to all bodies (821.), and consider
the _quantities_ as well as the _nature_ of the substances set free, a
generally accurate judgement of the primary or secondary character of the
results may be formed: and this important point, so essential to the theory
of electrolyzation, since it decides what are the particles directly under
the influence of the current, (distinguishing them from such as are not
affected,) and what are the results to be expected, may be established with
such degree of certainty as to remove innumerable ambiguities and doubtful
considerations from this branch of the science.

748. Let us apply these principles to the case of ammonia, and the supposed
determination of nitrogen to one or the other _electrode_ (554. 555,). A
pure strong solution of ammonia is as bad a conductor, and therefore as
little liable to electrolyzation, as pure water; but when sulphate of
ammonia is dissolved in it, the whole becomes a conductor; nitrogen
_almost_ and occasionally _quite_ pure is evolved at the _anode_, and
hydrogen at the _cathode_; the ratio of the volume of the former to that of
the latter varying, but being as 1 to about 3 or 4. This result would seem
at first to imply that the electric current had decomposed ammonia, and
that the nitrogen had been determined towards the positive electrode. But
when the electricity used was measured out by the volta-electrometer (707.
736.), it was found that the hydrogen obtained was exactly in the
proportion which would have been supplied by decomposed water, whilst the
nitrogen had no certain or constant relation whatever. When, upon
multiplying experiments, it was found that, by using a stronger or weaker
solution, or a more or less powerful battery, the gas evolved at the
_anode_ was a mixture of oxygen and nitrogen, varying both in proportion
and absolute quantity, whilst the hydrogen at the _cathode_ remained
constant, no doubt could be entertained that the nitrogen at the _anode_
was a secondary result, depending upon the chemical action of the nascent
oxygen, determined to that surface by the electric current, upon the
ammonia in solution. It was the water, therefore, which was electrolyzed,
not the ammonia. Further, the experiment gives no real indication of the
tendency of the element nitrogen to either one electrode or the other; nor
do I know of any experiment with nitric acid, or other compounds of
nitrogen, which shows the tendency of this element, under the in