THEORY OF GALVANISM. 14 



lation to galvanism. As far as respects this parti- 

 cular department of science, it will stand upon the 

 same general grounds with the hypothesis of Da\ r y 

 and Berzelius, although, for the same reason which 

 induced me to prefer the view of the subject 

 which has been taken by the former of these phi- 

 losophers, I conceive that of M. Oersted to be still 

 more objectionable, as by descending into a greater 

 variety of minute details, it becomes more in- 

 volved in difficulties and inconsistencies. 



I have already had occasion to detail the obser- Biot' 

 vations of M. Biot on the two leading theories of nion * 

 galvanism, in which he estimates their respective 

 merits, and appears almost in doubt to which he 

 ought to give the preference ; but in his late 

 learned treatise on naturaj philosophy he decidedly 

 adopts the electric hypothesis. He defines galvan- 

 ism to be electricity by simple contact, and he 

 conceives that electricity is capable of being ex- 

 cited by simple contact in metals and many other 

 substances, and probably indeed in all bodies in 

 nature.* As a proof of this position he refers to 

 Volta's experiment of the zinc and copper disks ; 

 and adapting it to the hypothesis of the two elec- 

 tric fluids, which he assumes in all his specula- 

 tions, he supposes that the zinc acquires the vitre- 

 ous, and the copper the resinous electricity as a 

 consequence of their contact ; and, like Volta, he 

 conceives that this difference in their electric 



* Traite de Physique, ii. 467. 

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