HISTORY OF GALVANISM. 87 



K. 



hibit any of its effects, or indeed not to indicate its 

 presence ; and that when these are manifested, it 

 always depends upon some retarding cause. The 

 electrical and chemical effects are supposed to ori- 

 ginate from different parts of the pile, or from dif- 

 ferent groups, considered in their relation to th$ 

 parts contiguous to them. The electrical effects 

 consist simply in the combination of the two 

 metals, each pair being separated by a non-metal- 

 lic conductor ; while for the chemical effects, ter- 

 nary groups are necessary, the two metals with a 

 fluid between them. This distinction between the 

 two sets of properties, or the two modes of action, 

 is supposed to be proved by the different effects 

 which are produced by the pile in its three states 

 of dissection. In the pile dissected in the first 

 manner, which indeed may be regarded as equiva- 

 lent to the instrument in the continuous state, 

 both the electrical and chemical action takes 

 place : for here are the two metals, either in con- 

 tact, or connected by the wire frames, for the elec- 

 trical effects ; and for the chemical effects, there 

 are the two metals with the wet cloth interposed. 

 In the pile as dissected in the second manner, there 

 are the binary groups, i. e. the metals in contact, 

 and accordingly they produce the electrical effects ; 

 but we have no chemical effects, because they have 

 no fluid between them. In the third dissection* 

 no effects are produced ; we have not the chemical 

 effects, because the metals have not the wet cloth 

 between them, and we have no electrical effects, 



