sulphuric acid, it is capable of combining with the oxygen
evolved there, and consequently unites with it, producing both carbonic
acid and carbonic oxide in abundance.

561. A great advantage is frequently supplied, by the opportunity afforded
amongst the metals of selecting a substance for the pole, which shall or
shall not be acted upon by the elements to be evolved. The consequent use
of platina is notorious. In the decomposition of sulphuret of silver and
other sulphurets, a positive silver pole is superior to a platina one,
because in the former case the sulphur evolved there combines with the
silver, and the decomposition of the original sulphuret is rendered
evident; whereas in the latter case it is dissipated, and the assurance of
its separation at the pole not easily obtained.

562. The effects which take place when a succession of conducting
decomposable and undecomposable substances are placed in the electric
circuit, as, for instance, of wires and solutions, or of air and solutions
(465, 469.), are explained in the simplest possible manner by the
theoretical view I have given. In consequence of the reaction of the
constituents of each portion of decomposable matter, affected as they are
by the supervention of the electric current (524.), portions of the
proximate or ultimate elements proceed in the direction of the current as
far as they find matter of a contrary kind capable of effecting their
transfer, and being equally affected by them; and where they cease to find
such matter, they are evolved in their free state, i.e. upon the surfaces
of metal or air bounding the extent of decomposable matter in the direction
of the current.

563. Having thus given my theory of the mode in which electro-chemical
decomposition is effected, I will refrain for the present from entering
upon the numerous general considerations which it suggests, wishing first
to submit it to the test of publication and discussion.

_Royal Institution,
June 1833._

SIXTH SERIES.

S 12. _On the power of Metals and other Solids to induce the Combination
of Gaseous Bodies._

Received November 30, 1833,--Read January 11, 1834.

564. The conclusion at which I have arrived in the present communication
may seem to render the whole of it unfit to form part of a series of
researches in electricity; since, remarkable as the phenomena are, the
power which produces them is not to be considered as of an electric origin,
otherwise th