a his Experiments Heats ” emptied upwards of Seventy Times in 24 Hours- Ad In 0S, Stil, ‘which, even ona large Scale, may” “be. charged a q Four Hundred and Bighty 'T Times every Twenty-four Hours _ Ureeola Elattica, on Caont-choue Vite of » Sumatra an . pinang—Mr- Ropman’s newly-invented Trepanning Initru Mr. Corutzr’s Fil eM fachines—-The Mus Burfarius ‘ating “certain Phenomena obferved in the Ait-Vau “Farmaces of the Devon Iron-Works—An Air and a Wa for equalifing the Difcharge of Air into irnace . ~~ Vol. VET. is iluftrated with a Plate illuftrating an, unufual _ zontal. RetraGtion of the - Air—A pparatus . empl L by = -Howarp for trying the Effects of fulminating Mereu ~ explain the Theory of the Evening and Morning De ew—Vef] Plivatus-—Mefeoriel Air-holder and ia Machine—I _ Diftifling and Re@ifyiog Apparatus for. fa v uel—Ma which the Strength of Horfes may bevtuiphiy ed to knead Pak He teprefentation of the Galvanic Pile end Galvanig Cit M. Volta—Meteorological Chart to illuitrate the Influence « PRE, at n in producing a periodical Variation. in the. 3 ~~ meter—The grand antique Bacchanalian Vafe, late in the Po Boe 5 ~~. of Lord Cawdor, now at Woburn Abbey; and, Apparatus . loyed by Dr. Herfchel j ja his Experiments on. the Spires Teg of the Rays of ieee ans Gut Bae eh pgs a i br gS Ney 2 ed L Thong aa Golosnine ‘ d Pp peét to. is om ufed by the ¥ “Fat of the Art, and. ES Experiments on the - of, the Sun. By Witt Her: ] If. Experiments on the Solar and on the Terreftrial Ree Heat; with a comparative View of the La which Light and ‘Heat, or rather the Rays: whic a them, are fubject, in order to determine. whi _ fame, ‘or different. By Wirtram Hanscu IV. Account of fome interefting Exper > the London Philofophical Socieey a8 : - Bleat, excited by a Stream. of Oxygen G ~ q Charcoal, on a number. of Gems and ‘ flances fibmitted to its. eg wi ; Srpeat eae St x eee — Publifoed the Laft Day of every Month, os [PRICE “PWO: SHILLINGS) THE: "PHILOSOPHICAL MAGAZINE: COMPREHENDING : THE VARIOUS BRANCHES OF SCIENCE, “THE LIBERAL AND FINE ARTS, AGRICULTURE, MANUFACTURES, ‘ AND Pec. 34) COMMERCE, a a ne RE TO RET eee NUMBER XXX. NOVEMBER 1800. + ee ILLUSTRATED WITH eg ‘THE FOLLOWING ENGRAVINGS BY MR. LOWRY: eee 8 a uarto Plate reprefenting various Apparatus employed by Dr. Herfchel in his Experiments on Heat and Light. MF ROY res illuftratins Mr. Wood’s Examination of St.. Pierre’s” _- - Theory of the Tides; and a Reprefentation of a bine Bye ess Bere! ay ahta to Sight, 7 a chirurgical Operation. eae konDor” ol) ; ian FOR A. ‘TILLOCH: . by ee Ricnagpson, Cornhill; Caper and Daviss, ; 5 nett, Piccadilly; Symonps, Paternolter-row ; Muanay and Hienrey, Nov 32, Fleet-ftreet; Barz, Kn hoe 148, Oxford-ftreet; Vernox and Hoop, Pouliry; Haxpine, No. 36, St. James’s-ftreet ; Beni and - Brapruts, Edinburgh; Brasn and Resp, Nae Glafgow; cd W: Girscat, Doblin. COMPREHENDING pee “THE VARIOUS BRANCHES OF SCIENCE, ti os ges “HE LIBERAL AND FINE ARTS, — : AGRICULTURE, ‘MANUFACTURE Ee | AND pete Stee 5 = : COMMERCE. Shares N U M B Er R: XXXL 7 DECEMBER 1800." ts ere el oe “4ALLU STRATED x ITH rete FOLLOWING ENGRAVINGS BY MR. LOWRY: #, Additional Apparatus employed by Dr. Fierfchel i in. his Experi- ey tients. on Heat and Light. a LB oes to ilafteate C. Carnot's Principles of the TiGuttchmal ee peeves Peprecctstion of’a newly invented Inftrament for meafuring -the ae sat Caloric mete cule fom Gakeous Pepin: S = ag ON D ow: £4: As fuusrip ay DAVIS, WILKS, AND TAYLOR, CHANCERY ANE at FOR A. FILLOCH? ae “And foia by Mefirs. Rrotiarpson, Cornhill ; Cape ty ial ee | $<- Strand; “Deprerr, Piccadilly; Symonps, Paternofter-row ; o7 "a AuRRay and- nook dermal No. 32, Ficet-ftreet;. Baux, Ne.148, Oxford-firect; Vernon and Huo, Poultiy; RDING, No. 36, St. James’s-ftreet ; Betx a aprurt, Edinburgh }-Brasiand Rerp,-- seeeees bins We Sua Hci Ive to. ie ‘Stru@ure of the Cryftal ohloxgde ° ftrating the beft Conftru€tion of the Vanes of W ; concerns the Angle of Weather—Mr. Muthet’s ~afcertaining | the Heat of an Affay: =furnaceé——Von fe - charging EleGtrometer, laid before the R RE hagen—Humboldt’s Portable Barometer for Trave s fate _ the comparative Height of the Mountains of Veen; t ~~ and the Moon; according to the Obfervations of M. Scxu of. Lilignthal—€,. Reewrer’s New Powder-proof’ for’ afte the comparative Strength of Gunpowder—And a mi _ prefentation of certain: “‘Animalculz found on the Surface of a Fi pond in as which g gave ita Red Heo 1 ieee Vel. V. is “lutrated ee a ( Rewelestaty we a Blatt-f for the Reduétion of Iron froit the Ore in the large way of M - nufa@ure; from a Drawing. Ui Mr. Musnet—the Apparaus em ployed. by the French Chemilts in their Experiments on t _ flagration of the Diamond; and alfo that ufed in the Prom& x ~ of Caft Steel from Iren-by Means of the Diamond—a QuartoP ey et of a New Mercorial Gazometer, invented by Mr. W. H. Sat ju un.—Mr. Howarn’ ’s Improved. Air-Furnace—a Quarto” an} a - O&tavo Plate, contathing’ Reprefentations of Mr, Burws’s nev I ~ vention, whereby Apartments may be more ‘effectually heated than By: the Methods now in ufe; and the Accidents which f oe occur, of Women’s and Children’s Clothes bei Fire by Sparks from the Grate, may be prevented—A Chari _ iluttrate Mr. Nucenv’s new Ma netic Theery—Mr. Sour Ventilator for preferting ‘Corn on ‘Ship-board—Mr. Davie 8 Po able ae for loading as Pate Goods. MB 4 : wiih nig Satie. Ye ie e, Ve Vinis 5 illufrated sci: ‘a Reprefentation of a remarkable cobs SBlettric. Phenomenon. obferved ina Thunder-Cloud—aAimeri ag ee reat improved 40 Gallon, Still, which may. be. charg 2 ed ptied u ipwards. Of Seventy ‘Times i in 24, Hours—An th eS Sth E one, -eyen on a large Sealé, may be charged and = to oe Hundred and Eighty Times every Twenty-four How Zi 9p Elaftica, or Capeehane Nine of Sumatra ‘and. pinang—Mr. Ropman’s newly invented Trepanning Inftrume r, COLLIER’s Filtering Machines—The Mus Burfarius— pci certain Phenomeia ebferved in the Air-" 3 _-Fuintaces of the Devon. Tron-Works—Au Air ‘and ate nee renalihe the OHS of Air into. a Bla-Furnace, ee: ean -unufual r—AApparatus . employed i: Sad of i 32 Ife AP Lngraved fer the Pla hf, . ylht at a phical Masavine Vol Vi. THE PHILOSOPHICAL MAGAZINE: COMPREHENDING THE VARIOUS BRANCHES OF SCIENCE, THE LIBERAL AND FINE ARTS, AGRICULTURE, MANUFACTURES, AND COMMERCE. BY ALEXANDER TILLOCH, MEMBER OF THE LONDON PHILOSOPHICAL SOCIETY, £TC. ETC. I <¢ Nec aranearum fane textus ideo melior, quia ex fe fila gignunt. Nec nofter vilior quia ex alienis libamus ut apes.” Just. Lrrs. Monit. Polit. lib. i, cap. Te 2 VOL. VII. LONDON: PRINTED BY DAVIS, TAYLOR, AND WILKS, CHANCERY-LANE, For ALexanpeR TiLLocw; and fold by Mefirs, Ricnarpson, Cornhill; Capex and Davies, Strand; DesreTT, Piccadilly ; Mur xay and Hicutey, No. 32, Fleet-ftreet ; Symonps, Pater-nofter Row; Beir, No. 148, Oxford-ftreet ; Veanor and Hoop, Poultry; Harpinc, No. 36, St. James’s-ftreet ; Betx and Brapruts, Edinburgh; Brasu and Reip, Glafgow; and W. Gitgent, Dublin - : hgh y ; wey ¢ | t i , ‘ n # Kee q + f --—* . 4 oe \ \ 3 P ‘ ¥ / é ‘ ' \ ; 1 ‘ ‘ ’ z R i 4 . a ‘ x F . : é 4 . ; i a ' . ‘ ‘ - - 5 - ' ' ! ‘ ‘ . °, ‘ e i ‘ CONTENTS EIGHTH VOLUME, ‘THOUGHTS on Colouring, and particularly with a Retox JSped to the Method ufed by the Venetians in the Mechanical Part of the Art, and to their Method of Arranging the _ Tints - - - rues Dat. Experiments on the Refrangibility of the invifible Rays of the Sun - = Foe - - Experiments on the Solar and on the Terreftrial Rays shat eccafion Heat; with a comparative View of the Laws te which Light and Heat, or rather the Rays which occafion them, are /ubjeG, in order to determine whether they are the fame, or different. By Witt1am Herscuet, LL.D, F.R.S. . - ~ 16, 126, 353 Account of fome interefting Experiments, performed at the London Philofopbical Society, refpefting the Effeéts of Heat, exctted by a Stream of Oxygen Gas thrown upon ignited Charcoal, on a Number of Gems and other refraca tory Subflances fubmitted to tts Aion; with a Deferiptian of the Apparatus employed - - 21, 263 An Effay on the Declivities of Mountains. By RicHary Kirwan, E/g. LL.D. F.R:S., and Prefident of the Royal Irifh. Academy ~ - - - 2g Op the Identity of the Pyromucous, Pyrotartareous, and Pyroligneous Acids; and the Neceffity of not confidering them any longer as diffin&t Zcids. By C. Fourcroy end VAUQUELIN = - - 40 Account of a fatal Accident which happened to a Traveller on the Glacier of Buct; with fome Cautions ta thofe whe through Curinfity may vifit the Mountains of Swifferland, and particularly the Glaciers. By M: A. Pictret, Pro- -_ feffor of Philofophy - - 53 10 he on the Ibis of the Antiont Egyptians. By C. Caxias ' 6k i brief Examination of the received Do&rines refpetting Heat or Caloric. By ALEXANDER TILLOCH. Read before the Afkefian Society, December 1799 ¥O, 119, 211 a - Mh foarte CONTENTS. A fhort View of the Obfervations which bave been made at different Times on the Luminous Appearance of the Sea. Read in the Phyfical Society af Gottingen, by J. G. L. BLUMHOFF - - Page 9F On the Submerfion of Swallows in Abed - 107 A cheap and efficacious Method for defiroying Rats and Mice; recommended to the Agriculture Society of Man- chefler by Mr. C. Tayvutor, Secretary to the Society for the Encouragement of Arts, Manufaéiures, and ee di ee An. Examination of St. PreRRR’s Hypothefis refpetting tha Caufe of the Tides, which, in oppofition to the recewed Theory, attributes them to Juppofed 4 periodical Effufions of the Polar Ices. By SaMuEL Woops, E/g. Read before the Afkefian Society November 5, 1799 - 134, 267 Account of a new Operation lately eee with Succe/s ix France, for refioring Sighs in certain Cafes of Ree By C. Demours On the Cultivation and Ufe 3 the Sie S2lk- ee ay J.A. MOLLER, Director - the UY gprenien Patriotie Society 149 ~ On feel new Properties di Lipwvdred im pap barter Ay- drogen Gas. By C. Raymonp, Probe of Chemiftry in the Central School of Ardeche - - 154 On the general Nature of Light. By Mr. Ropert HERon, - 164 Some Account of FREDERicK AuGcustus EscuEn, wha was fwallowed wP in a Fi were of the Snow in the Hones of Buet On the Difcovery ae that Salt known aie the Name as Seagnette’s Salt aceate of Soda). By Tree efor BECK= MANN 166 On the Proportions of Charcicl, or Ox a of aries contained in certain Kinds of Wood and,in Pit- Coal; and on a Car- _ buret of Sulphur newly difcovered. By M. Proust 169 Letter from A. M. Vasauyi-Eanp1 to J. Buvtna, Pro- Seljor of Medicine im the Cerra of Turin, on Animat Ele€tricity scot PO -» Of Chemical and Minetalepieal Nomenctatere “By RICHARD 1) \Kinwakt, EL.B.F.R.S. and PRIA. 172, 203 A fhort View of the new Elegirical. Bidgsctin ice patere by Dr. Van Marum . 313 _ Refesions on the Theory- of ti: Infrnitef mak: ries _ By _C.Carnor, Ex- Direétor of the Frénch Republic, Minijter BA War, and Member v the aA Pa Py sac Paris:1797. «Trae 4 CON TE N T's: Tranflated from the French, and illuftrated with Notes, by Witt1aMm Dickson, LL.D. ./ Page 222, 335 Account iof C. F. DamBerGER’s Travels through the inte- rior Parts of Africa, yen the Cape of Good Hope te Morocco - - 240, 353 An Effay to illuftrate na Principles of Compofition as con- neéled with spake Painting. Ey Mr. EpwarpD Dayes . 293, Letter from Profeffar DE Carro to Dr. PEARSON, on the Vaccine Inoculation - - 305 Letter from Joun Branson, E/g. Sara to Dr. PEAR- son, on the Vaccine Inoculation - . 308 Report of C. Nowe.t, M. D. of Boulogne, Corre/pondent of the Committee of Medicine, commiffio med to repeat at Paris the Experiments refpeéting the Vaccine Inoculation, to'C. MasEvet, Sub- Rime ad Difiria nh eateexe- Jur-Mer 309 Extra of a Tae from Dr. SAM. 7 Mircuitz, Pro- Seller of Chemifiry in Columbia College, to Mr, TILLocH 326 Extra& of a Letter from Profeffor ABILDGAARD, Secretary to the Royal Society at Copenhagen, to C. Huzarp, Member of the French National ister, on the Quantity of Carbon in the Blood - - 328 Analyfis of the Hee -flowe, or Mellite. By C. Vau- QUELIN a 29 3 Obfervations on the Effects ES TH fake place from the De- Struétion of the Membrana Tympani of the Kar. By Mr, Astiey Cooper. In a Letter to EVERARD Home, Ejg. F.R.S. by whom fome Remarks are added 359 Analyfis of a Stone called the Gadolinite; with an Account of fome of the Properties of the new Earth it contains. By C, VAUQUELIN ~ ~ - 366 New Publications 78, 1795 279 375 intelligence and Mi ae ees Atticles 85, 181, 283, 378 sab. ye “woth ' 3) gi era pore * Pe ~ vith natn aK cis ae Fue the aA a #0, ANS zit eet ie a, ae ret é nm Se pet a THE PHILOSOPHICAL MAGAZINE. OCTOBER i800. 1. Thoughts on Colouring, and particularly with a Retrofpe to the Method ufed by the Venetians in the Mechanical Part of the Art, and io their Method of Arranging the Tints. A theory founded on experiment, and not affumed, is always good for fo much as it explains. Burke, SIR, INCE I troubled you with a paper on the fubje& of Venetian colouring*, I have paid particular attention to fuch pictures of that fchool as have occafionally come under” my noticé, and, in my inquiry, I have been much aided by thofe in the Orleans colleétion ; but, from all the obfervations I have been able to make, I cannot help concluding that they never thought of the abforbent ground, on which I made fome remarks in my laft, and that the dark red ground never formed a part of the picture. Thofe conclufions I feel authorifed in making from the general tendency in the ab- forbent grounds to produce a hardnefs, a thing never oc- curring in the pictures of the Venetians ; and that the ground never entered into part of their pictures is evident from their being painted folid throughout, and the /badows glazed on a body of colour. I fhall, with a view further to illuftrate the fubje&t, introduce (occafionally as quotations) fuch remarks on colouring as I made in my catalogue immediately on my viewing the pictures in the collection above alluded to, * See Vol. IV. — Vor, VII. Ba On 4 Thoughts on Colouring. On locking into the Venetian pictures (particularly thofe of Titian and Paul Veronefe), I found that they had all been prepared with colder colours than the finifhing ones, and that there was one general colour which prevailed throughout the fhadows; this obfervation induced me to make the following remark: ‘ the Venetians appear to have prepared their pic- tures in the flefh, and its fhadow and draperies, in a colder ftate, and glazed or fcumbled them with warmer colours.”’ Qne of the greateft confiderations with the artift is to ac- quire the true tone of the fhadow and its dinfy fhadow; to do this he muft ufe fuch colours as will moft readily fympa- thife with each other in mixing: to this end it will be found that ivory black, Indian red, and white, will form the beft general fhadow colour, which may in the flefh be improved with vermilion in the reflections. The ivory black, and white, improved with lake, produces a moft beautiful pearly demi-tint for delicate flefh, and at the fame time one of the trueft and moft clean that can be acquired. Ivory black with Indian red, or lake, glazes finely, and may be highly improved, when dry, with brown pink, or afphaltum, ufed with drying oil. This is very like the method I formerly mentioned *, as practifed by that great man Sir Jofhua Rey- nolds, to acquire his fhadows, and whofe method of colour- ing was truly Venetian, accompanied with a chiaro /curo they were ftrangers to, and a tafte in his portraits unexam- pled. Thofe who choofe to try, will find their advantage in making the fhadow colour of ivory black, vermilion, and white (as mentioned in Vol. IV.), which will work cleaner _ than any other combination; and which colours, with the addition of burnt ochre in dark complexions, and yellow ochre in the lights, will be quite fuffictent for all the pur- pofes in flefh for firft and fecond colouring, or till the draw- ing is fixed; the whole being afterwards finifhed by glazing, to give depth to the fhadows, and enrich and improve the colouring. Tintoret appears to have'forwarded his pictures to nearly their full effet, with a pearly colour of black, red, and white, and to have acquired all his tints by glazing with a pure tranfparent colour, invariably leaving the lights white * See Vol. IV. to Thoughts on Colouring. 5 _to give them brilliancy: Titian, on the contrary, dead-com doured as near nature as poffible, oply enriching his colours by glazing, and keeping the fhadows as near of a tone as poffible. The abfurdity of ufing dark grounds mutt be ob- vious to every one who has had the leaft praétice, from the tendency in the white, and all the lighter tints, to fink into the ground; which accounts for the darknefs of many of the old pictures, and more efpecially thofe that have been painted thin. However defirable it may be to have one’s pictures well coloured, its prefence will by no means com- penfate for the lofs of dignity of compofition, accuracy of drawing or breadths: he that is content to pleafe by the Hlufion of colour, or that flatters the eye by an induftrious difplay of tints, muft not expect to rank high in the art. «« Mind, mind alope, (bear witnefs Earth and Heav’a!) «* The living fountains in itfelf contains “ Of beauteous and fublime: here hand in hand «6 Sit paramount the Graces.” AKENSIDE. I have often been. led to think that the exquifite clearnefs obfervable in fome of the pictures of Rubens, arifes at this time (in a great degree) from his having painted them on- white, or, at any rate, light grounds; the advantage of which will be obvious to any one that choofes to try the following experiment: that is, to fpread any light ‘colour (as a flefh colour for inftance) on a ground prepared half white and half dark; in the courfe of two or three days, that on the white ground will appear clear, while the latter. will have - funk many degrees into the under dark colour. Another advantage attending a light ground is, that the pi€ture is not ‘fo liable to be injured by cleaning, not to mention its wear- ing better: two of the fineft pictures, by Titian, in the Or- leans collection (Diana and Acteon, and Diana and Califo), bear ftrong teftimony to the truth of the above obfervation; the former being in fine prefervation, owing to its haying been painted with a great body of colour; while the latter having only a thin coat, the dark red. ground appears through the flefh, to its irreparable injury. This evil would in a great meafure have heen avoided, had the ground been light ; 6 Thoughrs on Colouring. light ; and it is evident that the ground was not intended to make the leaft part of the effect in the picture originally, as the thinnefs in the colour above alluded to, looks as if owing to accident, and the hafte of a man who could fell all the pictures he painted. I have alresdy mentioned that the beft general fhadow colour is ivory black, &c. which, if the lights and middle tints are coloured as near nature as poffible, may be enriched by glazing; or the glazing may be done on the middle tints, and the lights of one general hue laid on them, which ap- pears at times to have been the pratice of Titian. The fol- lowing remark on the piture of Diana and Califto, may ferve as a further illuftration :—‘ There appears to be yellow in all the lights, even the blue; I therefore infer, that they confidered the light as giving a colour, or of changing, in a fmall degree, the local colour of the obje€ls, and that their principle of colouring was thus: the lights on the objedis par- took of the colour of the light, the middle tints gave the local colour, and the foadows warm, and pretiy much of one bue.’* A piture painted on the above plan, will have a harmonious and pleafant effect. I with the artifts of any eminence would communicate the refult of their practice; much good would arife from it. Fine writing is not a neceffary requifite; for, in matters in- tended to infiruct, clearnefs will more than compenfate for want of elegance: fuch a conduét would contribute to re+ move many of the practical difficulties the ftudent labours under; an inconvenience | myfelf have greatly felt. It is very rarely that you fee a diftinét or whole colour in the Venetian pictures; as their blues feldom go beyond a violet, and the reds, ‘a crimfon. ‘* In all the pictures in the room (Orleans collection) by this mafter (Titian), no one decifive colour is to be feen, as they are all broken to corre- fpond.with each other: that is, the red are broken with yel- low, yellows with red, and fo on. He appears to have been particularly careful not to introduce blue or cold colours, and, when they do occur, it is only in fmall quantities.” I would by no means have it underftood that I with to tie the artift downto a particular manner of colouring; one 9 of Thoughts on Colouring. Y of our profeffional evils is looking too much to art for its rules; but I believe a great fource of the pleafure derived from the fight of the Venetian pictures, is their comfortable warm maffes: great caution however will be required to diftinguifh between a glowing and a glaring colour ; as we are apt to ad- mire what is fhowy, before we can diftinguifh what is beau- tiful. I have frequently had occafion to remark the fatisfaca. tion expreffed by the fpectators on viewing a warmly coloured picture, and the degree of comfort it has appeared to impart: this has frequently led me to reflect on the application of colour to medical purpofes, as in the ague or fever, or how much the mind might be tranquilifed by the room being of a particular colour; every one is fenfible of the effect of that beautiful amber-coloured light that at times prevails on our ~ fummer’s evenings, and which is fo highly congenial to health and life *. In all cafes the good fenfe of the artift muft be ufed, for ‘the colouring that fuits one fubject will not agree with an- other; moft of the Venetian pictures that I have feen, have been of the pleafing or ornamental caft, which require more decoration of colour than the higher walks of hiftory, but I have never been able to prevail on myfelf to believe the moft fublime fubje& would be hurt by grouping the colours. It would be worth inquiring how far the painter might be be- nefited (as the poet certainly is) by confidering Polonia as indicative of the paffions, and applying them accordingly : the fiery reds convey the idea of anger, and in this fenfe are eften ufed ; . ; «* Should intermitted vengeance arm again “« His red right hand to plague us ? MILTow. * The faét is it is ufed medically, as in the cafe of weak eyes, but not on fo extenfive a plan as it might be; for inftance, if the walls of the chambers where infane people are confined were to be plaftered to an uni-~ form furface, and coloured of a ftill green, as near the tranquil colour of grafs as poffible, it is probable it would contribute to compofe the fpirits ; inftead of which the fight is diftraéted, sand in all probability the mind fet to work in decyphering the fiffures and irregularities in their furrounding old walls, which may ultimately end in provoking that propenfity to- wards drawing exprefied by many unfortunate people, & exprenee by y Peep Addifon $ Thoughts on Colouring, Addifon, in his Cato, heightens his figure by * red with uncommon wrath.” Gray and the foft green convey the idea of tranquillity; and the dark blue gray, and brown, of foftow and melancholy : es ——— me, goddefs, bring, “ To arched walks of twilight groves, «© And fhadows brown, that Sylvan loves, “ Of pine ——— = Milton’s 11 Penferofoe « Mellow tones ever affociate with gentle, and fharp ones with violent, emotions. In the practice of glazing, the lefs. oil is ufed the better; if the part is rubbed out, and wiped dry with a filk rag (an old filk handkerchief is good, but a piece of wath leather does beft), then the fie fhould be driven as much as poffible and often repeated if neceffary, except it fhould be a colour that requires drying oil: and, I believe, on moft oceafions, if the part is hard, drying oil and turpentine, in equal parts, will be found as good a vehicle as any. In what the artift terms /cumbling, or ufing an opaque colour thin, it fhould be driven with a ftiff pencil, and as little oil as poffible. Asa conclufion to the prefent paper, I fhall add the funy of my es on the Venetian pictures in the Orleans eol- leétion :—** From the pictures of Titian and Paul Veronefe ‘TE judge they were particularly careful to group the warm colours; to avoid the ufe of blue and cold ones; never to fufjer them to interrupt the principal mafs of light, which with them is always compofed of warm colours; that the cold colours were fparingly introduced for the purpofe of fupport- img the blue in the fky or diftance, as in No. 123, 240, 249%, and never on the principal obje&. In many of their pictures there is a total exclufion of the cold colours, as in 169 and 384; in others, where the colours of the objects are all warm, the fkies are broken either with warm purple clouds, or the blue of the element reduced to gray, as in 49, 291, * 123, Holy family in a landfcape, Titian; 240, Diana and Aéteon, Titian; and 249, Diana and Califto, Titian; 169, an Allegory, and a8x, 2 ditto, Paul Verenefe, i 220. atateall Refrangibility of the invifible Rays of the Sun. 9 220*; their fhadows prepared with a gray or pearly colour, enriched with glazing: thcir draperies glazed; flefh glazed, and fcumbled with rich virgin tints; and the whole harmo- nifed by the high lights being fouuhed on with a warm yel- low colour, nearly oF the tone of the high lights of the flefh, as in remark on No. 249 f.”’ I cannot help adding, there were not any pictures in the Orleans colleétion which (in point of colour) looked fo agreeable as the Venetian, owing to their principal mafs of colour being invariably warm ; wherever the contrary occurred, the effect on the eye was unpleafant; as alfo when the great mafs was difturbed by the intervention of a cold colour. I remain, Sir, your humble fervant, E. DAYES. Francis-ftreet, April 11, 1800. The Editor of the Philofophical Magazine. Il. Experiments on the Refrangibility of the invifible Rays of the Sun. By Witu1amM HerscueL, LL.D. F-.R.S.} Ix that fe€tion of my former paper which treats of radiant heat, it was hinted, though from imperfect experiments, that the range of its refrangibility is probably more extenfive than that of the prifmatic colours; but, having lately had fome favourable funfhine, and obtained a fufficient confirm- ation of the fame, it will be proper to add the following ex- periments to thofe which have been given :— I provided a fmall ftand, with four fhort legs, and covered it with white paper§. On this I drew five lines, parallel to one end of the ftand, at half an inch diftance from each other, but fo that the firft of the lines might only be + of an * 249, Venus rifing from the fea, Titian; 211, the education of Cupid, Titian; 220, Europa, Titian. + Diana and Califto, Titian. { From the Tran/aftions of the Royal Society for 1800. § See Plate I. fig. 2. Vou, VIII, C inch Ig Experiments on the Refrangibility of inch from the edge. Thefe lines I interfeéted at right angles. - with three others; the fecond and third whereof were, re- fpectively, at 2} and at 4 inches from the firft. The fame thermometers that have before been marked No. 1, 2, and 3, mounted upon their fmall inclined planes, were then placed fo as to have the centres of the fhadow of their balls thrown on the interfection of thefe lines. Now, fetting my little ftand upon a table, I caufed the prifmatic {peétrum to fall with its extreme colour upon the edge of the paper, fo that none might advance beyond the firft line. In this arrangement, all the fpectrum, except the vanifhing laft quarter of an inch, which ferved as a direction, paffed down by the edge of the ftand, and could not interfere with the experiments. I had alfo now ufed the precaution of darkening the window in which the prifm was placed, by fixing up a thick dark green curtain, to keep out as much light as convenient. The thermometers being perfeétly fettled at the tempera- ture of the room, I placed the ftand fo that part of the red colour, refraéted by the prifm, fell on the edge of the paper, before the thermometer No. 1, and about half way, or 14 inch, towards the fecond: it confequently did not come be- fore that, or the third thermometer, both which were to be my ftandards., During the experiment, I kept the laft ter- mination of vifible red ‘carefully to the firft line, as a limit affigned to it, by gently moving the ftand when required ; and found the thermometers, which were all placed on the fecond line, affected as follows: No.1, . No.2. No, 3. | Here the thermometer No. 1 45 45 44 rofe 6: degrees in 10 mi- 49 45 “44. nutes, when its centre was 51 442 44 placed + inch beyond vi- 50% 434 43> fible light. In order to have a confirmation of this fat, I cooled the thermometer No. 1, and placed No. 2 in the room of it: 1 alfo put No, 3 in the place of No. 2, and No. 1 in that of No. 3; and, having expofed them as before, arranged on the fecond line, I had the following refult : No of the invifible Rays of the Sun. II No, 2. No. 3. No. 1.) Here the thermometer No. 2 44 44 45 |. rofe 23 degrees in 12 mi- 47 44 45 nutes; and being, as has 462 44 45 been noticed before, much 462 44 45 more fenfible than No. 1, it came to the temperature of its fituation a fhort time; but I left it expofed longer, on purpofe to be perfectly affured of the refult. Its fhowing but 2% degrees atlvance, when No. 1 fhowed 6!, has alfo been accounted for before. It being now evident that there was a refraction of rays coming from the fun, which, though not fit for vifion, were yet highly invefted with a power of occafioning heat, I pro- ceeded to examine its extent as follows: The thermometers were arranged on the third line inftead of the fecond ; and the ftand was, as before, immerfed up to the firft, in the coloured margin of the vanifhing red rays. The refult was thus: No. T. No. 2. No. 3.4 Here the thermometer No. 1, 46 46 45+ rofe 5; degrees in 13 mi- 50 46% 46 nutes, at I inch behind ries 463 464 the vifible light of the red 525 47 46% Pays I placed now the thermometers on the fourth line inftead of the third; and, proceeding as before, I had the following refult : No. 1. No. 2. No. 3.4 Therefore, the thermometer 48+ 48+ 472 No. 1, rofe 3; degree in ple 482 aye 10 minutes, at tt inch beyond the vifible light of the red rays. I might now have gone to the fifth line; but fo fine a day, with regard to clearnefs of fky and perfect calmnefs, was not to be expected often at this time of the year; I therefore haftened to make a trial of the other extreme of the prifmatic {fpectrum. This was attended with fome difficulty, as the illumination of the violet rays is fo feeble, that a precife ter- mination of it cannot be perceived. However, as well as could be judged, I placed the thermometers one inch be- yond the reach of the violet rays, and found the refult as follows : C2 No. 12 Experiments on the Refrangibility No.1. No. 2. No. 3.7 Here the feveral indications ° 48 48 | Bre. of the thermometers, two 48 48 — 472 of which, No. 1 and 2, 48 47% 47 were. ufed as. variable, 48% An 47 while the third was kept 48 48 Sin” vfs as the ftandard, were read off during a time that lafted 12 minutes; but they afford, as may be feen by infpection, no ground for afcribing any of their fmall changes to other caufes than the accidental dif- turbance which will arife from the motion of the air in a room where fome employment is carried on. I expofed the thermometer now to the line of the very firft perceptible violet light, bat fo that No. 1 and 2 might again be in the illumination, while No. 3 remained a ftandard. The refult proved as follows : No. 1. No. 2. No. 3: Here the thermometer No. 1 ~ "48 48 Ay rofe 1 degree in 15 mi- 48% 48 Age nutes; and No. 2. rofe 482 482 473 z degree in the fame 49 48> 475 time. From thefe laft experiments, I was now fufficiently per- fuaded, that no rays which might fall beyond the vielet, could have any perceptible power either of illuminating or of heating; and that both thefe powers continued together throughout the prifmatic fpeétrum, and ended where the fainteft violet vanifhes. A very material point remained ftill to be determined, which was, the fituation of the maximum of the heating power. As I knew already that it did not lie on the violet fide of the red, I began at the full red colour, and expofed my ther- mometets, arranged on a line, fo as to have the ball of No. 1 in the midft of its rays, while the other two remained at the fide, unaffected by them. No.1, No.2. No. 3.+ Here the thermometer No. 1 48% 48+ 48 rofe 7 degrees in 10 mi- Bae 48" 48 \ nutes, by” an expofure te 55s 48t 48 the full. red coloured rays. I drew back the fiand, till the centre of the ball of No. 1, was juft at the vanithing of the red colour, fo that half its ball was within, and half without, the vifible rays of the fun. No. of the invifible Rays of the Sun. 13 No. 1. No. 2, No. 3°> Here the thermometer No. 1 He i 43 rofe 8 degrees in 10 mi- 57 49. rhe nutes. By way of not lofing time, in order to conneét thefe laft obfervations the better together, I did not bring back the thermometer No. 1, to the temperature of the room, being already well acquainted with its rate of fhowing, compared to that of No. 2, but went on to the next experiment, by withdrawing the ftand, till the whole ball of No. 1 was completely out of the fun’s vifible rays, yet fo as to bring ‘the termination of the line of the red colour as near the out- fide of the ball as could be without touching it. No. I. No. 2. No: 3.> Here the thermometer No. 1, 57 49 48 rofe, in 10 minutes, an- 58E 492 49 other degree higher than 59 “nl SOR 49+ in its former fituation it 59 50 AQz could be brought up to; and was now 9g degrees above the ftandard. The ball of this thermometer, as has been noticed, is exactly half an inch in diameter ; and its centre, therefore, was + inch beyond the vifible illumination, to! which no part of it was expofed. It would not have been proper to compare thefe laft obferv- ations with thofe taken at an earlier period this morning, in order to obtain a true maximum, as the fun was now more powerful than it had been at that time; for which reafon I caufed the line of termination of vifible light, now to fall again juft 4 inch from the centre of the ball, and had the following refult : No. I. No. 2. No. 3.. And here the thermometer — 5OL 5Oz 50 No. 1, rofe, in 16 minutes, 57+ 50 49 = 83 degrees, when its cen- 585 Roe 495 tre was * inch out of the 582 50 » AOE vifible rays of the fun. Now, as before we had a rifing of nine degrees, and here 83, the difference is almoft too trifling to fuppofe that this latter fituation of the thermometer was much beyond the maximum of the heating power; while, at the fame time, the experi- ment fufficiently indicates that the place inquired after, need not be looked for at a greater diftance. ’ + 4 t 14 Experiments on the Refrangibility Tt will now be eafy to draw the refult of thefe obfervations into a very narrow compais. The firft four experiments prove that there are rays coming from the fun which are lefs refrangible than any of thofe that affect the fight. They are invefted with a high power of heating bodies, but with none of illuminating objects; and this explains the reafon why they have hitherto efcaped un- ~ noticed. My prefent intention is, not to affion the angle of the leaft refrangibility belonging to thefe rays, for witch purpofe more accurate, repeated, and extended experiments are re- ~ quired. But, at the diftance of 52 inches from the prifm, there was ftill a confiderable heating power exerted by our invifible rays, one inch and a half beyond-the red ones, meafured upon their projection on a horizontal plane. I have no doubt but that their efficacy may be traced fill - fomewhat further, The fifth and fixth experiments fhow that the power of heating is extended to the utmoft limits of the vifible violet rays, but not beyond them; and that it is gradually impaired as the rays grow more refrangible. The four Jaft experiments prove that the maximum of the heating power is vefted among the invifible rays, and is pro- bably not lefs than half an inch beyond the Jaft vifible ones when projected in the manner before mentioned. The fame experiments alfo fhow, that the fun’s invifible rays, in their lefs refrangible ftate, and confiderably beyond the maximum, ftill exert a heating power fully equal to that of red-coloured | light; and that, confequently, if we may infer the quantity of the efficient from the effeét produced, the invifible rays of the fun probably far exceed the vifible ones in number. To conclude, if we call dight, thofe rays which illuminate objects, and radiant heat, thofe which heat bodies, it may be inquired, Whether light be effentially different from ra- diant heat? In anfwer to which I would fuggeft, that we are not allowed, by the rules of philofophifing, to admit two different caufes to explain certain effects, if they may be ac- rpms for by one. A beam of radiant heat, emanating from of the invifible Rays of the Sun, 1S from the fun, confifts of rays that are differently refrangible. The range of their extent, when difperfed by a prifm, begins at violet-coloured light, where they are moft refracted, and have the leaft efficacy. We have traced thefe calorific rays throughout the whole extent of the prifmatic fpetrum, and found their power increafing, while their refrangibility was leflened, as far as to the confines of red-coloured light. But their diminifhing refrangibility, and increafing power, did not {top here; for we have purfued them a confiderable way be- yond the pri/matic /peG&rum, into an invifible ftate, full ex- erting their increafing energy, with a decreafe of refrangi- bility, up to the maximum of their power; and have alfo traced them to that ftate where, though {till lefs refracted, their energy, on account, we may fuppofe, of their now fail- ing denfity, decreafed pretty faft; after which, the invifible thermometrical /pectrum, if I may fo call it, foon vanifhed. If this be a true account of folar heat, for the fupport of which I appeal to my experiments, it remains only for us to admit, that fuch of the rays of the fun as haye the refrangi- bility of thofe which are contained in the prifmatic fpeGtrum, by the conftruction of the organs of fight, are admitted under _the appearance of light and colours; and that the reft, being ftopped in the coats and humours of the eye, aét upon them, as they are known to do upon all the other parts of our body, by occafioning a fenfation of heat. Slough, near Windfor, March 17, 1800. Explanation of Plate T. Sig: 2. AB, the {mall ftand. 1, 2,3, the thermometers upon it, CD, the prifm at the window. E, the fpe&rum, thrown upon the table fo as to bring the laft quarter of an inch of | the red colour upon the ftand. TI, Ex- * Cr" Ill. Experiments on the folar and on the terrefirial Rays that occafion Heat; with a comparative View of the Laws to which Light and Heat, or rather the Rays which occafion them, are fubje&, in order to determine whether they are the fame, or different. By WiLLtamM HerscHeEt, LL.D. FOR ae" Part I. Pie word beat, in its moft common acceptation, denotes a certain fenfation, which is well known to every perfon. The caufe of this fenfation, to avoid ambiguity, ought to have been diftinguifhed by a name different from that which is ufed to point out its effect. Various authors, indeed, who have treated on the fubject of heat, have occafionally added certain terms to diftinguifh their conceptions, fuch as, latent, abfolute, fpecific, fenfible heat; while others have adopted the new expreffions of caloric, and the matter of heat. None of thefe defcriptive appellations, however, would have com- pletely anfwered my purpofe. I might, as in the preceding papers, have ufed the name radiant heat, which has been introduced by a celebrated author, and which certainly is not very different from the expreffions I have now adopted ; but, by calling the fubje& of my refearches, the rays that occafion heat, I cannot be mifunderftood as meaning that thefe rays themfelves are heat; nor do I in any refpect engage myfelf to fhow in what manner they produce heat. From what has been faid, it follows that any objeétions that may be alleged from the fuppofed agency of heat in other circumftances than in its ftate of radiance, or heat- making rays, cannot be admitted againft my experiments. For, notwith{tanding I may be inclined to believe that all phzenomena in which heat is concerned, fuch as the expan- fion of bodies, fluidity, congelation, fermentation, friction, &c. as well as heat, in its various ftates of being latent, fpe- cific, abfolute, or fenfible, may be explained on the principle of heat-making rays, and vibrations occafioned by them in * From the Tranfaclions of the Royal Society for 1800~ the Experiments on the Rays that oceafion Heat. - “17° the parts of bodies ; yet this is not intended, at prefent, to be any part of what I fhall endeavour to eftablith; I mutt alfo remark that; in ufing the word rays, I do not mean to oppofe, much lefs to countenance, the opinion of thofe philofophers who ftill believe that light itfelf comes to us from the fun, not by rays, but by tke fuppofed vibrations of an elaftic ether, every where diffufed throughout fpace; I only claim the fame privilege for the rays that occafion heat, which they are willing to allow to thofe that illuminate objects. For, in what manner foever this radiance may be effected; it will be fully proved hereafter that the evidence either for rays, or for vibrations which occafion heat, ftands on the fame foundation on which the radiance of the illu- minating principle, light, is built. . In order to enter on our fubje& with fome regularity, it ‘will be neceffary to diftiriguifh heat into fix different kinds, three whereof are folar, and three terreftrial; but, as the di- vifions of terreftrial heat ftrictly refemble thofe of folar, it will not be neceffary to treat of them feparately; our fubjeé&, thete- fore, may be reduced to the three following general heads : We fhall begin with the heat of luminous bodies in ge- neral, fuch as, in the firft place, we have it direétly from the fun; and as, in the fecond, we may obtain it from terreftrial flames, fuch as torches, candles, lamps, blue- lights, &c. Our next divifion comprehends the heat of coloured ra- diants. This we obtain; in the firft place, from the fun, by feparating its rays in a prifim; and, in the fecond, by having recourfe to culinary fires openly expofed. The third divifion relates to heat obtained from radiants, where neither light nor colour in the rays can be perceived. This, as I have Thowbss is to be had, in the firft place, di- rectly from the fun, by means of a prifm applied to its rays ; and, in the fecond, we may have it from fires inclofed in ftoves, and from red-hot iron cooled till it can no longer be feen in the dark, Befides the arrangement in the order of my experiments which would arife from this divifion, we have another fubjeét to confider. For, fince the chief defign of this paper is to Vou. VIII. D give 18 Experiments on the Solar; and on the - ‘give a comparative view of the operations that may be per- formed on the rays that occafion heat, and of thofe which ‘we already know to have been effected on the rays that oc- cafion light, it will be neceffary to take a fhort review of the latter. I fhall merely felect fuch fats as not only are per- ~fe@tly well known, but efpecially fuch as will anfwer the in- tention of my comparative view, and arrange them in the following order. 1. Light, both folar and terreftrial, is a fenfation occa- ‘fioned by rays emanating from luminous bodies, which have a power of illuminating objects; and, according to circum- ftances, of making them appear of various colours. 2. Thefe rays are fubject to the laws of reflection. 3. They are likewife fubjeét to the laws of refraction. 4. They are of different refrangibility. 5. They are liable to be ftopped, in certain proportions, when tranfmitted through diaphanous bodies. 6. They are liable to be fcattered on rough furfaces. ‘7, They have hitherto been fuppofed to have a power of heating bodies; but this remains to be examined. The fimilar propofitions relating to heat, which are ins tended to be proved in this paper, will ftand as follows: 1. Heat, both folar and terreftrial, is a fenfation occa fioned by rays emanating from candent fubftances, which have a power of heating bodies. 2. Thefe rays are fubject to the laws of refleétion. 3. They are likewife fabject to the laws of refraction, 4. They are of different refrangibility. . 5. They are liable to be ftopped, in certain proportions, When tranfmitted through diaphanous bodies. 6. They are liable to be feattered on rough furfaces. 7. They may be fuppofed, when in a certain flate of energy, to have a power of illuminating objects; but this remains to be examined. Before I can go on, I have to mention that the number of experiments which will be required to make good all thefe points, exceeds the ufual length of my papers; on which account, I fhail divide the prefent one into two parts. Pro- ceeding, therefore, now to an inveftigation of the three firft ) ~~ heads Terreftrial Rays that .occafion Heat. 19 heads that have been propofed, I referve the three next, and a difcuffion which will be brought on by the feventh article, for the fecond part. 1ft Experiment. Refle&tion. of the Heat of the Sun. I expofed the thermometer, which in.a former paper has been denoted by No. 3, to the eye-end of a ten-feet New- tonian telefeope, which carried.a Camera eye-piece*, but na éye-glafs. When, by proper adjuftment, the focus came to the ball of the thermometer, it rofe from 52 degrees to 110; fo that rays which came from the fun, underwent three re- gular reflections; one on a concave mirror, and the other two on two plain ones. Now thefe rays, whether they weré thofe of light or not, for that our experiment cannot afcer- tain, had a power of occafioning heat, which was manifefted in raifing the thermometer 58 degrees. 2d Experiment. Reflection of the Heat of a Candle. At the diftance of 29 inches from a candle; I planted a fmall fteel mirror, of 3,+. inches diameter, and about 23 inches focal length +. In the fecondary focus of it, I, placed the ball of the thermometer which in my paper has been marked No. 2; and very near it, but out of the reach of reflection, the thermometer No. 3. Having covered the mirror till both were come to the temperature of their ftations, I began as follows: bio INY02, No. 3. }) Here, in five minutes, the Inthe Focus, Standard. | thermometer No. 2, re- o! 54 54 ceived 3+ degrees of heat [ 55 54 from the candle by re- 2 56 54 ¢ fleéted rays. I now covered 3 57 54 the mirror, but left all the 4 57 54 ; reft of the apparatus un- 5 Ly 54 Jj touched. ; eed a 3s Here, in fix minutes, the ther- ol 578 ; 54 i mometer loft the 3; degrees 3 5 5h 34 of heat again, which it had ro 55 c 4 gained before. I uncovered .. 4 54 the mirror once more. * See Phil, Tranf. Vol. LX XII. p. 176. + See Plate I, fig. x, D2 0 20 Experiments on the Rays that occafion Heat. of 54 54) And, in five minutes, the 3* degrees i; 56 54 of heat were regained, In confe- 3r 57 54( quence of which we are affured ve 544 that certain rays came from the 5 candle, fubjeét to the laws of refle€tion, which, though they might not be the rays of light, for that our experiment does not determine, were evidently invefted with a power of heat- ing the thermometer placed in the focys of the mirror. 3¢@ Experiment. Refleétion of the Heat that accompanies the Solar prifmatic Colours. In the fpectrum of the fun, given by a prifm, I placed my fmall fteel mirror, with a thermometer in its focus*, It was covered by a piece of pafteboard, which, through a proper opening, admitted all the vifible colours to fall on its polithed furface, but excluded every other ray of heat that, might be either on the violet or on the red fide, beyond the fpectrum. Then, placing the apparatus fo as to have the thermometer in the red rays, but keeping the mirror covered up till the thermometer became fettled, I found it flationary. at 58°. Uncovering the mirror, I had as follaws: No. 2.) Here, in two minutes, the thermometer rofe ’ of 58 } 35 degrees, by feflested heat. I covered 2 93 the mirror again, and, in a few minutes, the thermometer expofed to the direct prifmatic red came clown to 58° again. And thus the prifmatic colours, if they are not themfelves the heat-making rays, are at lea{t accom- panied by fuch as have a power of occafioning heat, and are liable to be regularly reflected. 4th Experiment. Reflection of the Heat of a red-hot Poker. I placed the fmall fteel mirror at twelve inches from a red- hot poker, fet with its heated end upwards, in a perpendi- cular pofition, and fo elevated as to throw. its rays on the mirror. The thermometer No. 2, was placed in its fe- condary focus, and had a fmall pafteboard fereen, to guard its ball from the dire&t heat of the poker. * See Plate II. fig. 1. + See Plate I. fig. 1. Experiments refpecting Heat. I No. 2. Here, in 14 minute, the thermo- ro 544 meter rofe 38£ degrees by re- 4. 93 flected rays; and, when the . Icovered the mirror. mirror was covered up, it fell 3! 65 in the next 15 minute, 28 de- grees. On which account we cannot but allow that certain rays, whether it be thofe that fhine or not, iffue from an ignited poker, which are fubject to the regular laws of re- fieCtion, and have a power of heating bodies. [To be continued. } IV. Account of fome interefting Experiments, performed at the London Philofophical Society, refpecting the Effects of Heat, excited by a Stream of Oxygen Gas thrown upon zgnited Charcoal, on a number of Gems and other refrac- tory Subfiances fubmitted to its Adtton; with a ek up of the Apparatus employed *, * I T is well known that no methods with which we are yet acquainted, are capable of exciting a degree of heat which is at all to be compared with that produced by the agents em- ployed in the operations about to be defcribed. The ftriking experiment of the deflagration of iron-wire in oxygen gas is frequently accompanied with phenomena, not hitherto at- tended to as they deferve to be, which furnifh ftrong proofs in fupport of this affertion. A receiver, or bel]-glafs, that will hold about two quarts, with an aperture at the top of about one inch in diameter (fuch as is now ufually denominated “ a deflagrating glafs’’), is charged with axygen gas, in the ufual manner, on the fhelf of a pneumatic tub, the aperture being {topped with a cork, or, which is better, coyered with a piece of flate, or other fuitable fubftance, ground flat fo as to lie clofely on its edges. If the veffel be then removed from the fhelf into an earthen plate, with a fufficient quantity of water in it to cover the edge .of the receiver, and prevent the efcape of the gas from * From the unpublifhed minutes of the Society. We are promifed, fem the fame quarter, feveral other interefting communicatiens. below, 22 Experiments refpelting Heat, below, the phenomena will be the better obferved. The wire being prepared by coiling it up into a fpiral, like a.cork- fcrew, inferting its fuperior extremity into_a cork or cover, adapted to the fuperior aperture of the receiver, and winding a little cotton round its lower extremity; the cotton is to be very flightly dipped in the melted tallow of acandle, and then fet on fire. This gives fuch a degree of temperature to thé wire as occafions it.to take fire when introduced into the gas, which is done by removing the cork or cover from the re-. ceiver and fubftituting that containing the wire at the mo- ment of its ignition. The wire then begins to deflagrate, and little globules of melted iron are formed at its extremity; each falling off in fucceffion when it acquires a weight fufficient to detach it from the remainder of the burning metal. One cireum- ftance, which cannot fail to imprefs the mind ftrongly with the intenfity of the heat produced in this experiment, is, that many of thefe globules, though they muft neceflarily firft pafs through the water in the plate, are always found, even when the water is two inches or upwards in depth within the receiver, to have fufed the vitreous glazing completely through, and to be fo ftrongly united with it, that they can- not be afterwards feparated_ without detaching the glazing, together with the femi-vitrefied and flag-like globule which adheres to it. Another effet, which may be produced at pleafure, fur-’ nifhes, if poffible, a ftill more convincing proof of the in- tenfity of the heat. The drops of liquid iron generally ac- quire the fize of a fmall pea before they detach themfelves. Tf the experimenter, watching the moment, give a quick jerk to the wire, and make the globule ftrike the fide of the glafs, it will often be found to melt its way through i an inftant, leaving a hole in the glafs, whofe edges are as well defined as if it had been drilled. The glafs ufed on this occafion ih the Society, and which is fuch a one as Mr. Var- ley, the experimenter to this inftitution, makes ufe of in his- public lectures, is generally as thick as a ftrong drinking tumbler; and it is worthy of remark, that, though in charg- ing the glafs, perhaps not a minute before the experiment, it ‘Experiments re[peSing Heat, 123 at muft neceffarily be immerfed in water, neither its coldnefs or humidity hinders the paflage of the globule, which feems to make its way through with as much eafe as it would through a piece of writing paper. When the jerk is lefs powerful, the ball of iron will fometimes not go quite through, but lodge itfelf in the fubftance of the glafs, which it in that cafe generally foftens fo as to raife a protuberance on the outfide. The contemplation of fuch powerful effets of heat as thefe, “induced the Society, on the fuggeftion of a very worthy , member, and zealous cultivator ef the feiences, Mr. Francil- jon, to enter upon the prefent experiments, which were per- formed upon the different fpecies of gems hereafter enume- rated; for all of which the Society was indebted to the po- litenefs of the gentleman who firft propofed the fubje&t, and from whoie very valuable cabinet they were accordingly fup- plied. The experiments were made in the prefence of the Society at different meetings, from 24th September to 26th Novem- ‘ber 1798, in the order in which they are here mentioned ; the prefent account being compiled from the original mi- nutes taken by Mr.’ Turton, their fecretary, with that degree of accuracy which ufually characterifes them, and which have again been compared with the gems in their prefent ftate. The apparatus employed will be defcribed at the end of the prefent communication. Diamonds. I. The firft ftone: fubjected, to experiment was a rofe dia- mond of the weight of 45ths of a carat. It was put upon a piece of compaét charcoal in which a fmall excavation had been previoufly made, and the flame of a lamp, urged by a common blow-pipe, then thrown into the "cavity. When the charcoal was ignited it was prefented to another blow- pipe, fupplied by the gafometer with an uninterrupted ftream of oxygen gas. The diamond, at the end of one minute and fifty feconds, was found to weigh only #,ths, having loft +2ths of its ori- ginal 24 Experiments refpefling Heat. ginal weight. It had loft its tranfparency, figure, and pos hture. Bergman obferves, that the diamond, urged by a very iri-’ tenfe heat, contracts a fort of foot upon its furface: no ap= pearance of this kind was obferved on the prefent occafion. The unconfumed portion of the diamond, which was re- cut after the experiment, now exhibits exaGtly the fame {pe- cies of luftre as before. It originally ‘* drew colour,”’ as jewellers term it; that is, it had 4 flight brown tinge throughout, fomewhat like that of a fmoked topaz, but very pale. It has ftill the fame colour. Mr. Fraricillon, whofe experience in matters of this nature is equal to that of moft perfons, made an obfervation on this circumftancé which deferves to be mentioned. It feems that there are fome dia- monds which, although in themfelves colourlefs, contain “ fouls’’ or ‘ fpecks,” as they are called, which are cavities filled with red, yellow, or brown earths; and thefe colours, being reflected through the tranfparent fubftance of the ftone when cut, give it the appearance of being itfelf coloured. When fuch ftones are fubjected to heat, the earth in thefe cavities turns black; the ftone after this ‘* plays colour= lefs,”? and the defe&t is cured. Thofe which * draw colour,” that is, which are themfelves tinged, undergo no change by being heated. IJ. Another diamond, which weighed £2ths of a carat; was fubjected to heat excited by oxygen gas in the fante manner as the former. At the end of 1’ 53” it was with- drawn, and was found to have loft 4£ths, or 4.4ths of its oris ginal weight. In a few feconds more, it would have en- tirely difappeared. It was indeed the intention of the Society to have produced this effect; but one of thofe fortunate cir- cumf{tances which fometimes lead to confiderable difcoveries, prefented on this occafion a phenomenon even more inter- efting than that of the total diffipation of the gem, though no lefs to have been expeéted. The diamond was at this time accidentally thrown from the charcoal, and was clearly and diflinéily feen to flame as a combuftible body in its paffage through the air. The flame was of a blueifh pearl colour, and nearly Experiments refpeéting Heat. 25 nearly three quarters of ah inch inlength. This experiment las fince been frequently repeated, and always fucceeds in nearly the fame manner. This ftone remains ftill in the ftate in which the experi- ment left it. Its figure and polifh are quite gone, and it is ftudded all over with carbonaceous matter of a fomewhat metallic brilliancy, which, on examination with a magni- fier, appears to be Shuster in union with the furface of the diamond, Amethy/fts. IIf. An amethyft, weighing 14, carat, in 40” broke into feveral pieces. At the end of 1’ "55! the fragments were withdrawn and again weighed, as there was reafon to fupeét that fome of them had flown off. Some of them, weighing =iths of a carat, were then taken and expofed to the heat for 1’ 15’, when they became fufed into one mafs, which, on cooling, again broke into feveral pieces. : The colour of the ftone is gone; the fragments are femi- tranfparent, and very much refemble fragments of cryftals of a pure white falt; fuch, for inftance, as purified nitre. The fufed mafs might perhaps have been preferved entire, if the precaution of cooling it flowly, by placing it under a muffle, or in a crucible, in a furnace, and fuffering the fire to die away gradually, had been taken; but this was not attempted. IV. Another amethyft, weighing half a carat, expofed to the heat for 5’, was fufed into a globule which is nearly {pheroidal and pretty fmooth, but full of fmali bubbles and cracks, fimilar to thofe in glafs which is threwn, when heated, into water. The whole is colourlefs and tranfparent like flint glafs, except a portion on one fide, which, having probably been leaft heated, looks like white enamel. The {tone loft ,'; part of its weight. Sapphires. V.. An oriental fapphire, weighing 17 1, carat, though Th heat was applied with caution, by expof ng it firft to the aétion of a lamp urged by a common blow-pipe, broke into three pieces, but fecmed to have undergone no other change Yor, VIII. E at 26 Experiments refpetting Heat. at the end of.one minute. The fragments were then fub- jected to the heat excited by a ftream of oxygen gas thrown upon the charcoal for 2 6'’.. Two of the pieces became co- lourlefs and have fome refemblance to alum; the third re- tains, in fome meafure, its original colour. Their prefent weight is 44ths of a carat. They have all of them loft a confiderable portion of their tranfparency, but have a rough polith, and retain their facets. VI. Another fapphire, in the form of a parallelopipedon, weighing 33ths of a carat, being expofed to the ftrong heat for 2’ 53”, had its angles rounded off, {fo that it became re- duced to the form of a tamarind-ftone, and loft its tranf- parency. It is now a femi-tranfparent whitifh mafs, but ftill retaining fome traces of its original colour. It is in part covered and interfperfed with a kind of brown fcoriz very hike copper bronze. The weight is the fame as at firft. VII. Seven fapphires, weighing together +ths of a carat, heated for 9’ 55’, loft no weight, but became agglutinated together; the fufed coat in which they are enveloped having the appearance of a whitifh femi-tranfparent vitreous cement, through which the remainder of the ftones are feen ftill re- taining fomewhat of their colour. One portion or face of the mafs, containing two of them joined as already men~ tioned, was afterwards fubjefted to the lapidary’s wheel: it took a good polifh, and proved as hard as at firft. The ap- pearance of the different parts of the polifhed face, is the: fame as that of other fimilar parts of the mafs. Oriental Topazes. VIII. A topaz, weighing 3$ths of a carat, was expofed for z' 19’ to a heat excited by oxygen gas, thrown upon the charcoal on which it lay, in two fireams, by means of a double blow-pipe of a new conftruétion, fuggefted and exe- cuted by Mr. Varley, and which will be defenbed, along with the other parts of the apparatus, in its proper place. The ftone entirely loft its colour, and now refembles a piece of borax. The fufion, if there was any, was extremely fuperfi- cial, being only juft fufficient to deftroy the polith, the form and facets ftill remaining, with the angles a little obtunded, Its weight is the fame as at firft. » Experiments refpefting Heat. 29 IX. Three more, weighing 33ths of a carat, heated for 4 26", became agglutinated together, but were found to have loft none of their weight. Being heated a fecond time for 4’ 30’, they melted into a globule, which broke in cool- ing. The principal portion is roundifh, and the fufion has evidently been complete: it has a brownifh appearance on the fufed furface, but is clearer in the fra€ture; the whole — being fomewhat like a piece of dirty camphor. The weight is a little increafed. _ X. A topaz, weighing iths of a carat, after being ex- pofed to the heat for 4’33’%, was found to have loft ,3,ths. It had, like the laft, loft its colour, but fill partly retains its original figure. One fmall furface was afterwards tried on the lapidary’s wheel, and found to be as hard as before. Brazilian Topaz. XI.-A Brazilian topaz, weighing 34ths of a carat, after being in the heat for 3'26", came out 22ths. It was per- feétly fufed, and had become of an opake white, like a fufed falt; fuch, for example, as fal prunelle. Oriental Rubies. XII. One weighing {jths of a carat, heated for 2/9”, feems flightly and fuperficially fufed: it is cracked, but the pieces have nat feparated. The weight and colour are the fame as before. It is well known that rubies, when expofed to a common lamp and blow-pipe, become colourlefs, but “recover their colour fuddenly and inftantly on cooling, when a little below a red heat. This ruby, after its expofure to the intenfe heat excited by the decompofition of the oxygen gas, refumed its colour as it would have done if it had been ex- _ pofed to a lower heat. . XIII. Five rubies, weighing together half a carat, were expofed to the heat for 4’ without lofing any weight. The whole became agglutinated into a fhapelefs mafs, in which the remains of the original ftones now appear interfperfed in a white vitreous cement. The colour of the {maller ftones was changed whitifh, but one larger portion was but little altered in this refpect, E2 XIV. 28 Experiments etre Heat. XIV. Eight more, weighing 1,8, carat, heated for 5’ 8”, loft no w eight: : they were zuelubiately like the former, into a fhapelefs mafs (which afterwards broke in two), with the fame appearance of a whitifh vitreous matter interpofed. One {mall portion of the furface ftill retained a fine polifh. An- other part of it was afterwards polifhed by the lapidary: the {tone was found to be as hard as before. XV. To prove whether a longer expofure would not pro- duce a more perfeét fufion, feven more, which weighed to- gether half a carat, were fubjeéted to the heat for oe all, but without undergoing any other change than that of being fuf- ficiently fufed to be firmly age elutinated together by a white vitreous cement: the colour of the ftones ‘enitaves remains, in a certain degree, unaltered. XVI. Nine rubies, weighing 4£ths of a carat, were in- tended to be expofed for a ftill longer portion of time, but, after 6° 10", were obferved to be in fufion. They were then withdrawn, and the mafs weighed, but no lofs of weight was perceptible. They now compofe an opake, dirty-looking, whitifh mafs, fomewhat like melted camphor, and which has evidently been perfeétly fufed. A few {mall portions ftill retain fomewhat of their original colour; but would probably, alfo, have become white or gray, by a longer con- tinuance of the heat. It is, perhaps, worthy of obfervation, that a happy acci- dental arrangement of the fubftances employed, will fome- times produce inftantaneoufly more powerful effects than a Jonger expofure under other circumftances. This was the cafe in the prefent inftance ; for the weight of the rubies ufed in the laft experiment, was to that of thofe employed in the preceding one, as 3 to 2, and yet, though the heat was ap- plied for little more than 2-3ds of the time, the effeéts were much more ftriking. Some remark may perhaps alfo be applicable with regard to the white vitreous fub{ftance into which the furfaces of the {tones become changed. Is it probable that the alkali of the charcoal contributed to deftroy the colour of the ftones? or, Would a carbonaceous fubitance, containing no alkali, have exhibited with them the fame phenomena in all refpects ? This, On ihe Declivities of Mountains. 2g This, and other queftions which will fuggett themfelves, can only be fatisfaCtorily anfwered by experiment. It feems at leaft poflible, however, that the refults.might be different if fufion could be effected under circumftances which fhould _ preclude the poffibility of extraneous admixture. It is, per- haps, not altogether abfurd to fuppofe that the mafs might in that cafe entirely retain its original colour ; and that at fome future, and perhaps not a very diftant period, {mall ftones and fragments may be fufed into larger maffes poffeffing all the properties of the natural gems with as much certainty as metals are now caft into ingots. : [To be continued. ] V. An Effay on the Deelivities of Mountains. By Ricuanp Kirwan, E/g. LL.D. F.R.S. and Prefident of the Royal Irifh Academy *. A\wone the various caufes to whofe aétivity the planet we inhabit owes its prefent wonderfully diverfified appear- ance, fome undoubtedly exerted their influence from its very origin, and others at fubfequent periods; of thefe laft, one at Jeaft, namely, the Noachian deluge, was univerfal in its operation, while the effects of many more were partial and local, fuch as thofe refulting from earthquakes, volcanos, particular inundations, &c. In a general furvey of the globe it is only to general caufes whofe operation was univerfal. that our attention can be di- rected, the effeéts of partial caufes being the proper objects of the geological hiftory of thofe countries that were parti- cularly affected by them. But to diftinguith caufes of the former clafs from thofe whofe operation was more confined, it is neceffary to difcover fome charaéter by which their effets may unequivocally be difcerned. _ Now, a general uniformity, or agreement in fome particular circumftance, in every part of the globe, feems to be a fure teft of the operation of fome general caufe. The difcovery of uniform appearances is therefore of primary importance * From the Tranjadlicas of the Ryal Ini Academy for 1800. | im 30 On the Declivitics of Mountains. in geological refearches. In the prefent effay I fhall confine myfelf to the inveftigation of one inftance of this fort, namely, the ineguality of declivity which the fides or flanks of moun- tains exhibit, in every part of the globe hitherto examined, according to the points of the compafs to which they face, and are expofed. That one part of almoft every high mountain or hill is Reeper than another, could not have efcaped the notice of any perfon who had traverfed fuch mountains; but that Na- ture, in the formation of fuch declivities, had any regard to different afpeéts or points of the compafs, feems to have been firft remarked by the celebrated Swedith geologift Mr. Tilas, in the 22d Vol. of the Memoires of Stockholm for 1760*. Neither Varenius, Lulolph, nor Buffon in his Natural Hif- tory publifhed in 1748, have noticed this remarkable cir- cumftance. } The obfervation of Tilas, however, relates only to the ex- treme ends, and not to the flanks of mountains: with refpect to the former, he remarked that the /ecepeft declivity always faces that part of the country where the land lies loweft, and the gentlefl that part of the country where the land lies higheft; and that, in the fouthern and eaftern parts of Swe- den, they confequently face the eaft and fouth-eaft, and in the northern the weft. The effential part of this obfervation extends therefore only to the general elevation or depreffion of the country, and not to the bearings of thefe declivities. The difcovery that the different declivities of the flanks of mountains bear an invariable relation to their different afpects, feems to have been firft publifhed by Mr. Bergman in his Phyfical Defcription of the Earth, of which the fecond edition appeared in 1773. He there remarked that, in mountains that extend from north to fouth, the weftern flank is the /feepeff and the eaftern the gentlef? : and that, in moun- tains which run eaft and weft, the fouthern declivity is the fteepeft, and the northern the gentleft. Vol. IT. § 187. This affertion he grounds on the obfervations related in his firft Vol. § 32, namely, That rftly, in Scandinavia, in the Suevoberg mountains that run north and fouth, feparating * See alfo Vol. XXV. Swed. Abhandl. p. 291, where Cronftedt ex~- plains fome obfeure parts of Tilas’s obfervation. ; Sweden . On the Declivities of Mountains. 3I Sweden from Norway, the weftern or Norwegian fides are the fteepeft, and the eaftern or Swedifh the moft moderate ; the verticality or fteepnefs of the former being to that of the latter as 40 or 50 to 4 or 2*. adly, That the Alps are fteeper on their weftern and fouthern fides than on the eaftern and northern. 3dly, That in America the Cordelieres are fteeper on the weftern fide, which faces the Pacific Ocean, than on the eaftern: but he does not notice a few exceptions to this rule in particular cafes, which will hereafter be mentioned. Buffon, in the firit Volume of his Epochs of Nature, pub- hthed in 1778, p. 185, is the next who notices the general prevalence of this phenomenon, as far as relates to the eaftern and weftern fides of the mountains that extend from north to fouth, but he is filent with refpeét to the north and fouth fides of the mountains that run from ea{t to weft; nay, he docs not feem to have a juft comprehenfion of this phe- nomenon, for he confiders it conjointly with the general dip of the regions in which thefe mountains exift. Thus he tells us, Vol. I. p. 185, that in all continents the general de- clivity, taking it from the fummit of mountains, is always more rapid on the weftern than on the eaftern fide ; thus the fummit of the chain of the Cordelieres is much nearer to the weftern fhores than to the eaftern: the chain which divides the whole length of Africa, from the Cape of Good Hope to the Mountains of the Moon, is nearer, he fays, to the weftern than to the eaftern feas: of this, however, he mutt have been ignorant, as that tract of country is fill un- known. The mountains which run from Cape Comorin through the peninfula of India, are, he fays, much nearer to the fea on the eaft than on the weft: he probably meant the con- trary, as the fact is evidently fo; and fo he ftates it in the fecond Volume, p. 295: the fame, he tells us, may be ob- ferved in iflands and peninfulas, and in mountains. This remarkable circumftance of mountains was, notwith- ftanding, fo little noticed, that in 1792, the author of an ex- cellent account of the territory of Carlfbad in Bohemia, tells * The verticality of the fides is inverfely as the length of the defcent. ‘ti. us 32 On the Declivities of Mountains. us he had made an obfervation, which he had never met with in any phyfical defcription of the earth, namely, that the fouthern declivity of all mountains was much fteeper than the northern, which he proves by inftancing the Erzgebirge of Saxony, the Pyrenees, the mountains of Switzerland, Savoy, Carinthia, Tyrole, Moravia, the Carpathian, and Mount Hemus in Turkey. 2 Bergm. Jour. 1792, p. 385, in the note. : Herman in his Geology, publifhed in 1797, p. 90, has at leaft partially mentioned this circumftance, for he fays that the eaftern declivities of all mountains are much gentler and more thickly covered with fecondary ftrata, and to’a a greater height, than the weftern flanks, which he inftances in the Swedifh and Norwegian mountains, the Alps, the Cauca- fian, the Appennine and the Ouralian mountains; but the declivities, bearing a fouthern or northern afpect, he does: not mention. La Metherie, in the fourth Volume of his Theory of the Earth, of which the fecond edition appeared in 1797, 4 work which abounds in excellent obfervations), p. 381 *, produces numerous inftances of the inequality of fh pao ad and weftern declivities, but fearce any of the northem and: fouthern, whofe difference he does not feem to have noticed ; but he makes a remark, which I have not feen elfewhere,’ that the coafts of different countries prefent fimilar declivities.. With regard to eaftern and weftern afpeéts, he thinks that a different law has obtained in Africa from that which has been obferved in other countries; for in that vaft peninfula he imagines the eaftern declivitics of mountains are the: fteepeft, and the weftern the gentleft. Of this, however, he adduces no other proof but that the greateft rivers are found on the weftern fide: this proof feems infufficient, as, if moun- tains be fituated far inland, great rivers may flow indifcrimi- nately from any fide of them, and fometimes few rivers flow even from the fide whofe defcent is moft moderate, for in-. ftance, from the eaftern fide of the mountains of Syria: the Elbe and the Oder, two of the greateft rivers in Germany, take their courfe from the weftern fides, the firfi of the . * Iristo be regretted that he fearce ever quotes his authorities, Bohemian On ihe Declivities of Mountains: 43 Bohemian and the other of the Moravian mountains, which yet are the fteepeit; manly originate from lakes, as the Shannon with us; many take fuch a winding courfe, that, from a-bare knowledge of the place of their difemboguement, it is ima poffible to judge from what fide of a mountain they iffue, if from any; their courfe at moft difcovers the depreffin of the general level of the country. In 1798, the celebrated traveller arid circumtiavigator; John Reinhold Fofter, publithed a gedlogical traét, whichi merits fo much more atterition as all the facts were either obferved by himfelf, or related to him by the immediate ob- fervers. In this he ftates, ds a fact univerfally obferved, that the fouth and fouth-eaft fides of almoft every mountain are fteep, but that the north and north-weft fides are gently co- vered, and conneéted, with fecondary ftrata in which organic femains abound, which he illuftrates by various inftances, fome of which have been already, arid others will prefently be, mentioned. At prefent this fact attracts the preateft attention, being obvioufly conneéted with the original ftructure of the globes and clearly proving that mountains are not mere fortuitous eruptions, unconnected with tranfaftions on the furface of the earth, as has of late been confidently advanced. I fhall now ftate the principal obfervations relative to this object that have been made in different parts of the world. In Europe. 1° The mountains that feparate Sweden from } Norway eX tend from noith to fouth; their weftern fides are fteep, and _ the eaftern gentle. 1 Bergm. Erde Befchreib. p. 157. 2° The Carpathian mountains run from eaft to weft; their fouthern fides, towards Hungary, are eep; their northern, towards Poland, nioderate. Fofter, § 46. 3° Doétor Walker, profeffor of natural hiftéry at Edin- burgh, obferved that the coafts and hills of Scotland ate fteeper and higher on the weftern fide than on the eaftetii, Jamifon’s Mineralogy of Shetland, p. 3..—However, Jamifoni obferved that the fouth fide of the ifle of Arran is the loweft, and the north fide the higheft: p. 51. Vou: VII: | + EF 4° The aig On the Declivities of Mountains. 4° The mountains of Wales are gentle on the eafiern and fteep on the weftern fides. 5° The mountains of Parthery, in the county of Mays, are flteep on the weftern fide. 6° The mountains which feparate Saxony from Bohemia defcend gently on the Saxon or northern fide, but are fteep on the Bohemian or fouthern fide. Charpent. p. 75.—The fouthern declivity is to the northern as fix to twoe 2d Bergm. Journ. 1792, p. 384 and 385. 4° Fhe mountains which’ feparate’ Silefia from Bohemia run nearly from eaft to weft, yet are fteeper on the northera or Silefiaty fide than ow the oppofite Bohemian. Affemanni Silefia, p. 335. Such branches as run from north-eaft to fouth-weft have their weftern covered with primordial ftrata, and confequently lefs fteep. 4 New Roz. p. 157. 8° The Meiffencr im Heffia is fteeper on the north and eaft fides, which face the Warra, than on the fouth and weftern. 1 Bergm. Journ. 1789, p. 272. 9° The mountains of the Harts and Habichtswald are fieep on the fouth and gentle om the northerm fides, Fofter, $46. to°® The Pyrenees, which run from eaft to'weft, are fteeper on the fouthern or Spanifh fide. Carbonieres XIII. 11° The mountains of Crim Tartary are gentle on the northern and fteep on the fouthern fides. Fofter, zbzd. ? In Afiz. 12° The Otirals, which’ flretch from nortf to fouth,: are far {teeper on the weftern than on the fouthern fides. Her man. Geologie, p. go; and 2d Ural Befchreib. p. 389. 13° The mountain of Armenie, to'the weft of the Ourals, jis fteep om its ea{t and north fides, but gentle on the fouthern and weftern. 4£ Pallas Voy. p. 277. 14° The Altaifchar mountains are fteep on their fouthern and weftern fides, but gentle on the northern and eaftern. Fofter, bid. aud Herman 2d Ural Befchreib. p. 390 in the’ Rete. 5° So alfo are’ the mountains of Caucafus. 3d Schrift. Rerl, Gefelfch. 474. , ¥6° The On the Declivities of Mountains. 35 + 46° The mountains of Kamfkatka are fteep on the eaftern fides. Pallas, 1 Act. Petropol. 1777, p- 43- 17° The Ghauts in the Indian peninfula are fteep on the weftern fides. 18° The mountains of Syria, which run from north te fouth, fkirting the Mediterranean, are faid to be fteeper on the weftern fide facing the Mediterranean. 4 La Metherie, p- 380. In America. The Cordelieres run from north to fouth; their weftern flanks towards the Pacific are fteep, their eaftern defcend’ gradually, In Guiana there is a chain of mountains that run from eaft to weft; their fouthern flanks are fteep, their northern gentle. Voyages de Condarnine, p. 140. To affign the caufes of this almoft univerfal allotment of unequal declivities to oppofite points, and why the greateft are direéted to the weft and fouth, and the gentleft, on-the contrary, to the eaft and north, it is neceflary to confider, 1% That all mountains were formed while covered with water. : 2° That the earth was univerfally covered with water at two different zras, that of the Creation, and that of the Noachian deluge. 3° That in the firt era we mut diftinguith two different periods, that which preceded the appearance of dry land, and that which fucceeded the creation of fifth, but before the fea had been reduced nearly to its prefent level: during the former, the primeval mountains were formed, and during the laft, moft of the fecondary mountains and ftrata were formed. 4° That all mountains extend either from eaft to welt, of from north to fouth, or in fome intermediate direction be- tween thefe cardinal points, which need not be particularly mentioned here, as the fame fpecies of reafoning mutt be applied to them, as to thofe to whofe afpeét they approach -mott. Thefe preliminary cireumftances being noticed, we are next to obferve that, during the firft, xra, this vafi mafs of - ae) N water 36 On the Declivities of Mountains. water moved in two general diredtions, at right angles with each other; the one from eaft to weft, which needs not to be proved, being the courfe of tides which ftill continue, but were in that ocean neceffarily ftronger and higher than at prefent; the other from north to fouth; the water tending to thofe vaft abyffes then formed in the vicinity of the South Pole, as fhown in my former eflays, Before either motion could be propagated, a confiderable time muft have elapfed. Now the primval mountains formed at the commence- ment of the fitft era, and before this double direction of the waters took place, muft have oppofed a confiderable obftacle to the motion of that fluid in the fenfe that croffed that of the direction of thefe mountains. Thus, the mountains that ftretch from north to fouth muft have oppofed the motion of the waters from eaft to wett; this oppofition, diminifhing the motion of that fluid, Sitpater 3 it to fuffer the earthy particles, with which in thofe early periods it muft have been impreg- nated, to cryftallife or be depofited on thefe eaftern flanks, and particularly on thofe of the higheft mountains, for over the lower it could eafily pafs: thefe depofitions, being incef- fantly repeated at heights gradually diminifhing as the level of the waters gradually lowered, muft have rendered the eaftern declivities, or defcent, gentle, gradual, and moderate ; while the weftern fides, receiving no fuch acceffions from depofitions, muft have remained fteep and craggy. Again, the primeval mountains that run from eaft to weft, by oppofing a fimilar refiftance to the courfe of the waters from north to fouth, muft have occafioned fimilar depofitions on the northern fides of thefe mountains, againft which thefe waters impinged, and thus fmoothed them. Where mountains interfe&t each other in an oblique di- rection, the north-eaft fide of one range being contiguous to the fouth-weft flanks of another range, there the afflux of adventitious particles on the north-eaft fide of the one muft have frequently extended to the fouth-weit fide of the other, particularly if that affluy were firong and copious: thus the ~ Eragebirge of Saxony, which run from weft to eaft, have their north-eatt fides contiguous to the fouth-weft fide of the Ricfengebirge that fepgrate ‘Silefg fi fram Bohemia; and hence 7 thefe ~“ On the Declivities of Mountains. Ey 4 thefe latter are covered with the fame beds of eneifs, &c. as the northern fides of the Saxon, and thereby are rendered fmooth and gentle comparatively to the oppofite fide, which, being fheltered, remains fteep and abrupt; which explains the feventh obfervation. The caufes here affigned explain why the covering of ad ventitious ftrata on the higheft mountains is generally thin- neft at the greateft height, and thickeft towards the foot, of the mountain; for the bulk of the water that contained the adventitious particles being proportioned to its depth, and the mafs of earthy particles with which it was charged being proportioned to the bulk of water that contained them, it is plain, that as the height of water gradually decreafed, the depofitions from it on the higher parts of the mountains muft have been lefs copious than on the lower, where they muft have been oftener repeated. Pence, 2°, granitic mountains, generally the moft antient, frequently have their northern or eaftern fides covered with ftrata of gneifs or micaceous {chiftus, and this often with argillite, or primeval fandftone or limetione, thefe being either of fomewhat later formation, or longer fufpendible in water. Hence, 3°, different fpecies of ftone are often found at dif- ferent heights of the fame flank of a mountain, according as the water which conveyed thefe fpecies happened to-be dif. ferently impregnated at different heights: during the firft era its depofitions formed the primitive ftony maffes; but after the creation of fifh, limeftone, fandftone, farcilites, and fe- condary argillites, in which pifcine remains are found, were depofited. But, during the fecond era, vzz. that of the Noa- chian deluge, by reafon of the violence and irregularity of its agereffion, the depofitions were more mifcellaneous, and are found at the greateft heights; yet, in general, they may well be diftinguifhed by the remains of Jand animals or of vege- tables, or of both, which they prefent in their ftrata (or at leaft by the impreffions of vegetables which they bear), as thefe muft have been conveyed after the earth had been in- habited, But mountains regularly flratified bearing fuch re- , mains, £8 Ow the Declivitics of Mountains: raains, for inftance the carboniferous, cannot be deemed to have been formed in a period fo tumultuous. - During this deluge the waters alfo held a diflerent courfe, proceeding at firft from fouth to north, and afterwards in both oppofite di- rections in our weftern hemifphere, as fhown in treating of that cataftrophe in my fecond effay. Hence, and from various contingent local caufes, as par- tial inundations, earthquakes, volcanoes, the erofion of rivers, the elapfion of ftrata, difintegration, the difruption of the lofty mounds by which many lakes were antiently hemmed in, feveral changes were produced in particular countries that may at firft fight appear, though in reality they are not, ex- ceptions to the operation of the general caufes already ftated. ' Thus the mountains of Kamfkatka had their eaflern flanks torn and rendered abrupt by the irruption of the general de- luge, probably accompanied by earthquakes. And thus the Meiflener had its eaft and north flanks undermined by the river Warra, as Werner has fhown: thus the eighth and fixteenth obfervations are accounted for, as is the thirteenth, by the vaft inundations fo frequent in this country,. 1 Pallas, p. 172, which undermined or corroded its ealt fide, while the weftern were {moothed by the calcareous depofitions from the numerous rivers in its vicinity. Hence, 4°, we fee why on different fides of lofty mountains different fpecies of flones are found, as Pallas and Sauffure have obferved, 2 Sauff. § g$1; a circumftance which Sauf- fure imagined almoft inexplicable, but which Dolomieu has fince happily explained, by fhowing that the current which «conveyed the calcareous fubftances to the northern, eaftern, and north-eaftern fides of the Alps, for inftance, was ftopped -by the height of thefe mountains, and thus prevented from conveying them to the fouthern fides; and thus the north- eaftern fides were rendered more gentle than the oppofite. 3 New Roz. p. 425, conformably to the theory here given. Hence, 5:, where feveral lofty ridges run parallel to each wother it muft frequently happen that the external fhould in- tercept the depofitions that do not furmount them, and thus -leave the internal ridges fteep on both fides, Hence, x ‘On the Declivities of Mountains. 