfitive furface, is alfo given: from this it follows, that the effeét of one particie is nearly a true meafure of the power of the whole number, _ when the ear lies at a great diftance from the planeC ND, reprefenting the trumpet’s mouth, Art.12. So much of the prefent fheet is occupied by the confideration of the firft caufe, that my remarks on the fecond, or the effeéts of the metallic fhell, muft be confined within marrow limits; thefe I fhall begin as follows. Art. 13. Since, the conduéting power of the trumpet is given, the vibrations communicated to the {mall end of it by the breath and face, will pafs to the oppofite extremity in a given time; which call L. Alfo let A be the force of a vibration at the diftance 1; and C L or d exprefs the fpace betwixt the trumpet and a remote ear. | Art. 14. In the firft place, let 1 be equalto L; then a fingle pulfe of the trumpet will firike the ear for every vibration of ; hm d2 Lo paper on this fubjeG@t. In the next place, let 2 be an aliquot ‘partof L; then the number of pulfes impreffed on ile ear in mo M 2 the the voice; and the force of it will be by my former 164 Theory of the {peaking trum pete SPEAKING TRUMPET. t 2a einiea h md the time of L is ae hence the force -* equation to the former of thofe found in Art. 9; and the fum gives the force of the teumpet upon a diftant ear. Art. 5. But if ¢be an aliquant part of L, the found will Add _ this = A ey : be imperfetly formed ; becaufe the quantity ori being a mixed number, the vibrations of the larynx will be conduéted along the metal, and difcharged into the air in a diforderly manner, fo as to defiroy the continuity of the note. The fame caufe, in all probability, conftitutes the difficulty which the inex- petienced find in their firft attempts to found horns and military trumpets: for the lips, which are compreffed by the end of the tube, form the mouth piece in this cafe; and the art of producing the found feems to confift in caufing the edges of them to vibrate in aliquot parts of L, or the interval belonging to the loweft note of the inftrument. The fame origin may alfo be afcribed to the mufical fcale, compofed of what are called the trumpet notes; the intervals of which decreafe in the following ratios, 1, 4, 4,4,4, &c. for 2 is ihe greate(t aliquot part of unity, + the next in fucceflion, and fo on. | Art. 16. If the remarks contained in the two preceding pa. ragraphs be juft, the perfon who makes ufe of a fpeaking trumpet, muft attend to the management of his voice; the pitch of which ought to coincide with fome note in the trumpet fcale of his inftrument: for proper attention to this circum- ftance will make the found of the metallic thell perfe@, and bring it into unifon with the other found; which arifes from the zrial pulfes, pafling through the cavity of the tube, at the fame inftant. In this manner, the greateft found will be pro- duced, fuppofing the power of the voice to be conftant; be- caufe the two fets of pulfes, conftituling the unifon, will im- | prefs the greateft poffible force upon the ear in a given time, _ On the other hand, if the foregoing precaution be negleéted, the imperfe& found of the metal will difturb the uniformity of the other, which is formed in the cavity ; and the force im-_ prefied on the ear by fo diforderly an aggregate of pulfes, will be interrupted and inconftant. Art. 17. Perhaps it is unneceflary to remark, that the perfeét elafticity of the air forms the bafis of the prefent theory; a fuppofition OBSERVATIONS ON BASALT, &c,' 165 fuppofition which in all probability is not altogether juft; but, when the fmallnefs of the angle O LC is recolleéted, the error arifing from the hypothefis vanifhes in a great meafure. JOHN GOUGH. Middlefhaw, Feb. 8, 1805. ° V. Obfervations on Bafult, and on the Tranfition from the vitreous to the fiony Texture, which occurs in the gradual Refrigeration of melted Bafalt ; with fome geological Remarks. In a Letter from Grecory Wart, Ejy. to the Right Hon, CHARLES © ~ Grevitre, V,P.R.S. From the ‘eines tues Tranfactions for 1804, p. 279. (Concluded from Page 126.) A CURIOUS diverfity may prevail in the produéts of a Fufion and eats compound body fubjected to fufion, when abfolute folution is py ee Mains cs produced, When merely fimple fufion takes place, the aggre- in compound bo- gation of the parts only is deftroyed: the fluidity arifes from dies, the more the facility with which they move on each other; and a regu- ae ae lated diminution of temperature, by facilitating their re-union, other. can hardly fail to recompofe the fame {pecies that formerly: appeared to exift in the compound. But, if the molecules have been diffolved and decompofed, and their component particles diffufed through the fluid, there feems to be very little probability that any re-union fhould compofe the fame mole- cules. It is more likely that new compounds will be formed, from which new molecules, and of courfe new cryftals, will be generated; and that, confequently, the fame rock may be- come the parent of very diverfified offspring. Thefe will however retain fome traces of their origin; for, as there can be no fufion of a compound body imagined, in which the mu- tual action of the components will not decompofe fome portion, there can be no folution fuppofed fo perfeé that every mole- eule fhall be deftroyed. In the firft cafe, there will exift the germs of a new compofition ; and, in the fecond, there will remain the relics of the old. If thefe obfervations are correét, confiderable utility feems The aqueous i Bo Nia : . formation exhi- derivable from them, in the explanation of fome geological bits fimilar facts. problems. \ 166 OBSERVATIONS ON BASALT, &c. problems. It will appear, that they ftrikingly illuftrate the ana- logy which exifts between the aqueous and igneous formations; and fhow that precifely the fame order and kind of arrangement is followed, in the generation of ftony mafies from water as from fire; for, the change of ftruéture, which I have obferved to he the moft inexplicable part of the procefs by which glafs pafles into ftone, is almoft exaétly imitated in the formation of @alcareous fta- Calcareous ftalaGtites. Succeffive depofitions of calcareous car- faétites: at fir bonate, form a ftalalite, which at firft is fibrous. A continuance ay of the procefs caufes the fibrous ftructure to difappear, and the thofe, then {pare ftalactite becomes irregularly {pathofe. The irregularities then vanifh, and it becomes perfect calcareous fpar, divifible into large thomboids, with the form peculiar to that minera!; and all the gradations may be found in the fame fpecimen. Nor is this change confined to a few folitary {pecimens; for a confiderable Coaft near Sun- extent of coaft near Sunderland, is formed of a lime-ftone eom- derland fo form- pofed of radiated {pheroids, from half an inch to three inches ie diameter, ‘imperfe€tly united. When one of thefe fpheroids attains fomething more than the ufual magnitude, it becomes compaét in the heart; and it is not unufual to difcover por- tions of the rock, in whieh the radii have entirely difappeared, and the whole mafs has become compact. It is probable that the entire formation of oolithi and pifolithi is owing to the fame caufe; and that they are prevented from ever arriving at great fize, by the union of their furfaces, and their fabfequent con- folidation into compact limeftone, into whieh they are conti- / nually found to graduate. Pelchicx, of Hitherto, I have feleGed inflances from fubRances which doubtful origin, have an undifputed claim to an aqueous origin. I fhall now, on sibeoriae eas the authority of Dolomieu, infiance a iimilar arrangement, ina ture. fubftance refpe@ting the origin of which theorifls are not agreed. A fpecies of petrofilex is found in the Val de Nido, in Corfica, which contains radiated petrofilieeous glands, from half a line toan inch in diameter. Thefe glands only differ from the bafis by their radiated, ftru€ure, andtheir colour; and appear to indieate very clearly, that the rock was fubjeéted toa fpecies of arrangement which, if it had been completed, would have changed its nature, and probably would have rendered it por-: phyritic; for Dolomieu obferves, that the centre of the glands was often occupied by a {mall cryftal of feld{par.* ‘Fhe extra- * Dolomicu. Journal de Phyfique, 1794, page 260. 5 : ordinary OBSERVATy~NS ON BasaLtt, &ec. 167 ordinary rock called the globular Granite of Corfica, is pan Globular granite analogous inftance. It is compofed of cryftals of hornblende, * eer _feld{par, quartz, and mica, in confufed aggregation ; and in this afis are immerfed {pheroids, about an inch and a half or two inches in diameter, compoted of concentric alternate coats of quartz and hornblende. The centre is principally occupied by hornblende; this is furrounded by a zone of quartz. Thefe {pheroids are radiated to the centre. There can be little doubt that this rock is merely the refult of interrupted ery Mallization; and that, if the procefs of arrangement had continued, this ftru€ture would have difappeared, and the whole rock would have refembled the prefent bafis. Hitherto, this very fingular rock has only been found in detached fragments.* The admiffion that folution is not a requifite of cryftalliza~ Solution not be- 4 7 ees ing indifpenfable tion, appears to me an important conceflion in favour of the to ¢-y Aatlization, aqueous fyftem, whicb has laboured under very great embar- butonly mecha- railment, from the difficulty of diffolving quartz. If a very Seite sei perfect mechanical fufpenfion be all that is requifite, we may cifficulties are removed. * I fhall venture to quote another inftance, on the authority of Profeflor Playfair. ‘* The falt rock in Chefhire, which lies in thick “© beds, interpofed between ftrata of an argillaceous or marly ftone, *< and isitfelf mixed with a confiderable portion of the fame earth, ‘exhibits a very great peculiarity in its ftru€ture. Though it - forms a mafs extremely compact, the falt is found to be arranged «© in round maffes, of five or fix feet in diameter, not truly fpherical, * buteach compreffed by thofe that furround it, fo as to have the ét fhape of an irregular polyhedron; thefe are formed of concentric « coats, diftinguifhable from each other by their colour, that is, © probably, by the greater or lef{s quantity of earth which they con- _ tain; fo that the roof of the mine, as it exhibits a horizontal {ec- ** tion of them, is divided into polygonal figures, each with a mul- “ titude of polygons without it, having altogether no inconfider- “* able refemblance to a Mofaic pavement. In the triangular {paces _* without the polygons, the {ait is in coats, parallel to the fides of “& the polygons.” I[lluftration of the Huttonian Theory, page 37, T am informed, that the filiceous depofition at Geyier, is at firft a porous friable mafs, and that the addition of more molecules ren- ders it fibrous; alfo that, on a farther addition, the fibrous ftruc- ‘ture difappears, and the whole aflumes the compact even texture of : chalcedony or flint. [If I am not mifinformed, a feries of {peci- “mens illuftrating this tranfition, exifted in the cabinet of the late Dr. Hutton, of Edinburgh. ceale 168 OBSERVATIONS ON B..SALT, &e, ceafe to wonder at the almoft daily formation of petrified wood, {in which, though eryftalllzation does not aétually take place, a very perfect arrangement is indicated, by the intimate union of the filiceous particles,) or of hydropbanous femi-opals in the decompofed ferpentine of Muffinet, near Turin, or of chalcedony containing drops of water, in the decompofed ba- falt of Vicenza. Since the cry- I have endeavoured to fhow, that.in the cryftallizations re- ftallizing may not (ylting from igneous fufion, it is not only poflible but probable, take place in the ‘ ; order of fufibili-that the moft infufible fubftances might not be the firft to ty, refractory eryftallize; and this appears to involve important confequences, fubftances may : . : ‘ : be impreffed by forit partly removes one of the greateft difficulties that embar- fuch as are more raffes the i igneous theory, by explaining the poffibility of re- foBble> fra€tory fabitenecs generated by fire being impreffed by the forms of more fufible ones. Itfeems, however, that the fame order of arrangement would prevail in fubftances that were fufpended ina fluid medium, as the degrees of attraétion would be the fame. In either cale, the firft itep by which the arrange-_ ment of an apparently homogenous mafs commenced, would probably be the accumulation of particular molecules into little globules. Such feems to have happened in variolites, and other rocks which contain fpherical concretions of a different nature Inftances and from their bafis. Still farther advanced is the arrangement of remarks, porphyries : the molecules of one fpecies have affumed a regular cryftalline form ; and fometimes two or even more varieties o cryftals are formed, which remain unmixed in the unarranged bafis. If the remaining molecules of that bafis are fufceptible of cryftallization, it may be fairly concluded, that an extenfion of the procefs of arrangement would convert the porphyry into granite, or at leaft into one of the compound aggregates of eryftals which conftitute the numerous tribes of granites, grun- fteins, and fienites; and it feems equally probable that this might be accomplifhed, whether the molecules were indebted to a fuitable temperature, of to an aqueous medium, for the requifite facility of movement. The formation of granite and other rocks, muft however be referred to the ultimate perfeGtion of cryftallization, by which all the molecules have been permitted to arrange. Thofe gra- nites called porphyritic, in which large.cry ftals of feldfpar are imbedded in a bafis compounded of the ordinary ingredients of granite in fmall grains, are apparently generated froee a men-> ftruum Granites and porphyry. 1s OBSERVATIONS ON BASALT, &e. 169 ftruum in which the molecules of one f{pecies, being greatly predominant in number to the reft, are the firft to exercife their polarity, and conftitute large cryftals, which are afterwards fur- rounded by fmaller ones, refulting from the fucceflive fepara- tions of the remaining elementary molecules. The changes of the fubftance that led to the foregoing re- The paffage marks, ferve to fhow that they are not altogether hypothetical ; roe E shi and any proof that may appear deficient, feems to be provided RE a a by the phenomena exhibited by lavas, in which may be obferved porphyritic, and : laftly to the gra= every fiep of the paflage from the vilreous to the ftony, from jitic gate are that to the porphyritic, and finally to the granitic ftate. The obfervable in lava of Lipari, which pafles from glafs to lava, by the genera- !*¥** tion of minute globules, may be cited, on the authority of Spal- lanzani, as an inftance of the commencement of the procefs of arrangement; * and, were not their origin ftill difputed, I might alfo cite the pitchftone lavas of the Euganean hills. It would appear, that the tranfition from the ftony to the porphyrytic flate israpid, for perfeéily homogeneous lavas are among the rareft of volcanic produ@s. The porphyritic lavas are moft numerous; and it is needlefs to detail the varieties they prefent. * Spallanzani, Viaggi alle due Sicilie. Tomo Secondo, page 238. The whole paffage, literally tranflated, ftandsthus: ‘* This lava «has a bafis of feldfpar, of a fine and compaét grain, a fplintery *¢ fragture, rough to the touch, and emitting fparks, like flint, «¢ when ftruck with fteel. It has an afh colour, in fome places ap- poaching to aleaden colour. It is thickly filled with an immen- “ fity of little bodies, which would be diftinguifhed with difficulty, «© from the refemblance of their colour to that of their bafis, were “¢ it not for their globular form. But this lava is joined to a great «© mafs of glafs, which forms a wholewith it, without any divifion <© or feparation between them; and this lava, which in many places ‘© retains its own nature, is in many other places reduced to glafs. «© Some parts of this glais are filled with the fame little bodies, but - other parts are pure glafs. This is in general very compact, has «© q dead black colour, and breaks rather into irregular pieces than ¢ into undulated fragments, as glafs properly does. Befides, it has «I know not what of unétuofity to the touch, and to the eye, <« which is not perceptible to the more perfect volcanic glafles. It «¢ yields {parks with fteel, like the lava; but the lava is wholly «© opaque, and the glafs, at the angles and thin edges, has confider- “« able tranfparency. It is only opaque where the globules are, &¢ which appear to be particles of lava.” | ; But, 170 OBSERVATIONS ON BASALT, &G But, though the procefs of arrangement has often only advanced thus far, it has in many inftances proceeded much farther, and it is by no means unufual to find the entire bafis regularly ar- ranged into cryftalline bodies; thus, to citea well known in- ftance, in many of the ancient lavas of Somma, large augites are imbedded in a cryftalline mafs, formed of minute cryftals of leacite, together with another cryftalline fubftance, whofe na- ture isnot perfeGily determined. Volcanic glafs. ‘The cafual occurrence of volcanic glafs is nowife at variance with this account, as itis fufficiently probable, that fome glaffes may have a much greater tendency to cryftalline arrangement than others poffefs; and it cannot appear extraordinary, that regular cryftals fhould femetimes be generated, even in the giafs, as it isa matter of daily occurrence in artificial glafles, and in furnace flags. Peculjar bodies Ff the diftin@ion attempted to be fhown between igneous may be afforded fufion and) folution be eftablithed, it may offer a means of ac- by this method counting for the abundance of peculiar bodies in lava, which do of feparation. te) not exift in other fituations, or at leaft are of extremely rare occurrence, For, if the igneous aétion decompofes the molecules of the fubftances on which it operates, there feems every probability that new compounds may refult, diffimilar to any fabitances we are acquainted with. It would appear, that the neceflity of imagining an undifcovered firatum abounding in leucites, chryfolites, and augites, may be difpenfed with; and, as I have endeavoured to fhow the probability that the moft infufible fubfances will not be the firft to cryftallize, the pene tration of reiraétory leucites by fufible augites, will ceafe to be an argument againft both being generated in the lava. I may alfo obferve, that the fame caufes which vary the cryftallized bodies refulting from igneous folution, muft operate upon the unarranged bafis; and that the fame rock may be fufed into lavas extremely diffimilar, as their varieties muft depend on the degree of folution which the fufion has accomplifhed.* rhe cae and If the analogy attempted to be fhown between the aqueous doétrines here and igneous formation appear founded, the tranfition from glafs given wil! not : ie affeét the quef- tion of the izne- & Phe evidence of the generation of Jeucites in the lava which roan i ie * contains them, colleéted by Leopold de Buch, and Breiflac, and bafalt, finally acquiefced in by Dolomieu, appears fo fatisfactory, that it can hardly be deemed prefumptuous to affume the point as deter- mined. OBSERVATIONS ON BASALT, &C. 171 to ftone can no way affe& the great queflion which has fo long divided geologifts, about the origin of bafalt; for though it is fynthetically demonftrated that bafalt may be formed by fire, the converfe of that propofition ftands fupported by ftrong ana- logical arguments, and its formation by water muft be allowed to beat leaft equally poffible. How far the probabilities derived from the examination of bafaltic formations may influence the ultimate decifion, isan enquiry in whicli I fhall not now engage; though I cannot avoid recalling to my mind, the numerous inftances of petrifaétions found in bafalt, and, as a counterpoile to that obfervation, the equally numerous inftances in which the heat emanating from it appears to have indurated ftrata, and coaked beds of coal. One remark may be ftated here with propriety, as it arifes immediately from the experiment which has occafioned thefe obfervations. In the ultimate refult of ¥ that experiment, the arrangement of the molecules was much ‘ more perfeét than in the original rock. It might be fuppofed, that a longer continuance of the fuitablé temperature was af- Fe forded it. This, however, could not be, for the mafs was only Why fo little of a few feet long, and a few inches thick ; the fire was only Ce maintained a day; and the whole was cooled in a week. But ttru@ture of the hill of folid bafalt, from which the fubftance operated upon >falt- was taken, is feveral miles long, and feveral hundred feet high; and, fuppofing it to have been irrupted in a ftate of igneous fufion, it muft have required months, nay years, for its refri- geration. How thencomes it, that the procefs of cryftallization is fo little advanced ? How comes the confafion of its texture to indicate the very reverfe of the tranquillity and perfe&tion of arrangement, which may be fairly affumed as neceffarily attending the extremely gradual changes of fo immenfe a mafs'? Fe i This objeGion admits of being obviated, upon the fuppofition sesame: i aan that, in the procefs. of melting, the molecules of the bafalt i a were decompofed; and that the new ones generated were more difpofed ta _ more difpofed to cryftallize than thofe whofe place they fup- cryfalliges plied. This explanation isin fome degree juflified, by the rained.. Neither de. Buch nor Dolomiew have been able to con- vince themfelves that the augites were alfo formed in the lava; but Eeonfefs myfelf entirely unable to appreciate the cogency of their arguments, which feem, annihilated by the admiffion they have made in fayour of leucites. total 172 OBSERVATIONS ON BASALT, &c. total difappearance of the minute fieldfpar and hornblende of of the bafalt; inftead of which, the regenerated ftone contains thin laminz: of cryftals, which are probably augites. The divifion of — [ cannot leave this {ubjeGt without noticing fome particulars, . ogg in which the procefs of arrangement defcribed in the early part during its de- of this letter, appears to yield a probable explanation of fome compofition in- of the peculiarities of bafalt, The general difpofition of bafalt mation of radi- to divide into globular maffes, in decompofing, 1s too re- ated {pheroids arkable a fa@t to have efcaped the attention of naturalifts ;_ therein; : , Kas : though, as far as I am informed, no fatisfa€tory explication of it has been given. The common effeéts of decompofition are obvioufly inadequate ; for it is common to fee a large block of amorphus bafalt feparate into numerous balls, afier a few months or years expofure to the weather ; and, rapid as the procefs of decompofition has been in the intervening portions, thefe balls refift its father progrefs with uncommon obftinacy. May not this_be attributed to the formation of the radiated {pheroids, whofe occurrence in my experiment J have already mentioned? and may not their greater refiftance of weather fimply arife from their aggregation being more perfeét than that of the incoherent molecules which have filled the intervals between them? Though the radiated ftru€ture has difappear- ed to the eye, thefe portions of the ftone retain the fupe- riority of more perfeét internal arrangement; and, if my pigmy experiments could yield fpheroids of two inches dia- meter, there can be no difficulty in fuppofing that the grand operations of nature may produce them of feveral feet. The feparation of the decompofed fragments in concentric coats, feems eafily explained; for I have already pointed out the fa- cility with which the radii of the fpheroids feparated at nearly the fame diftances from their centres, and the form of the fragments which refulted, refembling fragments of bombs. * and thefemay If this idea be not confidered as entirely divefted of plaufibi- a ieat 6c lity, I may venture to extend the fame principle,-to account faltic columns. for the wonderful regularity of the prifmatic configuration of * Even granite has been frequently obferved to affeét globular decompofition, and divifion into fragments of concentric coats. This mode of decompofition extends to many fubftances, that Wer- ner has called the formation it feems to indicate, ‘ abge/onderte Sticke,” which has been rendered in Englith, di/tinG concretions. bafaltic " ¢ " OBSERVATIONS ON BASALT, &c. 173 bafaltic columns, and alfo for their articulations, If we fwp+ Enumeration of pofe that a mafs of fluid bafalt has filled a valley to an indefi- RRR Fig. 1 reprefents one of the bottles. The bent tube, ABC, being attached to the outfide of the bottle when both heated, and entering it at C, may be made as ftrong as is thought confiftent with neatnefs. The part H B of the tube is of a conical form, fmall enougk at A to be inferted in a perforated cork. The fhort tube D E, on the oppofite fide, is alfo of a coni- cal form, large enough at E to admit a perforated cork. . The opening at F being intended for the tube of fafety. Fig. 2 reprefents the apparatus put together, the receiver being added as of a convenient form for conneéting with the other veffels. | The fmall tube AB of one bottle, is inferted in the perfo- rated cork fitted to the tube DE of the preceding one, and the joinings fecured in the ufual way by luting. The tubes of fafety being firft fecurely fixed, and the cork clofely fitted in the tube DE, any number of bottles may be | fucceffively added, without the leaft rifk of deranging thofe that are already connected. Obfervation 4 i ON BITUMENS, &c? 18] Vil. Obfervations on the Change of fome of the proximate Principles of Vegetables into Bitumen; with Analytical Experiments on a peculiar Subjiance which is found with the Bovey Coal. By Cuartes Harcuert, Efy. F. R.S. From the Philofophi- cal Tranfuctions for 1804. §.I: On E of the moft inftrudtive and important parts of geology, Converfion of is the. ftudy of the fpontaneous alterations by which Hides ee formerly appertaining to the organized kingdoms of nature : have, afier the lofs of the vital principle, become gradually converted into foffil fubftances. | In fome cafes, this converfion has been fo complete, as to The degrees are deftroy all traces of previous organic arrangement; but, inY@rious others, the original texture and form have been more or les preferved, although the fubftances retaining this texture, and exhibiting thefe forms, are often decidedly of a mineral nature. Some, however, of thefe extraneous foffils (as they are called) retain part of their original fubfiance or principles, whilft others ~can only be regarded as cafts or impreffions. From the animal kingdom we may feleét, as examples, the Inftances in the fofil ivory, which retains its cartilage*; the bones in Gib- ee: rallar rock, confifting of little more than the earthy part or _phofphate of lime; the fhells forming the lumachella of Bley- berg, which ftill poffefs the luftre and iridefcence of their original nacre; and the fhells found at Hordwell in Hamp- fhire, and in Picardy, which are chiefly porcellaneous, but more or le{s calcined; alfo the foflil echini and others, fo commonly found in the limeftone, chalk, and calcareous grit of this ifland, which, although they retain their original figure, are intirely, ‘or at leaft externally, formed of calcareous f{par, incrufting a nucleus of flint or chalcedony. And if, in addition to thefe, we may be allowed to regard the more recent limeftone and chalk firata as having been principally or partly formed from the detritus of animal exuviz, we fhall poffels a complete feries of gradations, commencing with animal fubftances analogous in * I have alfo found the cartilage perfeét, in the teeth of the mammoth. properties 132 MR. HATCHETT’S OBSERVATIONS properties to thofe which are recent, and terminating in bodies decidedly mineral, in which all veftiges of organization have been completely deftroyed, . and in the vegey The vegetable kingdom has likewife produced many in, sed ftances not lefs remarkable; and it is worthy of notice, that animal petrifactions are commonly of a calcareous nature, while, on the contrary, the vegetable petrifactions are general- ly filiceous *, It is not, however, my intention here to enter into a minute difcuffion concerning the formation of thefe extraneous foflils ; I fhall therefore proceed to confider other equally or perhaps more important changes, which organized bodies, efpecially vegetables, appear to have fuffered, (after the extinétion of the principle of life,) by being long buried in earthy ftrata, and by being thus expofed to the effects of mineral agents. . § IL Bituminous mat- The principal object I have in view, is to adduce fome ad, rash es ditional proofs, that the bituminous fubftances are derived matters; chiefly from the organized kingdoms of nature, and efpecially from Febetairce, vegetable Sadie for, although many circumflances feem to lead to the opinion, that the animal kingdom has in fome meafure contributed to the partial formation of bitumen, yet the proofs are by no means fo numerous, nor fo. pofitive, as thofe which indicate the vegetable kingdom to have been the’ grand fource from which the bitatneng have been derived. But this opinion, (founded upon very ftrong prefumptive evidence,) although generally adopted, is however queftioned by fome perfons; and I fhall therefore bring forward a few additional faéts, which will, I flatter myfelf, contribute to demonftrate, that bitumen has been, and is aétually' and i im- mediately formed, from the refin, and perhaps from fome of the other juices of vegetables. Pure biturmens The chemical charaéters of the pure or unmixed bitumens, differ much from fuch as paptha, petroleum, mineral tar, and afphaltum, are, in vegetable juices 5 : da aS} AL vs : tae By certain refpeéts, fo different from thofe of the refins and other infpiffated juices of recent vegetables, that, had the former never occurred but in a feparate and unmixed ftate, no pofitive inference could have been drawn from their pro- * Pyrites, ochraceous iron ore, and fahlertz, are alfo occafional- ly fpund in the forms of vegetable bodies. sic perties i] ON BITUMENs, &c, 183 perties in proof of their vegetable origin. Fortunately, how- but the progref- ever, they have been more frequently found under circum- ee ftances which have ftrongly indicated the fource from whence thefe refpetts. they have been derived ; and much information has been ac- quired from obfervations made on the varieties of turf, bitu- minous wood, and pit coal, on the nature of their furrounding ftrata, on the veftiges of animal and vegetable bodies which accompany them, and on various other local faéts; all- of which tend confiderably to elucidate the hiftory of their formation, and to throw light upon this interefting part of geology. Some inftances have already been mentioned, which fhow that foflil animal fubftances form a feries, commencing with fuch as are fcarcely different from thofe which are recent, and terminating in productions which have totally loft all traces of organization. Similar inftances are afforded by the vegetable kingdom; but without entering into a minute detail of every gradation, I fhall only cite three examples in this ifland, namely, 1. The fubmarine foreft at Sutton, on the coaft of Lincoln- Series of change, fhire, the timber of which has not fuffered any very apparent | " haces ins change in its vegetabie characters * 2. The ftrata of bituminous wood (called Bovey Coal) found 2+ Bovey coal in all its gradations, at Bovey, in Devon; which exhibits a feries of gradations, from the moft perfe ligenious texture, to a fubftance nearly approaching the characters of pit coal, and, on that account, diftinguifhed by the name of Stone Coal. 3. And laftly, the varieties of pit coal, fo abundant in many ae Perfect pit- parts of this country, in which almoft every appearance of vegetable origin has been deftroyed. The three examples above-mentioned, appear to form the extremities and centre of the feries; but as, from fome local circumftances, the procefs of carbonization, and formation of The fecond ftate offers the moft bitumen, has not taken place in the firft inftance, and as thefe itvagiive take effe€ts have proceeded to the ultimate degree in the Jaft, it jee for refearch. feems moft proper that we fhould feek for information, and for pofitive evidence, in the fecond example, which appears to be the mean point, exhibiting effe€ts of natural operations, by which bitumen and coal have been imperfeétly and partially * Account of a fubmarine Foreft on the Eaft Coaft of England, by Dr. Correa de Serra. Phil. Tranf. for 1799, p. 145. formed 184 Remarkable {chiftus, from Iceland, confifting very much of alder leaves. External chae racters. MR. HATCHETT’S OBSERVATIONS formed, without the abfolute obliteration of the original vegetable charaéters; and, although I have feleéted the Bovey coal as an example, becaufe it is found in this country, we muft recolle& that fimilar fubftances, or ftrata of bituminous wood, are found in many parts of our globe; fo that the example which has been more immediately chofen, is neither rare nor partial *, The nature, however, of the various kinds of ‘iasaatie wood, may in fome refpeéts be different ; but this I have not as yet had the means of afcertaining; I hall therefore only ftate the facts refulting from experiments made on Bovey coal, and more efpecially on a peculiar bituminous fubftance with which. it is accompanied. But, before I enter into thefe particulars, ‘it will be proper to mention a very remarkable {chiftus, with which I was, fome months fince, favoured by - the Right Hon. Sir Jofeph Banks, § III. This {chiftus was found by Sir Jofeph, in the courfe of his tour through Iceland, near Reykum, one of the great {pouting hot fprings, diftant about twenty-four Englifh miles from Hafnifiord ; but circumftances did not permit him to afcertain the extent of the ftratum. The fingularity of this fubftance is, thata great part of it confifts of leaves, which are evidently thofe of the alder, inter- pofed between the different lamella. I do not mean mere impreffions of leaves, fuch as are frequently found in many of the flates, but the real fubftance, in an apparently half charred ftate, retaining diftinétly the form of the leaves, and the arrangement of the fibres. The fchiftus is light, brittle, of eafy oxfoliation, in the tranfverfe fra€ture earthy, and of a pale brown colour ; but, when longitudinally divided, the whole furface conftantly pre- fents a feries of the leaves ,which have been mentioned, uniformly fpread, and commonly of a light gray on the upper furface, and of a dark brown on the other; the fibres on the * Strata of bituminous wood are found in various parts of France, in the vicinity of Cologne, in Heffe, Bohemia, Saxony, Italy, and efpecially in Iceland, where it is known under the name of Surturbrand. light ON BITUMENS, &c. 185 light gray furface being generally of a blackifh-brown, which is alfo the colour affumed by the fchiftus when reduced to powder, _ The leaves appeared to be in the ftate of charcoal, by being The leaves al- extremely brittle, by the blackith brown colour, by deflagrating ce ara fake with nitre, by the manner of burning, and by forming car- ‘ honic acid. I was, however, foon convinced that the fub- ftance of thefe leaves was not complete charcoal, but might more properly be regarded as vegetable matter in an incipient ftate of carbonization, which, although poffeffed of many of the apparent porperties of charcoal, {till retained a {mall portion of fome of the other principles of the original vege- table. My fufpicion was excited, partly by the odour produced but burning with _ during combuftion, which rather more refembled that of wood ths amie af than that of charcoal, and partly by the brown folution formed by digefting the powder of the unburned {chiftus in boiling diftilled water ; for, by various tefts I afcertained, that the fubflance thus diffolved was not of a mineral nature. In order, however, fully to fatisfy myfelf in this refpeét, I digefted arate of the 250 grains of the pulverized {chiftus with fix ounces of water. saargeeiihe 205, The liquor was, as before, of a dark brown colour, of the folution. It had but little flavour. Pruffiate of potafh, muriate of barytes, and folution of ifinglafs, did not produce any effeét; nitrate of filver formed a very faint cloud; fulphate of iron was flowly precipitated, of a dark brownifh colour; and muriate of tin produced a white precipitate. | , __ A portion of the folution, by long expofure to the air, was partially decompofed ; and a quantity of a brown fubftance was depofited, which could not again be diffolved in water. Another portion was alfo evaporated to drynefs, and af- forded a fimilar brown fubftance, which wads only partially . foluble in: water; and the refiduum, in both of the above cafes, was found to be infoluble in alcohol, and in ether. When burned, it emitfed fmoke, with the odour of vege- table matter. 250 grains of the {chiftus, afforded about three grains of the above fubftance; and, when the properties of ihe aqueous folution are confidered, fuch as its partial decompofition, and the depofit which it yielded by expofure to air, and by evapora- tion ; 186 It contained vegetable ex MR. HATCHETT’S OBSERVATIONS tion; the infolubility of this depofit when again digefted with water, alcohol, or ether ; the {moke and odour which it yielded when burned; and the precipitates formed by the addition of fulphate of iron and muriate of tin to its folution; when thefe properties, I fay, are confidered, there feems much reafon to conclude, that the fubftance diffolved by water was vegetable extraét, which had apparently fuffered fome degree of modifi- cation, but not fufficient to annul the more prominent charac- teriftic properties of that fubftance. The powder of the fchiftus, which had been employed in the preceding experiment, was afterwards digefted in alcohol during two days; and a pale yellow tinéture was thus formed, which, by evaporation, left about one grain of a yellow tranf- parent fubftance, poffefling the properties of refin. It appears, therefore, that a fubftance very analogous to Pee aa little vegetable extraét, and a {mail portion of refin, remain inherent > refin, but no tannin. in the leaves of this remarkable fchiftus. As folution of ifinglafs did not produce any effet, there was reafon to conclude, that the aqueous folution above-mentioned did not contain any tannin; but, as the tannin might be com- bined with the alumina of the fchiftus, I digefted a portion of it in muriatic acid, which, after filtration, was evaporated almoft to drynefs, leaving, however, the acid in a flight excefs. This was diluted with water; and afforded a blue precipitate with pruffiate of potath, a yellowith precipitate with ammonia, and a white precipitate with muriate of tin, but not any with fo- lution of ifinglafs. The tannin which might have been con- tained in therecent vegetable, appears therefore to have been diffipated or decompofed, with the greater part of the other vegetable principles, excepting the woody fibre reduced to the itate of an imperfeét coal, and the fmall portions of extract and refin which have been mentioned. Previous to having made the analyfis, I had an idea, that this fchiftus might be a lamellated incruftation, formed by the tufa of the hot fprings; but, according to Mr, Klaproth’s analyfis * the tufa of Geyfer is compofed of, Silica - - 98 Alumina - 4 - 1.50 Tron ~ - 50 4 100. * Beitrage, Zweiter band, p. 109. ‘ It ON BITUMENS, &c. 187 It is therefore very different from the {chiftus, the component ingredients of which were afcertained from the following analyfis. ANALYSIS OF THE SCHISTUS FROM ICELAND®, A. 250 grains, by diftillation, yielded water, which, in the Analjfis of the latter part of the procefs, became flightly. acid and turbid, ee = 42.50 grains. B. The heat was gradually increafed, until the bulb of the retort was completely red hot. During the increafe of the heat, a thick brown oily bitumen came over, which weighed 7.50 grains; it was attended with a copious produétion of hydrogen, carbonated hydrogen, and carbonic acid, the whole of which may be eftimated at 23.75 grains. C. The refiduum was black, like charcoal, and weighed 176.25 grains; but, being expofed to a ftrong red heat ina crucible of platina, it burned with a faint lambent flame, and was at length reduced to a pale brown earthy powder, which weighed 122 grains; fo that 54.25 grains were confumed. D. The 122 grains were mixed with 240 of pure potath; and, as fome particles of charcoal remained, 50 grains of nitre were added, and the whole was ftrongly heated, during half an hous, in a filver crucible. The mafs was then diffolved in diftilled water, and, muriatic acid being added to excels, the liquor was evaporated to drynefs, and was again digefted with muriatic acid much diluted; a quantity of pure filica then re- mained, which, after having been expofed to a red heat, weighed 98 grains. E. The liquor from which the filica had been feparated, was evaporated nearly to drynefs, and added to boiling lixivium of potath ; after the boiling had been continued for about one hour, the liquor was filtrated, and a quantity of oxide of iron was colleéted, which amounted to 6 grains. F, Solution of muriate of ammonia was added to the pre- ceding filtrated liquor ; and, the whole being then heated, a copious precipitate of alumina was obtained, which, after having been made red-hot, weighed 15 grains. Carbonate of foda caufed the preceding liquor (after the feparation of alumina) to become flightly turbid, but not any precipitate could be collected. * The remaining fpecimens are now in the Britifh Mufeum, and in the colleétion of the Right Hon. Charles Greville. Megae.s. . By \ 18s MR. HATCHETT’S OBSERVATIONS Component By this analyfis, 250 grains of the fchiftus afforded, - parts. Grains. Water - - - A. - 42.50 Thick brown oily bitumen ; ; 7.50 i Mixed gas (by computation) § 23.75 Charcoal (by computation) C. - 54425 Siliea § 0)" 7) 6} ae = ROM ment ae Oxide of iron -— = EL - 6 Alumina - - - - F, - 15 247. But the water and vegetable matter muft be regarded as extra- neous; and, if they are deduéted, the real compofition of the {chiftus is nearly as follows. Its component Silica - * ~ x 82.30 parts, exclufive . AF ees ana Alumina ce - - 12.61 vegetable matter. Oxide of Iron - - - 5. 