"There are other modes of procuring prussic acid, besides the one which has
been so tediously described; but these are found to be more expensive.
The only one which I shall now notice is the process by which it is
obtained from bicyanide of mercury. The bicyanide of mercury itself
is formed when peroxide of mercury is digested with Prussian blue,
the peroxide of mercury abstracting the whole of the cyanogen from
the blue, and leaving the oxides of iron at the bottom of the vessel.
The solution may be evaporated to dryness, and one part of the salt
dissolved in six of water; one part of muriatic acid, sp. gr. 1.15, is
then added, and the solution distilled, when the whole of the hydrocyanic
acid passes over, and by being conducted into a solution of potassa,
as in the former process, forms cyanuret of potassium. This process,
though easier than the first described, is rather given as a resource under
peculiar circumstances than as one to be adopted by the large manufacturer.
The expense is the only objection, but in a small quantity this cannot
be a consideration.

"In giving this very rough outline of the general mode of forming salts,
the minutiae necessary for chemical work have altogether been avoided,
and those parts alone are entered upon which are more immediately
necessary for the electro metallurgist to know and practice for himself.
This will account for the long description of the cyanuret of potassium,
while the preparation of the equally important and even more used acids,
the sulphuric, muriatic, etc., commonly found in commerce,
are altogether neglected.

"In using solutions of cyanide of potassium, the workman should not immerse
his arms into them, otherwise it occasionally happens that the solution
produces very troublesome eruptions over the skin."