muriatic acid is
electrolyzed or not, although it proves that if so, it must be in definite
proportions to the quantity of electricity used. Other considerations may,
however, be allowed to decide the point. The analogy between chlorine and
oxygen, in their relations to hydrogen, is so strong, as to lead almost to
the certainty, that, when combined with that element, they would perform
similar parts in the process of electro-decomposition. They both unite with
it in single proportional or equivalent quantities; and the number of
proportionals appearing to have an intimate and important relation to the
decomposability of a body (697.), those in muriatic acid, as well as in
water, are the most favourable, or those perhaps even necessary, to
decomposition. In other binary compounds of chlorine also, where nothing
equivocal depending on the simultaneous presence of it and oxygen is
involved, the chlorine is directly eliminated at the _anode_ by the
electric current. Such is the case with the chloride of lead (395.), which
may be justly compared with protoxide of lead (402.), and stands in the
same relation to it as muriatic acid to water. The chlorides of potassium,
sodium, barium, &c., are in the same relation to the protoxides of the same
metals and present the same results under the influence of the electric
current (402.).

764. From all the experiments, combined with these considerations, I
conclude that muriatic acid is decomposed by the direct influence of the
electric current, and that the quantities evolved are, and therefore the
chemical action is, _definite for a definite quantity of electricity_. For
though I have not collected and measured the chlorine, in its separate
state, at the _anode_, there can exist no doubt as to its being
proportional to the hydrogen at the _cathode_; and the results are
therefore sufficient to establish the general law of _constant
electro-chemical action_ in the case of muriatic acid.

765. In the dilute acid (761.), I conclude that a part of the water is
electro-chemically decomposed, giving origin to the oxygen, which appears
mingled with the chlorine at the _anode_. The oxygen _may_ be viewed as a
secondary result; but I incline to believe that it is not so; for, if it
were, it might be expected in largest proportion from the stronger acid,
whereas the reverse is the fact. This consideration, with others, also
leads me to conclude that muriatic acid is more easily decomposed by t