THEORY OF GALVANISM. 



employed, we obtain the evolution of electricity in 

 greater or less quantity, and in a more or less in- 

 tense state. 



The great discoveries that have been made by Davy's h y - 

 Sir II. Davy, in his application of galvanism to pot 

 chemical decomposition, and the importance which 

 must attach to all his opinions upon the subject, 

 will make us anxious to inquire, what view he 

 takes of the question that has now been discussed. 

 I have already related the experiments which he 

 performed on the chemical action of the pile ; and 

 it appears that he formerly considered it as the pri- 

 mary cause of the phenomena. This opinion, 

 however, he afterwards retracted, and adopted an 

 hypothesis which he conceived might reconcile the 

 doctrine of Volta with the experiments of the 

 English chemists. He supposes, that both electri- 

 cal and chemical actions are necessarily concerned 

 in the production of the effect; that the former 

 are the first in order of time, and that their ten- 

 dency is to disturb the electric equilibrium of the 

 different parts of the apparatus, while the chemi- 

 cal changes operate in restoring this equilibrium. 

 In the farther detail of the hypothesis I shall em- 

 ploy the author's own words. " In the voltaic pile 

 of zinc, copper, and solution of muriate of soda, in 

 what has been called its condition of electrical 

 tension, the communicating plates of copper and 

 zinc are in opposite electrical states. And with 

 regard to electricities of such very low intenMty, 

 water is an insulating body ; every copper plate, 



K 



