Experiments on the Chemtcaf PrcdttBion and Jgtney of EUEfricifj. 341 



Experiment 9. I have found that, by ufing an arnalgam of filver or of placinti, which 

 are not liable to be oxidated, I could obtain no eledricitjr. An amalgam of tin, on the 

 contrary affords a good degree of excitement. Zinc a6ls dill better ; but the beft amalgam 

 is made with both tin and zinc, a mixture which is more eafily oxidated than either metal 

 feparately. 



Experiment 10. But, as 3 farther trial whether oxidation aflifts in the produ£lion of 

 cleclricity, I mounted a fmall cylinder, with its cufliion and coiulu£tor, in a veflel fo con- 

 trived, that I could at pleafure change the contained air. 



After trying the degree of excitement in common air, I fubftltuted carbonic gas, and 

 found that the excitement was immediately deftroyed, but that it returned upon re-admiffion 

 of atmofpheric air. 



In conformity to this hypothecs, we find that the metal oxidated is, in each cafe, in a 

 Cmilar (late of electricity v for the cufljion of the machine, by oxidation of the amalgam 

 adhering to it, becomes negative; and in the fame manner, zinc, oxidated by the accu- 

 mulated power of an eledlrie pile, or Gmply by aftion of an acid, is alfo negative. 



This fimilarity in the means by which both ele£tricity and galvanifm appear to be ex- 

 cited, in addition to therefemblance that has been traced between their efiiCts, (hews that 

 they are both effentlally the fame, and confirms an opinion that has already been advanced 

 by others, that all the differences difcoverable in the efFe£ls of the latter, may be owing to 

 its being lefs intenfe, but produced in much larger quantity. 



V. 



An Account of feme Galvanic Comhinaiions, formed by the Arrangement offmgle Metallic Plates 

 and Fluids, analogous to the neiu Galvanic Apparatus of A4r. Volta. By Jldf. Humphry 

 Davy, LeElurer on Chcmiflry in the Royal Inflitution *, 



I. oaLL the galvanic combinations analogous to the new apparatus of Mr. Volta, which 

 have been heretofore defcribed by experimentalifls, confifl (as far as my knowledge extends) 

 of feries containing at lead two metallic fubflances, or one metal and charcoal, and a ftra- 

 tum of fluid. And it has been generally fuppofed, that their agencies are, in fome meafure, 

 connefted with the different powers of the metals to condu(Sl: eleftricity. But I have found 

 that an accumulation of Galvanic influence, exa£J:ly fimilar to the accumulation in the 

 common pile, may be produced by the arrangement of fingle metallic plates, or arcs, with 

 different ftrata of fluids. 



The train of reafoning which led to the difcovery of this fatSt, was produced by the ob- 

 fervatlon of fome phsenomena relating to the conae£i:ion of chemical changes with the evo. 

 Uuion of Galvanic power. 



* Philofophical Tranfaaions, I SOU 



It 



