The various saline compounds of this metal, as the acetate, sulphate,
and nitrate, are all highly poisonous, but they do not appear to us to
merit a separate consideration; and more especially as we have already
explained the various processes by which every variety of preparation
may be identified. We may just remark that the _sulphuret_, better known
by the name of _cinnabar_, or _vermilion_, has been known to occasion
deleterious effects. _Dr. Gordon Smith_[294] states, upon the authority
of _Mr. Accum_,[295] that “Vermilion has been detected as a poisonous
ingredient in cheese:” this may be very true, but he should have stated
at the same time, that the deleterious effects produced by it, did not
arise from the mercurial sulphuret, but from the red lead with which it
happened to be adulterated; and it is necessary to acquaint the forensic
chemist, that such a fraud[296] is by no means uncommon; it may be very
easily detected by burning a small portion of the suspected sample on a
piece of bread in the candle, when metallic globules will announce the
presence of lead; for the oxide of mercury, although revived by the
process, will at the same time be volatilized. The bread by combustion
affords the carbon by which the metallic reduction is effected.
The presence of very minute quantities of _vermilion_ may, according to
_Mr. Smithson_, be detected by the following simple experiment. Boil a
portion with sulphuric acid in a platina spoon, and lay the sulphate
thus produced in a drop of muriatic acid, on a piece of gold, and then
bring a piece of metallic tin in contact with both, when the white
mercurial stain will be produced.