should recoil at the deadly potion, and
shrink from the loathsome draught we are about to take. That which we
consider the most delicious and exhilarating portion of our common
beverage, porter, contains carbonic acid gas, commonly known by the
"spirit," and which the poor miners dread with the utmost horror, like
the Arabian does the destructive blast of the simoon. Oxalic acid, so
much the fear of those accustomed to the medicine--Epsom salts, is made
from that useful article, _sugar_, by uniting with it a smaller portion,
more than it has naturally, of oxygen gas. The air we breathe contains a
most deadly poison, called by chemists azotic gas, which, by its being
mixed with what is called vital air, (oxygen gas,) becomes necessary to
our existence, as much as the one (vital air or oxygen gas) would be
prejudicial without the other; and _Prussic acid_, the most violent of
all poisons, is contained in the common bitter-almond. But these most
destructive substances are always found combined with others, which
render them often perfectly harmless, and can be separated only by the
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 h