[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 as more powerful the nearer they are to their respective poles, and state that the positive current is superior in power to the negative current[A].

  [A] Annales de Chimie, 1807, tom. lxiii. p. 83, &c.

486.  M. Biot is very cautious in expressing an opinion as to the cause of the separation of the elements of a compound body[A].  But as far as the effects can be understood, he refers them to the opposite electrical states of the portions of the decomposing substance in the neighbourhood of the two poles.  The fluid is most positive at the positive pole; that state gradually diminishes to the middle distance, where the fluid is neutral or not electrical; but from thence to the negative pole it becomes more and more negative[B].  When a particle of salt is decomposed at the negative pole, the acid particle is considered as acquiring a negative electrical state from the pole, stronger than that of the surrounding undecomposed particles, and is therefore repelled from amongst them, and from out of that portion of the liquid towards the positive pole, towards which also it is drawn by the attraction of the pole itself and the particles of positive undecomposed fluid around it[C].

  [A] Precis Elementaire de Physique, 3me edition, 1824, tom. i. p. 641.

  [B] Ibid. p. 637.

  [C] Ibid. pp. 641, 642.

487.  M. Biot does not appear to admit the successive decompositions and recompositions spoken of by Grotthuss, Davy, &c. &c.; but seems to consider the substance whilst in transit as combined with, or rather attached to, the electricity for the time[A], and though it communicates this electricity to the surrounding undecomposed matter with which it is in contact, yet it retains during the transit a little superiority with respect to that kind which it first received from the pole, and is, by virtue of that difference, carried forward through the fluid to the opposite pole[B].