39 Henée, 6°, low granitic or other primitive hills are fre- ‘quently uncovered by adventitious ftrata on all fides, as at Phanct in the county of Donegal, or are covered on all fides; the impregnated waters either eafily pafling over them, or ftaonating upon them, according to the greater or leffer ra- pidity of its courfe, and the obftacles it met with. The two-fold motion of the antient ocean is noticed both ‘by Buffon and Bergman, but neither of them has deduced ‘from it the true explanation of the phenomena of which we here treaty Buffon attributed the formation of fecondary mountains to depofition or fediments from the fea after the exiftence of fifh, 1 Epoques, p. 143, in 8vo., which, he fays, invetted the bafes of mouritains, without hoticing any diftinc< tion of fides, p. 144 and +70. He thinks thefe fediments were equally conveyed from both poles towards the equator; for it is in the equatorial regions that, he thinks, thofe mighty caverns opened, towards which the primitive ocean was im- petuoufly borne, and in which it was ingulphed; p. 181, 182, and 183. If fo, fimilar declivities fhould be formed on the fouthern as on the northern fides of mountains ; which is: contrary to the obferved facts. His explanation of the eaflern and weftern declivities is defective and erroneous; for he at- tributes the.abruptnefs -of the weftern fides to the erofion of the coafts on that fide (an erofion that exifts only in fancy}, and the fmoothnefs of the eaftern, to the gradual defertion and retreat of the fea on that fide, p. 184 and 185; a retreat equally fictitious, as De Luc has well fhown. Whereas, fince the general motion of the fea is from eaft to weft, if the erofion were of either fide, it fhould rather be on the eafiern than on the weftern; befides, if the gentle declivities ef the eaftern fides of mountains arofe from the gradual re- treat of the fea, the petvifactions of the fecondary mountains thus formed fhould confift of fuch fhell-fith as inhabit fhal- low feas or fhores, whereas they confift chiefly of thofe called pelagic, which inbzbit the greateft depths *. With refpect to the eaftern and weftern declivities, Mr. Bergman’s account of the origin of their inequality agrees éxactly with mine, 2 Bergm. Erdeklotet, § 183 and 187; a * z Bergm- Erdekugel, p.'315. ae . but om) On the Identity of the Pyromitcoiis, but he fails in accounting for the inequality of the northerd and fouthern, for he ingots s the courfe of the waters tod tend equally from both poles towards the equator; which 4would render the depofitions equal on both fides; which is contrary to obfervation. VI. On the Identity of the Pyromucous, Pyrotartareous, and Pyroligneous Acids; and the Neceffity of not confidering them any longer as diftin@ Acids... By C. Fourcrot and VAUQUELIN *, . I. On the Multiplicity of the Vegetable Acids, Wa EN Bergman and Scheele had difcovered feveral vegetable and afiienal acids before unknown, and had de- ftroyed the pretended identity admitted in regard to thofe bodies, all the chemifts employed themfelves with great zeal in fubjectine various vegetable acid fubftances to a new exa- Mination. ‘The number of compounds, which till then had been reduced to two kinds, increafed fo much, that it was fuppofed it would far exceed that of the acids which had been difcovered among the foffils, and that it would be impoffible to fet bounds to the multiplicity of thefe natural productions of organifed bodies. The four liquors, extracted by diftillation from mucous bodies, wood, and tartar, though owing to an artificial de- eompofition, have been comprehended in the clafs of the vegetable acids, well charaéterifed as poffeffing a peculiar nature: fome analogies founded on their origin, their brown colour, and their burnt odour, have caufed them to be re- - ferred to a fpecial genus, under the name of the empyreu- matic acids. If we collect the faéts which feem to prove that they are different in nature not only from the other acids, but from each other, they will eafily fhow that thefe acids have not been fufficiently examined to be well known; that chemifts had only very imperfe& ideas refpecting their nature; and that it was for want of accurate analyfis that * From the Aanales de Chimie, Nos 104. they’ « Pyrotartarecus, and Pyroligneous Acids. 4t they were thought to be different from each other, and dif- ferent in their whole nature from any other vegetable acid, Il. Charaéers given to the Pyromucous Acid. Lemery, Boerhaave, Neumann, Cartheufer, Macquer, and Bucquet, were the firft who infificd on the fpecific characters of that acid which has been called the pyromucous in the Methodical Nomenclature, and which had long been diftin- guifhed by the name of Spirit of honey, of fugar, of manna, of gum, &c. M. Schrikel, in giving a detailed hifory of the analyfis of fugar and of this acid in 1776, greatly enlarged and confitmed the ideas before conceived refpecting the pe- culiar nature of the pyromucous acid, and all chemifts have fince adopted that opinion. It was charaéterifed by its dark red colour when impure, and its golden yellow colour after being rectified; by its odour of caramel, its very pungent tafte, its volatility, nearly fimilar to that of water; by its aétion on the fkin, which it tinges red, and on the glafs of retorts, which it feems to attack. It was believed to be en- tirely contained in mucous matters, and to be only developed by fire; it was faid to be fufceptible of decompofition by heat, and of being converted into gafeous bodies. But, be- fides that its fuppofed aGtion on glafs depended only on the adherence and penctration of the charcoal of the fugar; be- ’ fides the proof, already well eftablithed, of its non-exiftence in faccharine and gummy matters, and of its entire produc- tion by fire, it muft be allowed that, in examining what has been done in regard to faline compounds and the attractions of the pyromucous acid, no refult had been obtained but yague and undetermined notions, which feemed to excite doubt and uncertainty in regard to the particular nature of this acid. The reader will be enabled to judge of the truth of this affertion by perufing, in particular, the details given under the article Syrupy Acid of the Dictionnaire de Chimie Encyclopédique, where our learned colleague Guyton. has col- leG&ted every thing then known refpecting this empyreumati¢ acid: when drawing up, therefore, the article in my Syftem of Chemical Knowledge, written and printed feveral months before the difcovery now fubmitted to the Inftitute, I was Vor. VIL, G not 42 On the Identity of ihe Pyromucous, KO MRS Ag not able to obtain the real diftinguifhing charaGters of the pyromucous acid. III. Chara@ers aferibed to the Pyrotartareous Acid. We are. mdebted to. Lemery and Neumann for our firft knowledge of this acid, furnithed by diflilled tartar, and dif ferent from the tartareons acid. They foand that tartar, by diltillation, gave the fourth of its weight of acid phlegm. According to the prefeription of Neumann, it was to be rec- tified at a gentle heat; but C. Guyton was not able to per- form that operation with fuccefs, and the retort was always broken by the explofion which took place. The empyreu- matic odour and tafte of this acid are the two moft ftriking characters which made it be admitted by chemifts as a pe- cuhar acid. It is difficult to conceive why Venel fhould take this acid produét of dittilled tartar to be nitric acid, which he thought might be extraéted alone, and in a fate of pu- rity: it is no lefs aftonifhing to hear. C. Monnet maintain, in confequence of experiments made at fome length, that diftilled acid of tartar is muriatic acid, though he really found in it, according to his own acknowledgement, only approxi mative characters. The academicians of Dijon and C. Ber- thollet; after repeating all the experiments of Monnet, were convinced that there is no real analogy between the acid produét of diftilled tartar and the muriatic acid. Scheele, in proving that there is always a little real muriatic acid in the alkali of tartar, infifted on the differences between this acid and that of tartar, M. Fontana proved that the acid diftilled from tartar can be entirely refolyed into carbonic acid gas and carbonated hydrogen gas; fo that; by bringing it nearer to all the other vegetable acids, he removed further every idea of confounding it with the mineral acids. In the laft place, Guyton, in the firft part of the firft volume of the Dzétion- naire de Chimie Encyclopédigque, publithed in 1786, after de- tailing all the different opinions as well as the principal facts known refpeéting this acid, concluded that it would be ne- _ teffary to confider it as a peculiar acid; a produ& of tartar altered by heat, diftinguifhed from the latter by its being meapable of cryftallifation, and by the foluble falt which it 8 formsr- Pyrotartareous, and Pyroligneous Acids. 48 forms with lime; and he called it the tartareous empyreu- matic acid. Thefe ideas, adopted in 1787 by the authors of the Methodical Nomenclature, induced them to diftineuith this acid by the name of the pyrotartareous acid. Since that period, chemifts have continued to confider this acid as a dif- tinct {pecies, and no one has fubjected it to a new examina- ton. IV. Charagiers given to the Pyroligneous Acid. Boerhaave firft made known, under the name of acid fpirit of wood, the product diftilled from woody bodies; and be even compared it to a kind of vinegar. M. Goetling has given a particular hiftory of it in Crell’s Chemical Journal for the year 177g. Guyton made it known afterwards, under the name of the ligneoys acid, in the firft part of the Dic- tronnaire Encyclopédique, publithed in 1786. He collected all the information then acquired refpecting this acid, ac- cording to the experiments made by the Academy of Dijon. Every kind of. wood examined has hitherto furnithed by dif- tillation the fame acid; the difference in regard to colour, favour, acrid odour, and particularly that of faline com- pounds, formed by the liquid diftilled from wood, have made it to be diftinguifhed from every other acid: in the Methodicat Nomenclature it has been called the pyroligneous acid, and in my Syficm of Chemiftry I claffed it with the pyromucous and pyrotartareous acids, as forming with them a kind of acids compofed of fpecies analogous to each other in the ratio of their identic crigin, and of fome comparative pro- perties manifetily depending on their empyreumatic {ftate. The characters adopted to diftinguith the pyro-ligneous acid were, its fmoky fmell, its reddith “cblour, its property of giving a lafiing ftain to wood, the falts which it formed with alkaline bafes, and the elective attraétions which it obeyed, In giving a fyftematic explanation of the properties of this acid, as well as in regard to thofe of the pyromucous and pyrotartareous acid, the want of more accurate knowledge was always felt; characters fufficiently ftriking and well de- fined, proper to diftinguith thefe three acids from each other, could not be found; and even after they had been clafled Aogether into @ difuact genus, on account of their empyren- , (GG 2 matic 44 On the Identity of the Pyromucous, matic nature, which gave them a ftriking refemblance, when. chemifts withed to explain what were the peculiarities of each fpecies, they were obliged to acknowledge that the exa- mination of thefe Oe dudions of fire had not si carried to a fufficient length, and that their properties had not been fo thoroughly ftudied as to enable them to affign characters fufficiently firiking, and to give a correct hiftory of them, V. Firfi View of the Acetous Nature of the eae ae ng Acids, Such was the uncertain ftate of the fcience in regard to the three acids extracted from vegetable matters by fire, when a circumflance, prefented, as it were, accidentally, gave us an opportunity of difcovering a new fact refpecting their nature. In the courfe of thofe refearches in which C. Vauquelin and myfelfshave been fo long engaged refpecting the chemical analyfis of vegetable fubfiances, and of the experiments which we made on the folid or ligneous parts of plants, we were employed fome months in ‘the examination of cork. This epidermal covering of a {pecies of oak had appeared to me, for feveral years, to be of a nature fo very diftiné from other vegetable tiffues as to deferve a particular refearch: feveral experiments on the epidermis of other trees had in- clined me to think that in their characters they approached near to cork, and [ thought it my duty to prefent it as one of the immediate materials of plants under the name of Juber. Beg defirous of carrying my firft effays full further, and of giving more extent to thele firft ideas, we began to employ ourfelves this fummer on a more exaét analyfis of cork, Having fubjected a pretty large quantity of it, o’61lb, (three he¢togrammes), to diltillation with a naked fire, we. obtained fron it a fourth of its weight of a very light and vo- Jatile ot!, and almoft the fame quantity of a reddifh empyreu- matic liquid, which exhibited all the apparent characters of the pyroiigneous acid. But this acid liquor, when examined with more gare, rectified and combined with ‘alkalies, and difengaged from its bafes by weak fulpburic acid, foon exhi- bited properties of real acetous acid, and, after having fepa- rated it by flow diftitlation from the portion of coloured oil which Pyrotartareous, and Pyroligneous Acids. 45 which it held in folution, it evidently appeared to be that acid. When this faét was once afcertained, it was not difficult for us to prefume that the pyroligneous acid, from whatever wood extracted, could only be acetous acid: we had even reafon to fufpect that the two other empyreumatic acids were of the fame nature; but as a conjeéture, however well founded, has no real value in phyfics, we called in the aid of experiment to enable us to difcover the truth, or to reject our opinion as an error, VI. New Examination of the Pyromucous, Pyrotartareous, and Pyroligneous Acids. 1. Having diftilled, with great caution, fixteen parts of pure fugar, which furnifhed us with ten parts and a half of water charged with reddifh pyromucous acid, a little more ‘than four parts and a half of light charcoal, and half a part of gas, we combined this acid liquor with lime; tle liquor was then evaporated to drynefs, and afterwards treated in a retort with weak fulpburic acid. We thus obtained a pretty thick, clear, or very little coloured liquid, having a very. fen- fible acetous fmell, and which, when combined with potath, gave a very evident acetite of potafh. This falt, indeed, had a dirty gray colour; but, by filtering a warm folution of it through pounded charcoal, it loft the oil which coloured it, and became quite clear. The acid product, obtained from the firft calcareous fait by the fulphuric acid, was already much lefs coloured than the pyromucous acid; it now retained only very faintly the fmell of caramel (pan fugar), which characterifes the acetous acid. When difengaged a fecond time from alkaline falt by the fulphuric acid, it was ftill purer, had nothing of its firft origin, and now exhaled only a pure acetous odour. We had reafon, therefore, to conclude, from thefe experiments, that the pyromucous acid was nothing elfe than acetous acid united to an empyreumiatic oil arifing from the decompofi- tion of the fugar by fire. The fame refult took place with acid liquors extracted from 46 On the Identity of the Pyromucous, from gums, honey, manna, ftarch, paper, and feveral other vegetable fubftances which are known to yield pyromucous acid by diftillation. 2. White and purified tartar gave by the retort nearly a half lefs of acid liquor, than fugar furnifhed of pyromucous acid. This tartareous acid produét, obtatned by a weil re- gulated heat, was almoft tranfparent, and had not the red- difh-brown colour of the empyreumatic acids extracted by means of a ftrong heat. It however had an acrid empy- yeumatic odour, a heavy and highly coloured oil floated over it, and, notwithftanding its pungent nature, it would have been difficult to afcertain it to be acetous acid by this fingle experiment: but it did not long deceive us. Having fatu- rated it with potafh immediately, on account of its little colour and impurity, we diftilled it, after being evaporated to drynefs, with diluted fulphuric acid, and it furnifhed acetous acid, eafy to be diftinguifhed as fuch, without any mixture of empyreuma. We found that by diftilling pyrotartareous acid, even not rectified and in a red ftate, front off pounded charcoal, previ- oufly well lixiviated and earefully dried, it loft by this fimple operation its empyreumatic nature: we are even perfuaded that mere filtration of this acid warm, through charcoal, fe- veral times repeated, would be fufficient to feparate from it the oil, and to bring it to the ftate of acetous acid almoft pure, No doubt, therefore, can remain, that the pyrotartareous acid is acetous acid rendered impure by a portion of empy- reumatic oil produced by the decompofition of the tartareous acid by caloric. 3. The pyro-ligneous acid obtained from fhavings of beech wood, diftilled with care, formed with lime a brown falt not eryftallifable. This falt, when treated with very weak ful- phuric acid, gave acetous acid, known by its fnell, the de- liquefcent acetite it formed with potath, or = cryftallifable acetite obtained from it with foda. Another portion of the fame primitive pyroligneous acid, when immediately united to potafh, and filtered in its folu- tion through powdered charcoal, gave an acetite of potafh almoft.colourlefs, from which weak fulphuric acid difengaged, by Pyrotartarcous, and Pyroligneous Actds. 47 by diftillation, very pure acetous acid, almoft without empy- reumatic odour or fumes. ‘ It muft here be obferved that the pyroligneous acid, that of the three acids obtained by fire which has the moft ftriking empyreumatic odour and charaéter, 1s alfo one of the three moft difficult to be purified, and to be carried to the ftate of very pure vinegar. It does not, therefore, affume the nature’ of the laft, as the tartareous acid does, by filtration alone, nor even by two fucceflive diftillations from off powdered charcoal. By employing even the aid of ebullition and ftrong agitation with charcoal, it cannot be deprived of its oil, while both of thefe proceffes fucceed with certainty and eafe in purifying the pyromucous acid, which, indeed, gives up with moft eafe its oil; and even in purifying the pyrotar- tareous acid, though it be a little more difficult to feparate its oil than that of the pyromucous acid. But though it is more refraétory in oppofing purification, and that kind of analyfis of which I here fpeak, it is no lefs proved, thai the pyroligneous acid, like the two preceding, is only acetous acid impregnated with empyreumatic oil, pro- duced from wood altered by heat. VII. Artificial Converfion of the pure Acetous Acid into the Pyroinucous, Pyrotartareous, and Pyroligneous Acids. - The preceding experiments might be fufficient to make us acquainted with the identic and real acetous nature of the three empyreumatie acids, which have been hitherto confi- dered as forming three diftin& acids, and belonging to a genus well characterifed. But to thefe experiments a fupple- ment was {till wanting ; it was neceflary to inquire whether it was not poflible to imitate thefe acids with that of vinegar, by adding what {cemed to be added to it in each of thefe acids produced by fire. It was before fully proved that each of thefe products of diftillation differed from the other two by an empyreumatic oil united to it by the effect of its diftillation alone. It was very eafy, therefore, to try to diftil vinegar from off oils dif- tilled from 4 mucilage, tartar, and wood. This trial was attended with all the fuccels that could be expected, Acid ; . ‘ of ‘ 45 On the Identity of the Pyromucous, of vinegar, heated in a retort with each of thefe three oils, furnifhed a coloured and odorous product exa&tly of the fame nature as primitive pyromucous, pyrotartareous, and pyrolicneous acids : : the odour and fmell of thefe acids were very perce ptible ; only thefe fa€titious empyreumatic acids were a little ftronger and fourer than thofe arifing from dif- tillation, but nothing more was neceflary to carry them to the fame ftate of heaviniels than toad fo theni’a Kittle water. By repeated trial we obtained a manner of forming with the acid of vinegar the three empyreumatic acids much fpeedier, and in a more fimple manner, than by diftillation. We found that it was fuficient to throw fome drops of the empyreumatic oil of mucilages, of tartar, or of wood, into the acetous acid, to fuffer them to remain fome time together, or to fhake them ftrongly, to imitate thefe acids made by fire. The oil almoft immediately unites with the-acid, diffolves in it, gives it a red or brown colour, and communicates to it, at the fame time, the acrid odour and ‘bitter pungent tafte known in the pyromucous, pyrotartareous, and pyroligneous ~ acids. The acetous acid is then a real folvent of empyreumatic oils, and in that cafe it affumes the characters of the acid liquors or odorous fpirits, as they were formerly called, which iflue from vegetable matters treated by fire. To Feat thefe oils diffolved 4 in the acetous acid, and to brine back the latter to its purity and to its primitive fimplicity, the fame means muft be employed as for freeing the acetous acid from the empyreumatic acids united to it when obtained by dif- tillation, viz. filtration, agitation, ebullition with charcoal, union with lime and alkalies, and the difengagement of thefe combinations by weak fulphuric acid. It is to this folubility of oils in the acetous acid, that the odour which this acid fo eafily acquires and retains feems to be owing: it is to it that we mutt afcribe the diftinGtion of a great Badsber of empyreumatic acids, which feveral che- ffitte have been induced to make, and which they could not avoid doing, while continuing to confider, in the acid pro- ducts of diftilled vegetable matters, the odour, colour, and favour, as characters proper, if not for pofitively afcertaining, at Pyrotartareous and Pyrolignesus Acids. 49 at leaft for conjeGturing them to be acids different from each other; and efpecially by comparing thefe charaéters’in acid products furnifhed by kinds of wood very different in their properties, and confequently in their products, VIII. Reflections on the Frequency and the Nature of the different Procefjes which furnifh Acetous Acid. After having proved that mucilages, faccharine bodies, fcule, as well as wood and tartareous compounds, give by diftillation real acetous acid, concealed in the produéts of each of thefe bodies by a portion of oil, having a peculiar odour, fmell, and colour, and that, confequently, we oucht to dedu& from the number of the vegetable agids thefe three empyreumatic acids, we thought it might be ufeful to feience to give fome obfervations here on the ‘produétion of the acetous acid, The knowledge which the chemical ait pof= feffes at prefent refpecting this production, though much more extenfive than formerly, has never yet been colleéted into any work; it may, however, be of great importance in vegetable analyfis: fuch is the motive which induced, us to prefent a fhort view of it, without, however, entering into all the details which the fubje&t might require in a fyftematic work. The forniation of the acetous acid, which has always been believed to be neceflarily produced by a fermentation pecu- liar to vinous liquors, is fo frequent in the proceffes of art and the operations of nature, that it is indifpenfably necef- fary to make it a general phenomenon, and to ftudy this phenomenon under the name of acetification, as proper to throw light on the chemical properties of organifed bodies. » We may confider it either in regard to fubftances fufceptible of acetification, or in regard to ¢ircumftances which favour transformation into acetous acid. Under the firft point of view, befides vinous liquors, which were firft found, and long thought to be, the only ones ca- pable of acetification, we have found a multitude of bodies fufceptible of experiencing this change. There is fearcely any vegetable extract in which acetites are not found: fap, if it has been kept only a few hours, contains fome of it; Vou, VIII, se even 50 On the Identity of the Pyromucous, © even different kinds of mould itfelf are charged with it, as may be eafily proved by diftilling them with a little diluted ful- phoric acid: tan, when heated, emits an odour of vinegar, and_furnifhes fome of it by the fame treatment: water in which pulfe, cabbages, carrots, turnips, potatoes, cucum- bers, the pods of French beans, &c. have been fteeped arid grown four, is exceedingly acetous: the water from the ftarch - manufaétories is the fame: the juices of acid fruits, thofe of apples, pears, goofeberries, {trawberries, rafpberries, cherrics, oranges, and lemons, when expofed fome hours to the warm air, aflume, along with a {trong and pungent odour, a tafte differently and more ftrongly acid than that which they had naturally; befides perceiving in them acetous acid, you will obtain it pure and infulated by fubjeéting thefe juices to dif- tillation. It is well known from the experiments of Scheele, that milk in becoming four gives acetous acid; we have found that bouilli and animal jelly form this acid alfo: ina word, we have faid in other memoirs that the urine of the mammiferz, and that of man in particular, had the pro- perty of becoming acetous, ‘and gave a great quantity of we flrong acid by diftillation. ob fae the number of the fubflances fufceptible of acetifi- cation is very confiderable: extractive matter, mucilage, fae- charine bodies, feecula, and ftarch; even ligneous bodies, tan, the greater part of the primitive vegetable acids, the ge- Jatin of animals, the cafeous matter, and even urée, that body peculiar to urine, and which charaéterifes it, by its remark- able properties, al] thefe produéts of vegetable and animial organifation and Jife are equally fufceptible of acetification. It is true, that the circumfiances under which we have prefented their conyerfion into acetous acid, feem all to be- long to a fermentation, arfd that it might be thought that. they follow a formation more or lefs ftriking or fugitive of vinous matter, but it remains for us to fhow that thefe mat- ters may be acetified by phenomena or caufes different from fermentation; and this fact is already. proved by the acid . productions of the diftillation, which form the principal fub- ject of this memoir. I[t is here feen that the action of fire really acetifies gums, mucilages, tartrites, wood, A know- Ry tre . ledge Pyrotartareous, and Pyreligneous Acids. 5Y edge of the chemical phenomena exhibited by vegetable fubftances in regard to their acidification in general, enables us to obferve and diftinguith four circumftances which pro- mote their acetification or converfion into acetous acid. Thé firft is, the decompofing aGtion of the fire in diftilla- tion. Without here entering into more extenfive details on this fubjeét, which, when we confider the objeét of this me- moir, are lefs neceffary, we fhall content ourfelves with ob- ferving, that this action of caloric, by difuniting the con- ftituent principles of vegetable matters, combines a “part of them in fuch a manner as to give birth -to acetous acid; and that this converfion is accompanied with the formation of water, the formation and difengagement of gafeous carbonic acid, and the precipitation of carbon in the ftate of charcoal. ~The fecond mode of acetification of vegetable compounds is that arifing from the action of powerful acids, and parti- cularly of the fulphuric, the nitric, and the oxygenated mu- riatic on thefe compounds. This kind of produétion takes place in gums, fugar, extra&ts, and gelatin, when treated by acids; the greater part of the other vegetable acids, and even alcohol itfelf, often experience fuch a change by the decom- pofing influence of the acids above mentioned. While this kind of acetification takes place, there are formed alfo water and carbonic acid; fometimes carbon likewife is depofited. We mutt here add, that this acetification is the laft term of vegetable acidification in general, fince in treating acetous acid by the fame decompofing action of the mineral acids, you deftroy its acetous nature, and make it pafs to the ftate of water and carbonic acid, as is the cafe in every vegetable decompofition carried to its maximum. The.third mode of acetification is the oldeft known of the ~ whole, and the only one formerly admitted: it is the acetous fermentation that converts all the different kinds of wine into vinegar: in this there is neither a precipitation of carbon, nor difengagement of carbonic acid. It is well known that it takes place im confequence of an abforption of the oxygen of fhe atmofphere, and that ir fuppofes the preexiftence o. yinous liquors. In the laft place, we confider as the fourth and laft mode ‘ ee 3 (| of Bs On the Empyrcumatic Acids. of acetification, a kind of peculiar fermentation, which does not require the prefence of wine, which takes place in mat- ters foreign to the nature of vinous liquors, and which has fome relation to putrid decompofition. It is that obferved in animal liquors abandoned te themfelves, and perigee in urine. Each of thefe modes of acetification, though equally giving birth to acctous acid, and fuppofing the fame compofition from which that acid arifes, fince it is the fame in every cafe when it has been purified, admits, however, a difference in the produéts which accompany it. Each of the acetous acids arifing from it, prefents indeed a fpecific character proper for making it known and for indicating the fource which has given birth to it. Thus, 1{t, The acetous acid obtained by fire is empyreu- matic; it holds in folution an acrid oil, which gives ita pe- ~ . euliar odour, colour, and favour. ad, Faétitious acetous acid, produced by the aétion of ether acids, is chara¢terifed by the prefence of the malic, or of the oxalic acid, formed at the fame time as itfelf, and by its weaknefs, depending on the proportion of the water, which is alfo formed with the three preceding acids, 3d, The acetous acid .arifing from wine contains tartar, alcohol, and a colouring matter, which give it a peculiar charaéter. It is, as has been faid, a fpirituous acid. 4th, In the lat place, the acetous acid produced by putrid fermentation is always united, in whole or partially, to am- monia, which, like it, aries from this feptic commotion. But whatever may be the matters or new compounds united to the acetous acid formed under any of the four cir- cumftances abovementioned, this acid, capable of being fe- parated with greater or leis eafe from each of thefe fub- ftances, is always the fame, and always fimilar to that ex- trated from four wine by the help of diftillation. Tt muft therefore be now admitted that the acetous acid is not the fole and neceffary produ& of the fermentation of wine, and that its production, exceedingly frequent, is one of the moft conftant phenomena of vegetable and animal analy fis, Vi. ‘Autunt Cowan VII. Account of a fatal Accident which happened to a Tra- veller on the\ Glacier of Buet; with fome Cautions to thofe who through Curiofity may vifit the Mountains of Swiffer- land, and particularly the Glaciers, By M, A. Picret, Profeffor of Philofophy *. , A SENTIMENT of curiofity, exceedingly natural, induces travellers from all parts of Europe to vifit Mont Blanc, the higheft point of the old world, and to examine the furround- ing glaciers. Since the memorable afcenfion of the learned : hiftorian of the Alps, thefe places have acquired a.new de- gree of intereft: the, geologue, the mineralogift, and the mere amateur repair thither with avidity; and even women are amply indemnified for the fatigue of the journey by the pleafure arifing from the view of objeéts entirely new to_ them, and by the amiable and friendly reception they meet _with from the inhabitants, Every thing unites to make this excurfion, which is attended’ with no real dangers, the ufual obje& of all curious travellers who vifit Geneva and its environs. The more this journey prefents attraGions, the more it is of importance to make known the dangers to which travel- Jers who undertake it may be expofed merely by imprudence or inattention. Our principal view is utility, and without doubt it is of utility to make known, in all places where this journal may circulate, dangers which are indeed great to thofe ignorant of them or who forgot them, but of little importance to thofe who are forewarned or cautioned to avoid them. Had we treated this fubject fome years ago, the fatal accident which lately took place, and to which we were almoft witne{les, would not, perhaps, have happened. This reflection will not allow us to hefitate any longer. The experience I have acquired by travelling among the mountains, either when accompanying my illuftrious friend Sauffure, or in ten journeys undertaken to the glaciers of Chamouni ‘an particular, will perhaps entitle me to fome confidence from thofe whom I am defirous of faving from uneafinefs or * From Brbliotheque Britannique, No. 112. danger: 54 Fatal Accident which happened fo danger: I fhall, however, refer to the end of this article the cautions in this refpect which have been fuggefted to me by experience, and fhall proceed to an account of that event which induced me to take up my pen on the prefent fubject. C. d’Eymar, prefeé&t of Leman, an enlightened lover of the arts, and a paffionate admirer of the beauties of nature, having lately propofed to vifit the glaciers of Chamouni, a canton which at prefent forms the eaftern boundaries of the department under his adminiftration, invited me to accom- pany him; and I readily embraced his obliging offer. We fet out on the 7th of Augutt, and flept the firft aon at Sal- jenches, as travellers do in general. Next ‘morning, during our firft hoyr’s march, we meta _ young man on foot, accompanied by a peafant who was earrying a valife. We were ftruck with the melancholy and dejeGted air of this peafant. When we arrived at Servoz, three leagues from Sallenches, we learned from Deville, a very intelligent and experienced guide who attended us, that the morning of the day before, a ftranger, the companion of the young man we had met, being with his friend and a ~guide on the glacier of Buet, had fuddenly difappeared, at the diftance of fome paces before them, in a crevice of the gla- cier covered with fnow, which had given way under his feet. When they reached the mouth of the crevice, the bottom of which they could not perceive, the two furvivors.called out a great number of times, but in vain, ‘to their unfortunate ‘companion fwallowed up in the abyfs; and they did not quit the place till they had loft all hope of his fafety. M. Zimpf- ‘fen, the young man whom we met, when he arrived at Ser- voz, had given Deville a commiffion in writing,.to endeavour, if poffible, to difcover the bocy of M. Efchen, his friend, and to caufe it to be interred. As fearcely twenty-four hours had elapfed fince the event, the fenfible mind of d’Eymar was ftruck with a ray of hope, and he immediately and officially enjoined Deville (for he ~ hefitated, and not without reafon) to furnith himfelf with the neceflary means, to fet out in the utmoft hafte, accompanied by fuch a number of men as he prefumed might be necef- fary, and to give him an account of whatever fhould be the ‘refult. a Traveller on the Glacier of Buh, 58 refult. It was at leat a journey, of nine hours from Scrvoz to the glacier in queftion ; and as this glacier did not form any part of thofe we intended to vifit, it was impoffible for us to be informed of the iffue of the propofed fearch till we - pafled Servoz on our return from Chamouni, to which wé continued our route not without dejection. It is with regret that I am obliged to omit the details of the ftay we made in this interefling valley; they have a cha- racter which will always be imprinted in my remembrance, but they would be foreign to the prefent object. However, while the brave Deville and his companions are engaged with their enterprife, I fhall venture to fufpend the impa+ tience of my readers for a few moments in order to make them acquainted with the glacier of Buet, and the motives which might induce travellers to vifit it. Itis to Mefirs. De Luc, the two brothers, that philofos phers and naturalifis are indebted for difcovering the poffi« bility of reaching this fummit covered with eternal faow. It | is an infulated mountain fituated in front of the central chata to which Mont Blanc and its glaciers belong, and feparated. from them by a lower chain that runs ina parallel direGtion. This glacier may be feen from Geneva immediately on the left of the Mole. It appears under the form of a ridge not very falient, and which feems to be eafy of accefs. Mefirs. De Luc were, however, deceived in this refpe@, and the account of three attempts they made to reach it, the laft of which alone, on the 20th of September 1777, was attended with fuccefs, is one of the moft interefiing epifodes to be found in the works of any naturalift. It was a date to dif- cover the law which the decreafe of heat in boiling water follows in proportion as it is raifed in the atmofphere, that induced them to vifit this mountain, and to brave, three dif- ferent times, difficulties and dangers of various kinds to which they were expofed in attempting to reach a fummit that may be iaticlveee as the utmoft poffible boundary of philofophical obfervation. Honour to that feience which infpires courage fo perfevering, and which produces it in fucceeding generations! Our daring countrymen never ful- pected that, feventeen years after this expedition, Sauflure’ would 56 Fatal Accident which happened to would repeat their experiment on Mont Blanc itfelf, that is to fay, about 850 toifes higher than they were able to afcend after great danger and fatigue. ‘ Some years ago, a much eafier route for arriving at the fummit of Buet or La Mortine (for it is known by that name alfo) than that followed by Mefirs, De Luc was difcovered, and by this route I afcended it twice without experiencing any difficulty. You firft fleep at Chalets de Villy, the laft place of pafture of the valley which begins at Servoz and terminates at the glacier of Buet. From Villy you proceed to the Col de Salenton by a path practicable for mules; you then encounter the mountain on its eaftern and fouthern fides, and, pafling alternate declivities of fnow and flate, reach the fummit at the end of two hours and a half. The mean of two obfervations of the barometer which I made there, and which were very little different in their refults, gave me 1594 toifes for its height above the level of the fea. The mountain itfelf prefents nothing very interefting in a lithologic point of-view ; it confifts of flate intermixed with veins of rotten quartz, or quartz fimilar to ftalactites; but as a belvidere, nothing in my opinion exifts that can be com- pared to it. You here embrace at one view the whole fpace comprehended between Jura on the weft, as far as the mouths of the Rhone on the eaft, and, on account of this circumftance alone, I confidered this mountain as exceedingly proper for receiving fignals in an intended meafurement of a degree of latitude and two degrees of longitude in the pa- rallel of Geneva; a plan which may be found detailed in a memoir publifhed in the Philofophical Tranfaétions of the Royal Society of London for the year 1791 *. In * JT cannot convey a better idea of the fituation of this fpot than by quoting the words of M. De Luc:—« It is difficult to give a defcription in words when they do not awaken fenfations which have been felt; I do not, therefore, flatter myfelf with the hope of exciting in the minds of my readers thofe which I thenexperienced. The moft profound filence prevailed in thefe regions; we perceived that they were not made for living beings; they were as little known to our guides astous. The Chamois goats never approach them, and confequently no hunter had ever afcended fo far. 6‘ This a Traveller on the Glacier of Buet. b7 In my fecond journey to mount Buet, I was under the difacreeable neceffity of being conftantly enveloped by clouds “ This fenfation of profound folitude was one of thofe which we could moft-eafily explain, but it does not explain our fituation. We were on an immenfe extent of fnow, the whitenefs of which nothing altered. The rays of the fun, refleéted in a ftraight line from the fnow towards that luminary, fhowed us how fmooth it was; and this {moothnefs the imagina= tion extended to every thing around. We faw nothing but this fnow, and the heavens, towards which it was terminated in various folds, delicately rounded like thofe beautiful argentine clouds which are fometimes feen floating majeftically in the pure atmofphere. This was exactly what pro- duced the extraordinary fenfation which we then experienced. We actu- ally thought ourfelyes fufpended in the air on one of thefe cloands.— And what kind of air? Never had we before feen it of fuch a colour. It was blue, dark and bright at the fame time, which produced an inexpref- fible fenfation of immenfity. ‘¢ It was near noon when we arrived; and, on raifing our heads above the veil which fo long concealed from us the eaftern part of the horizon, we fuddenly difcovered the immenfe chain of the Alps in an extent of more than fifty leagues. On whatever fide we turned our eyes, the whole horizon was covered with mountains. Its boundary on the weft was no- thing but the thicknefs of the air; for we overlooked the chain of Jura, diftant about thirteen or fourteen leagues, fo much that we could have feen the plains of Franche-Comté and Burgundy, if the air had been fufficiently tranfparent. On the fouth-weft our view extended as far as Mount Cenis, and on the north-eaft probably as far as Saint Gothard. We were far raifed above all the defiles of the Alps, and only a few of their peaks were elevated above us. E> 6 In all this vaft {pace, where mountains were accumulated on each other, we could difcover no plain but in a fmall corner to the weft, the middle of which was occupied by Geneva ; and on the north-eaft we faw, almoft from one end to the other, the large valley through which the Rhone flows, from the place where it falls from the mountams, as far as Sion, the capital of the Valais, diftant from the piace where we were nine or ten leagues, All the reft was filled with mountains. © The details as well as the exfemble would have excited the attention of the moft indifferent beholder. A fingle view of the immenfe quantity of ice and fnow which covers the Alps will be {ufficient to fatisfy the fpeétator re(pecting the duraticn of the Rhone, the Rhine, the Po, and the Danube. It infpires us with an idea that this is their common re- fervoir, and that it is fufficient to fupply them with water during feveral years of drought. We compared, without having need of calculation, their ftreams with their fources, Thefe fources appeared to us only finall Vou. VIII. I rills -58 Fatal Accident which happened to clouds during the fix hours I remained on it. I was ex- ceedingly cold, and, in order to warm ourfelves, I and my: guides were obliged to conftruét a hut on the ridge of rocks neareft the fummit. We had at hand large pieces. of flate, and our building was fo folid that it ftill exifts, and has fheltered more than one curious traveller from the fe- verity of the weather. The glacier, which covers this fummit, differs from the greater part of thofe accumulations of ice known under that name in this refpeét, that the latter generally occupy the valleys, or the defiles in which the ice has not been ori- ginally formed, but to which it bas funk down by its own’ weight, and the preffure of the ice above it; whereas the ice of Buet has been formed in the place where it exifts; and at that height in our parallel the fnow never melts in fummer. This mountain, therefore, may ferve to determine with fome precifion the loweft boundary of the fnow in our climates. Thus, for example, by obferving from Geneva, through a telefcope furnifhed with a micrometer, the vertical angle comprehended’ between the fummit of the glacier and the loweft boundary of the fnow, I found it to be 16/14”, which, taking the diftance of Buet from Geneva at 29820 toifes, cor- refponds to 141 toifes, the diftance of this boundary below the , fummit, which places it at 1453 toifes above the level of the fea. _ It may here be afked, what is the mean annual tempera~ ture at this height in our latitude? We have pointed out fomewhere in our Journal a very fimple formula, which Sauffure deduced from a great number of obfervations, and which reprefents very well the law of the decrement of the mean heat of the atrnofphere from the bottom upwards. This decrement is a hundredth part of a degree of the thermometer of Reaumur per toife of perpendicular elevation, This for- rills, when compared with the valleys filled with ice, from which they flowed. Mont Blanc, which rofe above thefe valleys, feemed capable of furnifbing alone, for a long time, ‘a fufficiency of water for a river, fo much was it loaded with ‘ce from the top to the bottom ; that is to fay throughout a prodigious extent. —Recherches fur les Modifications de 1’ Atmofpbere, vol, ii. ps 390 ‘mula, f a ee ee Se 4 host a Traveller on the Glacier of Buet. 59 mula, therefore, applied to the mean temperature at the level of the fea, in the parallel of 46° (the latitude of Buet), as eftablifhed in Dr. Kirwan’s Work on the Temperature of the Globe, viz. 56°4° of Fahrenheit, or 10°,8 of Reau- mur, will give for 1453 toifes 14°53 degrees to be deducted ; which makes the mean annual temperature of the lower boundary of the f{now, in that parallel, to be 3°63 degrees below zero*. Tt is not furprifing, therefore, that this mountain fhould be crowned with a alaelee fince the fnow which falls there during the cold feafon, never entirely melts in the fummer. The water produced by the partial melting of the furface of the fhow filters through the porous fnow beneath it, and freezing in its interftices gradually converts it into ice. In this manner is formed an accumulation, the thicknefs of which M. De Luc endeavoured to efiimate from the follow- ing obfervation : “© We judged,” faid he, ‘ by the pofition of thefe fmall rocks, about 200 feet lower than the higheft part of the ice, that they formed a part of the real fummit of the mountain. The whole mafs above them was nothing but ice, in the form of a cone, cut through its axis, 200 feet in height, with a very extenfive bafe, and refting on the im- * I had occafion not long ago to difcufs this formula with a phi- loopher, who obferved to me, that, according to its nature, it was impolfible it could be correét; becaufe the denfity of the air, an ele- ment on which the prefervation of heat in the different ftrata of the atmofphere effentially depends, decreafes in geometrical progreffion 5 while the heights in toifes, which reprefent the temperatures, proceed in arithmetical progreffion. I admitted the juftnefs of the obfervation, fpeaking mathematically ; but, in a phyfical point of view, as the for- mula is compofed of co-efficients, fome of them unknown or inappre- ciable, which gives to the temperature an arithmetical progreffion, decreafing from the bottom upwards, itis no lefs true, that this formula, however deceptive it may be, reprefents the mean retults of obfervations fuffi- ciently well to be employed with convenience, when an approximative quantity only is neceflary: and this was exaétly the cafe. The queftion was the mean temperature of mount Saint Bernard, the philofopher was Bonaparte, and the difcuffion tock place at table, and even in the, apartment of the celebrated man whofe theory and calculations I was endeavouring to defend. 12 menfe 60 Fatal Accident, Be. menfe extent of permanent ice, which covers the whole de- clivity of the fummit.” But I learned, not without furprife mixed with horror, by the event, of which I am going to give an account, . that this glacier, fo often vifited by travellers, and which I twice traverfed myfelf with perfec fecurity, contains fome of thofe fiffures, covered with fnow, which renders others dangerous when the proper precautions are’ not employed. _ During our ftay at Chamouni, C. d’Eymar having heard that the guide, who accompanied the unfortunate Efchen, refided fomewhere in the valley, fent for him, to learn the particulars of the accident. When he arrived, defpair was ftill painted in his looks and whole countenance ; but we learned nothing from him that we did not before - know. He was a guide, felected by chance, who feemed to be little acquainted with the mountains, and who, however, as he told us, had requefted M. Efchen, when they arrived at the glacier, not to feparate from his two companions.. Hur- ried on, however, by that undefcribable fenfation which people fometimes experience when they reach high fummits, and obferving at the top of the glacier, a little diftance before him, two chamoy hunters, who were refting them- felves, he hurried forwards to join them ; 3 and it was then that he difappeared. We fhall now return to our narrative. As we paffed Servoz on the morning of the third day, the body of the un- ~ fortunate Efchen was conveyed thither. We viewed it with the livelieft emotion; and by minute infpeétion we were eonvinced that he had not furvived his fall a fingle moment,. NVe were fully confirmed in this opinion by the details which were given to us, and by obferving that three of the real ribs on each fide were broken, and that there was a great depreffion of the fternum; fymptoms which indicate that the unfortunate young man had experienced the moft fudden and ‘moft violent compreffion, The body was no ways disfigured, and his features, in perfect harmony, excited no idea oF his having fuffered pain. We learned by the paffport found in his packets, along with other articles, that his name was Frederick Auguftus Efchen; that he was born in ~ «On the Antient Egypiian Ibis. §1 in the bifhopric of Lubec, and that he was twenty-three years of age. { To be concluded in the next Number. ] VIII. Bemoir on the Ibis of the Antient Egyptians. By C. CuviER*. Bier one has heard of the Ibis, a bird to which the antient Egyptians paid divine honours; images of which they placed in their temples ; which they fuffered to wander about unmole(ted in their cities ; which they embalmed with as much care as they did their relations; to which they aferibed virginal purity, and an inviolable attachment to a country of which it was the emblem, and the figure of which the gods would have affumed, had they been forced te adopt one mortal. No animal ought to have been fo eafy to be diftinguifhed, for there is none of which they have left fo many cceatieue defcriptions, correct coloured fis gures, and even the birds themielvés carefully preferved with their feathers, under- the triple covering of that ftrong preferver bitumen, thick and — clofe bandages, and of ftrong vafes well covered with maftic. Yet among all the modern authors who have fpoken of the ibis, there is none but Bruce, a traveller celebrated by his courage and his knowledge of natural hiftery, who has avoided error in regard to the real fpecies of this bird; and yet his ideas, however corre&t, have not been adopted by naturalifts. After feveral changes, of opinion ‘refpecting the ibis, na- turalifts at prefent feem to agree in giving this appellation te- a bird, a native of Africa, nearly of the fize of the ftork, with white plumage, and the wing feathers black; raifed on lon red legs, and armed with a long bent bill, fharp at the edges, indented at the extremity, round atits bafe, and of a pale yel- low colour, and having its face covered.with a yellow fkin, deftitute of feathers, and not extending beyond the eyes. _™ Journal de Phyfigue, Frudtidor,, an 8, Such 62 Memoir on the Ibis of Such is the ibis of Perrault *, the white ibis of Briffon +, the white Egyptian ibis of Buffon t, the tantalus ibis of Linnus in the twelfth edition of his works; fuch is the bird which in the National Mufeum is called the Egyptian ibis, and which is there placed near, and not without rea- fon, to the curicaca of Margrave, or the tantalus loculator of Linneus, for they both haye a hooked, fharp, and in- dented bill. ‘Fo the fame bird, according to Blumenbach, who, however, confefles that at prefent it is very rare, at leaft in Jower Egypt, the Egyptians paid divine honours §. I participated in the error of thefe celebrated men above mentioned, till I had an opportunity of examining myfelf fome mummies of the ibis. This pleafure was afforded to me lately by Fourcroy, to whom General Grobert of the Artillery, on bis return from Egypt, prefented two of thefe mummies. On unwrapping it with care, we obferved that the bones of the embalmed bird were much fmaller than thofe of the tantalus; that they were fcarcely fo large as thofe of the curlew; that its beak refembled that of the latter, the length excepted, which was fomewhat lefs, and not at all equal to the tantalus; in a word, that its plumage was white, with the wing feathers black, as mentioned by the antients. We were therefore convinced, that the bird which the Egyptians embalmed was by no means our tantalus ibis ; that it was fmaller; and that it was neceflary to fearch for it among the genus of the curlew. After fome refearch, we found that the mummies of the * Defeription d'un ibis blanc et de deux cicognes in the Memoirs of the Acad. of Sciences, Vol. III, p. 61. Plate XIII. fig. 1.\ The bill is reprefented as truncated at the end; but this is the fault of the draftfinan. _ 4 Numenius fordide albo rufefcens, capite anteriore nudo rubro; la~ teribus rubro purpureo et carheo colore maculatis, remigibus majoribus, nigris, neétricibus fordide albo rufefcentibus, roftro in exortu dilute Juteo, in extremitate auranteo, pedibus grifeis.—Jér5 candida. Briflon Ornith. Vol. V. p- 349. + Hiffotre des Animaux, Vol, VIIL. 4to, p. 14. Plate I. Planches enl. No. 359. § Handbuch der Natur Ge/chichie, p. 203. Edit. of 1782. 9 ibis, the Antient Egyptians. 63 . ibis, opened before our time by different naturalifis, had been fimilar to ours. Buffon fays exprefsly that he exa- mined feveral of them; that the birds they contained had the bill and fize of the curlews and yet he blindly followed Perrault, in confidering the African tantalus as the ibis. One of the mummies opened by Buffon ftill exifts in the Mu- feum ; it is fimilar to thofe we have feen. Dr. Shaw, in the aaplement to his Travels*, defcribes and gives an exact reprefentation of the bones of a fimilar mummy ; the bill, he fays, was fix inches Englifh in length, and refembled that of the curlew, &c. Ina word, his defcription agrees entirely with ours. Caylus, in his Recueil d’ Antiquités +, gives the figure of a mummy ibis, the height of which, with its bandages, was only one foot, feven inches, four lines; though he fays ex- prefsly, that the bird was placed in it on its legs, with its head ereét, and that no part was bent back i in its embalmed ftate. Haffelquift, who confidered as the ibis a fmall white and black heron, affigns as his principal reafon for doing fo, that the height of this bird, which is equal to that of the crow, correfponds perfectly with the height of the mummies of the ibis{; how then could Linnzus give the name of ibis to a bird as large as the ftork; how, in particular, could he confider this bird to be the fame as the ardea ibis of Haf- felquift, which, befides its {mall fize, had a ftraight bill; and how could this Jaft error, in regard to fynonyms, be ftill retained in the Sy/lema Nature ? The only figure of the bill of an embalmed ibis, which does not accord with ours, is that given by Edwards §. It is a third larger than it ought to be; but as it contradi@s all the other teftimonies, we muft believe that it was taken * Edit. of Oxford, 1746. Plate V. p. 64—66. + Vol. VI. Plate 1X. fig.1. $ Iter Paleftinum, p. 249. Magnetudo galline, feu cornicis ; and p 250, Vala qua in fepulchris inveniuntur, cum avibus conditis, hujus {unt magnitudinis. § Plate 105. from ~~ fig Memoir on the Ibis of from the mummy of fome bird different from the ibis; or that the drafifman enlarged the proportions *. ‘It was neceflary, therefore, to feek for the real ibis fome- where elfe than among thefe birds of the tantalus kind, of a great height and with a fharp bill. In viewing the collection of bird, which Lacepede has arranged in fuch beautiful order in the Mufeeum of Natural Hittory, we difcovered a fpecies, never before mentioned or defcribed in any of the fyftematic authors except, Latham, and which alone corre- fponds to every thing indicated to us, by antient authors, ‘monuments, and mummies, as characters of the ibis. It is reprefented in the annexed figure (Plate III.) 5 it is a bird of the fize of the ‘curlew; its bill is fimilar to that of the curlew, but proportionally a little fhorter, and of a black colour; two-thirds of its head from the neck are bare of fea- thers, and covered with fhort black down; the plumage of the body, wings, and tail, is a dirty white, except the tips of ' the large wing feathers, which are black, and thofe of the Tower part of the back, which are of the fame colour, and, being long, fall over the tips of the wings when they are folded. The feet are black, and like thofe of the curlew. The individual in queftion formed part of the ftadtholder’s collection, but we are unacquainted with its native country. Defmoulins, who has feen two others, affures us that they were both brought from Senegal; one of them was even brought from that country by Geoffroy de Villeneuve: but, befides that. the climate of Senegal is in nothing different from that of the Nile, we fhall fee hereafter that Bruce found this fpe- eles in abundance in Egypt; and I imagine that the moderns will not admit, without fome latitude, the affertion of the antients, that the tbis never quitted that facred land. * Since I read this memoir, C. Olivier had the goodnefs to fhow me the bones which he took from two mummies of the ibis, anc to open with ns two others. Thefe bones were fimilar to thofe inthe mummies of General Grobert: one of the four only were fmalier, but it was eafily avferved by the epiphyfes that they had belonged to a young individual. C. Olivier fhowed us alfo a bill two-thirds longer than thofe found commonly in mummies of the ibis ; but this bi, however, was perfeétly fimilar to that of the curlew; and in particular to that of the*black ibis ef Belon; but ip no manner to that of the tantalus, Befides, . the Antient Egyptians. 65 Befides, this affertion would be as much contrary to the tantalus ibis as to our curlew; for the individuals which we poffefs of that fpecies, have been brought from Senegal. It was from this country that Geoffroy de Villeneuve brought the one in the Mufzum of Natural Hiftory : it is even much rarer in Egypt than our curlew, fince, according to Perrault, no one had ever faid that he faw it there, or had received it from that country. Since we are now acquainted with this bird, if we examine the works of the antients, and antient monuménts, we fhall find every difficulty vanifh, and that all their teftimonies agree with the beft of all, which is, the body of the bird itfelf preferved and embalmed. ‘* The moft common kind of the ibis,” fays Herodotus*, ** has the head and neck bare, the plumage white, except the head, the neck, the tips of the wings, and the rump, which are black. The bill and feet refemble thofe of the other kind of ibis:’’ and he had faid of the latter, “¢ they are all black, have feet like the crane, and a hooked bill.”” There are many modern travellers who do not give fach good defcriptions of the birds they obferve as that which Herodotus has given of the ibis. How could naturalifts apply this defcription to a bird having no part naked but the face, which is red? To a bird which has the rump white,:and not black? This laft character, however, was effential to the ibis. Plutarch fays, in his Treatife De Lfide et Ofrride, that the manner in which the white was mixed with the black in the plumage of this bird, made it appear as if marked with a crefcent; and, indeed, the union of the black of the rump with that of the two tips of the wings, which forms on the white a large femicircular in dentation, makes the white have a refemblance to that figure. It is more difficult to explain what he means when he fays that the feet of the ibis form with its bill an equilateral triangle. The paintings of Herculaneum +, however, place the mat- ter beyond all doubt. Some of thefe paintings, which repre- fent Egyptian ceremonies, exhibit feveral of thefe birds * Euterpe, + Plates, No. 138 and 140 of the edition of David; and Vol. IT. p- 335, No. 59; and p. 321, No. 60, of the original edition. Vou. VIII. K walking, 66 Memoir on the Ibis of walking in the courts of the temples: they are perfectly fimilar to the bird which we have pointed out: we may in particular obferve in them the charaéteriftic blacknefs of the head and neck; and it may be readily feen, by comparing their fize with that of the perfonages in the paintings, that it muft have been a bird of about half a yard in height at moft, and not.a yard, like the tantalus 1bis. The mofaic of Paleftrine exhibits alfo in its middle part feveral ibifes perched on buildings, and which are in nothing different from thofe of the paintings of Herculaneum. A far- donyx in the cabinet of Dr. Mead, copied by Dr. Shaw *, and reprefenting an ibis, feems to be a miniature of the bird which we arédefcribing. A large bronze medal of Adrian, an engraving of which is given in the Mufeum de Farnefe, and another of the fame emperor of filver +, exhibit figures of the ibis, which, notwithftanding their {mall fize, have a great refemblance to the bird in queftion. In regard to the figures feulptured on the plinth of the ftatue of the Nile at the Belvedere, and in the copy of it in the garden of the Thuillerics, they are not well enough finifhed to ferve as proofs; but we ftill have a fufficient number to obviate every doubt. We mutt do Bruce the juftice to fay that he difcovered thé real ibis t. . His abou-bann?s, compared with the bird we have defcribed, is fo fimilar, that it is hardly poffible not to confider it.as of the fame fpecies: and this traveller fays ex- prefsly, that it feemed to him to refemble thofe contained in the repofitories of the mummies. He fays alfo, that this abou-hannés, or Father John, is very common on the banks of the Nile; while the bird reprefented by Buffon under the’ name of the white Egyptian ibis, was never feen there by him. This abou-bannés has been inferted by Latham, in his Index Orniibologicus, under the name of Tantalus AZthio- picus; but he does not {peak of the conjecture of Bruce re- fpeéting its identity with the ibis, * Appendix, Plate V. + Mufeum de Farnefe, Vel. VI. Plate XXVIII. fig. 6.5 and Vol. ILL. Plate VI. fig. 11. t Vol. V. p. 172, Englifh edition. : All X the Antient Egyptians. 67 All travellers who preceded or followed Bruce, feem to have been in an error. Belon* gave the name of black Ibis to a bird, which is nothing elfe than a black curlew with a naked head, and.the feet and bill red; which does not agree ‘with the defcription of Herodotus, who fays that the black ibis is black all over. This bird of Belon is very common in colle¢tions; and yet as naturalifts fought alfo in the black ibis a tantalus with a fharp bill, the modern naturalifts have almoft all faid that Belon alone had {een this bird. Lacepede has rectified this error, and given the name of black ibis to the bird which had been diftinguifhed by that name by Belon. In regard to the white ibis, Belon believed it was the ftork; in which it is evident he contradicted every teftimony: no one, there- fore, has coincided in opinion with him in this point except the apothecaries, who have taken the ftork for their emblem, becaufe they have confounded it with the ibis, to which they afcribe the invention of injections. Profper Alpinus, who afcribes this invention to the ibis, gives no defeription of the bird in his work on the Medical Art of the Egyptianst. In his Natural Hiftory of Egypt ¢ he {peaks only from the information of Herodotus, to whofe account he only adds, I know not from what authority, that this bird in its figure and fize refembles the ftork. He fays he had Jearned that both the black and the white kinds were found in abundance on the: banks of the Nile; but it is evi- dent that he did not believe that he had ever feen any of them. Shaw, fpeaking of the ibis, fays§ that at prefent it is ex- ceedingly rare, and that he had never feen it. His emfeefly, tantalus ibis, is of the fize of the curlew, has a white body, and the feet and bill red. It frequents the meadows near cattle; its flefh is not well tafted, and foon fpoils. It may be eafily feen that this is not the tantalus, and ftill lefs the ibis, of the antients. * De la Nature des Oifeaux, Book IV. chap. 9, of the edition of 1556. 4+ De Medicina Agyptiorum, Lib. I. fol. 1. Paris, 1646. ~ Rerum Egypt, Lib. IV. cap. 1. Leyden, 1735- § Page 255, Emfeefly ox-bird K 2 Haffelquift ‘ ’ orox-bird, which Gmelin, very improperly, refers to the - 68 Memoir on the Ibis of Haffelquift was acquainted neither with the white nor the black ibis: his ardea ibis, is a fmall heron with a ftraight bill. Linneus, in his tenth edition, placed it, very pro- perly, among, the herons; but he was wrong, as I have al- ready faid, in tranfporting it asa caiieritie of the genus of the tantalus. Maillet, in his Defcription of Egypt*, conje&tures that the ibis may have been a bird peculiar to Egypt, which is ealled there Pharaoh’s capon, and at Aleppo, /apbanbacha. Tt devours ferpents. Some of thefe birds are white, and fome black and white, and it follows, more than a hundred leagues, the caravans which go from Cairo to Mecca, in order that it may feed on the carcafes of the animals killed in the courfe of the journey, while in every other feafon none of them are feen on that route. But he does not confider this conjecture as certain. He even fays that we muft give over attempting to underftand the antients when they fpeak in fuch a manner as if they had wifhed not to be underftood ; and he concludes with obferving that the antients perhaps comprehended, indifcriminately, under the name of zézs, all the birds which were ferviceable to Egypt in freeing it from thofe dangerous reptiles which the climate produces in abundance, fuch as the vulture, falcon, ftork, kite, &c. He was right in not confidering his Pharaoh’s capon as the ibis; for, though his defcription be very imperfeét, and though Buffon thought he could diftinguith in it the ibis, it may be readily feen, as well as by what Pococke fays, that this bird muft be carnivorous; and, indeed, we find by the figure which Bruce has given+, that Pharaoh’s capon is nothing elfe than the rachama, or {mall white vulture with black wings, vultur perenopterus, Linn., a bird exceedingly different from that we have proved to be the ibis. Pococke fays that it appears, by the defcriptions given of the ibis, and by the figures of it found in the temples of Upper Egypt, that it isa kind of crane. ‘ I have feen,” adds he, **a number of thefe birds in the iflands of the Nile; they were, for the moft part, grayifh ¢.’” Thefe few * Part IL. p. 23. + Vol. NOP. 19. t French tranflation of his Travels, 12mo. Vol. II. p. 53- words the Antient Egyptians. 69 words are fufficient to prove that he was no better acquainted with the ibis than others. The error which prevails at prefent in regard to the white ibis, began with Perrault; who is even the firft perfon who defcribed the tantalus ibis of the prefent time. This error, adopted by Briffon and Buffon, has paffed into the twelfth edition of Linneus, where it is confounded with that of Haffelquift, which had been inferted in the tenth, to form with it a compound altogether monftrous. It was founded on the very natural idea, that to devour ferpents, a fharp bill, more or lefs analogous to that of the ftork or heron, was ne- ceflary.. This idea is even the only good objection that can be made againft the identity of our bird and the ibis; for it may be faid, How can a bird with a weak bill, fuch as the curlew, be able to devour thefe dangerous ferpents ? But, befides that a reafon of this kind cannot hold out againft pofitive proofs, fuch as defcriptions, figures, and mummies; befides that the ferpents from which the ibis delivered Egypt were accounted exceedingly venomous, but not as of a large fize; I could anfwer direétly, that the mummified birds, which had a bill abfolutely fingilar to that of our bird, were real devourers of ferpents; for I found in one of their mummics the undigefted remains of the fkin and fcales of ferpents, which I prefented to the Clafs. This deftroys the objection that might be drawn from a paflage of Cicero, where he gives to the ibis a corneous and ftrong bill: having never been in Egypt, he imagined, from fimple analogy, that this muft be really the cafe. Our European eurlew, which has a bill ftill weaker than the ibis, devours eels, as I have been affured by an eye-witnefs. I fhall conclude this memoir with announcing the refults. The tantalus ibis of Linnzus muft remain a feparate genus with the tantalus locucator. Their character will be roffrum validum arcuatum, apice emarginatum. The other tantalus of the laft editions ought to form a genus with the common curlew. We may give them the name of numenius. Their character will be, roffrum graeile, arcuatum, apice inflatum. The ibis of the antients is not the ibis of Perrault and Buffon, “0 + Examination of the recived Doétrines Buffon, which is a tantalus; nor the ibis of Haffelquift, which is an ardea; nor that of Maillet, which is a vulture ; but a #wmenius or curlew, which has not yet been named by fyftematic authors, and of which Bruce has given a figure under the name of the ahou-hannés. I call it nwmenius ibis, albus, capite et collo nudis, remigibus pennis uropygit elonga- tis, roflro et pedibus nigris. ’ The tantalus ibis of Linneus, in the prefent ftate of his fynonymy, comprehends four fpecies, of three different genera : A tantalus, the ibis of Perrault and Buffon; An ardea, the ibis of Haffelquilt ; Two numenil, the ibis of Belon; And the ox-bird of Shaw. The reader may judge by this inftance, and many others, of the ftate in which the Sy/lema Nature fti]] remains, and of what importance it would be to free it gradually from thofe errors with which it abounds, and with which natu- ralifts feem to load it {till more, by accumulating, without choice and proper examination, fpecies, characters, and fy- nonymis. 1X. A brief Examination of the recetved Doétrines refpecting Heat or Caloric. By ALEXANDER TILLOcH. Read before the Afkefian Society, December 1799 *. To detail the yarious theories maintained at different pe- riods, and applied to explain the phenomena to which heat gives rife in the numerous changes prefented by Nature in chemical combinations and decompofitions, would be.taking up the time of this Society unneceffarily, as every member mutt be well acquainted with them. I fhall therefore confine myfelf to the modern doétrines on this fubjeét; and even with thefe I fhall be brief, as my chief object is, to inquire, Whether none of the circumftances that accompany the known faéts in this department of phyfics (fuch of them, I mean, as the limits I have preferibed to the prefent eflay will * For a fhort account of this Society, fee Note, p. 353, Vol. VIL. 4 , allow refpecting Heat or Caloric. a1 allow me to notice) have been overlooked? and whether, If all of them had been attended to, and the legitimate inferences _ been drawn from them, the theory now generally received would ever have been admitted into fcience ? The ground I am about to take may perhaps expofe me to the danger of being confidered as an innovator, or, what may be deemed worfe by fome, a fceptic as to certain opinions, rendered refpectable by-the great names that have embraced and maintained them; and at the fame time extremely plau- fible from the apparent facility with which they are applied to explain many phenomena that daily prefent themfelves to the eye of every attentive obferver. My only anfwer is, that I am .in fearch of truth; and fo decided an enemy to mere theoretical {peculations, that I neither admit myfelf, nor with others to admit in phyfics what cannot be proved to be truth. | When the human mind acquiefces on any ground fhort of this, it is either through mifconception, indolence, or pufil- lanimity, than which nothing has tended more to retard fcience and fhackle men with prejudices, leading them to receive great names for argument, and, for demonftration, long quotations. But, to proceed, I ufe the term beat to denote that fubftance which poffefles thofe properties, is go- verned by, thofe laws, and produces thofe effeéts which fhall be immediately enumerated; and I prefer it to the~term caloric* for no other reafon but becaufe the latter is em- ployed by many to denote heat exifting in a certain ftate, in which, they fay, it may be confidered as having actually loft its original charaéter: whereas I hold, and I even hope to conyince the members of this Society, that it invariably re- tains the fame chara¢ter, properties, and mode of action. * The term ca/oric has been’adopted in the new nomenclature to avoid that ambiguity and mifconception which might, it is faid, arife from em- ploying the fame term to exprefs a fubftance, and the fenfation produced by the aétion of that fubftancee By the fame mode of reafoning, all the fubftantives fhould be changed in any language that has fimilar verds. But fuppofe the argument for change, in the prefent inftance, to have full force in fome languages, it has little or none in regard to the Englifh, which employs the word warmth to exprefs the fenfation occafioned by ' beat. I hall, however, ufe the terms heat and caloric indifferently. (A) Heat | ' 92 Examination of the received Doétrines (A) Heat is diffufed through all the bodies in nature} whether folids, liquids, or acrifort fluids. (B) Heat tends to an equilibrium; fo that, when by any means it is accumulated in particular fubftances, a portion is quickly given off to the farrounding bodies to brirg the whole to one common temperature. On the other hand, where bodies have been deprived of a portion of it, heat is given off to them by, or heat paffes to them from, the furrounding bodies, to reftore the equilibrium. (C) Solids, by the addition of heat, affuine the form of Jiquids, and liquids the aériform ftate. On the other hand, gafes, by an abftraction of heat, become liquids; and liquids, folids. ; (D) The dimenfions of bodies are enlarged when heat is poured into them, and wice ver/a. The laws we have enunierated are general, and the objec- tions that may be ftated againft the truth of any of them fo few, and fo eafily obviated, that they cannot affect any in- ference drawn from them. The apparent exceptions relate chiefly to the change of volume in fome particular fubftances when pafling from the liquid to the folid form, or the con- trary. Water, for inftance, in paffing into the ftate of ice, affumes a larger volume, though heat is then paffing out of it. The fubftance, however, is only apparently enlarged. In freezing, the water affumes a cryftalline form; the cryf- tals, fhooting in every direction, crowd againtt, ‘and, as it were, joftle each other, caufing vacuities, which conftitute no real part of the matter. We may compare this pheno- menon to what takes place in a bundle of chips of wood, which will always, however clofely packed, occupy an ap- parently larger fpace than the fame weight of ligneous matter as arranged by nature in the tree. Another apparent excep- tion may be noticed in clay, which diminifhes the more in bulk the greater the quantity of heat poured into it: but here there is a mifnomer—it is not clay, but @ mixture of clay and water that is diminifhed in bulk. The water is driven off ;. and, where there is a diminution of matter, a reduction of volume mutt follow. Clay is therefore not aa exception to the refpeSing Heat and Caloric. "2 the general law—drive all the water out of it, that is, con- vert it into glafs, and it then obeys the general law. We {hail firft attend a little to the operation of the fore- going laws in fome given cafes; and afterwards examine the doctrines which have been eftablifhed from the pheno- mena obferved to accompany them: : If two bodies of the fame nature, unequally heated, be brought into contac, the heat will diffufe itfelf equally through them, and the quantities in each will bear the fame proportion to each other as the maffles themfelyes ; but, if the bodies differ in kind, though equilibrium take place, and each indicate the fame temperature, yet the proportions of heat in cach will not be as the maffes, but vary according as the bodies difier. (E) This property of bodies to hold different quantities Y heat, even when that fluid is ina ftate of equilibrium, Dr. Black calls the capacity of a body for heat ; the quantity itfelf he calls /pecific beat. ‘The diltinétion is perfeétly philofo- phical, nor need the terms be objected to; but they fhould be accurately defined, that they may never be employed to convey ideas different from the facts that gave rife to their adoption. | That the fenfe in which we underftand and ufe the terms may be clearly conceived, we fhall fubétitute another fub- ftance for heat, all other circumftances being as before. If -two fubftances of the fame kind (two pieces of chalk), un- equally wetted with water, be brought into contaé, the one will give off water to the other (or the one will abforb water from the other) till the quantity in each be as their maffes. If two bodies different in kind (chalk and weod) be thrown into water, the quantity they will cach take in will be as their capacities: this will alfo be the cafe if, inftead of throwing them into water, we fulpend both in the fame damp atmofphere; and the quantity in each, whether re- ceived by immerfion in water or in the atmofphere, is /pe- cific. Whe latter term matt be thus confidered, otherwife we fhall Jead ourfelves into error; for there is at leaft ag great a diflerence between the extremes of the general tem- perature in fummer and in winter as there is between a moift, and a comparatively dry (but yet moift) atmoiphere. You, VUI. L Some 74 _ Examination of the received Do€irines Some philofophers tell us that the caufe of this pbeno- menon of different bodies requiring different quantities of ca- loric to indicate the fame temperature (or, in other words, the caufe of their having different capacities for heat) arifes from the ‘different degrees of affinity which different bodies poflefs for heat! Is this an explanation ?—Different bodies hold different quantities of heat, becaufe they have different capacities :—Difierent bodies hold different quantities of heat, becauje they have different affinities !—yet we are to confider the one term as expreflive of a property, and the other as expreffive of the caufe of that property! Is this confiftent with that accuracy and precifion which fhould prevail in the language of fcience? But this is not all. Heat is confidered as exifting in two diftinét ftates ; free, and in chemical union. When heat is in equilibrio in any place; in other words, when a body is in equilibrio with the bodies which furround it with re- fpeét to its heat [that is, has received heat from the common ftock proportioned to its capacity]; that quantity which it contains is termed Jatent heat or caloric; com/ined caloric; heat in chemical union. We are told that in this ftate it is not perceptible by any external fign or organ of fenfe ; that it does not affect the thermometer, but remains qui- efcent in thofe bodies of which it conftitutes a principle ; and that it is then, more or lefs, in a ftate of confinement. Is the heat in any body termed Jatent becaufe the body has not a capacity to receive more? No; for if, by any means, an addition be made to the common ftock of. a_ pre- fcribed fyftem of -bodies, each individual fubftance will ftill provide lodging for a fhare of the added quantity, propor- tioned to its: capacity, in relation to the capacity of the reft, It fhould be obferved too, that, let the common temperature be what it may, if heat be in equilibrio, the portion in each body is, by fome at leaft, held to be /atent, in contra- diftinGion to what they term free heat. Hence it follows, that the quantity of Jatent beat in a given body differs in different feafons of the year; for heat may be in equilibrio in any fyftem of bodies in fummer as well as in winter. An aflemblage of different hodies, in equilibrio as to caloric, in Jamaica, vefpeting Heat and Caloric. i} Jamaica, the quantity in the whole is Jatent, and th each Specific and latent: the fame holds with regard to a fyftem of fubftances in England in the month of January. The heat in both cafes is detent. If the one fyftem of bodies could be tranfported to the other in a moment, and placed in contact with it, a portion of that heat which was latent in Jamaica, would be counted /ezfble heat in London ! This is exactly where the doétrine lands us when viewed gene- rally; and yet we are to confider heat as having two diftinct modes of exiftence! But let us take a clofer view of it: When by the paffing of a folid body into a fluid form the furrounding atmofpheré is found to have loft heat, this heat, they fay, has not been merely abforbed by the fub- ftance that has become fluid, but has become latent in it. When a liquid pafles into the aériform flate, the fame phe- nomenon accompanies the change, and alfo the fame af- fertion; and the doétrine is meant to convey the idea that heat has not only been changing its place, but has itfelf undergone a change as to its flate, its properties, and mode of aétion. It is a generally received axiom, that no more caufes fhould be admitted in phyfics than what are true and fuffi- cient to account for the phenomena. Let us inquire whe- ther this axiom be not violated in the cafes ftated, when re- courfe is had to the doétrine of latent, as diftinguifhed from free, heat, to aflift in explaining the phenomena. The dimenfions of bodies are enlarged when heat is poured into them (D). The primitive molecule (indepen- dént of the heat) of which the bodies are formed, are forced farther from each other by the, interpofed matter of heat. Continue the a¢tion of the fame caufe, their cohefion will be deftroyed entirely (C), and they will be diffufed through the predominating fubftance (heat), as the particles of fa- line fubftances diffufe themfelves through water when dif- folved in that liquid. In the cafe juft put for illuftratian, who ever fuppofes the water to have undergone any\change as to its effence or properties, whether direétly poured upon the faline fubfance or furnithed to it by the atmofphere. In chemical combinations it is admitted that we cannot, aim ane Li2 a {riri, 46 Examination of the received Doétrines a priori, determine the properties of the compound from @: previous knowledge of thofe of the ingredients. Every fubftance has, for one of its properties, @ capacity for beat. If two be united chemically, the capacity of the compound for heat may not be that of the fum of the capacities of the ingre- dients for the fame fubftance. Indeed it feldom or never turns out fo. If by any procefs then we ehange the capa~ eity of two or more bodies ; or, by uniting them, produce a third, whofe capacity for heat is greater than the fum of that of the ingredients, this new compound muft demand from the common ftock of heat diffufed through the atmo- fphere and other neighbouring fabflanees (A) am additional portion. Is there any thing in all this to lead us te the no- tion that the paflage of heat from the atmofphere, or other contiguous bodies, into the new compound, is the operation of any other than the general law by which heat tends to an equilibrium among all the bodies in a fyftem (B), and dif- fafes itfelf among them in proportion to their capacities for heat (E)? Is not the operation of thefe laws fufficient te explain the phenomena witheut the aid of any others? But, befides, is it not a general fact, i in all cafes whefe a capacity for a greater quantity of heat is produced ina com- pound than the fum of the capacities of the ingredients, that the fum of the volume of the compound is greater than that of the ingredients? And is it not equally true, that, when ingredients, before in union, are found, on being fe- parated, to have acquired capacities for heat, whofe fum is greater than was that of the body in which the ingredients. were united, the fum of the volume of the ingredients is greater than the volume of the compound was*? Can it be correét to fay that it neither affects our fenfes, nor is cog nifable by any external fign! when we can fee with our eves its effect in the increafe it has made in the volume of = Ac the rioment of writing I co not recolleé&ta fingle exception. In cafes where cryftallifation is concerned there may be fome apparent ones, asin the cafe of water and ice; but thefe wil! not affeét my argu- meat. Itis enough for me that she effect holds generajly in the cafes to which the doftrine of larent heat is applied—am efed perfe€tly con= fermabie (@ the general law (D), and allo cagnifable by our fenfes. the tefpetiing Heat and Caloric. wy the comipound fubftance before us; or in the fum of the mafies of two or more fubftances over that of the compound from which they were feparated ? Again—W hen gafes pals into the form of liquids, or li- quids into the folid ftate, heat is found to pafs from them into the atmofphere, “the heat that was latent in them before now becomes fenfible.” Was it not cognifable be- fore? It ought not to have been fo when latent. I find, however, that the volume of the body from which it has been feparated is now de/s than before; and this is exa@ly ~ what ought to take place from the general laws, not only of heat but of matter—a fubftance, heat, has been feparated from a body in which it formed a part of the mafs or yolume, and the remaining mafs is diminifhed in bulk. Let us, however, alter the mode of expreffion. A bedy, no matter by what means, is reduced into a Iefs vo-« lume; it is fo conftituted as to admit of this effet being pafled upon it; for one of its ingredients, heat, is'a fabtile fluid which may be diffodged; nay, will even run out, when the capacity of the body which held itis leffened. It is no way ftrange, in this cafe, that a fluid poured out of its recipient, and which, by its tendency to equilibrium, muft diffufe itfelf through the furrounding bodies in proportion to their capacities to receive it, fhould make itfelf manifett to our fenfe of feeling, we being immerfed at the moment in one of the neighbouring fubftances, the atmofphere, which affords a lodging fora portion of the diflodged heat, and ferves to tranfport other portions of it to all the neighbouring bodies. Nor is it firange that a fubftance which, while it formed an ingredient in the body from which it has been | removed, tonftituted alfo a partiofits volume, fhould, when it paffes into another body, mercury in a glafs tube, caufe an increafe in its volume proportioned to the quantity that has paffed in. It conftituted fenfible bulk in the firft body, and was Jatent beat; it conftitutes fenfible bulk in the fecond body alfo, but there it is fenfible heat!! Isthere no abfardity in al! this? Heat in thofe combmations, in which the term /afent 15 employed, not cognifable by our fenfes! Is it not obviotts from 98 New Publications. from the preceding ftatement that this is a miftake ? Be» fore the heat paffed out of its then combination it made a part of the volume which we contemplated with our eyes, aud the proportion that this part bore to the whole might, in many eafes, be determined by actual meafurement. Is fenfible heat, or rather heat in fuch combinations as it is im when that term is wfed, cognifable by any other means? To me it would appear as correét, when, by any powery the capacity of a veffel filled with a liquid. (water) is dimi- nifhed, to fay that the portion of liquid thereby ejected is fet at liberty; meaning thereby that it has undergone an effential change as to its form, properties, or mode of ex- iftence ; as to fay, when the volume of a fubftance contain+ ing heat is abridged, and a proportionate quantity of the heat is diflodged, that the heat, fo diflodged, has undergone any fuch change. The faét in my opinion is, the fubftance in which the caloric refided has undergone the change, where there is a change; not the heat: or, if it be changed, the change is of that kind which paffes upon a brick or any other body when we move it from one room to another. This, I think, mutt be pretty clear from what we have already ftated ;_but I hope to make it ftill more fo by examining a particular cafe or two which have been made to ferve for a foundation, as it were, for the doctrine which I oppofe. [ Vo be continued. ] NEW PUBLICATIONS. An Account of the Irides or Corone which appear around, and contiguous to, the Bodies of the Sun, Moon, and other Lu- minous Objects. Cadell and Davies, 1799. 46 pages. With One Copperplate. fi ne treatife is by the author of the Objervations on the Inflexions of Light, of which a {hort account was given in’ the Philofophical Magazine for September. In making thefe obfervations, that ingenious gentleman perceived that a ray Noi a weve tions. "9 a ray of white light, paffing between angular furfaces, fuch as the almoft meeting edges of two knives, was liable to be parted by its bendings, feparations, and other changes, into thofe differently coloured rays, which had been fuppofed by Newton to be the primogenial elements of pure white light. This obfervation is here applied to explain the formation of thofe zrides or corona, confifling of many-coloured circles, which are feen contiguous to the bodies of the fun, moon, &c. The order of the colours in thefe corone is as follows: 1. Next to the body of the luminary a circle of grayifh black, grayith blue, or faint diluted white, altering as it recedes into—2. A flrong lucid white of confiderable breadth. 3. Slender rings of yellow andred. 