ON GALVANISM. JQ7 



while the capacity of oxigen is increafed for (.he fame fub- 

 ftance; two facts for which I fhould be glad to know Mr. W.'s 

 authority. He nowfuppofes the oxigen to be attracted by the 

 pofitive wire, where it faturates itfelf with the electricity 

 neceffary to conftitute its gafeous form. The hydrogen, on 

 the other hand, is attracted to the negative wire, to which it 

 muft give itsexcefs before its elafiic form can be effe&ed. 



After all the labour Mr. W. has bellowed to bring the hydro- Obje&lon. 

 gen to one wire, and the oxigen to the other, he does not 

 appear, in my opinion, to have fucceeded ; for the excefs of 

 electricity in the hydrogen would be given to the deficient 

 oxigen, and the gaffes would be given out in the middle of 

 the liquid, and not at the ends of the wires. 



Mr. W. mentions the curious fad of water not being de- Water not de- 

 composed in a very (mall tube, and alfo, that no decompo- compofed in a 

 fition takes place when the wires in the liquid are as much 

 as eight inches diftant from each other. I have long been in 

 poffeftion of thefe facts : I have varied thefe experiments by Saline folutions 

 ufing, inftead of pure water, different folutions of falts, with are decompofed. 

 a view to increafe the conducting power of the liquid me- 

 dium : I found a folution of carbonate of potafii to anfvver Carbonate of 

 very well : I placed the wires in the ends of a tube of moreP 012 ' 11 ' 

 than a yard in length : The decomposition went on very ra- 

 pidly : I foon obferved the pofitive wire coated with beau- 

 tiful carbonate of copper, at the fame time I obferved a ga- 

 feous fubflance difengaged : I found it, by the teft of lime- 

 water, to be carbonic acid gas. I obferved the difengage-p ur e potaih. 

 ment of this gas, after I had rendered the potafh very caufiic 

 by lime. 



I afterwards ufed a tube of -^th of an inch in diameter, common fait, 

 and live feet long, into which I introduced a faturated folu- 

 tion of common fait. After the wires were introduced, and 

 the communication made, I obferved bubbles of hydrogen 

 upon the negative wire, in about a minute after *. 

 I remain, Sir, 



Your's, &c. 



CHARLES SYLVESTER. 

 Sheffield, Jan. 20, 1805. 



* This corroborates the fact of the hydrogen palling invifibly 

 through the liquid. 



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