skill of the chemist.

The Prussic acid (by some called hydrocyanic acid) is a liquid,
extracted from vegetables, and contains one part of cyanogen and one
part of hydrogen. It is extracted from the bitter-almond, (as has been
stated,) peach-blossom, and the leaves of the laurocerasus. It may also
be obtained from animal substances, although a vegetable acid. If lime
be added to water, distilled from these substances, a Prussiate of lime
is formed; when, if an acid solution of iron be added to this mixture,
common Prussian blue (or Prussiate of iron) is precipitated. The acid
may be obtained from Prussiate of potash, by making a strong solution of
this salt, and then adding as much tartaric acid as will precipitate the
potash, when the acid will be left in solution, which must be decanted
and distilled.

Its properties are a pungent odour, very much resembling that of
bitter-almonds, with a hot but sweetish taste, and extremely volatile.
It contains azote, with which no other vegetable acid is combined; it is
largely used in the manufacture of Prussian blue. It is the most violent
of all poisons, and destroys animals by being applied to the skin only.
It is stated by an able chemist, that a single drop applied to the
tongue of a mastiff dog caused death so instantaneously, that it
appeared to have been destroyed by lightning. One drop to the human
frame destroys life in two minutes.

But when chemically combined with other substances, its power is in a
great measure neutralized, and it becomes a valuable article, both to
the chemist as a test, and to the physician as a medicine. The Prussiate
of potash and iron will enable the chemist to discover nearly the whole
of the metals when in solution, by the colours its combination produces.