4. A fucceffion of rings of violet, blue, green, yellow, red. 5. Green, diluted yel- low, red; diluted green, diluted red. This is the common order; but it is occafionally varied-by flight irregularities. Newton has made the only plaufible attempt to account for thefe appearances. He fuppofes them to be produced by the rays of light falling upon globules of water, hail, or ice. He affumes that globules of ice or hail’ may, or ac- tually do, exift in fituations in the atmofphere in which they can receive the rays, fo as to produce that analyfis of the white light, and that diftribution of the coloured rays which thefe coronz exhibit. He conjectures that theie coronz in the atmofphere, furrounding the fun or moon, may be - produced in the fame manner in which a miniature ap- pearance fomewhat fimilar is occafioned by the reflexion of light from a Jens quickfilvered on the back-fide. But we do not know particles of hail or ice always to exift in the atmofphere when thefe many-coloured irides or co- ronz appear. The ordinary refraction of direét light, in its paffage through globules of liquid water, could not produce thefe appearances. Newton’s theory, though all that he poftulates were granted, would not explain that particular diftribution of thefe colours in the coronz, by which intervals or vacant fpaces are left between the different portions of the red and of the other colours. The iris, from a globule of eryftal having quickfilver on its further fide, is, according to Newton, produced, not by the reflexion of the main beam of light, 80 New Publications. fight, but by a faint light irregularly {cattered in every di- © reGtion from that beam: and a light fo faint would fcarcely be equal to the production of the many-coloured irides round the fun, moon, &c. in the circumftances in which thefe ap- pear; nor, indeed, could the globules of water fall under any light fo faint, where the main beam to whieh. they are ex- pofed is broader than their whole furfaces. On the other hand, the author of this effay has obferved that the arrangement of the colours and orders of colours in the many-coloured irides of which he treats, is not only im~ poffible by any refraction that can be fuppofed; but zs per- feGily the fame with the arrangement of the colours am the two fets of fringes into which a ray of white light, admitted into a dark chamber, and made to pafs between two parallel edges, is naturally divided. Each of thefe two fets of fringes, if takeh outward from the central line, exhibits precifely the fame arrangement of colours, as does the folar iris taken from its interior to its exterior extremity. He therefore concludes that, in the formation of the many-coloured irides, ihe fun’s irradiation, paffing between the edges of contiguous drops of water in the atmofphere, is, by the inflecting attrac- tion, which thefe exercife upon it, feparated into tivo fets of fringes, which fringes conftitute the wides, having the body of the fun for their central line. This is the author’s theory, Tt is at leaft admirably ingenious; more fimple and plau- fible than that which it ftrives to furperfede; and founded upon a better induction of unqueitianable facts. We fhould hope that the general difcuffion of philofophers mutt finally eftablith it as fcientific truth. The eflay is elegantly and unafiectedly written, A Treatife on the Chemical Hiflory and Medical Powers of fome of the moj? celebrated Mineral Waters, &c. By Wirirtam Saunpers, M.D. F.R.S., @c. Phillips, George-yard, Lombard-ftreet. 8vo. ‘483 Pages. THE more accurate analyfis of mineral waters by mo- dern.chemiftry, cafinot but lead national phyficians to efti- mate more juftly than before, the nature of their refpective medicinal powers. Ta New Piblicaiions. Si in the work now before us, Dr. Saunders applies, with vonfiderable fkill, the information of chemical analyfis to affift in explaining the proper remedial ufes of the waters of the moft celebéatetl mineral fprings in Britain and on the Continent. : His work begins with an account of the phyfital qualities and the chemical compofition of water, and of its natural fifes in the animal economy. He then examines, what ex- franeous fubftances are liable to exift in folution in water, and by what chemieal tefts or re-agents the prefence of any of them may be alcertained. A judicious chapter follows next, concerning the nature, as more or lefs falutary, of the waters in common ule. After this preliminary matter he defcends into a particular account of the cheimical analyfis and the medical ufes of three-and-twenty different fpecies of miferalifed waters. Thefe are, the waters of Malvern, Holywell, Briftol Hotwell, Matlock, Buxton, Bath, the Sea, Sedi:tz, Epfom, Seltzer, Tunbridge, Spa, Pyrmont, Cheltenham, Scarborough, Vichy, Carlfbad, Hartfell, Harrogate, Moffat, Aix-la- Chapelle, Borfet, Barese. A fynoptical table; exhibiting, in one view, the chemical compofitions of all thefe dierent waters; is fubjoined at the clofe of the chapter. The medical ufes of water, arc, next, more particularly confidered. Water in gericral, as he here ftates, is ufeful, ii proper quantity, to dilute and fufpend the folids which are taken into the ftomach, fometimes to ftimulate languid di- geftion 5 foinetinies, perhaps, to retard that which might be otherwife too rapid. In acute difeafes, its internal ufe as a diluent is highly beneficial. Tepid water, taken in moderate dofes, aéts, generally, as an agreeable fiimulant to the fto- mach. natural hiftory, as is that of Sir Ifaac Newton in natural phi- lofophy, or that of Lavoifier in chemiftry. In this volume Dr. Shaw gives the firft part of 4 general fyftem of zoology, in which the arrangement of Linneus is to be chiefly followed. Quadrupeds, birds, amphibia, fifhes, infects, vermes, tef{taccous animals, zoophytes, are to be comprehended in the fyftem. It is to be completed in ten or twelve volumes. The prefent volume comprehends the hiftory of the primates, bruta, and fer, the three firft orders in the clafs of mammalia or viviparous quadrupeds. The peculiar advantages of this fyflem are, as the author hopes, to arife from the combination of the arrangement of Lin- neus with the materials contained in the works of Buffor and Pennant; from the correction of errors relative to fyno- nyms 5 the inftitution of new {pecies ; the addition of more clearly diftinétive {pecific characters; from the communica-~- tion of thofe new faéts in natural hiftory which have becn learned in late voyages to the South Sea, and particularly by obfervations made in the great ifland of Auftyalafia, or New Holland. The deferiptions are illuftrated, as the title- page exprefles, with engravings of the forms of many of the animals deferibed. ‘Phefe engravings are copied trom the avorks of Buffon and other naturalifts, from various original drawings, and from fpecimens in the Leverian and the Britifh mufeeum. ‘The hiftory of thirty-eight different genera of quadrupeds is contained in the firft volume. The en- eravings are, in general, well executed by Heath and other artifts. It is extremely probable that the whole work, if conducted to an end with the fame care and fkill which appear in the firft volume, will prefent a fuller and more correct fyftem than has been as yet pubtithed of our knowledge in zoology, Its chief merits are, great clearnefs and accuracy of defcrip- tion, fidelity of reprefentation in the engravings, cafe and perfpicaity of Ayle, jult diferinsination as to diftinétive cha~ raéters, and the increafe which it affords of the namber of known animals. ‘Its chief imperfeétions are, that the authar appears to have fiudied more in cabinets of curiofities, than by converfing with living nature; that he allumes for his autho. r] M2 rities 84 New Publications. rities in facts, rather the writers of former fyfiems, than the narratives of original obfervations from which thofe writers ‘ compiled ; that, while intent chiefly upon accurate deferip- tion, he has told little, except in a few popular inftances, of the manners, habits, and local relations of the quadrupeds which he defcribes, The Afiatic Refearches; or Tranfaétio®s of the Society in- fiituted in Bengal for inquiring into the Hiftory and Anti-« tiquities, the Arts, Sciences, and Laterature of Afia. ‘al, VIL Calcutta, 1800, We are happy to find that this Society ftill continues its Jabours with unabated fpirit and induftry. The contents of this volume are; x. A Difcourfe detivered by Sir Robert Chambers, Knt. . Prefident.—2. ‘Narrative of a Journey from Agra to Onjein, —3. An Account of the Inhabitants of the Poggy or Naffau Iflands, lying off Sumatra.—4. Obfervations on the Theory of Walls, wherein fome Particulars are inveftigated which have not been confidered by Writers on Fortification.—5. On the Poifon of Serpents: Supplement to the foregoing Paper. —6, An Account of Petroleum Wells in the Burmha Coun- try.—7. On the Maximum of Mechanic Powers, and the Effects of Machines when in Motion.—8. On the Religion and Literature of the Burmas.—g. Narrative of a Journey to Siripagur. Enumeration of Plants noticed in the preceding Tour. Letter fron® Sir C. W. Malet, Bart. to the Prefident, on the Subje& of the following Paper:—r10, Defcription of the Caves or Excavations on the Mountain about a mile to the Eaftward of the Town of Ellora.—11. Remarks on fome Antiquities on the Weft and South Coafts of Ceylon; writ- ten in the Year 1796.—12. On Mount Caucafus.—13. On, the Antiquity of the Surya Siddhanta, and the Formation of Aftronomical Cycles therein contained.Appendix. Rules of the Afiatic Society. Members of the Afiatic Society. INTEL- { 8% J INTELLIGENCE, sabi MISCELLANEOUS ARTICLES. LEARNED SOCIETIES, ASLATTIC SOCIETY. Ace Afiatic Society inftituted in Bengal for inquiring into the Hiftory and Antiquities, the Arts, Sciences, and Lite- rature of Afia, having refolved to give with each fubfequent vo- lume of their Refearches a litt of fuch orienta] fubjects as re- quire further jlluftration, and to invite communications on the fubjeé&t, have fele&ted the following, and prefixed them to their lat volume, lately publithed at Calcutta. 4. Religion, Policy, Jurifprudence, Manners, and Cuftoms. t. An accurate defcription of the different feftivals and fafts prevalent in India; together with an inveftigation of their origin, and of the reafon and fignification of their pecu- liar ceremonies. As thofe are very numerous, the following are fpecified as obje&ts of primary inquiry : Among the Hindus—Doorga Pooja, or Dufferah; Kalce Pooja, Dewalee, Jonmon Afhtomer, Churkh Pooja. Account of the pilgrimage to the temple of Jaganatha, at Purfotom. Among the Mufulmans—Eed ul Zoha, Eed ul Fetr, Eed Ghudeer. 2. An enumeration of the different cafts of Hindus, with the cuftoms peculiar to each, as exifting in the prefent time, See an enumeration from the antient Sanforit records, Afiatic Refearches, Vol. V. p. 53. ‘ 3. A connected hiftory of the feveral Mufulman tribes ex- ifting in India: among thefc, an account of the fingular tribe known by the name of Boras, is particularly required. 4. What 86 A fiatic Society. 4. What kinds of oaths are confidered as peculiarly bind- ' ing by the different tribes and feéts in Hinduftan ? 5. What hiftorical monuments remain of the government, and the fyftem of police which obtamed in Hinduftan pre- vioufly to the Mufulman invafion ? UE Geography. 1. A catalogue of the names of towns, countries, pro- vinces, rivers, and mountains, from the Schafiers and Pu- ranas, with their mcdern names annexed; and a correé& lift, ,according to the oriental orthography, of the towns, &c. mentioned by Major Rennell and other European geogya- phers. The etymology, as far as practicable, would alfo be defirable. 2. What were the geographical and political divifions of the country before the Mufulman inyafion? * HI. Eiography. x. Accnrate tranflations of the accounts given of the lifg . and actions of Bouddha, by the pricits of his fect. 2. To inquire if there be any accounts remaining of Chauchafan, Gonagom, and Gafpa; whom the Burmas re- prefent as having preceded Godama, 3. The hiftory of Mahamoony, a difciple ar follower of Godama; to whom alfo adoration is paid by many among the worfhippers of Bouddha. 4. A hiftory of thofe faints, philofophers, &e. etther male or female, who have become famous, in modern times, among the nations and religious fects that inhabit India. IV. Commerce, Natural Hiftory, Materia Medica. 1. To inquire into the ftate of the commerce of India previoufly to the firft fettkement of Europeans. 9. To afcertain the different trees which produce gamboge, or a gum_-refin refembling it: to invettigate the qualities of the drug as procured from each of thofe trees, among which we may. reckon the following:—Cambogia gutta, Linn.; Garcinia celebica, Linn.; Sialagmitis cambogioides, Koen.3 Hypericum pomiferum, Rox. To procure accurate figures of 7 the Afiatic Society. 87 the fialagmitis cambogisides, or the Ceylon tree, and of the tree which yields this drug in @ambodia. Laftly, to deter- mine whether all thofe trees may not be referred to one genus, 3. To afcertain from what country the root commonly called columbo'is procured, and to give a botanical defcrip- tion and figure of the plant to which it belongs. 4. The botanical names of plants mentioned in the Hindu books of Materia Medica. 5- Fo fupply the deficiencies which remain in the accounts of the production of borax in the neighbourhood of Tibet and Napal, as delivered by Mr. Blane and Father Jofeph de Ravato in the Philofophical Tranfactions, Vol. LX XVII. 6. Whether the tobacco plant was known in Afia before the difcovery of America; and whether the edict, faid to have been publithed by Aurunzebe, againft the ufe of that plant, be authentic? V. Medicine and Surgery. t. Hiftory of that peculiar inflammation of the fehneide- rian membrane termed zakra, with the mode of treatment by the natives. 2, Hiftory of inoculation for the fmall-pox among the Hindus. 3. Antiquity of the veriereal difeafe in India; and the know- ledge which the antient Hindu phyficians had of its cure. 4. Their treatment of the leprofy; with fome account of the different fpecies of that difeafe which are met with among the natives of India. 5- How long have the natives poffeffed the art of couching for a cataract, and from what fource did they obtain it? VIL Language, Literature. 1. How many dialects are there of the Hinduwee, 2. ¢. of Janguages connected with the Sanfcrit ;) and in what parts of India were they or are they fpoken? 2. What general term had the natives of India before the Mafulman invafion, to defignate what we imply by the term Hindu. To obtain as full a catalogue as poffible of books.in the Sanfcrit bs Elatoral Academy at Erfurt. Sanfcrit and other Hinduwee languages, contaitiitig the fols lowing particulars, as far as they can be afcertained, viz. thé names of the authors, the fubjeéts, the dates, the age of thé moft antient manufcript of each tow khown to exift; and the places where the books are now to be found. ELECTORAL ACADEMY OF THE USEFUL SCIENCES AT EREURT. In the fitting of Febrvaty the 4th, Dr. G. H. Thilow communicated to the Academy an account of fome experi- ments he had madé ih regard to Galvanifm. Thefé experi- ments were a continuation of his former ones *, and tend ‘fill further to confirm the idea that faltpetre poffeffes the peculiar property of weakening the nervous fyftem. This he afcertained by feveral experiments. Having cut off a portion of the crural nerve, which had been laid bare, and weakened or deprived of its irritability by faltpetré; he laid bare another portion towards the knee, and, by ftrewing hitre over it, deprived it in a few minutes of all fufteptibility of irritation. ‘The fame thing always took place as far a8 the toes whenever a new portion of the nerve was Jatd bare: The author thence concludes that the vital power is not to- tally extinguifhed even when it cannot be excited By the ftrongett ftimulants applied to a nerve which has been feveral times fubjeG@ed to the action of fome fimulant. The heart ofa frog laid bare, and ftill in connection with the furround- ing parts, ahd which contracted and expanded with great vivacity, being firewed over with a little faltpetre; its move- ment was by thefe means immiediately checked: though thé author had taken the heart from the thorax, the fore-legs of the animal ftill moved with fuch ftrength, that the whole upper part of the body was thereby agitated from one fide td the other. Some drops of warm miilk, let fall between fome of the mufcles and nerves; ipeedily put an end to this violent movement. Thefe firiking phenomena the author endea= voured to explain from the circumfiances of milk removing obitinate {pafmodic affections, and reftoring the equilibrium of the mufcular and nérvous fibres. He had obferved alfo, re 1}. AS Sa Ny Jae ee 74 " “ee Philogphical Magazine, Vol. Vi. p. 284. \ feveral French National Inftitute. 89 feveral times, that perfons, whofe fibres were too rigid and tenfe, were often troubled with crampifh affeftions, and frequently fuffered from violent flatulencies. He always found that their complaints were increafed by bitters or car- minatives in general, but that they were leffened by the ufe of lukewarm milk. The fame author read fome obfervations on the ufe of the German opium. As foreign opiumis brought to Europe in ‘an impure and imperfeé “fate, it is of importance to dif- cover fome fubftance that might be fubftituted in its ftead. Profeflor Trommfdorff found fuch a fubftitute in poppy- heads, from. which he has prepared a tinéture. Dr. Thilow ‘having made fome experiments with this tinG@ure in the Clinical Inftitute of Erfurt, obferved that it fully anfwered expectation in cafes of flux, fpafms in the ftomach, gout, and byfterics*, FRENCH NATIONAL INSTITUTE. C. Olivier lately read before this fociety fome obfervations on the jerboa. His objeé was to rectify an error into which the antients and moderns have fallen, in regard to the manner in which the jerboa walks; and to make known the yery fingular organization of the genital parts of the jerboa, mus jaculus, Linn., mus fagitta, PALL., to compare them with thofe of the alaéaga, and to defcribe more at length the fpecies men- tioned by Linneus, under the name of mus dongipes, im- properly confounded with the mus meridianus of Pallas. The jerboa is reprefented in an erect pofture on the Cy- renean medals; Herodotus, Ariftotle, Theophraftus, Pliny, &c. among the antients, and Paul Lucas, Buffon, Alla- mand, Pallas, Vic. d’Azyr, &c. among the moderns, have all confidered this fmall quadruped as a biped, that is to * Tt may be gratifying to our readers to learn that a premium for the production of opium in England, offered by: the Society for the Encou- ragement of Arts, Manufactures, and Commerce, was awarded in their laft Seffion to a gentleman who produced a confiderable .quantity from poppies, which was found, by proper trials, to contain all the requifite properties, Vox, VIII. N fay, Pa go French National Inftitute. fay, an animal which walks on its hind legs alone. Olivier has rectified this error by his own obfervation, which, om this point, perfectly agrees with the ftruéture of the body of the animal, as it does not allow it to remain long upright on its tarfi. ; The penis of this quadruped, as obferved by Sonnini *, is furnifhed with two long offeous hooks near each other, and placed towards the middle of the upper part of the glans. The latter is guarded befides with papil/z, almott of an offeous nature, bent back and fhaped like afpoon. In the alaétaga, the mus jaculans of Pallas, the glans is merely covered with pa- pille, in the form of fpikes, almoft ftraight, rounded and directed backwards. The tefticles are concealed in the ab- domen ; and the orifice of the vulva in the female appears to be confounded with that of the anus. The defcription which Olivier gives of a fmall fpecies found by him in Egypt, and which, in fize, is nearly equal to that of a rat, is perfetly applicable to the mus longipes of Linneus; except that the latter, according to Linnzus, has only four toes on the fore feet, while that of Olivier has five; but it may be poffible, fays Olivier, that Linnzeus did not ‘pay attention to the thumb, which is indeed yery fhort. As there is great confufion in the fynonymy of authors, Olivier endeavours, at the end of his memoir, to rectify their miftakes. At the fame time he gives the fpecific charac- ters of the fpecies, which, in his opinion, belong to that genus. ; 1. Dipus cerfer pedibus pofticis tetradaétylis. 2. Dipus jerboa pedibus pofticis tridaétylis. 3. Dipus ala@aga pedibus pofticis pentadactylis, latera- libus multo brevioribus. 4. Dipus gerbillus fupra flavus fubtus albus; pedibus pofticis pentadaétylis, digitis fubaqualibus. Decandolle communicated to the Firft Clafs of the Infti- tute a monography of the bilocular leguminous plants. The bilocular leguminous plants are thofe, the fruit of which are divided into two cells by a longitudinal partition, com- * Foyageen Egypie, Vole I. p. 133. plete _— -— French National Inftitute. ot plete orincomplete. Tournefort has given a fe&tion of them . in his family of the papilionacet. Linneus has eftablifhed them into three genera: the biffemlu, characterifed by its indented feed ; the phaca, the feed of which ought to be femi-bilocular; and the a/fragalus, where the feed is bilo- cular; but thefe two laft genera are not fufficiently diftin& ; for that reafon Lamark united them. Decandolle has re- tained that arrangement, but he has changed the charac- ters and rendered them more diftinét. The genus of the phaca has for its character a carina, fur- nifhed with a long ftraight point; a feed with two longitu- _ dinal cells, fometimes complete, but for the moft part in- complete, formed by the folding back of the upper future, This genus comprehends twenty fpecies, viz. phaca febirica; Linn.; pb. myriophylla, muricata, fylvatica, oxyphylla, pro- Strata, PALL.; aftragalu verticellaris, alpinus montanus, cam- peftris, pilofus, LInN.3 a/fir. foetidus, VILL. 3 aftr. deflexus, PAaLu.; aftr.annularis, Fors«.; and feyen undefcribed {pecies. The phaca alpina, auftralis betiea and rigida, are referred to the colutea. The genus affragalus is diftinguifhed from the preceding by its obtu/e carina, and its feed with two lon- gitudinal cells, fometimes complete, or for the moft part in- complete, formed by the rep/z of the ower future. It compre- hends 125 fpecies, 36 of-which are nondefcript. This vaft genus had been divided into three fections, according as the ftalk was herbaceous, ligneous, or nulls but thefe divifions are not correét. Decandolle has divided the genus into twa feS&tions, according as the ftipule are diftin& from the pe- tiole, or adherent to it. The firft fection comprebends the fpecies with yellow or purpurine flowers. The fecond is di- vided into three fubdivifions; the firft has the ftipule ad- herent to the petiole and the ftalk, and the petiole herba- ceous and not fpinous; the fecond has the petiole not fpinous and cadugque; the third has the petiole fpinous perfiftant, and the folioles caducous. Thefe are the tra~ gacantha of which the old botanifts made a genus; but the fruétification prefents no character, and exhibits the . fame variations as thofe of the other aftraguli. The phaca, affraguli, baguenaudiers, and feveral other Na gencra 9%: French National Enjlitute. genera In different families, have the verficular pericarpium ‘filled with air. Decandolle has obferved, that if this air be analyfed at the moment when it is collected from the pe- ricarpium, it is found to be of the fame punity as atmofpheric air; but if this pericarpium be immerfed in water, the air lofes its purity, and in the courfe of about a day no oxygen gas is found in it. The fame thing takes place in the fun as well as in obfcurity. The total quantity of the air does not appear to the eye to be diminifhed. Is the oxygen gas converted into carbonic acid gas? or, rather, does it not ferve for the nutrition of the feed. What tends to fupport. this idea is, that Humboldt found that the tunics of the feeds coutain azot almoft in a fiate of purity. This fatt comcides with an obfervation which Decandolle made before on the veficles of the fucus veficulofus ; he oblerved that thefe ve- ficles contained atmofpheric air when they had remained fome hours out of water, amd azotic gas when they had been fome time immerfed in it. Thefe fats deferve the attention of phyfiologifis. It is well known that gum tragacanth is furnifhed by cer- tain fpectes of the affragalus, called on, that account /fra- gacanthe. It appears that feveral fpecies of this divifion pofiefs the fame property; according to Tournefort, the - afiragalus creticus furnifhes this gum in the ifland of Crete; and the ajlragalus gummifer furnifhes fome of it alfo in mount Lebanon, according to Lubillardier. It appears: that it, was the a/fragalus echinoides, from which Profper Alpinus; as he fays, faw this gum dittilling. Ina word, O]ivier afflures us that the gum ufed in commerce comes neither from Crete nor from Lebanon, but that the place of its deport is Aleppo; and that it is brought thither from Perfia, where indeed the fhrub that produces it is found. It is a tragacantha not yet defcribed. The anti-fyphilitic properties of the aftragalus exfcampus, have of late been much extolled, and ftill require coniifma- tion. The rarity of this plant prevents it from being-fub- jected to experiments. Decandolle recommends making them on the aflragalus ineanusy and monofpefulanus, which grow. ta France; and which feems to he analogous to the former. The Noa , 1 French National Inflitute. 03 The exiftence of ornitholites in ftrata of fubmarine forma- tion, is ftill contefted by feveral naturalifts. The celebrated Fortis has even publifhed a memoir in which he proves that no well afcertained inftances of this circumftance had ever been known. Mention had indeed been made in feveral works of thofe found at Montmartu; but fome doubts ftill remained. C. Cuvier, however, has lately prefented to the Inftitute a fofil which feems to have all the characters of an orni- tholite. Itis a leg compofed of a portion of the femur, a tibia, and a tarfus, in one piece; three toes, one of which has three, the fecond four, and the other five articulations, and the veftige of a fpur. Thefe members are not found but in the clafs of birds alone. This leg was incrufted in that kind of gypfum which in large {trata occupy fuch an immenfe fpace around Paris. It was found at Ville-Juif, in the third mafs, that is to fayy about fixteen yards lower than the ftrata which contain the bones of quadrupeds already defcribed by the fame author. _ C. Vidron, mufic matter at Paris, having announced a difcovery he had made, by means of which perfons born deaf could be enabled to hear mufic, Haiiy, Lacepede,; and Ca- vier, were appointed to examine this difcovery, and to make a report on the fubjeét to the Inftitute. It appears from this report that the apparatus employed by C. Vidron confifts of a fteel rod, one end of which he places on the lid of a harp- fichord, and the other between the teeth of the deaf perfon. This rod is furnifhed alfo with a branch terminated by a knob, which refts in the pit of the ftomach, and fometimes alfo with a fecond, applied to the cranium. The commif- fioners mentioned that feveral authors have announced that certain deaf perfons had been made to hear mufical founds by eftablifhing a communication between their teeth and the inftrument by means of a rod, goblet, or other body. Of thefe authors they mentioned Fabricius ab Aquapendente, Schellhammer, Boerhaave; ‘Winkler, and Joriffen. They endeavoured, in particular, to determine how far this ipvention might be of utility cither in regard to the different: kinds of deafnefs, or in regard to the different kinds of found, which et French National Inftitute. which one may with to communicate. They gave themfelves an artificial kind of deafnefs by ftopping their ears, and re-— moving to a great diftance. In both thefe cafes, founds were perfecily heard by the fteel rod, and the founds appeared to them to come from the infide of the rod, and not from their real place. But the refults were different with refpe&t to fome perfons actually deaf, on whom the experiments were tried: Some of them heard very diftintly; but the greater number declared that they experienced only a brecivelitts movement, more or lefs general. The commiffioners conclude that this nethGe may be em- ployed with fuccefs m cafes of deafnefs which arife only from fome obftructions in the external part of the auditory paflage, but that it is ufelefs in thofe occafioned by a paralyfis of the nerve, or any effential derangement in the interior organs, which, unfortunately, is moft commonly the cafe, efpecially in thofe born deaf. They are, however, of opinion, that it ought to be tried on young perfons who are deaf; for, even if there were found only one ina hundred capable of deriving benefit from this refource, it would at any rate be one fource more of enjoyment to fuch an individual. In regard to articulate founds or words, the commiffioners, found that it is hardly poffible to hope that they can be con- veyed with accuracy by this apparatus, at leaft in its prefent flate. In the fitting of Auguft 23, General Dugua, who had re- turned from Egypt, having brought with him two copies of a remarkable infcription found on a black granite of an ex- ceedingly fine grain, prefented them to.the Inftitute. This monument was difcovered in digging up the earth at Fort Elleve, near the Bogar of Rofetta, two leagues from that town. It was not brought to Cairo till after Buona s depar- ture, and was depofited in the Inftitute of that city. The difcovery was made by C. Bouchard, lieutenant of engineers, : who was appointed to fuperintend the repairs of the fort. Two members of the commiffion of the arts were employed at Cairo in taking copies of this monument, unique of its kind, in order that it might be preferved whatever might 7 happen, French National Inflitutes 95 happen. The firft was C. Marcel, director of the national printing-office in Eygpt, who poffeffes extenfive knowledge and an indefatigable zeal for acquiring more. By a fimple typographic procefs he obtained copies with the charatters inverted, but which could be eafily read by means of a mirror. » The fecond was C. Conté, chief of the brigade of aéroftats, who, by his knowledge of mechanics and the arts, had always been one of the moft ufeful men in the colony. He employed the procefles of engraving to obtain copies, which at firft gave the charaéters inverted ; but thefe copies being put under the prefs, gave others fimilar to the in{crip- tions. The infcription is in three different characters ; one portion prefents a feries of hieroglyphics, in feveral lines exceedingly regular; another which has not yet been fufficiently ex- amined, exhibits a great number of lines in characters which ftill leave fome uncertainty, and which require a more pro- found refearch. The laft portion is compofed of fifty three lines, written in Greek. Laport-Dutheil one of the mem- bers of the clafs of literature and the fine arts, immediately began to tranfcribe this part; and communicated to the clafs a part of its contents. He afterwards made known the fubftance of nearly the whole of it, having tranfcribed the firft thirty-eight lines. According to his explanation, it ap- pears that the infcription is a monument of gratitude from the priefts of one or more temples, either of Alexandria or fome place in the neighbourhood, to Ptolemy Epiphanes. A literary man of eminence has already publifhed fome obfervations on the firft explanation given of the Greek text. If the infcription be in honour of Ptolemy Dionyfius, fays he, it follows that the date of it muft be 63 years before the Chriftian era; on the other hand, if the infcriptions exprefs the fame thing, it thence follows that the hieroglyphic language was in ufe even fo late as 200 years before Chrift *, though * The Apocalypfe furnithes a dire&t proef that it was underftood, even fubfequent to the Chriftian gra. If commentators had attended to this fact, and followed the hicroylyphical acceptation of the figures em- ployed 95 ‘ . Foffils. though it is commonly believed among the learned, that in the time of Herodotus, that is nearly 500 years before Chrift, the knowledge of this language was already loft. Since’ thefe mfcriptions were prefented to the Inftitute, Bonaparte has ordered engravings to be made of them, in order to gratify the curiofity of the learned in all countries. v FOSSILS. Faujas St. Fond has lately brought to Paris fome curious foffils, having on them the impreffion of plants; which he found under lava at the depth of twelve hundred feet. Juffieu, Des fontains, and Lamark, have obferved that feveral of thefe impreffions belong to plants common in Europe at prefent; fuch as leaves of the chefnut tree, of the birch, mountain-afh, the maple, an entire cone of the pinus /ylvefiris, and a portion _ of acone of the pinus fativa. Fabricius and Latreille dif- covered in them alfo the impreffion of an infe&, which is the common hydrophylus or water-beetle.. Faujas St. Fond intends to publifh an account of this difcovery, illuftrated with engravings, ployed in that book, inftead of giving their own opinions, founded on a fuppofed refemblance of the figures tothe objects to which they arbitrarily applied them, they would have come nearer to the author’s meaning than they have done.—Epir.. ERRATA IN VOL. VII. Page 356, |. 21, for bis r. their: p.360, |, 5. for herr. the: p. 362, laxty for mere x. more: p. 372, 1. 4, for fulpbat, x» fulpburet,. THE | PHILOSOPHICAL MAGAZINE, NOFEMBER 1800. A foort View of the Obfervations which have been made at Kifferent Times on the Luminous Appearance of the Seas Read in the Phyfical Society of Gottingen, by J. G. In BLuMHorFrF*, Daurre are many things in nature of which we know - flothing more than that they exift: refpeting the manner in which they exift, and for what purpofe, we are entirely ig- norant.. They are often the objeéts of our wonder and ad- miration ; but, owing to the imperfection of our faculties, we can acquire no fatisfactory knowledge of their nature. The only courfe, therefore, which, as rational beings, we can purfue in fuch cafes, is to endeavour, by the help of con- jectures, to open a way to truth; and, when this cannot be accomplifhed, to endeavour to appro as near to it as pof- fible. This, indeed, may often be effected with fome degree of fuccefs, by admitting certain hypothefes, or fundamental principles deduced from analogy, efpecially when our re- fearches are conduéted with accuracy and perfeverance. It. may be proved by innumerable inftances, taken from the hiftory of the fciences, that hypothetical and conjectural explanations have often conducted mankind to the difcovery of immutable Jaws, and truths of the greateft importance. To explain the phenomena of nature, has always been * From Magazin fiir den Neueften Zufand der Naturkunde, &c. Vol.I, part 4. Vot. VIII. OQ the 98 On the Luminous Appearance of the Sea. the employment of philofophers; and yet there are many of them refpecting which our knowledge is very uncertain. But how is it poffible for fuch fhort-fighted beings as men are, to have, at command, and employ in a proper manner, all thofe external circumftances which are neceflary for the thorough examination of fuch phenomena? A thoufand things occur daily in nature which it is impoffible for our coarfe organs to perceive, and much more to obferve in a perfect manner: in this paper, however, I fhall not defcend to microfcopic objects, but offer a few remarks refpeéting a phenomenon which frequently occurs, and which has at- tracted the notice of many celebrated philofophers—I mean the luminous appearance of the fea. This phenomenon, which exhibits fo magnificent a fpeétacle to navigators, and which, when beheld for the firft time, muft excite aftonifh- ment, deferves certainly to be examined with more care and attention. I fhall here, therefore, take a’fhort view of the information which has been collected on this curious fubjedt., That the water of the fea fometimes exhibits a lurainous appearance in the night-time, efpecially when ftruck by the rudder of a fhip, or ftrongly agitated by its refiftance to the motion of the veffel, is a circumftance well known; and this phenomenon appears fometimes, in calm weather, like. multitudes of {mall ftars difperfed over the furface of the fea. It frequently happens, alfo, that the places only next the fhip or the fhip’s wake, or the track through which fifth have paffed, appears luminous. The well-known Americus Vef- pufius, the Italian navigator, according to Kircher, was the firft perfon who obferved this circum{ aoe In Lichtenberg’s Magazine for the lateft Difcoveries in- Phyfics and Natural Hiftory *, we find the following de- feription of this phenomenon as obferved in the Baltic :— <¢The phofphoric phenomena in the Baltic generally appear in the darkeft nights, with an undulating motion, in the track formed by yettels 3 in their progrefs hrouph the waves. The water feems to emit a lively light, which is fometimes of a pale red colour, and has the ‘eletahdaiioe of fparks. _Some- fimes it exhibits the appearance of a regular ftream of fire in ~ * Vol. IT. part iv. p. 48. the \ On the Lumineus Appearance of the Sea. 99 the fhip’s wake. This phanomenon is feen fometimes alfo when the wind blows, but not with that majeftic appear- ance as during a calm. It is worthy of remark, that, when veffels are lying at anchor, this phenomenon is obferved here and there, darting itfelf from one place to another with great vivaciiy, behind the veffels, even when they make little or no motion.” This defcription agrees in the moft effential parts with that of Gentil, who obferved the fame phenomenon in the Indian feas, particularly in the channel of Mozambique. On one occafion the fea appeared to this Navigator and his whole crew to be entirely covered with fire, and each wave to confift of a mafs of phofphoric matter. The fhip feemed as if moving up and down in a fiery lake. Someof the ropes reflected the light fo ftrongly, that the people on board could have read by it. The fire of Saint Elmo ap- peared alfo at the fame time on the fummit of the mainmatt *. Boyle + fought for the caufe of this phenomenon in cer- tain general laws of the earth, or of our planetary fyftem ; - but, had this celebrated philofopher contidered the fubje& “with a little more attention, he would have found that it may be explained on much better principles Father Bourzest, during his yoyage to India in the year 1704, had feveral times an opportunity of obferving the lu- minous appearance of the fea, and has given us a very valu- able account of the phenomenon. The light was often fo ftrong that he could read by it the title of a book, though he food’ at the height of nine or ten feet above the furface of the water. Sometimes he could diftinguifh the luminous * Nous eumes dans ces parages de fi mauvais temps, et entr’ autres une nuit fi éppuvantable, que la mer fembloit étre tout en feu: chaque lame €toit pour ainfi dire un phofphore : le vaifleau paroiffoit étre dans un étang de feu. Nous étions a la cape fous la mifaine: cette voile refléchiffoit la Jumiére de Ja mer 4 un point, qu’on efit dit qu’elle étoit’ éclairée par la jumiére d’un trés grand nombre dé fanaux; et on ett pu lire auprés de la relingue de cette voile, & la. faveur de cette lumiére refléchie de la mer. Le feu de St. Eime Paw un inftantau haut du grand mat.—Voyage dans les Mers d’ Inde, Vol. » p. 657- Mi Philofophical ree ae Vol. LIX. p. 450. $ Lettres édifiantes, Vol. IX, Philofophical Tranfactions abridged, \ a V2 (Dy 203s 02 parts 100 On the Luminous Appearance of the Sea. parts from thofe that were not fo in the fhip’s wake. The former exhibited in part luminous points and in part fmall luminous globules, fome of which were from one to two Jines in diameter, and others as large as a man’s head. Sometimes they formed ftreaks from three to four lines in length, and one or two lines in breadth: fometimes they re- fembled luminous vortices, which, according to the anthor’s expreffion, appeared and difappeared fnddenly at certain pe- riods, like flathes of lightning. Father Bourzes obferved alfo, that the paflage of fith through the water was marked by a ftream of light, fo that it was often poflible to diftinguifh their fhape and fize’ He remarked alfo a number of luminous particles in the water drawn up from the fea, when he ftirred it round with his hand in a dark place. Thefe luminous particles he obferved alfo on a piece of linen which he had dipped in fea-water, when jt was wrung in the dark, and even when it was half dry. This attentive obferver confiders the principal pS of thefe phenomena to be a kind of greafy vifcous matter in the water of the fea, which arifes perhaps from putrefac- tion, becaufe he thought that the water, the fatter it feemed, and the more covered with fcum, always emitted the more light. In confirmation of this opinion he ftates, that having caught a bonetta, its mouth appeared fo luminous in the in- fide that he could fee to read a book by it. On examina-. tion, the mouth of the fifth was found to be full of a vifeous matter, which being rubbed over a piece of wood, the latter became alfo Juminous in the dark, but the light it emitted ceafed as foon as the matter became dry. The experiments of Canton, mentioned in the Philofo- phical Tranfaétions *, feem to coincide perfe¢tly with the above defcription of father Bourzes. I thall therefore give a fhort account of them, as they are the moft accurate we have on the fubjeét. On the evening of the 14th of June 1768, Mr. Canton put fome frefh whitings into fea-water, and found that they emitted light for twenty-four hours. In the cellar where he depofited the veflel which contained * Vol. LIX. p. 446. them, On the Luminous Appearance of the Sea. 3OT them, Fahrenheit’s thermométer ftood at 54°. The water itfelf, when at reft, was quite dark; but, when a ftick was drawn through it, the whole part through which the ftick had paffed became luminous, and no light appeared any where elfe. When he agitated the whole water, it became luminous throughout.. When the fifh had lain in the water forty-eight hours, it was then brighteft: at the end of three days, though ever fo much agitated, it emitted no more light. The fea water, however, exhibited a much more luminous appearance when a herring was placed in it. The third night it was fo ftrong, that, when ftirred, a perfon could tell by it the hour on a watch; and at thofe moments the fifh feemed to be an opake hddy. After this period the light decreafed more and more, but it ftill continued, in fonfe degree, till the feventh night. Another veffel containing frefh water, into which a frefl herring was put in the like manner, continued entirely dark, without emitting the leaft trace of light. The thermometer during the time f{tood always above 60°. River water, in which falt was diffolved till it appeared by a hydrometer that it had acquired the gravity of fea water, exhibited the fame phenomena as water brought from the fea: in water to which more falt was added, the fith emitted no light. It appears from thefe experiments and thofe of Sir John Pringle * that the falt in fea water promotes putrefaction ; and that therefore the luminous appearance of fea water arifes from a difpofition to putrefaction, or a commencement of it. Experiments on the fhining of fith in falt water have been made alfo by other philofophers befides Canton: among thefe we may mention thofe of Boyle and Dr. Beal in the Philo- fophical Tranfactions ¢, and thofe of Martin in the Tranfac- tions of the Swedith Academy f, all of which feem to con- firm, in a greater or lefs degree, that the luminous appear- * Experiments on Septic and Antifeptic Subftances. + Philofophical Tranfactions, No.°31, p. 5815 and No. 13, p. 226. t Swedith Tranfaétions, Vol. XIII. p. 225. ance ! f For On the Luminous Appearance of the Sea. ance of fea water is owing toa commencement of putrefacs ~ ‘tion *, ' 3 “ tg Another circnmftance which has been proved by thefe ‘obfervations is, that heat deprives putrid bodies’ of their lu- munous property. This circumftance did not efcape Canton; for he remarked that, though a ftrong unite heat pro- moted putrefaction, a heat twenty dégiecs higher than that: of the blood feenred. to prevent it. This he difcovered by the following experiment :—He put a fmall piece of a fifh © which had Becsuiee annie into a globe of! thin olafs, immerfed it im water heated to 118° of Fahrenheit, and ob- ferved that it was deprived of its luminous property in lefs than a minute: on being taken from the water, however, it recovered its luminous property in tem feconds, but the light It emitted was not fo {trong as before. Spallanzani does net agree in opinion with Canton, that the luminous appearance of fifh. arifes from patrefaction +. He repeated Canton’s experiments with a variety of fifh, but he fucceeded only with a very few of them. Thofe _which. did not emit light he found in general to be the fat- teft, though, according to Canton, thefe ought, above all others, to conymunicate a luminons appearance to fea water. Another circumftance, which feems contrary» to /Canton’s hypothefis, is, that if the noéturnal luminous appearance of the fea were occafioned by the oleagmous remains of putrid fith, as thefe remains always float at the furface the light ought to be confined to the furface of the water; which ex- perience fhows not to be the cafe. '. Vianelli, a phyfician of Chioggia in the neighbourhood of Venice t, Grizzelini, a Venetian phyfician, the abbé Wollet §, and Dr. Prieilley, afcribe the luminous appearance _ * That feveral kinds of fith, fuch, for example, as the /epia, thine in the dark, is weil known. - + Memorie di.Matematica e Fifica della Soc, Italiana, Vol. II. p- 603. ~ & Nuove Séoperte intorno le Luci notturne dell’ Aqua Marina.— Pipes , §. Nouvelles Obfervat. fur la Seslonendee Marine, and the abbé Nollet, in. the Mémoires de Acad, des Sciences 1750, p. 88. of On the Luminous Appearance of the Sea, 103 of thie fea to phofphoric infects*, The abbé Nollet, in par- ticular, while at Venice in the ah 1749; paid great atten- tion to this phenomenon, and was confirmed in at opinion by the following obfervation:—Having remarked that the fea water in the harbour of Portofino emitted a ftrong light, he lay down on the edge of the water ; and, ftretching his head over it, he faw Hele infects {pring up, as infects in ge- neral do, from the bottom of the water, which was covered with fea-weeds. . When he attempted to catch them in his handkerchief, he found on it only luminous fpots, which he could fpread over it with his finge 1 Le Roi, during a voyage up “the Mediterranean, obferved that the head of the ae , as it pafied through the waves, threw up in the daytime a multitude of fmall particles, which at night had a fiery appearance t. He is not,' however, in- clined to afcribe this phenomenon to infects, becaufe, having, collected fome of thefe luminous particles in bis handker- chief, he found them to be round bodies like pin-heads, withont any appearance of animal organs, though he exa- mined them with a microfcope. But he does not deny that, there are luminous infects in the fea, though he is of opinion that its luminous appearance arifes from ote other caufe, which he does not further explain. Fougeroux de Bondaroy ¢ and father Teaahia afcribe the caufe of the luminous appearance of the fea toa multi-_ tude of {mall nereids, the hinder parts of which the former found to be endowed with the property of emitting. light. This is the cafe in particular with the xerzis noétiluca Linn. | * Some of the feolopendra, as the fcolop. elefrica and the Jeol. pha phorea L. really thine in the night-time. According to Hablitzl (fee Goth. Maz. Vol. 11. Part4, ‘No. 159), a cable drawn up from the fea emitted a very lively light, which arofe from its being covered with the fea flea (carcer pulex); a proof that thofe animals fhine in the dark. + Obfervat. fur une Lumiére produite dans Ja Mer, in the Memoires: prefentées, Vol. II]. p. 144. ¢ Sur la Lumiére que donne l’Eau de 1i Mer principalement dans lesLa- ° gunes de Venife, in the Mein, de |’ Acad, des Sciences. Paris 1767, p. 120. § Vorbereitung zur Naturgefchichte von Spanien, Halle 1773. 4to. || See Linn. Syft. Nat. Vol, I. edition 13. p. 10855 alfo his Ame- nitat. Acad. Vol. ill. p. 203. tab. 3. 5 Toe — \ ‘¥O4 On the Laminous Appearance of the Sea. The celebrated Forfkal, who accompanied Niebuhr as 1144 turalift in his travels through Arabia, having caught a great - number of marine animals, among which there were dif- ferent kinds of medufz, put. fome of them into a bucket full of water. After keeping them fome time, he threw, the con- tents of the bucket from a window, in the dark, and obferved that all thofe places where the water fell feemed to be co- vered with fparks of fire. He made feveral experiments on ~ this fubjeét, all of which convinced him that the luminous appearance of the fea arifes from infe&ts. Bartholinus alfo, and Donati, afcribe the luminous appearance of the fea to marine worms (molu/ca). Silberfchlag afcribes the luminous appearance of fea watet to phofphorus, the component parts of which may exift iti the fea as well as in the atmofphere. It is not improbable that feveral kinds of worms, which, according to various obfervations, have been confidered as luminous, may be in- debted for that property to marine phofphorus adhering to them. It has been found, by repeated obfervations, that the water of the fea, even at the depth of forty feet, is phofpho- refcent; and the abbé Spallanzani is therefore inclined to believe that this is the cafe alfo at every depth. Refpefing the luminous appearance of the fea water, however, he gives no decifive opinion, and confiders every thing hitherto faid on the fubjeét as mere conjectures. Mr. Erich Schytte remarks, that when fea water is con- verted into ice it retains its Juminous property; and that, when fea water is diftilled, the luminous matter does not pafs over, but remains behind in the ftill. Profeffor J. Mayer, in a paper publifhed in the Tranf- actions of the Royal Bohemian Society on the luminous appearance of the Adriatic, fays, that the water at the furface feems to imbibe the rays of light in the fame manner as a light magnet. This luminous appearance is obferved more at the furface than at any depth in the water, and difappears. when, by violent agitation of the waves, the water at the fur- face becomes mixed with that below. This author, however, is of opinion, that there are in the water foreign particles which emit a ftronger light, and which may be feparated 9 : from ’ : ‘ On‘the Luminous Appearance of the Sea. 105 from it, but there are no proofs that eleétricity has any hare in the phenomenon. M. Bajon, on the other hand, confiders the hindi dlne ap- pearance of the fea as electric, and, in fupport of this opinion, remarks that it is never obferved but when fri€tion is pro- duced by fome body paffing over or through the water. For this reafon the light is always feen very ftrong around fhips, and where great numbers of fith are colleéted together. The aétion of the atmofphere may alfo excite this light at the furface of the fea. It is promoted by a north wind, and is interrupted by a fouth wind, as well as by damp weather, &c. This opinion, in the moft effential parts, agrees per- fetly with that of M. De la Perrier, and of J. R. Forfter. M. Le Gentil alfo concludes, from obfervations made in the Indian feas, that this phenomenon is produced by the electricity of the fea water; for he obferved it only under certain cafes; as for example, when the heavens were filled with clouds, and the fea high, and much agitated. He ob- ferved it, however, during calms; but this was never the cafe except when a ftorm was to be apprehended. As long as the ftorm continued, the fea had a luminous appearance ; but as foon as it was over, the light ceafed. When the weather was in the ufual ftate, that is to fay, when the winds were regular, even though they were ftrong and the fea rough, he obferved nothing of the phenomenon. He failed upwards of fix hundred leagues with a ftrong weft wind and very high fea, but did not obferve the leaft fpark of light. They appeared moft abundant in winter, which is the period when the winds change, and when ftorms and hurricanes take place. M. Le Gentil afferts that at this period of the year he never wifhed to obferve the fea lumi- nous, becaufe he confidered it as a fj on of bad weather, and could always, with certainty, fcreiel by it when a change -was to take place. This phenomenon is more common in the Indian feas than in thofe parts on this fide of the Cape, between America, Europe, and Africa. M. Le Gentil afcribes the eleétricity of the fea to the dafhing of the waves againft each other, which muft naturally produce frition. | I hope I fhall be forgiven if I here add the following va- Vor. VIII. P luable 106 On the Luminous Appearance of the Sea. luable obfervations on this fubje&t by profeffor Forfter, of Hale. This celebrated navisator and naturalift obferved this phenomenon on the night of the 2gth of October 17725 during a frefh gale, a few miles. from the Cape of Good Hope. He faw alfo a great quantity of {mall luminous bodies floating on the fea, fome of them near and others at a con- fiderable diftance from the fhip. He caufed fome of the fea water to be hauled up ina bucket, in which he found an immenfe number of {mall globules which moved with great est naps , When the water was fuffered to ftand fome time ‘at reft, thefeluminous globules became lefs numerous 5 but, when agitated, ‘they relumed their lumincus property. Mr. Forfter found, when he examined fome of thefe globules, that they had life and organifation, but they died before he could wath them from his fingers. Profeflor Fortier diftinguithes three kinds of light in the fea, which feems to agree pretty well with the beforemen- ‘tioned obfervations. “The firft kind, he fays, muft be afcribed to eleétricity, becaufe the quick motion of thips through the water, efpecially when the wind is ftrong, occafions a violent friction ; and becaufe the agitation of the waves pro- duced. by the wind heats the waves more than the atmo- fphere above them. The refin, pitch, and tar, with which the outfide of fhips is covered, and the conducting property of water, render the probability of this phenomenon being connected with electricity fill ftronger. ‘ The fecond kind of light appears, in a proper fenfe, to be phofphoric. A great many animal bodies, by putrefying ia the fea, become decompofed, and confequently their come ponent parts, and particularly the phofphoric acid, are dif- engaged. An addition of inflammable matter forms with this acid that mixture which is commonly known by the name of pho/phorus*. Thus, fifth which are.dried in the air become fometimes phofphoric; and this is the cafe with the, ocean itfelf, when, after a long calm, it has been filled with * Profefior Forfter’s reafoning, here quoted, is agreeable to the old theory. _ We have no right to alter his words; and it will be feen by our chemical readers that the facts might as eafily be accommodated to the modern theory. putridity Submerfion of Swallows in Autumn. 107 putridity and corruption; as heat and tranquillity contribute to promote the fpeedier folution of animal fubftances. F ith, as well as velatinous animals, contain oily and inflammable particles, with which the liberated phofphoric acid may rea« dily unite and form a phofphorus on the furface of the fea, and give rife to this wonderful phenomenon. The third kind of light arifes, no doubt, from living ani- mals which float in the fea, and mutt be produced by their peculiar organifation, or rather their component parts, which deferve to be better examined by chemical experiments. Thefe conjectures of Dr. Forfter contain, in my opinion, the moft fatisfaétory explanation of this phenomenon. All the effects of it hitierto obferved may be referred to fome of the above-mentioned caufes ; and the general conclufion that may be deduced trom them is, that as thele effects have been feen under different circumtlances, they muft be explained by different caufes. II. On the Submerfion of Swallows in Autumn, sa our fourth Volume, p. 414, we’ laid before our readers an interefting letter on this fubjeét from Mr. Peter Cole to Dr. Mitchili of New York, to which we refer. Such rela- tions are often que(tioned ; but in natural hiftory, as in other branches of fcience, the evidence of pofitive faéts is never to be controverted by mere inferences from other fuppofed or real phenomena. Mr, Cole is a gentleman whofe veracity will not be queftioned by thofe who know him, and we have therefore no right to doubt the truth of former relations of , a fimilar nature merely becaufe we know not now the cha- racter of the relaters. The late Hon. Daines Barrington took the trouble to collect a number of teftimonies of fimilar fub- merfions obferved im England, which were publithed in the Philofophical Tranfactions, and we fubjoin another teftimony of fuch phenomena being obferved in the New World. New York, 28th July 1800. ** On the afternoon of the 24th of Auguft 1798, I was fitting in my parlour, which looks towards the North Pa River, 108 Submerfion of Swallows in Autumn. River*, about fifty feet from the bank, in company with our mutual friend Mr. Jacob Sebor. Our attention was attracted by numerous flights of birds, which appeared to come acrofs the town from the éaftward, and defcénd immediately into the river. So fingular an appearance excited our particular obfervation. “We went out and ftood clofe to the bank, and then pereeived- that what we at firft imagined to be black birds were aétually fwallows; and that, as foon as the va- rious flocks had cleared the houfes, and got direétly over the river, they plunged into the water and difappeared. This was not confined to the vicinity of the place where we ftood, but was the cafe as far as the eye could reach, up and down the river, and continued without ceffation for nearly two hours, when the clofing of the evening prevented our further obfervation. «© Aware of the importance of affording any additional information on this long difputed queftion in the natural hif- tory of the fwallow, I procured a telefcope, and watched at- tentively many of the flocks from their-firft appearance until their immerfion, continuing my eye fixed upon the fpot long enough to be fully convinced that not one of the birds re- turned to the furface again. Indeed, one flock of abont two hundred birds plunged into the water within thirty yards of us, and inftantly difappeared, without the leaft appearance of oppofition that might be expected to arife from their na- tural buoyancy; and at the fame time ‘the evening was fo ferene, and the river fo unruffled, that ‘no deception of our fight could poffibly have occurred. «© When, the birds firft came in view, after croffing the town, their flight was eafy and natural; but when they de- {cended near to the water they appeared much agitated and ‘diftreffed, flying ina confufed manner againft each other, as * The houfe of Mr, Pollock is fituated near the margin of the Hudfony about two hundred yards from the battery. The river is about a mile and a haif wide, and from feven to nive fathoms deep, and runs with a ftrong and rapid tide. Mr. Pollock does nor recolleét the fpecies of fwallow which then difappeared. The barn fwallow (brrusdo ruflica), chimney {wallow (Srrundo pelafeia), the fand or bank martin (Airundo. riparia), andthe purple martin (dirundo purpurca), all frequent and build their habi- tations in this city and its neighbourhood. ¢ i Fatal Accident, &c. 109 if the love of life, common to all animals, impelled them to ‘revolt againft this law of nature impofed upon their {pecies. ‘ As fome time has elapfed fince the above-mentioned facts occurred, I thought it proper, before I gave you Mr. Sebor’s name, as having been a witnefs to them, to confult his re- colleétion on the fubjeét, and I have pleafure in affuring you he citinétly remembers every circumftance I have recited, and of which I made a memorandum at the time.’ It may be worthy of remark, that, as far as my obfervation went, the fwallows totally difappeared on the 24th of Auguft 1798; for, during the remainder of that year, I did not fee one. «© H; POLLOCK.” III. Account of a fatal Accident which happened to a Tra- veller on the Glacier of Buet; with fome Cautions to thofe who through Curiofity may viftt the Mountains of Swiffer- land, and | danteiclanls the eee By M.A. PicTet, Profefjor of Philofophy. [Concluded from Page 61.] r D’EY MAR, in confequence of a report from two offi- cers of health, refpecting the inconveniences which might arife if Efchen’s funeral fhould be deferred, gave the necef- fary orders‘in our prefence for interring the body in a proper and decent manner. For this purpofe we made choice of a fpot which would neceffarily be feen by every traveller going to Chamouni, and even by thofe who might afcend the gla- cier of Buet by the route of Servoz and Villy, in confequence of the intention expreffed by the prefect that a monument erected over the grave of this unfortunate young man, with a fuitable infcription, while it preferved a remembrance of the event, might forewarn travellers of the dangers to which they would be expofed in traverfing the glaciers without taking proper precautions, and without paying to the information of their guides that attention to which it ought_to be enti- tled. While preparations were making for the interment, we interrogated C, Deville and his companions with much intere(t, 110 _ Fatal Accident which happened to intereft, refpecting their expedition to the glaciers, and the following account is drawn up from minutes written down at the time: “* In confequence of the order of C. d’Eymar, praefeét of Leman, C. Jofeph Maria Deville, after caufing a harpoon to be forged, and providing ropes, fet out, accompanied by his two fons John Claude and Bernard, and Jofeph Ettle, inn- keeper at Servoz, in order to proceed to the glacier of Buet in fearch of the ftranger fwallowed up by a fiffure in the fnow. They left Servoz at feven in the evening, and tra- velled the whole night. «* Having arrived on the glacier at day-break, they imme- diately repaired to a hut built of flate in the neighbourhood, called Caftle Pictet, near which, as they were informed, the aceident had taken place. They obferved fome figns of a fiffure covered by the fnow, but there was no aperture. They however continued their fearch, and about two 1n the after- noon Deville found in the fnow a hole almoft fquare, about two feet in extent each way, but of which they could not diftinguifh the bottom. In the neighbourhood there ap- peared fome figns of the exiftence of a fiffure beneath the fnow. “* By means of a ftone-tied to the end of arope in the form of a founding-line, they were able to difcover in this hole, at the depth of more than a hundred feet, the prefence of a body of a nature different from fnow or ice. They then let down the harpoon, which feemed to have laid hold of fome- thing, but which brought up only a fingle hair. Bernard the fon then propofed to defcend attached to a rope, which he’ accordingly did; and when he arrived at a depth where there were only eight inches diftance between the fides of the fif- fure, he was able to touch, with a ftaff five feet in length, the head of the dead body below him. He then caufed him- felf to be hoifted up, becaufe he found his pofition exceed- ingly confined, without having power to move any of his limbs. “The harpoon was again employed, but it brought up nothing except fragments of the clothes and a hat. Night came \ a Traveller on the Glacier of Buet. Tra came on, the weather was cold, and the travellers were wet. They were obliged, therefore, to return to the Chalets de Villy, where they arrived about ten at night. «< Having confulted together, they refolved to return to the glacier, after fupplying themfelves with fome pieces of wood and fome more ropes. They fet out from Villy at break of day, and on reaching the mouth of the fiffure they con- ftruéted a kind of apparatus, by means of which Deville the father was let down; but he was ftopped by the narrownefs of the fiffure, the fame obftacle which had ftopped his fon. He had carried down with him a fhort-handled hatchet, -by means of which he endeavoured to enlarge the paflage to- wards the’ place where the body lay, in order that it might not be covered by the fragments of ‘the ice. He defcended yradually towards it, and endeavoured, but in vain, to move it, as it was fo ftrongly wedged in between the fides of the pit. He then endeavoured to cut the ice around it, and at laft difengaged the upper part of the body in fuch a manner as to be able to faften a rope round it below the arms. The body was in an ereét pofition, the arms raifed up to the head, and the face turned towards the left fhoulder. It was quite frozen. « Deville then called out to the affiftants to pull the rope, in order to try whether it was poffible to raife the body, but the attempt was fruitlefs. He then continued to clear away the ice around, which he at length accomplifhed, after three hours labour with his hatchet. When this was completed, he firft caufed himfelf to be drawn up, and then the body ; by this time it was five in the evening. “¢ Search was then made in the pockets of the deceafed, in order to find out and colleét all his property, and an in- ventory of them was {fubjoined to the’ prefent minutes. A fledge was made with fome pieces of wood, and in this © manner the body was conveyed beyond the glacier. The brothers Deville then carried it on their fhoulders, in turns, ‘ as far as the Chalets de Villy, where they arrived at ten in the evening. It was then placed on a mule, and, after reft- ing an hour, they again fet out, and arrived at Servoz be- tween five and fix in the morning. Bernard, Deville’s 4 , youngelt / Ii2 Fatal Accident which happened to youngeft fon, being worn out with fatigue, was obliged to’ remain behind at the Chalets de Villy.” Deville himfelf was entirely exhaufted ; and, indeed, thofe who reflect on the labour he had to endure for feveral hours m the confined place in which he was fufpended, and the Jength of the way ‘he had walked, will be aftonifhed that he could hold out fo long. He refufed to take any repofe until he had affifted, along with us and a very numerous com- pany, at the funeral obfequies of the unfortunate traveller. - He was fpecially charged by the prefeét to caufe a temporary pyramid to be raifed in order to mark the fpot. The compreffion which the unfortunate young man had experienced by an accelerated fall of more than a hundred feet, in a fiflure the fides of which,approached each other in the form of a wedge, had been fo violent that his watch was beaten flat. We found in his pockets 78 livres in money, and the third volume of Sauffure’s Journey through the Alps. Such of his effects as were of any value were given to Deville, according to the agreement made by M. Zimpffen, and the prefect engaged to tranfmit the reft to his relations. We thought proper to add to them a lock of the hair of this in- terefting youth. 4 In his pocket-book was found a letter which he had begun, written in German, and direéted to his father. We cannot refift the temptation of publifhing fome fragments of it; they difplay a juft fpirit of obfervation, and great fenfibility of mind: I hope his unfortunate parents will forgive us! It is the part which we take in their grief that renders us perhaps indifcrete in publifhing the letter of the fon; but we wifh to make our readers participate in their regret, and to announce, wherever this work may circulate, what kind of fon thefe parents have loft, what hopes have been fnatched from them for ever *. We * The following is a literal tranflation of this letter, dated Vevey, Auguft 2, 1800:— You fee, my dear father, by the date of my letter, that I have undertaken a journey: you fee alfo that this journey is one of the moft interefting that can be wifhed. “ ¥ fet out on Tuefday from Rumlingen and on Wednefday.from Berne, and I fhall not return to my prefent habitation before a fortnight : or | | | | : . . ‘ ' a @ Traveller on the Glacier of Buet. 114 We left Servoz a few minutes after the difmal ceremony, and arrived about midnight at Geneva, having our minds and hearts filled with the events of our journey. One of the dangers to which travellers are crn in thefe mountains mutt be already known to my readers; but this is not the only one, and a fimple enumeration of the acci-_ dents which have taken place in the courfe of a few years back, will exhibit others which may fometimes occur. One of our countrymen, young and active, having ven- tured without a guide, and without proper fhoes, to traverfe the fleep and rocky declivities which form the bafe of the needle of Charmoz towards the glacier called Des Bois, was precipitated into one of thefe ravines, and perifhed. A young inhabitant of Zurich having afcended to the or three weeks, when I fhail embrace my dear and beloved pupils, my Rudy and my Sophia. It is neediefs to tell you that I travel on fcor, and you may alfo guefs that I travel in company with a friend; for the heart and mind never enjoy the moft beautiful a‘peéts of nature but when confcious that a living being fympatbifes with us. Every thing beautiful and fublime, in order that it may make a deep impreffion on the {oul of man, ovght to be united with the enjoyment of love and friendfhip.. “« Scarcely have you reached the canton of Fribourg when you lofe fight of that opulence, civilifation, culrure, and thofe natural beaanice! which diftiaguifh the canton of Berne; and che contraft is painful. 1 have found here aconfirmation of the opinion I long before entertained of the old government of Berne. However deficient it might be in many refpects, it was inconteftably fupcrior to all the other governments of Swifferland. ** Ja the hermitage (near Fribourg) there is mow living an old heimit with a long white beard called Le Frere des Bois, a name given here to hermits. “ Though pretty far advanced in years, he is ftill very frefh. He ferved a long time as an officer in a Swifs regiment in the pay of Au- firia. We were very much furprifed, when we alcended towards him, to fee him coming flowly to meet us acrofs the large hall, not in the drefs of a hermit, but in a huifar uniform; his fhort open red cloak, bordered with fur, and his white breeches, formed a concraft with his long fhowy beard. He received us with great kindnefs, fpoke to us in French and German, complained a great deal of the depravity of the prefent age, and told us that it was not fufficient to pray, it was. neceffary to aG@, &c. He congratulated himfelf o1 the tranquillity 6f his life, his habitation being at a Ciflance from all buftle, and his ears being affailed by no noites except that occafioned by the fall of a neighbouring torrent, and the finging of birds.” e=*Vovr, VIIt, O fummit we tr4 Fatal Accident which happened th fummit of an infulated rock which terminates the mountairt of Baime to the north, -and at a little diftance from the neck or paffage of that name which conduéts from Chamouni to the Valais, becoming giddy, made a falfe fiep, and was dafhed - to pieces at the Baifom of the precipice. A Genevefe family, who had gone to vifit the ice cave of Arveron, and who happened to be there at a time when the arch fell down in fucceffive fragments, in confequence, it is faid, of a piftol being fired, having been fo imprudent as not to retire in proper time, while. the accumulated ice obftructed the torrent, one of the fons was crufhed to death by the! falling blocks of ice, and hurried away by the waves ; another was feverely wounded; and the father, after Baik his legs were broken, efcaped from deftruction only in 2 manner almoft miraculous. _Thefe, however, are the only unlucky events which have taken place fora long time in a country vifited by many of the curious, who are fometimes imprudent. It may readily be believed. that none of thefe accidents would have hap- pened, had thofe who fell vidiims to them liftened to the voice of common prudence, which would dictate neany a as follows: | ‘ That there is very little merit or glory in expofing one’s life, throngh oftentation, in order to difplay a courage in which the moft common rope-dancer will always be fuperior to the traveller who attempts to give proofs of his good’ head pr agility in attempts more or lefs dangerous. That no one ought to think of traverfing thefe mountains except when conduc¢ied by a robuft, prudent, and experienced guide. Nothing can be more treacherous and, deceitful than thofe things which appear eafy when feen at a diftance; thofe apparent paffages, in which travellers are gradually in- volved, without reficcting that, if they are at laft flopped by fear, or by the impoffibility of proceeding further, this fear will double the difficulty of retreating, becaufe it deftroys that coolnefs which 1s neceflary for extricating one from difagree- able fituations. [have more than once experienced that it is poffible to recover this coolné{s by refolving to look only forwards, and endeavouring, by au effort of the nnagination, te 7 a Traveller on the Glacier of Buet. 115 to fuppofe that you are walking merely on the highway, or flepping from one ftone to another, or along the top ofa ftone fence in order to avoid wetting your feet. In a word, it is neceffary to place the moft implicit con- fidence in the cautions of your guide. Men of that clafs, when they accompany a traveller, lie under the weight of great refponfibility. If an accident fhould take place through their fault, it would ruin their reputation; and on this re- putation their maintenance depends. The guides, therefore, are interefted by one of thofe motives which are deareft to man, to give good advice; and the traveller ought to obey it. From thefe precautions, which may be called moral, I fhall now proceed to the phyfical. The mofi effential of all is proper fhoes. Three kinds of difficult declivities are found on the Alps—rocks, declivities of ice, and thofe covered with grafs, which are more flippery than ice when the fole of the fhoe is fmooth, as it generally becomes by walking over them. The ufe of cramp-irons either on the heel, as Sauffure recommends, or placed acrofs the fole, as they are ufed by fome of the mountaineers, will render travelling over thefe declivities fecure to a certain degree: but they muft often be put on and taken off, becaufe they render walking more or lefs cumberfome; which is a ‘great inconvenience, I have found fo much utility in an invention which I fubftitute for them, that I do not hefitate to recommend it to thofe fond of vifiung thefe romantic ‘{cenes, The traveller mutt provide firong fhoes, the foles of which are at leaft fix lines in thicknefs, and having the upper lea- ther and quarter double to a certain height around the fole. The upper leather muft be exceedingly pliable, in.order that it may nowhere hurt the foot, and the fhoes fhould be tried feveral times in fhort excurfions before a long journey is un- dertaken with them. Nails of tempered ftecl’ mutt be pro- vided, the tails of which form a fcrew; their heads, not lefs than four lines and a half in diameter, mutt be cut into the form of a fquare pyramid, which will have two points in confequence of the notch cut into each for receiving the feyew-driver to fix them in the fhoes. Twelve of thefe nails Q4 miu 116 Fatal Accident which happened to muft be put into each fole, viz. feven around the fore-part, difpofed at equal diftances, and five around the heel, as near the edge of the fole as poffible without endangering the burfine of the leather. The interval between thefe nails ought to be filled up with common Jarge-headed nails, fo clofe that their heads may touch each other. Shoes of this kind will enfure fafety to the traveller in all places of difficulty; the nails will hold on granite as well as on the grafs, will occafion no inconvenience in the platus, and will aft for along time. When the fleel heads become worn down, others may be fubflitutcd in their place. The firft fhoes of this kind, which I caufed te be made a dozen years ago, and which I have frequently employed ‘during that period, are ftill fit for fervice. A flaff, five or fix feet in length, fhod with iron, is alfo ufeful to thofe who traverfe the glaciers, either for founding the deceitful fnow which covers the fifures, or for walking with more fafety over the flippery ice. Staves of this kind, ready prepared by the guides, may be found at Chamouni. When the traveller has to afcend for a confiderable time, it is a bad plan to be defirous of hurrying. By thefe means the traveller becomes heated, and lofes breath, and his pro- grefs is moré retarded than he expected. The guide muft be ordered to walk foremoft; and it will be neceflary to be direéted by his fteps, which are meafured, as it were, in ca- dence, and to ftop from time to time, but without fitting down, and without halting too long to catch cold. He may afcend in this manner, without fiopping, 200 fathoms per- pendicular height, and that is enough. He muft pull off his coat when he begins to perfpire, and carry it folded up on his fhoulder: in this manner the heat produced by the labour of walking may be moderated, and he will find, when he halts, the benefit of an additional covering, without any of its inconveniences. In regard to drefs, it is of effential ad- vantage, when a traveHer fets out for the glaciers, whatever may be the heat im the plain country below, to take proper precautions to guard againft the cold, which it is not always pomible to forefee. To the Jadies in particular I recommend this attention. Thefe a Traveller on the Glacier of Buet. 117 -‘Thete precepts are addreffed, more or lefs direétly, to all travellers who may be defirous of traverfing the mountains “but I fhall add a few words to thofe who are philofophers or naturalifts, and to the amateurs of lithology in particular. - x, . . . The latter have trequevtly experienced the inconvenience of q y €xp \ having nothing but their pockets to contain the fpecimens of rock = es they detach with a hammer: thefe are foon filled, and harafs the traveller by their fwinging movement. I fupply this deficiency, with adyantage, in the following manner: To a pretty broad leather belt I have adapted a loop of the fame material, placed in an inclined pofition, to receive my hammer, nearly in the fame manner as the Turks carry , their pomards, On the other fide is a {mall pocket, which “contains a bottle of acid in a wooden cafe, a piece of fleel for ftriking fire, &c. This belt or girdle forms the upper part of an apron of very thin leather, which, when let dowa, would cover the knee, but which, when tucked up on each fide, forms a large horizontal pocket before, open at the top, and fupported in the middle by a thong fhaped hke an in- verted Y; the two branches of which are fewed to the girdle, and pafs round the apron below. The tail of the Y is turned up before, and is buckled to the bandolier with which £ carry my barometer. The ftones which [ pnt into this pocket being difpofed, as it were, around the centre of ¢ra- vity of the body, and being fupported in. part by the fhoul- ders, on account of the thong which envelops the apron, occafion no inconvenience. I thus. have them all under my eye, and at hand when [ wifh to fubftitute one fpecimen for another; and they experience no agitation, and do not rub againft each other as they do in the pockets. To the fame girdle, on one fide, are fufpended, by fteel hooks, one of Ramfden’s fextants of three inches radius, which gives even the minutes of a degree; an inftrument exceedingly convenient for meafuring angles. On the other fide is fulpended an artificial horizov, with a fpirit level for taking heights. The box of this inftrument I difpofe in fuch a manner that it ferves me for a fland when necefliry, being fupporigd by a ftaff that opens at bottom with three feces 118 Method for defiroying Rats and Nice. feet ; it ferves alfo as a fupport for my barometer, and makes an excellent walking-ftick when the three branches are folded together. | Thoush the whole of thefe inftraments, ‘ added to the ufual quantity of ftones collected during an excurfion of this kind, amount in weight to more than twenty pounds, I am not much incommoded by the burden, on account of its being equally diftributed; and in my lat. Alpine journey, which I undertook with the unfortunate Dolomicu, be envied ‘my lot, though, inftead of being accoutred as I was, he carried only his hammer and his fpecimens. = = at is = = = = = IV. A cheap and efficacious Method for deflraying Rats and Mice ; a eae to the Agriculture Society of Man- chefler*® by Mr. C. Tayton, Secretary to the Society for he Encouragement of Arts, Manufaciures, and Commerce, I N or near the places frequented by thefe vermin, place upon a flate or tile one or tivo meat {poonfuls of dry oat- ineal ; Jay it thin, and prefs it flat, that you niay more eafily know what is taken away, The rats, if not iuterrupted, will come regularly to feed there; fupply them thns with freth eatmeal for two or three days; then to about fix {poonfuls of dry oatmeal add three drops of oil of anifeeds; and having fiirred the mixture well together, feed them with this for tivo or three days more; then for one day aive them only half the quantity they have ufually eaten of this feented oat- meal, and on the following day place the following mixture: To four ounces of dry oatmeal, feented with fix drops of oil of anifeeds, add half an ounce of carbonat of barytes, previonfly pounded very fine in a mortar, and fifted through a litle fine muflin or cambric: mix this intimately with the feented oatmeal, and lay this mixture of oatmeal and barytes upon the tile or flate, as the oatmeal had been ufually placed, wind allow the rats to come and eat of it for twenty- four hours without interruption. * For this communication Mr. Taylor received the thanks of the Society. As that Socitty has not yet publifhed any of its tranfaétions, pge infecting this article cannot fai] to prove highly uferul. A few D6ltrines refpecting Heat or Caloric. 119 A fety hours after eating thereof, you will frequently fee fome of them running about as if drunk, or paralytic, but ! c . - eventually they generally all retire to their haunts and dic. - As rats are extremely fagacious, it/may be proper, where they have only eatena {mall portion, to allow the mixture to remain for forty-eight hours. It will be beft to burn what is left after that time, as a frefh mixture may be prepared at a trifling expenfe, when wanted. During the time in which the mixture of barytes is ex- pofed to the rats, it is neceflary to keep fhat the doors of tlie places where it is laid, to prevent the vermin from being difturbed, or a poffibility of accident to any other animal or perfon $ for though it is not fo extremely dangerous, if taken internally, as the preparations commonly employed for kill- ing rats, and is even in fome cafes ufed in medicine, yet it is (ae if taken improperly. The oil of anifeeds renders the mixture difagreeable to dogs and many other animals, but is, in fmall quantities, alluring to rats, The carbonat of barytes may be procured in large quan- titics at the lead mines belonging to Sir Frank Standifh, Bart. at Anglezark, near Chorley: the proper fort is tafte- lefs, femi-tranfpatent, and effervefces with acids: it is mo- derately hard and ftriated. It is frequently called aérated barytes (terra ponderofa aérata), and fometimes, by the miners, ponderous f{par. = Se TS: x WY. A brief Examinition of the recerved Doétrines refpecting Heat or Caloric.’ By ALEXANDER TitLocH. Read before the Afkefian Soctety, December 1799. {Continued from Page 78.] A Quantity of heat added to that already in water of a known temperature, which fhall /ea/dly increafe the volume of the compound, heat and water, only one thoufandth part, is fenfible heat; caloric not in combination, not in chemical, union—it is cognifable by our’ fenfes! But if enough be added j/enfibly ta increase the volume to one thoufand times ifs / 1 120 Examination of the received Do€trinés ats original bulk, then the added heat is latent; it is in che- mical union; it is combined caloric! Becaufe now not cog- nifable by our fenfes? No. We fee the volume of the fteam much larger then that of the water; and the more heat we add, the greater is the increafe of volume while water is left to reccive it. Yet I.am not to believe that the heat is cognifable by any organ of fenfe or external fign! In other words, I am commanded to believe as true, a ftate- ment which the evidence of my own fenfes makes it impof- fible I can give credit to. " But, fay the advocates for this doftrine, a fubftance fo charged with caloric as to become vapour, will not indicate, by the thermometer, any further increafe of temperature, though we continue to pour beat into the liquid that pro- duces the vapour; therefore the extra heat muft have become latent im the fteam that has been generated. Nay, we can proye the fact; for this fame latent heat may again be made Jenfible in the common procefs of condeniation. This mode of reafoning appears to me to be more fpecious than juft. It is demanding that the common thermometer fhould do in this cafe what it never'does in any. This in- firument never tells the quantity of heat paffing into‘ any body, even in thofe cafes where heat 1s counted fenfble or free; it only tells the comparative quantity pafling into itfelf from the body i in which it ts immerfed, or with which it is in contact, to bring it into equilibrium with that body as to heat. Boiling water, fleam, the materials of which the thermo- meter is made, become each charged with heat zu proportion éo their capacities, and this whether the thermometer be in the water-or in the fteam. The thermometer kept in the fieam well never rife higher than 212°, ‘ becaufe there the heat is /atent!’ Keep it in boiling water for a year, and it will not rife higher than 212°; yet there the heat is fenfrble ! Ts this AdtnGion reconcilable with common fenfe? But the refult may even be altered at pleafure. It will not rife higher than 212° in boiling water uader the common atmo/phere :—~ in other words, 1f we with to raife the heat higher, we mutt put a greater preflura upon the waier. Cenfine the water fo’ $8 that =—_ re/peGing Heat or Caloric. I2t that none of it may efcape, and the heat will rife in it far above 212°. Confine the fteam, and in it the heat will rife jut as high as in the confined water; yet in the one the heat exifts in a different {tate from what it does in the other!!— The refult, we fee, may be altered by mechanical contriv- ances: nay, ftri€tly fpeaking, What is the effect produced by the atmofphere but mere mechanical preffure? Yet we are to believe that a change has been effected in the phyfical properties of one of the fubftances fubjected to its mechanical operation !—If Nature had fo conttituted the atmofphere as to have only half its prefent gravity, the point at which heat would become latent, asit is called, in fteam would have been far below 212°. When water is made to boil in an exhaufted receiver at a lower temperature, have we done any thing but removed weight from its furface, and vice verfa >—Does the heat in the fteam in theie ca!es pafs into a latent ftate alfo ? If it does, the effect is mechanical: if it does not, then the mere accident of the atmofphere being of its prefent weight, has nothing to do with the boiling point happening to fall at 212°! But he that would fay fo would be counted mad, At Munich, and other places equally elevated above the level of the fea, that is, having a lefs weight of atmofphere upon them, water, in open veffels, boils at 209°. In a par- tially exhaufted receiver the fame effect takes place: and yet the do&trine of latent heat is never confidered as inconfiftent with the fact; really for no other reafon but becaufe.a com- mon thermometer cannot meafure /pecific heat. To demand that a thermometer {hould meafure the quan- tity of heat poured into water to convert it into vapour, and» to maintain it in that form; and to infift, becaufe the inftru- ment will not do this, that the heat muft have changed its nature, and loft its original character; is about as wife as it would be to demand, that a pint meafure dipt into the ocean fhould determine the quantity of water in the latter, and to infift that, otherwife, the water on the outfide of the veffel muft have loft its original charaéter, and be different from that within: it is demanding that mercury, which, by its conftitution, can at 212° only expand a certain quantity, compared with its own bulk infome given lower tempera- “Vou. VIII. R : ture, “122 Examination of the received Do€trines ture, fhould be able (without our making any comparative experiments to determine the point) to inform us how many times water will be increafed its own bulk when we pour a greater quantity of heat-into it! The heat in the fteam is as much fenfible or free heat.as it was before it paffed into the fleam, if thefe terms are to be applied to heat cognifable by our fenfes, and that may be meafured comparatively. But the ficam is really its own thermometer; and it indicates as truly the quantity of heat that has paffed into a given quantity of water, as the ther- mometer does the quantity that paffes into itfelf; aye, and by the fame means too—the magnitude of its own volume. Inftead of fuppofing, in the cafe of fteam, that heat has become latent, or been changed, would it not be more _correét to afcribe the pheenomenon that led‘ to this idea to another caufe, a change in the form of the water, which, by its conftitution, is forced to become vapour, under the common prefjure of the atmofphere, whenever a certain number of times its own bulk of heat is poured into it. The quantity, after proper comparative experiments, could then be expreffed in fenfible terms, and would turn out to be the whole bulk of the fleam, minus the original volume of the water in the com- pound. If fome fuch method were followed, it appears to me ex- tremely probable that we fhould foon arrive at many truths refpecting the operations of the univerfally diffufed fubftance heat, which otherwife muft efcape us, though the fads that might lead to them are daily prefenting themfelves in almoft every chemical procefg. It would furely tend much to the . Redvancement of Tcience, if the bulk, mafs, or volume of heat neceflary to convert different folids into liquids, and liquids into gafes, under a given preffure, were accurately deter- mined by experiment. The thermometer would then be a more ufeful infrument than it now is—But we fhould never Jook to it to perform impoffibilities ; we fhould no more ex- pect it to meafure the quantity of heat paffing into or out of bodies, than we fhould attempt to meafure the quantjty of ~ water delivered from a pump, by placing an hygrometer or any twifted fibrous fubftance in the ftream, and then exa- 9 mining refpelting Heat or Caloric. 