554 §> C§ v& §3 scientific Library §3 — — — aj §3 §3 §3 S' $ i> §3 §3 §3 & §3 §3 §3 & UNITED STATES PATENT OFFICE <§ ■§ t§ « « « I tg « « « «§ « <8 f I <§ 16—53001-1 . N / ■ ’ PHILOSOPHICAL RANSACTIONS. PARTI. -i A I \ . f A D 7 X. ■ r ' -c. , V * t 1 C Y A-*-' T PHILOSOP HICA L TRANSACTION S, OF THE /• ROYAL SOCIETY O F LONDON. VOL. LXXI. For the Year 1781. P A R T L ~ LONDON, SOLD BY LOCKYER DAVIS, AND PETER ELM SLY, PRINTERS TO THE ROYAL SOCIETY. MDCCLXXXI. HI C(" V \g&> [ V 1 3 3 / b advertisement. fTTl HE. Committee appointed by the Royal Society to dire& the pub*- A lication of the Thilofopbical Tranfadions, take this opportunity to acquaint the Public, that it fully appears, as well from the councibbooks. and journals of the Society, as from repeated declarations, which have been made in feveral former Tranfadions > that the printing of them was. always, from time to time,. the fingje act of the refpecHve Secretaries, till the Forty-feventh Volume : the Society, as a body, never interfiling them- felves any further in their publication,than by occafionally recommending the revival of them to fome of their Secretaries, when, from the particular oircumftances of their alfairs, the Tranfaffions had happened for any length of time to be intermitted. And this feems principally to have been done with a view to fatisfy the Public, that their ufual meetings were then continued for the improvement of knowledge, and benefit of mankind, the great ends of their firft inflitution by the Royal Charters^, and which they have ever fince fleadily purfued. But .the Society being of late years greatly inlarged, and their com* munications more numerous, it was thought advifeable, that a Committee ©f their members Ihould be appointed to reconfider the papers read be- fore them, and fele. Joh. Baptift. Beccaria, Phil. Exp. Prof Reg. Taurinenf. D. Petrus Jonas Bergius, M. D. Hijl. Nat. Prof. Stockholm. D. Thorbern Bergman, Chemice Prof UpfaJ. XX M. Joh. Baptift. Bernard, M. D\ Med. Prof Duacenf D, Daniel Bernoulli, R. Sc. A . Par. Soc. Pr , Afr . BajiL D. Ferd. FOREIGN MEMBERS. D. Ferd. Berthoud, Neocom. Helv. D. Jof. Steph. Bertier, Parif enfs. D. Carolus Bonnet, Genevenjis. D. Ignatius S. R. I. Eques a Born, D. Roger Bofcowich, Afiron. Prof Medial. D. Joh, Maur. Comes Bruhl, Or at. EleSi. Sax . ad Brit. Reg. D. Jof. Laurent. Bruni, M. D . Anat. Pr. Paur. D. G. L. le Clerc Comes de Buffo n, R.S. A. Par. S. & Hart. R. Pr. D. Mar. Ant. Leop. Caldani, Anat. Prof. Patav. D. Petrus Camper, M. D. Med. Pr. Gron . D. Marchio Dorn in. Caraccioli. D. Job. Baptift. Carbon, Prof. Med. Reg. Paurin. D. Caefar Franc. Caffini de Thury, R. S. A. Parf. & Berol. Soc «. D. 'Joh. Caffiglione, Ac. R. Sc. Berol. Soc. D. R. Caumont, M. D. Parif D. Paul Celefia, Nobil. Genoenfs. D. Jof. Bern. Marchio de Chabert, R. S. A. Parif Soc. D. Joh. Bapt. de la Chapelle, Parifienfs. D. Lud. Mar. Jof.-d’ Albert d’Ailly, Dux> de Chaulnes. D. Joh. Franc. Cigna, M. D. Paurinenfs. D. Franc. Gabr. Coyer, Parif. D. Lud. Joh. Mar. Daubenton,. M. D. A. R. S. Par..& Per. S., D. Petrus Davila,, Hifpanus .. D. A. Georgius Eekhard, Hagre Com. D. Leonardus Euler, Acad. Imp. Petrop. Soc* ■ D. Joh. Baptift, Faget, Parif erf. ©. Joh^Bapt, de Feronce, Corf. Aul. Brunf 3j>. Bened. Ferrner, Ord. de Stella Pol. Eques , R. A. Sc. Stockh. Soc » D. Samuel Fonney, Reg. Sc. Ac. Per. Sec. perp. EL Joh. Paul Grand Jean de Fouchy, R. S. Ac. Par » perp. hen. E. Paul,, FOREIGN MEMBER S. P. Paul. Frill, Prof. Math. Mediol. D. Jofeph. Gaertner, M. D. Wurt ember g. D. Car. .Hyacinth. Ant. Dux de Gallean, Princ. S, R . /» D. Job. Petr. Grofley, A. R . Irfc. Par . Soc. D. Job. Paul, de Gua de Malves, Reg. Sc. Acad. Parif. Soc. D. Oftavian. de Guafco, Abbas ; Nob. Pedemont. D. Jofeph. de Guignes, hit. Lin. Orient. Reg. Chrifl . D. H. Lud. du Hamel dii Monceau, R. S. A. Par. S. 9 D. Sam. Chriftian. Hollraannus, Philofoph. Prof, Gotting. D. Martin. Hubner, Confil. R. Danice , &c. D. Franc. Jacquier, Ord. Min. Rom. Math. Prof D. Teller Samuel Kuckhan, Jamaicenfs. D. Johannes Dux de La Foes, Lufitanus . D. Jeron. de la Lande, R. Sc. Ac. Par. & Ber, Soc . D. Joh. Philip, de Limbourg, M. D. Spadenfs. D. Ferdinandus S. R. I. Princeps Lobkowitz. D. Johannes Andreas deLuc, Genevenfs. D. Petr, de Lyonet, J. U. D. Haga Com. D. Xaverius Manetti, Prof. Med. & Bot. & Ac. Flor . Sec. D. Martin, de Mello e Caftro, Reg. Luf a Sec. & Conf D. Car. Meffier, Reg. Acad. Sc. Parif. Soc . D. Frid. Chrift. Meufchen, Ac. Imp . Nat. Cur. Soc. Hag Sec. 7 D. Cafimir FOREIGN MEMBERS. D. Cafimir Gomez Ortega, M. D. Prof. Reg, Botan, Madrlt, D. Gamillus Paderni, Rom anus. D. Petr. Simon Pallas, M. D. Hifi.Nat. Prof. Petr op. D. Martin Poczobut, Afron. Reg. Polonies. D. Petrus Poiaonier, Acad. Imp. Petr op. Soc. D. Seb. Jof. Marchio de Pombal, Luftanus. D, Jofeph Raulin, M. D. Parifienf. D. Ra ynal, Parifienf D. Sigif. Conies de Redern, Prof. Acad. Reg. Berolin* Princeps Abondio Rezzonico, Rom anus. D. Fulcus Marcbio Rinuccinus, Nob. Florentine. D.- Johannes le Roy, Ac. R. Sc. Par. Soc. D. David Van Royen? Bot. Prof Lugd . Bat. D. Georg. Ludov. le Sage, Genevenfis. D. Jof. Fr. Wicardel de Fleury, Comes de Saluce, Peder* . D. Jacob. Chrift. Schaeffer, S.T.D. Ratijbonenfs . D. Joh. de Schuvaloff, Cubicular. fuprem. Imperatr. Rujfi D. Achill. Petr. Dio. du Sejour, Acad. Reg. Par. Soc. D. LazarusSpallanzani, Hifl. Nat. Prof Paviee. D. Jacobus de Stehelin, Ac. Imp. Petrop. Soc. D. Simon Stratico, Epifcopus in Dalmatia. D.Joh. Jofeph Sue, JVI A. Parifenfs. D. S. A. D. Tiflot, M. D. Laufannenfs. D. Jof. T oaldo, Profef Aflron. Patav. D. . Jofeph. Ignat, de. Torres, M. D . . Hifpan „ D. .Abrah. Trembley, Genevenfs ... D. Ludov. Comes deTreffan, Reg . Sc. Acad. Par . Soce. D. T. Tronchin, M. D. Reg. Sc. Acad. Par . Soc. D.Marfilius Ventury, Nob. Par . Reg. Hif a Conf D., Petrus de Vigny, Reg., Ac. Arch. Par. Soc, D. Danfe de Villoifon, A. R. Infc, Par . Soc. D. Anton a FOREIGN MEMBERS. < • D. Anton. ce Ulloa, Pnzfedlus ClaJJisReg. Hifpan . D. Carolus Walmeiley. D. Petr.Wargentin >Ord.deStellaPoL Eques , Ac, R.ScAiockb* Sec. per p. 3 D. Joh. Hen. Georg. S. R. I. Comes de Werthern. D. Joh. Hen. Winkler, L'pfienjis. D. Euftatius Zanotti, AJirunom. Bonon ; ■ e -■ •A SPEECH * ;3> E L I -V E RID T 0 T H E ROY A L SOCIE T Y, On WEDNESDAY November 30, i*8o, BEING THEIR ANNIVERSARY. By JOSEPH BANKS, Esq. P R ESI D E N T. PRINTED BY ORDER OF THE COUNCIL. > s v \ r- •• .. • V- I [ 3 ] THE Emotions of Gratitude infpired by the very Place In which, by the Munificence of our Royal Patron, we are now for the firft Time affem- bled, render it impoffible for me to negledt the Opportunity which this Seafon, when ye have been ufed to hear yourfelves addrefled from the Chair, affords me, of offering my fmall Tribute of Acknow- ledgement for a Benefit fo eminently calculated to promote the Plonour and Advancement of this Society. Effabliffied originally by the Munificence of a Royal Founder ; foftered and encouraged fince that Time by every fucceffive Monarch who has fwayed the Britifh Sceptre, ye have ever proved yourfelves A 2, worthy [ 4 ] worthy the Favor of your Royal Protediors, A Newton, who pruned his infant Wing under your Aufpices, when his maturer Flights foared to Worlds unmeafurably diftant, fhill thought a Place among you an honorable Diftindtion. A Newton’s immortal Labors, a Boyle, a Flaaistead, a Halley, a Ray, and many others, of whom I trull: it is needlefs to remind you, have made ample Returns for the Patronage of former Monarchs. But bountiful as the Encouragement ye have received from former Patrons has ever been, the Favors which Science has, through your Interceffion, received from his prefent Majefty (whom God long preferve!) have eminently outdone their mod extenfive Ideas of Liberality. Ample Funds, by Him provided, have enabled you to reward Men of extenfive Know- ledge and Ability, for fpending whole Years in. the* Service of Science ; obferving twice the Tranfit of the Planet Venus over the Dilk of the Sun. At your Requefl, the Publick defrayed the Ex pence, of convey- ing [ 5 ] ing them to the mo.ft diftant Parts of the Globe we inhabit, where the purpofes of their Million, fo im- portant to the Science of Aftronomy, could beft be fulfilled ; while ye alone enjoy among your Fellow Academies the Reputation of having both fent and re- warded them. And more ; thofe very Donations were fo liberally planned by that Attention to Science which has ever diftinguifhed His prefent Majefly’s Reign, and wiM for ever bear Teftimony of his enlarged Mind, and Difpohtion favorable to the Advancement of tru-e Knowledge, that the Surplus alone enabled you, with his Royal Approbation, to mftitute Experiments on the Attraction of Mountains, a mid ft the barren and bleah Precipices of the Highlands of Scotland, which then, for the fir ft Time, beheld Jbftrumenfs of the. niceft Con ft mil ion tranfported to the Summits of their pathlefs Crags, and Men, ufed to other Habitations, voluntarily7 rending in temporary tints, eager to ex— preis a grateful Senfe 'of their Royal Patron’s Libe- rality^ [ 6 } rality, by thus promoting to the utmod the Caufe of Science, in which they were, under his Protection* embarked. Gifts like jthefe, unfolicited and unconditionally beftowed, might have fatisfied the Impulfes even of a Princely Munificence but not fo with our Royal Patron. Amply informed in every Branch of real Knowledge, Pie refolved to bellow a- (till more did in- guifhed Mark of his Favor on Science which he loved, and in this his laft bed Gift has fulfilled his Royal Refolution. Such a Donation, fo fwited to our prefent profper- ous and flouri thing Condition under his Royal Pa- tronage and Protection,, is admirably calculated to increafe the Refpect, great as it is, which yre have ever received from the Learned of all Europe, placing you at once, in every Point of fplendid Accommoda- tion, as much above all Foreign Academies, as the Labors of your learned Predeceffors had raifed you above them in. literary Reputation, Let [ 7 I Let then Gratitude to a Sovereign, from whom ye have received fuch confpicuous Encouragement, en- gage you, by an Application to a Promotion of the Sciences ye feverally pofiefs, to defer ve a Continuance of his Royal Favor ; to meafure your future Exertions by the Standard of his princely Liberality ; and thus fhew the World, that ye ftill are, as ye always have; been, worthy the Patronage of your King ! PHILOSOPHICAL TRANSACTIONS. I. Natural Hiftory and Nefcrlptlon of the Tyger-cat of the Cape of Good Hope. By John Reinhold For her, LL.Da Fo R. and A . S, Read November 9. 1780* FEW tribes of quadrupeds have in Africa more reprefenta* tives of their different fpecies than that of the Cat. The genus of Antelopes may perhaps be excepted, fince, to my knowledge, about twenty different Ghazels and Antelopes are to be met with in Africa ; but no more than about eight or nine of the Cat tribe have hitherto been difcovered on that continent. However, I know about twenty-one different fpecies of this Yol. LXXI. B great 2 Dr. forster’s ILiflory and Defcription of great clafs ; and, I fuppofe, thefe by no means exhauff this numerous tribe. The greater and more numerous the different genera of ani- mals are, the more difficult it muff be to the natural hiftorian ■ properly to arrange the whole of fuch an extenfive divifion of animals, efpecially if they are not equally well known. To form new genera, in order to difpofe and arrange them under* is a remedy which increafes the evil, inffead of curing it. The beft method, therefore, which can be devifed, is to make great divilions in each genus, comprehending thofe fpecies which, on account of fome common relation or charader, have a greater affinity to one another. The genus of Cat, to which the ani- mal belongs we are going to fpeak of more at large, offers three very eafy and natural fub-divifions. The firfi comprehends ani- mals related to the Cat-tribe, with long hair or manes on their necks ; fecondly , fuch as have remarkable long tails without any marks of a mane on their necks ; lajlly, fuch as have a brufh of hair on the tips of their ears, and fhorter tails than the fe- cond fub- divifion. The firff might be called in Latin Deles jubatce ; the fecond fub-divifion fhould be named Mlures ; and the third and laft, Lynces . To the firff fub-divifion the Lion and the hunting Leopard or Indian Chittah belong. The fe- cond fub-divifion confiffs of the Tyger , the Panther , the Leo- pard, the Ounce , the Puma , the Jaguar-ete , the Jaguara, the Ocelot , the Gingy of Congo, the Marakaya , the Tyger-cat of the Cape or the ’ NfuJJi of Congo , the Tibetan lyger-cat which I faw at Peterfburg, the common Bujh-cat of the Cape ; and^ laffly, the wild Cat , and its domeffic varieties. To the third divifion belong the Lynx , the Caracal , the Serval, the Bay Lynx , and the Ghaus of Profeffor guldenstedt. Since the Tyger-cat of the Cape of Good Hope, 3 Since it is quite foreign to my purpofe to fpeak of thofe fpe- cies which are known already to the naturalifl, I confine myfelf to that fpecies only which hitherto has been imperfe&ly known to naturalifts. The firft notice we had of the Cape Cat is, in my opinion, to be met with in labat’s Relation Hiftorique de TRthiopie occidentals , tom. I. p. 1 77. taken as is fuppofed from Father car