99.91. It evidently, therefore, belongs to the family of argillaceous {chiftus, although the proportion of filica is more confiderable than has been found in thofe hitherto fubjcéted to chemical analy fis. The {chiftus has not-been noticed by von Troil, nor by any of thofe who have written concerning Iceland; for the flate which was fent to Profeffor Bergmann by the former, and which is mentioned by the latter in one of his letters, is there exprefsly ftated to be the common aluminous flate containing impreflions *. § IV. Queftion, From the experiments which have been related, we find that whether the the leaves contained in the Iceland f{chiftus, although they are circumftances of eet * Letters on Iceland, by Uno von Troil, p. 355. were peculiar. Mr. Faujas St. Fond has however deferibed a fchiftus nearly. fimilar, ‘which is found near Roche-Seauve, in the Vivarais, The ftratum extends about two leagues; and the only difference is, that, according to Mr. St. Fond, the {chiftus at Roche-Seauve is of ~ the nature of marble, or, as he terms it, argillo-calcareous, whereas this of Iceland is ubdoubtedly argillaceous. From Mr. St. Fond’s account, it does not appear that the vegetable ' leaves contained in the fchiftus of Roche-Seauve have been chemically examined. Effa: de Geologie, par. B. Faujas St. Fond, Tome I. pp: 128 and 134, apparently ~ y ON BITUMENS, &¢, 189 apparently reduced almoft to the ftate of charcoal, neverthe- lefs retain fome part of their original proximate principles, namely, extraét and refin. This, of itfeif, is undoubtedly a remarkable faét;-but, if it were unfupported by any other, the only inference would be, that the fchiftus was moft pro- ~ bably of very recent formation, and had been produced under peculiar circumftances. , I was defirous, therefore, to difcover fome fimilar cafes, requires an at- which might ferve as additional corroborative proofs of the pea A ei gradual alterations by which vegetable bodies become changed, mens. fo as at length to be regarded as forming part of the mineral kingdom ; and, from the reafons which have been ftated in the commencement of this paper, as well as from a certain fimilarity in the external charaéters of the fubftance compofing the leaves above-mentioned with thofe of the Bovey coal, I was induced to make this laft alfo a fubje€t of chemical inquiry. In the Philofophical Tranfaétions for the year 1760*, fome Bovey coal. remarks on the Bovey coal, and an account of the ftrata, are ftated, in a letter from the Rev. Dr. Milles to the Earl of Macclesfield, The object, indeed, of the author, was to efta- blifh that this and fimilar {ubftances are not of vegetable, but _ of mineral origin; and, to prove this, he adduces a great “number of cafes, moft of which, however, in the prefent ftate of natural hiftory and of chemiftry, muft be regarded as ; proving the contrary; whilit others, mentioned by him, fuch 4 as the Kimmeridge or Kimendge coal, are nothing more than bituminous flates, and of courfe are of a very different nature. Dr. Milles’s account of the varieties of the Bovey coal, and Its hiftory. of the ftate of the pits at that time, appears te be very ac- curate; and, for the prefent ftate, or at leaft {uch as it was in 1796, I fhall beg leave to refer toa paper of mine, pub- lifhed in the fourth volume of the Tranfaétions of the Linnean Society +; for, as this is more immediately a chemical invef- tigation, I wifh to avoid, as much as poflible, entering into any minute detail of geological circumiftances. ' t * Vol. LI. p. 534. “+ Obfervations on bituminous Subftances, p. 138. See alfo Parkinfon’s Organic Remains of a former World. Vol. I. p. 126. é It 190 Its ftrata agree with thofe of furturbrand. MR. HATCHETT’s OBSERVATIONS [t may however be proper to obferve, that the Bovey coal is found in ftrata, correfponding in almoft every particular with thofe of the furturbrand in Iceland, deferibed by Von Troil*, and by Profelfor Bergmann t+. The different ftrata of both thefe fubftances are likewife fimilar, being:compofed of wood or trunks of trees, which have completely loft their cylindrical form, and are perfeéily flattened, as if they had been fubjeéted to an immente degree of preffure f. The * Von Troil’s Letters, p. 42. + Ofufewa Bergmannt, Tom. II. De Produdtis Veoicaniis, p- 239. + Bergmann, in the diflertation above quoted, accurately de- {cribes this appearance of the furturbrand, and then fays, *‘ Que autem immanis requiritur vis, ut truncus cylindricus ita compla- netur > Nonne antea frarticularum nexus futredinis quodam gradu fverit relaxatus? Certe, nifi compages quodammodo mutatur, quodlibet pondus incumbens huic effe€tui erit impar. Ceterum idem obfervatur phanomenon 7x omni fchifio argillaceo.” This is certainly a very curious faét ; and the learned Profeffor, with his ufual acutenefs, rejeéts the idea that mere weight can have been the caufe. Asa farther proof alfo, he afterwards obferves, ‘‘ Or- thoceratite, que zz ffrato calcareo conicam figuram perfee fervant, in {chifto Alanum fere triangulare compreffione efficiunt. _Idem:valet de pifcibus, conchis, infeétifque petrefaétis.’’ And again, ‘‘ Ob- fervatu quoque dignum eft, quod zdem referiatur effectus, quamvis Stratum calcareum fub Jchifto collocatum fit, et majori ideo fondere com - frrimente oauftum.’ De Produétis Volcaniis, p.240. It is evident, therefore, that weight alone has not produced this effeét; and Bergmann’s idea, that the folidity of the vegetable bodies may have undergone fome previous change, in the manner of incipient putrefaction, ‘by moifture, and by: becoming heated in the mafs, muft be allowed to be very probable. But bodies fuch as thells could: not be thus affeéted ; and. therefore they. muft have been ex- pofed to fome mechanical effeét, peculiar to argillaceous ftrata ; which effeét, however, from the circumftances which have been adduced, evidently could not have refulted from the mere preffure of the fuperincumbent ftrata. To me, therefore, it feems not very improbable, that, together with a certain change in the foli- dity of vegetable bodies, produced in the manner imagined by Bergmann, and, together with fome degree of fuperincumbent preflure, a real and powerful mechanical aétion has been exert- ed, by the contraction of the argillaceous ftrata, in confequence of ON BITUMENS, &c. / 191 The Bovey coal is commonly of a chocolate-brown, and fome- External cha- times almoft black. The quality and texture of it are various in different ftrata; from fome of thefe, it is obtained in the form of ftraight flat-pieces, three or four feet in length, refembling boards, and is therefore called Board Coal. Others have an oblique, wavy, and undulating texture, and, as Dr. Milles ob- ferves, have a ftrong refemblance to the roots of trees, from which, moft probably, this fort has in a great meafute been formed. Some kinds alfo appear to be more or lefs intermixed with earth; but that which produces the moft powerful and lafting fire, is called ftone coal; it is black, with a glofly fra€ture ; has little or none of the vegetable texture; is more folid and compaét than the others, being almoft as heavy as fome of the pit coals, the nature of veal it feems very nearly to approach. For chemical examination, I feleGted fome of the coal which had a wavy texture, and rather a gloffy fraéture; the quality of this fort being apparently intermediate between the others, as it retains completely the marks of its vegetable origin, while, at the fame time, it poflefles every perfect character of this {pecies of coal. A. 200 grains of the Bovey coal, by diftillation, yielded, Grains. 1. Water, which foon came overacid, and afterwards turbid, by the mixture of fome bitumen - - 60 2. Thick brown oily bitumen - - - - 21 3. Charcoal - - - ~ - 90 4, Mixed gas, confifting of at he Se carbonated hydrogen, and ee at 29 acid, 200. ‘The charcoal, in appearance, perfeétly refembled that which is made from recent vegetables. By incineration, about 4 grains of yellowith afhes were left, which confifted of alumina, iron, and filica, derived moft probably from fome finall portion of the clay ftrata which accompany the Bovey coal, of deficcation; this, I believe, has not hitherto been much confi- dered, but I am inclined, from many circumftances, to attribute to it a very great degree of power. ' : But racters of Bovey Coal. Chemical exa- mination of Bovey coal. 192 Tt refembles the fchiftus in its products as well as character 5 but it afforded no extract, but only refin ; MR. HATCHETT’s OBSERVATIONS But it is very remarkable, that neither the afhes obtained froma the charcoal of the Bovey coal, nor thofe obtained from the leaves of the [Iceland {chiftus, afforded the ee trace of alkali.* | B. 200 grains of the Bovey coal, reduced to powder, were digefted in boiling diftilled water, which was afterwards filtrated, and examined; but I could not difcover any figns of extraét, or of any other fubftance. C. 200 grains were next digefted with fix ounces of alcohol, in avery low degree of heat, during fivedays. A yellowith- brown tinéture was thus formed, which, by evaporation, afe forded a deep brown fubfance, poffefling all the properties of refin, being infoluble in water, but foluble in alcohol, and in ether; it alfo {peedily melted, when placed on a red-hot iron, burned with much flame, and emitted a fragant odour, totally unlike the very unpleafant fmell produced by burning the coal itfelf, or by burning any of the common bituminous fub- fiances. The quantity, however, which could be extracted from 200 grains of the coal, by alcohol, was but fmall, as it did not exceed $ grains. But this {mall quantity was fufficient to prove, that although the Bovey coal does not contain any vegetable extraét, like the {chiftus formerly mentioned, yet the whole of the proximate principles of the original vegetable have not been entirely changed; as afmall portion of true refin, not converted into bitumen, {till remains inherent in the cea!, although the bituminous part is much the moft prevalent, and caufes the fetid odour which attends the combuftion of this fubftance. Upon a comparifon of the general external charaéters of the Bovey coa!, with thofe of the {ubftance which forms the leaves contained in the Iceland {chiftus, a very great refemblance will be obferved ; and this is farther confirmed, by the fimilarity. of the produéts obtained from each of them in the preceding ex- periments, with the fingle exception, that the leaves contain * This, as far as relates to the Bovey coal, has been alfo no- ticed by Dr. Milles, Phil. Tranf. Vol. LI. p. 553. But wood, however long fubmerged, is not deprived of alkali, unlefs it has more or lefs been converted into coal; for I have, fince the read- ing of this paper, made fome experiments on the wood of the fub- merged foreft at Sutton, on. the coaft of Lincolnthire, and have found it to contain potash. Whine ee ON BITUMENS, &c, 193 ~ fome vegetable extra&t, which I could not difcover inthe Bovey coal. They agree however in every other refpeét; as they both confift of woody fibre in a ftate of femicarbonization, impreg- nated with bitumen, and a {mall portion of refin, perfelly fimilar to that which is contained in many recent vegetable bodies ; and thus it feems, that as the woody fibre, in thefe cafes, ftill retains fome part of its vegetable charaéters, and is but partially and imperfe@tly converted into coal, fo, in like manner, fome of the other vegetable principles have only fuffered a partial change. Undoubtedly, there is every rea- which moft pro fon to believe that, next to the woody fibre, refin is the fub- ee ftance which in vegetables pafling to the foffil ftate, moft the bitumen powerfally refifis any alteration; and that, when this is at length effeGted, it is more immediately the fubftance from which bitumen is produced. The inftances which have been mentioned corroborate this opinion ; for the vegetable extra& in one of them, and more efpecially the refin which was difcovered in both, muft be regarded as part of thofe prin- ciples of the original vegetables which have remained, after fome other portions of the fame have been modified into bitumen. The fmallnefs of the quantity of refin obtained in both the preceding cafes, by no means invalidates the proof of the above epinion; but, as an additional confirmation of it, I fhall now _ give an account of a very fingular fubftance, which ts found with the Bovey coal. $V. . Dr. Milles, in his remarks on the Bovey coal, (which I Singular fabe have feveral times had occafion to notice in the courfe of this ssi : Paper,) flates, that ‘‘ amongft the clay, but adhering to the coal, it coal, are found lumps of a bright yellow loam,’ extreinely light, and fo faturated with petroleum, that they burn like fealing wax, emitting a very agreeable and aromatic fcent-” * This fubftance, I alfo obferved, when I vifited the Bovey ft is » peculiar coal-pits, in 1794. and 1796. At that time, however, it was bitumen. fearce, and J could only procure one {mall fpecimen, which is now in the Britifh Mafeum; bat, from a curfory examination of it, L was convinced that it was a peculiar bitrminous fubftance, * Phil. Tranf. Vol. LI. p. 536. Vor. X.—Marcs, 1804. Oo and 194 Defcription of the bitumen from Bovey. Experiments on the fame. ~ MR. HATCHETT’S OBSERVATIONS and not loam impregnated with petroleum, as Dr. Milles had - fuppofed. I could not then conveniently make a regular analyfis of it, and therefore contented myfelf with briefly defcribing if, in a note annexed to my Paper on it et ae Subftances, * Lately, however, my Hott John Sheldon, Efq. of Exeter, F. R. S. obligingly fent me feveral pieces of it, together with fpecimens of the different kinds of Bovey coal which have been mentioned; and thus I was enabled fully to afcertain its real nature and properties. / DESCRIPTION OF THE BITUMEN FROM BOVEY. It accompanies the Bovey coal, in the manner already des fcribed, and is found in maffes of a moderate fize. The colour is pale brownifh ochraceous yellow. The fra€ture is imperfeéily conchoidal. It appears earthly externally, but, when broken, exhibits a flight degree of vitreous luftre. The fragments are irregularly angular, and completely opaque al the edges. _Itis extremely brittle. It does not apparently become foftened, when held for fome time in the hand, but emits a faint refinous odour. The {pecific gravity, at temperature 65° of Fahrenheit, is, 1,133. Some {pecimens have dark fpots, flightly approaching in co- jour and luftre to afphaltum ; and {mall portions of the Bovey coal are commonly interfperfed in the larger mafles of this bitumen. When placed on a heated iron, it immediately melts, Fare much, burns with a bright flame, and yields a very fragrant odour, like fome of the {weet-fcented refins, but which at laft becomes ilightly tainted with that of afphaltum. : The melted mafs, when cold, is black, very brittle, and breaks with a gloffy fra@ure. EXPERIMENTS. A. 100 grains of this bitumen, when diftilled until the bulb of the retort became red-hot, afforded, * Tranfaétions of the Linnean Society, Vol. IV. p. 139. ON BASALTs, &c. Grainse 1. Water flightly acid - a 2 6h 3 2. Thick brown oily bitumen, very fimilar to that which was obtained from the Bovey coal, but policing flightly the odour of vegetable tar - - 9 = 45 3. Light fpongy coal - 23 4. Mixed gas, compofed of hydrogen, garboued aya gen, and carbonic acid, (by computation,) = 99: The coal yielded about three grains and a half of afhes, which confifted of alumina, iron, and filica, with a trace of lime. B. The bitumen was not affeéted by being long digefted in boiling diftilled water. C. By digefting 100 grains in lixivium of pure potath, a brown folution was formed; this was faturated with muriatie acid, and a brown refinous precipitate was obtained, which weighed 21 grains, D. A portion was digefted in nitric acid: at firft, much nitrous gas was evolved, and, after the digeftion had been con- tinued for neatly 48 hours, a part was diffolved, and formed an orange-coloured folution, which did not yield any precipi- tate, when faturated by the alkalis, or by lime; the colour only became more deep, and, by evaporation, a yellow vifcid fub- ftance was obtained, which was foluble in water. The above nitric folution poffefled every property of thofe nitric folutions of refinous fubftances which I have mentioned in a former paper. * E. The benzoic and fuccinic acids were not obtained from this fubftance, by any of the methods ufually employed. F. Alcohol almoft immediately began to aét upon this bitu- men; and, being added at different times, gradually diffolved a confiderable part of it. The folution was reddifh-brown, and has a refinous odour; by the addition of water it became milky, and, by evaporation, afforded a dark brown fubftance, which had every property of retin, whilft the refiduum left by the alcohol poffeffed thofe proporties which chara¢terize afphaltum. The following analyfis was then made, to difcover the pros portions of the component ingredients, * Phil, Tranf. for 1804, p. 198. O2 ANALYSIS 195 196 Analyfis of the bitumen from Bovey Tts component parts. kingdom. MR, HATCHETT’S OBSERVATIONS ANALYSIS OF THE BITUMEN FROM BOVEY. A. 100 grains, reduced to a fine powder, were digefted during 48 hours with fix ounces of alcohol, the veffel being placed in fand moderately warmed. A deep reddifh-brown tin€ture was thus obtained ; and the operation was again twice | repeated, with other portions of the fame menftruum, until it ceafed to act upon the refiduum. 4 The whole of the {pirituous olution (which had been cau- tioufly decanted) was then fubjeéted toa very gradual diftilla- tion in an alembic, and yielded a brown fragant refin, which weighed 55 grains. B. The refiduum, which could not be diffolved by alcohoi, was digefted in boiling diftilled water, but this did not a€t upon it; the whole was therefore colleéted on a filter, was gradually dried, without heat, by mere expofure to the air, and then weighed 44 grains. Thefe 44 grains confifted of a light, porous, pale-brown fub- ftance, which, being melted, formed a black, fhining, brittle mafs. It burned with the odour of afphaltum, but rather lefs. difagreeable, owing moft probably to a {mall portion of the refin, which had not been completely extraéted by the alcohol. It -was infoluble in water, and in alcohol, but was readily diffolved by heated fat oils; and in every other particular was found to poflefs the properties of afphaltum. The 44 grains of afphaltum, when burned, left a refiduum, which weighed three grains, and confifted of alumina, filica, and iron, By this analyfis it appears, that the bitumen which accom- panies the Bovey coal, is a peculiar and hitherto unknown fubftance, which is partly in the ftate of vegetable refin, and partly in that of the bitumen called afphaltum, the refin being in the largeft proportion, as 100 grains of the above- mentioned fubftance afforded, Refin —~ - - - - - 55 Afphaltam ery crm «a ~ 41 Marthy refiduum shite). = 3 92, Thus we have an inftance of a fubftance being found under curcumftances which conftitute a foffil, although the charaéters of it appertain partly to the vegetable, and partly to the mineral § VI. ON BITUMENS, &c. | 197 § VI. The powerful ation which alcohol exerts on moft of the Experiments on refins, may juftly be regarded as forming a ftearked diftinétion be by the : n of alco-= between thofe fubftances and the bitumens. But, as fome of hol, the bitumens are aéted upon by alcohol, in a flight degree, I was defirous to afcertain whether a {mall portion of refin was contained in any of thefe; or, if that was not the cafe, I with- ed to determine the nature of the fubftances which could be feparated, although very fparingly, by this menftruum. I therefore made the following comparative experiments, on the foft brown elaftic bitumen from Derbyhire ; on the genu- ine afphaltum ; on very pure cannel coal; and. on the com- mon pit coal. 100 grains of each were digefted with three ounces of alcohol, in matraffes placed in warm fand, during five days, ‘ fome alcohol being occafionally added, to fupply the lofs , caufed by evaporation. After the above-mentioned period had elapfed, the liquid contained in each matrafs was poured into feparate veifels. I. The alcohol which had been digefted on the elaftic bitu- Refolts: men was not tinged, nor, when {pontaneoufly evaporated, did it leave any film or ftain on the glafs. I]. From afphaltum, the alcohol had extra¢ted a yellow tinéture, which, in fome fituations, appeared of a pale olive colour, and, being fpontaneoutly evaporated, a thick brown liquid was depofited, in {mall drops, on the glafs; thefe drops did not become hard after two months, and poffeffed the odour, and every other property, of petroleum, The afphal- tum had loft in weight about one grain and a half. IIL. The cannel coal had communicated a pale yellow tint io the alcohol, which, in the manner above defcribed, was afcertained to be caufed by petroleum ; but, from the f{mall- nefs of the quantity, the weight could not be determined. IV. The alcohol which had been digefted on pit coal, had not afflumed any colour; but, by fpontaneous evaporation *, it left a film on the glafs, which, by its odour, was alfo tound to be petroleum. By thefe experiments we find, that the aétion of alcohol on Alcohol aéts the bitumens is very flight; and that the {mall portion which Ky pa tate * Spontaneous evaporation, by expofure to the air, was em- ployed i in thefe experiments, for reafons w hich muft be fufficiently obviou Sa may 198 ‘They are not formed by time alone. MR, HATCHETT’S OBSERVATIONS may thus be extraéted from fome of them, is petroleum. In thefe, the procefs of bituminization (if I may be allowed to employ fuch a term) appears to have been completed, whilft in the Bovey coal, and efpecially in the fubftance which ac- companies it, nature feems to have performed only the half of her work, and, from fome unknown caufe, to have ftopped in the middle of her operations. But, by this circumftance, much light is thrown on the hiftory of bituminous fubftances ; and the opinion, that they owe their origin to the organized kingdoms of nature, efpecially to that of vegetables, which hitherto has been fupported only by prefumptive proofs, feems now, in a great meafure, to be confirmed, although the caufes which operate thefe changes on vegeiable bodies are as yet undifcovered, : Many faéts indicate, that time alone does not reduce ani- mal or vegetable bodies to the ftate of foflils. In this country, there are numerous examples of large quantities of timber, (even whole forefts) which have been {ubmerged prior to any tradition, and which neverthelefs completely retain their lig- neous charaéters.* Other local caufes and agents muft there- fore have been required, to form the varieties of coal and other bituminous fubflances. In fome inftances (as in the formation of Bovey coal), thefe caufes feem to have aéted partially and imperfeétly, whilft, in the formation of the I greater part of the pit coals, their operation has been exten- five and complete. In the pit coals, the mineral charaéters predominate, and the principal veftige of their real origin feems to be bitumen ; for the prefence of carbon in the ftate of oxide, cannot alone be confidered as decifive. Bitumen, therefore, with the exuviz and impreffions fo commonly found in the accompanying ftrata, muft be more immediately regarded as the proofs, in favour of the origin of pit coal from organized bodies ; and, confidering the general faéts which have been long obferved, together with thofe Jately adduced refpe&ting the Bovey coal, and the fubftance which is found with it, we feem now to have almoft unquel- * Phil. Tranf. for January, 1671. Phil. Tranf. Vol. XIX. p- 526. Ibid. Vol. XXII. p. 980. Ibid. Vol. XXIII. p. 1073. Ibid. Vol. XXVII. p. 298. Ibid. for 1799, p. 145. tionable> ON BITUMENS, &c, é 199 tionable eyidence, that bitumen has effentially been produced by the modification of fome of the proximate principles of vegetables, and efpecially refin. Modern chemiftry had comparatively made but a {mall pro- Whether they grefs, when the illuftrious Bergmann publithed his Differtation, %€ of igneous or aqueous formas entitled, Produdta Ignis fubterranet chemice confiderata ; for, at tion. that time, the extent and power of chemical a€tion, in the humid way, were very imperfectly underftood. In that part, however, of the above work, where he {peaks of the fofiil wood of Iceland, called Surturbrand, he evidently appears doubtful how far volcanic fire may have aéted upon it; al- though he conceives that, in the formation of it there has been fome connection with volcanic operations. His words are, “Quid de ligno fofili Iandiea fentiendum fit, gnaro in loco na- talt ae decidendum relinquimus. Jnéerea, ut cum Y vulcani operationibus nexum credamus, plures fuadent rationes, quamets hucufque modum ignoremus, quo fitum texturamque ad- quifiverunt hec firata.” It certainly was very natural that Bergmann (hould entertain this opinion, in refpeét to the fur- turbrand; and it is remarkable, that the leaves contained in the {chiftus lately defcribed, are of the fame nature, and are found in the fame country. The leaves alfo defcribed by Mr. St. Fond, are likewife found in a country which, according to him, was formerly volcanic. .Were thefe, fubftances, there- fore, never found but in countries which either aétually are or were volcanic, we fhould be almoft compelled to believe, with, the Swedifh profeffor, that the operations of fubterra- neous fires have been concerned in the formation. of thefe bodies, or rather in the converfion of them into their prefent fiate. But fimilar fubftances are found in countries where not the They are found fmalleft veftige of volcanic effeéts can be difcovered, pajel> coumaties ng _Devonthire moft undoubtedly is fuch; yet, neverthelefs, the aun vat Bovey coal is there found fimilar to the furturbrand, in moft of the external, and (from experiments which I made fome years ago, I believe I may fay) chemical properties ; to which muft be added, that both thefe fubftances perfectly refemble each other, by forming regular ftrata.* * Tranf. of the Linnean Society, Vol. IV. p. 138. Von Troil’s ‘ Letters, p.42. Ofufcula Bergmanni, Tom. III. p. 239. Moreover, 200 MR. HATCHETT’S OBSERVATIONS ON BITUMENS, &c, — Deduction. Moreover, the half charred appearance of Bovey coal, and of furturbrand, “cannot be adduced as/ any proof, that the original vegetable bodies have been expofed to the partial effects of fubterraneous fire; for, at this time, we know that the oxidizement of fubftances is performed, at leaft as fre- quently, and as effeétually, by the humid as by the dry way. It would therefore be fyperfluous here, to enter into an ela- borate difcuffion, to prove that coal and bitumen, with much greater probability, have been formed without the interven- tion of fire; and I am the lefs inclined to fay more upon this fubjeét, as I have already publifhed fome confiderations on it in a former paper.* The new fub- Before I conclude, I muft beg leave to obferve, that as the ftance found ~— {ybflance _which:is found with the Bovey coal is, in every with the Bovey : ; : opal aaesied refpeét, fo totally different from any of the bitumens hitherto Retinafpbaltum. difcovered, it feems proper that it fhould receive fome f{pecific name; and, as it has been proved to confift partly of a refin and partly of a bituminous fubftance, I am induced to call it Retina/phaltum, + a name by which a full definition of its nature is conveyed. 3 Account of ane [have lately feen, in No. 85 of the Journal des Mines, p. 77, other fpecimeny ay account of a peculiar combutftible foflil, found near Helbra, ae oF the county of Mansfield, and defcribed by Mr. Voight, in ie his Verfuch einer Gefchichte der Stetnkohle, der Brawnkohle, &c, p- 188. This fubftance is of an afh-coloured gray, pafling to grayifh-white ; it is found in a bed of bituminous vegetable earth, which has apparently been produced by the decompo- fition of foffil wood. The pureft fpecimens are in the form of nodules; the fra@ture is earthy; it is opaque; foft; brittle; and is very light. When applied to the flame of a candle, it burns and melts like fealing-wax, at the fame time diffufing an odour which is not difagreeable. This fubftance appears to accord in’ fo many properties with the retinaf- phaltum of Bovey, that I cannot but fufpeét it to be of a fimilar nature, and I have little doubt that, -by a chemical ex- amination, it will be found to confift partly of refin and partly ‘of bitumen. ei * 'Tranf. of the Linnean Society, Vol. IV. pp. 141, &c, + From priivn, refin; and acParl@-, bitumen, Account IMPROVED AIR PUMP. 901 VII. Account and Defcription of an improved Air Pump. By Mr. N. Menvessoun. To Mr. NICHOLSON. SIR, Ox entering into bufinefs, as a mathematical inflrument- Introduétory maker, I refolved to make it my principal ftudy to introduce ltt into them all the improvements which the prefent advanced fiate of {cience, the nature of the fubjeét, and my humble abilities would allow. Thus I have begun with improving Volta’s electrical lamp and the air-pump. I imagine, I have rendered the conftruétion of the Jatter much more fimple than it ufually is, and confequently lefs liable to derangement, at the fame time that it poffeffes a very great exhaufting power. Give me leave, Sir, to offer you a delcription of this improved air-pump with the requifite drawings. It is ready for your in- fpection. I fhall think myfelf very happy, if this ufeful phi- lofophical inftrument meet with your approbation. And if it be fo fortunate, I requeft you the favour of introducing it into public notice, by inferting my paperin your excellent and defervedly celebrated Journal. Iam, with the higheft efteem, Sir, Your humble and obedient fervant, N. MENDELSSOHN. No. 50, Surry-Street, Black-Friars, Feb, 13, 1805. ; Eee Notwithftanding the many improvements which have been Defcription of made upon the conftruétion of the air-pump, it was ftill de- ae firable that this inftrament fhould be more fimplified in its pump. mechanifm, and yet poffels the fame advantages of thofe con- itru@ed lately. That the mechanical power of the pump, and not the preflure of the air, fhould open the valves, has long been required and already done by Mr. Cuthbertfon, Mr. Haas, and feveral other fkilful artifts; but may I be allowed to remark, that on reading the defcription of their inftruments, they ap- peared to me to be too compounded, It mnft be very difheult for 202 Defcription of Mendelffohn’s improved air- pump. IMPROVED AIR PUMP. for an experimental philofopher to clean an inftrument which, being thus complicated, is not only rendered intricate, but is alfo difficult to be put together again. Being defirous, there- fore, to fimplify this inftrament, I adopted the conftru€tion here defcribed, by which it is capable of being put together in lefs than half an hour when cleaned, and requires that operation very feldom. I fubmit to the judgment of your f{cientific readers how far the prefent inftrument anfwers its defired purpofe. I have reje@ed that tube which, in common air-pumps, leads from the valves to the receiver, together with the cock that ferves to fhut this pipe: the ‘receiver is placed immediately upon the valves, thefe being put on the top of the cylinders, which, confe- quently, required the rackwork and pinion to be underneath, and inverted the whole inftrument. Sce the adjoining draw- ing, Plate VI. where AB and CD reprefent the two cy- linders of glafs ground and polifhed infide. E and F are the two valves that allow the cylinders to communicate with the receiver O through two very fhort canals AB and CD (fig 2, Plate VII) and the cock G. Two other valves that open into the atmofphere are within the covers z and k, as may be feen in Fig. 1, where e reprefents oneof them. M N is the receiver- plate of glafs ground flat; P Q a barometer-gauge, upon the plan of the firft Torricellian tube, as the eafieft to conftruct and the moft infallible in its effeéts. It will be found to be here quite out of the way,.fecure from being broke by accident, ° and the-moft in fight. HK and I L are two brafs pillars that fupport the whole. RS V W the ufual rackwork, having a double winch J m, which, upon trial, will be found preferable to a fingle one. It will now be neceffary to flew how this pump aéts, in which it will be fufficient to explain the a€tion of one cylinder, becaufe the other is in all parts alike, E is a conical metallic _ valve, from which a canal goes through the cock G up to the receiver, as is feen in Fig. 1 and 2, Plate VII, where all the parts are marked with the fame letters. ET is a fleel rod going through a leather box in the pifton U. The top of this rod is fixéd to the valve E, and its bottom part flides ina fmall hole with an allowance of 0,1 inch up and downward, confequently the valve E can move no farther. When the pifton defcends, it firft opens the valve by pufhing the rod to the — . IMPROVED AIR-PUMP. : 903 the bottom of the hole. Then it ‘flides down along the rod Defcriptiou of E T, and the air from the receiver has now free scot to the hae ely cylinder. When the pifton returns it lifts the rod E T, and pump. thus fhuts up the valve. Then the pifton flides again along the rod up to the top of the cylinder, condenfing the air above it, which air, by the leaft condenfation, opens a valve e, Fig, 2, and efcapes freely. into the atmofphere, This laf valve has neither {pring or additional weight to fhut it, but fhuts by its own weight (about a quarter of an ounce) as foon as the pifton is arrived to the top of the cylinder. The cylinders are made of glafs, and the piftons of tin, fo well fitted as to be air-tight, without thé interpofition of any leathers. The friétion of thefe two bodies is {mall beyond ex- pectation, a fufficient proof that they will be durable. They poflefs the further advantage of being capable of ftanding for even fix months, after which time they will ferve without being cleaned or repaired, becaufe they are not liable to be corroded by the oil which they contain, an inconvenience too ‘general in brafs cylinders, After all, if the prefent pump fhould want cleaning, it is an eafy operation to take off the | top piece gh, by unfcrewing the nuts H and I, when this ‘ piece, with all the apparatus upon it, will come off, Then each cylinder may very eafily be flid off from the pifton, wiped out and replaced, afier having greafed ite infide witha little of the cleaneft {weet oi! : The top is then to be put again in its place, and the two nuts H and I being fcrewed upon it, the inftrument is ready. Neither racks or pinion need to be taken out of their places, the cylinders ftanding above them. The cock is conftruéted fo, that, being in the fituation re- _ prefented in Fig. 1, the communication is open between the cylinders, the receiver, and the barometer-gauge, and, bya quarter of a revolution, the cylinders are excluded, the re- ceiver and gauge being fiill left in communication. A little ftopper in Fig. 3, ground into the cock, being open, air is admitted to the receiver if required. The receiver-plate is of glafs ground. flat, as was men- tioned before; this will be found preferable to brafs, becaufe cleaner, and never corroded by acids or water ; it will befides often prove very convenient in making experiments on elec- tricity in the vacuum. The 904 LETTER CONCERNING PALLADIUM. The whole inftrument is fixed upon a mahogany table, which ferves as a ftand to it. I will conclude by obferving, that neither the employing of glafs cylinders, or the method of opening the valves, are new, but, for aught I know, this is the firft inftrument of the kind ever executed in this country; as likewife the idea of putting the valves at top, and thus iimplifying the inftru- ment, feems to have efcaped the attention of the eminent artifts both here and abroad; as to my beft knowledge, it has never been done or defcribed any where. The metallic pil-. tons, without leathering, muft certainly add to the durability, and diminifh the great labour that ufually attends working an air-pump, 1X. Letter concerning Palladium, from Witit1am Hype Wot- LasToNn, M.D. F. R. S. the Difcoverer of that Metallic Body. To Mr. NICHOLSON. SIR, The author ‘Tue candour with which you communicated all circum- adverts toformer A. nees that came to your knowledge concerning palladium, proceedings re- fpeGiing pal- ata time when the difcoverer of that fubftance was yet un- eae menown to you, demands my earlieft acknowledgments, as coverer. having been the author of thofe communications; and it is proper that I fhould alfo exprefs the fatisfaction I received on learning the refpe€table tribunal you nominated at my requeft, for examining the merits of any attempts that might be made to form that fubftance artificially, Reafons why the As I have already fhewn (in a paper which you did me fhe a teoery ie: Ramil to reprint in your Journal for January laft, p. 34,) edto the world by what means a very {mall quantity of Palladium may be anonymoufly. extraéted from the ore of platina, and as I have there examin- ed the fynthetic attempts to prove that this body was a com- pound, with a degree of attention which I thought due to the chemical {kill of the perfon who. propofed them, as well as to the degree of uncertainty that muft attend a fubjeé entirely new ; I cannot now adduce further chemical evidence and can only add, for the information of thofe whofe judgment has been biaffed by the difficulty of accounting for the pro. duction ; ON FOCAL IMAGES, duétion of fo large a quantity of palladium as was offered for fale, that a proportional quantity of platina, from which the whole was extracted, was purchafed by me a few years fince, with the defign of rendering it malleable for the different purpofes to which it is adapted. That obje@ has now been attained, and during the folution of it, various unforefeen appearances occurred, fome of which led me to the difcovery of palladium ; but there were other circumftances which could not be accounted for by the exiftence of that metal alone. On this, and other accounts, I endeavoured to referve to myfelf a deliberate examination of thofe difficulties which the fubfequent difcovery of a fecond new metal, that I have called rhodium, has fince enabled me to explain, without being anticipated even by thofe foreign chemifts, whofe at- tention has been particularly direéied to this purfuit. I remain, Sir, Your obliged and obedient Servant, W. H. WOLLASTON. Feb. 23, 1805. a. Short Remark on Mr. Walker’s laf Letter refpecting Focal Images. By C.L. To Mr. NICHOLSON. SiR, 1 WOULD beg your indulgence for a very fhort letter, in anfwer to Mr. Ezekiel Walker. The only reply which feems needful, on the fubjeét of the temper in which he or I may have written, is that if his firft paper had indicated more of the calm fpirit of philofophy, as well as of philofophical cor- re€tne{s, my obfervations might either have been unneceffary, or, perhaps, drawn up without any extraneousremark. As it is, Ido not think myfelf entitled, nor am I indeed inclined to offer any ftri€tures upon his laft; which I leave to the un- - biaffed judgment of your readers. On the prefent occafion, T only wifh to adhere to the experiments. Men of feience will find no difficulty in forming a proper eftimate of our reafonings, In plain language, therefore, I will beg leave : ta 205 C. L. declines any farther dif- cuffion refpect- ing Mr. Walker’s experiments with lenfes; but denies the facts. 