122 mining how much its length is diminifhed or its diametet Increafed, i Some may fay, that the cafe of the converfion of water into fieam is not held by them as one of thofe that prove, the paffing of heat from a fenfible to a latent ftate, and that therefore our reafoning, drawn from that example, will not invalidate the doétrine; “ for in the cafe of water they con- fider the heat as in fimple mixture, and it would be an abufe of words to call fo weak an union by the name of combina- tion,” - I reply, that this cafe was one of the earlieft brought in fupport of the doGtrine, and alfo thought to be one of the firongeft; and if the good underftanding of any has led them to give it up, it is the more furprifing they fhould be fo blind as to continue upholding a fabric which was built on this as one of its foundation {tones; and which does not appear to. me to be upheld by any one fact that may not be as fatif- factorily explained, without admitting the exiftence of heat in two diftingt ftates. But, fay thefe, two different fluids of the fame temperature when united will often give out heat—What can wéeMay of this heat, but that it was /atent or combined in one or both of the fluids, and that it is thrown out as fenfible or free heat-by their union? T would fay no fuch thing without a previous éxamination of all the accompanying phenomena; and one of thefe I find to be a reduétion in ihe volume of the compound, which is lefs than that of the fum of the two. The molecule of the two fubftances occupy lefs room united than in their refpeétive fluids. For inftance, when fulphuric acid and water are joined, the volume of the mixture is lefs than that of the two before mixture; there is, therefore, lefs lodg- ing-room left for the heat: in other words, the capacity of the compound for heat is lefs than the fum of the capacities of the ingredients: therefore, compared with furrounding bodies, it has now too large a quantity, and, by the law of equilibrium, muft give eff the furplus to the furrounding bodies in proportion to their capacities, referving of fuch furplus only that portion due to itfelf, and neceffary to give it fuch an increafed temperature as the furrounding bodies Raz will 124 Examination of the received Doftrines will each have acquired, by the diffufion of the diflodged heat, when it has come again to a ftate of equilibrium ; a quantity ‘which muft in general be fo fmall as to elude all» meafure- ment in the petty proceffes of the laboratory. Are there any cafes in which heat is diflodged by the union _ of two liquids, and where, at the fame time, the volunie of the mixture is not reduced below that of the fum of the vo- lumes of the ingredients? I do not recolle& any. There may, however, be fome, and it will be time enough to at- tempt to explain them when they are adduced. In the mean time, when a diminution of volume follows, or rather ac- companies, the extrication of heat from any bedy, inftead of running to the doétrine of latent heat being then made fenfible (that is, heat being changed in its character), we ought to content ourfelves with flating an obvious fact, namely, that the molecule of the two liquids are fo con- ftructed and formed as to admit of their coming clofer toge~ ther when mixed than they could when refpectively alone ; and, of courfe, now fill reciprocally fpaces that, before their mixture, were filled with heat: the latter fubflance, in con- fequence of being thus diflodged (for two fubftances cannot, at one and the fame time, occupy the fame fpace), diffufes itfelf among the furrounding bodies in proportion to’ their capacities, conftituting in them, what it did in thofe it has quitted, du/k or AB ate What takes place in fuch cafes may be illuftrated by one of a different kind. Ifa pint of {mall fhot and a pint of dry fand be mixed, they will occupy a lefs volume than two pints; air is thrown out that was before lodged in the in- terftices of both of them. Was it /atent air then, and is it fenjible air now? Did it differ in its properties before and after being ejected? Weighing the ingredients before and after mixture, will not tell how much air has been ejected : but we know, notwith{tanding, that its volume may be mea- fured; and fo may that of the heat driven out in the cafe which this was brought to illuftrate. ~ How are fluids in general meafured but by their bulk ? or their weight, when circumftances will allow it? Water, for infance, in common cafes, is directly meafured by any velfel re/peting Heat or Caloric. 125 veffel whofe capacity is known or can be come at 3 in others, as in a wet piece of wood, a brick, or other fybftance, the quantity muft be found out by other means: but in every cafe where water is added to another fubftance, which is made thereby to expand exaétly in the direét ratio of the quantity of water added (if there be any fuch), the quantity may be determined by meafuring the compound, and de- duting therefrom the original volume of the other fubftance. Would it be afurd to talk of meafuring the matter, fluid, or Subfiance, called beat, in a fimilar manner ? : When a thermometer is applied to any fubftance of a higher temperature than itfelf, it is, by the operation of the general law, foon brought into equilibrium with that fub- ftance as to heat; and we fay, ‘‘ it has rifen fo many de+ grees.”’ We are habituated to this mode of {peaking, and fatisfy ourfelves, without any more inquiry, that the phzno- menon requires no further inveftigation; and as to the ac- companying phenomena, we generally overlook them alto- gether. When we find that the mercury has increafed in volume, would it be abfurd to afk this fimple queftion? Is the increafe to be attributed not merely to the addition of heat, but to the addition of a quantity equal in bulk to the increafe of volume acquired by the mercury? {1 think it ex- tremely probable that the amount of increafe or diminution of the volume of any fubftance, when heat is added or ab- firacted, is the real bulk of the heat fo added or ab{traéted. That I may be clearly underftood, I fhall illuftrate my mean- ing by a comparifon : If to a cubic inch of a compact piece of gum and water new unknown quantities of water be added, who would ever think of wire-drawing the mixture through a tube, and ex- preffing the refult in degrees of no known quantity, nor re- ferable to any determinate meafure ? The cafes to me appear perfectly parallel. To a mixture of gum and water we add.water, and the volume of the mixture is increafed; and to a mixture of mercury and heat we add heat, and the volume of that mixture is increafed. When “ 126 - Experiments on the Solar and on the When the volume of'a fubftance is increafed by thal: cafe any thing be conceived more eafily practicable, in many cafes, than to determine, by actual meafurement, the pro- portion that the increafe bears to the volume of the mafs at a given lower temperature? Is not this already done in many cafes? The experiments on this point fhould be multiplied, fo as to embrace, if poflible, every known fubftance and every dearce of heat. Moft fubftances would them become their own thermometers: nay, all are fo at prefent, but we have not examined the relations of all their different fcales. [To be continued. ] VL. Experiments on the Solar and on the Terreflrial Rays that accajion Heat; with a comparative View of the Laws to which Light and Heat, or rather the Rays which occafioa them, are fubjeét, in order to determine whether they are the fame, or different. By WittiamM Herscuer, LL.D. F.R.S, [Continued from Page 21.] 5th Experiment. Reflection of the Heat of a Coal Fire a ea plain Mirror. I PLACED a fmall fpeculum, fuch as I ufe with my 7-feet’ reflectors, upon a ftand, and fo as to make an angle of 45 degrees with the front of it*. This was afterwards to face the fire in my parlour chimney, and would make the fame angle with the bars of the grate. At a diftance of 3} inches from the fpeculum, on the reflecting fide of it, was placed the thermometer No, 15 and clofe by it, but out of the reach of the reflected rays, the thermometer No. 4. The whole was guarded in front, againft the influence of the fire, by an oaken board 1° inch thick, which had a circular open- ing of 11 inch diameter, oppofite the fituation of the plain mirror, in order to permit the fire to fhme upon it. The | thermometers were divided from the mirror by a wooden partition, which alfo had an opening in it, that the refle@ed * See Plate JI. fig. 2, rays Terreftrial Rays that occafion Heat, 129 rays might come from the mirror to No. 1, while No. 4 remained fcreened from their influence. On expofing this. pparatus to the fire, I had the following refult : No.1. No. 4.) Here, in five minutes, the heat re- o 60 60 flected from the plain mirror raifed I 62 60 | the thermometer No. 1, 7 de- 2 64. 60 > grees; while the change in the 8 66 60 | temperature of the fcreened place, 4 66 60 indicated by No. 4, amounted 2 67 60'j onlytohalfa degree: which fhows that an open fire fends out rays that are fubjeé& to the laws of reflection, and occafion heat, 6th Experiment. “Reflettion of Fire-Heat by a Prifi. Every thing remaining arranged as in the 5th experiment, T removed the fmall plain mirror, and placed in its ftead a prifin which had one of its angles of go degrees, and the ether two of 45 degrees each*. It was put fo as to have one of the fides facing the fire, while the other was turned towards the thermometer: the hypotenufe, confequently, made an angle of 45 degrees with the bars of the grate. The apparatus, after having been cooled fome time, was expofed . to the fire, and the following refult was taken: No. 1.° No. 4.7 Here, in eleven minutes, the o! iJ 62: tays reflected: by the prifm I 63 622 raifed the thermometer 4! 2 64 i. 63 |! degrees; but, the temperature ENS? se 63? of the place having undergone 5 65 - 63% an alteration of 1 degrees, we 8 65% 63% can only place 23 to the ac- 10 66+ 63 | count of reflection. The ap- 11 67 64z his paratus becoming now very hot, it would not have been fair to have continued the ex- periment for a longer time; but the effeét already produced ~ was fully fufficient to fhow, that even a prifm, which ftops a great many heat-making rays, {till refleéts enough of them to prove, that an open fire not only fends them out, but that. they are fubject to every law of refleétion, * Sce Plate I. fig. 2. F. 128 Experiments on the Solar and on the "th Experiment. Reflection of inviible Solar Heat, » Ona board of about 4 feet 6 inches long, I placed at one end a {mall plain mirror, and at the other two thermome- ters*. The diftance of No. 1, from the face of the mirror, was 3 feet gi inches; and No. 2 was put at the fide of it, facing the fame way, but out of the reach of the rays that were to be reflected by the mirror. The colours of the prifm were thrown on a fheet of paper, having parallel lines drawn upon it, at half an inch from each 5 The mirror was ftationed upon the paper; and was adjutted in fuch a man- ner as to prefent its polifhed furface, in an angle of 45 de- grees, to the incident coloured rays, by which means they would be reflected towards the ball of the thermometer No. 1. In this arrangement, the whole appaiatus might be with- drawn from the colours to any required diftance, by attend- ing to the laft vifible red colour, as it fhowed itfelf on the lines of the paper. When the thermometers were properly fettled to the temperature of their fituation, during which time the mirror had been covered, the apparatus was drawn gently away from the colours, fo far as to caufe the mirror, which was now open, to receive only the invifible rays of heat which lie beyond the confines of red. The refult was as follows : No. 1. No. 2.) Here, in ten minutes, the ther- of 56 56 mometer No. 1 received four ae 57 56 degrees of heat, reflected to it, re 59 56 in the ftricteft optical manner, vi 60 56 by the plain mirror of a New- 10 60 56 tonian telefeope. The great regularity with which thefe invifible rays obeyed the law of reflection was fuch, that Dr. Wilfon’s fenfible thermometer, No. 2, which had been chofen on purpofe for a fandard, and was within an inch of the other thermometer, remained all the time without the leaft indication of any change of temperature that might have arifen from ftraggling rays, had there been any fuch. I now took away the mirror, but left every thing elfe in the fituation it was. The eflect of this was thus: ® See Plate IV. fig. 1. : No. 1. Terrefirial Rays that occafion Heat. 12g No.1. No.2. Here, in ten minutes, the ther- o! 60 56 mometer No. 1 loft again the 5 58 56 four degrees it had acquired, 8 57 56 while No. 2 ftill remained un- 1 fe) 50 56 altered; and this becomes there- fore a moft decifive experiment, in proof of the exiftence of invifible rays, of their being fubje@ to the laws of reflection, and of their power of occafioning heat. 8th Experiment. Refleétion and Condenfation of the invifible Solar Rays. I made an apparatus for placing the fall fteel mirror at amy required angle *; and, having expofed it to the prifmatic fpeétrum, fo as to receive it perpendicularly, I caufed tHe colours to fall on one half of the mirror, which, being covered by a femicircular piece of pafteboard, would ftop all vifible rays, fo that none of them could reach the polifhed furface: On the pafteboard were drawn feveral lines, parallel to the diameter, and at the diftance of one-tenth of an inch from each other; that, by withdrawing the apparatus, [ might have it at option to remove the laft vifible red to any required diftance from the refleGing furface. In the focus of the mirror was placed the thermometer No, 2. I covered now alfo the other half of. the mirror, till the thermometer had aflumed the temperature of its fituation. Then, withdrawing the apparatus out of the vifible fpetrum, till the laft tinge of red was one-tenth of an inch removed from the edge of the pafteboard, and the whole of the coloured image thus thrown on the femicircular cover, I opened the other half of the mirror for the admiffion of invifible rays. The refult was ag follows : No.2. Here, in one minute, the ther- In the Focus of invifible Heat. mometer rofe 19 degrees. “ad 6 I covered the mirror. I 80 2" 4% : alpatt 6 Here, in three minutes, the thermomteter fell 3 6 16 degrees. I opened the mirror again. + 4 # Sce Plate IT. fig. ¢. Vou. VJIL 8 No. 2 s ‘P30 Experiments on the Sslar and on the Ngee Here, in two minutes, the Tn the Focus of invifible Heat. thermometer rofe 24. de- cf 83 grees. I covered the mir- 88 ror once more. 7 6g—And, in one minute, the thermometer fell 19 degrees. Now, by this alternate rifing and falling of the thermometer, three points are clearly afcertained. The firft 18, that there are invifible rays of the fun. Fhe fecond, that thefe rays are not only reflexible, in the manner which has been proved in the foregoing experiment, but that, by the firiét laws of reflection, they are capable of being condenfed. And, in the third place, that by condenfation their heating power is proportionally imcreafed; for, under the cireum- flances of the experiment, we find that it extended fo far as to be able to raife the thermometer, in two minutes, no lefs than 24 degrees. oth Experiment. Reficétion of invifible Culinary Heat. I planted my Jittle fteel mirror upon a fmall board*, and, ane proper diftance oppofite to it, erected a flip of deal, + inch thick and 1 inch broad, in ahorizontal direction, fo as to be of an equal height, in the middle of its, thicknefs, with the centre of the mirror. Againft the fide, facing the mirror, were fixed the two thermometers No. 2 and No. 3, with their balls within half an inch of each other, and the fcales turned the oppofite way. A little of the wood was cut out of the flip, to make room for the balls to be freely expofed. That of No. 2 was in the axis of the mirror, and the ball of No. 3 was {creened from the refle¢ted rays by a {mall piece of pafte- board tied to the feale. The {mall ivory fcales of the ther- mometers, with the flip of wood at their back, which, however, was feather-edged towards the ftove, intercepted fome heat 5 but it wil! be fen prefently that there was enough to fpare. When my ftove was of a good heat, I brought ine apparatug to a place ready prepared fot it. Bi No. 3. Here we find that, im one mi- In the Focus. Screerwed. nute, the invifible culinary oil 53 52 heat raifed the thermometer T gl 53 No. 2, 39 degrees; while * Sco Piate LV. figs 24. No. 35 Terreftrial Rays that oecafion Heat. 131 No. 3, from change of temperature, rofe only one, notwith- Handing its expofure to the ftove was in every refpect equal to that i No. 3, except fo far as relates to the rays returned by the mirror; and therefore the radiant nature of thefe in- vifible rays, their power of heating bodies, and their being fubje& to the laws of refleGtion, are equally eftabliihed by this experiment. soth Experiment. Reflection of the invifible Rays of Heat of a Poker, cooled from being red-hot till it could no longer be feen in a dark Place. The great abundance of heat in my latt experiment would aot allow of its being carried on without injury to the ther- mometer, the fcale OF which is not extenfiye; I therefore placed a poker, when of a proper black heat, at 12 inches from the fteel mirrer *, and received the effect of its con- denfed rays upon the thermometer No. 2, placed in the focus. Then, alternately covering and uncovering the mirror, ope minute at a time, the effect was as follows: No. 2.7 Here, im fix minutes, The mirror covered 0° 61 we have a repeated Open - i 68 | refultof alternate ele- Covered - 2 6t + vations and depref- Open - 3 64 ° fons of the thermo- Covered - 4 59 | meter, all ef which Open - 5 61: } confirm the reflexi- Covered - 6 55 Jj bility, the radiant ature, and the heating power of the invifible rays Has came from the poker. From thefe experiments it is now fufficiently evident, that in every fuppofed cafe of folar and terreftrial heat, we have traced out rays that are fubject to the regular laws of reflection, and are invefted with a power of heating bodies; and this inde- pendently of light. For, though, in four cafes out of fix, we had illuminating as well as heating rays, it 1s to be naticed that our proof goes only to the power of occafioning heat, which has been (tri@tly afcertained by the thermometer. If it fliould be fai id, that the power of iJluminating objects of ghele fame rays is as firiétly proved by t the fame experiments, * See Plate T. fig. 1, S73 I mut ‘ 132 Experiments on the Solar and on the I muft remark that, from the cafes of invifible rays brought. forward in the four Jaft experiments, it is evident that the conclufion that rays mult have illuminating power becaufe they have a power of occafioning heat is erroneous; and, as this muft be admitted, we have a right to afk for fome proof of the affertion, that rays which occafion heat can ever be- come vifible. But, as we fhall have an opportunity to fay more of this hereafter, I proceed now to inveftigate the re- fraction of heat-making rays. 11th Experiment. Refraétion of Sclar Heat. — With a new ten-feet Newtonian telefcope, the mirror of which is 24 inches in diameter of polifhed furface, I received the rays of the fun; and, making theny pafs through a day- piece with four lenses, I caufed them to fall on the ball of the thermometer No. 3, placed in their focus. Thofe who are acquainted with the lines in which the principal rays and pencils move through a fet of glafles, will eafily conceive how - artfully, in our prefent inftance, heat was fent from one place to another—heat croffing heat, through many inter- fecting courfes, without jofiling together, and each parcel arriving at, laft fafely to its defiined place. As foon asthe rays were brought to the thermometer, it rofe, almoft inftant- ly, from 60 degrees to'130; and, being afraid of cracking the glafies, 1 turned away the telefcope. Here the rays, whieh occafioned no lels than 70 degrees of heat, had undergone eight regular fucceffive refractions ; fo that their being fubject to its laws cannot be doubted, 12th Experiment. Refration of the Heat of a Candle. T placed a lens of about 1,4 inch focus and 1,1 inch dia- meter, mounted upon a fmail fupport, at a difiance of 2,8 inches from a candle *; and the thermometer No. 2, be- hind the Jens, at an equal diftance of about 2,8 inches; but which ought to be very carefully adjufted to the fecondary focus of the candle. Not far from the lens, towards the candle, was a pafteboard fcreen, with an aperture of nearly the fame fize as the lens. The fupport of the lens had an * Sec Plate IV. fiz. 3. ; eceentrie Terrefirial Rays that occafion Heat. 133 eccentric pivot, on which it might be turned away from its place, and returned to the fame fituation again, at pleafure. This arrangement being made, the thermometer was for a few moments expofed to the rays of the candle, tillit had affumed the temperature of its fituation. Then the lens was turned on its pivot fo as to intercept the direct rays which pafled through the opening in the pafteboard fereen, and to refract ay to the focus, in which the thermometer was fituated. ; be No. 2. Here, in three minutes, the thermometer re- = 535 ceived 2. degrees of heat, by the refraction 55z of the lens. The lens was now turned H oat away. / x f AN Here, in three minutes, the thermometer loft : oF 2\ degrees of heat. The lens was now re- 3 oe) turned to its fituation. of 53;) And, in three minutes, the thermometer re- I 542 gained the 2. degrees of heat. A greater 2 55% effet may be obtained by a different ar- 50 rangement of the diftances. Thus, if the lens be placed at 3' inches from a wax candle, and the ther- mometer fituated, as before, in the fecondary focus, we {hall be able to draw from 5 to 8 degrees of heat, according to the burning of the candle, and the accuracy of the adjuftment of the thermometer to the focus. The experiment we have re- lated fhows evidently that rays invefted with a power of heat- ing bodies iffue from a candle, and are fubject to laws of refraction, nearly the fame with thofe refpecting light. 13th Experiment. Refraélion of the Heat that accompanies the coloured Part of the Prifmatic Spectrum. I covered a burning lens of Mr. Dollond’s, which is nearly 9 inches in diameter, and very highly polithed, with a piece of pafteboard, in which there was an opening of a fufficient fize to admit all the coloured part of the prifmatic fpectrum *. In the focus of the glals was placed the thermometer No. 35 and, when every thing was arranged properly, I covered the # See Plate LV, fig 4 i eng nny ‘ 134 Examination of St. Pierre’s Hypothefis lens for five minutes, that the thermometer might affume the temperature of its fituation. The refult was as follows : , No. 3.> Here, in one minute, the ‘The lens covered 0’ 64 \ thermometer received Open - | I 176 112 degrees of heat, which came with the coloured part of the folar fpe&trum, and were refracted to a focus; fo that, if the coloured rays them- iclves are not of aheat-making nature, they are at leaft accom- panied with rays that have a power of heating bodies, and are fubjeét to certain Jaws of refraction, which cannot differ much from thofe aflecting light. [To be continued.]} ~ VIL. An Excmination of Sv. Pierrn’s Hypothefis refpeding the Caufe of the Tides, which, in oppofition to the recemed Dheory, attributes them to fuppofed periodical Eiffufions of the Polar Iees, By SAMUEL Woops, Efq. Read before ibe Afkefian Society November 5, 1799. fa tides are two periodical motions aCtuating the ocean (called the flux and reflux, or ebb and flow), which fucceed each other alternately at an interval of about fix hours; the period of a flux and reflux being, upon an average, 12 hours -24 minutes, the double of which, 24 hours 48 minutes, cor- refponds to that of a Junar day, or the time elapfing between the moon’s paffing a meridian and coming to it again. Thefe alternate elevations and depreffions of the ocean fo exactly correfpond with the courfe of the fun and moon, as to time and quantity, that the influence of thofe luminaries has in all ages been confidered as the caufe of their production 5 but it was referved for modern times to afcertain the princi- ple of their laws, and to calculate, with precifion, the effects produced by the different fituations of the fun and maon, and the proportions of their power. This principle 1s no other than gravitation, It is evident that, 1f the earth were entirely fluid wad quiefcent, its particles, by their mutual gravity, would form the whole mafs into a perfect fphere: now, if ah sower be fuppofed ta act on all the particles of this {phere 8 with, ~ _ wefpefing the Canfe of the Tides. - 35 with equal force, and in parallel directions, the whole mafs would be moved together without experiencing any alteration inits figure. But this is not the cafe with refpect to the moon’s action on our globe: the power of gravity diminithes as the fquare of the dittance increafes, ard therefore the waters (at Z, Plate V. fig. 1.) on the fide of the earth (A,B,C,D) next the moon (M), are more attracted by the moon than the central parts of the earth (O), and the central parts more at- tracted than the waters on the oppofite fide (at n) ; and there~ fore the diftance between the earth’s centre and the waters on its furface under and oppofite to the moon will be in- creafed. For, fuppofe three bodies in the fame line (H,0,D), if they are all equally attracted by any power (as M), they will all move towards it with equal rapidity, their mutual diftances continuing the fame; but if the attraction of this power (M) is unequal, the body moft forcibly attra¢ted will move fafteft, and their reciprocal diftances will be propor- tionally increafed: thus, the power of gravitation acting un- equally on the three bodies (H,0,D), the diftance of the firft (1) from the fecond (0); and of the fecond from the third (D), will be increafed in proportion to the difference of the gravitating power at the diftance of the three bodies (H,0,D) refpectively: now, fuppofe a number of bodies (ABCD) placed round the centre (O) fo as to form a fluid ring, unequally attracted by fome power (M), the parts neareft and furtheft (Hi and D) from this power will have their diftance from the centre (O) increafed, while the fides, of this ring (B and F), being ante! eguidifiant from the power (M), the centre (O) will not recede, but rather Bioich the centre (O), and form an ellipfis (nLIzN). To apply this reafoning to the cafe under confideration, while the earth, ky its gravity, tends toward the moon, the water directly below her will fwell and rife gradually; the water on the oppofite fide will recede from ithe centre (or, more properly, the centre will advance), and rife, or appear to rife, while the water at the fides is depreffed, and falls below the former leve) : hence, as the earth revolves on its axis from the moon to the moon again in 24 hours 50 minutes, there will be two tides of ebb and twoof dood in that period. In con- ‘ fequence 136 — Examination of St. Pierre’s Hypothefis fequence of the earth’s motion on her axis, the moft elevated part of the water is carried beyond the moon in the direétion ° of the rotation, and continues to rife after it has paffed di- rectly under the moon, not attaining its greateft elevation tll it has got about halfa quadrant further. It continues alfo to defcend, after it has pafled at go° diftance from the point below the moon, toa like diftance of about half aquadrant; and there- fore in open feas, where the water flows freely, the time of hich water does not exactly coincide with the time of the moon’s coming to the meridian, but is fome time after. Befides, the tides do not always anfwer to the fame diftance of . the moon from the meridian, fince they are varioufly affected by the fun’s action, which brings them on fooner when the moon Is in her firft and third quarters, and keeps them back Jater when fhe is in her fecond and fourth: becaufe, in the former cafe, the tide raifed by the fun alone would be earlier than the tide raifed by the moon: in the latter cafe, later. We have hitherto confidered the moon as the principal agent in producing tides, but it is obvious that the inequality of the fun’s aétion muft produce a fimilar effect ; fo that, in reality, there are two tides every natural day occafioned by the fun, as well as two tides every lunar day occafioned by the moon, and fubject to the fame laws: on account, how- ever, of the fun’s immenfe diftance, his a€tion 1s confider- ably inferior to that of the moon. By comparing the {pring and neap tides at the mouth of the Avon, below Briftol, Sir Haac Newton calculates the proportion of the moon’s force to the fun’s as g to 2 nearly. Dr. Horfley, in his edition of the Principia, eftinrates it as 5,0469 to 1; and, confidering the elevation of the waters by this force as an effe& fimilar to the elevation of the equatorial above the polar parts of the earth, it will be found that the moon is capable of producing an elevation of about ten feet, the fun of about two feet; which correfponds pretty nearly to experience. In order to underftand the caufe of fpring and nmeap tides, ~ we mutt confider, that the moon,’ revolving round the earth in an elliptic orbit, approaches nearer and recedes further from if, than her mean diftance, in every revolution or lunar month. When neareft, her attraction is frongeft, and vice vera e te/petting the Caufe of the Tides. 137 verfd: when both luminaries are in the equator, and the moon in perigeo, the tides rife higheft, particularly at oppo- fition and conjun@tion: at the change, when the attractive forces of the fun and moon are combined, the tide is raifed to a greater height: at the full, when the moon raifes the tide under and oppofite to her, the fun, acting in the fame line, raifes the tides under and oppofite to him, whence their conjunét effeét is the fame as at the change, and in both cafes occafions what we call fpring tides: but at the quarters, the fun’s action diminifhes the effe&t of the moon’s action, fo that they rife a little under and oppofite the fun, and fal] as much under and oppofite the moon, thefe two luminaries acting obliquely on each other, and producing what is called neap tides *. The fpring tides, however, do not happen precifely at the full and change of the moon, nor the neap tides at the quar- ters, but about two days later. In this, as in many other cafes, the effects are not greatelt, or leaft, when the imme- diate influence of the caufe is greateft or leaft: as, for in- fiance, the greateft heat of fummer is not at the time of the folftice, but fome weeks after; and if the aétions of the fun and moon fhould be fuddenly fufpended, the tides would con- tinue for fome time in their ufual courfe. The variations of the moon’s diftance from the earth produce a fenfible dif. ference in the tides. When the moon approaches the earth, her action on every part increafes, and the differences of her action increafe in a higher proportion as the moon’s diftances decreafe. According to Sir Ifaac Newton, the tides increafe as the cubes of the difiances decreafe ; fo that the moon, at half her diftance, would produce tides eight times as great. The fun being nearer the earth in winter than in fummer, the fpring tides are higheft, and the neap tides loweft, about the time of the equinoxes, a little after the autumnal and before the yernal; and, on the contrary, the fpring tides loweft and the neap tides higheft at the folftices, when the * In Fig. 2. Plate V. HZOWN reprefents the carth; ABCD the moon’s orbit. Art the full and change, the fun and moon aé& in the fame line SP: at the quarters, the fun’s influence in the line $OH counteraéts athat of the moon ating in the direétion MZN, and produces neap tides. - Vou. VIII. T fun 138 Examination of St. Pierre's Hypothefis fun is moft diftant from the equator. When ‘the moon 4s in the equator, the tides are equally high in both parts of the lunar day ; but as the moon declines towards either pole, the tides are alternately higher and lower at places having north or fouth latitude: while the fun is in the northern figns, the greater of the two diurnal tides in our climates is that arifing from the moon above the horizon: when the fun is im ‘the fouthern figns, the greateft is that arifing from the moon below the horizon. Thus the evening tides in fummer are obferved to exceed the morning tides, and in winter the morning tides exceed the evening tides: the difference at Briftol is found to be 15 inches, at Plymouth rz. It would be ftill: greater, but that a fluid always retains an imprefied motion for fome time, and confequently the pel tides always aficét thofe that follow. If the earth were covered all over with the fea toa great depth, the tides would be regularly fubfervient to thefe laws 5 but various caufes combine to produce a great diverfity of effect, according to the peculiar fituation and cireumfiances of places, fhoals, fords, and ftraits: thus, a flow and imper- ceptible motion of a large body of water, fuppofe two miles deep, will’ be fufficient to elevate its furface ten or twelve feet mm a tide’s time; whereas, if the fame quantity of water is forced through a narrow channel forty or fifty fathoms deep, it produces a very rapid ftream, and of courfe the tide is found to fet ftrongeft in thofe places where the fea grows narroweft, the fame quantity of water being conftrained to pafs through ‘a fmaller paflage, as in the ftraits between Portland and Cape Ja Hogue in Normandy; and it would be ftill more fo be- tween Dover and Calais, if the tide coming round the ifland did not check it. The fhoalnefs of the fea and the intercurrent continents are the reafons why the tides in the open ocean rife but to very inconfiderable heights, when compared to what they do in wide-mouthed rivers opening in the direétion of the ftream of the tide; and that high water is fome hours after the moon’s appulfe to the meridian, as it is obferved upon all the weflern coaft of Europe and Africa from Ireland to the Cape of Good Hope; in all which a fouth-weft moon makes . high eo - refpetling the Caufe of the Tides. 139 high water; and the fame is faid to be the cafe on the weftern coaft of America: fo that tides happen to different places at all diftances of the moon from the meridian, and confe~ quently at all hours of the day. To allow the tides their full motion, the fpace in which they ar¢ produced ought to extend from eaft to weft go° at leatt; fuch being the diftance between the places moft raifed and deprefied by the moon’s influence. Hence it appears that fuch tides can only be produced in large oceans, and why thofe of the Pacific exceed thofe of the Atlantic ocean : hence alfo it is obvious why the tides in the torrid zone be- tween Africa and America, where the ocean is narrower, are exceeded by thofe of the temperate zones on either fide: and hence we may comprehend why the tides are fo fmall in lands at a great diftance from the fhores, fince the water cannot rife on one fhore without defcending on the other: fo that at the intermediate iflands it muft continue at a mean height between its elevations on thofe fhores. The tide produced on the weftern coaft of Europe corre- fponds to this theory. Thus, it is high water on the weftern coatts of Ireland, Spain, and Portugal, about the third hour after the moon has paffed the meridian ; from thence jit flows into the adjacent channels, as it finds the eafieft paffage. Qne current, for example, runs up by the fouth of England, and another by the north of Scotland; taking confiderable time to move all this way, and occafioning high water fooner in the places at which it firft arrives, and begins to fall at thefe places while the current is proceeding to others further di- flant in its courfe. On its return it is unable to raife a tide, becaufe the water runs fafler off than it returns, till, by the propagation of a new tide from the ocean, the current is ftopt, and begins to rife again. The tide propagated by the moon in the German ocean, when fhe is three hours paft the me- ridian, takes twelve’ hours to come from thence to London bridge; fo that, when it is high water-there, a new tide has already attained its height in the ocean, and in fome inter- mediate place it muft be low water at the fame time. When the tide runs over fhoals, and flows upon flat fhores, the water T2 is. e 140 Examination of St. Pierre’s Hypothefis is elevated to a greater height than in open and deep oceans that have fteep banks, becaufe the force of its motion is not broken upon level fhores till the water has attained a greater height. If a place communicates with two oceans, or by two different openings with the fame ocean, one of which affords an eafier and readier paffage than the other, two tides may arrive at this place in different times, which, interfering together, may produce a great variety of phenomena. At feveral places it is high water three hours before the moon comes to the meridian; but that tide which the moon drives, as it were, before her, is only the tide oppofite to that produced by her when nine hours paft the oppofite meridian. It would be tedious to enumerate ali the particular folutions eafily deducible from thefe doétrines: as, why lakes and feas, fach as the Cafpian and the Mediterranean, the Euxine and the Baltic, have little or no fenfible tides; fince, having no communication,.or being connected by very narrow inlets with the great ocean, they cannot receive or difcharge water fufficient to alter their furface fenfibly. In general, when the time of high water at any place is mentioned, it is to be underftood on the days of new and full moon: the times of high water in any place fall at nearly the fame hours after'a period of about fifteen days, or between one fpring tide and another. ; This theory, however, is not without objections and diffi- culties; which has encouraged a Frenchman of fome emi- nence, St. Pierre, to frame a new and fingular hypothefis, afcribing all the phenomena of the tides to the periodical effufions of the polar ices. I fhall firft mention the moft “material faéts and confiderations which appear to militate againft the common theory, as ftated by St. Pierre; and I fha'] then endeavour to explain the theory he has {ubftituted (which it has coft me fome pains to colleé, abftract, and arrange), as nearly as poflible in a literal tranflation of his ewn language. IT is faid that, if the moon acted by her attraction, her in- fluence muft extend to the Mediterranean, the Baltic, the Caf, 9 pian, refpecting the Caufe of the Tides. 4t pian, and the vaft Jakes of North America, in fome degree at leaft; but all thefe have no fenfible tides*. This tran- quillity renders her attraction liable to fufpicion; and we fhall, perhaps, find that the greateft part of the tides in the ocean have nothing more than an apparent hires either to her influence or her courfe. The phafes of the moon do not correfpond all over the globe with the movements of the feas. On our coafts the flux and reflux follow the moon rather than her real motion: in various places they are fubject to diferent laws, which.obliged Newton to admit (chap. 25.) ‘ that in the periodical return of the tides there muft be fome other mixed caufe, hitherto undifcovered.”’ The currents and tides'in the vicinity of the polar cirale come frem the pole, as appears from the teftimony of Fred. Martens, who afferts, that the currents amidft the ieeés fet in towards the fouth; but adds, that he can fiate nothing with certainty refpecting the flux and reflux of the tides.—/oyage towards the North Pole, 1671. Henry Ellis obferved that the tides in Hudfon’s bay came from the north, and were accelerated as the latitude increafed: It is impoflible thefe tides fhould come from the line or the Atlantic. He afcribes them to a pretended communication with the Seuth fea. At Waigat’s ftraits thefe north tides run at the rate of eight or ten leagues an hour. He compares them to the fluice of a mill.—Voyage to Hudfon’s Bay, 1746. Linfcotten, in 1594, made nearly the fame remarks, and obferves that in Waigat’s ftraits the water was only brackith. He fays the tides come from the eaft with great velocity, bringing with them large iflands of ice. W. Barents (1595) confirms this account. All thefe effects can be produced by nothing elfe than the effufion of ices furrounding the pole. Thefe ices, which melt and flow with fach rapidity in the northern parts of America and Europe about the months of July and Auguft, * The Cafpian fea ig about 860 miles long, and, in one place, 260 miles broad: there are ftrong currents, but no tides. “There is no regular flux and reflux in the Baltic. In fome particular {pots of the Mediterranean there is a {mall tide. greatly 4 142 Examination of St. Pierre's Hypothesis greatly contribute to our high equinoétial tides; and when thefe effufions ceafe:in OGober, our tides begin to diminith. If the tides depended on the aétion of the fun and moon on the equator, they ought to be much more confiderable towards the focus of their movements than any where elfe. But this is ~ontrary to fact (Dampier fays). From: Cape Blanc, from the third to 30° fouth lat. the flux and reflux of the fea does not exceed two feet. The tides in the Eaft Indies rife not above a foot; near.the poles they rife 20 or 25 feet. : In the road of the tfland Maffafuero (33° 46! fouth lat. $a° 22’ weft long.) the fea runs twelve hours north, and then flows back twelve hours fouth: its tides, therefore, run to- wards the line. —Byron, April 1765. At Englith Creek, on the coaft of New Britata (5° fouth lat. £52% welt long.) the tide has a flux and reflux once in, 24 hours.—Carteret, , Aug. 4767 . At the Bay of Ifles, i in New Zealand (35° fouth lat.), the tides fet in from the fouth.—Cash, Dec. 1769. At Endeavour River, in New Holland, neither the flood nor ebb tides were confiderable, excepting once in 24 hours. June, 1770. At Chriftmas Harbour, -in Kerguelen’s Land, the flood eame from the fouth-eafi, running two knots an hour— Cook, Dec. 1776. It appears to have been recular and di~ urnal, 2. e, a tide of twelve hours. The tide rifes and falls about four feet. At Otaheite the tides feldom rife more than twelve or four+ teen inches ; and itis high water nearly at noon, as well at the quarters as at the full and change of the mn00n.—Cook, Dec. 3777. Itis evident, from a table of thefe tides for 26 days, that there was but one tide a day; and this, during the whole time, was at its mean height between tz and 1. Thefe tides, therefore, can have no relation to the phafes of the moon. Let us now take a curfory view of the effects produced by the tides in the northern part of the South fea. At the en- trance of Nootka it is high water, on the days of new and full moon, at twenty minutes paft twelve: the perpendicular. rifé and fall eight feet nine inches; which is to be under{tood of the refpecting the Caufe of the Tides, 143 the day tides, and thofe which happen two, or three days after the full and change. The ‘night ‘tides rife nearly two feet higher.—Cook, April 1778. Thefe femidiurnal tides: differ from ours in taking place at the fame’hour, and exhibiting no fenfible rife till the fecond or third-day after the full moon: all which is perfectly inexplicable on the lunar hypothefis. Thefe northern tides of the South fea, remarked in April, become, in higher latitudes, ftronger in May, and ftill ftronger in June; which cannot be referred to the moon’s courfe then paffing into the fouthern hemiphere, but muft be aferibed to the fun’s courfe paffing into the northern hemifphere, and proceeding, as its heat increafes, to fufe the ices of the north pole: befides, the direction of thefe northern ‘tides towards the line conftitutes a complete confirmation that they derive their origin from the pole. At the entrance of Cook’s River there was a ftrong tide fetting out of the inlet at the rate of three or four knots an hour: higher up in the inlet, at a place four leagues broad, the tide ran with prodigious violence at the rate of five knots an hour. Here the marks of a river difplayed themfelves, the water proving confiderably frefher.—Cook, May 1778. What Cook calls a river, is nothing but a real northern fluice, through which the polar effufions are difcharged into the ocean. Middleton (Voyage to Hud/on’s Bay, 1741 and 1742) found, between lat. 65° and-66°, a confiderable inlet running wett, which he calls Wager’s River; and, «after repeated trials of the tides for chive weeks, found the flood conftantly coming from the eaft. This is ‘another of the northern fluices. In Karakakooa Bay, Sandwich Iflands, the tides are very regular, ebbing and flowing fix hours each alternately. — Clerke, March 1779. At the town of St. Peter and Paul, in Kamfchatka, the tides are very regular every twelve hours.—Clerke, O&. 1779. Mr. Wales ({ntroduétion to Cook’s laft Voyage) acknow- ledges that the tides obferved in the middle of the great Pacific ocean fall fhort full two-thirds of what deci have been expected from calculation. The courfe of the tides towards the equator in the-South fea; 144 Examination of St. Pierre’s Hypothefis fea; their retardations and accelerations on thefe fhoress their direGtions, fometimes eaftward, fometimes weftward, according to the monfoons; finally, their elevation, which increafes in proportion as we approach the poles, and di- minifhes in proportion to the diftances from it, even between the tropics, demonftrate that their focus is not -wnder the line. The caufe of thetr motions depends not on the attrac- tion or preflure of the fun and moon on that part of the ocean, for their forces would undoubtedly aé there with the greateft energy, and in periods as regular as the courfe of the two luminaries. Why, then, are the tides between the tropics fo feeble and fo much retarded under the direét influence of the moon ? Why does the moon, by her attraction, give us two tides every 24 hours in the Atlantic ocean, and produce only one in many parts of the South fea, which is incomparably broader ? Why do the tides mike place there conftantly at the fame hours, and rife to a regular height almoft all the year round ? Why do fome rife atthe quarters juft the fame as at the full and change? Why are they always ftronger as you approach the poles, and frequently fet in toward the line, contrary to the principle of Junar impulfion ? *Thefe problems, which it is impoffible to explain by the Junar theory, admit an eafy folution on the hypothefis of the alternate fufion of the polar ices. Such are the moft material objeétions adduced to invali- date the lunar- theory. How far they are conclufive, fhall be left to future inveftigation. But St. Pierre is not content with demolifhing the old ftruture ; he has judged proper to ereét a new one; and a fair expofition of this fyftem will enable us to determine, by gomparifon, to which we fhall give our fuffrage. It is well known that Sir Ifaac Newton and Caffini differed in their opinion refpeéting the figure of the earth: the former conceiving it to be an oblate fpheroid, flattened at the poles ;- the latter contending it muft be oblong, or clongated at the poles. refpecting the Caufe of the Tides. 14% poles. To afcertain this point, fome of the moft celebrated mathematicians of Europe were appointed to determine, by actual meafurement, the length of a degree both at the equator and at the pole. They found that the polar degrees exceeded the equatorial, and concluded they muft confequently be parts of a larger circle, and, of courfe, that the earth was flattened at the poles. This was univerfally confidered as decifive of the queftion, till the genius of our Frenchman detested a grofs and palpable error in the calculation, which had efcaped their accurate knowledge and penetration: but, as the elongation of the poles con({titutes a leading feature in the new theory, I fhall give it a more detailed examination. This polar elongation, as he conceives, is fupported by four direct and pofitive proofs :—the firft geometrical, upon which he lays the greateft ftrefs, and upon which he has ftaked his reputation ; the 2d, atmofpherical; the 3d, naw tical ; the 4th, aftronomical : of all which in order. The 1ft, .or geometrical proof, is what he calls a demon- ftration founded on the meafurement of the earth, ang, admitting the polar degrees to exceed the equatorial: here follows the demonftration: If you place a degree of the meridian at the polar circle on a degree of the fame meridian at the equator, the firft degree, which meafures 57,422 fathoms, will exceed the 2d, which is 56,748 fathoms, by 6745; confequently, if you apply the arc of the meridian contained within the polar circle, being 47°, to an arc of 47° of the fame meridian at the equator, it would produce a confiderable protuberance, its degrees being greater, To render this more apparent, let us always fuppofe that the profile of the earth, at the poles, is an arc of a tircle containing 47°3 is it not evident, if you trace a curve on the infide of this are, as the academicians do when they flatten the earth at the poles, that it muft be fmaller than the are within which it is deferibed, being contained in it ? And the more this curve is flattened the fmaller it becomes.’ Of confequence, the 47° of this entire curve will be indi- Vidually fmaller than the 47° of the containing arc. But as the degrees of the polar curve excced thofe of the are of a circle, it matt follow that the whole curve is of greater extent Vor. VIE. U than 46 Examination of St. Pierre's Hyfothefis ‘ than the are of a circle: yow to be of greater extent it mufé be more protuberant : the polar curve, of confequence, forms a lengthened ellipfs. Q.E.D.* Tt mutt be acknowledged that this demonftration is very perfpicuous and convincing. How the moft celebrated aca- demicians and mathematicians, for nearly half a century, could have overlooked a propofition fo plain and fimple, can only be afcribed, in the opinion of St. Picrre, to their ob- flinate and inveterate prejudices. He purfues his victory in a firain of vain and indecent exultation, which would difhonour a more refpectable caufe; but, perhaps, a little attention will induce us to doubt at leaft whether the charge of grofs igno- rance may not, with juftice, be retorted on their accufer. It would have been indeed extraordinary, if men of fei- ence had been abfurd enough to imagine that a larger are might be included in a lefs; but they might fuppofe, with propriety and juftice, that the fmaller arc of a larger circle can be included in the larger are of a fmaller circle, which, ee the prefent inftance, appears to be the cafe. In meafuring a degree on the meridian, a certain fpot is fixed upon, where the elevation of the polar ftar is taken by’a quadrant ; from this fpot they proceed in a direct line north, till the quadrant indicates an additional elevation of one degree. In propor- faon as this degree ‘contftitutes a part of a larger or fmaller * Let, Fig. 3. Plate V. be the unknown arc of the meridian, comprehended above the arétic eircte ABC; and let DEF be the arc of the fame meridian, comprehended between the tropics; thefe two ares are each 47°. According to our aftionoiners, a degree at the polar circle is greater by 674 fathoms than a degree of the fame meridian near the equator; the arc x therefore exceeds, in extent, the arc DEF by 67447, Or 31,678 fathoms = 123 leagues. The queftion to be deter- mined is, whether this unknown polar are x is contained within the circle in the curve AA#C, or coincides with it, as A BC, or falls without its circumference, as AC. The arc x cannot be contained within the circle, as A 4C, for it would then be evidenthy fmaller than the ars” ABC; andthe more this curce ADC is Hattened, the lefs will be’ ~~ its extent, as ic will approach nearer and nearer to the ftraight line A Cc = Neither can it coincide with the are ABC, for it excceds it 122. leagues, It mutt belong, therefore, to a curve falling without the circle, as Aw C. The globe of the earth, therefore, is lengthened at the poles, fisce degrees of the ineridian are greater there than at the equator. circle, refpecting the Caufe of the Tides. 147 circle, a greater or lefs portion of ground will be paffed over before the defired elevation is obferved ; and the meafure- ment of this ground unequivocally decides whether this degree is part of a larger or fmaller circle. In this cafe the meafarement is aeued but the conclufion denied. St. Pierre feems to have fuppofed, that the academicians di- vided the polar are into 47 parts, and then meafured one of thefe parts: a thing impracticable and ridiculous. The fact is, that the polar arc, which, if the earth were a perfect fphere, would contain 47°, does not actually contain fo many, but perhaps about 46° of a larger circle; and if the polar degrees are parts of.a larger circle, as they certainly are, it is demonftrably evident that the real are muft be contained within the fpherical are, and, confequently, that the earth is flattened at the poles *. [To be continued. } Let the circle ABC D, Fig. 4. reprefent the earth as a fphere, and let P reprefent the polar ftar, having no fenfible parallax. Draw the diameter BD, prolonging it to P; draw the tranfverfe diameter C A, the tangent AP, and the line FP, parallel to AP; bifeét the quadrant A Di equally at F; draw the tangent K L perpendicular to the radius G F, and with the radius BF defcribe the circle EO MN, and let the fegment HEF reprefent the earth flattened at~the pole; draw the tangent SR fo the circle EO MN, perpendicular tothe radius BF, An oblerver at A will perceive the polar ftar P in the horizon; an obferver at Dor E will per- ceive it in the zenith, or at an elevation of 90°. If the earth be a fphere, _the tangent K L will be the horizon to an obferver at F, and the angle of elevation P F K is, by conftruétion, 45°; but if the earth is not a fphere, but flattened towards the pole, as in'the fegment HEF, the tangent SR will be the horizon to an obferver at F, and of courfe the angle PFS will be the angle of elevation.. Now, the angle F GF is by conftruétion 45°, confequently, the < F GB 135°, and the angles GBF and GFB each 22° 30’. Draw the dotted line EF. Now the triangle BE F is an ifofceles -triangle, ayd the angle GBF being found =.22° 30/, it follows that the angles B EF and BF E/are each 78° 45’, and the < S FB being a right angle, the < SFE is 90° — 78% 45’ = 11% 15’. At E draw the tangent TV, and, for the fame reafon, the < VE P= 11° 153 and confequently the < ExF = 157% 30', and the < Va'F = 22°30’. Now the to be perfecily harmlefs. The flowers appear about the end of May, and continue till the month of July; there are eften from twelve to fixtecn on’ one fem, each of which forms a bunch, containing from thirty to forty fingle flowers, Each fingle flower adheres to the bunch by a long thin flalk, and has'a fweetifh odour. Each bunch of flowers is fueceeded by three, four, and fometimes ten’ long; flat, and rough pods, which inclofe feveral round, yellowith brown, flat aud thin feeds wrapped up in a beautiful fhining white kind of filk. The feeds are winged; a form which nature has given with great variety to many others, in order that they may be conveyed with more eafe, and to a greater diftance, by the wind. MW. Upes.—ik, The filk, uhiek covers the feeds in the pods, is the principal part of ufe, and that from which the whole plant takes its mame. The pods gradually acquire maturity from Auguft to the beginning of October, at which time thofe who cuitivate this plant muft watch with great care for the period of their burfting, in order to collect ‘the filk, le(t it fhould be carried away by the wind, or be fpoilt by the rain. The pods when colleéted are ipread out, to the height of about half a foot, on .a net or rack, in an airy place, in ofder to dry. Th e filk, which is of a fhining white colour, from an inch: to an inch and a half in length, and exceedingly elailic, is then taken out, and being freed from the feeds 1s hung up, in thin bags in the fun, in order that it may become per- fe Sly dry ; and at the fame time it is often foftened with the hand, or by being beat. This vegetable filk may now be ufed, withont any further preparation, inftead of feathers and horte-hair, for beds, cufhions, coycrlets to beds, bolfters, and mattreffes. I'rom eight to nine pounds of it, which oc- ‘eupy the fpace of from fiye to-fix cubic feet, will be fufhi- cient fora coverlet, bed, and two pillows; fuch beds therefore are exccedinely gonyenient for travelling, It is not advife- 8 ! able, of the Syrian Silk-Plant. 15t able, however, to ufe this filk in common for beds inftead of feathers, as it is too foft and warm. It requires as little preparation for. quilts and counterpanes, and is lichter and warmer than thofe of common filk. For {pinning, however, notwithftanding its finenefs, which approaches near to that of common filk, it is not fit when taken alone, as it is almof too fhort, and therefore mutt be ufed with an addition of flax, wool, or common filk, but par- ticularly of cotton. One-third of this filk with two-thirds of cotton forms a very good mixture for gloves, ftockings, and > caps. Other mixtures may be ufed for different kinds of fuffs ; but it has been obferved that the cloth is much ftronger when the vegetable filk is employed for the woof rather than for the warp. Many colours have been applied to fuch cloth with great fuccefs, but as each fubfiance requires a peculiar mode of treatment, more experiments on this fubject are neceflary : a mixture of one-third vegetable filk, and two-thirds of hare’s down, forms hats exceedinely light, and foft to the touch, which have a great refemblance to beaver hats, and are much cheaper. ad, As foon as the pods have been collected, the ftems, which contain a fibrous part capable of being fpun, mutt be cut before they become dry or fuffer from the night froft. They mutt then be immerfed for fome dags in water, like flax orhemp, and then dried by being fpread out on the grafs. Care, however, muft be taken to afcertain, by experiments, the proper length of time, as too much or too little would be prejudicial. In the laft cafe the flaxy part is brittle, and ia the former it lofes its ftrength. After it has becn watered it is beaten and heckled: for beating it various kinds of ma- chinery have been invented, and for | bruifing the ems parti- eular mills are ufed. A mixture of the threads fpun from the flax of thefe ftems with the vegetable filk and cotton, produces a kind of cloth very proper for furniture. It has been however employed chiefly, with and without an addition of rags, for making all kinds of writing and packing paper; w hich fometimes 13 fimilar to the Chinefe paper, and fometimes exceeds ia -#rength the/ufual paper made from rags, 3d, Bot! ; 3d, Both 352 On the Cultivation and Ue 3d, Both the inner white fkin, and the external green hufle of the capfules, which contain the feeds, might be employed for manufacturing the finer forts of this filk paper. Ath, That as little as pofible of this plant fhould remain ulelefs, Nature has provided in the fweet juice of its flowers excellent nourifhment for bees. According to the author of Gefchichte-Meiner Bienen, this plant, in the above refpects the lime-tree escepied, is fuperior to all other vegetable pro- ductions. In America a kind of brown fugar is prepared from the juice of thefe flowers. The great utility of this plant bas been known only within thefe thirty years, though it is probable that it was intro- daced into Europe about the time of the crufades. A ma- nufactory of articles from the filk of this plant has been efta- blithed at Paris fince 1760, and it has long been employed at Laufanne, with advantage, for making candle-wicks; but no one has fhown more zeal in regard to the cultivation and preparation of this article than Mr. Schneider of Lieguitz, who has recommended it in two different pamphlets. In - regard to the application of it to paper-making, Mr. Schmid of *Lunenbure has made a variety of experiments; and it much to be wifhed that others would imitate his example. fil. Cultivationg—This plant is propagated twa ways, either by the feed or by flips. In the month of March, after the land has been well dug, the feeds are fown thin, and fingly, in furrows of the depth of an inch, and covered with earth, which is thrown over them to the depth of half an inch: they are fecured alfo from the night froft by mofs ora litle light dang. Tn from four to fix weeks the young plants begin to apps . The firft year they produce flea but do not bear feeds till the'fecond, and do not come to full ma- turity till the third. In the third year they are tranfplanted. But this method is more laborious, and perhaps ought not to be recommended but in particular cafes, fuch as when the roots have degenerated, or when they are traniplanted toa diferent climate. The obje& will be fooner r accomplifhed by flips from the roots. As the plant throws out around it long, roots with new of the Syrian Silk-Plant. 153 fiew eyes, thefe muft be lopped off from the old ftock either in autumn, when the milky juice in the plant has dried up, or in the fpring, before it again flows; and are to be cut into pieces of from four to fix inches in Jength, but care muft be taken that they have a fufficient number of eyes. A frefh incifion muft be made in the root before and behind, and they are then to be planted in the ground, to the depth of four or five inches, in an oblique pofition, with the eyes or buds ftanding upright. Thofe planted in autumn will produce feeds the next fummer, and thofe planted in {pring will bear the fecond fummer. In regard to the further care which this plant requires, the following obfervations deferve attention :—It thrives in al- moft every kind of foil, and even the moft ftony, without all further care: but, in order to be brought to perfeétion, it re- quires a tender fandy foil; which, however, muft not be too , oor and dry, and which ought to have as much fun as pof- fible. In fuch foil, when properly nurtured, it produces the longeft, fineft, and moft beautiful filk. The ground, before it is planted, muft be dug up to a good depth, and well dunged. It mutt alfo be well weeded, and kept exceedingly clean. After the crop has been colleéted, the ftems muft be cut clofe to the ground; and the plants which have died muft be replaced by young ones. Towards winter they mult be covered with a little dung, which ought to be fpread in the fpring. A fufficient fpace alfo muft be left between the plants. They ought to be planted in rows, and at the diftance of one foot and a half, or rather two feet, . from each other. Of the ftems which fhoot up, only the beft ‘parties about one half) fhould be left fanding ; the reft, as foon as the flowers appear, fhould be cut, and placed. in fand or earth, to dry up the milky juice that flows from them. Even of the prime plants, it will be proper to fuffer’ four or five of the loweft bunches of flowers to come to maturity. By fol- lowing thefe cautions, the filk obtained will be of a fuperior quality. The increafe is very great. In the year 1785, Mr. Schneider began with fix plants, and in 1793 had a planta-. tion which contained 30,000. The firft crop produced eight, *Vo-. VIII. ; x the t54 New Properties difcovered it the fecond 356, and the third 600 pounds of filk. If the Icaves, after the crop has been collected, be thrown toge- ther in heaps to rot, they form an excellent manure for fu- ture ufe. In regard to the preparation of the filk, little is. neceflary to be faid. It may eafily be conceived that it will be of advantage to feparate that which is long from the fhorter part, in order that the former may be employed for {pinning. The fhorter kind may be ufed for beds and for hat-making. This plant may be employed alfo in the manufaétory of paper. Schmid, an ingenious paper-maker near Lunenburg, has made feveral experiments with the capfules of this plant, which gave the following refults : 1h, From the interior white rind of the capfule, mixed with one-third of rags, he obtained writing-paper pretty ~ white, of a good quality, and fimilar to the filk paper of the . Chinefe. : ad, From the external green part of the capfules a greenifh-_ coloured paper, which, when fized, was ftronger than paper made of rags: “it was almoft as clofe in its texture as parch- ment, and even when unfized did not fuffer the ink to pe- netrate through it. This kind was exceedingly proper for wrapping-paper. 3d, From the ftems he shidoed a paper fo like in every; thing to common paper made of rags, that the difference could fearcely be diftinguifhed. X. On feveral new P roperties difcovered in phofphorifed Hy- drogen Gas. By C. RaymMonn, Profejor of Chemi/try - in the Central School of Ardeche*. V V E are indebted to C. Gengembre for the interefting difcovery of phofphorifed hydrogen gas. No chemift before: him had obferved an elaftic fluid which, like the one here fpoken of, poffeffes the fingular property of inflaming by the contact of the air alone, without requiring its temperature to be raifed, or an ignited body to be prefented to it. * From the Aznales de Chimie, No. 105+ The phofpborifed Hydrogen Gas. 153 The kind of undulating and always increafing ting to which this gas gives birth; when made to burn bubble by bubble in a place where the air is perfectly calm; the fplen- dour and magnificence which accompany its combuftion when effected in oxygen gas perfectly pure; the fudden pe- Netration of thefe two gafes, and their total converfion into water and phofphoric acid; fuch were the only facts known which had been interefting to chemifts in the hiftory of phof- phorifed hydrogen gas; when I endeavoured to difeover whe-’ ther this elaftic fluid did not poflefs other properties, which, if they did not exhibit fo brilliant a fpeétacle as .the greater part of thofe above alluded to, might be worthy of engaging the attention of chemitis. The property, long known, which fulphur communicates to hydrogen, and hydrogen reciprocally to fulphur, of being able to diffolve together in water, while both taken feparately are perfectly infoluble, had already given me reafon to think that the cafe might be the fame with the combination of phofphotus and hydrogen; and that thefe two fubfances, being previoufly united, might perhaps then become fuf- eeptible of partaking in the liquidity of water, and commu- hicate to it new properties nearly analogous to thofe poffefled by that folution of fulphurated hydrogen gas known under the name of bepaiifed water. To deftroy or confirm this fuppofition, I took a piafs bot- tle, and, having filled it with newly diftilled water, inverted it on the fhelf of a pneumatic tub, in order that I might in- troduce into it phofphorifed hydrogen gas arifing frem thé decompofition of water by a mixture made with phofphorus and frefh-flaked lime. When the bottle was half filled with phofphorifed hydrogen gas I removed it from the tub, taking éare to fhut very clofely its aperture with my finger, while I fhook it with force in order to effet more fpeedily an union of the gas with the water, in the fame manner as the folution of carbonic acid gas, as well as that of fulphurated hydrogen gas, is facilitated by making ufe of the fame means. I foon perceived, by the ftrong adhefion of my finger to the mouth of the bottle, that a confiderable vacuum had been ‘ efeCled in it, and perhaps, even, that the whole of the phof- X.2 phorifed. 156 (ANB Properties difcovered in phorifed hydrogen gas in it had participated in the liquidity of the water. i I then removed my finger, but not without fome difficulty, from the mouth of the bottle, that I might examine more accurately the nature and properties of the liquid it contained, and to afcertain whether there did not yet remain fome por- tions of the gas fufceptible of inflammation by the contact of the air. But, fcarcely was the communication eftablithed between the atmofphere and the infide of the bottle, when a loud detonation took place, accompanied with a very bril- ant light. I readily judged from this phenomenon, that the whole of the phofphorifed hydrogen gas had not been abforbed by the water contained in,the bottle; on which ac- count I clofed the aperture, in order to prevent the combuf- tion from being longer continued ; which would not have failed to produce a confiderable quantity of phofphoric acid, and confequently to occafion great uncertainty in regard to the refults which I withed to obtain, The bottle having been clofely ftopped, I continued to fhake it feveral times, under an idea that I fhould by thefe means be able to fix entirely the laft portions of the phof- phorifed hydrogen gas which had remained undiffolved. Hoping that I had fucceeded, and impatient to know the new properties which the water faturated with the gas might have acquired, I determined to unft lop the bottle a fecond time in contact with the air. This was foon followed by a fecond detonation, ftronger, indeed, than the former. After this I did not think of ftopping the aperture of the bottle, fo that a flame exceedingly pale continued for fome minutes to iffue from it. When I obferved.no more apparent figns. of combutftion, I examined by the fmell and tafte the eee remaining in the bottle. Its/fmell appeared to me exceedingly dilsprave able, and altogether different from that of gafeous phofpho- rifed hydrogen ; its tafte, though very bitter, had in it, how- ever, fomething infipid and difeufting and its colour was. little inclining to that of lemon. When tried with tin€ure of turnfol it foon made it fenfibly red, which J:afcribed to the fmall portion of phosphoric acid. which Se a ee ee mt phofphorifed Hydrogen Gas. 157 which muft have been produced at the moment when the detonations took place, as well as during the difengagement of the flame which followed the fecond detonation. I was then obliged to begin a new operation, that is to fay, to diffolve phofphorifed hydrogen gas again in water, that [ might afcertain, by employing more caution, in what accu- rate proportions this folution might be effected; and that I might prevent combutftion alfo from taking place in the in- fide of the bottle, which would have become a fource of error in the conclufion of my experiments. I had afcertained with certainty, by means of the quantity of water and gas which I had tried to diffolve the firft time, as well as by the detonations which had taken place at the moment when the bottle was unftopped, that diftilled water could not diffolve at’ the temperature of 47° a volume of phofphorifed hydrogen gas equal to its own. I took care, - therefore, to introduce into the bottle the fecond time only about a third of its capacity of the gas. I then repeatedly fhook the mixture in order to render the union of the gas with the water fpeedier, and as complete as poffible; after which I unftopped the bottle, holding it inverted in a fmall tub, which I had filled with newly diftilled water, that I might fee whether it would become entirely filled with it merely by the effect of the preffure of the atmofphere, and that I might thence judge whether the whole gas had been ‘liquefied. I indeed faw a portion of the water in the tub afcend into the bottle, but I perceived alfo that it was not entirely filled which confirmed me in the opinion that there ftill remained a portion of the gas which had not participated in the liquidity of the water. Having then tried to make fome bubbles of it iffue out through this liquid, thefe bubbles inflamed fponta- taneoufly by the contact of the air alone; which proved to me that the phofphorifed hydrogen gas had not been decom- pofed at all by agitation, nor by its contact with diftilled water; whereas it foon lofes its highly combuttible property when colleéted in bottles filled with water which has not been diftilled, or diftilled water which has been long kept, which } afcribe to the quantity of air which common water always holds 158 New Properties difeovrered i in holds in folution, the oxygen of which, joining a portion of the phofphorus, effects its feparation from the hydrogen by converting it into phofphorous oxyd, which being altogether infoluble; depofits itfelf on the fides of the vefiel, without any appearance in this kind of oxydation of any fenfible fign of combuttion ; while the oxygen of the atmofpheric air, which participates in the liquidity of the water, being always in that cafe deprived of a large portion of the light and caloric which are combined with it in its aérial aggregation, cannot pro- duce thefe two effeéts in a very fenfible manner when it paffes in this ftate of hquid aggregation from one combina- _tion to another. Having again agitated the bottle after clofing the mouth of it, I was able, by means of the {mall quantity of water which had been introduced into it, and of which I kept an exact account, to render the abforption of the laft portions of the gas complete; for, having a fecond time uncorked the bottle in the fame diftlled water, I then faw it become entirely filled. Itbink I may affirm, therefore, from thefe trials, and fome others which I made, that water freed from air by diftiation can diffolve and liquefy, at the ufual temperature, 2 little lefs than the fourth of its volume of phofphorifed hy- drogen gas, and that with this dofe it is completely faturated. This folution thus prepared, and kept free from the con- tact of the air, always exhibited the following properties : In colour, it has a pretty near refemblance to fulphur in flicks, though a little lefs dark ; it has a ftrong difagfeeable odour, and an exceedingly bitter, naufeous, and difgufting tafte. When examined in the dark, this folution does not appear Jumiiious ; which proves that the phofphorus is intimately combined in it w ith the hydrogen. When diftilled in. a fmall retort, connected with a pneu- ‘matic apparatus, it furnifhes, at a temperature a little above that of boiling watér, and efpecially when diftilled foon after it. has been prepared, a very large quantity of phof- phorifed hydrogen gas, as pure and: as combuttible as that obtained by heating cauftic alkalies, or quicklime, with phofphorus ‘and a very fmall quantity of water: what after- 4 wards — — > ee eee eee phofphorifed Hydrogen Gas. 159 ‘wards remains in the retort after the difengagement of this gas has entirely ceafed, is nothing elfe than pure water, having neither odour, tafte nor colour, and perfeétly re- fembling water newly diftilled. When brought into contact with atmofpheric air, this folution foon fuffers to be depofited a remarkable quantity of red oxyd of phofphorus, and at the fame time fuffers to be difengaged hydrogen gas, which is no longer fufceptible of inflammation, except when brought into contaét with a body in a ftate of ignition. If the folution be long expofed to the air, and if the points of conta& be frequently re- newed by agitation, it becomes completely decompofed ; that is to fay, is entirely refolved into phofphorus, oxyd, and pure hydrogen gas. _ Tindture of turnfol and that of violets experience no change in their colour from being in conta& with liquid. phofphorifed hydrogen; which proves that this liquor is neither acid nor alkaline. The fulphuric and nitric acids, or the fimple or oxygenated muriatic, when poured over this liquor, produce no effect worthy of notice. Potafh, foda and ammonia a& in the fame manner. The oxyds of mercury and lead are fpeedily reduced, and immediately converted into metallic phofphurets, by being mixed with the folution of phofphorifed hydrogen gas. When poured into nitrat of filver, this folution immedi- ately produces a very abundant black precipitate, which does: not in the leaft change its colour, and which, when tried by the blow-pipe, exhibits the charaéters belonging to me- tallic phofphurets. When brought into conta@. with a folution of mercury by nitric acid, it gives alfo immediately a very confiderable precipitate, which has firft a black colour, but which be- comes white and cryftallifed in proportion as it paffes from the ftate of phofphuret to that of mercurial phofphat, by imbibing oxygen, either from the nitric acid in which the precipitation takes place, or from the atmofpheric air with which it is in conta&. A folution of lead by the nitric acid is’ alfo decomipofed by 160 . New Properties, (8e. ; hy the hydro-phofphorous liquor, but with lefs force than the folutions of filver and mercury are. There is formed in this decompofition alfo phofphuret of lead, which in the courfe of time is converted into a phofphat. The fulphat of copper fhows alfo, at the end of a certain time, a pretty abundant black precipitate when poured into a folution of phofphorifed hydrogen. This precipitate, like. that obtained by the decompofition of nitrat of filver, re- tains its colour; which may give us reafon to believe that “it can be converted only with difficulty into a phofphat. Sulphat of iron did not appear to me to experience any. fenfible decompofition till the end of feveral days. Nitrat of arfenic; poured into this liquid, did not experience any fen- fible decompofition till the end of feveral days. There was then formed a precipitate of a very beautiful yellow colour under the form of fmall grains, and which could remain a long time expofed to the air without experiencing avy kind of change. This precipitate was an arfenical phofphuret. It refults from thefe new properties, firft difcovered, I think, by myfelf, im phofphorifed hydrogen gas, 1ft, That this gas can unite itfelf to diftilled water, in the proportion of Ce a fourth of its volume, when the folution is ef- feGed at the temperature of 44°5 of Fahrenheit’s thermo- meter*. 2d, That this gas communicates to the water in which it is diffolved a ftrong difagreeable odour, as well as a bitter tafte, which may one day make it be employed with fuccefs in the treatment of many difeafes, either on account of the facility with which this preparation futfers itfelf to be decompofed, or of the part performed by the phofphorus it contains in the formation of animal matters. 3d, That when water well freed from air has been employed to liquefy this gas, and when care has been taken to keep it thus dif- folved in bottles well corked, it may be preferved a long time without experiencing decompofition, fo that by heating the folution you may extract from it, in the flate of gas, all the phofporifed hydrogen it contains. 4th, That when * It is probable that at the temperature of freezing water mighg.diffolve a larger quantity, but the want of phofphorus prevented me from afcertain- ing this fact. the a eS eee On the general Naturé of Light. 164% the water has thus been freed from all the phofphorifed hy- drogen it had diffolved, it becomes pure water; which proves that it was indebted for its new properties to the pre- fence of this gas alone. 5th, In the lait place, that this . folution is capable of fpeedily reducing feveral metallic oxyds, whether alone or diffolved by acids, and of forming with them, by means of double electrive attraction, water and me- ‘tallic phofphurets, combinations which hitherto have been obtained only in the dry way; that is to fay, by heating metals with phofphorus, or by decompofing phofphoric glafs or metallic phofphats by metals and charcoal. Such are the properties which appear to me fufficiently interefting to be worthy of being added to the ftill imperfect hiftory of phofphorifed hydrogen gas. XI. On the general Nature of Light. By Mr. Ropert HERON. Cummunicated by the Author, "TL urovcn the medium ofthe Philofophical Maga zine I beg leave to lay before men of fcience the following opinions, which have lately fuggefted themfelves to meas . neceffary and fair inductions frora thofe facts that have come ‘to my knowledge refpecting light. _1. Light paffes only through the vacuities in other bodies s does not penetrate their folid fubftance, fo as ever to coexift with it in the fame place.: 2. It pafles through thofe vacuities in ftraight perpendi- cular lines, without any lofs of its qualities by attenuation aud fubdivifion of its particles: or, it is refracted from the perpendicular with a fubdivifion of its particles, by which its qualities are altered: or, its paflage is wholly interrupted, and it is either reflected or abforbed. 3. Since general attraction aéts in bodies in the proportion of their mafles and aggregation; fince the more the affinity of aggregation is in any bodies deftroyed, fo much the more readily and powerfully do the chemical affinities of com- pofition a¢t upon them; fince the extreme tenuity of light, Vor. VIII. ¥ the 162 On the general Nature of Light. the fubtilett of all vifible fubftances, renders it infinitely fepfible, equally to the general attractive force and to the chemical affinities of other bodies approaching it :—for thefe feafons, the fame general and chemical affinities, which pro- duce the other changes on material bedies, mutt appear tuf- ficient to occafion the different phenomena which light pre- fents in its various tranfitions. ‘4. The true primitive colour of licht, when unmixed with other fubftances, when its particles exilt together in their natural arrangement and aggregation, when the at- tractions of other bodies for it act not fo as to fcatter or de- compofe its parts, ts while. 5. Its colours and its peculiar action on the optic nerve depend on the peculiar forms of its elementary particles, on their peculiar agerezation, on their mechanical and chemical qualities, on the modes of its dif/ufion. 6. It paffcs without alteration or deflexion through tranf- parent bedies i» which the abtolute vacancies are fufficiently numerous to receive ifs rays, in which the difpofition of thefe vacancies is perpendicular. to the dire@tion of the rays, and in which the attractions of the body for the light are not fo ftrong as to act on the rays with a diflolving or a de- compoting force. 7. It is refraéed, when the vacuities it the bodies on which it falls are not difpofed throughout the tranfparent medium perpendicularly to the direction of the rays; and. when the attractions, cheniical and mechanical, of the parts of that medium are, in refpect to light, fo powerful as to oceafion either a tendency to the carrying of the ray into new combination, which fhall alter its aggregation, or even a partial fixation of it im fome new compound. 8. It is refleéted when it falls on furfaces which prefent no 7eélilinear vacuncies, none but fuch as are curves, through which its rays cannot pals; and when, at the fame. time, thofe furfaces have no affinities for its particles of fuificient ftrength to attract thefe particles imto their owt compofition. When thele circumftances concur in their utmoft power the reflexion is complete, and all the falling rays are returned from the furface; but the required cir- 4 cumitances On the general Nature of Light. 163 cumftances feldom do fo fully concur. In moft cafes of the reflexion of light, there is a portion of the falling light either tranfmitted or abforbed. g. Light 1s abforbed in the bodies on which it falls, when their attractions fix it in new compounds. with their parts; or when they prefent a medium in which it may be for a time fufpended, though not carried into aétual combi- nation. 10. As the primitive colour of light depends, in a great meafure, on the conformation and the relative arrangement of its particles, fo the other colours which it aflumes in're- fraction depend likewife on changes in’ the arrangement of thofe particles which vary the cflect of their conformation, While the particles remain in the fame arrangement the colour is the fame; and their elementary coniormation, and the law of movement to which they are fubject, continue their illuminating effect to the eye till they are loft by ex- treme diffufion, by abforption, or perhaps by entire decom- pofition. The permanent calours of the furfaces of bodies depend on the fame laws as the colours of the rays of light. The - conformation and the arrangement of the eatreme elementary particles at the furfaces of all bodies determine, refpectively, their different colours. White furfaces, for inftance, have one conformation and arrangement of the minutett par- ticles at their extremities: d/ve furtaces have another con- formation and arrangement of the fame particles: red fur- faces another, &c. &c. Thefe extreme particles of the fur- faces of bedies do not conftitute light, becaufe they are not unconfined and in motion, have not its peculiar re@tilinear elafticity, ‘pofefs not its chemical affinities; but when light’ is thrown upon them, they become vifible, each fet of particles under a different colour, juft as its conformation and arrangement are difierent. The extreme particles of blue furfaces have the fame conformation and arrangement as the particles of light in a b/ue ray; and fo of other co- Jours, m4 '>) XI. 4e- f 164 XII. Some Account of FREDERICK AUGUSTUS Escuen, who was fwallowed up in a Fi ‘ffure of the Snow in the Glacier of Buet*. A soa AucGustus EscHen was born in 1779, at Eutin, in the circle of Lower Saxony, where his father enjoyed a public office, which gave him an opportunity of having frequent intercourfe with the archbifhop of Lubec, his fovereign, by whom he was highly efieemed. The prince ftood godfather to this fon, and invefted him with the ca- aonicate. Being the eldeft of a numerous family, young Efchen was fetined for the ftudy of jurifprudence, with a view that he might be fitted for holding fome public employ- “ment; but his Fa did not confine his education merely to thofe branches of knowledge neceffary for that line. He was inftructed in the feiences and the fine arts; and, being early familiarifed with both, he applied to them with unabated ardour, and made fach a rapid Prog refs as attracted the at- tention of fome of the mot celebrated men of Germany, among whom was Vofs, who lived in ‘the fame village, and was an intimate friend of his father, -Young Efchen,was particularly noticed alfo by Count Stolberg, well known by his tranflaticn of Plato’s Dialogues and his Travels through Swifferland and Italy. At the age of twentv, young Efchen quitted his father’s houfe, and repaired to the univerfity of Jena, where he ap- plied chiefly to philofophy and junfprndence 5 ; the former of which he ftudied under Fichte, the difciple and rival of the celebrated Kant; and theatter under Profeffor Gufeland, a man as much diftinguifhed by his private virtues as by his talents and learning. Natural hiitory and philofophy occu- pied alfo fome part of his attention; nor did he,negleét po- etry, to which he had a ftrong natural propenfity. He tranf- lated feveral pieces from the Greck and Latin languages, which were almoft as familiar to him as his own, and to which he had added almoft all thofe of Europe. He pub- * See our laft{ Number, lithed Account of Frederick Auguflus Efchen. 