azzi. labat mentions there the * Nfujji , a kind of wild Cat of the fize of a Dog, with a coat as much ftriped and varied as that of a Tyger. Its appearance befpeaks cruelty, and its eyes fiercenefs ; but it is cowardly, and gets its prey only by cn lining and infidious arts. All thefe characters are perfectly applicable to the Cape Cat, and it feems the animal is found in all parts of Africa, from Congo to the Cape of Good Hope, in an extent of country of about eleven degrees of latitude, kolbe, in his Prefent State of the Cape Good Rope, vol. II. p. 127. (of the Bnglifh. edition) fpeaks of a Tyger Bujh-cat , which he defcribes as the largeft of all the wild Cats of the Cape-countries, and is {pot- ted fomething like a Tyger. A Ikin of this animal was feen by Mr. pennant in a furrier’s fhop in London, who thought it came from the Cape of Good Hope ; from this fkin Mr. pen- nant gave the firft defcription which could be of any utility to a natural hiftorian All the other authors mention this animal in a vague manner. When I and my foil touched the lecond time at the Cape of Good Hope in the year 1 775, an animal of this fpecies was offered me topurchafe; but I refuted buying it becaufe it had a broken leg, which made me apprehen- sive of lofing it by death during the palfage from the Cape to London. It was very gentle and tame. It was brought in a pxnnant’s' Svnoplls of Quadrupeds, p. iS'i, firft edit. B 2 bafket 4 Dr. forster’s WJlory and Defcription of bafket to my apartment, where I kept it above four and twenty hours, which gave me the opportunity of defcribing it, and of obferving its manners and oeconomy; as it did to my fon that of making a very accurate drawing of it. After a moft minute examination, I found its manners and oeconomy perfectly analogous to thofe of our domehic Cats. It ate frefh raw meat, and was very much attached to its feeders and benefactors though it had broke the fore-leg by accident, it nevertheless was very eafy. After it had been feveral times- fed by me, it foon followed me like a tame favourite Cat. It liked to be ftroked and careffed ; it rubbed its head and back always againft the per fon’ s cloaths who fed it, and deiired to be made much of. It purred as our domeftic Cats do when they are pleafed. It had been taken when quite young in the woods, and was not above eight or nine months old ; I can, however, pofitively aver, having feen many Ikins of full-grown Tyger~ cats that it had already very nearly, if not quite, attained its. full growth. I was told, that the Tyger-cats live in moun- tainous and woody tradts, and that in their wild Fate they are very great deftroyers of Hares, Rabbits, Yerbuas, young Am* telopes, Lambkins, and of all the feathered tribe. DESCRIPTIO FELIS CAPENSIS. Felis cauda fub-elongata, annulata ; corpore fulvo, fupra ma~ culis virgatis infra orbicularibus, auriculis nigris, macula lunata alba. ‘ * . * * ^ '1 ' i j *• ' j . j 1 * Thefe Ikins, with feveral others of rare and non-defcript animals, I bought at a very confiderable expence, and depofited in the Britifh Mufeum, that valuable national repofitory of artificial and natural curiofities. 5 the Tyger-cat of the Cape of Good Hope. 'NJuffi. labat Ethiopic. Occident, tom. L p. 177, lyger Bofch- katten. kolbe Cape of Good Elope, vol. II. p. 127. (Engl, edit.) Cape-cat ... pennant Syn, Quadrup. p. i8r. (if; edit.) Corpus magjdtudine Fells Cati fyheftris vel paulo majus. In genere fupra colore pallide fulvo, fubtus e cinereo albo, ma- culis atrisi fPili apice pallide fulvi, bad albi.) Caput Rofro magis acuto, quam F. Cati, albo; in labio fupe- riore prope angulum riftus macula orbiculata, nigra. Nares nudas, atrae. Myftaces . plurium ordinum in labio fuperiore et‘ fupra oculos validae, albte et fulvae. Ocull figura fere trian- guli fphterici, latere anteriore perpendiculari ; Irides flavae. • Papilla orbicularis, diurna (nec ut in F. Cato perpendiculari * rima lemnifcata). Lingua retrofum aculeata. Dentes acuti at in cogeneribus. Line a albida utrinque nafo parallela, ad interiora oculorum latera. Linea nigra paullulum convergens a cantho ante- riore oculorum defcendit in nafum ; alia dues nigrae fupra oculos infra convergentes, Inque frontem afeendentes 1% prseterea in capite pundla et lineolae nigree plures fparfae. Auriculae amplae, longitudine fere capitis, ovatae, fuberedta?., intus villofas, ochroleucae ; ext us nigrae, macula lunata, tranfverfa alba. Margo exterior facculo membranaceo nudo, lobato, . Corpus ovatum, elegans. Lineae at roe longitudinales quatuor in cervice inter aurium bafes or fas, in Do fb inter ruptee ; Supe- rior a later urn obtinent maculae oblongae, lineares, obliquae, Inferiora laterum maculis rotundis fparlis. Abdomen e cinereo- album, maculis rotundis parvis, fparlis, nigris. Pedes ■ 6 Dr. forster^s Wftory and Defcription , &c. Pedes omnes fuperne fubfafciati, extremitatibus pun&is numero- us, nigris confperfi. Digit I quinque felini. Ungues modici, retradtiles, nigri. Cauda attingit bafin tarli, annulis circiter octo vel decern nigris cinfta. M E N S U R M. Ab apice roftri ad bafin caudae Cauda Caput longum Auriculae margine exteriore Pedes anteriores a cubito Pedes poftici (tarli fcilicet) 1 8 unciae ped. Angl. 8 4 3 7 4§ / t 7 ] H« Experiments and Obfervatiom on the Specific Gravities and attractive Powers of various f aline Subfiances . By Richard. Kirwan, Efi[* F. R.S. Read November 1 6, 1780. \ . 1 THE do&rine of chymical affinities hath of late received great improvements from the labours of the very excel- lent Mr. bergman of Upfal, and the Rill later refearches of Mr. wentzel ; but the order of thefe attractions has hitherto been the only point attended to by thefe philofophers, as well as by moil: preceding chymifts : for I know of none, except Mr. morveau of Dijon, who has thought of afcertaining the va- rious degrees of force of chemical attraction, by which one body aCts on various other bodies, or even on the fame body in various circumRances. He has, however, fo ably ffiewn the advantages ariiing from fuch an inquiry, that I have made it the objeCt of my attention, and beRowed much pains on it for fome time paR ; and have been thereby enabled to determine pretty exaCtly the proportion of the ingredients of many neu- tral falts, and the fpecihc gravity of the mineral acids in their pureR Rate, and free from all water. The principles on which thefe determinations are founded are' the following. 1 R. That the fpecific gravity of bodies is as their weight, divided by the weight of an equal bulk of rain or diRilled wa- ter, this being at prefent the Randard with which every other body is compared. 2dly0, 8 Mr. kirv/an’s Experiments , &c. on the fpecific Gravities adly. That if bodies, fpecifically heavier than water, be weighed in air and in water, they lofe in water part of the weight which they were found to have in air ; and that the weight fo loft is juft the fame as that of an equal bulk of wa- ter, and Gonfequently that their fpecific gravity is equal to their weight in air, or abfomte weighty divided by their lofs of weight in water. % ^ ' ft. qdly. That if a folid, fpecifically heavier than a liquid, be . weighed firft in air, and then in that liquid, the weight it lofes is equal to the weight of an equal volume of that liquid ; and confequently if fuch folid be weighed firft in air, then in water, and afterwards in any other liquid, the fpecific gravity of this liquid will be as- the weight loft in it by fuch folid, divided by the lofs of weight of the fame folid in water. This method of finding the fpecif c gravity of liquids I have found much more exaft than that by the areometer, or the comparifoh of weights of equal meafures of fuch liquids and water, both of which are fubjeft: to federal inaccuracies. 4thly. That where the fpecific gravity of bodies is already known, the weight of an equal b%lk .of watef may alfo be found, it being as the quotient of their abfolute weight divided by their fpecific gravity. -This I fhall call their lofs of weight in water. Hence, where ’the fpecific gravity and abfolute weight of the ingredients of any compound are known, the fpecific gravity of fuch compound may eafily be calculated as it ought to be inter- mediate betwixt that of the lighter and that of the heavier, ac- cording to their feveral proportions : this I call the mathema- tical fpecific gravity. But, in fact, the fpecific gravity of com- pounds, found by adtual experiment, feldom agrees with that found by calculation, but is often greater without any diminu- and attradiroe Powers of various J 'aline Subjlances. 9 tion of the lighter ingredient. -This increafe of denfity- mu{jt then arife from a clofer union of the component parts to each other than either had feparately with ' its own integrant parts ; ’and this more intimate union mud: proceed from the attraction or affinity of thefe parts to each other : I therefore imagined this attraction might be eftimated by the increafe of denfity or fpecific, gravity and was proportionable to it, but was foon un- deceived. * • I mult alfo premife, that the abfolute weights of many forts of air have been accurately determined by Mr. fontana, at whofe experiments I was prefent, the thermometer being at 55% and. the barometer at 29I inches, or nearly fo. Their weights were as follows : • * • , - ■ ' a ■» Cubic inch, of common air ~ 0,385 Fixed air - - - 0,570 Marine air - - - 0,654 Nitrous air - - « 0,399 Vitriolic air - - - "0,778 Alkaline air - - 0,2 Inflammable. air * - - 0,03 OF SPIRIT OF SALT. From the time I firfl: read in Dr. Priestley’s Experiments on Air (that inexhauftible fource of future difcoveries) of the exhibition of marine acid in the form of air, free from wa- ter ; and that this air, reunited with water, formed an acid ~Tiquor in all refpeCls the fame as common fpirit of fait ; I con- ceived the poffibility of difcovering the exaCt quantity of acid in fpirit of fait of any given fpecific gravity, and by means of Vol, LX XL C this / io Mr. kir wan’s Experiments , &c. on the fpecifc Gravities this the exadt proportion of acid in all other acid liquors ; for if a given quantity of pure fixed alkali were faturated, firffcfey a certain quantity of fpirit of fait, and then by determined quantities of the other acids, I concluded, that each of thefe quantities of acid liquor muft contain the fame quantity of acid, and this being known, the remainder being the aqueous part, this alfo muft be known ; but this conclufion intirely relied on the fuppofition that the fame quantity of all the acids was requi- fite for the faturation of a given quantity of fixed alkali ; for if fuch given quantity of fixed alkali might be faturated by a fmaller quantity of one acid than of another, the conclufion fell to the ground. This point might, indeed, be in feme mea- fure determined by weighing the neutral falts, formed by thefe acids, when thoroughly dry ; but llill a fource of inaccuracy remained : for if they were expofed to a confiderable heat, part of the acid would neceffarily be expelled, and more of one acid than of another, and if the heat were not .confiderable, much of the water of cryflallization would remain ; fo that if the weights were found to be equal, this equality could not be afcribed to equal quantities of acid, but might perhaps arife from a fmaller proportion of acid in one of them, and a larger proportion of water, and in another from a larger propor- tion of acid and a fmaller proportion of water ; and if the: weights were unequal, no certain conclufion could be drawn. To obviate this difficulty I ufed the following expedient, i 11. I fuppofed the quantities of nitrous and vitriolic acids, neceffiary to faturate a given quantity of fixed alkali, exadlly the fame as- th-at of marine acid whofe quantity I determined ; and to prove, the truth of this fuppofition, I obferved the fpecific gravity of the fpirit of nitre and oil of vitriol I madeufe of, and in which 1 fuppofed, from the trial with alkalies, a certain proportion of acid 2 and aitradHve Powers of .various f aline Subfiances , 1 1 acid and water ; I then added to thefe more acid and water, and calculated what their fpecific gravities fhould be upon the above fuppofition, and finding the refult to tally with the fuppofition, 1 concluded the latter to be exafit. The experiments made on the marine acid were as follows. I took two bottles, which I filed nearly to the top with dis- tilled water, of which they contained in all 1399,9 gr. and in- troduced them fu'cceffively into two cylinders filled with marine air, which I had obtained from common fait by means of dilute oil of vitriol and heat, in a mercurial apparatus ; and this pro- cefs I renewed until the water had imbibed, in eighteen days, about 794 cubic inches of the marine air. The thermometer did not rife all this time above 55% nor fink, unlefs perhaps at night, under 50°, and the barometer was between 29 and 30 inches. This water, or rather Spirit of fait, I then found to weigh 1920 gr. that is 520,1 more than before. The quantity of marine air abforbed amounted then to 520,1 gr. I then exa- mined the fpecific gravity of this fpirit of fait, and found it to be 1,225. Its lofs of weight in water (that is, the weight of an equal bulk of water) Should then be 1567,346 gr. nearly; but it contained only, as we have feen, 1399,9 gr* °f water : therefore fubtraCting this from 1567,346, the remainder (that is, 167,446) muft be the lofs of 520,1 gr. of marine acid ; and con- sequently the fpecific gravity of the pure marine acid, in fueh a condenfed ftate as it is in when united to water, muft be ~ 3?I0°- ®ut Still it might be fufpeCted, that the den- fity of this ipirit did not inti rely proceed from the mere denfity of the marine acid, but in part alfo from the attraction of this acid to water, and though the length of time requifite to make water imbibe this quantity of acid made me judge that the C 2 attraction t2 Mr. sirwan’s Experiments) &c. on thefpecific Gravities attraction was not very confiderable, yet tbes following experi- ment was' more fatisfadlory. 