schemes of electro-chemical action might be drawn up, differing
essentially from each other, yet all agreeing with the statement there
given.

483. When Sir Humphry Davy uses more particular expressions, he seems to
refer the decomposing effects to the attractions of the poles. This is the
case in the "general expression of facts" given at pp. 28 and 29 of the
Philosophical Transactions for 1807, also at p. 30. Again at p. 160 of the
Elements of Chemical Philosophy, he speaks of the great attracting powers
of the surfaces of the poles. He mentions the probability of a succession
of decompositions and recompositions throughout the fluid,--agreeing in
that respect with Grotthuss[A]; and supposes that the attractive and
repellent agencies may be communicated from the metallic surfaces
throughout the whole of the menstruum[B], being communicated from _one
particle to another particle of the same kind_[C], and diminishing in
strength from the place of the poles to the middle point, which is
necessarily neutral[D]. In reference to this diminution of power at
increased distances from the poles, he states that in a circuit of ten
inches of water, solution of sulphate of potassa placed four inches from
the positive pole, did not decompose; whereas when only two inches from
that pole, it did render up its elements[E].

[A] Philosophical Transactions, 1807, pp. 29, 30.

[B] Ibid. p. 39.

[C] Ibid. p. 29.

[D] Ibid. p. 42.

[E] Ibid. p. 42.

484. When in 1826 Sir Humphry Davy wrote again on this subject, he stated
that he found nothing to alter in the fundamental theory laid down in the
original communication[A], and uses the terms attraction and repulsion
apparently in the same sense as before[B].

[A] Philosophical Transactions, 1826, p. 383.

[B] Ibid. pp. 389, 407, 115.

485. Messrs. Riffault and Chompre experimented on this subject in 1807.
They came to the conclusion that the voltaic current caused decompositions
throughout its whole course in the humid conductor, not merely as
preliminary to the recompositions spoken of by Grotthuss and Davy, but
producing final separation of the elements in the _course_ of the current,
and elsewhere than at the poles. They considered the _negative_ current as
collecting and carrying the acids, &c. to the _positive_ pole, and the
_positive_ current as doing the same duty with the bases, and collecting
them at the _negative_ pole. They likewise consider the currents