The ferrotype and how to make it - The Grian Press

SILVER. 71
The different salts of silver are obtained from
the ores or from the metal itself. The
NITRATE OF SILVER
is obtained by dissolving the pure metallic silver
in nitric acid, and is that salt of silver npon
which all the processes of photography are
founded, and beside which there is no metallic or
other element by which primary photographic
impressions can be made, although there are other
substances which are sen*»itive to light. There
are many processes for obtaining the pure nitrate
of silver from the ore or from the metal, from
among which the following is selected :
Pure nitric acid and water of equal parts
should be placed in an evaporating dish over a
gentle heat ; when warm, add the silver. This
part of the process should be carried on out of
doors, or where the draft of a chimney may cause
the fumes which arise to be carried off or bo dis-
sipated. After the silver is dissolved, the solu-
tion should be evaporated to dryness by a slow
heat, less than will produce fusion of the salt.
When the salt is dry, it should be dissolved in
the least quantity of hot water; the solution
should then be set aside to crystallize.
The crystallized nitrate may be purified by re-
dissolving in pure water and allowing it to re-
crystallize.
Nitrate of silver thus obtained is a dry salt
composed of oxide of silver and anhydrous nitric