a S - 4 eI ea, 1S s ™ i 40, si ” * 4 PHYSICAL anv LITERARY. \ Read before a SOCIETY in Epinsurcn, and _publifhed by them. VOLUME m EDINBURG H: —~-Printed for JOHN BALFOUR. M, DCC, LXx{ | | - ' { pheg et fas kot f $ sg hres Hi ‘ ' - me a u O / ' 2fuanuvidaa TIAL UNO wi boil ALL,OIC Ml | ON TE. mars. oF Az rT. Pag k HE Defcription of a new Plant; by Dr Arex. GARDEN Phyfician at Charles-town in South Carolina. I fl. A Defcription of the Matrix or Ovary of the Buccinum Ampullatum; by Roserr - Wuytrt, M.D. F. B.S. Fellow of the Roy- al College of Phyficians, and Profeffor of “Medicine in the Univerfity of Edin- burgh. 8 TI. Drawings of fome very large Bonés; by GeorceE CLERg, Efq; II IV. Obfervations on Light and Colours; by THoMAS Meuvitxe, M. A. 12 V: An eafy method of computing the Paral- laxes of the Moon; by Vi A Solution of ichalers Profiled: by Mar-. pTHEew STEWART, Profefflor of Mathema- tics in the Univerfity of Edinburgh. 116 “VII. Of the Cold produced by evaporating Fluids, and of fome other Means of pro- ducing Cold; by Dr Witttam CuLLew _* Profeifor of Medicine in the Univerfity of Glalgow. 159 ART. iv CO: Net oe ON oes. ART. pag. VIII, Experiments upon Magnefia Alba, Quick- lime, and fome other Alkaline Subftances; by Josep Brack, M.D. 172 IX. Of the Analyfis and Ufes of Peat; by Auex. Linp, Efq; 249 X. The Effects of Semen Hyofcyam: Albi; by Dr ArcHiBALD HamILton Phyfician in E- dinburgh. 268 XI, The Effe€ts of the Thorn-Apple; by Dr Asranam SwaIne, Phyfician at Brent- ford. 272 XII. The Effe&s of Mufk in curing the Gout in the Stomach; by JAMEs PRINGLE, Efq; late Surgeon to the third Regiment of Foot-Guards. $ 215 XIMf.An Account of an uncommon Effeé of antimonial Wine; by Dr James Wat- KER, Surgeon and Agent for the Navy at Edinburgh. 27 9 XIV.An obftinate Dyfentery cured by Lime- Water; by James Gratncer, M. D, Phyfician at London. 282 XV. The anthelmintic virtue of the Bark of the wild Cabbage or Bulge-water Tree; by the late Mr Perer Ducurp Surgeon in Ja- maica, Pat RESIS 3 a + SS CO UN wT oE Wee, v ant. | pag! maica, in a Letter to ALtex, Monro fenior, M. D. & P. A. 290 XVI. The Defcription of a monftrous Feetus ; by Mr Joun Mowar Surgeon at Lang- holm, in a letter to ALEx. Monro fenior, M.D. & P, A. 292 XVII, The Diffe&tion of the fame Monfter con- tinued; by ALEx. Monro junior, M. D, and Profeffor of Anatomy in the Univerfi- ty of Edinburgh. 297 XVIII. Bones found in the Ovarium of a Wo- man; by Dr Georce Youn, and com- municated to the Society by Dr Joun Bos- WELL, Fellow of the Royal College of Phyficians in Edinburgh. 300 XIX. Proofs of the Contiguity of the Lungs > and Piura; by Arex. Monro fenior, M.D. & PA. 303 XX. An Account of fome Experiments made - with Opium on living and dying Animals; by Rozsert Wuyrt, M.D.F. R.S. Fellow of the Royal College of Phyficians, and Profeflor of Medicine in the Univerfity of Edinburgh. . 307 XXI. The Hiftory of a compleat Luxation of the Thigh, in a letter to Dr Jonn RuTHER- FOORD ‘vi CO NOTCE ON T'S. ART. pag. roorp Prefident of the Royal College of Phyficians, and Profeflor of Medicine in the Univerfity of Edinburgh; by James Macxenzi£, M. D. late Phy fician at Wor- cefter. ‘ 347 XXII. Some Obfervations on the New Method of curing the Cataraé, by extracting the _ Cryftalline Humour; by Tuomas Youne Surgeon in Edinburgh. 355 XXII A Hernia from the Omentum falling down into the Scrotum; by THOMAS Li- VING STON, M. D. Tea at Aber- deen. 365 XXIV. A Child brought forth at a Rent of the Belly. 37¢ A Child efcaping at 2 Rent of the Womb into the Abdomen; by ALex. Monro, M.D.& P. A. st plas ye XXV. A preternatural Collection of Waters in the Womb with Twins; by StrerHen Fext Surgeon in Ulverftone. 374 XXVI.Hiftories of tophaceous Concretions in the Alimentary. Canal; by ALex. Monro fenior, M.D. F. R. S. and Profeffor of An- atomy in the Univerfity of Edin- burgh. a7 4 XXVII. CcanmnitEM TPs Vii ART. - pag,” XXVIII. Remarks: on. Procidentig Ant, Intuj's/- ceptio, Inflammation, and Volvulus of the » Anteftines ; by, ARexanwDer Monro fenior, oo M.D. & PA. 386 XXVIN, A‘ Hiftory of a genuine Volvulus of _ the Inteftines ; by ALEXANDER Monro -)gunior, M. D. and Profeffor of Ana- ‘tomy. 402 XXIK. A- Bickerletion of the American Yel- ‘low Fever, in a Letter from Dr Joun Linine, Phyfician at ‘Charles-town in South-Carolina, to Dr Rosert Wuytt Profeflor of Medicine in the Univerfity of Edinburgh. 404. XXX. Anfwer to an Objection againft Inocu- lation; by Esenezer Giucurist, M. D, Phyfician at Dumfries, 433 XXXI. A Propofal ofa new Method of curing obftructed Menfes; by Dr ARCHIBALD » Hamiton Phyficlin'; in Edinburgh. 440 XXXII. A Dropfy unexpeétedly cured; by Tuomas Livineston, M. D. Phyfician at Aberdeen. 444. > XXXIIL Hiftory of a Patient affected with Periodic nephritic Convulfions; by Corn« WELL vr CO Ned Ff athe ART. pag. WELL TATHWELL M. D. Phyfician at Stamford. 449 XXXIV. Hiftory of a Fever after Child-bear- ing ; by the fame. 454 XXXV. Hiftory of a Fever with bad fymp- toms; by the fame. 458 XXXVI. Accounts of extraordinary Motions of the Waters in feveral Places of North Britain, and of a Shock of an Earthquake felt at Dunbarton, 461 ESSAYS Hes. § Aes A N D OBSERVATIONS PHYSICAL anp LITERARY. - ARTICLE I, The Defcription of a new Plant; by Dr _ ALEXANDER Garpen, Phyfician at Charlefton zm South Carolina. OcTOR GaRDEN writes Dr Whytt, that, in fummer 1754, he met, about a mile from the town of New-York in . New England, with a plant, which, at firft, he took to be a hypericum, but, on exami- ning it, found it different: Upon which _hetook down its charadters, and fent them, fome days after, to Mifs Jenny Colden, (daughter to the Honourable Caldwalla- der Colden), a very ingenious young lady _ and curious botanift. In return to this, Mifs Colden fent Dr Garden the charac. ters of a plant which proves to be the fame: Tt is N° 163. of her collection; and was firft found by her, fummer 1753. Ufing W OL. 41. . A the JS 2 ESSAYS anp OBSERVATIONS the privilege of a firft difcoverer, fhe was pleafed to call this new plant Gardenia, in compliment to Dr Garden, The Defeription of the GARDENtA, fent by Dr Garden to Mi/s Colden, AN O'N’*Y M*O'S. POLYADELPHIA ENNEANDRIA. Raprx perpendicularis, in defcenfu fibras aliquot, at plures cirros, emittens, feniim attenuatur, fimplex, mollis. Cav rs fimplex, fruticofus, teres, rectus, ex alis foliorum internodiis fefqui- pollicaribus laterales emittens ra- mulos, lineam craflus, cubitum plus minus altus, cavus, annuus, glaber. Fora fimplicia, feflilia, patula, bina ex oppofito alternata, integerrima, ob- tufa, ovata, cordata in duo auricu- Ja, circa caulem fupra fe invicem expanfa, ad bafin extenduntuy, ni- tida, fuperne viridia, inferne glau- ca, rervo medio infra prominulo, pundiis lucidis Ayperzc: foliorum dimidium pol- licis inftar peiforata ‘PHYSICAL anp LITERARY. 3 licis plus minus latitudine, fefqui- pollicari fere longitudine, | PEpUNC. nunc alaris, nunc terminatrix, filiformis, femiuncialis. Caxnyx perianthium pentaphyllum perfi- {tens, foliolis linearibus, lanceolatis, acutis. CoROLL« pentapetala pallide rubra, brac- teis lanceolatis, cum calyce fitum al- ternantibus et longioribus. Stamina. filamenta novem, leviter pur- -purea, filiformia, in tria corpora ad bafin coalita. Fafciculi ifti filamen- torum, interpofitione trium corpo- rom necrariis fimilium, a fe invicem feparantur. Haecce corpora, colore funt bruneo-luteo, obtufa, crafla, breviora, receptaculo feffilia, hinc modice cava, inde gibbofa. An- therae fubrotundae, patvae, luteae. Pisriteum. Germen trigonum; ityli tres, parumreflexi, teretes; ftigma nullum, vel faltem nudis oculis im- perceptibile, _RECEPTac. parvum eee Cee, exca- vatum, 7 PERICARP. capfula oblonga, acuminata, f Hk Se obtule 4 ESSAYS anv OBSERVATIONS obtufe triquetra, trilocularis, trival- vis, tribus fulcis per longitudinem decurrentibus. SEMINA plurima, parva, obtufe cylindri« ca, receptaculo proprio per funem umbilicalem breviffimum in duo- bus ordinibus adhaerentia. 1. Hypericum inter polyadelphia polyandria collocat celeberrimus LINN Us; et optimo quidem jure: Nam, in qua= cunque re variant inter fe diverfae hujus {pecies, conftanter tamen exi- ftunt filamenta numerofa; at in hacce planta femper novem inveni- untur filamenta, et femper in tria. corpora vel fafciculos concrefcunt. 2. In hyperzco nunquam occurrunt nedfa- ria; at in anonymo femper exiftunt tria, confpicua, et ftamina ab invi= cem feparantia. 3. Germen et pericarpium’ figura fabro- tunda donantur ; at 1n anonymo uter= que triquetra forma gaudet. 4. In byperico, calyx perianth, quinque- partitum; at in anonymo, perianth. sentaphyllum. P pny Mi/s ‘PHYSICAL ann LITERARY, g_ Mifs Cotven's Defeription of the fame Plant, N° 153. GARDENIA. Cover of the flower is a cup, compofed of five lancet-fhap’d leaves continuing. FLoweER is five oval-fhap’d leaves, longer than the cup, and fpread out, CHIVEs are nine, placed in three bundles; every three are joined in one body for near half the length; their up- per parts are fine threads; they are a little fhorter than the flower- leaves. ‘The caps are roundith, There are three {mall oval-fhap’d bo- dies, of a bright red colour, placed on the /éat of the flower alternately with the bundles of chives, PistTiLy. The feed-bud (germen) is of a long ovally fhape, with three deep furrows. The /iz/es are three threads of the length of the chives. ‘The tips (fligma) are plain. © CoveER of the feed is a long oval-fhap'd ~ box, of a dark red colour, with three deep 6 -ESSAYS anp OBSERVATIONS deep furrows along it, and opening at three parts at top. Before the feeds are ripe, it contains three cells; but, when the feeds are ripe, the di- vifions feparate at the axis, and it © contains but one cell. ; SEAT of the feed is three ridges (being the infide of the three furrows of the faid box) each with two rows of feeds. SEEDS are numerous, fmall, and oval- fhap’d. RooT is fibrous; but, tho’ fibrous, the moft of them are about as thick as the ftalk ; they are white and branched ; fome of them are like fine threads. STALK grows fingle, is round and fmooth, and is branched out oppofitely from the arm-pits of the leaves. Leaves ftand thinly in pairs oppofitely on the ftalk and branches, they have no leaf=f{talks, are oval-fhap’d, a- bout half as long as they are broad, broadeft in the middle, are fmooth, have a rib along the middle, with fmall PHYSICAL and LITERARY. 7 {mall tranfparent veins extending from it towards the edges, and the edges are intire. The flowers are of a pale red colour; they ftand in clufters on the top of the ftalk and branches, and fome- times in» pairs at the arm-pits of the leaves.” This plant grows in wet ground, and flowers in Augutt. : OBSERVATION. The three chives only in each bundle, and the three oval-fhap’d bodies on the feat of the flower, together with the feat to’ which the feeds adhere, diftinguifh this plant from the Aypericums; and, I think, not only make it a different genus, but likeways makes an order which Linnzvs has not: ; . ; ART. 8 ESSAYS ap OBSERVATIONS — ArT. IL A Defcription of the Matrix or Ovary of the Buccinum Ampullatum*; dy RoBeERT WuyttT, M.D. F.R.S. Fellow of the Royal College of Phyficia:s, and Profeffor of Medicine in the Umverfity of Edin- burgh. ATURALISTs inform us that the buccina and purpure, the former towards the clofe of the winter, and the latter in the fpring, throw out a vifcid glutinous humour, which, thickening and becoming dry, forms a congeries of cells or receptacles connected together, fome- thing refembling the ¢ods of white vetch- es, and containing the nafcent buccina or purpure. ‘This congeries of cells or pods is often found upon the fhore, and fome- _times miftaken for the hardened froth of the fea, Bur * The buccizum ampullatum is that in which the her- mit-crab is found. ay wt ———— Wolk “Cabot & PHYSICAL ann LITERARY. 9 _ But, whatever may be the manner in which thefe cells are formed, the matrix, ovary or receptacle, in which the nafcent buccina ampullata are found, has fomething remarkably curious in its ftructure. Tas. i. fig. 1. reprefents the matrix, as itis called, of the duccinum ampullatum, fent me from South-Carolina by Dr Gar- den; the length of which was full two foot. aaaaa, &c, are the cells, recepta- _ cles, or pods, compofing this matrix, whole number amounted to g4. Thelfe pods, towards the extremity D, turned finaller, ABCD, a band or ligament connecting the feveral cells or pods, of much the fame kind of fubftance with the fides of the cells, but thicker and tougher. Tue pods or cells are compofed of a thin, tough, tranfparent {kin or mem- _ brane, and contain in their cavities a con- -fiderable number of {mall dbuccina, WoL. Il, B Fig. 10 ESSAYS anD OBSERVATIONS Fig. 3. fhews one of thefe cells or pods opened, that its buccina may be diftinétly feen. Fig. 4. exhibits feveral different views of the {mali duccina, all of their natural fize. tn fome of the pods or cells, I found 32, in others, only 28 ouccina: But, as towards the fmall end of the matrix the pods were lefs, and had fewer dbuccina in them, we may fuppofe that each pod might contain 25 buccma; in which cafe, the number in the whole matrix muft have béen 2350. ART. PHYSIGAL anp LITERARY. 11 Aare: Th Drawings of fome very large Bones; by Georce CLERK, Efq; ies Il. fig. 1. reprefents the /eapula or fhoulder-blade of an animal, found in a fhell marl-pit near the town of Dum- fries, of a monftrous fize, meafuring in length twenty-one inches and eight tenths, Fig. 2. isa rib twenty-three inches long, and two and two tenths broad. Fig. 3. and 4. are alfo pieces of broken ribs, found in the fame place; where the - whole or greateft part of the bones of the animal were afterwards difcovered, but loft or deftroyed by the country-people who found them. ‘As the bones defcribed are at leaft one third larger than thofe of our biggeft oxen, - or horfes, they are fuppofed to be the re- _ mains of an elk or fome other animal not at prefent an inhabitant of this country. _ THEY are juft now in the poffeffion of George Clerk. ART. 12 ESSAYS anno OBSERVATIONS ART? TY: Obfervations on Light and Colours ; by Tao- Mas M:itvii_t, M.A, * Salt CPE ink. On the, mutual Penetration of Light. 1. ¢ \¥NEofthe firft and greateft difficul- ’ ties thatoccurs in reflecting on this fubjec&, is, to conceive how itis pofliblethat light * ReadJanuary 3. and February 7. 1752. Had the ingenious author of this paper (who died De- cember 1753, atthe age of 27) lived to put the finifhing hand to it, he would, probably, have added many thinys, and perhaps retrenched fome others, by which it would have been rendered fill more deferving of the approbation of the public. Mr Melvill uled to oblerve, that as, of all Sir Ifaac Newton’s difcoveries, thofe relating to light and colours were perhaps the moft curious; it was fomewhat remarkable, that few, it any, ot his followers had gone one ftep beyond him on thefe fubjeéts, or attempted to com- pleat what de had left unfinifhed. Our author, therefore, prepofed to have applied himielf particularly to the fur- ther iilufration of the theory of light and colours. The following eflay is a {pecimen of what might have been ex- pected from him, and fufficiently fhews the uncommon ge; nius of its author, \ AKG SS MQ “ _ PHYSICAL anv LITERARY. 13 light can move thro’ light in all imagi- nable direCtions, without occafioning the leaft perceivable confufion or deviation - from its reétilinear courfe. Many have been induced, from this confideration, to believe it incorporeal; and all who have thoroughly ‘weighed the difficulty, have feen the neceflity of afcribing a fubtility to itincomparably greater than weare led, by any phenomena, to afcribe to any other {pe- cies of bodies in nature. There is no phy- fical point in the vifible horizon which does not fend rays to every other point; no {tar in the heaven which does not fend rays to every other ftar: The whole hori- zon is filled with a fphere of rays from every point.in it; and the whole vifible univerfe, with a {phere of rays from eve- ry ftar. | In fhort, for any thing we know, there are rays of light joining every two phyfical points in the univerfe, and that in contrary dire€tions; except where o- paque bodies interveen. 2. THOsE who fuppofe that light is nothing elfethan vibrations or pulfes pro-~ _ pagated through a fubtile elaftic medium - from ig ESSAYS anv OBSERVATIONS from the vifible object to the eye, may perhaps remove the difficulty by afcri« bing a fuflficient minutenefs to the parti- cles of that medium; fince we fee, by ex- perience, that found in the air, and waves in the water, are conveyed in different directions, without fenfibly interfering: But, as that hypothefis feems infupport- able on other accounts *, we mu‘ endea- vour to accommodate our folution to the only other conception we can frame of it; namely, that of particles aétually projected from the luminous body. 3. Iv is manifeft, that, though the mere fubtility of the particles of light may tend to account for its eafy paflage, in all directions, through denfe tranfpa- rent bodies, it will not ferve to explain ‘its eafy paflage through other light equal- ly fubtile: But, for this purpofe, it feems neceflary to fuppofe light incomparably rare when at the denfeft ; that is, that * Newtcni principia, book 2, prop. 41. and 42. Seealle Newton's optics, query 28, the py PHYSICAL ann LITERARY. rs the femi-diameters of two of the neareft particles in the fame or in different rays, foon after their emiflion, are incompara- bly lefs than their diftance. | 4. Let us confider a little the courfe obs particleof light from any of the remoter fix- ed ftars to the human eye; for inftance, from the {mall one called the Rider in the tail of the Great Bear: The particles by which we fee that ftar, have, in the firft place, paffed thro’ the fpace furrounding it, in which there are probably feveral planets revolving, and which mutt be therefore fo filled with a {phere of rays from each of them that they may be vifible to aneye any where fituated in thofe {paces ; after that, they have paffed laterally thro’ the:whole torrent of light flowing from the ftar of the fecond magnitude which we fee befide it; and laftly, they have pafled likeways acro{s the whole ocean of the folar light, and all that light with which the {pace fur- rounding the fun is filled from all the co- mets, planets, and fatellites; and befides, _in every phyfical point of their numerous journey from the Ader to our eye, they have | 16 ESSAYS snp OBSERVATIONS have paffed thro’ rays of light dlowwiide in all directions from every fixed ftar in the vifible univerfe: And yet, during the whole, they have never juitled againft one parti- cle of light ; otherways they could not have arrived in their true direCtion to our | eye. This reflection cannot fail to fug- gefta general notion of the rarity and te- nuity of light, far furpaffing all the fup- pofitions which are ufually made about its | gs. THe chance which any one body has to juftle with others of like magni- tude, is leffened in proportion to the bulk of the bodies with refpect to the {pace in which they move. It muft be therefore fuppofed, as we mentioned above, that the diftance of the neareft particles, flow- ing in the fame and in different lines, muft exceed their diameter, not indeed infinite- ' ly, but a number of times utterly incom> parable with all our ordinary numbers, in order that a particle may efcape in’ one phyfical point of its progrefs: But, that it may pafs freely on thro’ the whole diftance of the remoteft fixed ftars, it is evident, that PHYSICAL anp LITERARY. 17 that this proportion of excefs muft be multiplied by a number again incompara- ble. But this excefs, fo increafed, mutt be raifed to a power whofe exponent isa num ber equal to the number of all the fixed ftars, planets, and comets. And, laftly, +f there is an elattic medium diffufed thro’ the mundane fpace, as the propagation of heat * and many other phenomena feem to infinuate; this laft number muft be at leat doubled, if we would exprefs the pro- portion in which the diftance of the near- eft rays exceed the diameters of their par- ticles: And yet this diftance of the neareft rays, flewing from the fame centre, is fo incomparably below our fmalleft mea- fares, that there is no poffibility of defi- +, Uh , ey 4 . ning it. 6. Hap Euler confidered this extreme ra- rity, as well as tenuity of light, which mutt be acknowledged by all who fuppofe that its particles are actually projected from the lucid bedy, he would not have alledged, that this opinion is inconfiitent f x Il. C : with * Nevit. Opt. queries, ad jin. 18 ESSAYS anp OBSERVATIONS. \ with the freedom and perpetuity of the celeftial motions *. 7. Some have thought, that, if the par- ticles of light repel one another, theirmu- tual perturbation may be prevented: Bac the contrary is manifeft upon the leaft re-, fle&tion ; for tho’, by that means, the par- ticles might be prevented from ftriking, they muft inftantly turn one another from their rectilinear courfes, as foon as they come, in different directions, within the reach of their mutual powers. "Thus, we find by experience, it is impofhible to make’ one ftream of air penetrate another with- out confufion ; for-thetwo ftreams either unite into a common one \with an inter~ mediate direction, or produce irregular eddies. 8. HERE, by the bye, we may feethat the ingenious fyftem of Bofcovich, the Roman profeffor, concerning the elements of matter +, whatever may be faid for it froin other confiderations, gives us no af- fifta nce * See his Nova theoria Jucis et colorum. + See his Differt- de lumine et de viribus vivis, / PHYSICAL anp LITERARY. 19 Giftance in comprehending the mutual! pe> netration of light; for indivifible points, eadued with an_ imfuperable repulfive power, reaching toa finite diftance, areas fubject to interfere, as folid particles of a finite magnitude, Bho f.. U. On the Heating of Bodies by Light. g. Ir appears, by Sir Ifaac Newton’s ex- periments on the inflexion of light, that bodies act upon it at fome diftance; and that the fame power, varioufly exercifed in various circumftances, is the caufe, like- ways, of refraction and reflection. We know no inftance of any kind of attrac- tion or repulfion in mature which is not mutual; we obferve lik=wife that bodies ‘are heated by the influence of the fun’s rays: It is therefore natural to look upon this as the effect of the reaction of light upon bodies, and that, at a diftance from iRhern 5 ; for there is no reafoa to think that light no ESSAYS ann OBSERVATIONS light produces heat by adually ftriking the folid parts of bodies, after we are {atis- fied that bodies produce the refleGion and refraction of light, without fuffering it to come into contact with them 10. From thefe principles it follows, that light, in pailing out of one medium into another of different denfity, muft al- ways produce fome degree of heat; be- caufe it is partly refracted and reflected at the common furface: Secondly, that, in pating forwards through the fame ho- mogeneous or perfectly tranfparent me- dium, it can produce no heat ; becaufe there is no reflection or refraction, no influence of the body upon the light, but every ray purfues its own right-lined courfe, as if it moved in a perfect void*. 11, HENCE it appears, that, in water, glafs, and other tranfparent mediums, which are warmed by the fun’s rays, the heat muit ¥ Sir Ifaac Newton, in the third book of his Principia, where he dijputes concerning the tails of comets, lays it Cown as an obvious principle, Quod radi: folis non agi- tant media quae permanant, nifi in refiexione et refrace vione. : PHYSICAL anp LITERARY. 21 muft be propagated from their furfaces to- ‘wards their central parts *. 12. Hence likeways we underftand why opaque bodies are fooner heated by the fun-beams than tran{parent. ones; fince there are innumerable reflections land refractions within their fubfiances, ° befides what happen in common with *' franfparent bodies’ at their fuperficial parts. As each colorific particle of an o- paque body, by the reaction of the parti- cles of light, muft be fomewhat moved when the light is refleCted backward and forward between the fame particles, it is manifeft thatthey likeways muft be dri- ven backward and forward with a vibra- tory motion ; and the time of a vibration will be equal to that which light takes in moving through a particle, or from one particle of a body to another adjoining, This diftance in moft folid épaque bodies cannot be fuppofed greater than +z$55™ * I have found, by repeated trials, that the heat of water in deep lakes decreafes regularly from the furtace downwards, 22 ESSAYS anp OBSERVATIONS ofan inch, which {pace a particle of lighr deferibes in.23-eoe ties ee ee ee cond, With fo rapid a motion therefore may the internal part of bodies be agita- ted by the influence of light, as to per- form 125,000,000,000,000 vibrations or more in a fecond of time! The arrival ef different particles of light at the furface of ‘the fame colorific particle in the fame or different rays, may difturb the re- gularity of their vibrations, but will e- ~ vidently increafe their frequency, or raife ftill minuter vibrations among the parts which compofe thefe particles; by which means the inteftine motion becomes more fubtile and thoroughly diffufed. If the quantity of light admitted into the body be increa‘ed, the vibrations of the parti- cles muft likeways increafe in magnitude and velocity: Till, at laft, they may be fo violent as to make all the component par- ticles dafh one another to pieces by their. mutual! collifions: In which cafe, the co" lour and texture of the body muft be de-. Qroyed. Thus may we form, from known prin PHYSICAL anp LITERARY. 23 principles, fome imperfect conception of - the manner in which bodies are heated and’ burnt by the aétion of light: More than an imperfect notion of thefe fecret operations of nature is not to be expect- ed; for they certainly depend, in great meafure, upon laws and principles utterly unknown to us. _ 13. Ie one beam or ray of light, by paf- fing ftraight onwards through the fame pellucid fubftance, can communicate no heat to its internal parts, neither will the greateft quantity of rays, though crowded into the narroweft {pace, by crofling one another. From hence it follows, that the portion of air which lies in the focus of the mott potent /peculum is not at all affected - by the paffage of light through it, but continues of the fame temperature with the ambient air; although any opaque body, or even any tran{parent body den- fer than air; when put in the fame place, would be intenfély heated in an in- flant. 14, THs confequence, evidently flow- _ ing from the plaineft and moft certain princi: 24 ESSAYS anp OBSERVATIONS principles, feems not to have been rightly underftood by many philofophers *: for which reafon,! thought it might be worth while to fay fomething in explication of it’ The eafieft way to be fatisfied of the matter experimentally, is to hold a hairor down immediately above the focus of a lens or fpeculum, or to blow a ftream of fmoke from a pipe horizontally over it; for, if the air in the focus were hotter than the furrounding fluid, it would continual- ly afcend upon account of its rarefaction, and thereby fenfibly agitate thefe flender bodies.* Or a /exs may be fo placed as to form its focus within a body of water or fome other tranfparent fubftance, the heat of which can be examined from time to time with a thermometer: But care muft be taken in this experiment to hold the lens ; * See Boerhaave element. chem. tom 1. on fire, co- roll. 5. after exper. 14. and coroll. 1. and 7. after ex- per. 17. See Rutherforth’s fyftem of natural philofophy, prop 366, of the aftronomical part; and Nolet legcns de phyfique, tom 4. The filence of moft phyfical’ wri- ters, concerning this paradoxical truth, makes it proba ble that they were unacquainted with it. ‘ PHYSICAL axp LITERARY. 25 lens ag near as poflible to the tranfparent body; left the rays, by falling cloffer than ordinary on its furface, fhould warm it more than the common fun- beams. . | 15, Ir is well known that the rays of light, by paffing obliquely thro’ our at- mofphere, are inflected into a curve by the continued infraction arifing from the con tinual increafe of its denfity; therefore they muft produce fome degree of heat in every part of their progrefs through it {N° 10.]. But, as the whole fucceflive refraction is juft equal to the fingle re« fraction that would be made in pafling at once from celeftial fpaces into a medium as denfe as the loweft part of our atmo- {phere *, and all the fucceflive reflexions that can be made from every different fratum, are but equal to what would be made at once from the furface of a medi- um of the fame denfity ; it eafily appears, by comparing the denfities of air and wa- ter, and their refpective figns of refrac- .. Vou, IL. D tion, i * Newt. Opt book 2, part 2. Prop. 10% \ 26 ESSAYS AND OBSERVATIONS tion, that all the refraCtion and reflexion which the whole depth of our atmofphere produces is mach lefs than what happens - at one furface of water ; and confequent- ly, the heat produced in our atmofphere, by the immediate action of light upon its mutt likeways be much lefs than what is raifed in water. ‘The air feems to have the greateft part of its heat communicated ° to it from the opaque vapours which float in it and the general furface of fea and land to which it is contiguous. Boe CP ae ee On the filver-like Appearance of Drops of Water on the Leaves of Colewort. 16, IT is common to admire the volu- bility and luftre of drops of rain that lie on the leaves of colewort and fome other vegetables ; but no philofopher, as far as I know, has put himfelf to the trouble of explaining this curious phenomenon. Up- on infpe@ing them narrowly, I find, that the PHYSICAL anv LITERARY. 27 the luftre of the drop arifes from a copi- ous reflexion of light from the flattened part of its furface contiguous to the plant: I obferve further, that, when the drop rolls along a part which has been wetted, it immediately lofes all its luftre; the green plant being then feen clearly thro’ it: whereas, in the other cafe, it is hardly to be difcerned. 17. From thefe two obfervations laid together, we may certainly conclude, That the drop does not really touch the plant when it hasthe mercurial appearance, but hangs in the air at fome diftance from it, by the force of a repulfive power; for there could not be any copious reflexion of white light from its under furface, un- . lefs there were a real interval between it _ and the furface of the plant *, [See Tas. ji. Fig.2-] ; Pe * Newt Optics, query 29, Let AB, Tas, iii. Fig. 4. reprefent the extremity of , any repulfive body immerfed in water, for inftance a flice of colewort leaf, CL, and DM, the convex {urfaces of _ Water immediately furrounding it, and CD perpendicu- Jar 28 ESSAYS anp OBSERVATIONS 18. Ir that furface were perfectly fmooth, the under furface of the drop would be fo hikeways; and would therefore ihow an_ image 5 Jar to AB, the common tanzent of thefe curves, which will be the continuation of the general furface of the wa- ter. The forces with which any two particles, E and F, are prefled by the water in the dire@ions EG, *H perpea- cicular to KB, are known to be as K% and KH, and the repulfive powers which balance them muft be in the fame proportion. ff therefore the relation between the ordi- na‘e and abfcifs in the curve DM could be any way found by experiment, the law of the repulfive power might be determined, upon fuppofition that the particles are influy enced by no force but the repulfive power of the line KB- and the gravity of the fuperincumbent fluid ; but their mutual attraction, which tends to leffen their lateral cen- dency, muft be likeways taken into the account in order. to an exaét determination. Before I Jeave this fubjed of attragtion and repulfion, J beg leave to propofe to the Society, the f{pontaneous motions of light bodies on the furtaces of fluids, as_a thing worthy of being inquired into 3 for, though it be manifeft in general that they depend upon the different figures of the furface, it is far from being an ealy matter to explain the particular cafes by mechanical or hydrofta- tical laws. The following account of the phenomena may be nfeful towards fuch anenquiry. Ca/e1. Suppofe a fluid which is attracted to the fide of its containing veflel, and confequently ts eleyated, at the fides, into a concave furface: PHYSICAL avy LITERARY, 29 image of the illuminating body by ree flexion, like a piece of polifhed filver: But, as it is confiderably rough and unequal, * ei forface: If a body be immerfed which attraés the fluid, and is therefore furrounded likeways with a concave ele- wation of the fluid; as foon as the two elevations begin to join, the body will move towards the fide of the vel- fel with an accelerated motion. Cafe 2. Suppofe a fluid which is formed into a convex furface, either by the re- pulfive power of the containing vetlel or cohefive force of its own particles : if a light body be immerfed which attraéts the fluid; as foon as its furrounding elevation begins to join with the lateral depreflion of the fluid, it will begin to move towards the middle of the veflel ; and, it it be brought by force towards the fide, it will recede from it again witb an accelerated motion, In both the firft and fecond ca/es, if the attra@ing bo- dy be held faft, and the whole fluid made eafily move- able with its containing veffel, it will remove to or from the attracting body in the fame manner as the attracting body did with refpec to it; ze. in the firk cafe, the whole fluid will move fo that the attracting body may come to its edge; and, in the fecond, fo that it may re- cede from it. Ca/e 3. If, in-a fluid which is attracted by the fides of its veffel, a body be immerted which re- pels the fluid, and is therefore furrounded with a ditch or convex depreffion of the fluid; as foon as that depref- fion begins to join the elevation of the fluid at the fides, it will recede towards the middle; and, if forcibly brought to the fide of the veffel, will fly trom it with : aa 30 ESSAYS anp OBSERVATIONS the under furface becomes rough like- ways; and fo, by refleAling the light co- pioufly in different directions, affumes the an accelerated motion, Cafe 4. If, ina fluid which is . formed into a convex furface at the fides, a repelling body be immerfed; as foon as its depreflion begins to unite with the lateral depreffion of the fluid, it will move towards the fide with an accelerated motion. In thefe two laft cafes, the fame obfervation holds as with refpect to the frft and fecond, viz. that the whole fluid will move with correfpondent motions by the force of reaétion, if the repelling body. be held fait. Cafe 5. If two bo dies be immerfed in a fluid, which each of them attracts; as foon as their elevations begin to join, they will ru(h towards one another with equal forces and accelerated motions, and continue to adhere together. Cafe 6, If two bodies be immerfed in a fluid which they repel; as foon as the two depreffions that {urround them begin to interfere, they will likeways rufh together with an acce lerated motion. Cafe 7. It two bodies be immerfed ina fluid, the one of which attracts and the other repels it 5 as foon as the depreffion furrounding the one begins to join with the elevation of the other, they will mutually fly from each other. Lafily, if a body be immerfed in a fluid wh-ch it attracts in one part and repels in another, it will approach to or recede from other bodies and parts of the fluid, differently according to its tituation, by the rules above laid down. The different figures afcribed to the furface of the wa ter in thefe feveral cafes are plainly difcernible by the fight; PHYSICAL anv LITERARY 32 the refplendent white colour of unpolifh- ed filver. 19. AFTER fight; If the experiments are made with candle-light, they are diftinguifhed by the fhadowy or luminous rings’ which they project on the bottom of the veffel, according as they are convex or concave, Some writers have been fo inattentive as to afcribe the: motions in the frft cafe to an immediate attraétion be- tween the fwimming body and the fide of the veflel, See Helfkam’s Lectures, Betore 1 had obferved the fourth cand fixth cafes, 1 thought the phenomena might be alk v explained from this principle, that the light bodies al- ways tend tothe higheft parts of the water. It has been fuggelted to me by fome, that this tendency, combined with the greater or lefler immerfion of the bodies, upon account of the ring of water which they elevate or de- _ prefs, may produce all the different cafes ; and by others, that the whole is explicable from the fingle principle of attraction between the parts of water which caufes two drops to run into one. I believe it will be found, on due confideration, that none of thefe accounts is heiduabry ‘ But there is no reafon to defpair of coming to the bot- tom of thefe p/enomena; fiace other motions of a like _ kind have been fuccesfully explained. Thus the running of a drop of oil towards the concourfe of two glafs-planes, and the motion of a bubble on the furface of liquors, when the glafs is held obliquely towards that point where the glafs is inclined to the liquor in the fmalleft "angle, are eafily underflood from the diregion of the _ Sompound force with which the drop and bubble are acted, 32 ESSAYS anv. OBSERVATIONS. . 19. AFTER it is thus proved by an op- tical argument that the drop is reaily not in contact with the plant which fupports it, we eafily conceive whence its wonder= ful volubility arifes, and why itleaves no tract of moifture where it rolls. 20. From the like reafoning, we may conclude, That, when a {mooth needle is _madeto fwim, it does not any where touch the water, but forms around it, by its repul- five power, a ditch or bed, whofe concavity is much larger than the bulk of the needle. [See Tas. ili. Fig. 3-| And hence it is eafy to underftand how the needle fwims upon a fluid lighter than itfelf; fince the quan- tity of water, difplaced by it, may be equal to the weight of the needle. Phenomena of this kind, inftead of being reduced to hydroftatical principles, are commonly at- tributed to the mere tenacity of water, and even ufed for meafuriug its cohefive power. See Muf[chenbroeck, Elementa Phyf- £e5. 21. Tus inftance furnifhes us with a juft and neceffary correCtion of the com- mon hydroftatical law, That “the whole “ fwimming PHYSICAL ann LITERARY. 33 “ fwimming body is equal in weight to a ‘ quantity of the fluid whofe bulk is equal “to that of the part immerfed:’’ For, to comprehend this, as well as all ordinary cafes, it fhould be faid more generally, That “ the whole weight of the fwim- ** ming body is equal to the weight of the “ quantity of the fluid difplaced by it.” (22. THEsE Phenomena appeared to me worthy of obfervation here, both becaufe they fhew the fertility of optical principles in leading to the knowledge of things o- therways inacceflible, and becaufe they exhibit a clear fpecimen of a repulfive power, fimilar to that which we fuppofe _neceffary for the reflexion of light from the anterior furface of a denfer medium, Nor do I fee how it is poffible to account - for the fufpenfion of the drop in the air by comparative attractions; into which _ fome other appearances of repulfion have F been, perhaps, not unfuccefsfully,. refol- _ved*, Vou.I. EB Sik CT, . * See Jurin on capillary attra@ion, at the end of - Cotes’ hydroftatical le@ures. 34 ESSAYS Anp OBSERVATIONS DB hoa Bom ee On the Change which coloured Bodies under- go in different Lights. 23, S1r Ifaac Newton has abundantly proved, by a variety of arguments, that. the ordinary colours of natural bodies a- rife folely from the compounded colour of thofe rays which they reflect; their colour being denominated by the fpecies of thofe primitive rays which they reflect in great- eft plenty: But this part of the Newtonian doétrine will receive further confirmation by examining the different colours which © the fame body affumes when illuminated by different lights; and which may be called, in diftinétion from the former, their extraordinary colours. 24. Bop1ks of all the principal colours, viz. red, yellow, green and blue, are very little altered when feen by the light of burning {pirits: But, if falts becontinual- ly PHYSICAL ann LITERARY. 35 ly mixed with them during the burning, different changes enfue. 25. WHEN fal ammon. potath, or alum are infufed, the colour of red bodies ap- pears fomewhat faded and dirty: Green and blue appear much the fame as in can- dle-light ; both being faint and hardly diftinguifhable: White and yellow are {carcely at all affected. 26, WHEN nitre or fea-fale are plenti- fully mixed with the burning fpirits, and the whole is ftirred about brifkly ; the brighteft red bodies, feen by the light _ then emitted, are reduced to a dirty tawny brown, that feems to have nothing of red- nefs init: Green is transformed into ano- ther fort of brown, only diftinguifhable from the former by a certain inclination to a livid olive-colour ; when nitre is mix- ed with the fpirits, one may full fee fome remains of a greenifh colour, unlefs it be _ poured iv very plentifully: Dark blue is hardly to be known from black, except _ that it appears the deeper black of the two: - Light blue is changed into a very light _ brown of a peculiar kind: White aflumes. a 36 ESSAYS anp OBSERVATIONS a livid yellowifh caft: And yellow alone appears unaltered and extremely lumi- nous. Thefe experiments I made with dif- ferent forts of rich-coloured bodies, as filks, cloths, and paints. Polifhed copper, which has contracted from the air a high flaming colour, is reduced by the fame light into the appearance of yellow brafs ; the faces and hands of fpectators appear like thofe of a dead corpfe; and other mixed colours, which have red or green in their compofition, undergo like chan- ges. 27. Havine placed a pafte-board with a circular hole in it between my eye and the flame of the fpirits, in order to dimi- nifh and circum{cribe my object, I exami- ned the conftitution of thefe different lights with a prifm, (holding the refract- ing angle upwards) and found, that, in the firft cafe [N° 25.], when fal ammon. alum, or potafh fell into the fpirits, all forts of rays were emitted, but not in e- qual quantities; the yellow being vaftly more copious than all the reft put toge- ther, = _ ees a see aes PHYSICAL anno LITERARY, 37 ther, and red more faint than the green . ‘and blue. 28. In the light of fpirits mixed with nitre or fea-falt, I could {till obferve fome - blue, tho’ exceflively weak and diluted: With the latter, the green was equally faint; but, with the former, pretty co- pious. But, when either of thefe falts were ufed, I could hardly fee any veftige of the red at all, at leaft when they were poured i plentifully, and the {pirits con- ftantly agitated. At every little intermif- fion indeed the red rays would fhow them- felves very manifeftly below the hole, and red bodies feen by that light refumed fomewhat of their ordinary colour: And it was very entertaining to obferve how both would evanifh again at once, as foon as the falting and ftirring were renewed. THE proportion in which the bright yellow exceeds the other colours in this light, is ftill more extraordinary than in the former: Infomuch that the hole feen through the prifm appears uniformly of this yellow, and as diftin@ly terminated as thro’a plain glafs ; except that there is adjoining 38 ESSAYS AnD OBSERVATIONS adjoining to it on the upper fide a very faint ftream of gfeen and blue. White bodies illuminated with it, appear alfo thro’ the prifm perfectly well defined ; both which are very furprizing phenomena to thofe who have been accuftomed to the ufe of the prifm in other heterogeneous lights, where it never fails to throw con- fufion on the extremities of all vifible ob= jects. 29. Because the hole appears thro’ the prifm quite circular and uniform in colour, the bright yellow, which prevails fo much over the other colours, muft be of one determined degree of refrangibili- ty; and the tranfition from it to the faint- er colour adjoining, not gradual, but im- mediate. 30- UPON examining foap-water-films in the fame light, I could only obferve luminous bands feparated by dark ones; the green and blue being too weak to af- fect my eye in this view. It would be needlefs labour to enter here into a parti- cular detail of the reafons of the different transformations of coloured bodies, above related > », ELE PHYSICAL anp LITERARY. 39 related [N° 24. 25. and 26.]3 fince, in general, it is evident enough, that they are owing to the different compofitions of the lights with which they were illumina- ted: The experiments with the prifm [N° 27.28.] are of themfelves a fufficient com- mentary upon the reft. Si G: Ta Vv. A Remark on EULER’s Nova Theoria Lucis et Colorum, 31. EuLER, in that treatife, (publifh- ed lately along with fome other tracts, un- der the title of Opufcula Mathematica), en- deavours to amend the Huygenian hypo- thefis of vibrations, and fupport it againft the objections which made Newton and his followers reject it: Wefhall not enter here upon the difcuffion of that queftion; as it would require a difcourfe of con- fiderable length; and the rather, that the Newtonian theory of light and colours depends not on any particular hypothefis with 40 ESSAYS snp OBSERVATIONS with refpect to the intimate nature of light (in like manner as his fyftem of u- niverfal gravitation is independent of all hypothefes concerning the caufe of gra- vity). In his optics, he lays down his ‘difcoveries at full length, without ever in- quiring whether light confifts in vibrati+ ons propagated through a fluid, or of par- ticles projected in ftraight lines from the luminous body: And, in his queries, where he touches this matter *, he feems to be more pofitive in rejecting the hypothefis of vibrations, than in eftablifhing any o- ther. 32. BuT Euler likeways advances a new notion with refpect to the origin of co= lours in opaque bodies, which is intirely inconfiftent with the principal part of Sir Ifaac Newton’s doctrine. He fuppofes, that coloured bodies reflect the fun’s in- cident white light from their anterior fur- face; but, that the particular fpecies of light, by which they appear coloured, is properly emitted by the parts of the body: For inftance, he imagines that vermilion does * Newt, Opt, quer, 28, and 2¢, PHYSICAL anp LITERARY. 41 does not appear red by a more copious reflettion of red than of other incident rays, but by the new emiflion of red rays ' from the particular velocity of vibration ‘which its elaftic parts are capable of con- ceiving by the impulfe of the incident light. 33. IT is a fufficient AS of this fyftem, that no phaenomena proye or re- quire its exiftence:' Whereas Newton’s theory not only folves the phaenomena, but is directly drawn from a multitude of ex- periments. According to Fuler’s hypo- thefis,a body of one colour, placed in ho- mogeneous light of another, ought not to appear of the colour of the light, but ofa middle one between that and its own natu- al colour; which is contrary to experi- ence™. 34. Ir it fhould be Et That none of the incident light is capable of qualifying the body for emitting its proper colour, but rays of the fame colour, that which he calls new light emitted will be, in his Vou. Il. F fcheme, * Newt, Opt, book 1. part 2. prop, 10. ' 42 ESSAYS anp OBSERVATIONS fcheme, more properly incident light re- flected. 35. THE chief or only fact which feems to have led him into that opinion, is, that there are many coloured bodies, fuch as metals, which are capable of receiving a fine polifh; and therefore of reflecting regularly the images of other objects, and at the fame time retain their proper co- lour by which they are feen in all pofiti- ons. That light by which we fee in them the images of other objects, he acknowled- ges to be incident light properly reflected 5 but the other, he fuppofes, is properly e- mitted from the colorific parts of the bo- dy. But what neceflity is there of recur~: ring to this fuppofition, when we know, previoufly, that the component parts * of all opaque bodies are tranfparent; that, from every tranfparent body, there is a double reflection; part of the incident light being reflected at the firft furface, and a part of what pafles thro’ the firft, reflected at the fecond? And when we know, * Newt, Opt. book 2. part 2. prop: 2. PHYSICAL ann LITERARY. 43 know, further, that very thin bodies, (as foap-bubbles, Mufcovy-glafs, and air in a fracture of glafs or ice, or between two lenfes), while they reflect fome rays of all colours from the firft furface, reflect only particular colours at the fecond*? Do not thefe facts lead us naturally to fup- pofe the firft fort of light to be only a part of the incident light refleéted from the firft furface of the body ; and the fecond, a part of what had paffed on, reflected from the pofterior furfaces of the fuperfi- cial particles? AG Oy toa) & Concerning the Caufe of the different Refran- gibility of the Rays of Light +. _ 36. IN order to account for the differ- ent refrangibility of the differently-colour- * Newt. Opt, book 2. part 3, prop. 12. Ke | 5B Although the doétrine contained in this feftion has t “been already publifhed in the Philofophical tranfa@ions for 1753, (vid: vol, xlviii, part 1. p. 262, &c.), having : been 44 ESSAYS anp OBSERVATIONS ed rays, Sir Ifaac Newton * and feveral of his followers have fuppofed, that their par- ticles are of different magnitudes or den- fities: But, if there be any analogy be- tween gravity and the refractive power, it will produce equal perpendicular veloci- ties in all particles, whatever their mag- nitude or denfity be; and fo all forts of rays would be ftill equally refrangible. 37- Ir feems therefore a more proba- ble opinion, which others have advanced, that the differently-coloured rays are pro- jected with different velocities from the luminous body: The red, with the great- eft ; violet, with the leaft; and the inter- mediate colours, with intermediate degrees of velocity: For, upon this hypothefis, it is manifeft, that they will be differently refracted in the prifmatic order; accor- ding been communicated to’the Royal Society by the Author, in a letter to the Reverend Dr James Bradley D, D, F.ReS.; yet it could not be omitted here, on account of its conneéion with fome of the queries that follow ; befides that it contains feveral illuftrations not to be found in the Tranfa@ions. * Newt, Opt. query 29. PHYSICAL anv LITERARY. 45 ding to obfervation, Since, according to Sir Ifaac Newton’s do@trine of refra@tion now generally received, the velocity of a ray, after entering any new medium, is to its former velocity, as the fine of inci- dence to the fine of refraction*; if all the colours move with equal fwiftnefs in any one medium, their velocity will neceflarily become unequal, upon entering a denfer medium, in the inverfe proportion ‘of their feveral fines of refrangibility: Tho’ we fuppofe, therefore, the fun’s rays to be e- mitted with the common velocity, it will follow that their velocities are unequal in air, glafs, water, or any tran{parent body, _ whofe refractive denfity differs from that of the folar atmofpheref. This confide- ation is fufficient to take off the appear- ance of improbability from our hypo- thefis. 38. ON fuppofition that the different refrangibility of the rays of light arifes folely from their different velocities before inci-=- * Newtoni Principia, lib. 1. prop, 95, + See below, query 3. 46 ESSAYS anp OBSERVATIONS. incidence; thefe velocities muft be, to one another, nearly as their fines of re- fraction. 39. Sir Ifaac found their fines of re- fraction from glafs into air, beginning from the extreme violet, to be* as 78, 772, T7935 772) 773) 175s 7722773 the fine of incidence being 50: From whence their fines of refraction out of air into glafs, beginning from the extreme red, and en- ding with the extreme violet, are tound to be as f. 78000, 77573, 77797, 77063, 77496, 77330, 77220, 77000; the fine of incidence being 120120. Thefe numbers, therefore, nearly exprefs the velocities in air, of the feveral rays, before their inci- dence {. HENCE * Newt. Opt. book 1, part. 2, prop. 3. + The extreme fines are plainly reciprocal to the fors mer, and thofe of intermediate colours are fourth pro~ portionals to the fine in Sir Ifaac’s experiment, 77. and 78. + The quantities which give the accurate proportion of the velocities, before incidence, muft be in a conftant ratioto the fines of refraétion, by which the above calcu- lations are made, have this condition : But, it is other- ways - my te PHYSICAL ann LITERARY. 47 40. HENCE their velocities in any other medium may be found; for they are, to thefe, ways manifelt, that they give only a grofs approximation to the truth. From what follows, perhaps, an exaéter “computation might be made, if a proper mean angle of incidence were made ufe of, although the quantities in the canon are really not in a conftant ratio. TAB. iii, fige 1. Let two rays, talling in the fame line of incidence IC, with different velocities, upon AB the furface of a denfer pedir) be lvckeatted! nto different lines CR, CV. Taking any line CD in the perpendicu. Jar to reprefent the total action of the refracting power on the lefs refrangible ray, and CE on the more refrangi- ble; If, through D and &, parallels to IC be drawn, meeting the refra@ted rays in V, Rand G; it is plain, that CR, CV will be as their refpective velocities after refraction ; and DR, EV, as their velocities before inci- dence. Since the whole acceleration which a given power produces in a body, is, ceteris paribus, as the time in which it operates ; CD muft be to CE nearly as the time which the {wifter ray takes to pafs through the refracting fpace, to that which the flower ray takes in paffing through the fame, inverfely, as their velocities before incidence; that is, as EV to DR: but CD is like- Ways to CEas DG to EV; therefore DR, EV, and DG, are continued proportionals; therefore DR is te EV in the fubduplicate ratio of DR to DG: But DRis to DG “ima ratiocompounded of DR to DC, and DC to DG, that * is, in the compounded ratio of S$, DCR to S, DRC, and of 48 ESSAYS anp OBSERVATIONS thefe, as the fine of incidence to the fine of refraction, when a ray paffes from air in- to the given medium *, 41. WHILE the differently-coloured rays are fuppofed to move with one com= mon velocity, any pulfes, excited in the ethereal medium, muft overtake them at e- qual diftances; and therefore the inter- vals of reflexion and tran{miflion, if they arife in this manner, as Sir Ifaac New- ton conjectures, would bé all equal: But, if the red move {wifteft, the violet floweft, and the intermediate colours with inter- mediate velocities, it is plain, that the fame pulfes muft overtake the violet foon- eft, the other colours in their order, and, laft of all, the red; that is, the intervals. of the fits muft be leaft in violet, and gra- dually of S, DGC to $, DCG; wherefore DR is to EV in the fubduplicate ratio of S, DCR X S, DGC to 8S, DCGX S, DRC; that is, ‘* The velocities before incidence are ‘* nearly in the direct fubduplicate ratio of thefe fines ‘* and the reciprocal fubduplicate ratio of the fines of «© the exceifes of the common angle of incidence above «« the feveral angles of refradtion.” * Newt. princip. lib. 2. prop: 10. PHYSICAL aNp LITERARY. 49 dually greater in the prifimatic order ; ac- cording to obfervation, 2. As the proportion between thefe intervals in red and violet can be afligned by experiment, and the proportion of their velocities inany medium likewife, by N° gos the velocity of the etherial pulfes in any medium, and their diftance from one an- other, may be thence computed by the following rule: “* Multiply the product * underthe velocities of the red and violet “rays by the difference of the intervals ‘ of their fits ; then divide by the diffe-. “rence of the two produdts which are. * formed by multiplying the interval of © the fits in red by the velocity of the vio- ** let, and the interval of the fits in violet “ by the velocity of red:” The quotient fhall exprefs the seit ef the ethereal pulfes *. Mota ln). ee ~ 43. THE + * Let C denote the celerity of the etherea! pulfes, V the velocity of red light, and v that of violet, I and é the in- tervals of their fits, and D the perpendicular diftance of twa cceeding pulfes : It is plain, from the nature of the hypo- hefis, that I isto D as Vto C—V, and again, Dtoéas C—o g0 ESSAYS anp OBSERVATIONS ' 43. THE velocities of the red and vio- let in air, are, by the above eftimation, as 78 and 77 *; and the intervals of their fits are, By experiment f, as too and 63: From whence, by the canon now laid down, the velocity of the ethereal pulfes is found to be to that of red light, as 79753 to 78000. As light moves from the fun to us, by Dr Bradley’s lateft com- putation t, in 8’, 12”, the pulfés of the e- thereal fluid will be i > fia tabacyt the fame fpace in 8’, 1%. 