£xperitnentS on the Caufes of the Galvanic Phenomena, 595 



phuret of ftrontlan, produced no fenCble galvanic a£lion, though the moment the fides of 

 the pile weie moiftened with a little nitrous acid^ the ends gave, (hocks as powerful as. 

 thofe of a fimilar common pile. 



3. No phenomenon is more conftant than the ceflatlon of the a£tion of the common 

 galvanic pile in a vacuum * when the gage is below one-tenth. Suppofing the expulfion of 

 atmofpheric air from the water preventing it from oxidating the 2^nc, the fole caufe of 

 this ceflation, it follows, that a pile ought to a£l in vacuo when nitrous acid, or diluted 

 fulphuric acid, is the medium of connexion between the plates. Into each of the cells of a 

 feri'es of twelve pairs of filver and zinc plates, which had juft been moiftened with a little 

 water, a large drop of nitric acid was introduced : when the wires connefted with the 

 ends immediately began to produce the ufual appearances in water. The feries wa* 

 introduced under the receiver of an air pump, and the filver wire from its zinc end con- 

 ne£ted with a veflel of water that had been long boiled. The wire from its filver end was 

 fo fattened by refinous cement, to a Aiding brafs wire pafTing through the top of the 

 receiver, that it could be plunged at plcafure Into the water when the vacuum was made. 

 The receiver was cxhaufted till the gage ftood at ^c,- of an inch, when the communication 

 was effedled. The zinc wire immediately began to oxidate, and gas was given out round 

 the filver wire. The procefs went on for many minutes, and when it had ceafed, was 

 not fenfibly revived by the admiffion of the atmofphere. In another experiment the fame 

 phenomena were obferved. Gas appeared to be given out more rapidly from the filver 

 wire than in the atmofphere ; but this was from the diminution of preflure. The oxida- 

 tion was certainly lefs : which may be eafily accounted for, when we confider, that no 

 nittous acid could be recompofed in vacuo, as in the atmofphere from the nitrous gas 

 difengagcd between the plates, and that, in confequence of the diminilhed preflure, fome 

 of the acid muft probably have aflumed the aeriform (late. 



A drop of fulphuric acid, poured into each of the moiftened cells of twelve pairs of 



plates, enabled the wires from the ends to efFe£l the ufual changes in pure water for rather 



' more than half an hour in vacuo, the gage being at -j^-' The oxidation went on nearly as 



vividly as in the atmofphere, and what is rather remarkable, fome gas was given out from 



the oxidating wire, though very little was produced from the filver wire. 



4. The refults of the laft experiment are interefting not only from their coincidence 

 with the other fadts, but likewife becaufe they afford proofs that the prefence of oxygen 

 in that loofely combined or peculiar ftate in which, when abforbed by combuftible 

 bodies, it produces inflammation, and in which, in my infant chemical fpeculations, I 

 fuppofed it to be combined with the matter of light, is not eflential to the galvanic 

 eflTeds. Whether water is abfolutely efl'ential, we fliall find fome difficulty in deter- 

 mining, as it exifts in larger or fmaller quantities in all the non metallic fluid galvanic 

 condu(P:ors that have been yet experimented upon. The following fa£l: is in favour of 



• See Colonel Haldane, Phil. Journal, No. 43, Vol. IV. and my laft paper, No, 44. 



3 E 2 its 



