404 
needle than the most powerful intensities of common electri- 
city; showing, as it was suggested, that in the latter case the 
agent was electricity, which, being evolved by chemical ac- 
tion, contained much of the deflecting constituent element ; 
and that in the former the agent was electricity, with its natu- 
ral minimum of the deflecting constituent, because it was de- 
veloped without chemical action, by mere friction ; and hence 
the necessity of the presence of such electricity in considera- 
ble abundance to produce the required effect. 
The same thing was stated to be evidenced by an experi- 
ment, in which two voltaic apparatuses were made to act sepa- 
rately on a differential gold-leaf electrometer, one of them pro- 
ducing divergence, the other none; yet the effect of the latter 
on the galvanometer needle was powerful, that of the former null. 
Professor Faraday’s repetition of Colladon’s experiments 
on deflection by common electricity were then reviewed, and 
the remarkable circumstance was adverted to, that one of his 
deflections was produced by one pole, contrarily to the laws 
of voltaic electricity, in which the operation of two poles is 
indispensable. If it be admitted as proved, that common elec- 
tricity does not require a twofold polar arrangement in order 
to produce deflections, it becomes a question, what is the use 
of the two poles used in Colladon’s and Faraday’s experiments 
with the Leyden battery ? One of them must be superfluous. 
If this be so, we arrive at this general proposition, that voltaic 
electricity is composed of elements existing in such ratio, and 
so combined and modified, that it must be brought to bear 
upon the subject of its action by means of two poles simulta- 
neously and equally energetic; while the proportions and mode 
of combination in the common electric fluid are such, that it 
produces the same effect with one pole only. Thus a diffe- 
rence, instead of an identity, would be proved by these expe- 
riments. 
It was further observed, on Faraday’s deflection of the gal- 
vanometer needle by common electricity, that no less than 
