[A] Annales de Chimie, tom, xxviii. tom. li. p. 73.

492.  It is more than probable that many other views of electro-chemical decomposition may have been published, and perhaps amongst them some which, differing from those above, might, even in my own opinion, were I acquainted with them, obviate the necessity for the publication of my views.  If such be the case, I have to regret my ignorance of them, and apologize to the authors.

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493.  That electro-chemical decomposition does not depend upon any direct attraction and repulsion of the poles (meaning thereby the metallic terminations either of the voltaic battery, or ordinary electrical machine arrangements (312.),) upon the elements in contact with or near to them, appeared very evident from the experiments made in air (462, 465, &c.), when the substances evolved did not collect about any poles, but, in obedience to the direction of the current, were evolved, and I would say ejected, at the extremities of the decomposing substance.  But notwithstanding the extreme dissimilarity in the character of air and metals, and the almost total difference existing between them as to their mode of conducting electricity, and becoming charged with it, it might perhaps still be contended, although quite hypothetically, that the bounding portions of air were now the surfaces or places of attraction, as the metals had been supposed to be before.  In illustration of this and other points, I endeavoured to devise an arrangement by which I could decompose a body against a surface of water, as well as against air or metal, and succeeded in doing so unexceptionably in the following manner.  As the experiment for very natural reasons requires many precautions, to be successful, and will be referred to hereafter in illustration of the views I shall venture to give, I must describe it minutely.

494.  A glass basin (fig. 52.), four inches in diameter and four inches deep, had a division of mica a, fixed across the upper part so as to descend one inch and a half below the edge, and be perfectly water-tight at the sides:  a plate of platina b, three inches wide, was put into the basin on one side of the division a, and retained there by a glass block below, so that any gas produced by it in a future stage of the experiment should not ascend beyond the mica, and cause currents in the liquid on that side.  A strong solution of sulphate of magnesia was carefully poured without splashing into the basin, until it rose a little above the lower edge of the mica division a, great care being taken that the glass or mica on the unoccupied or c side of the division in the figure, should not be moistened by agitation of the solution above the level to which it rose.  A thin piece of clean cork, well-wetted in distilled water, was then carefully and lightly placed on the solution at the c side, and distilled water poured gently on to it until