44. THE diftance between the ethereal pulfes is, to || the interval of the fits in red, as the difference between the velocity of the ethereal pulfes and that of red light as to the velocity of red light ; that inter- val, therefore, is not much more than ';th of C—v tov; therefore, ex aequo, 1 is to #a8 CV—Vz to » €v—Vv : From which arifes the equation — v g i— X Vo “TX 7X Vy * In the celeftial medium they are lefs, [No 40.7 but. very nearly in the fame proportion, tT Newt, opt. book 2. p. 1, obfervat, 14, t See Eames abridg- tranfa@: vol, vi. Ps 15:7. i See note * to foregoing page, PHYSICAL anp LITERARY. 51 of the interval of the fits in red, and there- fore does not much exceed ,,;35,; of an inch *, 45» THE velocity of the ethereal pulfes being determined, as above, from the in- tervals of the fits in the two extreme co- lours, as found by experiment, the inter- vals of the fits in the fix intermediate rays may be calculated from theory; for the interval in any one colour muft be, to that in red, as a product under the velo- city of the given colour and the excefs of the velocity of the ethereal pulfes above that of red, isto a product under the ve- locity of red and the excefs of the velocity of the ethereal pulfes above that of the gi- ven colour: But, even upon the fuppofi- Vtion of the trath of our theory, an exact coincidence between calculation and ex- periment is not to be expected till the ve- Jocities of the fays be more accurately de- _ termined. _ 46. Upon the hypothefis of the diffe- 4 it * See the table of the thicknefs of colcured plates in Newt, opt. part 2. book 2, ; " .. rent 52 ESSAYS anp OBSERVATIONS rent velocities of different colours, we may underftand, at leaft in general, whence it is, that the intervals of the fits may bear a proportion fome way related to the fpaces * occupied by the feveral . colours in the fpectrum ; an analogy o- therways very unaccountable! Since, from the velocities of the feveral rays up- on which the intervals of the feveral fits depend, arife likewife their feveral degrees of r2frangibility, which determine the {pace occupied by each in the fpectrum. AND thus likewife we may conceive how the different rays are qualified to produce different fenfations in the mind: For, having different degrees of impulfive force, they may caufe vibrations of diffe- rent magnitude or velocity in the optic nerve; by which, according to the laws of our conftitution, the ideas of different colours may be excited +, in like manner as the ideas of different tones arife from different vibrations of the air communica- * Compare Newt. opt. book 1. part 2. prop. 3. with book 2, part 3, prop. 16. ~ + Newton’s optics, query 13- ted PHYSICAL ann ‘LITERARY. 53 ‘ted to the auditory-organ. It has been faid, that the different fenfations excited in the mind cannot arife from the diffe- rent force of the particles of light; fince the colour of homogeneal rays is not al- tered by pafling through different media, though their velocity be thereby always — increafed or diminifhed *. But it ought to be confidered, that every ray, as it mult pafs at lait through the humours of the eye in order to vifion, falls upon the refz- na with one given velocity, whatever num- | ber of refraQtions it has previoufly under- gone: For the velocity of any ray in any one medinm being, to its velocity in any other medium, in a conftant proportion, viz. the inverfe of the fines of incidence and refraétion, when a ray pafles from the.one into the other; it is manifeft, that each ray muft have a certain determined velocity i in any given medium, which can- not be either increafed or diminifhed by making the ray pafs previoufly through a * Mufichenbroeck elementa phyfices, § 1161, any $4. ESSAYS anp OBSERVATIONS any number of tranfparent bodies any how difpofed *, _ Ir is impoffible therefore to know, whether an alteration of the fwiftnefs, with which a homogeneal ray ftrikes the retina, would alter its colour ; I mean the fenfation of colour produced by it in the mind; Since itis impoflible to alter, at pleafure, the denfity of that fluid which determines its final velocity. One may diftinguith two different ef- fects of the refractive power on the rays of light, viz. the change of direction and change of velocity. Sir Ifaac Newton has proved, with refpect to the firft, That itis different in the differently-coloured rays, and ofa determined degree in each: He has further proved, that refraction, confidered in its firlt effeA, does not * Here it is proper to obferve, that the hypothelis which fuppofes the intervals of the fits to be determined by the velocity of the ray, agrees well with a remarkable ob- fervation of Sir Ifaac Newton (Optics, book 2. part 1. obf. 21): viz that thefe intervals in any medium, at a given angle of iacidence. are of a given magnitude, without re- gardto the denfity of the furrounding medium. change PHYSICAL ann LITERARY. sy. ‘change the colour of any fimple ray. But it appears, from what we have now faid, that none of hisexperiments prove the im- mutability of fimple rays by the fecond effects of refraction. Pp 47. As it is of great confequence in philofophy to diftinguifh between facts and hypothefes, however plaufible, it ought to be obferved, that the various re- frangibility, reflexibility, and inflexibility of the feveral colours, and their alternate difpofitions at equal intervals to be reflect- ed and tranfmitted, which are the whole ground-work of the Newtonian fyftem, are to be confidered as certain facts de- duced from experiment: But, whether the velocities of the different rays are exactly equal, or different in the manner now de= feribed, is no more than probable con- jecture ; and though this point fhould be decided by a method propofed afterwards, it would {till continue uncertain, whether the fits of reflexion and tranf{miffion are eccafioned by an alternate acceleration and retardation of the motion of light, OF. 56 ESSAYS anp OBSERVATIONS or in fome other manner *, - And, after all, ic is no more than probable conjec= ture, that fuch an alternate acceleration _and retardation is brought about by the influence of pulfes excited in the ethereal medium: Nay, there are fome circumftan- ces in thefe phenomena that feem hardly intelligible by that hypothefis alone ; as, why the intervals of the fits are lefs } in denfer mediums; and why they increafe fo faft and info intricate a proportion, ac- cording to the obliquity {of incidence. 48. AccoRDING to Dr Bradley’s beau tiful theory of the aberration of light, the ftars appear to be removed from their * For inftance, it might be fuppofed, that every parti- cle of light has two contrary poles, like a load-ftone ; the one of which is attracted by the parts of bodies, and the o- ther repelled ; and that, befides their uniform rectilineal motions, the particles of differently-coloured rays revoive in different periods round their centre: For thus, their friendly and unfriendly poles being alternately turned to», wards the furfaces of bodies, they might be alternately dify pofed to refletion and tranfmiflion ; and that at different: intervals, in proportion to the periods of their rotation, + Newt. optics, book 2. part 3. prop. 17. t Prop. 15, ibidem. true PHYSICAL ann LITERARY. 57 true places to a certain diftance, by the proportion which the velocity of the earth bears to the velocity of light : It is plain therefore, that, on our hypothefis, a ftar muft have a different apparent place for every different colour; that is, ics ap- parent disk mutt be extended by the aber- fation into a longitudinal form refen- bling the prifmmatic fpectrum, having its _ Ted extremity neareft to its true place. In the ftars fituated near the pole of the eclip- tic, its length fhould continue always the fame, though directed along all the different fecondaries of the ecliptic in the courfe of a year: But, in thofe which lie’ . im or near the plane of the ecliptic, it fhould be greateft at the limits of the eaftern and weftern aberrations ; ; the ftar recovering its colour and figure when the true and mean places coincide, But, there is no hope of difcovering, whether our hy pothefis be true or falfe, by this “confequence of it ; for the greatett length of the dilated disk, being, to the whole berration, as the difference of the velo- ¢ ity of red and violet to the mean velocity: ‘ee Vou, II, H of. ‘ 58 ESSAYS anp OBSERVATIONS. of light, z. ¢. as 1 to 77 nearly, (No, 39). cannot much exceed one fourth part of a fecond ; for the greateft aberration is but about twenty feconds. 49. | HE time which the extreme violet takes to move through any fpace muft be, tothat which the red takes, as 78 to 77. If Jupiter be fuppofed in a quadrate afpect with the fun, in which cafe the e- clipfes of his fatellites are moft commodi- oufly obferved, his diftance from the earth being nearly equal to his diftance from the fun; light takes about forty one mi- nutes of time in pafling from him to the earth: Therefore the laft violet light which a fatellite refle@s, before its total emerfion into the fhadow of Jupiter, ought to con-~ tinue to affect the eye for a 77th part of AY, or 32", after the red reflected at the | fame time is gone: That is, a fatellite, {een from the earth, ought to change its colour, above halfa minute before its total immerfion, from white to a livid greenith colour, thence into blue, and at lait eva- nifh in violet. I need fcarcely obferve, that the faid phenomznm fhould take place PHYSICAL anp LITERARY. 59 place in the time of emerfion, by a contra- ry fuccéflion of colours, beginning with red and ending in white. 50. I this phenomenon flint be agu- ally perceived by aftronomers, we {hall have a fufficient direct proof of the ditte- rent velocities of the coloured rays; for I fee not to what other caufe the phaenome- non could be rationally afcribed: If it be not, we may conclude that the rays of all colours are emitted and reflected with one common velocity. Pome eek be Eke On the Imperfection of our Knowledge‘ concern= ing the Inflexions of Light, . 51. Str Ifaac Newton went a very confi- derable length in examining the inflex- ions of light, as well as its reflexions and refractions; but did not bring his inquiry on this head toaconclufion, He tells us, that he intended once, if other bufinefs had not called him off, to have made more expe- 60 ESSAYS anv OBSERVATIONS experiments; not for confirming himfelf im preeonceived opinions, as many do}; but for difcovering the true manner in which light is: inflected, for producing the coloured fringes with black lines be- tween then Tie adds, however, fome’ queries which contain hints of what he had gathered on this fubject from his own obfervations, viz. that the rays of light differ according to their colour in: their degrees of flexibility, and that they are bent feveral times backwards and for- wards with a ferpentine motion in paffing by the fharp edges of bodies: Thefe thoughts he threw out “in order to in- “‘ cite others to a further fearch*.” But, fo far have his intentions been difap~ pointed hitherto, that few phyfical writers feem to comprehend diftinétly the hints which he has left concerning the manner of inflexions |; and none, as-far as [know, has) * Newt. Opt, p, 313. fee the firt two or three que~ ries, : + When any opaque body is held at the diftance of iree or four inches from the.eye, fo that-a part of fome raore: PHYSICAL ans LITERARY. 65, has advanced one ftep beyond them. ft is furprifing, that, before Sir Ifaac New- ton, the world continued fo long entirely ignorant of the true theory of light and colours ; - more diftant luminous object, fach as the window or the’ flame of 2 candle, may be feen by rays pafling near its’ edge : If another opaque body, nearer to the eye, be brought acrofs from the oppofite fide ; the edge of the’ firt body wil! feeny to fwell outwards and meet the lat- ' ter, and, in doing fo, will intercept a portion of the lu- minous object that was feen betore. This phaenomenon has been rafhly afcribed to the in: Sexion of light, by fach as underftood not thoroughly the nature of inflexion, nor obferved accurately the circum. ftances of the fa@, Let AB reprefent the luminous objet (TAB, ili, Fins 5.) to which the fight is directed, CD the more diftane opaque body, GH the nearer, and EF the diameter of the pupil; join ED, FD, EG, FG, and produce them till they mect AB in K, N, M, and L: It is plain, that the parts AN, MB of the luminous object cannot be feen, But, taking any point a between N and K, and drawing aDd; fince the portion dF of the pupil is filled with light flow. ing from that point, it muft be vifible: Any point 5 be- tween a and K mutt fil! fF a greater portion of the pupil, and therefore muft appear brighter. Again, any point ¢ between 4 and K mutt appear brighter than 4; becaufe it fills a greater portion gF with light. The point K itfelf, and every other poinc in the fpace KL, muf appear with 64 ESSAYS anp OBSERVATIONS -cdlours; and it is no lefs fo, that, fince he quitted the fubject, no further difcovery of any moment has yet been made a- mongft all the philofophical focieties in Kurope. 3 52. with compleat luftre ; Since they fend entire pencils of rays EKF, ELF to the eye: And the vifible brightnefs of every point trom L towards M mutt decreafe gradually , as from K to N: d. e. The fpaces KN, LM will appear as dim fhadowy borders or fringes adjacent to the edges of the opaque bodies. When the edge G is brought to’ touch the right line KF, the penumbra’s unite; and as foon asit reaches NDF, the above phenomenon begins: For it cannot pafs that right line without meeting fome line aDd drawa from a point between N and K, and, by intercepting all its rays that fell upon the pupil, ren- der it invifible. In advancing gradually tothe line KDE, .- it will meet other Jines Df, cDg, &c. and therefore ren- der the points b, c, &c, from Nto K fucceflively invifi- Ble; and therefore the edge of the fixed opaque body €D muft feem to fwell outwards, and cover the whole fpace NK, while GH by its motion covers MK. When GH is put to a greater diftance from the eye, CD continuing fixed the ipace OP to be paffed over for intercepting NK islefs; and therefore, with an equal motion of GH, the apparent {welling of CD muft be quicker ; which is found true by experience, If ML reprefents a luminous object, and REFQ any plane expofed to its light; the fpace FQ will be entirely fhaded from the rays, and the fpace coe PHYSICAL ano LITERARY. 63. 52. Many ingenious men have beftow- ed infinite thought and labour on the more complex and aftonifhing phenomena of nature, without arriving at any certain or definite difcoveries ; fuch as earth: quakes, thunder, and other meteors 3 magnetifm, electricity, vegetation, fermen- tation, and other chemical operations: -and the fubtihty of thofe matters will pro- bably continue to elude the fearch of Jateft pofterity. But, in the fimpler, ftea- dier, and more regular fubjects, fuch as light and colours, which are capable of accurate. menfuration and mathematical reafoning, a fagacious and induftrions obferver can hardly fail of making fome progrefs ; efpecially:in a branch of the in- quiry which is already puthed to’a confi- | derable 4 - {pace FE will be occupied by a penumbra gradually dark- er from Eto F: Let now GH continue fixed, and CD move parallel to the plane EF; and, as foon as it paffes the line LF, it is evident, that the thadow QF will : feem to {well outwards, and when CD reaches ME, fo as to cover with its fhadow the {pace RE, QF by its exten- fion will cover FE. This is found to uuold true likeways by experiment. "64 ESSAYS anp OBSERVATIONS derable length. Difcoveries of this kind are capable of a particular fort of proof, which is very beautiful and convincing, from the exact concidence of the compu- ted effects with the real ones, as to quan-: tity. Many inftances of this occur in Sir Ifaac Newton’s writings, and in all mathematical philofophy : fuch as the cal- culation of the moan’s irregularities; of the tides; of the preceflion of the equinoxes; of the refiftance of fiuids ; and, in optics, his computation of the dimenfions of the rainbow ; of the aberration of colours; of the intervals of the fits of reflexion and tranfimiffion ; and of the coloured rings reflected by thick tranfparent /peculums, Wart farther I have to offer concern- Jight and colours, confifting chiefly of doubts, difficulties, or loofe conjectures, thall be propofed under the form of ques TICS. SECT, F ' ftration of this queftion to form, by Sir PHYSIGAL ann LITERARY. 6 $B C TF. VIL Querics, confifting of Doubts, : Difficulties, and Conjectures, concerning Light Colours, and | coloured Bodies. Query I. Are not the rays, emitted by all forts of luminous bodies, fimilar to thofe of the fiin, both as to colour and degrees of réfrangibility? And, do not lu-. minous bodies differ from one another only according to the colours which they émit moft plentifully, in like manner as opaque bodies are diftinguifhed by the colours of incident light which they re- fle in greateft abundance? (See N° 24. 25. 26.27.28. and 29.) But, to make our induction fufficiently ftrong,; ought ‘hot experiments to be made with the _ lights of a greater variety of bodies? And would it not further conduce to the illu- Vou. IL I Haac’s 66 ESSAYS anND OBSERVATIONS Ifaac’s method*, a beam of folar light, confifting of fuch colours and in fuch proportions as were feen in the lights of "falts and burning fpirits; and then to obferve in it the appearance of coloured: bodies? Further, are not the intervals of the fits, in rays of any one colour, the fame in the fame meduim, from whatever luminous body they are emitted? For, if thefe intervals were different, would there not be changes in the. colours of bodies, not to be accounted for by the eompoli- tions of the lights with which they are’ illuminated? | | QveErR. II. Donot all luminous bodies, the molt languid as well as moft bright, emit their lights of any one colour with one determinate velocity ; fince it is found by experience that they are all equally refrac- ted by the fame medium? And therefore, does not the different fplendor of lumi- nous bodies proceed wholly from the dif- ferent denfity of their light»at equal di- ftances? Andis not this confirmed by the equality’ * Newt: Opt, book r.-part 2. prop. If* PHYSICAL anv LITERARY. .- 67 équality of Bradley’s aberration of light in fixed ftars of all magnitudes *? If this be fo, the comparative ftrength of diffe. rent lights, fuch as of the fun, moon, a candle, dc. may be eafily eftimated by finding the greateft diftances to which the fame opaque body is vifible when illumi- nated by each of them, or the limits be- yond which it is invifible to a given eye; for the denfities of the incident lights are nearly as the fquares of the diftances of thefe limits from the object ¢. Does not all light move with the fame velocity af- ter reflexion as before ; fince the angle of reflexion is always equal ta the angle of . incidence? - * Eames's Abridg. of tranfa&, yol. 6. p. 158. ~ $ Let A and a (Tas, iii, fig. 6.) denote the faine or two equal bodies of the fame colour illuminated with different - lights, and B, 4, the limits. As we fuppofe the light re- ceived by the eye, at thefe points, is juit fufficient to affe& it fenfibly and no more, the two lights at thele different diftances muft be nearly of the fame denfity; taking therefore in AB a line A g equal to wd, the denficy of the light as g mult be, to the denfity ot the light at 4, near- ly as AB? to Ad? : And, it is evident, that thefe denfi- fities, at equal diftances, muft be as the whole quantities of light reflected; and thefe again very nearly as the whole quanties of light incident. 68 ESSAYS ann OBSERVATIONS incidence? The exception, made by fome, of electrical light is founded on no lefs a miftake than confounding the luminous body with its light *. But the beft proof of this propofition is from the coincidence of the computations of the velocity of light, from the equation of the eclipfes of Jupiter’s fatellites,and the aberration of the fixed flars f. Quer. IL Is light emitted with the fame velocity, in whatever medium thelu- minous body be placed? Or, is it not ra- ther emitted with greater velocity in den- fer mediums, and that in proportion to their refraGtive powers? The fame argument from whence we gather in general the e- qual velocity of light emitted by all forts of luminous bodies, feems to prove the truth of the latter fuppofition. For, fince rays of any one colour, from the fan and a candle, for inftance, are equally refrac- ted by a furface of glafs or water, we * Muffchenbroeck’s Elementa Phyfices, late edition, in his chapter on electricity, el e y + Eames’s Tranfact. vol. 6. &e, ¢ PHYSICAL anv LITERARY. by aay conclude, that their velocities in air are equal. Wherefore, if the denfity of the fun’s atmofphere, contiguous to his furface, be different from the denfity of our lower air, as may be fafely prefumed, his rays muft have been emitted with more or lefs velocity than that of the candle; o- therways, they could not have the fame velocity afterwards in any common medi- um; For, the velocity with which any ray. is emitted, is, by the laws of refraction, to its velocity in any given med-um, as the fine of refraction to the fine of incidence, when a ray pafles from the medium of > miflion into the given mediym. Quer. IV. IF the atmofphere is noe much warmed by the paflage of the fun’s light thro’ it, but chiefly by its. contact with the heated furface of the globe, as we fhewed above (No 15.); may we not | hence give one very fimple and plaufible reafon, why it is coldeft in all climates on the tops of very high mountains ; namely, becaufe they are removed to the greatelt diftance from the general furface of 40 ESSAYS anp OBSERVATIONS of the earth? For it-is well known, that a fluid heated by its conta& with a folid body decreafes in heat, in fome inver{e proportion to the diftance from the body. But, to have this queftion fully determi- ned, the temperature of the air in the val+ Jey and on the mountain top muft be ob- ferved every hour both night and day, and carefully compared together. | ~ Quer. V. From what has been laid down in Se&, 2. concerning the manner of the action of light in heating bodies, is it not reafonable to fuppofe that the heat produced by a given number of rays, in an opaque body of a given magnitude, muft be greater when the rays are more inclined to one another, than when they are lefs fo? For the dire@tion of the vi- brations, raifed by the action of the light, whether in the colorific particles or thofe of an inferior order, will more interfere with one another; from whence the inte- ftine fhocks'and collifions muft increafe: Befides thisy'the colorific particles of o- paque bodies being difpofed in various fituations, perhaps, upon the whole, the Taya PHYSICAL anp LITERARY 7 rays will fall more diretly on each, the more they are inclined to one'another. Is not this the reafon of what has been re=_ marked by philofophers *+, That the heat of the fun’s light, colleéted into a cone, increafes in approaching the focus in a much higher proportion than accor- ding to its denfity ? That the. difference of the angle, in which the rays fallon any particle of a given magnitude placed at different diftances from the focus, is but fmall, is no proof that the phenomenon can= not be aferibed to it; fince we know not in what high.proportion one or both the eircumftances-now mentioned may ope- rate. However, that it proceeds not from any unknown a¢tion of the rays upon one -another, as has been infinuated t, is evi- dent from this, that each particular ray, after pafling through the focus, preferves its own colour and its own direction, in: the fame manner as if it were alone. QUER. _ * Boerhaave, Element. chemic. de igne, . t Mufichenbr, Elementa Phyfices, § 10402 Safad y2 ESSAYS 4np OBSERVATIONS’ Quer. VI.. May it not be inferred, that the component parts of opaque bo= dies are greater than thofe of tranfparent ones, as theory requires *, from this’ fim- ple obfervation, that the former, fuch as metals, ftones, woods, &c. when broken tranfverfely, fhew a vifible roughne(s and inequality at the’ fracture; whereas the latter, fuch as glafs, chryftal, gems, ice, &c. appear as fmooth, almoft, as. when they are polifhed ? Quer. VII. Do. not Newton’s experi- ments with the ifland and rock chryftal fufficiently prove, that the rays of liglit have different permanent properties in their different fides, relative to thefe two bodies ? Muft we not therefore conceive each particle of light to preferve its pofi- tion invariably while it moves forward, at leaft fo as not to revolve round its cen- ter perpendicularly to the direction of its motion ? Would it not be préper to try how light is inflected in pafling clofely by the feveral angles and fides of thefe fof fils ? * Newton’s opt. Book 2. part 3. prop. 4) | QUER.. >". a PHYSIGAL ann LITERARY. 73 Qurx. VIII. Is it not poflible to prove by experiment what Sir Iaac Newton takes for granted as a reafonable fuppofi- tion, that thin tranfparent plates, of any uniform colour, divided into fmaller frag- ments, would compofe a powder of like colour *? And would not this tend to ftrengthen the analogy between the co- Jourspf fuch plates and thofe of natural bodies ? For this purpofe, I have tried to freeze foap-bubbles ; but could never make any ftand till they were turned to ice, except fuch as were too thick to have lively colours: .However, I doubt not, but, with due care, the thing might be- done; efpecially, if the foap-water, in- ftead of being blown with a pipe into bubbles, were drawn out into a plain plate upon any wooden or metalline frame: For, the fides of a plain furface bearing a greater proportion to its area, than a bafe of a fpherical fezment to its - furface, the froft would be fooner com- municated to the whole water in the for- ~ mercafethan in the latter, There is this Vou. Il. K advantage * Newton’s Opt. book 2. part 3. prop. 5. wa ESSAYS asp OBSERVATIONS advantage too in ufing a plain furface of foap water, that, before it freezes, the obferver may draw out any particular colour or feries of colours, which he chu- des, to a greater breadth, by ftroaking it ‘along with a wet finger. For this reafon, amoneg{t others, I have found it a more convenient fubject for examining the va= rious orders of colours, than {phericat bubbles adhering to a plane. Perhaps, melted refin might be drawn out into a thin-celoured plate before it hardens ; for I have often blown it into bubbles with a tobacco-pipe till it became coloured. f Know no other ways in which the various: orders of colours can be preferved for de- liberate inf{pection, but either in a frozen plate of water or rofin, or in the perma= nent /coria that appear on heated metals. I have counted, on the fide of a clean polifhed copper tea-kettle, the fix firft or- ders of colours diftintly and regularly ranged in ‘the fame fucceffion in which they appear in the foap-bubbles; the firit order being formed on that part of the kettle that had been Icaft heated. Qr Er. PHYSICAL anv LITERARY. 75 Quer. IX, Wuart elfe is the inflexion of light towards the fine edges of bodies than a particular cafe of refraction, in which the rays, after being bent by the attractive power, are carried beyond the refracting furface, and mifs entering it, - becaufe of its {mall extent? For, if the furface of the edge be produced, it will meet the inflected rays ; and thus the in~ flexion will become properly refraction, And, in like manner, we may confider the inflexion of light off from the edges of bodies as a fpecies of reflexion. Quer. X. Is it not impoffible that an animal can fee, if the diameter of its eye be much lefs than the interval between the fits of tranfmiffion and reflexion in ater, that is, than 5;!5,5" of an inch? Quer. XI. THERE are many experi- ments which fhew that a yellow and blue ray mixed, make a green one; a yellow and blue powder, a green powder; and a | mixture of rays or paints of all the prif- - matic colours, a white ray or paint: Now, do not the fame experiments equally de- montftrate, 46 ESSAYS anp OBSERVATIONS monftrate, that the idea of green is a con- fufion or mixture of the ideas of yellow and blue; the idea of white, a mixture of the ideas of all the colours; and, in general, the ideas of all compound co- lours, a mixture of the ideas of their con- {tituents? In the experiments which Sir _ Ifaac Newton performed with the toothed inftrument, the component colours are not, indeed, prefented to the eye all at once; yet they follow one another in fo rapid a fucceffion, that their refpective impreflions remain in the eye till they are renewed, and therefore they muit arfect the mind all at once*. Ifa piece of pa- per * It is in this manner that philofophers explain (Ne: Opt. Quer. 16.) the appearance of a fiery circle, which is made by a burning body whirled about fwiftly. We {hall here give an account of fome other phenomena that flow trom the fame principle, If a white rod be moved rapidly backwards and for- wards with an angular motion, the whole circular {pace which it runs over will appear whitifh ; but not equally fo, being tainteft and moft dilute in the middle, and brighter towards the two fides, which feem to be di. flinctly terminated with two white rods interfeéting each other in the center of rotation, (See Tap, ili. Fig, 7.) i The PHYSICAL anp LITERARY. 77 per be daubed all over with fmall dots of blue and yellow, it will appear green to an The total impreffion made upon the eye by equal fmall parts of the feétor mult be, as the quantity of Jight emit- ted from it and the frequency of the returns of the rod to it; i,¢. inyverfely, as the time between the returns of the rod. Let ABC reprefent the circular fector, and DC _ a line bifedting it; the rod always returns to DC after the time of one vibration; and, to.any other line EC between DC and AC or AB, the mean time of its return is the fame; for it alternately returns in twice the time of deicribing AE and twice the tine of de- {cribing EB; fo that two fucceeding intervals ot its returns are equal to the time of two vibrations: But the intervals of the returns to the lines AC or CB ate mani- feftly equal to the time of two entire vibrations. The brightnefs of the fector therefore in DC, ar any line be- tween DC and AB or BC, mutt be fimply as the quantity | ipbot light emitted from equal fmall portions of the fe@or ; that is, in the inverfe proportion of the velocities of the rod when in thefe lines. It is plain from this, that the - fetor mutt be ixcomparably brighter in AC and BC, where it refts, than any where elfe, notwithftanding that the intervals of return thither are double ; that is, it will appear to be bounded diftinatly with a white rod on each fide. If the rod be agitated with fmall and quick vibrations . of its own, by fticking it again{t fome folid body imme- diately before it is hurried backw ards and forwards with the “8 ESSAYS anp OBSERVATIONS \ an eye which is placed at too great a di- {tance to diftinguifh the feparate points. In whatever manner fenfation be perform- ed, it is certain, that the organs which receive the firft impulfe from external ob- jects cannot convey to us any ideas, if they, or the impreffions made by them, be lefs than of a certain definite magnitude. A number of things feparately intangible, if joined together, may be felt by the touch: A certain number of invifible points become fufficient to affect the fight by their united rays; and a certain num- ber the angular motion, the feétor appears divided, at equal intervals, by a great many diftin@ rods, almoft as bright as the two lateral ones (Tas. ili Fig 8 ) refembling the fpokes of a fpread fan, The reafon of which curious phenomenon is plainly this; that its angular motion, be- ing alternately in the fame and in a contrary direction to its particular vibrations, is alternately accelerated and retarded or (topt. In the interval, where it is accelerae ted, the fector muft appear very dilute; and, where it is greatly retarded or brought to reft, mult appear very luminous or divided by white rods, for the fame reafon that they appear at the fides, PHYSICAL ann LITERARY. 79 ber of founds too fmall to be heard fepa- rately, at laft form an audible’ found *. Quer, XII. Since bodies derive their colours from the original and immutable qualities of thofe rays which they reflect moft *® Sore fceptics have difputed againft the endlefs di- vifibility of quantity, becaufe the imagination foon ar- fives at a minimum; alledging from thence, that our t- dea of extenfion involves the notion of indivifibles, and is as it were compounded of them, Nothing corporeal can be imagined or conceived at all which is not eonceived as feen, handled, or otherways fenfibly perceived. Ima- ginative ideas are nothing elfe than tranfcripts or images of fenfations, and therefore muft be limited by the fame bounds and in the fame manner as fenfation. Now the minimum fenfibile is rather in all cafes a confufed, indi- ftin@ and uncertain tranfition from perceivable to not perceivable, than the clear perception of a point indivifible in magnitude; for its magnitude depends on the luitre of the objet. That nothing can be conceived or ima- ginéd which is lefs than a certain bulk, is no more an ar- gument againit the endlefs divifibility of quantity, than that nothing can be felt or feen below that fize; which, it is evident, from every magnifying ylafs and from every d fferent diftance of an object, depends not at all on the conttitution of the ‘thing perceived, but on that cf the perceiver, or the means and circumftances of his per- ception, Nor, though it were granted that the mizimum vifibile is diftin@ly feen as an indivifible point, would it follow, that 85 ESSAYS anp OBSERVATIONS moft copioufly, ought they not to appear of the fame colour, whether viewed at the greateft or leaft difiances? Whence is it therefore, that the planets, whofe folid parts are probably covered with vegeta- bles, and muft therefore reflect great fu- periority of green rays, appear almoft in- tirely white when viewed from the earth? May not this be accounted for, in the fame manner as the change of colour ob- fervable in earthly objects feen through a great tract of the atmofphere? A moun- tain covered with the frefheft verdure, at the diftance of twelve or fifteen miles, looks that the idea of extenfion, received by fight, is made up of the ideas of indivifibles ; for we receive the idea of ex- tenfion by that motion of the eye which is neceflary to di- reét its axis to different objects or parts of an object: And, it is well Lnown, that the generation of quantity by mo- tion is preferred by the beft writers, for this very reafon, that it neceflarily excludes the notion of indivifibles. It fllould be remembered likeways, that a vilible object ts not divided by the eye into a number of contiguous mmé- nima vifhilia; for, to whatever mathematical point in the object the eye is directed, a minimum vifibile may be feen there by means of a certain portion of the object ine- mediately furrounding it, PHYSICAL aNnp LITERARY. 81 jooks blueith ; and at twenty or thirty, e {pecially if the air be thickened, degene- fates into a dim white, fo that one can hardly diftinguifh it from the clouds that fkirt the horizon. With refpect to the primary planets, it may be likeways an- {fwered, that perhaps we fee them chiefly by light reflected from the air and va- pours that furround them. ‘Quer, XIE Wuy is it fo hard to di- ftinguifh green bodies from blue “8 can- dle-light? Quer. XIV. WHENCE proceeds the bluenefs of the fey? Since it is certain that no body affumes any particular co lonr, but becaufe it reflects one fort of rays more abundantly than the reft; and — fince it cannot be fuppofed that the con- flituent parts of pure air are grois enough to feparate any colours of themfelves ; sli we not conclude, with Sir Ifaac New: ton * , that the violet and blue making rays are reflected more abundantly than | the reft, by the finer vapours ‘diffafed Vou. H. L.: through # Opt. book 2. part. 3. prop. 7: 82 ESSAYS anp OBSERVATIONS through the atmofphere whofe parts are not big enough to give them the appear- ance of vifible opaque clouds? Do not . thofe who fay *, that the ethereal blue proceeds from the mixture of the fun’s white light reflected faintly by the atmo- {phere with the perfeét blacknefs of the’: celeftial fpace behind, revive, without a- ny neceflity, the antient confufed notion, that all colours may be formed by cer- tain compofitions of light and fhade? Als though the atmofphere reflects more blue — rays than what go to the formation of perfect white, it is eafy to conceive how coloured bodies, illuminated by it, may not be fenfibly tin@ured with blue. Let us fuppofe, that the atmofphere reflects + more of blue rays than of the other co- lours, and that vermilion refle@s +2 of the red rays incident upon it, and 3; of every other colour; then, it is clear, that the 1ed rays, reflected by. the vermilion, will {till exceed the blue reflected by it, as 19 exceeds 1 +7:So that the purity of its’ * Nature difplayed, vol, 4. And Mufchen, Phyf. §. 1403-: PHYSICAL anp LITEBARY. 83 ats red colour will not be fenfibly impair- ed. But, to fhew that, in proper circum- ftances, the blueifh colour of fky-light may be feen on bodies illuminated by it, as it is objected fhould always happen*; ex- pofe to the fun-beams, on a clear cloud> lefs day, a fheet of white paper, and place on it any opaque body; you will perceive that the {pace of the fhadow, which is il- luminated only by the fky, appears re- markably blueith, compared with the re({t of the paper which receives the fun’s di- rect rayse If certain white and black paints mixed together produce blue, it is becaufe the black is not perfect thade, but a dark blue or purple { {.. Any mix- ture of whitenefs and true black can only form a fainter white or grey, which has no more affinity with blue Han with red or any other-colour. Quer. XV. Is not the opinion which Sir Ifaac Newton feems to have had §, and, * Muffchen. phyfices § 1403. t Ibid. § 1172. 4 Newt, Opt, book 2. part 3. prop. 7- § OP, book 2, part 3. prop. 5+ near the end. 84 ESSAYS anp O®SERVATIONS and, fince him, the generality of philofo- phers, concerning the caufe of the vari- ous colours reflected by the clouds at fun-rifing and fetting, liable to great dif- ficulties? For, why fhould the particles of the clouds become, at that particular time, and never at any other, of tuch mag- nitude as to feparate thefe colours? And why are they rarely, if ever, feen tindu- red with blue and green, as well as red, crange, and yellow? Is it not more credi- ble that the feparation of rays is made in pafling through the horizontal atmo- fphere? and that the clouds only. refleé and tranfmit the fun’s light, as any half traniparent colourlefs body would do in their place? For, fince the atmofphere, as was faid'in the laft query, refle@s a ereater quantity of blue and violet rays than of the reit, the fun's light, trant- mitted through it, oughr ‘to draw to- wards yellow, orange, or red; efpecially when it pafles through the greateft tract of air: Accordingly, every one muft have remarked, that the fun’s horizontal light is fometimes fo deeply tinctured, that ob- jects PHYSICAL axp LITERARY. 8g jeéts direQtly illuminated by it appear of a high orange or even red; at that in- ftant, is it any wonder that the colourlefs clouds refle& the fame rays in a more 7 bright and lively manner ! It is obfervable, that the clouds. do not commonly aflume their brighter dyes till the fun is fomemi- nutes fet; and that they pafstrom yellow toa flaming golden colour ; and thence, by degrees, to red; which turns deeper and deeper, though fainter, till the fun leaves them altogether... Now, it is plain, that the clouds, atthat time, receive the {un’s light through a much longer tract of air than we do af the inftant of fetting, per- haps by the difference of a hundred miles ormore; as may be computed from their height or the duration of their colours. Is it not, therefore, natural to imagine, that, as the fun’s light becomes always fomewhat yellowith or crange in pafling through the depth of the atmofphere ho- rizontally, it ought to itcline more and more from orange towards red, by paf= fing through a ftill greater length of air; fothat the clouds, according to their dif- 2 ferent &6 ESSAYS anp OBSERVATIONS ferent altitude, may affume all the vari- ety of colours obferved in them at fun- rifing and fetting, by barely refleCting the fun’s incident light as they receive it? I have often obferved with pleafure, when in Switzerland, that the fnowy fummits of the Alps turn more and more reddifh after fun-fet, in the fame manner as the clouds. What makes the fame colours much more rick and copious in the clouds, is their fenmi-tranf{parency joined with the obpagaaty of their fituation, Doss it not greatly confirm this expli- cation, that thefe coloured clouds imme- diately, refume that dark leaden hue which they receive from the fky as foon as the fun’s direct rays ceafe to ftrike upon them? For, if their gaudy colours arofe, like thofe of the foap-bubble, from the particular fize of their parts, they would pre(erve nearly the fame colours, though much fainter, when illuminated only by the atmofphere. About the time of fun- _ fet, or a little after, the lower part of the ikky, to fome diftance on each fide from the place of his fetting, feems to incling tg pHYSICAL any LITERARY. 87 to a faint fea-green, by the mixture of his tranfmitted beams, which are then yel- lowith; with the ethereal blue: At greater diftances, this faint green gradually chan- ges into a reddifh brown; becaufe the fan ’s rays, by paffing thro’ more air, be- gin to incline to orange: And, on the oppofite fide of the hemifphere, the co-+ lour of thé horizontal fky inclines fenfibly to purple; becaufe his tranfmitted light which mixes with the azure, by pafling through a ftill greater length of air, be- ’ comes reddifh; as we have faid above. To underftand diftinétly why the fun’s rays, by pafling through a greater and greater quantity of air, change by de- grees from white to yellow, thence to o« range, and laftly to red, we have only ta apply to the atmofphere, what Sir Ifaac fays (Book I. of his Optics, part 2. prop.. Io.) concerning the colour of tranfparent liquors in general. Is it not the fame coloured light of the rifing and fetting fun which tinctures the clouds, that, being thrown by the refrac- “tion of the atmofphere into the earth’s fhadow, 88 ESSAYS anp OBSERVATIONS fhadow, gives the moon fometimes, in tou tal eclipfes, the obfcure reddifh colour of brick? As the rays which pafs through the greateft tract of air become reddith: thofe which pafs through the leaft, yel= 'Yowifh; and the intermediate ones, o- range: The red muft converge fafteft in- to the fhadow; after them, the orange ; and laftly, the yellow: So, that the whole’ {pace of the earth’s fhadow, from the point of the cone to about femidiame- ters from the earth, being filled with a faint light, whofe colours verge always more to red in approaching the earth ; the colour of the moon, 1n total eclipfes, muft needs vary likeways, according to her diftance from the earth at the time of obfervation; and, if I miftake not, be al- ways more inclined to red at entering and leaving the {hadow, than in the middle. Let Aftronomers determine, whether the phacnomena agree with this theory. It is not furprifing, that this refraCted light is very faint and obfcure at the diftance of the moon; fince its mean denfity there will be as much lef than the denfity of — | the eros S262 PHYSICAL anp LITERARY. 89 the light of the fetting fun, as the annu- lar {pace of the lower air through which it pafles, drawn into the moon’s het 2 tal parallax, is lefs than the area of a great circle of the earth drawn into four times the excefs of the horizontal refraction of the atmofphere above the fame parallax ; that is perhaps as I to or more. QUER. XVI. I have obferved, when “atitea, that, though I preffed my. body and head firmly to a corner of the cabin, fo as to be at reft in refpect of every ob- je& about me, the different irregular mo: tions of the fhip, in rolling or pitching, were {till difcernible by the fight: How ig this fa@’to be reconciled to optical prin- ciples? Shall we conclude, that the eye, by the fudden motions of the veffel, is tolled out: of its due pofition ? Or, if ir fetains a fixed fituation in the head, is the _ perception of the fhip’ s motion owing to ta vertigo in the brain, a deception of the _ imagination ; or to what other caufe? Qver. XVII, Has not gold been redu- Pied, by beating, to a degree of thicknefS Me vouu. Me: " Hittle go ESSAYS AnD OBSERVATIONS little exceeding that which muft be aferi- bed to its colorific parts, according to Sir Ifaac Newton’s theory? But, how can it cohere into a continuous leaf, fo asto leave no vifible pores, unlefs there be many of its component particles contained in. its: thicknels? Quer. XVIII. Wen one looks fted- faftly at Sirius, or any bright ftar not much elevated above the horizon, its co- lour feems not to be conitantly white, but appears tinctured, at every twink- ling, alternately with red and blue: To what is this appearance owing? Is not the’ fevaration of colours by the refraction of the atmofphere too fimall to be percei- ved? vER. XIX. Boprers become black by burning: becaufe they are reduced * into very fmall parts: But, whence is it, t hat moft bodies, when further burned to afhes, aflume a grey or whitith colour? U FRLRX. Sine E the caufe of black- nefs in bodies is. the fmallnefS of their ee Cae * Newt. optics, book 3. part 2, prop. 7. trant ee ee Pee 4 > eek ae etn eee te il ee ii i OO Oe, PHYSICAL anv LITERARY. 91 tranf{parent parts, which renders them in- capable of reflecting any colour, How can black bodies, folid or fluid, be at the fame time opaque? Can light be finally ftifled by the refractive powers of the par- ticles alone? Or, ought it not rather to make its way thro’ the body, if there be no reflexion, without any fenfible lofs, al- tho’ the feveral rays might iffue in vari- ous direCtions? And, may it not be de- manded, in like manner, concerning all coloured opaque bodies, How all forts of light can be ftifled and ftopt within a _ body, whofe internal parts are fitted to refle@ only one or two cOlours, and trans- mit all the reft? | QUER. XXI. If the parts and pores of pellucid bodies be much lefs than the leaft interval between the fits of reflexion and traf{miflion ; it is plain, that rays of light, entering a part or pore in a fit of tranf- miflion, will not be refle&ted at its back 4 furface : And thus it may be underftood, how all rays that enter the firft furface of _ atranfparent body continue to be .tran{- Mits 92. ESSAYS ano OBSERVATIONS mitted through its fabftance to the greateft ditances, viz.if the rays are always put into a new fit of moft eafy tranfmiilion at entering every new pore or particle. But is nat that fuppofition contrary to what Sir Ifaac teaches elfwhere, that the fits of reflection and tranfmiffion continue to return at equal intervals, after a ray has entered a tranfparent body, and are thus regularly propagated to the greateft dif- tances *? And, if this be true, how can the rays be tranfmitted to any fenfible diftance, fince they muft often arrive in fits of eafy refieCtion at the common fur- faces of pores and particles? But, al- though it could be underftood by the doétiine of the fits in light, why there ig no refiection from the interior’ parts of water and other pellucid mediums T, does not the rectilinear tranfmifficn of hehe through thefe bodies in all direGtions, and confequently in all degrees of obliquity, to their internal parts, prove, that thefe | pitta * Newt opt. book 2. part 2, prop. 12. - T ibid. book 2. part 3. prop, 4. PHYSICAL sNp LITERARY. 93 parts, upon account of their minutenefs, lofe their powers of refraction as well as reflexion? And to what known property of light or bodies can this be attribu- ted? QUEER. XXII. Ir the fits are produced by an alternate acceleration and retarda~ tion of the particles of light, fome of the particles, which are fwift enough to be tranfmitted at the firft furface ofa tranf- parent. medium, muft overcome the re- flecting power more eafily than others ; namely, thofe that happen to be in their point of greateft celerity or neareft to phar Now, muft not rays that are moving with different velocities, be differently bent from their courie, as we argued above with re- {pect to fimple coloured rays, by the fame refractive power? Why theretore is not every beam of light, homogeneal or he- terogeneal, diffufed by refraGtion into in- numerable rays, according to the refpec- tive velocities with which they entered the refracting furface? Is it a fufficient an{wer to this query, That rays which are farchen from thei eir point of greateft {wift- 5) nels - 94 ESSAYS anp OBSERVATIONS nefs will be moft bent ina direction con- trary to that of refradlion, by the reflea- ing power, and will therefore only return to the direction of fwifter rays bya great- er degree of refraction? Quer. XXIII. Sir Ifaac Newton juft- ly argues, that light muft be reflected at a diftancée from bodies; becaufe the moft polifhed furface, being extremely rough and uneven in refpect of the particles of light, would difperfe them indifferently in all directions, if they rebounded from it by ftriking: But, will not the like dif- ficulty ftill remain, viz) How light can be reflected or refra@ted regularly by the beft-polithed furface, if the power of the body proceeds from an attraction or re- pulfion belonging to each phyfical point? {t might be perhaps fuppofed, that the re- pulfive power produces reflexion at a di- itance fo great, in refpect of the inequali- ties that are left in polifhed bodies, that the direction of force, refulting from their joint action, may be very nearly perpendi- cular to the general furface of the body; and this might tend to account for the regular PHYSICAL ann LITERARY. 95 regular’ reflexion from the anterior fur- face of a denfer medium. But, will this fuppofition fuffice for explaining theregu- larity of refraction, and of reflexion, from the pofterior furface of a denfer medium: In both which cafes, the light muft actu- ally enter the pores of the attracting bo- .dy, and therefore approach much nearer to one inequality than another; fince the pores, by which it enters, are certainly much lefs than thofe inequalities! In wa- ter and other tran{parent liquors, this -muft certainly be the cafe, if their globu- lar particles touch one another, as is com- monly concluded from their incompreffi- os bility : For, as a number of {pheres laid together leave no rectilinear paflages be- tween them, the tranfmitted light muft pafs through the component particles ; and therefore the pores, by which it enters, muft be much lefs than the whole hemi- fpherical furfaces of the particles which evidently conftitute the inequalities of the _ general furface of the liquor*, Quer. * We are certain, that the inequalities of a craggy Fock or rough wall are much greater than the ed particles of 96 ESSAYS anp OBSERVATIONS QueER. XXIV. How does light preferve its reCtilinear courfe in pafling through air, ether, and other elaftic fluids? Will not the difficulty ftill continue, whatever fabtility or rarity is afcribed to thefe me- diums ; fince the powers from whence their elafticity arifes, muft prevail through all . the three fpaces that interveen their particles ? Mutt we not, therefore, fuppofe, that the rays of light are not fubje€ to thefe repulfive powers, though they pafs through the fphere of their action? Does not the refraction of light towards the perpendicular, out of the celeftial fpaces nto air, even prove that it is attracted by the particles of air; Would it not be ex- travagant and incongruous beyond mea- fure, to imagine the ether fo fubtile, in refpect of light, that, though it be driven’ out of the way by the rays, as air is by commo!r of air or their dihance from one arother, by whieh their repulfive powers are probably terminated (Newt. Princip.) e ‘ Why is found, therefore, refleGed fo regularly from’, fuch bodies, that the echo is faintly hear, except at am ange of incidence equal to the angle of reflexion? PHYSICAL Anp LITERARY. 97 common projectiles, it is not capable of retarding them fenfibly in their motion from the moft diftant fixed ftars to our eye? Do not thefe and many other diffi- culties; in the phyfical part of optics, whofe folution is fought for in vain from any principles hitherto difcovered, fhew the neceffity of extending our views and inlarging our ftock of principles by fur- ther experimental inquiry? Such objec- tions are not to be confidered as demon- , {trations of the -falfhood of our prefent theory, but as proofs of its narrownefs, partiality, and imperfection. Des CarTEs, contenting himfelf with a fuperficial and inaccurate knowledge of the laws of impulfe, vainly dreamed, that he had got poffeffion of the univerfal caufe from whence all effects in nature are de- rived; when, in truth, he was unable to _deduce from them the fimpleft cafes of collifion. » Many in this age, who write and fpeculate on phyfical fubjects, feem to fall into a like error; while they em- ploy their whole fiudy in endeavouring Vor. IE. N to 98 ESSAYS ann OBSERVATIONS to reconcile all phexomena with the new principles difcovered by Sir Ifaac New- ton: And when they find, to their mor- tification, that’ this will not always fuc- ceed; phenomena muft be difguifed and nature tortured, to hide their ignorance. From the lazy method of philofophizing in the clofet, among books and diagrams, there never arofe, there never will arife, any difcovery of confequence: Great in- ventors ufually underftand the extent of their own principles too well, to leave much of the application of them to o+ thers. THE -difcovery of the different refran- gibility of the rays, was an ineftimable addition to natural knowledge ; as it ferves, at once, for explaining innumera- ble phacnomena ia nature which flow from ‘it as immediate and neceflary confequen- ces: And, if it {hall be demonftrated by the obfervation propofed in N° 49. that the differently-coloured rays really move with different velocities, our theory of light will be ftill farther improved ; asthe diffe= PHYSICAL any LITERARY. 99 different refrangibility can be thence me- chanically explained. _ Tue whole fyftem of nature is one im- menfe feries of caufes and effects, whofe beginning and end are equally hid in the depths of infinity. Only a fmall, a very {mall portion of it, comes under our im- _ mediate obfervation ; being expofed alike to the fight and other fenfes of all man- kind. Almoft every phaczomenon is, at once, the caufe of manifold effets; and one ef- fet, among many, of a fuperior caufe. ‘The butinefs of {cience is to extend our views, by unfolding the latent caufes which exift in nature ; and thence explain- ing their manifeft effe@s. The difcovery of one fuch real caufe, unknown before, if it be of general or very extenfive influ- ence, as that of univerfal gravity, is to be e{teemed a great advancement of natural philofophy. To undervalue fuch a difco- very, as fome have done, becaufe the taufe of that caufe cannot yet be afligned, ‘is highly abfurd: Since the fame objection muit for ever lie againft all caufes, except primary roo ESSAYS anp OBSERVATIONS primary ones; which are certainly remo= ved far beyond the reach of human in- quiry. The proper office, and higheft boaft of true philofophy, is, to bring us ftill nearer to the De1Ty, by leading us upwards, ftep by ftep, in the mighty {cale of nature, ART. PHYSICAL ano LITERARY 10; ne eo. An cafy Method of computing the Parallaxes of the Moon * ; by —————— ry AB. IV. fig. 1. 1. If from Q, the center of the fun, a right line OW be carried round, always touching the. earth’s furface, this line will form a coni- cial furface; which, being cut, bya plane pafling through the center of the earth, at right angles to the line joining the cen- ters of the fun and earth, the fe@tion fo made is the difk of the earth. 2. THE fame conical furface will cut off a circular portion of the moon’s {phere wanes; within which, any arches, inter- cepted by lines drawn from the center of the fun and extended to the difk of the earth, will be nearly in the fame propor- | tion ® Nov. 6: 1755 1o2 ESSAYS AND OBSERVATIONS: tion to one another, as the refpective di- {tances intercepted on the difk. 3. HENCE, ¢ being the center of the circular portion, wce the ecliptic, if the femidiameter of the difk be exprefled by , the number of feconds in the arch ¢w or ce=horizontal parallax of the moon from the fun, every line drawn on the difk will | be exprefled by the feconds of its corre- fpondent arch of the moon’s {phere. 