[A] It is just possible that this case may, by more delicate experiment, hereafter disappear. (See now, 1340, 1341, in relation to this note.--_Dec. 1838._) 449. There is no strict electrical distinction of conduction which can, as yet, be drawn between bodies supposed to be elementary, and those known to be compounds. _Royal Institution, April 15, 1833_. FIFTH SERIES. S 11. _On Electro-chemical Decomposition._ P i. _New conditions of Electro-chemical Decomposition._ P ii. _Influence of Water in Electro-chemical Decomposition._ P iii. _Theory of Electro-chemical Decomposition._ Received June 18,--Read June 20, 1833. S 11. _On Electro-chemical Decomposition._[A] [A] Refer to the note after 1047, Series viii.--_Dec. 1838._ 450. I have in a recent series of these Researches (265.) proved (to my own satisfaction, at least,) the identity of electricities derived from different sources, and have especially dwelt upon the proofs of the sameness of those obtained by the use of the common electrical machine and the voltaic battery. 451. The great distinction of the electricities obtained from these two sources is the very high tension to which the small quantity obtained by aid of the machine may be raised, and the enormous quantity (371. 376.) in which that of comparatively low tension, supplied by the voltaic battery, may be procured; but as their actions, whether magnetical, chemical, or of any other nature, are essentially the same (360.), it appeared evident that we might reason from the former as to the manner of action of the latter; and it was, to me, a probable consequence, that the use of electricity of such intensity as that afforded by the machine, would, when applied to effect and elucidate electro-chemical decomposition, show some new conditions of that action, evolve new views of the internal arrangements and changes of the substances under decomposition, and perhaps give efficient powers over matter as yet undecomposed. 452. For the purpose of rendering the bearings of the different parts of this series of researches more distinct, I shall divide it into several heads. P i. _New conditions of Electro-chemical Decomposition._ 453. The tension of machine electricity causes it, however small in quantity, to pass through any length of water, solutions, or other substances classing with these as conductors, as fast as it can be produced, and therefore, in relation to quantity, as fast as it could have passed through much shorter portions of the same conducting substance. With the voltaic battery the case is very different, and the passing current of electricity supplied by it suffers serious diminution in any substance, by considerable extension of its length, but especially in such bodies as those mentioned above.