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ARTIFICIAL i)i':.\TrRKS ; i:lkctk()-I)EI'Osit. 107

itcd ( 1' ii^'. 62 represents this form of battery). The cu]) is
then nearly filled with eight parts of a saturated snlution of
bichromate of jjolash to one part of sul])huric acid, when the
arrangement is complete.

DEPOSITION OF GOLD.
Since for the deposition of gold it is necessary that the
metal be brought to the state of solution, we will first con-
sider the method of preparing the salt commonly known as
the clilorid of gold, but which, strictly speaking, is the ter-
chlorid, as it contains three equivalents of chlorin.
Preparation of Gold Chlorid.—The most convenient way
to dissolve gold is to place the desired quantity in an
evaporating- dish and add to it a sufficient amount of aqua
rcgia (2 parts hydrochloric acid and i part nitric acid) to
dissolve it. To dissolve i ounce of gold (troy weight)
about 4 ounces of aqua regia is required.
The chemical action which takes place may be acceler-
ated by placing the dish upon a moderately heated sand-
bath. Heat should then be gently applied to drive off the
acid, until the mass assumes a dark-red color and just
ceases to flow about the vessel, at which moment it should
be set aside and allowed to cool.*
The red mass, or the gold chlorid, is next dissolved in
distilled water, which will assume a clear, brownish-yellow
color. If after the chlorid is deposited a white deposit
remains in the bottom of the dish, it is the chlorid of silver,
resulting from a trace of that metal having been present in
the gold.
* If too much heat is applied when the solution has acquired the dark-
red color, it will quickly become reduced to the metallic state. It would
then become necessary, after dissolving out the chlorid with distilled
water, to test it with aqua regia, which will redissolve it.