165 lifhed. alfo various fpecimens of original poetry, many of which, of the Idyl kind, met with the approbation of Schiller and Goethe, the former of whom inferted one of them in. the Almanac of the Mufes, of which he is the editor. Another of thent, entitled Die Lebre der Befchie- _denbeit, The Leffon of Modefty, deferves to be known on account of the ingenious manner in which the author treats a trifling fubjeét little fufceptible of poetical ornaments. Efchen wrote alfo feveral efflays and differtations on different points of antient literature, which appeared in fome of the German journals, and which procured him an acquaintance with feveral men of eminence in the republic of letters. It is no little recommendation of Efchen’s character, than we can mention among thefe Schlegel and Humboldt. In the fpring of the year 1798, Efchen undertook a journey to Swifferland in order to fuperintend the education of a young man, chiefly with a view that he might improve his own; and for that purpofe fettled at Berne, where one of his coun- trymen had been before engaged in the fame occupation. Others foon followed him; and fome young inhabitants of Berne, who had been the companions of his ftudies at the univerfity, joined themfelves to the circle of his friends. In the enjoyment of their company, with the charms of friend- fhip and ftudy, though amidft the ftorms of the revolution, he faw two years glide away in peace, and diftinguifhed by labours which might have done honour to a longer life. His tranflation of the Odes of Horace had juft appeared a little before the fatal event which fnatched him from letters and from his friends. This production may be reproached with containing too many Latinifms and bold expreffions little fuited to the genius of the German language; but with | all thefe faults it will fti}l remain a claffic work worthy of being ranked among the real treafures of German literature, and suhich ought to have infpired the greateft hopes of young man, who, at twenty-three years of age, could yen- ture to undertake a tafk fo difficult. The unfortunate cataftrophe which bboikared the life of thjs interefting young man has been already detailed in this journal, 166 On the Difcovery of Seignette’s Salt. journal. We {hall therefore only obferve that, about the end of July, this year, Efchen undertook, in company with M. Theodore Ziemfen his friend and countryman, a tour to the borders of the lake of Geneva and the valley of Cha- mouni. They afcended together the Buet, a bigh mountain behind the village of Servoz, celebrated by the experiments. made there by De Luc and Sauflure, and which commands a view of the country round Mount-Blanc. They were juft on the point of reaching the fummit, and nothing feemed to announce that any danger was to be apprehended; Efchen was walking forwards in high fpirits before his friend and their guide, when, all of a fudden, his two companions Jott fizbt of him. A thin cruft of fnow, which covered a deep fifiure, had given way under his feet, and he fell into the abyfs; where he peri(hed as already related. XII. On the Difcovery of that Salt known under the Name of Sergnette’s Salt (Lartrite Pasa) By Profejjor Beck- MANN. "Eats neutral falt, which confifts of the mineral alkali (foda) and the acid of wine-ftone (fartareous acid), was pre- pared and made known by a Frenchman named Peter Seig- mette, towards the end of the laft century. The confidence with which the inventor recommended it, and the care he took to conceal the method of making it, bad, as is ufual, fuch an effect, that it was employed in preference to many otber medicines, long known, which had been cqually fer- viceable; and by thefe means he was enabled, without much trouble, to acquire a fortune. Jt mutt, however, be allowed that he was a fkilful chemift, who, by his writings and the invention of various other medicines, had obtained confider- able reputation as a phyfician and naturalift. He was efta- blifhed as an apothecary at Rochelle; publifhed papers on various natural objects which he had obferved in his neigh- bourhood, in the Memoirs of the Academy of Sciences at Paris, as well as in other works, and died on the 11th of March On the Difcovery of Seignette’s Salt. 167 March 1719 *. He recommended this falt, whichentiched him and rendered his name famous, in fome fmall:treatifes printed, in particular, about the year 1672. He cailed it fometimes alkaline fult, fometimes fal polychrefl, and fome- times Rochelle fait. After his death, his fon continued to prepare and to vend it with the greateft fucceis. Manufacturers and mechanics have been often reproached with the jealoufy which they entertain of literary men; but, in my opinion, the latter are the caufe of it. It muft indeed be confeffed, though humiliating for human knowledge, that the moft ufeful difcoveries have at firft prefented themfelves to the former, while engaged im the various operations which their employments require; but their merit confilts principally in remarking and following phenomena till they produce from them fomething ufeful. If they are fo fortu- nate as tc fucceed, they keep their difcoveries fecret in order that they may enjoy a monopoly of them; but no fooner has the man of letters heard of a new difcovery than he withes to have a fhare in the honour of making it known; and his zeal in this refpect is proportioned to its importance and the care with which it is concealed; becaule, in general, he can gain only by rendering it public. The man of letters, how- ever, has a great advantage over the mechanic or manufac- turer, as his exertions never fail to be approved; becaufe, by endeavouring to diffufe an important benefit, he appears in the character of a patriot, a friend to mankind, and a citizen of the world; and may thus place the merit of the mechanic or manufacturer in a difadvantageous point of view. This oppofition of private intereft proves of great utility to the whole fociety of which both parties are members. When the mechanic or manufacturer makes difcoveries, they are communicated to the public by the man of letters; who, by thefe means, renders them ufeful ; prevents their being hurt- ful by a monopoly ; fecures them from dying with the dif- coyerer; and, by inveltigating the principles on which they * Some of Seignette’s papers ave printed in Biblioshegue Hiflorique «le fa Fiance par Ferret. de Hontelte, Paris 1778, 5 vols. fol. fuch asa paper taken from Memoires de 1’ Acad. 1707, p. 1 155 and alfoin Prffoire de la Rochelle, par M, Arcére, Wel. UL. p. 424. » depend, 168 On the Difcovery of Scignette’s Salt. depend, makes their benefit to mankind more certajn, and fhows how they may be applied in various cafes of which the artift or manufafturer never had an idea*. If, by this eondu&, he leffen the merit of one, he on the other hand points out employment to many ;° and gives rife to eftablifh- ments in which thoufands participate, and by which they acquire riches. Thus Seignette difcovered fal polychreft while he was engaged in making foluble tartar (tartrite of potafh), and, according to the old opinion, imagining that both the fixed alkalis were the fame, ufed foda inftead of the alkali of tartar (potath). By thefe means he procured, not without furprife, a falt different from the common foluble tartar, which he withed to prepare, and from the other well known falt alfo. He was induced therefore, to examine it; and having found it to be a new laxative, he recommended it and became rich. The experiments of learned chemifts difcovered the compo- nent parts of this falt; the mode of preparing it was then made publicly known; and, by more accurate examination, the difference, before overlooked, between vegetable and mineral alkalit was determined: by which new light was thrown upon chemiftry, and an important fervice rendered to a variety of arts. Among thofe who contributed to bring this falt into re+ pute was N icholas Lemery, to whom Seignette fent a large quantity of it, which he diftributed at Paris, though unac- guainted with its component partst. Its compofition was difcovered at the fame time, about the year 1731, by two French chemifts, Boulduc and Geoffroi. The former pub- lifhed his obfervations in the Memoirs of the Academy of * Nam invenire preclare, enuntiare magnifice, interdum etiam barbari folent; difponere apte, figurare varie, nifi eruditis, negatum eft. Pin. Epift. W213. + Profeffor Gmelin, in anfwer to the queftion, Who firft remarked the difference between the vegetable and mineral alkalis, replied that, at any yate, it was firft properly defined by Stahl. See G. E. Stadlit Funda- menta Chymie dogmatice et experimentalis. Norimberge. $746. 3 vol. 4to. IIL. p. 268 and 304. + Lemery Volikommene Chy mift. Drefden und Leipzig, 1734- 2 vol. vo. I. p. §1a. Scuuen- 4 Proportions of Charcoal in Wood and Pit- Coal: 16g. Sciences *; and the latter communicated his to Sir Hans Sloane, who caufed them to be printed in the Philofephical Tranfa@ions t+. I fhall here obferve that chulzt has afferted falfely that Neumann made known the compofition of Seignette’s falt in his Treatife on Saltpetre ; for Neumann’s fal polychreft-is effentially different; and he himfelf con- feffes§ that he was not acquainted with the Rochelle falt. After the above period, the nature and properties of the mi- neral alkali were examined with more accuracy by Grofle, Duhamel, Brand (a Swede), and feveral others | , — = ——— —- SS SSSI KIV. On the Proportions of Charcoal, or Oxyd of Carbon, con- tained in certain Kinds of Wood and in Pit-Coal; and on @ Carburet of Sulphur newly difcovered. By M. Proust 4. Gr EEN oak yields of chafcoal 20 per cent.; wild ath 173; willow 173; white afh 17; pine 20; heart of oak 19; black ath 25; guaiacum 24 per cent.: but all good pit-coals. afford 70, 75, ‘or 80 fer cent. of carbonaceous matter ; and there are fome kinds which exhibit no figns of contain- ing hydrogen; and which burn without either flame or fmoke. This abundance of carbonaceous matter yielded by pit- coals does not depend on their containing a larger proportion of earth; for good pit-coal yields as {mall a proportion of afhes as dried pine-wood. The pit-coal of Afturia and Andalufia yields only 2 or 3 ger cent. of afhes ; that of Eftre- imadura not more than 6 or 7 per cent. Befides the known produés obtained from the diftillation 4 Mempires de 1 Academ. des Sciences; Aunée 1731, pi 124. + Nv. CCCEXXXVI.-p. 37. + Chemifchen Verfuchen, Halle, 1745. 8vo. p: 50. § Neumann’s Chymie nach Keffels avfgabve. [..3. p. 1603 || An account of the principal writings on Scignette’s falt may be found in Weigel’s Chymie, Griefswaid, 1777, a vol. 8vo. LI. Pp 1225. See al{o Grorgii Ludov. Enckelmann Diff: de Sale Alkali de Seignette, ejufque Natura ‘sef Uju. Argentorati, 1756. 4to. q From the Yournal de Phyfique, Vor. VHE. Zz of 890 Proportions of Charcoal in Wood and Pit-Coal. of pit-coals, IT have reafon to believe that they contain @ fmall portion of faccinic acid. The colle&ted produés from 30 /b. of pit-coal afforded me about one dram of a particular falt, which, by its fmell, indicated the prefence of that acid. But what more particularly arrefled my attention in the analyfes of pit-coal was a very peculiar combination of fome of ‘the carbonaceous matter with .a portion of fulphur, and _where pyrites was not prefent. A coal in the vicinity of Almaden, in Eftremadura, which contains no pyrites, yields very white afhes, and from. which no fulphur can be obs tained by diftillation, exhibits, however, as it paffes from imcandefcence to incineration, proofs of containing fulphur, which, becoming oxydated along with the coal, makes it fenfible to the fmell. A peculiar carburet of fulphur there- fore exifts m this coal; but combuftion is neceflary to its decompofition. Expofed to the greateft heat, this coal neither difcolours filver, nor affects iron in the forge. This fingular phenomenon, happily perhaps for the arts, 1s one of the caufes which fo beneficially retard or pro- Jong the combuttion of pit-coal. | Phofphorus eombined with charcoal is much lefs combuftible than when alone : neither the conta¢t of atmofpheric air, nor even the com- bined aétion of alkalis and water, is fufficient to fepa+ rate phofphorus from its combination with carbon, From the difficulty with which the earbonaceous portion of ani- mal fubftances is burnt, the fame inference may be drawn refpecting fulphur; for fulphur is known to exift in a con- fiderable proportion in animal febftances. Wool, unquef- tionably, contains much fulphur, but none pafles over when that matter is diftilled. Where then can it remain, if not in union with the carbonaceous refiduum? That-refiduum fhould be examined witha view to this point. One thing is certain, that foap of wool, prepared in a filver veffel, deeply fulphurates its interior fui face. XV. Let- [4 XV. Letter from A. M. Vasatei-Eanpi to J. Bovina, Profeffor of Medicine in the Univerfity of Turin, on Animal Ele€tricity*. i Tur eletric phenomenon which you obferved in my electrometer, placed on the back of a difeafed animal at the moment of its being attacked by a fit of fhivering, appears to me to be a neceflary confequence of the general theory of eleétricity, and of the modifications which it experiences in the animal economy. The following is the manner in which, I think, I have proved in my letter on the origin of animal electricity, that man, in the ftate of health, like all other animals, has parts pofitively electric, while others are negatively fo. It appears that, in the animal, the negative part, that of the excretions, is not fo ftrong as the pofitive part, that of the blood. But if the change of the animal economy de- firoys the natural boundaries of eleétricity in the body, on account of the tendency of the latter to bring itfelf into equilibrium, it ought to efcape and to manifett itfelf exactly at the moments when the boundaries are deftroyed +; that is to fay, when the virus changes the internal parts, which is proved by the fits of fhivering: fear and other violent paf- fions, as they change the animal economy, ought alfo to produce the fame cffeét. Thus you have feen the firings of my electrometer, placed on, the back of the animal, feparate from each other, either during the fits of {hivering occa- fioned by a contagious difeafe, or during thofe produced by fear; you fee that the fame theory explains alfo the want of electricity which you obferved in difeafed cats. I am per- fuaded that this want will in no cafe exift till the difeafe has continued feveral days, and the animal economy has become deranged. When I concluded my eleéric experiments on water and ice {, [ repeated them on feveral liquids, animals, * From the Yournal de Phyfique, Pluviofe, an, 8. 4 Journal de Phyfique, Metidor, an. 7. t Memorie della, Sovieta Maliana, Vole lil, Sap) and 172 Chemical and Mineralogical Nomenclature. and vegetables, as well as on different preparations of water. Urine ‘and animal humours exhibited to me the greateft degree of eleétric difference. - You fee then that my opinion is fupported by facts. As I have found, however, that the blood of thofe labouring under an intermittent fever is ftill pofitively electric *, it might be ufefuyl to afcertain in what difeafes, and at what degree of thofe difeafes, it lofes its eleGtricity, Might not the electrometer be employed to diftinguifh defperate difeafes, and be ufed, if I may be al- lowed the expreffion, as a vitalitometer? But many expe- rimenis are (ull wanting before we can reach that point /of perfection in the feience of eleétricity. The dilcovery of electricity in the torpedo feems aftonithing. That of Co- tugno, who received an electric fhock from a moufe which he was difiecting; and that of Tonfo, who had one from a cat; and my eleétric experiments on rats feem conclufive. But the immenfity of nature ftill prefents matter for new refearches ; and at prefent, fince I have found the electricity of the blood and that of the excretions contrary, I fee how much remains to be done to reduce to their jutt value the opinions of Gatdini, Bertholon, Treflan, and Carlice, on ani- mal electricity. You have purfued the beft route, which is to interrogate nature by experiments. Continue to do fo, and you will enjoy the fatisfaction of having enlarged the boundaries of fcience. ———eeeeeeeeeeeSeSSSSeSeeeSsSSesesSsHsssFSeeeee XVI. Of Chemical and Mineralogical Nomenclature. By RicHaxD, Kirwan, LED. F.R.S. and P.R.ILA.t - Pe E names given to the different fubftances known in common life, whether oceurring in nature or produced by. art, are coeval with languages Hentai and whether all were mercly conv entices or fome of them grounded on fome relation to the thing fignified, is now of little importance to inquire, as from Jong habit both are equally immediately re- ferred to the thing fignified, without any refle€tion on the * Fourna’ de thifgte, Germinal, at. 7. } Fiorp the Tranfuciions of the R yal lrife Acad my for 1800. original ee ‘ — Chemical-and Mineralogical Nomenclature. 173 original reafon of their impofition. . Thus, though the name barometer was originally impofed on the inftrument fo called, becaufe the terms that compofe this name, baros and metron, denote its ufe in meafuring the weight of the atmofphere ; yet*the name is juft as well underftood by thofe who are to- tally unacquainted with its etymology, as by thofe to whom this is perfectly known. The inftrament itfelf, and not its ufe, is denoted by the name, and equally occurs to both; the workman who knows not its ufe, knows what the name immediately fignifies as well as the philofopher who employs it, and as well as the German who calls it a /chwermeffer, whofe primitive components alfo exprefs its ufe; nor is it better underftood by either than the name /crew or /chraube, which cannot be refolved into any primitive component terms. Who, on, hearing the Latin name of a book, ever thinks of its primitive fienification—the bark of a tree? Languages muft have been invented jong before either chemifiry or mi- neralogy were in any deeree cultivated. In both the analytic and fynthetic branches of chemifiry as well as mineralogy, many fubftances mutt have occurred, to which, in common language, no name was applied, yet the neceffity of denoting them by fome name was urgent. Here, then, a difliculty occurred, which fome fought to farmount by a name ardi- trarily impofed, others by names derived from fome real or fanciful relation of the given fubftance to fome ufe, object, perfon, or particular quality or circumftance. Thus, in che- mifiry, a/cobol appears to be a name arbitrarily impofed on highly rectified fpirit of wine or very fubtile powder *. Mer- curius vite denotes an antinonial preparation of great effi- cacy, as kermes mineral does one that refembles that fub- ftance in colour; Glauber’s fault, a particular fubftance firft formed by Glauber; Ep/om, a falt firft difcovered in the {fprings near that town, &c. So in mineralogy, quartz feems to be a name arbitrarily impofed; and /path, a name originating from the refemblance of the integrant lamelle to a blade; and /elenite, from fome fictitious refemblance to thé moon. The etymology of thefe names was, however, fooy- forgotten or not attended to, and confequently, fuch of thera * Some derive it from the Arabic daba/a exaruit. - 8 ax ‘ 174 Chemical and Mineralogical Nomenclature. a confifted of only one word, not evidently denoting fomeé falfe relation, might without inconvenience be admitted 5 but in procefs of time defcriptions were admitted inftead of nanies, and thefe often falfe or ‘abfurd, as fal mirabile, fal Secretum, arcanum duplicatum, arcanum corallinum, &c. The inconvenience and evident impropriety of many of thefe- defignations at laft attracted the attention of thofe eminent pbdlojaphic chemi{ts, Bergman and Morveau. Morveau, fo early as the year 1782, publithed an excellent memoir on this fubject in Rozier’s journal, and his fentiments met with the entire approbation of Bergman, The new denominations he fought to introduce, foon however gave way to the more exquifitely devifed fyftematic appellations grounded on the difcoveries of Lavoifier, and the total elimination of the pblo- giftic element formerly admitted. Thefe, in the formation of which Morveau alfo, in concurrence with a few of the moft eminent Parifian chemifts, bore a confiderable part, were fince admitted and recognifed by moft European che- mifts, and particularly in England, The exceptions that ap- peared to me reafonable to the general rules laid down by this highly refpectable affociation, or to fome of the terms they introduced, I thought of too little confequence to men- tion, knowing that the few antient denominations [ retained, and the flill fewer new ones I introduced, were perfectly in- telligible; nor fhould T attempt at prefent to vindicate them, had T not perceived they attracted the cenfure of many on whofe efteem I fet the higheft value. Thus circumftanced, 1 feel myfelf juftified in examining the general propriety of thofe rules and affumed principles from which I thought proper to deviate, and of the denominations which I reject. The firft principle laid down by M. Morveau is, ‘ that shrafes are not a name; that fubftances and chemical pro- duéts fhould. be de nated by names fit to indicate them on every occafion, without having recourfe to circumftances ; p- 373. Fo this principle I give my entire affent. Anather rule laid down, by M. Morveau is, ‘¢ that in choohng denominations we fhould prefer thofe which have - their roots in the dead languages more generally known, in order that the fenfe thould fuggell the name, and the name Chemical and Mineralogical Nomenclature. 178 the fenfe.”” It is for this reafon, combined with the firft, that I prefer fingle names, already underftood, and well known by all thofe that have attained any knowledge of chemittry, to new names derived from the Greek or new unknown barbarous Latin names. Hence I prefer the term hepar, denoting in all chemical authors a combination of fulphur to every bafis except a metallic, to the barbarous unknown Latin term /i/phuret; and, with refpeét to metals, I prefer the well known terms pyrifes and galena, to the newly-devifed /ulphuret of iron, or copper, or lead; the former has the advantage of denoting the particular fpecific combi- nations of fulphur with iron, copper, arfenic, or cobalt, and of excluding not only other fulphurated metals that do not give fire with fteel, as the vitreous filver ore, fulphurated anti- mony, or lead, cinnabar, blende, fulphurated bifmuth, &c.; but alfo fuch compounds even of copper and fulphur as do not give fire with fteel, as the vitreous copper ore and the gray copper ore, and the purple. On thefe, and many other confi- derations which will prefently be mentioned, I hope the ingen nious Mr. Mufhet will recall his with that I had modelled my Nomenclature on the principles of the French fchool. Phil. Mag. II. p. 156. » C. Faujas, though of that fchool, remarks that thefe ufual names (when otherwife faultlefs) cannot, with- out great inconvenience *, be changed for others either eru- dite or barbarous. Journal des Mines, XXXV. p. 894. Nor is his opinion in the leaft invalidated by the note of C. Coque- * This puts me in mind of fome Latin purifts who change known modern names into what they efteem purer Latin ones. Thus, inftead of cancellarius, they fav preefedtus jurts, and for which Lipfins Not. ad Lib. I. Politicorum cap. 9. juftly cenfures the hiftorian Paulus AZmilius. « Vetuftatis etiam nefcio quid affeétat in nominibus hominum, locorum, urbium immutandis et in veterem formam redigendis, fepe erudite, in- terdum vane, fed, ut ego judico, femper indecore, quorfum chariferizs, Gallorum cancellarius, qguadrigarius mihi fit? et ille ipfe cancellarius ap- pellatur prefedtus juris? et ubique Rex Tarraconenfis, qui nobis et ma- joribus fuit Arragoniz ? talia infinita funt axdad?er et ambitiofe innovata et cum fraude pariter ac cruce leCtoris.” The Greek and Roman hiforians were frequently guilty of the fame fault, which occafions at this day much perplexity. , bert, = 176. ~~ Chemical and Mineralogical Nomenclature. bert, who aflerts that the new are more exaét, fonorous, and fignificative; for any term is exact and fignificative when it denotes, without obfcurity or ambiguity, the thing figniiied ; and as to found, it may deferve attention In poetry, but furely, if not exceedingly uncouth, it deferves none in feience. He acknowledges that thefe alterations may caufe fome embarraflment_to the prefent race of men, but thinks that fucceeding generations will blefs thofe that introduced them. I think on the contrary that they will curfe them, for obliging them to learn both the new and the old denomina- tions under the penalty of not underftanding Stahl, Henckel, Margraf, Lemery, Geofroy, Duhamel, Macquer, Bergman, Scheele and many others of the bigheft merit. Can any one be fo arrogant as to pretend that thefe immortal authors can become unintelligible without prejudice to the feience? Is it poffible that, muficians fhould judge more fhrewdly than thofe who profefs to be philofophers? Yet thefe have rejected all the modern alterations of notation that have been propofed to them, though attended with fome advantages, from the fingle confideration that, if new modes were adopted, the in- imitable compofitions of the laft and prefent age would either foon become unintelligible, or the arduous tafk of learning both: methods of notation would be impofed on ail fucceeding generations. I am not however for the total exclufion of the term fulpburet; let it be employed to denote the compofition of fulphur with any bafis im genera/, whether alkaline, earthy, metallic, oleaginous, fpirituous or carbonaceous; im this moft extenfive fenfe the old nomenclature fupplied no term, and yet fome name was wanting; in this fenfe there- fore it may be retained. Another general maxim advanced by M. Morveawis, that. < the denomination of a chemical compound is neither clear nor exact except it expreffes by names conformable to their - nature the ingr edients that enter into that compound.” This maxim, unhappily too eafily adop ted by the French fchool, -tends to'the fubverfion of the received language of all fciences, and even of common life. By this rule we are to banith the name water, and inflead of it fubfitute its component ingredients Chemical and Mineralogical Nomenclature. 179 frigredients hydrogenated oxygen or oxyeenated hydrogen* ; and inftead of ice we are to fay decaloricated hydrogenated exygen, and for fleam, caloricated hydrogenated oxygen. In- ftead of common /oap we are to fay oleaginated joda, and for glafs, filicited alkali, &c. The French chemifts it is true retain the name /oap, but in contradiction with their own principles; for they furely cannot in this word difcover the radicals of its compofition. Nay, Lavoifier retains the old word nitre and falt petre con- jointly with that of mztrat of pota/b, (fee his Treatife of Che« miftry, vol. I. p. 79 and 232, French) and yet they difap- prove of my retaining a few of the antient denominations that were as well known to all chemifts as the names /oap or gis/s in the language of common life, fuch as Glauber, Ep- Jom, and Sylvian (rejecting only the term falt ufually tacked to them; but evidently fuperfluous) ; alfo felenite, gypfum, ’ borax and alum—thefe I retain for two reafons; firft, becaufe they exprefs their refpective objects by a fingle name, which appears to me a confiderable advantage, and fecondly, be- caufe thofe names continually occur in all treatifes of che- miftry publifhed before the year 17g0, and in many fince, and confequently ita be known by all who with to under- ftand them. Morveau and the French fchool in general reject the names of inventors, ‘ as having no conformity either generi¢ or in- dividual with things:” and for the fame reafon they fhould reject the names Alexandria and Conftantinople derived from the founders ; and in general, by the fame rule, all names of places fhould be changed for fuch as would exprefs their fituation. Is it not therefore evident, when the fignifi- cation of names is already fixed and generally known, that they fhould be retainedt, the inconvenience of rejefing them being far fuperior to any advantages propofed by the change ? Yet, ftrange to tell, they object to a few new names © whieh I inttoduced in mineralogy, though exaétly founded on ~ their own principles, and not attended with any inconve- * Fourcroy exprelsly fays water may be called oryd of hydrogen. Sce St. John’s Method of Nomenclature, p. 64- + 19 Roz. p. 374. Vor. VII, Aa mience, 178 Chémical and M. ineralogical Nomenclature. nience, as they denote objects not known by any denomi- nation previoufly affigned to them, and even poffefling pe- culiar properties of great importance. Thus they difapprove* of the name muricalcite, a name which I thought proper to beftow on fuch limeftones as contain a notable proportion of magnefia; and baryto-ca/cyte on fuch as contain a notable proportion of barytes; thefe ftones having been diftinguifhed by no name, and thefe new names being in conformity with the principles of the French fchool derived from and sasha on their component ingredients. Mr. Tennant has Gan fhown, in an important paper in the Philofophical Tranfactions for 1799, the evident neceffity of diftinéuifhing thefe muricalcites from common limeftones, with which they have always been confounded; and, from the deleterious properties which barytic lime water poffeffes, it is evident that the limeftones that contain any proportion of barytic earth cannot without danger (fometimes to humag life) be confounded with common limeftones. The ftone which the Germans without any inconvenience called apatite, approaching in our language too nearly the word appetite, I have called pho/phorite to mark its compofition; but as the phofphori ic acid has alfo been dete&ted, or at leaft fufpected, ; in compofition with argil, to diftinguith this compound from the former I call it phofpholite, aname better fuited to it than that of Valentia garnet, by which it was formerly de- noted—a change attended with no inconvenience, as the ftone itfelf was known in no part of Europe but Spain. To thefe denominations they object their monotonous termina- tions ; but thefe terminations are beti fuited to our language ; they do not recollect that the terminations in at, as nitrats, fulpbats, muriats, carbonats, phofphnis, a ovalats, 8c. &c. are equally monotonous in theirs. They think, or rather magifierially decide, that minerals fhould be denoted by the fame name as fimilar chemical compounds; a rule that might be admitted if fuch minerals were not previoufly gene - rally known by other fingle appellations, and if their com- pofition was perfectly fimilar to analogous chemical com- pounds. But in the firft place feveral minerals are already * Ann. Chym. XXKIIL p. 1 generally New Publication. t "9. generally known by peculiar proper denominations ; for inflance, cinnabar, furely a more convenient name than the drawling new name /ulphurated red oxyd of mercury : and in the next place they fhould confider that chemi- cal compounds being artificial productions may contain only thofe ingredients which their compound names im- port. But minerals whofe principal compofition is ana- logous, often contain other fubftances alfo, which the new chemical name would not exprefs, and would thus lead to important miftakes. Thus, for inftance, pho/phorite is commonly contaminated with filex, aérated lime, muriated lime and iron, and fometimes with manganefe and fluor ; whereas the analogous chemical compound on which the name phofphorated lime is properly impofed, is free from fuch contaminations. Subftances, therefore, fo different, fhould certainly be detinguifhed by different names, or at Jeaft the word natural or native mult be tacked to the name of the chemical compound; and though, with refpeét to fof- file metallic chemical compounds, this inconvenience may often be avoided by the addition of the word ore, yet here alfo the antient name often’ exprefles fome other inherent property; thus the term w7treous added to filver ore denotes not only the compofition, but alfo the eafy fufibility of that particular ore, [To be continued. ] NEW PUBLICATION. ‘New Obfervations concerning the Colours of thin tranfparent Bodies, fhowing thofe Phenomena to be Infle&ions of Light, &c. Cadell and Davies, Strand, 1800. Ts ESE Obfervations are by the author of two treatifes on the Origin of the Diverfity of Colours in the Rays of Light, and on the many-coloured Corone occafionally ap- pearing round the Sun and Moon; of which the Jeading principles have been flated in former Numbers of the Philo- fophical Magazine. Aaa The 389 New Publication, The object of the prefent treatife is to explain, in a mans ner confiftent with the leading principle formerly a advanced by the author, another important clafs of the phenomena of light and colours, Sir Ifaac Newton has reprefented the fmalleft parts of all natural bodies as tranfparent., He fuppofes thofe parts to be placed | ina medium, inferior in refractive power to them- felves. Thofe bodies are in his eftimation tranfparent, which confilt uniformly of the fmalleft parts and the fmalleft inter- mediate /paces; thofe are black, which have their integrant parts and the intervening fpaces of a fize fomewhat greater : fuch as are varioufly coloured confit of parts larger than thofe of either tranfparent or black bodies. The rays of light are, in his judgment, difpofed, by a natural indeftruc- tible quality, to be alternately tranfmitted through oppofing media, and reflected from them. By this quality, the tranf- miffions of light, its refractions and its reflections, appeared to him to be in all cafes regulated. The author of this ue, on the contrary, denies that the minuteft integrant particles of bodies are known to be tran{parent; that there exift within bodies any fuch refrac- tive media furrounding their parts as Newton has imagined ; that refraction and ot ek depend in any meafure on the arrangement and conformation of the parts of bodies, which Newton fuppofes; or that light is, by a mytterious natural quality, difpofed, by turns, to eafy tranfmiffion and to eafy reflection. He maintains, that all the phenomena which Newton has thus erroneoufly explained, are only fo many different cafes of the inflection of the particles of light by the attractions of bodies approaching them. According td him, as it fhould feem, light is never, in any circumftances, made to exhibit a diverfity of colours in its rays, otherwife than by the points or edges of approaching bodies exerting on it an attractive force fufficient to deftroy the natural confiftency of the whole, or at leaft a part, of the white ray. Refraction and reflection _ depend upon no peculiar qualities in light, but fmply on the attraction exercifed upon it, according to the general laws, by the other bodies with which, in various circumfiances, it comes Royal Society of London. 181 gomes in contact. He has made feveral ingenious experi- ments, which are in this treatife related in detail, and of | which the common refult feems forcibly to fuggeft the con- clufion which he thinks that he has eftablifhed. Much of the treatife is employed in pointing out the errors as to fact, and the fallacies of induction, which appear in the explana- tions by Sir Ifaac Newton, concerning this part of the {cience of optics. ~ To fay the truth, we find the faéts and reafonings in this effay fomewhat lefs fatisfactory than thofe in itg author’s two former eflays. It is probably the true principle which he has difcovered: but he does not, in this inftance, fee it clearly ; he only gropes at it, as it were, in the dark. Per- haps, however, not the author, but the dullnefs or impatience of the reviewer, may here be chiefly in blame. INTELLIGENCE, AND MISCELLANEOUS ARTICLES. LEARNED SOCIETIES. ROYAL SOCIETY OF LONDON. Orx Thurfday, Nov. 6, this learned and ufeful body held» their firft fitting fince the long vacation, when the commence- ment of Dr. Herfchel’s Second Part of his Inquiry refpecting Heat and Light was read. : On the 13th the Society occupied itfelf in reading the con- clufion of Dr. Herfchel’s paper, which contains a detail of a number of moft interefting experiments relative to the dif- ferent quantities of heat and light tranfmitted through yarious fubfances and through different coloured glaffes. From Dr. Herfchel’s experiments it appears that red glafs allows moft heat and leaft light to pafs through. One experiment is 182 Society of Antiquaries. is detailed, which, though he fays it was coarfely conducted, leads him to conclude that the focus of heat falls at the di- fiance of half an inch from that of light. One hundred and feventy experiments are recorded, from whence be concludes, that, as the Jaws of the motion of. light and heat are effen- tially different, there is the greatett ern to conclude ine they are not the fame fluid. The Croonian lecture, on the irritability of the nerves, by Everard Home, was begun reading the fame evening, and concluded at'the following mecting on the 20th. In this paper Mr. Home denies the hypathefis of a peculiar nervous fluid. SOCIETY OF ANTIQUARIES. ‘ Thurfday, Nov. 6, the Society met for the firft time fince the fummer vacation; on which evening, and on the 13th and goth, feveral very curious fragments of the paintings from the walls of St. Stephen’s chapel, reprefenting various fub- jets from the books of Job and Tobit, were exhibited ; and a very curious memoir on the fubject, by their learned Se- cretary, was read. The Prefident. addreffed the Society, and informed them that the Society had appointed a committee for the purpofe of fuperintending the execution of drawings which were making of all the curious remains that have been difcovered during the alterations that were carrying on at St. Stephen’s chapel, and which of Jate had excited fuch eeneral curiofity among all claffes of people, SOCIETY OF NATURAL HISTORY AT PARIS. C. Haiiy lately read before the Society a note on the eryf- tallifations of iron ore. The intended publication of a treatife on mineralogy by this author having induced him to revife, witb great care, what he had written on cryftallifation, he found that he had rectified only in part the incorreétnefs into which he had fallen in regard to the cryftalline forms of iron ore. He had already announced, in an extraét from his treatife, that the cryftals of volcanic iron were not fegments of the regular o) Chemifiry. fuccefidn ; ; but i take great care not to dry the wheat prez pared in this manner either i in an oven or ftove, left thé germ fhould be injured ; it muft not even be dry when fown, becaufe the Jime would detach itfelf, and mjure the fower. “© Tn regard to weevils, one of my neighbours has en-_ tirely cleared his houfe of them by a very eafy procefs. Int the month of June, his granaries and barns being entirely empty; he caufed a number of large ant-hills to be collected in bags, and difperfed them throughout the places infefted by t thefe infeéts. The ants immediately attacked the weevils and devoured them entirely, fo that not one of them was to be feen. Since that period none of thefe deftruétive in- ‘feéts have appeared on his premifes. “ The third fecret is very fimple: it confifts in wafhing the fmutty wheat in pure water till it no longer becomes black ; it mutt then be immerfed in boiling water and dried; fo that it can be ground. By this procefs as good bread may be obtained as that made from wheat which is free from fmut.” CHEMISTRY, Mr. Klaproth, of Berlin, having lately analyfed horteys fone, has found that the alumine contained in it Is united to an acid, the radical of which is the fame as that of the vegetable acids, but with different proportions of the earbor and hydrogen. The vegetable alkali has been found in different minerals. This new faét cannot therefore fail to prove interefting, and may lead to fome ufefi:l faéts refpecting the connettion be- tween the vegetable‘and mineral kingdoms, THE PHILOSOPHICAL MAGAZINE, DECEMBER 1800. I. A fbort View of the new Eleéiric Experiments performed by Dr. VAN Marum: = ‘T HE experiments which form the fubject of this articld Were performed with the large machine in the Teylerian mu- feeum at Haarlem, partly undertaken at the requeft of other philofophers, and defcribed in his laft work on electricity, éntitled Tweede Vervoly der Proefneemingen gedaan met Teeyler’s El, Mach. Haarlem 1795, 4to. It muft here be obferved that, fince the laft publication refpecting thefe ex- periments, great improvements have been made in the large thachine, and particularly in regard to the cufhions. Ac- cording to the old mode ¢f conftru€tion, the cufhions were preffed towards the glafs plates by means of two fcrews, im eonfequence of which it was not poflible to maintain an liniform prefftire on both fides. At prefent, however, an iniformity of preffure is obtained by two fteel {prings, which are applied with hinges to the end of two iron plates, and are kept together by one fingle ferew. As thefe fprings exercife their preffure on the centre of gravity of the cufhions, the preffure is uniformly the fame in every patt. Befides this improvement, the conductor is conftruéted in fuch a manner that, merely by turning, it can be employed fometimes for seceiving pofitive and fometimes negative electricity ; fo that both thefe kinds of electricity can be communicated to the gonduétor by changing its pofition. The collector is no Vou, VIL Ce ‘longer 194 New Ele&iric Experiments. longer furnifhed with fpikes, but is perfectly fmooth and fomewhat rounded, and has been lengthened from fix to tet inches. ze) the conductor alone experiments were made. 1. Refpecting the effect of eleétricity on the pulfe. Dr. Vinit Marum thought he had reafon to conclude from his former experiments, that electricity does not imcreafe the pulfe. But, as fome doubts arofe on this fubjeét, which were fupported by a paper of Meffrs. Von Trooftwyk and Deiman, he thought it might be of fome utility, in a fubjeét ef fo much importance to medical eleCtricity, to repeat the experiments according to the method of thefe philofophers. ¥or this purpofe cleven perfons were felected, and the expe- siment was repeated four times on each, .both with pofitive and negative electricity. Thete perfons were placed in a, toom sriiighs was at fuch a diftance from the machine that they could not hear the noife it made in turning; they were alfo infulated, and their pulfe was felt when the machine was in motion as well as when it was at reft (which laft eir- eumfiance was unknown to them), and the beats were told by a good obferver by means. of an excellent watch. In fome fingle cafes a few beats more were obferved, but on the whole rails was no particular increafe of any confequence. In general, however, there was great irregularity in the pulfe both during the time the perfons were electrified, and during the time the machine was at reft. 2. Refpeéting the increafe of infenfible perfpiration during the time the perfons were eleétrified. Dr. Van Marum em- ployed for this purpofe a very fenfible balance, one feale of which was infulated by means of a filk cord. -On this feale he placed a boy, eight vears of age, connected with the con- ductor, and brought the balance into equilibrrum. - He then examined the lofs of weight fuflaincd in half an hour before the boy was electrified, and found it amount to 280 grains 5 after which the machine was turned for half an hour, and the lofs at the end of that time amounted to 295 grains. By a fimilar experiment on another occafion, the lofs of weight before being elestrified was 330, and after being exantedl to electricity only 310. A girl of feven years-loft, before beiug 8, electrified, New Elcftric Experiments. 195 electrified, 180; and when electrified, 165 grains. A boy of eight years and a half loft unelectrified 430, and when electrified 290. Another of nine years, unelectrified 170, electrified 240. As the laft boy was exceeding!y quiet during the experiment, it was thought that the increafe was the confequence of eleéricity; on this account he was feverat times fubjected to the experiment, and the refults were in the unelectrified fiate 550; in the electric 399, 330 and 270, §50 and 420. In moft of the ‘experiments it appeared that there was rather a decreafe. 3. Refpeéting the irritability of the veffels of vegetables as the caufe of the afcent and defcent of fap —The relult of thefe experiments (viz. that from the cut ftems of different kinds of euphorbia, and other plants of the like nature, when expofed to ftrong fparks, no more {ap flows, as, by the itri- tability of the fibres being deftroyed, the veflels are rendered incapable of contra¢ting themfelves) is already well known. 4. Refpecting the exiftence of caloric in the electric matter. —Dr. Van Marum caufed a conductor of very thin brafs plate, five inches in diameter and eleven inches in length, to be conftructed with a cavity in the middle, in which he placed the bulb of a very fenfible thermometer, and fufpended it by filk firings near the conductor of the large machine, Neither by pofitive nor negative electricity, however, did their appear the leaft fien of the thermometer rifing, As Charcoal is an excellent conductor, he introduced the bulb of the thermometer into a cavity made in a piece of that fub- ftance; but ftill there was no fign of heat. From this it appears to him, that the figns of heat exhibited by electricity . may arife only from the great velocity with which the electric matter paffes through bodies, and that the fufion or combuf= tion of thefe bodies thence refulting may be occafioned by the friction thus produced. If a ftream of electric matter be conveyed to the bulb of a thermometer, it immediately rifes as Van Marum found, and often from 80 of Fahrenheit to 100 and more: but this experiment cannot be confidered as a proof of the exiftence of caloric in the electric matter, as Cavendifh found the electric current decompofes the at- mofpheric air, by which means fome caloric may be dif- Cc engaged 1096 New Eleéiric Experiments. engaged from it. To afcertain the truth of this conjeélure, Van Marum introduced a thermometer into a receiver be- tween two conductors, and, having exhaufted:part of the air, threw the ele&tric ftream on the bulb. The thermometer, however, rofe higher than in the open air, or to 120 degrees. The air in the receiver had been rarefied to 7,. That he might proceed with ftill greater certainty, he performed the experi- ment in oxygen gas and azotic gas rareficd in the fame de- gree; but in both cafes the thermometer rofe as much as before. Van Marum thought he fhould find another proof of the above opinion, by trying whether the eleétric matter was able to convert aqueous liquids into expanfible fluids ; for, as the elafticity of all fuch fluids is afcribed to their mix- ture with caloric, it feemed reafonable to conclude that calorie mutt exift wherever it is poffible to form expanfible fluids. Prieftley converted vitriolic ether, by means of eleétrie fparks, into inflammable gas, and obtained the like refult from oil of turpentine, {pirit of wine, and ammonia; but Dr. Van Marum, from thefe fubftances, obtained only very little gas, though his machine worked with much greater ftrength, and the fmall quantity which was obtained was again foon ab- forbed; and therefore he is of opinion that thefe gafes were tather expelled from the above fubftances by the bledhrieity, than prepared by it from their component parts. With ether and ammonia the quantity was a little larger; but, as thefe fubftances are exceedingly volatile, it could not be determined with certainty that the air was produced from the caloric of the electric matter; becaufe feveral liquids acquire their Jiquid form merely from the preflure of the atmofphere. Dr. Van Marum conceived the idea of making the experi- ments in vacuo with other fluids; becaufe in that cafe a fmall quantity of caloric might produce air. For this purpofe he employed the Torricellian vacuum, and, having put platina wires into feveral barometric tubes 4 inch in diameter, fufed the elafs around them at a lamp; he then inverted the tubes, and filled them with quickfilver in fuch a manner that 4 inch of each remained empty. Into, this empty fpace he frites duced the fluids, through which the electric {parks were to be conveyed ; then clofed the aperture, and again inverted the New Eleétric Experiments. 107 the tubes, that the fluid might afcend to the upper part of them, The exhaufted fpace left by the defcent of the mer- cury was fome inches in length, which appeared to him to be the moft advantageous. He then held the tubes in a ver- tical pofition in a veffel filled with mercury, and, placing a ball three inches in diameter on the wires at the top of the tubes, caufed ihe {parks from the conduétor to fall upon it. ‘The quickfilver in the tube was at the fame time connected with an infulated ball by means of a wire. The firft experiments were made with water, carefully pu- rified by boiling and by the air-pump. When the fparks ftruck the water through the vacuum, a confiderable quanuty of air feemed immediately to be produced, fo that in three minutes the mercury fell 1} inch. During the next five minutes the mercury fell only + of an inch, and the produc- tion of air then totally ceafed. After three days, the air which had been produced did not appear to be in the leat leffened. By another experiment of the like kind fuch a quantity of air was produced that in four minutes the mer- cury fell 3 inches 4 lines; but next day the air was leffened 1 inch 8 lines: the remainder retained its elafticity. In an experiment with alcohol, fuch an abundant quantity of air was produced that at firft the mercury fell 4 inch at each fpark. The production of air, however, decreafed in ‘proportion to the falling of the mercury, Two experiments of the fame kind gave more ftriking refalts, which in other refpects were fimilar to the former. In an experiment with cauftic ammonia, a column of air’ of 21 inches was produced in five minutes. Carbonat of ammonia gave a column of 18 inches, and camphor one of 6! inches in the fame time. The air produced by alcohol, when tried by a teft, was found to be pure inflammable air; that from camphor was found to be nearly as free from mix- ture: that, however, from both kinds of ammonia confifted of inflammable air mixed with azot. From this it appears that the eleétricity had feparated from each other the two component parts of the ammonia, hydrogen and azot. Dr. Van Marum imagined that the air produced from the water would confift alfo of oxygen and hydrogen, and on that ac- count ' 198 New Ele&ric Experiments. count tried to inflamte it, but without fuccefs: he condenfed the air he obtained till it almoft equalled in that refpeét at- mofpheric air, by immerfing the barometric tube in a wider one filled- with quickfilver; but inflammation did not take place until a little oxygen’ gas or atmofpheric air was intro- duced into it. Hence there was reafon to conclude that in- flammable air only was obtained from the water; and Dr. Van Marum acknowledges that it is difficult to explain what ‘came of the oxygen, the other component part of the water. Why, fays he, did it not form itfelf into oxygen gas with the caloric produced from the electric matter? But it is poffible, adds he, that this laft formation may be much more-difficult than the former; and, as it appeared from former experi- ments, that the electric {park decompofed oxygen gas, its oxygen may have paffed into the mercury, and the caloric may have efcaped: no figns of oxydation, however, were obterved on the mercury. All the kinds of air produced in this manner, that from water excepted, fully retained their elafticity; for even at the end of a year no leffening of them was obferved in the tubes, though kept under a preflure equal to that of the atmofphere. BleGricty; therefore, had effected in thefe experiments what had been formerly afcribed to caloric, and they feemed to prove that caloric exifts in the electric fluid. This much however is evident, that the electric fluid is not caloric itfelf, otherwife it muft heat thofe bodies through which it paffes ; but this is not the cafe: it appears alfo that in the electrie {parks it is combined with fome other fubftance which pre- vents it from communicating heat to bodies; and perhaps it is ina condition to do fo only when it is bape and be- comes free by the ele&tric matter being decompofed. Whether this other fubftance may not be the matter of fight, and whether during thefe experiments it paifed through the fides of the glafs, as no figns of any other matter on the glafs could be obferved, he could not decide. All the caloric difengaged was not, however, employed in the formation of jafammiable air: apart of it remained free, and heated the tubes, which within five minutes were at a temperature equal ‘40 250 degrees of I'ahrenheit, New Eleétric Experiments. 199 -g: Experiments made to determine whether it was poffible by eleGtric fparks to decompofe certain fubftances, or to change them in a fenfible manner,—As Dr. Van Marum, in the years 1785 and 1787, was able to decompofe nitrous and alkaline air by electric fparks, he wifhed to try the fame ex- periment with other fubftances. For this purpofe he em- ployed tubes of from 13 to 14 inches in length, and from 3 to 4 lines in diameter, inte the ends of which he introduced platina wires, and fufed the glafs around them. When the bodies to be examined required mercury, he filled the tubes with that fubftance, and introduced the bodies in fuch a manner that they floated about an inch over it. Above the bodies an inch of air was left, that the fparks might be con- yeyed to them with greater foree; for he bad been taught, by experience, that the fhocks are of the utmoft importance in experiments of this kind. However, he could not venture: here to employ any atmofpheric air; as this air, when de- compofed, gives nitrous acid, which would have mixed with the products obtained. The fitteft for this purpofe were vital air and azot. When he tried fuch fubftances,as attack mer- cury, the whole tubes were filled with the acid, and a platina wire was immerfed in it, fo that its upper end was an inch deep below the furface of the acid. This wire ferved inftead of the mercury as a conductor. Having introduced concentrated fulphuric acid into this laft apparatus, and conveyed to it, for a quarter of an hour, pofitive or negative fparks, no figns of any change were ob- ferved. The cafe was the fame when it was ftrongly heated or rarefied. Fuming nitrous acid gave, in the courfe of five minutes, a column of two inches of an aériform fluid; but in a quarter of an hour very little of it remained. It appears that the ca- loric of the eleétric matter had given the acid a gafeous form, but in itfelf no change could be perceived. Common nitrous acid gave a column of air of half an inch, which difappeared alfo when the eleétric matter ceafed to < # Common fuming muriatic acid exhibited the fame phe- momena as the former. The hyperoxygenated did not pro- duce . TOO New Eleé&tric Experiments. duce the leaft gas; it appeared that the caloric had no great tendency to unite itfelf with the oxygen. Be oe Carbonat of potath, or fufed falt of tartar, treated for a quarter of an hour over mercury with fparks, experienced no change. Concrete volatile alkali gave, between mercury and air, {fo much gas that the whole tube was filled with it. In this cafe the product was partly inflammable air and partly azot ; and it appears from thefe experiments that the formation of gas from both thefe component parts takes place as well im air as in vacuo. Tin@ure of lackmus did not become red, though expofed to {parks for half an hour, Profeflor Volta had requefted Dr. Van Marum to convey fparks to fufed faltpetre, in order to. try whether a decrepita= tion would take place. This, however, was not the cafe; and, after cooling, the faltpetre did not appear to be in the Yeaft alkalifed. As oxygen feparates' itfelf from horn-filver in the light of the fun, Priefiley firft propofed’ to Van Marum to expofe it to electricity; but no air could be obtained from it, either between the mercury and water, or in the Torricellian vacuum. Solutions of filver, copper, tron, lead, and quickfilver, in nitrous acid, and of gold and tin in aqua-regia, did not give the Jeaft precipitate im a tube’ furnifhed with a platina wire. With filver, lead, tin, and quickfilver, a little aériform matter was obferved, which however did not amount to above one- fourth of an inch, and was again immediately abforbed after the experiment. 6. Experiments which fhow that charcoal eontaims hy- drogen. . Thele experiments were made in confequenee of a vifit - from Landriani, on the roth of November 1788. Lavoifier’s combuftion of charcoal in oxygen gas had proved merely that carbonic acid is produced from charcoal and oxygen gas¢ but he as little proved as any of the antiphlogiflians, -by a direct experiment, that the charcoal or the carbonic acid, obtained by its combuftion im yital air, carried with it ne - water e _ : f a i 4 New EleG&ric Experiments. 201 water. The fixed air in this experiment was obtained by heat from a mixture of charcoal-duft well dried and freed from air, and red ‘precipitate expofed to heat. In order that the veffels might be freed from all moifture they were ex- pofed to a ftrong heat, and the quickfilver employed in the apparatus was boiled. In order to try whether the car- bonic acid obtained contained any water, {trong fparks were made to pafs through it; and the operator watched with great care to obferve whether water would be produced, and whether a long fpiral iron wire, employed in.the apparatus, would be oxydated. The fixed air itfelf occupied in the tube the length of nearly 4 inches 6% lines before being fubjeéted to eleGtricity, and the diameter of the tube was 7 lines. As foon as the fparks entered it, the operators faw with afto- nifhment that the column of air gradually increafed, and, after being eleétrified 16 minutes, the air in the tube occu- pied a {pace of 5 inches 1 line, which gave an increafe of al- moft .*, of the whole. They then wafhed the fixed air in cauftic alkali till its volume ceafed to be leffened, and the ‘efiduum in the tube amounted to two inches. The flame of a taper being then applied to the aperture, this eleétrified refiduum fifacned) and therefore fhowed that it confifted en- tirely of unmixed inflammable air. As this refult did not coincide with what we are taught by theory, it was refolved to repeat the experiments, and to employ double care in order to drive off the moifture. But as greater attention was now paid to what took place during the revival of the mercury, it was obferved that fome vapour was depofited in the upper part of the flafk employed for the experiment, as - well as in the tube through which the produced air was made to pafs. It was fuppofed on the firft view that this vapour was fublimated mercury; but it foon formed itfelf into fmall drops of water, which increafed in fize, fo that no doubt now remained refpeéting the production of water. The re- duétion was then fufpended, and the whole apparatus was heated and dried as well as poflible; but, on continuing the experiment, the drops again appeared. Now, as it was im- poffible that this water could arife from the moifture of the veffels, it feems proved to Van Maruin that carbon not only Vor. VIL. Dd eontains 202, Chemical and Mineralogical Nomenclature. contains the bafe of carbonic acid, but that alfo of hydrogen gas. But even if this experiment had proved the exiftence of hydrogen in charcoal, it would not follow that the inflam- mable air thence refulting effects the redution of metallic oxyds in the way audéstiood by the Stahlians ; it would fhow nothing more than that charcoal is not a fimple fubftance *; for, if it were fo, it would not produce water, but would thie join the the oxyd and reduce it. [ To be continued. | If. Of: Chemical and Mineralogical Nomenclature. By Ricuarp Kirwan, LL.D. F.R.S. and P.R.LA. [Concluded from Page 179. ] Neha inconvenience arifing from denon aiming to exprefs the compofition of the objects on which they are beftowed, is, that they often cannot exprefs the pro- portion of the compounding ingredients without confiderable embarrafiment; this proportion neverthelefs is a circumftance often of great importance, as it induces an important differ- ence in their properties, and the embarrafimentis greater when the compounding ingredients are numerous. To obviate the firft, in one particular inftance, the French fchool have very properly afligned different names to compounds holding dif- ferent proportions of oxygen and poffeffing different properties in virtue of that difference of proportion, as acids and oxides; but feveral of the vegetable acids differ from each other only in the proportion of ingredients, which cannot, even if fully known, beexpreffed in detail on every occafion. So, to cb- tain a diftinct knowledge of the various combinations of ful- pbur, or fulphur and hydrogen, with different bafes, is of the utmoft confequence to any one that wilhes to obtain any infight into the phenomena prefented by mineral waters during their analyfis, or of the nature of other fulphurated compounds.: on this obfcure and intricate inyeftigation moft * Tt is wellknown that charcoal retains water with great obftinacy and it is extremely probable that, in fpite of the care ufed in this experi- ment, fome of that liquid had been deft in the charcoal employed. . Ben ti ne certainly -s r “ ' pl a SE NR ces Chemical and Mineralogical Nomenclature. 203: certainly the eminent abilities of Fourcroy, and the confum-- mate {kill and fagacity of Berthollet and his affociate Welter, have thrown the cleareft light; yet I muft own that the terms employed by the two laft to denote the different com- pounds appear to me very perplexing, though the beft that could be chofen on the principles of the new nomenclature *. I flatter myfelf, therefore, that a fhort explanation of them, and of the names I would with to fubftitate in their room, will not be unacceptable nor out of place on this occafion. Sulpbure, Sulphuret of the Englifb. By this the French underftand the compound of /u/phur Jingly with any bafes except hydrogen : thefe compounds I call bepars if unmetallic, but if metallic I apply their antient names. va 2 Hydrogene Sulphur2, Sulpburated Hydrogen. This complex denomination expreffes the union of fulphur with hydrogen. I call it by its antient name, epatic air. Souffre Hydrogené. This term expreffes the union of fulphur with hepatic air. The fulpbur abounds, and it does not form a permanent air, but aJumes an oily form. Englifh neologifis would, I pre- fume, ‘have called it hydrogenated Julphur: itis plain that this name does not exprefs all the ingredients, for it is to hepatic air, and not merely to hydrogen, that the fulphur is united; I call it therefore bepaticated fulpbur. t Hydro Sulphure. Hepatic air is capable of uniting to various bafes, and even , precipitates fulphur from them if previoufly united to them ; on thefe compounds Berthollet beftows the above denomina- tion. The inglifh, I fuppofe, would call them Aydro/ulphu- rets; I call them bepatules. us Sulphure Hydrogené. This denotes the union of hepaticated fulphur (uffre hy- drogené) with any bafis: the Englith, I fuppofe, would call ® See Ann, Chem. XXV, p-230: and New Rox. Jour. III. p. 436- Dda thefe 204 Cherrical and Mineralogical Nomenclature. thefe compounds hydrogenated fulphurets: this appellation does not exprefs the compofition. I eniploy the term hepa- ticated to exprefs this compofition. Berthollet has difco- vered that fixed alkaline hepars, when diffolved, or even -moift, are always in this fiate, and confequently, that an alkaline hepar cannot exift but in a dry ftate. In the cafe before us, we fee the confufion and perplexity oceafioned by a ftriét adherence to the rule recommended by Lavoifier *, that a conformity or connection fhould be main- tained between the names of a bafis and its compounds: in fome cafes it is highly proper, andhence the different de- grees of oxygenation of cértain acids are very properly indi- cated by a flight alteration of the termination of the name of each, as /ulphureous and /ulpburic; but thefe names indicate only extreme fiates, the firft only the fmalleft degree of oxy- genation conftituting an acid, and the laft the ftate of perfec? faturation: now, this fame acid commonly occurs in neither of thefe fates, but in a ftate participating more or lefs of both ; thefe names, therefore, applied to it when thus circum- ftanced are falfe; and as in this intermediate ftate it has al- ways been known by the name of vitriolic acid, I think this name fhould ftill be retained. ‘Nay, the fulphureous acid is itfelf capable of two very different ftates, as may be feen in the 6th volume of De Machy’s edition of Junker, p. 143. So the term niértc is very proper to denote the full faturation of the nitrous bafis with oxygen. But the term zitrous, em- ployed to denote the fmalleft degree of oxygenation neceflary to convert this bafis into an acid, is Improper, as it has ever- more conveyed a different idea. Hence I exprefs this. loweft extreme of oxygenation by the term mephito nitrous, as the radical primary bafis may be called mepbite, or mephitie air, - inftead of the new coined name azet. And the term mtrous acid may fill denote, as it has evermore done, the mean ftate of oxygenation ; that indeed in which it is ufually found, and for which the French fchool have no name but that of one or other of the extreme flates, which muft therefore be falfely applied. The term efznitrous air, introduced by the learned and ingenious Dickfon, may be ufed to denote what Doétor * Lavoier, p. 72 and 73. ‘ Prieftley Chemical avid Mineralogical Nomenclature. 205 Prieftley called depblogifficated nitrous air, at leaft until its nature is better developed. It is in vain that the authority of Bergman is invoked to countenance the fuppreflion of the antient names of Glauber, Epfom, &c. rejecting only the oftentatious additions made to fome of them, as fal admirabile Glaubert, &c. 4 Bergm, p: 257. Itis true he affirms that the bef? names are fuch as indicate the compofition, or fome effential property; but of this fort he gives no example, nor rejects any old names merely on this account: on the contrary, where expreffive names cannot eafily be had, he tells us it is better to apply fome that convey no determinate expreflion, p. 259; and this is often the cafe where different proportions or numerous ingredients are to be denoted. Hence I am far from rejecting, but on the contrary ap- plaud the ingenuity of the inventors of the terminations of at and ite to denote the different proportions of oxygen in the acids contained in different compounds, as /ulphats, ful- phites, nitrats and nitrites, &c. as fuch general names were undoubtedly wanting, and the old fchool afforded none. But the welcome admiffion of thele does not require nor imply the difmiffal of fuch of the old as were faultlefs, and enfran- chifed by prefcription. A highly valued friend fuggefted to me, that the ufe of the old names was a departure from the fyftem on which the new denominations were founded. I replied, that fyftems were the creatures of convenience, and fhould be adhered to only as far as they promoted it; nitre, epfom, borax, &c. are much fhorter (and equally well known) than nitrated pot ath or fulphat of magnefia; and Lavoifier himfelf preferves the name borax; he might as well have preferved that of epfom. The fifth rule (very properly) laid down by Morveau with refpe& to names is, that they fhould be adapted to the genius of the language ; confequently, if old names be retained, they fhould be employed in the true ufual fenfe of their own fig- niftcation in that language, and neither extended beyond it nor reftricted within narrower bounds: on this ground I re- ject the term: pota/h, employed to denote the vegetable fixed ‘ alkali 206 Chemical and Mineralogical Nomenclature. alkali in its pureft fate; for that name, both in Englifh and French, has always denoted an impure alkali; but the pureft alkali of this fort, having bee formerly denoted by the name of falt of tartar, a name certainly improper, I fubftitute in its room the unexceptionable name fartarin, which, by its aflinity to the former, eafily fuggelts its fignification, and is moreover attended with a {mooth flowing adjective, tartari- nated, which is often wanting. For the fame reafon I reject the name ammonia to exprefs the volatile alkali, as the name ammoniac has always been employed to exprefs the combina- tion of avolatile alkali with an acid, and, if no particular acid was exprefled, the muriatic was underftood: inftead of vola- tile alkali, which is a compound denomination, I fubftitute volalkali, whofe fignification cannot be miftaken. Its ad- jective is not, indeed, quite fo happy : inftead, then, of volal- halifed, 1 ufe the word fuliginated, which eafily indicates the fame idea. Thefe are the only new chemical names I employ. The term oxide is alfo unfuited to our Janguage, in which it naturally exprefles the Aide of an ox. In pronunciation they cannot be diftinguifhed ; in its ftead I would ufe ovat or ovidat, and inftead of owided 1 would fubftitute oxidated. The application of either of thefe terms to metallic fubftances in an oxidated ftate is generally fuperfluous, as fuch fubftances are already denoted, and known under the name of metallic calees. Guyton* has lately proved that diamonds are the pureft carbon; yet furely even the French fchool will not at- tempt to fupprefs that well-known name, and exchange it for carbon. Neither, I fuppofe, will they call charcoal an oxide of carbon, though proved to contain fome portion of axygen; and for the fame reafon I {hall not exchange the well-known term plumbago for that of carburet of iron, though with re- fpeét to fimilar compounds of other metals the term carburet fhould be employed. This fyftem of conciliation the French fchool rejects with * Tt is with much regret and reluétance I mention this gentleman under this new name, as he was generally known, and gained immortal fame, under that of Morveau; hence I ihali fill ufe this in quoting his former works, difdain, he =e Chemical and Mineralogical Nomenclature. 207 difdain. Guyton tells us, “ it is fo much more difficult to conceive, as it is an evident facrifice of principles to habits *;”” as if the ground of their fyftem of nomenclature were univer- fally allowed, and afforded rules fo {trict and general as to enjoy the fingular privilege of admitting no exception! as if there was no fuch thing as principles of convenience, or, if there were fuch principles, that they were to be facrificed to mere fpeculative truths (if truths) of much lefs importance : a traly harfh, intolerant, and defpotic maxim! as ill calcu- lated to point out the moft advantageous road to {cience, as the maxim that a ftraight line fhould always be followed, would be to infure us the beft road to the fummit of a mountain, though prefenting in that direction a feries of feabrous and abrupt precipices; and hence departed from by Lavoifier himfelf, as we have feen in the inftances of /alipetre and dorax, and indeed by the whole French {chool in the inftances of cater and diamond, as already mentioned: for common fenfe, in fome inftance or other, feldom fails of af- ferting its rights: yét Lavoifier tells us he was cenfured (by fome chemical higots) for this condefcenfion. The principles of religion and juftice are the ouly that can in no poflible cafe yield to conveniency. Among many jult reflections that occur in the preface to Lavoifier’s celebrated elementary treatife of chemiltry, there are fome connected with this fubject that appear to me not quite correét. Thus, p. x. (of the original) he tells us, “ that the only way of avoiding thefe errors (unfounded hypothefes) is to fupprefs reafoning, or at leaft to fimplity it as much as poflible, as it proceeds from us, and can alone lead us aliray; to try it always by the teft of experiment, to preferve only the facts, which are the data given by nature, and which cannot deceive us; to feek for truth only in the natural concatenation of experiments and obfervations, as mathematicians arrive at the folution of a problem by the fimple arrangement of the data, &c.’” From this paragraph we might be led to conclude that all reafoning fhould be ba- nifhed from chemical inveftigation, or, at leaft, that only the fimpleft fhould be admitted; yet it may eafily be fhown that * Ann. Chem. XXYV. p. 207. the 208 Chemical and Mineralogical Nomentlature. the moft fignal inftances of fuccefsful chemical inveftigation | in the obfcurett fubjeéts, and the happieft difplay of chemical Tagacity, are the refults of very complicated reafoning. Such is Berthollet’s theory of aqua regia, Berthollet and Welter’s obfervations on hepatic air, Fourcroy’s on hepatic waters, Vauquelin’s theory of the mutual decompofition of nitrous air and the folution of vitriol of iron*, moft of Scheele’s and many of Klaproth’s analyfes, and a few others. The juft arrangement to which mathematicians owe the eafy folution of their problems, is itfelf the refult of profound reafoning, as is evident in the formation of equations. But the modes of reafoning employed in the folutions of mathe- matical and chemical problems cannot properly be compared, the former being founded on the relation of identity or equa- lity, and the latter on that of caufe and effe&. Page vi. he tells us, “ it 1s the feries of faéts that confti- tutes feience.”” I fhould rather fay, it was a knowledge of the relation that fubfifts between the faéts that occur; but neither the facts themfelves' can often be difcovered without much fubtile reafoning, nor can they be marfhalled im a lu- minous feries without difcovering the reciprocal relations of the component ingredients of compound fubftances to each other; a difcovery ‘which often requires an elaborate train of reafoning. Laftly, both he and Morveau tell us that the memory of learners is fingularly relieved by compound denominations. exprefling the component ingredients of each compound. In reply to which, I fay, that the fcience is not to be charged with a Sabine train of words merely to gratify the indo- lence of beginners. Are we then, on every occafion, to fub- ‘ftitute the definition of words for the words themfelves? Are Wwe, in imitation of the Germans, to fay a band/boe inftead of, a glove? Helvetius has long fince remarked, that every man of common underftanding poffeffes {ufficient power of memory * All foreign chemifts are infinitely obliged to him for giving the old denominations of weights and meafures inftead of centimetres, &c. Che- miftry aims at enlightening the world, and not Freachmen alone; it fiould therefore fpeak a language univerfally underftood, and flake off the yoke of national pedantry. to BUS etek ates taen ee Ee Chentical and Mineralogical Nomenclature. 20g to retain the fignification of moft words in his own, and often of thofe of feveral other languages: chemiftry and mineralogy together fearcely prefent two handred appertaining to them alone; neither the fciences of aftronomy, law; or medicine; afford fewer. The fathionable rage of coining new words from the Greek, without any neceffily, has been particularly barieful to mine- falogy, infomuch that foreigners, though well acquainted with the received terminology, cannot, without being verfed in that language, underftand the meaning of the new-fangled terms lately introduced. It is well known that the mineralogical knowledge of all Europe is chiefly derived from’ the Germans and Swedes, whofe nomenclature is in moft inftances the fame, and where any ambiguity has arifen it has been re- fnoved by the exertions of Werner. His nomenclature, where not too difcordant with the language, or at open va- fiance with the received technical names-of other countries, fhould therefore, for the fake of precifion and uniformity, be univerfally preferved. Abbé Haiiy, who is now preparing a treatife of minera- logy, of which the higheft expe¢tations are juftly entertained, fince, in addition to his own fuperior intelligence and pro- found phyfical knowledge, he is affifted with the chemical abilities of Guyton, Vauquelin, Defcotilles, and many others, and the extenfive refearches of Dolomieu, feems convinced of the propriety of retaining the received terminology, at leaft for the prefent, with the limitations and reftrittions above mentioned ; for, in his prefatory difeourfe, Journal des Mines, XXVII. p. 224, he tells us, ‘ that with refpe& to thinerals of the firft clafs (that is, confifting of mere earths), he left them thofe names which they had hitherto borne, and did not take the liberty of impofing new ones, except in cafes of neceflity, as where a new fpecies occurred, either formerly unknown, or confounded with one of a different nature. We have altered fuch names only as were intolerably ambiguous.” Yet after this declaration we find the following new-coined names : Telefia, for oriental rubies, fapphires, and topazes. Thus fapphire is called blue telefia, &c.—Cymophane; tor the chry- Vou, VII, Ke foberil EB Ce) Chemical and M ineralogical Nomenclature, ° foberil. of Werner.— Amphibole for cryftallifed hornblende. Pyroxene, alfo cryftallifed hornblende; at leaft I have reafon to think fo, for of the eleven external characters of both, given by La Metherie, there is only one in which they ab- folutely differ, that is, the eleCtrical.—Stawrotide for ftauro- lite, the name very properly impofed by La Metherie inftead of the compound name it bore before.—Awinite I believe to be only a variety of thumerftein.— Aéinote for aétinolite, the termination /z/e moft properly denoting a ftone.—Tballite for delphinite, the name already given it by Sauffure.—Idocra/e feems, as I conjecture (feeing no exact account of it), a va- riety of olivin. I pafs over feveral new names, as ewcla/e, dioptafe, cha- bafie, &c. as they may poffibly denote new fpecies, which I. with were fettled in conjunétion with Berthout or Van Buch, or fome of the Wernerian fchool. Yet even thefe denomi- nations, we are told, are only provifional, being hereafter to be altered as analyfes may require. I muft here add, by way of note, that C. Guyton, in re- viewing the firft volume of my Mineralogy, Ann. Chem. p. 105 and 106, has fallen into two miftakes, which I am perfuaded his candour will prompt him to acknowledge. The firft is, in flating that my experiments on the fufibility of dif- ferent ftones and earths were made in limeftone veffels, whereas they were in Heffian crucibles. The fecond is, in fiating the alleged infufibility of barytic earth and lime as the refult of my experiments, whereas I exprefsly quoted Lavoifier, having myfelf made no experiments on fuch mix- tures. (See Mem. Par. 1783, p. 599 and 600.) Other writers have frequently imputed to me miftakes of Bergman, though I exprefsly quoted him. Ill, A toe CT I. A brief Examination of the received Doétrines refpefting Heat or Caloric. By ALEXANDER TitLtocnw. Read before the Afkefian Society, December 1799. [Ccn-luded from Page 126. ] I SHALL now endeavour to prove that the pofition which maintains that “ heat, when in chemical union in bodies, cannot be made to manifeft itfelf but by the aGtion of fome new chemical affinity, does not hold univerfally, and there- fore may fairly be queftioned. Gafes, as every one knows, are formed by the folution of certain bafes in caloric. (Whether light be alfo an ingre- dient, or whether light be a modification of heat, or vice verfa, affects not the prefent argument.) The bafe or bafes, and the caloric, are chemically united, and therefore the ca- loric, according to the received doétrine, is /atent in the gas ; it is not cognifable by any external fign or organ of fenfe. 1 fhall not ftop to infift here upon the large increafe of volume acquired by the bafe fo diffolved—an increafe cognifable by our organs of vifion, and alfo tangible if the gas be received in a bladder, having already ufed a fimilar argument when fpeaking of the converfion of water into fteam—but proceed to obferve that this chemically combined caloric may be, par- tially at leaft, feparated from its bafe by means merely me= chanical. To fuppofe that any body can by mechanical force be re- duced into a fmaller compafs without any portion of its ori- ginal ingredients being thereby driven out of the mafs, would be an abfurdity. When we attempt to comprefs in a metallic veffel, of a known eapacity, a quantity of any gas equal im volume to twice that capacity, we, by the mechanical force employed with that view, abfolutely caufe a portion of one of the ingredients in the compofition of the gas to percolate through the materials of which the veffel is made (every fub- ftance in nature being pervious to heat). That. ingredient, that fubfance, is heat. The veffel in this cafe performs the office of a filter, fuffering the heat to pafs, but keeping back the other ingredients; and the quantity of heat pafled off in Ee2 this 212 Examination of the received Doflrines this cafe will be, if denominated by its volume, ewaétly of the bulk of the capacity of the veffel. If the veffel has been charged with a quantity of gas equal in bulk to three times its own capacity, the heat forced out will be equal in bulk to twice that capacity ; and fo of any other proportion of charge. Here, then, the fame effect takes place as when we con- fine {team ; the means are mechanical. in both; the heat is Squeezed out through the fides of the veffel by the force em- ployed, as water is fqueezed from a fpunge by preflure ap- plied to it. Was the water in the fpunge of a different na- ture before and after being expreffed, firft latent and then fenfible? If it would be abfurd to fay fo, why fhould we fup- pofe heat, when diflodged by fimilar means, to have under- gone.any change as to its nature, and to have been /atent before but /en/ible after? meaning thereby that its charaéter- iflic properties were different before and after the procefs. But have we any experiments that prove heat to be actually feparated by mechanical force from fubftances in which it is held to be /atent or in chemical union? When the condenfer of an air-cun, or any other proper veffel, is charged with more than one atmafphere, the materials, as the procefs goes on, become of a higher temperature than the furrounding bodies *, and heat is given off to them. This fhows that heat is expreffed from the contained air; and that, not being able to pafs freely, but forced to pafs more or lefs sass; according to the conducting power of the materials of the veffel, it is partially OLE ANODE in the materials, and then from them paffed off to furrounding bodies to reftore equili- brium according to the general law. If the wall of feparation, which forces the confined gas ta remain charged with afmaller quantity of heat than its con- fiitution would permit, but for the violence employed, be removed, what takes place? The gas infiantly feizes upon a portion of the caloric employed in maintaining the common temperature of the furrounding bodies, fitted to its own ca- pacity in its unreftraimed ftate, and in confequence refumes its orjginal yolume. This plamly appears to be the cafe, * See Dr, Darwin's paper on this fubjeét, Philofophical Tranfaétions for 1788. for Se ee ee, eee = refpeting Heat or Caloric. 213 "for any fubftance placed before the cock when it is opened is reduced in temperature. , Water fo placed will even be converted into ice, in confequence of a portion of its heat being violently feized upon by the gas, and more quickly taken into union with it than the privation experienced by the water is compenfated for by furrounding bodies in the paflage of caloric from them to reftore the equilibrium. Tam aware that it may be objected againft this experiment, indeed [ have heard the objection offered, that the friction of the forcing fyringe mutt excite or accumulate a confiderable portion of heat in the materials of which it is made; that the air, paffing inftantly from it into the condenfing ball, mutt neceffarily carry a portion of the heat along with it, having no intermediate bodies to come in contact with; and that therefore we have no evidence of heat being in this cafe expreffed from the compreffed air. Some force might-be allowed to this objeétion, if the air, when liberated, had no effect in reducing the temperature of the bodies expofed to it; but, as it has the power of taking from them a portion of their heat, and of reducing them below the common temperature, the objection falls to the ground: for, if the heat found to be accumulated in the materials of the condenfing ball was only a confequence of its containing air, made dot hy pafjing from a cylinder heated by friéiion, the air when liberated thould blow hot, and raife the temperaure of the bodies expofed to the ftream inftead of lowering it, as we find it does, The reafoning here is conclufive, but any perfon may alfo have the-evidence of a direct experiment. Expofe the ball of an air-gun, charged only with one atmo- {phere, to the heat of a common fire till the temperature of the ball be raifed a few degrees: the contained air will now be in a fituation to expand itfelf as foon as the valve is opened; for we know that the air has been heated by the ball. Expofe a thermometer to the aperture as the air efcapes, and the thermometer will indicate an increafed temperature. I have heard fome object to the inference from a eon- denfing ball being heated when charged, by queftioning the fact, for “ they haye often applied their hand to it without perceiving 214 Examination of the received Doftrines perceiving any fuch efe&.” It may be true that a ¢bick ball of fmall capacity will not give any fenfible indication of heat to a band applied to it, or even to a fluggith thermometer, which can only touch it in one point; for, where @ large mafs of materials is ready to receive the heat as it is exprefled from the air, the effeét may not be immediately obvious: it would be a long time before a large piece of ordnance could be made fenfibly hotter by applying the flame of a taper to it, but who would therefore deny that heat has paffed into the metal? Inftead of applying their hands to the condenfing ball, let them, as before ftated, place a thermometer in the ftream of the air when liberated, and they may receive com- plete evidence that the air demands a portion of caloric to bring it into equiltbrium with the furrounding bodies, which could not poffibly be the cafe if it had not previoufly fuffered fome privation. I fhall here briefly ftaté the refults of an experiment under- taken for the exprefs purpofe of afcertaining whether there had been any miftake in the facts reported by others refpect- ing the phenomena which accompany the compreffion of atr*, By means of a powerful fyringe A, Plate VI. fig. 1. (23 inches long and 2 infide diameter) made faft to one end of a table and to the floor of the room, the veffel B, con- ftructed of tinned copper, and made faft to the other end of the table, was charged with as much air as could be forced into it by the ftrength of one man. The temperature of the room was 59°. By the condenfation of the air, the thermo- meter C, introduced into a tube foldered into the veffel B {and open at its exterior extremity), was raifed feven de- grees. On expofing the bulb of another thermometer to the orifice of the cock D, which was then opened to dif- * For the execution of this experiment I am indebted to the London Phitofophical Society. Having ftated to that Society the faét, which E- wifhed to fee afcertained, the fubjeét was taken up with that alacrity and zeal which charatterifes all its proceedings. The apparatus was prepared by Mr. Varley, experimenter to that inttitution, and the experiment was faade in the prefence of the Society on the 18th of November 1799. charge a“ ye (’ « er ee ee ee ee ae refpetling Heat or Caloric. NG charge the air, that thermometer funk to nine degrees below the temperature of the room, or fixteen degrees below the point to which the other had been raifed by the expreffed heat. p It cannot be urged that in this experiment the air paffed immediately from the fyringe into the air-veffel, for it had to traverfe a tube interpofed between them of about four feet in length. Now, when it is confidered that the thermometer was in contact with the veflel B in only one minute point (for the tube in which it was inferted, and againft the fide of which the bulb refted, was more than three times the diameter of the bulb), and that the whole furface of B was above ‘50 {quare inches; and when it is alfo recollected that only a {mall portion of the effeét which the air iffuing from D was capable of producing could manifeft itfelf by means of the thermometer expofed to its action (as the thermometer was obliged to be kept at fome diftance to prevent its being broken by the difcharge of the air); fome idea, though not an adequate one, may be formed of the mafs of heat that muft have been thrown off from the whole furface of B in the procefs of charging that veffel *. The, * Subfequent to the delivery of the prefent paper to the Society, I received Mr. Mu thet’s interefting communication, which was afterwards inferted in the Philofophical Magazine for February 1800. It contains fome cus rious faéts which confirm and illuftrate the refults obtained from this ex- periment. Speaking of, the effects produced in the blaft-furnace by the - nature, ccmpreffion, and velocity of the air ufed, he obferyes that the com- preffion always occafions an increafe of temperature. On entering a blow- ing cylinder immediately after ftopping the engine, he finds the thermo- meter rife from 15% to 174° higher than the furrounding atmolphere. A thermometer held in the middle of the current of blaft was found to be reduced below the common temperature as much as the cylinder was ,raifed above it. In fome cafes, when the common temperature is about 54°, the blaft, as it iffues, will fink the thermometer 2° or 3° below the freezing point. He ftates another faét (fee alfo Mr, Rocbuck’s paper, Philofophical Magazine, Vol. VI. p. 324.), which completely does away every idea of any part of the effect being derived from frition, At fome iron works air-vaulty of from 60,000te 70,000 cubical feet in content are employed for the 416 - Examination of the received Dodtrines The refults obtained by the preceding experiment, though. only a fmall part of the effect could be appreciated, are fuffi- cient to afcertain the fa&t it was meant to eftablifh—that the do&trine which afferts heat to exift in a latent ftate im the atmofphere, and confequently to be not feparable from it without a chemical decompofition of the air, cannot be true, otherwife mechanical preffure and chemical decompofition mean the fame thing, which the advocates for the exiftence of heat in two diftin& ftates will hardly maintain. But the effe& would be much more ftriking, and the quantity of heat could even be comparatively eftimated by employing in the experiment fuch an apparatus as would enable us, in fome meafure, to intercept the heat as it pafles off from the wbole furface of the air-holder, and accumulate it in fome liquid. After thinking on various contrivances, with this view, @ method of conftructing fuch an apparatus occurred to me, a defcription of which, though I have not yet had time to carry it into execution, I beg leave to lay before the Society, Defcription of a Gafo-Calorimeter. The gas-holder A, fig. 2. of any capacity, fay a quart, con- ftruéted of tinned copper or any other metal, well foldered and riveted at the joinings, fhould be made double, or, in other words, the veflel, properly called the gas-holder, fhould be covered with another of the fame fhape made of thin metal, (as tinned iron) in fuch a manner that the two may not touch each other except at the lower part, where they are fitted on, and foldered faft to one common collar. By this ineans a fpace is left between the exterior furface of the gas- holder and the interior of the cover, to be-filled with a fluid for the purpofe which fhall immediately be ftated. ‘Phe in- terior veflel, which is to receive the gas, is open at the collar, and into this collar is fitted the cock B, made of glafs, be- caufe of the mercury to be employed in the experiments, and the purpofe of eyualifing the blaft. In thefe the increafe of temperature is more ferfisle than in the blowing cylinder, It takes place at a con- fiderable dillance from any mechanical fri€tion, and is therefore evidently produced by heat extricated from the air, for re[pefting Heat or Caloric. 