206 “ USE OF GREEN VITRIOL to wave any attention to the hiftory of Mr. Walker’s experi- ments, upon which I have animadverted, and to deny his faéts. What may have’deceived him in his proceedings, his admeafurements, and his repeated regifterings, is not for me to difeufs. If he will fend his lenfes to you, and you fhould find that, under any circumftances whatever of diftance or pofition, it be poffible, by a mere alteration in the aperture, to preduce a difference, as 2 to 3, in the length of the focal image, (fee Philof. Journal, Vol. IX. p. 165.) I think it will be incumbent upon us to re-examine all the faéis and demonftra- tions, of what we have hitherto been in the habit of calling the fcience of optics, in order to reconcile them with fo ftrange a refult. Lam..Sin Your obliged C. L. A; A Communication on the Uje of Green Vitriol, or Sulphate of Tron, as a Manure; and on the Efficacy of paring and burn- ing depending, partly, on Oxide of fron. By GEoRGE Pearson, M.D. Honorary Member of the Board of Agri- culture, F. RS. From a Communication made by him to the Board, and inferted in the fourth Volume-of their Tranfacions, Sulphate of iron | TAKE leave to lay before this Honourable Board, an ac- or martial vitriol . 7 : hitherto fuppofed Count of a fubftance as a manure, which I find, on examina- deftru@ive of tion, is one of the things, hitherto univerfally believed to be MS ERED a poifon to vegetables. Having afcertained that this fubftance is what is commonly known by the name of vitriol of iron (the fulphate of iron of the chemifts), inveterate opinion prevented me for fome time from accepting the teftimony of it as a ma- nure; but feeling the weight of the refpe€table evidence by whom it was attefted, after confideration I perceived that the fa&t in queftion was not at variance with eftablifhed principles of vegetable philofophy, as I fhall, I think, make appear in this communication. —but the con- My friend John Williams Willaume, Efq. of Tingrith in trary istiuee = Bedfordthire, having defired his brother, Charles Dymoke Willaume, E{q. to afk my opinion of a faline fubftance col- c le€ied AS A MANURE. 907 leéted from peat, which has been ufed with profitable confe- quences as a manure in his neighbourhood; I propofed a fet of queries to Mr. John W. Willaume, the anfwers to which, in the two following copied letters, comprehend the evidence I have tor offer. LETTER No. I. To Dr. Pearfon, fron C. D. Willaume, E/q. My pear Sir, I ReEcEIVED the inclofed laft Saturday, and hope the an- Letter of infor- fwers to your queries will be fatisfa€tory, and tend to elucidate apeiicee this curious fubje@. Though the an{wers under the article du duft. only relate to your queries, yet my brother has thought proper to advert to the afres, which you conceive to be a caput mor- tuum; but which have been ufed as, and have been fuppofed to be, a beneficial manure from time immemorial. I have re- ferved a piece of the peat from which the afhes are produced, and if you would with to analyfe it, I willfend it you. Fae vour me with the refult of your future inquiries on this fabje@, and I am, My dear Sir, your’s very fincerely, Walham Green, C.D. WittauMe. Aug. 24, 1801. LETTER No. II. From John W., Willaume, Efg. to C. W. Willaume, Efy. - Queries propofed by Dr. Pearfon. 1. How long has the falt of peat been ufed £ Queries refpecte - 2. How much per acre is laid on? ing falt of peat. 3. On what kind of lands? 4. The effeéts of it on vegetation ? 5. Whether it is mixed with dung manure, or lime? 6. In what parts of the country has it been employed ? 7. Any other faéts which can be colleéted relative to the ule of this fubftance ? In anfwering the above queries, I fhall divide the fubjeé into three articles, 1{t, the peat confidered as an objeét of fuel; 2d, the afhes; 3d, the falt of peat, or duft; the two laft as objeéts of manure. ; : 1, Peat 908 USE OF GREEN VITRIOL Defeription of 1. Peat. The peat, which is found after the removal of the aii turf or exterior furface, to about a {pade’s depth, has long been known as amarticle of fuel. It is, however, ufed only by cottagers, who burn it on a brick hearth; it has been re- je€ted from the parlour, the kitchen, the brewhoufe, &c. as being injurious to grates, and to all forts of veffels put on it; it cannot be employed in the roafting of meat, as it will im- part a difagreeable tafte, and it is deftruétive of all forts of fur- niture by the effluvia which it emits, or by the duft or athes which may chance to be blown from it. If thefe difagreeable confequences could be obviated, it might be made an article of general confumption as a fubftitute for coal, much to the advantage of the feller and confumer; it is dug out in the form of abrick to acertain depth, well known to the common labourer, This depth muft be carefully atfended to, left you fhould cut out the ftaple, in which cafe it would never be re- trieved; but, this circumftance attended to, it will grow again to its former ftate in the fpace of fifteen years. Thus the whole moor is divided into proper portions, and periodi- cally cut once in fifteen years. Its afhes. 2, Afhes. The turf or furface, and fuch nade of the peat as do not appear to be of the beft quality, are laid up in con- fiderable heaps, and reduced to afhes by the aétion of fire. The afhes are red. Anfuer to Queries. Anfwers tothe 1. The afhes have been long known as a manure, and the queries as to the demand is on the increafe. i 2. The quantity ufually laid on an acre, by fpreading or fowing it, is fifty bufhels, either on grafs or arable land. 3. It is laid on hot land. By hot land, we underftand fandy, gravelly, chalky foils of a dry nature, fuch as are burnt up on the long continuance of hot weather. It is moft commonly ufed for graffes ; but is in confiderable efteem, as a manure, for oats or barley on land of the nature above-men- tioned. 4, The vegetable effeé is furprifing, inafmuch as it will double or treble a crop of any new fown grafs, fuch as trefoil, &c. have feen the benefits arifing from it on old pafture land much overgrown with mofs, which it effectually deftroys, , and produces in its flead white or Dutch clover. Youmay ~ trace AS A MANURE, 209 trace to an inch the ceffation and recommencement of this manure. It is obfervable, that near the fire heaps, as far as the wind can carry the lighter parts of the afhes, the produc- tion of clover is fure to be abundant; it is equally favourable _to the growth of barley or oats. ibis 5. It is not mixed with lime, or any other manure. 6. Thefe afhes are bought by a fet of higlers, who carry them in bags loaded on affes to a confiderable diftance, where they are known to be in great repute; they muft come excef- fively dear to the confumer by this mode of conveyance. The farmers in the vicinity fend for them in waggons, particularly Mr. Brumiger, near Sundon in Bedfordhhire, a confiderable and intelligent farmer, who increafes his confumption every _ year, both for his grafs and arable land. 3. The Salt of Peat, or Dujt. Anfwer to Queries.-1. The duft or gray faline fubftance is Anfwers refpects produced by beating the earth containing this falt toa pow- inde eit der ; it is found in particular fpots, not univerfally, the earth not being equally impregnated with it in all places; it has not been known as a manure above fix years; but on trial greatly increafes in reputation and demand. 2. Fifty bufhels are the proper quantity per acre. This fhould not be exceeded, for if it be laid on in too great abun- dance, it may prove extremely deleterious. 3. It is ufed for cold lands. By cold lands we underftand clayey, or any wet grounds. 4. It will much improve the vegetation of fowed graffes, and old pafture, and is equally favourable to the produétion of corm; the ground, whether grafs or arable, being of a cold nature. 5. It is not mixed with lime, or any other fubftance. 6. The duft is likewife bought by the higlers, and carried to great diftances. The nearer farmers likewife fend for the duft in waggons, particularly Mr. Anftie, of Dunftable Hough- ton, and Mr. Smith, of Sundon, who hold this manure ir great efteem. Your’s, &c. Tingrith, dug. 19, 1801. J. W. Witraumg. Vor. X.—Marcu, 1805. P Dr. 210 USE OF GREEN VITRIOL Dr. Pearfon’s Experiments, Obfervations, and Remarks on the Subftance called Salt of Peat, or Dujt. Dr. Pearfon’s 1. It is a blackifh gray, coarfe, and rather heavy powder. chemical exami- Ffas no fmell; taftes ftrongly ftyptic; readily diffolves in the nation of falt o peat or duft, mouth; did Hat deliquefce on expofure to the ar. "2, Diffolves ini four times its weight of water of ‘the tem- perature of fixty degrees of Fahrenheit, and in twice its weight of boiling hot water, giving a pale green coloured rant eed with a trifling fediment, which is infoluble in muriatic acid. 3. To the folution (2.) I added a little liquid prufhate of vegetable alkali in a perfeétly neutral ftate, which occafioned immediately a moft abundant precipitation of pruffiate of iron; and this teft was added gradually, till no further precipi- tation took place. 4, Into the decanted and _filtrated fluid (3) was poured li- quid cauftic volatile alkali, but without inducing any change. 5. Into the fame fluid (3) was poured liquid carbonate of vegetable alkali, which produced a {carcely perceivable cloudy appearance, 6, Into the folution (3) was dropped the aqueous folution of muriate of baryt, which occafioned immediately a milky appearance. 7. To the folution (3) I added the oxalic acid, and turbid- nefs enfued. 8. A little of the powdery fubftance, called the falt of peat, with concentrated fulphuric acid, produced no emiffion of fumes, nor {mell. 9, The folution (2) with muriate of baryt, immediately grew thick and white as cream. 10. The folution (2) with carbonate of potafh, depofited a very copious greenifh fediment; and the fame effect enfued with cauftic volatile alkali. 11. Phe folution (2) with oxalic acid, gave inftantly a very turbid bluifh green precipitation. The preceding experiments manifefted that the peat falt-con- filts of fulphate of iron, vulgarly called green vitriol of iron, mixed with a very minute proportion of filicious earth, and of lime uniled either to fulphuric acid, or to. carbonic acid, But the prefence of the earths magnefia and argill; the uncom- bined AS A MANURE, 2h bh bined alkalies; the uncombined acids; are by thefe experi- ments excluded, In fhort, the falt of peat is almoft pure sul- phate of tron. 7 Remarks. 1. The falt of peat is, I apprehend, depofited by evapo- Salt of peat how rations which run over the moors, where it is found; and Produced. hence I fhould expect many of fuch waters to be ftrongly im- pregnated with it, and in many parts the foil to be tinged red and yellow by ochre. Very likely * on enquiry much iron pyrites will be found on, or near the moors, 2. The quantity {pread on land is faid to be fifty buthels per Its quantity muit acre, which J eftimate at 2,250 pounds avoirdupoife; this wall. ots ay give near feven ounces anda half per fquare yard. If alarger quantity be applied, it is obferved it will prove extremely de- Jeterious. This is true alfo of every other manure, fuch as lime, alkaline falts, marine falt, nay, of the dung of animals: forif they be ufed in certain quantities, they poz/on plants, in- ftead of promoting their growth. This is equally true in the animal kingdom ; for there is not an article taken as food, or as feafoning, which is not a poifon, if taken in certain quan- tities. A human creature may be poifoned or alimented by and it is hurt- beef or pudding, according to the quantity of them taken into gh ovat the ftomach. He may be poifoned, or have digeftion greatly condiments alfo affifted by falt, or pepper, according to their quantity. _In*** brief, the vulgar notion of the term pozfon is erroneous: for by it is conceived that fubftances fo called are in their nature _ ~pofitively deftruétive of life; but the truth is that the moft vi- rulent poifons are, in all reafon and faét, only deleterious ac- cording to the quantity applied. White arfenic fwallowed in the quantity of ten grains or lefs, will deftroy life; but in the quantity of one-fixteenth of a grain, it is as harmlefs asa glafs of wine; and further, in that dofe is a remedy for inveterate agues, From thefe confiderations I conclude, that there is no ad- miffible contradiétory evidence to the teftimonies for the fer- # « This is,” fays Mr. Willaume, ‘‘exaély the fa&. This ful- phate of iron, the falt of peat, during the heat of the fummer is frequently found in a chryftalized ftate, very white, and crackling under the feet; but is deliquefcent in that form, and turns to its former dark colour when the air becomes moift.”—-Note by Mr. Fs - W. Willaume. ah PQ tillizing Q12 USE OF GREEN VITRIOL ; tilizing effect of fulphate of iron, unlefs by fuch contravening evidence the quantity ftated to be ufed exceed fifty bufhels per acre; it being an eftabliflred fa@t, that in certain proportions this metallic falt isa poifon to plants. This difcovery of Mr. Willaume will, I think, give new light, fo as to explain fully the rationale of the improvement of land by the burnt earth and afhes from paring and burning. | It is ufual to account for the effeéts of this procefs, by refer- ting to fuppofed alkaline or other falts; but of thefe there is no evidence, nay, on trial I have not deteéted them, or at leaft not in any efficient quantity ; but this I know, that {uch earth and afhes contain oxde of iron, and as I fufpeét of mangane/e ; which from the analyfis, and the effeét of falt of peat, muft now be-admitted into the clafs of manures. This very com- munication of Mr. Willaume, affords evidence of the truth of this conjecture, for the afhes of the peat which afford the falt «« have been long known as a manure, and the demand 1s on the increafe :” of courfe, thefe afhes contain an unufual quan~ tity of oxide of iron. A confequence of this reafoning is, that the burnt earth of foils will, ceteris paribus, fertilize in proportion to the oxide of iron it contains. Accordingly the afhes of the peat, fays Mr. Willaume, have a furprifing ef- fect, they “will double or treble a crop of any new-fown gtafs, fuch as trefoil, &c.” they are fo beneficial, that in fpite of the expence they are carried in bags by higlers to great dif- tances. It would be extending this paper beyond the propofed limits, to reafon at a greater length, and to make a further in- duétion of faéts: therefore I will clofe with afferting, that the more I contemplate the fa&ts in Mr, Willaume’s letter, the more evidence | perceive for the truth, that metallic falts, and metallic oxides in general, and falts and oxides of iron in par- ticular, are manures, if applied in proper dofes. itis confiderea 1 do not think it is within the defign of this paper to make as effeétive upon obfervations on the anfwers to the 2d, 3d, 4th, 5th, and 6th the fame princie ¢. ple as condi- queries, except, once for all defiring that it may be under- ments or feafon {tood, that I confider the falt of peat and the afhes of peat, as fay, operating in promoting vegetation analogous to feafoning, or condiments, taken with the food of animals ; that is, analogous to muftard, cinnamon, ginger, &c, which are not of them- felves at all or neceffarily nutritious, but contribute to render, other things nutrilious, by exciting the a@ion of the ftomach and AS A MANURE, and other organs of digeftion and affimulation. I have no doubt of the truth of the propofition, that no living thing, neither plant nor animal, can grow and live in a ftate of vifi- ble aétion without conftant fupplies of matter which has been alive ; in other words, living animals and vegetables can only live on dead animals and dead vegetables. No plant, nor ani- mal has ever been known by experience, nor in the nature of things does it feem reafonable, that they can be nourifhed by mere water and pure air, as fome perfons have afferted. I fhall make a few remarks on the other tro fibftances which are the fubjeét of Mr. Willaume’s letter. 2. The Peat. 213 The peat is a denfe mafs of vegetable matter for a certain Chemical re« depth, partly in a dead and partly ina living ftate, with which ™** 0” Peate is mixed more or lefs earth, and in burning it affords fo much eimpyreumatic oil, as to give a difagreeable tafte to roafted provifions; hence, as we are, told, it has been rejeéted from the kitchen. This fuel affords a vaft quantity of what the chemifts call ignic acid ; hence it is rejeéted alfo from the parlour, as very deftruétive to the grates. I beg to fuggeft that this lignic acid might be faved in burning the peat as fuel, and be ufed for various purpofes in manufactures; and the charred peat may be ufed in place of charcoal of wood. Pro- bably too other ufeful products will be found, on examining the matters more accurately which are afforded by diftillation. 3. Afhes. If the peat were mere vegetable matter, the afhes afforded The athe by it would be as trifling as thofe of wood; but fome parts of Eee ihe moor contain fo much.earth and oxide of iron, as to leave behind, on burning, a confiderable quantity of incombutftible matter; and fuch kind of peat, we are told, is not ufed as fuel; but, after burning, the refiduary matter is an efficacious manure, much more fo than is commonly afforded by paring and burning. The afhes are more red and more fertilizing than afhes of common turf, becaufe they contain more iron. The fpontaneous fpringing up of white clover, in land ma- produce nured with thefeafhes, is fimilar to the fpontaneous growth of clover, this plant on heath land, which has been covered with lime to deftroy all its prefent vegetation ; and this fa¢t thews that pro- bably 214 Explanation. Omiffion ftated to be made in Accum’s che- mifiry. Paffage where the fuppofed omiffion is found, PRACTICAL CHEMISTRY, P bably thefe are feeds buried in the earth for many ages, which yet remain alive, but do not grow until expofed to the ftimuli of air, water calorific, and lifelefs animal, or vegetable matter, (To be concluded in our next.) XII. Letter from Mr, Accum, refpe@ing an Error ftated to exift in his Pradtical Chemifiry. To Mr. NICHOLSON. SIR, Compton-Street, Soho, Feb. 16,.1805. W. F. C. cenfures me in your Journal, No. 38, page 105, of not having given in my book on Praétical Chemiftry “The means of preparing either nitric acid, or nitrate of potash, or rather having fated them by implication, as incapable of being produced by ari.” The fidelity with which you have laid his remarks before the public, encourages me to hope, that with equal impartiality you will allow me to appear before the fame tribunal, in order to plead to this accufation NoT GUILTY. For ihe method of obtaining nitric acid from its conftituent principles, W. F. C. may read in the Vol. I. page 211. In order to let the judicious readers who are not in polfeffion of the work, judge for themfelves, I beg leave to lay before them the meihod there pointed out, which literally runs thus: “« Take w barometer tube, the diameter of which is about 4 part of aninch, Shut one of its extremities with a cork, through the middle of which pages @ fmall wire with a ball of metal at each end. Fill the tube with mercury and invert it into a bafon of this fluid. Throw up into this tube as much of a mixture of 12 parts of nitrogen gas, and 87 parts of oxigen gas as will fill 3 inches. Through this gas by means of the wire in the cork pafs @ number of electric fparks; the volume of the gas gradually diminifhes, und in ity place will be found nitrous acid.” * * Nitrous acid doesnot differ from nitric acid, in compofition, but merely by the admixture of nitrous gas. See the book under con. fideration, Vol. II. p. 288. It — ee eae DURABLE AND SUPERIOR LAKE. 915 _It appears that W. F. C. has not noticed thefe lines. The production of nitric acid by fynthefis, being here clearly ftated, his animadverfion relative to that fubje& falls to the ground. To exculpate myfelf from his further accufation, namely, of Other explana- not having noticed the produ€tion of nitrate of potafl: by arti-°"* ficial means, or rather having ftated it by implication, will be- come equally erroneous, on reminding him, that the method of preparing this falt artificially is pointed out, Vol. II. page 287, thus, ‘‘ Nitrate of potafh may be prepared by neutralizing carbonate of potafh with nitric acid,” From what has been ftated, it is obvious that W. F. C.’s remarks are not correct, for both the methods of obtaining ni- tric acid, and nitrate of potath are correétly given, and not by implication, as W. F. C. apprehends. I have the honour to be, Sir, Your’s, ; FREDERICK ACCUM, AUT. Proceges for obtaining a durable and fuperior Lake from Madder, By Sir H.C. Encierizzrp, M.P. F.R.S.* Tue want of a durable red colour, which fhould poffefs IntroduCtions fomething of the depth and tranfparency of the lakes made from cochineal, firft induced me to try whether the madder root, which is well known to furnifh a dye lefs fubjeét to change by expofure to air,-than any other vegetable colour, except indigo, might not produce fomething of the colour I wanted. Several of the moft eminent painters ‘of this country have, Madder lakes fer fome time, been in the habit of ufing madder lakes in oil neady ahaa bel pictures: but the colours they poffeffed under this name were they were bad. either a yellowifh red, nearly of the hue of brick-duft, or a ~ pale pink opake, and without clearnefs or depth of tint, and quite unfit to be ufed in water-coloured drawing, which was the principal obje& of my fearch. My firft attempts were to repeat the procefs given by Mar- Margraf’s pro i ‘ . fford graf, in the Memoirs of the Academy of Berlin: but the co- Hodge toe * From the Tranhfa&tions of the Society of Arts, who voted the gold medal in honour of this difcovery. 1804. lour 216 becaufe moft of the colour yemained in the Yroot, Water takes up little of the colour. Whence mecha- ‘nical preffure is advifaple, Procefs x. ‘Two ounces of madder were pounded in a bag with a pint of water ; DURABLE AND SUPERIOR LAKE. lour produced by this mode was of a pale red, and very opake, although the eminent author of the procefs ftates the colour he produced to be that of ‘le /ung enflummé,” which probably means a deep blood colour. It may, however, be obferved, that colours prepared with a bafis of alumine will appear much deeper when ground in oil than they do in the lump, the oil rendering the alumine nearly tranfparent. This advantage is however, loft in water-colours, On examining the refiduum of the madder root, after it had been treated in Margraf’s me- thod, it appeared tinged with fo rich a red, that it was obvious, that by far the greater part of the colour ftill remained in it, and that the moft powerful and beautiful part. To extraét this, feveral ineffectual trials were made, which it would be ufelefs to enter into; but, on attentively examining the ap- pearances which took place on infufing the madder in water, I began to fufpeét that the red colouring matter was very little, if at all, foluble in water, and that it was only mechanically mixed with the water when poured on the root, and fufpended in it by the mucilage, with which the root abounds. A very {mall quantity, therefore, can be obtained by any in- fufion or decoétion, as the greater part finks down on the root, or remains with it on the fieve, or in the bag, through which the infufion or decoétion is paffed to render it clear. I there- fore was induced to try whether, by fome merely mechanical means, I could not feparate the colouring matter from the fi- brous part of the root. In this attempt my fuccefs was fully equal to my hopes; and, after feveral trials, I confider the procefs I am now about to deferibe, as the moft perfeét I have been able to difcover. Procejs 1. Enclofe two ounces, troy weight, of the fineft Dutch madder, known in commerce by the name of crop madder, in a bag, capable of containing three or four times that quantity, and made of ftrong and fine calico. Put it into a large marble, or porcelain mortar, and pour on it about a pint of cold foft water. The Thames water, when filtered, is as good as can be ufed; it being very nearly as pure as dif- tilled water, at leaft when taken up a very little way above London. With a marble or porcelain peftle, prefs the bag ftrongly in every direétion, and, as it were, rub and pound it asmuch as can be done without endangering the bag, The water will very foon be loaded with the colouring matter, fo as DURABLE AND SUPERIOR LAKE. oa as to be quite opake and muddy. Pour off the water, and The water when add another pint of frefh water to the root, agitating and tri- ries cae turating it in the manner before defcribed; and repeat the off and another operation till the water comes off the root very flightly tinged. ie Tee About five pints of water, if well agitated and rubbed, will fore: : extraét from the root nearly the whole of its colour; and if Five fucceffive the refidual root be taken out of the bag and dried, it will be Ents Cee found to weigh not more than five drachms, apothecaries ing five drams ef weight; its-colour will be a kind of light nankeen, or cinna- bre. mon, and it will have entirely loft the peculiar odour of the root, and only retain a faint woody {mell. The water loaded with the colouring matter, muft be put The coloured into an earthen or well-tinned copper, or, what is ftill better, line Kats a filver veffel, (for the ufe of iron muft be carefully avoided through the whole), and heated till it juft boils. It muft then be poured into a large earthen or porcelain bafon, and an ounce and one oz. of troy weight of alum diffoived in about a pint of boiling foft a pitt df beilieg water, muft be poured into it, and ftirred until it is (horoughly water added ; mixed. About an ounce and a half of a faturated folution ee mild vegetable alkali fhould be gently poured in, ftirring the a precipitate of whole well all the time. A confiderable effervefcence will ©¥r take place, and an immediate precipitation of the colour. The whole fhould be fuffered to ftand till cold; and the clear yellow liquor may then be poured off from the red precipitate. A quart of boiling foft water fhould again be poured on it, and well ftirred. When cool, the colour may be feparated from Edulcoration, the liquor by filtration through paper in the ufual way; and eee boiling water fhould be poured on it in the filter, till it paffes half an ounce through of a light ftraw colour, and quite free from any alka- af Sie Jine tafte. The colour may now be gently dried ; and when quite dry, it will be found to weigh half an ounce ; juft a fourth part of the weight of the madder employed. ) By analyfis, this colour poffeffes rather more than 40 per i Mai erg cent. of alumine. If lefs than an ounce of alum be employed (7 )'°° with two ounces of madder, the colour will be rather deeper ; but if lefs than three quarters of an ounce be ufed, the whole of the colouring matter will not be combined with alumine. On the whole, I confider the proportion of an ounce of alum to two ounces of madder, as the beft. Procefs 2. If, when the folution of alum is added to the Procefs 2. water loaded with the colouring matter of the root, the whole Hf he Macerae procefs 3. be be iuffered to cool 18° DURABLE AND SUPERIOR EAKE. and fettle after be fuffered to ftand, without the addition of the alkali, acon-. hea j, fiderable precipitation will take place, which will be of a dark a duljred fedi- dull red. The remaining liquor, if again heated, will, by the mg a admiflion of the alkali, produce a rofe-coloured precipitate of “ r re Hs tee bp ing Auidif «2 beautiful tint, but wanting in force and depth of tone. heated and pre-e This is the procefs recommended by Mr. Watt, in his et atreeds a Effay on Madder, in the Annals de chymie, Tome7; and this fine but not latter colour is what may perhaps, with propriety, be called 5 rersareen aes Lake. But, although the lighter red may be exe cellent for many purpofes, yet I confider the colour produced by the union of the two colouring matters, as given in the firft procefs, as far preferable for general ufe, being of a very beautiful hue when ufed thin, and poffefling unrivalled depth and richnefs either in oil er water, when laid on in greater body. “Lefs alum caufes If but half an ounce of alum be added to the two ounces of the fecond pre- the root, the firft precipitate will be nearly fimilar to that cipitate to be ‘ lefs in quantity, When an ounce is employed; but, the fecond, or lake pre- but richer. —_cipitate, will be lefs in quantity, and of a deeper and richer , tint. Jn this cafe the whole of the colouring matter, as be- fore obferved, is certainly not combined with the alumine ; for, on adding more alum to the remaining liquor, a pre- cipitate is obtained of a light purplifh red. In this procefs, when two ounces of madder and an ounce of alum are ufed, the firft precipitate has about 20 per_cent. of alumine, and the fecond, or lake precipitate, about 53 per cent; but thefe proportions will vary a little in repetitions of the procefs. Procefs3. When Procefs 3. If the madder, inftead of being wafhed and ses aCe iS triturated with cold water, as directed in the foregoing procefs, boiling snftend be treated in exaéily the fame manner with boiling water; the of cold water, colour obtained will be rather darker, but fcarcely of fo good the colour is ; < neither fo good 2 tints and the refiduum of the root, however carefully preffed nor fo plentiful. and wafhed, will retain a flrong purplifh hue; a full proof | that fome valuable colour is retained in it, probably fixed in the woody fibre by the aétion of heat. Mr. Watt, in his excellent treatife on madder above mentioned, obferves» that cold water extracts the colour better than hot water; and I have reafon to fufpeét, that a portion of that colouring matter, which produces the bright red pigment, diftinguifhed before by the name of Madder Lake, remains attached to the root, when acted on by boiling water. Procefs 4. e produced from it by Procefs 1, is of a deeper and jicher tint DURABLE AND SUPERIOR LAKE, i 919 Procefs 4. If to two ounces of madder, a pint of cold water Procefs 4. If the be added, and the whole be fuffered to ftand for a few days i oe (three or four days) in a wide-mouthed bottle, lightly corked, before wathing \in a temperature of between 50° and 60°, and often fhaken ; is ey in a flight fermentation will take place, the infufion will acquire mucilage . fe a vinous {mell; and the mucilaginous part of the root will be ftroyed by fer- in a great degree deftroyed, and its yellow colour much lef- Pita rs a fened. If the whole be then poured into a calico bag, and eafily extraéted; the liquor be fuffered to drain away without preffure, and oa tanotsle then the root remaining in the bag be treated with cold water, &c. exaétly as direéted in the firft procefs, the red colouring matter will quit the root with much greater eafe than before fermentation. It wil! alfo be equal in quantity to that afford- ed by the firft procefs, but of a much lighter red. This dif- ference of tint appears to be owing to a deftruétion of a part of the lake by the fermentation of the root; for if the colours from the fermented root be obtained feparate, as in Procefs 2, the firft precipitate will not fenfibly differ from that obtained from the untermented madder, but, the fecond, or lake will be of a very light pink. This procefs, then, is not to be recommended. Spanifh and Smyrna Madders. Spanith Madder affords a colour of rather a deeper tone Spanifh madder than the Dutch Madder, but it does not appear to be of fo menue _ pure a red as the Zealand Crop Madder. colour than : 5 , Dutch madder. The Smyrna Madder is a very valuable root. The colour Smirashnudies is better than than any I have obtained from the Duich Madder. ~The Dutch ~ quantity produced from two ounces, is only three drathms, twenty-four grains: but this is not to be wondered at; for as this madder is imported in the entire root in a dry ftate, and the Crop Madder of Zealand confifts principally of the bark, in which probably the greateft part of the colouring fubftance refides, there is every reafon to think thatthe Smyrna madder really contains a greater proportion of colour than the Zealand, in equal weights of the eniire root. The produéts of Procefs 2 prove, that ‘the lake of the Smyrna madder is more abundant in quantity, and of a richer tone than that of the Dutch root; for, from two ounces of Dutch madder the firft precipitate was two drachms, and the Jake was two drachms and forty eight grains; whereas, from ie 4, two > 90 DURABLE AND SUPERIOR LAKE, two ounces of the Smyrna root the firft precipitate was one drachm and twenty four grains, and the lake was two drachms and twenty-four grains. The proportion of the lake to the other colour is, therefore, much higher in the Smyrna, than in the Dutch reot. Frefn Madder. The recentroot_ The colour may be “prepared from the recent root; and it is preferable. F 3 ; ; , will be of a quality equal, if not fuperior, to any other. The difficulty of procuring the frefh root has prevented me from making as many experiments on it as I could have withed, I procured, however, a {mall quantity of the beft roots packed in mofs from Holland, and the following procefs anfwered perfectly well. Experiment ac- Eight ounces of the root having been firft well wafhed and age ee cleaned from dirt of all kinds, were broken into {mall pieces, madder 3 and pounded in a bell-metal mortar, with a wooden peftle, till reduced into an uniform pafte. This pafte being enclofed in a calico bag, was wafhed and triturated, as defcribed in the firft procefs, with cold water. About five pints feem to have extracted nearly the whole-of the colour. To the water thus loaded with colour, and boiled as before, one ounce of alum, diifolved in a pint of boiling water, was added, and very fuecefsful. the alkali poured on the whole, till the tafte of the mixture was juft perceptibly alkaline. The colour thus obtained, when dry, was of a very beautiful quality. It promifes The fuccels of this experiment, which was twice repeated aceon i with the fame refult, has led me to hope, that it is not im- poflible that the mode of obtaining the colour from the frefh root here defcribed, may be produ@tive of advantages for more extenfive ufe than I had in view when firft I attempted to obtain a pigment from madder. Many tracts of land in this country are as well adapted to the growth of this valuable article, as the foil of Holland can be; and the cultivation of it, which has more than once been attempted to a confiderable extent, has been laid afide, principally from the expence at- tendant on the ereétion of drying-houfes and mills, and the great expence and nicety requifite for condu€ting the procefs For if the colour of drying. But fhould the colour prepared in the mode juft a pe for defcribed, be found to anfwer the purpofes of the dyers and would fave dry- ¢alico-printers, the procefs is fo eafy, and the apparatus re- ing and carriage 5 -* quired DURABLE AND SUPERIOR LAKE. 29} quired for it fo little expenfive, that it might be in the power of any grower of the root to extra@ the colour: befides which, another great advantage would be obtained; the colour thus feparated from the root, may be kept any length of time, without danger of {poiling, and its carriage would be only one fourth of that of the root. I am, moreover, thoroughly inclined to believe, that in the prefent mode of ufing the root, a very confiderable part of the colour is left in it by the dyers; and, fhould this prove to be the cafe, an 24 probably be advantage much greater than any hitherto adverted to, may ey eee arife from the procefs here recommended. : Should it be attempted to obtain the colour from the frefh Direétions for root, on an extenfive fcale, IT fhould recommend, that the censtatincs ok root be firft reduced to as uniform a pulp as poffible, by grind- madder colour. ing or pounding. To this purpofe, it is probable that the cyder-mill would anfwer perfeétly well; and its extreme fimplicity is a great recommendation. For the purpofe of trituration, bags of woolen, fuch as are ufed in the oil-millsy would probably an{wer as well as calico, and they would be much cheaper and more durable. A large vat, with ftampers, would be eafily conftruéted, by thofe who are converfant in mechanics, for the holding them and prefling them in water ; and when the colour was boiled and precipitated, the. flues of the boilers might eafily be formed into convenient drying ’ tables, without any additional expenfe of fuel. The part of the procefs, which I confider as of the greateft importance, and as being the effential advantage of my methods over all thofe which have come to my knowledge, is the trituration or prefling of the root in water; and I believe that the colouring matter of the root has not been hitherto confidered as fo nearly infoluble in water, as I have reafon to think it is. . It were much to be wifhed, that in the prefent advanced We want a good flate of Chemiftry, fome {kilful analyfer wouid inveftigate gg of ag the properties of this very ufeful root; in which perhaps it will be found, that there are three, if not four, different colouring fubftances. Such are the procefles and views, which I have thought it not improper to fubmit to the con- fideration of the Society of Arts, &c. I have only now to defcribe the fpecimens which accom- The fpecimens pany this paper ; affuring the Society, that they have been all pe ir cia prepared by my own hands entirely, and that I am therefore refponfible may be kept fur along time, 299" DURABLE AND SUPERIOR LAKE, refponfible for their having been produced by the proceffes ftated, without the addition of any foreign matter whatever, excepting the cake ground up with gum, and the bladder of oil-colour, which were prepared from the colour which I gave him, by Mr. Newman,- of Soho-Square, whofe {kill and fidelity are too well known to need any teftimony in their favour. It may be proper to add, that all the colours produced frais the Dutch madder were prepared from the fame parcel of crop madder, in order that the differences in them might proceed from the proceffes, and not from,a variation in the qualities of the root, which, in different {pecimens, will produce differ- ent fhades of colour under the fame mode of treatment.* 1. Dutch madder, treated by procefs Ift, Do Oy > itp apes - procefs 2d. 3. Ditto - - - = procefs 3d. 4,.Ditto -. .5 .-., =. procefs 4th, 5. Dutch madder, two ounces; alum, half an ounce; treated by procefs 2. ) 6. Dutch madder, two ounces; alum, one ounce; fer- mented two days, and then treated by procefs 2. 7. Produce of procefs.1, ground in gum by Mr. Newman. 8. Produce of procefs 1, ground in oil by Mr. Newman. S—1. Smyrna madder, by procefs 1. S—2. Dilto - - - procefs 2 S—3. Ditto - - - procefs 3. S—4. Ditto - - - procefs 4. * Certificates accompanied the foregoing defcription, from Mr. Cotman and Mr. Munn, teftifying the merits of Sir H. Engle- field’s madder lakes, as water colours; and alfo, from Mefirs. ~ Weft, Trumbull, Opie, Turner, Daniel, and Hoppner, fpeak- ing greatly iu its favour, where it has been tried in oil-colours. - The DUTCH METHOD OF CURING HERRINGS, 935 XIV. The Dutch Method of curing Herrings, exira&ed and tranflated Srom the German of Kriinitz’s_ Economical Encyclopadia (Oeconomifche Encyclopadie), Article Hiiring, by J. Hincxiey, Ef. F.S. A.