r
will do); a moderate heat may be applied to favor the action. The
mixture should be stirred often with a glass rod; care should be
observed not to apply too much heat, for at a temperature of about 300
deg. the chlorine would be expelled and leave a metallic precipitate,
which would require re-dissolving. Acid may at any time be added if
necessary to dissolve the gold, but it is advisable to add as little
excess as possible, as it would require more time to evaporate. After
all the gold has dissolved, and the liquid assumes a deep red color,
the solution should be allowed to cool, being stirred nearly all the
time. This salt is of a reddish-brown color. It is rarely we find in
our market good chloride of gold, as common, salt is used for the bulk;
and when the bottles are labelled "15 grains," "20 grains," nine-tenths
do not in reality contain exceeding five grains of chloride of gold.
The salt is mixed with the above solution when it is cooling, and gives
bright yellow crystals, which some of our uninformed operators conceive
to be the best quality.

Chloride of Silver.--(Oxide of Silver.)--Take any quantity of silver
coin or other silver, roll or hammer it thin; cut in small pieces.
This in order to save time. Put the silver in a glass or earthen
vessel (Florence flask is best); pour in nitric acid and water, about
three parts of the former to one of the latter. The operation of
cutting up the silver may be facilitated by applying a gentle heat.
This blue solution consists of oxide of silver and oxide of copper,
both combined with nitric acid. Should the operator wish a pure
solution of silver, which, however, is not always used, he may obtain
it in the following manner:

To separate the two metals contained in the above solution from each
other, put some bright copper coins into the solution and set it aside
in a warm place for three or four days, occasionally giving it a
circular motion. The separated laminae are pure silver, which is to be
digested with ammonia until it ceases to be colored blue. The silver,
after being washed and dried, is again dissolved in nitric acid, and
the liquid, diluted with water, is kept as solution, of silver.

Either of the above solutions (the one of oxide of silver and copper,
and the pure silver solution) may be prepared for use by putting them
in a bottle, with a quantity of water, and adding common fine salt, you
obtain a white curdy precipitate of chloride of silver