128 Experimental Philosophy. [Lecture 9- 



In point of theory, galvanism is as much 

 afloat as either magnetism or common electricity. 

 Three different theories of the galvanic battery 

 have been proposed. 1 . That the galvanic pile is 

 entirely electrical. 2. That it is altogether che- 

 mical 3. That electricity produces the phaeno- 

 mena, but is, itself, evolved by chemical action. 

 The first of these theories was advanced by 

 Volta; the second by Donovan; the third by 

 Wollaston, and defended by Dr. Bostock. 



It has been ascertained by unequivocal expe- 

 riments that the galvanic pile never acts unless 

 when one of the metals which compose it has 

 been oxydized ; and that its energy only conti- 

 nues as long as the oxydizing process goes on : 

 hence Volta's theory is evidently imperfect. 



The most cursory attention to the galvanic 

 pile will suffice to demonstrate that it never acts 

 except the circle be completed ; that is, unless 

 there be a current of electricity : and this seems 

 to set aside Donovan's theory. Whence it would 

 seem to follow, that both chemical decomposi- 

 tions and a current of electricity are necessary to 

 constitute the galvanic pile. They who wish 

 farther to investigate this curious subject may 

 advantageously consult Dr. Bostock's History of 

 Galvanism. 