* ‘Tue veflels employed in this fifhery, commonly called her- Dutch method ting-buffes, from the Dutch name, are generally between 49 ° catching and and 60 tons burthen, though fome from 40 to 80 and 100 tons face oi are ufed. The largeft of all carry 120 tons, are three-mafted veflfels, with one deck, and a cabin at each end; that. a-head ferving asakitchen. Of the larger, the crews are 24 men, thofe of the fmaller 18. They carry a few fmall guns and mufquetry. Their nets are dipped, or caft out, in the evening, and drawn up in the morning. It requires three hours to wind them on board. From the net, the fifth are immediately put into bafkets, while others of the crew are occupied till even- ing in gutting, falting, and packing. But although from ten to fifteen laft are fometimes taken at a draught, the twelve perfons ufually employed for the purpofe, cannot complete more than five laft in a day. During the three firft weeks, from the 25th of June to the 16th of July, all the freth-caught herrings are thrown into cafks without picking, and conveyed to Holland, in the jagers, or yachts+, that accompany the herring-buffes. But, after this period, immediately on being got on board and gutted, they are afforted into three qualities,—maiden her- * From the Tranfaétions of the Society of Arts, who have pub- lifhed it for the information of our fifhers in North Britain, who appear to be well acquainted with the treatment from catching and landing, but not with the fubfequent proceffes. Mr. Walter Baine, of Greenock, had the Society’s filver medal for this object laft feafon. * + Thefe are {mall faft-failing veffels, which follow the herring- buffes, fupply them with provifions, cafks, falt, and other necel- faries, and carry the fith that have been taken to the neareft port, where they are re-packed, and prepared for fending to the places of their deftination. rings, 224 DUTCH METHOD OF CURING HERRINES. Dutch method rings, full herrings, and fhot herrings, The firft of thefe are of catching and thofe taken earlieft, and without row or melt, but which, curing of her TINZS. though well flavoured, do not keep. Full herrings are thofe taken at Midfummer, on the point of fpawning; from which the brand-herrings, fo called from the barrels being marked with a hot iron, only differ.in being caught later, re-packed immediately on arrival, and fo clofe and hard preffed down, that they do not require re-packing at other places, but only new pickle; and are immediately expedited, or may remain on hand: whereas the other two forts, not being fo clofely Jaid, muft abfolutely be re-packed. Shot-herrings are thofe which have fpawned,.or are taken in the at of fpawning, in confequence of which they are thin and lean. With the laft two forts the bufles themfelves return (as foon as they have got their loading, or find no more fith), one after another, to port, where all three forts, except the brand, herrings, before being expedited, are opened, falted anew, re-packed, and fo heaped up, that fourteen cafks are re-packed in twelve, which make a laft. By a regulation of the States- General, this.re-packing muft be performed in. the open air, where ftrict watch is kept, that the fpeiling fifh be carefully feparated from the good, and the latter properly laid in the barrels, and ftrongly preffed down. The Dutch fifhery continues generally from twenty to , iwenty-fix weeks, or even. fomewhat longer, namely, from the 25th of June to the middle of January., The Datch fith only on the Scotch and Englifh coafts, off Hittland, Fairhill, and Bocken, from Naehimycen till the 25th of July ; off Bocken or Serenial, from thence till the 14th of September; and in deep water, Eaft of Yarmouth, and as far as the mouth of the Thames, from thence to the 25th of November, when the regular fifhery ceafes. But herrings are found not far from Yarmouth till the end of January, after which the fifhery is prohibited, as the {pawning feafon then commences. (To be continued.) .. ~ + s See eS — if: aes Zs "om Cc H Hib hivean = it fom | AVHIHT I Mt ANN) a i Hitt) TTA Tl NT | i re ss mA Ia) | i | i a7, i rns ee ea ie S : S 4 ae Philos. Journal. Vol. X.PU.VUEp. 224. rupee Up : Pf) TO C7 Ue,’ HUI UM» dak Bese 2 A JOURNAL OF NATURAL PHILOSOPHY, CHEMISTRY, AND TUE ARs: APHTTL, *¥sus. ARTICLE T: A short Account of the Caufe of the Difeafe in Corn; called by Farmers, the Blight, the Mildew and the Ruft. Reprinted, and the Plates copied, with Permifion, from a Memoir communi cated by the Right Hon, Sik Joseru Banks, Bart. P.R.S. &e. Sc. §c. With fome additional Notes.* Boranists have long known that the Blight in Corn 1s Botanifts have occafioned by the growth of a minute parafitic fungus or muth- Ke thane’ Lier room on the leaves, ftems, and glumes of the living plant. caufed by a mi- Felice mute parafitic fungus 3 * Immediately after the title in the original is the following pre+ fatory note : “The following brief Publication, fuggefted by the alarming *¢ ftate of the harveit in Augntt laft, would have been diftributed “¢ before the end of wheat feed-time, had the engraver fulfilled his ** engagement. © This circumftance will; it is hoped, be confidered as a fufficient *« apology for the want of a@ual obfervations on the origin and pro- * srefs of the difeafe. Thefe it is prefumed will be abundantly * fupplied in the courfe of the prefent year, by thofe intelligent ‘¢ agriculturifts, whofe refidence in the country enables them daily ’ $€ to examine, not only the progrefs of their crops, but the origih *¢ and advances alfo of all thofe obftacles which nature has oppofed to the fuccefs of agricultural labours, as if to awaken the ener- VoL. X.—APRIL, 1805, 2 6 gies 996 ON THE BLIGHT iN CORN. Felice Fontana publithed in the year 1767 an elaborate ac- count of this mifchievous weed,* with microfcopic figures, which give a-tolerable. idea of its form ; more modern bo- tanifts t+ have given figures both of corn and of grafs affeGted by it, but have not ufed high magnifying powers in their re- fearches. butagriculturits . Agriculturifls do not appear to have paid, on this head, have paid little {yfficient attention toahe difcoveries of their fellow-labourers attention to this. 5 ; f : sé: in the field of nature; for though fcarce any Englifh writer of note on the fubje& of rural economy has failed to ftate his opinion of the origin of: this evil, no one of them has yet attri- buted it to the real caufe, unlefs Mr. Kirby’s excellent papers on fome difeafes of corn, publified in the Tranfaétions of the Linnzean Society, are confidered as agricultural eflays. Engravings of On this account it has been deemed expedient to offer to this deftru€tive the confideration of farmers, engravings of this deftructive Oe aston plant,. made trom the drawings of the accurate and ingenious by Mr. Bauer Mr. Bauer, Botanical Painter to his Majefty, accompanied ae with his explanation, from whence it is prefumed an attentive ation. | reader will be able to form a correét idea of the fa€ts intended to be reprefented, and a juft opinion whether or not they are, as is prefumed to be the cafe, corre@ and fatisfa€tory. Organized truce In order, however, to render Mr. Bauer’s explanation more ture of the fur- eafy to be underftood, it is neceffary to premife, that the face of ftraw. : , ‘ , Its ,pores or ftriped appearance of the furface of a ftraw which may be mouths, fhut infeen with a common magnifying glafs, is caufed by alternate aa ae fi longitudinal partitions of the bark, the one imperforate, and the other furnithed with one or two rows of pores or mouths, fhut in dry, open in wet, weather, and well calculated to imbibe fluid whenever the ftraw is damp. ft By €< cies of reafon, and to reward the farmer for the exertions of his *¢ intelle€tual faculties, by the fatisfation of furmounting them.” *¢ Jan. 30th, 1805.” “JOS. BANKS,” * Offeryazioni fopra la Ruggine del Grano. Lucca, 1767, 8vo. + Sowerby’s Englifh Fungi, Vol. II. Tab. 140, Wheat Tab. 139. Poa aquatica. The pores or t Pores or mouths fimilar to thefe are placed by nature on the mouths onthe furface of the leaves, branches, and ftems, of all perfe& plants, a furface of plants provifion intended no doubt to compenfate, in fome meafure, the are defigned to ‘ ; 5 Z abforb er want of loco-motion in vegetables. A plant cannot when thirfty go ON THE BLIGHT IN CORN.: 997: “ By thefe pores, which exift alfo ow the leaves and glumesy it,The feeds of the is prefumed. that the feeds of the fungus gain admiffion, and ee Sea at the bottom of the hollows to which they lead, (fee Plate 1X. Fig. 1, 2,) they germinate and puth their minute roots, no doubt (though, thefe have not yet been traced) into the cellular germinate in : the cellular tex- 2 ' : j ” ture, intercept by intercepting the fap that was intended by nature for the the fap, and rens nutriment of the grain; the corn of courfe becomes fhrivelled pig ed in proportion as the fungi are more or lefs numerous on the abfraétion ve plant; and as the kernel only is abftra€ted from the grain, the kernel. while the cortical part remains undiminifhed, the proportion of flour to bran in blighted corn, is aways reduced in the fame degree as the corn is made light. Some corn of this year’s crop will not yield a ftone of flour from a fack of wheat; and it is not impoflible that in fome cafes the corn has been The flour may fo completely robbed of its flour by the fungus, that if the coray ee proprietor fhould choofe to incur the expenfe of thrathing and ceptea, grinding it, bran would be the produce, with fcarce an atom of flour for each grain. Every {pecies of corn, properly fo called, is fubje@ to the All corn is liable blight; but it is obfervable that {pring corn is lefs damaged ae ee by it than winter, and rye lefs than wheat, probably becaule it than winter, and is ripe and cut down before the fungus has had time. to ane than increafe in any large degree.—Tull {ays that ‘ white cone or «© bearded wheat, which hath its ftraw lke a ruth full of pith, «is lefs {abject to blight than Lammas wheat, which ripens a « week later.” See page74. The {pring wheat of Lincolnfhire Hitorical faéts, was not in the leait fhrivelled this year, though the ftraw was in - fome degree infe@ted: the millers allowed that it was the beft fample brought to market. Barley was in tome places con- fiderably {potted, but as the whole of the ftem of that grain is naturally enveloped in the hofe or bafis of the leaf, the fungus can in no cafe gain admittance to the ftraw ; it is how- texture beyond the bark, where they draw their nourifhment go to the brook and drink, but it can open innumerable orifices for the reception of every degree of moifture, which either falls in the fhape of rain and of dew, or is feparated from the mafs of water always held in folution by the atmo{phere; it feldom happens in the drieft feafon, that the. night does not afford fome refrefhment of this kind, to reftore the moifture that has been exhaufted by theheats of the preceding day. d Q 2 ever ! 298 ON THE BLIGHT IN CORN. ever to be obferved that barley rifes from the flail lighter this year than was expeéted from the appearance of the crop when gathered in. Little informa- Though diligent enquiry was made during the laft autumn, 1? pag aor ge no information of importance relative to the origin or the refpecting —sprogrefs of the blight could be obtained: this is not to be Wish eae ies wondered at; for as no one of the perfons applied to had any explainedsthe knowledge of the real caufe of the malady, none of them , remedy itis could direét their curiofity in a proper channel.. Now that its hoped will be i ior ered, nature and caufe have been explained, we may reafonably expeét that a few years will produce an interefting colleétion of fats and obfervations, and we may hope that fome progrefs will be made towards the very defirable attainment of either a preventive or a cure. Progrefs of the | It feems probable that the leaf is firft infe@ed in the fpring, infection. or early in the fummer, before the corn fhoots up into ftraw, and that the fungus is then of an orange colour ;* after the ftraw has become yellow, the fungus affumes a deep cho- colate brown: each individual is fo {mall that every pore on a ftraw will produce from 20 to 40 fungi, as may be feen in the plates, and every one of thefe will no doubt produce at leaft Increafe of the 100 feeds; if then one of thefe feeds tillows out into the num- fungus incalcuebher of plants that appear at the bottom ofa pore in Plate 1X. lably rapid ; i é : Fig. 1, 2. how incalculably large muft the increafe be! A few difeafed plants fcattered over a field muft very fpeedily infect a whole neighbourhood, for the feeds of fungi are not much heavier than air, as every one who has trod upon a ripe puff- ball muft have obferved by feeing the duft, among which is its feed, rife up and float on before him. and its periods How long it ts before this fungus arrives at puberty, and of generation fcatters its feeds in the wind, can only be gueffed at by the very quick, ¢ i X analogy of others; probably the period of a generation 1s fhort, poffibly not more than a week ina hot feafon : if fo, how frequently in the latter end of the fummer muft the air be loaded as it were with this animated duft, ready, whenever a * The Abbé Teffier, in his Traité des Maladies des Grains, tells us that, in France, this difeafe firft fhews itfelf in minute {pots of a dirty white colour on the Jeaves and ftems, which {pots extend them- felves by degrees, and in time change to yellow, and throw off a dry orange coloured powder. pp.201, 340. Note of Sir 7, B ; gentle ON THE BLIGHT [tN CORN, 229 #entle breeze, accompanied with humidity, thall give the fignal to intrude itfelf into the pores of thoufands of acres of corn, Providence, hewever, careful of the creatures it has created, If there were no has benevolently provided againft the too extenfive multipli- ria neck cation of any {pecies of being; was it otherwife, the minute the incteafe of plants and animals, enemies again{ft which man has the feweft one means of defence, would increafe to an inordinate extent; this larger atl however, can in no cafe happen, unlefs many predifpofing 4 fpecdily be de- caufes afford their combined affiftance. But for this wife and ATA te beneficent provifion, the plague of flugs, the plague of mice, the plagues of grubs, wire-worms, chafers, and many other creatures whofe power of multiplying is countlefs as the fands of the fea, would, long before this time, have driven mankind, and all the larger animals, from the face of the earth. Though all old perfons who have concerned themfelves in The blight does : ; : not appear to agriculture remember the blight in corn many years, yet fome ,> OPPEM OO | have fuppefed that of late years it has materially increaled ; Jate yearss this however does not feem tobe the cafe, Tull, in his Feiss hoeing Hufbandry, p. 74, tells us, that the year 1725 “ wasa * year of blight the like of which was never before heard of, and « which he hopes may never happen again ;” yet the average price of wheat in the year 1726, when the harveft of 1725 was at market, was only 36s. 4d. and the average of the five years of which it makes the fir, 37s. 7d.—1797 was alfo a year of great blight; the price of wheat in 1798 was 49s. 1d. and the average of the five years, from 1795 to 1799, 63s. 5d.* The climate of the Britifh Ifles is not the only one that is The blight in liable to the blight in corn; it happens occafionally in every part £2" Probably : . : happens in ai! of Europe, and probably in all countries where corn is grown, countries. * The {carcity of the year 1801 was in part occafioned by a mil- dew which, in many places, attacked the plants of wheat on the S.E. fide only: but it was principally owing to the very wet harveft of 1800. The deficiency of wheat, at that harveft, was found, on a very accurate calculation, fomewhat to exceed one fourth. But wheat was not the only grain that failed: all others, and potatoes alfO were materially deficient. This year the wheat is probably fomewhat more damaged than it was in 1800, and barley fomewhat lefs than an average crop. Every other article of agricultural food is abundant, and potatoes one of the largeft crops that has been known. But for thefe bleffings on the labour of man, wheat mu before this time have reached an exorbitant price.—Sir F. B. = 3 taly . : «+5 980 ON THE BLIGHT IN CORN. Italy is very fubje& to it, and the laft barveft of Sicily has heen materially hurt by it. Specimens received from the colony of New South Wales fhew that confiderable mifchief was done to the wheat crop there in the year 1803 by a para- fitic plant, very fimilar to the Englith one. Common opinion It has been long admitted by farmers, though’ fearcely cre~ that wheat in the ited by botanifts, that wheat in the neighbourhood of a bar+ neighbourhood of y : harlenerdets berry bufh feldom efcapes the blight, The village of Rollefby an ee in Norfolk, where barberries abound, and wheat feldom fuc- : ceeds, is called by the opprobrious appellation of Mildew Rollefby. Some obferving men have of late attributed this very perplexing effect to the farina of the flowers of the bar- berry, which is in truth yellow, andrefembles in fome degree the appearance of the ruff, or what is prefumed to be the blight in its early fate, The barberry It is, however, notorious to all botanical obfervers, that the leaf is very fub-Jeaves of the barberry are very fubjeét to the attack of a ject to a mildew Tepes yellow parafitic fungus, larger, but otherwife much refembling the ruft in corn, ‘ which may be Is it not more than poffible that the parafitic fangus of the transferred to ae barberry and that of wheat are one and the fame f{pecies, and that the feed transferred from the barberry to the corn is one caufe of the difeafe, Mufletoe, the parafitic plant with which | ° weare the beft acquainted, delights moft to grow onthe apple and hawthorn, but it flourifhes occafionally on trees widely differing in their nature from both of thefe: in the Home Park, at Windfor, mifletoe may be feen in abundance on the lime trees planted there inavenues, If this conje@ture is founded, another year will not pals without its being confirmed by the obiervations of inquifitive and fagacious farmers, Conjeétures di- It would be prefumptuous to offer any remedy for a malady, rected toremedysthe progrefs of which is fo little underftood; conjeétutes, however, founded on the ‘origin here affigned to it, may be hazarded without offence, Probable fa& as [t is believed * to begin early in the fpring, and firft to ap- pei pear on the leaves of wheat jin the form of ruft, or orange- coloured powder; at this feafon, the fungus will, in all pros * This, though believed, is not dogmatically afferted, becaufe Fontana, the beft writer on the fubje&t, afferts that the yellow and the dark-colomed blight are different fpecies of fungi. bability, ON THE BLIGHT IN CORN, 231 bability, require as many weeks for its progrefs from infancy to puberty as it does days during the heats of autumn; but a very few plants of wheat, thus infeGted, are quite fufficient if the fungus is permitted to ripen its feed, to {pread the malady over a field, or indeed over a whole parifh. The chocolate-coloured blight is little obferved till the corn The chocolate is approaching very nearly to ripenefs; it appears then in the oe es field in {pots, which increafe very rapidly in fize, and are in from central calm weather fomewhat circular, as if the difeafe took’ its etn of the ‘origin from a central pofition. May it not happen then, that the fungus is brought into the Whence it may field in a few ftalks of infe€ted ftraw uncorrupted among the Shite by mafs of dung laid in the ground at the time of fowing? it jnfe@ed ftraw in muft be confeffed, however, that the clover lays, on which no the manure 5 dung from the yard was ufed, were as much infeéted laft autumn as the manured crops. The immenfe multiplication of the difeafe in the laft feafon, feems however to account for this; as the air was no doubt frequently charged with feed for miles together, and depofited it indifcriminately on all forts of crops. It cannot however be an expenfive precaution to fearch and may, itis diligently in {pring for young plants of wheat infeed with sednicd spel ‘the difeafe, and carefully to extirpate them, as well as all by extirpating graffes, for feveral are fubje@ to this or 2 fimilar malady, the Ban's frlk which have the appearance of orange-coloured or of black ftripes on their leaves, or or their ftraw and if experience fhall prove that uncorrupted firaw can carry the difeafe with it into the field, it will coft the farmer but little precaution to prevent any mixture of frefh ftraw from being carned out ‘with his rotten dung to the wheat field. In a year like the prefent, that offers fo fair an opportunity, Whether blights it wili be ufeful to obferve attentively whether cattle in the ftraw preemie yard thrive better or worfe on blighted than on healthy ftraw. than dean ftrawy That blighted ftraw, retaining on it the fungi that have robbed for cattle ? ‘the corn of its flour, has in it more nutritious matter than clean ftraw which has yielded a crop of plump grain, cannot ‘be doubted; the queftion is, whether this nutriment in the form of fungi dees, or can be made to agree as well with the *tomachs of the animals that confume it, as it would sido ‘ firaw and corn. it ‘ it 939 : ON THE BLIGHT IN CORN, Though the Tt cannot be improper in this place to remark, that although feeds of blighted: he. feads uo ambiaabuatad peiadendslyiols the exhaufting power of corn afford little rey gP flour, they are the fungus, fo lean and fhrivelled that fcarce any flour fit tual i for the manufaéture of bread can be obtained by grinding plumpett famples; them, thefe very feeds will, except, perhaps, in the very worft cafes *, an{wer the purpofe of feed corn as well as the faireft and plumpeft fample that can be obtained, and, in fome and aremuch refpeéis better; for as a buthel of much blighted corn will ied eet ie contain one-third at leaft more grains in number than a bufhel eichivcs: of plump corn, three bufhels of fuch corn will go as far in , fowing land, as four bufhels of large grain. The flourin the The ufe of the flour of corn in furthering the procefs of vege- fhrivelled grain tation, is to nourif the minute plant from the time of ifs isamply fufficient mar se : to nourifh the developement till its roots are able to attra@ food from the «uae plants till manured earth; for this purpofe one-tenth of the contents of ey take root. : : ; 2 a grain of good wheat is more than fufficient. The quantity of flour in wheat has been increafed by culture and management calculated to improve its qualities for the benefit of mankind, in the fame proportion as the pulp of apples and pears has been increafed by the fame means, above what is found on the wildings and crabs in the hedges. Tt is a wafteful It is cuftomary to fet afide or to purchafe for feed corn, the Shonen boldeft and plumpeft famples that can be obtained; that is, grain for feed, thofe that contain the moft flour; but this is unneceflary wafte Se for Of human fubfiftence ; the fmalleft grains, fuch as are fitted the mi!] are out before the wheat is carried to market, and either cone esi gine for fymed in the farmer’s family, or given to his poultry, will he found by experience to anfwer the purpofe of propagating the fort from whence they fprung, as effeétually as the largett.. Arrangement of | Every ear of wheat is compoted of a number of cups placed pee soa *” alternately on cach fide of the firaw; the lower ones contain, The lower ones according to circumftances, three or four grains, nearly equal + eo in fize, but towards the top of the ear, where the quantity of upper are not nutriment is diminifhed by the more ample fupply of thofe inferior as feed. cups that are nearer the root, the third or fourth grain ina cup is frequently defrauded of its proportion, and becomes ® 80 grains of the moft blighted wheat of the laf year, thit could be obtained, were fown in pots in the hot- houfe; of thety feventy- two produced healthy plants, a lofs. of 10 per cent. only fhriveled ON THE BLIGHT IN CORN. fhrivelled and fmall. Thefe {mall grains, which are rejected by the miller, becaufe they do not contain flour enough for his purpofe, have neverthelefs 2n ample abundance for all purpofes of vegetation, and as fully partake of the fap, (or ‘blood, as we fhould call it in animals,) of the kind which pro- duced them, as the faireft and fulleft grain that can be ob- tained from the bottoms of the lower eups by the, waftefal preeets of beating the fheaves, =e TOE LS EXPLANATION OF THE PLATES, Plaie 1X. Fig. 1. A piece of the infe€ted wheat ftraw—natural fize: at a the leaf fheath is broken and removed, to fhew the fraw which is not infeéted under it. Fig, 2. A highly magnified reprefentation of the parafitic plant which infeéts the wheat: ain a young ftate ; bfall grown; ¢ are two plants burfting and fhedding their feeds when under water in the microfcope ; dtwo plants burft in a dry ftate; e feems to be abortive; f feeds in a dry flate; ga {mall part of the bottom of a pore with fome of the parafitic fungi grows ing upon it, Fig. 3. Apart of the ftraw of fig. 1, magnified. Fig, 4. Part of fig. 3 at a b more magnified. fig. 5. Part of a ftraw fimilar to fig. 3, but in its green ftate, and before the parafitic plant is quite ripe. Fig. 6. A fmall part of the fame, more magnified. Plate X. | Fig. 1. A highly magnified tranfverfe cutting of the ftraw, correfponding with Fig. 4. Plaie I. fhewing the infertion of the parafite in the bark of the ftraw. fig. 2. A longitudinal cutting of the fame; magnified to _the fame degree. Fig. 3. A {mall piece of the epidermis of a ftraw, thewing the lage pores which receive the feed of the parafite; the {maller {pots obferyable on the epidermis, are the bafes of hairs 233 234 ; OW .TRIANGLES. hairs that grow on the plant of the wheat whilft young, but which fall off when it ripens, magnified to the fame degree as the preceding figures. ————— ik. Theorems refpecting the Properties of the Sides of Triangles in- terfeed by Right Lines drawn from the three Angles fo as to meet 7 one Point. By Mr, Joun Goucnu. To Mr. NICHOLSON. SIR, Middlefhuw, March 1, 1805. Certain proper- (GEOMETRICIANS have paid but little attention to the ties of triangles. properties of the fides of triangles, which are interfected by right lines, drawn fronr the three oppofite angles fo as to meet in one point. Perhaps all the theorems of this kind that have been hitherto publifhed, are contained in the feeond book of Emerfon’s Geometry, with the fingle exception of a propofi- tion given by Mr. Landen; who has proved that if one of the internal angles of atriangle, and the two oppofite external an- gles of the fame be bifeéted, the right lines, drawn for this purpofe, will alfo meet ina common point. The following propofitions take a more general view of the fubjeét; and as fome mathematical papers have appeared of late in the Philo. fophical Journal, I have ventured to afk a place for the prefent feet, in your valuable mifcellany. T remain, &c. JOHN GOUGH. P.S. In vol. X. page 66, line 2, for 53 yards read 3} yards, al a aol Propofition 1ft. Let three right lines CM, BN and AG, - (Plate X1. Fig. 1, 2.) drawn from the three angles of a trian- le ABC, interfe@ the oppofite fides, produced or not, in the points M, N and §, and alfo meet each other in a com- mon point O; then if all the points M, N and S$ lay betwixt a 1 the ON TRIANGLES, 935 the angular points B, A and C, the place of O will be within Certain proper- the triangle, and the three lines CO, BO and AO will fall ®° of trianglese wholly within the fame; but if one of thefe points, as S, lay in BE, which is C B produced, the place of O will be ex- ternal to the triangle; in which cafe, one of the two remain- ing points of interfection will lay in its refpe@ive fide pro- duced; but the fituation of the other will always be betwixt the angular points of the third. fide. Demonfiration. Cafe if. Let M, N andS (Fig. 1.) be betwixt the angu- lar points B, A and C; in which cafe, the triangles ABC, M BC are of the fame-altitude; confequently they are as their bafes AB, BM, Luc. 1.6; but BM isa part of AB by hypothefis; therefore the triangle MBC isa part of ABC, (Simpfon’s Euclid, D. 5.) that is, the triangle A BC contains the triangle M BC; for the fame reafon, the fame A BC con- tains the triangle S A B; but the figure M BS O is common to the triangles MBC, SAB; therefore it is contained in the triangle ABC; confequently the place of O is within the fame: now as the points A, B, C and O are all found in the fpace ABC, thelines AO, BO and C O muft alfo lay wholly within the fame triangle. Cafe 9. When the point S falls in BE or C B produced, (Fig. 2.) the angle CBA is external to the triangle ABS; therefore it is greater than’the angle BS A, (Euc, 17, 1;} and the fum of the angles CAB, ACB is lefs than the angles CAS, ACS taken together, (Zuc. 32.1); hence the angle C AB is lefs than CAS; confequently the right line AS, produced at pleafure, falls wholly without the triangle A BC, ~Now if the remaining two lines C M and B N be fuppofed to ' eut the fides B A and AC not produced, the place of O, their common interfeGiion, will be in the fpace A BC, by Café 1: but this isimpoffible; for O is in the right line AS by hypo- thefis; which has been fhewn to fall wholly without the trian- _ gle ABC, confequently one at leaft of the lines CM, BN muft alfo lay without the fame fpace; let this be BN, and draw O K parallel to C A; then the external angle OK E of the triangle OK C is greater than the internal and eubeis angle 236 ON TRIANGLES. Certain proper- angle BC M, 17.1; but the angles OK E, AC B are equal ties of triangles. -7r4¢,99,] ;) therefore the triangle M B C isa part of the trian- gle ABC, and is contained in it; but thefe triangles are as their bafes M B, B A (£uc. 1.6 ;) confequently M B is apart of BA, Simf, Euc. D. 5; and the point M is between the points A and B..,.Q)Exb, Corollary. Hence it appears that if two lines C M and BN be drawn, and their interfe€tion O lay within the triangle ABC, the place of the third point S will be in the fide BC unproduced. But if O lay without the triangle, the place of the third point will depend on the fituation of the given points; namely if thefe be in two fides produced, the place fought will lay in the remaining fide unproduced; but if either of the given points fall between two angles of the triangle, the third will be found in the remaining fide produced. Propofition2. If aright line C M (Fig. 1.) be drawn from C, one of the angles of a triangle A BC, to cut the oppofite jide A B, produced or not, in M, and if from the point M, perpendiculars, M F, M H be let fall upon the fides A C, CB, the reGlangle B M, M F will be to the reGangle AM, MH, as BCistoC A, Demonftration, Draw AP, BQ perpendicular to BC, C A; then we have the following proportions, by femilar triangles ; as MB:M.H::AB:AP; andasMF:MA::BQ:BAs henceasMBxMF:AMxMH::BQ:AP. ButasBQ:; AP::BC:CA, Euc. 14.6; therefore the rectangle M B, MF is to the retangle MA, MH as BC is toC A. Euc, ie. QB.) D, Cor. 12. If Oh, OF be drawn perpendiculartoBC, C A, from any point O in MC; the rectangle MB, Of willbe to MA, Oh as BC isto C A; for by fimilar triangles as fO Oh::FM:MH; henc2 aaMBxOf:MAxOh::MB *xMF:MAxMH; confequently as MBxOf:MAx Ohler BC : CiAy ‘Buc. 11.5. Cor. 2nd. Let the triangle A BC be ifofceles, having the fides BA, AC equal; aifo let CM, BN, drawn to the op- pofite fides BA, AC meetin O; then the point S$ is given, in which A O, prodaced if neceffary, cuts the remaining fide CB. For draw Of, O ¢ perpendicular to C A, A B, and we shall have, as BSxOf: CSxOg:: BA; AC, Cor. 1; but BA, ON TRIANGLES. 937 B A, AC are equal by hypothefis; therefore BS x Of = C S Certain proper- xOg; hence as Og: Of ::BS:SC; confequently ge HE? OF Sangleay point S may be found, proper attention being paid to Cor. Prop. 1. Propofition 3. If three right lines CM, BN, AS, drawn from the three angles of a triangle ABC (Fig. 1 and 2) meet each other in a point O, and the oppofite fides B A, AC and C B, in M, N and S; the fegments of any one fide are as the rectangle under the alternate fegments of the remaining two fides; z.e. BS is to SC as the reCtangle BM, AN to the reGtangle CN, AM, Demonftration. Draw Of, Og, Oh perpendicular toC A, ABandBC. ThenasBC:CA::BMxOf:AMxOh; Cor. 1. Prop.2; for the fame reafonas AB: BC:: NAx Oh: NCxOg; hence as BA: AC:: MBxNAxOfP: NCxMAxOg; butasBA:AC:: BSxOf:CSxOg; confequently BS is to SC as the reétangle B M, A N is to the reCtangle CN, AM. Q.E.D. Cor. If two right lines C M, BN be drawn from two an- gles of any plain triangle A BC, fo as to meet each other in a point O, and the oppofite fides BA, AC in Mand N; a point S may be found in the remaining fide, produced if ne- ceflary, fothat if SA be joined, the right lineAS fhall pals through O. For fince the right lines BM, MA, AN and N C are given, the re@angles BM, AN and CN, AM are alfo given ; confequently the ratio of thefe re€tangles is given : but the right line A O cuts the fide C B, produced or not, ac- cording to circumftances, in the fame ratio, by the laft pro- pofition ; therefore if both M and N lay betwixt the angular points of the triangle, or in their refpeétive fides produced, divide BC in S, fo that BS may be to S C in the ratio of the _ seGtangles BM, AN and CN, AM; then will S be the re- quired point by Cor. to Prop. 1; but if M be fituated betwixt the-angles B, A, and N lay in CA produced; find SinC B alfo produced, fo that B S may be to S C as the reGtangle B M, AN is to the rectangle C N, AM; and S will be the re- quired point, by the corollary laft referred to. Prop. 4. Let three right ines CM, BN and AS (fig. 1 and 2) drawn *)m the’ three angles of a triangle ABC, in- terfe@t each other in a common point O, and meet the oppo- fite 233: Certain proper- ties of triangles. ON TRIANGLES, fite fides BA, AC and CB, in the points M, N and §; if AN be to NC as A®B is to BPC; but BM be to MA as BC is to CtA; then will BS be to SC as the produce of BPA into BIC is to the produét of BPC into ATM. Demonjtration.. As AN:NC:: BPA: BRC; andas BM >MA::B'C: CIA by hypothefis; hence as BMxAN: CNxAM:: BPAx BC: BPCxCTA; but as BMxAN® NCxAM::B8:S8C; confequently BS is to $C as the produ of BPA into BTC is to the produét of BPC into C*A. Bue. PFS! QELS D. Corollary iff. The preceding theorem is general; for the yatios of BM to M A, and of AN'to NC can be expreffed by fome power or powers of the lines BC, C A and A B, BC, which contain the angles oppofite to the fides B A and AC; therefore if the points M, N and S be arranged accord- ing to the corollary to Propofition 1ft, and the fegments be- twixt thefe points and the adjacent angles have the ratios af- figned in the prefent theorem, right lines, drawn from M, N and S$ to the oppofite angles, will all meet in one point. Cor. 2. When rand pare equal, BS is toS C as BPA is to A°C by the propofition; therefore if the fegments betwixt the points M, N, S and the adjacent angles are in the ratios of the adjacent fides raifed to any given power, right lines, drawn from M, N and S to the oppofite angles, will all meet in one point by Cor. 1/t. Cort 3rd.) Let 'p =o 5 then as. iB Son GOW ACS by the propofition; but BPA : A°C is the ratio of equality ; therefore if M, N and S bifeé the three fides of a triangle, lines drawn from them to the oppofite angles will meet in one point by Cor. 2nd. Cor. 4. Letp=1; alfo let M and N interfe@ the fides BA, AC not produced; then S lays between the angular points B,C, Cor. Prop. 1; and as BS:SC:: BA: AC, Cor. 2; therefore the right line SA bifeéis the angle BAC; confequently if three right lines bifeét the three internal an- gles of a triangle, they fhall all meet in one point by the laft propofition. — Cor. 5. Let p= 1 as before; alfo fuppofe M to be in the fide BA not produced; but let N be withcut the triangle; then S$ is in C B produced, Cor. Prop. 1; butas BS? $Cx 3 BA ON TRIANGLES, &c. 239 BA :AC, Cor, 2; therefore $A bife&s the angle BAN, (Simpjon’s Euclid: .6 A); alfoas BM:MA::BC:CA; therefore C M bifeéts the angle A CB, Euc. 3.6 ; con {equently if two lines bife@ ; any two uf the external angles of triangles, and a third line bife@ the internal angle oppo to thefe an- gles, thefe lines fhall meet in one point by the laft propofitions Prop. 5. If BM beto M A as BPC toC?A ; and kO, Of be. perpendicular to & C and CA; kO is to Ofas B?~'C to ©? >A, Demonfiration, As BMxOf:AMxOh?::BC:CA, Cor. 1. Prop, 2; and as BPC: APC :: BM: MA by hypo- thefis; therefore as BC x Of : APC x Oh:: BC: CA; con fequently asOh:Of::B?—*C:CP +A. Q.E.D. Ill. \ A Communication on the Use of Green Vitriol, or Sulphate of Iron, asa Manure; and on the Lifficacy of paring and burn- ang depending » partly, on Oxide of Iron. By Georce Pearson, M: D. Honorary Member of the Board of Agri- culture, F.R.S. From a Communication made by him to the Board, and inferted in the fourth Volume of their Tranjactions, (Concluded from page 214.) APPENDIX. ern following fa@s, lately difcovered by moft refpe@able chemifts, appear to be worth adding to the preceding memoir, as they ferve to fhew that other falts, befides fulphate of iron and ‘certain earths, may be employed advantageoufly as manures, although like iron they have been efteemed deleterious ,to plants. 1. Afhes of Pit Coal area good Manure for Grafs. My much valued friend, the Rev. William Gregor, peep afhes iP ene : : ‘ ; are a goo Grampound, on examination of the afhes of coal from Liver- ine fin geal _ pool, found them to contain both fulphate of magnefia and Mulphate of lime,. efpecially the former, falt. I apprehend that thefe athes allo contain oxide of iron, or perhaps fulphate of 240 USE OF GREEN VITRIOL of iron. . Thefe afhes, fays Mr. Gregor, ‘* jreaded” * over grafs apparently produced good effeéts notwithflanding the Sulphate of magnefia, which I was well affured they contained. See Nicholfon’s Journal, Vol. V. p. 225. Sulphate of From this obfervation of Mr. Gregor, it feems he is aware anger alae of the prevailing popular opinion, that fulphate of magnefia to plants, tho” is not favourable to vegetation; and to reconcile his fat with ag magnefia the unfriendly nature of magnefia to plants, as difeovered by Mr. Tennant, he obferves that the effe@ls of fulphate of magnefia may be very different from thofe of magnefia and carbonate of magnefia. I apprehend it is the magnefia (cal- cined magnefia) only which this learned chemift found hurtful to vegetables, as the difcovery was made on the examination ef Nottingly lime, which the farmers near Doncafter employ asa manure, while they rejeét the lime of their own neighbour- hood. In the latter Mr. Tennant met with magnefia, and in the former none. See the account of this important difcovery in the Philof. Tranfactions. 2. The Earth from Ajhes called Cinis, ts a durable and efficacious Manure; by Profeffor Mitchill, of New York, one of the Reprejentatives in Congrefi. Addrefed to Dr. Pearfon. Earthfromafhes Dr. Mitchill, in a letter addreffed to me on cinis, or earth isa good manures end in the afhes of wood, has made fome obfervations rela-~ tive to the preceding memoir, which feem worthy of notice. « Afhes of wood contain very commonly fulphate of potath, alfo phofphoric acid, befides other well known falts ; but after thefe falts are feparated by lixiviation, there remains a peculiar earth, and a {mall proportion of iron, This earth differs from lime, baryt, magnefia, flrontian, or any other known {pecies of earth, I would call it cins, for plentiful, common, and important as it is, fcience has not dignified it with a name, To judge of the excellence of this earth as a manure, after all the falis are extraéted from foap boilers’ afhes, the earth fells for ten cents the bufhel, and notwithftanding this high price, it is not unufual for the farmer to pay for the article twelve months beforehand. When ploughed into fterile ground, at twelve loads per acre, it produces great crops of ; wheat, clover, and other forts of grafs and grain, and its fertilizing operation will laft twenty years. Although fome: # From Excdeaw of AS A MANURE, 24} Of the otlier ingredients of the athes left after lixiviation may prove beneficial, yet the effects are chiefly from the cinis, or new named earth. “* This earth, which is fo prized in America as a manure, was efteemed of old in Afia, as an ingredient in a cement: among the ancient Syrians, it was one of the materials form- ing the plafter of their walls; and as it holds an intermediate place between lime and potafh, it can eafily be conceived how it may aét both as a cement and a manure. It is to be hoped, chemifts will turn their attention to this important fubjeét.”” See Tilloch’s Philof, Magazine, Vol. VII. p. 273, for the whole of this interefting letter. 3. Several Metallic Salts promote Vegetation, shewn hy the Exe periments of Profejor Barton, of Philadelphia. Letter from Benjamin Smith Barton, M. D. Profeffor of Medicine in the College of Philadelphia, to Dr. Pearfon, containing Experiments with Metallic Solutions to determine their Effedas - on Plants. Sik, Philadelphia, O&. 28, 1802. IN the Annals of Medicine for the year 1801, you inform Direé&t expeéri- us; that you have lately read a paper at the Board of Agricul- re ture, ‘* containing an account of the effets of a faline body faits on vegeta- célleéted from peat, as a moft powerful manure, which turhs "™ out to be fulphate of iron; a fubftance (you remark) hitherto confidered to bea poifon to plants.” This piece of intelligence gave me much fatisfaction. I have, for fome years, been engaged in an extenfive feries of experiments, relative to the effets of various ftimulating articles, fuch as camphire, &c. upon vegetables; and on the abforption of certain powerful ‘mineral {ubftances into the organic fy{tem of vegetables. In numerous inftances I have fubjected the ftems and leaves of plants, young and old, large and fmall, to the influence of the fulphates of iron and copper. I have found, that both of ‘thefe metallic falts are very greedily abforbed by vegetables, infomuch that I have dete@ed the prefence of iron in the veflels of a branch of mulberry, at the height of five or fix feet above the place of immerfion in a folution of the fulphate of this metal. A full account of my experiments, I defign Vor. X.