217 for the convenience of feeing. The exterior veffel has an opening at the top C, into which is fitted a glafs tube CD. Through this tube (or before fixing the tube in its place) fill the fpace between the intérior and exterior veffel with any coloured liquid. If this double veffel be now filled wile and immerfed in, warm water, it is plain that the heat thus communicated to it will expand the coloured liquid contained between the in- terior and exterior furfaces, and make it rife to fuch a height in the glafs tube as fhall correfpond to the temperature of the water in which it is immerfed. By employing water of dif- ferent temperatures the different dégrees of heat, as afcer- tained by an accurate thermometer, may be marked upon the tube, or on a feale attached to it; and thus the veffel itfelf will, in faét, become a large hollow thermometer. To the lower end of the cock B attach another veffel EF, made of caft iron, furnifhed with two other cocks, a and 4, dnd conneéted with the- vertical tube FG, made of iron (a feries of gun barrels properly joihed to each other) or of glafs,. fecured by a cafe of wood, with cement interpofed between it and the glafs. Provide alfo a veffel of the fame capacity as the internal dimetifions of the gas-holder A. This veffel may be called the meafuire. From the above fhort defcription the conftruétion of the frafo-calorimeter, its ufe, and the way of operas with it, may be eafily conceived. Open the cocks @ and F, and pour mercury into the funnel at G. It will rife in E, driving the air before it, — which will efcape by the cock a. Having in this way filled, the veffel E with mercury up to the cock B, fhut the cock F, lace the meafure before mentioned below the cock 3, and | a that cock draw off one meafure of the mercury. It is obvious that by fo doing one meafure of air will at the fame time pafs into E through the cock a*. The cocks ad being now fhut, pour mercury into the tube FG to any convenient height; open the cock B, and then the cock F, The mea- * Any other gas may be introduced by conneéting this cock with a pneumatic apparatus. Vor. VIII. Ff , fure 218 Examination of the received Do&rines fure of air contained in the veffel E, having now no way t@ elcape, will, by the afcent of the mercury in E, be forced to pafs through the cock B into the gas-holder A. As foon as this is perceived, by the mercury fhowing itfelf 1 in the ghals cock B, fhut that cock. The gas-holder will thus beeome charged with two atmo fpheres, and that in a way fo expeditious as to allow but little time for the efcape and lofs of caloric, efpecially if the tube FG be of large diameter, and if the veffel E have been “ previoufly lined, and the veffel A covered over with fome bad conduétor of heat. The expreffed heat muft then pafs through the fides of the gafo-calorimeter, and there, exer- olfiny | its aGtion on the imterpofed thermometric fluid, mutt. pinise it afcend in the tube CD toa height proportioned © the heat thus communicated to the fluid * Another atmofphere may be ee ea by fhutting the cock F, opening @ and 4, and withdrawing another meafure of mercury as before, and then, by mercury poured iato GF, making the air to afcend into A, in the manner already de- feribed t. ‘Then note again the height to which the ther- mometric fluid rifes in CD; and fo of a fourth ora fifth atmofphere ; obferving that the height of the colamn of mer- cury in FG mutt always be proportioned to the number, of atmofpheres to be introduced. | The quantity of coloured fluid contained between the ex - terior and interior of the double veffel A, fhould be deter- mined by weighing the quantity introduced before gradu- ating the tube-CD. By this means it will be poffible to de- termine not merely how many degrees the heat exprefled from. tKe air raifes the fluid in the tube CD, but to how many ounces of the fluid it communicates that degree of tempera- ture. The weight of the materials of which the double veffel * As mercury is found to be a good conduétor of heat, it would be advifable to have a little oil, or fome other liquid, in the veffel E, before the Art introduction of the mercury. The vil would rife on its furface, and the interpofed ftratum rifimg with the mercury prevent its contaét with the air driven before it into the weffel A. 4 Or two or more atmofpheres may be foxced. up at ance, if the veffel E be made of fufficient capacity. is vefpecting Heat or Care 21 9 is made, fhould be alfo determined, that it may be known how many ounces or pounds of metal have alfo been heated to the fame degree. The ebaverte may be exhibited by. the fame apparatus by a different mode of operating. Detach the veffel A from the veffel E; invert it, and fill it with water, previoufly deprived of air by boiling or by the air-pump, and, having fhut the cock B, again invert it and join it to the veflel E. Fill the latter with mercury in the manmer that has been already de- feribed, and to the cock 4 adapt an iron tube, of 31 or 32 inches in length, to defeend vertically into a bafon of mer- eury. Ifthe cocks Bd be now opened, all the others being fut, mercury will defeend from E, through the tube fitted to 4, into the bafon in which the lower extremity of the tube is, and the water will pafs from A into E, leaving a vacuum in A. When the water has all paffed out of A, fhut the - cock B, If one atmofphere be now introduced into E,- and, the cocks,g and 4 being fhut, be compreffed into a half, a fourth, or a fifth of its original volume, by means of a proportionate column of mercury in the tube FG, heat will be expreffed from the air, which mult pafs off through the fides of the veffel E. Allow the apparatus to ftand for fome hours, till every thing conneéted with it has come to the common tem- perature. Then open the cock B, and the compreffed air, finding itfelf at liberty, will pafs up into the vacuum in A, where it will find {pace to expand itfelf to its natural volume, the quantity employed being one meafure, or, in other words, equal exaétly to the capacity of A. The mercury fhould alfo be allowed, by opening the cock F, to afcend till it reach the cock B. But the air, in refuming its original volume, will demand heat from the materials of hich” A is conftruéted, and from the thermometri¢ fluid of A, fafter than they can receive it from the atmofphere and contiguous bodies, efpecially if defended by a covering made of a bad conducting fubftance; and, as a neceffary con- fequence of this, the thermometric fluid will fall i the tube FG. If heat be thus deteéted paffing from or into air by mere Fifa preflure, 220 Examination of the received Doétrines preffure, or the contrary, and that it will we have already fufficient evidence, gf what kind is rhe heat? According to the received doétrine, it is neither /en/ible nor latent heat; for that heat which, united to oxygen and azot, forms atmo- {pheric air, is nof fenfible, and that which raifes the tempe- rature of bodies is mot latent: but this heat con/ftutes one- half, two-thirds, three-fourths, or four-fifths of atmo/pheric air (according to the number of atmoipheres comprefied into one), is a conftituent chemical ingredient of the atmofphere, and therefore Jatenl heat: and yet it raifes the temperature of other bodies, without being feparated from its union with the oxygen and azot by the exercife of any chemical affinity 3. therefore it is /enfible heat. The doétrine feems evidently to ftand oppofed to itfelf; or fhall we, to avoid this conclufion, fay that heat has a third. mode of exiftence, in which it may be called sENSIBLE- LATENT CALORIC! Abfurd as fuch a pofition might be, it would not be more fo than the doétrine of latent heat, taking that term in its common acceptation. ‘ I meant to have troubled the Society with a few further. remarks on this interefting fubjeét, but, having already en- croached further upon its time than J at firft intended, muff defer them for the prefent. To conclude: The doétrine of latent and fenfible heat ap- pears to me to have arifen from a want of due attention to the facts eftablithed by the veteran Black refpecting the dif- ferent capacities of bodies for heat. This emiment chemitft was the firft who propofed any thing rational on this fubject, and, when the beautiful fimplicity of the firkt principles which he eftablifhed is duly attended to, it appears wonderful to me that the fimple and permanent ftructure that might, have been reared upon them fhould have efcaped his faga- - cious obfervation. Having eftablifhed this incontrovertible / fa&, that different fubftances have different capacities for heat, this truth of itfelf necefiarily embraced another, which, though it could not poffibly efcape obfervation, has never been applied as it ought; namely, that in every chemical combination’ we effect we are altering the capacities of bodies for heat, and confequently deranging the equilibrium; for 9 4 the, a ee vefpelting Heat or Calorie. 225 the produ& differs in its capacity from the ingredients; and - the fame holds in decompofitions. Had this been properly attended to, it would have been found perfeétly fufficient, when taken along with that property by which heat tends to equilibrium, to explain the paffage of heat from fubftances to other fubftances, without ever once fuppofing the heat changed in its properties. Heat feems to a&t uniformly, and its effects depend always on its quantity (not kind) compared with the capacity of the body into which it enters: but it is continu- ally bandied about, as it were, by the conftant changes that are paffing upon bodies, by which their capacities for receiv- ing or holding it are altered; fo that it is in a conftant ftate of influx and efflux in bodies, and there is going on a con- ftant adjuftment, as it were, of the differences exifting among them, each requiring its own fhare of the common ftock, and giving off, receiving, or merely tranfmitting heat, according to circumftances. Bodies are continually undergoing change by the ation of heat. This is admitted on all hands. Is it neceflary then to look for a change i in the agent as well as the patient? In many refpeéts its ation, as we have before obferved, may be illuftrated by that of water. Different fub- ftances require different quantities of water to diffolve them ; and different fubftances require different quantities of heat to diffolve them. The property which different fubftances have to take in different quantities of water, may be called their capacity for water: but who ever talks of a certain quantity of water, when diffufed among any number of fubftances in proportion to their capacities, being /atent water ? or, when an interpofed hygrometer is affected by its paflage from one fukftance to another, of its being then /en/ible or free ? IV. Re- {eae at IV. Refleftions on the Theory of the Infinitefimal Calculus. Bu C. Carnot, Ex-Diredor of the French Republic, Miniflen of War, and Member of the National Inflitute, Paris 1797. Tranflated from the French, and illuftrated with Notes, by WitttAM Dickson, LL.D. To the Editor of the Philofophical Magazine. DEAR SIR, “AL HE mathematicak readers of your excellent publication need not be told of the importance of the infinitefimal calcu- lus, or of the affiftance it lends to every part of natural phi. lofophy, which falls not within the province of chemiftry. That calculus is praétically the fame with what we call the method of fluxions, except in name and notation. But the theories of the two methods are different; or, rather, thofe thearies are only different ways of illufirating one and the fame method under different names and fymbols. The flux- ionary theory, as delivered by its inventor, the incomparable. Newton, is confeffedly the moft accurate ; but the infinitefi- mal, otherwife called the differential theory, is generally thought, I know not for what reafon, to. be the moft eafily undertiood*. As it ts often advantageous to confider a fub- ject in different points of view, it was perhaps fortunate that M. Leibnitz claimed this difcovery, as-he was, of courfe, obliged to give it a new explanation; and thus we have the ideas of two of the moft acute men who ever exifted, on one of the moft extraordinary and fublime fpeculations which ever exercifed the human intellect. *« We truft,” faid the excellent apoftle, with infinitely more depth and propriety than appears at firft hght; ‘* we tw? that we have a geod con- fcience.” T[ traf that I underftand fomething of Newton’s fuxionary theory ; but I never could underfand the differential, as delivered by Leibnitz, in the Ada *ruditerum of Leipfic, for O&tober 1684, of which the' learned and ingenious Mr. Raphfoy has inferted a tranilation m his Hiftory of Fluxions. 1 believe moft impartial perfons, who “Ay to read that perplexed and perplexing piece, will be far from accufiug the hift torian of feverity, when he fays, that it contains ‘ far-fetched, fymbolifing, infignificant noveities,’ and that the notation is ‘ lefs apt and more labo. rious’ than that of the rear inventor. In : ’ ' Me | On the Theory of the Infinitefimal Calculus. 223 In the eflay, of which the following is a tranflation, the two theories are blended, and fo clearly explained, that thofe who think the pure fluxionary theory, even as facilitated by Mr. T. Simpfon, in his excellent “ Select Mathematical Exercifes,” ftill fomewhat dificult, may derive inftruétion from the author’s new and perfpicuous way of treating the fubje&. This theory, like other mathematical theories, being of an abftraét nature, may perhaps, after all, be more eafily conceived than exprefled. And, as happens in the practice of arithmetic, there may be perfons who are expert in the application of fluxions, but who have never been able fully to fatisfy themfelves as to the demonftrable validity of the theory. It fhould however be remembered, that all rational practice entirely depends on found theory ; and, to ufe the words of the great Maclaurin *, in proportion as the “ ge~ neral methods are valuable, it is important that they be efta- blithed above all exception; and fince they fave us fo much time and labour, we may allow the more for illuftrating the methous themfelves.” Thofe who, with a competent knowledge of geometry, al- gebra, and the conic fections, attentively perufe the following effay, will perhaps wonder why a fubject capable of fuch clear illuftration has been reprefented as fo difficult. The performance, though obvioufly not without faults, is, upon the whole, well worthy of the attention of fuch mathematicians as I have alluded to. The tranflation is as literal as the idioms of the two languages would bear; and I have annexed notes where I thought they would be ufeful. Though I de- eidédly prefer the ‘fluxionary notation, as well as theory, to the differential; yet in the feat I have retained, among the other fymbols of the original, all the d’s, and the dd’s, and the ddd’s and the dddd’s, to which the foreign mathemati- cians are fo partial, as being molt congenial ‘with the j inge- Dious author’s manner of confidering his fubject. Iam, Dear Sir, ; wis and refpectfully yours, ' W. OD. 4 * In the Iqtroduétion to his Treatife of Fluxions. * Adver- a24 Carnot on the Theory of Advertifement by the Author. : Some years ago; the author of the following refle&tions re= duced them to the form in which he now prefents them to the public. He is at prefent charged with bufinefs fo very important as to forbid his refuming his former ftudies ; but, as every circumftance announces that the mathematical fci- ences are about to foar to a new elevation, it is believed that fome advantage may refult from the publication of a memoir. in which the theory of the differential ‘calculus is difeuffed at large, and with precifion, and in which are united the different points of view in which that theory has been confidered. Subje of the following Differtation. x. No difeovery ever produced fo happy and fo fudden 2 revolution in the mathematical fciences as the infinitefimal analyfis; nor hath any improvement furnifhed us with fuch fimple and efficacious methods of arriving at a knowledge of the laws of nature. By decompofing, fo to fpeak, magnitudes into their conftituent elements, that analyfis feems, as it were, to have detected their internal {truéture and organifa- tion. But as all extremes elude the cognifance of the fenfes and the powers of the imagination, we have been able to form but an imperfeét idea of thofe elements, a fingular: kind of beings, which muft fometimes be treated as real quanti- ties, fometimes as abfolute nullities, and which feem, by their equivocal properties, to hold a middle place between magnitude and zero, between exiftence and nothing *. Happily this difficulty hath not interrupted the propre of the difecovery. There are certain primitive ideas which are always fomewhat clouded in the imagination, but whofe firft * T here fpeak in conformity with the vague ideas which we commonly entertain of infinitefimal quantities, when we have not been at the pains to examine their nature. Burt in truth, nothing can be more fimple than the notion of infinitefimals. Indeed, to fay that a quantity is infinitely fmall, is precifely to affirm, that it is the difference of two magnitudes which have for their limit the fame third magnitude, and nothing more is meant. The idea, then, of an infinitefimal quantity is not more dificult ~ to conceive than that of a limit; but it has befides, as is univerfally ae lowed, the advantage of leading to a much more fimple theory. confequences, Za roe See! al the Infinitefimal Calculus. 225 confequences, when once. fairly deduced, open a vatt field, which may be eafily traverfed, Such appears to be the idea of infinity, of which many geometricians, who perhaps were never able to fathom it, have made the moft happy ule *. Philofophers, however, unable to content;themfelves with fo vague an idea, have been wifhful to afcend to principles ; but in doing this, they foon found themfelyes divided in opinion, or rather in their manner of viewing the objects of their re- fearch, My defign in this performance is to reconcile thofe different points of view, to fhow my readers their relations, and to propofe new ones; and J fhall think myfelf well re- warded for my trouble, if I fhould fucceed in throwing fome degree of light on a fubject fo interefting. The Origin which the Infinitefimal hat Seah have had: 2. The difficulty frequently experienced in accurately eXx- prefting by equations the different conditions of a problem, and in refolying thofe equations, might have given birth to the firft ideas of the infinitefimal calculus. When, indeed, it is too dif- ficult to give an exact folution of a queftion, it is natural for the analy! {t to feek the means of approximating to it as nearly as poflible, by neglecting the quantities which embarrafs the combinations, if it be forefeen that fuch quantities; on ac- count of their fmall value, may be negle&ted, without pro- ducing any fenfible error in the refult of ‘the calculation. Thus, for example, as the difcovery of the properties. of curve lines is very difficult, they have been confidered as polygons * Certainly no geometrician, or metaphyfician either, was ever able to fathom quantities infimtely great or infinitel¥ fmall; I had almoft faid, even in the reftricted ferfe of the mathematicians, who define them to be quantities greater (or lefs}' than any aflignable quantities. Yet the meta- phyficians can prove- that fuch quantities. mult necefarily be received ameng the other evt/a rationis; and the mathematicians demonftrate many of their relative powers and properties; juft asthe chemifis, mutatis me tandis, exhibit to the fenfes many ef the properties of natural bodies, though they do not pretend to-have any idea whatever of their intimate effences. On the difficulty, or rather impoflibiliry, of conceiving, and the necellity ‘of admitting, Eternity and Infinity, fee Dr. Saniuel Clarke’s ex- cellent Demonftration of the Being and Atwributes of God, page 8, et fegg. soth edition. W, D. Vote. VIII. G ¢ of 226 Carnot on the Theory of of a very great number of fides. If, indeed, we conceive @ restilar polygon to be infcribed in a circle, it is evident that thofe figures, though they be always different, and can never become identical, yet refemble each other more and more as the fides of the polygon increafe in number. The circum- ferences of thofe figures, their furfaces, the folids formed by their revolutions about a given axis, the analogous lines drawn without and within them, the angles formed by thofe liries, &c. are, if not refpectively equal, at leaft the nearer to equality the more the number of fides augments. Hence, by fuppofing the number of fides to be very great, we may, without any fenfible error, attribute to the circumfcribing circle, the properties which we have difcovered to belong to the infcribed polygon. Farther, the fides of this polygon evidently diminifh in magnitude in proportion as their number is augmented; and confequently , if we fuppofe the polygon to be really compofed of a very great number of fides, we may alfo affirm that Hee of thofe fides is really very {mall. This being underftood, if, in the courfe of calculation, a cafe happen to occur in which many operations would be much fimplified by neglecting, for example, one of thofe fides, which is fmall in citipaeitel with a given line; that is, by caployie in the calculation that given line jinttead of a quantity equal to the fum of that given line and the little fide in quefiion, it is clear that this may be done without incon- venience; for the refulting error muft be extremely fmall, and it will not be worth while to inquire into its value. 3. For example, if it were propofed to draw a tangent to a given point M, of the circumference of the circle MBD (fie ig. 1). Let C be the centre of the circle, and DCB the axis. Sup- pofe the abfcifs DP=., the correfponding ordinate MP = y, and Jet TP reprefent the fubtangent required. In order to find that fubtangent, let us confider the circle as a polygon of a very great number of fides. Let MN be one of thofe fides, and te produced till it meet the axis. It will then rides be the tangent in quefiion, becaufe ic falls not within the polygon. Moreover, let fall the per-, pendicular SE Pea the Infinitefimal Calculus. 227 pendicular MO upon NQ, which is parallel to MP, awd put a for the radius of the circle. We fhall then evidently have . MO: NO:: TP: MP3 that is, 5 = , On the other hand, the equation of the curve for the point M being yy = 20x — xx*, the equation for the point Ni will be (y + NO)? = 2a (w« + MO) — (x + MO)’; and fubtraGting the former equation from the latter, and re- ducing, we have : MO’. * °2'y 4 NO”? apyg! = ager = OF but we before found MO _ TP. i ery ee eT therefore afk Ha Gp EO nat need oy (2y + NOY and multiplying by y, we have TP = ST eo If, then, MO and NO were known, we fhould have the. value of T'P, the fubtangent required. Now the quantities MO and NO are very f{mall, being each of them lefs than the fide MN, which, by the fuppofition, is itfelf very fmall. We may therefore, without any fenfible error, rejet thofe quan- tities, in comparifon with the quantities 2y and 27 — 2a, wherewith they are connected. The equation will then be reduced to TP = v= 7. the value of the fubtan-. 22 — 2X ama x gent fought. The Infinitefimal Calculus may, in this View, be confidered as a fimple Method of Approximation. 4. If this refult be not abfolutely exact, it is at leaft-evident that, in practice, it may pafs for fuch, becaufe the quantities MO and NO are extremely fall. But a perfon who has no idea of the do¢trine of infinites, will perhaps be furprifed to 2 be told that the equation TP = , does not barely make axsX a near approach to the truth, but that it is really and perfedtly « accurate, Of this, however, he may eafily fatisfy himfelf by * For, in the circle. 2a—a ty i: yi ae Gg2 invef- 228 Carnot on the Theory of inveftigating the value of TP, on the princi le of the tangent being perpendicular to the extremity of the radius 5 for i it is evident that the fimilar triangles, CPM, MPT, give CP: MP :: MP: 1D and therefore TP = att J : CP 5. As a fecond example, aes we are to find the furface of agiven circle. Let us ftill confider that curve as a regular polygon of a great number of fides. The area of any regular polygon is aa to the produét of its cireumference into shale the perpendicular let fall from the centre on one of its fides. The circle, therefore, being confidered as a regular polygon of a great nuniber of fides, its furface ought to be equal to the produét of its circumference (that is, the fum of very numerous fides) into half the radius; a propofition as exact as the other. “ 6: However vague and indeterminate the expreffions thy great and very /ma/l, or others of the fame nature, may ap- pear, we fee, by the two preceding examples, that they are not unufefully employed in mathematical combinations, and that the quantities fignified by thefe expreffions may afford much help in facilitating the folution of divers queftions which may be propofed. For, the notion of fuch quantities being once’ rightly underftood and admitted, all other curves, as well as the circle, may be confidered as polygons of a great number of fides; all furfaces may be divided into a great number of fillets or zones; all bodies may be refolved into corpulcles; and, in a word, all quantities may be decompofed into particles of the fame fpecies with themfelves. Hence arife new relations and combinations; and we may eafily judge, from the examples already adduced, of the refources in calculation, which the introduction of fuch elementary quantities muft afford, 7. But the advantages of admitting thefe quantities is fill more confiderable than could, at firlt fight, have been ex- pected. For we have feen, in the examples propofed, that » as before. what was confidered, at the outfet, as a fimple method of. approximation, conduéts us, at Jeaft in certain cafes, to re- fults perfectly accurate, It becomes interefting, therefore, ; to Lae ee re oe the Infinitefi mal Calculus. 229 to be able to.diftinguith the cafes in which. this accuracy takes place, and thus to convert this method of approxima- tion into a calculus perfectly exact and rigorous ; aud fuch is the object of the infinitefimal analyfis. 8. Let us firft fee, then, how it came to pafs that, in the equa- tion TP = 2 (2y + V@. found in article 3d, though we 2a— 2x — MO’ neglected MO and NO, the juftnefs,of the refult was not af- feted ; or rather, how the refult became exa¢t from the fup- Safes of thofe quantities, and why it was not exact before that fuppreffion. ' Now, the reafon of what happened in the folution of the above problem will eafily appear, on remarking that the hy- pothefis on which that folution is grounded, is falfe; it being abfolutely impoflible that a circle can be a ¢rue polygon, what- ever be the number of its fides; fo that there muft refult from that hypothefis an error of fome kind in the equation TP = ater + NO) But the refult TP = -—— being neverthe- 2a — 2x — MO a—x lefs exact, as was proved by the cclidensiton of the two tri- angles CPM, MPT, we found that M70 and NO might be. neglected i in the firft equation. Indeed thefe quantities oxght to be negleéted, in order to correét the calculus, and to at {troy the error which had arifen from the falfe hypothefis firft aflumed. The rejection of quantities of this nature is not barely allowable, but is abfolutely neceflary in fuch cafes, as being the only manner of expreffling accurately the condi- tions oF the problem. The Accuracy of fuch Refults is owing to-a Compen/fation of Errors. g. The accurate refult TP = = hasbeen obtained then, ' fe only in confequence of a compenfation of errors; and this compenfation may be rendered fiill more evident, by treating the example above given in a manner fomewhat different, namely, by confidering the circle as (what it really is) a true- curve, and not a polygon. For this purpofe, from the point R (fig. 1.) taken arbitra- 8 rily 230 Carnot on the Theory of rily at any diftance from the point M, draw the line RS pas rallel to MP, and, through the points R and M, draw the fecant RT’; then we thall evidently have T/P: MP:: MZ Zz : RZ, and therefore T'P, or TP + T/T = MPL, Now, if we imagine RS, moving parallel to itfelf, to son con- tinually to AZP, it is evident that the point 7” will, at. the fame time, more and mofe approach to the point 7; and con- fequently, that we may render the line 7’ Tas fmall as we pleafe, without affecting the proportion above eftablifhed. If, then, we neglect the quantity 7’ 7 in the equation juft found, there will indeed be an error in the refulting equation TP = MZ : : MP ee to which the former will now be reduced: but this error may be diminifhed as much as we pleafe, by making RS approach to MP as nearly as is neceflary; that is, the proportion of the two members of this Taft equation will differ as little as we pleafe, from the proportion of equality. MZ -' ay + RZ In hke manner we have —.|- = ——~—-—__.._ (See boas RZ 2@ —2n—MZ ( Article 3.) And this equation 1s perfeétly accurate, what- ever be the pofition of the point R; that is, whatever be the values of MZ and RZ, But, the nearer RS approaches to AIP, the fmaller will be the lines 17Z and RZ; and hence, if they be negleéted in the fecond member of that equation,, 4 : : ; MZ the error which will refult in the equation -,,- = ed ; RZ re ie will, as in the former cafe, be thereby rendered as fmall as’ we think proper. This being fo, without paying any regard to errors, Rehich T have it aly: ays in my power to dinntarth as much as I pleafe, ; “MZ T' treat the two equations TP = MP —_, and —_— 4 RZ? RZ _, as if both of them were perfeGtly accurate: fubfti- a ee : : MZ tuting, therefore, in the former the value of ——, expreffed RZ = 5 that is, TP = J a—x in the latter, Ihave 7P = 5 as ; before, This _ the Infinitefimal Calculus. 23%: This refult is perfectly juft, becaufe it is conformable to ‘that which was obtained by the comparifon of the triangles MZ CPM and MPT; and yet the equations TP = MP az _, MZ. MEY 2 Rr and Te py certainly both of them fa//z, For the diftance of RS from MP, was not fuppofed nothing, or even very fmall, but equal to a line arbitrarily aflumed. It follows, therefore, of neceflity, that a mutual compenfationm of errors took place in the comparifon of the two erroneous equations*, Why this Compenfation takes place. 10. Having fhown that there exift compenfating errors, whence they originated and how they are proved, I fhall next proceed to explain them, and to fearch for a mark by which it may be known that a compenfation takes place in calcula- tions fimilar to the preceding, and the means of producing fuch compenfation in particular cafes. * This ** compenfation of errors’’ the acute -Dr. Berkeley, Bithop of Cloyne, in The Analyf, publithed in 1734, laboured to magnify into a ferious objeétion againft the differential calculus; not ecenfidering that errors which we may make as little as we pleafe, will affeét the truth as litile as we pleafe. Thus 1°999999, &c. is not, in rigid ftriétnefs, equal to 2; but as, by annexing g's, the error may foon be rendered /zcompre- henfibly minute, no one can doubt that its wisimare ratio to 2, is a ratio of equality. Hence the word fu//r, applied by our ingenious author, in this paragraph and elfewhere, to differential equations, is abundantly too ftrong ; and, had he read The Analyft, he would certainly have.ufed a lefs excep. tionable term, fuch as incorreét, or inaccurate, or imperfré?, a word which in the fequel he takes in a fimilar fenfe. But fale (faux, fauffe) fignifies not minutenefs of error, but a total’ negation of truth. It is not always eafy, indeed, to find words exactly fuited to exprefs very abftraé ideas. The great Simpfon (Selec? Exercifes, p. 239.) admits that, had Newton ufed the word /imiting inftead of ultimate ratios, Dr. Berkeley might not have conjured up his “ Ghofts of departed Quantities.” Yet Mr. Simp- fon, and ail offer competent judges, allow that Newton, by reprefenting fiuxions not as in the :atio of the whole increments, but in the firft ratio of thofe increments confidered as nafcent, or in theic ultimate ratio con- fidered as evanefcent, has effectually anticipated every reafonable objec- - tion; and this, no doubt, the learned and ingenious bifhop would have confeiled, had he given himfelf time to digeft this doctrine, which is partly ‘wofolded in the prefent uact. W. D, For 432 Carnot on the Theory af For this purpofe, it will be fufficient to remark, that the ; : ; MZ MZ rors ] i f tf rez errors, included in the two equations 7’P = y RZ? and RZ = a oad may be rendered as fall as we pleafe; and the aX P fame thing would take place if there were any error in the 2 refulting equation TP = , and if that error depended aGa—wMX on the arbitrary diftance of the lines MP and RS, But no fuch error can exift in this laft equation; becaufe the point M, through which the tangent mutt pafs, is given, and not one of the quantities, 7'’P, a, x, or y, 1s arbitrary. Hence it follows, that the compenfation of errors, which takes place in the equations TP = y ee and ee s ae is indicated in the refult by the abfence of the quan- an-x tities AfZ and RZ, which caufed thofe errors. Confequent- ly, after having introduced thefe laft quantities into the cal- culation, to facilitate the expreflion of the conditions of the problem, and having treated them, in the equations expreffing thofe conditions, as nothing in comparifon of the propofed quantities, we have only to eliminate thofe quantities out of the equations, in order to free them from error, and to ob- tain an accurate refult. 11. The inventor of this method might therefore have been conducted to his difeovery by a very fimple train of reafon- ing. If, inftead of a propofed quantity,’ might he have faid, “ 1 fubftitute in my calculation a quantity which is not equal to it, fome error will certainly refult. But if the dif- ference of the quantities in queftion be arbitrary, and I have it in my power to render that difference as {mall as I pleafe, the error cannot be dangerous. I may even commit feveral fimilar errors at once, without incurring any inconvenience ;_ becaufe I have always in my own power the degree of precifion, which I choofe to give to my refults. Befides, it may happen that thofe errors will mutually compenfate cack other, and, if fo, my refults will become perfectly accurate.” But how is fuch a compenfation to be effected in all cafes? A little refleCtion wilk \ : 7 the Infinitefimal Calculus. 238 Will fugget an anfwer to this queftion. « In fact,” might the inventor continue, “ let me fuppofe for a moment that the defired compenfation has taken place, and let me inquire by what mark it ought to be indicated, in the conelafion of the calculation. Now it muft naturally happen, that when the quantities which occafion the errors difappear, the errors themfelves will: difappear at the fame time. For thofe quan-. tities (fuch as MZ and RZ) having, by the fuppofition, ar- bitrary values, ought no longer to exilt in formule, or re~ fults, which are not arbitrary, and which depend, not on the will of the calculator, but on the nature of the things whofe relation, exprefled by thofe refults, he propofed to inveftigate. The mark, then, which announces that the defired compen- fation has taken place, is the abfence of the arbitrary quan- tities which produced the errors ; and therefore I have nothing more to do, in order to effect that compenfation, than to eli- minate thofe arbitrary quantities.” 12. With a view to fix thofe ideas the more firmly in the mind, and to give to the principles thence derived’ the ne- ceflary degree of precifion and generality, I {hall remark, that the quantities which we have occafion to confider in the fub- ject before us, may be diftinguifhed into two claffes. The firft clafs confifts of quantities which are either given, orde- termined by the conditions of the problem, fuch as MC, MP, PT, MT. The fecond clafs is compofed of quantities, fuch as RS, RT’, ST’, which depend on the arbitrary pofition of the point R, and which, as the point R approaches to the point M, do refpectively approach their correfponding quan- tities in the firft clafs. Thus MP, for example, is the limit of RS, that is, the fixed term to which it continually ap- proaches, or, if you will, its laft or ultimate value. In like manner, A/T is the limit or ultimate value of RT’, and PT that of ST’. For the fame reafon, it is clear that the limits or ultimate values of AZZ, KZ, MR, T’'T, are, every one of them, 0. In fine, it is alfo evident that the w/timate ratio of RS to MP, (that is, the ultimate value of a) is the ratio of equality, and fuch is the ratio of RT’ to MT, of ST’ to PT, or, in a word, fuch is that of any other quantity to its limit. Vou, VIII. Ih . 13. To a94s Carnot on the Theory of 13. To enable us to extend thefe remarks to other pro~’ blems of the fame kind, let us now put the cafe, That any? fyftem whatever of quanuities is propofed, in order that the: relations which’ exift between them may be inveftigated *. 14. And firft, I fiail comprehend, under the name of afjigned quantities (quantilis defignées) not only all: the quantities propofed in the very enunciation of a problem, but alfo all thofe which depend on thofe quantities, that is, which are funétions of thofe quantities, and of mone elfe. * 15. On the other hand, I fhali give the names of un- afjigned, or auxiliary quantities, to all thofe which make no part of the fyftem of affigned quantities, and which confe- quently do not effentially enter into the calculation, but are introduced folely to facilitate the comparifon of propofed quantities. Thus, in the preceding example, MP, MC, MT, DP; &ce. are affigned quantities ; becaufe they depend only on the pofition of the point M, to which the tangent is to be drawn. “But RS, and all its dependent lines, MZ, RZ; TT, T’P, &c. are auxiliary quantities ; becaufe we fhould not have thought of drawing them, except their affiftance had been wanted in the folution of the queftion, the object of which is todifcover the proportion, or relation, of MP to MT. * [here fuppofe that, im any problem propofed, the relations which exift between fuch ov fuch propofed quantities has been’ previoufly difcovered, If, for example, the problem be, to find a curve which has a certain de- terminate property, I fuppofe that the relation between. an ordinate of that curve and the correfponding abfciffe is already known. In like manne, if it were required to draw a tangent to any indeterminate point of that curve, I begin by arbitrarily fixing on the point to which I wifh to draw the tangent, anc [ limit the problem to the inveftigation of the relation which fubiifts, for inftance, between the fubtangent and the abfciffe, or between the ordinate and the correfponding fubnormal at that peint. But if it fhould be afked how I apply the definition of snfx/zp to fuch queftions as thefe: Is matter divifidle ad infinitum? Is. the fpace in which all created’ leings exift infinite? T fay, if fuch queftions fhould be put to me, I fhould ici. that my definition is reftriéted' to mathematical infinity, and that it can only be applied co problems whofe objeét is the difcovery of the re- Jations which exif between different mathematica! quantities, and that the metaphyfical queftions juft ftatcd ean by nota eans be referred to the theory, af which I here ‘propofe'to eftablith the prig ciples. Hence the Tnfinitefimal Calculus. 935 ence ‘it evidently follows, that into all unaffigned quan- ‘tities there neceffarily enters fomething arbitrary ; for, if this -were not the cafe, their value would then be affigned, by the very conditions of the problem, and confequently they would wholly depend on propofed quantities; which is contrary to the fuppofition. 16. Since in the mathematics, two lines, two furfaces, two folids, in fhort two quantities of any kind whatever, are fappofed continually to approach each other by infenfible degrees; fo that their proportion, or the quotient reprefent- ing that proportion, differs lefs and lefs, and as little as we pleafe, from unity, we fay, that the laft, or ultimate ratio of thofe two quantities is a ratio of equality. 17. If one of the quantities be affigned, and ‘the other auxiliary, the firft is called the Zimit, or ultimate value of the fecond. Thus a limit is nothing elfe than an affigned quan- fity, to which an auxiliary quantity is fuppofed continually to approach, in fuch a manner that their difference may be rendered as {mall as we pleafe, and that their ultimate ratio may ‘be a ratio of equality. Thus auxiliary quantities alone can be properly faid to have limits; for afigned quantities, being fuppofed conftant and unchangeable, and to be themfelves the terms, or ulti- ~ mate values of auxiliary quantities, cannot, in ftriétnefs, be faid to have any limits ; unlefs we choofe to fay, that every affigned quantity is its own limit, a liberty of fpeech which cannot be refufed us; fince the ultimate value of any de- terminate quantity whatever can be nothing elfe than that quantity itfelf. 18. Hence, in general, we give the names of ultimate yalues and ultimate ratios of quantities, to the values and ratios which are, in fact, the laft, or ultimate, ones afliened to thofe quantities and their relations, by the law of conti- nuity, when each of them is fuppofed to approach, by con- tinued and infenfible degrees, to its correfponding afligned quantity. 19. We generally give the name of an Infinitely fmall quantity, to the difference between any auxiliary quantity whatever and its limit. Thus, for inftance, RZ, which is’ Hha2 the 236° Carnot on the Theory of the difference between RS and AZP, is what we call an in~ finitely {mall quantity. 20. On the other hand, we call every quantity Infinitely great, or fimply Infinite, which is equal to unity divided by” an ary {mall quantity : confequently the quantity ap TT is infinite, or infinitely great. But, fince MP is the limit, or ultimate value, of RS, it is evident that o is the ultimate value of RZ, or RS—IMP, and that 2 is the ultimate value of “5 21. Thus we may affirm, in general, that An infinitely Small quantity is a quantity whofe limit is 0; and on the contrary, that An infinitely g Brea, or fimply an Sah fC quan~ tity is a quantity whofe limit is ? 22. Under the name of ipo quantities, We com- prehend quantities which are infinite, or infinitely great, as well as thofe which are infinitely fmall. All other quantities are called jiite. 23. To fay, in conformity with common ufage, that In- finity is that which has no bounds, or is that which is without limit, or is that whofe limit does not exift, is a mode of expreffion which conveys a fimple idea of what is meant, and which is by no means deftitute of propriety ; be- caufe in fact, the limit of one kind of infinitefimal quantities is oO, and that of the other 2; and 0 and 3 are not real quan- tities *. 24. But, * This kind of notation, which is in general ufe, is very apt and figni- ficant, But we are under no neceffity of making o always reprefent ab/o- lute nothing. Weare at liberty, when our fubjeét requires it, to make o ftand for relative nothing, or that which may be confidered as nothing relatively to fome other quantity. Thus any very fmall fraétion “opoocococeor, (prefixing cyphers at pleafure) though not abfolutely . nothing, may be fafely confidered as nothing, relatively to, or compared with 1, and, @ fortiort, with any other whole number, and accordingly may be reprefented by o. And, if fo, SoosKNSGor? Or 100000000009 (annexing cyphers at pleafure) though by no means abfolutely infinite, may be accounted infinite relatively to, or any moderate given number, and accordingly may be reprefented by 2 a Thus the diameter of the earth ee fe eee ee eee a ee the Infinitefimal Caleulus, ‘ 237 24. But, from o and 2 being the limits of infinitefima] quantities, it by no means follows that thefe quantities them felves are chimerical entities. On the contrary, it appears from the definition (article 19) that an infinitely fmall quan- tity is the difference between two very efficient quantities, - namely, between any auxiliary quantity whatfoever and its limit, 25. Hence it follows farther, that every infinitely fmall quantity may be confidered as the difference between two auxiliary quantities, which have the fame third affigned quantity for their limit. For, let. X and Y be two different auxiliary quantities, whofe limit is the fame third quantity A. I fay, that X—Y is an infinitely fmall quantity, For, fince the limit, or ultimate value of X is 4, and that of Y is alfo A, it follows that the ultimate value of X — Y will be A—A, or o. Therefore the limit of 4 + (X—Y) is 4; earth may be reckoned very /mall, compared with the diftance of the fun, and as re/ative o, compared with that of any fixed ftar; and converfely, the diftance of the fun is very great, and that of a fxed ftar 1, or infinite, compared with the earth’s diameter.—Again ; fuppofing a rectangle to be continually diminifhed by the parallel motion of one of its fides, the law of continuity tells us that it will come to o, or that the moving fide will arrive at the fixed fide of the reétangle ; fo that o here is not abfolute nothing, but it is a line, which however may be looked upon as o, if com- pared with the reétangle ; and the re€tangle as 2, or infinite, if compared with the line. Jn like manner, a point and a reétangle are as 0, or no thing, when refpeétively compared with a line and a parallelopiped ; and thefe laft as 2, or infinite, when refpeétively compared with the two firft. Thus we fee that the fenfe of the o is always to be determined by the fub- je&t into which it is introduced. See Emerfon’s P.S. to the 2d edition of his Algebra, where he replics to the Reviewers, who had mifunderftood the very elegant folutions of his 73d and 74th problems. The rft, 3d, 6th, and 7th corollaries to the former of thefe problems will be ufeful in this place. “Cor. 1. If o multiply any finite quantity, the product will be pothing. * Cor. 3. Ifa finite quantity be divided by 0, the quotient is infinite. “ Cor.6. Adding or fubtra€ling any finite quantities to or from an ins finite quantity, makes no alteration. “© Cor. 7. Therefore, in any equation where are fome quantities in- finitely lefs than others, they may be thrown out of the equation.” W. D. and 238 Carnot on thé Theory of and confequently we may confider X— Y as ‘the difference between an auxiliary quantity 4 + (X —Y) and its hmit A, and this difference (by article 1g.) 1s an infinitely fmall quantity. It may therefore be affirmed, in general, that dz infinitely [mall quantity is the difference between two auxiliary pe which have the fame limit. 26. Two quantities cannot have the fame third quantity for their imit, unlefs the ultimate ratio between thofe two quantities themfelves be a ratio of equality. For, fince, by the fuppofition, the limit, or ultimate value of 4 is I, and 4 Tate bees : ie? 3 that shor is alfo 1, it is evident that the limit, or ulti- Bx x lee Reliab igs (=) mate value of —z=. is hikewife unity. Now ee ( (Zz) a3 and therefore the limit, or ultimate value of = is 1; that is, the ultimate ratio of X to Y is a ratio of equality. It may therefore be affirmed, in general, That An infinitely {mall quantity is the ratio which the difference of two quantities, ultimately im the ratio of equality, has for each of thefe two quantities. 247. In fine, it may evidently be farther affirmed, That 4x infinitely fmall quantity is an unaffigned quantity, to which as at firft attributed any arbitrary value whatever, and which as afterwards fuppofed to decreafe infenfibly till it arrive at o, er zero. Thus, in general, when it is faid, Let Z, for ex- ample, be an infinitely /mall quantity, it is precifely tanta- mount to faying, Let Z be any arbitrary quantity whatever, (and confequently auxiliary, for afligned quantities cannot be arbitrary) and let us afterwards fuppofe that quantity (Z) to decreafe continually till it come to O, or zero *. 28. A quantity is faid to be infinitely fmall relatively to another quantity, when the ratio of the firft to the fecond is o* Inthe 25th, 26th and 27th articles, the author gives us different ideas of an infinitely fimall quantity ; but which, if duly confidered, will be found to amount nearly to the fame thing. W. D. an woos the Infinitefimal Calewlus. Laxey @ infinitely fmall quantity; and, reciprocally, the fecond is faid to be infinite or infinitely ereat, relatively to the firft. 29. Two quantities are faid fo differ infinitely little, or to be infinitely little different, from one another, when the ratio of the one to the other differs from unity only by an in- finitely fmall quantity ; fo that their ultimate ratio is a ratio of equality, and fuch evidently are RS and MP. 30. -Fhe Infinitefimal Calculus may be defined to be the art of difcovering, by the help of quantities called Infinitefi- mals, the proportions or relations, whatever they may be, which fubfift between the different parts of any fyftem of quantities propofed. . Thefe infinitefimal quantities being nothing more than auxiliary quantities, introduced into the calculation only to facilitate the expreffion of the conditions of any propofed problem, it is evident that they muft neceffarily be eliminated out of the calculation, in order to obtain the defired refult, namely, the relations fought. Thus we may in fome re- {pects affirm, That every Infinitefimal Calculation is an un- jinifhed calculation; for in fact, as foon as the auxiliary quantities, which are not effential, come to be eliminated, the calculation ceafes to be infiuitefimal, and in every thing refembles an ordinary algebraic refult *. To complete the explanation of the principal terms which relate to the theory of Infinites in general, it remains for me to ftate what [ underftand by an imperfect equation. 31. I call every equation An imperfect equation, whofe two fides are unequal quantities, the difference however be- tween them being infinitely fmall; or, which comes to the fame thing, Every equation is imperfeét, the two fides of which, though unequal, have for their ultimate ratio, the ratio of equality, Thus, for example, the fal/e equations, TP = ae ee é ae ; and mee ye (fee article 9.) are what I call imperfe& * Every one knows, indeed, that a calculation, in which Infinitefimal quantities have any place, is not fuppofed to be finifhed, and that we never think the refult accurate till all the infinitefimal quantities are en- tirely eliminated, te aati equations-; 240° Travels through the equations; becaufe the quantities, negleted in the accuraté equations, whence they are derived, are infinitely fmall quan- tities. Ou the theory, therefore, of this kind of equations is founded the folution of the queftion before handled, and that of all’ queftions of that fort. For this reafon it is, that I fhall proceed to inveftigate the principles of the theory of imperfect equations, which is the foundation of the Infinite- fimal Calculus, or rather, which is itfelf that calculus. [Yo be continued. ] , V. Account of C.F. DamBercer’s Travels through the interior Parts of Africa, from the Cape of Good Hope to Morocco *. Tus adventurous traveller, a native of Germany, and brought up to the bufinefs of a carpenter, enlified at Amfter- dam, in the year 1781, as a foldier in the fervice of the Dutch Eaft India Company, with whom he entered:into an engagement for feven years. On the 21{t of June he failed from the Texel, and on the 21ft of September arrived at the Cape of Good Hope, where he was conveyed to the hofpital along with eighty-four other fick, who had come out in the fame veflel. After being a month in the hofpital, he was relieved from military duty, by being taken into the fervice of Mr. Brand, the poftmafter at the Cape and prefident of the council, who fent him to Falfe Bay, where he remained a whole year, employed in various labours, fuch as loading and unloading fhips, cutting down wood in the mountains, and other things of the like kind. Soon after he was promoted by his matter to be his houfe+ fteward, and in this fituation difcharged his duty for fome time to the complete fatisfaction of his employer, who after- wards carried him back with him to the Cape Town; but having quarrelled with his miftrefs, he found himfelf expofed to fo much ill-treatment, that he refolved to defert, and: to~ make his way to Europe by land. In order that he might be hetter able to carry this plan into execution, he requefted his * From C. Fv Damberger’s Landreife in das innere yon Afrike, in den Jabren.1781 bis 1797. Leipzig, 1301, matter } Interior Parts of Africa. AAT mafter to fend him back to Falfe Bay, where he expected he thould have an opportunity of effecting his efeape with the lefs danger of detection. This requeft was granted, and he fet out for the Bay onthe 14th of November 1783, after hav- ing put his box into the Company’s waggon, received twelve months pay due to him, and difpofed of various articles which he confidered as entirely ufelefs for his intended expe- dition. Among the Dutch troops at the Meifenberge was a cor- poral named Martens, a native of Hanover, who having accompanied Colonel Gordon on a journey into the interior part of the country as far as Caffraria, had conftructed a map of the diftricts through which he had paffed and prefented it to the Company, under an idea that he fhould be rewarded for his trouble ; but inftead of a reward, he was enjoined, under the pain of fevere punifhment, never to attempt any thing of the like kind in future. This man however was fo fond of thefe purfuits, that he ftill amufed himfelf with making charts, and our traveller after fome difficulty pre- vailed on him to allow him to copy fome of them in order to affift him in his enterprife. On the 24th of December, every thing being ready for his journey, he obtained leave of abfence from the fergeant on command under pretence of going to the Cape Town, but proceeded towards Stielenbufch, fo called from a governor of the name of Van Stiel, who formerly prefided over the Dutch fettlements at the Cape, where he arrived next evening. Being acquainted with the bailiff of this farm, who had often feen him at Mr. Brand’s houfe, he accofted him with con- fidence, and was received in a very friendly manner, efpecially as he told him that he was going to his matter’s plantation, to fee that every thing was properly conducted. At this place Damberger purchafed a new fowling-picce, and on the 26th proceeded to the farm of another acquaint- ance, named Munch, from whom he obtained two pounds of powder and thirty balls. On the 27th he came in fight of . his mafter’s farm, but did not approach it till the evening, left he fhould be obferved by the bailiff. As foon-as it was dark he went privately into the apartment inhabited by the flaves, You, VII. li whom baie) Fravels through the whom he requefied not to fay any thing of his arrival, and, after partaking of fome refrefhment, retited to reft, but with a mind fo agitated that he enjoyed very little fleep. Next morning at day-break he continued his journey, and on the roth of February reached Blettenbere’s Bay, where he pur- chafed feveral things neceflary for his intended expedition, fach as a calabafh to hold water, a few more pounds of pow- der, a flint and fleel, matches, &c. -During the few days’ that he remained here, he took up his lodging in the houfe of a perfon named Vogtmeyer, who was not then at home ; but he was kindly emtertamed by his wife, and he embraced this opportunity of obtaining frony the Hottentots im the fa- mily every information poffible refpecting the route he in- tended to purfue. The country around-this place has a beautiful appearance, and is exceedingly fertile ; it abounds with timber of every kind, and has a good fupply of ex- eellent water. When Vogtmeyer returned, which was on the 25th of February, he recetved our traveller with great friendfhip, but at the fame time told him that he knew he was a deferter, and that he would fend him back to the Cape; where he was fure he fhould be well rewarded by his mafter. He however entertained no fuch defign; for, after being in- formed of Damberger’s real views, he furnifhed him with a knapfack made of a ealf’s fkin, a hand-bill, with feveral other fmall articles, and wifhed him a good journey. Our traveller, who had now got to the diftanee of 74. miles from the Cape, again fet out on the 26th of February, and, purfuing his way owntels Caffraria, arrived next day at the firftt Hottentot kraal he had feen, which confilted of about twenty huts. In this kraal he remained nine days, at ihe end of which time he had an opportunity of continuing his journey in company with fome Hottentots of another kraal, who had come hither to procure fheep. Having pro- ceeded two miles with great difficulty through the long grafs, which rendered their progrefs exceedingly tedious and tire- fome, they halted for the night on the banks of the Silver River; but were unable to fleep for fear of the wolves, which, attracted by the fheep, kept prowling around them ; as they were afraid of kindling ous" to frighten them away, left they fhould Interior Parts of Africa. QAR, fhould fet fire to the grafs, which was exceedingly long and. almoft dry. In the morning they reached the fummit of the Milk Mountains, where they found good pafture ; they therefore fat down to breakfaft, and turned their fheep loofe to feed ; but fearcely had they put a morfel to their mot ath, when they efpied ten men rapidly advancing towards them. Our tra- veller having foon learned from his companions that thele firangers were Bofhmen, who no doubt would attempt to plunder them of their fheep, he endeavoured to infpire them with courage, and, immediately loading his piece, fired it at the enemy, one of whom fell; the reft then difcharged their aflagays, and betook themfelves to flight. Next morning our traveller arrived at the kraal where his companions refided. As he was much fati cued, having {pent feveral nights without the leaft repofe, he threw himfelf down in one of the huts and enjoyed a found fleep. When he awoke the Hottentots brought him fome milk and roaft mutton; and whilft he was partaking of this repaft the chief of the horde entered the hut in his drefs of ceremony, and, bowing feveral times before him, thanked him for the ‘afi ance he had given to bis countrymen. ~The chief then told him that shel Bofhmen, a few days before, had ftelen from the kraal thirty fheep. Our traveller, in confequence of this information, inquired what might be the ftrengih of the horde, and where they refided. Being informed, that they confified of about thirty men, and that they refided at a place in the mountains a few miles diftant, where, to guard againft the danger of an attack, they had fortified themielves behind a kind of abbatis, and were furnifhed with a great number of ftones, he told the Hottentots that he thought it not impof- fible. to drive them from their lurking-place, and offered to lead the attack, if they would promife to fupport him. “The chief liftened to this propofal with great pleafure, as it held forth hopes of recovering the ftolen fheep ;' but he ftarted fome objections as to the praéticability of carrying it into execution.. It was however at lait agreed that the at- tempt fhould be made, and Damberger, after giving proper inftruétions to the Hottentots, defired each to furnifh himfelf Ii 3 with 244 Travels through the with a ftout cudgel, a bundle of dry grafs, and a little dry wood, As foon as it grew dark, they proceeded in great filence towards the mountain, where, as foon as they arrived, our traveller divided the whole troop into two bodies, one - under his own command, and the other under that of the ‘ chief. They then rufhed towards the firft fence, which being inftantly fet on fire, the flames were foon fpread by the wind, and in a little while the whole mountain feemed to form one general conflagration, They now proceeded to a place at the bottom of the mountain, by which it was fup- pofed the enemy would be obliged to make their efcape. Here they had not long waited, when they heard a dreadful howling, and faw feveral of the Bofhmen half feorched rufh-. ~ Ing through the flames. To terrify them the more, and at the fame time to give a more general fignal to the Hotten- tots to attack them, our traveller difcharged his piece among the flying enemy, who were attacked with fuch fury by his Hottentot allies, that this whole horde of plunderers were ex+ tirpated. Next morning they not only recovered fome of the ftolen fheep, but found feveral more which had belonged to the enemy. When the conquerors returned to the kraal, they were received with great joy. As our traveller found himfelf much fatigued by the expedition, he retired to enjoy fome reft in the chief’s hut, but the Hottentots fpent the whole night in rejoicing on account of their victory. Damberger continued two weeks among thefe people, who treated him with great refpeét ; but as it was then the moft favourable period for travelling, he refolved to proceed and to take.advantage of the winter feafon, as it is called, which takes place in April, and which however is diftinguifhed only by the weather being rainy and the air cooler. _ In gonfequence of this refolution he left the kraal on the 25th of March, and direéted his courfe eaftwards towards Fith River, but with fome caution to avoid falling in with any of the Dutch plantations, of which there were feveral in ‘ the neighbouring diftriéts. After paffing another kraal he took up his lodging for the night in a third, which was the jaft within the jurifdiétion of the Dutch Eaft India Company. It was fituated on the Fith River, at a place where it divides itfelf Interior Parts of Africa. 245 ' itfelf into two arms, one of which flows between the moun- tains and the Dutch colonies, and the other into the Silver River already mentioned. — The author in fpeaking of the Hottentots f%ys, ‘* Mr. Vaillant has given a very ample defcription of the manners and cuftoms of thefe people, but he is not always correct. * The chief of a horde bears the title of Montur. This office however is not hereditary, and the perfons chofen to fill it are thofe who have diftinguifhed themfelves by fome heroic aétion, fuch as killing fome favage animal, or obtain- ing a victory over the enemy. The chief of each kraal, whether it lies within the jurifdiction of the Dutch or not, Teceives from the Company a large cane, having at the top a filver knob, infcribed with the Company’s arms, and which is borne by the chief on folemn occafions. Each Hottentot alfo receives annually two pounds of tobacco and two bottles of brandy; but, in return, muft endeavour to Jearn in fome meafure to underftand the Dutch language. Thofe who refide among the planters learn it with great eafe; but thofe who live at a diftance muft embrace fome other opportunity of learning it: and when the Monturs go to the Cape Town, they muft always carry with them fome men belonging to their horde, to whom various occupations, fuch as cutting wood, &c. are affigned in the caftle, that they may. become familiar with the language by frequenting the com- pany of the foldiers, and the inhabitants. When the Mon- tur goes to the Cape the next vear, he carries with him fome more of his countrymen, and thofe who came the preceding year return. Thefe Hottentots are perhaps the lazieft people in the world; but in many parts of their country they are defiitute of water. Tliey leave the moft fertile fields unculti- vated, and only plant here and there a little Turkifh ‘corn. Their chief occupations are the rearing of cattle and hunting, but they purfue the latter only when compelled by neceflity and the want of food. They pay little attention to fifhing, though they have very good opportunities, efpecially in win- ter, of catching fifh without great exertion. There have been inftances of their enduring hunger for feveral days rather than give 2.46 Travels through the give themfelves the Jeaft trouble to fearch for food. "The Coinpany have irequently offered to fupply them with nets, corn, and other articles, and to affign lands to them nearer the Cane, if they would only become.a little more aétive and induftrious—but without the leaft eficét ; as they believe that in this cafe they fhould be expofed to more bodily labour. They preter living in poverty in the midft of the deferts, in a flate little faperior to that of their cattle; and are fo timid as to fuffer themfelves to be driven fometimes towards the South by the Caffres, and fometimes towards the Eaft by the Bofhmen. If they could only aflume a little courage, they would foon make their enemies fenfible of their power; but they have very little care for the future. “* The women are very active in the management of their domeftic economy, but have a confiderable degree of vanity, for they employ a great deal of their time in ornamenting their perfons. To amother a child is a great treafure, and the hufband dare never prefume to take it into his hands as long as it is at the breaft, though in other refpects he treats his wife as his flave. This right has been claimed by the mothers in confequence of the cruelties formerly praétifed by the fathers; for, when the Portuguefe firft vifited this country, many of the men fold their children to them for brandy or tobacco; this incenfed the mothers, and therefore they affumed the above privilege. A. child is fuckled for four months, during which time the mother in the day carries it about on her back wrapped up in a fheep’s fkin, but in the night places it in her bofom; after that period it is fuffered to lie on a mat fpread out on the grafs, and has the fame food as the reft of the family. «© T was much pleafed with their treatment of the dead. They never bury them until every mean poffible has been tried to recall them to life. Thofe who die of chronic or lin- gering difeafes, they fhake and ‘beat on the ribs with their fifts ; if they exhibit no fiens of life, they are interred the fame evening, but not until fimilar experiments have been tried to revive them. On young perfons who die fuddenly other methods are tried: the foles of their feet are pricked with o ‘ ; Interior Parts of Africa. 447 with aflagays *, pieces of red hot. iron are applied to their nofe, and their bodies are well rubbed; but if no figns of life appear, they are committed to the earth next evening. The corpfe is immediately carried out from the hut, and watched by fome of the relations, who do the fame thing for twenty-eight days after it has been buried, in order to pre- vent it from being torn up by wild beatts. Our traveller refumed his journey on the 25th, directing his courfe towards Fifh River, and on the 2gth entered Caf- fraria, where at firft he had to afcend fteep mountains, but towards evening defcended into the level country. After pafling through feveral hordes of Caffres,’ by whom he was ~ in general well received, he arrived at a kraal confifiing of 27 huts, and containing 1400 inhabitants. As he was here treated with great friendthip, he remained fome weeks ; and having heard from the natives, among whom he faw feveral European articles, that a {hip had been firanded on the coatft, at a place lying at the diftance of two days journey, he re- folved to go thither, and prevailed on fome of the Caffres to accompany him. They accordingly fet out on the 27th of April, and next evening reached the remains of the veffel, which were lying in a bay between Fifh River and the river St. Lucia. Here they found feveral half-putrid bodies, moft of them pierced with wounds, fcattered about on the fhore, and intermixed with cafks, chefts, bales of cotton, and other articles, entirely fpoilt by the fea water and the fun. What chiefly attracted the notice of the Caffres was the iron work belonging to the fhip, of which they collected as much as they could. After burying the bodies +, and picking up various articles, among which was a pocket compafs, they fet out to return. The compafs, which was not injured, fell * The points of their affagays are not poifoned except when they go out to attack their enemies. + This thip had been Joft in dadessidekn of a mutiny which broke out among the crew, who firft murdered their officers, and then ran the veffed on fhore. The crew then landed, and waadered about in the country, where they either fell a facrifice to the climate or were maffacred by the Caffres. Of the whole fhip’s company four only efcaped, and of thefe four two died of their wounds, The other two made their way to the Cape. to 248 Travels through the to the lot of our traveller, who confidered it as an acquifition of no fmall importance. On the 20th of May, Damberger took leave of thefe friendly Caffres, and, after encountering confiderable dangers and difficulties between that period and the 11th of July, directed his courfe eaftwards, with a view of proceeding to Egypt. Towards evening he difcovered fome huts at a- diftance, but was not able to reach them ; he therefore Jay down on the grafs with his head on his bundle to enjoy a little reft, but was foon roufed by four Caffres, who con- duéted him to their huts. Here he was robbed of his fowl- ‘ing-piece and bundle, but they were both afterwards reftored. He was attacked alfo with a violent pain in his bowels; but on making known his complaint to one of the Caffres, he gave him fome dried leaves to chew, which acted as a ftrong’ emetic, and foon afforded him relief. Among the next horde whom he vifited he was more un- fortunate, being robbed both of his bill and his fowling- piece; the former he recovered, but the latter was broken to pieces by the Caffres in order that they might convert the iron part of it into points for their affagays. Soon after leaving this horde he was obliged to pafs the night in the open air on the banks of a rivulet, where he made a large fire to frighten away the wild animals, but was unable to fleep a moment on account of the multitude of fnakes which fwarmed around him ; and towards morning he faw hundreds of large baboons. The latter had taken up their ftation on all the neighbouring trees, and did not feem in the leaft fhy or afraid. Of thefe people the author fays, ‘* This nation, as well as feveral more of the African tribes, are accufed of indolence, but I am convinced that the induftrious Europeans, if tranf- ported hither, would be equally ina€tive. The heat oppreffes the labourer too much, and exhaufts the powers of the body ; to this it may be added, that moft of thefe tribes are deftitute ef the neceffary implements, fuch as fpades, hoes, &c. and the ground is fo hard that, before any other tool can be ufed, it muft be cut up with a fort of pickaxe. The cultivation of the few fields, which are fown here with Turkifh wheat, confumes czatieal Interior Parts of Africa. 248 confumes a great deal of time and requires much labour. 1 obferved that two ftout ative men could till in a day no more than fix feet fquare. The land, after being fown, was covered, to the height of two inches, with fand, in order that the exceflive heat might not too foon dry up the moifture, and to prevent the ground from cracking by the drought and the rain. They derive more advantage, without much la- bour, from rearing of cattle, and from hunting and fifhing. This nation, indeed, have a ftrong propenfity to ftealing, bat they never commit murder; and much lefs do they devour. human flefh. Several Europeans *, however, who have vi- fited thefe people, affert that they eat human fiefh with great avidity; but this is abfolutcly falfe. If a traveller underftand their language he has nothing to fear, efpecially if badly clothed and i in poffeffion of no articles of value. If they take any thing from him, he may reft affured that they will give him fomething of theirs in return if he afks for it. & The dead are interred at fome diftance from the kraal, and ‘the relations kindle a large fire near the fpot, which they maintain three days, to prevent the favage animals, that might be attracted by the {mell, from coming to tear up the body. Few perfons die 1 in the kraals, as the fick are-removed to huts fituated at a diftance ; for they believe that every dif- eafe is infectious, and that it is their duty to guard againft the contagion.” After a {tay of three weeks among thefe people, whom our traveller calls the Jamatians, he continued his journey, and, crofling the Makumbo river, entered the territories of the Muhotians. Here he was at firft treated with great harfh- nefs and feverity, but he ftill found friends among the female fex. While he remained with this tribe he was conduéted to a place where he found the bodies of five white men co- vered with wounds, and apparently pierced with affagays : ob their right arms he obferved the figure of a crucifix, with the Jetters H, 1, E, M, and the date 1779. On the fecond of Oétober he arrived among another tribe , called the Kamtarians, who inhabit a diftrict fituated on the river Tambo, and who live chiefly by hunting and the rear- * Kolbe, Sparmann, Patterfon, &c. Vo. VIII. Kk ing %s50 « Travels through the ing of cattle. The men in general are of low ftature, and have fhort woolly hair. Thefe people were of a darker complexion than the other tribes he had quitted.’ They confifted of fix or {even thoufand, of both fexes, capable of bearing arms. The women were of Jarger fize than the men, and exceedingly bold and courageous, The greater part of them had been carried away by force from other nations, or had been taken prifoners in war and retained by the, men. Thefe people never rear their female children, but deftroy them as foon as they are born. There are no priefis among them, though there is reafon to think that they are not deftitute of religion. The oldeft inhabitant in each village acts generally in the capacity of chief and judge. Folygamy is allowed among . this tribe; and every woman not pregnant by her hufband) is at liberty to cohabit with any other man whom fhe choofes, sand if fhe bring forth a boy to him, fhe may become his wife. | Thefe people are exceedingly fuperftitious, and, when the . leat misfortune befalls them, fhut themfelves up in_ their huts, where they remain totally imaétive for three or four : , davs. When any one of their nation has been wounded or killed by wild beats while hunting, they fay ‘ he offended the great god;”” but if fach an event take place in the night- . time, and particularly by moon-light, they fay, “ he offended the little god,”’ and on that account was punifhed. Ifa woman die-in childbed, which, however, is feldom the cafe, fhe is buried in a particular fpot, and her family muft remain fix moons, at fame diftance from the village, in huts fet apart for that purpofe, without having any intercourfe with the -reft of the tribe. If a woman bring forth a male child — during cloudy weather, or when the moon does not fhine, it is concluded that his father bas offended the gods, and that the boy is nat worthy of being a refpeétable member of fo- ciety. When he grows up, therefore, he is employed in the mott menial offices, fuch as cutting wood, guarding the cat- tle, and other fervices of the ike kind, Neither cireumeifion, nor any fimilar practice, is known in this country. If a woman be. delivered of a boy at a fortunate period, the father kills a goat, and gives an entertainment to the friends af * a Interior Parts of Africa: 25 of hig family. The dead are génerally buried by their rela- tions under large trees. During the time of the funeral a large fire is kindled, in which the effeéts. of. the deceafed are burnt, and the afhes are thrown into the gfave., The fire is kept burning till the next full moon: Whoever fteals.a mar- ried or unmarried female, may keep her as his wife; but, if he does not choofe to do fo, he may fell her, and in. return generally receives a flcep, or a greater or lefs number of afia+ gays, according to her beauty. Thefe people are kind and hofpitable to Gianrers: Damberger left! the Kamtarians on the 7th of O&ober, * and on the. 3oth, after pafling through part of the kingdom of Biri, arrived in the territories of that of Mataman. The fovereign of this country rules with unlimited power, and is ftiled Sobaawoia, that is, Chofen by the gods. The crown is hereditary to females as well as males: When one of the former fucceeds, fhe may choofe from her fubjects a hufband to participate with her in the government. The perfon fo chofen, however, muft be firft examined by the oldeft part of the community, in order that it may be known whether he pofleifes the talents neceflary for the intended dignity. The king here acts in the capacity of high-prieft, prophet, and tutor to the youth. [His decifions are refpected even when he judges wrong. He pofleffes the exelufive privilege of having a plurality of wives, and muft inftall the inferior judges, pricfts, &c/ He never takes the field againft the enemy, but delegates the command of the army to another, The foldiers are brave, and exccedingly expert in managing their bows and arrows. They are faid to amount to about 30,000. There are three large cities in the kingdom, the capital of which, called Seenhofa, lies at the diftance of two ' days journey. This city, the refidence of the king, our tra- veller réfolved to vifit; and, being furnifhed with a perfon ta fhow him the way, foon reached the place. Ont his arrival he repaired to the Mohwoe*, who gave him fome corn and four milk, and conducted him into his hut, where he was * This is the name given to the governors appoirt-d in each town by the king, and who atthe fame time act as piictls. Kk a allowed 252 Travels through the Interior of Africa. allowed to pafs the night. Next morning the Mohwoia car- ried him through a Jong ftreet, bordered on each fide with huts, to a kind of green, where he was introduced to the king, whom he found ftanding amidft a circle-of his attend- ants, and who appeared to be about forty years of age. The day before he had taken four florins from his veft *, in order that he might make an offer of them to the fovereign. This he accordingly did, and requefted his majefty’s protection ” and a fupply of food. The prince, after looking fome time at the money, ordered one of his wives to fetch fome milk and meal, which being mixed together and ftirred round, our traveller fat down on the ground and made a hearty meal, He then accompanied the king into his hut, where a mat vas brought for him to fit upon. The king afked him for fome more money, and told him that in return he would make him a kah/ceto (fervant). Damberger protefted that he had none; but, as he was defirous of becoming acquainted with the manners and cuftoms of the country, he informed the king that he gratefully accepted his offer. Obferving, however, fome days after, that he was confidered in the light of a common flave, he refolved to make his efcape the firft opportunity he could find for that purpofe. On the 2gth of November, having been obliged to accom- pany the king his mafter on a hunting excurfion, for the pur- pofe of carrying a calabafh filled with water, a leather bag containing millet, and a javelin, in pafling through a wood interfperfed with fmall hills he pretended to be fuddenly taken ill with a pain in his bowels, and immediately fat down on one of thefe eminences. The king, not fufpecting any deception,. gave him permiffion to remain till he fhould call for him, and, taking the javelin from him, proceeded forwards; but as foon as his mafter was out of fight, our traveller fet off as faft as - he could, purfuing a northern direGtion with a view of reach- ing the mountains. In croffing a river he ftumbled againft a {tone and hurt his foot, by which means his progrefs was confiderably retarded; and falling in foon after with fome of * Some time before this period the reft of his clothes had become fo ragyed and filthy that he was obliged to burn them. the Experiments on the Rays which occafion Heat. 253 ji the natiyes, they compelled him to. take upon his back a young wolf they ‘had found, and to return with them toa village which he had left only a few hours before. Here he was detained eight days, during which he fuffered confiderably from the wound in his foot; but being at length fuffered to. depart, and proceeding towards the territories of the Seege- rians, he arrived at a village called Mukofa, fituated on. an eminence. [To be continued. } VI. Experiments on the Solar and on the Terreftrial Rays that occajion Heat; with a comparative View of ‘the Laws to which Light and Heat, or rather the Rays which occafion them, are fubje, in order to determine whether they are the fame, or different. By Wiiiiam Herscuer, LL.D. F.R.S. [Continued from Page 134-] 14th Experiment. Refraéiion of the Heat of a Chimney- Fire. ca I PLACED Mr. Dollond’s lens before the clear fire of a large grate*. Its diftance from the bars of the grate was three feet; and in the fecondary focus of it was placed the thermometer No. t. No. 4 was flationed, by way of ftand- ard, at 2! inches from the former, and at an equal diftance from the fire. Before the thermometers was a flip of maho- gany, which had three holes in it, °. of an inch in diameter each. Behind the centre of the firft hole, 3 of an inch from the back, was placed the thermometer No. 1; and between the fecond and third hole, guarded from the direét rays of the fire by the partition, at the fame diftance from the back, was put No. 4. Things being thus arranged, the fituation of the apparatus which carried the thermometers, and that where the lens was fixed, were marked. Then the thermometers, having been taken away to be cooled, were reftored to their places again, and their progrefs marked as follows : * See Plate VIII. fig. 3. No. 254 Experiments on the Solar and on thé No.1. No.4. 7 Here, in nine minutes, the ray$ Burning lens, Screened. coming from the fire, through o! 58 58 the burning glafs, gave gi i 65 60 { degrees of heat more to the 3 68 61 thermometer No. 1, that 5 70 6r2 No. 4, from change of tem- 7 one 613 + perature, had received behind 9 oh oe 613 J the fcreen. “Now, to deter- mine whether this was owing merely to a tranf{miffion of heat through the glafs, or to a condenfation of the rays, by the refraction of the burning lens, I took away the lens, as foon as the laft obfervation of the thermometers was written down, and continued to take down their progrefs as follows+ No.1. No.4. Here the dire& rays of the et lz 61+ fire, we fee, could not keep It 70% 614 up the thermometer No. 1; 12 FO 613 which loft 2: degrees of — 69+" eres heat, notwithftanding the 14% 69% Gre lens intercepted no felizer any of them, I now reftored the burning glafs, and conti- nued, 5’ 69% 613 Here again, the lens aéted as a 16 69+ 613] condenfer of heat, ‘and gave 13 17 70 61 degrees of it to the thermometer 20 70%, 613 | No.1. ITnow once more took 25 71 6i;J away the lens, and continued the experiment. pa 71 613) This again confirms the fame by 3I 68 61~f a lofs of 3 degrees of heat. Lf refiored the lens once nr6re, and had as follows: No.1. No. 4.) And here the thermometer Burning Lens, Screened. received 1} degree of heat 1's 68 613 again ; fo that, in the courfe 35 69} 6x3 of 35 minutes, the thermo- meter No. t was alternately raifed and depreffed five times, by rays which came from the chimney fire, and were fubject "to laws of refraétion, not fenfibly different from thofe which affe& light. 15th Experiment, Refra€iion of the Heat of red-bot Iron. I caufed a lump of iron to be forged into a cylinder of 2 9 inches Terreftrial Rays that occafion Heat. 255 inches diameter, and 2% inches long*. This, being made red-hot, was ftuck upon an iron handle fixed on a ftand fo as to prefent one of its circular faces to a lens placed at 2.8 inches diftance ; its focus being 1.4 inch, and diameter 1.1. Before the lens, at fome diftance, was placed a fercen of wood, with a hole of an inch diameter in it, by way of limiting the objeét, that its image in the focus might not be larger than neceflary. The fereen alfo ferved to keep the heat from the thermometers, No. 2 was fituated in the fecondary focus of the lens; and No. 3 was placed within 3; of an inch of it, and at the fame diftance from the lens as No. 2. By this arrangement, both thermometers were equally within the reach of tranfmitted heat; or, if there was any difference, it could only be in favour ¢ No. 3, as being behind a part of the lens which, on account of its thinnefs, would ftop lefs heat than the middle. Now, as the experiment gives a refult which differs from what would have arifen from the fituation of the thermometers, on a fuppofition of tranfmitted heat, we can only afcribe it to a condenfation of it by the refraction of the lens; and, in this cafe, the thermometer No. 3, by its fituation, muft have been partly within the reach of the heat- image formed in the focus. During the experiment, the ther- momieters were alternately Eiened two minutes from the effeéts of the lens, and expofed to it for the fame length of time, and the refult was as follows: No.2. No.3. Here, in the firft In the Focus. Near the Focus. 4 and fecond mi- Screened 0’ 56 * 56 | nutes, No. 2 Open b) 62 60 \ gained two de- Sereened 4 59 58 grees | of heat Open a) 61 59 more than No.3. Screened 8 58> 57: : Inthe third and Open io 59: 58: J fourth, itloft one 5 more than No. 3. In the fifth and fixth, it gained one more. In the feventh and eighth, it loft 1£ more; and in the ninth and tenth, it gained 2 more than the other thermometer. This plainly indicates its being acted upon by refracted heat. Lett there {hould remain a doubt upon the fubjeét, I now re- * See Plate VIII. fig, 1. moyed 256 Experiments on the Solar and on, the moved the lens, and, putting a plain glafs in the room of if, I repeated the experiment with all the reft of the apparatus in its former fituation. Screened 0% 5RE 56%) Here we find that both Open 2 G2. 613} thermometers receiv- Screened 4 60! 60 { ed heat and_ parted Open 6 6% 60° f with it always in equal Screened 8 60 59+] quantities, which con- Open 10 60% 60:J firms the — experi- ment that has been given. And thus it is evident that there are rays iffuing from red-hot iron, which are fubjeét to the laws of refra€tion, nearly equal to thofe which affect light; and that thefe rays are invetted with a power of caufing heat in bodies. 