ON GALVANISM. $\ 



Mr. W. imputes to me alfo the miftake of having " ob- Obfemtionj r #» 

 ferved that the fenfation is in proportion to the furface afted f P sd ' R Sg ai - 

 on ;" adding, that " the experiments of the French philofo- 

 phers proved, that the action of galvanifm on animal fub- 

 ftances is in the ratio of the number of plates employed, and 

 not the furfaces expofed." This is another inftance of the 

 inaccuracy of Mr. W.'s obfervations ; for fenfation I never 

 mentioned; nor aclion on animal fubftances ; not at all confi- 

 dering the intenfity, but the quantity only of the eleclric fluid 

 produced ; which may not always correfpond ; for the charge 

 of fmall plates being weak, although according to their fur- 

 faces, the electricity meets with almoft infurmountable ob- 

 structions from the interlaces of the pile; which to a fironger 

 charge, from larger plates, are very trifling impediments: 

 but Mr. W. thinks, himfelf, that " the produ&ion of galva- 

 nic phenomena is always proportionate to the degree of oxi- 

 dation ;" and muft not the quantity of metal oxidated be in 

 proportion to the furface expofed to the water ? The French 

 philofophers, too, have " concluded (I quote Mr. WVs own 

 words, from p. 207 of your laft volume) that the effects of a 

 galvanic battery on metallic fubftances, are in proportion to 

 the furfaces of the plates employed:" Muft we not then fuf- 

 pecl the experiments to have been imperfect which led them 

 to conclude, if they have fo concluded, that the effefts on. 

 animal fubftances are different ? 



Whether I " fet out too hypothetically as to electricity 

 being a modification of caloric/' is a queftion on which many 

 of the moft celebrated men of fcience would differ from Mr. 

 W. in opinion, " Pars invenit utraque Cavjfas ; yet it appears 

 to me, that the experiment noticed by a Correfpondent, p. 173, 

 almoft determines it : " If the gas which is produced from one 

 of the wires communicating with the pile in the water, be 

 united and 'inflamed with the other in a juft proportion, the 

 water which is common to both is reproduced, and common 

 fire in great abundance." Thus the electric fluid, which alone 

 conveys the oxigen and hidrogen from the water, actually be- 

 comes, when differently modified by combufiion, for there 

 is " no evidence of the prefence of fire until this point of 

 time," active caloric. 



But fuppofmg, with Mr. W. that the dearie matter and 

 caloric are perfectly diflind bodies, we have Hill the fame 



re a fon 