—Aprit, 1805, oak ae te 242 Sulphate of iron exifts in Ruffian peate USE OF GREEN VITRIOL to communicate to the public in two memoirs. Permit me to obferve, in the meanwhile, that the fulphate of iron, applied to vegetables in the manner I have mentioned, ‘‘ is only (to ufe your own words) a poifon, like almoft every thing elfe, from the over-dofe.” Jn several of my experiments, the branches of vegetables that were placed in veffels containing folutions of Sulphate of tron and copper, lived longer and exhibited more Signs of vigour, than fimilar branches that were placed zn equat quantities of fimple water, It is true, that, in many other ex- periments, thefe metallic falts proved fatal to my plants; but this was when I employed too large a dofe. In like manner I had found feveral years ago*, that camphire, by greatly ftimulating, often kills vegetables; and yet, when properly dofed, this is a very wholefome ftimulant to plants. I had alfo found, that large dofes of nitre (which is unqueftionably a powerful ftimulant both with refpeét to animals and vege- tables) produce an appearance like genuine gangrene in the leaves of vegetables: and yet it is certain that nitre, when it is judicioufly dofed, may be made to greatly affift the healthy vegetation of plants. Excufe the liberty I have taken in troubling you with thefe few loofe hints, and permit me to fubfcribe myfelf, - Sir, your very humble and obedient Servant, &c. Benyamin Smitu Barron, 4, Sulphate of Iron in the Peat of Rufia, found by Profeffor Robifon. Something elfe befides vegetable matter is neceflary to form peat or black mofs of the moors. The {mell of burning peat is different from that of vegetable matter. Peat afhes, fays the Profeffor, always contain a very great proportion of iron; he has feen three places in Ruflia where there is fuperficial peat mofs, and in all of them the vitriol is fo abundant as to - eflorefce. In particular, on a moor near St. Peterfburgh, the clods fhew the vitriol ({ulphate of iron) every morning when the dew has evaporated. According to this learned Profeffor’s obfervation, the fulphate of iron in pit coal may be accounted for in the following manner: ‘ peat moffes form very regular * See Tranfaétions of the American Philofophical Society, Vol, IV. No. xxvii. ; Z ftrata, AS A MANURE, 943 firata, lying indeed on the furface; but if any operation of nature fhould cover this with a deep load of other matter, it would be compreffed and rendered very folid: and remaining ~ for ages in that fituation, might ripen into a fubftance very like pit coal. See the Medical and Chirurgical Review for November 1803, o. Mr. Anfiey’s Teftimony of the Ufe of Peat Dujt and Peat Afhes. Sir, . Houghton Regis, Dec. 3, 1801. I received yours, dated the 18th of November laft, in Tettimony of which you requefted me to inform you what experiment I hadM* Anfteye ‘made from the turf duft, taken from Tingrith Moor. I have made ule of the afhes and duft near thirty years, and I fre- quently lay on from eighty to a hundred bufhels per acres Our land is dry and very thin ftapled, owing to the chalk rock laying fo very near the furface; it encourages vegetation in moift warm weather; but when hot and dry, the reverfe. We never mix any other manure with it. It cofts about four-pence per bufhel, including all expences. We chiefly {pread it on our feed grafs, clover, &c. Iam, Sir, your humble Servant, JOS. ANSTEY. IV. On Speétacles, Ina Letter from Mr, Ezexiit WALKER» To. Mr. NICHOLSON. Dear Sik, Lynn, February 16, 1805. In a former paper, I pointed out a property in fpectacles, Pofition refpecte which had been overlooked by the writers on optics; but as'"8 Peecles, fome of your readers entertain opinions contrary to mine, the fabjeét feems to require further invefligation, What I have advanced concerning {peétacles is, that we viz. that we fee fee better by oblique, than by direét pencils of rays * ice raySe Phil ofophical Journal, Vol, VII. p. 291. R2_ It 244 Confiderations relating to oblique pencils. ON SPECTACLES, Ithas been demonftrated by mathematicians, that an oblique pencil of rays has its focus a little nearer the lens, than a dire pencil; but how much this difference amounts to, at- different angles, feems not to have attraéted their attention. This difference, however, is too confiderable to be difregard- ed, when the rays of light fall very obliquely. For let L L (fig. 3. Pl. xi.) reprefent a double convex Jens, F its focus, A F its axis, and aba ray parallel to it, which will be refraéted to F, after paffing through the lens. Alfo let c b and d d be two oblique rays falling upon the lens, at band d. Then the rays near A F falling almoft perpendicularly upon the fides of the lens, are lefs bent than the rayse b, dd, which fall obliquely on both fides of the lens, ‘* For the more oblique they are, the more they are bent, and turned out of their direét way. And confequently the oblique rays c b, dd, will fooner interfe€t in G, than thofe at F.” (Emerfon’s Optics, page 124.) When the angle a6 c is very confider- able, the difference between x F, and y G, will likewife be very confiderable. And the following fhort account of my experiments will throw fome light upon the truth of this pro- Spectacles obliquely placed. pofition. In the {peétacles that I ufe, the reading diftance of oblique rays is four inches nearer the glaffes, than the diftance at which I can fee beft, with the direct rays. And by experiments made with a lens of 24 inches focal diftance, and 4 inches in diameter, contraéted to 2 of an inch, I found the focal diftance of an oblique pencil of rays 8 inches fhorter than the focal diftance of the direét rays. The axis of the lens, when placed for the oblique rays, made an angle of 26° with a line drawn from its centre, to the candle with which the experiments were made. And the diftance be- tween the candle and the lens meafured about 10 feet, when the lens was placed to receive the direct rays. Cor. 1. When an objeé& is feen through fpeétacles, by oblique rays, it appears larger than by direét rays. For the objeét is feen under the greateft angle, by thofe rays that are moft refraéted. Cor, 2, When an objeét is viewed by oblique rays through fpeétacles, it is feen more diftinétly with one eye, than with the other. For REMARKS ON DR. THOMSON’S CHEMISTRY, 24,5 For the rays fall more ioe upon one of the glaffes, {han upon the other. Cor. 3. The dire& pencils of rays are but feldom ufed, by a perfon whofe f{pe€tacles are of the longeft focal diftance, that will afford him diftin@ vifion. For he generally looks through thofe parts of Kis glaffes, which are remote from their centres, in confequence of that motion which is given to the eyes, to view obje@s in! dif. ferent dire€tions. Iam, Dear Sir, Your moft obedient Servant, EZEKIEL WALKER. = ¥, Remarks on certain Paguges in Dr. Thomfon’s Chemifiry, te~ gether with fome Experiments on Sandarach and Majic. In @ Letter from Mr. R. Matruews. To Mr. NICHOLSON. SIR, , In a work of fuch importance as Dr. Thomfon’s Chemiftry, which muft be fo frequently referred to by the lovers of that {cience, the flighteft inaccuracy ought not to pafs unnoticed : the following obfervations Mie 3 perhaps may be con- InDr,Thomfon’s fidered fufficiently interefting to deferve a place in your Shemitry, valuable Journal. In his 4th Vol. page 307, Dr, Thomfon has the. following i it is ftated, that remark: ‘ Hitherto it has been affirmed by all chemifts both con ie a * ancient and modern, that the alkalies do not exert any a€tion thar alcalies do on the refins.” This remark I admit may be generally true ; ic ba but although moft chemifts have been negligent in afcertaining the effeéts of alcalies upon fubfiances of this nature, I con- ceive fome of them were not unacquainted with the power they poffefs of diffolving refinous bodies. Boerhaave, for inftance, in his elements of chemiftry, page The contrary is 545, exprefsly fays, that, ‘* both the fixed ana volatile alcalies “ska by Boers have a diffolving power, upon animal, vegetable, and mineral ; fubftances, fo far as thefe contain oils, balfams, gums, rojins. er gummy rofins, &c,” 3 Hoffmana 946 REMARKS ON DR, THOMSON’S CHEMISTRY, andbyHoffmanne Hoffmann alfo, by the method he employed in diffolving amber with cauftic nitre, evinced that he was acquainted with this property in alcalies.. Dr. Thomfon defcribes Mr. Hatchett as the firft difcoverer of the a€tion of alcalies upon refin, The facts above quoted will leffen the originality, without diminith- ing the value of Mr. Hatchett’s ingenious experiments. _. How therefore it can be true that, * all chemifts both ancient and modern, have affirmed, that the alcalies do. not _ exert any action on the. relins” J] cannot eafily difeern, une lefs indeed we impute to them the moft palpable contradice tions, an error which I believe is not often found in their writings. Dr. Thomfon Page 340 in the fame volume, Dr. Thomfon afferts, that afferts, that one (andarach is not foluble in alcohol, about a fifth part of it re- fifthoffandarach |, : “gh : is infoluble in maining undiflolved; and defcribes the infoluble part as pof- alcohol. feffing peculiar properties, differing from fandarach, and calls. it fandaracha. It ought not to be concluded, that Dr, Thomfon himfelf can have chemically examined every fubflance he muft have occafion to defcribe in a work which embraces fo great a variety ; but the importance of fandarach as an ingredient in varnifhes being nearly equal to that of any other refin, this fubftance certainly deferves more altention from chemifts than has hitherto been beftowed on it. The properties of this refin as mentioned by Dr. Thomfon, are fiated to reft folely on the authority of Giefe, no other chemift having examined - tty Experiment. It Upon trial I found that fandarach was foluble in eight times proved foluble in its weight of alcohol, a very minute proportion only being left, ae ans s which appeared to confift almoft entirely of extraneous matter, alcohol. | Confequently the fubftance Dr. Thomfon has denominated fandaracha can have no exiftence in this refin, It is proper to obferve, that the refin I made ufe of was felefted fine, and is known in commerce by the names of gum juniper and fandarach. From the obvious difagreement in the refults, perhaps we onght to conclude, that the fubftance employed by Giefe in his experiments was not true gum fandarach *. * Looking to fome chemical notes, I find that when three or four tears of fandarach were put into pure alcohol, and left for a day, a fimall quantity of thick fluid remained at the bottom, which, however, was taken up by agitation, and the whole became femi- opake :—It is remarkable, that this fubftance is not folublein tallow or oil, as common refin is. N. 4 Speaking REMARKS ©N DR. THOMSON’S CHEMISTRY. OAT Speaking of maftich, vol. 3, p. 311. Dr. Thomfon Dr. Thomfon’s fays, it is readily foluble in alcohol. In the fame valuable aa volume, page 332, he informs us, that ‘ that part of maftich - which is infoluble in alcohol is faid to be pure caoutchouc.” In inveftigating this apparent contradi@ion, I examined the The Author's _ aétion of alcohol upon maftich, and found that nearly a fifth xPeriments. part of it remained undiffolved. This refiduum, after re- Alcohol leaves peated wafhings in alcohol, was white, confiderably elaftic, mareanigial® and adhefive; it was inflammable; and when heated became {olved, brown, emitting inflammable gas. In this ftate it had much refembling the appearance of common Indian rubber, but fomewhat 4 rubbere glutinous: It was not in the leaft aGted on by water. I was induced to try the effects of different menftrua on Comparative ex- this refiduum, and on the elaftic gum caoutchouc, with a Perimentson the : x ee: : : . refidue of mase view to afcertain their identity or otherwife. The following tich, and on are the refults I obtained : caoutchouce Sulphuric ether, previoufly wafhed with diftilled water, diffolved this refiduum as well as caoutchouc. Alcohol precipitated both thefe fubftances from their folvent in the form of a white curd. Water had no aétion on the folutions. By the nitric acid the refiduum was converted intoa yellow brittle porous: mafs, nitrous gas being difengaged from the * acid. Nitric acid did not aé€ fo eafily on caoutchouc; but when raifed to the boiling point it changed it into a fimilar fub- ftance. | With the fulphuric acid a fubftance like charcoal was form- ed, the acid affuming a dark port wine colour, part of it being converted into fulphureous acid. . ~ The fame effect was produced by the fulphuric acid on caoutchouc, though not without the affiftance of heat. . Neither the muriatic gr oxymuriatic acids appeared to have any action on either of thefe fubftances. ~ Acetic acid diffolved a fmall portion of the refidusm, but had no aétion on caoutchouc, * Solutions of potafh and ammonia produced no effeét an either the refiduum or caoutchouc. From the above experiments it will be obferved, that the Thefe appear to acids a€ with greater facility on the infoluble part of maftich, be the fame, than on caoutchouc. Notwithflanding this difference in their action, 248 rs Dutch method of catching and guring herrings. DUTCH METHOD OF CURING HERRINGS. action, I think it may be inferred, from the coincidence .in their effeéts, that thefe bodies are fimilar fubftances. Probably the aétion of the acids on the refiduum was affifted by a {mall portion of refin which it was combined with, and which jit defended from the action of the alcohol employed to diffolve the maftich. . Iam, your obedient Servant, ' R. MATTHEWS, March 13, 1805. VI. The Dutch Method of curing Herrings, extracted and tranflated from the German of Kriinitz’s Economiéeal Encyclopadia (Oeconomifche Encyclopadie), Article Haring, by J, Hinckrey, Efy. F. 8. A, (Concluded from p. 224+) Herrines, however, are equally good, wherever they are taken, provided they be but caught in the proper feafon, and well managed. As they die immediately on quitting their element; falting and packing are the circumftances which principally affe their quality. The fuperior excellence and, flavour of Dutch herrings, above thofe of all other countries, arifes from the clofe attention and indefatigable induftry em- ployed. Every thing, however minute, both as to feafon and management, which can maintain the reputation they have enjoyed for more than two hundred years, is moft, punétually obferved; and above thirty ordinances on the curing and ma- nagement of herrings are recited by Sir wie Temple, in the 17th century. Herrings, cured with Scotch falt, very quickly deeay. Thofe of Norway are cured in the fame manner as the Scotch, but with French falt, and packed in fir or deal; in confe- quence of which they are worfe, and lefs palatable, as they leave a four (afte in the mouth, and foon fpoil. In like man- ner, other nations are equally carelefs in afforting the fith, and to this may be attribyted the precedency which the Dutch herrings have fo long maintained. The Dutch catch their fifh regularly and early off Hittland, from the 25th of June, becaule DUTCH METHOD OF CURING HERRINGS. 949 becaufe they are then, and to the beginning of July, fatteft; Dutch method after which time, the nearer they approach the coaft, the ion gisr med Jeaner and worfe they are. ‘ It redounds no lefs to the honour of the Dutch, than to their advantage, that they pay the utmoft poffible attention to thefe rules: according to which, the fifh mutt be taken at the proper feafon, properly falted, well afforted, and rightly packed ; to do all which, the captain and failors are by feveral laws obliged to bind themfelves by oath, before they fail. There are alfo overfeers well paid, that they may not betray their truft, but watch and enforce every the minuteft regula- ‘ tion; to which circumftance alfo, the pre-eminence of Dutch herrings throughout the world may partly be afcribed. As foon as the herrings are taken out of the water, they are thrown either upon the end of the deck, which has been cleared, and made perfeétly clean for the purpofe, or into bafkets ; and then gipped (the gills and guts taken ont) with a knife, by fome of the crew, who are folely employed there- in, having been brought up to that praGtice. The milt, o roe, however, is always left in the fifhe* What are taken during one night, are, before the following fun-f{et, neatly and fkilfully laid in oaken barrels, coarfe Spanifh or Portu- guefe bay falt being ftrewed between. This the fithermen of other countries either entirely negle&, .or lefs carefully per- form, being lefs fcrupuloufly nice; becaufe they either go out to fea later, or, like the Scotch, commence fifhing too foon ; or only navigate fall boats near the coaft; do not kill the fifh with a knife, or gut, falt, or pack them, while on board, but throw them down in a boat, and when fully laden, go on fhore, proceed at their Jeifure, caft the fifh on the fea-coaft in confiderable heaps, where they are even fuffered to lie fometimes feveral days, before they are gutted, falted, and packed, in confequence of which they grow ftale and ferment, The Dutch, on the contrary, indefatigably purfue their me- thod day and night, during twenty, twenty-four, or (wenty- fix weeks, be the weather what it may. Hence, their fifh are ufually more tender, better flavoured, and not fo very falt as the Englith and the Scotch, - * Mr. M‘€ulloch’s Treatife (fee note, page 413) fays, they fhould alfo be kept cleanly, and out of the fun, as well as froft or Kain, There 250 Dutch method of catching and curing herrings. DUTCH METHOD OF CURING HERRINGS, There are two methods of falting and preferving herrings for a confiderable length of time. The one is called white falting, the other red. The former is thus performed. Im- mediately on being taken, the fifh are gutted, as above de- fcribed, and wafhed in clean water. Then falt is fprinkled on them, either internally, or both within and without, and the fifh, being thrown into large bafkets with handles, are well roufed, (or fhaken about a few times) that the falt may the better sie AMelh and penetrate: or, laftly, which is the beft method, they are thrown into a tub filled with a ftrong brine made with bay falt and frefh water, in which an egg will fwim. In this pickle they are left upon deck in the open air, provided the weather be good, during twelve or fifteen hours; but, if circumftances require, a good deal longer, and are well ftirred (efpecially if pickled on fhore) with fhovels feveral times, that the falt may the better and more generally penetrate every where. Laftly, to pack them properly, they are taken out of the pickle, fuffered to drain fufficiently, and then packed in barrels, which are ftrewed at bottom pretty thickly with falt, and, if there is time enough, they are neatly laid in ftrata or layers, always flrewing fuff- cient falt upon each layer. But, if the abundance of fifh be too great, they are thrown in promifcuoufly, with as much falt as is requifile to preferve them from fpoiling. When this is done in ftrata, each new layer is preffed down hard upon the preceding. This laft-mentioned procefs, however, cannot eafily be attended to at fea, efpecially when the fifhery is very abundant. Hence, if the fith are to be exported, or remain long unufed, they are re-packed on fliore, laid in frefh falt, and prefled down hard; without which precaution her- rings exported by fea would {poil. The fame praétice is pur- fued in France, Hamburgh, and doubtlefs elfewhere. At Hamburgh, as in Holland, they are packed in the open air, ten packers and three overfeers being appointed for the pur- pofe, and all fworn. Befides re-packing, the packers in the maritime towns have alfo to pick and affort the fifh, according to their goodnefs, falt them anew, and put them in frefh pickle. It is alfo generally a part of the magiftrates and trading companies oaths, not to fuffer any bad fith to be de- livered from the quay or cuftom-houfe. After DUTCH METHOD OF CURING HERRINGS, Ase | ” After packing, whether the goods are intended for expor- Dutch method tation or home-confumption, whether preffed down hard or Of Catching and ; curing herring$. not, they are regularly coopered, that the pickle may not leak out, and the fifh turn yellow or fpoil, which takes place the moment they are deficient in pickle. Properly, the herrings fhould, on the very day on which they are taken, not only be gutted, but falted and put in cafks, or at leaft fhould not lie more ‘than one night in the firft pickle. And accordingly fuch herrings are diftinguifhed in France by the name of Harengs @une nuit. But, when the fithery is abundant, this is not always poffible; fo that only a part can be properly attended to; and the reft, after being gutted, muft unavoidably remain, at leaft the whole following day, if not longer, in the firft pickle, the regular packing of them being poftponed till the third day, Thefe fith, having flood two nights on deck in the open air, are called Harengs de deux nuits. But fuch goods not only are inferior, but do not keep fo well as the former. If the fifhermen mean again to caft their nets on ‘the follow ing night, or if, on account of the great abundance of the fhoals, they do not expeét to complete the falting and regular packing in two days, the fifb, which they cannot fo complete, are falted in large heaps, and are then called Slabbers, or Stlabbegut, coarfe goods. Thefe are frequently too falt, be- caufe want of time prevents their being properly managed. They are put into the {chuyts, which always accompany the herring-buffes, and wafhed; after which they are {moked ; though not fo much as the Bickléngs (Biicklinge) or red-her- rings. The falted herrings, hitherto fpoken of, are called Bockel herringe, or pickled herrings, or, in general, plainly Herrings ; thofe properly falted and packed im layers, Packed, or Barrel herrings; and thofe half falted, and promifcuouily — packed in barrels, Wrack herrings. ' The other mode of curing, called Redsfalting, is thus per- formed. When the fifh are taken out of the above-defcribed pickle, in which, however, they muft remain longer than thofe intended for the common, or white-faliing, and at leaft four-and-twenty hours; they are bung by the head in rows on wooden poles, in ftoves conftruGed for the purpofe, each of which generally contains 12,000 herrings. Being thus placed, a fire is made under them with vine-ftalks, or any at green 252 Dutch method of catching and curing herrings. BUTCH METHOD OF CURING HERRINGS, green faggot-wood, that affords much fmoke and little flame.* Here they remain till dried, and properly fmoked, which ge~ nerally requires twenty-four hours. Thus they become Bick- lings, or Red-herrings; when thefe are packed in barrels, they are called Barrelled Bicklings, and are much falted ; but, if laid in ftraw, they are called Straw Bicklings, and are fomewhat lefs falled. The excellence of the Bicklings prin- cipally confifts in their being large, fat, tender, frefh, pro- perly falted, pliable, foft, of the colour of gold, and not torn or mangled. In Holland, the beft fith are chofen for this purpofe; but in other places, the above-defcribed Slabbers only are ufed, or other inferior herrings, deemed unfit for the ufual mode of falting. The beft and fatteft {moked Dutch ° herrings are called, in German, Speckbucklinge, or fat red- herrings; in low Saxon, Flzckhdringe; and in Hamburgh, Flikheeringe. They are cut open along the back.+ . * At Bremen, the place moft celebrated for finoking fith, and where no fecret is made, as in Holland, of the procefs, they are hung in ovens of the fize of a fmall parlour, and ftri& attention is paid not to ule fir, or any wood, in which is any the leaft turpen- tine or refinous matter, which invariably gives a bad'tafte to the fith. + The a& of parliament regulations, and many ufeful obferva, tions, may be feen in two fimall traéts, 8vo, in poffeffion of the Society for the Encouragement of Arts, Manufaétures, and Com- merce, the one entitled, ‘* Obfervations on the Herring-Fifhery upon the North and Eaft Coaits of Scotland, &c.; with plain Rules, propofed for curing, and for fupplying the London Market with White Herrmgs: By Lewis M‘Culloch, many Years employed in furnifhing the Merchants of London with Herrings for Exportation. London. Richardfon, 1788... The other entitled, ** The bet and moft approved Method of curing White Herrings, and all Kinds of White Fifh; containing particular Dire&tions how to flit, gut, falt, dry, and barrel them, fit for’Sale ‘at home or foreign Markets; with Directions for boiling of Oil: Bya Trader in Fith, London. J. Davidfon, 1750,” The a DENSITY OF SOLID MERCURY. 3 953 Vil. Th Denjity of Mercury in its folid State afcertained. By Mr. Joun Bippvir. To Mr. NICHOLSON, SIR, Birmingham, March 4, 1805. Agr the Philofophical Society in Birmingham, of which I Experiments be- am a member, I read a few weeks ago a lecture on mercury. fore the Eola ; In the courfe of my experiments on this iubjeét, conducted Gitahiphan with a view of exhibiting this metal in a folid ftate, by ex- pofure to the frigorific mixture of muriate of lime and fnow, it appeared to me the {pecific gravity of this metal would be moft accurately obtained in comparifon with other metals under fimilar circumftances of folidity and temperature. J therefore undertook, amongft a variety of others, the follow- ing experiments, to afcertain its fpecific gravity in a folid ftate, which I believe had never before been accomplifhed : They fucceeded to my fatisfaétion, and to the gratification of fome who were prefent: I am, therefore, inclined to be- heve, you will think them worth inferting in your Philofos phical Journal. I am very refpectfully yours, JOHN BIDDLE. —EEeE HAVING purified mercury, by diftilling from an earthen Mercury was pu- retort into a glafs receiver 50 per cent. of the quantity put in, oe re aaa Oe . . P to avoid the alloy of any other metal, and afterwards having heated it to 300° of Fahrenheit, to drive off any water that might adhere, fuch as was ufed in other experiments, and expofed to the aftion of muriate of lime and {now,—I pro- ceeded as follows: One thoufand grains of this mercury were introduced to the and expofed to fied ing ciixitiire) together with three ounces of alcohol, in We Wied a round-bottomed glafs; and having placed in the mercury a fine bent wire, the weight of which was previoufly known when immerfed in the fame alcohol, to a certain point, in the temperature of 47 degrees above zero of Fahrenheit : this wire, during the congelation of the mercury, was fixed in it, fo that 25 4 DENSITY OF SOLID MERCURY. that the whole became attached to the inner furface of the glafs, and could not be feparated until the glafs with its con- tents was taken out of the freezing-mixture, and warmed, by dipping it in water, fo as to foften the mercury at the furface attached to the glafs; one hand being applied to the wire at the fame time, to draw the mercury from the glafs at the moment of its being loofened: it was then replaced, as be- fore, in the freezing-mixture. ‘Wifible figns of © During the congelation of the mercury it was obferved, ‘ AAA eie the furface of the metal towards the centre was very confi- ip treccing derably depreffed by the contraétion of its particles, and the " veflel having been moved during its congelation, a {mall hole ' nearly reaching the bottom of the glafs, was obferved gra- dually leffening in its dimenfions, prefenting a conical cavity with the apex downwards, The wire which held the mercury attached to it was now fixed by the other bent end to the hydroftatic balance, which held in the oppofite fcale the weights by which the mercury had been weighed in the ajr, together with the balance of the wire immerfed in the fame alcohol to a point marked on the wire. Lofs of weight It appeared by weighing the 1000 grains of mercury thus abe immer- immerfed in alcohol, the lots of weight was 59,8 grains: this ‘ was weighed five or fix times, with the glafs ftill in the freez- ing mixture, with the fame refult; but when it was with- drawn only a little way from the muriate of lime and {now, the difference of weight was perceptible, in confequence of the temperature of the mercury and alcohol increafing. Comparativeex- One thoufand grains of pure filver, weighed by the fame periment with an fcale immerfed in the fame alcobol at the fame temperature, equal weight of : : 5 filvers loft in weight 88,105 grains: therefore, as the lofs of the weight of the mercury is to the lofs of weight in the filver, fo is the fpecific gravity of the filver to the fpecific gravity of the mercury. Whence thefpe- The fpecific gravity of the filver in the fame balanbe having cific gravity Of been afcertained, by diflilled water, to be 10,436, it follows, ee " if this fum be multiplied into the fum of its lofs fufpended and = 15.612) weighed in alcohol, and divided by the fum of lofs of mer- ; eury weighed in the fame way, that the fpecifie gravity of ’ the mercury in the folid ftate, at about 40 degrees below zero on Fahrénheit’s feale, equals 15,612. Ry GEOMETRICAL PROPOSITIONS. 955 By the fame hydroftatic balance it appears, the fame mer- Sp. Gr. when cury in a fluid ftate, the thermometer ftanding at 47 degrees os ay above zero, is 13,545, By thefe experiments it appears, the difference $8 denfity between its fluid ftate, at the temperature of 47° above zero, and its folid ftate, at 40° below zero, is 2,0673 in 13545, or 1,5265 in 10, which is 15,265 per cent. that is, nearly 2th of its greateft volume, or nearly 4th of its leaft volume. ‘ Vil. Obfervations on Mr. Boswexrx’s Geometrical Propofitions. By An OLp CoRRESPONDENT. To Mr. NICHOLSON. SIR, March 6, 1805. W en your ingenious correfpondent Mr. Bofwell fent On Mr. Bof- to you his difcovery of a ready method of determining a Well’s lines | drawn in a circles chord-line equal to the fide of a fquare of the fame area as the eircle in which it is drawn, it fhould feem that he was not aware that the quantum of error might be afcertained by cal- culation, as you have done in the fubjoined note, otherwife he would not have fatisfied himfelf with the mechanical proof which he has adduced as a teft of its accuracy. Had it oc- curred to you, I am perfuaded you would with equal facility have fhewn, that this gentleman’s other “* faét in geometry” is ftill more erroneous, though announced with a degree of confidence which appears to have arifen from a miftaken conviétion of fuch obvious accuracy as ftood not in need of proof. “« A right line (BE), fays he, drawn from the extremity B of the line 1B, at right angles through the oppofite diameter (LF) to the circumference, will be equal to a fourth of the cir- cumference,”’ Let us try how far Mite affertion is founded in truth. But Overfight by in- before we enter upon the examination, I will beg leave to Vérfion of terms in W. N.’s note. point out a circumftance in your note, page 152 in your laft number, which, baving arifen out of inadvertence in your tranfcribing 256 GEOMETRICAL PROPOSITIONS. tranfcribing it moft probably, may tend to puzzle your reads ers, and amohg the reft perhaps Mr. Bofwell himfélf, who muft be the moft interefled: You have faid, “ as the radius is to IW, fo is the diameter to 1B,” (Plate VIII. Fig. 10); but I take it for granted you meant, ‘as I W is to radius, Jo is the diameter to 1B,” becaufe this analogy is agreeable to Farther elucida- the refult of your calculation. And as you have net men- tion of the note. tioned how the do@trine of fimilar triangles applies in the con ‘ftruétion of the figure, I hope you and your numerous readers 7 will not deem me prefumptuous, if I introduce the diagram again with fome additions, particularly as it will give me an opportunity of proving more intelligibly the error of the fecond propofition already quoted. Any triangle formed ina femi- circle, of which the’ diameter is one fide, with its oppofite angle at the circumference, isa right angled triangle (Eucl. III. Prop. xxxi.): ‘This will be the cafe in Mr, Bofwell’s figure if a right line be drawn from B to F, the right angle being at B; and as the angle at I is common to the {mall right angled triangle 1O W, and to tie large one I B F, the two triangles are fimilar, and therefore the hypothenufe I W of the fmall one is to its bafe IO, as the hypothenufe I F (or diameter) is to the bafe I B of the large one. Q.E. D. ; How far Mr. With refpe& to the fecond propofition, it is very well B.’s fecond pro- known (Eucl. III. Prop. xx.) that the angle formed at the pofition is accu. ; X i ! rate. centre of a circle is double of the angle at the circumference, if they have the fame common chord as a bafe; now in the triangle IO W (Plate XI. Fig. 4), the fides IO being given = .5, O W = .25, and therefore IW = .55901, we have, by a fimple cafe in plane trigonometry, the angle at I = 26° 33’ 5.4, the double of which ts\53° 6’ 10.86 for the angle BO F at the centre; but BG, one half of the line B E in queftion, is the fine of this angle, and in natural num- bers is, by the tables, equal to .7997163, when unity is ra- dius; but, in our figure, the diameter reprefents unity, there- fore the double fine, or chord line, B E is = .7997163, which, according to Mr. Bofwell’s affertion, ought to be = .7854, or one-fourth of the circumference 3.1416; hence the error is .0143163, or very nearly 4th of the whole. Apology to thefe As I have not the pleafure of knowing Mr. Bofwell, not« remarks, withftanding I have admired feveral fpecimens of his ingen ity, and as I profefs to be a promoter of all arithmetical ape. proximations ie LACTIC ACID. 257 proximations and fcientific proje@ts, that have for their means facility of application, and utility for their obje@, I mean fo far as they have accuracy to recommend them, IJ truft he will not impute any motive of a perfonal nature to me, but give me credit for the declaration, when I affert, that the implied invitation colle€ted from his memoir, to afcertain the accuracy of any of his projeéts, has been my only inducement for laying before the public the prefent paper. lam, Sir, With due refpeét, An O.p CorRESPONDENT. he A Memoir on Milk and the La@ic Acid. By Cit, BourttoN LAGRANGE, (Concluded from page 144.) "Tue muriate of foda, and more efpecially the muriate of Curd is not fee lime, affords a proof of this. Thefe falts effect a feparation of ae angsty the curd only in part; and, neverthelefs, the muriate of lime of water, has.a very great affinity for water: the decompofition ought therefore, in this cafe, to be made in a more ftriking manner than with the acids. Whey is not therefore the produ& of fermentation. The Whey not a alcohol obtained from milk does not prove that this formation Preduét of fer- mentatione is neceflary in order to obtain the laétic acid; for this laft may be obtained from a ferum recently prepared. With regard to the formation of the carbonic acid indicated Carbonic acid im in the fixth experiment, it is owing to the decompofition of ¥#¢Y a {mall portion of animal matter, and part of the fugar of milk diffolved in the ferum. ‘The more of thefe fubftances is de- compofed the greater will be the quantity of carbonic acid formed, and accordingly the degree of acidity is more marked on account of the prefence of the carbonic acid; but if the » acid be expelled, the ferum is milder, and not fo four as that which has been for fome time expofed to the air. If the ferum be expofed to the air for ten or twelve days, Acetic acids in proportion as the faccharine matter is decompofed the whey Voi. X.—APRIL, 1805, S becomes 258 Whether the falts in whey render it four. Zoonic acid by diftilling milk; is acetous acid. Curd contains phofphate of lime, Examination of whey feparated by different -2ZNtSe EBACTIC ACID becomes more acid. 'Thefe degrees of acidity are owing to 2 {mall quantity of acetic acid, formed by the aid of carbonic acid and alcohol remaining in the liquor, which muft naturally augment the acidity of the acid already formed in the milk. With regard to the fecond queftion, Whether whey exhf- bits acid properties only on account of the falts it holds in {olution ? I have proved that the acid may be lie: from the faline matters without expofing the milk to the air for acertain time, as Scheele has dire€ted; and the experiments I fhall relate in this memoir will afford additional proofs. So that its acid properties do not depend merely upon the falts it holds in folution, and the la@tic acid is not produced by a fermentation fimilar to the acetous. Though the aétion of caloric upon milk is generally known, I fhall neverthelefs make an obfervation upon the acid ob- tained by diftillation with a naked fire, which has for feveral years been known by the name of the Zoonic Acid. If this acid be purified and combined with potafh, a falt is obtained, which prefents all the chara¢ters of the acetate of potafh. I muft alfo obferve the cheefy matter in which fome che- mifts have been unable to find phofphate of lime, as announced by Scheele. ‘To obtain this, nothing more is neceffary than ftrongly to heat this fubftance in a crucible after having well - wathed it, and to calcine it to whitenefs. The refidue is a hard white matter, of which fome {mall pieces, veined with blue, may be compared to the turquois. The nitric acid diffolves it without effervefcence,; lime- water and ammonia occafion a flocculent precipitate of phot phate « of lime. | The Bisiaic of ammonia alfo demonftrates the prefence of lime. SEC PO NTE: Concerning the Serum of Milk. Being defirous of knowing whether there is any difference between the wheys obtained from milk by different fubftances, I made ufe of the mineral acids, fome vegetable acids, falts, fuch as alum, the acidulous tartrite of potafh, &c. The coa- cen a was employed in due quantity; as I had — 3 remarked, LACTIC ACID, 959. femarked, that when an excefs of acid is ufed, it is found to exift in the ferum; whereas, when the neceflary quantity is ufed, it is found in the cheefe only. After having feparated’ the cheefy matter the ferum was It is the fame clarified ; the wheys were found to have all the fame tafte and ple a a i colour, and poffeffed the fame degree of acidity. This freth whey turns fyrup of violets green: This property It affeéts fyrup mutt be attributed only to the union of ‘the ‘yellow and blue, & vicletss and not to faline matters, as chemifts have afferted. Whey, . which has loft its colour by expofure to the air, reddens the fyrup of violets. The means employed to afcertain the acids which had been ufed to coagulate the milk, did not exhibit even the fmalleft quantity when. the operation was performed with exaétnefs. I made a comparative examination of the ferum which had Sour ferum by become four in the open air; and I obtained, by expofing the ies a Co milk, the fame phenomena as were pointed out in the fecond fe€tion and third experiment. The {pontaneous ferum differed, 1. In its tafte, which was differed from more acid; and, 2. Its colour, which is dull and whitifh, ‘er f&rum. - owing to white filaments which are feparated. It may be had clear by filtration, without aeuniing the colout of frefh whey. The cheefy matter refulting from the fear experiments Cheefy matters before related, gave the ine red with tinéture of turnfole, If it be calcined and treated with the known re-agents, the prefence of fulphuric acid will be indicated if this- acid has been employed in the coagulation, and alumine when alum has been made ufe of. I do not therefore fee any inconvenience, in preparing whey Alum or fulphu- for the purpofes of pharmacy, to coagulate the milk with one hae he or the other of thefe fubftances, more efpecially if the precau- HE INE milks tions I have mentioned be attended to. Thofe who have thought it unwholefome to coagulate milk with alam, have doubtlefs made no experiment on the fubjeét. Oxigen gas is not abforbed by the ferum; even agitation Oxigen and fe- does not facilitate its union. rum. ~ The ation of lime- water, the folution of barytes, ftrontian, Other agents, and fome metallic falts, though already known by chemitts, require to be again examined, and will enable me to explain the proceffes for obtaining laétic acid. 5 2 SECTION . > 2960 LACTIC ACID. SECTION IV. On the Sugar of Milk. Whether acetic The formation of acetic acid does not-arife merely from the. ae Ee a alteration of the fugar of milk; and though the experiments decompofition of already defcribed “admit of certain conjeétures, I have afcer- its fugar. tained whether a like quantity of fugar of milk could be ob« tained from frefh ferum and a ferum expofed for twelve days ata temperature from 14 to 20 degrees, A little fugaris I have found that four milk affords a fomewhat lefs quantity ee by of fugar of milk, which proves, that a portion of the faccharine a matter was employed in forming a quantity of acetic acid. We may therefore obtain carbonic acid, alcohol, and acetic acid, either by confining whey in clofe veffels, or by leaving it expofed to the air. Other experiments made on pure fugar of milk indicated nothing remarkable. Habitudesof It does not redden tinéture. of turnfole. When diffolved fugar of milk» in water and expofed for a long time to the air, it does not become acid. By diftillation it affords acetic acid along with the known produéts, It is foluble in weak acetic acid. If a fmall quantity of freth gafeous matter be added, it is foon found that the liquor holds it in folution. By pouring in a few drops of alkali to faturate the excefs of acid, it lofes its trarifparency, becomes | turbid and milky, with a mild tafte refembling that of milk, ant preferves its opacity for a confiderable length of time. General refults The following refults are deducible from the preceding refpecting milk. f, 5 :— 1, New milk reddens the tinéture of turnfole. 