16th Experiment. Refrattion of Fire-beat, by an Infirument d refembling a Telefcope. Tt occurred to me that I might ufe a concave mirror te condenfe the heat of the fire in the grate of my chimney, and, reflecting it fideways by a plain mirror, I might after- wards bring it to a fecondary focus by a double convex Jens ; and that, by this conftruction, I fhould have an inflrument much like a Newtonian telefecope *. The thermometer would figuratively become the obferver of heat, by being applied to the place where, in the real telefcope of the fame conftruc- tion, the eye is fituated to recerve light. Having put toge- ther the different parts, im fuch a way as I fuppofed would an{wer the end, I tried the effect by a candle, in order to afcertain the proper diftance of the objeét-mirror from the bars of the chimney-grate, «The front of the apparatus was guarded by an iron plate, with a thick lining of wood; and the two thermometers which | ufed, were parted from the mirrors and lens by a partition, which fcreened them from the heat that was to be admitted through a proper opening in the front plate, to come at the objeét-mirror. In the par- tition was likewife an opening, of a fufficient diameter to permit the rays to come from the eye-glafs to their focus, on the ball of the thermometer No. 1; while No. 4 was placed * See Plate VIIE. fig. 2. by > a ee —e Co i a i al St ns a Terreftrial Rays that occafion Heat. 257 by the fide of it, at lefs than half an inch diftance. In the experiment, the obje&t-mirror was alternately covered by a piece of pafteboard, and opened again. The thermometers were read off every minute; but, to fhorten my account, I only give the laft minute of every chance. PbS No.1... No.4. .) Here,in the In the Focus. Near the Focus. firtt eight The mirror covered 0° Ve "7 = minutes, The murror open 8 $4 eho. 1: the ther- Covered - 16+, 86; 795 mometer Open - 21 892 $1 expofed Covered - ag 892 825 to the ef- Open ae 37 gts Ose aT 2 fects OT Covered - 47 84 797 J the fire- inftrument, gained 2 degrees of heat more than the other. In the next 8 minutes, the mirror being covered, it gained i degree lefs than the other. The mirror being now opened again, it gained, in five minutes, 23 degrees more than the other. When covered fix minutes, it gained 14 degree lefs than No. 4. In the next ten minutes, when open, it gained 4 degree more; and, in the laft ten minutes, when: the. fire began to fail, and the mirror was again covered, it loft one degree more than the other thermometer. All which can only be accounted for by the heat which came to the ther- mometer through the fire-inftrument; and, as this experi- ment confirms what has been faid before of the refraction of culinary heat, fo it alfo adds to what has already been proved of its reflection. For, in this fire-inftrument, the rays which occafion heat could undergo no lefs than two reflections and two refractions. \ 17th Experiment, Refraction of the invifible Rays of i Solar Heat. I covered one-half of Mr. Dollond’s burning lens with pafteboard, and threw the prifmatic fpectram upon that cover *; then, keeping the laft vifible red colour one-tenth of an inch from the margin of the pafteboard, I let the in- vifible rays beyond the fpeétrum fall on the lens. In the * See Plate I. fig. es! Vou. VIII. LI! focus 258 Experiments on the Solar and on the focus of the red rays, or a very little beyond it, I had placed the ball of the thermometer No. 1; and, as near to it a3 con- venient, the fmall one No. 2. Now, that the invifible folar rays which occafion heat were accurately refracted to a focus, may be feen by the following account of the thermometers : Bory. .:. Ne: 2. Here, in one minute, thefe In the Focus. Near the Focus. rays gave 45 degrees of heat o! 57 1 Be ~ to the thermometer No. 1, I 102 57 which received them in the focus, while the other, No. 2, fuffered no change. It is remarkable se notwithftanding I kept the red co- Jour of the fpeétrum ', of an inch upon the pafteboard, a little of that colour might ftil] be feen on the ball of the ther- mometer. This occafioned a furmife that, poffibly, the in- vifible rays of the fun might become vifible if they were pro- perly condenfed; I therefore put this to the trial, as follows: 18th Experiment. Trial to render the invifible Rays of the é Sun vifible by Condenfation. Leaving the arrangement of my apparatus as in the laft experiment, I withdrew the lens, till the laft vifible red colour was two-tenths of an inch from*the margin of the femicir- cular pafteboard cover; then, taking the thermomet ters, I had - as follows : No. 2. No. 3.) Here there was no longer the leaft o! oy de 57 \ tinge of any colour, or veftige of 1 78 57 light, to be feen on the ball of the thermometer; fo that, in one minute, it received 21 de- grees of heat, fram rays that neither were vifible before, nor could be rendered fo by condenfation, i? To account for the colour which may be feen in the focus, when the laft vifible red colour is Jefs than two-tenths of an inch from the margin of the pafteboard which intercepts the prifmatic fpeétrum, we may fuppofe that the imperfeét re- fraGtion of a buming lens, which, from its great diameter, cannot bring rays to a geometrical focus, will bring fome feattered ones to it, which ought not to come there. We may alfo admit that the termination of a prifmatic {pectrum, cannot Terreftrial Rays that occafion Heat. 259 tatinot be jaccurately afcertained by looking at it in a room not fufficiently dark to make very faint tinges of colour vi- fible. And to this muft be added that the imcipient red rays muft aétually be feattered over a confiderable fpace, near the confines of the fpectrum, on account of the breadth of the prifm, the whole of which cannot bring its rays of any one colour properly together; nor can it feparate the in- vifible rays entirely from the vifible ones. For, as the red rays will be but faintly feattered in the beginning of the vi- fible fpectrum ; fo, on the other hand, will the invifible rays, feparated by the parts of the prifm that come next in fuccef- _fion, be mixed with the former red ones. Sir Ifaac Newton has taken notice of fome imperfect tinges or hazinefs on each fide of the prifmatic {pectrum, and mentions that he did not take them into his meafures *. 19th Bsa sinant. Refra&ion of invifible Culinary Hear. , There are fome difficulties in this experiment; but they arife’not fo much from the nature of this kind of heat, as from our method of obtaining it in a detached ftate. A red- hot lump of iron, when cooled fo far as to be rio longer vifible, has but a feeble ftock of heat renmiaining, and lofes it very faft. A contrivance to renew and keep this heat might certainly be made, and I fhould, indeed, have at- tempted to carry fome method or other of this kind into exe- cution, had not the following trials appeared to me fuffi- ciently conclufive to render it unneceffary: Admitting, as has been proved in the 15th experiment, that the alternate rifing and falling of a thermometer placed in the focus of a lens, when the “ball of it is fucceffively expofed to, or fereened from, its effects, is owing to the refra€lion of the lens, and cannot be afcribed to a mere alternate tran{miffion and ftop- page of heat, I proceeded as follows + :—My lens, 1°4 focus, and 11 diameter, being placed 2‘8 inches from the face of the heated cylinder of iron, the thermometer No. a, in its focus, was alternately guarded by a {mall patteboard fereen put before it, and expofed to the effets of condenfed heat by removing it. * Newton's Optics, p.23, 1. 10. + See Plate VIII. fig. 2, Ll2 No. 260 Experiments on the Solar and on the ; No. 2. >| Now, the! begin Screened» 0’ ©. 55 | Very red-hot. ning of this ex~ Open z 63! Red-hot. periment, being Screened 4 55 Still red-hot. | exactly like that Open. .6 60% Stull red. ; ofthe 15th, with Screened 8 57> Alittle red. the thermome- Open’ 10 59° Doubtful. ter No. 3 left Screened 12 57; Notvifiblein mv +} out, ,the argu- Open 14. 582 room darkened. ments that have Screened 16... 57% before proved the Open 8 585 refraction ofheat Screened. 20 ive | in one ftate, will Open 22 58 ; now hold good Screened ‘2 57% for the whole. Open 26 58 For here we have Screened 28 Sve J a regular alter- nate rifing and falling of the thermometer, from a bright red heat of the cylinder, down to its weakeft {tate of black heat; where the effect of the rays, condenfed by the lens, exceeded but’half a degree the lofs of thofe that were ftopped by it. 20th Experiment. Confirmation of the 19th. In ordér to have fome additional proof, befides the uniform and uninterrupted operation of the lens in the foregoing ex- ‘periment, I repeated the fame with an affiftant thermometer, No. 3, placed firft of all at 2 of an inch from No. 2, and more towards the lens, but fo as to be out of the converging pencil of its rays, and alfo to allow room for the little fore between the two thermometers, that No. 3 might not be covered by it. No, 2. No. 3.) Here No. 3, be- Th the Focus, Advanced fideways. ing out of the 4 Always open. reach of re- Screened 0° 625 63 fraétion, gra- Open I 63% 64 dually acquir- Screened 2 622 64. ed its maxi- Open 3 64. 644 ¢ «muin of heat, Screened 4°. 63% 644 in’ confe- Open 5 647% 64: quence of an Screened. 6 64% 64% uniform. ex- Open yi) 644 64 pofure to the Screened 6 64.5 64. J influence of the hot cylinder; after which 4t began to decline.. No.2, on the Terreftrial Rays that occafion Heat. 261 the contrary, came to its maximum by alternate great ele- vations and finall depreffions; and afterwards loft its heat by great depreflions and {mall elevations. After the firt eight minutes, [ changed the place of the affiftant thermometer, by putting it into a ftill more decifive fituation ; for it was now placed by the fide of that in the focus, fo as to partici- pate of the alternate fereening, and alfo to receive a fmall fhare of one fide of the inyifible heat-image, which, though unfeen, we know mutt be formed in the focus of the lens. Here, if our reafoning be right, the afliftant thermometer thould be affected by alternate rifings and fallings; but they thould not be fo confiderable as thofe of the lens. © No, 2. No. 3. 7) Here the changes Inthe Focus. Inthe Edge of it. } of the thermo- Both open 8! 64: 64 meter No. 4 Both open. g 63% 633 were —3 4 4 Open I 64% 64 —1i+i-— Sereerred ras) 4 63 63 OT Ei Sand Open 14 633 63% thofe of No. 3 Sereened § 16 623 63 were — 2 + Open 18 632 63% gE +ie + 4 3, Ail which fo clearly confirm the effect of the re- fraction of the Jens, that 1t mult now be evident that there are rays iffuing from hot iron, which, though in a ftate of total invifibility, have a power of occafioning heat, and obey certain laws of refraction, very nearly the fame with thofe that affect light. As we have now traced the rays which occafion heat, both folar and terreftrial, through all the varieties that were men- tioned in the beginning of this paper, and have fhown that, in every flate, they are fubject to the laws of reflection and of refraction, it will be eafy to perceive that [ have made good a proof of the three fir of my propofitions. For the fame experiments which have convinced us that, according to our fecond and third articles, heat is both reflexible and refrangible, ettablith alio its radiant nature, and thus equally prove the firft of them. End of the Firft Part. Slough, near Wind‘or, 1 April 26, 1800. “ ! VII. Account f. 262. }: VIE. Account of fome interefling Experiments, performed at the London Pbhilofopbical Society, refpefting the Effects of Heat, excited by a Stream of Oxygen Gas throwm upon zgnited Charcoal, on a Number of Gems and other refrac- tory Subjiances fubmitted to its Adtion; with a Defcription of the Apparatus employed. [Continued from Page 29:] Wedgewood’s Pyrometer Pieces. evi Puree the experiments already defcribed, it was propofed by feveral of the members that fome attempt fhould be made to determine the degree of heat which had been excited ; and, with a view to this end, a fragment of one of Mr. Wedgewood’s pyrometer pieces was fubjeéted to the blaft: in a few feconds, however, it became perfeétly fufed. It does not appear, therefore, that we are at prefent in pof- feffion of any better inftrument for appreciating the intenfity of heat thus produced than the gems themfelves, which, as fome of them are more refractory than others, and mans; of them more fo than moft other fubftances, may, from the changes which they undergo, ferve to afford a rough method of eftimating the comparative degree of temperature. Spinel, XVIII. A ruby-fpinel, which weighed 24ths of a carat, was, like the preceding flones, expofed in an excavation made "am a piece of charcoal ignited by means of a common blow- pipe, to a fiream of oxygen gas from the gafometer. At the. end of 23” it had loft neither weight nor colour, but had affumed the appearance of a rough garnet, having apparently undergone a very flight and fuperficial fufion, juft fufficient to injure its polifh. Jargoons. o XIX. Thefe ftones are colourlefs, and harder than rock- eryftal, but lefs fo than the ruby. They are ufually found in diamond-mines, and, when well cut and fet, play nearly as well as rofe diamonds. That they are however effentially 9 different Experiments refpe&ting Heat. 263 _ different from the diamond, needs no other proof than their incombutftibility. One which weighed {ths of a carat, aisle to the heat - for 2°, was found to hike loft no weight; whereas a diamond of the fame fize would in that time have been entirely diffi- pated, and refolved into carbonic acid gas. The ftone loft its tranfparency, and affumed the appearance of a piece of white enamel: it had evidently begun to fufe, but fome traces of its form, and even of its facets, are ftill difcernible. XX. Another jargoon, weighing 4Sths of a carat, was expofed to the heat for. the fame length of time. It broke into three pieces while under the blaf, but now prefents the fame appearances as the former. The furfaces of both are more opake and white than the interior. Vermilions. XXI. A vermilion which weighed ;*,ths of a carat, treated for 2', loft no weight, but became fisfed into a polifhed opake globule, which is nearly black, with a tinge of brownifh- green, like that of very dark bottle elafs. XXII. Fourteen vermilions, weighing 4°ths of a carat, expofed for 2 30%, were completely Fite! into a polifhed opake globule, very like the former, but not quite fo dark. It is alfo not fo round or polithed, having been preffed while foft. A fmall face being afterwards fubjected to the lapidary’s wheel, the {tone appeared as hard as at firft, but not fufcepti- ble of fo high a polith. Garnet. XXIII. One which weighed 1,ths of a carat, expofed to the blaft for 1/ 40", broke in two miedes; both of which be- came fufed. The largeft prefents an appearance very like that of the vermilion No. xx1.; the other is of a dark lead _colour inclining to a bronzy hue and chatoyant, fomewhat like peacoek-lead ore. Both were prefled while foft; the Jatter fo much fo, that it at prefent retains nothing of a glo- bular form. Emeralds. XXIV. One, of the weight of 2°ths of a carat, was fufed in 2’into a globule of an opake Swhite colour without any lofs 264 Experiments refpetting Heat. lofs'of weight. Itexactly refembles. a) peark from a cammion oyfter, or dead pearl,’’ as jewellers term it. XXV. Another cs stwabel weighing 2 =°ths of a carat, being treated for the fame length of time, prefents the fame appear- ance as the former, except that about one-half of the globule flill retains fome traces of its original colour, and is.now of a greenifh gray. Chryfolite. XXVI. A chryfolite, weighing 1°ths of a carat, weing treated during 2° Joft no weight, but became fufed into a rough opake greenifh black gtobule. Jucynth, XXVIT. One jacynth, weighing #4ths of a carat, treated for 1’ 14! loft no. weight, but became fufed into a globule nich refembling one of dark coloured bottle-glafs, but nearly opake. Opal, XXVIII. An opal, weighing *4ths of a carat, treated for 44!’ melted into a polifhed labile of a greenith white almoft tranfparent, but full of {mall bubbles, It loft no weight. Cryflals. XXIX. A cut white cryftal, weighing 72ths of a carat, treated 1’ 44!’ melted into a perfectly tranfparent globule Jike flint glafs, but full of cracks and bubbles. | Its weight is the fame as before. ail XXX. Two fragments. of rock-cry (ial, weighing together x} carat, expofed to the heat during 5’ 19/’ meted together, but flew to pieces on cooling, and the whole.is now in fe- veral frarments; fome of it even in powder. It refembles a very pure white falt. f Platina. XXXI_. Sixteen carats of platina in grains, in the crude fate, were perfectly fufed in a few feconds. A fecond and a third quantity were likewife fufed; but the circumftance moft remarkable was, that the globules thus formed were found to be pure and cigdeables On examining *themrat- tentively it was found that tlre i iron, which is! always prefent in ‘ ~~ ee | peer PP, ae F es Bie as he Experiments refpelling Heat. 985 i tn erude platina, and which, by adhering to it with great _ ebftinacy, makes it difficult to obtain that metal in its pure flate, was completely oxydated, and adhering fo loofely to - the furface of the globules that it feparated itfelf in fcales when they were‘firuck with a hammer. The globules were then extended under the hammer without breaking. From this experiment it appeared probable that means might be devifed to fuse large quantities of crude platina, and at the fame time to obtain the metal pure and malleable; an object fo defirable, that the Society refolved at leaft to make the attemyst. XXXII... A table furnace was conftru€ted in fuch a man- ner, that the crucible containing the platina (eight ounces) could be brought to a ftrong heat, by means of charcoal all. round it anda pair of double bellows, before allowing the fiream of oxygen gas to be introduced into it. The platina __-was put into the centre of the crucible, with charcoal below and all round, in fuch a manner that the crucible was filled _with the charcoal and the metal. The cover was luted on, and a tube, made of burnt clay, which paffed from a hole— near the bottom of the crucible to the outfide of the furnace, was firmly luted into the crucible, which was fupported in the middle of the furnace. The clay tube was connected, by means of another tube, with the large vafometer, and that again with a feries of cafks filled with oxygen gas. After exciting, by means of the double bellows, the fire round the outfide of the crucible, till it was thought the cru- cible and its contents muft have attained the utmoft degree of heat that could in this way be obtained, the communica- tion between the gafometer and the interior of the crucible was opened, and a ftream of oxygen gas forced in through the clay tube among the contents oF Chie crucible. It will be obferved from what has been ftated, that the in- - tention was not to excite the fire in the body of the furnace by means of a fiream of oxygen. That appeared to be an unneceffary wafte. All that was aimed at was, by exciting a fudden and rapid combuftion of the charcoal lodged in the _ erucible along with> the platina, to reduce the latter; and it was thought that the previous ignition of the crucible and its _ contents, by the help of the furnace, would facilitate this, > Voz, VIII. Mm tu 266 Experiments re[pecling Heat. In a few feconds after opening the communication with, the gafometer, fuch a vivid flame iffued through the hole in the cover of the furnace, that it was thought unneceffary to carry the procefs further, as the gas appeared evidently to be acting on the fuel in the furnace, inftead of having its action confined principally, as was intended, to the contents of the crucible. After fome time, the furnace was examined. More than a half of the clay tube which ferved to convey the gas through the furnace into the crucible was found gone, and the remaining portion of the tube polifhed highly on the furface, the clay having been running in a ftate of extreme fufion. The fide of the crucible next the tube was polifhed in the fame manner, and the hole in which the tube had been luted was found greatly enlarged. The charcoal in the crucible had not been half confumed, and the platina was found fufed at the bottom. A few globules were:found in- terfperfed among the charcoal, having been arrefted in their defcent by ftopping the procefs before they had time to reach the chief mafs at the bottom; but it feemed plain that, had the blaft of oxygen gas been continued for a minute or two longer, the crucible would have been completely ran down. ~ The platina was then examined, but the refult was not what the Society had promifed themfelves. Though it had been completely fufed, the procefs was found to have been of too fhort a duration to oxydate all the iron contained in it. The large button broke under the hammer. From this it appears that, though platina, in fmall quanti- ties (Exper. XX XI.) may be reduced and brought to a ftate of purity by oxydating the iron by means of a ftream of oxy- gen gas, it will require a confiderable degree of addrefs to be able to apply this on a fcale of any confiderable extent. If even rock-cryftal, and thofe gems which, till thefesexperi- ments, have been held infurfible, are yet found fufible by the powerful heat excited by the agents employed in them, how are materials to be obtained fufficiently refractory to main- tain the neceffary arrangements in a furnace during fuch a . procefs ? VIL. An Re [ 267 ] VII. An Examination of Sv. Prerre’s Hypothe/is re[petting the Caufe of the Tides, which, in oppéjition to the received Theory, attributes them to fuppofed periodical Effufions of the Polar Ices. By SamuEt Woops, E/g. Read before the Ajkefian Society November 5, 1799. [Concluded from Page 147. ] I NOW proceed to ftate the three remaining proofs adduced by St. Pierre in corroboration of the Ranianiiaka I have jut noticed; but, as I conceive myfelf to have fully difproved the geometrical evidence, I fhall not trouble you with an at- tempt to invalidate thefe fubfidiary confirmations. The fecond proof (fays he) is atmofpherical. It is well known that, in proportion as you afcend amountain, the mercury in the barometer fubfides: now the mercury finks in the barometer in proportion as you advance northward. The weight of one Jine of mercury at Paris is equivalent to an elevation of 10 fathom and 5 icet, whereas in Sweden it is equivalent to Yo fathom 1 foot 6 inches only; and of courfe the ground of Sweden muft be higher. From a feries of obfervations made by captain Cook in the fouthern hemilphere in 1773 to 1775, we perceive the mercury {carcely ever rifes higher than 29 inches beyond the 6oth degree of fouth latitude, aad mounted almoft always to 30 inches and even higher in the vicinity of the torrid zone; which proves that the barometer falls as you recede from the line, and that both poles are elongated, The third proof is nautical, arifing from the annual de-= feent of the ices toward the line, impelled by currents pro- ceeding alternately from each pole during their refpective fummers, immenfe mountains of ice being frequently feen by navigators in low latitudes. The fourth proof is aftronomical. Childrey (an Englith author of note) fuppofes, as I do, that the earth at the poles. is covered with ice to fuch a height as to render its figure fenfibly oval. Kepler fays that the eclipfe of the moon on the 26th September 1624, like the one obferved by Tycho Brahé in 1588, whieh was total, and very nearly central, : Mm 2 differed a6$ Examination of St. Pierre’s Iypothefis differed widely from the calculation: for, not only the dura- tion of total darknefs was extremely fhort, but the reft of the duration, previous and pofterior to the total obfcuration, was fill fhorter, as if the figure of the earth was elliptical, having the fmalleft diameter under the equator, and the greater from pole to pole, Navigators in the north have always feen the elevation of the fun nee the horizon greater the nearer they approach the poles. It is impoffible to afcribe thefe optical effects to atmofpherical refraction. Barents, on the 24th of January, in Nova Zembla, faw the fun 15 days fooner than he expeéted, which would give a refraction of 25°; a thing impoffible, and the circumftance can be afcribed to no other caufe than his real elevation. St. Pierre cuts the difficulty arifing from the different vi- brations of the pendulum, by obferving that they are lable to a thoufand errors. The elongation of the poles being thus demonfirated, the current of the feas and tides follows as a natural and neceflary confequence. Let us now confider the extent of the polar ices, and the powers capable of effecting their folution. The polar ices in the winter proper to each hemifphere are from fix to feven thoufand leagues in circumference; but in their fummer, from two to three thoufand. The ices and fnows form in our hemifphere, in January, a. cupola, the arch of which extends more than two thoufand leagues over the two continents, with a thicknefs of fome lines in Spain, fome: inches in France, feveral feet in Ger- many, many fathoms in Ruffia, and beyond the 60° of north fat. of fome hundred feet. Some ice iflands were feen: by Ellis from fifteen to eighteen hundred feet above the level of the fea, and they probably go on increafing to the pole toa height indeterminable. . Hence the enormous aggregation of water, fixed by the cold of winter in our hemifphere, above the level of the ocean, is clearly perceptible ; and to the pe- riodical fufion of thefe vaft mafles the general movement of the feas and tides is juftly afcribable. The ices at the fouth pole exceed in quantity thofe at thenorth; and two fuch bodies 4 » vefpecting the Caufe of the Tides. 269 bodies of ices, alternately accumulated and diflolved, at the two poles, muft occafion a very perceptible augmentation of its waters at their return to it by the action of the fun, and a great diminution by their reduétion to ice when the fun - fetires. It has been calculated that the earth and fea covered ' with ice, may be equalled to 1-1oth of the whole ocean, and the height of the polar ices is at leaft 600 feet; a mafs which in melting muft add 1-10th, that-is 60 feet, to the level of the ocean. Nature has diftributed fandy zones to affift, at the proper feafon, in accelerating the fufion of the polar ices. The winds in fummer convey the igneous particles with which thefe zones are filled towards the poles, where they allift the fun’s action on the ices. The moon alfo diffolves ice by the humidity of the atmo- fphere. When the moon fhines in winter nights in all her Juftre it freezes very fharply, becaufe.the north wind checks the evaporating influence of the moon: -but if the wind is filled ever fo little, you fee the heavens covered with vapours which exhale from the earth, and you feel the atmofphere foftened. Nature haying determined to indemnify the poles for the fun’s abfence, makes the moon paf{s toward the pole, which the fun abandons: fhe cryftallifes, and reduces iftto brilliant fnows, the waters which cover it; fhe renders its atmofphere more refractive, that the fun’s prefence may be detained longer ’ es y g in it, and reftored fooner to it: and hence alfo there is reafon to conclude fhe has drawn out the poles of the earth in order to beftow on them a longer participation of the fun’s influence, We may judge from analogy the general. effect of the tides: A fource difcharging itfelf into a bafon produces at the fides of that bafon a backward motion or counter current, which car ries {traws and other floating fubftances up towards the fource, Charlevoix (Hitt. of New France) tells us that, though the wind was contrary, he failed at the rate of eight leagues a day up lake Michigan, againft its general current, by the affiftance of its lateral counter-currents. M. de Crevcceur affures us, that in failing up the Ohio, along its banks he made 422 miles in 14 days, or ten leagues a-day, 270 Exaytination of Si. Pierre's Ly pothefit- a-day, by means of the counter-currents, which have always a velocity proportional to that of the principal current. The particular effects obferved in Jakes and rivers commu- nicating with icy mountains, illuftrate the nature of the polat effufions. A kind of flux and reflux in the lake of Geneva, during fummer and towards the evening, is obfervable, occa- fioned by the melting of the fnows, which fall into it after noon in greater quantities than at other feafons of the day. The intermittence of certain fountains ts afcribable to the fame eaufe. The frequent and rapid fluxes (ten or twelve times a day) of the Euripus, the firait feparating Beeotia from Eu- boea, arife from the fame fource. The currents of the ocean are reducible to two general . ones: one, during our fummer, from the north pole, in a fouth direction; the other, during our winter, proceeding northward from the fouth pole. Dampier lays it down as a principle, founded on many ex- periments, that currents are fearcely ever felt but out at fea, and tides upon the coatts. The polar eflufions, which’ are the tides of the north and eaft to thofe who dwell in the vicinity of the pole, or in bays communicating with it, take their general courfe to the middle of the channel of the ‘Atlantic ocean, attraéted toward the line by the dimination of the waters, which the fun is incef- fantly evaporating. They produce by their general current two contrary currents or collateral whirlpools fimilar to thofe produced by rivers on their banks, and the tides may be:con- fidered as vortices of the general current of the Atlantic ocean. : The general current, which flows from our pole in fummer with fo much rapidity, and which is fo violent towards its fource, crofies the equino¢tial line, its flux not. being ftemmed by the eflufions of the fouth pole, at that feafon confolidated ‘into ice; it extends beyond the Cape of Good Hope, and being directed eaft, by the pofition of Africa and Afia, forces the Indian ocean into the fame dire€tion, and may be con- fidered as the prime mover of the weftern monfoon, whicli takes place in the Indian feas in April, and ends in September. The general current, ifuing during our winter from the 3 fouth. ~~ age Sot refpetting the Caufe of the Tides. 27 fouth pole, reftores the Indian ocean to its natural motion welt; crofles, in its turn, the equinoétial line, penetrates into our Atlantic ocean, directs its motion. north by the pofition of America, and produces various changes in our tides. All the bays, creeks, and mediterraneans of fouthern Afia, fuch as the gulphs of Siam and Bengal, the Perfian gulph, the Red fea, &c. are directed relatively to thefe currents north and fouth fo as not to be ftemmed by them; as all the bays and mediterraneans of Europe, as the Baltic, the Englith channel, the bay of Bifcay, the Mediterranean fea, Baffin’s bay, Hudfon’s bay, the gulph of Mexico, and many others, are direéted relatively to thefe currents eaft and weft; or, to {peak with more precifion, the axes of all-the openings of the Jand in the old and new world are perpendicular to the axes of thefe general currents, fo that their mouth only is crofled by them, and their depth is not expofed to the impulfions of the general movements of the ocean. That thefe currents are not the offspring of my own ima- gination, but actually fuch as I have. defcribed them, will appear from various teftimonies. Froger fays that in Brazil the currents follow the fun, running fouthward when he is fouth, and northward when he is north. In the fuinmer of the fouthern hemifphere, the tides fet in northward (Schouten, Jan. 1661), but in winter run fouthward and come from the north (Fra/er, May 1712). C. Columbus fet fail from the Canaries the beginning of September, and fteered to the welt; he found, during the firlt days of his voyage, that the cur- rents carried him to the north-eaft; when he had advanced 200 or 300 leagues from land, he perceived their direction was fouthward : finally, as he approached the Lucayo iflands, he again found the current fetting in north, The nautical obfervations of Cook demonftrate that the currents of the Atlantic ocean are alternate and half-yearly like thofe of the Indian ocean. The beans called Oxeyes, which grow only in the Weft Indies, are every year thrown up on the coatt of Ireland, 1200 leagues diftant. Seeds and turtles are brought to the Hebrides from the Weft Indies and America; and the maft of the Tilbury man of war, burnt at Jamaica, was found on thefe coafts; the current which anh Examination of St. Pierre’s Hypothefis ; which wafts thefe along proceeds in a north direétion, and proves that the Atlantic current comes from the fouth, and fets in north during our winter. The currents of the north . annually convey, in fummer, toward the fouth, long banks of floating ices of very confiderable depth and elevation, which run aground as far fouth as the banks of Newfoundland. Rennefort (June 20, 1666); near the Azores (in lat. 40? to 45°), faw the broken mafts, failyards, &e. wrecked in the engagement which lafied four days between the Englifh and Dutch, from June 11 to 15: this naval combat took place 12 miles to the north-weft of Oftend, about 51° north. The currents from the north had therefore wafted them in nine da¥s 11° fouth, befides a confiderable progrefs weftward. The general current iffuing from the fouth pole divides into two branches; one, fetting in towards the Atlantic ocean, penctrates even to its northern extremity. This part, firaitened by the prominent parts of Africa and America, forms on the coaft two counter currents, which proceed in oppofite directions. One of thefe currents runs eatft, along the coaft of Guinea, to the 4th degree of fouth latitude; the other takes its departure from Cape St. Auguftin, proceeding fouth-weft, along Brafil, to Maire’s Straits. In the middle of the Atlantic ocean, beyond the ftrait formed by the two continents, this general branch pufhes on north, and ad+ vances to the north extremities of Europe and America, . bringing as twice every day along our coafts the tides of the fouth, which are the half daily effufions of the two fides of the fouth pole.. The other branch takes a dire¢tion fouth of Cape Horn, rufhes into the South fea, produces the mon- foon in the Indian ocean, and, having made the tour of the globe, unites itfelf by the Cape of Good Hope to the general. current which enters the Atlantic ocean. In our fummer, commencing toward the end ‘of March, when the fun retires from the fouthern hemilphere, and pro- ceeds to warm the north, the effufions of the fouth pole are ftayed, thofe of our pole begin to fow, and the currents of the ecean change throughout every latitude. The general current of our feas divides alfo into two branches 5 the firft deriving its fource from Waigats, Hudfon’s Bay, &¢, flows with - a a oe J refpefting the Caufe of the Tides: 273 with the rapidity of a fluice, defcends through the Atlantic ocean, croffes the line, and, finding itfelf confined at the fame Strait of Guinea and Brafil, forms two lateral counter cur- rents fetting in north : thefe counter currents produce, on the éoafts of Europe, the tides which appear to come from the fouth. The general currént advances fouth, arrives about the month of April at the Cape of Good Hope, and renders the paffage round this cape fo difficult to veflels returning from India at this feafon ; about the middle of May it reaches the coafts of India, produces the welt monfoon, and, having éncompaffed the globe, proceeds to Cape Horn, re-afcends the coafts of Brafil, and creates a current terminating at Cape St. Auguflin. The other general branch, which receives much lefs of the icy effufions, iffues between the continents of Afia and Ame- rica, and defcends to the South fea, where it is re-united to the firft branch. The ocean accordingly flows twice a year round the globe in oppofite fpiral dire&tions, taking its de- parture alternately from each pole, and defcribes on the earth the fame courfe which the fun does in the heavens. The courfe of our tides towards the north in winter is not an effect of the lateral coufiter currents of the Atlantic ocean, but of the general current of the fouth pdéle, which runs north. In this direétion almoft throughout it pafles from 4 wider fpace into a narrower, and carries before it at once the whole mafs of the waters of the Atlantic ocean, without per - mitting a fingle column to efcape either to the right or left. However, if it mect a cape or ftrait to oppofe its courfe, it would form there a lateral current, as at Cape St. Auguftin, and in Africa about 10° N. Jat.; for in the fummer of the ‘fouth pole the currents and tides return fouth on the Ame- fican, and eaft on the African fide, the whole length of the Gulph of Guinea, in contradiétion to all the laws of the lunar fyftem. From thefe polar éffufions the principal phenomena of the fides may be explained. It will be evident, for example, why thofe of the evening fhould be ftronger in fummer than thofe of the morning; becaufe the fun aéts more powerfully by day than by night on the ices of the pole on the fame meri- . Vou, VIII, Na dian an4 Examination of St, Pierre’s Hypothefis dian as ourfelves: and alfo why our morning tides in winter rife higher than thofe of the evening, and why the order of our tides changes every fix months; becaufe, the fun being alternately towards both poles, the effect of the tides muft be oppofite, like the caufes which produce them. At the fol- {tices the tides are lower than at any other feafon of the year; and thofe likewife are the feafons when there is moft ice on - the two poles, and confequently leaft water in the fea: the reafon is obvious, the winter folftice is with us the feafon of the greateft cold; of courfe there is the greateft poffible ac- cancun of ice on our pole and hemifphere. At the fouth pole it is indeed the fummer folftice ; but little ice is then melted, becaufe the ation of the greateft heat is not felt there as with us, till the earth has an acquired heat fuper- added to the fun’s aG@tion, which takes place the fix week¢ following the fummer folftice. At the equinoxes, on the contrary, we have the higheft tides ; and thefe are precifely the feafons when there is leaft ice at the two poles, and of courfe the greate{t quantity of water in the ocean. At our autuninal equinox in September, the greateft part of the ices of the north pole is melted, and thofe of the fouth pole begin to diffolve. The tides in March rife higher than thofe in September, becaufe it is the end of fammer to the fouth pole, which contains much more ice than ours, and confequently fends a greater mafs of water to the ocean. I fhall fay nothing (he proceeds) of the intermittence of. the polar effufions, which produce on our coaft two fluxes and two refluxes nearly in the fame time that the fun, making the circuit of the globe, alternately heats two continents and two oceans, that is, in the fpace of 24 hours, during which his influence twice aéts and is twice fufpended ; nor fhall fpeak of the retardation, which is nearly 3 of an hour every day, and which feems regulated by the different diameters of the polar cupola of ice, whofe extremities, melted by the fun, diminifh and retire from us every day, and whofe effufions muft confequently require more time to reach the line, and to return from the line to us. ‘Nor fhall I dwell on the other. relations thefe polar periods have tothe phafes of the moon, efpecially re[petting the Caufe of the Tides, , vA {pecially when fhe is at fall; for her rays poflefs an evapo- rating heat, as the late experiments at Rome and Paris fully demonftrate * ; much lefs {hall I involve myfelf in a difeuflion of the tides of the foutk pole, which in fummer in the open fea come in vaft furges from the fouth and fouth-weft. There are two tides every day; becaufe the fun warms by turns, every 24 hours, the eaft and weft fide of the pole in fufion. Precifely the fame effe& takes place in lakes fituated in the vicinity of icy mountains, which have a flux and reflux in the day-time only. But it cannot be doubted that, if the fun warmed, during the night, the other fide of thefe mountains, they would produce another flux and reflux; and confe- quently two tides in 24 hours, like the ocean. We are not to imagine that every fide is a polar effufion of the particular day on which it happens, but an effect of the feries of polar effufions; fo that the tide which takes place on our coafts to-day, is perhaps part of that which took place fix wecks ago. But here, too, muft we admire the harmony of nature: the evening and morning tides take place on our coafts as if they iflued that very day from the higher and lower part of our hemifphere; and the tides of fummer are precifely oppofite to the tides of winter, as are the tides from whence they flow; our evening tides In fum- mer, and our morning tides in winter, being greateft, If the tides are ftronger after the full moon, it is becaufe that luminary increafes by her heat the polar effufions, ‘and confequently the quantity of water in the ocean. Let us now explain why the tides of the South fea do not refemble thofe of the Atlantic ocean. The irregular effufions of the poles, not being narrowed in the fouthern hemifphere, as in ours, produce on the fhores of the Indian ocean and South fea expanfions vague and intermitting. The fouth pole has not, like the north pole, a double continent, which feparates into two the divergent effufions daily produced by the fun: it has no channel in pafling through which its effluxes fhould be retarded: its effufions accordingly flow di- rectly into the vaft fouthern ocean, forming on the half of that pole a feries of divergent emanations which perform the * I do not know where any account of thefe ftrange experiments can be foynd.—W. Nnga tour 276 Examination of St, Pierre's Hypothefis tour, of it in 24 hours, like the rays of the fun. When a bundle of thefe effufions falls upon an ifland, it produces there a tide of twelye hours, 2. e. of the fame duration with that which the fun employs in heating the icy cupola through, which the meridian of that ifland paffes; fuch are the tides of the ‘iflands of Otaheite, Maffafuero, New Holland, New Britain, &e.: each of thefe tides lafts as long as the courfe of the fun above the horizon, and is regular like his courte. / In the nothern part of the South fea the two continents approach; they pour therefore by turns, in faummer, into the channel which feparates them, the two femi-diurnal effufions of their pole, and there they collect by turns, in winter, thofe of the fouth pole, which produces two tides a day as in the Atlantic ocean. But as this channel about the 55° of N. lat. ceafes to exift by the fudden divergence of the continents of Afia and America, thofe places only fituated in the point of divergence of the northern parts of thefe two continents ex- perience two tides a day. Such are the Sandwich Iflands, Where fuch places are more expofed to the current of the one continent than the other, its two femi-dijurnal tides are un- equal, as at the entrance of Nootka Sound: but when it is completely out of the influence of the one, and entirely under that of the other, it receives only one tide of twelve hours every day, as at Kamtfchatka. Thus, two harbours may be fituated in the fame fea under the fame parallel, and one of them have two tides, and the duration of thefe tides, whe- ther double or fingle, double equal or double unequal, regu- lar or retarded, is always 12 hours every 24 hours, 2. ¢. pre- cifely the time the fun employs in heating that half of the polar cupola from whence they flow ; which cannot poffibly be referred.to the unequal courfe of the fun between the tro- pics, and much le{s to thatof the moon, which is frequently but a few hours above the horizon of fuch harbours. All iflands are in the midft of currents: on looking therefore at the fouth pole with a bird’s-eye view, we fhould fee a fuc- ceffion of archipelagos difperfed in a fpiral line all the way to the northern hemifphere, which indicates the current of the fea, juft as the projection of the two continents on the fide ef the north pole indicates the current of the Atlantic. Thus, ; the refpecting the Caufe of the Tides. -- 277 the courfe of the feas from one pole to the other is in a fpiral line round the globe, like the courfe of the fun from one tropic to the other: admitting therefore the alter- nate fufion of the polar ices, all the phanomena of the tides and currents of the ocean may be explained with the greatelt facility. I have then eftablifhed by facts fimple, clear, and nume- rous, the difagreement of the tides in moft feas with the moon’s action on the equator, and their perfect coincidence with the fun’s action on the polar ices. I have no doubt various objections may be urged again this hafty explanation of the courfe of the tides, &c. But thefe phyfical caufes prefent themfelves with a higher degree of probability, fimplicity, and conformity, to the general progrefs of nature, than the aftronomical caufes by which it is attempted to explain them.—Thus far St. Pierre. I hefitate whether I ought not to apologife for occupying fo much of your time and attention in the detail of a theory which may be deemed unworthy of ferious notice; yet I flatter myfelf it will afford an opening to curious and intereft- ing difcuffion. St. Pierre complains that the prejudices of mankind are fo ftrong in favour of received opinions, that he cannot obtain a hearing, To the beft of my judgment I have offered a fair and can- did expofition of a hypothefis which he has drefled up with fome eloquence and much declamation, and ufhered into the world with a folemn and impofing air of confidence and af- furance, tolerably well calculated to confound the ignorance and candour of his readers. I am not confcious of having omitted any material fact or argument which tends to the fupport and elucidation of his theory; I have negleéted much abfurd reafoning, yet not without retaining fome curious {pecimens. I did once intend to have entered into a ge- neral examination of his principles and reafoning ; to have fhown the fallacy of the former, the inconclufivenefs and inconfiftency of the latter; but I fhall now be fatisfied with offering a few fats and obfervations extracted from the 2d and third voyage of Captain Cook, which appear to me de- cifive of the queflion, Captain 298 Examination of St. Prerre’s Hypothejis Captain Cook, who fpent three fummers as near as the icé would permit his approach towards the fouth pole, found on December 14, 1772, and from that date to the beginning of January 1773, in latitude from 55° to 64° fouth, a vaft compact body of ice which. prevented his further pro- grefs. The thermomeier varied from 30° to 35°. Being immerfed 100 fathom deep for about 20 minutes, it came up 34°; and on the r3th of January 1774, on a repetition of this experiment, the open air being 36°, the furface of the fea 331°, the thermometer came up 32% They found water generally freeze at 33°. We certainly had no thaw, (fays he,) the mercury keeping ufually below the freezing point. Being near an ifland of ice (December 24, 1772) 50 feet high and 400 fathom in circuit, I fent the mafter in the jolly boat to fee if any water ran from it. He foon returned with an account there was not one drop, or any other appearances of thaw.”? And in the fummer of 1774—75 his experience was nearly fimilar. On the 13th of February 1775, the thermometer fiood at 29°. In his 3d voyage to the north-weft coaft of America, on the 17th of Auguft 1778, in lat. 70? 44’, they were ftopped by a field of ice 10 or 12 feet high, as compact as a wall; ‘ further north it ap- peared much higher; here and there we faw upon it pools of waters we tried, but found no current. July 7, 1779, lat. 69° ftopped by a large field of ice, prefenting a great extent of folid and compact furface not in the fmalleft degree thawed ; the thermometer ftood at 31°.” << As far as our experience went, the fea is clearer of ice in Anuguft than in July, and perhaps it may be {till freer in a part of September. We tried the currents, and found them never to exceed a mile an hour; we found the month of July infinitely colder than Auguft ; the thermometer in July was once 28°, and very commonly 30° ; whereas it was feldom as Jow as the freezing point in Auguft.” *¢ J am of opinion (fays Captain Cook) that the fun con- tributes very little towards reducing thefe vaft maffes of ice ; for, although that luminary is a confiderable time above the horizon, it feldom fhines out more than a few hours‘at a time, and often is not feen for feveral days in fucceffion. It js the wind, or rather the waves raifed by the} wind,. that reduces 4 the New Publication. 275 the bulk of thefe enormous maffes, by grinding one piece againft another, and by undermining and wathing away thofe parts that lie expofed to the free 3 and more ice may be deftroyed in one ftormy feafon Gani: is formed in feveral winters, and its accumulation thus prevented.” This evidence clearly proves that the fun’s influence at the. poles, fo far from being equal to produce a conftant and uni- form effeét, creating an impulfe extending its effect to the remoteft parts of our globe, and a daily elevation of feveral. feet to the waters of the ocean, is not fufficient in the hotteft period of {ummer to diffufe a fenfible thaw ;, and thus we are eonvinced that a few plain and fimple faéts are of much greater avail than a multitude of fanciful conjectures. NEW PUBLICATION. A Manual of a Courfe of Chemiftry ; or, a Series of Experi- ments and Illuftrations necefJary to form a complete Courfe of that Science. By J. B. Bourtyon Laeranee. ProfefJor in the Central Schools of Paris, €¥c. Tranflated from the French, with 17 Plates. 2 Vols. 18 Shillings. Cuthel, and Vernor and Hood, 1800. W: have perufed this work with much pleafure. It is comprehenfive, though concife; and the manner in which the author treats his fabjee i is well calculated to give to thofe who with to ftudy chemiftry, not only a knowledge of the theory, but alfo, which ought to be the chief aim of every work of this kind, of the. procefles and manipulations as applicable to the arts and the common purpofes of life. The apparatus employed in modern chemiftry is defcribed with confiderable accuracy and clearnefs, and illuftrated with appropriate engravings; but in the original, the conne@ion and relation of all the parts, though very correétly given in out- dine, are not fufficiently apparent and obvious, “necalle to tyros. The Englith publithers have done juftice to the work, , and even a fervice to the feience of chemiftry, by haying their plates properly thaded and highly finifhed. It is enough of 280 New Publication. of them to fay, that they are from the graver of Lowry, and equal in merit and execution to thofe given in the Phi- Jofophical Magazine. The tranflator, who has not given his name, has performed his tafk in a manner creditable to himfelf. He has fhown himfelf fomething more than a mere literary drudge: he has corrected feveral overfights of the author, or rather, perhaps, inaccuracies of the French printer, which, though often only a fingle letter in the name of a compound body, were of im- portance. The terminations in afes, and ites, and ats, fo ufeful in the modern nomenclature, have this inconvenience— they are fo nearly fimilar, that printers, not chemifts, will often fubftitute the one for the other. We fpeak this from experience, and we may be allowed to take this opportunity of recommending to chemical authors always to revife after the printer before their fheets are put to prefs. _ A fhort appendix has been added by the tranflator, con- taining fome ufeful notes and notices of new faéts difcovered fince the original work was publithed ; and alfo feveral tables of French weights, &c. We hall here give a few extraCts, which, at the fame time that they ferve as a fpecimen of the work and of the tranfla- tion, will furnifh information or amufement to fome of our readers. Fluoric Acid. ~ For our knowledge of the fluoric acid we are indebted to Schecle. This appellation was given to it becaufe it is extracted from a kind of earthy neutral falt, known under the name of Jparry fluor, phofphoric mineral, fluate of lime. As the fluoric acid diffolves glafs, it 1s neceflary, when you wifh to have it pure, to employ for that operation veffels of a metal on which neither it nor the fulphuric acid exer- cifes any aétion: lead, among the known metals, is that which is beft fitted for this purpofe. There are two methods of preparing this acid: 1ft, With a metallic apparatus: 2d, With a olafs-apparatus. ift, To obtain the fluoric acid alone, and free from every combmation, put one part of the fluate of lime, reduced to powder, New Publication. 281 powder, into a Jeaden retort; pour over it three parts of ful- phuric acid, and adapt to the retort a leaden receiver half full of water. The operation is performed with a balneum mariz ; and for this purpofe you put the retort into a cop> per or iron veffel containing water, or into a falt-bath; you then expofe the apparatus to a gentle heat, and the fluoric acid, in proportion as it is difengaged, will be abforbed by the water in the receiver. For this purpofe, inftead of a receiver, you adapt to the orifice of the retort a bent tube of lead, the extremity of which is introduced under a mercurial pneumatic apparatus. 2d, When this acid is made by means of a glafs appara- tus, you employ a retort, having adapted to it a tube in- ferted in a bottle containing diftilled water. As this acid has the property of diffolving glafs, it feizes on the filex, which appears under the form of white flakes. Care mutt be taken to employ large tubes, efpecially when you operate with glafs, as for want of a fufficient paflage the gafeous acid is compreffed in the retort, and its aétion on the glafs is augmented, fo that the retort will be foon cor- roded through. The filex. depofits itfelf in the water, becaufe the latter has more affinity for the acid than the acid has for the filex. If you preferve fome of this gas under a giafs bell, it will diffolve the filex of the glafs. If you plunge inte it an extinguifhed taper, an incrufta- tion will be formed on the wick, becaufe the water which iffues from it diffolves the furrounding acid charged with filex, and the filiceaus earth is precipitated upon it from this folution. This gas is heavier than atmofpheric air; it extinguifhes a lighted taper, kills animals, reddens blue vegetable co- jours, and has a penetrating fmell, which approaches near to that of muriatic acid gas. It corrodes the fkin : it undergoes no alteration from hight. In contaét with the air it emits white fumes. If you ex- pofe to the vapour of this gas in an earthen veffel animals, bits of fponge a little moiftened, charcoal, &c. the moifture Vou, VIII, Co they 282 New Publication. they contain will diffolve the acid, and the filéx will be pre- cipitated upon them. If this experiment be made in a metal veffel, the fame in- cruftation will not take place. It thence refults that the earthy fubftance which 1s pre- cipitated by the contact of the fluoric acid gas and the water, is nothing elfe than a portion of the glafs, which is attacked and a¢tually diffolved by the aériform acid. It often happens alfo, that when this gas is made to pafs into water, the filex is precipitated in a quartzy pellicle. Each bubble of the acid which touches the water is imme- diately enveloped in filex, and leaves on its way as it afcends to the furface of the water, traces in the form of tubes, which Prieftley calls organ-pipes, and which decreafe to a point upwards, becaufe the bubble decreafes in proportion as the water diffolves it, and the filex is thus carried off. The filex depofited in the veffels is foon after re-diffolved by the excefs of acid, in proportion as the water is faturated ; for the water, being at firft little faturated with the acid, has not fufficient ftrength to hold the filex in folution. Bergman obtained fluate of filex in a cryftallized form. When the fluoric acid is made in earthen veffels, you will have filex depofited, and then re-diffolved by the re-aétion of the acid: this is a real fluate of filex inftead of pure flu- oric acid. Alkalies may be employed for deteéting the prefence of the filex. The tafte of this acid, diffolved in water, is like that of the fulphuric acid diluted with water, or of vinegar. If a folution of fluoric acid in water be expofed to heat, part of the acid is volatilized; but the laft molecule adhere fo ftrongly, that the water and the reft of the acid are vo- latilized, if the heat be increafed. This acid is preferved in bottles covered on the infide with wax diffolved in oil, or in veffels of lead or of platina. Guyton employed this property to engrave labels on bot- tles, and in particular on thofe deftined to hold acids, the Jabels of which when made of paper are always burnt. The elements of this acid are fill entirely unknown, ~ [To be continue, | INTEL, [ 283] INTELLIGENCE, AND MISCELLANEOUS ARTICLES. ‘ LEARNED SOCIETIES. ROYAL SOCIETY OF LONDON, eS fittings of the i7th November, the 11th and 18th December, were occupied in reading an interefting paper on the mechanifm of the eye, by Dr. Young: St. Andrew’s day falling on a Sunday, the anniverfary meeting was held on the 1ft of December. The auditor’s report on the ftate of the finances of the Society was read. The names of the new members, thofe deceafed, and thofe withdrawn, were declared; and the names of the officers juft élested were announced. The Right Hon. Prefident then addreffed the Society, congratulating them on the progrefs of fcience in the laft year, and concluded by informing them that Sir Godfrey Copley’s medal was adjudged to Mr. H. Howard for his paper on fulminating mercury. Sir Jofeph Banks then informed the Society that Mr. Howard had alfo difeovered a new fulminating filver, aud is now en- gaged on a fubject that promifes to prove highly interefting to meteorologifts and mineralogifts, namely, the analyfis of ftones that have fallen from the clouds. SOCIETY FOR THE ENCOURAGEMENT OF ARTS, MANUFACTURES, AND COMMERCE. , This Society, which has rendered much fervice to the arts by its numerous premiums, that its efforts may, if pof- fible, be rendered ftill more generally ufeful, has juft circu- lated the following notice : Qos Adelphi, 284 ‘Board of Agriculture. ‘Adelphi, Dec. 8, 180. Bharsdiims by the Society for the Encouragement of Arts, Manufaétures, and Commerce. The time of propofing and publifhing the premiums to be given by this Society for the enfuing year now approaching, the patrons of the arts, and all ingenious men, are hereby invited to fugge(t new objects, to which the Society ag extend its liberality. ~ Communications are requefted to be made in writing, and addrefled to the Society’s fecretary, at their houfe in the Adelphi, on or before the 1ft of February 1801. N.B. The 18th volume of the Tranfa@tions of this Society is now in the prefs, and will fpeedily be publifhed. By order, CHARLES TAYLOR, Sec. BOARD OF AGRICULTURE. This Board has juft publifthed the following lift of pre- Miums: This Board having been required, by a cornmittee of the Foufe of Lords, ‘ to examine into, and report to their lord- thips, the beft means of converting certain portions of grafs land into tillage, without exhaufting the foil, and of return- ing the fame to grafs, after a wei period, in an improved tate, or at leaft without injury ;’ and being defirous that theit information, on a fubject of fo great importance, fhould be ‘complete, adapted to every fort ‘of foil, and founded on the, moft ample experience, have come to the refolution of offers ing the following premiums for that purpofe, v7z. To the Beton’ who fhall produce, on or before the firft day of February 1801, the beft and moft fatisfactory effay on the fubject before mentioned, diftinguithing, refpectively, what part of the plan recommended, or of the details given, is the cefult of aétual experiment, accurate obfervation, or well authenticated information, 200/. For the fecond beft, 1004. For the third beft, 60/7. For the fourth beft, 40/7. And to fuch perfons who may communicate information, which, though ufeful, may be confidered of Jefs importance, fmaller rewards, proportioned to-the opinion of the Board. + It Board of Agriculture. 285 Tt is required that each effay fhall fully detail the courfe of crops, regard being had to the varieties of foil, and the time propoled for continuing the land under tillage. Alfo, to explain the cafes in which it may be eligible to drain land previous to tillage. In what cafes paring and burning are advantageous, with di- Feétions thereon, regard being had to the fubfequent cropping. The depth to which grafs lands fhould, at firft breaking up, be ploughed. Whether the crops intended for cattle and fheep are to be fed on the land, and by which kind of ftock, or carted off. To ftate the crop with which the grafs feate in each cafe eught to be fown, when the land fhall be again laid down :— The forts and quantities of grafs feeds for éach kind of foil, and whether to be provided by landlord or tenant :—Whe- ther it be beft to mow or feed the grafs in the firtt year after laying down; to detail the management in each cafe :—The manuring which may be thought neceflary :—The principle on which an increafe of rent ought to be eftimated, where permiffion may be given to break up old pafture now under leafe. The Board requires that thefe objects fhould be particularly attended to, with relation to the leading qualities of land, viz, —Clay, tm all its difinétions; and foils too ftrong or wet for turnips :—Loam, in all its diftlinGtions, fit for turnips :—Sand, including warrens and heaths, as well as rich fands :—Chalk land and downs :—Peat, including moory, fedgy, rough 0 toms, and fens. It is hoped that no perfon will be deterred from commu- nicating bis knowledge to. the Board on account of his expe- rience being confined to one of thefe foils only. The Board referves the power of withholding any premium, in the cafe of no effay being deemed fufficiently i importarit to merit it. ' The effays which fhall obtain any premium, or other res ward, to remain the property of the Board. Each effay to be fent (fealed) without any name, but with a mark or motto; and accompanied by a fealed letter with the fame mark or motto, containing the name and addrefs of the 286 French National Inflitite. the author; and this'letter will not be opened, unlefs on¢ of the prizes, or fome other reward, fhall be adjudged to him. . All communications to be addreffed to Lord Carrington, prefident, Sackyville-ftreet. FRENCH NATIONAL INSTITUTE: The following account of the labours of the Phyfical and Mathematical Clafs during the aft three months of the year 8 was read by C. Delambre. C. Meiffier has given a cufious comparifon of the fummer of the year 1800 and that of the year 1792: It refults frovit his obfervations, that if the duration of the heat was nearly the fame at each of thefe periods, it is certain that im the year 1792 the thermometer kept, pretty conflantly, two de- grees and a half higher than in the year 18003; but what renders the Jaft fammer more remarkable is, the extraor= dinary lownefs of the water of the Seine. In the year 1792, the water, for two months and a half, kept, pretty ¢onftantly, at about an inch above zero of the feale on the bridge de la Tournelle. During four days only, © it funk fo low as zero. On the 11th of Auguft laft it was ftill lower by 4°9 inches. On the 20th of Auguft it was even 7°65 inches below zero. It appears, then, that in the year 1800, the depreffion of the water of the Seine was fome- thing more than fix inches greater than it was in 1792. The year 1719 was remarkable alfo for a long drought and deprefiion of the river. During the whole of that year there fell no more than nine inches four lines of water at the ob+ fervatory of Paris, which is not the half of the ufual quan- tity. The depreffion of the water appeared then fo extraor- dinary, that, to preferve the remembrance of it, the feale of the bridge La Tournelle was conftru@ed. Thts precaution, however, did not prevent us from having 325 millimetres of uncertainty in regard to the level of the Seine at that period. According to Parcieux, the depreffion of the water in 1719 was indicated by the zero of the feale. According to Buache, it correfponded to the firlt foot of that feale. Meiflier is in- clined to adopt the latter indication. But however this may be, it is certain that in the year 1899 the river fell lower 9 than French National Inftitute. aby than at any period ever remembered. According as we follow the one or the other of the two authors above mentioned, the difference will be 16 or 48 C. Meiffier read alfo a note on the eclipfe of the moon which took place on the firft of O&ober lat. The clouds prevented him from obferving the commencement of it. Towards the middle the moon appeared at certain intervals ; and he took advantage of thefe moments to meafure twelve times the part eclipfed. At 1s h. 21’’the eclipfe feemed to be at an end: it was more certainly fo at 11h. o! go’, Ac- cording to the obfervations of C. Delambre, the end took place about 11h. o! 30/; which agrees pretty well with what might have been expected, C. Prony read a memoir containing a defcription and the analytical theory of a new infirument, proper for meafuring the length of a pendulum that fwings feconds. It is well known, that the ufual method requires the niceft attention, not only in regard to the form of the body made to ofcillate, but alfo that the ofcillations may not be prolonged beyond two hours at moft, and that the refults deduced from them may be always fubordinate to the regularity of the time-piece which ferves for comparifon ; and in the laft place, the ne- ceflity of fitting up, and taking to pieces the apparatus, may leave fome doubts refpeéting the identity of the experiments made at different times, and in different places. All thefe inconveniences C. Prony propofes to remedy. His new inftru- ment fuperfedes the neceflity of paying attention to the form of the ofcillating body ; the mafs of it is too confiderable for the ofcillations to continue during the whole time that elapfes between two confecutive paflages of a ftar over the fame vertical, fo that the time-piece of comparifon is of no further ufe than to count with more facility’ the ofcillations pf the pendulum ufed for the experiment. The theory of C. Prony appears to be clear and fatisfac- tory, and he foon intends to fubjeé&t his new pendulum to a trial. The ingenious method by which Borda found means to correct or obviate the inconveniences of the common method are not yet forgotten. His determination of the length of the pendulum received the approbation of all 7 learned 383 French National Injfiitute. Jearned men, affembled at Paris, for fixing the new meafures. Tf it be difficult to attain to greater precifion, it will at leaft be interefting to fee how far the refults obtained are confirmed by a method abfolutely different, C. Flaugerges read feveral memoirs, containing obfer- vations on various fubjects; as, on the phofphorefcence of earth worms; on the effects of thunder ; on ‘halos, or Jumi- nous rings around the fun; experiments tending to prove that the fhadows of opake bodies, expofed in the open fields to the light of the fun, when the fky is ferene, and projected on a white furface, are always blue, or, more correétly, of the colour of the heavens; and, in the la{t place, experiments from which it refults, that the waves, produced at the furface of the water by percuflion, do not produce a movement of tranflation in the parts of the fluid, as bas been believed, ac-" cording to Newton, but only a continued depretiion of intu- mefcence, which is afterwards propagated circularly, C. Briffon has publithed Phyfical Principles of Chemuftry, deftined as a fapplement to his Principles of Natural Philo- fophy. The author compofed this work chiefly for the ufe of the ftudents in the central {chools, It contains, in a clear and methodical order, an account of all the fubftanees which fall within the province of chemiftry, an analyfis of them, their fpecific gravities and other moft remakable pro- perties, with a defeription of the principal kinds of apparatus — employed for chemical experiments*. C. Lacroix has publithed his Treatife of Differences and Series, forming a continuation of his Treatife on the Differ- ential and Integral Calculus. This important work com- prehends in one fyltem the methods fcattered throughout dif- ferent academical collections, and in the works of the greateft geometricians of modern times. The fame author has publifhed a fecond edition of his Treatife of Trigonometry, and the application of Algebra to Geometry. C. Arboguft has juft publithed a large work, entitled The Calculus of Derivations. The author gives the name of de- rivations to quantities deduced from each other by an uniform # We are happy to learn that a tranflation of this very ufeful work is wow ip the prefs, and will {oon be published. procefs French National Inflitute. a8 procefs, which has a great refemblance to that ufed for finding the differentials of all the orders. This procefs he applies to different polynonidus quantities s ; he teaches the method of finding the derivations in their greateft fimplicity, and of forming them almoft without any other trouble than that of writing them. Each term of the refolution may be obtained directly, and without being obliged to pafs through the intermediate ones. This new caleulus may be applied to fimple and double recurring feries, and to the general recurrence of feries. It will ferve often alfo to give more generality to known the+ orems, more vigour and brevity to demontftrations ; in 2 word, it is of the greateft utility in the differential and siblreat calculus, w hieti indeed forms only a peculiar cafe of the calculus of derivations. The foreign members of the commiffion of weights ang meafures continue their information refpecting the intereft with which their different governments receive the models of the metre and chiliogramme. M. Bugge, director of the obfervatory and of the board of longitude’ at Copenhagen, informs us that thefe two models have been conimitted to his care. C. Tralles, the deputy from Helvetia, and the mi- nifter of arts and feiences for that republic, gives reafon to hope that the metric fyftem will be adopted in that coun~ try. All thefe letters have been printed. We muft not here ‘omit a circumftance which adds to our hopes in regard te Helvetia; which is, that, by a fortunate chance, there exifts avery fimple and remarkable relation between the metre and the Zurich foot, one of the moft ufual meafures in Swifferland, This foot is exactly equal to three decimetres, or at leaft it does not exceed it but by two centi- Mikintizes, that is to fay, by a little Jefs than the hundredth part of a line—a quantity that may be negleéted in commerce, and which is often inappreciable even in the niceft operations of the phyfical fciences. | You, VIN. Pa. 10K OU AAO R = 290 ip: Natural Hiflory. Medicine. MISCELLANEOUS ARTICLES. NATURAL HISTORY. Cc. Guerfant, profeffor of natural hiftory at Rouen, ‘tranf- mitted lately to C. Cuvier, for the purpofe of examination, a quantity of bones found, in the rocks in the environs of Honfleur, by the late Abbé Bachelet, and which belonged to the cabinet of the central fchool of Rouen. C. Cuvier has difcovered among thefe bones thofe of a kind of croco- dile, hitherto unknown, aad very different from the foffil animal of Maeftricht, which fome confider asa crocodile alfo. The jaw-bones of this crocodile of Honfleur refemble in their prolongation thofe of the cavial, only the teeth are not fo equal, and the futures of the bones are differently figured. The moft {triking difference is in the vertebra; thofe of all the known eecadeles have the anterior face of their body concave, and the pofterior convex; in that of Honfleur it is precifely the contrary. The apephytes of thefe vertebrze are alfo more complex than in the ordinary crocodiles, This animal appears to be about 18 feet in) length ; its bones are petrified, and ftrike fire with fteel. Their hollow parts are filled with pyrites. .They were found in a.marley kind of ftone, very hard, of a grayith colour, and from which they could not be difengaged without difficulty. Befides the bones of this crocodile, C. Cuvier has found others which feem to arife from fmall animals of the cetaceous kind. MEDICINE, : Whii¥ The following account of a very fingular difeafe which attacks men and animals in the province of Chiacas, in. the government of Potofi, is extracted from the journal of Lima: *< The malady, which Dr. Como Rueno calls furtoa locura, is one of the moft remarkable facts in the hiftory of this province. It is chiefly in the village of Tutari that it at- tacks men and animals, but among the latter thofe (fuch as the ox, horfe, fheep, &c.) which have been brought from Europe; for the vigogne, the guanaco, and other quadrupeds “af pe SpNPLYs are not expofed to it, No force caneftrain 4 a perfon Cure for the Stone.—Chemifiry. 20% @ ~ perfon attacked | by this difeafe, during the firft fits of phrenfy. ' Being totally a ftranger to eheiesens of fhame, he efcapes from bed, and runs with violence to the mountains. He flies from p: ‘ecipice to precipice, and at laft throws him- felf from the firft iieep rock he finds in his way. In general the unforitinate wretch is dafhed to pieces; but if, by fome uncommon chance, the fall does not prove mortal, be foon recovers his reafon and health, and has nothing more to fear from a return of this fatal ifiilatly! I thall not attempt, fays the author, to inquire whether the mineral effluvia which rife from the bofom of the earth in a country expofed to vol- cani¢ conyulfions, may not have as great a fhare in this phenomenon as the conftitution of ‘the inhabitants; but what is certain is, that it often makes its appearance f the province. This fa&, adds he, has fo much analogy with what we read in Ovid’s Metamorphofes refpecting the leap of Leucade, that the one would feem to have ferved as the original of the other. Who knows, fays he, whether the ‘antient fable may not have originated from fome malady fimilar to the above ? A furgeon of Madrid has been able to diffolve camphor in water by means of the carbonic acid. This camphorated folution, injected into the urethra of perfons afflicted with the ftone, allaySyhe pain almoft inftantaneoufly. ‘ CHEMISTRY. Mr. Hahneman, of Altona, has difcovered a new fixed al- kali, which he calls pnewm, becaufe, when heated to rednefs, its volume is extended to twenty times its ufual fize. It cryf- fallifes in large prifmatic hexaedral cryftals terminated by two inclined faces, one of which appears to be triedral, and the other pentaedral. Thefe cryftals neither run per delie guium. nor efflorefce; but when pulverifed they diffolve at 300° of Fahrenheit in half their weight of water, and melt almoft in their water of cryftallifation, At 65° of the fame thermometer, 140 parts require for their folution about 500 parts of water. By cold they feparate from the water. They do not diffolve in alcohol. This alkali produces but little effervefcence with concentrated acids, With vitriolic acid it forms az - pg 292% Meteorology. > forms a falt not foluble in alcohol, and with. difficulty i water. The neutral falts. formed: with this alkali, and the. nitrous, muriatic, and phofphoric acids, and thofe in parti- cular formed with the acetous acid, diffolve with eafe not only in water but in alcohol. Its muriate eryftallifes in.the form of feathers: its phofphate has a bitter tafte. All thefe falts, except thofe formed by the phofphoric acid, part with their acids by heat, and the alkali remains pure: the fulphate requires for that purpofe a red heat; the nitrate only 300° of Fahrenheit: it does not detonate on ignited coals; nor does it decrepitate, or become luminous, when thrown on them. It is difficult to faturate this alkali with carbonic acid, as it lets it efcape in the ufual temperature ef the atmofphere: when faturated with it, it aflumes the form of a light earthy falt. This alkali exercifes an action on vegetable colours. It precipitates metals and earths from their folutions in acids, and in the fame manner as the other alkalies. It produces no change on mercurius dulcis, but it gives to corrofive fublimate the colour of carmine. It precipitates the nitrate of mercury black. When combined with oils, it forms a foap which diffolyes in alcohol. Lime, precipitated by it from muriate of lime, is foluble in diftilled water. It does not decompofe muriate of ammonia but at a heat of 100° of Fahrenheit. METEOROLOGY. During the violent ftorm on Sunday the gth of November laft, the mercury in a barometer at Walthamftow, Effex, was very vifibly agitated; the vibrations up and down were. perhaps about four hundredth parts of an inch. This vibra- tion was obferved by feveral perfons, and was feen at different periods of the day, during which the mercury rofe very Cony, fiderably. The fame circumftance was obferved in other places, THE - PHILOSOPHICAL MAGAZINE, , and Br = —— 3 am % the Infinitefimal Calculus, 341 I know very well that I am committing an error, and I put the equations, mentally, fo to ar yn? this form, MZ MP = TP +9; and “Uo. @ and 9/ being fuch quantities as af pir ie ay eee want to render them exact. In like manner, in the equation DP. a , refulting from the above two imperfect equa- MP = TP tions, I underfland the quantity e”, being fuch that eS Nive 2) + 9! = 0, may be an exact equation. But I know well enough, that this laft quantity 9” is equal to zero; or, at leaft, that it is only an infinitely fmall quantity, fince no infinitefimal enters into the firft term. Now this cannot happen, untefs each of the terms, taken feparately, be equal to nothing; whence I conclude, that I have exa&tly ——— z= —— ; ; fo that the quantities g, g/ and 9! have not been fupprefed as nullities, but only enderflood, in order to fimplify the calculation, Again: if X, for example, be an arbitrary quantity, which may be rendered as fmall as we pleafe, and if there were given an equation of this form, A+ BX + CX? + &. = 4, A, B, C, &c. being independent on X, this equation cannot exift, unlefs it: be A =o, B= 9, C= 0, &c.; ‘that is,. unlefs each term, taken feparately, whatever be their num- ber, be equal to zero. And, for the fame reafon, if we have an equation of this general form, P+ 92 = 0; fo that P may be a funétion of the quantities given or determined by the conditions of the problem; and, on the other hand, Q, a quantity which we may fuppofe as {mall as we pleafe, we fhall neceffarily have P= 0, and Q2=o, But fuch is pre- cifely the nature of the equation in the laft article, namely, /) TT _ 2y°. (RZ: MZ) + aRZ—#RZ (sy meets) i (year “(@—%).(2a— 22 Hz )=°- Therefore each of the terms of this equation, taken fepa- rately, is equal to zero; and confequently, the quantities T'T, MZ and RZ, which enter not into the firft term, may Vou, VILL se be 342 Carnot on the Theory of: be neglected, in the courfe of the calculation, without alter- ing that firft term. T he Infinitefimal Analyfis, therefore, differs from the. method of indeterminates only in this, that in the former, quantities which, were they allowed to remain, would, in the end, always deftroy one another, are treated as nothing, or rather are underftood throughout the calculation ; while, in the Method of Ticketoumnliixailens we wait till the end. of the calculation, and then cancel the arbitrary quantities which ought to be eliminated. This laft method may therefore very cafily be made to fupply the ufe of the Infinitefimal Calculus, without the help of imperfeé&t equations, and without com- mitting any error in the courfe of the calculation. 38. There is yet another method of coming at the refults of the Infinitefimal.Analyfis, without overpafling the bounds of ordinary algebra; and that is, by the Method of Limits, or Ultimate Ratios. For though this analyfis be founded entirely on the properties of limits.and ultimate ratios, it differs never- thelefs from what is properly called the method of limits, in this, that in the latter, the quantities which we call Infini- tefimal, do not enter feparately into the calculation, nor even, their ratios, but only the ultimate values of thefe ratios, which being finite quantities, do not fo properly conftitute this method a particular calculus, as a fimple application of ordinary algebra. : The bufinefs before us, then, is by barely introducing | into ordinary algebra, not -Infinitefimal quantities themfelves, but the ultimate ratios of thefe quantities, to fupply the means which the Infinitefimal Analyfis furnithes, for, dif- covering any properties, ratios and relations whatfoever, of the magnitudes which conftitute any propofed fyfem ; and this is that which ts properly called the Method of Limits. | To explain the procedure, and give fome idea of the fpirit, of this method, we fhall again refume the example before treated of. Explanation of the Method of Limits, properly fo called. It is arian from what was delivered) in article g, that, though = Bi ve not equal to —— , vet the firft of thefe TP MP 3 quantities + my the Infinitefimal Calculus. 343 ‘quantities differs fo much the lefs from the fecond, as RS G : Z ‘approaches nearer to MP; or, in other words, that >7 = t gr. ne d : zp 3 an imperfect equation ; but that (putting L for the MZ . Tf ; TP . limit, or the ultimate value,) Ly = qzp '8 4 poritths _ — orrigoroufly exaét, equation. . MZ In like m: cima gen gpa <2 4h f | ike manner, L. RZ aes proved to be a per fe&t, or rigoroufly exaét, equation. Equating then thefe two Z RZ? Yyalues of L. TP Sy e ty WAG dah Co (MP being = y) TP = -_.- a—-n* there arifes, as before, Thus, this new calculus contains neither the infinitely fmall shis : . MZ quantities AZZ and RZ, nor even their ratlo RF 5 but only RZ Oe , MZ the limit or ultimate value of that ratio, namely, L. RF > which is a finite quantity. 3g. If this method could be always as eafily put in practice as the ordinary Infinitefimal Analyfis, it might even appear the moft eligible of the two: for it would have the advantage of conduéting us to the fame refults, by a path which is always dire& and luminous; whereas the other conduéts us to the truth, only after having made us traverfe, fo to {peak, the regions of error. But it muft be owned that the Method of Limits is attended with a confiderable difficulty, which has no place in the ordi- nary Infinitefimal Calculus. In the former, the infinitely fmall quantities cannot, as in the latter, be feparated from each other; and thefe quantities being always connected two _and two, afford no opportunity of introducing into the com- binations, the properties of each in particular, or of fubject- ing the equations into which they enter, to thofe transform- ations which may affift in their elimination. This difficulty is much lefs felt in the operations themfelves, than in: the preparatory and fupplemental propofitions and reafonings. Yya The 344 Carnot on the Theory of The Origin of the Name, Infinitely Small Quantities. 40. From what has been faid (in article 2.) on the origirt which the Infinitefimal Analyfis might have had, it appears, that the quantities called Infinitely Small, received that name from it’s being at firft believed that it was neceffary, for the fuccefs of the calculations in which they were employed, to» attribute to thofe arbitrary quantities values, which were really lefs than any which could be recognized by the fenfes, or conceived by the imagination. But a better digefted theory. has made it appear, that fuch a fuppofition is unneceflary ; fince the fuccefs of this calculus proceeds not:from the atte- nuation of thofe arbitrary quantities, but folely from the compenfation of errors which they occafion in the procefs. We have feen indeed, in illuftrating the example fo often adduced, that the procedure and the refults of the calculation were precifely the fame, whatever value we attributed to the infinitely fmall quantities MZ and RZ, and that confequently the character of this kind of quantities confifts not in their real minutenefs, but rather in their being abfolutely indeter- minate, that is, in their property of remaining arbitrary throughout the calculation, and fo independant on the pro- pofed quantities, that we can always take them as {mall as we pleafe, without changing, in any relpect, the conditions of the problem. Infinitefimal quantities, as was obferved in artiele 24, are - by no means chimerical beings, but fimply variable quan- tities, characterized by the nature of their limit, which is o for infinitely fmall quantities, and a for thofe which are infinitely great. To thefe indeterminate quantities, as well as to all other indefinite quantities, may be fucceffively attri- buted, divers arbitrary values, and among thofe values ought to be included the ultimate values of all, that is, o, for ah ee : res : . -quantities infinitely fmall, and —- for thofe which are infi« nitely great, Diflindtion: the Infinitefimal Calculus. 345 Diftinétion of Mathematical Infinity into Senfible and Abfolute. 41. This obfervation leads to the diftin€tion of mathema- tical infinity into two kinds, namely, /enfible, or ajfignable; infinity, and ab/olute, or metaphyfical, infinity, which is the limit of the former. If then, to any infinitely fmall quantity, be affigned a determinate value, which is not o, this value will be what I call a fenfible, or affignable, Infinitefimal ; whereas, if this value be the Jaft of all, that is, if.it be abfolutely nothing, it will be what I call an ab/olute, or metaphy/fical, Infinitefimal, which I {hall alfo diftinguifh by the name of an evanefcent quantity. Thus an evanefcent quantity is not that which is generally called an infinitely fmall quantity, but only the. ultimate value of that quantity. It #s only, I fay, a deter- minate value which, like any other value, may be attributed ' to that arbitrary quantity, which is generally denominated infinitely fmalt. 42. The confideration of thefe evanefcent quantities would be almoft ufelefs, if in calculation we were reftriéted to treat them as fimple nullities ; for, in that cafe, they would pre- fent only the vague ratio of o to o, which is no more equat to 2 than it is to 3, or to any other quantity whatfoever. But it muft not be forgotten, that thefe nullities are here invefted with particular properties, as the ultimate value of indefinitely {mall quantities, whofe limits they are; and that the particular epithet, evane/cent, is applied to them in order to denote, that, of all the ratios and relations of which they are fufceptible in quality of nullities, no other is confidered as entering into the calculation, than thofe which the law of continuity affigns to them, when the fyftem of auxiliary quantities is fuppofed infenfibly to approach te the fyftem of _affigned quantities, This idea is what fome great geometri- cians have thought they could exprefs, when they faid, that evanefcent quantities were quantities confidered, neither before nor after they had vanifhed, but in the very inftant of their vanifhing *. For * (C’eft ce que de grands geometres ont cru pouvoir exprimer, &c.) The author here plainly alludes to Sir 1. Newton, the author of this doétrine B46 Carnot on the Theory of For example, in the cafe before adduced, as long as RS does not coincide with MP, the fra&tion — is greater than — ; nor do thefe fractions become equal, till MZ and RZ are reduced to nothing. It 18 true, that then, ar is a8 much’ equal to any other quantity as to eh 3 becaufe =. is a quantity altogether arbitrary; but, among all the different values which i may be {uppofed to have, “ is the only one which js nateened to the law of continuity and deter- “mined by it. For, if a curve were conftructed, whofe abfeitfe dofirine of pritae and ultimate ratios, and of the whole, method of Fluxions. That great man, in-the concluding fclolium of Seét. 1. Be xt of the Principia, has thefe words: ‘ Odjeé?/o ff, &e.” * It may be ob=. je€ted that evanefcent quantities have no ultimate proportion ; for that, before they vanifh, that proportion cannot be the laft, and after they have vanifhed, it is nothing. But, by the fame argument, when a moving body ftops at a certain place, it may be faid that it has no ultimate velocity, for that, before the body reaches that place, the velocity is not the ultimate velocity, and when it has reached the place, the velocity is nothing. The anfwer is eafy ; for by the ultimate velocity is meant the velocity of the body, neither Jefore it reaches its laft place, nor after it has reached it, but that velocity with which it aétually reaches it ; that is, the very velo- city with which the body attains its laft place, and comes to reft. In hike’ manner, by the ultimate ratio of evanefcent quantities is to be underftaod, the ratio of thofe quantities, neither dcfore, nor after they vanith, but ¢be ratio with which they vanif>. And thus alfo the prime ratio of nafcent quantities is that ratio with which they firft ftart into exiftence,” &c. Though but a humble and diftant follower of Newton, Quem longe fequor, et wchigia pronus adoro, I fee nothing that could hinder him from “ thinking he could exprefs”” the fundathental principle of this doétrine by fuch language. For my oiwn part, I muft frankly fay, that the fcholium whence it is quoted, con- veys, or fuggefts, that principle more clearly to my mind, than all that our ingenious author and others have written on’ the fubjeét. But we do not all fee things, with equal clearnefs, in the fame point of view. Some of my fuperiors in genius and knowledge have a different opinion of that {cholium, and of the reft of Newton’s fluxionary doétrine, as delivered by himfelf, and even as explained by Ditton, Simpfon, and others. To fuch E would recommend the prefent perfpicuous trraét—W. D, was the Infinitesimal Calculus. 