4. Let C be the centre of the difk, WE,NS, the projections of we the eclip- tic, and #5 a circle of latitude; WNE being the upper or northern femicircle, and WS E the lower or fouthern. Let V be the place of any given vertex on the difk, and v the correfpondent point in the moon’s fphere; VA, VB, perpendiculars to NS, WE, and v 4,00 their correlatives. If the point v be the true place of the moon, i. ¢- if the vifible places of the fun and moon be the fame, then will VA be the par. lon. )#O, and VB. the par. lat. to a {pectator at the point V on the difk, or at the given vertex on the furface of the earth. For the par. loa. ) 4 @ asthe difference PHYSICAL ano LITERARY. 103 difference of the vif. lon. » 2 © obferved at Vand C: But the vif. long. y2© obferved at C, is the fame as if feen from A; there- fore the par. lon. DZ © is equal to the dif. ference of the vif. long. ) 4 © obferved at V and A, which is equal to the arch v a the meafure of VA. In like manner, VB may be proved to be the par. lat. )40; the vif. lat, being the fame when obferved at Bor C. _ g.In any other pofition of the moon, af its diftance from the point v exceeds not one degree, which it can never do in the time of an eclipfe; the parallaxes, to a {peGator at the point V of the dilk, will continue nearly the fame as before, with- —outiany fenfible alteration. Let / be the place ‘of the moon, /d,/f, perpendiculars | tocn,¢e;and let fl, v a, be produced till they meet in the point g¢ ; and let /d meet with vb in the point ¢; the vif. lon. pa ©, will be nearly the fame at the points ¢ and /, Therefore the vif. long. ) 2, ob- ferved at V, is the angle under which the arch vg is feen from that point. But the arch vg will be feen nearly under the fame tog ESSAYS any OBSERVATIONS fame angle from the points V and C; and confequently it is the meafure of the vif. lon. »@ «. But the truelon. is d/=ag: Therefore v g—ag=va is the par. lon. » é@@- Again, ad=/g=vif. lat. >) 40; and ¢ed=fl=tr. lat.: Therefore v b=ac=ad+ dc=par. lat.) 40. 6. But thefe parallaxes va, vb, and the vif; lon. and lat. vg, vi, fuppofe the fpectator at the point V on the difk ; whereas his true place is at the corre= {fpondent point of the furface of the earth ; _ confequently, the vif. lon. and lat. » 20, vg, vf, muft be increafed in the ratio of the diftance of the point v from the {pec- tator’s place on the furface, to its diftance from the point V on the difk. But, as the horizontal femidiameter of the moon fhould tikewife be increafed in the fame ratio, it will equally anfwer the purpofe of finding the times and phafis of an eclipfe, to let thefe continue unaltered, and to diminifh the fun’s apparent femi- diameter in the fame ratio. 7. LET Cr be the axis of the earth pro~ jected on the difk, FMD the ellipfe into — a which ale a¥, * it Pal My od ok tag iy, vtalow yah % WL gail ‘9 Hy ie em PHYSICAL anv LITERARY. 105 which the parallel of the given place is projected, DF its greater axis, OM its feffer femiaxis, VG perpendicular to CO; MH, GK, perpendiculars to CW, and MI,GL, at right angles to CN; and, - for fhortening the rules, put CW, the fe- midiameter of the difk, or the horizon- tal parallel p 2 © equal to the radius of the tables of fines and tangents. 8. For computing the parallaxes VA, VB, it will be convenient firft to fuppofe the fun in the meridian, and the place of the vertex at M; then to compute the va- Tiation of parallaxes for the given time from noon. 9. THE meridian par. lon. D 4 © is MI or CH ; 3 and the meridian par. lat. > CO) is MH or Cl: For finding which the re- quifites are, dite a? of the lat. of the place, : To be found zt of the declination of the fun, ~ ‘ p from the cat § of PCN =complement of the merdian angle, | ae Vou. Il, ares . Oc - 106 “ESSAYS any OBSERVATIONS oc= S: lat. pl_ x cof dec. © § North 2 if the Jat. North. a | a an South § pl, be South, anes Cof. Jat. e XS, decl. © of acontr. {pec. to the decl. ©. Diff. 2? of OC and OM, if (the fame A cM= he they are of different § SPEcies. CM X cof, merid. ang. 7 R Merid. par lon, D) 4 O=MI=Hc Eaft Sum ? Win. ? folfti fi the . toth in. ¢ lolitice North, Wel as Win, 3 ei, Sum. if C Mis South. . CI , merid. Mer. par. lat. ) @ @=MH=IC= vet RE of a contre fpec to CM, 10. THE variations from the merid. parallaxes for the given hour from noon, may be conceived to be made up, each of two parts; which are the projections of MG and GV upon CW for the lon. and upon CN for the lat.: The former be- ing HK, KB; and the latter IL, LA. For os which, befides the aie eS: re=- quifites, there is required Sine Verf. Sine ‘ cf the degrees from noon. Mc=2 Mx ie deg. 2 noon, Cof, lat. pl. S, deg. d@ noon cv=cok lat P x deg : Variation PHYSICAL anv LITERARY. 107 Variation of the Par. Lon. 240. ift Part = VGX == r KY rot I “4409 vrhen the fun is in jee vasa ge mt GV XS, merid. ang. Fatt AM. 2 Welt PM. Variation of the Par. LAT. >a ©. MG x S, mer. ang, esi! contr. to the decl.© rt Part= z “GV yx cof. merid. ang. R od Part = aw im - Forenoon oh when the fun is in § a Q is pared De Afternoon a mh § wnen the fun is ais in§ ioe - Sq Ps 3 t1. By art. 6. the part to be fubtracted from the apparent femid. © mutt bear the fame proportion to the whole, as the di- ftance of the vertex on the furface of the earth from its point on the difk, to the di- ftance of the points V, v; which i is nearly the fame with the femidiameter of the moon’s 108 ESSAYS anp OBSERVATIONS. moon’s orbit, and may always be ex~ prelied by a conftant number, viz. that of the 2ds of a degree equal to the radius of a circle, The diftance of the vertex from its point on the difk may be conceived to be made up of two parts, pofitive, or ne~ ative: The firft of which is the perpendi~ cular diftance of the centre of the given parallel circle from the plane of the difk 5 the fecond part is the perpendicular di- {tance of the given vertex from a plane pafling through the forefaid centre, and parallel to the difk. 5 i Pof. 7 when the Jat. pl. rt Pane’ lth x Sel. © § : Neg. § and dec], © are of $5 neo ipecies, different Cof. lat: pl. X cof. decl_ © X cof. deg. 2 noon See RR. oe ee Nene if the given. hour from: noon be - nea than 6+ 8 12. It would be eafy,. from the fore~ going rules, to conftruct tables of the pa- rallaxes for any given latitude. Such ta- bles would be fufficiently exact, Gf calcus lated for every third degree of the fun’s longitude, and every quarter of an hour from PHYSICAL anv LITERARY. tog ‘from noon to 6 hours, affuming 10000 for radius, or the horiz. par. »4@-. The equation to be fubtracted from the appa- rent femid. © needs only be calculated for every 10th degree of longitude, and every half hour from noon to 6 hours, taking the mean femid. ©, 13. Ir the given time from noon be more than 6 hours, fubtract it from 12 hours, and the long. © from 12 figns ; and, for the remaining time and longi- tude, feek the intire parallax, and the e- quation for the femid. ©, changing its fign. 14. SucH tables, tho’ conftructed for a particular latitude, may eafily be made to ferve for any other latitude. For the variations from the meridian parallaxes are always proportional to the cofine of Jatitude. And the meridian parallax, whether of long. or lat. is made up of the fum or difference of two parts; the firft of which is proportional to the fine, the fecond to the cofine of lat. Thefe two parts for the tabular latitude are found thus. To the given lon. © add 6 fens; and aro “ESSAYS Anp OBSERVATIONS | and take out the merid.. parallax anfwer-) ing to each longitude. Half the fum of. thefe gives the rift part, and half their difference the 2d part, to be added to the firft when the merid. par. for the given long. © is greater than the other, and to. be fubtracted when lefs. In like manner, the equation for the femid. © confifts of two parts; the 1ft of which is propor- tional to the fine, the 2d to the cofine of lat. The rf{t part is the equation for the given long. @, and 6 hours from noon; and this fabtra@ted from the equation for, the given long. © and hour from noon, gives the 2d part. 15 THE famerules will ferve for find- ing the moon’s parallaxes from a fixed ftar or planet. If the femid. of the planet have no fenfible magnitude, there will be no place for the correction mentioned in art.6. But, as the requifites could not be found from the common tables, if the {tar has latitude, it will be convenient, firft, to fuppofe it has none, and after=- wards to apply a proper correction. . Be- fides, the proceeding in this way will make . the PHYSICAL Anp LITERARY. 111 the tables already defcribed to be of the fame ufe as in folar eclipfes, fubftituting the long. * for the lon. ©, and, for the hour from noon, the equatorial diftance of the ftar’s ecliptic place from the meri- dian, converted into time at the common rate of 15 degrees to an hour. 16. Ir the {tar have latitude, then the true lon. and lat. ) #* are meafured by arches, from the center of the moon, per- pendicular to a circle of latitude, and to a great circle at right angles to it, both | pafling thro’ the ftar. Hence, As radius to cof, tr, lat. D, fo true lon. yp 4* to the fame projected. And, _ As cof. tr. lon. y. 2* to radius, fo tan. tr. lat. to the fame projected: Or, * without any fenfible error, fo tr. lat. > to the fame projected. 17. To find the correction of the paral- laxes for the latitude of a flar: Let CW (fig. 2.) be the ecliptic on the earth’s fur- | face, N its pole; CN a circle of latitude ' thro’ the ftar; W its pole; V the given vertex, 112 ESSAYS anp OBSERVATIONS vertex, CD, the lat. *, WVA a great cir- cle thro’ the vertex V, meeting with the circle of latitude in A; WD another great circle; VB, Vd, arches perpendicular to WC, WD. Then WA is a quadrant, and the fine of VA is the par. lon. ) 2 *, whe- ther the ftar has latitude or not: The fine of VB is the par. lat. if the ftar be in the ecliptic ; but, if it is in the circle WD, the par. lat. will be the fine of Vd; which may be found from the parallaxes of lon, and lat. given for the ecliptic place of the ftar: Thus, $, WV =Cof. VA= YR+ par. long x K—par. ion, R x S, VB (par. lat. | sn ee vVwi>= VWB ie CWO, if the lat. * be Ss, WV XS. VWS S, Vb —par. lat. Dée =o : R S,VWB — ; South, North. 18. Since the radius of the tables of fines and tangents was all along taken for the.horiz. par. >) 4 © or *; the parallaxes and equation found muft be altered pro- portionally. EXAM. E.113 ] FgS50$£9 6 ogglors'6 Egotv6l'6 ee ee 1gE661E°S Oz£gstry'6 hq poasayqo sem ‘ghL1 hr Aqnf ‘aydrppo sepoy aya Jo Suruurgaq ayy, = 10ZLSgL° - ] | cobtzed-6 nN 61g2S=W9 : : AD> | 1ge6OvE*S: “g§ 0690% = WO goowy “Sap *s | | 36795256 ‘© "3p *§ jd "327 Jon | EgoEv6L*6 *qd “ey JOD : : OW | | E125 93°6 “tN G046f = 507 mo a eel eS © re bike OGG Cer ad’ *uoow two3; s9213ep Sya -oggLorg*s 3 ( aug sraltse ct lo 6b gh “Sg[3ce ueipwsw ) a Hottest 6 rae £R0EP6L 6, ‘Jor 6EbbE6 G6: 00 {68 qr “€g0e]d aqi Jo 22F] Smad ‘9 2 4 1 Sen ee “ure of -b ,6.0q 01 “yotmuaatn Iw ‘AATAVyg aq © ‘ - C27 74 VS” Soe ++ x ® Vou. tr, 114 J C ae ; eae EEL esse ros a Ee ee ed i i crtiS Tet Mh linet pemenininiil) Cof. merid, ang. CM Merid. par, Jon D2O.F : as E. 9-3580017, S. merid, ang. 9.9384042 9.7227.902 CM - 9.7227902 9.0807919 | Merid, par. lat, 97111944 =51429,S. $ D465. ee Ee eed deneesnsieeibino ee aaisstiebinmenieemss senscisiatiae-aomoeuneuniimmibas jiemic smite. ¢ Variation of Par. Lon. Variation of Par. Lat. | | Cof. merid ang, 9 3580017 | S. merid. ang., 9.988 4042 MG 8.97657701 He | MG 8.7657701 ift Part=1330, E. 8.123 nit 'C xt Part=5678, S. 867541743 S merid, ang, 9. 9884042 | Cof, merid, ang, 9-35S001r7 GV 9-6350963 GV 9.6350963 2d Part—42024, E, 9 695 $095 | } ad Paat=98 42," N. 89930980 Total 43354, E, a | Totaby. “4164, N. Meiid, par. 12045; £, | pei par. 51427) S. : Par, lon, 55399) B. 9.743501 r3| | Par. lat = 47 47263; S. ‘9 6745213 Horiz. par. ) 4 @==53° 58” 3-5 103768 j- Horiz. par. D a4@ 3.5102968 Tr. par. lon )2O=29 54k. 3.25375 767) Tripar, lat. ) é©= 25"' 30" ps; 361 3.47981) - Tr, lon. D 26, W. = 58 34 Ww, E Tretat, p= 33-56, N, Vif} lon, ) 2@, W.- 28 40, W. MVif lat. Dé @Qm 8, 26, 'N.* Rehr. [ *papioae ‘asnjeout 3v938 e OF ‘os9q SI sjuasuey pur seoy josajqey oyi fq Surysom jo ayqno.y ay) se fuayRa Yonw ‘smn swe ay] ie *pue *aleindde B100) 19q}e4 eq 0} punofaq ‘uoyied -woa uodn ‘jm s3jas SuloSa10; ayy Aq suon -esodd ay3 syarga oq aad § aepiwy Arjaad aq 03 wae} vi spoyi2ui om} oy1 0g) tpuy ‘297d --wed jey3 mey aq as0jaq Sug] Sujim vi UNG gf1b010'r 69£9326z golzorsé sVLs$gorv 1$z6S5€g 6 LEL0610°6 36795756 6£7¥£63°6 4q W jo asouryqny oy pey oy aeq) “oaemU wy St i oeeetienemeeeiiaene’ O73 ye St - ‘LES 39 - o6zch = Luvg pe Lvege = Lavg yl | © ‘Pep 's 4 ' d EX AMY P LBA In the orbit of Mars, the mean diftance is to the excentricity as 152369 to T4100. Suppofing the mean anomaly to be’ 19, it is required to find the anomaly of the ex- centric, : The 144 ESSAYS snp OBSERVATIONS | The log. tang. of 30, half the angle AC3, is 7.9408 534. » The difference of the logs. of AS, SP is 0.0806086 The difference 78602408 is the log. tang. of 24°.9196814, half the difference of the angles CSB, C85; there- fore, the angle CSB, that is, the angle ACD, is £4'.9196814; and the angle CBS, that is, the angle BCD, is 5.0803186., Again, to determine the angle CDS, The log. tang. of half the angle ACD is 7,8958249 The difference of the logs. of AS, SP is 0.0806086 The difference 7.91 52163 is the log. tang. of 22°.4641426, half the difference of the angles CSD, CDS; there- fore the angle CDS, that is, theangle DCF, is 4'.995698I- Acatn, as the radius is to the fine of 5’.0803186, fo is 57°.2997795, Ot. the number of degrees in an angle fubtended by an arc equal to the radius, to the number pape th é 4 ~ PHYSICAL anv LITERARY. 145 mumber of degrees and minutes in an angle fubtended by an arc equal to the fine of 5’..803186. The log. of 57°.2957795 is —_ 1.7581226 The a fine of 5° See Is 7.1633313 The fum is 8.921453y The log. of radius is 10,0000900 The difference 249214539 _ The difference is the log. of 5’ .0073 162, he number of minutes contained in the angle A; the excefs therefore of the angle BCD, above ‘the angle A, is 0 .0930024. Again, as the fine of the angle BCD is to the tangent of the angle DCF, fo is 0,0930034 to the angle DCG, The log. of 0’.0930024 is —2.9684941 Thelog. tang. of the ang. DCFis7. 1622795 The fum is 6.1307736 The log. fine of the ang. BCD i 1.7. 1633313 2.9674423 ‘Vou. I, | sg ne 146 ESSAYS anv OBSERVATIONS is the log, of 0°.09277743 the angle DCG therefore is 00927774; therefore the angle ACG, the anomaly of the excentric,. is §5’.0124588, EXAMPLE HI. SupposinGc the mean anomaly in the fame orbit to be 45°, it is required to find the anomaly of the excentric. The log. tang. of 22° 30 is 9.6 172243 ‘The dif. of the logs. of AS, SPiso OBEGaBy The difference 9+53661 58 is the log. tang. of 18° §9°.1327325, half the difference of the angles CSB, CBS; the angle CSB, that is, the angle ACD, there= fore, is 41° 29'-1327325 3 and the angle CBS or BCD is 3° 30 .8672675. The log. tang. of half the angle “eae 9.5 783203 The diff. of the logs. of AS, SP is 0.080608 5 The difference 9.4977118 1S ee PHYSICAL anv LITERARY. 147 is the log. tang. of 17° 27°-7082672, half the difference of the angles CSD, CDS; the angle CDS or DCF, therefore, is 3°16°858099. Again, as radius is to the fie of the angle BCD, fo is 57° Wiatonians &c. to the angle A. The log. of 57°.2957795, &ce is 1.7581226 The log. fine of the angle BCD is 8.7874623 eel The fum is 10 5455849 The log. of rad. is 10.0000000 ‘The difference re 5455849 is the log. of 3°.5122459; the angle A, therefore, is 3°. 30%.734754; the excefs of the angle BCD above the angle A is 071325135. Again, as the fine of the angle BCD is to the sei 0 of the angle SDC or DCF, fo is 071325135 to hie an- gle DCG. The log. of 0%1325135is —z.1222601 The log. tang. of the angle SDC Bore is 8.7583537 The fum is 7-8806138 The 148 FSSAYS anp OBSERVATIONS — The log. fine of the angle BCD is’ iy" 8.7874623 eT The difference —1,0931515 is the log. of 641239228; the angle DCG, therefore, is 0.1239228; therefore the angle ACG, the anomaly of the excentric, is 41° 2942566553. | EXAMPLE Iv. AGAIN, in the fame orbit, fuppofing the mean anomaly to be 100° degrees, it is required to find the anomaly of the ex- centric. The log. tang. of 50°, half the angle ACB is TO. 0761865 The difference of the logs. of AS, SP is . 0.0806086 t 3 The difference 9-9.55779 is the log. tang. of 44° 42 -4982192, half the difference of the angles CSB, CBS ; therefore the angle CSB, that is, the an- gle ACD, is 94° 42". ie and the angle _ PHYSICAL anv LITERARY. 149 angle CBS, that is, the angle BCD, is §°17'-5017808, Again, to determine the angle CDS, Thelog. tang. of half the angle ACD is.’ 10.055728¢ The difference of the logs. of na AS, SP is Weipa 0.0806086 The difference 9: 9751199 is the log. tang. of 43°21° ~ 5819834, half the difference of the angles CSD, CDS ; therefore the eagle CDS, that is, the angle DCF, is 3°59’. 6671212. AGAIN, as the radius is to the fine of 17. -5017808 the angle BCD, fo is 57°.2997795 to the angle A, The log. of §7°.2957795 is 1-7581226 The log. fine of Sa 17 45017808 is — 8.9642388 The fum is 19.7223607 The log. of radius is 10, 0000000 _ ‘The difference 0.7223607 Is ryo ESSAYS anp OBSERVATIONS is the log. of 5° 16’.600752, the number of degrees and minutes contained in the angle A; the excefs therefore of the an- gle BCD above the angle A is 0’.9010288, Again, as the fine of the angle BCD is to the tangent of the angle DCF, fo is 079010288 to the angle DCG. . The log. of 079010288 is —1.9547387 The log. tang. of the angle DCF is. 8.8440431 The fum is 8.797818 The log. fine of the angle | BOD is 8.9642381 The difference —1.8345437 is the log of 06831934; the angle DCG therefore is 0+68319343; therefore the angle ACG the anomaly of the excentric is 94° 437.1814126, Tue three laft examples are taken from Dr Keil’s aftronomical Lectures, Lecture 23- and the numbers agree very nearly with his. | In PHYSICAL ann LITERARY. 15% In the orbits of Mercury and Mars, if the excefs of the angle BCD above the angle A be added to the angle ACD, the fum will be nearly the anomaly of the excentric reckoned from the aphelion. In orbits of {mall excentricity, the an= gle ACD is nearly the anomaly of the ex- centric; thérefore the following rule will give the anomaly of the excentric very nearly. | From the logarithmic tangent of half the mean anomaly, fubtract the difference of the logarithms of the aphelion and pe- rihelion diftances; the remainder is the logarithmic tangent of an angle, which eall B: To the angle B, add half the mean anomaly ; the fum will give very nearly the anomaly of the excentric. | 4 EXAMPLE V. In the earth’s orbit, the mean diftance is to the excentricity as 100000 to 1691. Suppofe the mean anomaly from the | aphelion 152 ESSAYS anv OBSERVATIONS aphelion to be 30°, it is required to find the anomaly of the excentric. The log. tang. of 15° is 9.4280525 The diff. of the logs. of AS, SP is 0.0146892 The difference 9.4133633 is the log. tang. of 14° 31/.3670421, half the difference of the angles CSB, CBS ; therefore the angle CSB, that is the an- gle ACD, is 29° 31/.367042; therefore the anomaly of the excentric is nearly 39°31 .3670421, that is 29° 31/22'’.022526, which agrees very nearly with Dr Keii’s numbers in the forefaid Lecture. EXAMPLE VE AGAIN, in the earth’s orbit, fuppofe the mean anomaly to be 60°, it is re- quired to find the anomaly of the ex- centric. The log. tang. of 30, is 9-7614394 The diff. of the logs. of AS, SP is 0.0146892 The difference 9.9467 502i IS = eee. PHYSICAL anv LITERARY. 153 _ _ is the log. tang. of 29° 10°.081573, half the difference of the angles CSB, CBS; therefore the angle CSB, that is, the angle ACD, is 59° 10°.081873 3; there- fore the anomaly of the excentric is near- ly 59°10 .081873. EXAMPLE VIL. In the orbit of Venus, the mean di- {tance is to the excentricity as 10000000 to 6y855. Suppofe the mean anomaly reckoned from the aphelion to be 60°, it is required to find the anomaly of the ex- centric. The log. tang. of 30° is '9.7614394 The diff. of the logs, of AS,SP | is 0-0060677 The difference 9°7553717 is the log. tang. of 29° 39 «2739959, half the difference of the angles CSC, CBS; therefore the angle CSB, that is, the angie - ACD, is 590 39%2739959 3 therefore the VoL. H. © U- anomaly 154 ESSAYS anp OBSERVATIONS ancmaly of the excentric is nearly 59° 39 .2739959, that is 59° 39'.16' 439754. Ir the mean anomally reckoned from the perihelion be 120°, the anomaly of the excentric would be nearly 120° 20.43 -560246, which agrees very nearé Ty with Mr Machin’s numbers in the forecited TranfaGtion. THE anomaly of the excentric being found, the coequate or true anomaly will be found by the refolution of the triangle GCS: Thus, from the log. tang. of half the anomaly of the excentric, fubtraé the difference of the logs. of the aphelion and perihelion diftances, the remainder will be the leg. tang. of an angle; to this an- gle add half the anomaly of the excentric 5 let the fum be called the angle C; to the log. tang, of the angle €, add half the fum of the logs. of the apkelion and pe- rihelron diftances ; from this fum, fub= tra the log. ‘of the mean diftance; the remainder ‘will be the log. tang. of the coequate or true anomaly. Lit CL be the leffer axis of the planet’s orbit, Becaufe, from the nature of the ellipfe, : ae PHYSICAL ann LITERARY. 155 ellipfe, the fquare of CL is. equal to the rectangle ASP, the log. of CL will be equal to half the fum of the logs. of AS, SP: And, becaufe the tangent of the angle KSH. is to the tangent of the angle GSH as HK to HG; that is, from the nature of the ellipfe, as LC to CA; therefore, if to the log. tang. of the angle GSH, the log. of CL be added, and from the fum the log. of AC be fubtraéted, the remainder will be the log. tang. of the angle KSH. Acatrn, the fine of the true anomaly is to the fine of the anomaly of the excen- tric, as the leffer axis of the orbit to the diftance of the planet from the fun. - Because CL is to HK as C3 to GH, that is, as the radius to the fine of the a- maly of the excentric, and HK is to KS as the fine of the true anomaly to the radius ; therefore CL is to KS as the fine of the true anomaly to the anomaly of the excentric. THE place of a planet in an met or- bit [granting the quadrature of the el- lipfe} may be found at any given time within a fmall limit, by tne following theorem. THEOREM 156 ESSAYS anp OBSERVATIONS THEOREM. Fic. 7. Let the ellinfe, whofe greater axis is AP, foci S, ix, 2ndcenter C, reprefent the orbit of a planet round the fun at 5; and, fuppofing the periodic time of the planet round the fun to be known, and likeways the time the planet pafled through the aphelion A: As the perio- dic time of the planet round the fun, is to the time elapfed fince the planet paffed through the point A, fo let the area of the ellipfe be to the fector ACB; join SB, and draw CD parallel to SB on the fame fide of AP that SB is; and let OD be equal to CA; join SD; Tet CD, SD, meet the ellipfe in E, F: The true place of the planet is between the points E, F; that is, the planet is paf- fed the point E, but not come to the point F, rs Let G be the place of the planet; join SG, and join BD meeting AP in H, and join y PHYSICAL anv LITERARY. 157 join KB; draw SL parallel to KB meeting * BDin L. Becaufe CD is. parallel to SB,- CD will be to SB as CH to HS ; therefore, twice CD will be to SB as twice CH to HS. ‘But, becaufe twice CD is equal to AP, that is, equal to KB together with BS, and twice CH is equal to KH together with HS; therefore KB together with BS will > be to KS as KH together with HS is'to HS ; ; aad therefore KB will be to BS as KH to HS, that is, as KB to SL; there- fore BS, SL are equal: Therefore the an: gle SBL is equal to the angle SLB, that is, equal to the angle KBD ; and therefore, froin a known property of the ellipfe, BD is a tangent to the ellipfe at the point B; and therefore | Prop. 2.) the fector ACB | is greater than the fector ASE, and lefs | than the fector ASF: But, becaufe Gi is the place of the planet, the area of the ellipfe will be to the feétor ASG as the periodic time of the planet round the fun is to the time clapfed fince the planet paffed thro’ the point A, that is, as the area of the el- lipfe to the fector ACB ; therefore the fec- tor ASG is equal to the fe@or ACB; and aa therefore ‘ 158 ESSAYS anp OBSERVATIONS. therefore the fe¢tor ASG is greater than the feftor ASE, and lefs than the fector ASF; therefore the line SG falls between the lines SE, SF; and therefore G, the place of the planet, is between the points E, F; therefore the planet has pafled the ‘point E, but not come to.the point F. Joy te os - PHYSICAL aNp LITERARY. 159 ARTs VEL Of the Cold produced by evaporating Fluids, and of fome other Means of producing Cold ; by Dr WiLuiaMm CULLEN, Profeffor of Medicine in the Univerfity of Glafgow *. Young gentleman, one of my pupils, whom [had employed to examine the heat or cold that might be produced by the folution of certain fubftances in fpirit of wine, obferved to me, That, when a ther- mometer had been immerfed in fpirit of wine, tho’ the fpirit was exactly of the temperature of the furrounding air, or | _ fomewhat colder; yet, upon taking the | . thermometer out of the fpirit, and fufpend- ing it in the air, the mercury in the ther- - mometer, which was of Farenheit’s con- ftruGtion, always funk two or three de- grees. ‘This recalled to my mind fome experiments and obfervations of M. de ' Mairan to the fame purpofe; which I had read fome time before. See Dzfertation : fur pr May 1. 1755. 160 ESSAYS 4nd OBSERVATIONS Jur la glace, edit. 1749 pag. 248. et eq. When I firft read the experiments of M, de Mairan in the place referred to, I fuf- pected that water, and perhaps other fluids, in evaporating, produced, or, as the phrafe is, generated fome degree of cold. The above experiment of my pupil confir- med my fufpicion, and engaged me to. verify it by a variety of new trials. I began by repeating the experiment with fpirit of wine; and found, when I had taken the utmoft care to have the {pi- rit exactly of the temperature of the air, that conftantly however, upon taking the thermometer out of the fpirit, the mer~ cury funk feveral degrees, and indeed con- tinued to fink fo long as the ball of the thermometer continued wet with the fpirit of wine. I found alfo, when the ball be- _ gan to dry, and the mercury to rife again in the ftem of the thermometer, that, if the ball was again dipped into the {pirit, and immediately taken out, the mercury - in the thermometer might be again obfer- ved to fink, and that thus, by repeated dippings, the cold produced might be ren- dered PHYSICAL ann LITERARY. 161 dered very remarkable.. The cold produ- ‘ced was alfo obfetved to be ftill greater, when, between each dipping, the thermo~ meter was moved very nimbly to and fro in the air; or if, while the ball was wet with fpirit of wine, it was blown upon by a pair of bellows, or indeed if the air a- bout the ball was otherwife any how put in motion. If any of thefe means for putting the air in motion are employed; the repeated moiftenings of the ball of the thermometer’ may be performed by dip- | ping it into the fpirit of wine. But, when | a certain degree of cold has been produ- ced by a firft dipping, that is apt to be - diminifhed by dipping again into. the ‘warmer {pirit; and therefore the thermo- meter ought either to be dipped into the fpirit and taken out again very quickly, or, what is ftill better, the ball of the ther- mometer ought to be moiftened by a fea- ther that has been dipped into the fpirit of wine. By taking thefe methods, I have, by fpirit of wine, made the mercury in the _ thermometer fink from 44 degrees to be-: low the freezing point; and, by employing PV ou, Il. X fome © 162 ESSAYS anp OBSERVATIONS | fome other fluids to be mentioned by and by, I have produced a finking of the ther- mometer much more confiderable. In making experiments of this kind, it is to be obferved, that the cold produced is of very fhort duration. On this account it is not proper to employ a thermometer inclofed in a glafs tube; and itis neceflary to employ one having a fmall ball, which may render it more fenfible- But, asa fmall ball occafiens the divifions of the {cale to be the fmaller, a thermometer fil- led with quick filver is not fo proper for thefe experiments, as one filled with fpirit of wine; having at the fame time both a fmall ball and a flender ftem. What beft of all fhews the cold produced, and is in- deed, with refpeé to feveral fluids, quite neceflary, is an air thermometer. This too will be rendered more convenient by having the upper part of the tube bent as in the figure an- nexed, fo that the ball may | be moiftened without the li- | quor’s running down upon the {tem and {cale. PHYSICAL anv LITERARY. 163 Ihave entered into this detail for the fake of thofe who may defire to repeat my ex- ‘periments. Having now faid enough on the manner of .making them, I go’on to obferve, that in this way I have examined a great variety of fluids. Such as, The guick-lime fpirit of fal. ammoniac, The ether of Frobenius, The nitrous ether, The volatile tincture of fulpbur, Spirit of wine, Spirit of fal. ammoniac made with the fixed alkali, Brandy, Wine, Vinegar, Water, Oil of turpentine, Oil of mint, Oil of pimento. By each of thefe employed to moiften i. the ball of the thermometer, fome degree _ of coid is produced. ‘I dare not however at prefent determine exactly what is the finking 164 ESSAYS anp OBSERVATIONS. finking of the thermometer. produced by each, .For this purpofe, it would be necef- fary to repeat the trials often and with pre- cifely the fame circumftances at each time: “Which I find to be very difficult. In the mean time I have endeavoured to give a notion of the comparative power of thefe fluids in producing cold, by the order in which I have fec them down; having men- — ‘tioned that fluid firft which feemed to me to occafion the greateit finking of the ther- moméeter, and the reft follow in order as they feemed to occafion lefs and lefs. From the above enumeration I ima- gine it will appear, that the power of eva- porating fluids in producing cold, is near- ly according to the degree of volatility in each. If to this we join the confideration, that the cold is made greater by whatever haftens the evaporation, and particularly, that the finking of the thermometer is greater as the air in which the experiment is made is warmer, if dry at the fame time ; I think we may now conclude, that the cold produced is the effect of evaporation. ——— PHYSICAL anv LITERARY. 165 I did not think it neceflary to diverfify my experiments further by examining a great many fluids, which. are manifeftly of a like nature with thefe above mention- ed. I prefume pretty confidently, that the feveral {pirituous, watery, and oily fluids, akin to thefe already tried, will be found ‘all of them to have fimilar effects. And, confidering how many fluids thefe clafles comprehend, and that, in thefe already tried, the cold produced feems to depend more on the volatility of the aggregate than on the nature of the mixt; I was ready to conclude, that all fluids whate- ver would, in evaporating, produce cold, But I have found a feeming exception, When the ball of the thermometer is moi- ftened with any of the foilil acids, a con- fiderable degree of heat is produced. It is however to be doubted, if this affords an exception, We know that thefe acids attract water from the air ; and alfo that thefe acids, mixed with water, always pro- duce heat: It may therefore be fuppofed, that the heat produced by moiftening the ball of the thermometer with thefe acids, is ‘ Srey on ce, 166 ESSAYS anp OBSERVATIONS is to be imputed rather to their mixing with the water of the air, than to their e- vaporation fingly. This perhaps cannot be pofitively determined, till the evapora- tion of thefe acids, in a very perfect va- cuum, is examined ; which I have not yet had an opportunity of doing. In the mean time, I have made an experiment which I think is to the purpofe. To one part of ftrong acid of vitriol, I added two parts of {pring-water. When this mixture, which produces a great degree of heat, was returned to the temperature of the air, I ufed it for moiftening the ball of the thermometer, and found it produced a fen- fible degree of cold, and feemingly a great- er than water alone would have done. I need not here obferve, that the mixture I ufed was ftill a very acid liquor, only fo much faturated with water, that it would not now attract any from the air. Whe- ther it would not have had the fame effed, tho’ lefs diluted, I have not had time to examine. ‘The experiment, as it ftands, tends to prove, that the heat produced by acids, applied to the ball of the thermo- meter, PHYSICAL anv LITERARY. 167 meter, is owing to the mixture of thefe with the water of the air; and therefore, it is ftill very probable, that all fluids, which do not immediately affeét the mix- ture of the air, will, in evaporating, pro ‘ duce cold. | WHEN J had proceeded thus far, I be- gan toconfider, whether the cold produced in the above experiments might not be the effet of the mixture of the feveral fluids with the air; and that therefore, toa lift of cooling mixtures and folutions which I was then making up, I fhould now add the feveral folutions made by the air. By one who fuppofes the evaporation of fluids to depend upon the action of the air as a menftruum, this would be readily admit- ted; but, as I knew that fluids evaporate mm vacuo as well as in the air, 1 refolved to fufpend my opinion, till I fhould repeat my experiments in an exhaufted receiver. In profecuting thefe, a number of new, _and,to me, curious phenomena have prefent- ed themfelves; fo many, that I find the experiments muft be often repeated, and art diverfified, before I can give the pecety 168 ESSAYS anp OBSERVATIONS fociety a proper account of them. In the mean time, I fhall give you the following facts already fufficiently verified. A thermometer hung in the receiver of an air pump, finks always two or three degrees upon the air’s being exhaufteds After a little time, the thermometer za va- cuo returns to the temperature of the air in the chamber, and, upon letting air a- gain into the receiver, the thermometer always rifes two or three degrees above the temperature of the external air. WHEN aveflel containing fpirit of wine, with a thermometer immerfed in it, is fet under the receiver of an air-pump ; upon exhaufting the air, the mercury in the thermometer finks feveral degrees. It be- comes miore efpecially remarkable when the air in any plenty iffues out of the fpi- rit of wine. As the {pirit continues long to give out air, fo it is long before the thermometer immerfed in it returns to the temperature of the external air. But when after fome time it appears {tationary, if it is then drawn up out of the fpirits and fufpended in. the vacuum, the mercury finks PHYSICAL ann LITERARY. 169. finks very quickly eight or nine degrees 5” a good deal farther than it would have done in the fame circumftances ih the air, In the fame manner as in the air, the ther- mometer im vacuo may be made to fink lower by repeated dippings into the fpirit of wine: Buthere thefe repeated dippings _ have not fo remarkable an effect as in the air; becaufe the dipping cannot be fo - guickly performed, and the thermometer is therefore more affected by the warmth of the fpirit. It is fometimes alfo affect- ed by a drop of the fpirit which the ball takes up along with it, and which, as I fhould have obferved above, ought always to be taken away in the experiments made ° in the air. This experiment with {pirit of wine was often enough repeated, to fhew elearly, that the evaporation of the foirit im vacuo produces a greater degree of cold than the evaporation of the fame in the p sir. , ' | 'SaTisFreD of this, I have tried alfo fome other fluids, as the quick-lime fpirit of fal, ammoniac, and the two kinds of | ether. Veffels containing thefe with a Sevo., li. ¥ ther- ‘ 179 ESSAYS anp OBSERVATIONS © thermometer immerfed in the liquor, but feparately and at different times, were fet under the receiver. With regard to the different fluids, the p/ezomena were much the fame. Upon exhaufting the receiver, the fluid gave out a great quantity of e- laftic air; and, while this happened, the mercury in the immerfed thermometer funk very faft and to-a great length. In our trials,it generally funk below the fcale applied, fo that we could not meafure ex- actly how far. In one experiment, before exhaufting the receiver, the thermometer had flood at 50 degrees, and, after exhauft- ing, we could judge very certainly that it funk tobelow 20. In another experiment made with the nitrous aether, when the’ heat of the air was about ¢3 degrees, we fet the vefft] containing the aether in ano~ ther a little larger containing water. Up- on exhaufting the receiver, and the veflel’s: remaining for a few minutes iz vacuo, we found the moft part of the water. frozen,. and the veflel containing the aether fur- rounded with a thick and firm cruft of ice. Secu PHYSICAL anv LLTERARY. 171 Sucu a means of producing cold, and to fo greata degree, has not, fo far asf know, been obferved before, and it feems to deferve being further examined by ex- _ periments. Till that is done, 1 do not chufe to give any account of fome other remarkable phaenomena that have occurred in the above experiments, nor to enter in- to the feveral fpeculations that the fubject feems to fuggett. SINCE writing the above, I have had occafion to obferve, that Mr Richman of the Academy of Peterfburg has taken no- tice of the effect of evaporating fluids in _ producing cold; but does not impute it ‘to the evaporation alone. His 'very exact account of the phenomena, and his theory with regard to them, may be feen in Nov. Comment. Atad. Petiopolitanae ad aun, 1747 & 1748, page 284. ) | ART. A ahi 172 ESSAYS anp OBSERVATIONS AR Tas, Wikis Experiments upon Magnefia alba, Quicklime, and fome other Alcaline Subftances 3 by Joseru Brack, M. D.* PART I, Tt OFF MAN, in one of his obferva- tions, gives the hiftory of a powder called magnefia alla. which had been long ufed and efteemed as a mild and taftelefs purgative; but the method of preparing it was not generally known before he made it public fT. Ir was originally obtained from a li- quor called the mother of nitre; which is produced in the following manner, SaLT-PETRE is feparated from the brine which firft affords it, or from the water with which it is wafhed out of ni~ trous * June 5.1755, + Hoff. op. T. 4. p. 479- PHYSICAL ano LITERARY. 173. trous earths, by the procefs commonly u- fed in cryftallizing falts. In this procefs the brine is gradually diminifhed, and at length reduced to a {mall quantity of an unctuous bitter faline liquor, affording no more falt-petre by evaporation; but, if urged with a brifk fire, drying up intoa confufed mafs which attracts water ftrong: ly, and becomes fluid again when expofed - to the open air. | | To this liquor the workmen have gi- ven the name of the mother of nitre; and Hoffman, finding it compofed of the mag- _ nefia united to an acid, obtained a fepara- tion of thefe, either by expofing the com- pound to a ftrong fire in which the acid was diflipated and the m:juefta remained behind, or by the addition of an-alkali _ which attraéted the acid to itfelf: And this laft method he recommends as the beft. He likewife makes an inquiry into the nature and virtues of the powder thus prepared ; and obferves, that it is an aul forbent earth which joins readily with all acids, and mutft neceffarily deftroy any a- cidity it meets in the ftomach; but thae 1C§ 174 ESSAYS ann OBSERVATIONS its purgative power is uncertain, for fome- times it has not the leaft effe@ of that kind. As it isa mere infipid earth, he rationally concludes it to be a purgative only when converted into a fort of neutral falt by an acid in the ftomach, and chat its effect is therefore proportional to the quantity of this ad@d. ALTHOUGH magnefia appears from this hiftory of it to be a very innocent medi- cine; yet, having obferved, that fome hy- pochondriacs who ufed it frequently, were fubject to flatulencies and f{pafms, he feems to have fufpected it of fome noxious qua- lity. The circumftances however which gave rife to his fufpicion, may very pofii- bly have proceeded from the imprudence of his patients, who, trufting too much to magnefia, (which is properly a palliative in that difcafe, ) and neglecting the affiftance of other remedies, allowed their diforder to increafe upon.them. It may indeed be alledged, that magnefia, as a purgative, is not the molt eligible medicine for fuch confiitutions, as they agree beft with thofe that ftrengthen, ftimulate, and warm ; which . PHYSICAL anv LITERARY. 175 which the faline purges commonly ufed are not obferved to do. But there feems at leaft to be no objeCtion to its ufe when children are troubled with an acid in their ftomach; for gentle purging in this cafe is very proper, and it is often more con- - veniently procured by means of magnefia than of any other medicine, on account ef its being intirely infipid. THE above mentioned author obfer- ving, fome time after, that a bitter faline liquor, fimilar to that obtained from the brine of falt-petre, was likewife produced by the evaporation of thofe waters which contain common falt, had the curiofity to try if this would alfo yielda maznefia, The experiment fucceeded : And he thus found eut another procefs for obtaining this powder, and at the fame time affured himfelf by experiments, that the product from both was exadlly the fame*. My curiofity led me fome time ago to inquire more particularly into the nature of magncfia, and efpecially to compare its L pro- , ® Hoff, Op. T. 4. p. 500% 176 ESSAYS snp OBSERVATIONS properties with thofe of the other abfor- bent earths, of which there plainly appear- ed to me to be very different kinds, altho’ commonly confounded together under one name. | was indeed led to this examina- tion of the abforbent earths, partly by the hope of difcovering a new fort of lime and lime-water, which might poflibly be a more powerful folvent of the ftone than that commonly ufed ; but was diflappoint- ed in my expectations, ‘Ihave had no opportunity of feeing Hoffman’s firft, magnefia, or the liquor from which it is prepared, and have therefore been obliged to makemy cxRenmea up- on the fecond. In order to prepare it, I at firft e aploy- ed the bitter faline liquor called bittern, which remains in the pans after the eva- poration of fea-water. But, as that liquor is not always eafily procured, I afterwards made ufe of a fait called Ep/om falt, which is feparated from the bittern by cryftalli~ zation, and is evidently compofed of mag nefia and the vitriolic acid, THERE PHYSICAL anp LITERARY. 177 THERE is likewife a fpurious kind of Glauber falt, which yields plenty of mag- nefia, and feems to be no other than Epfom falt of fea water teduced to cryftals ofa larger fize. And common {alt alfo affords a {mall quantity of this powder ; becaufe, being feparated from the bittern by.one hafty cryftallization, only, it neceffarily contains a portion of that liquor. THOSE who would prepare a maguefia _ from Epfom falt, may ufe the following procefs. , DissOLve equal quantities of Epfom falt,and of pearl afhes feparately, in a fuf- ficient quantity of water; purify each fo- lution from its dregs, and mix them ac- curately together by violent agitation: Then make them juft to boil overa brifk fire. , : | App now to the mixture three or four times its quantity of hot water; after a little agitation, allow the magunefia to fet- tle to the bottom, and decant off as much F of the water as poflible. Pour on the ~ fame quantity of cold water; and, -after 4 fettling, decant it off in the fame manner, : VOL, II. Mee Repeat 178 ESSAYS anp OBSERVATIONS | Repeat this wafhing with the cold water ten or twelve times, or even Oftner, if the magnefia be required perfectly pure for che- mical experiments. WHEN it is fufficiently wafhed, the wa- ter may be ftrained and fqueezed from it in a linen cloth; for very little of the —, nefia pafles through. THE alkaliin the mixture uniting with the acid, feparates it from the magnefia; which, not being of itfelf foluble in water, muft confequently appear immediately undera folid form. But the powder which thus appears is not intirely magnefia; part of it is the neutral falt formed from the union of the acid and alkali. This neu- tral falt.is found, upon examination, to a- gree in all refpects with vitriolated tartar, and requires a large quantity of hot wa- ter to diffolve it. As much of it is there- fore diffolved as the water can take up; _ the reft is difperfed through the mixture in the form of a powder. Hence the necef- fity of wafhing the magnefia with fo much trouble; for the firft affufion of hot water is intended to diffolve the whole of the — falt, PHYSICAL anp LITERARY. 179 falt, and the fubfequent additions of cold water to wafh away this folution. THEcaution given of boiling the mixture is not unneceffary ; if it be neglected, the whole of the magnefia is not accurately {e- parated at once; and, by allowing it to reft for fome time, that powder concretes into minute grains, which, when viewed with the microfcope, appear to be affemblages of needles diverging from a point. This happens more efpecially. when the folution of the Epfom-falt and of the alkali are di- luted with too much water before they are mixed together. Thus,if a dram of Epfom “falt and of falt of tartar be diffolved each in four ounces of water,and be mixed,and . then allowed to reft three or four days, the whole of the magnefa will be formed into thefe grains. Or, if we filtrate the mixture foon after it is made, and heat the clear liquor which pafles through, it will be- _ come turbid, and depofite a magnefia. _ Thad the curiofity to fatisfy myfelf of pete purgative power of magnefia, and of “Hoffman's opinion concerning it, by the following eafy experiment. I made a neu- Oa. | tral 180 ESSAYS anp OBSERVATIONS. tral falt of magnefia and diftilled vinegar; chufing this acid as being, like that in weak ftomachs, the product of fermenta- tion. Six drams of this I diffolved in wa- ter, and gave to a middle-aged man, de- fring him to take it by degrees, After having taken about a third, he defifted, and purged four times in an eafy and gen- tle manner. A woman of a {trong con= {titution got the remainder as a brifk pur- gative, and it operated ten times without caufing any uneafinefs, The tafte of this falt is not difagreeable, and it appears to be rather of the cooling than of the acrid kind. Havine thus given a fhort fketch of the hiftory and medical virtues of mague- fia, 1 now proceed to an account of its chemical properties. By my firft experix, q ments, {intended to learn what fort of neu- tral falts might be obtained by joining it to each of the vulgar acids; and the re- fult was as follows. MacGNeEsia is quickly diffolved with violent effervefcence, or explofion of air, © _ by the acids of vitriol, nitre, and of com-_ mon Pa al = 2 = PHYSICAL ann LITERARY. 181 mon falt, and by diftilled vinegar; the neutral faline liquors thence produced having each their peculiar properties, TuaT which is made with the vitriolic acid may be condenfed into cryftals fi- milar in all refpects to Epfom fale. THAT which is made with the nitrous is of a yellow colour, and yields faline cryftals, which retain their form in a ve- ry dry air, but melt in a moift one. TuaT which is produced by means of fpirit of falt, yields no cryftals; and, if e- vaporated to drynefs, foon melts ia when expofed to the air. THAT which is obtained from the uni- on of diftilled vinegar with magnefia, af- fords no cryftals by evaporation, but is condenfed into a faline mafs, which, while warm, is extremely tough and vifcid, very much refembling a ftrong glue both in colour and confiitence, and becomes brit- tle when cold. By thefe experiments magnefia appears to bea fubftance very different from thofe of the calcarious clafs; under which I would be underftood to comprehend all thofe 182 ESSAYS AND OBSERVATIONS thofe that are converted into a perfect quick-lime in a {trong fire, fuch as lime- f{tone, marble, chalk, thofe {pars and marles which effervefce with aqua fortis, all ani- mal fhells, and the bodies called /ithophyta, All of thefe, by being joined with acids, yield a fet of compounds which are very different from thofe we have juft now de- feribed. Thus, if a fmall quantity of any calcarious matter be reduced to a fine pow- der and-thrown into fpirit of vitriol, it is attacked by this acid with a brifk effervef- cence; but little or no diffolution enfues. It abforbs the acid, and remains united with it in the form of a white powder, at the bottom of the veflel, while the li- quor has hardly any tafte, and fhews only a very light cloud upon the addition of an alkali*. THE * Mr Margraaf has lately demoniftrated, by a fet of curious and accurate experiments, that this powder is of the nature, and pofleffes the properties, of the gypfeous cr felenitic fubftances, That fuch fubftances can be re- folved into vitriolic acid and calcarious earth, and can be again compofed by joining thefe two ingredients to- gether. Mem de l’Acad. de Berlin, an. 1750, p. 144. PHYSICAL anv LITERARY. 183 THE fame white powder is alfo formed when fpirit of vitriol is added to a calca= rious earth diffolved in any other acid; the vitriolic expelling the other acid, and joining itfelf to the earth by a ftronger attraction; and upon this account the magnefia of fea~water feems to be different from either of thofe defcribed by Moffman, He fays exprefsly, that the folutions of each of his powders, or, what is equivalent, that the liquors from which they are ob- tain, formed a coagulum, and depofited a white powder, when he added the vitri- olic acid *; which experiment J have often tried with the marine bittern, but without fuccefs. ‘The coagulum thus formed in * the mother of nitre may be owing to a quantity of quick-lime contained in it; for quick-lime is ufed in extracting the falt-petre from its matrix, But it is more difficult to account for the difference be- _ tween Hoffman’s bittern and ours, unlefs _ we will befatisfied to refer it tothis, that he got his from the waters of falt {prings, which ‘dl Hoff, Op, ‘FE: 4 Pp. 480 & 500» 184. ESSAYS anp OBSERVATIONS which may poflibly be different from thofé of the fea, Macngsta is not lefs remarkably di- ftinguifhed from the calcarious earths, by joining it to the nitrous and vegetable a- cids, than to the vitriolic. Thofe earths, when combined with fpirit of nitre, can- not be reduced to a cryftalline form, and, if they are diffolved in diftilled vinegar, the mixture fpontaneoufly dries up in a friable fale. Havinc thus found magunefia to differ from the common alkaline earths, the ob- ject of my next inquiry was.its peculiar de- gree of attraction for acids, or what was the place due to it in Mr Geoffroy’s table of elective attractions. THREE drams of magnefia in fine pow- . der, an ounce of falt ammoniac, and fix ounces of water, were mixed together, and digefted fix days in a retort joined toa re- ceiver. Durinc the wholetime, the neck of the retort was pointed a little upwards, andthe — moft watery part of the vapour, which — was condenfed there, fell back into its bo- dy. PHYSICAL anp LITERARY. 185 dy. In the beginning of the experiment, a volatile falt was therefore collected in a dry form in the receiver, and afterwards diffolved into fpirit. WHEN all was cool, I found in the re- tort a faline liquor, fome undiffolved mag- — nefia, and fome falt ammoniac cpyftallized. The faline liquor was feparated from tae other two, and then mixed with the alka- line fpirit. A coagulum was immediate- ly formed, and a magnefia precipitated from the mixture, THE magne(iawhich had remained in the retort, when well wafhed and dried, weigh- ed two {cruples and fifteen grains, WE learn by the latter part of this ex- periment, that the attra@iion of the vola- tile alkali for acids is {tronger than that of magnefia, fince it feparated this powder from the acid to which it was joined. But it alfo appears, that a gentle heat is capa- ble of overcoming this fuperiority of at- traction, and of gradually elevating the alkali, while it leaves the lefs volatile acid with the magnefia, ~ Vou. Il. Aa Dis- 186 ESSAYS anp OBSERVATIONS ~ Dissotve a dram of any calcarious fubftance in the acid of nitre or of com- non falt, taking care that the folution be rendered perfectly neutral, or that no fu- perfluous acid be added. Mix with this folution a dram of magnefia in fine powder, and digett, it in the heat of boiling water about twenty four hours; then dilute the mixture with double its quantity of water, and filtrate.” The greateft part of the earth now left in the filtre is calcarious, and the liquor which pafled through, if mixed with a diffolved alkali, yields a white powder, the largeft portion of which , is a true magnefia, From this experiment it appears, that an acid quits a calcarious earth to join it- felf to magnefia; but the exchange being performed flowly, fome of the magnefia is fill undiffolved, and part of the calcarious earth remains yet joined to the acid. WHEN a fmall quantity of magnefia is thrown into a folution of the corrofive fublimate of mercury, it foon feparates part of the mercury in the form of a dark fed powder, and is itfelf diffolved. IMa* PHYSICAL anp LITERARY. 187 ' IMacrtninc thatT perceived fome re- femblance between the properties of mag- néfia and thofe of alkalis, I was led to try what change this fubftance would foffer from the addition of quick-lime, which alters in fuch a peculiar manner the alka- line falts. TwENTY feven grains of magrefia in fine powder were mixed with eighteen ounces of lime-water in a flafk, which was corked clofe and fhaken frequently for four days. During this time, | frequent: ly dipp’d into it little bits of paper, which were coloured with the juice of violets ; and thefe became green as foon as they touched the water, until the fourth day, when their colour did not feem to be alter- ed. The water being now poured off, was intirely infipid, and agreed in every che- mical trial with pure water. The pow- der, after being perfeCtly well dried, weigh- ed thirty feven grains. It did not diffulve intirédly in fpirit of vitriol ; but, after a brifk effervefcence, part of it fubfided in | ' the fame manner as the calcarious earths, ~ ewhen mixed with this acid. WHEN 188 ESSAYS anp OBSERVATIONS WHEN I firft tried this experiment, I was atthe trouble of digefling the mixture in the heat of boiling water, and did not then know that it would fucceed in the heat of the air. But Dr Alfton, who has obliged the world with many curious and » ufcful difcoveries on the fubject of quick- lime having had occafion to repeat it, I learned from him that heat is not neceflary; and he has moreover added an ufeful pur- pofe to which this property of magnefia may be apphed; I mean the {weetening of water at fea, with which lime may have been mixed to prevent its putrefac- tion. THaT part of the dried powder which does not diffolve in fpirit of vitriol, con- fifis of the lime feparated from the water, Quick-Limzitfelf isalforendered mild by magnefia, if thefe two are well rubbed together and infufed with a fmail quantity of water. By the following experiments, I pro- pofed to know whether this fubftance could be reduced to a quick-lime. ody PHYSICAL anv LITERARY. 