Excitement of Galvanic Electricity. 305 
plates. In these respects, it is certainly more 
adequate to account for the phenomena. It 
is chiefly objectionable, in as much as the 
data, on which it is founded, are altogether 
gratuitous. For what other evidence have 
we, than those very phenomena of the pile, 
which the theory is brought to explain, that 
electricity ts evolved by the oxidation of me- 
tals, or that hydrogen is capable of forming, 
with the electric fluid, a combination so little 
energetic, as to be destroyed by the mere 
approach of a conducting body? The theory 
is imperfect, also, in taking no account of 
that. change in the relative quantity of 
electricity in two metallic plates, which, 
according to the observations of Bennett and 
Volta; must necessarily happen when their 
surfaces are put in apposition. 
The discoveries of Mr. Davy, respecting 
the chemical agencies of the electric fluid, 
have:led him to a theory of the Galvanic pile, 
intended to reconcile, in some degree, the 
hypothesis of Volta with that of the philoso- 
phers of our own country. It is admitted, by 
this acute reasoner, that the action of the men- 
struum, contained in the cells, is absolutely 
essential to the activity of Galvanic arrange- 
ments; and that .the two circumstances even 
bear a proportion to each other. Notwith- 
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