1 expofed 1 440 gr. of this fpirit to marine air for five days,, the thermometer being at 50° or under; it then weighed 1 562 gr. and confequeiitly imbibed 122 gr. of marine air; its fpecific gravity was then 1,253, which agrees exactly with what it fhould be by calculation. N. B. I have not repeated the whole of thefe experiments, as they were very tedious; but I began them over again feveral times before 1 could afcertairi with any precifion the quantity of marine air ablbrbed, as, when the whole of a cylinder full of air was abforbed, it was difficult to flop the bottles fo as to pre- vent any mercury from falling in ; and I was obliged every night to fill the cylinders with air, left if there remained but a fmali quantity it might be imbibed before morning, and the mercury fall into the bottles. I alfo made fome allowance for the com- mon air which I could not avoid letting into the cylinder with the marine air, as will be very apparent to whoever repeats the experiment. Being now fatisfied I had difcovered the proportion of acid and water in fpirit of fait, I was impatient to find it in other acids alfo; and for that purpofe I took 180 gr. of very ftrong oil of tartar per deliquium , but of whofe fpecific gravity X can find no note, and found it to be faturated by 180 gr. of fpirit of fait, whofe fpecific gravity was 1,225. Now, by calcula- tion it appears, that 180 gr. of this fpirit contains 48,7 gr. of acid and 131,3 of water, and hence X drew up the following table. and attraBive \ Powers of various f aline Subfances. i j The fpecific gravity of the ftrongeft fpirit of fait, made in the ufuai way, is, according to Mr. baume, 1,187, anc^ ac~ cording to Mr. bergman, 1,190; but we read in the Paris Memoirs for the year 1700, p. 19 1. that Mr. homberg? palled a fpirit whofe fpecific gravity was 1,300 ; and that made by Dr. priestley (fee vol. III. p. 275.) muft have been, about 1,500. Hence we fee, that fpirit of fait,, whofe fpecific gravity is 1,261 or lefs, has little or no attraction with water, and' therefore attracts none from air, and on that account does not heat a thermometer whofe ball is dipped in it as fpirit of vi- triol and fpirit of nitre do, as has lately been obferved by the Friendly Society of Berlin. This table is not exactly accurate, as I had not fin this firft experiment found1 the point of faturation as nicely as was requifite. However, I have not corrected' it, as the error is but fmall, and the proportion may at any time be found by calculation ; at leaf! when the fpecific gravity of this fpirit does not exceed' 1,253. Whether the mathematical fpecific gravity and that by1 obfervafion differ in the higher degrees of fpecific gravity, I have' not examined 1 but the table is formed on the fuppofition that they do not. Marine acid. W a ter. Specific Gravity. Parts. Parts. 50 G497 60 i»4 31 70 1,381 80 G34i 90 1,308 100 1,282 1 10 1,259 120 1,246 I3° ‘ 1,223 140 1,209 15° 1,196 160 1,185 17 0 m75 180 1,166 . ^90 1,158. 200 1,151 7 210 1,144 220 IM38 4.8,7 230 GI32 240 1,127 250 1,122 ' 260 1,118 270 1,114 280 1, 1 10 290 V* H-l O O - 3°° 1,103 310 1,100 320 1,097 - 33° 1,091 . 340 1,089 350 I,086 360 1,084 370 1,082 38° 1,080 39o 1,078 400 1,076 410 1,074 Common 1 4 Mr, KIR WAN’s Experiments , &c. on the Specific Gravities Common faint of fait is always adulterated with vitriolic acid, and therefore not fit for thefe trials. Intending to determine by this experiment the proportion of acid, water, and fixed alkali in digeftive fait, as it is called, I took ioo gr, of a folution of a tolerably pure vegetable alkali that had been three times calcined to whitenefs, the fpecific' gravity of which folution was 1,097. I alfo diluted the fpiritof fait with different portions of water ; the fpecific gravity of one fort was 1,115, and of another 1,098. I then found that the above quantity of the folution of a ve- getable alkali required for its figuration 27 gr. of that fpirit of fait whofe fpecific gravity was 1,098, and 23,35 gr. of that fpirit of fait whofe fpecific gravity was 1,115. Now, 27 gr. of fpiritof fait, whofe fpecific gravity is 1,098, contain 3,55 gr. of marine acid, as appears by calculation. As the principle on which this calculation, by which the proportion of fubflances in . alloy is found, may not be generally known, I fhall here mention them in the words of Mr. cotes. 44 The data requifite are the fpecific gravities of the mixture 44 and of the two ingredients. .... Then, as the difference 14 of the fpecific gravities of the mixture and the lighter ingre- 44 dient is to the difference of the fpecific gravities of the mix- 64 ture and the heavier ingredient, fo is the magnitude of the 44 heavier to the magnitude of the lighter ingredient. Then, 44 as the magnitude of the heavier multiplied into its fpecific 44 gravity is to the magnitude of the lighter multiplied into its 44 fpecific gravity, fo is the weight of the heavier to the weight 64 of the lighter .... Then, as the fum of thefe weights 44 is to the given weight of either ingredieiit, fo is the weight 44 given to the weight of the ingredient fought.” Thus, and attractive Powers of various faline Subfances, 1 5 Thus, in this cafe, 1,098 - 1,000 = ,098 is the magnitude of the heavier ingredient, viz. the marine acid ; and, 098 x 3,100 = 0,3038 the weight of the marine acid; and, on the other hand, 3,100 — 1,098 = 2,002 the magnitude of the wa- ter, and 2,002 x 1,000 = 2,002 its weight; the fum of thefe weights is 2,3058 : then, if 2,3058 parts of fpirit of fait con- tain 0,3038 parts acid, 27 gr. of this fpirit of fait will contain 3,55 acid. In the fame manner it will be found, that 23,35 gr. of fpirit of fait, whofe fpecific gravity was 1,115, contained 3,55 gr. acid. The point of faturation was pretty accurately found by put- ting the glafs cylinder which contained the alkaline folution on the fcale of a very fenfible balance, and at the fame time weigh- ing the acid liquor in another pair of fcales, when the lofs of weight indicated the efcape of nearly equal quantities of the fixed air contained in the folution ; then the acid was gradually added, by dipping a glafs rod into it, to the top of which a fmall drop of acid adhered : with this the folution was fiirred, and very fmall drops taken up and laid on bits of paper framed blue with radifh juice. As foon as the paper was in the lead: reddened, the operation was completed fo that there was always, a very fmall excefs of acid, for which half a grain was con- dantly allowed ; but no allowance was made for the fixed air, which always remains in the folution ; but as, on this account, only a fmall quantity of the alkaline folution was uled, this proportion of fixed air mud have been inconfiderable.. If an, ounce of the folution had been employed, this inappreciable: portion of fixed air would be fufficient to caufe a fenfible error : for I judged of the quantity of fixed air loft by the difference: betwixt the weight added to the 100 gr. and the a&ualf weight 1 6 Mr. kir wan’s Experiments , &c. on the fpecific Gravities of the compound. When this difference amounted to 2,2 gr. then I judged the whole of the fixed air expelled, and found it to be lo, as 100 gr. of this alkalnie folutioii, being evaporated to dryhefs in a heat of 300°, left a refiduum which amounted to 1 of gr. ; which iof gr. contained 2,2 gr. of fixed air, as will hereafter be feen. H ence 8,3 gr. of pure vegetable fixed alkali, free from fixed air and water, or 10,5 of mild fixed alkali, were faturated by 3,55 gr. of pure marine acid, and confequently the refulting neutral fait fhould, if it contained no water, weigh n,85 gr. ; but the halts refulting from this union (the folution being eva- porated to perfect drynefs in a heat of 1 6o° kept up for four hours) weighed at a medium 12,66 gr. Of this weight 11,85 gr. were acid and alkali ; therefor^ the remainder, viz. 0,81 of gr. were water; therefore 100 gr. of perfectly dry, digefHve fait contain 28 gr. acid, 6,55 water, 65,4 of fixed alkali. I was then curious to compare my experiments with thofe made by others, but could not find any made with fufficient precifion but thofe of Mr. homberg in the Paris Memoirs for 3699. However, as to fpirit of fait 1 did not think proper to compare them, as he mentions that his could diffolve gold, and therefore was probably impure. OF SPIRIT OF NITRE. The common reddifh brown or greenifh fpirit of nitre con* taming, befides acid and water, a certain portion of phlogifton, and being alfo mixed with fome portion of the acid of fea. fait, I judged unfit for thefe trials, and therefore ufed only the de- phlogifticated fort, which is quite colourlefs, and refemblespure water in its appearance. This pure acid cannot be made to exiffc in and attractive Powers of different f aline Subfiances * 17 in the form of air, as Dr. priestley has fhewn ; for when it //v is deprived of water and phlogifton, and furnifhed with a due proportion of elementary fire, it ceafes to have the properties of an acid, and becomes dephlogiflicated air ; I could not, there- fore, determine its proportion in fpirit of nitre as I had done that of the marine acid, but was obliged to ufe another method. i ft. To 1963,25 gr. of this fpirit of nitre, whofe fpecific gravity was 1,419, 1 gradually added 179,5 gr, of difiilled wa- ter, and when it cooled I found the fpecific gravity of this mix- ture 1,389. 2dly. To 1984,5 gr. of this I again added 178,75 gr. of wa- ter; its fpecific gravity was then 1,362. I then took 100 gr. of a folution of fixed vegetable alkali, whofe fpecific gravity was 1,097, the fame I had before ufed in the trials with fpirit of fait, and found this quantity of alkali to be faturated by 1 1 gr. of the fpirit of nitre, whole fpecific gravity was 1,419 ; and by 12 gr. of the fpirit, whofe fpecific gravity was 1,389 ; and by 13,08 of that, whofe fpecific gra- vity was 1,362. The quantities here mentioned were the me- dium of five experiments. I found it neceflary to dilute the nitrous acid with a fmall proportion of water, of which I kept an account. When I neglected this precaution, I found that part of the acid was phlogifticated, and went off with the fixed air. Note alfo, that after each aftufion of acid ten minutes were allowed to the matters to unite, % precaution which I alfo found abfolutely neceflary. Hence (upon the fuppofition that, a given quantity of fixed vegetable alkali is faturated by the fame weight of both acids) we fee that 1 1 gr. of fpirit of nitre, whofe fpecific gravity is 1,419, contain the fame quantity of acid as 27 gr. of fpirit of \ ql# LXXl. D fait, 1 8 Mr. Kir wan’s Experiments , See. on the fpecific Gravities fait, whofe fpecific gravity is 1,098, that is, 3,55 gr. ; the remainder of 1 1 gr. is therefore .mere water, viz. 7,45 gr. ; consequently, if the denfity of the acid and water had not been increafed by their union, the fpecific gravity of the pure and mere nitrous acid fhould be 11,8729; for the fpecific gravity of this acid fhould be as its abfolute weight divided by its lofs of weight in water, and this lofs fhould be as the total lofs of thefe 1 1 gr. minus the lofs of the aqueous part. Now the total lofs = = 7,749, and the lofs of the aqueous part —7,45, and confequently the lofs of the acid part is 7,749 - 7,45 ~ 4 0,299, anc^ therefore the fpecific gravity of the acid part, that is, of the pure nitrous acid, is — 11,8729. But it is well known, that the denfity of the nitrous acid, as well as that of the vitriolic, is increafed by its union with water ; and therefore the lofs above found is not the whole of its real lofs in its natural ftate (if it could be fo found), but partly the lofs that arifes from the denfity that accrues to it from its union with water : for fince its denfity is increafed by this union, its lofs is lefs than it would be if the nitrous acid had only its own proper denfity, and confequently the fpecific gravity above found is greater than its real fpecific gravity. To determine, therefore, the real fpecific gravity of this acid in its natural hate, the quantity of accrued denfity muff be found, and fubtraded from the fpecific gravity of the fpirit of nitre, whofe true mathematical fpecific gravity will then ap- pear. I endeavoured to effed this by mixing different portions of fpirit of nitre and water,, remarking the diminution of their joint volume below the fum of the fpaces occupied by their fe- parate volumes ; but could never attain a fufficient degree of precifion. and attractive Powers of various /dime Suhfances* \ 9 precifion. The following method, though not eia&'ly accurate, I found more fatisfi&'ory. 12 gr. of the fpirit of nitre, whofe fpecific gravity by obfervation was 1,389, contained as I fup- pofed from the former experiment 3,55 gr. of acid, and 8,45 of Water ; then if the fpecific gravity of the pure nitrous acid were 1-1,872, the fpecific gravity of this compound of acid and water fhould be 1,371; for the lofs of3,55gr.acid fhould beo,299, and the lofs of the water 8,45 ; the furn of the Ioffes 8,749. f • = 1,371 ; but, as I already faid, the fpecific gravity by obfervation was 1,389, therefore the accrued denfity in this cafe was at leafl ,018, the difference betwixt 1,389 and 1,371. 