18% AN ounce of maguefia was expofed in a crucible for about an hour to fuch a heat as is fufficient to melt copper. When ta- ken out, it weighed three drams and one Eels. or had loft 7; of its former weight. I repeated, with “#8 magicfia prepared in this manner, moft of thofe experiments I had already made upon it before calci- nation, and the refult was as follows. Ir diffolves i in all the acids, and with thefe compofes falts exactly fimilar t to thofe defcribed in the firft fet of experiments: But what is particularly to. be remarked, it is diffolved without ay the leatt degree of effervefcence. Ir flowly precipitates the corrofive fub- limate of mercury in the form of a black powder, - It feparates the volatile alkali in falt ammoniac from the acid, when it is mixed with a warm folution of that falt. But it does not feparate an acid from a calcari- ous earth, nor does it induce the leaft change upon lime-water. | : LasT iy, when a dram of it is digefted . eth 2 an ounce of water in a bottle for fome 390 ESSAYS anp OBSERVATIONS fome hours, it does not make any the leaft change in the water. ‘The magnefia, when dried, is found to have gained ten grains ; but it neither effervefces with acids, nor does it fenfibly affect lime-water, OBSERVING magnefia to lofe fach a re- markable proportion of its weight in the fire, my next attempts were directed to the inveftigation of this volatile part, and, a- - mong other experiments, the following ~ ‘feemed to throw fome light upon it. THREE ounces of magnefia were diftilled ‘in a glafs retort and receiver, the fire bé- ing gradually increafed until the magnefia -was obfcurely red hot. When all was cool, I found only five drams of a whitifh water in the receiver, which had a faint fmell of the fpirit of hartfhorn, gave a green colour to the juice of violets, and rendered the folutions of corrofive fubli- mate and of tilver very flightly turbid. But it did not fenfibly eflervefce ‘with a- cids. Tue magnefia, when taken out of the re- tort, weighed an ounce, three drams, and thirty grains, or had loft more than the half vf ae PHYSICAL anp LITERARY. rot half of its weight. It ftill effervefced pret- ty brifkly with acids, though not fo —s, ly as before this operation, THE fire fhould have been raifed here to the degree requifite for the perfect cals cination of magnefia. But, even from this imperfect experiment, it is evident, that, of the volatile parts contained in that pow- der, a {mall proportion only is water; the reft cannot, it feems, be retained in vellels, under a vifible form. Chemifts have of- ten obferved, in their diftillations, that part of a body has vanifhed from their fenfes, notwithftanding the utmoft care to retain it; and they have always found, upon further inquiry, that fubtile part to be air, which having been imprifoned in the bo- dy, under a folid form, was fet free and rendered fluid and elaftic by the fire. We may therefore fafely conclude, that the vo- latile matter, loft in the calcination of magnefia, is moftly air; and hence the _ calcined magnefia does not emit air, or " make an effervefcence, when mixed with | acids. THE 192 ESSAYS ann OBSERVATIONS THE water, from its properties, feems to contain a fniall portion of volatile alka- hi, which was probably formed from the earth, air, and water, or from fome of thefe combined together ; and perhaps al- fo from a fmall quantity of inflammable matter which adhered accidentally to the magnefia, Whenever chemifts meet with this falt, they are inclined to afcribe its origin to fome animal or putrid vegetable fubftance; and this they have always done, when they obtained it from the calcarious earths, all of which afford a fmall quan- tity of it. There is, however, no doubt that it can fometimes be produced inde- pendently of any fuch mixture, fince ma= ny frefh vegetables and tartar afford a con- fiderable quantity of it. And how can it, in the prefent inftance, be fuppofed, that any animal or vegetable matter adhered to the magnefia, while it was diffolved by an acid, feparated from this by an alkali, and wafhed with fo much water? Two drams of magnefia were calcined in a crucible, in the manner defcribed a: bove, and thus reduced to two feruples an “PHYSIGAL anv LITERARY. 193 and twelve grains. This calcined magne- fia was diffolved in a fufficient quantity of - fpirit of vitriol, and thea again feparated from the acid by the addition of an alkali, of which a large quantity is neceflary for this purpofe. The magnefia being very well wafhed and dried, weighed one dram and fifty grains. Ir effervefced violently, or emitted a large quantity of air, when thrown into acids; formed a red powder when mixed with a folution of fublimate ; feparated the calcarious earths from an acid, and fweetened lime water: And had thus recovered all thofe properties which it had but juft now loft by calcination: Nor had it only recovered its original pro= perties, but acquired befides an addition of weight nearly equal to what had -been loftin the fire; and, as it is found to effer- yefce with acids, part of the addition muft certainly be air. Tuts air feems to have been furnifhed by the. alkali from which it was feparated by the acid; for Dr Hales has clearly proved, - that alkaline falts contain a large quantity of. fixed air, which they emit in great a= mv eL. II. Bb bundance 194 ESSAYS anv OBSERVATIONS bundance when joined toa pure acid. In the prefent cafe, the alkali is really joined to an acid, but without any vifible emif= _fion of air ; and yet the air is not retain- ed in it: For the neutral falt, into which it is converted, is the fame in quantity, and in every other refpect, as if the acid employed had not been previoufly fatura- ted with magnefia, but offered to the alka- Hin its pure ftate, and had driven the air out of it in their conffi@. It feemsthere= fore evident, that the air was forced from the alkali by the acid, and lodged itfelf in the magnefia. THESE confiderations led me totry a few experiments, whereby I might know what quantity of air is expelled from an alkali, or from magnefia, by acids. Two drams of a pure fixed alkaline filt, and an ounce of water, were put in- to a Florentine flatk, which, together with its contents, weighed two ounces and two drams. Some oil of vitriol diluted with water was dropt in, until the falt was ex- actly faturated ; which it was found to be, when two sisi two icruples, and three grains a PHYSICAL anv LITERARY. 195 grains of this acid had been added. The phial with its contents now weighed two ounces, four drams, and fifteen grains. One {cruple, therefore, and eight grains were loft during the ebullition, of which a trifling portion may be water, or fome- thing of the fame kind. The reit 4s air. . THE celebrated Homberg has attempted to eftimate the quantity of folid fale con- tained in a determined portion of the fe- eral acids. He faturated equal quanti- ties of an alkali with each of them; and, obferving the weight which the alkali had gained, after being perfe@ly dried, took this for the quantity of folid falt coatain- ed in that fhare of the acid which perform- ed the faturation. But we learn from the above experiment, that his eftimate was mot accurate; becaufe the alkali lofes weight as well as gains it. Two drams of magnefia, treated exact- dy as the alkali in the laft experiment, were _ juft diffolved by four drams, one fcruple, and feven grains of the fame acid liquor, and loft one fcruple and fixteen grains by ithe ebullition. | Two 196. ESSAYS anv OBSERVATIONS - Two drams of magnefia were reduced, by the action of a violent fire, to two feru- ples and twelve grains, with which the fame procefs was repeated as in the two jait experiments; four drams, one feru- ple. and two grains of the fame ‘acid were required to compleat the folution, and no weight was loit in’ the experi- ment. _ As in the feparation of the volatile from the fixed parts of bodies, by means of heat, a imall quantity of the latter is ge- nerally raifed with the former; fo the air ~and water, originally contained in the magnéfia, and afterwards diflipated by the fire, feem to have carried off a fmall part of the fixed earth of this fubitance. This is probably the reafon, why calcined mag- nefia is faturated with a quantity of acid, fomewhat lefs than what is required. to diffolve it before calcination: And the fame may be afligned as one caufe which hinders us from reftoring the whole of its original weight by folution and precipi- tation. PHYSIGAL ann LITERARY. 197. Wh ftcok care to dilute the vitriolic acid, jn order to avoid the heat and ebullition which it would otherwife have excited: in the water; and I chofe a Florentine flafik, . on account of its lightnefs, capacity, and shape, which is peculiarly adapted to the experiment; for the vapours raifed by “the ebullition circulated for a fhort time thro’ the wide cavity of the phial, but “were foon collected upon its fides, like dew, afid none of them feemed to reach - the neck, which continued perfectly dry ‘to the end of the experiment. We. now perceive the reafon why crude and calcined magnefia, which differ in ma- ny refpects from ‘one another, agree how- /ever in compofing the fame kind of fal, ‘when -diflolved in any. particular acid ; - for the crude magnefia feems to differ from the calcined. chiefly by containing a con- fiderable quantity of air, which air is una- voidably difiipated and loft curing the diffolution. FRomM our experiments, it feems proba- ble, that the increafe of weight which fome meta!s acquire, by being farft diffol- ved 198 _ ESSAYS anp OBSERVATIONS ved in acids, and then feparated from them again by alkalis, proceeds from air furnifhed by the alkalis. And that, in the aurum fulminans, which is prepared by the fame means, this air adheres to the gold in fuch a peculiar manner, that, in a moderate degree of heat, the whole of it recovers its elafticity in the fame inftant of time; and thus, by the violent fhock which it gives to the air around, produ- ces the loud crack or fulmination of this powder. Thofe who will imagine the _ explofion of fuch a minute portion of fix- ed air, as can refide in the aurum fulminans, to be infufficient for the exceffive loudnefs of the noife, will confider, that it is not a large quantity of motion communicated tothe air, but rather a fmart ftroke, which produces found, and that the explofion of | but a few particles of fixed air may be capable of caufing a loud noife, provided they all recover their {pring fuddenly, and in the fame inftant. | ‘THE above experiments lead us alfo to conclude, that volatile alkalis, and the common abforbent earths, which lofe their PHYSICAL anv LITERARY. 199 their air by being joined to acids, but _ fhew evident figns of their having reco-= vered it, when feparated from them by alkalis, received it from thefe alkalis which loft it in the inftant of their joining with the acid. THE following are a few experiments apon three of the abforbent earths, made in order to compare them with one an- other, and with maguefia. Sufpecting that magnefia might poflibly be no other than a common calcarious earth, which had changed its nature, by having been previously combined with an _ acid, I faturateda fmall quantity of chalk with the muriatic acid, feparated the acid from it again by means of a fixed alkali, and carfully wafhed away the whole of the ~ falt. The chalk when dried was not found to have fuffered any alteration; for it ef- | fervefced with the vitriolic acid, but did not diffolve in it; and, when expofed to a violent fire, was converted into a quick-. lime, in all refpects fimilar to: that obtain- ed from common chalk, a Ix 400 ESS‘ YS anv ee IN another experiment of the fame kind, I ufed the vitriolic acid with the fame event, ANY calcarious matter reduand. to a fine powder, and. thrown into a warm fo- lution of alum, immediately raifes.a brifk. effervefcence. But the powder is not dif folved ; it is rather increafed in, bulk: And if the addition, be repeated until it is no longer accompanied with eflerveicence the liquor_lofes all taftéof the alum, and yeilds only a very light cloud upon the ad- mixture of an alkali, From this experiment we learn, that acids attract the calcarious earths more ftrongly than they do the earth of alum ; ; and as the acid in this falt is exa@ly the fame with the vitriolic, it compofes with the calcarious earth a neutral fubftance; which is very difficultly foluble in water, and therefore falls down to the bottom of the veilel along with the, earth of alum which is deprived of its acid. The light cloud formed by the alkali proceeds from: the minute portion of the calcarious com- pound which faturates the water. 3 THE ccs AND LITERARY. 20t THe earth of animal bones, when re-. duced to a fine powder and thrown into a diluted vitriolic acid, gradually abforbs the acid in the fame manner as the calca- rious earths, but without any remarkable effervefcence. -When it is added to the ni- trous or to the muriatic acid, it is flowly difflolved. The compound liquor thence produced is extremely acrid, and {till changes the colour of the juice of violets to a red, even after it is fully faturated with the abforbent. Duitilled vinegar has little or no effect upon this earth; for, after a long digeftion, it {till retains its ' four tafte, and gives only alight cloud up- on the addition of an alkali. By dropping a diflolved fixed alkali in- to a warm folution of alum, I obtained the earth of this falt, which, after being well wafhed and dried, was found to have . the following properties. Ir is diffolved in every acid, but very flowly, unlefs affifted by heat. The feve- ral folutions, when thoroughly faturated, © are all aftringent with a flight degree of an acid tafte, and they alfo agree with Vou. Il. cc folution 202 ESSAYS anp OBSERVATIONS folution of alum in this, that they give a red colour to the infaGon of turnfol. ; NEITHER this earth, nor that of ani- mal bones, can be converted into quick- lime by the ftrongeft fire, nor do they fuf- fer any change worth notice. Both of them feem to attract acids but weakly, and to alter their properties lefs when u= nited to them than the other abforbents. 2 gh cn Ot wate La reflecting afterwards upon thefe ex= periments, an explication of the na= ture of lime offered itfelf, which feemed to account, im an eafy manner, for moft. of the properties of that fubftance. Ir is fufficiently clear, that the calcari- ous earths in their native ftate, and that the alkalis and magnefia in their ordina- ry condition, contain a large quantity of fixed air, and this air certainly adheres to them with confiderable force, fince a {trong fire is neceflary to feparate it from magne- fia, and the ftrongeft is not fufficient to | expell ‘ats . ‘ : ‘ " f , | PHYSICAL anv LITERARY. 203 expell it entirely from fixed alkalis, or take away their power of effervefcing with acid falts. ; THEsE confiderations led me to cons clude, that the relations between fixed air and alkaline fubftances was fomewhat fi- moilar tothe relation between thefe and a- cids; that as the calcarious earths and al- kalis attract acids ftrongly and can be fa- turated with them, fo they alfo attract fix- ed air, and are in their ordinary ftate fa- turated with it; and, when we mix an a- cid with an alkali or with an abforbent’ earth, that the air is then fet at liberty, and breaks out with violence; becaufe the alkaline body attracts it more weakly than it does the acid, and becaufe the acid and air cannot both be joined to the fame bo- dy at the fame time. I alfo imagined, that, when the calca- rious earths are expofed to the ation of a , Violent fire, and are thereby converted in- "to quick-lime, they fuffer no other change Bip. their compofition than the lofs of a {mall quantity of water and of their fixed air. ‘The remarkable acrimony which we : perceive 204 ESSAYS anp OBSERVATIONS — perceive in them after this procefs, was not fuppofed to proceed from any addi- tional matter received in the fire, but feem- ed to be an effential property of the pure earth, depending on an attra@ion for thofe feveral fubftances which it then be- came capable of corroding or diffolving, which attraction had been infenfible as long as the air adhered to the earth, but difcovered itfelf upon the feparation. THIs fappofition was founded uponan obfervation of the moft frequent confe- quences of combining bodies in chy- miftry. Commonly when we join two bo- dies together, their acrimony or attrac- ‘tion for other fubftances becomes imme- diately either lefs perceivable or entirely infenfible; although it was fufficiently {trong and remarkable before their union, and may be rendered evident again by -disjoining them. A neutral falt, which is compofed of an acid and alkali, does not poffefs the acrimony of either of its con- flituent parts. It can eafily be feparated from water, has little or no effet upon metals, ig incapable of being joined to in- 4 PHYSICAL ano LITERARY. 205 inflammable bodies, and of corroding and diffolving animals and vegetables; fo that the attraGiion both of the acid and alkali for thefe feveral f{ubitances feems to be fuf> pended till they are again feparated from one another. CrUupDeE lime was therefore confidered as a peculiar acrid earth rendered mild by its union with fixed air: And quick- lime as the fame earth, in which, by ha- ving feparated the air, we difcover that a- crimony or. attraction for water, for ani- mal, vegetable, and for inflammable fub- flances. Tat the calcarious earths really lofe a large quantity of air when they are burrt to quick lime, feems fufficiently pro- ved by an experiment of Mr Margraaf *, an exceedingly accurate and judicious chymift. He fubjected eight ounces of oiteocolla to diitillation in an earthen re- tort, finifhing his procefs with the moft violent fire of a reverberatory, and caught in the receiver only two drams of water, which * Mem. de Il’Acad, de Berlin, an: 1748, ps 546 206 ESSAYS anp OBSERVATIONS . which by: its fmell and properties fhewed itfelf to be flightly alkaline. He does not tell us the weight of the ofteocolla remain- ing in the retort, and only fays, that it was converted into quick-lime; but,as no calcarious earth can be converted into quick-lime, or bear the heat. which he ap-- plied without lofing above a third of its weight, we may fafely conclude, that the lofs in his experiment was proportional, and proceeded chiefly from the diffipation _of fixed air. i ACcoRDING to our theory, the relation of the calcarious earth to air and water appeared to agree with the relation of the fame earth to the vitriolic and vegetable acids. As chalk for inftance has a ftrong- er attraction for the vitriolic than for the vegetable acid, and is diflolved with more difficulty when combined with the firft, than when joined.to the fecond: So it al- fo attracts air more ftrongly than water, and is diflolved with more difficulty when ' faturated with air than when compound- ed with water only. . aa + o Fo - PHYSICAL anv LITERARY. 207 ‘A calcarious earth deprived of its air, or in the ftate of quick-lime, greedily ab- forbs a confiderable quantity of water, becomes foluble in that fluid, and is then {aid to be flaked ; but, as foon as it meets with fixed air, it is f{uppofed to quit the water and join itfelf to the air, for which it has a fuperior attraction, and is there- fore reftored to its firft ftate of mildnefs and infolubility in water. WueEn flaked lime is mixed with wa- ter, the fixed air in the water is attracted by the lime, and faturates a {mall portion of it, which then becomes again incapable of diffolution, but part of the remaining flaked lime is diffolved and compofes lime-water. Ir this fluid be expofed to the open air, the particles of quick lime which are near- eft the furface gradually attract the parti- cles of fixed air which float in the atmo- fphere. But at the fame time that a particle of lime is thus faturated with air, itis alfo’ reftored to its native ftate of mildnefs and mfolubility ; and as the whole of this change muft happen at the furface, the whole 208 ESSAYS-anp OBSERVATIONS whole of the lune is fucceflively collected there under its original form of an in‘ipid calcarious earth, called the cream or cruits of lime-water. WHEN quick-lime itfelf is expofed to the open air, it abforbs the particles of water and of fixed air which come with- in its {phere of attraction, as it meets with the firft of thefe in greateft plenty, the greateft part of it aflumes the form of fla- ked lime; the reft 1s reftored to its origi- nal ftate ; and, if it be expofed fora fufh- cient length of time, the whole of it is gra- dually faturated with air, to which the water as gradually yields its place. We havealready fhewn by experiment, that mignefia alba is a compound of a peculiar earth and fixed air. When this fubftance is mixed with lime-water, the lime fhews a ftronger attraction for fixed air than that of the earth of meguefia ; the air leaves -this powder to join itfelf to the lime. And as neither the lime when faturated with air, nor the maguefia when deprived of it, are foluble in water, the lime water becomes perfectly pure and infipid, PHYSICAL anv LITERARY.. 209 infipid, the lime which it contained being mixed with the magnefia. But, if the ma-, guefia be deprived of air by calcination before it is mixed with the lime-water, this fluid fuffers no alteration. Ir quick-lime be mixed with a diffolved alkali, it likeways fhews an attraGtion for fixed air fuperior to that of the alkali. Ic robs this falt of its air, and thereby be- comes mild itfelf, while the alkali is con- fequently rendered more corrofive, or dif- covers its natural degree of acrimony or - - {trong attraction for water, and for bodies of the inflammable, and of the animal and vegetable kind; which attraction was lefs perceivable as long as it was {aturated with air. And the volatile alkali, when deprived of its air, befides this attraction for various bodies, difcovers like eways its - matural degree of volatility, which was formerly fomewhat reprefled by the air a | adhering to it, in the fame manner as it is : * reprefled by the addition of an acid. _. Tuis account of lime and alkalis re- Bees encoded itfelf by its fimplicity, and a, affording an eafy folution of many Vor. Il, Dd. plaiomena ‘210 ESSAYS AND OBSERVATIONS phenomena, but appeared upon a nearer view to be attended with confequences ‘ that were fo very new and extraordinary, as to render fufpicious the principles from which they were drawn. I refolved however to examine, ina par- ticular manner, fuch of thefe confequen- ces as were the moft unavoidable, and found, the greateft number of them might be reduced to the following propofitions. I. Ir we only feparate a quantity of air from lime and alkalis, when we ren- » der them cauftic they will be found to lofe part of their weight in the operation, but will faturate the fame quantity of a- cid as before, and the faturation will be performed without effervefcence. II, Ir quick lime be no other than a calcarious earth deprived of its air, and whofe attraCtion for fixed air is ftronger than that of alkalis, it follows, that, by adding to it a fufficient quantity of alkali faturated with air, the lime will recover the whole of its air, and be entirely reito- red to its original weight and condition : And PHYSICAL ann LITERARY. 211 And, it alfo follows, that the earth fepara- ted from lime-water by an alkali, is the lime which was diffolved in the water now reftored to its original mild and infoluble {tate. Ill. Ir it be fuppofed that flaked lime does not contain any parts which are more fiery, active, or fubtile than others, and by which chiefly it communicates its virtues to water; but that it is an uniform compound of lime and water; it follows, that, as part of it can be diflolved in wa- ter, the whole of it is alfo capable of be- ing diffolved. : } IV. Ir the acrimony of the cauttic al- kali does not depend on any part of the lime adhering to it, a cauftic or foap-ley will confequently be found to contain no lime, unlefs the quantity of lime employ- ed in making it were greater than what is juft fufficient to extract the whole air of the alkali ; for then as much of the fu- _ perfluous quick-lime might poflibly be diffolved by the ley as would be diffolved : _by pure water, or the ley would contain as much lime as lime water does. N. ‘a12 ESSAYS AND OBSERVATIONS | V WE have fhewn in the former ex- periments, that abforbent earths lofe their air when they are joined to an acid; but recover it, if feparated again from, that acid, by means of an ordinary alkali: The air pafling from the alkali to the earth, at the fame time that the acid pafles from the earth to the alkali. Ir the cauftic alkali therefore be defti- tute of air, it will feparate magnefia from an acid under the. form of a magicfia free of air, or which will not effervefce with acids; and the fame cauftic alkali - wili alfo feparate a calcarious earth from acids under the form of a calcarious earth deftitute of air, but faturated with ‘wa- ter, or under the form of flaked lime. TuHeEse were all neceflary conclufions from the above fuppofitions. Many of them appeared too improbable to deferve any further attention: Some, however, I found upon reflection were already fe- conded by experience. Thus Hoffman has obferved, that quick-lime does not ef- férvefce with f{pirit of vitriol *; and itis well * Hoff. Op T, iv: p. 480: PHYSICAL anv LITERARY. 213 wellknown that the cautftic fpirit of urine, or of falt ammoniac, does not emit air, when mixed with acids. This confide+ ration excited my‘curiofity, and determin- ed me to inquire into the truth of them all ‘by way of experiment.. I therefore engaged myifelf in a fet of trials; the hi- {tory of which is here fubjoined. Some new facts are likeways occafionally -men- tioned:; and here it will be proper to ins form the reader, that I have never men= tioned any without fatisfying myfelf of their truth by experiment, though [ have fometimes taken the liberty to negle& de- f{cribing the experiments when they feem- ed fufficiently obvious. DeEstrineG to know how much of an acid’a calcarious earth will abforb, and what quantity of air is expelled during the diflolution, I faturated two drams of chalk with diluted {pirit of falt, and ufed “the Florentine flafk, as related in a fimi- lar experiment upon magne/ia. Seven -drams and one grain of the acid finifhed sthe diffolution, and the chalk loft two ‘Acruples and eight grains of air. Tuts 214 ESSAYS anp OBSERVATIONS © THIS experiment was neceflary before the following, by which I propofed to in- quire into the truth of the firft propofi- tion fo far as it relates to quick-lime. Two drams of chalk were converted " into a perfect quick-lime, and loft two feruples and twelve grains in the fire. This quick-lime was flaked or reduced to a milky liquor with an ounce of water, and then diffolved in the fame manner, and with the fame acid, as the two drams of chalk in the preceeding experiment. Six drams, two {cruples, and fourteen grains of the acid finifhed the faturation without any fenfible effervefcence or lofs of weight. Ir therefore appears from thefe experi- ments, that no air is feparated from quick- lime by an acid, and that chalk faturates nearly the fame quantity of acid after it is converted into quick-lime as before. W1TH refpect to the fecond propofi- tion, I tried the following experiments. A piece of perfect quick-lime made from two drams of chalk, and which weighed one dram and eight grains, was reduced - pHYSICAL anp LITERARY. 215 reduced to a very fine powder, and thrown into a filtrated mixture of an ounce of a fixed alkaline falt and two ounces of wa- ter. After a flight digeftion, the powder being well wafhed and dried, weighed one dram and fifty eight grains. It was fimilar in every trial to a fine powder of ordinary chalk, and was therefore fatu- rated with air which muft have been fur- nifhed by the alkali. | A dram of pure falt of tartar was dif | folved in fourteen pounds of lime-water, and the powder thereby precipitated, be- ing carefully collected and dried, weigh- ed one and fifty grains. When expofed to a violent fire, it was converted into a true quick-lime, and had every other qua- lity of a calcarious earth. THIs experiment was repeated with the volatile alkali, and alfo with the foffil or alkali of fea-falt, and exactly with the fame event. Tue third propofition had lefs appear: ib ance of probability than the foregoing ; _ but, as an accurate experiment was the on- “Ay teft of its truth, I reduced eight grains : of 216 ESSAYS ann OBSERVATIONS of perfect quick-lime made of chalk, to an exceedingly fubtile powder, by flaking it in two drams of diftilled water boiling hot, and immediately threw the mixture into eighteen ounces of diftilled water in a flafk. After fhaking it, a light fedi- ment, which floated through the liquor, was-allowed to fubfide; and this, when collected with the greateft care, and dry- ed, weighed, as near as I could guefs, one, third ofa grain, The water tafted ftrong- ly of the lime, had all the qualities of lime-water, and yielded twelve grains of precipitate, upon the addition of falt of tartar. In repeating this experiment, the quantity of fediment was fometimes lefs than the above, and fometimes amounted to half a grain. It confifted partly of an earth which effervefced violently with a- qua fortis, and partly of an ochry powder, which would not diffolve in that acid. The ochry powder, as it ufually appears in chalk to the eye, in the form of veins running through its fubflance, muft be confidered only as an accidental or foreign: admixture ;.and, with refpect to the mix nute “eh PHYSICAL ano LITERARY. 217 hute portion of alkaline earth which com- pofed the remainder of the fediment, it cannot be fuppofed to have been origi- nally different from the reft, and incapa- ble, from its nature, of being converte into quick-lime, or of being diffolved in water; it feems rather to have conifted of a fmall part of the chalk in its mild ftate, or faturated with air, which had either remained, for want of a fufficient fire to drive it out entirely, or had been furnifhed by the diftilled water. I indeed expefted to fee a much larger quantity of fediment produced from th® lime, on account of the air which water conftantly contains ; and, with a view to know whether water retains its air when fully faturated with lime, a lime-water was made as ftrong as poffible: Four ounces of which were placed under the Teceiver of an air-pump, together, with four ounces of common water in a phial of the fame fize; and, upon exhanfting the “receiver, without heating the phials, the “air arofe from each in nearly the fame ee Vor. Il, Bie quantity : 218 ESSAYS anp OBSERVATICNS quantity : From whence it is evident, that the air, which quick-lime attracts, is of a different kind from that which is mixed with water. And that it is alfo different from common elaftic air, is fuficiently proved by daily experience; for lime-wa- ter, which foon attracts air, and forms a eruft when expofed in open and fhallow veflels, may be preferved, for any time, in bottles which are but flightly corked, or clofed in fuch a manner as would allow ree accefs to elaftic air, were a vacuum formed in the bottle. Quick-lime there- fore does not attract air when in its moft ordinary form, but is capable of be-. ing joined to one particular fpecies only, which is difperfed through the atmo- fphere, either in the fhape of an exceed- ingly fubiile powder, or more probably in that of an elaftic fluid. To this I have given the name of fixed air, and perhaps very improperly ; but I thought it better to ufe a word already familiar in philo- fophy, than to invent a new name, before we be more fully acquainted with the nature PHYSICAL anp LITERARY. 219 - mature and properties of this fubftance, which will probably be the fubject of my further inquiry. Ir is, perhaps, needlefs to mention here, that the calcarious fubitances ufed in ma- king the above experiments fhould be of the pureft kind, and burnt with the ur- moft violence of heat, if we would be fare of converting them into perfect quick lime. I therefore made ufe of chalk burnt ina {mall covered crucible with the fierceft fire of a black{mith’s forge, for halt an hour, and found it neceflary to employ, for this purpofe, a crucible of the Aufirian kind, which refemble black lead ; for, if any cals carious fubftance be heated to fuch a de- gree. in an ordinary or Heffian crucible, the whole of it is melted down, together with part of the veflel, into glafs. I now prepared to inquire into the pro- _ perties of the caultic alkali; in order to _ which, I made a cauftic or foap-ley in the _ following manner, TwekntTy fix ounces of very ftrong ~ quick-lime made of chalk, were flaked or -Feduced to a fort of fluid patte, with eleven pounds ‘ 220 ESSAYS anp OBSERVATIONS” pounds of boiling water, and then mixed in a glafs veflel with eighteen ounces of a pure fixed alkaline falt, which had been firtt diffolved in two pounds anda halt of water, This mixture was fhaken fre- quently for two hours, when the action of the lime upon the alkali was fuppofed to be over, and nothing remained but to fe- parate them again from one another. I therefore added 12 pounds of water, ftir- red up the lime, and, after allowing it to fettle again, poured off as much of the clear ley as poflible. THE lime and alkali were mixed toge- ther under the form of a very thick milky liquor or fluid pafte; becaufe they are thus kept in perpetual contact and equal mixture until they have acted fufficiently upon one another: Whereas, in the com- mon way of ufing a larger quantity of water, the lime lies for the moft part at bottom, and,-tho’ ftirred up ever fo often, cannot exert its influence fo fully upon the alkali, which is uniformly diffufed thro’ every part of the liquor. THE PHYSICAL anno LITERARY. 221 "THE above ley was found upon trial to bi faturated by acids without the leaft ef- - fervefcence or diminution of weight, Ir was now proper to exaraine whether. the alkali fuffered any lofs in becoming cauftic, which | propofed to attempt by _ afcertaining the firength of the ley, or the quanuty of falt which a given portion of it contained , from which, by computa- tion, fome imperfect knowledge might be obtained of the quantity of cauftic produ- ced from the eighteen ounces of mild fale, I therefore evaporated fome of my ley ; but foon perceived that no certain judge- ment could be formed of its firength in this way; becaufe it always abforbed a confiderable quantity of air during the e- yaporation, and the dried falt made a pretty brifk effervefcence with acids, fo - that the ley appeared ftronger than it real~ ly was; and yet, upon proceeding in the _ eftimate from this rude and unfair trial, it appeared that the falt had loft above a fixth in becoming cauftic, and. the quan- ty of acid faturated by two drams of it os to the quantity of acid faturated by two 222 ESSAYS anp OBSERVATIONS two drams of falt of tartar, nearly as fix _ to five. : THESE experiments are therefore agree- able to that part of the fecond propofition which relates to the cauftic alkali. Upon iarther-examining what changes the alkali had undergone, I found that the ley gaveonly an exceeding faint milky hue to lime-water; becaufe the cauftic alkali wants that air by which falt of tartar pre- cipitates the lime. Whena few ounces of it were expofed in an open {hallow veffel for four and twenty hours, it imbibed a {mall quantity of air, and made a flight effervefcence with acids. After a fort- night’s expofure in the fame manner, it became entirely mild, effervefced as vio lently with acids, and had the fame effect upon lime-water, as a folution of an ordi- nary alkali. It likeways agrees with lime- water in this refpect, that it may be kept in clofe veffels, or even in bottles which are but flightly covered, for a confidera- ble time, without abforbing a fenfible quantity of air. In a PHYSICAL ann LITERARY. 223 In order to know how much lime it contained, I evaporated ten ounces in @ - fall filver difh over a lamp, and melted the falt, after having diffipated the wa- ter *. Tre cauftic thus produced was diffol- ved again in a {mall quantity of water, and depofited a trifling portion of fed1- ment, which I imagined at firft to be lime; but, finding that it could eafily be diffol- ved in a little more water, concluded it to be a vitriolated tartar, which always accompanies the fixed alkali of vegetables. Ithen faturated the folution of the cau- flic falt with fpirit of vitriol, expecting thus to detec the lime; becaufe that acid precipitates a calcarious earth from its or- dinary folutions. During the faturation, a large quantity of white powder was formed ; bat this likeways turned out to f be * This evaporation was performed in a filver difh, on account of the acrimony of the falt; which is fo very _ great, that, having once evaporated a part of the fame dey in a bowl of English earthen or lone ware, and melt- fee the cauftic with a gentle beat, it corroded and diffol- _ Yed a part of the bow!, aud left the infide of it pitted ' ‘With {mall holes. 324 ESSAYS anv OBSERVATIONS be a vitriolated tartar, which had appear- ed in the form of a powder, becaute there was not enough of water im the mixture to diffolve it. LasTLy, I expofed a few ounces of the ley in an open thallow veilel fo long, that the alkali loft the whole of its caufticity, and feemed entirely reftored to the ftate of an ordinary fixed alkali ; but it did not however depofite a fingle atom of lime. And, to affure myfelf that my cauftic ley was not of a fingular kind, I repeated the © fame experiments with an ordinary foap- ley, and with one made by mixing one part of a pure fixed alkaline falt with three parts of common ftone-lime frefh flaked and fifted; nor could I difcover any lime in either. The firft of thefe contain- ed a {mall quantity of brimftone, and was far from being perfectly cauftic, for it made a pretty brifk effervefcence with a- cids ; but the laft was fo entirely deprived of its air, that it did not diminifh in the leaft the tranfparency of lime-water. THESE experiments feem therefore to fupport the fourth propofition, and to fhew . a % | . folved again in diftilled water, compofes th § PHYSICAL ano LITERARY. 225 fhew that the cauftic alkali does not con- fain any lime. As it feems probable, from the quick- nefs and eafe wherewith the alkali was rendered cauftic, that more lime had been employed than what was juit fufficient to extract the whole of its air, we are fur- prifed to find that little or none of the fuperfluous quick-lime was diffolved by - the water.. But this phenomenon will be- come lefs furprizing, by comparing it with fome fimilar inftances in chemiftry. Water may be made to depofite a falt, by the admixture of a fubftance which it at- tracts more ftrongly than it does that falr; fach as fpirit of wine; and quick-lime it- felf may be feparated from water upon the fame principle: For if that fpirit is added to an equal quantity of lime-water, the mixture becomes turbid and depofites a fediment, which, when feparated and dif- lime water. We may therefore refer the *! above phenomenon, with refpeé to the ley, to the fame canfe with thefe, and fay, that ‘the water did not diffolve the lime, be- You. Il, Ff caufe 226 ESSA\S aNp_OBSERVATIONS_ caufe it already contained a cauttic alkali, for which it has a fuperior attraction. — I alfo rendered the volatile alkali cau- ftic, in order to examine what change it fuffered in the operation, and obtained an exceedingly volatile and acrid {pirit, which neither effervefced with acids, nor altered in the leaft the tranfparency of lime wa- ter; and, altho’ very ftrong, was lighter than water, and floated upon it like fpirit of wine. ; I next inquired into the truth of the fifth propofiuon, in the following man- ner. rt Two drams of Epfom falt were diffol- ved in a fmall quantity of water, and. thrown into two ounces of the cauttic ley; : the mixture initantly became thick, like a decoction of ftarch or barley, by the mog~ nefia, which was precipitated. I then add- ed fpirit of vitriol by degrees, until the mixture became perfectly ‘clear, ‘or the whole of the magnefia was again difolved ; ~ which hippened without any effervefcence or emiflion of air. 4 HAatr % PHYSICAL ann LITERARY. 257 . OPALY an ounce of chalk was diffolved ‘in fpiric of falt, the quantity of which was fo adjufted, that the mixture was not acid in the leaft degree; and the folutioa was thrown into twelve ounces of the cau- {tic ley ; which quantity I found, by ex- periment, to be fufficient for precipitating almoft the whole of the chalk, I now 4l- trated this turbid liquor, and laid the powder remaining in the paper upon a chalk ftone, in order to draw as much of the water trom it as pofiible, and thereby reduce it to the form of a more den‘e and “heavy powder, that it might fubfide the _ more perfectly in the following part of the experiment. I then mixed it with about twenty ounces of pure water in a flafk, and, after allowing the powder to fubfide, "poured off the water, which had all the - qualities of lime-water. And I facceflive- . ly: converted eight waters more into lime- water, feven of thefe in the fame quanti- 4 ty, and with the fame management, as “th the fir {t. The eighth was likeways in the fame quantity; but I allowed it to re- ‘main with the sel, and fhook it fre- : / quently r oe 228 ESSAYS anp OBSERVATIONS quently for two days, This, after being’ filtrated, formed a cream or cruft upon its furface when expofed to the air; changed the colour of the juice of violets into green ; feparated an orange coloured pow. der from a fclution of corrofive fubli- mate ; became turbid upon the addition of an alkali; was entirely {weetened by magnefia ; and appeared fo ftrong to the’ tafte, that I could not have diftinguifhed. it from ordinary lime-water. And when J threw fome falt ammoniac into’ the lime which remained, the vapour of the volatile’ alkali inmediately arofe from the mix- ture. In this experiment therefore the air is firft driven out of the chalk by an acid, and then, in order to feparate this acid from it, we add an alkali which has been: previoufly deprived of its air; by which means the chalk itfelf is alfo obtained free of air, and in an acrid form, or in the form of flaked lime. We have alfo feveral proceffes for ob- taining the volatile alkali in a cauftic form, which feem to be only fo many me- thods ‘ Te PHYSICAL anp LITERARY. 229 thods of obtaining it in its pure ftate, and free of fixed air. The firft of thefe is the feparation of the alkali from an acid, merely by heat; an inftance of which we have from Mr Margraaf*. He prepared from urine an ammoniacal falt, the acid of which is the bafis of the phofphorus, and is of fuch a peculiar nature, that it en- dures a red heat without being diflipated« Sixteen ounces of the neutral falt were fubjected by him to diftillation. The a- cid remained in the retort, and he foundin the receiver eight ounces of an alkaline fpirit, which, he tells us, was extremely vo- Jatile, very much refembling the fpirit of falt ammoniac diftilled with quick-lime ; -and no cryftals were formed,in it, when expofed to the cold air. A cauftie volatile alkali may alfa be. obtained, by mixing falt ammoniac with half its weight of a cauftic fixed alkali, or of magnefia which has been previoutly de- prived of its air by fire; and then fub- mitting thefe mixtures to diftillation : Or, merely a * Mem. de !’Acad. de Berlin, an. 1746, p. 87+ 34 ESSAYS aNd OBSERVATIONS ~ merely by adding any ordinary volatild alkali to a proper quantity ofa cauftic ley; for, inthis cafe, the air pafles from the vo- latile to the fixed alkali, by a fuperior at- traction for the laft, and, by a gentle heat, the compound yields a fpirit fimilar to that prepared from falt ammoniac and quick-lime. ' Ir is therefore probable, that, had we alfo a method of feparating the fixed alka- li from an acid, without, at the fame time, faturating it with air, we fhould then ob- tain it in a cauftic form; but I am not acquainted with an inflance of this fepa- ration in chymiftry. ‘| here are two in- deed which, at firtt fight, appear to be of this kind; thefe are the feparation of the fixed alkali from the nitrous acid by means of inflamed charcoal, in the pr o- cefs for making nitrum fixatum, and of the fame alkali, from vegetable acids merely by heat ; but, upon examining the product of each procefs, we find the alkali either fully or nearly faturated with air. In the farft, either the charcoal or the acid, or both together, are almoft _wholly PHYSICAL axp LITERARY, 231 wholly converted. into air; a part of which is probably joined to the alkali. In the fecond, the acid is not properly feparated,, but rather deftroyed by the fre: A con- fiderable portion of it is converted into an inflammable fubftance ; and we learn from Dr Hales, that the bodies of this clafs contain alarge quantity of fixed air. Wa EN we confider that the attraction of alkalis for fixed air is weaker than that of the calcarious ear ths, and reflect upon the effects of heat in chymiftry, we are led to imagine, that alkalis might be en- tirely deprived of their air, or rendered “perfectly cauftic, by a fire fomewhat weak = er than that which is fufficient to produce the fame change upon lime; but this opi- Rion ‘does not feem agreeable to experi- : enée. ald, us lopas alkalis do, however, acquire fome dere of caufticity in a ftrong fire, as ap- pears from their being more eafily united of wine after having been kept Jour — for fome time.» For that ima C 232 ESSAYS anp OBSERVATIONS lour from.a few drops of a ftrong cauttic ley. The circumftances which hinder us from rendering thefe falts perfectly cauttic by heat, are their propenfity to diffipation in the utmoft violence of the fire, their ex- treme acrimony, and the imperfection of our common veffels. For, before the heat becomes very intenfe, the alkalis either e- vaporate, or diffolve a part of the cruci+ bles in which they are contained, and oft- en efcape through their pores ; which hap- pens, efpecially as foon as they have alrea- dy acquired fome degree of additional a- crimony, by the lofs of part of their air. THE fufion alfo, which they fo readily undergo, is well known by chymifts, asa {trong obftacle to the feparation of the. volatile from the fixed parts of 1 come pound by - fire; accordingly, in feveral procefies, we are directed to. add to the, fufible compound fome porous fubftance which is incapable of fufion, and will re- tain the whole in a fpongy form, there-: by to facilitate the diflipation of the vola- tile parts. In PHYSICAL anno LITERARY, 233 In order to know whether an alkali would lofe a part of its air, and ac lire a degree of caufticity, when expofed, with this prec aution, to the action of a ftrong fire, | mixed an ounce and a half of falt of tartar with three ounces of black lead, a fubftance of any the moft unchangeable by chymical operations. This mixture I expofed, for feveral hours, in a covered crucible, to a fire fomewhat {ftronger than what is neceflary to keep falt of tartar in fufion. When allowed to cool, I found at ftill in the form of a loofe powder; and taking out one half, I diluted it with wa= ter, and by filtration: obtained a ley, which, when poured into a folution of white marble in aqua fortis, precipitated the marble under the form of a weak quick-lime: for the turbid mixture gave a green colour to the juice of violets, and threw up a cruft like that of lime-water: : and the precipitated powder collected and. mixed with fale ammoniac immediately _ yielded the {cent of the volatile alkali, Lest it fhould here be fufpected, that _ the alkaline qualities of this mixture, and Won. II, Gg of 234. ESSAYS anp OBSERVATIONS _of the precipitated marble were not owing to a lime into which the marble was con- verted, but to the alkali itfelf which was added, itis proper to obferve, that I mix- ed fo fmall a proportion of the ley with the folution of marble as made me ire: from certain experiments, that the whole of the alkali was fpent in performing the precipitation, and was confequently con- verted into a neutral falt by attracting the acid. The properties therefore of the mixture can only be referred to a lime, as is indeed fufficiently evident from the cruft which is peculiar to lime-water. I was therefore affured by this experi- ment, that an alkali does really lofe a part of its air, and acquire a degree of cautti- city, by the proper application of heat 5 but finding, by feveral trials, that the de- gree of caufticity which it had thus ac- quired was but weak, and that the quick- lime produced in this experiment was ex- bauited and rendered mild by a fmall quantity of water, I expofed the crucible, together with that half of the alkali which remained in it, to a ftronger fire, in order PHYSICAL anv LITERARY. 235 order to expel a larger quantity of air, and render it more remarkably cauttic ; but. the whole of it was diilipated by the force of the heat, and the black lead, which ftill retained the form of a loof and fubtile powder, Goer d little or no- thing to water. We learn then from the above experi- ment the reafon why the alkali newly ob- tained from the afhes of vegetables is ge- nerally of the more acrid kinds of that falt. It never appears until the fubject be converted into afhes, and is fuppofed to be formed by the fire, and to be the re- fult of a particular combination of fome of the principles of the vegetable ; one of which principlés is air which is contained in large quantity in all vegetable matters whatever. But, as foon as the {mallet part ofa vegetable is converted into athes, and an alkaliis thus formed, this falt ne= ceffarily fuffers a calcination, during which itis kept in a fpongy form by _ the afhes, and fhews a very confiderable £ Bie ice of acrimony, if immediately ap- _ Pied to the body of an animal ; but, if the afhes 236 ESSAYS anp OBSERVATIONS athes are for any time expofed to the air, or if we feparate the alkali from them by the addition of a large quantity of water and fubfequent evaporation, the falt im- bibes fixed air from the atmoiphere, and becomes nearly faturated with it: Though, even in this condition, it is generally more acrid than falt of tartar, when this is pre- pared with a gentle heat. Boxax has fometimes been referred to the clafs of alkalis, on account of fome refemblance it bears to thofe falts: But it has been demonftrated by accurate ex= periments, that we fhould rather confider it as a neutral falt; that it is compofed of an alkali and of a particular faline fub- {tance called the fedative falt, which ad- heres to the alkali in the {ime manner as an acid, bat can be feparated by the ad- dition of any acid whatever, the added a- cid joining itfelf to the alkali in the place of the fedative falt- As this conjunction of an acid with the alkali of borax hap- pens without the leaft etlervefcence, our principles lay us under a neceflity of al- lowing that alkali to be perfectly free of air,, a PHYSICAL ann LITERARY. 237 air, which muft proceed from its being incapable of union with fixed air and with the fedative falt at the fame time: . Whence it follows, that, were we to mix the fedative falt with an alkali faturated with air, the air would immediately be expelled, or the two falts in joining would produce anveffervefcence. This I found to be really the cafe upon making thetrial, by mixing a fmall quantity of the feda- tive falt with an equal quantity of each of the three alkalis, rubbing the mixtures wellin a mortar, and adding a little wa- ter. It is however proper in this place to obferve, that, if the experiments be made in a different manner, they are attended with a fingular circumftance. Ifa fmall quantity of the fedative falt be thrown into a large proportion of a diflolved fix- ed alkali, the fedative falt gradually dif appears, and is united to the alkali with- out any effervefcence; but, if the addition be repeated feveral times, it will at laft be accompanied with a brifk effervefcence, which will become more and more remark- able, 238 ESSAYS anv OBSERVATIONS. | able, until the alkali be entirely facurated” with the fedative fait. THIS phenomenon may be explained by confidering the fixed alkalis as not per- fectly faturated with air: And the fuppo- fition will appear very reafonable, when we recollect, that thofe falts are never pro- duced without a confiderable degree of heat, which may eafily be imagined to’: diffipate a {mall portion of fo volatile a body as air. Now, if a fmall quantity of the fedative falt be thrown into an al- kaline liquor, as it is very flowly diflolved by water, its particles are very gradually mixed with the atoms of the alkali. They are moft ftrongly attracted by fuch' of thefe atoms as are deftitute of air, and therefore join with them without produ- cing an effervefcence; or, if they expel a fmall quantity of air from fome of the falt, this air is at the fame time abforbed by fuch of the contiguous particles as are deftitute of it, and no eftervefcence ap= pears until that part of the alkali, which was in a cauftic form or deftitate of air, be nearly faturated with the fedative fale. But re A) PHYSICAL anv LITERARY. 239 But if, on the other hand, a large propor- tion of the fedative falt be perfectly and fuddenly mixed with the alkali, the whole or a large pare of the air is as fuddealy expelled. In the fame manner may we alfo ex- plain a fimilar phenomenon, which often prefents itfelf in faturating an alkali with the different acids: The effervefcence is lefs confiderablz in the firft additions of acid, and becomes more violent as the mixture approaches the point of fatu- ration. This appears moft evidenily in making the fal diurcticus or regenerated tartar: The particles of the vegetable acid here employed being always . diffufed through a large quantity of water, are more gradually applied to thofe of the al- kali, and during. the firft additions are chiefly united to thofe that are freeft of air *. THAT the fixed alkali, in its ordinary / fiate, is feldom entirely faturated with air, feems * Boerh. operat. chym. procefs. 76, 240 ESSAYS anp OBSERVATIONS feems to be confirmed by the following experiment. I expofed a fmall quantity of a pure vegetable fixed alkali to the air, in a broad and fhallow veiffel, for the fpace of two months; after which I found a number of folid cryftals, which refembled a neu- tral falt fo much as to retain their form pretty well in the air, and to produce a confiderable degree of cold when diffolved ° in water. Their tafte was much milder than that of ordinary falt of tartar; and yet they feemed to be compofed only of the alkali, and of a larger quantity of air than is ufually contained in that falt, and which had been attracted from the atmo- fphere: For they ftill joined very readily with any acid, but with a more violent effervefcence than ordinary; and they could not be mixed with the fmalleft por- tion of vinegar, or of the fedative falt, without emitting’a fenfible quantity of air, As it now appeared that feveral alka- line fubftances have an attraction for fix- ed air, I tricd a few experiments to learn the a PHYSICAL anv LITERARY. 241 the relative ftrength of their feveral at- _ trations. _.. © Twenty four grains of magnefia in fine powder were mixed with five ounces of the cauftic ley ina {mall phial, which was immediately corked and fhaken fre- quently for four hours. The ley was then poured off,and the magnefia wathed with repeated affufions of water, and dried. It - had loft about the half of-its weight, and, when reduced to a fine powder, was readi- ly diflolved by acids with an effervefcence which was hardly perceivable: The al- .- kali had therefore extracted its air. I al- fo threw fome frefh magzefia into the ley - which had been poured off, and thereby rendered it perfectly mild and fimilar to a folution of falt of tartar; fo that it effer- _ vefced brifkly with acids. WitTH an ounce of the mild fpirit of falt ammoniac, I mixed a dram of magne- _ fra in very fine powder which had been __ previoufly deprived of its air by fire; and, a. obferving that the magnefia had atenden- _ cy to concrete into a folid mafs, I fhock SeViou. Il. Hh the 242 ESSAYS anp OBSERVATIONS | the phial very frequently. After fome days the powder was increafed to more than double its former bulk; and, when the phial was opened, the alkaline {pirit emit- ted a moft intolerably pungent fmell. It likewife floated upon water, but was not perfectly cauftic; for it ftill yielded fome air when mixed with acids, and alfo ren- dered lime-water turbid : Neither of which would probably have happened if I had ufed a greater quantity of maguefia, or had allowed the mixture to remain a lon- ger time inthe phial. I now wafhed out the whole of the mixture into a bowl, and dryed the maguefia until it loft all fmell of the alkali. It weighed a dram and fif- ty eight grains, effervefced violently with acids, and therefore contained a large quantity of air, which had been drawn from the alkali by a ftronger attraction. HaviNc formerly fhewn, that mague- fia faturated with air feparates an acid from a calcarious earth, which it is not able to do after being deprived of its air by fire; I now fufpected that the air was the caufe of this feparation, becaufe I found PHYSICAL anno LITERARY. 