2 ‘Thescheely matter may be feparated without contaét of the air. 3. The ferum does not retain the acids made ufe of to coa- "-gulate milk. 4, Diftillation either of milk or of fugar of milk to drynefs, affords the acetic acid. ‘ 5. The formation of carbonic acid and alcohol is owing to muco-faccharine mattem 6. A quantity of acetic acid is formed by the fermentation of thcfe fubflances, 7. The t LACTIC ACID, 961 7. The cheefy matter, when feparated, always manifefts the prefence of an acid, and differs in tafte and confiftence according to the matters employed in its feparation. 8. When wafhed and affording no fign of acidity, if it be efierwards diffufed in diftilled water for feveral days, at a temperature between 15 and 22 degrees {about 65 and 80 Fahrenheit), it acquires a {trong difagreeable odour; the fluid flightly reddens turnfole, and lime difengages ammonia, 9. The ferum and the cheefy matter contain, befides the known fubftances, phofphate of lime, as Scheele had an- nounced. 10. The difference which exifts between frefh mts and that which has been expofed to the air, confifts in the acetic acid, which is prefent along with the free acid-in the milk. 11. Laftly, there exifts in milk and the ferum a free or yncombined acid, which feemed to me to be the acetic acid, SECTION VY. Concerning the Laétic Acid. Scheele having afcertained that it is not poffible to obtain Laétic acid, not the acid by fining diftillation, had recourfe to peculiar me- ppisiney fimple diftilla- thods to effeét this feparation. tion. This chemift firft reduced the whey to one-eighth by eva- Scheele’s pro- poration; he then filtered it, and there remained, oe oe Evaporate whey . to him, no more cheefy matter. to one-eighth. ‘He faturated the fluid with lime-water, and phofphate of Filter. Saturate with lime-water lime was precipitated : This liquor having been filtrated and which An dilated with three times its quantity of water, he poured in down phofphates Iter. Dilut oxalic acid drop by drop, to feize and precipitate all the lime; rare ate and he afcertained, by the addition of a little lime-water, cipitate lime by that no more oxalicacid remained. He evaporated the liquor setae 6 to the confiftence of honey; the thickened acid was re- confiftence. Dif- diffolved in reétified alcohol; the fugar of milk and all the eS foreign fubftances remained on the filtre, not having been Then add waters diffolved by the alcohol. Laftly, after having again added a a = 8 2 aiconol, e uc little water to the acid held in folution bat the alcohol, he is ae aaa’ drew off this laft fluid by diflillation, and found the laGtic acid in the retort, This long and expenfive procefs does not afford a pure Tt is not pure. acid. It was therefore neceflary to adopt a fimpler procefs before its nature was examined, Experiment 962 LACTIC ACIDé With freth whey - Experiment 1. If inftead of expofing whey to the air ‘as as isob- Scheele direéts, the procefs be immediately performed on the frefh whey, a very {mall quantity only of acid is obtained, which is lefs coloured) and has a more animal fmell. This acid appeared to me to be uncombined in the milk, as its quantity was fo fmall, If barytes or Experiment 2. Inflead of ufing lime-water and the oxalic chee tabe ae I ufed barytes or ftrontian ‘tai the fulphuric acid. By ufed inftead of this means I obtained an acid no lefs pure than that of the aa bee peel Swedifh chemift. Scheele the re- xperiment 3. I had likewife attempted to ications a - fult is equally Ja@tate of potafh with acetate of lead, expeéting to form a eke lagtate of lead decompofable by the fulphuric acid; but the acetate of lead precipitate thus formed is nota laétate of lead, for when a uniuccefsful. futieient quantity of fulphuric acid is added for the purpofe of decompofing it, no uncombined acid is fet at liberty. It ap pears that part of the oxide falls down with the animal matter; and this compound is even to a certain degree foluble. It is alfo found that the fluid won @ retains much acetate of lead 1 in folution. We therefore fee that though this procefs has been pointed ‘out as fuperior to that of Scheele, it is certain that it cannot be employed to obfain the la@ic acid. The following e pein ments were made on the laétic acid of Scheele. Dieioacdar 1. The intenfity of its colour may be diminifhed by grinds _ Scheele ex-_ ing a piece of red hot charcoal in a mortar, and pouring the a laic acid upon it. A quantity of {mall flakes were feparated which rofe to the furface. The fluid was flightly boiled and filtered, and the acid was then le!s coloured, and had lefs i ie Nhen this acid is diflilled in\a retort acetic acid pafles over vine thick yellow very acid matter remains, 3. It may perhaps be thought that part of this acid becomes changed into acetic acid by the-affiftance of caloric, as Ber- thollet obferves in his Chemical Statics. «©The ternary acids, as this chemift obferves, may be © changed into acetic acid, when by the ation of heat they ' abandon part of their carbon, and their elements, which refift this aétion lefs, are feparated by volatilazation.” I have afcertained that great part of this acid previoufly exifted in the fluid. 3. The . } LACTIC ACID. 963 '-$. The fame phenomena take place, but more ftrikingly, if whey be diftilled which has been expofed to the air at the temperature of 15 or 20 degrees (60 and 68 Fahrenheit) for- about a’fortnight. The firft produét is a clear tranfparent fluid of an acid tafte, and odour of alcohol, which when combined with potafh, forms an acetate. If alcohol be added to what remained in the retort, it be- ‘ comes coloured. After decantation and diftillation, an acid is found in the retort of a peculiar odour, animalized, and re- fembling the preceding; but the acid contains a very {mall quantity of phofphate of lime. . Thefe experiments confirm the obfervations I have made : It is a mixed 1. That a mixed acid is obtained by the procefs of Scheele, ** and 2. That an acid exifts in milk and in whey recently prepared. It remains to fhew the nature of that acid. For that purpofe I prepared the lac acid according to the procefs of Scheele with every neceffary precaution. I even afcertained the purity of my alcohol, which having been diftilled from muriate of lime, marked 40 degrees of the aerometer of Reau- ‘mur. The laGtic acid when diffolved in alcohol was fubmitted to When diffolved diftillagion, There paffed into the receiver an alcohol which fami, ew reddefied the tin@ure of turnfole. sai Bick the nine When the acid was totally deprived of alcohol the diftilla- La@ic acid ree tion was flopped. The laétic acid of Scheele remained of a ™ained. yellow colour and very four tafte. : Experiment 1. I mixed quick lime with this concentrated It gave out am- acid, and a difengagement of ammonia took place.* poke ben Experinient 2. If a laétate of potath be formed and evapo- Latate of siitalhs rated by a gentle heat, a brown matter is feparated, which is leaves preflic infoluble in water. This being afterwards heated iy a cruci- ea ke ble, the falt {wells up and emits an animal odour. The pre- fence of pruffic acid was proved by diffolving the remainifg matter in water and adding a {mall portion of the fulphate of iron in folution: * I had before afcertained the prefence of ammonia in this acid. I announced it on the 15th Nivofe to the Society of Pharmacy. Mr. Vauquelin, who was not acquainted with this faét, informed me at the reading of the firft part of this memoir that he had alfo afcer- tained the prefence of an animal matter in the laStic acid of Scheele, - Experiment BGA LACTIC ACID. Sulph. acid Experiment 3, If fulphuric acid be added to Jaétic acid, or og daccs to a lalate of potath, a difengagement takes place not only of acetous acid. acetic acid, but alfo of an elaftic fluid, which forms a thick cloud when in contaé& withammonia, Diftillations Experiment 4, When the preceding mixture is diftilled in an apparatus proper to receive the gafeous produét in water, the diftilled water of the bottle preferves its tranfparency; the {mell of acetic acid is very evident; it reddens turnfole and precipitates the muriate of filver. When a {mall quantity of ammonia was brought near the tube out of which the gas iffued, a very denfe cloud was formed, Fire decompofed Laperiment 5. What was left in the retort was evaporated the acid of the to drynefs, This refidue was brown, very acid, and when lactate of potath> sFerwards heated in a crucible of platina, {welled up and left a coal. During this operation a {mall quantity of {ulphuric acid was decompofed. The matter that remained in the retort was diffolved in dif- tilled water. The folution did not redden turnfole, but it gave a brown colour to paper tinged with curcuma. A little fulphuric acid was added to faturation, and after evaporation cryftals were obtained by cooling, which exhibited the cha, raéters of fulphate of potafh. As the fupernatant liquor had a metallic tafte, pruffiate of lime was poured on it, which produced a bluifh tinge. Lattic acid dee Experiment 6. The laétic acid may alfo be concentrated to compofed by fire drynefs ; heated to incineration in a crucible; afterwards dif, et pion _folved ina diftilled water and precipitated by nitrate of filver, A muriate of filver is formed which may be feparated by the filter; and the fluid which contains the nitrate is then eyapo- rated and decompofed by heat, A while matter remains, which when diffolved in water, affords with the tartareous acid an ‘acidulous tartrite of. potafh. Component parts Hence I conclude that the la@ic acid of Scheele is com- of Scheele’s pofed of acetic acid; muriate of potath; a fmall portion of wept iron probably diGlead in the acetic acid; and an oaimal mabtet 8 MAGNESICAL FYRITES. 265 an An Analyfis of the Magnetical Pyrites; with Remarks on fome of the other Sulphurets of Jron. By Cuartes Hatcuert, Ejy. FL RS. From the Philofophical Tranjactions for 1804. § I. Or the various metallic fulphurets which conftitute one of Univerfal dif- the grand divifions of ores, none appear to be fo univerfally dif- eee perfed throughout the globe, as the fulphuret of iron, commonly phurets of iron. called Martial Pyrites; for the {pecies and varieties of this are found at all depths, and in all climates and foils, whether ancient, or of alluvial and recent formation. It is remarkable alfo, that, under certain circumftances, this fulphuret is daily produced in the humid way; an inftance of which, a few years back, I had the honour, in conjunétion with Mr. Wifeman, to lay before this Society ; * and although, in regard to pecuniary value, the pyrites of iron may be confidered as comparatively infignificant, yet there is every reafon to believe, that in the operations of nature, it is a fubftance of very confiderable importance, g Il. The fpecies and varieties of martial pyrites, are in general fo Among the numerous fpecies well known, and have been fo frequently and accurately de- one is remarkable fcribed, as to figure, luftre, colour, and other external charac- for ftrong mag- ters, that it would be totally fuperfiuous here to give any de- sea blige’ tailed account of them. One of the {pecies, however, merits peculiar notice, as poffefling the remarkable property of {trong magnetic polarity; and, although it has been defcribed by mo- dern mineralogifts,+ it does not appear to have been as yet fub- jeéted to any regular chemical examination; fo that, whether it be a fulphuret of iron inherently.endowed with the magneti- cal property, or a fulphuret in which particles of the ordinary magnetical iron ore are fimply but minutely interfperfed, has to this time remained undecided, * Phil. Tranf. for 1798, p. 567, + Kirwan, Vol. II. p. 79. Widenmann, p. 792. Emmerling, ad edit. Tom. II. p. 286. Karften, p. 48. Brochant, Tome II. p- 232, This 266 ¥ts obvious or external proper- ties, Where found, Degrees of magnetif{me. Abundantly found in Caer- narvonthire. MAGNETICAL PYRITESS This {pecies is known by the name of Magnetical Pyrites, and is called by the Germans Magnet-Kies, or Ferrum minerali« Jatum magnetico-pyritaceum. It is moft frequently of the colour of bronze, paffing to a pale cupreous-red, The luaftre is metallic, The fra@ure is unequal, and commonly coartelpeuiaieds but fometimes imperfeéily conchoidal. The fragments are amorphous. The trace is yellowifh-gray, with fome metallic luftre. It is not very hard; but, when ftruck with fleel, fparks a are produced, although ial fome difficulty, It is brittle, and is eafily broken. = This pyrites has been hitherto found only in fome parts of Norway, Silefia, Bavaria, and efpecially at Geier, Mefferfdorf, and Breitenbrunn in Saxony ; but, having received fome {peci- mens from the Right Hon. Charles Greville, F. R. S. I was ‘ftruck with their refemblance to the pyrites of Breitenbrunn, which happened at that time to be in my poffeffion ; and; upon trial, I found that they were magnetical, and agreed with the Jatter in every particular.. Their magnetic power was fuch as firongly to affe@t a well-poized needle, of about three inches in length; a piece of the pyrites, nearly two inches fquare, aéted upon the needle at the diftance of four inches. The powder (which is blackifh-gray, with bat little metallic luftre) is immediately taken up by a common magnet; but the pyrites’ does not a€t thus on the powder, ‘thor on iron filings, unlefs it has been placed for fome time between magnetical bars; then indeed if aéts powerfully, turns the needle completely round, attraéts and takes up iron filings, and feems permanently to retain this addition to its original power, In the fpecimens which I obtained, the north pole was gee nerally the ftrongeft. This pyrites was found im Wales, sine the year 1798, by the Hon.- Robert Greville, F. R.S. who fent the {pecimens above defcribed to his brother, the Right Hon. C. a with the following account. “It is found in great abundance in Caernarvonfhire, near «« the bafe of the mountain called Moel Elion, or probably with “‘ more accuracy Moel Ailia, and oppofite to the mountain « called MAGNETICAL PYRITES. . Y67 “called Mynydd. Mawr. Thefe mountains form thaentrance € intoa little clofe valley, which leads to Cywellin lake, near ‘¢ Snowdon, a little beyond the hamlet of Bettws, ‘* The vein appears to be fome yards in depth and breadth, ‘and feems to run from north to fouth, as it is found on «© Mynydd Mawr, which is acrofs the narrow valley, and ** oppofite' to Moel Alia.” Mr. R. Greville, in another part of his letter, ftates that copper ore has been worked in feveral of the adjacent places, _and that, many years ago, Capt. Williams, of Glan yr Avon, employed fome miners at the place where this pyrites is found, ' but the undertaking proved unprodu@ive. Yellow copper ore is certainly in the vicinity ; for fome portions of it were adhering tothe fpecimens which have been mentioned ; and I fhall here- obferve, that the ftone which accompanies the-magnetical pytites, is a variety of the lapis ollaris or pot-{tone, of a pale grayith-green, containing fmooth cubie cryftals of common pyrites. § III. From the appearance of thofe parts of the magnetical pyrites Magnetic’py- ‘which have been expofed to the weather, it feems to be liable ites is fightly ae cite oxidable by the to oxidizement, but not to vitriolization. : weather. The fpecific gravity, at temperature 65° of Fahrenheit, is Sp. gravity. 4518. When expofed tothe blowpipe, it emits a {ulphureous odour, Efe of mere and melts into a globule nearly black, which is attracted by the Lae by blow magnet, Five hundred¢grains,° in coarfe powder, were expofedy ina—ina crucible ; fmall earthen,retort, to a red heat, during three hours. By - - this operation, the weight of the powder was very little di- minifhed; neither was there any appearance of fulphur in the receiver, which however {melt ftrongly of fulphureous acid, Five hundred grains of the fame were put into a flat porce-—in the mufilt. Jain crucible, which was kept in a red heat, under a muffle, during four hours. The powder then appeared of a dark gray, with a tinge of deep red, and weighed 432.50 grains. |The Jofs was therefore 67.50 = 13.50 per cent. but, upon examining the refiduum, I found that only part of the fulphur had been ‘thus feparated, The 268 Partly foluble in dilute fulph, acid. Precipitates, Effet of nitric acid. Of muriatiec acide MAGNETICAL PYRITES. The magnetical pyrites, when digefied in dilute fulphuric acid, is partially diffolved, with little effervefcence, although there is a very perceptible odour of fulphuretted hydrogen. The folution is of a very pale green colour. Pure ammonia produced a dark green precipitate, tending to black; and prufliate of potath formed a very pale blue preci- pitate, or rather a white precipitate mingled with a {mall portion of blue, The whole of the latter, however, by expofure to the air, gradually aflumed the ufual intenfity of Pruffian blue; and the blackifh green precipitate, formed by ammonia, became gradually ochraceous. Thefe effeéts therefore fully prove, that the iron in the folution was, for the greater part, at the minimum of oxidizement, fo as to form the green fulphate, and white pruffate, of iron; * and, confequently, that the iron of the magnetical pyrites is either quite, or very nearly, in the ftate of pence metal, This pyrites, when treated with nitric acid, of the fpecie gravity of 1.38, diluted with an equal quantity of water, is at firft but little affeéted; but, when heat is applied, it is diffolved, with much effervefcence, and difcharge of nitrous gas; the effervefcence, however, is by no means fo violent as when the common pyrites are treated in a fimilar-manner, It is alfo worthy of notice, that if the digeftion be not of too long dura- tion, aconfiderable quantity of fulpbur, zn /ubjtance, is feparated ; whilft, on the contrary, fearcely any can be obtained from the common pyrites, when treated in a fimilar manner; although I fhall foon have occafion to prove, that the reat quantity af fulphur is much more confiderable in the latter than in the former, As foon as muriatic acid is poured on the powder of the magnetical pyrites, a flight effervefcence is produced, which becomes violently increafed by. the application of heat; a quantity of gas is difcharged, which, by its odour, by its in- flammability, by the colour of the flame, by the depofition of fulphur when burned, and by other properties, was proved to be fulphuretted hydrogen, During the digeftion, fulphur was depofited, which fo en- veloped a fmall part of the pyrites, as to prolee it from the farther a€tion of the acid. * Récherches fur le Bleu de Pruffe, par M. Proutft. — de Chimie, Tome XXIII. Pp 85. The MAGNETICAL PYRITES. 2969 The folution was of a pale yellowifh-green colour. With neva folue pruffiate of potath it afforded a pale blue precipitate, or rathera i white precipitate mixed with blue; and with ammonia it formed a dark blackifh-green precipitate, which gradually became ochraceous; fo that thefe effets corroborated the conclufions which were founded on the properties of the fulphuric folution, namely, that the iron contained in the pyrites, is almolt, if not quite, in the metallic ftate. Other experiments were made; but, as they merely confirm the above obfervations, I fhall proceed to give an account of the analyfis. § IV. ' ANALYSIS OF THE MAGNETICAL PYRITES. A. One hundred grains, reduced toa fine powder, were Analyfis. , : oe Eel 100 gr. mapgnes dizgefted with two ounces of muriatic acid, ina glafs matrafs ,;, sycites wots placed in a fand bath. The effeéts already defcribed took eminlly mu- place; and a pale yellowith-green folution was formed. The Bead Gkcae refiduum was then again digefted with two parts of muriatic Refidue treated acid mixed with one of nitric acid; and a quantity of pure ees deen fulphur was obtained, which, being dried, weighed 14 grains. fulphur fepa- B. The acid in which the refiduum had been digefted, ae Pa ~ was added to the firft muriatic folution; fome nitric acid was Jutions was added alfo poured in, to promote the oxidizement of the iron, and dog saein acid *)- ee: . . ° é and the iron w thereby to facilitate the precipitation of it by ammonia, which ghey Sean. iy was added after the liquor had been boiled for a confiderable ammonia. The time. The precipitate thus obtained was boiled with lixivium Leen doe. of potafh; it was then edulcorated, dried, made red-hot with ath and then ree ‘wax in a covered porcelain crucible, was completely taken up ee Sei by a magnet, and, being weighed, amounted to 80 grains. C. The lixivium of potafh was examined by muriate of The potath lix- ammonia, but no alumina was obtained, eee me D. To the filtrated liquor from which the iron had been pre- The firft folu- cipitated by ammonia, muriate of barytes was added, until it sess was > $F te . "4 f recip. muri- *ceafed to produce any precipitate; this was then digefled with oe oe pba fome very dilute muriatic acid, was colleéted, wafhed, and, The ng aes i ; t - after expofure to a low red heat for a few minutes in a crucible a aid of platina, weighed 155 grains. If therefore the quantity of the quantity of fulphur, converted into fulphuric’acid by the preceding oper- bes detain ations, and precipitated by barytes, be calculated according to the accurate experiments of Mr. Chenevix, thefe 155 grains of fulphate 970 MAGNETICAL PYRITES: | fulphate of barytes will denote, nearly, 22.50 of falphur : fo that, with the addition of the 14 grains previoufly obtained in fubfance, the total quantity will amount to 36.50. Eftimate of the EE. Moreover, from what has been flated it appears, that oP lglg inthe the iron’ which was obtained in the form of black oxide; weighed 80 grains; and, by adding thefe 80 grains to the 36.50 of fulphur, an increafe of weight is found = 16.50. This was evidently owing to the oxidizement of the iron, which, in the magnetical pyrites, exifts quite, or very nearly, in the metallic ftate, but, by the operations of the analyfis, had received this addition. The real quantity of iron muft, on this account, be eftimated at 63.50. Component One hundred grains, therefore, of the aagaones pyrites, parts. ielc Sulphur 4. and welded, ae icon 7. Sulphur | D. 92.50 i 36.50 grains. Tron Ee 63.50 100. Analyfis re- This analyfis was repeated in a fimilar manner, excepting peated by acidi- that the whole was digefted in nitric acid, until the fulphur was fying all the ful- , 5 pbur by nitric intirely converted into fulphuric acid. To the liquor which acid. Same fe- remained after the feparation of the iron by ammonia, muriate of fult. ; sy he . ‘ barytes was added, as before, ahd formed a precipitate which weighed 245 grains. Now, as the fulphuric acid in fulphate of barytes is eftimated by Mr, Chenevix at,23.5 per cent. and the fulphur which is required to form the fulphuric acid contained in 100 parts of fulphate of barytes, at 14.5 *, it follows, that 245 grains of dry fulphate of barytes, contain fulphuric acid equal, very nearly, to 36 grains of fulphur; fo that the two analyfes corroborate each other. The proportion of fulpbur in the mag- netical pyrites, may therefore be ftated at 36.50, or indeed at 37 per cent. if fome {mall allowance be made for the occafional prefence of earthy particles; a minute portion of quartz having been found, by. the laft analyfis, after the complete Ba cay of fulphur. ; The iron in this The increafe produced, by the operations of the analyfis, and inall pyrites, jn the weight of the iron, arofe, as I have already remarked, is very nearly in the metallic. | from the addition of oxygen; for the iron, as obtained bythe | tate. analyfis, was in the ftate of black oxide; but in this, and * Tranfaétions of the Royal Irifh Academy, Vol. VIII. ‘p.'240.. \ indeed ‘MAGNETICAL PYRITES. 971 indeed in all pyrites, it undoubtedly exifts very nearly,. or quite, in the ftate of perfect metal. Now the black oxide of iron, called Protoxide by Dr. Thomfon*, has been proved, by Lavoifier and Prouft, to confift of 100 parts of metallic iron combined with 37 of oxygen, thus forming 137 of black oxide; the exaét proportion of oxygen is therefore 27 per cent, and 80 grains of this oxide muft contain 2J.6 of oxygen. But, in the above analyfes of the magnetical pyrites, the . increafe of weight did not amount to more than 16.5; and we may therefore conclude that, in all probability, a quantity of oxygen = 5,1 was previoufly combined with fome part, or with the general. mafs, of the iron in the pyrites. A {mall part of the abovementioned increafe of weight, mutt likewife i have arifen from another caufe ; for, although the true propor- tions of the black oxide of iron are 27 of oxygen and 73 of iron, (fo that 100 parts of the latter abforb 37 of the former,) yet, in a€tual praétice, it is difficult to obtain it exaéily in this fiate, and there is commonly a fmall excefs of weight: this I have repeatedly obferved, in many experiments, fome of which were purpofely made. When, for inftance, 100 parts of fine iron wire were diffolved in muriatic acid, and after. wards precipitated by ammonia, edulcorated, dried, and made red-hot with a fmall quantity of wax in a covered porcelain crucible, the weight, inftead of 137, ufually amounted to 139 or 140. The quantity of wax employed, certainly did not afford a ponderable quantity of coal, or other refiduum ; but the real caufe of the increafe of weight, appears to be the air, which can fcarcely be completely excluded, and which, after the wax is burned, combines with the fuperficial part of the oxide, and converts a portion of it into the red or per- oxide ; fo that the furface in the crucible appears brown, when compared with the interior. To this caufe, therefore, I. am inclined alfo to attribute a {mall part of the increafe obferved in the weight of the iron obtained by the preceding analyfes. § V. Before I make any obfervations on the nature of the ful- Comparative phuret which has been proved to conftitute the magnetical @alyfis of other pyrites, by aci« - Se dif h * Syftem of Chemiftry, 2d edition, Vol. I. p. 147. re np pyrites, fulphure 272 MAGNETICAL PYRITES. pyrites; it may be proper to ftate fome comparative analyfes which I have made of feveral-of the common pyrites; and, as the method employed was precifely the fame as that which has been defcribed, all that feems to be requifite, is to give an account of the refults. In each analyfis, the whole of the fulphur was converted into fulphuric acid, which was precipitated by barytes ; and, in the feleCtion of the {pecimens, great attention was paid to take the internal parts of the fragments, and not to make ufe of any which exhibited an appearance of decompofition, or of extraneous fubftances, The iron was, as before, reduced to the ftate of black ox- ide; and the addition of weight in each feparate analyfis, correfponded, within a few fractional parts, with the propor- tion of oxigen requifite to form into black oxide a given quan- tity of metallic iron, equal to that which in each pyrites was afcertained to be the real proportion, by deduéting the quan- tity of fulphur from the total quantity of each pyrites. The iron, therefore, in thefe is completely metallic, and as fuch is ftated in the following refults ; Sulphur 52.15 The component No. 1, Pyrites in the form of dodecaedrons eS o7.85 parts of the come with pentagonal faces. + > mun pyrites ef Se 1 ete walls Specific gravity 4830, 100. um, 9 fulphur and 8 iron, with no great varia- tion. Sulphur 52.50 No. 2. Pyrites in the form of ftriated cubes. iron of aia 100. Sulphur 52.70 No. 3. Pyrites in the form of fmooth polifhed Iron 47.30 cubes, found in the lapis ollaris which accompanies the magnetical pyrites. Specific gravity 4831. 100. Sulphur 53.60 No. 4. Radiated pyrites. - = S 46.40 Specific gravity 4698. 100, Sulphur 54.34 Iron 45.66 No, 5. A fmaller variety of radiated pyrites, Specific grayity 4775. 100. Confidering the difference in the figure, luftre, and colour of thefe pyrites, 1 expeéted to have found a much greater difference MAGNETICAL PYRITESS 273: difference in the proportions of their component ingredients ; but, as the refults are the average of feveral experiments, I have not any reafon to doubt their accuracy. The pyrites cryftallized in regular figures, fuch as cubes Regie age and dodecaedrons, according to He abode analyfes, contain “doen lefs fulphur, and more iron, than the radiated pyrites, and other pyxites. perhaps than others which are not regularly cryftallized. | This difference, however, is not confiderable ; for the dodecaedral pyrites, which afforded the fmaileft quantity of fulphur of any of the regularly cryftallized-pyrites, yielded 52:15; and the tadiated pyrites, No. 5, gave 54.34; the difference, therefore, is only 2.19. So that the mean proportion of ful+ phur, in all the pyrites which were examined, is 53:24 per cent. and, taking the proportion of fulphur in the magnetical pyrites at 36.50 or 37, the difference between this and the mean of the common pyrites will be 16.74 or 16.24. The magnetical pyrites, therefore, is quite diftinét, as a fulphuret of iron, from the common martial pyrites; and, in the follow ang obfervations I fhall prove, that a fulphuret coniifting of the proportions laft mentioned, has ull now been unknown as a product of nature. § VI. Although pyrites is one of the moft common of mineral Hiftory of py-" fabfances, yet the difcovery of its real nature is comparatively ‘ cutest of a late date; for it appears that even Agricola (whofe know- ledge of mineral bodies was certainly great, confidering the ftate of {cience in his time) was not acquainted with its cha- rateriftic ingredient, namely, iron. According to Henckel, this was firft noticed by our countryman Martin Lifter, a member of this learned Society, who fays, ‘* Pyriles purus putus ferret metallum eft.” From the time of Henckel, pyrites feems little to have Experiments of attraéted the notice of chemifts, until Mr. Prouft, the learned P'°4*+ profeflor of chemiftry at Madrid, publifhed two memoirs, in which he ftates, that there are two fulphurets of iron, the one Two fulphurets being artificial, and the other natural. The firft is the falphu- or eee ret which is formed in laboratories, by adding fulphur to red- eafily foluble in hot iron, or by expofing both of them to heat in a retort. This 2“!4% and natu - Maarten ; , i a boats ral, lefs folubles is diftinguifhed from the fecond fulphuret, (which is the com- “mon martial pyrites,) by its éafy folubility in acids, efpecially Vou, X.---APRIL, 1805, x in Q7 Ae MAGNETICAL PYRITES? in muriatic acid, by the formation of falphuretted hidrogeri gas during the folution of the fulphuret in the laft named acid,! by its colour, and by its inferior denfity. Artificial ful- According to Mr, Prouft; the firftvor artificial fulphuia is is Ceara compofed of 60 parts of falphur, combined with 100 parts of iron; natural, iron; whilf the fecond fulphuret, or common pyrites, confifts 9 fulphur and 10 of 90 parts of fulphur and 100 of iron. ' iron. - ke exbek of He moreover obferves, that the fulphur of the Gr -fulphiiret fulphur is eafily js difficultly feparated; but that the excefs which isin the fe- feparated from d fateh me ee Gl Ned d Sy pyrites; but not Cod fulphuret, or common pyrites, is eafily expelled, and is the other por- that portion which is obtained by diftillation, the refiduum i being then reduced to the ftate of the firft fulpburet *. 100 parts, therefore, of this fubftance, are compofed of 62.50 of iron and 37.50 of fulphur; and 100 parts of common pyrites are, according to this flatement, compofed of 52.64 of iron and 47.36 of fulphur. They are the Thefe proportions Mr. Prouft confiders as the minimum acne ne 0M and maximum of the fulphurets of iron. For the latter he fulphurets. allows fome variation; but‘the compofition of the former he regards as fixed by the invariable law of proportions +; al- though:he obferves, that zt has not as yet been difcovered in ihe mincral kingdom t. ° In Grane of thefe affertions, Mr. Prouft fates, Experimentsof 1. That the pyrites found near Soria, when diftilled in a . wor this retort heated to rednefs, afforded nearly 20 per cent. of ful- ub) ° phur. 2. That the refiduum of the above: difillation had loft the © external charaéters and chemical properties of pyrites, and had affumed thoie of the artificial fulphuret of iron, * Fournal de Phyfique, Tome LIII. p. 89, and Tome LIV. p., 89. From pp. 91 and 92 of Tome LIV. it is evident, that the author does not mean to affert, that the firft fulphuret contains 60 per cent: of fulphur; but that 100 parts of iron are combined with 60 of fulphur, and form 160 of the fulphuret. In like manner, when 90 of fulphur are united -with 100 of iron, a fubftance analogous to common pyrites is formed, which weighs 190 grains or parts. See alfo our Journal, I. 109, 269, 253, for tranflations of thefe excellent memoirs. + Yournal de Phyfique, Tome LIKI. p. 90. { ‘© La regne minéral, jufqu’ icly ne nous a point encore iprée fenté le fer fulphuré au minimum.” ‘Journal de Phyfique, Tome AV..p. 93. ‘ 3 3. That MAGNETICAL PYRITES. Q75 3. That when to this refiduum a quantity of fulphur was added, and the whole was diftilled in a degree of heat not too great, the 20 per cent. of fulphur, which had been feparated by the firft diftillation, was, by this, again reftored; and the mafs in the retort thus recovered nearly the original colour, luftre, and chemical properties of the pyrites. 4. That, by adding fulphur to iron filings, or fine iron wire, heated to a low red ina retort, a compound is obtained, in which the proportion of fulphur amounts only to about 20 or 30 parts; but, if this compound is again treated with fulphur in a red heat, a fulphuret is formed, which is readily diffolved in acids, and plentifully affords fulphuretted hydro gen gas. This is the real minimum of the fulphurets of iron, fixed by the invariable law of proportions, (according to Mr. - Prouft,) at 59 or 60 of fulphur and 100 of iron, the former being (as I have already obferved) in the proportion of 37.50 per ceng, 5, and laftly. That when this fulphuret is again mixed and diftilled with fulphur, (due attention being paid to the degree of heat,) the produét is found to have aflumed moft of the chemical and external properties of the natural common pyrites, denfity alone being excepted. - The application of the above obfervations, to the principal The magnetical fubjedt of the prefent paper, is fufficiently obvious 5 for, when nee it is contidered, that the magnetical pyrites is fo different from confidered as the common pyrites, in colour, hardnefs, folubility in fulphuric having been only acid, and more efpecially in muriatic acid, with the copious sii aes Th produétion of fulphuretted hydrogen gas; when, by aralyfis, it has been found to confift of 36 or 37 of fulphur, combined with about 63 of metallic iron; and, when the artificial ful. phuret'of iron which has been lately defcribed, is proved-to agree with the magnetical pyrites in the nature and proportions of its component ingredients, and in every one of the aboves mentioned properties ; it is evident that the magnetical pyrites is identically the fame with this fulpburet, which hitherto has remained undifcovered in nature, and has only been known as a produ@t of our laboratories, In order however more fully to fatisfy myfelf, I made experiments on the artificial fulphuret, which I formed with {ylphur and fine iron wire. T2 This PF ean 276 The artificial pyrites agrees IMAGES FORMED BY CONVEX LENSES. This fubftance agreed, in all the properties which have beer rah the natural NOtCed, with the antes pyrites; and the precipitates ob- magnetic pyrites. tained by adding pruffiate of potafh, and ammonia, to the Remarks on the Leiters of C. L. Quotation, in which C. L. de- nies Mr. W.’s gadis. Mr. W.’s reply. Horizontal MvQNe muriatic and Eh hulle folutions, were precifely fimilar. The {pecific gravity was 4390, whilft (as I have already remarked) that of the magnetical pyrites is 4518. (To be concluded. ) r nese aera XI, Anjfwer to a Letter of C. L. with other Remarks, on the Images . formed bly convex Lenfes, Jn a Letter from Mr, Ezextet ~ Walker. To Mr. NICHOLSON. DEAR SIR, C. L. in his letter in your laft Number, reprefents my firft paper as deficient in ** philofophical corre@nefs,” and wanting “‘ the calm fpirit of philofophy.”” But in attempting to prove. my errors, he has proved nothing but his own want of know- ledge: and to thofe who wifh to fee an example of C. L.’s * calm fpirit of philofoply,” I beg leave to recommend the perufal of bis letter in Vol. IX. p. 235, of this Journal.— Thefe firange affertions are followed by another ftll more firange. He fays, “ [will beg leave to wave any altention to the hiftory of Mr. Walker’s experiments upon which I have ani- nadverted, and to deny his facts.” ‘Thinking that I did not underftand his meaning correétly, I examined. the fide-note, which runs thus: ‘* C. L. declines any turther difcuflion refpecting Mr. Walker’s experiments with lenfes, but denies the faéts.”’ As there is no reafoning with a man who will deny facts, I fhall decline examining the remainder of C, L.’s letter. Your other anonymous correfpondent, who has denied the truth of my experiments, will be more eafily anfwered, The opinions which have been advanced refpe€ting the horizontal lumimaries, fince the days of Ptolomy, who was born about the year 70 of the Chriftian era, are, fo numerous, that {MAGES FORMED BY CONVEX LENSES. O77 that it is fearcely poffible to form a new one. This corre- {pondent has picked up the theory of Des Cartes, which was confuted more than 100 years ago by Mr. Molyneux. See Philof. Tranf. abr. Vol. I. p. 221; or Dr. Hutton’s Mathe- matical Di@ionary, Vol. Ii. p. 74. I fhall pafs over this writer’s optical errors by juft obferving, that he has been doing nothing lefs than denying an eftablifhed property in optics. But before I proceed, it may be convenient to thofe who Farther remarks are not in poffeffion ‘of your twe Numbers which contain my ak former papers on this fubjeét, to know what that property y : in optics is, which has met with fo much oppofition. I have proved experimentally, that the image of a candle afferted to vary in the focus of a double convex lens, decreafes in magnitude With the aper- as the aperture of the lens is contraéted *; And I have allo advanced, that the image of the fun or moon, in the focus ef the obje@-glafs of a telefcope, decreafes with its aper- ture f+. Now it is well known to thofe who underftand optics, This pofition that this property, the truth of which has been denied fo po- “epg to NewWe fitively, was difcovered by Sir Ifaac Newton: and a demon- {tration of it may be feen in the Optics of Newton, Emerfon, Smith, and Martin, and alfo in the Encyclopedia Britan- nica, &c. ‘¢ The breadth of the leaft circular fpace into which obje@Q- becaufe he notes glaffes of telefcopes can colleé all forts of parallel rays, he tpace of dif : _ , fufion in pencils about the 273 part of half the aperture of the glafs, or 55th of rays. part of the whole aperture.” (Newton’s Optics, 2d Idit, p- 73). Hence it is evident, that if you contraé the breadth Whence it is of the objeét-glafs from 10 to 1, the breadth of the circle of S¢4ceds that : Serna, Be : the image alfa light, in its focus, will be contraéted in the fame proportion, will vary. Jn my next paper, this interefting property of light will - be further explained, : Iam, Dear Sir, _Your humble fervant, EZ. W/ LKER, Lynn, March 16, 1805. * Philofophical Journal, Vol. IX. p. 164. + Philofophical Journal, Vol. X. p. 110, QT AEROSTATIC VOYAGE, KU: - Account of an Aeroftatic Voyage, made by M . Gay-Lussac on the 29th Fruétidor, in the Year 12. Read to the National Inftiiute, on the 9th Vendemiaire, in the Year 13.