1 fa y at leaf , for as the fpecific gravity 11,872 was certainly too high, the lofs of 3,55 gr. acid was certainly too fmall ; and if it were greater, the mathematical fpecific gravity 1,371 would have been frill lower. However, ,018 is certainly a near approximation to the degree of denfity that accrues to 3,55 gr. acid by their union to 7,45 gr. of water, and differs inconfi- derably from the truth, as will appear by the fequel : therefore fubtrafling this quantity from 1,419 we have nearly the mathe- matical fpecific gravity of that proportion of acid and water, namely, 1,401. And fince 1 1 gr. of this fpirit of nitre contain 3,55 gr. acid and 7,45 of water, its lofs of weight fhould be — 7,853, and fubtra&ing the lofs of the aqueous part from this, the remainder 0,405 is the lofs of the 3,55 gr. acid, and confequently the true fpecific gravity of the pure and mere ni- trous acid is ppg; = 8,7654 : this being fettled, the mathema- tical fpecific gravity and true inereafe of denfity of the above mixtures will be found. Thus the mathematical fpecific gra- vity of 12 gr. of that fpirit of nitre, whofe fpecific gravity by D 2 obfervation 20 Mr. kir wan’s Experiments , &c. on the fpecific Gravities obfervation was 1,389, muft be 1,355, fuppofing it to contain 3,55 gr- acid and 8>4 5 of water ; for the lofs of 3,55 gr. acid is ifiij-0’ 4°5? anc^ t^le fofo water 8,45; the fum of thefe loiles is 8,855. Then, = 1 ,355, and confequently the ac- crued denfity is 1,389 - 1,355 = ,034. In the fame manner it will be found, that the mathematical fpecific gravity of 13,08 gr, of that fpirit of nitre, whofe fpecific gravity by obfervation was 1,362, muft be 1,315, and confequently its accrued den- fity ,047. But the whole ftill refts upon the fuppolition that each of thefe portions of fpirit of nitre contain 3,55 gr. of acid. To verify this fuppolition, I could' think of no better method than that of examining the mathematical fpecific gravities of the firft mixture I had made of fpirit of nitre and water in large quantities ; for if the mathematical fpecific gravities of thefe agreed exaTly with thofe of the quantities I had fuppofed in fmaller portions of each, I could not but conclude, that the fuppofitions of fuch proportions of acid and water, as I had determined in each, was juft; and that this was the cafe will appear by the following calculations. 1 ft. When to 1963,25 gr. of fpirit of nitre, whofe fpecific gravity was 1,419, 1 79?5 gr* °f water were added, the quan- tity of acid upon the above fuppofition fhould be 634,53 gr. ; for ;; 11 . 3,55 :: 1963,25 . 634,53 . the quantity of waterin thofe 1963,25 gr. of fpirit of nitre fhould then be 1328,72, and after adding 179,5 gr. of water, the whole quantity of acid and water fhould be 2142,75, the lofs of acid was pi ,24, and the fum of the Ioffes 1 5 80,46 : then the mathematical - - -fpecific 3 S'/ G and attractive Powers of various J, aline Subjlances. 2 x fpecific gravity fhould be ~ 1 ?355? which is exa&ly the fame as that which was found in 12 gr. of this fpirit of nitre, on the fuppofition that they contained 3,55 gr. acid. Again: when to 1984,5 gr. of this mixture I added 178,75 gr. of water, the whole quantity of diluted fpirit of nitre was 2163,25 gr. and the quantity of acid in 1984,5 gr. was 587,081 gr. for H- 12 . 3,55 :: 1984,5 . 587,081 ; the lofs of this quan- tity of acid is 66,96 gr. and the fum of the lolfes of acid and water is 1643,129 gr. ; and confequently the mathema- * 2I0o?7 l) tical fpecific gravity fhould be 757^ 77^ — 1 5 3 1 5 9 which is the fame as that determined in 13,08 gr. of the fame mixture. By continuing thefe mixtures until I found the mathematical fpecific gravity and that by obfervation nearly to coincide, I was enabled to draw up the following table, in v/hich if any errors be found, I hope they will be excufed, from the impoffibility of avoiding them where the weights mufl be found with fuch extreme precifion : the two firft feries were only found by analogy. 2 2 Mr. kir wan’s Experiments , See. on the fpecific Gravities Spirit of nitre. Acid. Water. Accrued denfity. Mathema- tical fpecific gravity. Specific gravity by obfervation At craft, of the acid to water. Attraft. of water to the acid. Grs. Grs. t Grs. 9 — — 5.45 ,000 2,537 i,537 - - — — IO — — 6,45 ,009 1,458 1,467 ,009 ,054 1 1 — — 7,45 ,018 1,401 1,419 ,0x8 ,045 12 — — 8,45 ,°34 i,355 i,389 ,027 ,036 13,08 — — 9.53 ,047 1,3 1 5 1,362 ,036 ,027 *4, *5 — — ' 10,6 ,051 1,286 *,337 ,045 ,018 J5'23 — — 1 1,68 ,054 1,260 i,3*4 ,054 ,009 1^,305 _ _ 12,755 ,054 1,238 1,292 ,054 ,009 *7,38 — — *3,8 3 ,051 1,220 1,271 1 8,443 _ _ 14,9 ,047 1,205 1,252 *9>53 — — 15,98 ,044 I,!9I i,235 20,605 - — 17,055 ,042 I, l8o 1,222 21,68 _ _ 18,13 ,040 I,I77 1,217 22 >755 - - 19,205 ,038 1,160 1,198 23.83 _ — 20,28 ,°36 1,152 1,188 24,905 - - 2i,45 ,°33 1,144 i,*77 26,17 >—4 laa 22,62 ,030 1,132 1,162 27.34 3.55 23,79 ,027 1,130 1, *57 28,51 24,96 ,026 1,124 1, *5° 29,68 — — 26,13 ,024 1,114 1,138 30.85 - - 27,3° ,022 1,2*3 i,*35 32 02 — - 28,47 ,020 1,109 1,129 33>°9 - — 29,54 ,018 1,102 1,120 34,26 _ _ 3o,7i ,016 1,101 1,117 35,43 _ - 31,88 ,014 1,097 1,1 1 1 36,60 _ _ 33,' 05 ,012 1,094 1, 106 37.77 - 9, 34,22 ,010 1,090 1,100 j&>94 — — 35,39 ,008 1,088 1,096 40,n - - 36,56 ,006 1,085 1,091 41,28 — — 37,73 ,004 1,082 1,086 42,45 _ _ 38,90 ,002 1,080 1,082 The intermediate fpecific gravities may be found by taking an arithmetical mean between the fpecific gravities by obferva- tion betwixt which that fought lies, and noting how much it exceeds or falls fliort of fuch arithmetical mean ; and then tak~ ling alfo an arithmetical mean betwixt the mathematical fpecific (6 gravities and attraffiive Power's of various faltne Subfiances . 23 gravities betwixt which that fought for mujft lie, and a propor- tionate excefs or defect. I have added a column of attra&ion of the nitrous acid to water as far as it keeps pace with the increafe of denfity, but no farther, as I am unacquainted with the law of its further increafe. The fpecific gravity of the ftrongeft fpirit of nitre yet made is, according to Mr. baume, 1,500; and according to Mr. BERGMAN, 1,586. I next proceeded to examine the proportion of acid, water, and fixed alkali in nitre, in the fame manner as I had before done that in digeftive fait, and found that ioo gr. of perfectly dry nitre contain 28,48 gr. acid, 5,2 of water, and 66,32 of fixed alkali. I fhall now compare the refult of thefe experiments with thofe of Mr. homberg. The fpecific gravity of the fpirit of nitre which Mr. hom- berg made ufe of was 1,349 ; and of this, he fays, 1 oz. 2 dr. and 36 gr. that is, 621 Troy, are requifite to faturate 1 French (oz. 472,5 Troy) of dry fait of tartar; according to my com- putation 613 gr. are fufficient ; for this fpecific gravity lies be- tween the tabular fpecific gravities by ohfervation 1,362 and 1,337, and is nearly an arithmetical mean between them. The correfponding mathematical fpecific gravity lies betwixt the ta- bular quantities 1,315 and 1,286, and is nearly 1,300. Now, the proportion of acid and water in this is, 2,629 of acid, and 8,765 7,465 of water; for - 1,500 8,765 x. 300 = 7,465 water and = 2,629 °* ' acid ; ■ and the fum of both is 10,044. Now, fmce 10,5 gr. mild ve- getable fixed alkali require 3,55 gr. of add for their faturation, 472,55 24 Mr. kip, wan’s Experiments , See. on the fpeclfic Gravities = X 472,5 will require 159,7; therefore, if 10,044 gr. of nitre contain 2,629 gr. acid, the quantity of this fpirit of nitre re- quihte to give 159,7 W^1 he 613,2 nearly, and hence the differ- ence betwixt us is only. about 8 gr, ndly. Mr. homberg fays, he found his fait,, when evapo- rated to drynefs, to weigh 186 gr. more than before ; whereas, .by my experiment, it fhouid weigh but 92,8 gr. more than at lirfb I (hall mention the caufe of this difference in treating of tartar vitriolate, for it cannot be intirely attributed to the dif- ference of evaporation. jdly. Mr. homberg infers, that 1 oz. (that is, 472,5 Troy gr.) of this fpirit of nitre contains 141 gr. Troy of real acid: by my computation it contains but 123,08 gr. of real acid. This difference evidently proceeds from his negledling the quantity of water that certainly enters into the compofition of nitre; for he proceeds on this analogy, 621 . 186,6 :: 472,5 . 141. The proportion of fixed alkali I have afiigned to nitre is fully confirmed by a very curious experiment of Mr. Fontana’s, inferted in rozier’s Journal for November 1778. This inge- nious philofopher decompofed 2 oz. of nitre by diftiiling it in a ffrong heat for eighteen hours. After the diftillation there re- mained in the retort a fubftance purely alkaline, amounting to 10 French dr. and 12 gr. Now 2 French oz. = 944 gr. Troy, and the alkaline matter amounts to 607 gr. Troy ; and, accord- ing to my computation, 944 gr. of nitre fhouid contain 625 of alkali. So final! a difference may fairly be attributed to the lofs in transferring from one vefifel to another, weighing, filter- ing, evaporating, See. Mr. Lavoisier, in the Paris Memoirs for the year 1776, has given us, after Dr. priestley, the analyiis of the nitrous acid. In and attractive Powers of various f aline Sub dances. 25 •In 2 oz. French meafure ( = 945 gr- Troy) of fpirit of nitre, whofe fpecific gravity was 1,3160, he diflolved 2 oz. and 1 dr. of mercury ; the quantity of air obtained during the folution was 190 cubic inches French ( = 202,5 5 Englifh). This air was all nitrous. There remained a white mercurial fait, which, being diflilled, afforded 12 cubic inches (= 1 2,785 Englifh) of air mixed with red vapours, and which differed little from com- mon air. There afterwards arofe 224 cubic inches ( = 258,56 Englifh) of dephlogiflicated air, during the production of which, the mercury was almoft revivified, there remaining but a few grains of a yellow fublimate. The 12 inches of air mixed with red vapours arofe, he fays, from a mixture of 36 cubic inches of nitrous air ( = 38,34 Englifh) and 14 of dephlogiflicated air (14,91 Englifh); and as the mercury was almoft wholly re-, vived, he concludes, thefe airs arofe from the nitrous acid, ancT formed it ; and hence infers, that 16 oz. of this fpirit of nitre ( = 7560 gr. Troy) contained 13 oz. 7 dr. 364 gr. (that is, 6589 gr. Troy) of water, and confequently only 971 gr. Troy of real acid, and therefore 2 oz. of this fpirit of nitre contained but 120 gr. Troy of real acid: but, by my calculation, 2 oz. of this fpirit of nitre contained 213 gr. acid; for its ma- thematical fpecific gravity is 1,265. The fame weight of acid will alfo be found in it by computing the weight of the volumes of the different airs he himfelf found it confift of, or at leaf: to afford by its decompofi tion ; for 202,55 cubic inches of nitrous air weigh, by Mr. fontana’s experiment, 80,8174 gr. Troy, and 238,56 inches of dephlogifticated air weigh 100,1952 gr. Troy, and adding to thefe the weight of 38,54 inches of nitrous air, and of 14,91 of dephlogiflicated air, • which made the 1 2 cubic inches of air mixed with red vapours, we fhall find, the whole weight of thefe airs to be 202,181 gr. ; Mol. LXXL E the 2 6 Mr. kirwan’s Experiments , &c. otz /L? \fpecific Gravities the few grains wanting of 213 gr. may be accounted for from the abforption of the water in which he received the airs, and by allowing for that Hill remaining in the yellow fublimate. OF OIL OF VITRIOL The oil of vitriol I made ufe of was not perfeflly dephlo- giflicated ; but though pale yet a little inclined to red. It con- tained fome whitifh matter, as I perceived by its growing milky on the affufion of pure difhilled water. How far this may alter the refult of the following experiments I have not tried ; but believe it to be as pure as that which is commonly ufed in all experiments, and therefore the fitted: for my purpofe. To 2519,75 gr. of this oil of vitriol, whofe fpecifie gravity Was 1,819, I gradually added 180 gr. of diddled water, ^ and fix hours after found its fpecifie gravity to be 1 ,77 1 . To this mixture I again added 178,75 gr. of water, and found its fpecifie gravity, when cooled to the temperature of the at- mofphere, to be 1,719 ; it was then milky. I then faturated the fame quantity of the oil of tartar above mentioned with each of thefe forts of oil of vitriol in the manner already mentioned, and found the faturation to be ef- fected (taking the medium of five experiments) by 6,5 gr. of that whofe fpecifie gravity was 1,819; by 6,96 gr. of that whofe fpecifie gravity was 1,771 ; and by 7,41 of that whofe fpecifie gravity was 1,719. I was obliged to add a certain proportion of water to each of thefe forts of oil of vitriol ; for when they were not diluted, I