120 Faraday's Researches

of a true protochloride consisting of single proportionals (430,

426. Periodide of mercury being examined in the same manner,
was found most distinctly to insulate whilst solid, but conduct
when fluid, according to the law of liquido--conduction (138);
but there was no appearance of decomposition. No iodine
appeared at the anode, nor mercury or other substance at the
cathode. The case is, therefore,, no exception to the rule, that
only compounds of single proportionals are decomposable; but
it is an exception, and I think the only one, to the statement,
that all bodies subject to the law of liquido-conduction are
decomposable. I incline, however, to believe, that a portion of
protiodide of mercury is retained dissolved in the periodide, and
that to its slow decomposition the feeble conducting power is
due. Periodide would be formed, as a secondary result, at the
anode ; and the mercury at the cathode would also form, as a
secondary result, protiodide. Both these bodies would mingle
with the fluid mass, and thus no final separation appear, not-
withstanding the continued decomposition.

427. When per chloride of mercury was subjected to the voltaic
current, it did not conduct in the solid state, but it did conduct
when fluid. I think, also, that in the latter case it was decom-
posed; but there are many interfering circumstances which
require examination before a positive conclusion can be drawn.

428. When the ordinary protoxide of antimony is subjected to
the voltaic current in a fused state, it also is decomposed, although
the effect from other causes soon ceases (138, 536). This oxide
consists of one proportional of antimony and one and a half of
oxygen, and is therefore an exception to the general law assumed.
But in working with this oxide and the chloride, I observed
facts which lead me to doubt whether the compounds usually
called the protoxide and the protochloride do not often contain
other compounds, consisting of single proportions, which are
the true proto compounds, and which, in the case of the oxide,
might give rise to the decomposition above described.

429. The ordinary sulphuret of antimony is considered as
being the compound with the smallest quantity of sulphur, and
analogous in its proportions to the ordinary protoxide. But I
find that if it be fused with metallic antimony, a new sulphuret
is formed, containing much more of the metal than the former,
and separating distinctly, when fused, both from the pure
metal on the one hand, and the ordinary grey sulphuret on the
other. In some rough experiments, the metal thus taken upd other acids.tion at a convenient opportunity.ttmuiE Ofhe surface were