he
electric current than water; since, even when diluted with eight or nine
times its quantity of the latter fluid, it alone gives way, the water
remaining unaffected.

766. _Chlorides._--On using solutions of chlorides in water,--for instance,
the chlorides of sodium or calcium,--there was evolution of chlorine only
at the positive electrode, and of hydrogen, with the oxide of the base, as
soda or lime, at the negative electrode. The process of decomposition may
be viewed as proceeding in two or three ways, all terminating in the same
results. Perhaps the simplest is to consider the chloride as the substance
electrolyzed, its chlorine being determined to and evolved at the _anode_,
and its metal passing to the _cathode_, where, finding no more chlorine, it
acts upon the water, producing hydrogen and an oxide as secondary results.
As the discussion would detain me from more important matter, and is not of
immediate consequence, I shall defer it for the present. It is, however, of
_great consequence_ to state, that, on using the volta-electrometer, the
hydrogen in both cases was definite; and if the results do not prove the
definite decomposition of chlorides, (which shall be proved
elsewhere,--789. 794. 814.,) they are not in the slightest degree opposed
to such a conclusion, and do support the _general law_.

767. _Hydriodic acid._--A solution of hydriodic acid was affected exactly
in the same manner as muriatic acid. When strong, hydrogen was evolved at
the negative electrode, in definite proportion to the quantity of
electricity which had passed, i.e. in the same proportion as was evolved by
the same current from water; and iodine without any oxygen was evolved at
the positive electrode. But when diluted, small quantities of oxygen
appeared with the iodine at the _anode_, the proportion of hydrogen at the
_cathode_ remaining undisturbed.

768. I believe the decomposition of the hydriodic acid in this case to be
direct, for the reasons already given respecting muriatic acid (763. 764.).

769. _Iodides._--A solution of iodide of potassium being subjected to the
voltaic current, iodine appeared at the positive electrode (without any
oxygen), and hydrogen with free alkali at the negative electrode. The same
observations as to the mode of decomposition are applicable here as were
made in relation to the chlorides when in solution (766.).

770. _Hydro-fluoric acid and fluorides._--Solution of hydrofluoric acid did
not