perceived that part of the acid was phlogifHcated, and went off with the fixed air ; but knowing the quantity of water that was added, it was eafy to find, by the rule of proportion, the quan- tity and attractive Powers of various fallne Subjtanees » 27 tity of each fort of oil of vitriol that was taken up by the alkali. Hence I fuppofed, that each of thefe quantities of oil of vi- triol of different denfities contained 3,55 gr. of acid, as they faturated the fame quantity of vegetable fixed alkali as 1 1 gr. of fpirit of nitre, which contained that quantity of acid. I then endeavoured to find the fpecific gravity of the pure vitriolic acid in the fame manner as I before had that of the nitrous, as it cannot be had in the fhape of air unlefs united to fuch a quantity of phlogifton as quite alters its properties. The lofs of 6,5 gr. of oil of vitriol, whofe fpecific gravity is 1,819 is 3,572 ; but as thefe 6,5 gr. contained, befides 3,55 gr. acid, 2,95 of water, the lofs of this muff be fubtradted from the intire lofs, and then the remainder 0,622 is the lofs of the pure acid part in that ffate of denfity to which it is reduced by its union with water. The fpecific gravity therefore of the pure vitriolic acid in this ffate of denfity is — 5,7 07. But to find its natural fpecific gravity we muff find how much its denfity is increafed by its union with this quantity of water : and, in order to obferve this, 1 proceeded as before with the nitrous acid. 6,96 gr. of oil of vitriol, whofe fpecific gravity was 1,771, contained 3,55 gr. acid, and 3,41 of water; then its fpecific gravity by calculation fhould be 1,726, for the lofs a « *2 C £ of 3,55 gr. acid is — 0622 ; the lofs of 3,41 gr. water is d? » / 3,41 ; the fum of the Ioffes 4,032. Then, = 17,261 therefore the accrued denfity is 1,771 - 1,726 = ,045. Taking this therefore from 1,819, mathematical' fpecific gravity will be 1,774, then the lofs of 6,5 gr. of oil of vitriol, whofe E 2 fpecific zB Mr. kirwan’s Experiments , &c. on the fpecijic Gravities- fpecific gravity by obfervation is 1,819, will be found, to b# 6 £ —^=3,664; but of this 2,95 gr, are the lofs of the water it contains, and the remainder 0,714 * are the lofs of the mere n acid part. Then, ^^ = 4,9649 is nearly the true fpecific gra- vity of the pure vitriolic acid. I then found the true increafe of denfity arifing from the union of the vitriolic acid and water in the foregoing mixtures, and obferved, that in oil of vitriol, whofe fpecific gravity was 1,771, it was 0,84, and in that whofe fpecific gravity was 1,719, it' was 0,100; To obtain a fynthetical proof of thefe deductions, I compared them with the fpecific gravities of the fir ft mixtures I had made ; for if thefe deductions were true, the mathematical fpecific gra- vities, and the accrued denfities, added to each other, Ihould amount to the fame quantity as the fpecific gravities by obferva? tion ; and this I found to happen very nearly ; for in the firft experiment, where 2519,75 gr. of oil of vitriol, whofe fpecific gravity was 1,819, were mixed' witli 180 gr. of water, that oil of vitriol contained by my calculation 1376,1.71 gr. of. acid and 1143,597 gr. of water, befides the 1S0 gr. of water that were added' to it, the lofs of the acid was ~ 277,22. The 4,964 t ' whole quantity of oil of vitriol was 2699,75 gr. ; then the fum of the Ioffes was 1600,81 ; and therefore the mathemati- cal fpecific gravity 'rr 1,686 ; to which, adding ,084 the I 0 Q j o I degree of accrued' denfity, the fpecific gravity by obfervation * By mi flake, the following calculations were made on the fuppofition that the lofs was 0,715 ; the difference being immaterial, the calculations were not repeated. I Ihould. and attractive Powers of various Jaime- Suhftanccs . . 29 fiould be 1,770,, which wants lefs than 1 oooth part in 2700: of being juft. Again in. the mixture,, whofe fpecific gravity was 1,719. the fum of the Ioffes was 1779,549, and the weight of the whole 2878*4, the mathematical fpecific gravity fhould be = 1 ,6 } 7, to which adding o, 100, the fpecific gravity by obfervation fhould be 1,717, which is nearly the truth. By continuing thefe mixtures until the fpecific gravities by calculation and obfervation nearly coincided, I formed, the fol- lowing table. The extra-tabular proportions are. to be fought in the manner already fhewn ; the two firft feries were formed 30 Mr. kirwan’s 'Experiments , he. on the fpecijic Gravities Oil and pint of vitriol. Acid. W ater. Accrued denftty. [Vlathema- ticalfpecific gravity. Specific gravity by obfervation Attract, of the acid to water. Attract, oftvater to the acid. Grs. Grs. Grs. 5,58 _ _ 2,03 ,000 2,032 2,032 ,005 0,140 6,04 - _ 2,49 ,005 1,884 1,889 >045 0,149 6,5 2,95 ,045 1.774 9819 ,084 1 39 6,96 - - 3,4i ,084 1,687 9771 0,100 °937 7>4 1 — — 3, 86 0, 100 1,619 9719 0,112 0,129 7 ,87 — — 4,32 0,1 12 1G63 9675 0,122 0,122 §,33 — — 4, 7 8 0,122 95*5 9637 0,129 0,1 12 8,79 _ — 5G4 0,129 1,476 9605 OA37 0, 100 9>25 — - 5,70 0037 1,441 9578 OA39 ,084 9.71 — — 6, 16 j The fpecific gravity of the molt concentrated oil of vitriol yet made is, according to Mr. baume and bergman, 2,125. I afcertained the proportion of acid water and fixed alkali in tartar vitriolate, as before, in nitre and digeftive fait. I found the falts, refulting from the faturation of the fame oil of tar- tar, with portions of oil of vitriol of different fpecific gravi- ties, to weigh, at a medium, 12,45 gr* Of this weight only 11,85 gr. were alkali and acid, the remainder therefore was water, viz. 0,6 of a grain; confequently 100 gr. of perfectly dry tartar vitriolate contain 28,51 gr. acid, 4,82 of water, and 66,67 flxec^ vegetable alkali. Note, in drying this fait I ufed a heat of 240° to expel the adhering acid more thoroughly. I kept it in that heat a quarter of an hour. According to Mr. homberg, i French oz. (or 472,5 gr. Troy) of dry fait of tartar required 297,5 gr. Troy of oil of vitriol, whofe fpecific gravity was 1,674, to faturate it ; but, by my calculation, this quantity of fixed alkali would require 325 gr. : a difference which, confidering our different methods of determining the fpecific gravity of liquids (his method, viz. that by menfuration, giving it always lefs than mine) the different defecation of our alkalies, &c. may pafs for incon- fiderable. The refulting fait weighed, according to Mr. homberg, 182 gr. Troy above the original weight of the fixed alkali; but by my experiment it fhould weigh but 87,7 gr. more ; for - 10,5 . 12,45 :: 472,5 . 560,2. It is hard to lay how Mr. homberg could find this great excefs of weight both in nitre and tartar vitriolate, unlefs he meant by the original weight of the fait of tartar the weight of the mere alkaline, part, diilinT from the fixed air it contained : and indeed one would be tempted to think, lie did make this diflindxion ; for in that 6 cafe -32 Mvxir WAN’s 'Experiments, ' &c. -on the- fyecijic Gravities cafe the excefs of weight will be very nearly fuch as he deter- mined it: for -H 10,5 . 8,3:: 472,5 . 373,3* Now, the whole weight of his nitre was 560,2, as I have above fhewn : then 560,2 - 373,3 — 1 16,9, which is only 4 gr„ more than he -de- termined it. Hence he -inferred, .that 1 oz. (472,5 gr. Troy) of this oil of vitriol contains 291,7 gr. of acid. By my computation it contains but 213,3 ; but it muft be confidered, he made no allowance for the water contained in tartar vitriolate, and ima- gined the whole of the increafe of weight proceeded from, the acid that is united in it to the fixed alkali. Now the aqueous part in 560 gr. of tartar vitriolate amounts to 37 gr. the re- maining difference may be attributed to the different degrees of defecation, &c. OF THE ACETOUS ACID. I have made no experiment on this acid ; but, by calculating from the experiment of Mr. homberg, I find the fpecific gra- vity of the pure acetous acid, free from fuperfluous water, ihould be 2,130. It is probable, its affinity to water is not if rong enough to caufe any irregular increafe in its denfity, at leaf! that can be expreffed by three decimals ; and hence its pro- portion of acid and water may always be calculated from its fpecific gravity and abfolute weight. 100 parts of foliated tartar, or (as it ffiould rather be called) acetous tartar, contain well dried 3 2 of fixed alkali, 1 9 of acid, and 49 parts of water. The fpecific gravity of the fhrongefi: concentrated vinegar yet made is 4,069. It- and attractive Powers of various faline Subjlances „ 3 3 It is harder to find the point of faturation with the vegetable than with the mineral acids ; becaufe they contain a mucilage that prevents their immediate union with alkalies, and hence they are commonly ufed in too great quantity. They fhould be ufed moderately hot, and lufncient time allowed them to unite. From thefe experiments it follows : id. That fixed vegetable alkalies take up an equal quantity of the three mineral acids, and probably of all pure acids ; for we have feen, that 8,3 grains of pure vegetable alkali (that is, free from fixed air) take up 3,55 gr. of each of thefe acids, and con- fequently 100 parts of cauflic fixed alkali would require 42,4 parts of acid to faturate them. Now, Mr. bergman has found, that 100 parts of cauflic fixed vegetable alkali take up 47 parts of the aerial acid, which, confidering his alkali might contain fome water, differs but little from my calculation. It fhould therefore feem, that alkalies have a certain determinate capacity of uniting to acids, that is, to a given weight of acids 4 and that this capacity is equally fatiated by that given weight of any pure acid indifcriminately. This weight is about 2,35 of the weight of the vegetable alkali. 2dly. That the three mineral acids, and probably all pure acids, take up 2,253 times their own weight of pure vegetable alkali, that is, are fafurated by that quantity. 3dly. That the denfity accruing to compound fubffances irom the union of their component parts, and exceeding its mathematical ratio, increafes from a minimum , when the quan- tity of one of them is very fmall in proportion to that of the other, to a maximum , when their quantities differ lefs ; but that the attraction, on the contrary, of that part which is in the fmallePc quantity to that which is in the greater, is at its Vol. LXXL F maximum 94 Mr. kirwan’s Experiments , See . the fpecific Gravities maximum when the accrued denfity is at its minimum , but not reciprocally ; and hence the point of faturation is probably the maximum of deniity and the minimum of fenlible attraction of one of the parts. Hence no decompofition operated by means of a fubftance that has a greater affinity with one part of a com- pound than with the other, and than thefe parts have to each other, can be complete, unlefs the minimum affinity of this third fubftance be greater than the maximum affinity of the parts already united. Hence few decompofitions are complete without a double affinity intervenes ; and hence the lad: portion of the feparated fubftance adheres fo obftinately to that to which it was firft united, as all chemifts have obferved. Thus, though acids have a greater affinity to phlogifton than the earths of the different metals have to it, yet they can never totally dephlogifticate thefe earths but only to a certain degree ; fo though atmofpheric air, and particularly dephlogifticated air, attra&s phlogifton more ftrongly than the nitrous acid does ; yet not even dephlogifticated air can deprive the nitrous acid totally of its phlogifton, as is evident from the red colour of the nitrous acid when nitrous air and dephlogifticated air are mixed toge- ther. Hence alfo mercury precipitated from its folution in any acid, even by fixed alkalies, conftantly retains a portion of the acid to which it was originally united, as Mr. bayen has ffiewn ; fo alfo does the earth of allum, when precipitated in the fame manner from its folution ; and thus feveral anomalous decompofitions may be explained. Indeed, I have reafon to doubt, whether mercury does not attract acids more ftrongly than alkalies attract them. 4thly. That concentrated acids are, in fome meafure, phlo~ gifticated, and evaporate by union with fixed alkalies. 5thly. and attractive Powers of various f aline Subftances . 