2 1 o . Chanlcal ProduBlon and jlgemy of EleSlrlc'ily. 



obfervcd^ to have in the elcftric pile, may be afccrtaincd by 

 other means. 



In the precipitation of copper bv filvcr, an inftiincc of dc- 

 oxid>uion (or phlogilticalion) by negative clecliicity has been 

 mentioned : the oxidatinc; power of pofitive eleftricity may 

 be alfo proved h\ its efi'c ot on ve<retablc bhie colours. 



Expir. 8. Having coloured a card with a llrong infufion 

 of litmus, I palled a current of elecfric fparks along it, by 

 means of two fine gold points, touching it at the diftance of 

 an inch from each other. The efl'ed, as in other cafes, de- 

 pending on the fmallnefs of the quantity of water, was molt 

 • diicernible when tnc card was nearly drv. In this ftatc, a 

 veK^\- few turns of the machine were fufHcicnt to oceafion a 

 rcdnefs at tiic yofitive wire, verv manifefl to the naked eye. 

 The negative wire, being afterwards placed on the fame fpot, 

 foon reltorcd it to its original blue colour. 



By Mr. Volta's apparatus, the fame eflfciSls are produced 

 in much lefs time. 



Befidc the fimilarity which has thus been traced between 

 tlie etfccis of elcAricity excited by the common machine and 

 thofe obferved from the eledric pile, I think it appears alfo 

 probable that they originate from the fame fouree. 



With regard lo the latter, its power is now known to de- 

 pend on oxidatioh ; fo alfo does the excitement in the former 

 appear very much to depend on the fame procefs ; for, 



Expcr. g. I have found, that by ufmg an amalgam of filver 

 orofplatiua, which are not liable to be oxidated, I could 

 obtain no electricity. An amalgam of tin, on the contrary, 

 affords a good degree of excitement. Zinc a6ls (lill better ; but 

 the belt amalgam is made with Iwth tin and zinc, a mixture 

 which is more eafily oxidated than either metal feparatelv. 



£a />(■;-. lo. Bui, as a further trial whether oxidation alilfls 

 in the production of cleArieity, I mounted a fmall cylinder, 

 with its cufliio-n and condurtor, in a veflel fo contrived that 

 I could at pleafure chan<.!;e the contained air. 



After trying the degree of excitemciit in common air, I 

 fubdituted carbonic gas, and found that the excitement was 

 immediately dellroyed, but that it returned upon readmiflioii 

 of almofpheric air. 



In conformity to this bypofhclls, we find that the metal 

 oxidated is, in each cafe, in a fimilar ftale of eleclrieity ; for 

 the culhion of the machine, by oxidation of the amalgam 

 adhering to it, become? negative ; and, in the fame manner, 

 zinc oxidated by the accumulated power of an eleftric pile, 

 or fimply by aftion of an acid, is alfo negative. 



This 