243 found that it was joined to the calcarious earth at the fame time that the acid was joined to the earth of magnefia; and ima- gined that a pure calcarious earth might poffibly have a ftronger attraction for a- cids than pure earth of magne/ia. I therefore diffolved two drams of mag- nefia in the marine acid, and thus obtain- ed a compound of an acid and of the pure earth of this fubftance; for the air which was at firft attached to it, was ex- pelled during the diffolution., 1 then ad- _ ded thirty grains of ftrong quick-lime in exceeding fine powder, fhook the mixture well, and filtrated it. The powder re- maining in the paper, after being well wafhed, was found to be a. magnejia, which, as I expected, was deftitute of air; for it was diffolved by the vitriolic acid without effervefcence; And the filtrated liquor contained the lime united to the a- cid; for, upon dropping {pirit of vitriol into it, a white powder was immediately formed. . WeE muft therefore acknowledge a _ ftronger attraction between the calcarious earths 244 ESSAYS snp OBSERVATIONS © earths and acids than between thefe and magnefia: But how does it then happen, that, if maznefia faturated with air be mixed with a compound of acid and cal- carious earth, thefe two laft, which attraét one another the moft ftrongly, do not re- main united ; but the acid is joined to the magnefia, and the calcarious earth to the air which it attraéts much more weakly than it does the acid? Is it becaufe the tum of the forces which tend to join the magnefia to the acid and the calcarious earth to the air, is greater than the fum of the forces which tend to join the calcari- ous earth to the acid, and the magnefia to the air; and becaufe there is a repulfion between the acid and air, and between the two earths; or they are fome how kept afunder in fuch a manner as hin- ders any three of them from being united together? THE firft part of this fuppofition is fa- youred by our experiments, which feem to fhew a greater difference between the forces wherewith the calcarious earth and ynagnefia attract fixed air, than between _ thofe _ | PHYSICAL anv LITERARY. 245 thofe which difpofe them ‘to unite with the acid. The repulfions however hinted in thesfecond are perhaps more doubtful, thoughthey are fuggefied in many other initances of decompofition ; butthe bounds of my prefent purpofe will not allow me to enter upon this fubject, which is one of the moft extenfive in chemiftry. We meet alfo with a difficulty with re- fpect to the volatile alkali fimilar to the above. Thus a calcarious earth that is pure or free of air has a much ftronger at- traction for acids than a pure volatile al- kali, as is evident when we mix quick- lime with falt ammoniac; for the alkali 4s then immediately detached from the a- cid : And agreeably to this I found, upon the trial, that a pure or cauftic volatile alkali does not feparate a calcarious earth from an acid... Yet, if we mix a mild vo- latile alkali, which is acompound of alka- li and air, with acompound of acid and calcarious earth, thefe two laft, which at- tract oneanother molt {trongly, do not re- main united; butthe acid is joined to the alkali andthe earth to the air, as hap- pens 246 ESSAYS anv OBSERVATIONS pens in the precipitation of a calcarious earth from an acid, by means of the com- mon or mild volatile alkali, I remember likewife a parallel inftance with regard to quick-filver. This metal has an attraction for the vitriolic acid, and when joined to it appears under the form of turbith mineral: But this attra@ti- on is weaker than that of the fixed alkali for the fame acid; for if we mixa diflolved falt of tartar with turbith mineral, the tur- bith is converted into a brown powder, and the alkali into vitriolated tartar ; which change happens the fooner, ifthe pure or cauftic alkali is ufed. Yet, if to a com- pound of quick filver and the nitrous a- cid, we add a compound of the fixed al- kali and the vitriolic acid, or a vitriolated tartar, and digeft the mixture with a ftrong heat, the vitriolic acid does not re- main with the alkali, but is joined to the quick-filver which it attracts more weakly, compofing with it a turbith mineral; while the alkali is joined to the nitrous acid, which it likeways attracts more weakly PHYSICAL anp LITERARY. 247 weakly than it does the vitriolic, and is converted into falt-petre. From fome of the above experiments, | it appears, that a few alterations may be made in the column of acids in Mr Geof- froy’s table of elective attractions, and that a new column may be added to that table, according to the following {cheme, where the alkaline fubftances are all con- fidered as in their pure ftate and free of fixed air. Acids. Fixed air. Fixed alkali, Calcarious earth. Calcarious earth, Fixed alkali. Volatile alkaliand magnefia, Magnefia. * + #* © € & Volatile alkali. * * @ & AT the foot of the firft column eter __ of the metals might follow, and after thefe the earth of alum; but, as I don’t know _ what number of the metals fhould pre- cede that earth, I have left it to be deter- Mined by further experience. THE. 248 ESSAYS anp OBSERVATIONS THE volatile alkali and magnefia are placed in the fame line of this column; becaufe their force ‘of. attraction feems pretty equal. When we commit a mix- ture of magnefia and falt ammoniac to diftillation, the alkali arifes and leaves the acid with the magnefia ; becaufe this earth, by attracting the acid, reprefles its volatility, and it feems alfo to diminifli the cohefion of the acid and alkali, and to render them feparable by a gentle heat. If the magnefia be faturated with air, this likewife, on account of its volatile nature and attraction for the alkali, is driven up along with it, and makes it appear under a mild form, and in the fame manner do the alkali and air arife from a mixture of falt ammoniac and of a crude calcarious earth. ART. PHYSICAL ann LITERARY. 249 Art. IX. Of the Analyfis andU fes of Peat, by ALEXAN= DER LIND, Efquire *. The Analyfis of Peat: IVE ounces of peat, hard, dry, and of a deep brown colour, found fix or feven miles from Edinburgh, being diftil- led with a gradual heat, gave firft an ounce and an half of clear water; after which the oil began to come over, firft yellow, then darker coloured, till it became like tar, and, along with it, a yellow or brown coloured acid oily liquor, ftrongly empy- reumatic, to the quantity of fix drams: This liquor, towards the laft, became al- kaline: But of this there was only a fmall quantity ; for the diftilled liquor that came over firft, was found to be confide- rably acid, fo that it took more than a / Vou, IL. Seca dram * 1744. 250 ESSAYS anv OBSERVATIONS dram of o/. tart. per deliquium to faturate it; if the diftillation had been continued with a very violent heat, there would have come over more alkaline fpirit with the pitchy oil: The quantity of oi] that came over was two drams and an half; it coa- gulates in the cold, and melts with a fmalf heat. ‘There remained in the retort two ounces of coal; which being carefully burnt in a crucible, left eleven drams and a few grains of fine yellow afhes. THAT it may appear how far the Scots and Dutch peats agree, I {hall next give the analyfis of fome Dutch peat madeby Deg- ner. He took twenty four ounces of peat, which being firft reduced to a powder; and then put in aretort, yielded, by a gentle diftillation, a good quantity of infipid phlegm, with an empyreumatical fmell. This being taken away, there followed next a yellow fpirit, and about the neck of the retort, remained fticking a certain white unctuous earth, refembling a volatile falt. The degree of heat being increafed, there came forth a white fmoke, with which a red oil rifing at the fame time, was collect- | ed PHYSICAE anp LITERARY. 25: ed in the receiver, in the form of a thick, pitchy matter, fwiming upon the fpirit, and flicking ftrongly to the fides of the- veflel. Inthe retort remained only a black coal. | Havine weighed each of thefe fepa- rately, the coal was nine ounces fix drams ; the thick pitchy oil, an ounce and an half; the volatile oily falt or {pirit four ounces ; the reft, the infipid phlegm received in an open receiver. ) Tue phlegm being firft examined, was nothing but a fimple clear watery liquor, | without tafte or fmell, Tue redifh yellow liquor that came next, was a liquid volatile unctuous fale, compofed of a watery phlegm, a volatile falt, anda little.oil, which commonly goes under the’ name of fpirit. This mixed with {pirit of fea falt occafioned only a few bub- bles; it raifed with oil of vitriol an effer- vefcence, and turned muddy ; it precipi- tated a folution of mercury in agua fortis, _ into a black powder, turned fyrop of vio- lets green, had no effec upon chalk fpirit of falt ammoniac: Spirit of hartfhorn made 252 ESSAYS anp OBSERVATIONS made no other change upon it, but turn- ing the liquor, which was before muddy, clear. From all which, he fays; it ap- pears, this fpirit is of an alkaline nature; and that, except a little oil, contains chief: ly a volatile alkaline falt. THE oil which was found fwimming up- on the water or fpirit had a {trong empy- reumatical {mell, tho’ not fo fcetid as the diftilled oil of animals, yet ftronger than that of oils diftilled from bituminous mi- neral fubftances, and was in fmell the moft like that of peat fmoke. In the cold, it congealed into a body of the confiftence of foap or honey, or rather into a pitchy - fubftance of a redifh brown colour, being of a cauftic pungent tafte ; upon the fire it melted like wax, and when cold, look- ed like the foot of peat. Tuis oil eafily catches fire, but is foon again extinguifhed. “When kindled, it burns like weak fpirit of wine, but not fo intenfely. When put upon the fire in a {poon, if you approach a lighted candle, it kindles into a flame ; and, upon the re- moval of the candle, is immediately ex- we ' tinguifhed ; PHYSICAL anv LITERARY. 253 tinguifhed; fo it muft be frequently kin- dled before it wholly confumes, THE cinder that remained in the retort, being put in the fire, in a fhort time turn- ed red, and immediately, without fmoke or flame, fell into grey.afhes, nothing dif- ferent from ordinary peat-afhes. Thefe adhes contain lefs falt than thofe of wood, All peat-afhgs do nat yield the fame quan- tity of falt, but differ according to the quality of the peat. From a pound of Dutch afhes. Degner, after boiling, filtra- ting, and infpiffating in the ordinary way, obtained only half an ounce of a redifh impure falt, mixed with much earth: From other peats, that leave after burning a red afh, and that were taken from drier ground, he had an ounce of a redifh im- pure falt. | Tuts falt, he fays, has rather a faline than alkaline tafte; and, when expofed to the open air, runs flowly, after the man- mer of fuch faline lixivious fale. Being : diffolved in water and mixed with oil of vitriol, it becomes turbid, with a finail bubbling up. With fixed fale, or fpirit ! | | of 234 ESSAYS anp OBSERVATIONS of hartfhorn, it turns muddy; with fpi- rit of fea falt, there is no change, the li- quor remaining clear, only a few bubbles, It coagulates foap when boiled with it, in the fame manner that fea faltdoes. This falt diffolved again in water, filtrated and infpiffated until it begins to cryftallize, gathers, when fet in a cool place, into a falt of a cubical form, and, when thrown into the fire, makes a noife like fea falt that is decrepitated. The liquor being further infpiffated and fet to cryftallize a fecond time, yielded a nitrous falt; the re- maining liquor was a pure lixivious alka- Jine fale, that made a {trong effervefcence with acids. From all which it appears, that this falt is principally compofed of a falt like that of common fea falt, with a - fmall proportion of the alkaline kind, WuarT remained after the falt was ex- tracted, out of the afhes, was only a flimy earth and fome fand. To thefe analyfes, I fhall add two others, Dr Smidberg a phyfician at the Hague, having diftilled fome peat in a retort, ob- tained from it a fpirit, an oil, a volatile falt, Ue eee eae es PHYSICAL any LITERARY. 259 falt, all of them much like that of harti horn. Ottoman, an apothecary at Stut- berg, from a Swabian peat, had a volatile fpirit, like that of fpirit of tartar, a foe , tid oil, but no volatile falt. The Ufes of Peat. THE principal ufe of peat is burning, ~ not only for the fervice of families, but likeways for that of a great many trades; ‘fach as brewers, bakers, diftillers, making of lime, &c.: And, as there is a good deal of difference in peats, and fome kinds _ ‘preferred to others, I fhall here take no- ‘tice of fome of the principal differences. THE firft is, with refpect to the place out of which they are taken. . Such as - aregot from brackifh grounds, near the fea, alfo fuch as are impregnated with vitriol or fulphur, have a difagreeable fmell, and ae are hurtful to the health. In Zealand, | they have a kind of peat, which, when : ~ burning, makes every body in the room look like a dead perfon; and, when they fit 256 ESSAYS anp OBSERVATIONS | fit long by the fire, grow faintifh: It alfe turns the bottom of their veflels white; Peats taken from moffes, free of all mine- rals, have none of the above mentioned, or any other bad effect. As to the matter itfelf, that differs in many refpects; fo that in the fame mofs, _ according to thé different depth of it, there are three or four kinds of peats found. In North Britain, in the province of Gro- ningen, and in feveral other places, that | which is uppermoft, is light and {pungy; further down, better; and at bottom is. a fubftance that is black, and makes a firm folid peat. - In Holland, that which lies uppermoft is beft, being of a dark or black colour, to which others fucceed of different colours and fubftances not fo good. That which is light and {fpungy, taken from a barren heathy ground, or from a dry fandy foil ; alfo fuch mofs as is much mixed with pie- ces of rotten wood, roots, mud, gravel, or fand, or which, confuming quickly, leaves behind a great many impurities mixed with its afhes, is bad. PEATS PHYSICAL anv LITERARY. 257 Prats differ confiderably, according to the pains beftowed in making them. Such as are perfectly freed from all hétrogene- ous matter, well knead and wrought, are the beft of all. Upon which account, peats, made in the province of Holland, where no labour is {pared in the working them, are preferable to all others; tho’, in other places, the fubftance may be e- qually good. A Dutch peat fix inches long and three or four thick, will weigh a pound; a peat made at Nimiguen, of the fame dimenfions, will not weigh above half a pound, often lefs. It is a general obfervation, that all peats made of mofs- mud, and well knead, are confiderably heavier than fuch as are only cut out of the mofs. - Prats that are of a dark colour, and folid, that continue longeft in the fire without confuming, that have a good cin- . - der, and fall into white afhes, are moft _efteemed: On the contrary, fuch as are light and porous, confume quickly in the ' fire, leave no cinder, but a great many impurities and afhes, are little valued. Vou. II, Kk THE all 258 ESSAYS anp OBSERVATIONS THE afhes of peats differ alfo confide~ rably in colour, quantity, and weight ; as to which nothing certain can be deter- mined, Sometimes the white, fometimes the grey, and at other times the red, are heavieft. In Friefland, the peat that leaves the red afhes, Degner fays, is heavieft 5 about Nimiguen, thofe that are red are found lighter than the Dutch peat which leaves a grey afh. THE brewer, diftiller, and other trades, prefer the peat that leaves a red afh, which, tho’ it feldom has a firm cinder, yet burns violently. The baker makes choice of the light turf ; and, in North-Holland, where the inhabitants are extremely clean- ly, they ufe the peat that has red athes, upon account of their being heavier than the white, and therefore not fo apt to fly about and fpoil their furniture. BEsIDEs the ufes now commonly made’ | of peats, there are two others in which, I think, they may be employed with great — advantage, ‘The firft is, the fmelting iron ore: The only fewel at prefent ufed in that operation is charcoal of oak, and other hard 1 hy 7 ‘i PHYSICAL ann LITERARY. 259 hard woods; any attempt made to do it wey? ; - with pit-coal, fo far as I can learn, has Fi hitherto proved unfuccefgful ; and indeed, from the nature of that fubftance, there ‘ feems little hopes of ever bringing it to ~ anfwer the end, the bituminous or inflam- -mable part of pit-coal haying nearly the fame effect upon iron which common ful- phur has. It deftroys, as experience fhews, the malleability of iron and all other me- tals, Pit-coal has likeways another bad quality, which I have often found to my coft. With a ftrong heat it runs intoa glally. fubftance, which in time, by its fticking fo clofely together, and to the fides of the furnace, quite choaks it up, and, by its tenacity, hinders the metallic parts from finking downwards, as they would _do by their natural gravity. What is chiefly wanted in finelting, is an open fire; ‘the furnaces are commonly fufficiently clogged with the itony andother hetero- Bencos bodies united with the ore, which rs ‘un into elafs without the addition of any ‘ fach foreign matter as has a tendency to 5 Mitrification.. The charred wood, on the contrary, » 260 ESSAYS anp OBSERVATIONS contrary, keeps always an open fire, the inflammable part of which is fo far fron harting metals, that it preferves their mal- leability, by fupplying with its own ful- phur that which is dettroved or carried off from the metal, by the intenfe heat em-, ployed in the imelting ; and this is fo far true, that iron reduced toa ca/x or friable fabttance by calcination, has its mallea- bility reftored by being fluxed with pow- dered charcoal only. And this we may here obferve, by the bye, as an inftance | of the difference of fub{tituting a vegeta- ble in place of a mineral fulphur, THE peat then being intirely a vege- table fubftance, there feems nothing more requifite to make it a proper fewel for {melting iron, but the being able to raife by its means a heat fufficient for that pur- pofe. This, experience fhews, cannot be done with the peats we now have, The mott likely mechod of obtaining this end, I think, is, to bring them to be as folid and compa¢t a fubftance as poflible. The denfett bodies, ceteris paribus, when tho= roughly heated, are the hotteft: Hence if Foy :. PHYSICAL anv LITERARY. 261 it is, that metals, as they are the heavieft bodies, fo they reach the greateft degree of heat. ‘The fame holds in fewel; the hardeft woods are made choice of, when a ftrong heat is wanted ; and, even in common peats, I have fhewn you how far preferable the hard and folid are to the light and fpungy. By fome experiments which I have made, I find it to be no difficult matter to bring peat to a confi- derable degree of folidity, as you your- felves may fee by the fpecimen I now fhow you. The fimple operation of grind- ing, does the bufinels ; ;and as a peat, when taken out of the mofs, is a foft body, and eafily grinded, a machine may be eafily contrived to grind, at a moderate expence, feveral tuns in a day. The charge of digging peats, cutting them into {quares or the form of bricks, when of a proper drynefs, will be little different from that of making peats in the : ar) i. dinary way- The folidity of peat pre- pared in the manner mentioned is fur- prifing ; its fpecific gravity being fome- what greater than that of pit-coal. I compared 262 ESSAYS anp OBSERVATIONS compared a peat of this kind with a piece of coal brought from Baron Clerk’s coal- mines near Edinburgh, and, by the hy- droftatical balance, reckoning water 1000, their {pecific gravities were nearly as fol- lows, pit-coal 1287, folid peat 1303. From what has been faid, it appears, that, if iron could be made with peat, it would be of great fervice, particularly in fome places of North Britain, where peat is to be had in plenty,. along with iron, which now lies unwrought for want of wood: And, even where wood may be found, if peat brought to the confiftency I mention would do the bufinefs, it would come cheaper than charred wood, Ano- ther advantage of this kind of peat, would be the fmelting of lead with it alone, which cannot well be done at prefent, without the help of pit-coal, which in fome places muft be brought from a con- fiderable diftance, and at no {mall charge. THE other ufe I would propofe of peat, is the employing it as dung, for the fer- tilizine of ground, when prepared in the manner I fhall afterwards mention. [am not PHYSICAL anp LITERARY. 263 not ignorant, that the afhes of peats are ufed for that purpofe with great advan- tage, not only by themfelves, but likeways mixed with other dung, and even the duft of peat that remains‘at the bottom of _ peat-ftacks; but in that ftate it has not the effects of dung, nor are its effects e- qual to what they would be, were it right~ ly prepared. To fet this matter in a pro- per light, I muft be allowed to fay fome- thing in general of vegetation, and of the ufe of dungs in promoting it, VEGETABLES which increafe by feed, as is the cafe with by far the greateft part, if not all of them, are at firft plantulas “‘wrapt up in a very {mall bulk in the end of the feed; which, when put in the ground, by the moifture they find there, extend themfelves, and are firft nourith- éd by part of the feed itfelf, which does the fame office to the young plant, by af- _ fording it a finer nourifhment, as the pla- | eenta does to the embryo. When the plant & becomes ftronger and. fhoots forth its y Boots, it then draws its nourifhment from the 8 - 264 ESSAYS ann OBSERVATIONS the earth. Thus it goes on growing un- til it has attained its utmoft perfection: After which it gradually decays, dies, and at laft rots and putrefies. By putrefacti- on, the parts of which the vegetable was compofed, viz. its falts, oils, phlegm, and éarth, are feparated: Part remains upon the ground where the plant falls ; but the far greateft part being volatile, flies up into the air, from whence it defcends a- gain upon the earth and incorporates with it. The fame materials ferve to nourifh new plants, there being no part of them, as we all know, loft. What we call a vegetable mould, is an earth in which there is ftore of fuch parts of ve- getables lodged, the matrix in which they lie being a fine but barren fand. As long as there is a fufficient ftock of fuch particles in any earth, that ground is - fruitful; but when this is exhaufted, which happens fooner or later, from the quantity of vegetables nourifhed by it, and carried off for the ufes of life, it be- comes barren, The only remedy, when ne GES PHYSICAL anv LITERARY. 265 ind better can be had, is to allow it to reft, until it receives a new recruit from the air, in which are perpetually doating, and falling down upon the earth, particles of all kinds proper for the nourifhment of plants. But, as this isa tedious way of recovering the fertility of ground, the better and more expeditious one, is by laying dung upon it, which being wholly made up of putrefied vegetables or ani- mals, equally proper for nourifhing plants, the parts of which both are compofed being the fame, and the tranfition from the one to the other eafy; the ground, by this new acquifition, becomes again fer- tile. Every vegetable then whoie parts are fet loofe by that laft fermentation of nature, putrefaction, affords a proper pd- bulum for vegetables; and the great di- ftinGtion of plants, which commonly lies in a very {mall part, and that too the motft volatile, being taken away by putrefacti- on, all vegetables, when reduced to that ftate, feem to be pretty much upon a par ‘for that purpofe. Now, to return to what evo. Il. Lh : I 266 ESSAYS anp OBSERVATIONS * I intended to fay, and to which what f have mentioned was only a kind of pre- amble: Peat mofs, being wholly a vege- table matter, muft, if reduced toa tho- rough {late ef putrefaction, anfwer the fame purpofes for fertilizing ground as. other putrefied vegetables. While it lies in the mofs, there is too great a quantity of water to raife a fuflicient degree of heat, to bring the vegetables of which peat-mofs is compofed, whether actually growing, decaying, or decayed, toa com= pieat degree of putrefaCtion. But, if it were taken out of the mofs, and laid in heaps like other vegetables to rot, with a degree of moifture tuitable for that pur- pofe; and if, to begin and alfo quicken the putrefaction, green frefh fucculent plants were employed in a fufficient quantity firft to raife a heat; this I make no doubt would, by communicating it to the mofly tubftance, in a fuitable time, and by right management, reduce the whole mafs to the ftate defired. This already is in fome meafure practifed in Holland, where they Mr PHYSICAL anv LITERARY. 267 mix the duft of peats with ordinary dung, in making of dung-hills. I fhall conclude this paper with only mentioning two other ufes of peat, which I had almoft forgot, viz. that peat-duft ftrawed upon ground where peafe or o- ther feeds are fown, in order to have an early crop, 1s an excellent prefervative of fuch vegetables from the froft; as it ‘keeps the ground warm, by not allowing the cold to penetrate into it. And that there is nothing properer than peat to ftop water, and to confine it, in the making of fifh-ponds, &c. This I learned from his Grace the Duke of Argyle, who I ob- ferved ufed it with gat fuccefs for that purpofe. ART. 268 ESSAYS anp OBSERVATIONS Ah Ts. ae The Effects of Semen Hyofcyami albi, by Dr ARCHIBALD HamILTon Phyfician in Edinburgh *. , Student of phyfic, of a thin habit of body, about twenty years of age, had been, for two years, in the ufe of ta- king a {mall quantity of white henbane- feed to make him fleep, and without any bad effect. But, on Friday March the Sth 1754, betwixt four and five in the af- “ternoon, he, in order to procure fleep, f{wallowed about twice as much of this » feed as he could'take up betwixt his fore- finger and thumb, 7. ¢. nearly 25 grains. He felt himfelf, half an hour after, very heavy and much inclined to fleep ; his eyes were oppreiled, and fpirits dejected, © with a general laffitude and inadtivity O- | ver his whole body. Thefe fymptoms emt: ch: * May 1. 1755. peas PHYSICAL anp LITERARY. 269 ftill increafing, he went abroad and drank tea about fix o'clock; and with ‘great difficulty could keep awake, having fome- times let fall the tea-{poon infenfibly. He complained of a great uneafinefs and dry- nefs of his throat, and that the tea in {wallowing was like to choak him. He had alfo fome gripes in his belly. After he drank tea, he was foon feized with con- vulfions and fo great a degree of infenfi- bility, that he did not know the people who were in company with him. He . fpoke many incoherent things, and, at the | beginning of his illnefs, faid he was afraid - he had taken poifon, The people who - were with him being alarmed, ordered hi m to be carried home, and fent for me. 1 found him incapable of giving any ac- count of his misfortune. His eyes were open and rolling, now and then he was feized with tremors, ftartings, ‘and cor- -vulfions, grapling the bed-cloaths, his head, face, nofe, and other parts of his body, in the manner patients frequently do 270 ESSAYS anv OBSERVATIONS do in nervous fevers. His pulfe exceflive- ly {mall and low, with /ub/ultus tendinum. The fenfe of feeling feemed alfo impaired ; for, when I[ pinched his fkin, he made no complaint. He had no inclination to vo- mit, nor had any {tool from the time he took the feed. I ordered him immediate- ly a vomit ; and in the mean time Dr Bof- well was fent for. He fpit out the vomit ‘as foon as it was poured into his mouth; fo that it appeared he was either not de- prived of tafte, or could not let the vomit over. A fecond vomit was inftantly gi- ven, which was alfo {pilt or {pit out. A folution of white vitriol was afterwards given, the moft of which he fwallowed without the defired effet. A ftrong cly- {ter with antimonial wine was adminittred, which he kept about twenty minutes. He got a fecond injection an hour after. As he continued in the fame miferable ficuation, a blifter was applied to his head, and finapifms to the foles of his feet. He pafled the night in the fame condition without PHYSICAL anv LITERARY. 271 without fleeping, and was alternately {ei- zed with convulfions, ftartings, and catch- ed with his hands at every thing about him, In the morning, he became more fenfible, and began to fpeak a little di- ftin&tly, although his head was yet very confufed and muddy. Fe told what quantity of the feed he had taken, and for what purpofe. His pulfe was now fomewhat ftronger. He got a purgative infufion, which operated four times that day. In the evening, he was {till more diftinct, although his eyes continued hea- _vy and his head confufed. His pulfe was now quick, full, and {trong ; and he com- plained of a great pain and weight in his head. He was blooded about twelve o'clock that night to the quantity of twelve ounces. He fweated plentifully, | had good fleep, and was altogether fen- fibleand diftin® next morning, ART. 272 ESSAYS anp OBSERVATIONS, 15 10b dys thi) The Effects of the Thorn-Apple, by Dr A+ BRAHAM SWAINE Phyfician at Brent- ford *. > Oprrr BuULMER, a man of a ftrong ~ conftitution, 69 years of age, and . who had enjoyed a good ftate. of health all his life, tll about two years before, when he was firtt afflicted with the gra- vel; in O&ober 1746, being advifed by a friend to take a decoction of the fruit . of the common burdock, as a remedy for his difeafe, by miftake gathered the fruit of the ftramonium or thorn-apple. Af-= ter dividing three of thefe, each of which was as big as a {mall hen’s egg, inte two parts, he boiled them in a pint of milk, — which, when a little cooled, he drank off about eighto’clock in the morning fafting. Prefently afterwards, he became vertigi- nous * May 1. 3555. PHYSICAL aNp LITERARY. 273 mous or giddy; and therefore rofe from his chair to take the air, with an intention to pluck more truit. In walking two or - three hundred yards from his houie, he _ flaggered'as if drunk, feared he fhould fall on his head, and that he was about to lofe his fenfés; but had no ficknefs “nor the leaft inclination to vomit. “As -foon as he got home he went to bed, and, complaining of an exceflive drynefs of his tongue and throat, a little water mixed with wine was given him; he alfo felt an odd fenfation of drynefs in and violent -girding a-crofs the thorax. In lefs than half an hour he began to faulter in his Apeech, became infenfible, reftlefs, and ‘muttered frequently; in which condi- ‘tion I found him. His extremities, and alfo the trunk of his body, were cold. His pulfe fmall and quick. He often raifed himfelf on his knees, con- | tinually ftretched out his arms, and em- ployed his hands as if fearching for fome- thing he wanted; his eyes were dull and. “heavy ;. after fome time, he became dumb and more quite, had almoft no pulfe; and, ~ Vou, Il, | M m upon 274 ESSAYS anD OBSERVATIONS upon his being taken out of bed, that ic might be put into better order, his limbs were vifibly paralytic. Although he changed poftures a little, yet he remained *ftupid for fix or feven hours; then he ra- ged furioufly, requiring two perfons to — hold him in bed ; notwithftanding which, © he raifed himfelf up, tofled greatly, and feemed to catch at the byftanders with his hands, uttering incoherent fentences. At laft he became fenfible and more quiet, reftlefS and delirious. by turns; and, about — ten o’clock in the evening of the fame day, perfectly recovered. After taking a pur- gative, he flept well all night, and had fe- veral ftools in the morning. For the {pace of fourteen hours he neither flept, vomited, nor difcharged any thing by {tool or urine, though he frequently paf- fes urine at other times, being grievoufly afflicted with the gravel, ART. er PHYSICAL anv LITERARY. 275 ART. XII. The Effect of Mufk in curing the Gout im the ' Stomach; by JAMES PRINGLE, E/quire, late Surgeon to the third Regiment of Foot-Gaurds*, A. Gentlewoman, aged 43 years, natu- rally of a delicate conftitution, who has been for feveral years fubject to hy- fteric fits, attended with a dry afthma, which her fhape much contributed to, | was frequently attacked, to a violent de- | gree, with the gout in her head and fto- mach, as well as in all her extremities; and-with which fhe was lame the moft part of Summer 1745. On the 3d of No- vember following, fhe was violently fei- zed with itin her ftomach, which occafion- ed violent hiccups and convulfions of the part. The defcription the gave of it was, that, as foon as thefe fits feized her, there came on a violent working of her ftomach, and fo great an agitation of her back, to that Tat April 3. 17463 276 ESSAYS ann OBSERVATIONS © that her maid was not able to keep her hand on it. By degrees it rofe to her throat, when fhe was almoft ftrangled. She could by no means lie down, but was forced to fit night and day in an eafy chair ; and, even then, if fhe leaned her head to the one fide or other, it gave her great pain ; fo that fhe was obliged to fit in an erect pofture. Her legs were very. much fwelled, which fubfided a little on laying them on a chair; but as foonasthathap- _ pened, the afthma returned. She did no” , thing all this while but keep herfelf warm, now and then drinking a little ot fome gene- rous wine (as fhe faid,to keep it out of her {tomach), and once or twice took a little of the t:éd#. facra. On the 21ft of — November, about 9 o’clock at night, a la- dy of her acquaintance, who had feen her in this condition, defired me to vifit her, though fhe doubted if I fhould find her a- live. Accordingly I went; and, as I had {een fach extraordinary effects of the Ton- quin medicine in the /imgultus, and had heard from Mr Read of its efficacy in o- ther nervous cafes, I imagined it might be peg eats hon ¢ yi eer Sib au Sinha. Pudatis PS ais He aul goat Apnisies ary Poet Gihye Bee mebinatd jays oat ‘ sees bs P8Sh |, be ae ames: 243 tt | Steak P> ty Beat ih ahh » Peeroye bh hte creat! bile 10-083 en oe casslavania: O19 i dar; a ossithy am Ra Beal ah erent ts a 4) a a PP ae ose ~ ae ene om ii , Ain “ 4 J “9 M "nd gtx Malt Dos Greer Rea ope : x / - Be 3S ot Denn gia l oshoe eecy aunt - my ak & " a ea} - QW Y, UY, Y Wy ‘PHYSICAL ano LITERARY. 277 | be of fome fervice here: And therefore I fent her the following bolus. R Cinnab, nativ. 3 Antimon. ana gr. XXv. Mofch. opt. gr. xvi. - Syrebalf gq. f- F- bolus. Bur although this is Mr Read’s com- mon‘dofe; yet, as fhe was very weak, I or- dered her to take only the one half of it immediately, drinking after it a cup of brandy, and the other half in fix hours af- ter. Next morning 1 found her much better, having from the firft dofe no more convulfions in her ftomach. I then ven- tured to give hera whole bolus at 9 o’clock in the morning, to be repeated every four hours until fuch time as fhe fhould fleep or {weat : And, notwithftanding the cold- nefs of the weather, and her being obliged to fit in a chair; yet, by the time fhe had _ taken four bolufes, a plentiful fweat and _ fleep enfued, and then fhe was able to lie ina horizontal pofture on her couch with- out the return of her former fymptoms. This 278 ESSAYS anp OBSERVATIONS This {weat continued from the afternoon of the 22d till the 24th at night, with ve- ry little intermiffion. I gave over the bo- lufes, and ordered her ajulep, to eight ounces of which I put twelve grains of mufk, to be taken ad ibitum. In this me- thod fhe continued till the 27th, quite ea- fy and free from all her former fymptoms, and even the fwellings of her legs almoft gone: But, as on this day fhe fancied the gout in her ftomach was returning, I gave her another bolus. She complained this time of the intolerable heat of the brandy, which was the firft thing fhe had found warm in her {tomach during this illnefs. On the 29th, fhe was apprehenfive of ano- ther attack, and took another bolus; af- ter which fhe found herfelf very well, and walked about the room, the fwellings of her feet being quite gone. And, on the ath of December, went out in a chair to thank the lady who fent me to her, and continues to be well to this day. ART. ——— se _ * Feb, 5. 1756. PHYSICAL anp LITERARY. 279 ART. XIll. An Account of an uncommon Effedt of anti- monial Wine; by Dr JAMES WALKER Surgeon and Agent for the Navy at Edin- burgh *. { HE winum benedictum is univerfally known to bea ftrong emetic, when given in a large dofe; and it has alfo been often prefcribed in fmaller quantities as an attenuant, fudorific, and diuretic: But an accident lately difcovered to mea very different effect of it from any of the a= bove mentioned. BEING one evening, in December 1755, a little hot and feverifh, with a quick and full pulfe, I went early to bed, and drank a full Englifh pint of fack whey, which . Thad ordered one to make for me. Very foon after this, I fell afleep, and continued all night oppreffed with an unufual drow- finefs: At ten next morning, I with great difficulty got fo far the better of this le- _ thargic difpofition, as to get out of bed ; when 280 ESSAYS ANp OBSERVATIONS when I found myfelf ftill heavy and in- clined to fleep, with a laflitude and numb- ne{s in my limbs, fo that I could fearce ftand. Being thus incapable to go about bufinefs, I refolved to ride out on horfe- ‘ back; and, having mounted with fome dif- ficulty, found my head very giddy, and had much ado to keep myfelf from fall- ing afleep. After having rode three hours, I returned home much in the fame fitua- . tion, and was furprized to find two ap* prentices with the fame complaints I had myfelf: They could aflfign no caufe of their being fo affected, nor had they eat any thing but their ufual food, except the curd of which I had got the whey. Being led by this to fufpect fomething uncom- mon in the wine with which the poffet: was made, I called for it; and had a bot- tle brought me containing vinum benedic- zum, which had been made about a month , before ; and the bottle having been put in an improper place, was the reafon of its having been miftaken for Lifbon, I found | had drank in my whey about 2 gill and a half of this emetic wine, and was — : | : ; PHYSICAL AND LITERARY. 28t was furprized it had not vomited me oe". Thinking, however, that the ., finely. _attenuated particles of the antimo- V Ping Uke. moftly fafpended in the curd, igs time acticilarly at the two young ' who had eat it, whether they geo deeesd with any n4ufea or vomiting ; ‘but they told me they found no other ef- fe& but a heavinefs and great inclination to fleep. 'Fhis drowfinefs continued with them two days; but I did not find myfelf quite free of it at the end of four days. Ido not know if it be worth while to ob- _ ferve, that, the day after I had drank the __ above whey, my pulfe was ten in the mi- ‘nute flower than it had been the night before, It may be proper however to take notice, that the vinum benedium which was ufed by miftake, inftead of Lifbon, eta. uaade exactly as is directed in the E- | _ dinburgh Difpenfatory ; and I have fince found half an ounce of it vomit a patient very well. Myo... Nn Aue / 282 ESSAYS anp OBSERVATIONS ART. XIV, An obftinate Dy fentery cured by Lime-water: : a, ' ov about by }ames GRAINGER, M. bi on hor‘ at London ™*. Arfdale, a ftout, middle aged, but intemperate foldier, was feized, November 1751, with thivering and other fymptoms that precede an acute diforder. The day following, he went frequently to ftool, and evacuated blood to the quantity of a: gili every quarter of an hour. Tho’ the fever was inconfiderable, yet, as he was » ot a fanguine habit, the lancet was not fpared. He fwallowed fome ipecacuan vomits; was gently purged every third day with rhubarb; and had fmall quan- tities of opium at bed time to hinder his - rifing in the night. The third week his fundament came down, attended with but little pain, uulefs when he went to ftool. This fymptom, however, wrac timeoufly. removed by fomentations of a decotne- of oak-bark, December; his ftools, tho’ lefs / * May 3. 1753. a wea of ees ny hae i re, PHYSICAL anv LITERARY. 283 jefs frequent, were mixed with blood and mucus. ‘Then the gripes feized him in good earneft, fometimes fixed and tortu- “ting like a ftitch in the baftard ribs, at other times wandering with bo borygmi, now as it were twifting his guts, then cutting him in two, as he expreffed it, and bending him forward. They were always moft fevere before ftool, eafier in the time | of evacuation, but eaffeft after. With thefe fymptoms were complicated a dy- fury and piles, greatly inflxmed but bleed- ing none. Thefe difmal complaints con. tinued almoft equally violent for three months, altho’ V, S. emetics, vitr. antimon, cerat. mild antiphlogiftic purzatives, opi- ates, lubricating and aftringent re- medies were ufed, as the fymptoms indi- cated. Opiates, tho’ they eafed him, fel- dom procured undifturbed repofe, and al- ways affected his head ; this confequence of Jaud. was more effectually prevented _ by bal/. locatel. than any thing elfe. Vo- mits always relieved him; but increafed _ the pain of the hxmorrhoids. Aftrin« gents, though they bound him up for a iri i little 284 ESSAYS any OBSERVATIONS little time, moft generally brought ori _afterwards a more frequent inclination to fiool, with increafed formiza,- Clyfters were impracticable on account of the piles ; but he found confiderable fervice from themilder purgatives, with calomel; ands when the fwelling of his fundament was removed by /u/phur and emollient, difcu- tient applications, they became highly ufeful. In the 4th month, the region of the ftomach fwelled, with rednefs of his face, efpecially after food, and continued for fix months, although its removal was: attempted by bitters, and the bark, (cau- tioufly combined with purgatives), mul- led claret, and camomile tea, while pro- per external applications were not forgot-’’ ten. April and May, the hemorrhoids and dyfury left him ; but his ftools became thinner, more acrid, and intollerably fe- tid. Then he was feized with a hiccup, his face looked ghaftly, his extremities turned cold, his pulfe became quick, fmall, irregular, and his gripes were rather a= bated. Evacuations in thefe deplorable circumflances were improper,’ but fina- pifms, ~ “mag PHYSICAL sawp LITERARY. 2385 pifms were applied to the foles of his feet, and epifpaftics to the region of the ftomach, with fome fuccefs. A bolus of bark, caftor, and camphire was given e- very third hour, and wafhed down with a glafs of mulled claret ; his guts too were fomented with anodyne, emollient, and antifeptic clyfters. By thefe his deadly fymptoms left him, he could fit up at the fire, and had not above 12 ftools in the _ 24 hours, which were however ftill icho-_ rous. I could not find from the nurfe that he ever paffed any of the villous coat of the guts, though /cybala were frequent- ly evacuated, About the end of May, he was able to walk round the ramparts of Fort-William, and he told he thought . ¥ . he would recover, were he fent from Locha- — bar. On this, he was carried, by water, to the Ifle of Mull, being provided with proper medicines to forward his recovery. Here, though the hiccup and facies bippo- cratica did not recur, yet his gripes did; and he purged blood and worms almoft inceffantly. The latter end of July, he was fent back to the Fort a perfect fkele- ton 5; 286 ESSAYS anp OBSERVATIONS ton; where, though I am convinced the air is inferior to that of Caftle-Dowart in Mull ; yet, as great care was taken bothof his diet and medicines, he paffled no more worms, his gripes only feized him at ftool, whither he went much more fel2om than formerly; what he pzffed now ap- peared to be mucus mixed with pus and | ftreaks of blood. Very fmall dofes of ipecacuan, vz. eight grains three times a day, were then adminitred to him every third day; but, though they relieved by operating both up and down, yet they fickened him fo much, that I was obliged to fubftitute a bolus of calomel over night, and a purging ptifan next morn- ing, in their place. The difeafe, how- ever, did not yield; and, when the regi- ment was ordered to march for Berwick upon Tweed, he was put aboard the veffel that carried our baggage. This was a hardy ftep, confidering his weaknefs, and ‘the length and danger of the voyage; but he could not be carried with his com- rades over the Black mountain; and he defired to die any where, rather than re- main PHYSICAL anp LITERARY. 287 main in Fort William. Five or fix weeks ‘after he landed at Berwick, his {tools were more numerous, and {till very painful. Sometimes blood, fometimes flime, fome- times ichor, and once he pafled a great quantity of hardened excrements, which relieved him of a dull pain of his left hy- pochondre; his legs too, at night, {welled and pitted to the touch, and his ftomach was often inflated. Bitters, with fteel, were prefcribed, and camomile tea drank for breakfaft, while the utmoft regard was had to diet; the vitr. antimon. was again tried, and alum poflet recommended. The dyfentery baffled all our attempts ; and now, defpairing of his recovery, I ordered . him to drink lime water, with a third part milk, to the quantity of an Englifh pint and a half every day: It was at the latter end of November 1752. In three days time, there was a fenfible change to the better, his ftools were lefs frequent, and his pains abated. Encouraged by this happy beginning, he was ordered to drink /id, iii, of lime water a day. This, *~hree weeks, made him fo coftive, that 1 588 ESSAYS ann OBSERVATIONS I was obliged to clyfter him, and dimi- nifh the aq. calc. to the quantity firft or- dered. In fix weeks from his taking this medicine, he was fo thoroughly recovered, that he was difmiffed the hofpital, and foon after marched to his company at Carlifle, where he ftill, enjoys perfect health. The diforder was on him full 14 months; and I have reafon to think his recovery was chiefly owing to the lime- water, after the moft celebrated antidy-— fenterics had been ufed in’ vain. THE dyfentery is endemic at Mary- burgh, near Fort-William, and commonly attended with procidentia ani, piles, dyfu- ry, abdominal inflations, oidema’s, and hiccup. Many of the foldiers died, efpe- cially the more intemperate; between the 20th and 35th day, is the fatal period. Thofe who died had mortifications of the great guts: It began with us about. the latter end of October; autumn however is its ufual feafon; it rages commonly two months, though many have it all the winter, and | always obferved them worft — sul PHYSICAL anv LITERARY. 289 in rainy weather. It may be worth while to obferve, that of late lime-water princi- pally conduced to cure an Officer of a dy- fentery, while another was effectually cu- red of a weaknefs in the bladder, by the fame remedy. — Vox, II. Oo AR’. 290 ESSAYS anp OBSERVATIONS ArT. XV. The anthelmmite Virtue of the Bark of the wild Cabbage or Bulge-water Tree ; by the late MrPeterR Ducuip, Surgeon in. Jamaica, ma Letter to ALEXANDER Monro fenior, M. D. & P. A. HE writers on the difeafes of the Weft-Indies generally take little no- "tice of the inhabitants of Jamaica, young and old, white and black, being much troubled with worms, efpecially the long round fort. They are however fo frequent, that every prafifer ought to have regard to them in treating moft of his patients. I imagine thefe worms infeft the inha- bitants here on account of their fweet vifcid bread-kind, to wit, plantains, yams, bananas, {weetifh potatoes, &c. which are fit nourifhment for thefe vermin, I was lately allowed to open a Gentleman’s child, that, at feven months of age, died of vo- miting * May i 1755; PHYSICAL ann LITERARY. 291 miting and convulfions. [n its inteftines there were twelve large worms: One of them filled the appendix vermiformis, and three of them were intertwifted in fuch a manner as to'block up the opening at the valvula Tulpiit, fo that nothing could pafs from the finall to the great guts. Nature has bountifully provided the people here with a powerful remedy a- gainit fo great an evil. This is the bark of a tree growing plentifully in this ifland. The inhabitants call it wi/d cab- bage or bulge-water: And, from whatI have — feen, it appears to be the moft powerful vermifuge yet known; for it frequently brings away as many worms by {tool as would fill a large hat. It is commonly given in decoction, but not in any regu- lar quantity ; the negroes Leing generally the preparers of this medicine, and there- fore no wonder that it fometimes has ve- ‘Ty violent effets, Iam now making ex- periments for afcertaining the dofe to pa- tients of different ages, and {hall foon fend _ you the refult of my trials, together with ~fome of the bark itfelf. ART, 292 ESSAYS aNp OBSERVATIONS A aka Da XVI. The Defcription of a monftrous Fetus; by Mr — Joun Mowat Surgeon at Langholm, iz a Letter to. ALEXANDER Monro /fenior, M: D. & P.. A. * ca learned men having of late x» years difputed about the formation of monfters, it is probable the hiftories of them may be of ufe in accounting for fome phenomena in nature; on this ac- count, I fend you the following defcrip- tion of one, which will be better under- ftood by the figures which young Profef- for Monro caufed to be drawn of it, of half the natural dimenfions. See plate VI. fig. I- eS as re when fix months with child, had this abortion, which lived half an hour. TAB. * May ie 1755. a : 7 ee a ee PHYSICAL ano LITERARY, 293 Tas. VI. fg. 1. AA The lower parts of the bodies of two female fetu/es, with their lower extremities in a natural ftate, B The navel-{ftring common to both fetufes. C The bodies joined immediately above the navel. DD The fupericr extremities of the more compleat fetus, which is here repre- fented moft in view. dd ihe fuperior extremities of the o- ther fetus. All the four being of a natu- ral form. E The /lernum of the more compleat fetus, which had clavicles joined to it in the common way, as the other alfo had, F One neck common in appearance to both fetu/cs, The face and ears, being natural, need no letters of reference to their parts, G The forehead had hair farther down - than ordinary. --H..The top of the head of an extraor- dinary breadth. I The hairy fcalp covering the parietal bones. K The 294 ESSAYS anp OBSERVATIONS K The right temple of the fetus D D. L, The teguments covering the occipi- tal bone. ci M The occiput of the other fetus, Fig.2. The back view of thefe fetufés, where the head, neck, and fore parts of the thorax only are reprefented. NWN The fcalp over the four parietal bones. OO The two occipital bones. P P Two ears joined together. Q Q The two meatus auditorii. R A paffage by which a probe could be put into the @/ophagus, S The neck of the fetus D D. T The flernum, UU The forepart of the arms, THE back parts of neither fe7us are drawn, having nothing preternatural. Where the abdomen of each fetus was di- ftinét at AA, the vi/cera were in a natural ftate, and, in the undivided cavity of the belly above C, there were two ftomachs, livers, fpleens, inteftina duodena, jejuna, and ilium; but I faw only one omentum and one a | PHYSICAL anp LITERARY. 295 one pancreas. One diaphragm divided the abdomen from the thorax, but it was pierced by two vene cave and two efophagi, and two aorte defcendentes pafled ‘between its appendices on seis fide: wheresthe vertebre Were. « : ale k was a frernum.to the thorax of both fides, Efig..1..and Ty fg. 2.) From each jierntim a, mediaflinum was extended to a ligamentous flefhy fubftance, which was continued tranfverfely from one {pine to the other. In each mediafiinum was a pe- ricardium with its heart and veffels as in natural fetufes, and on each fide of each mediafiinum was a thorax with lungs. Thofe in the thorax of the more compleat child, the one, to wit, with the face, being of a pale colour and fwimming when put into ; water, while the other lungs were of a ' redder colour and fank in water. Tue {pines gradually approached each other as they extended towards the neck, at the lower part of which the fides of the _ bodies of the vertebre feemed to be con- ¥ tiguous ; but I pufhed a probe up be- tween them as far as the fecond vertebra, WITHIN 296 ESSAYS anp OBSERVATIONS WiTHIN the head I faw a cerebellum on each fide divided from a common cerebrum by a membranous plexus produced from the dura mater. The parts of the encepha- Jon were too foft arid tender for my dif- fection, and I examined the anatomy no further, but have the monfter in fpirits with the three great cavities filled with lint and bran where the bowels were ta- ken out. ART. PHYSICAL anv LITERARY. 297 ArT. XVII. The Diffection of the fame Monfter continued ; by ALEXANDER Monro junior, M. D. and Profeffor of Anatomy in the Univer- | fity of Edinburgh *. Y father having ‘fhewed the Mr Mowat’s defcription of the mon- ftrous fetus, and a model of its form in wax, I was curious to.know how the parts of the head and neck were, formed. The | preferved fetus was obtained with difficul- ty, and under a promife that no difleion fhould be made which might {fpoil its form. The fubject was. unfavourable, and the promife rendered the difleCiion difficult, and impoflible to be performed fo accurately as I wifhed. AFTER drawing afunder the two pari- etal bones of each fide I N N (fee Mr Mowat’s fig.) to take out the lint, &c. wath which the fcull was filled, and, ha- | _ ving cleaned away the matter, membranes, mH: Pep &e: See May 1. 17555'" 298 ESSAYS anp OBSERVATIONS &c, adhering to the bones, I faw the cra- nium of a natural form on that fide where the face is, fo far back as the /ella turcica, behind which the ends of the cuneiform proceffes of the two occipital bones united together. From each of thefe cuneiform proceffes, the occipital bones extended of a natural enough form to each fides their fituation may be judged by confidering the figures at L, M, or O, O, having each a foramen magnum for the fpinal marrow. At the fide of each of the occipital bones, - neareft to the conjoined preternatural ears, an os petrofum was placed, but without having any fquamous part of the tem- poral bongs, fuch as were on the other fide of each occipital. Between thefe offa petrofa there was a triangular little bone which fuftained thefe preternatural ears, and was inftead of orethmoides, fphenoides, and two fquamous bones. The fecus with the face had therefore all the common nerves, but the fetus with only the conjoined ears wanted the 1.2. 3. 4. 5. and 6 pairs. THE meatusQ,Q, fig 2. led into the crgan of hearing. ‘The orifice R was the entry PHYSICAL and LITERARY. 299 entry to a paflage which opened into the wfophagus of the fetus D D. THE mouth of the more compleat fetus ~ had all the ordinary parts, with the zvula, nares, larynx, and pharynx. Behind this pharynx and the e/opbagus defcending from it, there was another /aryzx and tra- chea, From the back part of the glottis of this laft mentioned /arynx, a little excre- {cence refembling a tongue ftood out, and ' behind a canal defcended of the form of one of the zares which joined with the . one continued from RK to form another wfophagus. I could. not profecute the veiflels and nerves placed on the neck and head with- out breach of promife, and therefore can give no account of them, ART. sine a5 < Si —— 300 ESSAYS ann OBSERVATIONS ArT. XVIII. Bones found in the Ovarium of a Woman ; by Dr GEorGE Youna, and communicated to. the Society by Dr Joun. BoswEL L, Fellow of the Royal College of Phyficians in Edinburgh *. Woman near fifty years of age, who £ % had never, had a child, being four months obftructed, thought fhe had con- ceived; but the men/es then returning, fhe r had exceflive flooding, which was fome- times in great quantity, at other times was lefs, but fcarce ever intermitted for a year and a half. It was then ftopped by fome medicine ; after which, her belly fwelled to fuch a degree in fix weeks, that her urine was almoft totally fuppreffed ; fhe was very coftive unlefs when clyfters were given, and fhe died in a few days more. On cutting the teguments of a abdo- men, a large quantity of bloody water rufhed * November 1, 1737. ath be I PHYSICAL any LITERARY. 301 rufhed out; and, when the, containing parts were fully opened, all the cavity was bloody, and the veflels were large and turgid with, dark-coloured, blood... . No bowel was now. feen ;.all that appeared in view» being a great numbet.of.,irregular flefhy lumps, which were bladders full, of a red watery liquor. Some of them. were of the fize of the largeft apples I have feen, others were as fmall as pigeon-eggs ; and there were of all the intermediate fizes between thefe. Upon a ftricter exa- mination, thefe veficles were found to be all contained in one common cyft, of which I had cut the fore-part with the teguments of the abdomen. The large cyft filled all the belly : When it was ral- fed, the bowels appeared in a natural ftate; except that, 1. The left Fallopian tube was very large. 2. No ovarium of that fide could be feen, unlefs the great cyft was that ovarium immenfely diftend- ed. 3. The right ovarium was as big as the head of a new-born child. It contain- | ed a vifcid white-coloured fubftance re- fembling mathed brains, which run toge- the 302 ESSAYS anp OBSERVATIONS | . ther like fuet when put into water. In this ftuff 1 found the bones herewith fent, Tue bone reprefented in plate V1. fig. | g. is a piece of a jaw with three firm den- tes molares, A,in it. Fig. 4. and §. are two views of a part of a jaw, in which are three dentes molares, B, irregularly fet, and an incifor C, ART, PHYSICAL anv LITERARY. 303 ART. XIX, Proofi of the Contiguity of the Lungs and Pler= ra; by ALEXANDER Monro fenior, M. D. and P. A*. age experiment of opening the thorax without hurting the lungs of living animals, while the trunks of their bodies are immerfed in water, through which no bubbles of air rife after the perforation, as propofed by the ingenious Lieberkuhn, and executed by the illuftrious Haller f, is a decifive one, if rightly performed, for proving no’ air between the pleura and ' Jungs. But, as an unwary operator may wound the lungs in perforating the thorax, when air would certainly rife in the wa- ter, from which the exiftence of air in the thorax might be concluded, and feveral other circumftances may, and: have cau-_ fed the conclufion’ from this experiment _ to be difputed; it may not be amifs to 4 Mention fome eafier ways of proving the ; non-= ® February.7. 