oot. The articles to be silvered are
scratch-brushed, washed, and electroplated, till they begin to look
undesirably rough. They are then taken out of the bath, rebrushed,
and the process continued till a sufficiency of silver is deposited.
Four grammes weight of silver (nearly) is deposited per ampere hour.
It is best to use a fine silver anode, so that the solution, does not
get contaminated by copper.

In most factories it is usual to "quicken" the objects to be silvered
before placing them in the electrolysis vats, because the deposit is
said to adhere better in consequence of this treatment. I have never
found it any improvement for laboratory purposes, but it is easy to
do. A dilute (say 2 per cent) solution of cyanide of mercury is
required containing a little free cyanide. The objects to be
"quickened" are scratch-brushed and dipped into the cyanide of mercury
solution till they are uniformly white; it is generally agreed that
the less the mercury deposited the better, so long as a perfect
coating is obtained. The objects are rinsed after quickening, and put
in the depositing bath at once.

The mat surface of silver obtained by electrolysis of the cyanide is
very beautiful--one of the most beautiful things in nature--shining
with incomparable crystalline whiteness. So delicate is it, however,
for so great is the surface it exposes, that it is generally rapidly
deteriorated by exposure to the air. It may be protected to some
extent by lacquering with pale lacquer, but it loses some of its
brilliancy and purity in the process. The deposit is generally
scratch-brushed or burnished down to a regular reflecting surface.

Sec. 133. Cold Silvering.

A thin but brilliant coat of silver may be readily applied to small
articles of brass or copper in the following way. A saturated
solution of sodium sulphite (neutral) is prepared, and into this a 10
per cent solution of nitrate of silver is poured so long as the
precipitate formed is redissolved. A good deal of silver may be got
into solution in this way. Articles to be silvered need only to be
cleaned, brushed, and dipped in this solution till a coat of the
required thickness is obtained.

I must admit, however, that the coating thus laid on does not appear
to be so permanent as one deposited by simple immersion from the
cyanide solution, even though it is thicker. The cyanide plating
solution will itself give a good coat of silver if it is used boili