BEFORE AND AFTER COMPLETION OF THE VOLTAIC CIRCUIT. 
45 
in the present condition of science, we must not yet abandon Volta’s theory, since it 
may very readily happen, that, at the contact of two bodies, a disengagement of elec- 
tricity may take place, resulting from a commencement of chemical action between 
these bodies.” 
De la Rive*, who has laboured perhaps more than any of the continental philoso- 
phers in advocating the chemical origin of voltaic electricity, cannot but admit some 
such similar qualification, as may be seen from the following extract from one of his 
papers : — “ The two theories between which philosophers are divided with respect to 
the origin of voltaic electricity, are still the subject of lively controversy ; when we 
are adverting to the pile itself and to hydro-electric currents, we cannot deny the 
superiority of the chemical theory ; the recent labours of Faraday have, moreover, 
added powerful arguments in favour of this theory ; but it must be acknowledged 
that it is not easy to defend it when we advert to electricity of tension developed in 
the contact of two heterogeneous bodies, especially if the two bodies are solid.” 
Faraday ~f~, who has recently instituted a series of elaborate researches in support of 
the chemical theory, writes thus of it : — ■“ The theory assumes that, the particles of the 
di-electric (now an electrolyte) are, in the first instance, brought by ordinary induc- 
tion into a polarized state, and raised to a certain degree of tension or intensity before 
discharge commences, the inductive state being in fact a necessary preliminary to 
discharge.” Again, “ One point is, that different electrolytes or di-electrics require 
different initial intensities for their decomposition. This may depend upon the 
degree of polarization which the particles require before electrolytic discharge 
commences^.” 
Grove §, in a recent communication to the Royal Society, in allusion to the action 
of the gas battery, says, “ If, indeed, the contact theory assume contact as the efficient 
cause of voltaic action, but admit that this can only be circulated by chemical action, 
I see little difference, save in the mere hypothetical expression, between the contact 
and chemical theories; any conclusion which would flow from the one would like- 
wise be deducible from the other ; there is no observed sequence of time in the phe- 
nomena, the contact or completion of the circuit and the electrolytical action are 
synchronous. If this be the view of contact theorists, the rival theories are mere 
disputes about terms. If, however, the contact theory connects with the term con- 
tact an idea of force which does or may produce a voltaic current independently of 
chemical action, a force without consumption, I cannot but regard it as inconsist- 
ent with the whole tenor of voltaic facts and general experience.” 
24. I shall have occasion to revert to the gas battery, the action of which is fully 
described in the paper from which I have taken the preceding quotation ; but the 
action we are now examining is not that arising from contact or completion of the 
circuit, but that which is caused by contact in the arrangement of a progressive 
* Archives de l’Electricite, vol. i. p. 619. 
t Ibid. § 1354. 
f Experimental Researches, § 1345. 
§ Philosophical Transactions, 1843. 