1754. F Opufe. de refpirat. 304. ESSAYS 4nD OBSERVATIONS non-exiftence of air in this place. Such are the following. 1. DissEcT the teguments and inter- coftal mufcles from the p/ezra of either a dead man or quadruped without wound- img this membrane, in which there is no difficulty ; then pull up and deprefs alter- nately the /fernum and ribs as often as you will, the lungs are feen contiguous all the while to the pleura; but, on making a fmall puncture ‘through this membrane, the lungs, if they are not grown to the pleura, which is often the cafe in the, hu- man fubject, fly from the pleura, and are no more feen. 2, THIs connection ‘of the Lin and pleura, more or lefs of which is {een in moft human bodies, implies ftrongly a natural contiguity of thefetwo parts. Lay bare the pleura, without wounding it, between two ribs of any living qua- druped, which requires no great) dexter1- ty; and then the contiguity of the lungs — and. pleura may be feen, though the lungs ~ are conftantly fliding and changing place along PHYSICAL anv LITERARY. 305 along the pleura, and though this mem~ brane is in different ftates: While the crea- ‘ture infpires, it is concave; during ex{pi- ration it is convex and prominent out- wards, for this plain reafon, that, while in- fpiration is performing, the air does not pafs fo quickly at the narrow glottis as to fill the lungs at once with air of denfity and weight equal to the atmofphere; and,. during exfpiration, the air cannot efcape fo faft at the glottis as to prevent its more than ordinary condenfation and expanifili- ty in the lungs than the external air has. Ir we were to find accurately what weight the pleura could raife when it is made convex during ex{piration in the pre- ceeding experiment, would not this de- ‘termine how much more preffure, than that of the atmofphere, the part of the lungs within this elevated p/eura, on which this weight is fuftained, is expofed to? WOULD not the preflure on the fame part of the lungs, during infpiration, be early as much lefs than the weight of on as is the weight raifed in exfpiration ; fince it is the fame glottis Vor. IL Qq which 306 ESSAYS anp OBSERVATIONS which allows the air to pafs in both cafes ? Is not the force, by which the infpira- tory organs, aCing with the greate(t ener- gy of the mind, exceed the power of the exfpiratory organs uninfluenced by the ‘mind, confiderably lefs than the weight of the atmofphere ; fince, if, after exf{pira- tion, we prevent the entry of the air by the glortis, we cannot dilate the thorax as in infpiration, though there is ftill a good deal of rarefying air in the lungs? Do not the infpiratory organs, during — : infpiration, overcome the refiftance of the ex{piratory organs, and likewife that fhare of the preffure of the atmofphere which the air, rufhing into thelungs, does not ba- lance? ARF not the ribs arched, and the {paces & ¢ } % “ > between them narr ow, to prevent ill effects — from that unbalanced part of the atmo- (phere during infpiration? ART. = ea ‘PHYSICAL anv LITERARY. 307 ArT. XX. An Account of fome Experiments made with Opium « on living and dying Animals ; by RoBERT WuyTT, M. D. F. R. S. Fellow “of the Royal College of Phyficians, and Profé effor of. Medicine in the Univer fity of Edinburgh *. HE ancient phyficians imagined that opium extinguifhed the fame |) of life in animals by its exceflive cold; ie 4 and, in later times, there have not been wanting thofe who deducéd its effects x from a quite oppofite quality, whereby it was thought to rarefy the blood and to | comprefs the brain or origin of the nerves. Thefe falfe notions, however, of the na- ture and action of opium, have been re- — futed by feveral of the moderns, whofe | writings have thrown confiderable light | upon this fubject. _ + THE following experiments were made | with a view ftill further to illuftrate the E oduces its effects, and particularly to. a 4 / : fhew lee 2 * Avgul 7.1755. ov manner in which this wonderful drug 3go8 ESSAYS anp OBSERVATIONS fhew its influence upon the motion of the heart. 1. Havina injected a folution of opi- um in water into the ftomach and guts of a frog, I obferved that, in little more than half an hour, it feemed to have loft all power of motion, as well as feeling ; for there was no contraction produced in the mufcles of its limbs and trunk by irrita- ting them. I opened the thorax an hour after the injection, and found the heart, inftead of between 60 and 70, making on- ly 17 pulfations in a minute, The auri- cle, which was much diftended with blood, always contracted firft, and after it the ventricle. 2. A frog continued to move its limbs, and leap about for above an hour after I had cut out its heart, and was not quite dead after two hours and a half. Five minutes after taking out the heart of another frog, I injected a folution of o- pium into its ftomach and guts. In lefs than half an hour, it feemed to be quite dead ; for neither pricking nor tearing its mutfcles ct ee ie PHYSICAL AND LITERARY. 309 mufcles produced any contraction in them, or any motion in the members to which they belonged. After cutting off its head, a probe pufhed into the fpinal marrow made its fore-legs contract feebly. 3. EIGHTEEN minutes paft four in the afternoon, I injected a ftronger turbid folution of opium in water than that ufed in the preceeding experiments *, into the ftomach and guts of a frog; and, as it {quirted out moft of the folution injeted by the anus, I threw in fome more in its place. At twenty four minutes patt five, I opened this frog, and obferved the-heart with its auricle greatly diftended with blood and beating very flowly, not above feven timesinaminute. When the heart was touched with the point of a pair of {ciflars, its motion was rendered quicker for two or three pulfations: After which it became as flow as before. 4. IMME- * Viz, half an ounce of opium diffolved in eight oun- ces of water; which was alfo made vfe of in all the fol-- lowing experiments. The heat of the folution was near- ly the fame in all the experiments, viz. about 60 degrees of Farenheit’s thermometer. - gro ESSAYS anp OBSERVATIONS 4. IMMEDIATELY after decollating a frog, I deftroyed its fpinal marrow, by pufhing a {mall probe down thro ‘its {pine, which occafioned ftrong convulfions of all - the mufcles, efpecially thofe of the infe- rior extremities. Ten minutes after this, I opened the thorax, and found the heart beating at the rate of 45 times in a mi- nute. Sixteen minutes after decollation, it moved 40 times ina minute. After half an hour it made’36, and after fifty minutes only 30 pulfations in the minute, which were now alfo become very {mall and feeble. N.B. Wen l nheaed the thorax of another frog immediately after decolla- tion, and deftroying its fpinal marrow, I obferved its heart beating at the rate of 60 in a minute, which is four or five pul- {ations lef than I have generally feen the hearts of frogs make in that time, when their thorax was opened without decolla- tion. 5. AT PHYSICAL anp LITERARY. 311 5. AT nine minutes paft eleven in the forenoon, immediately after decollating another frog, I deftroyed its {pinal mar- row with a red hot wire, which produced terrible convulfions in all the mufcles, as in the laft experiment. I opened the ¢ho- rax of this frog thirty five minutes after decollation, and obferved its ‘heart beat- ing 30 times in aminute. The contrac- tion of the auricle régularly ‘preceeded that of the heart: The ‘auricle was not near fo much diftended with blood, nor the heart fo much fwelled, ‘as-‘in thofe frogs which had a folution of opium in- jected into their f{tomach and guts *. At. one o'clock (wiz. an hour and fifty one minutes after decollation) the heart of this frog made 20 pulfations in a minute. At half an hour paft two, when the room was become warmer by the fhining of the fun, it beat 25 times in a minute; and, when placed in the fun-beains, it pefform- éd 31 contractions ‘in that time, After this, I removed the frog to an eaft window, " ‘where * See No, 3. above, and Effay on the Vital and other involuntary Motions of Animals, p 371. and 372. 312 ESSAYS any OBSERVATIONS ‘where it o expofed to a cool breeze; upon which the motion of its heart became flower, fo that in a fhort time it only made 25 pulfes ina minute, I then expofed it anew to the fun-beams, by which its motion was foon quickened, fo that it beat 30 times in a minute. AT twenty-five minutes paft five in the evening, (viz. fix hours and fixteen mi- nutes after decollation and the deftruction — of its {pinal marrow) the auricle of this. frog’s heart, which was ftill filled with blood, contra¢ted twelve times in a mi- nute; but the heart itfelf lay without motion, was {welled and very red : How- ever, when pricked with a pin, it perform- ed two or three pulfations, and then re- mained at reft, till roufed by a new fi- mulus. At thirty five minutes paft five, the heart feemed to be quite dead, but the, auricle continued its motion; may, at half an hour paft eight, near three hours after the heart had been without motion, the auricle, which was very near as much filled with blood as when I firft opened this frog, beat 11 or 12 times in the mi- nute 5 - PHYSICAL anv LITERARY. 313 mute; its pulfations, however, were not. now fo regular as to time, as they had been before. - Ts it not probable, that the auricle of this frog’s heart beat longer than ufual, becaufe it continued, to the laft, to be fil- Jed with blood; whereas, generally, the y auricles of frogs hearts, which are opened after decollation and the deftruction of their fpinal marrow, expell, after fome time, the blood which they contain, and acquire the appearance of a {mall pellucid blad- peer filled with air? -. I laid- bare the abdominal mufcles z baa thorax of a frog, by difleCting off the fkin, and, at twenty minutes before nine in the morning, Iimmerfed the whole bo- dy of the frog in a turbid folution of op’ ‘ym in water, ina {mall bafon, which I covered, to prevent the frog from leaping out of it. Thirty five minutes after im- ~ merfion, I took it out of the folution and _ opened the thorax and pericardium. ‘The . -heart’s auricle, which was much diftend- ed with bloud, beat 15 times in a minute, ke but the heart itfelf, only 6 times. Forty Vor. Il. Rr minutes 314. ESSAYS anp OBSERVATIONS minutes paft nine (viz. twenty five mix nutes after the frog was taken out of the folution of opium) the heart feemed to have recovered more life; for it perform- ed erght pulfations in a minute: The con= tractions of the auricle now became fee- bler, and were {care more numerous than thofe of the heart, but always preceeded them fome little time. Six minutes be- fore ten, this heart moved only fix times: in the minute. Twenty four minutes paft ten it made only five pulfations in fixty é five feconds, the firft, third, and fifth of which pulfations were after an interval of fifteen feconds, and the fecond and fourth after a paufe of ten feconds. Seventeen minutes before twelve, and two hours and twenty eight minutes after the frog was taken out of the folution of opium, its heart moved only thrice in feventy five feconds, and performed its /yffole very flowly. Before two o'clock afternoon the heart was quite dead; but how long, I 4 cannot fay, not having had leifure to ob- — ferve it from a quarter before twelve to ‘ near two. 7, AFTER & Z PHYSICAL ano LITERARY. 315 7, AFTER cutting off a frog’s head and k deftroying its {pinal marrow with a red hot wire, I laid bare the abdominal muf- cles and thorax, as in the laft experiment, and immerfed the whole body of the frog in a turbid folution of opium, at half an hour paft nine in the morning. ‘Thirty fix minutes after immerfion I took it out of the folution, and opened its thorax and pericardium, ‘The heart and its auricle beat, each, twenty fix times in a minute, _ andthe pulfations of the auricle preceeded ; thofe of the heart regularly. The heart did not appear to be more {welled or red- 4 der than in a natural ftate, and the auri- cle was not near fo full of blood as in Exp. 6. Twelve minutes paft ten, viz. fix minutes after this frog was taken out of the folution of opium, its heart beat 27 times ina minute. At eleven o clock it performed 18 vibrations in that time ; and 16 at a quarter before twelve. At two o'clock afternoon, the auricle, which t __ having expelled all its blood, was now on- , | ly filled with air, continued its motions; but the heart lay at reft. Ten minutes : pat 316 ESSAYS anp OBSERVATIONS pat four, z. e. five hours and forty four minutes after the frog was taken out of the folution, the auricle of its heart beat 9 times in fixty four feconds. 8. I laid bare the abdominal mufcles and thorax of another frog, and, at four- teen minutes paft eight in the morning, immerfed it as above in a turbid folution _of opium. Fourteen minutes paft nine, I tock it out of the folution, and laid open its thorax and’ pericardium ; after which the heart began to beat at the rate of nine times inaminute: But the auricle, which was greatly diftended with blood, made no motion, except in fo far as it was agi- tated a little by the pulfation of the heart: Nor were the mufcles of the legs or thighs brought into contraction by cutting or tearing their fibres. At half an hour paft nine the heart beat only 7 times in a mi- nute; and the auricle, which was now pretty empty of blood, and, in place of it, filled with air, had a pulfation as well as the heart. Thirteen minutes before ten, 7..¢. thirty three minutes after the irog was ‘taken out of the folution, the au- ; ricle ‘ PHYSICAL anv LITERARY. 317 ricle fhewed, at confiderable intervals, a very faint pulfation; but the heart lay without any motion. g- THe fame day, after cutting off the head and deftroying the {pinal marrow of another frog, | laid bare its abdominal mufcles and ¢horax ; and, at eighteen. mi- nutes paft ten, immerfed it ina folution of opium, asabove. Eighteen minutes paft eleven, I took it out of the folution and opened its thorax and pericardium, after which the heart began to move at the rate of 8 times ina minute. Twenty five mi- nutes pat eleven, the heart beat. 15 times in a minute; and at twelve o'clock it per- formed between 13 and 14 vibrations in the fame time. At two o'clock, (viz. two hours and forty two minutes after the frog was.taken out of the folution) the auricle, which was now filled with air, continued to vibrate weakly, about r4 times in the minute; but the heart irfelf was without motion, Ar ten minutes be- fore four in the afternoon, the auricle full continued to move, bur more feebly than the auricle of N° 5. 1o, I 318 ESSAYS anp OBSERVATIONS 10. I laid open the whole abdomen of a larger frog than any of the former; and, at twenty two minutes paft ten in the morning, immerfed it in a {olution of o- pium, as above. ‘1 hirty five minutes af- ter immerfion, .I took it out ot the folu- tion, and opened its thorax and pericardi- um. ‘The heart was vaftly red and much {welled, and its auricle greatly diftended with blood ; but both were without any motion: After two minutes, however, the heart began to vibrate at great leifure, {carcely performing nine pulfations in a minute; but the overitretched auricle made not the {fmalleft motion. During every /yfiole, the heart was remarkably paler, and, in the time of its relaxation, be- came much redder; which phenomenon I obferved likeways in all the frogs hearts in the above experiments, but more remark- ably in thofe frogs who had-been expofed to the action of opium. Another thing which i remarked in all thefe experiments, was, that the heart, during its /y/tole, be- care manifeftly fhorter, and was length- ened in the time of its relaxation. But te PHYSICAL ano LIT ERARY. 319 ‘to return ; at fix minutes paft twelve, (7. ¢. an hour and nine minutes after the frog was taken out of the folution) its heart made only 6 pulfations in the minute ; and, at eleven minutes paft twelve, obfer- ving it without motion, I pricked it with -a pin, and breathed upon it. in order to fenew its pulfation, but to no purpofe. ii. TwinTy eight minutes paft feyen in the evening, I laid open the whole aé- domen and thorax of a frog, and immedi- ately after immerfed it ina folution of opi- um as above. Thirty eight minutes patft feven, when I pricked its legs with the point of a penknife, it made very little motion. ‘Two minutes after this, I turn- ed it to its back, and obferved its heart moving only between ten and eleven times in a minute, Having laid the frog again on its belly, that it might be more expo- fed to the action of the opium ;. at forty eight minutes paft feven, i. ¢. twenty mi- nutes from the firft immerficn, I turned it again to its back, and obferving the heart without motion, I opened the peri- bardium; which producing no effeé, 1 cut 320 ESSAYS AnD OBSER VATIONS cut the heart out of the body, and laid it on a plate, when ‘it gave two or three pul- fes. and never after moved, tho’ it was pricked once and again with a pin. No motion was produced in any of the other mufcles of this frog, by irritating them. 12. I cut offa frog’s head and deftroyed the fpinal marrow with a hot wire, then laid open its ¢horax and abdomen, and im- merfed it in a folution of opium at nine- teen minutes paft eleven. Eight minutes before twelve, i. c. thirty-three minutes’ after immerfion, I obferved its heart beat- ing very flowly: But two minutes before’ twelve, when I took it out of the folution -of opium, it had no motion. After this I opened the fericardium, and irritated the heart two or three times with the point of a fcalpel, which always produced a few pulfations. I then put the frog in the fo- jution for five minutes more, and, upon taking it out, found its heart quite dead. 12. AFTER cutting off a frog’s head and deftroying its {pinal marrow, I laid open: :. its whole abdomen, and immerfed it in a folution — . PHYSICAL anv LITERARY. 32: folution of opium, twenty-three minutes before one. After it had lain fixteen mi- utes, I cut up its ‘borax and pericardium ; and, obferving the heart beating very regu- larly and pretty ftrongly, 21 times in the minute, I immerfed it again in the fo- lation, which had now immediate ac- cefs to the heart. After five minutes, I took it.out of the folution; and, finding the héart without motion, | pricked it with the point of a knife; upon which it began to beat at the rate of 14 times in the mi- ‘riute, and continued its motions very lan suidly,and not without fome interruption, for about a quarter of an hour. 14. [cut out the heart of a frog, and put 4t in fountain-water at ten minutes paft ten 5 immediately after immerfion, it beat about 28 times in the minute, Eighteen minutes paft ten, it rindi 6 pulfations in thirty feconds. Twenty minutes after ten, E took it out of the water and laid it on a table, and obferved, that, as often as it was gently touched with any thing it made ‘ene fall and ftrong penton, and no. Vor}. Sf more: 322 ESSAYS anp OBSERVATIONS “more: However, in four or five minutes, it began to beat of its own accord, and, at twenty-eight minutes after ten, per- formed 19 pulfations in a minute. Thir- ty-five minutes paft ten, it beat r2 times in a minute. 15. TWENTY-three minutes paft twelve, I cut out the heart of another frog, and put it in fountain-water. After twelve minutes immerfion, I took it out of the water, when it beat above 20 times in a minute. Having put it in the water’ for five minutes more, it ceafed from motion, and, when taken out, did not move except when pricked, and then only performed one pulfation. 16, EIGHT minutes paft eleven, I cut out the heart of a third frog, and put it into fountain-water. Eleven minutes af- terimmerfion, its heart beat 8 times in the minute, and, four minutes after this, it vi- brated 11 times in ‘thirty feconds ; but the motion was confined to about one third part of the heart next its apex. Twenty minutes after immerfion, it con- tinned to move much in the fame way ; but PHYSICAL ano LITERARY. 323 but, in two minutes more, obferving no motion in it, I took it out of the water, and laid it ona table, where it remained at reft, unlefs when touched. Soon after this, however, it began to move; and, at twenty-five minutes after immerfion, it made 9g pulfes in fixty-three feconds, Four minutes after this, it moved oaly thrice isi - fifty feconds, and then ceafed altogether ; pe eae unlefs that, when pricked with the point of a knife, it gave one very faint pulfa- tion. At forty feven minutes paft eleven, ‘it was quite dead, a 17. I cut out the heart of a fourth frog, and, at thirty minutes paft ten, immerfed it in a turbid folution of opium in water of the fame degree of heat with the fogntain~ water ufed in the three laft experiments * After this heart had been immerfed ten minutes, I took it out of the folution, and laid it on a table, but it made not the {malleft motion ; and when pricked with - i, the point of a knife, though it quickly re- covered its fhape, yet it was not excited into * Viz, Nearly fisty degrees of Farenheit’s thermometer. g24 ESSAYS anp OBSERVATIONS into a proper contraction, as the heart of N° 14. I continued to obferve this heart from time to time for more than half an hour, but it never made the leaft motion. r 18. I cut out the heart of a fifth frog, and put it into a folution of opium in wa- ter five minutes before eight. After fe- ven minutes immerfion, I took it out, and laid it on a plate, where it remained at reft. When pricked with a knife, it did not perform a full pulfation like N° 14. but feemed to feel a little, by a very faint kind of motion, which was excited in fome of its fibres. 19, AT thirteen minutes before twelve, I cut out the heart of a fixth frog, and immerfed it in a folution of opium. Six minutes after immerfion, it had no mo- tion; but, when pricked, made one pulfa- tion. After lying five minutes more in the folution, it was quite dead. 20. I cut out the heart of a feventh frog, and, at thirty-feven minutes paft nine in the morning, immerfed it in a folution of opium, as above, Forty-two minutes after nine, PHYSICAL anv LITERARY, 329 nine, when I took it out of the folution, st was without motion: But, wien touch- ed with the point of a knife or probe, it performed one contraction, but with lefs vigour and more flowly than the heart of N° 14. Forty-feven minutes pait nine, it began to beat of its own accord. Two minutes after this, it moved 6 times in the minute, but much more feebly than N°14, Six minutes before ten, it beat only 4 times in a minute: After this, it began to beat much fafter ; but its motions foon return- ed to their former flownefs. At ten, af- ter having Jain near a minute without mo- tion, it began again, of its own accord, to beat at the rate of 17 times in the mi+ nute, and continued for eight or ten mi- nutes after this to beat very feebly, and in an irregular manner as to time. 21. Mr Robert Ramfay ftudent of me- dicine in this place, having diflolved two fcruples of opium in an ounce of water and a dram of liquid laudanum, injected _ it blood warm into the inteftinum rectum of a very {mall dog near fix months old, In lefs than a minute after the injection was 326 ESSAYS anp OBSERVATIONS was made, the dog could not ftand on his hinder legs; and, in 3 or 4 minutes, he had loft the ufe of them fo much, that, when they were ftrongly pinched, he nei- © ther moved them, nor feemed in the leaft degree fenfible of pain. He could, how- ever, fill fcramble about with his fore- legs; and when they or his ears were pinched, he howled remarkably, and feem- ed to feel confiderable pain. Ten minutes after the injection, he lay as if he had been quite ftupid; only, when a noife was made by beating on the ground, he opened his - eyes a little and howled, but prefently af- ter fell into a profound fleep. Ina few minutes after this, he began to be convul- fed; upon which Mr Ramfay injected a ftrong folution of fea-falt in water into his guts, which purged him feverely, and occafioned a prolapfus ant; foon after this, he awaked from his fleep, and gradually recovered the ufe of his hinder legs; fo that in lefs than an hour he could run a- bout the room, though he often fell down, his legs bending under him. After three. or four hours, he feemed to be quite well iN PHYSICAL anv LITERARY. 327 im every refpect; but, although the expe- ~ riment was made at mid-day, he could tafte no meat till late atnight. Whenhe was in the moft ftupid ftate, he could make ule of his fore-legs, and complained when his ears were pinched. 22, THE fame young Gentleman, at my defire, made the following experiment. _ Onthe oth of April 1755, after making an __ opening into the cavity of the abdomen of the dog on whom the laft experiment was made, he injected by the wound a dram of _ opium diffolved in two ounces and a half of water; but, before he could ftitch up _ the wound, about an ounce of the folu- ~ tion efcaped.. The dog loft the power of _ his hinder limbs almoft inftantaneoully. - Two minutes after the injection ‘was smade, he began to be convulfed ; and, in two minutes more, after having raifed | himfelf upon his fore-legs, he fell down % fenfelefs, At this time Mr Ramfay laid bare the thorax, by diffeCting’ off the tegu- ments, which did not feem to give the dog any pain; and could plainly feel the motion of his heart through the pleura: It beat 76 ae tines 328 ESSAYS anp OBSERVATIONS times in a minute, but became gradually” flower *. Immediately after counting the pulfe, Mr Ramfay cut the ribs on each fide vf the fternum, which he laid back in the ufual way. The heart, which was thus brought in view, appeared quite tur- gid, and continued in motion about five minutes; during which time it performed only between 60 and 65 weak vibrations; for they were not compleat contractions. While the heart was thus moving, warm fativa was firft applied to it, then cold wa- ter, and laft of all oil of vitriol ; which fhrivelled the parts it touched, almoft in the fame manner as a hot iron would have done; but none of them accelerated the heart’s vibrations, which became gra- dually flower, till they ceafed altogether. THE fibres of fome of the intercoftal mufcles on the right fide of the flernum — continued to be agitated with a weak tre- — mulous motion near half an hour after — the inje@ion was made into the abdowmrn ; : bet * The dog’s heart in a natural ftate, and before the injeStion of the {olution of opium, beat 150 in the minutes, “PHYSICAL anv LITERARY, 329 _ but the intercoftal mufcles attached to the ribs on the fides of the thorax were not obferved to move, nor did the diaphragm make any motion when its fibres were _ pricked or cut. NotTHinG remarkable was feen in the abdomen; ‘only, altho’ it was opened ten minutes after making the injection, the in- _teftines had’no motion; whereas, in ano- _ther young dog, which had got no opium, Mr Ramfay obferved: the periftaltic mo- tion continue half an hour after See iti | open the thorax. THE dog loft little or no blood in ma- ding the wound into his abdomen, nor were any of his bowels hurt by it. *23. A fmall dog into whofe ftomach the late celebrated’: Dr Mead had: forced, at four diferent times, a folution of two drams of opium in water, lived above an hour and three quarters after getting the ‘firft dofe. Vid. Treatife on poifons, Eflay Vox. Ii, Meas f 24. IT 30 ESSAYS anv OBSERVATIONS 24. Ir may not be improper to add here an experiment related by Dr Alfton in his: learned diflertation on opium *, Into the crural vein of an old dog, forty two pounds weight, he caufed be injected, at three dif- ferent times, half an ounce of opium dif- folved in four ounces of water, filtrated, and of the fame warmth with the blood of the animal. The firft time, about fif- teen drams were thrown in, and very flow- ly. It had no obfervable effect. About an hour after, eight drams more were in- jected flowly, and immediately the dog was feized with ftrong convulfions: The pulfe was frequent and fmall, and, after fome time, he foamed at the mouth. But, there appearing no figns of immediate death, after waiting an hour more, the laft nine drams were thrown in quickly; upon which the pulfe became full and flow, and, in a minute or fo, the dog ex- pired. FROM * Edinburgh Med, Effays, vol. 5, p. 1. arte 12 : : PHYSICAL ann LITERARY, 331 From the preceeding experiments, we may, I think, fairly draw the sae conclufions. (a) Opium applied to the ibethaeal guts, cavity of the abdomen and thorax, _ and abdominal mufcles, foon leffens, and after fome time intirely deftroys all feel- 4ng and power of motion, not only in the -parts to which it is applied, but through » the whole body, N° 1.2.3. 8. 11. and (8) Orrum produces thefe effets much _ more quickly in animals which are foon killed by want of food and air, than in ‘thofe which can live long without them, - and the parts of whofe bodies preferve a power of motion and appearances of life _ for a confiderable time after they are fe- parated from each other. N° r. 3, ec, compared with N° 21.22. and 23. (c) Stncea {olution of opium injeed _ into the ftomach and guts deftroys the - fenfibility and moving power of frogs, fully as foon when they are deprived of heir heart, as when this organ remains “antouched; it follows, that opium applied t ; to 332 ESSAYS anp OBSERVATIONS to thefe parts, does not produce its effects by entering the blood, and being, iby its means, conveyed to the brain, as fome have imagined, but by its immediate ac- tion on the organs and parts which it touches. N° 3. compared with N° 2. See. alfo Edinburgh Medical Effays, edit. 3. vol. 5. part I. page 140. (d) Stnce, after decollation and the deftruction of the fpinal marrow, opium operates much more flowly in deftroying the heart’s motion in frogs, than it does when the animals are intire (N°.6, com- pared with N° 7.); it follows, that it muft produce its effects chiefly, if not wholly, by its action on the brain, {pinal marrow, and nervous fyftem. The heart of the frog N° 7. whofe brain and fpinal mar- row had been deftroyed, beat 27 times in a minute, after the animal had lain thirty fix minutes in a folution of opium 3 which was only three pulfations lefs than the heart of the frog N° 5. performed thirty five minutes after the deftrudction of its brain and fpinal marrow, although it was | not expofed to the action of opium. (¢) WHEN J PHYSICA Luana LITERARY. 333 -(¢) Wen opium injeted into the veins, and thus mixed with the blood, leffens or deftroys the fenfibility and mo- ving: power of animals much in the fame way as when it is applied to their {to- mach, guts, or cavity of the abdomen (N° 24.); is it mot probable, that it pro- duces thefe effets by its action on the ex: tremuities of the nerves which terminate upon the internal furface of the heart and whole vafcular fyftem; and perhaps, alfo, by affecting immediately the medulla ce- rebriitfelf? And when a folution of opium A applied to the bare;abdominal mufcles of a frog deprived: of its brain. and fpinal marrow, does, after a long time, confide- _sably impair the heart’s motion; Is it not reafonable to think, that this is owing to the finer parts of the opium being ab- forbed by the bibulous veins and carried to the heart, and thus brought into con- tact with the nerves of this organ? No7, _ compared with N° 9, (f) Since opium, without entering the blood or being carried to the feveral parts of the body, deftroys the power of feeling 334 ESSAYS anp OBSERVATIONS feeling in animals merely by ating on the nerves to which it is applied (c) (d), it follows, that the nerves are the inftru- ments of fenfation, or, at leaft, neceflary to it. Nor is it fufficient to deftroy this conclufion, that there have been inftances of animals endowed with feeling whofe brains were fo greatly difeafed, as to feem incapable of performing their functions. It is far from being fafe to build theories in phyfic upon a few monftruous appear- _ ances in nature. (g) Ir appears from N° 4. and 5. com- pared with N°3. 6.8. ro. and 11. thatde- collation and the deftruction of the fpinal marrow does not weaken or deftroy the heart’s motion in frogs, near fo foon as opium injected into their ftomach and guts, or applied to the mufcles and bow- els of the lower belly and thorax, (4) AtTHo’ a folution of opium ap- plied to the opened thorax and abdomen of a frog, after decollation and the de- ftruction of its {fpinal marrow, foon wea- kens or deftroys the motion of the heart; yet it does not produce thefe effects fo — {peedily + Par PHYSICAL anv LITERARY. 339 fpeedily as when the brain and fpinal marrow are intire, N° 11. .and12. In the former cafe, the opium can only af- fect the heart by its topical influence; in the latter, it not only acts this way, but al- fo exerts its powers upon the brain, fpinal marrow, and whole nervous fyitem ; and therefore muft produce more fudden ef- fects. : (i) Iv appears, beyond doubt, from the preceeding experiments, that the heart is not exempted from the power of opium, _as the learned Dr Haller has afirmed *,, _ but has its motion deftroyed by it, as well as the other mufcles, only not fo foon. See N° 4. and 5, compared with N° 3. 6, 8. and ro. and N° 14. tg. and 16. comi- pared with N° 17.18. 19. and 20. IT is true, that the fibres of the inter- coftals on the right fide of the ffernum of the dog N° 22. continued to be agitated with a tremulous motion confiderablyy longer than the heart, and when the in- tercoftal mufcles attached to the ribs were © quite dead. But did not this happen be- | eaule, * A&, Gotting, vol. 3. p.147. and 154. . amet 336 ESSAYS anp OBSERVATIONS caufe, after feparating the flernum from the ribs, and thus cutting off all céromu-: nication between it and the fpinal mar- row, the-mufcles attached to it, could be no more affected by the opium, which had been injected into the cavity of the abdomen; while the heart and other muf- cles, whofe communication, by means of the nerves, with the brain and fpinal mar- row, was intire, continued to be expofed to its action ? ; (k) As Dr Langrifh has obferved, that the diftilled water of laurel-leaves injected into the cavity of the abdomen, kills dogs fooner than when it is taken into the fto- mach *; fo N° 21. and 23. compared with N° 22. fhew that opium injected into the ftomach and great guts of dogs, does not produce either fuch fpeedy or powerful effets, as when thrown into the cavity of the abdomen, And N° 6. compared with N° ro. fhews, that a folution of o- pium applied to the abdominal mutfcles, does not kill frogs fo foon as when all the vifcera * Phyfical experiments on brutes, p. 64, PHYSICAL ann LITERARY. 337 wifcera of the lower belly are expofed to its action. (4) ALTHo’ it feems probable, from N® 22, compared with N° 24. that a folu- tion of opium injected into the veins of dogs does not kill them fo foon as when _ thrown into the cavity of the abdomen ; yet this cannot be certainly concluded, fince the dog of N° 24. was much older and above ten times heavier than the o- ther. (m) IT appears, that a folution of o- _ pium injected into the great guts of a dog, _ affects the inferior part of the {pinal mar- row much more remarkably than its fu- perior part, or the brain; fince the dogs of N° 21. and 22. not only loft the power of motion fooner in their hinder legs than in their fore ones, but alfo were infenfible of any pain in them, and yet howled _ ftrongly when their ears were pinched. (a) A folution of opium injected into the cavity of the abdomen or great guts - f dogs, does not deftroy the feeling and ower of motion of their hinder limbs, by fending any effluvia to their mufcles; Vou. II. Uu other~ 536 KSSAYS anp OBSERVATIONS — otherways it could not produce thefe ef- fects fo inftantaneoufly, (N° 21. and 22.). Befides, fince opium thrown into the fto- mach and guts of a frog after being de- prived of its heart, deftroys the fenfibili- ty and moving power of its mufcles equal- ly foon, as if the animal had been intire (N° 2.); it is plain, that thefe effects can- not be owing to the finer parts of the o- pium being received into the blood, and by its means carried to the feveral muf- cles and organs. | (0) Nor does a folution of opium in- jected into the great guts or cavity of the abdomen in dogs produce its effects by tranfinitting through the nerves any fub- tile effluvia to the fpinal marrow; other- ways its operation could not have been fo inftantaneous (N° 21. and 22.); nor could the fpinal marrow and its nerves have recovered their functions fo foon,; after the opium was evacuated by a pur- gative clyfter, N° 21. (p) Ir remains, therefore, that apiani, by affecting the extremities of the nerves of the parts to which it is applied, does, by PHYSICAL anv LITERARY. 339 by means of their connexion and fympa- thy with the brain and {pinal marrow, deftroy or prevent, through the whole nervous fy{tem, the operation of that power upon which depends fenfation and motion in the bodies of animals. (g) SINCE opium applied to the abdo- minal mufcles of a frog, deprived of its brain and fpinal marrow, does not de- ftroy the motion of the heart fo foon, as when it is applied to the abdominal muf- cles of a frog whofe brain and {pinal mar- row are intire, (N° 6. and 7.), it follows, that the brain and fpinal marrow, and - confequently the nerves derived from them, have a greater influence than any other part of the animal fyftem, upon the motion of the heart. (r) Or1um does not only deftroy the moving power of the mufcles of animals by intercepting the influence of the brain and fpinal marrow, but alfo by unfitting the mufcular fibres themfelves, or the ner- vous power lodged in them for perform- ing its office: Otherways a folution of o- pium, when applied tothe abdominal muf- ° cles 340 ESSAYS anp OBSERVATIONS cles or vi/cera of a frog, would not puta ftop to the heart’s motion fooner, or indeed fo foon, as decollation and the deftrudtion of its fpinal marrow, (No 4. and §. com- pared with No 8. and io.) Opium there- fore does not produce its effects, folely, ° by putting a ftop to the funtion of the brain and {pinal marrow, but its influence "reaches to the fibres of the mufcles them- felves, or to the extremities of the ner- vous filaments which terminate in them. WHEN I fay the influence of opium reaches to the nervous filaments which terminate in the mufcular fibres, it is not meant, that any effluvia or fubtile parts of the opium are tranfmitted to them (See mand o above), but that it deftroys their powers, by means of that fympathy which they have, through the brain or fpinal marrow, with the nerves to which the opium is immediately applied. (/) From the above experiments we may infer, that not only the power of vo- luntary motion in the mufcles, but alfo their irritability or power of motion, when {timulated, proceeds from the nerves, or is ' PHYSICAL anp LITERARY. 341 is at leaft immediately dependent on their influence ; fince opium, which produces its effects, foley, by affeCting the nervous fyftem (m, 1 & 0), deftroys thofe powers fo fuddenly. I know it ‘has been lately argued by a celebrated author, that the irritability of the mufcles muft be inde- pendent of the nerves, becaufe the muf- cles of animals preferve a power of mo- ving when irritated, for fome time after the communication between them and the brain, by means of the nerves, is cut off *. But, fince a folution of opium applied to the abdominal mufcles of frogs, mere- ly by its action on the nerves, puts a flop to the irritability or moving power of the heart, much fooner than the deftruction of the brain and fpinal marrow (g) ; Is it not reafonable to conclude, that the tremulous motions of irritated mufcles after their nerves are tied, proceed from the integrity of the nervous filaments be- low the ligature, and the nervous power | full * Aca Gotting. vol. 2.p. 134, &2. 342 ESSAYS ANp OBSERVATIONS fill remaiming in them or in the mufcular fibres them{felves ? THE tying or cutting of a nerve, only prevents the derivation of any new influ- ence from the brain to the parts to which it belongs; but does not immediately deftroy the power or influence remaining in the nerve itfelf. Opium applied in fufficient quantity to the fenfible parts of animals, not only quickly puts a ftop to the function of the brain and fpinal mar- row, and thus produces in the mufcles all the effects of a ligature on their nerves, . but alfo deftroys the power of every ner- vous filament in the body (r), and there- fore puts a ftop to the motion of the heart in frogs fooner than the deftruction of the brain and fpinal marrow. (t) THe almoft inftantaneous palfy brought on the hinder legs of a dog, by injeting a folution of opium into the ca- vity of its abdomen (N° 22.), and the ef- feéts of the fame folution injected into the {tomach and guts of a frog deprived of its heart (N° 2.), where no part of the o- pium could be conveyed to the mufcles, nor ‘ _ blood through the heart, on account of PHYSICAL anp LITERARY. 343 nor be conceived to alter the nature of their gluten; fhew, that the irritability ofthe mufcles has not its feat in this glue, as fome have lately imagined *. But, if the motions of irritated mu(cles be owing to a difagreeable fenfation ex- cited in them or their nerves, as we have elfewhere endeavoured to fhew f, it is eafy to fee, that opium mutt, by deftroying . the fenfibility of the mufcles, of confe- quence alfo deftroy their irritability. (u) IN animals which have got a large dofe of opium, the veins, efpecially thofe of the membranes of the brain, are ob- ferved to be much {welled ; whence it has been thought, that opium produces its ef- fects in the bodies of animals, partly, at leaft, by rarefying the blood and com- preffing the brain: But this diftenfion of the veins feem to be no more than a con- fequence of the very flow motion of the the * A&, Gotting, vol..2. p, 152s _ + Effay on the vital and other involuntary motions of animals, fect, ix, and Phyfiological Effays, p. 188. &c. 344 ESSAYS any OBSERVATIONS the infenfibility with which this organ is affected *, (v) StncE opium foon puts a ftop to the vital motions of animals, which yet continue in time of fleep with little or no diminution of their vigour; fince it often eafes pain without bringing on fleep, and ‘fince, by its topical action on the heart, it deftroys the motion of this organ after all communication between it and the origin of the nerves is cut off f; it fol- lows, that the effects of opium are not owing, as fome have thought, to its pro- ducing fleep: On the contrary, the fleep which it occafions, feems to be only a confequence of its impairing the fenfibi- lity of the whole nervous fyftem. THE other effects of opium may be al- fo deduced from the fame caufe, particu- larly its reftraining all evacuations that are *n frogs, into whofe ftomach and guts I had in- jected a folution of opium, | not only found the heart’s auricle, but alfo the great veins leading to it, much di- fended with blood. Vid, Eflay on vital motions, Xe. p. 371. and 372. '-} Vid. N° 42, 13. 17. 18, 19. & 20. above Sg et PHYSICAL ano LITERARY. 345 are owing to an unufual irritation of the - parts of the body, and, at the fame time, promoting thofe natural fecretions which have been diminifhed or {ftopt by {pafmo- dic ftrictures of the veflels, from fome uncommon flimulus affeCing them. _ ‘ (w) Last iy, does not opium kill ani- - oi ieee tes ft ese ee mals by rendering their feveral organs wholly infenfible of the /fimuli, which are deftined by nature to excite. them into aétion ; whence not only a ftop is put to the periftaltic motion of the guts, and _to the propulfion of the chyle*, but the Wik Lda BRS Regeings fluids * "In a {mall dog, which Dr Kauu Boerhaave opened, after having given him three grains of opium, he obfer- ved fearce any periftaltic motion in the guts: The fto- mach was much diflended ; the pylorus was fhut, and the bread and milk, which the dog lad taken with the opium about ten hours betore, was indigefted. ‘There was nothing like chyle in the duodenum, nor any lacteal . veffels to be feen inthe mefentery. The bladder of urine and great guts were much filled, nor had-the animal evacuated either urine or feces from the time he fwal- lowed the gpium. Impetum faciens Hippocrati dium, p- 402. and 403, The learned Dr Haller has alfo obier- ved, that opium puts a ftop to the periftaltic ‘motion of . the guts in frogs and other animals, Act. Gotting. vol. 2. Ps 154, \ 346 ESSAYS anp OBSERVATIONS fluids alfo begin to flagnate firft in the fmaller and afterwards in the larger vef= fels *; while the heart becoming gradu- ally lefs fenfible of the /#jmulus of the blood with which it is diftended, con- tratts more feebly and at greater inter= vals, till at laft it ceafes from motion al- together? ART. * This my worthy Colleague Dr Alfton obferved witht a microfcope in frogs into whofe ftomach he had convey- ed a few drops of a folution of opium in water. Vid, Me- dical Eflays, vol. 5. part 1. art xii. And indeed, the great diftenfion of the heart and its auricle in frogs killed with opium (N° 5. compared with No 3. 6, and 10. above) indicates a more than ordinary refiftance to the blood’s motion in the arteries, as well as a lefs degree of irritas bility in the heart, Further, is not the flow, full pulfe, and dry parched mouth in thofe who have got an over- dofe of opium, owing, partly, to the flower motion of the fluids in the fmall arteries and fecretory veflels of the glands? Though it muft be confefled, that the drynefs of the mouth may be in fome meafure owing to the per~ ‘fpiration being greatly increafed by the opium, _ PHYSICAL anv LITERARY, 347 ACR Fe (eh). The Hifory of a compleat’ Luxation of the Thigh, im a Letter to Dr JouN Ru- THERFORD, Préfident of the Royal College of Phyficians, and Profe; or of Medicine in the Univerfity of Edinburgh 5 by James Macxenzir, M. D. late Phyfician at Worcelter * SIR, Feb. 10. 1755+ 5 HE account which I gave you of a e compleat luxation of the thigh re- * duced at the Worce(ter Infirmary, I now + fend in writing, agreeably to your re- *“gueft. fend you alfo Doctor Wall’s | *‘Tetter vouching this diflocation ; and “Mr Jefterys's narrative of the fame cafe. “Tf you think any further proof necef- “fary, there are {till two Phyficians and two Surgeons more, alive and well, who _“ were prefent at the reduction, and will bear witnefs, if required, to the truth 66 of * March 6.1755. 348 ESSAYS anno OBSERVATIONS ** of this accident, as well as the two gen- “ tlemen above named, and myfelf, who Sean. Goer WILLIAM JONES, a tall, robutt, heal- thy butcher, fifty-fix years old, was Car- ried to the Worcefter Infirmary on the feventeenth of Auguit 174.7, lame, and in grievous pain. His account of himfelf was, That he happened unfortunately, fome hours before, to ride an unraly horfé, which ran away with him; and that, making an effort to check him, juft as he was galloping over a itone bridge, the animal reared himfelf upon his hins der feet ; and immediately fell backward on his rider. The man was ftunned with the fall; but the horfe quickly recovered himfelf, and went off full fpeed, dragging poor Jones after him by his leg which was engaged in the flirrup. The horfe was foon providentially ftopped, and the man fet at liberty, but unable to move Ais thigh, which he believed was broken. Tue furgeon in waiting, (for four phyficians and three furgeons gave their attendance PHYSICAL anv LITERARY. 349 attendance in rotation, namely, Doctors Attwood, Mackenzie, Cameron, and Wall; and Meff. Edwards, Ruffel, and Jetferys) . having thoroughly examined the {ituation and figure of the parts difabled and in, pain, came to one of the phyficians, and told him, that the poor man’s thigh was diflocated ; that the head of the bone was {truck quite out of the acetabulum, and lay fairly in the groin. The phyfician having, in his younger days, attended Boerhaave (who, furely, underftood phyfic and fur- gery as well as any man ever did), and knowing that, from the prodigious ftrength of the ligaments, and depth of the focket in that articulation, this learn- ed Profeffor was of opinion, that ‘the thigh-bone was. never diflocated by ex- ternal violence, but freqhently broken near the head: -Which was the true rea- fon why fuch accidents were feldom, or. never, cured: The phyfician, I fay, per- fuaded, that his preceptor was in the | right, obferved to the furgeon, that there muit be a miftake fomewhere, and that there was no inftance on record,'which | could gso ESSAYS anp OBSERVATIONS could be depended upon, of fuch a luxa- tion as he defcribed: ‘To which the fur- geon replied, “ Sir, if you will not be- *‘ lieve me, you will belicve your own * eyes and fingers prefently.” THE novelty of the cafe brought all the phyficians and {urgeons to the Infirmary. A fkeleton was fetched, and great care taken, by a ftrict inquiry into circum- {tances, to fatisfy all prefent, that the bone was not broken, but really and fair- ly diflocated. There is no reafoning a- gaintt faéts: The toes and knee were turn~ ed outwards, the difabled limb was long- er than the found, the hip-joint utterly inflexible, and the round large head of the bone lay obvious to the fight and touch in the groin, THE next inquiry was, how this diflo- cation ithouid be reduced. All were call- ed to coniultation; not one of the phy- ficians or furgeons had eyer feen the cafe before. Some of the principal books of modern furgery were looked into ;, but one and all defcribed the reduction, and recommended extenfion in fuch a general, languid, y > ‘ ‘PHYSICAL anp LITERARY. 351 languid, hearfay manner, that it was ‘plain they were as unpractifed in the cafe as the, gentlemen prefent: Nor was any better fuccefs to be expected from ° Galen’s * method of reducing a luxation of this joint by hanging the patient to a ftrong beam by the heels with his head near the ground. AFTER mature deliberation, it-was a- greed, that, in cafe the ufual extenfion did not fucceed, the vis percu!! onis (which is well known to increafe the force toa furprifing degree by accelerating the mo- tion) fhould next be tried. In order to both, therefore, we provided a large ftrong table, of a proper length and. height, which we faftened with {crews _to the floor, and covered with fuch blan- kets and bolfters as we wanted ; a piece of * Vid. Gal. in librum Hipp, de artic. commentarior, lib, 4 aph 42. And indéed the ancients feem to have been acquainted with luxations of the hip-joint only in children, or diflem- " pered bodies ; unlefs we fhall except Paulus Agineta, whofe various methods of extenfion, in this cafe, whe- _ ther real or fuppofed, fome of the moderns have copi- ed, and fome have altered, g¢2 ESSAYS anp OBSERVATIONS * of ftrong cloth alfo was laid upon the blankets, under the patient’s back, of length fufficient to turn up between his thighs, and pafs over his fhoulders down” to the floor, where both ends were fecure- ly fixed, with a view to refift or counter-= act the neceffary extenfion. We provided alfo two towels of a convenient length . and thicknefs ; one of which, at the mid- dle, was tied with a tight but eafy knor, above the patient’s ancle, and the two ends twifted together, were given to three’ - ftrong men to hold. The other towel was in the fame manner faftened above the knee, and the double end given to three more; while the furgeons ftood ready, one with his hand on the ball of the diflocated bone to direct it into the fockes, one at the knee, and another at the foot to turn them inwards. WHEN all things were ready, the ex= tenfion was begun, in the common me- thod, by the towel-men; but though they exerted their utmoft ftrength, the head of the bone was not moved in the leaft, and their effort ferved only to in- creafe ‘PHYSICAL anv LITERARY, 353 _ creafe the poor man’s torture to an into- lerable degree. Finp1NG thus the extenfion of no fig- _nificancy; and the patient’s courage re- viving after fome refpite; the vis percu/fio- nis was carried into execution after the following manner: The towel-men were directed to flacken their towels to a cer- tain point, to ftand with their feet firm, their arms ftreight, and their bodies bending a little forward; and, upon a _ Certain fignal agreed on, were ordered to pull with a vehement and quick jerk, throwing themfelves back with all their might. AFTER every thing was in good order, and the affiftants apprifed of the nature and neceflity of the operation which they were about to perform, the fignal agreed was at laft given. The towel-men pulled in a moment with a {trong and fudden pring; the furgeons performed their “parts dexteroufly ; and imftantly there was a loud crafh heard, which made one f ithe phyficians call out, Alas! the ta- Dle is broken, But at that very moment Vou Ii, X y the 354 ESSAYS anv OBSERVATIONS the patient, with a: thundering vos) cried, It’s in, it’s in, it’s ine And fo it really was; for we immediately found the limb reftored to its natural pofition, length, and flexibility. The patient was put to bed; and, by a proper diet and care, recovered his former health, and could walk perfectly well in three weeks, One of the phyficians often met him af- terwards on foot driving cattle, and al< ways afked, How he did? To which his conftant anfwer was, Very well, thank ‘ God and the gentlemen. And he can now, upon occafion, walk twenty miles in a day, without fatigue or pain, though the injured limb ftill remains near a quar- ter of an inch longer than the other. ART. a “a i PHYSICAL anp LITERARY. 355 ART. XXII. Some Obfervations on the new Method of . curing the Cataract, by extracting the Cryftalline Humour ; by THoMas Younc Surgeon in Edinburgh *, O reftore loft fight, is recovering one of the moft ufeful of all the fenfes, _ and the couching of the cataract, would _ be one of the moft valuable operations, could it always be done with fafety ; but ’ the bad fuccefs, and dreadful confequen- * ces which often attend it, have deterred many good furgeons from performing this operation, and thrown it’much into the hands of empyrics. I have couched but few in the old way, and thofe with fuch bad fuccefs, that I was fully determined to operate no more ' _ on the eyes; nor did the fuccefs of the new _ method performed by the ingenious M. Daviel, alter my refolution for a confide- rable > March 4, 1756, 3%6 ESSAYS ANp OBSERVATIONS rable time, till, at the importunity of fome of my beft” friends, I confented to try this new operation. ~ Six cataracts luckily caft up laft fummer in the Royal Infirmary at Fdinburgh, which I extra@- ed in the following manner, THE patient being feated in a chair, with an affiftant at his back, to fupport his head, and keep up his eye-lid, as in the old operation, the operator may ftand or fitin achair, as he finds moft conve- Dient. aA | He fhould keep down the under eye~ lid with two fingers of the one hand, while with the other he takes the final! knife A (Plate VIL Fig. 3.) with which he pierces the tran{parent cornea at the ex- ternal angle of the eye, near to where the cornea joins with the /fclerotica, taking great care not to wound the ris. Run. the knife in a horizontal direction acro{s the anterior chamber, and bring it out about the fame diftance from the white — of the eye, as where it entered; then cut — that part of the cornea which lies below the two orifices, as much in the form of a PHYSICAL anv LITERARY. 357 a crefcent as poffible, this makes the in- cifion larger, and keepé the cicatrice more off the fight; lift up the flap of the cut cornea with the {coop B (Fig. 4.) or any other ‘convenient inftrument ; introduce at the fame time a common couching’ needle C, (Fig. 5.) thro’ the pupil, to open. the cap/ula of the cryftalline Jens, that the latter may come the more eafily out. A fmall aperture generally ferves this purpofe ; if the Jens is of a firm contift- ence, it often fticks to the point of the needle, fo that when the inftrument is withdrawn the cryftalline comes along with it; if it does not, a very gentle pref: fure upon the eye forces it out. The ope- ration may be frequently performed with the knife alone, the cap/ula of the cryftal- une being fometimes fo thin, that, after the cornea is cut, a fmall preffure on the. eye makes the /ens come away. Tus method of operating is much the fame with that pradctifed by M. Daviel, which you'll find at large in the Memoirs of the Academy of Surgery, vol. ii. p. 337. Ihave followed the example of the fa- aR | ous 4 358 ESSAYS anv OBSERVATIONS mous Mr Sharp, and fhunned the great multiplicity of inftruments M. Daviel makes ufe of, which renders this opera- tion more fimple, lefs tedious, and _ lefs dangerous. . ; I fhall next mention the fuccefs of each operation in the order they were perform- ed. 1. RoBERT Laurie, aged about 30 years, was admitted into the Royal Infir- mary with a cataract in both eyes. I operated on the left eye the 23d of July 1755. As foon as I had paffed the knife into the anterior chamber, he turned his eyes fo much upwards, that the cornea was quite out of fight ; I waited till the eye returned to its former pofition, when I found the point of the inftrument in the iris, which I immediately difengaged, and finifhed the operation without any other accident. I expeéted a great inflammation from the zris being touched, but was agreea- bly difappointed, finding the man recover with .