THEORY OF GALVANISM. 143 



The opinion which is entertained by Dr. Young Young's 

 on this much agitated question, whether the pri- opin 

 mary effect of the pile be chemical or electrical, 

 although not given in a very decided manner, is, 

 I apprehend, favourable to the hypothesis which I 

 have endeavoured to defend, at least so far as re- 

 lates to the connexion between the two operations. 

 He observes, that the phenomena of galvanism are 

 piincipally derived from an inequality in the dis- 

 tribution of the electric fluid, but that it originates 

 from chemical changes. He supposes that this 

 inequality is continued in consequence of the re- 

 sistance which the electric fluid experiences to its 

 motion depending upon the alteration of sub- 

 stances of different kinds, which is conceived to 

 afford a greater resistance to its transmission than 

 would have arisen from any one of the substances 

 singly. He does not venture to determine in 

 what degree the different conducting powers of 

 the elements of the pile contribute to its action ; 

 but he conjectures that the oxidation of metals 

 may produce positive electricity, and that, on the 

 contrary, negative electricity is produced by their 

 combination with sulphur, and that these electric 

 states, when generated, may be communicated to 

 the best conductors that are contiguous to them.* 



In tracing the progress of opinions, it is neces- 



sary to notice the abstruse speculations of Pro- ypot 

 fessor Berzelius, which are indeed not essentially 



* Lectures on Nat. Phil. i. 674. 