* | c Motives of the In the account of the firft aeroftatic voyage which M., Biot alcent. and I had the honour to fubmit to the Inftitute, we announced that, from the furface of the earth to the height of 3977 metres (13024.675 feet), the magnetic power did not experience any fenfible diminution; and at the fame time we fignified a defire to undertake new afceénts, to afcertain this important fact. at greater heights. We foon found that this was alfo the wifh of many members of the Inftitute; and, encouraged by the ge- neral intereft which our fir voyage had excited, we refolved on making a fecond very fhortly; but our aeroftat not being capable of carrying us together to a greater height than in our firft afcent, it was agreed between us that I fhould go alone, From ‘this moment all our attention was given to the inftru- ments which it was requifite for me to carry; and their cone ftruGtion, which was again entrufted to M. Fortin, as well as an operation which the balloon underwent to give it more levity, retarded my departure till the 29th of laft Fruétidor, Conftruétion of — Inftru@ted by the experience of our former afcent, we the infirumentts ode fome changes in our inftruments; and, in the firft place, Horizontal si that. the ofcillations of the horizontal needle might be lefs needy affeled by the rotation of the balloon, we caufed a new one to be conftru€ted, only 15 centimetres in length. Thus, its ofcillations being more rapid than thofe of the balloon, it would be eafier to determine their duration. ; Dipping needle. © We made greater modifications in the dipping needle, That we might not be obliged, at each obfervation, to replace it in the magnetic meridian, and to adjuft its axis truly horizon- | tal, we fufpendéd the metallic chape which fupports it by a filken thread; and, to judge of its inclination, we fixed a portion of a tranfparent circle, graduated in divifions, to the chape. The whole apparatus was very light, the tenfion on the filk thread but tyifling, and the needle could refume its ¥ From Annales de Chimie, No. 154, Fruétidor, An, XIII, meridian —— ee ee ee Ss > a / AEROSTATIC VOYAGE. 279 meridian with facility: M.Coulomb, after having touched the needle, proved it by the method which he propofed in the Memoirs of the Inftitute ; and he found that it gave an ineli- nation of 70.5° of the common feale. In one of its pofitions, which was that in which it was to remain, it varied 31°. In our firft afcent, the under furface of the glafs which Azimuth come covered our azimuth-compafs was covered with water, and? Ay, we were prevented from feeing the fiadow of a horizontal thread, which ferved us for a ftyle. To avoid this inconve- mience, it was fufficient to remove the glafs of the compafs; in other refpeéts, no alteration was made in its firft difpofition. M. Lepine again fupplied us with two fecond-watches, one of which was a ftop-watch: it was with the latter that I made all my obfervations, The thermometer I ufed, was the centigrade. mercurial Thermometers thermometer.. To guard it from the a¢tion of the fun, we placed it within two concentric cylinders of pafteboard co- vered with gilt paper; one of which was about four centi- metres in diameter, and the other fix. Our hygrometers Hygrometerss” with four hairs, of the conftru€tion of M. Richer, were dif- poled in nearly a fimilar manner, The two glafs balloons'in which I was to bring the air, were exhaufted to nearly a milli metre of mercury, and we were fatished by leaving them in this ftate for eight days, that they perfe@ly retained the va- cuum. For fear of an accident, we had provided a third bal- loon. of brafs; but very fortunately it was ufelefs, — Z - Our two barometers have not a conflant level; and to get Barometers; the true barometric heights, we formed a table of comparifon, by placing them under the receiver of the pneumatic ma- chine, and meafuring their depreffion from five to five cen timetres, by means of a ftandard, the refervoir of which hasa eonftant level, and which is provided with a very good fcale, Being no longer obliged to obferve more than the upper level to get the trué barometric heights, the number of obfervations was diminifhed to one half; which is of great importance when the attention is divided between perfonal fafety and delicate experiments. _ Such nearly were the effential inftruments I took with me ‘Im my voyage, I was alfo provided with an apparatus for The apparatus determining the ele@tricity of the air; but a few moments afte: vs meafuring e electricity of I toon the earth, I loft the two sietallid wites which wete the air rendered u to ufelefs, 286 AEROSPATIC VOYAGE. to atiraQ the eleétricity at 50 and at 100 metres below mey and I could not make any ufe of it. It will be feen that we had avoided every thing which could influence our needles ; and even our anchor, although fufpended 50 metres below the boat, was of wood armed with copper. This is not the place to mention the precautions which M, Conté had taken, that this new afcent might be free from danger; but it is to be wifhed that he would himfelf publifh what a long and enlightened experience has taught him on this fubje€i. For ourfelves, we owe him a great fribute of gratitude for his trouble and the intereft he has taken in our voyages ; and we are bound to acknowledge, that if they have been fo fortunate, we are indebted for it to his provident cares, Departure. All our inftruments being ready, my departure was fixed for the 29th Fru@tidor: In fa@, on that day I afcended from the Confervatory of the Arts and Manufaétures, at 9" 40’, the barometer being at 76.525 centimetres, the hygrometer at State of the at- 57.5°, and the thermometer at 27.759. M. Bouvard, who inc epics 2teorological obfervations daily at the Obfervator pec makes meteorolog y y of Paris, judged the atmofphere to be greatly charged with vapour, but without clouds. In faét, I had feareely rifen 1000 metres when I perceived a light vapour diffufed through all the atmofphere, which rendered the fight of remote objeéts confufed, Firfterperiment Arrived at the height of 3032 metres (9929.8 F.), I sided on che offs | to make the horizontal needle ofcillate, and this time I ob- rizonial needle. tained 20 ofcillations in 83”, while on the earth, and in other refpeéts in the fame circumftances, it required 84.33” to make the fame number *. Although my balloon was affected with the rotatory motion we had percetved in our firft experiment, “ the rapidity of the motion of our needle Baines me to count 20, 30, and even 40 ofcillations. Inclination of At the height of $863 metres (12651.365 F.), I found the the necdle ata variation of my needle, taking the mean of the amplitude height of i eee ai feet, Of its ofcillations, was lenfibly 31°, as ‘on the earth, It re- the fame as on the earth. bg ‘ . * Althouch I have here indicated hundredth parts of a fecond, I am aware that I cannot obferve fuch fimal] fragtions; but I ob- tained them by divifions, becaufe on the earth I generally made 30 efcillations, which required 126.5”, 2 quired ATROSTATIC/VOYAGE. ~ 981 quired much time and patience ta make this obfervation bev caufe, although borne by the mafs of the atmolphere, I per- ceived a flight wind which continually deranged the compals, ° and after feveral unfuccefsful attempts, I was obliged to give up making new ones. Neverthelefs, I believe the oblerva- tion [ have ftated above is entitled to {ome confidence. Some time after I wifhed to obferve the dipping-needle ; The obfervations but behold what had happened. The drought, favoured by so pat 9 the aGion of the fun in a rarefied air, was fuch, that the come not to be de- pafs was fo much warped as to have bent the metallic circle prnses ayer on which the divifions were traced, and to be itfelf crooked, The motions of the needle therefore had not the fame free- - dom; but independently of this difappointment, I had ob- ferved that it was very difficult to obferve the dip of the needle with this apparatus. In fhort, when I placed the compafs Caufes of its dee. fo as to make the fhadow of the horizontal thread, which ane ferved as a ftyle, coincide with a fixed line, the motion I had given to the compals communicated one to the needle, and by the time this was nearly reftored to reft, the fhadow of the ftyle no longer coincided with the fixed line. It was ne- ceflary to place the compafs again in a horizontal pofition, and during the time which this operation required, every thing was again deranged. Unwilling to perfift in making . obfervations on which I could place no reliance, I abandoned them entirely ; and divefted. of every other care, I gave all my attention to the ofcillations of the horizontal needle. [ The experiment am neverthelefs convinced, by the knowledge of the defeéts ftill-pradeicables of our compafs, that it is poflible to employ one more fuitable, which would determine the dip with great precifion, In trying this experiment, I lowered the other heedles feparately in linen bags, to 15 metres below the boat. That the aggregate of all the refults which I obtained may The aggregate be more eafily feen, [I have colle€ted them into a table which Naa alae: is at the end of this memoir; and they are placed there as table. they occurred to me, with the correfponding ‘indications of the barometer, thermometer, and hygrometer. The heights Calculation of haye been calculated, according to tne formula of M. Laplace, a oe by M. Gouilly, engineer of bridges and highways, who has compared with been fo kind as to take this trouble. The barometer not °"¢ ote earths having varied fenfibly on the day of my afcent, from ten e’clock to three, to calculate the different heights at which I made 282 and of the tem- perature. The irregular variation of the temperature arifes from the change of place during the ob- fervation. AEROSTATIC VOYAGE. made my obfervations, the height of the barometer on the earth has been taken at 76,568. centimetres, which. was the cafe at three o’clock; a height which, conformably to the obfervations made by M, Bouvard at, the Obfervatory;. is greater by 0.43 millimetres than that which had been obferved at the moment.of my departure. The heights of the. baro- meter in the atmofphere have been brought to thofe which would have been indicated by a barometer with an-uniform level placed in the fame circumflances, and the mean. between the obfervations of the two barometers has been taken. for each height. .The temperature on the earth having alfo va- ried very little between ten and three o’clock, it has been fuppofed conftant and equal to 30,75° of the centigrade ther- mometer, Now on looking into the table it will be evident, in the firft place, that the temperature follows an irregular courfe with refpeét to correfponding heights; which, no doubt, is occafioned by the obfervations having been made fometimes in afcending, and foretimes in defcending, and the thermo- meter having followed thefe variations too flowly. But if the degrees of the thermometer alone.are confidered, which form with each other a continually decreafing. feries, a more regu- Difference of elevation corre- fponding to a de- gree of the dif- ference of tem- perature. lar law will be found. Thus the temperature on the earth | being 27.75°, and §.5° at the height of 3691 metres, if the difference of the heights is divided by that of the tempera- tures, we fhall at once obtain 191.7 metres (627.8175 feet) of elevation for each degree of the reduction of the tempera- ture. By performing the fame operation for the temperatures 5,25° and 0.5°, as well as for thofe of 0° and —9.5°, we fhall. find, in both cafes, 141.6 metres (463.74 feet) of ele» vation for each degree of the reduétion of the temperature ; which feems to indicate that near the furface of the earth the heat. is governed by a law which decreales lefs than at an elevation in the atmofphere, and that at length it follows a decreafing arithmetical progreflion. If it be fuppofed that from. the furface of the earth, where the thermometer was at 30,75° to the height of 6977 metres (22849.675 feet), where it. had fallen to —9.5°, the heat had diminifhed as the eleva- tions increafed, an elevation of 173.3 metres (567.557 feet) will correfpond to each degree of the reduétion of the tempe- sature, The \ AEROSTATIC VOYAGE. ISS ~The courfe of the hygrometer was very fingular. At the Unfteady courfe ‘ pof the hygro- furface of the earth it was only at 57.5°, while at the height of 3032 metres it marked 62°: from this point it was conti- nually falling to the height of 5267 metres, where it indicated no more than 27.5%; and from thence to the height of 6884 metres, it rofe gradually to 34.5%. If, by thefe refults, it is withed to determine the law of the quantity of water diffolved in the: air at different elevations, it is clear that ‘attention muft be paid to the temperature ; and on joining this confider- ation with it, it will be feen that it follows an extremely de- creafing progretlion. If now the magnetic ofcillations are confidered, it will be'Magnetic ofcil- obferved that the time for ten ofcillations, made at different!4tions at difter- ent heights. heights, is fometimes above and fometimes below 42.16”, which they require upon the earth. By taking the mean of alk the ofcillations made in the atmofphere, ten ofcillations would require 42.20”, a quantity which differs very little from the preceding; but on confidering only the laft obfer- vations which were made at the greateft heights, the time for ten ofcillations would be a little lefs than 42.16°, which would indicate, on the contrary, that the magnetic power had been a little augmented. Without meaning to draw any confequence from this apparent flight increafe, which may very probably arife from the errors to which experiments of _ this defcription are liable, I conclude that the total of the The magnetic refults I now offer, confirms and extends the fa@ which M. tea ws fens 1 altered at Biot and myfelf had obferved, and which, as well as MP the ereaten cle- oniverfal gravitation, proves that the magnetic power does Vtions. not experience fenfible variations at the greateft heights to which we can afcend, The confequence we have drawn from our experiments, Probable pte will appear a little too precipitate to thofe who recolleé that? the touched needle. But if it be obferved that the power which caufes an horizontal needle to ofcillate, is neceflarily dependent upon the intenfity and dire@ion of the magnetic power itfelf, and that it is reprefented by the co-fine of the angle of inclination of this latter power, they cannot avoid concluding with us, that, fince the horizontal power has not varied, neither can the magnetic power have varied, unlefs they fuppofe that the magnetic power can have varied pres cifely. conelufion ¥ Tee we were unable to make experiments on the inclination of futed, 284 | . Further proofs of the magnét- ifm being the fame as on the earth. Heights at which the air was taken for examination. Greateft eleva- tion. Effects on the animal economy at this height. Clouds at a very great height during this afcent. Their extreme beight in the former one. AEROSTATIC VOYAGE: cifely in oppofilion to, and in the fame proportion ‘as the co- fine of its inclination, which is by no. means probable. In - fupport of our conclufion we have, befides, the experiment on the inclination made at the height of 3863 metres (12651.325 feet), which proves that, at that elevation, the variation did not vary in a fenfible manner. When at the height of 4511 metres, I prefented to a fmall touched needle, and in the dire€tion of the magnetic power, the lower extremity of a key ; the needle was attracted, and aflerwards repelled by the other extremity of the key, which I brought down parallel to itfelfi The fame experiment, repeated at 6107 metres, had the fame iffue: another very evident proof of the a@tion of terreftrial magnetifin. At the height of 6561 metres (21487.275 feet), I opened one of my two balloons of glafs; and at 6636 metres (21733.9 feet), I opened the fecond: the air entered both with a hiffing noife. Finally, at S" 11’, the aerofiat being perfedily full, and having only 15 kilogrammes of ballaft, I determined to defcend. The thermometer was then at 9,5° below the temperature of melting ice, and the barometer at 52.88 centimetres; which gives for my greateft elevation above Puris, 6977.37 metres (22550.887 feet}, or 7016 metres (22977.4 feet) above the level of the fea. Although well clothed I began to feel the cold, particularly in my hands, which I was obliged to keep expofed to the air. My refpiration was fenfibly obftruéted ; but I was far from feeling any inconvenience fufficient to induce me to defcend. My pulfe and my refpiration were greatly accelerated ; hence from refpiring very frequently in a very dry air, I could not be furprifed at my throat being fo dry, that it was with diffir culiy I fwallowed bread, Before fetting out I had a flight head-ach, arifing from the fatigues of the preceding day and the want of reft in the night, and I retained it all the day, without perceiving that it was increafed. Thefe are all the inconveniences I experienced. A phenomenon which ftruck me at this great height, was the feeing clouds above me, and at a diflance which appeared to me to be very confiderable, During our firft afcent the clouds did not rife above 1169 metres (3828.475 feet), and above, the fky was in its greateft purity. Its colour at the zenith was fo intenfe, that it might be compared with that of Prufian " AKROSTATIC VOYAGB. 285 Pruffian blue; but in the laft voyage which I made I faw no clouds below me; the fky was very vaporous, and its colour generally dull. It is perhaps not ufelefs to obferve, that on DireGion of the the day of our firft afcent the wind was north-north-weit, and vad. on the laft, fouth-eatt. As foon as I perceived that I began to defcend, I thought Defcent. only of moderating the defcent of the balloon, and of render- ing it extremely flow. At 3" 45’ my anchor touched the ground and held, which gives 34’ for the time of my defcent. The inhabitants of a fmall hamlet in the vicinity foon ran to: the fpot, and. while fome brought the balloon towards thei by drawing the rope of the anchor, others, placed under the boat, waited impatiently till they could reach it, with their hands, to catch and depotit it upon the earth. “My defcent was therefore effected without the flighteft fhock or the leaft accident, and I do not believe that a more fortunate one is pofible.. The {mall hamlet befide which I defcended, is called Saint-Gourgon; it is fituated fix leagues north-weft trom Rouen. » On my arrival at Paris, my firft care was to analyze the air Analyfis of the I had brought, All the experiments were made at the Poly- ae technic School, under the eyes of MM. Thenard and Greflet, and I)trufted as much to their judgment as to my own. We noticed the divifions of the eudiometer alternately, and with- out communication, and it was only when we were perfcétly agreed that we wrote them down. The balloon which was filled with air at 6636.5 metres (21735.537 feet), was open- ed under water, and we all judged that it had at leaft filled the half of its capacity ; which proves that the balloon had retained the vacuum very well, and that no foreign air had entered it. We, purpofed to have weighed the quantily of water entered into the balloon, to compare it with its capa- city; but not having the neceffary inftruments at, hand, and Qur impatience to know the nature of the air it, contained being very great, we did not make that experiment. . At firft ave ufed Volta’s eudiometer, and. we analyzed it compara- tively with atmofpherie air taken in the middle of the court- yard of the Polytechnic School. The following is the come parative analyfis of thefe two airs. - Analyfis 986 AEROSTATIC VOYAGE. Analyfis of the atmofpheric Analyfis of the dir taken at an ' Air. Elevation of 6636 Metres, Meafures. Meafures. Atm. Air, a3) Airy a - - $i: aay Hyd. Gas; ote; Hyd. Gas, + 2) Firlt a Refidue after Refidue, ~ 3.05 penimen': | - the combuf- tion, - 3.04 | rere hee Mécluress| : Meafuresé Of dees Atm. Air, 3 Arr, - ~~ 3. oy EPS 2 HydieGas, 2) 9 | AydsGasy + 2: riment, Refidue, 3.05 | Réefidue, - 3.0% Atmofpheric air © At the fame time one meafure of very pure oxigen gas and air taken at required '2.04 meafures of hidrogen gas; and this refult dif a great elevation, are identically fering only .OL from that obtained in experiments made on a the fame. very large feale, and with great care, in the compofition of water, it is evident that great confidence may be placed in our refults. They prove therefore that atmofpheric air, and air taken at an elevation of 6636.5 metres, are identically the fame, and that each of them contains .2149 of oxigen. On analyzing the latter air by hydro-fulphuret of potafh, we found in it .2163 of oxigen. 1 cannot give the refult of the comparative experiment made on atmofpheric air, becaufe ‘we were unable to colleét it; but ihe proportion of oxigen which I have indicated, 1s alfo a little greater than that given by the combuftion of hidrogen gas, and 1s comprized within the limits of the variations found in the compofition of the atmo(phere at the furface of the earth, and which do not pre- vent it from being confidered as conftant. This fa& proved The identity of the analyfes of the two airs made by a experi- hidrogen gas, proves direétly, that that which I brought did : not contain the latter gas; neverthelefs I alfo fatisfied myfelf of it, by burning with the two airs only a quantity of hidro- gen gas lefs than would have been requifite to abforb all the oxigen gas; for J found that the refidues of the com. buftion of the two airs with the hidrogen gas were exactly the fame. . Sauffure te Te ee i Ss 7 AEROSTATIC VOYAGE. | 937. Sauffure junior alfo found, by ufing nitrous gas, that air The compofition taken in the Col-du-Geant contained, within one hundredth Gums ody part, as much oxigen as that of the plain; and his father where the fame. afcertained the prefence. of carbonic «acid on the fummit of Mont-Blanc : Moreover, the experiments of MM, Cavendifh, Macarty, Berthollet, and Davy, have confirmed the identity of the compofition of the atmofphere over all the furface of the earth, It may therefore be concluded generally, that the conftitution of the atmofphere is the fame from the fur- face of the earth to the greateft heights to which we can afcend. © Thefe are the two principal refults which I obtained from Recapitulation my la{t voyage. I have afcertained the fa@ which had been % the Feftitss obferved by M. Biot and me, on the fenfible permanence of the intenfity of the magnetic power at a diftance from the furface of the earth ; and befides, I think I have proved that the proportions of oxigen and azote which conftitute the at- mofphere, do not vary fenfibly in the moft. extended limits. — Many things ftill remain to be elucidated in the atmofphere, and we hope the facts we have already collected will fo far intereft the Inftitute as to induce them to defire us to continue our experiments. . TABLE ee : j z L88°0S8Z% Le" LL69 88°SE me 4 o a L'lt Or o'¢s 06 BOOSH LES PI°ETSso 66°EE CHE. ja Orgy 1S J) ote | * or. [5 ot%s. |. Oa- | OFS'61102 Ig 6F19 OL'9¢ 666 | oo'6 =~ |S SY} Jo [add] oy} COV ol c Lat OG | EFE'LSEBL CO*LENG 81'GE ee Sa 2) 0°O i] O°SP Ol Ors 00 L¥FO"1000G 61° LOT9 96°9¢ IGE Ged ye ZES'ESLEL | OL'OFO9 LY‘L6 os |. Of — 0} PouyEM st yr I LO? Or S'9GT O¢ 16€'8S6TrEl 90°ELTE | Tt If OFBG 2), Ou é FEL S8CS8T CBP lga¢ 10°66 j'06 ¢ 0 (sajio} OZ) sosjou GES" 69081 916199 C86 Lo S'S 6E yoy ye fq po Oo or OI oO'69T OF GES" ESGLT * GL L960 a | a O'LG COT | 2 a 8SO' 1 S691 C8"1OOS 6F OP T'0€ COS Cea = bee =| agteh 31 + Ol | Suet F Be |B eeoeLEyl. }. 19 LISP 82'S% $6 | o1'9 * | sqysioy ay [Vv Sob | Ol C8SI | OF 005 '9F LST $1808 ES'E4 GLB | OG°9 . OOP Ot OPS. | OG O66 69FCL OG’ S6LF TOE 9°LG CG'8 a O'Sh Ol O'98. 03 IPLELIFI 98° LOEY 96°9% 6'6% Got =| 5 ‘ainuiedap ag} ai10j |g") p Or C°Sol Of 86L996ET GIPIST 99°99 6 06 Oot br: = COV Ol GILG} OG GOG'GLLTEI ID TISF 86 SF = : oe DD Fe. or = or FE ‘Or<\© eee'eorat | es9is¢ £0'6¢ oes |osor | g | @peur asa yorpm § L0°G80Z | GE 1G9E 89" 6F, G46 | OS'S e @ OOD FLAIT LLGLté 2 ae 0°0¢ OO'Tt uo aie See i Se Sok Oo” |3 Hee E -O5" |. gos'6z6c 10°S606 18'S O%9 | OF BI saad aur ysyayyp | OL'op Ol COSI O¢ 00 0°O GOS'OL G°L¢ GL'LG VW “ ae ° o “ot ten lA . *[2aoy JULY *519) "393 . : 3 ‘sour | en om pe ae ‘007 usu , ‘stir | -Wod & YIM 49jaW | -ouoIshy | -awows9yy SeRavevAuasao | Suipuod “Beals ) 5 suo Lae ut ByStay SAoqe $aij2uUl | -o1rg & JO IEY 03 Om? avy opraznuas pee OF NDP | ce csc ces Codec A acuitsaniars UL SIYBay | 3ySooaq araydjoune | — go suo ayy Jo saaiBap, MODY cad suoly Bhs See Ssdtuih, 4 sss Butpucdsauog YI Ut JayoWOIeg | -voiputoyT UL payotdxa| 2 eE(IIO . d q N . out jo jysiaq uray jo uroyy “sangeaaduss,L by ATV Se ‘SNOLLVAWASHO JO MOTION OF THE SAP. 289 XI. Experiments and Objervations on the Motion of the Sap in Trees. ina Letter fron THoMas Anvrew Knicur, Lfy. to the Right Hon. Sir Joserpu Banks, Rart. K.B.P.R.S, from the Philofophical Tranfuctions for 1804. My pear Sir, / In the Obfervations on the Defcent of the Sap in Trees, which Experiments I laft year took the liberty to requeft you to lay before the eee ar " on the motion of Royal Society, I offered a conje@ture, that the veflels of the the fap in trees. bark, which pafs from the leaves to the extremities of the roots, were, in their organization, better calculated to carry the fluids they contain towards the roots than in the oppofite direétion. I had not, however, at that time, any experiment direétly to fupport this fuppofition; but I thought the forms generally af- fumed by trees in their growth, evinced (he compound and con- tending actions of gravitation, and of an intrinfic power in the velfels of the bark, to give motion to the fiuid paffing through them. In the account of the experiments which I have now the honour to addrefs to you, I truft I fhall be able to adduce fome interefting fa¢is, in fupport of that inference. Having feleted, in the {pring of 1802, four ftrong fhoots of the vine, growing along the horizontal trellis of my vinery, I depreffed a part of each fhoot, whilft it was foft and fucculent, about three inches deep. into the mould of a pot placed beneath it for that purpofe ; but without making any wound, of incifion, in the young fhoots thus employed as layers. In this pofition they remained during the fucceeding fummer; and, in the autamn, had nearly filled the pots, which were ten, inches in diameter, with their roots. As foon as the leaves had fallen, the layers were difengaged from the parent flocks ; and about five inches of wood, containing one bud, were leit, both at the proper and the inverted end of each layer. Every bud was alfo, by previous management, made to ftand at an equal diftance from the mould in the pots, and with an equal elevation, of about thirtv-fix degrees. About one inch of wood was like- wife left at each end of every layer beyond the buds, | Vor. X.—APRIL, 1805. ea In / 290 Experiments and obfervations on the motion of the fap in treese MOTION OF THE SAP, In the fucceeding fpring, the buds vegetated ftrongly, both at the proper and at the inverted ends of the layers, as the experiments of Hales and du Hamel had given me reafon to expeét; and, in one inftance, the bud at the inverted end of the layer grew with greater vigour than that at its proper endz but the growth of thefe buds was not the objeét which I had In view. I have already ftated, that nearly an iaeh of wood was left at each end of every layer, beyond the bud ; and, to this wood, at the inverted ends of the layers, my attention was chiefly direét- éd: for, if the veffels of the bark poffeffed the powers I attributed to them, I concluded that the fap would be impelled to the in- verted ends of the layers, and be there employed in the pro- duétion of new wood, and roots; and, in this, my expectations were not difappointed. At the proper end of the layers, the wood immediately beyond the buds became dry and lifelets, - early in the fucceeding fummer ; the ftems alfo, between the buds and the mould in the pots, increafed in fize as ufual; and nothing peculiar occurred, But, at the inverted end, appear- ances were extremely different: new wood here accumulated rapidly beyond the buds, and numerous roots, of confiderable length, were emitted, whilft no fenfible growth took place be- tween the bafe of the young fhoots and the mould in the pots. “It having been proved by Du Hamel, that inverted parts of trees readily emit roots, I expeéted to derive further information from cuttings of this kind: I therefore planted, in the autumn of 1802, forty cuttings of the goofeberry-tree, and an equal number of the common currant-tree; one half of each being inverted. Of the former, not one of the inverted cuttings fuc- ceeded ; whereas few of the latter failed; and in thefe I had an opportunity of obferving the fame accumulation of wood above the bafes of the annual fhoots, and the fame mode of growth, in every refpeét, asin the inverted vines; except that no roots were emitted at their upper ends. ‘The fame thing occurred, without any variation, in inverted grafts of the apple-tree, If it be admitted, according to the theory Ihave on a former occafion laid before you, that the fap defcends from the leaves through the veffels of the bark, and that fuch veffels are, in their organization, better calculated to carry their contents to- wards the original roots than in the oppofite direQion, it will be extremely eafy to explain the caufe of the accumulation of ‘ wood, MOTION OF THE SAP, 991 wood, and the emiffion of roots, above, inftead of below, the Experiments bate of the annual fhoots. The veffels of the bark (the vaigeaux ie pi propres of Du Hamel) commencing in the leaves, were formerly the fap in treese traced by M. Mariotte, and fubfequently by myfelf, (being ignorant of his difcovery,) to the extremities of the roots ; and, when a cutting or tree is planted in its natural pofition, the fap pafles downwards through thefe, to afford matter for new roots, and to increafe the Bull of thofe already formed, having given proper nutriment to the branches and trunk in its defcents Bat, in the inverted cutting, or tree, thefe veffels become in- verted ; and, if their organization be fuch as I have fuppofed it, a confiderable part of that fluid, which naturally defcends, will be carried upwards, and occafion the produGtion of new wood, above, inftead of below, the junétion of the annual thoot with the older wood, asin the experiments I have defcribed. The force of gravitationawill, however, ftill be felt; and by its agency, fufficient matter to form new roots may be conveyed to thofe parts of the inverted cutting, or tree, which are beneath the foil. Befides, if we fuppofe a variation to exift in the powers or organization of the veffels which carry the fap towards the root, we may alfoattribute, in a great meafure, to this caufe, the different forms which different fpecies or varieties of trees affume; for, if the fluid in thefe veffels be impelled with much force towards the roots, little matter will probably be depofited in the branches, which, in confequence, will be flender and feeble, asin the vine; and there is not any tree that has been the fubjeét of my experiments, in which new wood accumulated fo rapidly at the upper end of inverted plants. To an excefs of this power, in the veffels of the bark, we may alfo afcribe the peculiar growth of what are called weeping trees ; for, by this power, the effeéts of gravitation will be, in a great degree, fufpended; and the pendant branch will continue healthy and ‘ vigorous, by retaining its due circulation, The perpendicular branch will, however, ftill poflefs {ome advantages ; for in this, gravitation will aét on the fluid defcending from the leaves ; and thefe will of courfe abforb from the atmofphere with in- creafed aétivity. A greater quantity of matter will therefore enter, within any given portion of time, into veffels of the fame capacity ; and this increafed quantity may frequently exceed that which the veffels of the bark are immediately prepared to carry away. Much new wood willin confequence be generated, U2 . and 292, Experiments and obfervations on the motion of the fap in treese MOTION OF THE SAF. and increafed vigour given; and, the fame caufes operating through fucceffive feafons, will give the afcendancy we gene- rally obferve in the perpendicular branch. In the preceding experiments, none of the layers, or cuttings, exceeded a few inches.in length; and, to the fummit of thefe the fap appeared to rife, through the inverted tubes of the wood, nearly as well as in thofe which retained their natural pofition. But fome former experiments had induced me to fufpeét, that this would not be the cafe in longer cuttings; I therefore planted in the autumn of 1802, twelve cuttings of the {wallow, (Salix caprea,) inverting one half of them. The whole readily emitted roots, and grew with luxuriance; but their modes of growth were extremely different. In the cuttings which flood in their natural pofition, vegetation proceeded with moft vigour at the points moft elevated ; but in the inverted cuttings, it grew more and more languid as it became diftant from the ground, and nearly ceafed, towards the conclufion of the fummer, at the height of four feet. The new wood alfo, which was generated by thefe inverted cuttings, accumulated above the bafes of the annual fhoots, as in the preceding inftances. -Thefe faéts appear to prove, that the veffels of plants are not equally well calculated to carry their contents in oppofite di- rections ; and, I think, afford fome grounds to fufpeét that the veffels of the bark, like thofe which conftitute the venous fyftem of animals, (to which they are in many refpeéts analo- gous,) may be provided with valves, whofe extreme minutenefs has concealed them from obfervation. The experiments, and ftill more the plates, of Hales, have induced naturalifts to draw conclufions in direét oppofition to the preceding. But the Plates of that great naturalift are not always taken correétly from nature; * and Plates, under fuch circumftances, however fair and candid the intentions of an author may be, will too often be found fomewhat better calcu- lated to fupport his own hypothefis, than to elucidate the fa@is he intends to ftate. The preceding peculiarities in the growth of inverted jedings appear to have efcaped the obfervation of Du Hamel ; and, as very few inftances of error, or want of accurate obfervation, * The eleventh Plate (Vegetable Staticks) is that to which, in this place, I particularly allude, will MOTION OF THE SAP. 2993 will ever be found in the works of that excellent naturalift, J Experiments muft requeft permiffion to fend you fome of the fubjeés of my ap ohn ee experiments, as vouchers for my own accuracy, the fap in tress. Of the inverted cuttings employed by Du Hamel, a {mall portion only appears to have remained above the ground; and under {uch circumftances, the different forms of thofe growing in their natural, or inverted, pofition would be {carcely. ob- fervable, It appears alfo, from his experiments, that fuch ine verted cuttings, in fublequens years, grow withas much vigour as others that are not inverted; whence we mutt conclude, that the organization of the internal bark becomes again inverted, and adapted to the pofition of the branch. The growth of fome inverted plants of the goofeberry-tree, which I obtained, many years ago, from layers, gave me reafon to draw a different con- clufion; for thefe always continued weak and dwarfifh, Ida not, however, entertain the flighteft degree of deubt, but that the affertion of Du Hamel is perfectly correét. I intended to have added fome obfervations on the repro- duction of buds and roots of trees; but thefe would neceffarily | extend the prefent Paper to an immoderate length; I fhall therefore referve them for a future communication, and con- clude with an account of an experiment which more properly belongs to the Paper I had the honour to addrefs to yo laft _ year, but which had not then fucceeded. I have ftated, in that Paper, that the leaf-ftalk, the frat. ftalk, and the tendril, of the vine, had been f{uccefsfully fubfti- tuted, in many inftances, for each other; but that I had failed in my efforts to engraft a bunch of grapes, by approach, on the leaf-ftalk ; owing, I conceived, to the operation having been improperly performed, In thofe experiments, I cut the leaf-ftalk into the form of a wedge, and made an incifion in the fruit- ftalk, adapted to receive it; but, under fuch circumftances, the leaf-ftalk (as I had proved by many experiments). has no power to generate new matter; and the wounds of the fruit-ftalk heal fo flowly, that I readily anticipated the ill-fuccefs of the opera- tion. In the laft {pring, I pared off fimilar portions of the leaf- ftalk and fruit-ftalk; and, bringing the wounded parts into contaét, I fecured them clofely together, by means of a bandage, letting the leaf remain. Under thefe circumftances, an union took place; and the fruit-flalk being then taken off below the point of junction, and the leaf-flalk above it, the grapes drew their 994 ATMOSPHERIC ELECTRICITY. Experiments their whole nutriment through the remaining part of the leaf- Sean cg tee They did not, however, acquire their full fize; and the the fap in trees. feeds were {mall, and, I think, incapable of vegetating ; but this I attribute to the want of nutriment in quantity rather than in quality; for the union of the veffels of the leaf-ftalk with thofe of the fruit-ftalk was very imperfeét. The grapes, which were the purple Frontigniac, poffeffed their mufky flavour, in the fame degree with others growing on the fame plant. There is another experiment in my laft Paper, which I will alfo notice here, becaufe it appears to lead to fome important conclufions, and had been tried only in a fingle inftance. I have there ftated, that the ftem of a young tree became ellipti- cal, by being confined to move only in the fegment of a large circle. This experiment was fuccefsfully repeated during the laft year, on other trees; but I have nothing to add to the de~ fcription which I have already given. J am, &c. TOA RNIGHT: XIV. Extra of a Memoir of Mr. Erman, entitled, Obfervations and Doubts concerning Atmofpheric Electricity *, Me. ERMAN who is already fo advantageoufly known to philofophers, has publifhed towards the end of laft year, a memoir which appears to deferve their attention in an une common degree, Signs of atmof- | When he made experiments upon the ele@tricity of the at- My ae mofphere, he obferved a great difference between the refult cording tothe prefented by an eleétrometer armed with a conduétor which inftrument, was fuddenly raifed from the earth, according to the known method, and that ofa metallic rod of much greater length which was infulated and fixed. Defcription of The ele@rometer he ufed was that diftinguifhed in the electrometer» Germany by the name of the electrometer of Weifs. The length of its leaves of gold is half an inch, and the diameter of the glafs tube which enclofes them 1s three quarters of an * Journal de Phyfique, Thermidor 12, or Vol, LIX, 98, inch ATMOSPHERIC ELECTRICITY, 995 inch in diameter, the height being an inch anda half. Its cover of ivory does not projeét above the glafs, and is per- forated in the middle with a hole in which a fmaller glafs tube is fixed,:and through this laft tube paffes the metallic rod that ferves to fufpend the gold leaves, and is upon the whole five feet in length, being compofed with feveral pieces {crewed together, in order that they may be more eafily conveyed from place to place by feparating them. A divergence of three lines in thefe leaves anfwers to two lines in the elec- trometer of Volta; and that degree of eleétricity which would produce a divergence of two lines and a half in this laft, caufes the leaves of Mr. Weifs to touch the fides of the glafs cylinder. ” Mr, Erman walked in the fields with his eletrometer, When raifed having its rod confined to the length of three feet. When he oman irr fuddenly raifed it from the ground, he obferved a ftrong divergence of plus eleétricity. When he lowered it with the fame {wiftnefs, he perceived an equal great divergence of minus. The point of a fixed metallic rod of much greater length, ereéted at the {ame fpot, did not give the leaft indica- tion of eleétricity. ; An ele&rometer placed on a poft of three feet in length, If Mowly raifed it produced no divergence; and, when it was afterwards flowly riot raifed one foot, or a foot and a half, it likewife afforded no fuddenly de- fign; but when it was very quickly brought down to the poft, ee it exhibited minus ele€tricity to fuch a degree, that the gold leaf touched the fides of the glafs. This charge was gradually difperfed in the air, or by touching the eleGtrometer with the hand * ; but by raifing the inftrument with equal {peed above the poft, a divergence of plus eleétricity of the fame ftrength was afforded which was deftroyed in the fame manner. The more infulating the air the lefs it is neceffary to raife Conduéing the electrometer in order to produce this effeét; but the longer Power of the air the point, the more ftrikingly will the effeét be thewn, even _eatie me in damp weather. A circular motion at a confiant diftance above the earth does not exhibit any eleétricity, neither does a progreflive motion upon level ground afford any change; * From this fa& it appears, that the eleé&trometer had not any flips of metal within the tube like thofe of Bennet, who firft ufed gold leaves. N, but 296 ATMOSPHERIC ELECTRICITY. but when the ground rifes even infenfibly, the phenomenon is obferved, and it is rather extraordinary, that it even affords a means of afcertaining the level,: Variations ofthe To vary the experiment, the electrometer may be placed experiments anon a low fupport, and touched with an infulated ftick or wire which has been quickly moved towards the ground, and is afierwards raifed with the fame quicknefs. The elec- trometer in the firft cafe exhibits plus ele€tricity, and in the fecond minus. It is very remarkable, that the ménus ele@tricity paffes through Zero before it changes into plus, and vice verfa, ac- cordingly as the inftrument is raifed or lowered even when there is no interval between the two motions; but the diver- gence will be more vifible, if time be allowed for the elec~ trometer to difcharge itfelf between the two experiments. Sauffure's obfer- Sauflure formerly obferved the effential requifites in this vationse phenomenon; but his ele&trometer was not fo fenfible, and he explained the phenomenon by fuppofing that the elec- trometer was the moft infulated, and the fixed rod not fuf- ficiently fo to indicate fuch flight degrees of eleétricity. Theele@trometer Mr. Erman has afcertained, that the phenomenon muft is affected not by he attributed to the manner in which the electricity is diftribut- . pe ed in bodies. The mafs of the ground exerts its influence ~ but fimply by the very fenfibly to a certain diftance, and the ele€tric atmofpheres wiginiea of Te aét upon each other without any intervention of the air, The pears to poflefs infulated metallic rod which we raife from the ground by the minus fate» boiding it perpendicularly, undergoes no other change than is owing to its own proper eleétricity, which is then lefs com- penfated by the influence of the ground. Whether the elec- trometer or the plate of an ele@cophorus be flowly railed, the electricity becomes communicated to the furrotinding air,, The termination and is not manifefled, A ball placed on the point of the rod of the conduétor of the eleGQrometer does not at all change the divergence of or even its being ( ; : enclofed in:glats, the leaves ; and even when the condu@ting rod of the elec- makes no dif- trometer is enclofed im a tube of glafs not open at the top, po coi the phenomena are the fame, and the divergencies of plus and mnus are equally feen according to the direétion of the motion. And when a fecond tube is put over the firft, for the purpofe of more exaétly preventing the conta of the air, the refults are not at all changed. 