35 5thly. That, knowing the quantity of fixed alkali in oil of tartar, we may determine the quantity of real pure acid in any other acid fubftance that is difficultly decompofed, as the feda- tif acid, and thofe of vegetables and animals; for 10,5 gr. of the mild alkali will always be faturated by 3,55 gr. of real acid : and reciprocally, the quantity of acid in any acid liquor being known, the quantity of real alkali in any vegetable alkaline liquor may be found. OF THE SPECIFIC GRAVITY OF FIXED AIR IN ITS FIXED STATE. Being defirous to know the fpecific gravity of fome fub- ftances which are difficultly procured, or at lead: preferved for any time, free, from fixed air, fuch as fixed and volatile alkalies, I was induced to feek the fpecific gravity of the former in its fixed ftate as of an element neceffary to the calculation of the latter ; it being very evident, that its denfity, in its fixed hate, mu ft be very different from that which it poftefles in its fluid elaftic ftate. I therefore took a piece of white marble, of the pureft kind, which weighed 440,25 gr. and weighing it in water, found it to lofe 162 gr. ; its fpecific gravity was therefore 2,7175. Of this marble, reduced to a fine powder, I put 180 gr. into a phial, and expelling the fixed air by the dilute vitriolic acid and heat, I found its quantity amount to 105,28 cubic inches ; the thermometer being at 6 50, and the barometer be- tween 29 and 30 inches, this bulk of air would, at 550 of Fahrenheit, occupy but 102,4 cubic inches ; at which tem- perature, according to the experiment of Mr. fontana, a F 2 cubic 36 Mr. kir wan’s Experiment s, kc. on the fpecific Gravities cubic inch of fixed air (the barometer ' being at 29°!) would weigh 0,57 of a grain ; therefore the weight of the whole quantity of fixed air amounted to 58,368 gr. which is nearly one third of the weight of the marble. At this rate, 100 gr. of the marble contained 32,42 of fixed air. To determine the proportion of .water and calcareous earth, and alio the fpecific gravity of this . latter, I put 3009,25 gr. of the fame marble finely powdered into a crucible, loofely covered ; the crucible and its contents, before calcination, weighed 8394 gr. and after remaining fourteen hours in a white heat I found it to weigh 7067,5 gr. The weight of the crucible alone was 5384.75 gr. ; therefore the weight of the lime fingly was 1682.75 gr. The marble then loff by calcination 1326,5 gr. ; j8o gr. of the marble fhould then lofe 79,3 43 gr. and 100 gr. Ihould lofe 44,08 ; but of thefe 44,08, 32,42 were fixed air, as is already feen, therefore the remainder, that is, 11,66 gr. were water, and the quantity of pure calcareous earth in 100 gr. of the marble was 55,92 gr. I next proceeded to difcover the fpecific gravity of the lime. Into a brafs box, which weighed 607,65 gr. and in the bot- tom of which a fmall hole was drilled, I fluffed as much as pofiible of the finely powdered lime, and then fcrewed the cover on, and weighed it both in air and water. When immerfed in this latter, a confiderable quantity of common air was expelled ; when this ceafed, I weighed it. Therefultof this experiment was as follows : Weight and attractive Powers of various f aline Subfiances. Gr. Weight of the box in air - 607,65 Its lots of weight in water - 73,75 Weight of the box and lime in air 1043,5 Weight of the lime fingly in air - 43 5, $5 JLofs of weight of the box and lime in water 256,5 JLofs of weight of the lime fingly - 182,3 Hence, dividing the abfolute weight of the lime by its lofs in water, its fpecific gravity was found to be 2,3908. From thefe data I deduced the fpecific gravity of fixed air in its fixed ftate ; for 100 gr. of marble confifi of 55,92 of earth, 32,42 of fixed air, and 11,66 of water; and the fpecific gra- vity of the marble is 2,717. Now, the fpecific gravity of the fixed air, in its fixed hate, is as its abfolute weight divided by its lofs of weight in water ; and its lofs of weight in water is as the lofs of 100 gr. of marble minus the lofies of the pure calcareous earth and of the water. Lofs of 100 gr. of marble = — — = 36,8 gr. ° 2,717 J > Lofs of 55^92 gr. calcareous earth rr ~~ ~ 23,39 Sr’ jupfs of 1 1,66 gr. water — 11,66 35j°5 Then the lofs of the fixed air 36,8 - 35,85-1,75; conic- quently, its fpecific gravity 18,52 ; by which it appears to be the heavieft of all acids, or even of all bodies vet known, gold and platina excepted. O F 38 Mr. kirwan’s 'Experiments, Sec. on the fpecific Gravities OF FIXED VEGETABLE ALKALI. As the manner of conducing the experiments I made on this fait was nearly the fame as that I ufed in the foregoing (except that to find its fpecific gravity I weighed it in aether inftead of water), I lhall content myfelf, to avoid the repetition of tedious calculation, with relating the refult of thefe experiments. - ill. I found that 100 gr. of this alkali contain about 6,7 gr. of earth, which, according to Mr. bergman, is filiceous : this earth pafles the filter with it when the alkali is not faturated £ with fixed air, fo that it feems to be held in folution as in liquor Jilicum. zdly. ■ 1 found, that the quantity of fixed air in oil of tartar 79 ,041 1,209 1,250 121,66 _ — 95s4 ,040 1,198 1,238 127,34 — — 101,15 ,°39 1,187 1,226 133,02 - - 106,83 ,°38 1,178 1,216 i38,7 — — 112,51 ,°37 1,170 1,207 !44>3 - - 118,19 ,°36 1,162 1,198 149,98 _ — 123,87 ,035 i,i55 1,190 155,66 — — I29s55 ,°34 1,149 i,i83 161,34 - - J35s23 s°33 I,I43 1,176 167,02 26,25 140,91 ,°32 i,i38 1,170 172,70 _ - 146,59 ,03! •i,i32 1,163 i78,38 _ — I52>27 ,03° 1,128 i,i58 184,06 — »= 157,95 ,029 1,123 i,i52 189,74 - — 163,63 ,028 1,119 i,H7 195,42 — _ 169 ,31 ,027 1,115 1,142' 201,10 - - 174,99 ,026 1,112 i,i38 206,78 - - 180,67 ,025 1,108 1,433 212,46 — -t* 1 86,35 ,024 1,105 1,129 218,14 — — 192,03 ,°23 1,100 1,123 223,82 _ — i97,7i ,022 1,099 1,121 229,50 - _ 203,39 0,21 1,097 1,118 235>l8 — — 209,07 ,020 1,094 1,114 240,86 ~ _ 214,75 0,19 1,092 1, 11 1 246,54 _ 220,43 ,018 1,089 1,107 252,12 ~ - 226,11 0,17 1,087 1,104 257,80 — — 23I,79 ,016 1,085 1,101 263,48 — — 237,47 ,015 1,083 1,098 269,16 - -> 243,15 ,014 1,08 i 1,095 Gr and attrattive Powers of various fallne Suhflances. 41' Gr. of the folution. Gr. of alkali. Gr. of water. Accrued denfity. Mathema- tical fpecific gravity. Specific gravity by obfervation 274,78 — 248,83 ,013 1,079 1,092 280,46 — 254,51 ,012 1,077 1,089 286,14 — - 260,19 ,01 1 1,076 1,087 291,82 - - 265,87 ,010 1,074 1,084 297,5° — - 27i,55 ,009 1,070 1,079 303,18 - — 277,23 ,008 1,069 1,077 308,86 26, 25 282,91 ,007 1,068 1,075 31 4*54 — 288,59 ,006 1,066 1,072 319,22 — — 294,27 ,005 1,065 1,070 324,90 — - 30°, 45 ,004 1,064 1,068 330G8 - 3o6>13 ,003 1,063 1,066 336,26 — - 311,81 ,002 1,062 1,064 34i>94 — — 3i7,49 ~,OOI 1,061 1,062 Impure vegetable fixed alkalies fuch as pearl afh, pot afhes, &c. contain more fixed air, as appears by the experiments of Dr* lewis. Pearl afh, according to Mr. cavendish, contains 28,4 or 28,7 per cent, of fixed air. Hence in lyes of equal fpecific gravity with thofe of a purer alkali, the quantity of faline mat- ter will be more probably in the ratio of 28,4 or 28,7 to 21 ; but this furplus weight is only fixed air ; and hence even in thefe lyes the quantity of depurated fait they will afford will be found by the above table. Much alfo depends on their age, the oldefl containing mofl fixed air. N Vol. LXXT. G t *2 3 III. Account of the violent1 Storm of Lightning at Eaft-boum, in Suffex, Sept. 17, J780; communicated by Owen Salufbury- Brereton, Ffq, F. R. and A . S. Read December 14.;, 1 780-0, S I R, I AM defired by my friend’ and" neighbour james adair, Efq;. of Soho Square, to communicate to you an account of the dreadful accident which happened to him and his family at Eaft- bourn, in the county of Suffex, at nine o’clock in the morning, on Sunday the feventeenth of September haft. He rented a houfe which ftood by itfelf, built of various forts of ftoile, three ftories high, and facing the fea, which was nearly South- eaft of it. The morning was very ftormy, with rain, thunder, and lightning ; and juft at nine o’clock a horrid black cloud ap~ peared, out of which Mr. adair faw feveral balls of f re drop into the fea fucceffively, as he was approaching the window in a one-pair of flairs room ; and very foon after, as he was-ftand- ing at it with his hands clafped, and extended open againft the middle of the frame, a moft violent flafti of fire forced his hands, afunder, and threw him feveral yards upon the floor on his back, with both his legs upright in the air, which remained! l;onp- fo fixed.. He was very fenfible of his fituation all the time, but could not open his eyes or fpeak ; nor had he the leaft: power of motion of any of his limbs for a long time.. On help. O' Mr, brereton’s Account of a Storm of Lightnings 43 help coming in, and examining his cloaths, which were blue cloth, his right fleeve, both of coat and waifleoat, and alfo fhirt, were all torn on the infide of the arm entirely open, as if by a dog, from the fhoulder to the wriif ; the right-fide of the breeches was torn in the fame manner, and part of each of the brafs buttons melted. He had in his fob a gold watch with a ffeel chain ; the but- ton which opens it and three other places of the cafe were melted. The pendant to which the chain is fixed was almoft melted through, and much of the heel chain is incorporated with it, as is reciprocally fome gold on that part of the ffeei which, was within the fob. The going of the watch had flopped in- flantaneoufly, occafioned, as at firfl appeared by the fmall pendulum fpiral heel fpring having been lengthened ; not that it was abfolutely fo, but relatively, refpefling the fcapement of the watch, the feveral inner turns being brought clofer together. His right-arm, right-fide, and thigh, were miferably fcorched, and the flefh torn : the foot of the flocking of his right leg and his fhoe were torn in feveral places between the buckle and the toe- end of the fhoe, and one of his toes fplit almofl to the bone ; but the buckle, which was a broad filver one, was not the lead hurt or even marked, and remained buckled as before. His fleeve- button of gold, in which was platted hair covered with cryflal, was broken from its link, and neither hair or cryflal have been found fince. A key and a pen-knife in his right-fide breeches pocket have feveral marks of fufion upon them. The frame of the window on which Mr. adair was lean- ing was little damaged ; but every pane of glafs fo completely fmafhed, you could fcarce perceive it had ever had glafs in it. The room was fluccoed and papered, and between the windows hung a large pier glafs, which, with much of the flucco, was fhivered to pieces,, and flrewed over the floor. A door oppofite the window G 2 was 44 Mr. breretqn’s Account of the violent Storm was Shattered- to pieces, and the polls of a bed in a room behind it, and all the bell- wires were deftroyed. Under the dining-room Mr. adair was in, on the parlour floor, were his coachman, butler, and footman. The coach- man was going to open a glafs-door to go towards the fea, and was ftruck dead. His body was totally black. His cloaths, and the caul of his wig, and cravat, were much torn ; but no particular flefh wound was found. The enamelled face of his fllver watch was broken to pieces, and the links of his Heel chain faftened together. The footman was drefflng his hair near a window, when he was thrown dead on the ground. He appeared much fcorched, bruifed, and black. He had a very large wound in his fide which penetrated near his heart ; but very little, if any, blood came from it. His buck-lkin breeches were much torn, and the fteel of a metal knee-buckle driven through them. The window falh was driven into the room, and a ftone, about eight inches fquare, forced out of the wall into the middle of the room, not far from the body. The butler was a yard or two behind the coachman, and going out with a telefcope in his hand, which was forced in pieces from him, his hat and wig were thrown to fome diflance, and he perceived a violent preffure on his fkull and on his back, but was no otherwife hurt. He had a fiver watch with a fiver chain, which received no damage. In the room over Mr. adair’s, a young lady was drefing, and her maid attending. They were both driven to a diftant part of the room, and rendered infenfble for fome time, but not hurt. The polls of the bed (he had juft left were all fhivered to pieces, and the bell wires deftroyed, and the chimney thrown down on the roof. 6 It of Lightning at Eafl-bourn, in Suflex. 