347 was the indefinitely fmall quantity MZ, and it’s ordinate MZ “RZ 2 : thie “ iciffe o, would be reprefented by foe and not by an arbi- proportional to ——, that which would anfwer to the ab- trary quantity. Now this is what diftinguifhes the quantities which T call eyanefcent from thofe which are fimply nothing... Thus, though i in general we have'o = 2X0, = 3 X o, = 4X0, &c. yet we cannot treat an netbeans quantity, fuch as MZ, in the fame manner, and fay MZ = 2MZ = 3MZ = 4MZ, &c.; for the law of continuity cannot affien to MZ and MZ, any other ratio than that of Saray, nor any other relation than that of identity *. 43. We have feen that by introducing into the calculation infinitely fmall quantities, and by neglecting them in com- parifon with finite quantities, the equations became imper- fet, and that the errors which they produced were only compenfated in the required refult. But we have it now in our power to avoid this kind of inconvenience, by means of evanefcent quantities, which being nothing elfe than the ultimate values of the infinitely fmall quantities correfpond- ing to them, may, like any of the other values, be attributed to “thefe indefinitely fmall quantities; and which being, in another point of view, abfolute nullities, may be neglected, when they are found conneéted with any effective quantities, without preventing the calculation from being perfeétly ri- gorous. — 44. The Infinitefimal Analyfis, then, may be confidered in two different points of view ; by regarding the infinitely fmall quantities, either as real, effective quantities, or as abfolute nullities. In the firft cafe, the Infinitefimal Analyfis is nothing elfe than the Calculus of compenfated errors; and in the fecond, it is the art of comparing evanefcent quantities among themfelves, and with others, in order to deduce from thefe comparifons the proportions and relations, whatever they may be, which fubfift among the quantities propofed. * For “ identity,’’ the author fhould have ufed the word ‘ congruity.” They are very far from being fynonymous terms ; though ufed as fuch by fome mathematicians, Sce Euclid’s $th axiom.—W. D. pill ‘Evanefcent 348 Carnot on the Theory of Evanefcent quantities,-as being equal to nothing, ought to be neglected in the calculation, when they are connected, by addition or fubtraétion, to any real, effective quantity. But they have, neverthelefs, as we have feen, relations very important to be known, relations which are determined by the Jaw of continuity, to which the fyftem of auxiliary quantities is fubjected in its mutations. Now, in order to difcover this law of continuity, it is eafy to perceive, that we are obliged to confider thefe evanefcent quantities at fome diftance from the limit where they entirely vanifh, otherwife they prefent only the indefinite ratio of o to a; but this diftance is arbitrary, and hath no other objeét but to enable us to judge more eafily of the ratios or relations which exift between thefe evanefcent quantities. Thefe are the ratios which we have in view, when we confider infinitely {mall quantities as abfolute nullities, and not thofe ratias which exift between the quantities which are not yet arrived at their limit, or the term of their annihilation. Thefe laft quantities, which I have called indefinitely fmall, are not themfelves defigned to enter into the calculus confidered in the prefent point of view; but are only employed to affift the imagination, and to indicate the law of continuity which de- termines the ratios and relations, whatever they may be, of the correfponding evanefcent quantities, According to this hypothefis, the quantities reprefented by MZ and RZ, in the proportion MZ: RZ:: TP: MP, are fuppofed abfolutely. equal to nothing. But, as it is their ratio that is required, in order to perceive it’s equality to hs) the indefinitely fmall quantities, which anfwer to thefe nullities, mut be confidered, not that they themfelves may be introduced into the calculation, but that the vanifhing quan- tities, which are their ultimate values, may enter into it, under the denominations of MZ and RZ. ; 45. Thefe expreffions therefore, MZ and RZ, here repre- fent nullities, and are ufed under the forms of MZ and RZ, rather than under the common form o, becaufe, if they were ufed under this laft form, it would no longer be poffible, in the operations wherein they are mixed, to diftinguifh their different’origins, or, in other words, to diftinguifh the dif- ferent the Infinitefimal Calculus. 349 ferent indefinitely fmall. quantities which, anfwer to them. Now the confideration of thefe lati, at leaft mentally, is ne- ceflary to the apprehenfion of the law of continuity, which determines the required ratio of the evanefcent quantities which are their Jimits; and confequently it is effentially ne- ceflary to keep them in view, and to characterize them by expreffions which may prevent them, from being confounded. 46. Evanefcent quantities, which are the fubject of the Infinitefimal Calculus, confidered in this new point of light, are, it is true, entia rafionis, creatures of the underftanding. But this does not hinder them from having mathematical properties, and from being compared together, as well as imaginary quantities in Algebra *, which have no better claim to exifience. For it is not more certain, for example, that 60 is = 20. +,49, than that f— 2 is = Y— 34 ee fl ‘Now no perfon doubts the accuracy of the refults obtained “by the calculus of imaginary quantities ; though they be _ only the algebraic forms and emblems of abfurd quantities. With much greater reafon are we prevented from rejecting evanefcent quantities, which are at leat the limits of real quantities, and are in intimate contact, fo to fpeak, with their exiftence. What fignifies it, indeed, Whether thefe eva- nefcent quantities are, or are not, chimerical entities, if theit ratios be not fuch, and if thefe ratios alone intereft us? Wheny therefore, we- fubject infinitefimal quantities to calculation; * The author might have added points, lines; furfaces and folids in geometry ; for they too are entia vationis, which have no exiftence in ex+ ternal nature. | Pojnts are merely the terms or limits of lines; lines of furfaces, atid furfaces of folids ; juft as the prime ratios of nafcent, and the ultimate ratios of evanefcent, quantities, are the limits of thofe ratios, when the quantities are confidered as beginning, or ceafing, tobe. Yer geometry refts on this foundation of abfiract entities, With perfe& fecurity ; for the truth is, that, without abftraét ideas, fcience, firidtly fo called, cannot exif. And he who can conceive a mathematical point, a mere abftraét focus, a fomething without parts, an entity truly one and indivifible, which, being a creature of the intellect, entirely eludes the cognizance of evety fenfe; I fay fuch aman will no fooner underftand Newton's doce trine of ptime and ultimate ratios, than he will efteem it 2 legitimate foundation of mathematical reafoning.—W. D. Vou, VIIL Z4 ; we ¢ 350 Carnot on the Theory of - ve have it entirely'in our power to confider thet either as real quantities, or as abfolute nullities. . The difference be- “tween thefe two ways of confidering this queftion, confifts in aa “this, that, by regarding evanefcent quantities as nullities, the ~ propofitions, equations and refults, whatever they may. be, are always accurate and rigorous; but have a reference to ‘quantities which are creatures of the underftanding, and ex- prefs the relations which exift between quantities which do not themfelves exift*. On the other hand, by confidering infinitely fma!! quantities as having fome reality, the propo- -fitions, equations and refults, whatever they may be, have ’ for their {ubjeét real quantities. But thefe laft propofitions, equations and refults are falfe, or rather imperfeét, and be- come exaét in the end only in confequence of the compen- fation of their errors, a compenfation, however, which is the neceffary and infallible refult of the operations of the calculus. * Thus the ratios of the ordinal numbers (one, two, three, &c.) to each other, while thofe numbers remain floating, fo to fpeak, in indeter- minate abftraétion, and unapplied to any particular objeéts of fenfe, may be faid to‘ exprefs the relations which exift between quantities which do not themfelves exift.” Thus alfo, if a body be /ippofed to fall from any moderate height, its velocities at any two points (refiftance apart) will have to each other the ratio of the {quare rocts of the fpaces fuppofed to be defcribed ; although no body ever adfually fell, or perhaps ever will ~ aétually fall, fiom that’ precife height. Thefe examples, it is hoped, will prevent readers who are not much accuftomed to fuch fpeculations, from rafhly eha¥gitiz our author with abfurdity, in talking of the relations be- tween quantities which do not themfelves exift; that is, which haye no exifterice in external nature. For the truth is, and 4 furprifing, nnac- countable truth it appears to many beginners, that the objeéts of Pure Mathematics, though originally abftracted, or copied, from external ob- jeéts, have no exiftence out of the minds which conceive them; and hence proceeds al] that atcuracy fer which thofe fciences are juftly valued: The inaccuracy of the figures, motionss &c. of external objeéts induces a corres fponding inaccuracy into Mixed Mathematies.+The inaccuracy of lan- guage has,an analogous effe€t in metaphyfics; for metaphyfical relations and deduélions may be perfeétly accurate 7x rhe mind, yer few of them can be adequately and unexceptionably exprefled, for want of an accurate, unambiguous language. Hence the endlefs difputes with which men unhappily difpofed to cavil, and who affeét to doubt of every thing, never ceafe to embroil that important, and otherwile not unpleafant, region of philofophy.—W. D, i 47+ The the Infinitefimal Calculus. 351 47. The theory which has been thus expounded eafily furnithes anfwers to all the objections which have been made againft the Infinitefimal Analyfis, the principle of which fe- veral geometricians have thought faulty, and capable of lead- ing to erroneous conclufions. But thofe. gentlemen have been overwhelmed, if the expreffion may be allowed, with a mul- titude of prodigies, and with the fplendour of the numerous truths wherewith this principle has teemed. a Thefe objeCtions may be reduced to this. The quantities faid to be infinitely fmall, are either abfolute nullities, or they are not; for it is ridiculous to fuppofe that there. exilt entities, which hold a middle place between quantity and nullity. Now if they are abfolute nullities their comparifon leads to nothing, for the ratio of o to oO is no more a@ than it is b, or any other quantity whatever. If, on the other hand,, they are not nullities, but real quantities, they cannot withe out error be neglected, as the rules of the Infinitefimal Ana- lyfis preferibe. The anfwer is fimple. So far from its not being logical to confider infinitely fmall quantities, either as real beings, or as nothings, they may, on the contrary, be treated at plea- fure, either as nullities or as true quantities. For they who with to confider them as nullities, may an{wer, that what they call infinitely fmall quantities are not any nullities taken at random, but nullities affigned by the law of continuity which determines their relation*; that among all the relations of which thefe quantities are fufceptible as nullities, they only ~eonfider thofe which are determined by this law of conti- nuity ; and, ina word, that thefe relations are not vague and arbitrary, becaufe the law of continuity does not affign feveral different relations between the differentials, for example, of the abfciffe and ordinate of a curve, when thefe differentials yanifh, but one only, which is that of the fubtangent to the ordinate. On the other hand, they. who regard infinitely {mall quan- tities as true ones, may anf{wer, that what they call an infi- nitely fmall quantity is one which is arbitrary and independant on the qualities propofed ; that, therefore, without fuppofing * See the Note on article 22. 224 it 352% Carnot on ihe Infinitefimal Calculus. it nothing, it may be treated as fuch, and yet no error will exift in the refult; becaufe that error, if there were any, would be arbitrary, like the quantity which occafioned it. Nowit is evident, that no fuch error can exift, except among’ quantities, one of which at leaft is arbitrary. When, there- fore, we arrive at a refult containing no arbitrary quantity, and which expreffes any relation whatever between quantities given, and thofe determined by the conditions of the problem, we may reft affured that that refult is accurate; and that, confequently, the errors neceflarily committed in exprefling thefe conditions, muft have been compenfated and have difap- - peared, by the neceffary and infallible effects of the operation, 48. Other mathematicians, apparently embarraffed by the objection juft difeuffed, have fimply confined themfelves to prove, that the Method of Limits, the proceffes of which are rigoroufly accurate, in all refpeéts, mutt neceffarily lead. to the fame refults as the Infinitefimal Calculus. But, while it is agreed that the principle of that method is very luminous, it cannot be diffembled, that the difficulty is thus only elud- ed, not removed ; that the Method of Limits leads to the fame refults as the Infinitefimal Calculus, only by a difficult and circuitous way; and, in fine, that that method, far from being the fame with the Infinitefimal Calculus, is, on the contrary, only the art of difpenfing with this calculus, and of fupplying it by ordinary Algebra. It appears to me, that they would fucceed, in a more fimple manner, by the Method of Indeterminates. But why adopt one of thefe methods to the exclufion of the reft, when they can afford us their mutual affiftance? Let us then employ them all—the Infinitefimal Calculus, properly fo called, the Method of Limits, and the Method of Indeterminates, as circumflances may require, and Jet us neglect none of the means which can conduét us to truth, or fimplify our refearches. It remains for me to fhow, by fome examples, the applica- tion of the general principles, which I have explained. This I fhall do, by giving my reader an idea of the Differential and Integral ‘Calcul, which, properly fpeaking, are the ari sittin Analyfis itfelf reduced to praétice, {To be continued. ] XI, Ace bag Jes XI. Account of C.F. DamBERGER’s Travels through the interior Parts of Africa, from the Cape of Good Hope te Morocco. {Continued from p. 253.] Ox the 15th of December our traveller proceeded on his: jourmey, and after paffing through three villages refted for fome time near a fourth under a beautiful matahora tree *. Here he was vifited by fome of the natives, who offered him a piece of wolf’s flefh, which he at firft refufed; but finding he could get nothing elfe, he ate it, and thought it tafted better than that of the buffalo. Two miles further he found’ in a wood a prodigious number of tortoifes, which exciting’ "his appetite, he refolved to fpend the night there under fome trees. He therefore made a large fire, and roafted fome of the fleth of thefe animals, but ate fo freely, that for fome time he’ could not fleep. ‘Towards morning he fell afleep, but had fearcely remained an hour in that flate, when he found fome- thing move at his feet ; upon which he ftarted up, and difco- vered a fnake three ells in length and a foot in thicknefs, devouring the remains of his meal. Being much alarmed at the appearance of this gueft, he immediately haftened from the fpot and continued his journey. Towards evening he arrived at a narrow but long ridge of mountains, where he sefted for the night. Next morning, when about to depart, he heard human voices, and foon after faw about twenty armed men, who were efcorting a company of prifoners, coupled together, two and two, with thongs. Some of the former immediately fprung towards him, and conduéted him to their leader, who, after furveying him for fome time, took a thong which was wound round his middle, and, having bound with it his hands and feet, ordered him to follow him. Towards noon they arrived at the large village of Cuojaha, where they refted, and procured a fupply of water, This was the firft village in the © The leaves of this tree are {mall and long; the branches hang down, and the flowers are of a reddith colour. The fruit are round, and about the fize of a large pea; they contain a kind of meal of an excellent tafte, which is formed into a fort of cakes nor inferior to bifcuit. province 354 Travels through the province of Porguhomat, which in maps is called Ofila. Damberger’s Fellow: travellers belonged to this nation, and refided'at a place half a day’s journey further to the north. This province lies at the diflance of four days’ journey from the boundaries of the kingdom of Congo; it is exceed~ ingly fertile, and abounds with productions of various kinds. The people are warlike, and defend theiy territories with great bravery. Our traveller was told; that they could bring into the field from 18,000 to 20,000 men; bist he believes this account to be exaggerated one half, as the population ap- peared to be only very moderate. This nation-was formerly fubje&t to the king of Bengue'a, who procured from it his beft foldiers; but as thefe foldiers were often fold for flaves when the prince ftood in need of money, the people rebelled in the year 1776, and, putting to death the old king Khiguan,, declared themfelves independent. The fon of the murdered) king was afterwards placed on the throne ; but in every thing that relates to public affairs he is obliged to be guided by the adyice of the oldeft of the inhabitants, who are afligned to him as counfellors. Dilputes and quarrels among thefe people are fettled by the oldeft perfons in each family; and, the offending party, when the caufe has been determined, is, punithed out of doors. Many of their cuftoms are fimilar to, thofe of the neighbouring nations, but they have fome pecu- liar to themfelves. There are fewer women here than in fome of the other African nations, and it is even, not un- common for two men to have only one wife, and vet to live together in perfect harmony. The women are highly re- fpected, and treated much better than among the furrounding nations. Male children immediately after birth are clrcum- cifed, and great rejoicings take place on fuch oceafions, be, caufe boys are much more valued than girls. As foon as a child can fpeak, he is taught by his grandfather, or, if he has, none, by his father, to know thofe vegetables and fruits which can, be ufed as food, and to guard againft thofe which are pernicious. He mutt learn alfo to make mats of long grafs, and,»when he becomes older, to take a fhare in the management of the domettic concerns of the family : his chief attention, however, is directed to hunting, in which it is Diterior Parts of Africa. 955 . is requifite that he fhould difinguith bimfelf by his boldnefs and dextenuy... When he kills an elephant, he. is no longer elaffed among the boys,: but,confidered as having attained to the rank of,a.man. Every ftrangermot..engaged in; trade . with this nation. is confidered as. a en but he.1s, well treat- ed, and never afterwards. fold; for thefe, people deteft this traffic, and endeavour to free from their ftate of flavery thofe unfortunate beings who are deftined by..other nations to be fold. . When they learn therefore that any, flave-dealers,.are about to pafs through or near their territories with a cargo of _ flayes, they affemble inva large body, attack the. flave-meyr- chants, and, having deliv ered the: flay es, receive. them,as members of their mation. Our traveller was obliged to ac- company a party of them on an expedition of this kind, but he had the misfortune to be taken prifoner. The people by -whom-he was made captive were called the Sovians. Being liberated however {ome time after, he continued his journey on the 26th of February, 1786,.and on the 5th of June following arrived at the village of Mohakam on the frontiers of the antient kingdom of * Loango, where he pro- cured a guide who panacea him to the.town of Malemba, the capital, of the united kingdoms of Malemba and Cacongo. This country is about four hundred miles in length, and two hundred and forty in breadth ; it 1s exceedingly fertile, and abounds with vegetables, minerals, and animals of various kinds which are caught for the fake of their fkins. The river Bambo.and the lake Samoy fupply plenty of fith and fhell- fith.. The trade of this country is exceedingly advantageous to the Europeans, who for the mereft trifles, fuch as fhells and bits of iron, often get in return the beft {kins and furs in large quantities.. The king’s fianding army confifts of be- tween ten and twelve thoufand men, who can at any time be __ collected in the courfe of forty-eight hours., The king him-~ » felf is a good warrior, leads his troops into, the field in perfon, and is much dreaded even by his more powerful neighbours : : _ . whenever he goes abroad he is ufually attended by four of his » minifters, who are at the fame time officers, and twelve men ye of, his budy- guard. _ The town is {urrounded by a wall compofed of fragments ‘wi au « 4 of u 356 - “Travels through the of rock and loofe ftones, heaped together without cfay oF mortar, and by a ditch. The palace where the king re~ fides is badly built, is one ftory high, and about five hun- dred feet in circumference. It ftands before the water-gate on the river Malemipo, towards the lake, and affords a good profpect. Our traveller faw planted near it four three- pounders. After being expofed to various hardfhips among thefe people, our traveller, being fent out with a party to collect ‘elephants’ teeth, found means to make his efeape, and ar- rived among a people called the Yaganefe, with whom he remained till the end of the year. On the 2d of December he again refumed his journey, and, croffing the Akafi moun- tains, reached the territory of Mugari. This country is fmall, and thinly peopled. The inhabitants are of low ftature, and far from being hofpitable to flrangers. Though of fmall fize, they are more expert in hunting the elephant than many of their neighbours ; and from the hides and teeth of thefe ani- mals they procure their chief fubfiftence. The whole number of the inhabitants does not amount to more than three thou- fand: moft of them live in caves of the mountains. After paffing through a variety of fmall villages our tra- veller entered the kingdom of Yukodego (Moncemugi), which towards the eaft borders on Abyffinia. The river Zambece, which at the town of Yukora divides itfelf into five branches, traverfes nearly the whole of the country, and, at the diftance of half a day’s journey from the town of Zambre, forms a large Jake, bearing the name of that town. The town of — Zambre, which he vifited foon after, confifts of four hun- dred huts, and fifty or fixty houfes. The former are built of timber and ftraw, the latter of ftones and mortar. The town, which is of a triangular fhape, lies on the right fide of the river Zambre, has two principal and three crofs ftreets, and is defended on one fide by a wall. The houfes, as wel! as the palace, are only one ftory high. At Zambre our traveller was introduced to the king, who — eonduéted him ittto what he called his hall, where he difplayed to him his treafures. They confifted of a few worn copper — coins, two looking-glaffes, an almanack for ‘the year 17435 * : a few | Tuierior Parts of Africas , B57 @ few fleets of printed paper; four fmall cannons, fuch as children haye to play with; a few other toys, and a wooden «lock, which feemed to be quite deranged. The: king having, by an interpreter, exprefled great concern that the clock did not go as formerly, our traveller, when his ma- jefly was gone, told the interpreter that he would try to re- pair it, if the king gave him permiffion. The king afferted; and Damberger, though not much acquainted with clock- making, was fo fortunate as to fucceed, When the king returned next day he was much furprifed, and began to en- tertain a very high idea of a man who had been able to efle&t what exceeded the flall and ability of the moft ingenious of his fubjects. From that moment our trayeller’s confequence continually increafed; he received the fame victuals as were | ufed by the kine, accompanied him every where, and, by means of this privilege, had an opportunity of getting complete view of the lake of Zambre, when the king went thither to fee the people employed there in fowling and fith- ing. This lake is in length three full days journey, and is interfperfed with about forty fmall iflands, frequented by in- numerable flocks of birds. It is of an oval form, and about half a day’s journey in breadth. The king keeps here a guard of two hundred men to take care that the fowling and fifhing are properly conducted for his majefly’s advantage ; but our traveller was told that thefe people drefs for themfelves the be&t of the fowls and the fith that are caught. After fpending five months at this place, Damberger, hay- ing obtained the king’s leave to depart, continued his journey on the 28th of May 1787, and on the 11th of June arrived at the firft frontier huts of the Moohatans; a numerous and warlike nation, who inhabit a tract of land belonging to the kingdom of Monemugi, and fubjeét to its fovereign. As the rainy feafon had now commeuced in this part of the country, he was obliged to remain fome time under very unfavourable circumftances at the village of Mytob, from which he fet out on the 1gth of July, in company with fome travellers from the country of Moffeguejos, lying eaftward of the kingdom of Moncmugi, who were going to the kingdom ef Otoba to fetch falts After crofling the Vo. VIL. 3A river 358 Travelsthrough the Interior of Africa.. river Druma, and afcending a high mountain to the weft, he arrived among a people called the Mophanians, who dwell in caves, and by whom he was well received. The king of this country is an abfolute fovereign, and poffeffes a tract of territory ten days journey in Jength from weft to eaft, and feven in breadth from north to fouth. Of the various kinds of fruit-trees found here, the moft remarkable are the domo and the inknbak. The former bears a kind of apples without pips, of the fize of a hen’s egg, having a golden colour, and a tafte like that of lemons. It grows on the mountains, has long, narrow, fharp-pointed leaves, and at- tains to the height of the cherry-tree. The bark refembles that of the cinnamon-tree, and is preferved along with the fruit, and ufed all the year through as a corroborant. The inkobak tree bears a fruit of the nut fpecies as large as an egg: itis of an oblong form, and has a red hufk, which in all probability would afford a good colour for dyeing. Our traveller obferved that the earthen-ware ufed by the inhabit- ants was dyed with it, and that it retained its beauty even in the fire. The nut itfelf is white, and taftes hike cinnamon. The tree is as large as the oak, and all the year through bears fruit and bloffoms at the fame time. After leaving thefe people, our author profecuted his journey through the villages of Qhgothen, Uhroh, and Mato, to Ocymioro, the refidence of the king, where he was placed among the royal flaves; but, finding means to effec his efeape' acrofs the fandy denies, he afcended the Mountains of the Moon, and arrived in the territories of the Voma- hanians. Thefe people he found hofpitable and good tem- pered ; they prefented him with tiger’s fiefh, which he had never before tafted, and, having directed him what courfe to proceed, wifhed him a brditpebe ss journey. He now direéted his courfe northwards acrofs Dahamta to the kingdom of Vohyagtam; and falling in with fome travelling negroes, who called themfelves Taomuh, he purfued his journey in their company as far as the frit huts on the frontiers of Ba- hura. On the roth of November he fet’ out with a caravan bound to Vangara, by the way of Vadgayu, Yomy, Se. but, not bemg able to bear the fatioue of riding, he was left on the road, and fell- fick, On his recovery, which took . place & . Deftrwétion of the Membrana Tympani. 359 filace foon after, he proceeded back again to Yandoka, and Bahahara the capital, where he was detained for a fhort time as a flave; but having repaired fome of the king’s weapons he obtained his liberty, and travelled in the fuite of the king to Kahoratho. : [To be continued. ] XII. Obfervations on the Effects which take place from the Deftruétion of the Membrana Tympani of the Ear, By Mr. Asttey Coorrer. In a Letter to EVERARD Home, E/q. F.R.S. by whom fome Remarks are added*. DEAR SIR, Ar the time you were engaged in the inyettigation of the ftru@ure and ules of the membrana tympani, you mentioned a with to afcertain the effeét a rupture of that membrane would have upon hearing. I now fend you fome obferva- tions on that fubject, which, if you think them of fufficient importance, you will do me the honour of prefenting to the Royal Society. I am, .écc. i ASTLEY COOPER. Awnatomists have endeavoured to afcertain, by experi- ments on quadrupeds, the lofs of power which the organ of hearing would faftain by perforating the membrana tympani: dogs have been made the fubject of thefe trials; but the re- {alts have been neither clear nor fatisfaCtory, and they accord but little with the phenomena I am about to relate. Mr. Chefelden had conceived the defign of making the human organ itfelf the fubject of dire&t experiment ; and a condemned criminal was pardoned, on condition of his fub- mitting to it; but a popular outcry being raifed, it was thought proper to relinquith the idea. Though denied the aid of experiment, we are not without the means of obtaining knowledge upon fuch fubjects; fince the changes produced by difeafe frequently furnifh a clue _which is equally fatisfactory. _ It often happens, that fome parts of an organ are deftroyed - * From the Tranfadlions of the RoyalSaciety for 1890. 3A by > 360 Obfervations on the Deftratiion by difeafe, whilft others are left in their natural ftate’; and hence, by the powers retained by fuch organ, after a partial deftruction, we are enabled to judge of the funétions per- formed by thofe parts when the whole was in health. Guided by this principle, I have made the human ear the fubject of obfervation, and Have endeavoured to afcertain the degree of lofs it fuftains in its, powers by the want of the membrana tympani; a membrane which has been generally confidered, from its fituation in the meatus, and its connee- tion with the adjacent parts by a beautiful and delicate ftruc- ture, as efientially neceffary to the fenfe of hearing; but which, as appears by the following obfervations, may be loft, with little prejudice to the functions of the organ, Mr. P » @ medical ftudent at St. Thomas’s hofpital, of the age of twenty years, applied to me, im the winter of ¥797, while he was attending a courfe of anatomical lectures, requefting my opinion upon the nature of a complaint in his ear, which had long rendered him flightly deaf. Upon inquiring into the nature of the fymptoms which had preceded, and of thofe which now accompanied the difeafe, he informed me, that he had been fabject from his infancy to pains in the head, and was attacked, at the age of ten years, with an inflammation and fuppuration in the ‘ left ear, which continued difcharging matter for feveral weeks in the fpace of about twelve months after the firft attack, fymptoms of a fimilar kind took place im the right ear, from which alfo matter iffued for a confiderable time. The difcharge in each inftance was thin, and extremely of- fenfive to the fmell; and, in the matter, bones or pieces of bones were obfervable. The immediate confequence of thefe dttacks was a total deafnefs, which continued for three fonths; the hearing then began to return, and, m about ten months fromm the lait attack, was reftored to the ftate im which it at prefent remains. Having thus deferibed the difeafe and its fymptoms, he gave me the following fatisfactory proof of each membrana tympani being imperfect. Having filled his mouth with air, he clofed the noftrils and. contracted his cheeks: the air, thus consprefled, was heard to ruth through the meatus ‘au- ‘ ditorius of the Alembrana Tympani. 36%. ditorius with a whiftling noife, and the hair hanging fron the temples became agitated by the current of air which iffued from the ear. To determine this with greater precifion, T called for a lighted candle, whieh was applied in turn to eacly ear, and the flame was agitated ina fimilar manner, Strack with the novelty of thefe phenomena, I wifhed to have many witneffes of them, and therefore requefted him, at the con- elufion of the le&ure upon the organ of hearing, to exhibit them to his fellow fiudents ; with which requeft he was s fo obliging as to comply. It was evident from thefe experiments, that the membrana’ tympani of each ear was incomplete, and that the air iffued © from the mouth, by the Euftachian tube, through an open- ing in that membrane, and efcaped by the deisebal meatus. To determine the degree in which the membrana tympani had been injured, I paifed a probe into each ear, and found that the membrane on the left fide was entirely deftroyed ; fince the probe ftruck againft the petrous portion of the tem- poral bone, at the interior part of the tympanum, not by pafling through a fall opening; for, after an attentive exa~ mination, the fpace ufually occupied by the membrana tym- pani was found to be an aperture, without one trace of merm- brane remaining. On the right fide, alfo, a probe could be paffed into the eavity of the tympanum; but here, by conduéting it alone the fides of the meatus, fome remains of the circumference of the membrane could be difcovered, with a circular open= ing in its centre, about the fourth of an inch in diameter. From fuch a deftruction of this membrane, partial indeed in one ear, but complete in the other, it might be expected that a total annihilation of the powers of the organ would have followed: but the deafnefs was inconfiderable. This gentleman, if his attention were exerted, was capable, when ‘ym company, of hearing whatever was faid in the ufyal tone of converfation ; and it is worthy of remark, that he could hear with the left ear better than with the right, though in the left no traces of the membrana tympani could be per- ecived, When attending the anatomical! lectures, alfo, he could hear, — ’ a2 Obfervations on the Deftruction hear, eyen at the moft diftant part of the theatre, every word that was delivered; though, to avoid the regular and cons fiant exertion which it required, he preferred placing himfelf near the lecturer. I found, however, that when a note was ftruck upon the pizno forte, he could hear it only at two-thirds of the dif- tance at which I could hear it myfelf; and he informed mey that in a voyage he had made to the Eaft Indies, while others, when fhips were hailed at fea, could catch words with accuracy, his organ of hearing received only an in- diftinét impreflion. But the moft extraordinary circum- ftance in Mr. P ’s cafe is, that the ear was nicely fuf- ceptible of mufical tones; for be played well on the flutes and had frequently borne a part in a concert. 1 {peak this, not from his own authority only, but alfo from that of his father, who is an excellent judge of mufic, and plays well on the violin: he told me, that his fon, befides playing on the flute, fung with much tafte, and perfectly in tune, The flight degree of deafnefs of which Mr. P. complained, was always greatly increafed by his catching cold: an effect which feems to have arifen from the meatus being clofed by an accumulation of the natural fecretion of the ear; for.it’ frequently happened to him, afier he had been fome time deaf from cold, that a large piece of hardened wax, during a fit of coughing, was forced from the ear, by the air rufhing from the mouth through the Euftachian tube, and his hear- ing was inftantly reftored. ° From bathing, likewife, he fuffered confiderable inconve- nience, unlels his ears were guarded againft the water, by cotton being previoufly forced into the meatus.-» When this precaution was neglected, the water, as he plunged in, by Yuthing into the interior parts of the ears, occafioned violent pain, and brought on a deafnefs, which continued until the caufe was removed, that is, until the water was difcharged ; but he had acquired the habit of removing it, by forcing air from the mouth through the ear. In a healthy ear, when the meatus audiiorius is topped by the finger, or,is otherwife clofed, a noife fimilar to that of a diftant roaring of the fea is produced: this arifes from 8 : the of the Membrana Tympani. 363 the air in the meatus being compreffed upon the membrana tympani. In the cafe here deferibed, no fuch fenfation was produced: for, in Mr. P.’s ear, the air, meeting with no impediment, could fuffer no compreffion ; fince it found a paflage, through the open membrane, to the mouth, by means of the Euftachian tube. Mr. P. was liable to the fenfation commonly called the _ teeth being on edge, in the fame degree as it exifts in others ; and it was produced by fimilar acute founds, as by the filing of a faw, the rubbing of filk, &c. Its oecurring in him feems to difprove the idea which has been entertained of its eaufe; for it has been thought, that the clofe conneétion of the nerve called the corda tympani with the membrana tym- pani, expofed it to be affected by the motions of the malleus 5 and that, as it paffes to nerves connected with the teeth, they would fuffer from the vibratory ftate of the nerve, pro- duced by the agitations of the membrane. But, in this cafe, as the membrane was entirely deftroyed on that fide on which the fenfation was produced, fome other explanation muit be reforted to; and I fee no reafon why this effect fhould not be referred to that part of the auditory nerve which Itnes the labyrinth of the ear, which, being impreffed by acute and difagreeable founds, would convey the impreffion to the portio dura of the fame nerve, and to the teeth with which that nerve is connected. The external ear, though two ‘diftin& mufcles are inferted into it, is capable, in its natural ftate, of little motion: how- ever, when an organ becomes imperfect, every agent which can be emplpved to increafe its powers is called into aétion ; and, in the cafe here defcribed, the external ear had acquired a diftinét motion upward and backward, which was obfervs. able whenever Mr. P. liftened to any thing which he did not diflinétly hear. This power over the ‘ iifened was fo’ great, that when defired to raife the ear, or to draw it backwards, he was capable of moving it in either direction. This cafe is not the only one of this defeription which has come under my obfervation ; for another gentleman, Mr. A., applied to me under a fianlar complaint, (but in one ear e. only.) procecding from fuppuration, and producing the fame effects, \ 364 Obfervations on the Deftrudtion' effects. This gentleman has the fame power of forcing air through the imperfect ear; fuffers equally from bathing, if the meatus auditorius be unproteéted ; and feels, even from expofure to a ftream of cold air, very confiderable pain. The . only difference I could obferve was, that in Mr. A.’s cafe, ‘the defe& of hearing in the difeafed organ was fomewhat greater than in the former; for though, when his found ear. was. clofed, he could hear what was faid in a common tone of voice, yet he could not diftinguifh the notes of a piano forte at the fame diftance: a difference which might have in part arifen from the confufed noife which is always produced by clofing the found ear; or becaufe, as he heard well on one fide, thé imperfeét ear had remained unemployed, and confequently had been enfeebled by difufe. From thefe obfervations it feems evidently to follow, that the lofs of the membrana tympani in both ears, far from producing total deafnefs, occafions only a flight diminution of the powers of hearing. Anatomifts who have deftroyed this membrane in dogs have aflerted, that at firft the effect on the fenfe of hearing was trivial; but that, after the lapfe of a few months, a total deafnefs enfued. Baron Haller alfo has faid, that if the membrane of the tympanum be broken, the perfon becomes at firft hard of hearing, and afterwards perfectly deaf. But, in thefe inftances, the deftruétion muft have extended further than the membrana tympani; and the labyrinth muft have fuffered from the removal of the ftapes, and from the confe- quent difcharge of water contained in the cavities of the m- ternal car; for it has been very conftantly obferved, that when al] the fmall bones of the ear have been difcharged, a total deafnefs has enfued. It is probable, that in inftances in which the membrana tympani is deftroyed, the functions of this membrane have been carried on by the membranes of the feneftra ovalis and feneftra rotunda: for, as they are placed over the water of ihe labyrinth, they will, when agitated by the impreffions of found, convey their vibrations to that fluid in a Similar man- ner, though in fomewhat an inferior degree, to thole which are copveyed by means of the membrana tympani and the {mal} of the Membrana Tynipani. 368 fmall bones which are attached to it ; and thus, in the organ of hearing, each part is admirably adapted, not only to the purpofe for which it is defigned, but alfo as a provifion againft accident or difeafe ; fo that, whenever any particular part is deftroyed, another is fubftituted for it, and the organ; from this deprivation, fuffers but little injury in its functions. It feems that the principal ufe of the membrana tympani is, to modify the impreffions of founds afd to proportion them to the powers and expectation of the organ. Mfr. P. had loft this power for a confiderable period after the deftruc- tion of the membrane; but, in procefs of time, as the ex- ternal ear acquired the additional motions I have defcribed, founds were rendered ftronger or weaker by them. When, therefore, he was addreffed in a whifper, the ear was feen immediately to move; but; when the tone of voice was louder, it then remained altogether motionlefs. Some additional Remarks, on the Mode of Hearing in Cafes aubere the Membrana Tympani has been deftroyed. By Everarp Home, Ejg. After having communicated to this learned Society the very curious facts contained in Mr. Cooper’s paper, which prove that the organ of hearing is capable of receiving all the different impreffions of found, when the membrana tympani has been deftroyed, it may not be improper to ‘explain, from the obfervations contained in a former paper’ on this fubjeét, in what manner this may take place. It is there ftated, that any vibrations communicated: di- reétly to the bones of the fkull, are as accurately impreffed upon the organ, as through the medium of the membran& tympani. The office of that memibrane is therefore to afford an extended furface, capable of receiving impreffions from the external air, and of communicating them to the finall bones of the ear; which a membrane would be incapable of doing, unlefs it had a power of varying its tenfion, to adapt it to different vibrations, In the above cafes, in which this membrane, the malleus, and the incus, had been deftroyed, it would appear that the ftapes was aéted upon by the air received into the cavity of Vot. VIII. 3B . the 366. Analyfis of a Stone the tympanum, and communicated the impreffions imme- diately to the internal organ. This not happening for fome months after the membrane was deftroyed, probably arofe from the inflammation of the tympanum confining the ftapes, and rendering its vibrations imperfect. That founds can be communicated with accuracy by the bones of the fkull to the internal organ, when received from folid or liquid fubftances, has long been well underftood. That the membrana tympani is incapable of perfectly anfwering this purpofe, when founds are propagated through air, has been a generally received opinion ; to refute which, was the object of my former paper. That, in cafes in which the membrana tympani has been deftroyed, the air is ca- pable of aéting with fufficient force upon the ftapes to com- municate vibrations to it, and to produce on the internal organ the neceffary effect foe perfect hearing, is completely afcertained by Mr. Cooper’s obfervations. XIII. Analyfis of a Stone called the Gadolinite; with an Account of fome of the Properties of the new Earth it contains, By C. VAUQUELIN*. ° 4 ey HE number of fimple bodies, and particularly that of earths, has been greatly increafed within’ a few years paft; and if chemiftry go on ftil] thus advancing, it is to be appre- hended that the time may arrive when the human mind will not be able to embrace all the combinations produced by the multitude of fimple bodies. But the analogy which exifts between certain claffes of natural fubftances, gives chemifis reafon to fufpeét that they contain a common generating principle, and affords them a hope that fome fortunate chance, or an experiment made by fome man of genius, will reduce them all to one fingle kind, either by difengaging them from thofe principles which efta- blith differences between them, or by combining thefe fame elements to thofe which are fimple. *® From the Annales de Chimie, No. 107. Till called the Gaaolinite. 367 Till chemical means are brought to that degrce of perfec- tion, we muft make known thofe bodies which, on account of their peculiar properties, we cannot refer to any of thofe already known, and which, till a new order be eftablifhed, we are obliged to confider as new fubftances. An attentive examination of their properties is of great importance; for, even though they may be only modifications of bodies al- ready known, it may happen, of which we have many in- ftances, that their qualities may become ufeful to the arts and to manufaétures, and, in any event, it is better to err through excefs than deficiency. With this view I fhall here defcribe, with fome details, the properties of a new earth difcovered by M. Gadolin, and which has been examined by M. Ekeberg under new points of view. I thall firft give a fhort defcription of the ftone, and then explain the different proceffes which I employed to analyfe it; and fhall conclude with indicating the principal proper- ties that charaéterife the new earth it contains. The greater part of the obfervations I fhall make on this fubjeét, may have been already publifhed by the chemifts above men- mentioned ; but their works being not much known, I have thought it my duty to aét in this manner, that the prefent Aifcovery may be better propagated, I fhall, however, repeat what has been communicated to me by M. Manthey, profeffor of chemiftry at Copenhagen, to whom both Haity and I are indebted for a large ere of matter containing this new earth *, In 1794, M. Gadolin difcovered this earth; and his la- bour on the fubjeét was printed in the Menibirs of the Aca- demy of Sweden, and in Crell’s Chemical Annals for the year 1796. M.Ekeberg, about two years ago, began an analyfis of the fame fione, and confirmed the refults of M,. Gadolin. To the new earth he gave the name of Yitria, from Ytterley, a place in Sweden, where it is found. A fhort mention of it was made alfo in the Annales de * Profeffor Abildgaard, alfo, has had the goodnefs to fend me a pretty large quantity of this ftone, which enabled me to vary my experiments, and to difcover'the chara€terifing properties of the new earth it conrains. 3B2 Chimie, 368 Analyfis of a Stone : Chimie, No. 100. This earth, according to him, exifts im the gadoliaite in the proportion of 0°47 Accompanied by flex — 0°25 - Oxyd of iron — _ 018 Alumine — _— 0°04 He defcribes allo fome of the properties poffefled by this new earth when freed from all the bodies united to it in the ftone, and which are as follows :—** All its combinations with acids have a fweet tafte like that of the falts of Jead, but a little more aftringent; with the fulpburic and aceti¢ acids it forms cryftallifable falts which do not change in th¢ air; with nitric acid it gives a radiating mafs, and with the muriatic-acid nothing that can cryftallife. Chara&ers of the Stone. 1ft, This fubftance has a black colour, and its duft is of a blackifh gray. ad, Its fra€ture is abfolutely vitreous, like that of glafs. 3d, Its fpecific gravity, afcertained by Haiiy, is 4:0497. 4th, It makes the magnetic needle move in a fenfible manner. | 5th, When expofed to the blow-pipe, it fplits into fmall fragments, which fly toa confiderable diflance in bright red fparks, which, when they detach themfelves, produce a ftrong erackling noife,. What remains of the ftone has a sav white colour, and does not fufe completely. 6th, When heated with borax it fufes, and communicates to that falt a yellow colour inclining to violet. ath, A hundred parts of this fubftance, expefed to heat in a platina crucible, lofe eight parts of their weight, and the matter aflumes ap ochry red colour. If, from the quantity of iron it contains, we eftimate the oxygen it muft abforb by the operation, we fhall find that it has Joft about 11 per cent. Phenomena which the Gadolinite exbibits with the Mineral Acids, The gadolinite (it is by this name J thal] diftinguifh this ftone in the courfe of this memoir,) is attacked by the power- ful mineral acids, fuch as the fulphuric, the nitric, and the . muriatic; called the Gadolinite. 369 Yauriatic; and, if their ation be affifted by a gentle heat, they form a thick jelly of a grayifh or yellowifh colour. If this kind of jelly be then evaporated to drynefs, and the refiduum of the evaporation be wafhed in water, you will obtain filex under the form of a white powder, which, when well wafhed and brought to a red heat, gives by its weight the proportion in which it exifts with the other principles. The folutions of gadolinite in acids do not all exhibit the fame phznomena by evaporation. The fulphuric and mu- riatic acids retain the iron and the new earth in combina- tion, and nothing but the filex is feparated; while, on the contrary, the nitric acid abandons at the fame time the filex and the oxyd of iron, which may be eafily conceived from the properties of the nitrat of iron. I took advantage of this property in preference to any ether, in order to apply it to the analyfis in queftion. I diffolved too parts of gadolinite in nitric acid fufficiently diluted with water, and fubjected it to evaporation, expofing it to a little heat towards the end, to effeét a complete de- compofition of the nitrat of iron. By re-diffolving it in water, I obtained, combined with the nitric acid and dif- folved, the peculiar earth feparated from the iron and the ~flex. While my folution {till retained fome traces of iron, which I eafily perceived either by the reddifh colour or by the gallic acid, I again evaporated the liquor tao drynefs, or I added a drop of ammonia, and the iron was then precipi- tated under the form of yellowifh flakes, which I {eparated by the filter. To feparate the iron from the filex, I boiled the mixture in muriatic acid a little concentrated; I then diluted the folution with water, and made it pafs through the filter, in order that I might colleé the filex, and wafh it till it was no’ longer precipitated by ammonia. _ In regard to the new earth diffolved in nitric acid, it will be fufficient if it be pure to precipitate it by ammonia, and to wafh it to obtain it feparate; but having learned, by pre- liminary trials, that in this ftate it is mixed with fmall quan- tities of lime and magnefia, I was obliged to employ fome further means for accomplifhing that end, T never- 370 Analyfis of a Stone T neverthelefs began to precipitate it by means of ammo- nia, which does not, precipitate lime. I then poured into the liquor, united to the wafhings of the precipitate, fome drops of a folution of common cafbonat of potafh, and I obtained the lime combined with the carbonic acid. I re- diffolved, for the third time, in nitric acid, the earth mixed with the oxyd of manganefe, and added, in fmall quantities at a time, a folution of hydro-fulphuret of potafh, in order that I might precipitate only the metallic parts, which, with a little attention, I was able to effea. I had then the earth alone, fo that nothing was neceffary to obtain it pure but to precipitate it by ammonia. Analyfis of the Gadolinite by Potafh. T ftill emploved another method, which alfo fucceeded, to feparate the different elements which conftitute the gadoli- nite: it confifts in fufing it with two parts of cauftic pot- afh, wafhing the mefs with boiling water, and filtering the liquor, which has a beautiful green colour. In evaporating this liquor, the manganefe, which gave it its colour, was gradually precipitated under the form of a black powder, which could be eafily collected by decanting _the fupernatant water. : When it is obferved that there is no more oxyd of manga- nefe, the liquor muft be faturated with nitric acid: on the other hand, the fediment mutt be put to digeft with the fame acid much diluted with water: by thefe means the earth alone diffolves, producing a great deal of heat; and the filex, and the iren too much oxydated, do not diffolve. This folution with the above liquor, faturated with nitric acid, muft be evaporated to drynefs, in order that if any parts of iron and filex have remained they may be feparated:: in other refpects the procefs is the fame as before. The latter has the advantage of feparating the manganefe from the other principles, and of rendering unneceffary an operation the fuccefs of which is difficult. The gadolinite might alfo, rigoroufly fpeaking, be ana- lyfed by directly attacking it by the fulphuric and muriatic acids; but as thefe acids diffolve at the fame time, and without | called the Gadolinite. Py without diftinGtion, all the elements which compofe this ftone, a hydro-fulphuret muft be employed to feparate the metals; and the juft management of this operation is diffi- cult, becaufe the new earth is precipitated by an excefs of the re-agent. By the help of thofe means, which I have briefly explained, I was able to difcover and feparate the fubftances which enter into the compofition of the ftone called gadolinite. Thefe fubftances are filex, black oxyd of iron, lime, oxyd of manganefe, and the peculiar earth to which M. Ekeberg has given the name of Yétria. The proportions. in which they are found are as follow: ift, Silex —_ —_ 25°5.° ad, Oxyd of iron — 25 3d, Oxyd of manganele — 2 4th, Lime — —_ 2 5th, The new earth, or Yétria 35 89°5 Lofs 10°5 Thefe 10°5 form the fmalleft lofs I experienced in the dif- ferent analyfes I made; for I thought it neceffary to employ, in confiructing this table, the greateft quantities of each of the matters obzained by either of the proceffes. I at firft thought that this lofs arofe from fome alkaline fubftances, as is the cafe in feveral kinds of ftone; but, hay- ing treated 100 parts by fulphuric acid, I affured myfelf that it arofe from another caufe; for, having precipitated by am- monia all the earthy and metallic matters diffolved in the fulphuric acid, and having brought to a red heat the falt produced by evaporating the liquor to drynefs, there remained nothing in the crucible but a little fulphat of lime. As I fufpected that this was occafioned by fome volatile fubftance, I heated, in a platina crucible, 100 parts of the ftone reduced to powder, and found that it had decreafed eight parts, and ihat the remainder had affumed a yellowith eolour. The flight effervefcence which I had always remarked 4 when 374 Analyfis of a Stone’ when the ftoné was diffolved in acids, induced me to ima’ gine that one part at leaft of the deficit was owing to the car- bonic acid. To affure myfelf of it, I introduced into a fmall phial 100 parts of the matter in powder, and, after preparing 4 glafs tube, deftined to convey the gas into the lime-water, I poured into it fulphuric acid diluted with a certain quantity of water; a fwelling up and heat were produced, and fome air-bubbles paffed into the lime-water, by which it was ren- dered turbid; but the quantity of the precipitate was fo fmall, that it was impoffible for me to meafure it. As the fpace, indeed, in the veffels which remained empty was fo great, it is probable the greater part of the carbonic acid re- mained in it. But this experiment fufficiently proved te me that the 10°5 of lofs belonged not merely to the carbonic acid; for, though the fpace furttifhed by my veffels was pretty confiderable, it would not have been capable of retaining it, and I fhould alfo have obtained a greater quantity of calcareous precipitate. In the hope of finding fome other fubftance, which, with carbonic acid, might contribute to form this lofs, I put 100 parts in a retort of luted glafs, to which I adapted a fmall receiver, and I expofed it to a ftrong heat: There appeared in the neck of the retort, and even in the bottle, fome fmall drops of water, the quantity of which was fo {mall that I could not weigh it. But the matter taken from the retort weighed no more than gt parts. Thus it appeared to me that the lofs which I experieniced in my analyfes is chiefly owitig to water and carbonic acid. Having given the moft remarkable characters of the foffil ‘ealled gadolinite, and the -proceffes which appeared to me beft adapted for feparating its principles, I fhall now briefly explain fome of the properties exhibited by the new earth extracted from it. ift, It is perfectly white; but it is pretty difficult to ob- tain it in that ftate on account of the oxyd of sa, which follows it in almoft all its combinations. ad, It has neither favour nor fmell. 3d, Te : : called the Gadolinne. 373 3d, It is not fufible alone, but with borax it forms a white glafs, which is tranfparent when it has not been added in excefs. 4th, It is not fenfibly foluble in cauftic fixed alkalies: in this it is different from alumine and glucina, which combine with thefe very eafily and in large quantity. 5th, It is foluble in the carhorat of ammonia, but five or fix times lefs fo than glucina ; ; that is to fay, five or fix times more carbonat of ammonia is required to diffolve an equal quantity of yttria. 6th, It combines rapidly with the fulphuric acid, and pro- duces heat in proportion as the union is effected: the falt thence refulting cryftallifes in fmall brilliant grains little fo- iuble in water: it appeared to me that more than fifty parts of cold water were neceffary to diffolve it, efpecially when hot accompanied with an excefs of acid. It has a tafte at firft aftringent, and afterwards fweet, like fugar or falt of lead. This property, though analogous to that oF glucina, 1 is, how- ever, fo fenfibly different from it, that by comparing them they may be eafily diftinguifhed. 4th, Its ea ea cel, with the nitric acid has a more ftriking favour, but it produces in the mouth an effec of the fame nature: it cryftallifes only with difficulty, and its affinity for water is fo great, that it requires fome trouble to dry it. During this operation, if it be expofed to too much heat, inftead s: becoming folid, like the greater part of the falts, it grows foft, and affumes the appearance of thick tranfparent honey ; by cooling, it becomes hard and brittle like a tone; when expofed to the air, it attraéts the moifture of it, and becomes foft. The fulphuric acid, poured into a folution of the nitrat of yttria, forms in it a cryftalline precipitate, which is a fulphat of the fame earth. 8th, The combination of this earth with the muriatic acid exhibits nearly the fame phenomena, in the feveral experi- ments I made, as the nitrat above examined: like the nitrat it can be dried with difficulty, it is fufible by a gentle heat, and ftrongly attraéts. the moifture of the atmofphere. gth, Ammonia precipitates yttria earth from the three Vor. VITIL. 3C corre - 444 Analyjis of the Chaltabintee combinations above mentioned ; lime and bary tes produce much more fenfibly the fame effet. toth, The oxalic acid, and confequently the oxalat of ammonia, form in its folutions precipitates which have an appearance abfolutely fimilar to that of the muriat of filver: elucina with the oxalic acid forms a very foluble falt—a new difference between thefe two earths. tith, Pruffiat of potath cryftallifed and re-diffolved in water occafions, in the folutions of this earth by acids, a white granulated depofit ; but this is not the cafe in folutions of alucina. 12th, The phofphoric acid does not precipitate it from the other acids, but the phofphat of foda feparates it uader the form of gelatinous white flakes. 13th, It appears to me that it has more affinity for, at Yealt, fome of the acids, than glucina has. 14th, It precipitates an infufion of gall-nuts in brow flakes. , From what I have faid, a great number of analogies may without doubt be obferved between this earth and glucina ; but, at the fame time, there appear differences which do not permit us to confound thefe two earths. Thefe differences chiefly are, the infolubility of the yttria and the folubility of glucina in fixed cauttic alkalies ; the little folubility of the fulphat of the yttria, and the rede folubility of glucina, in the fulphuric acid; the difficult folubility of yttria, and the ready folubility uF glucina, in carbonat of ammonia; the precipitation of yttria, and non-precipitation of glucina, from their folutions by oxalic acid and the pruffiat of potafh. Here then we have nine kinds of earth very diftin& by the properties peculiar to each: foon, no doubt, we fhall reckon ten, if, as we have reafon to prefage from the accuracy of ° M. Tromfdorf, the exiftence of that which he has lately an- nounced under the name of augu/?,. in the Saxon beryl, be realifed. Thefe earths will increafe in a wonderful manher the number of tlie faline combinations, which are already very confiderable, and will furnifh to chemifts a multitude of new properties to be ftudied. It is to be wifhed that they may | find New Publications. 375 find fome of them applicable to the arts; in order that thefe difcoveries may not remain altogether. ufelefs. It is to be wifhed alfo, when the properties of this new earth fhall be better known, that chemifts may give themfelves the trouble to change the name of ytttia, by which it is now known, and which is derived from Ytterley, the place where it is found, that another derived from its eflential properties maybe given to it. I fhall conclude with remarking the great difference be- tween the refult of M. Ekeberg’s analyfis and mine. I do not know exactly to what it is owing, but I can ‘aflert that, in five analyfes which I made of this ftene by different pro- cefles, I never had lefs than 12 of lofs. I prefume that a certain quantity of moifiure, and perhaps carbonic acid, re- mained in the new earth obtained ‘by M. Ekeberg, for it is chiefly in this point that we differ. He found 47,5, and I only from 34 to 35, becaufe I calcined it more ftrongly. NEW PUBLICATIONS, |: A Manual of a-Courfe of Chemifiry ; or, a Series of Experi- ments and Illufirations neceffary to form a complete Courfe of that Science. ‘By J. B. Bourrton LaGRrancGeE, Profeffor in the Central Schools of Paris, &c. Tranflated from the French, with 17 Plates. 2 Vols. 18 Shillings. Cuthel, and Vernor and Hood, 1800. [Continued from Page 282. ] In our Jaft we announced the publication of this ufeful work, and promifed a few extracts. We now fubjoin the following. Citric Acid [Concrete juice of lemons]. Scheele was the firft perfon who found means to obtain the citric acid cryftallized, and well feparated from the mu- cilage, which accompanies it in the juices of thofe fruits that furnith it. F The procefs for obtaining this acid, according to that che- mift, is as follows: Exprefs the juice of lemons, and leave it 3C2 at 376 New Publications. at re(t for twenty-four hours, to favour the feparation of the mucilage ; then filter it through paper, and faturate it with a quantity of the carbonate of lime. The citrate of lime, which refults from this faturation, being infoluble, is preci- pitated to the bottom of the liquor : when this depofit is well formed, draw off the fupernatant liquor, and wafh the preci- pitate until it becomes infipid and exceedingly white ; then decompofe this falt by the help of a gentle heat, with half its weight of fulphuric acid, diluted with fix parts of water; the fulphuric acid takes the lime from the citric acid; the greater part of the fulphate of lime formed is precipitated, and the citric acid remains free in the water. This acid may be obtained under a cryftalline form, by evaporating it to the confiftence of clear fyrup, and then fuffering it to cool. Dizé, who made feveral experiments on this fubjeét, found that an excefs of fulphuric acid was neceffary to deftroy the portion of mucilage, which the acid obftinately retains in its combination with the lime, and which oppofes its cryftalli- zation. He obferved alfo, that to obtain the citric acid per- fectly pure, it was neceflary to diflolve it, and to caufe it to cryftallize feveral times. The cryftals qbtained by Dizé were rhomboidal prifms, having their planes inclined to each other at angles of about 60 or 120 degrees, and terminated on each fide by fummits with four faces, which intercepted the folid angles. One part of diftilled water at the temperature of ten de- grees, according to this author, diffolves 1-25 of cryftallized citric acid, and, during the folution, cold equal to 13 degrees (29° F.) is produced. This acid reddens blue vegetable colours: when expofed to the fire in clofe veffels, with a pneumatic apparatus, it ig decompofed ; an acid phlegm, carbonic acid gas, and carbo- nated hydrogen gas, are obtained from it: and a little char- coal remains. Its cryftals eflorefce in the air. An agreeable lemonade may be prepared with this acid : for this purpofe Dizé propofes about half a dram of the acid diffolved in about two pounds of water, and a fufficient quantity. of fagar and o/eofaccharum, made with lemon peel. If Sera New Publications. 377 If a bit of fugar be rubbed againft a piece of orange or Jemon-peel, it will imbibe the volatile oil, and form an oleo- faccharum, foluble in water, and exceedingly proper for ren- dering certain liquors aromatic, [To be continued. ] Mr. Biarr, of the Lock Hofpital and Finfbury Difpens fary, affifted by feveral other refpeCtable furgeons, has been fome time engaged in writing a comprehenfive Sy/fem of me- dical and operative Surgery, adapted to the prefent improved practice at the London Hofpitals, &c. Mr. Witi1amM Henry, of Manchefter, has in the prefs, and in confiderable forwardnefs, a fmall work, intended, , partly, to facilitate the acquirement of chemical knowledge, to perfons entering on the ftudy, without the benefit of an inftruétor ; and, partly, as a pocket companion, for the ufe of more advanced fiudents. The firft part will contain di- ye&tions refpecting the beft mode of ftudying chemiftry ; and alfo, an arranged feries of experiments, neceflary to be performed by thofe who intend to become acquainted, by actual obfervation, with the chemical properties and habi- tudes of bodies. More minute direétions will be given, for conduéting thefe experiments with fuccefs, than are to be found in other elementary books. The fecond part will comprife fummary inftructions refpecting the analyfis of mineral waters, and of mineral bodies in general: and the third part will point out fome of the ufeful applications of chemical agents, in detecting adulterations, in difcovering poifons, &c. The work will form one {mall pocket volume; and it may be proper to obferve, that it will not at all inter- fere with the excellent little manual, lately publifhed by Mr. Parkinfon, the plan and objects of which are perfectly dif. ferent. INTEL- LTS J INTELLIGENCE, AND MISCELLANEOUS ARTICLES, , ROYAL SOCIETY OF LONDON. - To our prefent number we have prefixed a ftriking like- nefs of the Right Hon. and learned Prefident of this Society, a gentleman whofe unwearied zeal and princely liberality in promoting every thing that can advance fcience or add to the comforts of mankind, place him far above any eulogy in our power to beftow. We only fpeak the fentiment of the whole philofophical world, when we exprefs our ardent with that he may Jong continue to prefide over that learned Body, to which the world owes fo mahy difcoveries, and which has made fuch rapid advances fince this Right Hon. Gentleman was called to the chair he fo ably fills. On the 8th of January the Society met for the firft time. fince the Chriftmas recefs, when the cenclufion of Doctor Young’s paper on the mechanifm of the eye was read. ‘ An appendix by Dr. Herfchel, to his paper on the power _ of penetrating {pace by means of telefcopes, was read. The means extend fo far as to difeover nebule, the light of which, according to the velocity afcribed to that fluid, muft have been one million nine hundred and ten thoufand years. coming to this earth! A paper on impoffible quantities, by Mr. Woodhoufe, was read the fame evening. Jan. 15, a letter by Mr. Wilham Hay was read, giving an account of a fhip fpringing a leak in the Indian feas. The water, which gained fo faft as to render it impoffible, by pumps and the ufual means, to prevent the fhip from finking, was fortunately ftopped by pouring rice into that part of the fhip. The rice in four days diffolved, and in about eight days after became fo hard that with difficulty me hae Meteorology. 379 #t could be chifeled out when the fhip came into port. The author tates, that the fame means have been tried at other times, but not with the fame fuecefs, and furmifes that heat is neceflary. On the 22d was read a paper on the produétion of cold, by means of muriat of lime, by Mr. Walker. The firft conful of France tranfmitted to the Society * Voyage autour du Monde, par C. E. Marchand,” 4 tom. moft handfomely bound. The thanks of the Society were ordered to be returned to the firft-conful of France for this. prefent. , METEOROLOGY. The fol lowing particulars refpecting the ftorm on the oth of November, furnifhed by an intelligent correfpondent, can- not but prove interefting to fome of our readers : The preceding night sed been ftormy, with torrents of rain. At 9 A.M. wind abated and rain over. Thermometer.55°. Barometer, defcending ,"; inch ger hour, gave evident intima- tion of the event. About noon it had arrived at its loweft point, having dropped from 29,9 to 28,5 fince the morning of the fixth. At this time it was cloudy and nearly calm, when the wind veered ‘to the northward, and.in a few minutes blew from north-wef with aftonifhing violence for about an hour. - The quickfilver, which had fearcely become ftationiary, as fud- ely changed its direction, and continued to rife at the rate of 4 per bot: the whole afternoon. It became fiationary at 29,7, with a hoar-froft in the morning. The index-hand of an excellent wheel barometer, fixed againft a folid wall, was obferyed to librate continually during this rapid afcent, retreating about =2., and then advancing a little more. In the {pace of about fix hours, on this oceafion, the atmofphere paffed through near one-half of its total variation of gravity, which would require, in its ordinary courfe in this country, about as many days. | This impetuous irruption of denfe air from the northern ‘regions was probably occafioned by the fudden rarefaction, ‘, ‘gonfequent upon’a general precipitation of that water’ which % we ; during 380 © New Alkali.—Alhaline Pruffiat.—New Earth. during the preceding four weeks had been accumulating itt the atmofphere in a diffolved ftate. The lofs, in a certain, fpace of atmofphere, of fo great a quantity of elaftic fluid, and the operation of its difengaged caloric on the remainder, will at once account for the effect to thofe who are acquainted with pneumatics: ; THE NEW ALKALI. In our laft (p. 291) we mentioned that a Mr. Hahneman, of Altona, had announced the difcovery of a new alkali, to which he gave the name of pueum, from its property of {welling by heat to twenty times its original volume. Both Klapioth and Hermbftadt have lately examined this alkali, and found it to confit of nothing but boram: ALKALINE PRUSSIAT. Dr. A. N. Scherer has (in his journal) recornmended to chemifts to take up the idea fuggefted by Scheele, and to endeavour, by following the hint given by that author, to produce a perfectly pure alkaline pruffiat. Scheele ftates that pruffiat of mercury is perfectly free from iron; and that, were a combination of that kind decompofed by an alkali; the refult would certainly be pruffiat of alkali entirely free from iron. A NEW EARTH. The particular properties of a new fpecies of earth called Ytiria, of which an account was given by Ekeberg in the third volume of Scherer’s journal, have been confirmed by Klaproth, who lately read a paper on this fubjeét at the Royal Academy of Berlin. Vauquelin has alfo analyfed the ftone which produces this earth.—See his Memoir on this fubftance in the prefent number, p. 366. CHEMICAL EXPERIMENTS ON THE MATTER OF BLACK VOMIT. A memoir on the analyfis of black vomit, by Dr. Cathrall, was read before the American Philofophical Society at Phila- . delphia, on June 20, 1800. This is a very interefting and inftructive paper. The experienced and intrepid author has given a defcription of the black vomit, has analyfed the fluids ejected a few hours before the commencement of black vo-« 3 maitingy : Black Vomit.—Tetanus cured by the Cold Bath. | 381 miting, and exhibited a fet of experiments on the matter of black vomit itfelf: to which he has added, experiments to afcertain the effects of black vomit on the living fyftem of man and other animals, and a fynopfis of the opinions of _ authors concerning its formation and qualities. The expe- riments fhow that this fingular morbid excretion contains an acid, which is neither carbonic, phofphoric, nor fulphuric ; and, what our readers will hardly expect, that the black vomit may be fmelled, tafted, and fwallowed, without in- ducing yellow fever, or even any ficknefs at all: fo little in- fection or contagion does it feent to contain! He concludes it to be an altered fecretion from the liver. TETANUS CURED BY THE COLD BATH: Communicated in a Letter to Dr. R. H. Ancuer, of Balti- more, by Dr. Witt1aM Harris, of Pennfylvania*. In the autumn of 1799, I vifited a labourer, about thirty years of age, of a {lender make, but healthy, who was fuddenly . feized, whilft in bed, with fpafms in his lower extremities, which fhortly after affected his whole fyftem, but particularly his ftomach, which was drawn in a hard lump, and protruded to a confiderable diftance. His pains were excruciating. He had a violent vomiting and purging, which came on an hour after feizure, and continued about two hours. At one time he had emprofthotonos, at another opifthotonos, to the greateft degree, and fometimes complete tetanus. The mufcles of his face were drawn in every direétion, and de- glutition entirely impeded. His pulfe varied much, but was generally feeble. He could affign no caufe for the attack. I bled him, put him in the warm bath, and ufed all the re- medies laid down by medical writers, but without any mi- tigation of his pains, or relief to his {fpafms. At this time, which was twenty hours after the attack, when the cold fweat of death appeared to be upon him, his tongue had refufed its office, his eyes funk, having a glafly appearance, and his exit was every moment expected, it oc- ‘curred to me that the cold bath might have a good effect ; and, after confulting his friends, who readily acquiefced, I * Medical Repofitory, vol. iv. p. 76, Vor. VIII. 3D had “ 382 Treatment of Locked-Jaw by Eleétricity. had him, in this ftate, carried in a blanket to a forge-dam which was at hand, and plunged in. He was then infenfible. His fpafais immediately abated, and, in twenty minutes, to- tally ceafed. The debility induced by mufcular exertion was fuch that it required feveral days before he could be removed ; after which he rapidly recovered, and is at this time perfeétly well, This was a complete tetanus; and, I think, tetanus from wounds, &c. would yield to the fame mode of treatment. TREATMENT OF LOCKED-JAW BY ELECTRICITY. Dr. Samuel Perry, of New-Bedford [America], has com- municated to the public the fuccefsful refult of two experi- ments, in curing the locked-jaw by means of electricity. Previous to the application of the eleétrical fluid, recourfe had been had to bleeding, cathartics, antifpafmodics, the warm bath, and opium applied internally and externally, without the leaft effect in either cafe. But a {mall receiver being filled, and difcharged through the jaws of the perfons affected, they flew open inftantaneoufly. In one cafe the complaint was entirely removed by three fhocks; in the other, by an occafional fhock for a few days. Both the patients were {trong and healthy perfons, the one a man and the other a woman, and the mode of treating them had been fimilar. ' Dr. PEARson’s Letures on the Materia Medica, Praétice ‘of Phyfic and Chemiftry, will recommence at the Elaboratory, Whitcomb-ftreet, Leicefter-fquare, on Tuefday, February 3, at eight in the morning. Se aag / INDEX Us 983" INDEX 0. Oko ABILDGAARD’s s (Profeffor) experiments with carbon of blood,. 328. Acid, fluoric, to prepare, &c. 280, Acid of mellite, characters of, 332. Acid, citric, or Concrete juice of lemons, to prepare, 375. Acids, pyromucous, pyrotartareous, pyraligneous, on the identity of, with acetous acid, 40. Africa, Damberger’s travels through, 240, 3.53. Agriculiure. On the method of cultivating the Syrian filk Fain! 149. , ufeful hints in, 191. -——, premiums for eflays on, 284. Wilaks, A ncw.one difcovered ; its properties, 291. A fraud, 380, Alkaline pruffiates, a hint concerning, 380. Alps, hints to thofe who may vifit the, 53, 109. Amethyfts fuled by the London Philofophical mpeicty, 256 Analyfis of various plants, 185. of honey-fione or mellite, 329. of Gadolinite, which contains yttria earth, 3/6. Animal eleétricity, experiments and obfervations on, 88, 171. Antiquaries, proceedings of the Society of, 182. Antiquities. On an antient infcription found in Egypt, 94. Afiatic Society, proceedings of the, 85. Refearches, account of Vol. VI. 84. Aftragalus, remarks on, 92. / Barometer, electrical experiments upon, 315. Beckmann on the difcovery of Szignette’s fait, 166. Black vonit, experiments on, 340. Blair, Mr. notice of a new work by, 377. Blood, Abildgaard’s experiments on carbon of, 323. Blow-pipe, defcription of a newly invented Double, 2b, Beard of Azriculiure, premiums offered by the, 284. Bonaparte, prefent from, to the Royal Society, 379: Branjon, Mr. on vaccine inoculation, 308. 3D2 Caloric, 384 | INDEX. | Caloric, Tilloch on the received dodtrines refpeing, 70, 119, 211. * , exiftence of, in the electric fluid, 195, 316. Camphor diffolved in water by means of carbonic acid, 291- Carbon of the blood, Abildgaard’s experiments on, 328. Carburet of fulphur, on a newly difcovered, 169. Carnot’s reflections on the theory of Infinitefimal Calculus, 222, 337- Charcoal, on the proportions of, in wood and pit-coal, 169. | -, hydrogen feparated from, by electricity, 200. Chemical and mineralogical nomenclature, Kirwan on, 172, 202. Chemifiry, new difcoveries in, 49, 170, 192, 291, 367, 380. --, account of Lagrange’s manual of, 279, 375. Chryfolite fuled by heat excited by oxygen gas, 24. Citric acid, to prepare, 375- Colouring, thoughts on, by Mr. Dayes, 1. Colours of thin tranfparent bodies, obfervations on, 179. Compvfition, the principles of, in panting, 293. Condudors for lightning, experiments on the tize of, 319. Cooper on the deftruction of the membrana tympani, 359. Cow-pock, information refpecting the, 305, 308, 309. Cryflallography, remarks concerning, 182. Cryftals, rock, fufed by heat excited by oxygen gas, 264: Cuvier on the Egyptian Ibis, 61, Damberger’s travels through Africa, 240, 353. Dayes’s thoughts on colouring, t. Dayes-on landfeape painting, 293. Deaf perfons made to hear mufic, 93. Decandolle’s experiments on vegetation, 188. De Carro (Dr.) on vaccine inoculation, 305. Decompofition of bodies by ele&tricity, 199. Declivities of mountains, Kirwan’s eflay on, 29. Demours’ operation for refloring fight, 148. Diamonds, experiments on the combultibility of, 23. Difeafe. A very lingular one in South America, 290. Dixon’s tranflation of Carnot on Fluxions, 222, 334. ‘Ear, on the deftruétion of the membrana tympani of the, 359: Eleéoral Academy at Erfurt, tranfaGtions of the, 88. Elediric experimenis, account of Van Marum’s, 193,, 318. Emeralds tufed by heat excited by oxygen gas, 263. Empyreumatic acids, on the identity of the, 40. Efchen, F. A. fome account of, 164, Evaporation, eleétrical experiments on, 314, 315. Fifb, experiments on the fhining of, roo. Fluoric acid, account of ; way to obtain, 280, Fluxions, Carnot on, 222,.337- Foffils, notices refpecting, 96, 290. French National Inftitute, proceedings of the, 8g, 187,-286. Gadolin, N INDEX. 385 Gadilia, a new earth difcovered by, 367. Gadolinite ftone, analyfis of the, 366. Galvenifin, experiments in, 8, 171+ G -rnets fafed by heat excited by oxygen yas, 263. Gafes, production of, by electricity, 196. 3 Gafometer, defcription of that of the London Philofophical So- clety,) 322. ' ; Gafo-cal.rim-t-r, def{cription of a propofed, 216. Gems, experiments to fufe, 21, 262, 322. Glacier of Buct, accident to a traveller on the, 53, 109. Gum, tragaéanth, on the altragalus which produces, g2. Hearinz, mode of, when memb. tymp. is deftroyed, 365. fea!, Tilloch on the received doétrines refpecting, 70, 119, 211, » production of, by elcétricity, 195, 316. Fiat excited by oxygen gas, experiments on the effeGis of, 21, 262, 322. Fieat and light, experiments on, 9, 16, 126, 181, 253. Heary, Mr. W. notice of a new work by, 377. Flercn on the geneval nature of light, 161. He fchel (Or.) on the power of penetrating fpace, 378. Fier{che?’s (Dr.) experiments on heat and light, 9, 16, 126, 18%, 253. How: on the deftruction of the membrana tympani, 359. Honey-frone, Vauquelin’s analy fis of, 329. Hydrogen, eleCtrical experiments to produce, from charcoal, 2c. Tbis of the antient Egyptians, memoir on the, 61. Zufinit fimal Calculus, Carnot on the theory of, 222, 337+ Inoculation, on the Vaccine, 305, 308, 300. Inferipticn, remarks refpeCting av antient, 94. Tridis or Corona, account of the, 78. fron ores, on the cryftallifations of, 182. Facynth fufed by heat excited by oxygen gas, 254. Fargoons expoted to ignition with oxygen gas, 262 Jerboa, Olivier on the, 89. Kirwan’s eflay on the declivities of mountains, 29. a nomenclature, 172. - Lagrange’s Manual of Chemiftry, account of, 279, 375. Landf-ape painting, eflay on compofition in, 293. Leaks in fhips topped by applying rice, 378. Learned Societies, proceedings of, 85, 181, 283, 378. Light, Dr. Herfchel’s experiments on, 9, 16, 126, 18. - Light, Mr. Heron on the general nature of, 11. Light of lamps, efle&s of, on vegetation, 188, Lightning, experiments on conductors for, 319. : Locked» 386 INDEX. Locked-jaw cured by cold bath, 381. — cured by eleétricity, 382. : London Philofophical Society’s experiments on gems, 21, 262, 322, Luminous appearance of the fra, obfervations on the, 97. ; Mellite, Vauquelin’s analyfis of, 329. Membrana tympani, obfervations on the deftruétion of, 359. Meteorological remarks, 2860, 292, 379. Mice and rats, Mr. Taylor’s vecipe for deftroying, 118. Milk, good for fpafmodic affections, 89. Mineralogical and chemical romenclaiure, Kirwan on, 172, 202. Minzral waters, Dr. Saunders’s treatife on, 80. Mitchill, (Dr.} letter from, to the Editor, 326. WMountains, Kirwan’s eflay on the decliyities of, 29. Natura! Hiftcry, proceedings of the Saciety of, at Paris, 182. — » Notices refpecting, 290. Newton's explanation of the irides of the fun, &c. oppofed, 79. -- theory refpeding tranfparent bodies, oppoled, 180. New publications, 78, 179, 375- Nit e weakens the nervous fyftem, 88. Nomenclature, Kirwan on chemical and mincralogical, 172, 202. Nowell on the cow-pock in France, 309. : Oleo-faccharum, to render liquors aromatic, how made, 377. Opal fufed by heat excited by oxygen gas, 264. Opium prepared in Germany, 89. England, 89, Note. Ornitholites, remarks on, 93+ Oxalic acid compared with acid of mellite, 333. Oxides, eleétrical experiments on the reduction of metallic, 315. Oxide of carbon, on the proportions of, in wood.and pit-coal, 169, Oxygen gas, on the effecis of heat produced by, 21, 262, 322. Painting, On the mechanical part of the art, 1. --, effay to illuftrate compofition in landfcape, 293. Pendulums, on meafuring the ofcillations of, 287. Perfpiration, infenhble, electrical experiments on, 194. Philomatic So-iety, proceedings of the, 184. Pholphorifed hydrogen gas, on the properties of, 154. Phofphorus, elettrified in vacuo, 316. Pictet’s cautions to thofe who may vifit the Glaciers, 53, 109. Plants, analyfis of various, 185. Platina, experiments on the fufion of, 265. Pneum, on the alkali fo called, 291, 380. Prouft on charcoal aud carburet of fslphur, 169. Pruffats, a hint refpeing, 380. Publications, account of new, 78, 179, 375. Pulfey effect of electricity on the, 194. Pyrometer <9 INDEX 337 Pyrometer pieces fufed by the London Philofophical Society, 262. Pyromucous, pyrotartareous, and pyroligneous acids, on the identity of, with acetous acid, 40. Rats and mice, Mr. Taylor’s recipe for deftroying, 118. Rays, invifible, of the fun, Dr. Herfchel on, 9, 16, 126, 253. RefraGory fubftances, experiments to fufe, 21, 262, 322. Refrangibility of invifible rays of ‘the fun, Dr. Herfchel on, g. Royal Society of London, tranfactions of the, 181, 283, 378. Rubies interefting experiments on the fulibility of, 27, 262. Sapphires. attempts to fule, by means of oxygen gas, 25. Saunders’s (Dr.) treatife on mineral waters, account of, So. Sauffure (the fon) on influence of foil on vegetables, 184. Sea, on the luminous appearance of the, 97. Seignette’s falt, on the difcovery of, 166. Shadows, refult of experiments on, 288. Ship, leak in, ftopped by applying rice, 378. Sight, method to reftore, in certain cafes, 148. Smutty wheat, to convert, into good flour, 192. Society for the Encouragement of Avis, notice by the, 284. Soil, influence of,.on conitituent parts of vegetables, 184. Solar rays which cccafion heat, Dr. Herfchel on, 16, 126, 253. Spinel ruby, attempt to fufe the, 262. Summers of 1800 and 1792 Compared, 286. Swallows, on the fubmerfion of, 107. Swiffrland, cautions to thofe who may vifit the mountains of, 3, 109. ‘ Syrian filk plant, on the cultivation and ufe of, 149. Tartrite of foda, on the difcovery of, 166. Terrefrial rays that occafion heat, experiments on, 16, 126, 253. Tetanus cured by the cold bath, 381. cured by eleétricity, 382, Tides, examination of St. Pierre’s hypothefis of the, 134, 267. Tilloch on heat or caloric, 79, 119, 211. Topaxes fufed by the London Philofophical Society, 26, Tran/parent bodies, obfervations on the colours of ‘thin, 179, Travels, Damberger’s, through Africa, 240, 353. Vaccine inoculation, on the progrefs of, 305, 308, 309. Van Marum’s elegtrical experiments, 193, 318. Vaf.illi-Eandi on animal eleétricity, 171. Vauguelin’s analyfis of mellite or honey-ftone, 32g. | -———— gadolinite, 366. Vegetable acid found in the mineral kingdom, tg2. Fegetables, influence of foil on conttituent parts of, 184. ; , electrical experiments upon, 195, 314. Vegetation, experiments on, with artificial light, 188. Venetian method of colcuring, thoughts on the, 1. Vermilions fuled by heat excited by oxygen gas, 263. Fs 4 W aves 388 INDEX. Waves on the furface of water, refult of experiments on, 238, Weevils, a fimple and efficacious way to deltroy, 192. Wedzewood’s pyrometer fufed by the London Phiiotophical Society, 7 202. Wood's examination of St. Pierre’s hypothefis of the tides, 134, 267. Yitria carth, a principle in gadolinite, 366, 380. Zoolocy, account of Dr. Shaw’s general, 82. » remarks concerning, 137. ERRATUM. Page 8, line 12, for rudded out, read eiled ont. END OF THE EIGHTH VOLUME. TO THE BINDER. Place the Head of Sir Josern Banxs at the beginning, and the ether Plates at the end, of the Volume. Printed by Davis, Wixxs, and Tavior, Chancery-Lane.- ed x ~ Philo. Mag. PLT Vol. VIM im Ss ————— i HHH} | Lowry seule “> Philo. Mag. 21M. Vol. VI. \| wl i! i i= i i = HH} \} = | = | Bll aml = te ; ve *) > ¥ . ry t 4 4 Cat 4 url / ' ms a .. A - 4. fs ‘ 4 : 7 § - ‘ ‘ j J ait | , ‘ i Vi. PLM Vil. VEIL, Phito. IBIS wrulfe DIOPY es = } 7 a gD rh . tl | ly f Philo. Mag. Fl. V. Vel. VIZ. fig. 2. 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