fluence of
the electric current, to pass in either direction along its course.

749. As another illustration of secondary results, the effects on a
solution of acetate of potassa, may be quoted. When a very strong solution
was used, more gas was evolved at the _anode_ than at the _cathode_, in the
proportion of 4 to 3 nearly: that from the _anode_ was a mixture of
carbonic oxide and carbonic acid; that from the _cathode_ pure hydrogen.
When a much weaker solution was used, less gas was evolved at the _anode_
than at the _cathode_; and it now contained carburetted hydrogen, as well
as carbonic oxide and carbonic acid. This result of carburetted hydrogen at
the positive electrode has a very anomalous appearance, if considered as an
immediate consequence of the decomposing power of the current. It, however,
as well as the carbonic oxide and acid, is only a _secondary result_; for
it is the water alone which suffers electro-decomposition, and it is the
oxygen eliminated at the _anode_ which, reacting on the acetic acid, in the
midst of which it is evolved, produces those substances that finally appear
there. This is fully proved by experiments with the volta-electrometer
(707.); for then the hydrogen evolved from the acetate at the _cathode_ is
always found to be definite, being exactly proportionate to the electricity
which has passed through the solution, and, in quantity, the same as the
hydrogen evolved in the volta-electrometer itself. The appearance of the
carbon in combination with the hydrogen at the positive electrode, and its
non-appearance at the negative electrode, are in curious contrast with the
results which might have been expected from the law usually accepted
respecting the final places of the elements.

750. If the salt in solution be an acetate of lead, then the results at
both electrodes are secondary, and cannot be used to estimate or express
the amount of electro-chemical action, except by a circuitous process
(843.). In place of oxygen or even the gases already described (749.),
peroxide of lead now appears at the positive, and lead itself at the
negative electrode. When other metallic solutions are used, containing, for
instance, peroxides, as that of copper, combined with this or any other
decomposable acid, still more complicated results will be obtained; which,
viewed as direct results of the electro-chemical action, will, in their
proportions, present nothing but confusion, but will appear perfec