Excitement of Galvanic Electricity. 809 
becomes oxidized, but if of a non-oxidable 
metal, oxygen gas is evolved from it, whilst, 
in both cases, a stream of hydrogen gas pro- 
ceeds from the negative wire. Why, it may 
be asked, do the elements of water, thus dis- 
united, arrange themselves at a distance from 
each other? If the particle of water, which 
has been decomposed, be imagined to have 
been in contact with the extremity of the 
positive wire, the hydrogen must have been 
transmitted in an invisible state to the nega- 
tive wire: But if the decomposed water were 
in contact with the negative pole, then the 
oxygen must have passed imperceptibly to the 
positive wire. 
These appearances have been explained by 
Dr. Bostock on the same hypothesis, by which 
he has accounted for the phenomena of the 
pile. The electric fluid, he imagines, enters 
the water by the positive wire, and is there 
instrumental either in oxidizing the metal or 
in forming oxygen gas. In either case, the 
decomposition of the water must furnish hy- 
drogen, which, uniting with the electric fluid, 
is carried invisibly to the negative pole, the — 
attraction of which for electricity again occa- 
sions the separation of hydrogen, and _ its 
appearance in a gaseous state. This theory, 
however, is liable to some objections, 
