MIKING IN CALIFORNIA AND NEVADA. 29
to it, and in this manner the plates will act nearly as well as in the other case.
These " copper plates "
used for this purpose, and also outside the boxes, are, however,
prepared specially with a view of their intercepting nearly all the
gold that is splashed over their surface, and, as stated already, the
inside plates are from \ inch to J inch thick, whilst outside
1-16 inch thick or ordinary copper plates are used. All these plates
are prepared in the following manner, viz.:—They are well cleaned and
burnished with very coarse sandpaper, after being straitened out; a
coat of good beeswax is then given to the side not cleaned, in order to
confine the process to the one side only. The copper plates so prepared
are then hung in a bath containing a solution of silver of regulated
strength, then they are connected with a battery, and thus
electro-plated with pure or coin silver on one side in such a manner
and with such a quantity of silver, as will not amount to less than one
ounce of silver per square foot; any larger percentage is preferable if
the coating presents as rough as possible a surface. Without
exception, all the superintendents I spoke with declared that no
battery is complete without them. The reason why these silvered copper
plates are held in such high esteem, is simply as follows :—The copper
and silver form, as soon as the quicksilver is added in the usual way
for amalgamation, a powerful galvanic battery, the action of which is
much increased by the slightly aciduous water generated through
crushing pyritous ores passing over these combination plates, and of
course any metal such as gold or silver, already susceptible to
amalgamation, would at once be absorbed by this very particularly
lively mercury.
The
following account for the ingredients used in the solution with a
five-head battery—-less the silver and the battery—sufficed for over
ten months, and gives the articles at Californian 'quotations :—