3 Mr. ti ATMOSPHERIC ELECTRICITY. 907 Mr, Erman procured a tube of glafs 14 feet long, which he A fixed rod not ; : : affe ted, becaufe covered with varnith, and through which he introduced a3j.. g uation with metallic wire which pafled above the upper part, and had regard to the the eleétrometer adapted to its lower extremity. A foal piece of amber being rubbed and applied to the upper end | of the wire, produced a divergence in the leaves. The . eleétricity of the air had not, however, any influence on this fixed, and very nicely infulated point ; which fhews, that the air furrounding a point is more adapted to deprive it of elec- tricity than to communicate if. Another ele&trometer which was raifed from the earth at the fame time produced a great divergence. Mr. Erman wifhed to know whether two bodies in the fame Two ele&trome- atmofpheric ftratum reciprocally modity their electric ftate, ea ae when their diftance is altered in either dire@ion, Two gold then horizontally leaf ele€trometers equally fentible, and armed with rods three car feet long, one of which was bended, fo that its point could cording to the be placed near that of the other eleéirometer, on the fame pe of Ritei, horizontal line were held at arms length trom each other, and oe touched with the finger to difcharge, and. put them in equili- briam with the furrounding air. They were atterwards brought towards each other horizontally, and when they were fuf- ficiently near to permit their atmofpheres to .aét on each other, there was a divergence of minus eie@tricity on both fides, which came to its maximum when the electrometers were in contact. They were agam feparated, and the divergence difappeared, both being at the ftate of Zero. One of the wires of thefe eleGtrometers was put in contaét with the earth, when the divergence of the other infulated electrometer fuddenly diminifhed to half its former quantity; a fa@ that ‘alfo proves that the whole depends upon the eledtricity ins herent in bodies, and not at all upon that of the atmofphere. When the eleétrometers were removed froin each other, Continuation of that which was touched with the finger indicated plus in a the experiment degree equal to the minus it had before fhewn. If the two eleCtrometers be touched with the finger, no further aps pearance of the minus divergence is feen in either of ihem; but if they be then feparated both will exhibit plus. Can thefe phenomena be attributed to the air? or is x pollible to avoid admitting in thefe experiments the influence of eleétric atmolpheres, and the law of the condenfer?—lIt is, therefore, well 208 The ele&tric in- fluence of a tree was {till greater. , The mutual ine . fluence of two electrometers is fcarcely feen very near the earth. Remarks on aeroftatic ex- periments pro- pofed. ATMOSPHERIC ELECTRICITY. well proved, that all bodies, even which are in equilibriam with the earth, have eleétric atmofpheres in the open air, from which retults a modification in their eleétric ftate. Mr. Erman conjeétured, that a body of a greater volume might have {till more influence. - He obferved a tree which ood alone in an open fpace. He retired to the diftance of twenty paces from it, and difcharged the eleétricity of his electrometer by touching it with the finger. He then ap- proached-the tree, keeping his ele€trometer at the fame height above the earth. The electrometer diverged negatively, and the divergence continually augmented as he came nearer, fo that the leaves of gold touched the fides of the glafs at the moment when he was under the tree. This negative ftate lafied as long as he remained there, but when he retired again it gradually difappeared, fo as-to have become infenfible when he arrived at the original diftance of twenty feet. When the communication between the point of the elec- trometer and the earth was completed under the tree, the divergence ceafed; but the ele€tricity was only apparently deftroyed, and manifefled itfelf again when he ‘retired from the tree, Two eleérometers being brought near each other at the» diftance of half a foot from the earth, did not produce this effet, becaufe the mals of the earth too greatly influenced that proximity. In order to have very fimple refults, it would be requifite to difcover fome means of rapidly elevating an infulated body to fome thoufands of feet above the ground ; and if this experiment were undertaken in the boat of a bal- - loon, it would probably be feen, that the pofitive charge would conftantly increafe during the afcent, and would be- come negative as it approached the earth: but if means could be had of changing the fyftem of the balloon in the at- mo{phere, by the intervention of another body, which would be difficult, the contrary effects might be expected. This change of fyfiem is however feen when a cloud defeends, and difcharges itfelf with explofion into the earth, But an electrometer of the ufual conftru€tion in the boat of a balloon would indicate nothing, becaufe the upper part always has a charge of ele@tricity of the fame kind as that of the gold. leaves, and of equal intenfity. If ATMOSPHERIC ELECTRICITY. 299 If the influence of the ele€tricity of the ground be fuf- Thefe effeés ficient to prevent the divergence, the fame effect ought to ee take place in every clofe chamber, becaufe a roof or ceiling &c. may be confidered as a prolongation of the ground. Hence it is that this polarity does not manifeft itfelf in a chamber ; it is alfo erroneous to pretend that the atmo{phere produces eleétricity ; and it is equally erroneous to affert, that eleéiric repulfion does not take place ina vacuum; Mr. Erman pro- pofes to eftablifh in an inconteftible manner in another me- moir, that the repulfive force of ele€tricity, as well as of magnetifm, are alfo manifefted in a vacuum. If the eleétricity of the rod of the eleétrometer could be The eleéric afcribed to that of the atmofphere, it would follow, that it "gate fhould be equally eleétric through its whole length; but if it air; for therod depend on the earth, the rod will not be equally eleérified, ee a ee . » ; ‘ ; ified through- and its different parts will be varioufly modified accordingly as out, they may be more or le{fs: remote from the earth; and this in faét is the cafe. Two eleétrometers, each having a pointed rod of three feet, one of which was twice bended in a right angle, fo as to have an horizontal portion of three or four inches before it proceeded upwards, were held im fuch a manner, that the point of the ftraight rod of the one touched the horizontal part or elbow of the other, which was lower, When they were touched, to difcharge them, no divergence was feen, but when they were afterwards feparated horizon- tally, the leaves of the lower ele&trometer diverged, while thofe of the upper were not at all moved. It is very remarkable that the nearer the contaé is made to Its fate differs ‘the upper point of the compound conduor to take its elec- 2 the contact is ie: ' ; “ae ; made in different tricity from it, the greater is the pofitive divergence of the parts of its lower eleétrometer; and if the difcharge be made very near !¢nsth. the upper point, the electrometer will indicate plus but very feebly in comparifon with that below, ‘If thefe two eleGtrometers, the conduéting parts of which Eleétric polarity. form together a length of fix feet, be raifed perpendicularly - fome feet above the earth, the plus eleétricity will be oblerved in both; but if they be feparated horizontally, the upper one will retain its divergence, and the lower will augment it fud- denly, even to double. From this it is evident that the con- duéior has not the fame charge of eleétricity through all its length, and this is precifely what is called polarity ; andas the prefence 800 ATMOSPHERIC ELECTRIGITYs prefence of the eleGtrometer is not effential in this éxperiment, we may conclude from it that each conduétor placed perpendi- cularly on the earth, has ils polarity in the dire€tion in which we have juft explained it. One extremity © This thows why an ele@rometer indicates a divergence plus a a. ee when the point is touched with the hand in the open air, and is vergence; the foon withdrawn, while there is no divergence when the lower other does note part of the wire is touched. This phenomenon is feen in Weils’s eleG@trometer, even when the wire is not more than three quarters of a foot long. Experiments on From all thts it will be feen how deceitful the experiments iis buns ad on the eleétricity of the atmofphere may be; for in the com- pneontata. mon method, the hand is direéted to be moved from the bottom upwards, towards the point of the ele€trometer, to deprive it of its accidental electricity, and it is precifely this which com- municates it to it. ‘The interven- With refpeé to the exceptions which the faéts announced ae ae eg above may be liable to, it muft be obferved that when a ftorm verfes the phe- drives a cloud over the zenith of the obferver, or when rain, ee het hail or fnow falls at the place of obfervation, the phenomena which occur are totally oppofite; the ele€irometer gives plus when it is brought towards the earth, and minus when it is re- but a continued moved from it, &c. &c. But this anomaly is only a tranfient whale ee effeét, and the pretended negative ftate of the atmofphere does by clouds does not exift, either when the rain is of long duration, or when eae eet the {ky is entirely covered with clouds; for in the latter cafe - the ele&trometer is pofitive on being raifed, as when the fky is clear. The perturbations {poken of are only momentary and Thefe changes change continually. Itis evident that thefe changes cannot be rhe athe attributed to the charge of eleétricity fet at liberty in the airs of the cloud, it is more probable that thefe maffes of clouds modify the elec- trometer by their atmofpheres, like the tree in the preceding experiment. The perpendicular conduétor may be compared to an iron bar, the polarity of which is reverfed accordingly as the fame pole of a magnet is prefented to one or other of its _and may be imi- extremities; thefe effeats of the meteoric mafles may alfo be Sera imitated by conduétors ; ; the fole motion of the hand above the point of an electrometer is fufficient to produce the negative flate in queftion, and infulation renders thefe effeéts more fenfible. | (To be concluded in our next.) SCIENTIFIC SCIENTIFIC NEWS. S01 SCIENTIFIC NEWS. Proressor DANZEL of Hamburgh made, in the be- Mechanifm for. Te é --__ directing aeroftae ginning of laft year, a fecond experiment of the mechanifm | iinet he has invented for the direétion of aeroftatic machines. He is faid to have obtained a progrefs, in a right line, of twelve feet in a fecond, which is nearly equal to three leagues in an hour, although he did not bring more than half his means into aélion., On the fame day he made an effay with another machine for the fame ufe, the refult of which was not lefs fuccefsful, He has fince publifhed the principles of his difcovery in a pamphlet, entitled, ‘‘ Bafis of the Mechanifm for the Direétion of Aeroftatic Globes, by Profeffor Danzel, of the Society of Emulation of Abbeville, at Hamburgh.” The clafs of phyfical and mathematical {ciences of the Correfpondents National Inftitute of France, in its fitting of 2d Plaviofe, in elected by ee x ; . ¢lafs of phyfical the year XII. elected the following correfponding members. and mathematical Mefirs. Leblond, engineer, returned from Cayenne; Bernard, ‘iences of the : 4 : E French national engineer and aftronomer, at Bagnols; Simons, phyfician at Jnaitate. London; Crell, German chemift; Thunberg, the fucceffor of — Linnzus in Sweden, who made the voyage to Japan; Bugge, aftronomer to the king of Denmark; Goffe, chemift at Geneva; Prouft, chemift at Madrid; Cugnoli, aftronomer at Modena; Reboul, to whom we are indebted for the meafures made in the Pyrenees; Mendoza, a Spaniard, fettled at London, known by his important works on navigation. They were all corre{pondents of the Academy of Sciences in 1793. The fame clafs has prolonged the time for receiving anfwers Prize queftions, to the following prize queftions, until the 1{t Germinal, in the year XII]. To determine by experiment the different fources of carbon in vegetables.” And, ‘ To determine by anatomical and chemical obfervations and experiments, what are the phenomena of the torpidity which certain animals, fuch as marmots, dormice, &c. experience during the winter, with refpeé& to the circulation of the bleod, refpiration and irritability 3, to enquire what are the caules ‘of this fleep, and why it is peculiar to thefe animals.” The value of the prizes is doubled, and confifts of two kilogrammes of gold, about 2331. fterling each. The aftronomical prize, inftituted by M. de Lalande, to be given to the perfon, in France or elfewhere, the members of the 302 SCIENTIFIC NEWS, Prize queftions. the Inftitute alone excepted, who fhall have made the ob- fervation moft interefting, or publifhed the memoir moft ufeful to the pfogrefs of aftronomy, was in the publie fitting of the 6th Meffidor, decreed to M. Jofeph Piazzi, Profeffor Royal of Aftronor my and Dire@tor of the Obfervatory of Palermo, for the Ore which he has lately publifhed under the title: Pracipuarum fellarum inerrantium pofitiones medic tneunte feculo XIX. ex obfervationibus habitis in fpecula Pa- normitana. Panormi, 1803, one volume in folio. The fubje& of the mathematical prize propofed by the clafs, in this fitting, is the following: To give the theory of the perturbations of the planet Pallas, difcovered by M. Olbers,” The works are to be written in French or in Latin;-and are to be received to the 1f{t Germinal in the year XIV. The prize is a gold medal weighing a kilogramme. OY are academy of fciences, literature, and ‘he fine arts of Turin has propofed the following new prizes. Clafs of Phyfical and Mathematical Sciences. Firft Prize. - The ele&tric and galvanic fluids offer fo many points of analogy, and fo great a number of different effects, that many philofophers believe them to be identical, and many others make them two diftin@ fluids : New experiments are required which fhall decide, in a definitive manner, on their identity or diverfity. Second Prize. It will be feen in the Connorjunce des tems, for the year XII. page 217, that the refraétions which are adopted do not fhow an agreement in the obfervations of the fummer and winter folftices of the years 7, 8, and 9, to give the fame obliquity of the ecliptic, as they fhould do; and it is clear that a difference, fuch as is found, of eight feconds in the refult of the calculations, not of one obfervation, or of two, but in the total of feveral, made on different days of different years, muft have fome caufe: A fatisfactory explanation is demanded. Clafs of Literature and the Fine Arts. Queftion propofed. To demonftrate whether the economical feience known by the name of Statiftics, is a new feience, and what are the advantages fates may derive from it. The prize for each -queftion is 600 francs ; and memoirs are to be received until the 30th Frimairé of the year XIII. They are to be writlen in Latin, French, or Italian, and 5 fent ¢ SCIENTIFIC NEWS. 303 fent, free of poftage, to the academy. The prizes will be Prize queftions. declared in the lait public fitting (Meffidor) of the fame year. The fociety of emulation of Colmar in its fitting of the 17th Thermidor, propoted the following fubje@ for a prize ‘of 300 francs, to be decreed in the public fitting of Meffidor, in the year XIII. ; «« 1, What are the readieft and leaft expenfive means of converting into animal oil, fuch remains of animals as have - been hitherto loft to the arts and to,confumption ? “© 2, To what arts, and to what kinds of fabrication can this produét be applied; and what preparations fhould this fubftance undergo before it is brought into commerce? «‘ 3. Finally, in an extenfive undertaking, the object of which would be to convert the remains of animals into animal oil, what precautions would be neceffary in the adminiftrative police, to prevent the public health from being injured?” The memoirs are to be written in French, German, or . Latin, and fent before the 13th Meffidor, free of poftage, to the Prefeét of the Depattment, or to the Secretary of the Society. ee Extra& of a Letter fron Mr. J. Darton, LeQurer ai ihe Royal Inftitution. Dated, Manchefter, March 12, 1805. A VERY remarkable and fingular appearance of the Remarkable aurora borealis was obferved at Manchefter from 10 to {1 in *°*° ah a the evening of Saturday the 23rd of February. The fky was almoft completely ob{cured with dark clouds, efpecially to the fouth, with {ome rain; about 60° above the horizon, on the fouth meridian, there was a {pace in which the cloud was lefs denfe, where a very ftriking vacillating flame arrefted the attention of mofi people who happened to be out. It - fometimes fhone with fuch vividnefs as to exhibit a ftream of light right down to the horizon through the thickeft part of the cloud; and at other times, the whole fouthern region was illuminated as with a flafh of lightning. The light feemed fcarcely to reach the zenith, and at breaks in the clouds to the north, no light appeared. Should this phenome- non have been obferved in the fouth of England or in France, a comparifon of the obfervations may lead us to form fome idea of the height of this and other appearances of this meteor, which occur much more rarely of late vears than formerly. To 04 To CORRESPONDENTS. THE ingenious infirument of I. S. F. for erplofions has not appeared to the Editor to be wanted. Chemical leéturers in this metropolis ufe a fmall particle of phofphorus, of the fice of a pin's head, and fprinkle upon it a pinch of the oxymuriate of pote afh, in a Wedgewood’s mortar, This fmall quantity, being firuck by a fudden rub of the pefle, gives a loud explofion with the vifible flame, but the burring maiter is too little to endanger the fpecta- tors. : The excellent perfpeive inftrument dejeribed and drawk by the Rev. Wm. Grecor, has no doubt the priority in aQual date to that of R. L. Encwortn, Ejy. deferihed in our firft Vol. page 281. But he will see, by turning to that article, that the inftru= ments are too nearly alike to admit of a fecond publication. I am-much obliged to Mr. CuMBERLAND for his favour of the 17th feb. The ufejul ohjeéts mentioned in his poftfeript ap- pear tome to be fuchas would be very acceptable to the public. I am afraid (hat the circumfance of the imventionof Mr, J. having been publifhed before would make it le/s proper to, be reprinted mm © a Journal which is hovered, with fo much or iginal matter, that prefes Jor infertion. But I hail be happy to give it a more deli- berate confideration Ys his friend will favour me with the loan of the plates, and fia paddinanal objérvations or notes,as he may think fit to make, ne The. cafe of deafnefi, communicated by Mr. H1iu of Wells, Norfolk, m.which fo much benefit wus derived from elericity, is wery interefting. Some medical cajes hace appeared in the early numbers of the firft feries of this Journal; and others prefented themjelves for my decifion as Editor with regard to-their value and importance. But in the attempt io perform this-part of my duty, I found difficulties fo great, and a fulyedct fo extenfive, that 2t appewred proper to confine the papers, to be admitted, to fuch as are dire&tly and immediately connedted with chemical and me- chanical feience. I shall be happy to convey his letter to a re- _dpetiable Medical Pousnal, af he fhould think fit. _ Lam ne Bee that the letter froma CoxnRESPONDENT, who requefied fome enquiries to be made, concerning the fundamental | expercments on heat, of the late Dr. Invine, has been fo long without its effed. I hope to be enabled to give the narrative he requefts in the next numb Tr. MU Engraved by Mutlow Rupee GL wie Me jh i | Pe a, a Poe PHUSe Torna OLN LUN SO | y Mutlow Rufsell. Co.! v Engraved é Drawn by Franas Bauer. L whe vi, OCCEIAOR: Highly magn if feed 2 Veclions re ant Liructine of Wea « Mra, = Fi ges ; aS exhibiting lhe mecwoscgpie plant 1 the Blight en Com Mutlow SaTtupiell Cot Philex.Journal. Vol. X PLXTp.304. INDEX ooeom A. ‘Accum, Mr, letter from him refpect- ing a fuppofed omiffion in his Practical Chemiftry, 214 Acid, benzvic, different methods of ob- taining, 87.—-Properties of, 88 —— laétic,'a memoir on the, 141—257- Cheniical examination of, 261 -——— lignic,~is found in peat, 213 nitric, on the direét produGion of, IO5——-214 ; Acroftatic voyage, account of an, to exa- imine the magnetifm of the air, &c. 278 Agricola, 273 Air taken at great elevations, analyfis of, 285 =~ pump, defcription of an improved, 201 Alcaiies, ation of, on refins, 245 Alcohol, aétion of, on fandarach, 246.—— On mattich, 247 Aletes on the’ reflection of cold, and in- vention of the telefcope, 92—145 Animal bodies, converfion of, into foffils, 187 a———= oil, queftions refpecting the con- yerfion of animal remains into, 303 Anftey, Mr. on the ufe of peat-afhes and duft as manure, 243 Apparatus, improvement in the con{truc- tion of Woulfe’s, x80 Afhes of péat, on their ufe as manure, 208—-Probably occafion the fpontaneous * growth of clover, 213 =—— of pit-coal, a good manure for grafs, 239 -—— of wood, contain a peculiir earth, 240 Aftronomy, ancient Egyptian hierogly- phics fuppofed to relate to, 4 Atmofphere, ‘its compofition every where the fame, 287 Vor. X. 1805, | Aurors borealis, a remarkaole, .303 Azimuth-compafs. for aeroftatic .experi- ments, 27y e049 B. Bacon, Lord, the firft who proved the incomprefhibility of water, 3-145 Banks, Sir Jof. 24—A remarkable {chif- tus found in Iceland by, 184.—-On the caufe of the blight in corn, 225 ; Barberries, commonly reputed, to occafion the blight in wheat, 230 Barometers, for aeroftatic experiments, 279 Barton, Prof. on the effet of metallic falts on vegetation, 241 Barytes, native carbonate of, § Bafalt, experiments on the gradual refrie geration of, 113-165 Bauer, Mr. 226 Baumé, i141 ‘ Beddoes, Dr. 16 Beech, abfocbent powers of the a ee of, 15 Bennet’s eleétrometer, 295 Benzoin, analytical experiments and obs fervations on, 82 Bergelius, J. B. on cerium, 10 © Bergmann, 41——~183 L% Bernard, 301 Berthollet, 237 Biddle, Mr. J. on the denfity of mercury, in its folid ftate, 253 Biot, 278 Bitumen, converfion of the proximate principles of vegetables into, 181 Blaife de Vignere, 88 Bleaching, mechod of, practifed at Salz« burgh, 126 Blight in corn, on the caufe of, 225 b Boerhaave, INDEX. Boerhaave, 41245 Bonvoifin, Dr. 53 Borelli, 147 Bofc-d’ Antic, 60 Boftock; Dr. 99 Bofwell, J. W. Efq. on the degrees of facility with which bodies change their temperatute; ‘70.——On the coriverfion "of round meafure into fquare; 153.— Obfervations on his geometrical propo- fitions, 255 Bovey-coa’, hiftory and chemical exami- nation of, 189 Boullay, his réport on ‘the artificial pro- duétion of camphor, 131 Bouvard, 280 ‘Box, abforbent powers of the charcoal of, 16 Brandé, Mr. W. his analytital experi- ments and obfervations on benzoin, 82 Breiflac, 170 Briffon, 33 Brochant, 265 Bucholz on pruffic acid and ifs combina tions, 42 Bugge, 30! Cc. Cadet, memoir oh the fuming liquor of, 6 Camphor; teport on the artificial produc- tion of, 131.—Its action on vegetables, 242 Canton, Mr. 4 Caoutchouc, fubftancé refembling it ob- tained from maftich, 247 Carbon, queftion refpeéting the fourcts of it in vegetables, 307 Carbonate of barytes, native, § — Cafeous miattet, nature of, 144 Cavallo, 42 Cavendifh, Mr. 56—237 Cerium, a néw metal, account of, 10 C. H. on the apparent enlargement of the moon near the horizon, 156° Chapta!, 48..—His method of cbtaining binzoie acid, $7 ~ Charcoal, on its property of abforbing the gafes, 12.—On the differences of, from different woods, 15.—Experiments on the faturation of, by different fubftances, 18 Chenevix, Mr. 40—268 Chomet, 131 Cinis, a peculiar earth contained in wood- afhes, 240 Circle, to find the fide of a fquare equal toa, 152 C, L. on focal images, 205 Clocks, application of fome properties of heat in the conftruétion of, 71 Clover, obfervations on its fpontaneous growth on fome lands, 213 Cluzel, 131 Cold, refle€tion of, by whom difcovered, I—92 Coik, properties of the charcoal of, 16 Corn, on the caufes of the blightin, 227 Correa de Serra, Dr. 183 Cotman, Mr. 222 Cotton; method of bleaching, 126.—Per- “nianent red dye for, 129 Coulomb, 279 Crell, 3017 Crofthwaite’s Cugnoli, 301 Cuthbertfon, Mr. 208 pendulum, 72 D. Dalton, My 20.—On the greateft denfity of water, 93.—-On a remarkable aurora borealis, 303 Daniel, Mr. 222 Danzel, Prof. his methanifm for direét~ ing aeroftatic machines; 30% Dartigues on the devitrification of glafs, and the phenomena which happen during its cryftallization, 58—89 Devy, Mr. 20—287 De Buch, 170 Délametherie, §8 Def Cimento, excellency of the works publifhed by the Academy, 2 De ee ee ee ae INDEX. De Lue, 79 Delunel, 141 Dempifter, G. Efq. 115 Defcotils, 24 Defcattes, 277 Devitrification of glafs, see Deyeux, 141 D’Hefinger, W. on cerium, 10 Dipping-needle for aeroftatic experiments, 278 Difcoveries, on the original inventors of » Certain philofophical, 1 Dolomieu, 118—166 Dryander, Mr. 82 Du Hamel, 290 Dutens, 149 Pye, a permanent red, 129 E. Earth, a peculiar one in wood-afhes, 240 Eclipticy queftion refpecting an apparent - error in calculating the obliquity of the, 302 Eleétricity, method of exhibiting that of metals without a condenfer, 42.—-Ob- fervations and doubts concerning at- mofpheric, 294.—Queftion refpecting its identity with galvanifm, 302 Eleétrometer, defcription of Weils’ ae | Emerfon, Mr. 234 Emmerling, 265 Engiefield, Sir H. C. on the orginal in- ventors of certain philofophical difco- veriesy I—-145.—-His proceffes for ob- taining a durable and fuperior lake from madder, 215 E. O. hiftorical and ele obfervations by, 145 Erman, Mr. extraé& of his memoir an at- mofpheric elericityy 294 Euler, 68—-163 Extract, colouring, of lacy properties of, 95 F. Fanjas St. Fond, £38 Ferrilite, 1X5 Flamftead, 146 Fluids, ele@tric and galvanic, queftion re- {pecting their identity or i 302 Fontana, 226 Fortin, 278 Foffils, converfion of organized bodies | in- to, 187, Fourcroy, 2 24—=48—139—141 Fuming liquor of Cadet, memoir on, 6_ Fufion, the vitreous, is meisis from that of falts, 58 G. Galileo, 3—92—146 Gallate of cerium, 10 7 Galvanifm, obfervations refpecting, 30— 56.—Difficulties refpecting the decom- pofition of water by, 106.—Queftion on its identity with ele¢tricity, 302 Gafes, on the abforption of them by has coal, 12 —— mixed, further obfervations on the conftitution of, 20 Gay-Luflac, account of his aeroftatic voy- age, 278 Geoffroy, 47—141 Geology, application of the phenomena of . the devitrification and cryftallization of glafs to, 9 . Giefe, 246 Glafs, on the devitrification of, 5889. —Cryftallizations in, 9g0o.—Revitrifi- cation of, 91 Gluten of lac, properties of the, 97 Gold, its du@ility renders it unfit for fhowing the incompre flibility of water, 2 Fe Goffe, 301 Gottling, his method of ens benzoic acid, 87 Gough, Mr. J. his stir vathests on the canftitution of mixed gafes, 20,—His experiments and remarks on the aug~ mentation of funds, 65.—His mathe- matical theory of the {peaking-trumpet, 160,—On certain properties of triangles, 234 ay, bz ~ Gouilly, INDEX. Gouilly, 281 Granite, globular, of Corfica, ftructure of, 1675 5 Gregor, Rev. W. 239 Gien, 48 -33.—His method of obtaining benzoic acid, 37 Grefict, 285 Greville, Rt, Hon. C. 4.—Letter to him on bafalt, 113-—165 Gridiron pendulums, apparatus for exa- mining, 80 Guiton, 142 H. Haas, Mr. 201 Hales, 290 : Hall, Sir James, 60—123 Harduinus, 146 Hatchett, C. Efq. his analytical experi- ments and obfervations on lacy 45-82 —93-—His obfervations on the change of the proximate principles of vegetables into bitumen, 181.—His analyfis of magnetical pyrites, 265 Hauys, 118, , Heat, its fpeedy aétion on bodies depends on their fo.id dimenfions and figure, 70 Hencke!, 273 Herrings, Dutch method of catching and curing, 223—248 Hleroglypiics, ancient Egyptian, Capote to reiate to aftronomy, 4 Hinckley, J. Efq. on the Dutch method of caiching and curing herrings;.223-— 248 Hipparchus, 146 Hoffmann, 141-~246 Homberg,: 143 Hoppner, Mr. 222 Horizontal moon, on its enlarged appear- ancey 108—-139s-——Remarks on Mr. Walker's experiments ony 1§6.—Opi-. - nions refpeéting, 276 ments, 278 — needle, for acroftatle experi- ' Huddart, Jofeph, Efqi on the-enlarzed appearance of the moon at low altitudess 137 Hutton, Dr. 167—277 Haygens’s circular pendulumy ase marks ony 3:—158 Hydro-fulphuret of cerium, . 1 Hygrometers for acroftatic experiments; 279 I, Images, focal, on the meafure Pfs 1OB—e 205 Ingenhouz, M. 23 Inftrument for drawing in penpeine in- ventor of the, 4 for making correé&t drawings from nature, 111 for meafuring the poner of gafes, 12 ~———-=—-—— a new one recommended, 22 Inftruments, a method for nautical fur~ veying without, 303 ss for aeroftatic experiments, 278 : Iridium, a new metal obtained from pla- tina, 26 K. Karften, 265 Keir, Mr. rrg—176 Kepler, 3—92—145 Kerr, Mr. 45-100 Kind, M. his experiments on the pro- duction of artificial camphor, 131 Kirby, Mr. 226 Kircher, 152 Kirwan, 16—20—115—265 Knight, F. A. Efgq. on the motion of the fap in trees, 289 aL. Lac, analytical experiments and obferva- tions on, 45—93 Lagrange, Botillon, on milk and the lace tic acid, 141—257 ' La INDEX. La Grave, 30 ; Lake, procefies for obtaining a durable, from madder, 215 Lalande, 301 Landen, Mr. 234 La Place, 281 Lavoifier, 21-271 Leblond, 301% Lehale, 141 Lemery, 47 Lepire, 279 Lichtenftein, 88 Lime, cryftallization of in glafs, 90 Linens, permanent red dye for, 129 Lifter, Ma'tin, 273. Loyfel, 90 M. Macarty, Mr. 287 _Madder, proceffes for obtaining a durable lake from, 215.—A good analyfis of, wanted, 221 Magellan’s apparatus for examining grid- iron pendulums, 80 Magnefia, fulphate of, probably not hurt- ful to vegetation, 240 Mazgnetical pyrites, analyfis of, 265 Magnetifm, does not vary at confiderable diftances from the earth, 284° Manure, on the afhes of peat as a, 208. —A good, for grals, 239 MEX Marges, 137 Margraff, 215 Mariotre, 291 Martin, Mr. 277 Maftich, experiments on, 247 Matthews, Mr. P. on fome paffages in Dr. Thomfon’s Chemiftry, with expe- riments on fandarach and maftich, 245 MCulloch, Mr. 249 Mechanifm for direéting aeroftatic ma- chines, 30% Mendelsfhon, Mr. N. defcription of his improved air-pump, 201 . Mendoza, 301 Mercury, on its denfity in a folid ftate, 253 : Metals, two new ones foundsin pkatinay 24.—Third new one. found in,,the fame, 34.—Experiments on the eleétrie | city of, 42 Mildew in corn, .on the fei of 225, Milk, a memoir on, 141--257 Miles, Dr. 189 Mitchill, Dr. extra of a letter 8m on a peculiar earth in wood-afhes, 240, Model, 137 Molyneux, Mr. 277 Montucla, 148 Moon, horizontal, on its enlarged ape pearance, 108—139.—-Remarks on My Walker's “expeniag on, 156 Morozzo, ©. L. on the abforption of the gafes by charcoal, Mortlock, Capt. ona sens and accurate method of furveying, 103 Mullery 47 | Munn, Mr. 222 N. Newman, Mr. 2223 Newton, Sir I, 18—-145—277 Nitre, its ation on vegetables, 24% — o. Odier, 16 Oil, queftions relative to the converfion of animal iemains into, 303 — of benzoing. properties of, bd Olbers, M. 302 ‘Opie, Mr. 222 Ofmium, anew metal obtained from pla- tina, 27 Oxide, fulphurated, of'cerium, 1% of zinc, native, § “{- Oxigen gas, action of charcoal.ony 12. Specific gravity cf, 20 R Palladium found in the ore.of platina, 344 —Account of the difcovery of, 204. Pallas, queftion refpe€ting'the planet, 302 Parmentier, INDEX. Parmentier, 141 Peat, on its ufe as*fuel, 207. Preneesnital * remark on, 213 Pearfon, Dr. 47.—On the ufe of ritpitiee of iron as a manure, and on the efficacy of paring and burning land, 206—239 Pendulum, ufe of a large block of ftone - yn fixing a, 72.—Imperfections of the compound, 73.—Various conftruétions of the circular, 76.—An ofcillatory or rolling, 77.—On the properties of the, 158 Pétrofilex, formation of, 166 — ' Phofphate of cerium, rr Piazzi, Mr. Jofeph, 302 Piet, M. 1—g2 Pine’s pendulum, 72 Platina, two new metals, iridium and of- mium, obtained from, 24.—-On a new metal, rhodium, found in crude, 34 Playfair, Prof. 167 Plot, Dr. 115 Porcelain of Reaumur, nature of the, 59 —123 Porphyry, formation of, 168 Portay J.P. 50 Prize wees, 30% Prouft, 268—273—g01 FruMfiate of cerium, 11 of potafh, on the poftibility of _ obtaining it purey, 32 Ptolemy; 146 ; l’yrites, compatative analyfis of ines kinds of, 271 Pyrometers, alledged defects in, whoa Methods by which they have been ob- viated, 79 Q Queftions, prize, 302 R. = Ragttone, analyfis of, 115 Ramfden, Mr. the inventor of an infru- mvent for drawing perfpeCtive, 4.—His . pyrometer, 89 * Reaumur, §9—123 ht Reboul, 307 ie ce Refin of lac, properties of, 97 Refins, the ation of alcalies on, 245 Rhodium, a new metal’found in crude . platina, 34 Richter, 279 Robifon, Prof. on fulphate of iron found in peat-athes, 242 Rouelle, 141 Rouppe, M. 14—18 Roxburgh, Dr. 45 Rutt in corn, on the caufe of the, 225 S» Sallow, abforbent pewer of the charcoal ofs, 05 Salt of peat, on its ufe asa manure, 207, ‘——Chemical examination of, 219 Salts, metallic, cn their effeéts on veges tation, 241 . : Sandarach, experiments on, 246 Sap, experiments and obferyations on its motion in trees, 289 Saron, 82 Saunders, Mr. 45 Sauffure, 287—297 Scheele, his method of obtaining bensoic acid, $7-~-141=——261 Schiftus, a remarkable, 184.—-Ansyfi of, 187 > ’ Schoerbing, M. C. ona method of bleach- ing cotton, and of giving a permanent red to cotton and linen, 126 . 4 Sculpture, an ancient Egyptian, Suppoted to relate to aftronomy, 4 Serum of milk, chernical examination of, 258 Simons, 301 ' Smithfon, Mr. 122 Sound, experiments and obfervations on, “6 Spallanzani, 169 Spar, formation of calcareous, 166 | ‘Speaking-trumpet, mathematical. theory of the, 160 ; Spectaclesy INDEX. Speétacies, letter from Mr. E. Walker on, ¢ 9243 i. Square, to find the fide of one equal to a circle, 152 StalaGites, formation of cultarédus, 166 Sratittics, queftion relative to, 302 ) Steinkaver, Mr. his account of an ancient Egyptian fculpture, 4 Stone, on the ufe of a large block of, in fixing a pendulum, 72 Succinate of cerium, 11 Sugar of milk, chemical examination of, 259 Sulphate of iron, on its ule as a manure, 206—242 of magnefia, probally not inju- rious tu vegetation, 240 Sulphuret of iron, two kinds of, 273 Surveying, a fimple and accurate method of, 103 Sylvefter, Mr. C. on galvanifm, 106 T. Table of obfervations made at different heights in the air, 283 —= of the rapidity of heating and cool- ing according to the bulle of bodies, ike T.C. B. his defcription of a fimple in- ftrument for making drawings from na- ture, III Telefcope, true era of the invention of the, 3—92—145 Temperature, on the degrees of facility swith which bodies admit of changes in their, 70.—On that at which water pofiefies the greateft denfity, 93 Tempie, Sir W. 248 Tennant, Smithfon, Efq. on two new meta's in platina, 24——240 Teffier, Abbé, 223 Theon, 146 ‘ Thenerd on the fuming liquor of Cadet, 6—141—285 Thermometers for aeroftatic experiments, 279, ——— hickneffvy Ra. Efq. his, cemarks),om galvani{m, 30 on Thomfon, Dr. 23.—Remarks on fome pafiages in his Chemiftry, 245=-27% Thunberg, 301 I. ot Torpidity of animals in winger, qveftion re{pecting the, 201 4 Trapeguntius, 146 . Sy. Trees, experiments and. PER oe on the motion of fap in, 289, ra ill Triangles, on certain properties’ of, 234 Tromfdorff, 8$,—His, experiments on che’ production of artivicial camphor, 132, iv Troughton’s pyrometer, 320. , rh J Trumbull, Mr. 222 ily ro 6 Trumpet, mathematical poner of the {peaking, 160 ue Tull, Mr. 227 : Turner, )Mr.. 222 _ Tycho Brahe, 147 Vv. Van Mons, 18 Van Norden, 14—~13 Vauquelin, 24—139——141 Vegetables, converfion of the proximate principles of, into bitumen, 181.— Queftion refpe€ting the fources of car= bon in, 301 Vegetation, prcbably not injured by fule phate of magnefia, 240,—Effets of metallic falts on, 241 Venturi, §2——136 Vitreous fufion is diftin® noe that of falts,. 58 ‘ b gARE AH, 4 Vitriol, greet, on its ifs as a manure, 206 : yea : Volta, 57 Von Troil, 188 WwW. Walker, Mr. E. on the horizontal moon, 108.—-Remarks on his experiments on the horizontal moon, 156,.—-On fpec- tacles, 243.—His remarks on the ima- ges formed by convex lenfes, 276 ' Water, Water, an ercor refpsctitz its compref- fion in a globe of gold, 2.——-Experiments ° to afcertain the temperature at which it poffeffes the greatelt denfity, 93.— Difficulties refpe&ting the ccaleiahtioes of, by galvanifm, 106 , Wart, Gregory, Efgs his obfervations on bafalt, 113-165 ' : ‘Wax of lac, properties of, 98 W. B. on an impfoved conftruétion of ‘Woulfe’s apparatus, 180 Weifs’s ele€trometer, defcription of, 294° Werner, 172 Weft, Mr. 222 W. F.C. on the dire& produétion of ni- “tric acid, 105—-214 Wheat feldom efcapes the blight if near a barberry buth, 236 Whey, experiments on, 143.—Js: not a produ ét of fermentatidn,' 257 ‘Widenmann, 265 Wilkins, Mr. 45—rox ie gl eal Wilkinfon, Mr. 30.——His galvanic iMufs trations and remarks, 56.—Objeétions to his hypothefis of galvanifm, 106 Willaume, Mr. on peat, 207 * Wilfons Mr. Wi his method of exhibits ing the electricity of metals without a condenfer, 42 Wifeman, Mr. 265 Witheringy Dr. 115 W. N. on pendulums, 79.——On the ho» rizontal moon, 13§9 Wollafton, Dr. on a new metal found ia crude platinay 34.—His letter relative to the difcovery of palladium, 204 Woulfe, improvement in the conftruction of ‘his appatatusy 180 pe Yi Young, Dr. M. 69 Ls Zinc, oxide of, native, § JNTH VOLUME, ERRATA. Pare 146, 7. 20, r. attronomicarum—147, /. 17, fidereuse-/. 25, perfpicillum—/. 4p, janfem——P, 248, 0%; 13) r cauda—ibid. r. at—/. 14, Claritudo—/. 19, Montuclas= P, 150, 4. 245 envaciates—/, 32, propagatum—id. caufam. aE ana VW. Stratford, Printer, Crgwa Court, Temple Bar. as +4 Hf tt * teh Teta teh: mii pene 35 es sisiety Hate i tae iit poesebas she2e pes" Sita i bit ee