45 It is to be remarked, that though the bodies of the two fer- vants lay unburied from the Sunday till Tuefday, all their limbs were as entirely flexible as thofe of a living perfon. Multitudes on the fhore before the houfe faw the meteor dart in a right line over their heads, and break againfl: the front of the houfe in different dire&ions, and all agreed the form and flame was exadly like that of an immenfe Iky- rocket. [ 46 ] IV. An Account of the Harmattan, a fngular African Wind. By Matthew Dobfon, M. D. F. R. S. ; communicated by John Fothergill, M, D . F. R . S. Read December 7, 1780. r 1^1 HE Harmattan is a periodical wind which blows from JL the interior parts of Africa towards the Atlantic Ocean, and poffefTes fuch extraordinary properties, as to merit the at- tention of the naturalift, making a curious and important article in the hiftory and theory of the winds. The firft information I had on this fubje£t was from my friend Mr. norris, who has frequently vifited the Coaft of Africa, and is a gentleman of an excellent underftanding and ftrifit veracity. This information immediately excited my at- tention ; and as Mr. norris was preparing to make another voyage to that part of the world, I def red him to confirm the fa£ts which he had related, by further inquiries, experiments, and obfervations ; and it is from thefe materials, with which I have been obligingly furnifhed by Mr. norris, that the follow- ing account is drawn up. On that part of the Coaft of Africa which lies between Cape Verd and Cape Lopez, an eafterly wind prevails during the months of December, January, and February, which by the Fantees, a nation on the Gold Coaft, is called the Harmattan. Cape Verd is in 150 N. latitude, and Cape Lopez in i° S. lati- tude, and the coaft between thefe two Capes runs, in an oblique dire£tion, Dr. dobson’s Account of the Harmattan, &c. 47 direction, nearly ftom W.S.W. to E.S.E. forming a range of upwards of two thoufand one hundred miles. At the Ifles de Los, which are a little to the northward of Sierra Leone, and to the Southward of Cape Verd, it blows from the E.S.E. on the Gold Coaft from the N.E. and at Cape Lopez and the River Gabon from the N.N.E. This wind is, by the French and Portu- gueze who frequent the Gold Coaft, called limply the N.E. wind, the quarter from which it blows. The Englifh, who fometimes borrow words and' phrafes from the Fantee language, which is lefs guttural and more harmonious than that of their neighbours, adopt the Fantee word Harmattan. The Plarmattan comes on indifcriminately at any hour of the day, at any time of the tide, or at any period of the Moon,, and continues fometimes only a day or two, fometimes five or fix days, and it has been known to laft fifteen or fixteen days. There are generally three or four returns of it every feafon. It blows with a moderate force, not quite fo ffrong as the fea breeze (which every day fets in during the fair feafon from the W. W.S.W. and S.W.) ; but fomewhat ffronger than the land wind at night from the N. and N.N.W. 1. A fig or haze is one of the peculiarities which always ac- companies the Harmattan. The gloom occafioned by this fog is fo great, as fometimes to make even near objects obfcure. The Englifh fort at Whydah hands about the midway between the French and Portuguefe forts, and not quite a quarter of a mile from either, yet very often from thence neither of the other forts can be difcovered. The fun, concealed the greateih part of the day, appears only about a few hours about noon, and then of a mild red, exciting no painful fenfation on the eye. As the particles which conflitute the fog are depofited on the. grabs, the leaves of trees, and even on the fkin of the negroes, fo 43 Dr. dobson’s Account of the Harmattan, fo as to make them appear whitifh, I recommended to Mr; norris the ufe of a good microfcope, as this might poffibly difcover fomething concerning the nature of thefe particles. 44 I was prevented,” fays Mr. norris, 44 by the bad hate of 44 my health from availing myfelf of the microfcope ; neither 4 4 could I difcover any thing by the tafre, or by expofing plates 44 covered thinly with melafFes, for when I had dropped an acid 44 or alkali into the water in which X had diffolved the melaffes, 44 nothing followed to enable me to jndge of the nature 44 of the particles. Surely they cannot be infects, or ani- 44 malcuke of infedts ? for we have no appearance of any 44 thing produced from the myriads of them which are depofited • 44 on the earth. They do not flow far over the furface of the 44 fea : at two or three miles diftance from the fliore the fog is 44 not fo thick as on the beach ; and at four or five leagues dif- 44 tance it is intirely loft, though the Harmattan itfelf is plainly 44 felt for ten or twelve leagues, and blows frelh enough to alter 44 thecourfe of the current.” 2. Extreme drynefi makes another extraordinary property of ; this wind. No dew falls during the continuance of the har- mattan; nor is there - the leaft appearance of moifture in the atmofphere. Vegetables of every kind are very much injured ; all tender plants, and moft of the productions of the garden, are ■ deftroyed,; the grafs withers, and becomes dry like hay; the vigorous ever-greens likewife feel its pernicious influence; the branches of the lemon, orange, and lime trees droop, the , leaves become flaccid, wither, and, if the harmattan continues to blow for ten or twelve days, are fo parched as to be eafily rubbed to duft between the fingers : the fruit of thefe trees, . deprived of its nourifliment, and Hinted in its growth, only ; appears to ripen, for it becomes yellow and dry, without acquiring afingular African Wind, , 49 acquiring half the ufuai fize. The natives take this oppor- tunity of the extreme drynefs of the grafs and young trees to fet fire to them? efpeeially near their roads, not only to keep thofe roads open to travellers, but to deftroy the fhelter which long grafs, and thickets of young trees, would afford to fkulk- ing parties of their enemies. A fire thus lighted flies with fuch rapidity as to endanger thofe who travel : in that fituation a common method of efeapeis, on difeovering a fire to windward, to fet the grafs on fire to leeward, and then follow your own fire. There are other extraordinary effefts produced by the extreme drynefs of the Harmattan. The covers of books, Mr. norris informs me, even clofely fhut up in a trunk, and lying among his cloaths, were bent as if they had been expofed to the fire. Houfhold furniture is alfo much damaged : the pannels of doors and of wainfcot fplit, and any veneered work flies to pieces. The joints of a well-laid floor of feafoned wood open fuffi- ciently to lay one’s finger in them ; but become as clofe as be- fore on the ceafing of the Harmattan. The feams alfo in the fides and decks of fhips are much injured and become very leaky, though the planks are two or three inches in thicknefs. Iron-hound calks require the hoops to be frequently driven tighter; and a calk of rum or brandy, with wooden hoops* can fcarcely be preferved ; for, unlefs a perfon attends to keep it moiflened, the hoops fly off. The parching effects of this wind are likewife evident on the external parts of the body. The eyes, noftrils, lips, and pa- late, are rendered dry and uneafy, and drink is often required, not fo much to quench third:, as to remove a painful aridity in th z fauces. ■ The lips and nofe become fore, and even chapped ; and though the air he cool, yet there is a troublefome fenfation of prickling heat on the Ikin. If the Harmattan continues Vol. LXXL H four 50 Dr. dobson’s Account of the Harmattan, four or five days, the fcarf fkin peels off, fir ft from the hands and face, and afterwards from the other parts of the body, if it continues a day or two longer. Mr. norms obferved, that when fweat was excited by exercife on thofe parts which were covered by his cloaths from the weather, it was peculiarly acrid, and tafted, on applying his tongue to his arm, fome- thing like fpirit of hart’s-horn diluted with water. As the ftate of fait of tartar placed in the open air, and the quantity evaporated from a given furface of water, are obvious proofs of the comparative moifttire or drynefs of the atmofphere, I defired Mr. norris to put the Harmattan to each of thefe tefts ; and particularly to moiften fait of tartar ad deliquium , and expofe it to the night air during the time that the Harmattan was blowing. The following is the account of the refult ©f thefe experiments. Salt of tartar wTill not only remain dry during the night as well as in the day ; but, when liquified fo as to run upon a tile, and expofed to the Harmattan, becomes per- fectly dry in two or three hours ; and, expofed in like manner to the night air, will be dry before morning. With refpeft to evaporation Mr. norris fays, “ 1 fixed the tin veflel, with which you favoured me, on a grafs plat 4t behind my houfe, upon a ftand four feet high, and expofed Th sSJ*' A/‘ Mr, hunter on a new Method of applying the Screw. 59- 3. That the machine be as fimple as is confident with other conditions. 4. That it be as portable and as little troublefome in the ap- plication as poffibie. 5. That the contrivance be fuch that the moving power may be applied in fuch a way as to a£t to the greatefl advantage ; and that the motion ultimately produced may have that diredlion and velocity which is mod: adapted to the execu- tion of the defign propofed by the whole. 6. Of two machines, equal in other refpedts, that deferves the preference in which the fridlion leaf!: diminiffies the effeft propofed by the whole. It will eafily appear, that fome of thefe conditions, if car- ried to an extreme, will be inconfiflent with fome of the others. Here the proper medium confifts in adapting them to each other in fuch a manner, as that the refult of the advantages of both may be the greatefl, and that of the defedbs the leafl, that is poffibie. The following method of applying the fcrew, I think, may in certain cafes be attended with fome of thefe advantages to a greater degree than by thofe commonly pra&ifed. Let ab (fig. 1.) be a plate of metal in which the fcrew CD plays, having a number of threads in an inch equal to a. Within the fcrew CD there is a female fcrew, by which is re- ceived the fmaller fcrew de of ay-i threads in an inch. This fcrew is retained from moving round along with the fcrew C£> by means of the apparatus at argb. Now, if the handle ckl be turned a times round the fcrew, CD will advance upwards an inch, and if we fuppofe the fcrew de to move round along with cd, the point e will alfo advance an inch. If we now turn the fcrew de a times backwards, the I 2 point 6o Mr. hunter on ci new Method point e will move downwards of an inch, and the refult of both motions will be to lift the point e upward ( i - = ) of an inch. But if, while the fcrew CD is turned a times #+ 1 round, de be kept from moving, the effedt will be the fame as if it had moved a times round with CD and been a times turned back, that is, it will advance —7— of an inch. At one turn therefore of the handle ckl it will move upwards x ~ of an inch. If then we fuppofe the handle ckl to be h inches long, the power gained by the machine will be. as a x 6,2832 h to unity. To illuftrate this by a particular example, let the fcrew cd have 1 o threads in an inch, and de 1 1 : then, while the handle ckl is turned 1 o times round, the point d will rife one inch above its former fituation. But at 10 turns it can only pafs over 1 o threads of the fcrew de, and confequently it will advance upon that fcrew 1-iths of an inch. The point e therefore mud: rife _Vth of an inch, that the point d may have room to rife a complete inch above its former place : therefore, at one turn of the handle, the point e will rife -^th of an inch ; and if the handle be fuppofed half a foot long, the power, to produce an equilibrium, muft be to the weight as 1 to no x 6,2832 x 6=z 4146,912, which is the very number expreffed by the general theorem, viz. a% + a x 6,2832 b, calling a = 10 and b= 6. Now let us compare, according to the rules before laid down, this method of uling the fcrew with the common one. And, firft, in order to have the fame power by means of the common fcrew that is exerted by this machine, it muft have a number of threads «f applying the Screw. dr threads in an inch equal to az a, which would render it too- weak to refill any considerable violence. For example, if dc have five threads in an inch, and de fix, and if the handle ckl is a foot in length, the power gained by the engine will be' nearly as (V -|- a x 6 b — ) 2 1 60 to 1 ; whereas, to have the fame force by means of the common ferew, it muff have 30 threads in an inch, and fo mufl yield under a refinance which the other ferew would overcome without any difficulty. Upon this- principle, the ferew may be applied with advantage in preffes of different kinds, by fixing one of the plates of the prefs to the end of the ferew at e. As to the fecond requisite, both methods may be equally adapted to it ; yet other circumffances will determine us to apply the common ferew where a fmall increafe of power is neceffary, and the prefent contrivance, when we ffandinneed of a greater. This will follow from the third rule, as in. the method now propofed a double number of ferews is required, which makes the ffrudiure more complicated, occafions more expence, and requires a greater accuracy of conffrudtion, fince, unlefs this is attended to, the machine will not move. However, the machine may, in fome cafes, anfwer the fourth intention better than the common one, as the power gained by the additional ferew enables us to ffiorten the handle which will tend to make the whole more portable. The power is here applied in the fame diredlion as. in the common ferew, fo that both equally anfwer the firff part of the fifth rule ; but as to the laid, the motion ultimately produced, it will depend on particular circumffances wfffich of them is moff fit for ufe in any cafe. Thus, if the ferew. de be intended to carry an index which muff turn round at the fame time that it rifes upwards, the common ferew is preferable ; for although T Call:: 6 2 Mr. hunter on a new Method ,Can fee a method by which the machine before defended may be made to anfwer this purpofe, I am aim of: afraid to propofe it, I mean, that within the ferew de another fill fmaller fhould be made to play, and be connected with the ferew cd, fa as to move round along with it. It m-uft have ad + a + i threads in an inch, and they mu ft be in the contrary direction to thole of cd, fo that when they are both turned together, and cd moves upwards, this other one may move downwards. At one turn of the handle this wall move upwards — x x a a a + a + I — — : — of an inch, and at the fame time will move a44-24- i Mr , pennant’s Account Turkey to be thought a native of India. He quotes jelian for that purpofe, who tells us, 44 That in India are very large poultry not with u eombs, but with various coloured crefls inter— 44 woven like flowers, with broad tails neither 44 bending nor difplayed in a circular form, which 44 they draw