Xll 



C O N T E NTS. 



Zinc in the Galvanic circuit undergoes no oxidation at common temperatures vvltli pure water ; 

 but it is oxided when the water contains either atmofpheric air, oxygen, nitrous gas, nitrous 

 acid, or marine acid, &c. Thefe fubftances at the fame time undergo chemical change. The 

 pile of Volta does not a£l with pure water ; but it does when the water contains any of the lafl 

 enumerated fubftances. Its power appears to be proportional to the oxidation of the zinc ; 

 which may therefore be efteemed the caufe. This conclufion leads to methods of conftrufling 

 piles of immenfe power. Experiments in proof. Pile with nitroui acid at leaft fix times a^ 

 ftrong as the common pile. 



II. On raifing Water by the Engine of H. Goodwyn, Efq. through double or 

 treble the Space of the defcending Column, and on the proper Arrangement 

 to make it require no Attendance. By a Correfpondent - 342 



III. Obfervations and Experiments on Light and Heat, with fome Remarks on 

 the Enquiries of Dr. Herfchel, refpefting thofe Objefts. In a Letter from 

 Mr. JohnLeflie - -. - - p. 344 



Experiments by the photometer, to determine the abforbent and reflefling powers 'of. coloured fub- 

 ftances with regard to radiant heat ; and the heat afforded by the different rays of the folar 

 fpeftrum. Remarks on the optical difcoveries of Newton, and the late experiments of Dr. 

 Herfchel ; againft the latter of whicli and the inferences thence drawn, various objeflions are 

 flrongly urged. Recommendation of the optics of Bouguer and the Photometria of Lambert. 



IV. Account of a Memoir of M. Prouft, on feveral interefting Points in Che- 

 miftry - - --' -p. 350 



Oil of camphor. Method of obtaining the pure taning principle. Theory and formation rf ink 

 with galls and fulphate of iron. Sulphuric acid profitably obtained from the refidue of fulphuric 

 ether. Deteflion of phofphoret of carbon iu the diftiliation of phofphorus. EfTeniial oil in 

 crude iron. Native iron of Peru, which is confidcrably dufilile, and does not ruft; itis.fbund 

 to contain nickel. Experiments on fiefli. Pyritc of the Incas. Purification of zinc. 



V. Experiments on the folar and on the-. terreftrial Rays that occaffon Heat; 

 with a comparative View of the Laws to which Light and Heat, or rather 

 the Rays which occafion them^ are fub]e£t, in order to determine whether 

 they are the fame or different. By W il'liam Herfchel, LL. D. F. R. S. 



. u . , P-360 



A feries of experiments were made in which tlie light of the fun, of a candle, of the folar prifmatic 

 fpeftrum, of a red hot poker, and of a coal fire, were feverally reflected from metallic mirrors, 

 and produced heat. The invifible radiance from the fame objefls was alfo made to undergo 

 optical refleflion and condenfation, and produced heat. Experiments of the fame kind were 

 made by diverting the vifible as well as invifible radiance, of the fame obj efts out of its courfe 

 by refraftion, and condenfing it by the' fanie nieatis, in all which ca/es heat wa;s produced. 



VI. On the Arragonite of Werner. By Cit. Hauy - p. 367 



VII. On the true Origin of Refin, known by the Name of Sandarac, and on 

 that of Gum Arabic, by M. Schoufboe - - p. 369 



VIII. Remarks on the Memoir in whicl* M. Girtanner examines whether 

 Azote be a fimpld or compound Body. 'By Cit. Berthollet p. 37 1 



4 IX. On 



