or at least of the nitrogen, previously united to the
acid; and this effect takes place _most extensively_ with large plates,
because the gas evolved at them is in the most favourable condition for
solution,

720. With the intention of avoiding this solubility of the gases as much as
possible, I arranged the decomposing plates in a vertical position (707.
708.), that the bubbles might quickly escape upwards, and that the downward
currents in the fluid should not meet ascending currents of gas. This
precaution I found to assist greatly in producing constant results, and
especially in experiments to be hereafter referred to, in which other
liquids than dilute sulphuric acid, as for instance solution of potash,
were used.

721. The irregularities in the indications of the measurer proposed,
arising from the solubility just referred to, are but small, and may be
very nearly corrected by comparing the results of two or three experiments.
They may also be almost entirely avoided by selecting that solution which
is found to favour them in the least degree (728.); and still further by
collecting the hydrogen only, and using that as the indicating gas; for
being much less soluble than oxygen, being evolved with twice the rapidity
and in larger bubbles (717.), it can be collected more perfectly and in
greater purity.

722. From the foregoing and many other experiments, it results that
_variation in the size of the electrodes causes no variation in the
chemical action of a given quantity of electricity upon water_.

723. The next point in regard to which the principle of constant
electro-chemical action was tested, was _variation of intensity_. In the
first place, the preceding experiments were repeated, using batteries of an
_equal_ number of plates, _strongly_ and _weakly_ charged; but the results
were alike. They were then repeated, using batteries sometimes containing
forty, and at other times only five pairs of plates; but the results were
still the same. _Variations therefore in the intensity_, caused by
difference in the strength of charge, or in the number of alternations
used, _produced no difference as to the equal action of large and small
electrodes_.

724. Still these results did not prove that variation in the intensity of
the current was not accompanied by a corresponding variation in the
electro-chemical effects, since the actions at _all_ the surfaces might
have increased or diminished together. The deficienc