THEORY OF GALVANISM. 117 



informed ; but we may conclude, that it is not 

 from any chemical operation, because in the letter 

 to Delametherie, written four years after that to 

 Gren, it is expressly said, that the fluids have no 

 effect but in transferring the electricity from one 

 metal to another. 



Upon the whole we may conclude, that Volta General 

 conceives the electricity to be excited by the electric hy- 

 metals producing a degree of electro-motion, or by potl 

 destroying the natural equilibrium of the electri- 

 city ; one metal thus becoming positive and the 

 other negative, they each of them exhibit signs of 

 electricity to an electrometer or other similar in- 

 strument. The only use of the fluid is to tranfer 

 the electricity which is excited by one pair of 

 metals to the next pair ; and although a chemical 

 action may take place between the fluid and the 

 metal, this action is merely incidental, and is not 

 essential to the production of the galvanic effects. 



The objections to Volta's hypothesis are very Objections 

 forcible : in the first place, I am disposed to think to 

 that the fundamental position, on which the whole 

 rests, is objectionable. Volta supposes that two voita's 

 metals, as for example, a plate of zinc and one of [!)" " 

 copper, when placed in extensive contact with each 

 other, may become respectively positive and nega- 

 tive. This he endeavours to prove by direct ex- 

 periment ; but it will be found that in none of the 

 cases is the experiment precisely in point. He 

 adduces some facts, where metals were found re- 

 spectively positive and negative, that had been in 