- PHYSICAL anp LITERARY. 359 with licrle pain, no fever, and the inflam- mation inconfiderable. Axovr three weeks after the operation, “he could diftingnith colours and large objects tolerably well; but could not bear much light. His eye continued weak and watery for about three weeks more, when he could eafily fee a pin in the fleeve of his own coat; his eye was clear, but the pupil not quite round, which was cer- tainly owing to the zrzs beirig hurt. 2. ——— was admitted into the Royal Infirmary about the middle of Sep- tember, with a cataract in the one eye, and the cornea of the other quite opaque. THE pupil of the cataracted eye was contracted to above the fize of a large pin- head, but quite immoveable. HE was vifited by feveral furgeons in _ town, who were of opinion, that the dif- eafe was incurable, and that the bottom of the eye was affected, as well as the eryftalline lens. “I propofed trying the new operation, before he fhould be difmified incurable; to which they very readily confented. ; ; I 360 ESSAYS anp OBSERVATIONS I performed it without any accident, and the man recovered in a few days, without any fever, pain, or inflammation, He was difmiffed the houfe about a fort- night after the operation, when his eye - was quite clear, but the pupil ftill im- moveable ; and he could only perceive a glimmering of light, which is more than _ was expected from the appearance of the pupil before the operation. 3- & 4. JOHN Crata, aged about 40 years, was admitted into the Royal Infir- mary with acataract in both eyes, which had much of the milky appearance, I operated on both eyes the 28th of Sep- tember 1755, and nothing extraordinary occurred during the operation ; only, up- on dividing the cap/ula of the cryftalline, a fort of milky liquor came out, and the Jens was of a dark brown colour. He had a very {peedy recovery ; fix days after the operation, I uncovered his eye; he was capable of diftinguifhing colours. I look- ed again into his eyes on the 13th day, when I found his fight ftill better, and his PHYSICAL and LITERARY. 361 his eyes more able to look at {mall objeds, * without complaining. | HE was difmiffed the houfe the 1oth of November, when he could read without the affiftance of glaffes. ! 5. ROBERT Laurie, whom have al- ready mentioned, had the operation per- formed on the right eyethe 12th of O@o- ber, when nothing extraordinary happen- ed; he had a very good recovery, with fcarce any pain or inflammation; he was difmiffed from the Houfe the 19th of No- vember, when he faw very diftintly with both eyes. , 6. AGNEs Barrowman, aged about 39 years, was admitted into the Royal Infirmary, with cataracts in both eyes. T operated on the left eye the 26th of October 1755. . THE fpace betwixt her eye-lids, when raifed up, was fo fmall, that I could with difficulty fee all the cornea, which, in this patient, was remarkably flat. As foon as I had pafied the knife into the anterior chamber, fhe was feized with Re a fit of coughing, which obliged me to Vout. II, BS G2 cut 362 ESSAYS anp OBSERVATIONS * ‘cut the cornea in a very great hurry. The opening in the cornea was but fmall, which gave me more difficulty in extracting the cryftalline than I had in any of the for- mer. NoTwITHSTANDING this unlucky accident, fhe had a tolerably good reco- very; her eye was pained, and fomewhat: inflamed, for fome time after the opera- tion, but never violently, She was dif- miffed the houfe about fix weeks after the operation, being them able to diftinguifh very finall objects. N. B. Some eyes are more proper for this operation than others ; the larger the eye, and the more convex the cornea, the operation will be the eafier. This woman had a remarkably bad eye in this refpect ; it was {mall, the cornea flat, and the di- ftance between the eye-lids, when open, was very little: Perhaps the,/pecu/um oculi would be of ufe to help all thefe faults while the cornea is cutting, but no longer, for fear of prefling ont the vitreous hu- mour, THERE PHYSICAL anv LITERARY. 363 THERE was nothing particular in the treatment of thefe patients after the ope- ration ; i¢ confifted chiefly in blooding, fpare diet, now and then a gentle laxa- tive, and cloths dipt in vinegar and wa- ter applied frequently to the eyes; they were not confined to their beds above a day or two, and none of them required fomentations. I do not pretend, from the above oafes, to make a comparifon betwixt the fuccefs _ ef couching, and the new method ; this _ fequires more cafes than I have had occa oc. to fee, _ - Accorpinc te thetrials made by fome of the French fargeons, which you'll find in the Memoirs of the Academy of Sur- | gery, vol. ii. p. 578. the couching was the moft fuccefsful. Mr Moranp couched fix patients. 3 of them faw diftinélly. } 3 of the cataracts rofe again. _ M.« ua Fave extraéted fix cataracts in ‘the new way. 2 of the patients faw diftindlly. 2 of 364 ESSAYS anp OBSERVATIONS 2 of them faw lefs diftincly. 2 of them were quite blind. | M. Pover extracted feven cataracts af- ter the new method, 2 of his patients faw diftinétly. 2 of them lefs diftinétly. 1 could diftinguith light. 2 of them were quite blind. WERE | to judge from my own expe= rience in both operations, the new method certainly claims the preference; fince I have only operated upon fix cataracts, and all of them have fucceeded, tho’ fome were ’ mot very promifing. | Tuts, I hope, will excite others to make further trials and- improvements in this operation. ART. - oe. ; CK, PHYSICAL anv LITERARY. 365 | ae ‘Art. XXII A Hernia from the Omentum falling down " Gnto the Scrotum ; by TH omas LIvINnG- ' STON, Mz. D. Phyfician at Aberdeen *, “fA Young man, aged about 28, of a very % thin habit of body, and naturally of a healthy conftitution, was feized with a pain and uneafinefs about the region of _ the ftomach; for which complaints (with- _ out any regular advice) he took a vomit, * which operated in the ufual manner, but f RS 2 Jen . without alleviating his former uneafinefs. In the evening of that day, about fix hours . after the operation of the vomit, he was - feized with fharp pains over all his belly, _ for which, by the advice of a phyfician, he was ordered an emollient clyfter, and an anodyne at bed-time. The cly{ter-o- __ perated gently, and he paffed the night - pretty free of pain, till towards morning : that the pain returned more violent than ever 3 ® February 5, 1755. ' + 366 ESSAYS anv OBSERVATIONS: ever; particularly in the left, fide of the umbilical region, and in the left tefticle. I was called to vifit him that forenoon, and, upon: examination, found a fcrotal hernia on the left fide, about the fize of a large fift, extremely hard over all its fur= face, and very painful on the flighteft touch. He had a hard frequent pulfe, intenfe thirft, and all the other fymptoms of inflammation. He was immediately blooded to a confiderable quantity, warm {tupes wrung out of an emollient decoc- tion were alternately applied upon his Scrotum and belly, and an emollient pur- gative clyfter was injected. The applica- tion of the warm ftupes gave him fome {mall relief, and he imagined the parts were fofter ; but, upon ufing the taxis, the pain was intolerable, and it was in vain ‘to endeavour to reduce the hernid. Hecon- tinued in this ftate till the evening, when his fever demanded a fecond blooding, which was accordingly performed; ano- ther ftimulating clyfter was thrown up, and foon after he had two or three copi- ous dejections of indurated feces. The operation: PHYSICAL anv LITERARY, 367 operation of the clyfter gave him fome eafe; but the ftate of the hernia was not in the leaft altered. He continued reftlefs and much pained all night, and in the _ morning he drank the decoc?. tamarindor, cum dupl. fenne, which gave him feveral loofe {tools throughout the day, the hernia - eontinuing as hard and painful as for- merly. He-would not agree to have the opera- tion of the dubonocele performed, and in the evening his pulfe became feeble; he had frequent returns of a fingulfus, and died next morning. It may be neceflary to - mention, that, foon after the vomit, he cried out, that fomething was tearing his ftomach and guts towards the bottom of his belly. _ During his illnefs I was much per- _ plexed about the nature of the hernia, As _ the clyfters and ptifan had operated very | naturally, [could not imagine that it was ~ any portion of the inteflines; and, as he _ was of a remarkably thin habit of body, _ Icould fearcely imagine that it was the otnentum ; however, as his friends gave ; me 368 ESSAYS anv OBSERVATIONS me the liberty of examining the body, my, coubts and fcruples were foon fatisfied. I firft locked the ftate of the abdomen,’ where the following appearances were very obvious. The omentum fallen.down, ereatly ftretched, and fo tenfe, that one fhould have imagined it would havebroke, ‘The ftomach much diftended with air, the great curvature of it much lower down than its natural fituation ; the great arch of the co/on quite out of its place, and _ lying as low as the midd’z of the {mall guts; the jejunum and z/eum confiderably inflamed and much diftended with air, and the mefenteric veflels much more tur- gid than ufual. Thefe were the principal things to be obferved in the abdomen. Upon making an incifion through the te- guments of the /crotum, (in the fame di- rection as is ordered in the operation for the bubonocele) I foon difcovered the her- nial fac, which was very thin, tenfe, and rigid; and, upon laying the fac open, there was nothing to be found but the omentum, which was compleatly mortified as high as the ring of the mufcle. Up- on ‘PHYSICAL any LITERARY. 369 on dilating the ring itfelf, I found a con- volution of the i/ewm fticking in the very mouth of the opening, but the one half of the tranfverfe diameter of the canal was only engaged, and that part of it which was {ftrangulated was in a mortifi- ed ftate. The remaining part of the gut betwixt that and the caput coli was much fmaller than ufual, confiderably inflamed, and contained a little putrid vifcid chyle. -Upon taking out the omentum, I found a refiftance towards the lower part of the Scrotum, which I imagined was owing to fome adhefion; but, upon ufing a very _ gentle force, it was eafily extracted, and - plainly came out of the tunica vaginalis teftis, in which there was a pretty large hole or perforation. The teflicle appear- ed to be quite found. That portion of the omentum which was contained in the fcrotum weighed fix ounces and a half, Vor, IL Aaa A al 370 ESSAYS anp OBSERVATIONS ART. XXIV. A Child brought forth at a Rent of the Belly*. N April 1736, Elfpet Grant, in the pa- i rifh of Moy, being’ with child, ‘took her labour-pains. After they had conti- nued three days with the child in ‘the birth, two cracks, as if the rafters of the houfe had broke, were heard about the — fick wife, and her belly was rent from near the navel, with a fquaint downwards. and to the left fide, to near the fhare- bone. At this rent the child came into the world, the after burthen was brought away, and the intrails were feen. THE rent was cured without any other application, than that of butter mixed white fugar, and its fcar was only as the fcratch of a big pin. THESE facts are attefted by eiccd oaths of Anna Kennedy a midwife, and ~ Mary Ogilvie a neighbour, who were pre- tig So fent * May i. 1755. pag $ PHYSICAL anv LITERARY. 371 | _ fent when the rent was made and the _ child came out of it; of Margaret Dallas, who affifted to bring away the after-bur- then; of Robert Smith who faw the rent and intrails immediately after this; and of Ifobel Tarrel, who afterwards examined the fcar: Taken and fubfcribed by James Macqueen younger of Corribrough, bai- lie to the Laird’ of Mackintofh, at Moy- hall, November 22. 17383 of which the original fubfcribed copies arekept by the fecretaries of the philofophical fociety of Edinburgh. A Child efeaping ai a Rent of the Womb in- to the Abdomen; by Au EXANDER Mon- RO, M.D. ou PF; 4; yp March 1744, I was defired by Mr Ramfay furgeon here, to witnefs the _ examination of the body of a woman who died in child-labour without being deli- vered. ‘The account given me of this wo- man was, that fhe was about 35 years _ ef age, and had born two dead children, and 372 ESSAYS anp OBSERVATIONS and_a living one. Being at her full rec= koning, her pains had begun on Tuefday morning, and continued in a natural way, the child advancing towards the birth, and feme of the waters coming away all that day and Wednefday, till Wed- nefday evening, when fitting in a chair in labour, fhe gave a fudden {pring from the chair, complaining of violent pain in her belly. The child never was felt after- wards by thofe who attempted to aflift her delivery. She conftantly complained of violent pain in her belly, with her fen- fes and judgment intire, till Friday morn- ing, when fhe died. On Saturday her body was opened. ArTer cleaning away with fpunges a confiderable quantity of blood floating in the abdomen, we faw a ripe child and its fecundines lying in the lower part of it, a little to the right fide. The child, placenta, and umbilical rope were intire, and the membranes were as ufual after birth. ‘Fhe woman's uterus had its fun- dus raifed as high as the navel, with its fubftance foft and fpongy as is common in PHYSICAL anv LITERARY. 373 in pregnants, nothing preternatural ap- pearing in its fore-fide ; but, when the fundus was turned down and forwards to- wards the ofa pubis, a large rent four inches long was feen towards the neck of the womb; which being again put into its natural fituation, was opened its whole length, in the middle of its forepart, when ‘we had a better view of the rent, extend- ing from very near the os uteri upwards, a little obliquely to the right fide. The os uteri was then very little open. The cervix, which is diftinguifhable plainly from the fundus in a-woman not with child, was here extended into the fame common fac withit. The inner furface of the womb was all fmooth, feeming to to be covered with a fine villous mem- brane. From the larger fize of the finufes at the back and upper part of the womb, ‘I judged the placenta to have been former- ly applied there. ART. 374. ESSAYS anv OBSERVATIONS ART. SKVe | A preternatural Collection of Waters in the Womb with Twins ; by STEPHEN FELL Surgeon in Ulverftone *. . i? November 1747, I was called to Han- nah Salthoufe, mother of feveral chil- dren, then, according to her reckoning, in the firft week of the eighth month of her pregnancy. She had obferved her belly increafing in bulk very faft during the preceeding month, and particularly in ‘the two laft weeks, in every day of which a fenfible difference was faid to have been obferved. At my firft vifit her abdomen _ appeared to me much more diftended than ever | had feen in a woman with child, efpecially from the navel to the upper part of the epigaftric region, where 1t was more tenfe than towards the offa pubis, and the moft ftretched part had little fenfe of feel- ing. Her pulfe was high and quick, her breathing was difficult, her face was ca- daverous’ * February 6. 1755+ i PHYSICAL ano LITERARY. 3» : f — daverous, and fhe had continued unparo- ral labour-pains, with much thirit and little urine. Theos ‘tince was a little o- pened, but’ without.any forming of water » that could-be-felt. .Lordered clyfters and an opiate at night, which made her pafs it quietly. Next day the pains were more natural, and fhe was tolerably eafy. In the even- ing, fhe took an opiate with two fcruples of pulv. ad partum, after which, there were intervals between her pains; but, at four in themorning, fhe became delirious, and appeared like one who had not an hour to live. On taking rich hot negas, thefe fymptoms went off; and then, ha- ving felt a child’s head floating in water, I broke the membranes, and brought away two male children, who were fearce half the fize of children born at the ufual time. One of them was dead, {welled and livid; the other lived 64 hours, but without ta- king food, or making any difcharge by {tool or urine. The quantity of water voided in this delivery was computed by all 376 ESSAYS anp OBSERVATIONS all prefent not lefs than fix wine gallons, 48 or 50 lib. My patient’s belly fubfiding to the na- tural dimenfions, was fwathed immediate-= ly after the after-burthen was brought away. She had ftrengthening cordials and anodynes given her, with a proper diet, and fometimes clyfters. Now, on the 12th day after her delivery, the ap- pears out of danger, PHYSICAL ann LITERARY. 377 ABT s XXXVI. Hiftories of tophaceous Concretions in the ali- mentary Canal; by ALEXANDER Monro jenior, M, D, FR. S, and Proféffor of Anatomy in the Univerfity of Edinburgh *, b ai HE number of hiftorians of tophace- ous concretions in the alimentary canal is not fo great, but that your col- lection might, in my opinion, admit of fome few, efpecially if there is a variety in them. fifi. 1. A healthy boy, about twelve years of age, began to complain of colic- pains, which increafing with frequent gripes, Lorborygmi, and vomiting, had fuch an effect, that his parents aflerted, he was -fcarce of fo large.a ftature after fix years of his difeafe as he was at the beginning ‘of it. Vomits, purges, vermifuges, atte- nuants, and a variety of other medicines, Be -veuy Il. Bbb had » * February 6.1755, 378 ESSAYS anp OBSERVATIONS had been given in that time without any benefit. His father, one of the town-officers or ferjeants, having then afked my worthy friend and colleague Dr Plummer’s advice, he defired my affiftance. We were told by the lad, who was greatly emaciated and very weak, that, fome years paft, he had not had the vomiting, but found a hard painful tumor above the left groin,. which fometimes fhifted place a little,, where he fancied often he felt fomething like the ftriking of two hard bodies.on each other. He had been of late much fatigued with cenefmus, Sometimes he had no excretion of feces for feveral days, and. often he could fearce make any water, and that only in drops. During two days before our vifit, the teze/mus was conftant, | and he felt fomething hard within the ‘redum near to the as, which he and fe- 9 veral others had endeavoured in vain to — bring away with their fingers. - Ow extracting this fubftance with a for- — ceps, fuch as is ufed for extracting ftones © from the bladder, he was much eafier than. — he PHYSICAL ann LITERARY. 379 ~ he had been of a confiderable time. Next day, he pafled two other balls, and, on each of the two following days, a ball» which he could not force out at the avus, was extracted with the forceps. After this, he had no uneafinefs, and foon became a heal ftrong young man. Tue largeft of thefe five balls, which was the firft extraGted, is five inches in circumference and fomething glo- ’. bular, but with feveral prominences and common bafe, flat furfaces. -Moft of the flat parts had a {mooth fhining tartarous thin coat, the ref{t of it was more rough and of a {pongy appearance, ‘The two laft brought away are lefs in bulk, and without fo much tar- tarous cruft. The two fmall ones are all covered over with the fhining tartarous” cruft, which in feveral places is prettily variegated with different fhades of an afhy colour. One of them has fome re- femblance in its fhape to the fhell ofia tortoife. The other or {malleft may be compared to two pyramids Joiped by a The 380 ESSAYS ann OBSERVATIONS Tue fecond in fize and the fmalleft are cut through near to the middle, where there is a fmall flat bone, that probably has been the nuclens about which thefe balls were formed, though they are not of the fame fhape. r WE were informed by the parents, that they had often chid their fon for fwallow- ing the {mall bones of fheep and lambs feet, the finewy parts of which, when boiled, the adie frequently ‘took for food. ‘Hift. 2. A man who had been long — tortured with a painful hard {welling in his belly a little above the right groin, which frequently caufed | vomiting and diarrolea, though at other times he was very coftive, afked my advice, when he was very weak and emaciated. The feat of this tumor, the kind of feel it had through the containing parts, and its tumbling, as the patient faid, from one : place to another, when he changed po- . ftures, made me fufpe@ a concretion to be lodged in the great fac of the colons. Te whee ae | n ee ———————— PHYSICAL ann LITERARY. 38: In hope to puth it forwards in the co- fon, I caufed his great guts to be filled with whey injected by the anus, and then — dire@ed himfelf and affiftants to prefs re- peatedly the tumor upwards. This ma- NeUvre being feveral times renewed with- out fuccefs, I preferibed a brifk purga- tive, and ordered the inje@tions with the preffure to be repeated as foon as the ca- thartic began to operate. But this and feveral other fuch operations failing, my atient died. Havinc obtained leave to examine - his body, my conjecture proved to be right ; ; for, in the caput coli, there was a ball of more than feven inches circumfe- - rence, with a depreflion at oppofite ends, The ‘inteftine had contracted fo much at the fide of the ball next to the cavity of the colon, that I could not force it through the aperture there, but was obliged to cut the fac in which i it was is ie to take i it : , out. THE ball had no tartarous cruit on its furface, and, when it was cut through, Bie ge 3 Y by sie OAS ; z . , PE its 382 ESSAYS anp OBSERVATIONS its nucleus was a chalky or limy fubftance about the fize of a common pea. Hift. 3. Dr John Stevenfon phyfician gave me a concretion fix inches in cir- cumference, the muclus of which is a plumb {tone, taken out of the inteftines of a boy of five years old. Though the ftone had been fwallowed long before the boy’s death, the kernel of it was freth when the ftone was taken from the mid- dle of the ball. A clyfter had brought away feveral other plumb-ftones from this ~ boy fome months after the plumbs had been eat. iif. 4. Dr Stevenfon alfo gave me a= nother fuch concretion, which has four flat fides with feveral depreflions in them, meafuring about five inches in circum- ference, formed alfo on a burnet plumb- itone, which he took out of the inteftines of a girl. Hifi. 5. ¥rom the fame gentleman I likeways had a third concretion pretty like to, but a little larger than the one defcribed and painted by Dr Simfon in Med, Eff. vol. 1. art. 32. which, with three PHYSICAL anp LITERARY. 383 three fuch others, he took out of the in= teftines of another patient. Each of them had a fmall ftone in the middle, the pa- ' tient having formerly fwallowed {mall ftones and pebbles, for what he called a colic in his ftomach. Tae Dr tells me, that all thefe three patients wafted, without being fick or lofing their appetite. They were fond of flefh for food, and were averfe to flops. They feldom were free of Lorborygmi, which made the abdomen to change .almoft con- fiantly its appearance, the parts of it rifing and finking as the air went from one place to another. Hift, 6. In a ball of this kind, eight inches one.way and fix the other, taken from a gentleman’s inteftines, whofe hi- ftory Ido not know, the zucleus is a little round piece of wood about the fize of a common hazle nut. Nowe of the balls mentioned in. thefe four laft hiftories have any tartarous crutt; but they and all the other cut ones have the Gage of being compofed of | firata 384 ESSAYS ano OBSERVATIONS frata farrounding the zuc/eus, their colour differing in fhades from a dark rufty toa pale afhy colour. Their fubftance, ex- cept where there is tartarous crafty re- fembles a fine hat or chamois leather when cut. Hifi, 7. IN the collection of curiofities kept by the Surgeons of this place, there is a ball taken out of the'ftomach of a horfe, which is nearly fpherical, and nine- teen inches in circumference. Its furface has fomething of the mulberry form, be- ing compofed of a great number of he- mifpherical knobs, about a quarter of an inch diameter, contiguous to each other. Their outward fhell looks like a thin eruft of. fandy clay; but within this the fubftance has the fame matted appearance as the human concretions have. Hif. 8. Bauus are alfo frequently formed in the ftomachs of cows. Three of them which were given to me, are a | moft exact fpheres of a black colour, com- pofed of an external hard tartarous cruit, . which | PHYSICAL anv LITERARY. 385 which is about 3% of an inch thick, Within this there is nothing but fhort black hairs matted compactly together. The circumference of the largeft is 9 in-= . ches;_ of the fecond, 6; and that of the third, is 53. Vor. I. Cec Art. 386 ESSAYS anp OBSERVATIONS ~ Art, XXVIL. Remarks on Procidentiz Ani, Intufufceptio, Inflammation, and Volvulus of the Inte- jiines; by ALEXANDER Monnxo fenior, M.D @ Ps A. AT ftool more or lefs of the infide of the reffum is generally thruft out be- yond the verge of the aus, which afcends when the preflure of the diaphragm and abdominal mufcles ceafes. If the pro- truded inteftine is not then retracted, it is fqueezed by the /phinéer ani, fo that the return of liquors from the part of it which is beyond this ftricture, muft be rendered difficult; on which account, this part {wells, becomes of a colour more red than natural, and a larger than ordi- nary quantity of flime flows from the ends of the veffels that open on its in- verted villous furface. This ftate is cal- oe led * February 6. 1755. _ 4 procidentia, is very faulty, They apply ee SS ee — PHYSICAL ann LITERARY. 337 led procidentia ani; a difeafe to which children, old people, thofe weakened by difeafes, or fuch as are attacked by tene/- mus, from whatever irritating caufe, are more fubje&t than others. Tue fpeedy reduction of the inverted protruded part of the inteftine, is the ef- fectual cure; nor fhould time be loft, as is often advifed, in trying to ‘diminifh the {welling by warm fomentations and poultices, which relax the veffels, and ra-~ rify the liquors, and therefore produce an effe&t very different from what they are intended to have. If the prolapfed inte- ftine is fo much {welled, that it cannot be made to pafs through the contracting Jphinéter, incifions may be made in its furface, by which part of the flime and blood contained in the cellular mem- branes, may be fqueezed out, to dimi- nifh its volume, and thus to make it ca- pable of returning again within the bo- dy. _ THE practice of the nurfes and other good women, in making the redudtion of i478 388 ESSAYS anp OBSERVATIONS a warm cloth to the protruded part of the gut, and preffling on it, endeavour to thruft it all up at once. Before the in- teftine {wells, this operation fometimes fucceeds with children whofe /phinder is weak, But dry cloths or fingers are lia- ble to adhere to the villous coat and give great pain in taking them off. The cloths or fingers applied here ought’ al- ways to be befmeared with oil, unfalted butter, or axunge, to. prevent this adhe- fion. The bulk of the prolapféd part 1g often fo great, that it is impoffible to make ‘it all pats” at once through the Sphinéter, and a fruitlefs attemptof reduc- tion generally increafes the fwelling. The reduction ought to be made by prefling a fmall part of the fides of the orifice with a gréafy finger, and, when that part is chruft within the orifice, another finger is appliéd to what is then the’ verge of the orifice to pufh it upwards, while the frit applied finger is withdrawn: By fach, an alternate fucceffion of two! fingers, the whole may be introduced in thoft ca~ fes without incifions; fo that this difeafe 15 PHYSICAL anp LITERARY. 389 is feldom fatal; and, for that reafon, the patient is generally too much negleéted after the reduction is made, which is fometimes attended with bad confequen- ces. | Ir, after the reduction, the part conti- nues to be pained and the patient's pulfe is quick, blood-letting,. and a low and cooling diet, are neceflary to prevent in- flammation and its confequences. In all cafes, too much coftivenefs, and its con- trary a diarrhea, efpecially with tencfnus, are equally to be guardéd ‘again{t;: feeing a return‘of the procidentia may be caufed by either of them: The relaxed parts are ato be braced by ftrengthening topical me- dicines- « In: the vaftringents) commonly ‘prefcribed, I can have no confidence ; ‘their effea& goes no deeper than the {kin ; but ftimulants; fuch as ardent {pirits or ‘tinctures of the aromatic refins made with them, give a fpring to all the: parts, and excite a glowing heat ‘whenever they are applied, fo as to touch any part of the ex- _ .fremity of the gut, which they can al- “ways be made to do, 390 ESSAYS anp OBSERVATIONS - T have faid, that this difeafe, the proci- dentia ani, is feldom fatal; and the reduc- tion of the prolapfed part of the inteftine into the body is generally regarded as a cure of it; but that this is not true, when the doubling of the inteftine is high up, will appear from the following hiftory. A large-fized, ftrong, healthy boy, a year and a half old, after a diarrhea of fome days, with tene/mus, was obferved to have a procidentia ani, which was treated two days by the women who attended him ; after which Mr Adam Drummond, Sur- geon in this place, was called to his af- fiftance. He reduced the procidentia fre- quently; but it foon returned, which made him defire I fhould be confulted. THE inverted inteftine ftood out four inches from the anus, without being much fwelled or of a deep red colour, and the child feemed to have no other difeafe. Mr Drummond moft eafily introduced all the tumor into the body ; but foon after it was puthed out again, upon the child’s having a defire to ftool, notwithftanding _a fervant’s keeping a finger on each fide of ee PHYSICAL anp LITERARY. 391 of the anus near to each other, while fome liquid excrement was pafled. After the reduétion was again made, I put my fin- ger, which is long, up the reéfum, pushing the orifice of the inverted gut on the point of it, and then found the orifice of the ins verted gut refembling the feel of the os tince of an unimpregnated womb refting on it, which I could throw up fome way further with a fudden jirk of the laft joint of the finger, but without being a- ble to invert it. We then caufed a large quantity of milk and water to be injected with force, while the two fides of the anus were prefied firmly on the pipe of the fy- ringe introduced by the anus into the redum, to prevent the liquor’s recoiling, in hope that the liquor would carry the inverted gut before it, to caufe its return to the natural fituation. This operation being repeated feveral times in vain, the procidentia always returning with. the ¢e- nefinus, a very long probe of whale-bone was made, a fponge was faftened round the probe, this was wet in oil, the probe was introduced into the orifice, which, I ) faid, 492 ESSAYS 4np OBSERVATIONS | faid, refembled an os tince, the fides of which refted on the {punge; and with this the inteftine was pufhed a great way up into the body in the direction of the rectum, but without fuccefs. Several at- tempts of the fame kind failing, we de- fpaired of a cure; and the child, fome time after, being attacked with fevere vo- miting and perpetual tene/mus, died ina few days. Mr Drummond, who opened the body, told me, that the inverfion began a little below the upper part of the figmoid flex- ure of the colon ; and that the mefocolon Was torn away from the inverted part. .’ WHEN a doubled part of an inteftine is extended into the cavity of this alimen- tary canal, without appearing externally at the auus, it is called intufu/ceptio, which, I am perfuaded, is a much more frequent difeafe than is generally thought. Ihave feen feveral whom I judged to have died by it, and fhall now relate the cafes of four people whofe bodies were examined after death, 1A | PHYSICAL anv LITERARY. 393 rA middle-aged woman, during fix- teen months before her death, fuffered greatly from colic-pains, diftenfion of her belly, vomiting, and fenefmus. In the jatter part of her life, when I firft {aw her, fhe had no ceffation from pain, except by the force of opium. © ‘In the great arch of the cols was a doubled part of that gut, feven inches jong. 7 he containing inteftine had a ve- ry flight adhefion to the inverted doubled. part contiguous to it. The doubled part ‘was of a dark red colour, but not very hard, The paflage for the feces through it was very narrow, not allowing a finger pufhed with force to pafs. 2- A woman about fifty years of age lived two years with fuch fymptoms as were narrated in the preceeding cafe. We _ found a doubled part of the colon four in- ches long in the left loin, with the fame _ appearance as defcribed in the former hiftory. 3. A girl feven year old, after eating a § carrot and fome curren-berries, had a es colic which continued with a diftended Vou. Il, Ddd - belly, aaa ee nr 394. ESSAYS anv. OBSERVATIONS belly, vomiting, and pafling little feces, from July till the middle of December, notwithf{tanding various medicines were. given. ae Mr Malcolm furgeon in Dalkeith, whofe patient fhe was, being allowed to open her corpfe, cut out the affected part of the inteftine, and fent it to me. The end of the zum, valvula Tulpi, caput coli, and appendix vermiformis, were raifed twelve inches within the colon, to which they had a flight adhefion. The outer furface of the contained inteftines was dark coloured, and very unequal. The orifice of the prolapfed part was not at its end, but at one fide an inch and a half from the end, with a foft flexible pro- minence at each fide of the aperture, which I judge to have been Tulpius's : valve, The doubled parts were fo grown together, that I could not diftinguifh one from the other, The paflage within them was fo fmall and crooked, that I could not pufh a probe through it; but, cutting it open gradually, I found it was ftill pervious. _ RE . 4. De PHYSICAL anp LITERARY. 395 vd 4. Dr Cullen, profeffor of medicine in the univerfity of Glafgow, communicated the following cafe to me. A boy about twelve years of ape coms plained of wandering colic-pains, which he imputed to blows received on his belly from fome of his companions. Thefe pains returned frequently with diarrhea, and fometimes bloody ftools; for near a year, when his parents confulted Mr James Muir furgeon in Glafgow about him. The boy was then much emacia- ted, had a quick pulfe, and was fo weak as to be confined to his bed. Two weeks after this, a livid-membranous fubftance, paffed by the boy at ftool, was brought to Mr_ Muir; who, obferving it to be tubu~ ® lar, tied one end of it, and blowing ; into . ‘ - which | caufed to bé drawn from the ori- the other, diftended it into fuch a con= voluted tube thirteen inches long, as you fee reprefented A BC, Fig. 1. Fab. VII. ginal which was fent me. Ass it has the % _ mefentery D connected to all its concave. fide, it appears to have been an entire _ pitce of gut, and not the villous coat on- ly, 396 ESSAYS anp OBSERVATIONS ly. Befides this large portion of inteftine, there were feveral threds and fmaller pie- ces paffed by the patient ; notwithftand- ing which, Mr Muir faw afterwards, a= mong the boy’s feces, {kins of potatoes which he had eat after thefe parts of the | inteitine came away, fo that they had not made any difcontinuity in the ali- mentary canal. The fymptoms continu- ing, the boy died in fix weeks. Mr Muir opened the body of his pa- tient, in prefence of feveral gentlemen of the faculty, who faw what | am now to defcribe, with the afliftance of a figure, which I caufed to be taken of the dried preparation of the inte({tine fent me. Tue folds of the inteftines and omen- tum were all glued together by a fatty cur- dy matter. Within four inches of the valve of the colov, the ilium ABC, Fig. 2, Tab. Vil. formed into the ufual curve by the mefentery D fuddenly rofe perpendi- cularly at E, where it was much contract- ~ed and had the appearance of a cicatrice. When the inteftine was opened, this con- tracted part of it was found much thick- erg PHYSICAL anv LITERARY. 397 er and harder than it was any where elfe, efpecially on one fide, where it ftood fo far into the cavity, as to leave a very {mall paflage for the aliment. Along this con- tracted part, the mefentery F was firm and thick. After this, the inteftine G became: of a natural cnangh form and make. THE rele dec in -Glafgow were, | think, juftly of opinion, that the part of the inteftine inflated by Mr Muir, deline- ated.in Fig. 1, was an intufufcepted part fallen away by gangrene from the in- teftine at E. in Fig. 2..where, if there was a concretion, as is related in cafe 3, it might have feparated without leaving any difcontinuity in the alimentary ca~ nal, | Sis have feveral times feen an intu/ufeep- #io in. the fmall guts of children, a little below which I obferved feveral worms 3 but the inverted part was neither {welled nor difcoloured, which made me think this diferder had happened foon: before death. Im one of them a lumbricus teres had _ the half of its length thro’ a hole 398 ESSAYS anv OBSERVATIONS hole made in the gut; but, as there was no rednefs or other mark of inflammation atthis part, I judged the perforation to have been made by the worm after the death of the fubject. | THERE is little difficulty in concei= . ving how a piece of a gut fhould enter doubled into the part below it, and how it may be gradually protruded downwards to a confiderable extent by the food of feces, in their defcent towards the anus; but it is not eafy, when this difeafe be- gins, to diftinguifh it from a variety of other diforders which happen im the ali-+ mentary canal, or to find a remedy when it is fufpected, efpecially if the zntufeu/cep- tio is in the fmall guts; and from the obfervation above narrated of the child with the fatal procidentia ani, it would ap; pear difficult to cure it; nay, if the doubled parts of the inteftine are grown together, as in moft of the hiftories, a reduction of it is impoffible. Nature fel- dom will perform what I imagine fhe did in the laft cafe, feparate the doubled part,. and unite what contained it. Nor do 2} believe PHYSICAL anny LITERARY. 399 believe any will be fo hardy as to advife the amputation of the affected part of the - gut. ‘Tis furprifing how the people in the preceeding hiftories lived fo long as they did, with fuch large doublings of the in- teftine, and its mefentery preffed together within another piece of inteftine, when the common inflammation of the inteftine often kills foon thofe it attacks; of which I could give numerous examples, but fhall relate only one. A Gentleman of weak nerves, and fubje& to flatus and pain in his ftomach, was feized with a cholic- pain about ten o’clock at night, for which he fwallowed a fmall quantity of an ar. dent fpirit. At three in the morning, twelve or fourteen ounces of blood Were let from a vein in his arm, and a laxative clyfter was injected, and operated well. At eleven that forenoon, I firft faw him, when his friends thought him much bet- ter, being free of pain; but, as his belly _ Was greatly fwelled and very tenfe, his pulfe quick,. fmall, and Antermitting, his eyes 4oc ESSAYS ANp OBSERVATIONS ~ eyes languid, his countenance faded, and ~ a cold clamy fweat was over all his body, I made the prognofis of his having very few hours tolive. He died before five of the atternoon, fo that his difeafe killed him in eighteen hours ; and I have heard of others who died in lefs than twelve hours after the firft appearance of inflam- mation. THE common practice of taking fpiri- tuous liquors, or the warm carminatives, when people feel colic-pains, is often un- lucky, and public warning fhould be gi- ven againit it; for, tho’ relief is found from fuch things in the windy or f{pafmo- dic colics, which is not a deadly difeafe, yet * they hurry onthe inflammatory ones fo faft that they foon prove mortal. I muft like- wife think that writers on the inflammation of the inteftines don’t reprefent ftrongly e- nough the languor and low {mall pulfe which fuch patients generally have more than in moft other difeafes. Itis fuch, that I have feen feveral cafes, where people of fill, deceived by thefe fymptoms, have been afraid to order blood-letting, left the ” patient GX OOO OO yas PHYSICAL ann LITERARY. or patient had not ftrength to bear iit, and thereby neglected this evacuation till it was too late. Whenthere is a fixed pain in the ftomach or inteftines, witha quick, _ tho’ fmall pulfe, no time is to be loft; blood ought immediately to be let plenti- fully, and venefection fhould be repeated tall the pulfe becomes full and free, which 4s a hopeful fign of a cure’s being made, tho’ neither pain nor fever have yet ceafed. | THE intufyfceptio or inflammation; but efpecially the latter, is generally the caufe of what is commonly called the iliac pat: fion or miferere; for the volvulus or twitt- ing a part of the inteftines into a knot, which was formerly faid to be the cafe, is generally thought now, when anatomy is more cultivated, and infpection of mor- bid bodies is more univerfally allowed, to be an imaginary evil. It is very rare, but not imposible, as will appear from the hiftory fubjoined to this, and com- municared to me by my Son, Vou. Il. Kee ART. 402 ESSAYS anp OBSERVATIONS | ART. XXVIII. A Fiflory of a genuine Volvulus of the In- tefliness by ALEXANDER Monro, juni- or, M. D. and Profeffor of Anatomy *. A N old man complained of a colic, which was neglected more than two days; when Mr William Wood Sur- geon in Fdinburgh being called, found him in the agonies of death, Next day I obtained leave to open his abdomen, in prefence of feveral ftudents of phyfic. We faw fourteen inches long of the zte- fiinum ilium hanging in a finus down in the pelvis, all black and mortified, occa- fioned by a ftrangulation at the upper part of the two pieces of the cium which formed the finus. The firm ftri@ture there was made by the appendix vermiformis, the body of which lay behind the con- ftricted parts of the ifium, while the end of * February 6. 1755. PHYSICAL anp LITERARY. 402 of it pafling over and before them, had funk back again into a plica of the mefen- tery, from which, with great difficulty, I could draw it out; for it was there extended inte a globular fhape of three fourths of an inch diameter, by a glairy liquor, and was lodged in a depreffion of the mefen- tery, the entry to which was fmaller than ‘the cavity where the globular end of the appendix had been lodged. AR Te 404 ESSAYS ann OBSERVATIONS ART. XXIX, 4 Defcription of the American Yellow Fe: wer, ina Letter from Dr Joun Lint NG,, Phyfician at Charles-town in South Ca- rohna, toDr Ropert Wuytt Pro Sefer of Médiine in the Univerfity af E- dinburgh, ee ae, CHArLEs Town, December 34, 17530. ‘* » N obedience to your defire, I have - i fent you the hiftory of the yellow “‘ fever as it appeared here in the year “1748, which, as far as I can remember, ** agreed in its fymptoms with the fame “* difeafe, when it vifited this town in for= “mer years In this hiftory, I have con- ' “ fined myfeif to: a faithful narration of “facts, and have avoided any phyfical: ‘inquiry into the caufes of the feveral. “* fymptoms in this difeafe; as that would “have required more leifure than I am,. i oe * March 7 rr5ae - PHYSICAL anp LITERARY. 405 at prefent, mafter of, and would per- “haps have been lefs ufeful than a plain * deicription. ‘‘T wrote this hiftory, fo far as it re- “lates to the fymptoms and prognoftics, “in the year 1748, when we had the “* difeafe laft in this place; intending af- terwards, if it returned, to add, from “ further experience, the method of cure, “ and likeways an account of any other “fymptoms which might attend it; but, “as no fuch opportunity has offered, I * muft now omit that parts However, I “hope the defcription which I have gi- “ven of this dreadful malady, which fo “ frequently rages like the plague in the “ fouthern parts of America, is fo. full, “ that a phyfician may, from thence, not “ only form a true judgement of its: na- “ture, but likeways be able to deduce “and communicate fome more certain * method of cure than has perhaps hi- “ therto been ufed. “Tam forry I could not give a fuller & account of the diflections. of thofe who ; . died. 406 ESSAYS anp OBSERVATIONS “ died of this difeafe, having unfortu- “ nately loft my notes taken from thofe “ diffections. “ Tam,” &c. I, i Beet fever, which continues two’ or three days, and terminates ~ without any critical difcharge by fweat, urine, ftool, &c. leaving the patient ex- ceflively weak, with a {mall pulfe, eafily depreflible by very little motion, or by an erect pofture, and which is foon fuc- ceeded with an icteritious colour in the white of the eyes and the fkin, vomiting, hemorrhages, &c. and thefe, without be- ing accompanied with any degree of a fe- brile pulfe and heat, is called in America, the Yellow Fever. Il. THis fever does not feem to take its origin from any particular conftitution of the weather, independent of infectious miafinata, as Dr Warren * has formerly well obferved. For, *In his treatife concerning the malignant fever in Barbadoes, page &.. I PHYSICAL anv LITERARY, 407 For, within thefe twenty-five years, it has only been four times epidemical in this town, namely, in the autumns of the years 1732, 39,45, and 48, tho’ none of thefe years (excepting that of 1739, whofe fummer and autumn were remark- ably rainy) were either warmer or more rainy (and fome of them lefs fo) than the fummers and autumns were in feveral o- ther years, in which we had not one inftance of any one being feized with this fever ; which is contrary to what would proba- bly have happened, if particular conftity- | tions of the weather were productive of it, without infectious miaf/mata. But, that this is really an infectious difeafe, feems plain, not only from this, that almoft all the nurfes catched it and died of it; but likewife, as foon as it appeared in town, it foon invaded new comers, thofe who _ never had the difeafe before, and coun- | try-people when they came to town, while _ thofe who remained in the country .efca- " ped it, as likewife did thofe who ‘had for- _ merly felt its dire effects, tho’ they- walk- _ed about the town, vifited the fick in all the 408 ESSAYS anp OBSERVATIONS the different /fadia of the difeafe, and at- tended the funeral of thofe who died of it. And, laftly, whenever the difeafe appeared here, it was eafily traced to fome perfon who had lately arrived from fome of the Weft-Indian !flands, where it was epide- mical. Altho’ the infeétion was fpread with great celerity thro’ the town, yet, if any from the country received it in town, and fickened on their return home, the in- fection fpread no further, not. even fo much as to one in the fame houfe, Ill. THE fubjects which were fufcep- tible of this fever, were both fexes of the white colour, efpecially ftrangers lately arrived from cold climates, Indians, Mi- ftees, Mulattoes of all ages, excepting young children, and of thofe only fuch as had formerly efcaped the infection. And indeed it is a great happinefs that our conftitutions undergo. fuch alterations . } in the fmall-pox, meafles, and yellow fe- ver, as for ever afterwards fecure us from a fecond attack of-thofe difeafes. There is fomething very fingular in the confti- tution of the negroes, which renders them not PHYSICAL anv LITERARY. 409 not liable to this fever ; for though many of thefe were as much expofed as the nurfes to the infection, yet [ never knew one inftance of this fever amongft them, though they are equally fubje& with the white people to the Jilious fever. IV. Tuts fever began in the middle or rather towards the end of Auguft, and continued till near the middle of OGober, when the weather became cold enough to prevent its further progrefs. In the be- ginning of Auguft, the weather was warmer than I had ever known it in that month: The mercury in Farenheit’s ther- mometer, for fome days at 2 o’clock p. m. rofe, in the fhaded air, to the 96th degree, at which time feveral people died of apoplexies. The latter part of Auguft and the firft week in September were much more temperate ; the weather being then much as ufwal at that feafon of the year. : The fecond week in September was cold, _ the wind being conftantly eafterly and the : weather cloudy; after which time I kept a regifter of the heat of the fhaded air ; an abftract of which follows. Vou. Il. FE ht 410 ESSAYS anp OBSERVATIONS In the latrer part of September, and from the rft tothe 15th of OGtober, Septemb. O80. The mean heat at. p.m. was 72. 66 The mean nocturnal heat was 68 54 The greateft heat at 2 /..m. was.79 75 The leaft heat at 2 p.m. was 60 ‘n2, he greatet nocturnal heat was 71 70 The leaft nocturnal heatwas 62 42 The greateft increafe of heat in 24 hours was re 4 The greateft decreafe of heat in 24 hours was Or tea a2 In all the month of September, and in the greateft part of Odtaber, the wind was eafterly- THE depth of the rain in Auguft, Sep~ tember, and Odober refpeCtively, was 6.881, 7442 and. 5.550 inches; which, theugh it exceeded the rain of theft three months taken together at a medium, from. the ten preceeding years, by 5.570 inches, yet it was inferior to that which fell in. the fame months in feveral cther years 5 forin the years 1747; 50, 51,and 52, there felh PHYSICAL any LITERARY. 414: ¥ell ‘refpectively, in thofe ‘three. months of thefe years, above 21, 22, 24 and 26 inches of rain. , V. For a day or two before the attack of the fever, people in general complain- ed of a headach, pain in the loins’and ex- _tremities, efpecially in the knees and calves of the legs, lofs of appetite, debility and a fpontaneous lafiitude. ; Some however were feized fuddenly, “without any fuch previous fymptoms. VIL AFTER a chilnefs and hérror, with which this difeafe generally invades, a fe- ver fucceeded ; in which, ) 1. THE pulfe was very frequent till near the termination of the fever, and was generally tull, hard, and confequently ftrong: In fome, it was {mall and hard, .in others, foft and fimall; but, in all thofe cafes, it frequently varied in its fullnefs and hardnefs. | Towards the termination _of the fever, the pulfe became fmaller, -harder, and lefs frequent. In fome there was a remarkable throbbing in the caro- tids and in the Aypochondria; in the iatter __ of which, it was fometimes fo great, that it 412 ESSAYS any OBSERVATIONS it caufed a conftant tremulous motion of the abdomen. | ) | 2. THE heat, generally, did nde exceed 102 degrees of Farenheit’s thermometer ; in fome it was lefs, it varied frequently, and was commonly nearly equal in all parts, the heat about the precord:a being feldom more intenfe than in the extremi- ties, when thefe were kept covered. In the firft day of the difeafe,fome had fre- quent returns of a fenfe of chillnefs, though there was not any abatement of their heat. In a few, there happened fo great a remiflion of the heat for fome. hours, when at the fame time the pulfe was foft and lefs frequent, and the fkin moift, that one, from thefe circumftances, might reafonably have hoped that the fe- ver would only prove a remittent or inter- mittent. About the end of the fecond day, the heat began to abate. 3. THE fein was fometimes (though -yarely) dry ; but oftner, and indeed ge- nerally, it was moift and difpofed to feat. 3 PHYSICAL anp LITERARY. 413 On the firft day, the {weating was com= monly profufe and general; on the fee cond day, it was more moderate: But, on both thefe, there happened frequent and fhort remiffions of the fweatings ; at ‘which times>the febrile heat increafed, and the patient became more uneafy. On the third day, the difpofition to fweat was fo much abated, that the fkin was generally dry; only the forehead and backs of the hands continued moift. 4. THE reéfpiration was by no means frequent or difficult, but was foon accele- rated by motion, or the fatigue of drink- ing a cup of any liquid. 5+ THE tongue was moilt, rough and white, even to its tip and edges. On the fecond day, its middle in fome was brown, On the third day, the whitenefs and roughnefs of the tongue began to abate. -6. THE zhirfi in very few was great. 7. A naufea, vomiting or frequent reach- ings to vomit, efpecially after the exhibi- tion of either medicines or food, came on generally the third day, as.the fever began to lefien ; or rather as the fulnefs of the pulfe, 414 ESSAYS anp OBSERVATIONS» pulfe, heat, and difpofition to fweat, be- gan to abate. Some indeed, but very few, on the firft day, had a vomiting either bi- lious or phlegmatic. 8. VERY few'complained of anxiety or oppreffion about the precordia or hypochon= . dria, nor was there any tenfion or hard- nefs about the latter. 9. ON the firft day they generally dozed much, but afterwards were very watch- ful. | 10. Reftlefsnefs and almoft continual jactations came on the fecond day, 11. A great defpondency attended the fick trom the firft attack. 12. THE ftrength was greatly proftra- ted from the firft, attack. 13. THE pain in the head, loins, &c, of which they had complained (V.) be- fore the attack, were greatly increafed, and in fome, the pain in the forehead was very acute and darting; but thofe pains went generally off the fecond day. 14. THE face was flufhed, and the oy were hot, inflamed and unable to bear much light. elas 15,ON PHYSICAL anp LITERARY. 41s 15. ON the firft day, many of them, at times, were a little delirious, but after- wards not until the recefs of the fever, 16. THE blood faved at venefection had not any inflammatory cruft; im warm weather, it was florid like arterial blood, and continued in one foft homogeneous- like mafs, without any feparation of the ferum after it was cold. When there was any feparation, the craffamentum was of too lax a texture, 17. THE ftools, after the firft day, were: fetid, inclined to a black colour, and were: very rarely bilious, foft or liquid, except= ing when forced by art; for an obftinate. coftivenefs attended the febrile flate. ‘18. THE urine was difcharged in a large qu antity, was pale, fometimes limpid,, and rarely of a higher than a ftraw colour,, except when the weather was very warm, ~and then it was more faturated, of a deep: eclour, and difcharged in imaller quanti- ties. It had a large cloud, except when it was very pale or limpid; but more gene+ rally it had a copious white fedimenty, even in the firft day of the fever. le On 416 ESSAYS And OBSERVATIONS - On the fecond day, the urine continued to be difcharged very copiouily ; in fome, it was then turbid, and depofited a more copious fediment, than on the firft day ; this fediment was fometimes of 2 brown= ifh colour ; in which cafe it was generally followed by bloody urine, either about the end of tke fecond, or beginning of the third day. The colour and quantity of the urine, difcharged in equal times, were remarkably variable, being now limpid, then of a deéper colour, now difcharged; ina larger, then in a fmaller quantity; which could not be afcribed to any change made either m the quantity or quality of the drink, dc. VII. Tu fever accompanied with thofé (VIL.) fymptoms, terminated on the third day, or generally m lefs than 72 hours from the firft attack, not by any afimula-= tion or coétion and excretion of the mor- bid matter; for, if by the latter, there would have been fome critical difcharge by fweat, urine, ftool, or otherways, none of which happened; and if by the for= mer, nothing then would have remained but - PHYSICAL anp LITERARY. 417 but great debility. No; this fever did not terminate in either of thefe falutary — ways, excepting in fome, who were hap- py enough to have the difeafe conquered in the beginning by proper evacuations, and by keeping ‘up a plentiful fweat, ull the total folution of the fever, by proper mild diaphoretics and diluents. But thofe who had not that good fortune, however tranquill things might.appear at this pe- riod, (as great debility and a little yellow- nefs in the white of the eyes feemed then to be the chief complaints, excepting when the vomiting continued), yet the face of affairs was foon changed; for this period was foon fucceeded by the fecond fladium ; _aftate, though without any fever, much _ more terrible than the firft; the fymp- _ toms in which were the following : VU. 1. THE pulfe, immediately after _ the recefs of the fever, was very little more : frequent than in health, but hard and ; fmall. However, tho’ it continued {mall, it became, foon afterwards, flower and | very foft; and this foftnefs of the pulfe remained as long as the pulfe could be felt. You. Il. Gegeg In 418 ESSAYS anp OBSERVATIONS | In many, in this ftage of the difeafe, the pulfe gradually fubfided, until it became f{carce perceptible ; and this, notwithftand- ing all the means ufed to fupport and fill it; and, when this was the cafe, the icte- ritious-like fuffufion, the vomiting, delir- um, reftlellnefs, oc. increafed to a great degree. ‘In fome, the pulfe, after being exceedingly {mall and fcarce perceptible, recovered confiderably its fullnefs ; but that favourable appearance was generally of but fhort continuance. . 