288 M. De la Rive's Researches 



m 



in the circuit than when it is isolated ; in the latter case the 

 two electricities have a tendency to reunite immediately in a 

 larger proportion than when the pair is placed between two 

 others, one of which takes possession of its positive electricity 

 and the other of its negative : in addition, the current which 

 is established in the liquid in which the oxidable element of 

 the pair is immersed, facilitates the oxidation of that element 

 by decomposing the liquid, and consequently augments the 

 quantity of electricity developed. This is particularly the 

 case when piles are employed consisting of pairs of copper 

 and distilled or amalgamated zinc; the current itself is at 

 once cause and effect. Sometimes the pair introduced is so 

 feeble that it can only be considered as an imperfect conduct- 

 or interposed in the liquid which unites the opposite elements 

 of the two pairs between which it is placed ; its influence then 

 consists solely in diminishing the quantity of the opposite 

 electricities of these pairs which would neutralize each other, 

 and consequently the current of all the other pairs and that 

 of the whole pile. If the diminution of effect be due to the 

 cause which has just been stated, it ought to be the same 

 whatever be the direction in which the elements of the pair 

 introduced are disposed ; and I have had opportunity of ve- 

 rifying that such is the fact. 



We shall now inquire whether the theory which has just 

 been enunciated will explain all the phaenomena presented by 

 voltaic piles ; and to this end we shall investigate in succession 

 their tensile and their dynamic effects. 



Tensile effects. — When a pile is insulated and its two poles 

 are not united by a conductor, an equal quantity of positive and 

 negative electricity should, in agreement with what we have just 

 seen, be found at each of them. These two electricities, con- 

 stantly carried towards a pole, would in the end acquire an 

 enormous tension if the pile itself which separates them werenot 

 a more or less perfect conductor, which allows them in part to 

 reunite in neutralizing each other; it acts in this respect as the 

 band of moist paper placed by Volta between the two poles of 

 the pile, or as a secondary pile placed in the same position. 

 Commencing at each of the poles, an electricity should there- 

 fore be found in the pile of the same nature as that of the pole, 

 but constantly diminishing towards the middle where it is null, 

 because that is the point of meeting and consequently the 

 place of neutralization of the two electricities ; and this is 

 precisely what experiment demonstrates. The recomposition 

 of the electricities of the two poles, which takes place through 

 the pile itself, is proved by the following fact, that when one 

 of the poles is put in communication with the earth, the other 



