THEORY OF GALVANISM. 139 



all metals are naturally in the same state of elec- 

 tricity, and that, by being placed in contact, a 

 portion is attracted from one to the other, the facts 

 would seem to indicate that the reverse takes 

 place : and that although the electricity of each 

 individual metal is in equilibrio with the atmo- 

 sphere, yet that it is unequal with respect to each 

 other ; that zinc, for example, is negative with res- 

 pect to copper. When they are placed in con- 

 tact, their electricity is equalized; but when they 

 are again separated, the zinc, having acquired a 

 portion of electricity from the copper, becomes po- 

 sitive with relation to the atmosphere; and the 

 copper, for the same reason, negative. 



The electric hypothesis of galvanism being, in Relation of 

 some measure, connected with the views which ^chemical 

 have been lately taken by Sir H. Davy, respecting affimt J- 

 the connexion between electricity and chemical 

 affinity, it may be proper to consider the grounds 

 upon which these opinions rest, and also to inquire 

 how far they affect the present question. Hisin- 

 ger and Berzelius seem to have been the first who 

 distinctly pointed out the property which the two 

 extremities of the pile possess of attracting to 

 themselves different kinds of substances ; and Sir 

 H. Davy, by a masterly train of experiments, 

 afterwards showed that this action was so power- 

 ful, as apparently to counteract the usual effects of 

 chemical affinity. Not only was a solution of a 

 neutral salt, in which the two wires terminated, 

 decomposed, and the acid attracted to the positive, 

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