2, THE heat did not exceed the natural animal heat; and, when the pulfe fubfided, the {kin became cold, and the face, breaft, and extremities, acquired fomewhat of a livid colour. | . THE {kin was dry when the weather was Soar. but was moift and clammy when the weather was hot. 4. THE refpiration was natural or ra- ther flow. | 5s. THE tongue was moift he much cleaner than in the former (VI. 5.) ftage; its tip and edges, as alfo the gums and © r , Lips, | | | PHYSICAL anv LITERARY. 41g lips, were of a more florid red colour than ufual. 6. Very few complained of thirft, tho’ they had a great defire for cold liquors. 7. THE vomiting or reaching to vomit increafed, and in fome was fo conftant, that neither medicines nor aliment of any kind were retained. Some vomited blood ; others only what was laft exhibited, mixed with phlegm ; and others again had what is called the black vomit *. The reaching to vomit continued a longer or fhorter time, according to the ftate of the pulfe ; for, as that became fuller, and the heat greater, the reaching to vomit abated, and, : é contra, 8, FHEe * That which is called the Black vomit, at firkt fight, appears to be black ; but, ona more careful examination, T obferved, that this colour proceeded from a great quan- tity of fmall, flakey, black fubftances which floated ia the ’ liquor thrown up by vomit ; but the colour of this liquor Was much the fame with that which the patient had laft drank, and was by no means black. Thofe black flakey' fabftances are the bile mixed with, or adhering to, the meus which lined the ftomach, For, upon diffection of thofe 420 ESSAYS anp OBSERVATIONS 8. THE inquietude was very obftinate, and when they dozed, their flumbers were but fhort and unrefrefhing. There were fome who were drowfy ; but thefe always awaked, after the fhorteft flumbers, with a great dejection of {pirits and ftrength. y. THE jacfations or reftleffnefs was furprifing 5 it was frequently fcarce pof= fible to keep the patients in bed, though, at the fame time, they did not complain of any anxiety or uneafinefs ; but, ifafk- ed how they did, the reply was, Very ro. THR thofe who died of this difeafe, not only in this but former years, { alwaysobferved that the mucus of the Romach-was: abraded, and the bile in its cy/?#s was black and fometimes. very vifcid. In a Jad who died of this difeafe in the begin- ning of the fourth day, and who was immediately open- ed, the bile was not only black, but had the confillence cf thick Venice-turpentine, and was exceedingly tough, On the infide of the flomach, there were feveral carbuncles or gangrenous fpecks. And, in all thofe have difleted, wha have died ot this difeafe, | have'not only always obferved the fame, but likeways that the blood was very duid, and the veflels of the vi/cera much dillended; from whence: J have been very inclinable to think, when the difeafe was not conquered in its firlt /fadium, that, about the time of the termination of the fever, there was a 7e~ tafafis of the morbid matter to the vi/cera, PHYSICAL ann LITERARY. 421 10. THE debility was fo great, that, if the patient was raifed ere& in the bed, or, in fome, if the head was only raifed from the pillow, while a cup of drink was given, the pulfe funk immediately, and became fometimes fo fmall, that it ' could fcarce be felt; at this time, they became cold, as in a horripilatio, but without the anferine-like fkin: Their {kin became clammy, the de/irium increafed, their lips and fkin, efpecially abour the neck, face, and extremities, together with their nails, acquired a livid colour. 11. THE delirium returned and increa- fed ; it was generally conftant in thofe whofe pulfe was {mall and fubfiding. 12. THE inflammation of the tunica conjunctiva or white of the eyes incteafed - much, but without pain. | __ 13. A yellowne/s.in the white of the eyes, if it did not appear before in the febrile ftate, became now very obferva- ble, and that icteritious-like colour was foon diffufed over the whole furface of the body, and was continually acquiring a deeper faffron-like colour. In fome in- * deed 422 ESSAYS 4nd OBSERVATIONS deed no yellownefs was obfervable, ex- cepting in the white of the eyes, until a little before death, when it increafed fur- - prifingly quick, efj eee about the breaft and neck. 14. THERE were many fmall /pecks, not raifed above the fkin, which appear- ed very thick in the breaft and neck ; but lefs fo in the extremities, and were of a {carlet, purple, or livid colour. 15. IN women the menf?rua flowed, and fometimes exceflively, though not at their regular periods. 16, THERE was fuch a putrid diffolu- tion of the blood in ‘this//tadium of the difeafe, that, befides the vomiting of blood formerly mentioned, and the bloody urine foon to be taken notice of; there were hemorrhagies from the nofe, mouth, ears, eyes, and from the parts which were bliftered with cantharides. Nay, in the year 1739 or 4745, there was one or two inftances of an hemor- thage from the fkin, without any ap- parent puncture or lofs of any part of the {carf-fkin. 17. AN PHYSICAL ayy LITERARY. 423 17. AN obftinate coftivere/s continued in fome ; in others, the {tools were fre= quent and oofe; in fome, they were black, liquid, large, and greatly fatiguing; in others, when the {tools were moderate, even though they were black, they gave great relief; in others again, the ftools nearly refembled tar in {moothnefs, te- nacity, colour, and confiftence. 18, THE urie was difcharged in a large quantity, in proportion to the drink. retained by the patient: It was pale, if the patient was not yellow; but if yellow, then it was of'a deep faffron-colour; in either cafe, it had a fediment, or at leaft a large cloud, which remained at the bottom of the glafs; in fome, it was ve- ry turbid, in others, it was very bloody, and the quantity of blood difcharged with the urine, bore always fome proportion to the ftate of the pulfe; when that be- came fuller, the quantity of blood in the urine was diminifhed: When the pulfe - fubfided, the bloody urine increafed, and eyen returned after it had ceafed fome days ; 424 ESSAYS anp OBSERVATIONS days; foon after, the pulfe became fmal- ler. ‘ . Tus ftage of the difeafe continued fometimes feven or eight days before the patient died. IX. WHEN this fladium (VIII.) of the difeafe terminated in health, it was by a recefs or abatement of the vomiting, hz- morrhagies, delirzum, inquietude, jacta- tions, and icteritious-like fuffufion of the {kin and white of the eyes; while, at the fame time, the pulfe became fuller, and the patient gained ftrength, which, after _ this difeafe, was very flowly. . But, whenit terminated in death, thofe (VIII.) fymptoms not only continued, but fooner or iater increafed in violence, and were fucceeded with the following, which may be termed the shird fiadium of the difeafe, which quickly ended in death. X. THE pulfe though foft became ex- ceedingly fmall and unequal ; the extre- mities grew cold, clammy, and livid; the face and lips, in fome, were flufhed; in others, they were of a livid colour; the livid fpecks increafed fo faft, that in fome, the PHYSICAL anv LITERARY. 42¢ ' the whole breaft and neck appeared livid; the heart palpitated ftrongly ; the heat about the precordia increafed much ;_ the refpiration became. difficult, with fre- quent fighing ; the patient now became anxious, and extremely reftlefs ; the fweat flowed from the face, neck, and breaft; blood flowed from the mouth; or nofe, or ears, and in fome, from all _ thofe parts at onee; the deglutition be- came difficult; the hiccoughs and /ub- Jultus of the tendons came on, and were frequent; the patients trifled with their fingers, and picked the naps of the bed- cloaths; they grew comatous, or were conflantly delirious. In this terrible itate, fome continued eight, ten, or twelve hours before they died, even after they had been fo long fpeechlefs, and without any perceptible pulfation of the arteries in the wrifts ; whereas, in all other acute difeafes, after the pulfe in the wrifts ' ceafes, death follows immediately. When - . the difeafe was very acute, violent con- vulfons feized the unhappy patient, and, » quickly brought this /ladium to its fatal ame VOL. I, - Hhh ‘ ends 426 ESSAYS anp OBSERVATIONS end. After death, the livid blotches in- ereafed faft, efpecially about the face, | breaft, and neck, and the putrefaCtion began very early, or rather increafed ve- ry quickly. . XI. Tus was the progrefs-of this ter- rible difeafe through its feveral /tadia, But, in hot weather, and when the fymptoms: in the firft ftage were very violent, it paf- fed through thofe ftages, as Dr Warren has likewife obferved, with fuch precipita- tion, that there was but little opportuni- ty of aiftinguifhing its different fudia ; the whole tragedy having been finifhed: in lefs than 48 hours. XII. Ir was remarkable, that, r. The infection was increafed by warm and leffened by cold weather. 2. The fymp- toms in the feveral /fadia were more’ or lefs violent, according to the heat er coolnefs of the weather. ‘In hot days, the fymptoms were not only more violent, but in thofe who feemed, in mo-~ derate weather, to be on the recovery, or at leaft in no danger, the fymptoms were all fo greatly heightened, when the wea- | ther PHYSICAL ann LITERARY. 427 ther grew confiderably warmer, as. fre- quently to become fatal. In cool days, the fymptoms were not only milder, but many, who were apparently in great. danger in hot days, were faved from the very jaws of death by the weather be- coming happily cooler. 3. The difeafe was generally more fatal to thofe, whe lay in {mall chambers not conveniently fituated for the admiffion of ‘freth air, to. thofe of an athletic .and full habit; te ftrangers who were-natives of a cold cli- mate, -to thofe who had':the. greateft dread of it, and to thofe, who, before the, attack of the difeafe, had overheated themfelves by exercife in the fun, or by: exceflive drinking of {trong liquors ; either of which indeed feemed to render the body more fufceptible of the infection. Laftly, the difeafe proved moft certain- ly fatal to valetudinarians, or to thofe who had been weakened by any previous difeafe. KILL. Tue prognoftics in the firft /ladi- um are thefe: 1. The more acute and con- _ ftant the pains are in the head, loins, knees, rte 428 ESSAYS anp OBSERVATIONS dc. the more the eyes are inflamed, the greater their inability is to bear light, and the more the face is flufhed at the firft at- tack, the fever and all the fymptoms (VI.) in the firft /fadium will be the more vio- jent. 2. The more intenfe the fymptoms are in ‘the firft ftate, the fooner will the fever terminate. -°3. The fooner the dif- eafe runs thro’ the firtt fadium, the fhorter will be the duration of the fecond, ef ¢ contra. 4. The fhortéer the’duration is of the firft, the greater'and more certain’is the danger in the fecond ftate... For, when the fever terminated before the béginning of the third day, death feemed inevitably to‘be'the confequence, as‘ there’ was then no poflibility of fapporting the pulfe, and as all the bad fymptoms were then hurried of with fuch precipitation, that the patient generally died before the end of the fifth day, excepting a confiderable coolnefs of the weather happily interveened ; but, on the contrary, it was a favourable circum- {tance when the fever was protracted to the-end of the third day, without any re= markable hardnefs or depreflion of the © pulfe, PHYSICAL aN LITERARY. 429 pulfe. 5. A’great’deprefiion of the pulfe, - about the termination of the fever is bad; fince, from ‘that circumftance, the vomit- ings, inceflant:jactations, the’coldnefs and lividnefg of the extremities, hemorrhagies, delirium, &c- are ufhered in with furpri- fing‘celerity.) 6. The more the ftrength is _proftrated from the firft attack, the greater is the danger.’ 7.. A vomiting coming on early, in the difeafe, and contiauing or in- creafing, is bad, and generally prefages the black vomit. 8. A fediment-in the uriné in the firft and fecond day .of the difeafe is bad; and, the more copious the fediment is, the greater is the danger,. ; _XIV. THE prognoftics in the eis fia: 7 i are thefe: 1, An early yellownefs in the white of the eyes is. bad:,When itis: - obfervable about the end of the fecond day, in the firft /tadmum, the patient gene- rally dies about the beginning of the fourth day from the firtt attack of the difeafe. But, when the yellownefs does not. appear _ -till.the end of the third day, if the patient does not recover, the difeafe fometimes - continues to oth or roth day of the fecond radium 430 ESSAYS anp OBSERVATIONS fladium before the patient dies. When the yellownefs of the {kin and eyes increafes faft, and acquires foon a deep icteritious- like colour, the: greateft danger is to be apprehended. 2. If the inflammation of the white of the eyes increafes, it is bad. 3. The more inflamed and bloody-like the fkin is where it has. been bliftered, the greater is the danger. . 4. If the vomiting continues or increafes, it is bad; but the black vomiting is generally mortal. 5. When the pulfe varies frequently in its fullnefs, being fometimes f{mall, then full- er, it is bad. But there was lefs depend- ence'to be had on the pulfe in this than is common in other difeafes; for,m fome © patients, in the fecond ftage of the difeafe, even within a few hours of their death, the pulfe, with refpect to its fullnefs, foft- nefs, equality and frequency, has conti- nued like that of one in perfect health, altho’, from the other fymptoms, the death of the patient could be foretold with great certainty. 6. The. more the ftrength of the patient is reduced in the firft, the greater is the danger in the fecond fiadium. | 7. Great PHYSICAL anv LITERARY. 43t 7. Great reftleffnefs, inquietude, an ear- ly deliritm, and'a continuation of ‘it, are very bad. 8. Livid blotches about the neck and breaft, a lividnefs of the lips and. nails, flufhing of the face, ora livid co- lour thereof, are fure figns of the quick approach of death. 9. Frequent loofe ftools, which give not any relief, are bad; and, the fooner they fpontaneoufly happen, the greater is the danger: But thofe which © are black, and continue fo without any abatement of the fymptoms, are generally mortal. 10. Bloody urine and all hemor- rhagies, excepting flight ones from the nofe, are bad ; and, the more copious they are, the greater is the danger. But a flux of the menfes, tho’ not at their regular pe- riod, if attended with an abatement of the fymptoms, is a favourable circum= ftance ; otherwife, it is bad. 11. A fup- - preffion of urine, efpecially in thofe, who, in the courfe of the difeafe, have had large difcharges that way, is a certain fign of the quick approach of death. XV. As 432 ESSAYS anp OBSERVATIONS. ' XV. As to the prognoftics in the third (X) fiadium, it is fufficient to fay _. *¢ Nature, alas! was now farpriz’d, “* And all her forces feiz'd, “‘ Before fhe was how to refift advis’d *. * Dr Sprat’s Account of the plague of Athens». _ AR ¥. ‘PHYSICAL anv LITERARY. 433 ART. RAR. Anfwer to an Objection againft Inoculation; by EBENEZER GitcurisT, M.D. Phy- fician at Dumfries *. No CULATION has been practifed here ] about five and twenty years, twenty almoft conftantly. The fuccefs of it foon demonftrated the great advantage and ne- ceflity of it, efpecially in a place long re- markable for bad {mall-pox. A letter I. wrote two or three years ago to a gentle- man, who afked my opinion.and advice for his children, was a means of intro- _ ducing it into a part of the country where it had never been tried, While many were difpofed to come into it, there were not wanting fome, as in all {uch cafes, to oppofe it; tho’, in a pretty large trial of it, at the time, it had fucceeded to the joy and fatisfaGtion of all who wifhed well to it, Amongft other objections, one Vo... Il. i Se was * February 5. 1756, 434 ESSAYS anp OBSERVATIONS was more pofitively infifted on; which, indeed, were it as well founded as it is {pecious, would effectually put to filence the warmeft advocates for inoculation, and overturn altogether the practice. A proper anfwer was made to it; and per- haps I fhould have thqught no more of it, had I not been informed fome time af- ter, that, ina fociety of ingenious gen- tlemen, who made matters of this kind the fubjects of their debates and inquiry, the fame objection was taken notice of, and feemed to make an impreflion. Pains were taken to undeceive them alfo. — | THE objection, to give it in the words ed my friend’s letter, is this : “The fmall- “pox, in the ordinary way, is defigned es hi nature as a drain toclear tlie confti- ‘ rution of fome grofs humours, . which, if not carried off in this way, would ‘< bring on other dangerous difeafes, and _ “ for moft part end in death, before per- * fons arrive at middle age. Now, fay * the objectors, the fuppuration where ‘§ the fmall-pox is inoculated, is fo incon- “ fiderable, that it cannot be, fuppofed. ** fufficient ~~? PHYSICAL 4nd LITERARY. 435 © fafficient to clear the body of thofe hu- “mours which are the parent of other “deftructive diftempers. Befides, fay “they, this theory is juftified by facts *“and experience. Upon inquiry, it is “ found, that in thofe places where ino- © “ culation has moft prevailed, particular: “‘Wiyvin and about Dumfries, there are as ‘many that die in childhood, and before “* they arrive at the age of twenty, as for- “‘ merly, even including thofe who are cut ** off by the fmall-pox. If this is the café, “then inoculation is to no purpofe.” I fhall not trouble you with what occurred to me in an{wer to this objection. I great- ly fufpect the foundnefs of the principle on which itis built, and have ventured to deny the truth of the fact; How tri- fling foever you may think the objection, yet, as there is great ftrefs laid upon jit, - and’ by perfonsof rank, I thought it might not be improper to apprife you of it. ‘Thus far my friend, An objection fo plaufibly formed, and with fuch particular application, feems to affect, more than any thing I have feen advanced, — 436 ESSAYS anp OBSERVATIONS ~ advanced, at once inoculation itfelf, and ' indirectly all who, from a ferious per- fuafion of its ufefulnefs, have fhewn them- felves induftrious to promoté it. To en- courage and recommend a praétice more hurtful in its confequences, than the im- mediate good of it can be of fervice, which could not efcape the obfervation of every one, fuppofes want of attention at leaft, or fomething worfe. Yet, not fo much to obviate a reflection of this kind, becaufe I believe undefigned, but for a more im- portant reafon, have f thought it demand- ed a public animadverfion. Iw order:to fatisfy mfelf fully, and o- thers, I have not trufted wholly to my. own opinion ; but converfed with all who have been long and principally concerned in inoculating, thro’ an extenfive coun- try: And we can affirm, that, of the ino- culated, few are dead. ‘Twocor three of a hundred arethe utmoft we can recollect: Bur, fuppofing them more, it is far thort’ of the number that-in ordinary cireum- {tances die before twenty.. Nor are we miftaken, do we think, when we fay, that they PHYSICAL ann LITERARY. 437 they are uncommonly heakhy; which the {mall proportion that are dead will readily fuggeft to every one. Itis impof= fible.to-be very, exact ; but it is fafficiently evident to-us, that the ftate of the inocu- lated is much the reverfe of what is ob- (jected. this is true every where, as here it. certainly has been hitherto, we are led to a very material difcovery ; and that which was intended as an unan- fwerable objection,..by giving occafion to a pretty. careful inquiry, has accidentally. furnifhed a new argument in favour of inoculation, and a further proof of the ‘great benefit of it. Long ufe has fhewn it to be immediately a real fecurity again{t the prevailing malignity of a very mortal diitemper ; and the prefent inftance af- fords a {trong prefumption that it is, in tts confequences, no lefs a prefervative from many difeafes incident toa period of life the moft fatal to mankind. As to the theory in the objection, it is more philofophical perhaps to argue thus : The fever of the {mall pox, communica- ted in the infant-ftate, not only deftroys or 438 ESSAYS Any OBSERVATIONS - or expells the latent feeds of difeafes, be foye they are, by time and accidents, \per- fected and put into action, but caufes fuch an alteration of the humours as'may make them lefs fufceptible of any morbid impreflions : And the veffels being fo foon accuftomed, before they become rigid, to certain motions and extenfions, the body is rendered ever after: more paflive to the impulfes of any fubfequent diftemper ; which therefore will be attended with lefs danger. This is agreeable to experience; for one who has fuffered ‘an acute illnefs will bear ficknefs better than another who never liad the diftemper, and belefs over= come by it. . From fuch reafoning it will feem to follow, that the fooner inoculation can be performed with fafety, the greater will _ be the advantage. I cannot affert, that to this is owing the more than ordinary healthfulnefs of the inoculated with us, and that fo few of them are dead: But if nothing. forbid, I always advife it, the child yet unwearfed; and with me it has always, happily and pleafantly fucceeded. Though PHYSICAL ann LITERARY. 439 Though many have been inoculated be- fore the fixth month, I chufe to delay#it~ till this time, or any convenient time after, unlefs the fubject is big and ftrong. Then, befides the greater pliancy, or kindly yielding of the folids, the blood has not, from the ufe of animal food, acquired an inflammatory difpofition, and the hu- mours a vicious taint. The firft paflages are not, as at a more advanced age, dif- ordered by worms or other foulneffes, A formal preparation, the juices being “all fweet and found, is very little necef- fary: And the continual dread and dan- ger of the natural infection is early re-_ ‘ moved; a matter, in this cafe, both for _ parents and children, not leaft to be con- fidered. Teething, I know, is made the - great objection here; but from this I have met with fo little difficulty, that I make no fcruple, except in a few circumftan- ces, which may be ealily difcovered and avoided. Pin 7! 440 ESSAYS Any OBSERVATIONS ArT. XXXAl. A Propofal of anew Method of curing ob= firuéted Menfes; by Dr ARCHIBALD Hami.iton Phyfician in Edinburgh *. 18 a converfation I had fome time ago with my friend Dr, Hunter, now Phy- fician in Beverly, concerning the cure of « , fome particular difeafes, I remember he — propofed a method of removing obftruc- tions of the men/trua by a mechanical compreffion of the external iliacs. I thought, from the anatomical ftructure of the parts, the propofal pretty reafona- ble in fome cafes; and refolved to. put it into practice, the firft favourable cafe that occurred to me. About fix months ago, I was fent for to vifit a girl betwixt nineteen and twenty years of age, who had been obftructed for near feven months, occafioned by fuddenly expofing herfelf ta % May 1. 1755¢ ‘ PHYSICAL ann LITERARY. 441 to cold, during the time fhe was menftru- ating. From the firft appearance of her catamenta, to the time of their ftoppage, fhe had enjoyed a very good ftate of health. She had confulted no regular praCtition- er; but had taken a few things, without any relief, that fome of her female ac- quaintance had defired her. Her com- plexion was a little pale and wan. Her _ appetite and digeftion bad, with erudta- tions, and fometimes fwelling of her fto- mach. She had now and then fickiih and fqueamifh fits, with inclination to vomit. Her pulfe was flow and languid, swith a great laffitude and inactivity of body, not having a defire to take her u~- faal exercife. On inquiry, I found fhe never had any pulmonic diforder, nor at prefent any complaint or uneafinefs of her breaft. She had alfo no pain or {welling about the pudenda. It now wanted about twelve days of the ufual time of the ap- : proach of her menjfes. I defired her to re- ceive the fteam of warm water, every night at bed-time, upon the pudenda, in order to relax thefe parts, fo that the Vou. I. Kkk blood 442 ESSAYS anp OBSER VATIONS blood might more eafily flow that way, Iordered her alfo ten days after, an alo- etic purgative, to clean the prime vie, that the blood might find lefs refiftance in its courfe when determined to the uterus. Next day, after fhe had taken the purge, T went and faw her, and found it had o- perated four times. About feven o’clock that evening, I applied a comprefs and bandage to the crural arteries, at the fame place where they put the tourniquet in amputations of the thigh, but not fo tight as to endanger a mortification of the inferior extremities, At the fame time, I defired her to fit above the fteam of warm water. I intended to have ftaid © with her, to obferve the gradual effects of | the bandage; but unluckily wasfent forin | a hurry to fee another patient. I left | {trict orders with a woman, who was with — her, to untie the bandage, in. cafe fhe © complained of any difficulty of breathing, On my return, about twenty, minutes af- — ter, I found her in the fame fituation | | left: her. Her pulfe indeed beat about | fix ftrokes in the minute fafter than be- forg - pHYSTCATL ann LITERARY. 443 fore the application of the bandage. At the expiration of half an hour, fhe began ’ to feel a fenfe of weight and fullnefs in -~ the uterine region, and turned fickifh. As her head and breaft continued pretty eafy, I begged of her to allow the ban- dage to continue fomewhat, longer, and gave her a fpoonful of a cordial-julep. An hour and a half after the firft appli- cation of the bandage, we found a vifible appearanicé of the return of her menfes, by applying a piece of foft clean linen to the parts, which, when removed, was {tained in feveral places. I flacked the bandage, as her legs were fomewhat benumb’d; but was unwilling to remove it altogether, till the difcharge fhould continue to flow for fome time. I put her to bed; and, on my return next morning, found her {till menftruating and eafy. I now removed the rollers,. The men/es continued to flow for three days, and returned regularly next period. Since that time, I under fiand, fhe has been very healthy. ARTs 444 ESSAYS anp OBSERVATIONS ArT. XXXIT, 4 Dropfy unexpectedly cured; by Tuomas: LivincsTon Phyjfician at Aberdeen *. . AP thofe who are much converfant ia the a . practice of phyfic and furgery may ‘be frequently difappointed in their fa- vourable prognoftics, fo they may fome- times be agreeably furprifed with the unexpected recovery of patients, whofe fymptoms they had pronounced mortal, An inftance of which, I prefume, will plainly appear in the hiftory of the follove~ ing cafe. ; Rosert Duncan, aged about 20 years,, a labouring fervant in the country, was brought to the Infirmary of Aberdeen June 19. 1753- He was fo weak, that he could give no account of the origin or progrefs of his difeafe; but thofe who attended him from the country inform- ed me, that, during the preceeding win= ter,. * February 6. 755+ PHYSICAL ano LITERARY. 445 ter, he had been much expofed to cold ; after which, his belly and lower extremi- ties began to fwell, he contracted an ins tenfe thirft with a paucity of urine, loft his ftrength and appetite; and the above ’ fymptoms continued to increafe, without any means being tried for his recovery. _ He was admitted into the Infirmary, not with any profpect of relieving his com- plaints; but, as he was deftitute, and wanted the commen neceflaries of life, he was ordered a place on purpofe to let him die in peace. He had a very large afcites, with an univerfal anafarca, parti- ularly of his thighs and legs, which feemed ready to burft, and gangrenous~ like veficles appeared upon feveral parts of his legs and feet. His _/crotum was di- ftended to fuch an enormous fize, that I could hardly at firft dittinguifh the penis ; and the above fymptoms were attended with a dy/para, and fach a defect of vis vite, that I could not difcover a pulfa- : tion in any of the arteries, and was only fenfible of a tremulous fort of motion about his heart. In this difmal fituation, a 446 ESSAYS and OBSERVATIONS: I gave him over to the care of a nurfe; ordered him a little warm wine and wa- ter, and expected to hear of his death next morning; but I was difappointed. June 20. His countenance appeared rather more lively ; he {poke a little with great difficulty; andI could difcover a ve- ry languid pulfation at his wrifts. I fnip- ped the veficles on his feet and legs, and made feveral fmall punctures witha com- mon lancet into, the moft depending parts of the /crotum: There was a confiderable difcharge of a bloody-coloured /erum from the veficles; but the difcharge from the punctures in the /crotum was clear and pellucid. Iordered warm ftupes wrung out of ahot aromatic decoction to be al- ternately applied to his /crotum and legs ; and he got a large fpoonful of the julap. diuret. Pharmacop. Paup. every two hours, with wine and water for his ordinary drink. 21. THERE was a confiderable quantity of water difcharged by the punc- tures zn /croto, the fize of which was fen- fibly ‘leflened ; but there came nothing from i PHYSICAL anp LITERARY. 447 from the veficles.on his legs and feet.,, I made feveral {mall punctures into, the calves of his legs, and continued the fotus and julep: His other sib much. as yefterday. | ——22, THERE was an incredible quan- tity of water evacuated from the punc- tures in his legs and /erotum: He had more ftrength, {poke more diftindlly, and his breathing eafier. Ordered his medi- cines to be continued as above. 23. The difcharge from the punc- tures continued as yefterday; the {welling - of his trunk and extremities was confide- _ zably diminifhed ; his breathing ‘ eafier, and pulfe more diftin@: He had fome ap- petite: The fame medicines were conti -nued, From the 23d to the — the difcharge continued, but turned daily lefs ; and on the 27th was intirely ftopped; his head, thorax, arms, /crotum, thighs, and legs, quite free of {welling ; but his belly {till confiderably diftended, tho’ not near fo Jarge as when he was admitted. He was reduced to the loweft ebb of weaknefs, and had 448 ESSAYS anp OBSERVATIONS had a light nourifhing reftorative diet or- dered him. | From June 27. to July 4. there was no very fenfible change on the fize of his belly: Heufed the cerevifia diuretica of the Pharmacop, Paup. was daily growing ftronger, and took {mall dofes of rhubarb and pulv, fcillitic. at fuch intervals as his ftomach could bear them. From Fuly 4. to Fuly 20. he continued the ufe of the cerevifia diuretica, and took three of the pilus, mercur, laxant, every o- ther night ; thefe gave him two or three loofe watery {tools in the morning, which he bore very well: And, from the time he began to ufe them, he pafled his urine in much greater quantity than formerly. guly 25. He was difmiffed the Infir- mary quite cured, and continued {trong and healthy, on the 22d of Oftober 1754, when this was wrote. ARTe . PHYSICAL ann LITERARY. 449 Art. XXXII, Hiflory of a Patient affeded with Periodic Nephritic €onvulfions ; by CORNWELL _ TatHwex., M.D. Phyfician at Stam ford*. Fair healthy looking girl, ofa full habit of body, aged 17, about the beginning of laft July, without any warn- ing, fell into violent and gerieral con- vulfions, and a ftrong delirium, which lafted about fix hours, then ended in fleep, and left a giddinefs behind them for fome time. As foon as the fit was off, fhe was blooded and bliftered by her apothecary, _and feemed to have got well. In about three weeks after, a diarrhea came on, and ‘fhe BEBE 4. a little of a flight - pain in her back and bowels ; and, ina ‘month from the firft feizure, being a few days. before the full mcon, fhe had a fe- Vou. Il. LIl cond # May 1. 1755. ‘450 ESSAYS anp OBSERVATIONS cond fit about as long as the former, which ended in the fame manner. Soon after this fit, her tongue was of a dufky colour, her pulfe quick, and her urine pale and {mall in quantity. The blooding | was repeated, a foetid plaifter applied to ‘the abdomen, and a few ftools procured by pills of foap and aloes; after which there appeared a white fediment in the urine. : HALF an ounce of valerian was got down in faline draughts every day; in a week, a feton was put into her neck, and the week after fhe began to go into the cold ‘bath every morning. Some bark and bitters, with a light chalybeate wa- ter, were added to the valerian, and the opening pills were ufed occafionally. Axsour the latcer end of Auguft, after fe- veral ftools, a giddinefs and fleepinefs came on with a flight delirium, but with- out any convulfions. Wuen fhe was waked out of this fleep, » fhe complained greatly of a pain in her ' ftomach and back; which neither V. 8. the /emicupium, nor tinétura thebaica,would relieve — PHYSICAL anp LITERARY. 451 - relieve for any long time. ' The next day, on repeating the /emicupium, fhe vomited, ’ and then firft complained of a dyfury: 1 now gave her fome pills of foap and jal. martis. On’ the evening after, the pain returning in her back and os pubis, fhe was again put into the femicupium, and after-~ wards voided a confiderable quantity of pale urine, which at firft feemed to con- tain fome rags, but foon hung with a ‘white cloud, and let fall a whitifh pow- der. The pain going off next day, the urine was more faturated, and, as the fe micupium foon made her faint and fick, it was omitted, ALL this while the catamenia, which had firft appeared about two. years before, were entirely regular, and generally came on at their ufual. period about a week af- ter each fit. She now continued the ufe of the pills, with German Spaw-water and the cold bath. The feton was dried “up about the end of September, and fhe had only a flight return of pain in No- vember, .which was carried off by fo- menting the abdomen. I recommended lime 452 ESSAYS anp OBSERVATIONS lime-water with her pills; but fhe has continued perfectly well ever fince, without taking any thing. | | 1. WERE not thefe a kind of periodi- cal nephritic convulfions? I have known nephritic fymptoms particularly trouble- fome to other female patients about the time of menftruation ; ; which feems to be owing to the greater turgefcence of the neighbouring parts of the uterus at that period, by which the urinary veflels - become at the fame time fuller and more ftraitened. 2. Ir is remarkable thefe convulfions were {carce accompanied with any fymp- tom of the nephritic kind till the pain and dy fury Seat appeared fo, after the third fit, which the intermediate means feem to have contributed to make much flighter than the two former. Tus will lead us, efpecially in nervous cafes, which are often found to be fympa- thic, to be more particularly attentive to even the fmaller fymptoms, which are fometimes a better clue to guide us to the origin of the diforder, than thofe violent accidents ¢ PHYSICAL anp LITERARY. 453 accidents that are more apt to engrofs our attention. 8. THE diarrhea preceeding the fits, was probably only an effect of the irri- tation of the urinary paflages by confent. - of parts; fince the keeping of her open afterwards feemed of fervice, inftead of bringing on a relapfe. Whence I fhall only beg leave to obferve, how neceflary it is in practice to diftinguifh fymptoms that only precede others from thofe that produce others: In fhort, of what confe- quence it is, not to miftake that for a caufe which is only prior in point of time; e- fpecially as this, I fear, is too common a cafe, and often requires our utmoft care, in obferving the juvantia and /edentia, to avoid it, — | 454, ESSAYS anp OBSERVATIONS , ART. XXXIV. Hifiory of a Fever after Child-bearing ; by the fame*. A Delicate young woman (who, for two years before fhe was married, had, from a fright, been tubje-t, at times, to a kind of hyfteric epilepfy, efpecially at the approach of the catamenia) about four days after being fafely delivered of her firft child, had a milk-fever, which came on attended with languor, catch- ings, and reftlefinefs. She was carefully treated with mild diaphoretic and anti- f{pamodic remedies both internally and externally. A miliary eruption came out upon her arms; the Jochia flowed regu- larly, and the belly was kept moderately open: Yet fhe got no reft, was delirious, her tongue dry and black, and her pulfe quick and fmall, A blifter was applied over # May 1. 1755+ | ; PHYSICAL anv LITERARY. 455 over her head, which, without any“pain or ftrangury, produced a very large dif- charge. The next day, being the ninth from the beginning of the fever, ‘fhe ‘got fome fleep, and became more fenfi- ble: A gentle perfpiration was promoted . by jp. mindereri im diluents, and hot > ‘bricks applied occafionally to her feet. The pulfe was more quiet and regular, the tongue moifter, and a white cloud fubfided in the urine. On the 12th day, thefe flattering fymptoms vanifhed the delirium rofe higher than ever: She was perpetually comatous or convulfed ; breathed with difficulty ; often rubbed. her hands together, and picked the bed- cloaths; and the pulfe could fcarce be’ felt. A ftimulant clyfter was not retain- ed; veficatories would not rife upon her ; yet fhe was excoriated with involuntary urine. In this deplorable extremity, fina- pifms raifed a blifter on her feet, and a large flux was promoted from them by an emollient cataplafm, to which wz- guent, ad veficator, was. added pro-re nata. As 456 ESSAYS ann OBSERVATIONS As no medicine could be got down by the mouth, pulv. cort. Peruv. unc. {. in decodt. capit: papav. alb; une. vi. was thrown up by way of clyfter, and repeat- ed twice the next day with fix drams each, Thefe three, containing in all two ounces of bark, were retained for a week ; in which time the bad fymptoms went off by degrees, and fhe took freely. of both whey and other nourifhment- Her feet ftill continued running, and were drefled with unguent. alb. Three more of the clyfters with /crup. vi. each were given in as many days. She now refted well, and her pulfe was become re- gular, was much emaciated, and fo weak fhe could fcarce be raifed without bring- ing on fome hyfteric fymptoms. By de- grees. fhe began to recover her ftrength: The clyfters were repeated now and then, increafing the quantity of bark in each to unc. i. Her appetite returned: In a fort- night fhe could be got out of bed: In a- nother week, inftead of the clyfters, the took extr. cort. Peruv. fcrup. ii. twice a= day, occafionally interpofing fome rhi- barb; PHYSICAL ano LITERARY. 457 barb; in about ten days more fhe was got pretty well. The next month fhe had. a flight fit of the kind fhe had been ufed to before marriage; but, by the help of fome volatile foetid tincture in bitter wine, the got rid of thefe, and has continued free from them ever fince, tho’ fhe has had _ feveral more children. Von ON or AR 458 ESSAYS AND OBSERVATIONS Art. XXXV. Hiftory of a Fever with bad Symptoms ; 3 by ~~ the fame *. | Middle aged man, generally employ- ed in a malt-kiln, about. the latter end of July 1749, fome time after having fatigued himfelf, and got into a quarrel in a crowd at a public diverfion, was feized with a fever; in the beginning of which he was blooded, then had a vomit, and af- terwards a great variety of diaphoretic medicines were tried with him. He was kept {weating, and feveral crops of erup- tions fucceeded each other, without any relief. Blifters were applied in feveral places, yet ftill a delirium and vigilie con- tinued. Mufk, and even the bark in fub- {tance, was given him; but all without any effect for above a month. The apo- thecary who attended him in the mean time * May 111755. ". =. PHYSICAL anp LITERARY. 459 time often urged the neceflity of further advice; but his friends would. not con- fent to it, till, at laft, Iwas called in. I found him in continual tremors and /ué- fultus tendinum; his pulfe was fmall and obfcure, his tongue foul and dufky; and his urine had only a flight cloud in it, . His eyes were fo dim, he could fcarce di- ftinguifh the perfons about him; and it was very difficult to make him hear, e- {pecially on the right fide. He.was reit- lefs, languid, and delirious; often groan- ed and fighed, and was flill bathed in a’ perpetual fweat. Some red {pots appear- ed upon his breaft, and many purple and livid ones on his back. As he had been coftive for fome days, firft a ftool or two was procured by a warm clyfter, fome antimonial drops © (which I have often experienced to deferve very juftly the encomiums Dr Huxham* has beftowed upon them as an excellent _ deobftruent) were given now and then in red wine. Elixir of vitriol and volatile tincture — * Obf. de aere, vol. i. p. 141. 4$0 ESSAYS ann OBSERVATIONS tincture of bark were adminiftred, firtk in faline draughts, and afterwards in tinc- ture ofrofes. Within three days, his fweats were gradually checked, the red papule came to a kindly fuppuration, the livid {pots difappeared, the tremors, Subjultus, and delirium went off. An abfcefs (which I had foretold from the particular deaf- nefs on that fide) broke. ia his right ear, and, together with a blifter behind it, was Kept conftantly running. Ina day or two more, all the bad fymptoms were vanithed ; his pulfe grew fuller and ftrong- er, a good fediment appeared in his urine, © and his tongue regained its natural co- lour. The volatile tincture was foon changed for a much larger proportion of the REOe tincture of bark. In a week, not only his fenfes returned, but an ap- petite; and he began to recover his ftrength, A ftrdng decoction of bark was added to. the laft mentioned tinture, by which,with a few dofes of rhubarb interpofed occafi- onally, the cure was compleated. ART. PHYSICAL anv LITERARY. 464 ART. XXXVI. Adcounts of extraordinary Mont of the Was zers in feveral places of North Britain, and of a Shock of an Earthquake felt at Dun- barton. ey great defign of the inftitution of this Society being faithfully to re- cord every remarkable phanomenon in - mature that occurs, it has been thought proper to infert the following accounts of the effects of the late earthquakes, as they have been obferved in our diftrict of North Britain ; nor do we regrete, that they are “not more fingular or interefting in their kind. When all the facts and circum= {tances fhall be collected by the united la- bours of the learned in different places, there is reafon to expect, they may furnifh materials for a more compleat and accu- rate hiftory, than hath been tranfmitted of 462 ESSAYS anp OBSERVATIONS of any like event that ever happened in any preceeding age of the world. THAT a tremor, which is hardly to be felt at land, or which may altogether e- {cape notice there, may be very percepti- ble-on the waters, will eafily be believed; nor is it more incredible, that a {mall con- cuffion given to a great body of water will produce a very remarkable agitation in the narrow creeks and fhallows. And it is obfervable, that thefe commotions were moft violent in the deepeft lakes, particularly in Loch-nefs; the extraordi- nary depth of which hath been fometimes affigned as a reafon for its never freezing, the fevereft winters not being able to re- duce it to the coldnefs of ice. 1. Letter ¢ PHYSICAL anv LITERARY. 463 1. Letter from Mr RopeERT GARDINER Commiffary to the Army it North Britain, to Dr Joun STEVENSON Phyfician in E+ dinburgh, giving an Account of the Agitati- on of the Waters of Loch-nefs on the xf of November 1755, when the City of Lisbon qwas defiroyed by an Earthquake. S1R, EpinsurGH, December 22. 17554 3 i Have your favour of the 20th, and, “ & in compliance with your requeft, I “ give you the following reply to your Nvquieries, [ arrived at Fort Auguftus “ from Fort William on the 31ft of Oéto- “ber laft. .Next morning about ten, I “ walked abroad, when the Barrack Ma- “ fter and feveral others came and ac- “ quainted me, that they had feen a very “extraordinary agitation in the waters of “Toch-nefs. I refufed giving credit to “their ftory, and a little afterwards re- “ turned to the Fort. “ ABouUT 464 ESSAYS anv OBSERVATIONS “ AzouT eleven, my clerk and the “brewer at that place came and ac= “ quainted me, that a more extraordi- “nary agitation than the former had *‘ happened, and they apprehended fome ** danger to our brewery, which is fitu-| _ * ated where the river Oich difcharges it- ; “ felf into the lake. I walked then to | “that place; but, before my arrival, the “water had returned to its ufual chan- *‘ nel. I faw very clearly the marks on “‘ the banks, to which it had flowed. The “ banks were quite wet, and a ftrip of “leaves of trees and twigs, &c. left on “them. I inquired then into this affair, ‘and the account the fpeCtators gave, “were: That they obferved the river * Oich, which runs from weft into the “ head of the lake, fwell very much, and’ “ flow up the river from the lake with a “ pretty high wave, about 2 or 3 fees “ higher than the ordinary furface, with ‘4 pretty quick motion againft the wind, ‘and a rapid itream about 200 yards up “ the river; then broke on a fhallow, and PHYSICAL anp LITERARY. 465 “ and flowed about 3 or 4 feet upon the “ banks on, the. north-fide. of, the rivery “ and returned again gently to the lake: iif That it continued ebbing and flowing ‘in that manner, for about an hour; « without any .waves fo. remarkable ag « the firft, till about eleven © ‘clock, when 4 a wave higher than any of the reft came “up the river; and, to the great, fur- “| prize of all the {pectators,. broke with k fo much force on the low ground on he north fide of the river, as.to run upon * the grafs 30 feet from. the river's, bank. “ LiEUTENANT Smith of the artillery, “ Mr Gwyn, fon. of Captain Gwyn of “ the Loch-nefs-galley, Mr Lumfden bar- * rack-mafter at Fort-Auguftus, Mr For- »* bes barrack=mafter at Bernera, Thomas “©Robertfon brewer > at 'Fort-Aueuftus, ‘cand George Bayne my clerk, and feve- “ ral others, were the fpectators of:this ) “extroardinary phenomenon ; fome of “them faw the whole progrefs of it, o~ ‘ thers only a part. | - Loch-nefg is about 20 miles in Yength, & and from 1 to 1+ miles broad, and bears Vou.l. Nan ol frdm a ea een \ 466 ESSAYS anp OBSERVATIONS * from fouth-weft to north-eaft ®, There © was no extraordinary muddinefs in the ~ ‘water, though it did not appear quite fo “clear as ufual, The morning was cold “and gloomy. and a pretty brifk’ gale “ blowed from weit fouth-weft. The ri- ' “ver Oich Hes on the north fide of the * Fort, and on the fouth fide, runs the ri- “ver Tarff from weft fouth-weft, and “ difcharges itfelf into the head of the “ Jake, which was obferved to be quite a- ** gitated at the fame time and manner a, “the other. But there was no fhaking or “ tremor felt upon the land.” | 2. Letter from Lieutenant tshac BARRE'‘Tto Davip Ross, E/q; Sheriff-Depute of the Shire of Banff, concerning the Motion of the Waters of Loch-nefs, November ‘1. 175S- STI R,. FortT-AUGuUSTUS, January 15.1756. ~ i Have been here eight days, and, by | “" the ftricteft inquiries, have at. laft ** picked ® Itlies betweenthe s7thand 58th deg. of northern latitude, |f PHYSICAL anp LITERARY, 467 picked up the following account. | Per- “ haps the whole may be of little confe= | ** quence; or, if it is, may come too late “to be of any ufe to the gentlemen who ** defired it. “ AzsouT half an hour after ten in the “‘ morning of the 1{t of November, Loch- “ néfs was obferved to rife in a moft ex- ‘‘ traordinary manner at Fort Auguftus; “ it rufhed with great rapidity above two * hundred yards up the river Oich, which « runs into the Loch near the Fort; it laft- “* ed by the beft accounts about three mi- “ nutes: The people of the country, un- “ accuftomed to {uch an appearance, ima- “ gined at firft it was caufed by a great “number of felks rufhing up the Loch, “There was no fhock of any fort felt on fhore, and the air was remarkably clear, “ and avery mild day, the wind then ‘be- * ing wefterly (and of courfe againft the ** ftream.) “I could get no account of any perfon’s “being in a boat on the Loch at the “time; but what follows has an air of “truth; becaufe the relater is reckoned * an 468 ESSAYS anp OBSERVATIONS “an honeft man and of great veracity ; *‘ and befides, had told the fame circum- “ ftances frequently before he could’ fu- ** fpect that this extraordinary phaenomenon A iia be the fubject of a ferious inqui- Eye * He went with a boat for weds from = Glen-Morrifon to the Old General’s Hut ‘on the oppofite fide; and, about the “time abovementioned, his boat being “near loaded, as he was coming to it *¢ from the hill, he obferved a fudden and “violent wave coming, which drove her « feveral yards on the beach, and return- “ ing, drew her back into the loch ; a fe- cond came with rather more violence, . Wate pretty near the fame effet; a third ‘came with a much more extraordinary fe east than either of the former, and “with more furprifing effects ; it drove “ the boat further on the beach, took the *‘ wood intirely out of her, broke off the L. rudder, and left her afhore full of wa- “ter. At this time there was a gentle * breeze from the weft, and a mild ferene Gs fy.” “THIS PHYSICAL ann LITERARY, 469: ~*©'TuH3s account was given by James *Fergufon a miller at Folt-Soy near §§ Glen-Morrifon, and alfo attefted by his ** companion James Macdonald. “ Tey affert, that the water, in their “ opinion, upon examining the ground “ afterwards, mutt have rifen at leaft three “ feet perpendicular ; and the time of the “whole agitation was about three mi- * nutes.” 3. Letter from Mr Joun ROBERTSON Zo James SMoLLET of Bonhill, E/g; one . of the Commiffaries of Edinburgh, con- cerning the Agitation of the Waters of Loch-lomond, November 1. 1755 *. SIR, Rospok, December 17.175 56 is A’ I have been from home for a fort~ ~ *“ night paft, your’s came to hand on- ly yefterday, or would have anfwered it * fooner. The tafk you impofe upon me, Vise * Lochlomond lies upwards of fifty Englifh miles weft of Edinburgh, about the 56th degree of north latitude. —-_ 47°. ESSAYS AND OBSERVATIONS *< viz. the giving an account of the com- * motion that was obferved in the waters * of Loch-lomond on the 1ft of November, * is already executed by Mr Macfarlane *¢ the minifter of Arrochar, according to “the beft accounts he could get of it ** from the fpectators; as I was not an * eye-witnefs of this uncommon pheno= *¢ senon, and as the account he gives of itis ® perfectly agreeable to the relations of all * thofe who faw it, I will write you an ex~ * act copy of his relation, which, I think, is * as fulland diftinc an account as can be * got of it. “On the 1ft day of November laft, * Toch-lomond, all of a fudden, and with- * out any guft of wind, rofe againtt its “ banks with great rapidity, and imme- ** diately retired; and in five minutes time * fubfided, till it was as low in appear- *‘ ance as any body then prefent had ever * feen it in time of the greateft fummer * drought, and then it inftantly returned * toward the fhore, and, in five minutes * time, rofe as high as it was before ; and * the agitation continued at this rate from §¢ half PHYSICAL anv LITERARY. 47 *¢ half an hour paft nine forenoon till fif- * teen minutes paft ten, taking five mi- * nutes to rife and as many to fubfides “* and, from fifteen minutes after ten, till “ eleven, every rife came fomewhat fhort “in height of the immediately preceed- “ing rife, taking five minutes to flow, “ and five to ebb, until the water fettled “6 as it was before the agitation. After “ the agitation was over, the height to “ which the water had rofe was meafured, ** and found to be 2’ feet 4 imches perpen- “S-dieular..| Loch+long: and Loch-keatrin bt-were agitated on the fame day, and a- -* bout thedame time ; but the phenomenon “was not fo minutely obferved: asuthat any exa& account can ‘be got of its “2186 "Pea sirelation of Mr Macfarlane’s of the phenomenon, contains mit every °® thing remarkable I have as yet heard ie concerning ce \ 4. Letter 472 ESSAYS anv OBSERVATIONS 4. Letter from Mr Marx M‘CaLium 20 Grorce CLERK, E/q3 concerning. an unw ufual Motion of the Waters of the Frith of .' Forth at Queensferry, feven miles weft of Edinburgh, on the 1/2 of November 17556 | vs SULRe se O the beft of my rememibrarice, ori a Saturday the firft of November, 'a- * bout ten 6’clock before noon, being then on the pier’at Queensferry, I obferved ** the water torife very fuddenly, and re- ‘turn again with the fame velocity about “a foot or eighteen inches perpendicular, ‘as near as I ean remember; the*barks -* and boats then afloat ran forwards and “‘ backwards with great rapidity, and this “ continued for the fpace-of three or four “ minutes ; but, after the fecond or third ‘“‘ rufh of the water, it gradually abated. ** There was no wind at the time the wa= * ters were agitated as above.” 5. An o os PHYSICAL anv LITERARY. 473 - ‘ An Account of an unufial Motion in the Waters of Clofeburn-Loch ix Dumfries- Shire, on Sunday 1h: 1/? of February t é& 6é és 6s 1756, in a Letter to GEORGE CLERK, B/qs | ae i PS SIR, Ciiosevurn, February 4. 1955 BouT aquarter before nine onSun- . day morning, we were alarmed “ with on unufual motion in the waters © of Gieiiateeloak: The firft thing: that appeared to mein this wonderful icene; was a ftrong convulfion and agitation of the waters from the weft fide towards the middle, where they toffed and wheel- ed.in a terrible manner. From thence proceeded two large currents, or more ** properly rivers, which ran with a {wift- nefs and rapidity beyond all defeription “ quite contrary ways; one from the mid= Vou. Ih. Ooo er: | * It may not be amifs to obferve, that, on thé 1ft of February 1756, according to advices from abroad, a confiderable earthquake happened at Oporto in Portus ‘gal. 474 ESSAYS anv OBSERVATIONS — ** dle to the fouth-eaft, and the other to *¢ the north-eaft points of the Joch. ‘Fhere “they were ftopped fhort, as the banks are pretty high, and obliged to turn; ‘ which occafioned a prodigious tumb- ling and agitation at both ends of this “* body of water. ‘There was likeways a “© current which rofé fometimes confide- rably above the furface, near the weft ** fide, that I frequently obierved running ‘with great velocity a hundred yards to the fouthward, and returning in aw a ‘* ment with as great velocity thesother $6 way. » What I obferved, in the next ¥6 place, was the tofling of the waters in “* the ponds, which were more or lefs ** moved as the agitation of the loch came cn n near this fide, or kept at a greater di- *‘ftance from it. But, as it is beyond my capacity to give a particular des {cription of all that happened-on this occafion, I fhall conclude with telling you, that the agitations and currents above-mentioned continued, without ‘intermiffion, for at leaft three hours : and an half, or four hours, when they “ began a“ ”“ “~ wn“ a -~ PHYSICAL anv LITERARY. 475 bs began to abate a little in their violence, ** though the toflings and currents were © nor quite over at funfet. I had almoft forgot to tell you, that this phenomenon ** was renewed on Monday morning a lit- « tle before nine, and lafted for an hour nt and an half; but the motion of the wa- £* ters, dc. were not fo violent as the day ** before. What is very remarkable, there ** was not the leaft gale of wind on Sun- §* day till one o’clock, which helped us ‘* not a little in our obfervations,” 6. Letter from Mr PANTON relating to the | Earthquake felt at Dunbarton. | SIR, | DUNBARTON, January 1]. 1756+ N anfwer to your’s relative to the A earthquake here, there happened but . ** one fhock, and that very moderate, be- ‘© fore one of the clock December 31ft A755 5 it continued for a very {mall r ice of time. _ It agitated fome people ‘in bed very perceptibly, and was felt sé # by Mrs Weir and ty Ws others, who . _§ were wh | ye ge TP saat 7 i ke AY ~—Te eos he 476, ESSAYS AND Re i. ~ot ‘* were not gone toed. It had. eg 2 ‘* effect upon fone birds in cages -“ fowls : It fo alarmed. both, as to bs ‘the former flutter prodigioufly, and *¢ the latter to croak ina frightful man= — “© ner: It fhook the board out of one a cage, and fpilr the water in the glafs thereof. It was equally felt by thofe ¢« who lwed i in ground-ftories, as by thofe in fecond and third ftories, ‘There ** were fome fconces in Mrs Colquhoun’s _“houfe obferved to vibrate during the “* fhock. os se more happened worth ** noticing.” _N. B, This earthquake was felt.at =) fame time in Glafgow, Greenock, and o= ther places of the neighbouring country SS a ent ee a cic