along the ground as peacocks do 44 when they do not eredt them ; and that the w feathers are partly of a gold colour, partly *4 blue, and of an emerald colour” This in all probability was the fame bird with the Peacock Pheafant of Mr., edwards, Le Paon de Tibet of M. brisson, and the Pavo bicalcara - tus of LiNNaeus. I have feen; this bird living*:. It has a crefl:, but not fo confpicuous as that; described by jelian ; but it has thofe. friking colours in: form of eyes, neither does it eredr its tail like the Peacock t ? but trails it like, the Pheafant. The Catreus of strabo | feems , to be the fame bird. He defcribes it as un^ commonly beautiful and fpotted, and very like a Peacock. The former, author § gives a more minute account of this fpecies, and under the fame name. He borrows it from clitarchus, am attendant of Alexander the Great in all his conquefts. It is evident from his defcription, that it was of this kind ; and it is likewife pro- bable, that it was the fame with his large Indian * De Anim. .lib. XVI, c, ■f Edw. II. 67. Lib. XV. p. 1646 § De Anim. lib, XVII. c. 23, poultry a Not natives of Europe ; nor of Afia ; poultry before cited. He celebrates it alfo for its fine note ; but allowance muft be made for the credulity of ^elian. The Catreus , or Peacock Pheafant, is a native of Tibet, and in all proba- bility of the north of India, where clitarchus might have obferved it ; for the march of Alex- ander was through that part which borders on Tibet, and is now known by the name of Penj-ab or five rivers. I fhall now collect from authors the feveral parts of the world where Turkies are unknown in the Hate of nature. Europe has no fhare in the queftion ; it being generally agreecT that they are exotic in refpedt to that continent. Neither are they found in any part of Afia Minor, or the Afiatic Turky, notwithftanding ignorance of their true origin firft caufed them to be named from that empire. About Aleppo, capital of Syria, they are only met with, do- mefticated like other poultry *. In Armenia they are unknown, as well as in Perfia ; having been brought from Venice by fome Armenian mer- chants into that empire f, where they are fiill fo fcarce as to be preferved among other rare fowl in the royal menagery J. du halde acquaints us, that they are not natives of China ; but were introduced there from other * RUSSEL, 63. f Tavernier, 146. | bell’s Travels, 1, 128, L 2 countries. 76 Mr. pennant’s Account countries. He errs from mifinformation in faying that they are common in India. I will not quote gemelli c areri, to prove that they are not found in the Philippine Iflands, be- caufe that gentleman with his pen travelled round the world in his eafy chair, during a very long indifpofition and confinement * in his native country. But dampier bears witnefs that none are found in Mindanao J. nor Africa ; The hot climate of Africa barely fuffers thefe birds to exift in that vaft continent, except under the care of mankind. Very few are found in Guinea, except in the hands of the Europeans, the negroes declining to breed any on account of the great heats §. prosper alpinus fatisfies us, they are not found either in Nubia or in Egypt. He defcribes the Meleagrides of the ancients, and only proves that the Guinea hens were brought out of Nubia, and fold at a great price at Cairo |j ; but is totally blent about the Turkey of the moderns. Let me in this place obferve, that the Guinea hens have long been imported into Britain. They were cultivated in our farm-yards ; for I dilcover in 1277, in the Grainge of Clifton, in tho * Sir james sorter’s Obf. Turkey, I. 1. 321, + BAS EOT in Churchill’s Coil. V. 29. § BOSMAN, 22 9. |1 Hift, Nat. iEgypti. I. 201. a parifh of the Turkey. jj pariffi of Ambrofden in Buckinghamffiire, among other articles, fix Mutilones and fix Afrfeanc s fee mines *, for this fowl was familiarly known by the names of Afra Avis and Gallina Africana and Numida. It was introduced into Italy from Africa, and from Rome into our country. They were negle&ed here by reafon of their tendernefs and difficulty of rearing. We do not find them in the bills of fare of our . ancient feafts f ; nei- ther do we find the Turkey : which lafi: argu- ment amounts to almofi: a certainty, that fuch a hardy and princely bird had not found its way to us. The other likewife was then known by its claflical name ; for that judicious writer Dodtor caius deferibes, in the beginning of the reign of Elizabeth, the Guinea fowl, for the benefit of his. friend gesnek , under the name of Meleagris, befiowed on it by akistotle J* Having denied, on the very befi: authorities, that the Turkey ever exifted as a native of the old world, I muft now bring my proofs of its being- only a native of the new, and of the period in which it firfi: made its appearance in Europe* but of The firfi; precife defeription of thefe birds is America, given by oyiedo, who in 1525 drew up a fum- mary of his greater work, the Hiftory of the * ken net’s Parochial Antiq. 287. f Neither in that of george nevil nor among the delicacies mentioned in the Northumberland houfhold book begun in the beginning of the reign of henry VIII. | caii Opufc, 1 3, Hi#. ..An. lib. VI, c. Indies., theiflands, Mexico, Mr. pennant's Account Indies, for the ufe of his monarch CHARLIES V* This learned man had viflted the Weft Indies and its iflands in perfon, and payed particular regard to the natural hiftory. It appears from him, that the Turkey was in his days an inhabitant of ’the greater iflands, and of the main-land. He 'fpeaks of them as Peacocks ; for being a new bird to him, he adopts that name from the re- semblance he thought they bore to the former. 64 But,5® fays he, 44 the neck is bare of feathers, 44 but covered with a Ikin which they change *4 after their phantafie into diverfe colours. They 44 have * a horn as it were on. their front, and 44 haires on the breaft-j~ftv He defcribes other birds which he alfo calls Peacocks. They are of the gallinaceous genus, and known by the name of Curafiao birds, the male of which is black, the female ferruginous. The next who fpeaks of them as natives of the main-land of the warmer parts of America, is Francisco fernandez, fent there by philip 31. to whom he was phyfician. This naturalift obferved them in Mexico. We find by him, that the Indian name of the male was Huexolotl, of the female Cihuatotolin. He gives them the title of Gallus Indicus and Gallo Pavo. The Indians, as well as Spaniards, domefticated thefe ufeful birds. He fpeaks of the flze by comparifon, faying, that the wild were twice the magnitude of -■* In the Spanifh Pe^on corto, $ InrvacHAS, III. 995. 1 the / , of the Turkey/ . yy. the tame ; . and that they were {hot with arrows or guns*. I cannot learn the,, time when Fer- nandez wrote. It mu ft be between the years 1:555 and 1 598, the period of Philip’s reign. pedro de dies A mentions Turkies on the Ifth- musofDarient- lery, a Portuguefe author, afferts, that they are found in Brazil, and gives them an 1 Indian name J ; but -fince Lean difeover no traces of them in that diligent and excellent naturalift MArcgrave, who refided long in that country, I muft deny my affent. But the former is con- firmed by that able and honeft navigator dam- pier, who faw them frequently, as well wild; as tame* in the province of Yucatan §, now reckoned part of - the kingdom of Mexico. In North America they were obferved by the very firft difcoverers. When rene de laudon- niere,. patronized by Admiral coligni, attempted to form; a fettlement near the place where Gharleftown now ftands, he met with them on . his firft landing in 156^ and by his hiftorian has reprefented them with great ’fidelity in the fifth pjate of the recital of his voyage 1 1 : from his time the witneftes to their being natives of the conti- nent are innumerable. . They have been feen in , flocks of hundreds in all parts from Louifiana Hifp. zf. f Seventeen Years Travels, 20. J in dexaet’s Defer.' des Indes, 491.- § Voyages, yol. II. part II, p. 65, 85. 114,5..' | PE SRY, • . - > .. ’ - even'i Darien j Yucatan, ; North America,;. So Mr. pennant’s Account even to Canada ; but at this time are extremely rare in a wild Hate, except in the more diftant parts, where they are {till found in vaft abun- dance. When firft It was from Mexico or Yucatan that they were introduced firft introduced into Europe ; for it is certain, that into Europe, they were imported into England as early as the year 1524, the 15th of henry viii *. We probably received them from Spain, with which we had great intercourfe till about that time. They were moll fuccefsfully cultivated in our kingdom from that period ; infomuch, that they grew common in every farm-yard, and be- came even a dilh in our rural feafls by the year 1585; for we may certainly depend on the word of old tusser, in ~his Account of the Chriftmas Hufbandlie Fare f* Beefe, Mutton, and Porke, fhred pies of the bell:, Pig, Veale, Goofe, and Capon, and Turkie well dreft, Cheefe, Apples, and Nuts, jolie carols to heare. As then in the countrie, is counted good cheare. But at this very time they were fo rare in France, that we are told, that the very firft which was eaten in that kingdom appeared at the nuptial feaft of Charles ix. in 1570 j. % baker’s Chr. anderson’s Di&. Com. I. 354. hackluy-t, II. 165. makes their introdu&ion about the year 1532. earnaby googe, one of our early writers on Hufbandry, fays, they were not feen here before 1530. He highly commends a Lady hales of Kent, for her excellent management of thefe fowl, p, 166. 4 Five Hundred Points of good Hufbandrie, p. 57, f anderson’s Di£t, Comm. I. 410. To Philos. Trans. Vol.Lxxr. Tab . m . p.So. C&ASCR6.SC. of the Turkey. 8 1 „ To this account I beg leave to lay before you the very extra- ordinary appearance on the thigh of a Turkey, bred in my poultry yard, and which was killed a few years ago for the •table. The fervant in plucking it was very unexpededly wounded in the hand. On examination the caufe appeared fo lingular, that the bird was brought to me. I difcovered, that from the thigh-bone iiiiied a fhort upright procefs, and to that grew a large and ftrong toe, with a lharp and crooked claw9, exadlv refembling that of a rapacious bird. You LXXX. M [ «*■] VII. Account of a Nebula in Coma Berenices. By Edward Pigott, Ffq. In a 'Letter to Nevil Malkelyne, D , D, F. R. S, and Ajlronomer Royal, Read January n, 1781. Prampton-houfe, Glamorganfhire, S I Kj September 3, 1779. AS my father generally addreffes to you fuch papers as he communicates to the Royal Society, I beg the favour of you to acquaint that learned body, that, on the 23d of March, I difcovered a nebula in the condellation of Coma Berenices, hitherto, I prefume, unnoticed ; at lead not mentioned in M. de la lande’s Aftronomy, nor in M. messier’s ample Cata- logue of nebulous Stars. I have obferved it in an achromatic tranfit inftrument, three feet long, and deduced its mean R. A. by comparing it to the following liars, having made the necef- fary corrections for aberration and nutation, the refults are : o / // i9i 28 33 I9I 28 4I I91 28 45 191 28 36 1 91 28 34 Mean R. A., of the nebula for April 20, 1779, 19 1 28 38 By (51 Gemini By y Canis Majoris By e Virginis By v Virginis By § Leonis Its I Mr. pigqtt’s Account of a Nebula, &c. 83 Its light being exceedingly weak, I could not fee it in the two-feet telefcope of our quadrant, fo was obliged to determine its declination likewife by the tranfit inftrument. This deter- mination, however, I believe, may be depended upon to two mi- nutes : hence its declination north is 220 53"!* The diameter of this nebula I judged to be about two minutes of a degree. I am, &c. E. PIGOTT. S' [ 84 ] VIII. Double Stars dif covered in 1779, at Frampton-houfe, Glamorganfhire. By Nathanael Pigott, Efq. F. R. S. Foreign Member of the Academies of BrmTels and Caen, and Correfpondent of the Royal Academy of Sciences at Paris ; communicated by Nevil Mafkelyne, D. D. F. R. S. and AJlrononomer Royal Read January 1 1, 1781. TO THE REV. NEVIL MASKELYNE. rev. sir, O&ober 27, 1779. INCLOSED are the determinations of the places of three double ftars, which I difcovered this fummer; at leapt, I prefume, they have not been obferved before, hecaufe I do not find them inferted in Dr. Bradley’s catalogue, publifhed in the Nautical Almanac 1773, or in the Connoiffance des Ferns , no more than in other catalogues in my poflefiion. y Delphini, indeed, is in M. de la caille’s catalogue ; but not as a dou- ble ffar. The inftrument he ufed was not, probably, power- ful enough for that purpofe. In the two-feet telefcope of my quadrant it appears only as a fingle ftar. Thefe ftars were ob- ferved by me in a three-feet achromatic telefcope of a tranfit inftrument, with an objedt-glafs near two inches diameter. The R. A. are nicely determined by feveral obfervations, which always agree with each to a fraction of a fecond in time. The 1 declinations Mr. pigott’s Account of double Stars , See. 85 declinations were deduced from the difference of altitudes be- tween the double ftars and the known ftars, to which they were compared, as ffiewn by the graduated femi-circle of the tranfit inftrument, which, being divided to two minutes only, cannot be fuppofed to give any great precifion : however, I believe, their declinations, hence deduced, to be corre