916.  In order to render more distinct the principles which I have been endeavouring to establish, I will restate them in their simplest form, according to my present belief.  The electricity of the voltaic pile (856. note) is not dependent either in its origin or its continuance upon the contact of the metals with each other (880. 915.).  It is entirely due to chemical action (882.), and is proportionate in its intensity to the intensity of the affinities concerned in its production (908.); and in its quantity to the quantity of matter which has been chemically active during its evolution (869.).  This definite production is again one of the strongest proofs that the electricity is of chemical origin.

917.  As volta-electro-generation is a case of mere chemical action, so volta-electro-decomposition is simply a case of the preponderance of one set of chemical affinities more powerful in their nature, over another set which are less powerful:  and if the instance of two opposing sets of such forces (891.) be considered, and their mutual relation and dependence borne in mind, there appears no necessity for using, in respect to such cases, any other term than chemical affinity, (though that of electricity may be very convenient,) or supposing any new agent to be concerned in producing the results; for we may consider that the powers at the two places of action are in direct communion and balanced against each other through the medium of the metals (891.), fig. 76, in a manner analogous to that in which mechanical forces are balanced against each other by the intervention of the lever (1031.).

918.  All the facts show us that that power commonly called chemical affinity, can be communicated to a distance through the metals and certain forms of carbon; that the electric current is only another form of the forces of chemical affinity; that its power is in proportion to the chemical affinities producing it; that when it is deficient in force it may be helped by calling in chemical aid, the want in the former being made up by an equivalent of the latter; that, in other words, the forces termed chemical affinity and electricity are one and the same.

919.  When the circumstances connected with the production of electricity in the ordinary voltaic circuit are examined and compared, it appears that the source of that agent, always meaning the electricity which circulates and completes the current in the voltaic apparatus, and gives that apparatus power and character (947. 996.), exists in the chemical action which takes place directly between the metal and the body with which it combines, and not at all in the subsequent action of the substance so produced with the acid present[A].  Thus, when zinc, platina, and dilute sulphuric acid are used, it is the union of the zinc with the oxygen of the water which determines the current; and though the acid is essential to the removal of the oxide so formed, in order that another