at they can travel in any other direction than what will
accord with its course, and therefore can never tend to pass otherwise than
_from_ the anode and _to_ the cathode.

964. In such a circle as that delineated, therefore, all the known _anions_
may be grouped within, and all the _cations_ without. If any number of them
enter as _ions_ into the constitution of _electrolytes_, and, forming one
circuit, are simultaneously subject to one common current, the anions must
move in accordance with each other in one direction, and the cations in the
other. Nay, more than that, equivalent portions of these bodies must so
advance in opposite directions: for the advance of every 32.5 parts of the
zinc _b_ must be accompanied by a motion in the opposite direction of 8
parts of oxygen at _d_, of 36 parts of chlorine at _g_, of 126 parts of
iodine at _l_; and in the same direction by electro-chemical equivalents of
hydrogen, lead, copper and tin, at _e, h, k_. and _m_.

965. If the present paper be accepted as a correct expression of facts, it
will still only prove a confirmation of certain general views put forth by
Sir Humphry Davy in his Bakerian Lecture for 1806[A], and revised and
re-stated by him in another Bakerian Lecture, on electrical and chemical
changes, for the year 1826[B]. His general statement is, that "_chemical
and electrical attractions were produced by the same cause, acting in one
case on particles, in the other on masses, of matter; and that the same
property, under different modifications, was the cause of all the phenomena
exhibited by different voltaic combinations_[C]." This statement I believe
to be true; but in admitting and supporting it, I must guard myself from
being supposed to assent to all that is associated with it in the two
papers referred to, or as admitting the experiments which are there quoted
as decided proofs of the truth of the principle. Had I thought them so,
there would have been no occasion for this investigation. It may be
supposed by some that I ought to go through these papers, distinguishing
what I admit from what I reject, and giving good experimental or
philosophical reasons for the judgment in both cases. But then I should be
equally bound to review, for the same purpose, all that has been written
both for and against the necessity of metallic contact,--for and against
the origin of voltaic electricity in chemical action,--a duty which I may
not undertake in the present paper[D]