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DELICATE OPERATIONS.
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and
as much as possible of the superfluous quicksilver is pressed out of it
through, wash-leather; the remaining quicksilver being expelled by
heat from the retorts in which the amalgam is placed.
The
sulphurets which have been retained in the concentrates are often
submitted to a process called chlorination. The principle of this is
the alleged property possessed by chlorine gas of changing gold into a
chloride. This process consists in first roasting the sulphurets, to
drive off the sulphur, etc., and then, when cool, damping it. It is now
placed in an air-tight vessel of peculiar construction, into which the
chlorine gas is admitted beneath the pulpy mass to be chlorinized. An
escape hole is left at the top of this receptacle, so that, as the gas
rises, the common air is expelled, until the vessel is full of chlorine
gas, when the hole is stopped, and the contents left undisturbed for
twenty-four hours. The next process is to extract the chloride of gold
by the introduction of water ; and the precious fluid is then drawn off
with care into a precipitating vat, where, by the addition of a
solution of sulphate of iron, the gold is precipitated, and afterwards
easily collected, dried, and melted in a crucible.
All
this will sufficiently show that skill and care are necessary to render
gold-mining and extraction a success. In proportion as the reduction
staff know their business, and attend to it with constant diligence, so
will results be satisfactory, or other-
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