This historic book may have numerous typos and missing text.
Purchasers can usually download a free scanned copy of the original
book (without typos) from the publisher. Not indexed. Not
illustrated. 1902 edition. Excerpt: ...to each gallon of bath will
be sufficient. He has usually noticed that brassing solutions
evolve hydrogen most freely when poor in metal, and when containing
a large excess of cyanide. A solution richer in metal, and
containing but a moderate excess of cyanide, generally yields
better results, both as to colour and general character of the
deposit. A great deal depends, however, upon the amount of current
and its tension, and also upon the temperature of the bath. A
solution rich in copper and zinc is best worked at about 130 Fahr.,
or even higher. When the solution becomes partly exhausted of its
metals, owing to the brass anodes not becoming freely dissolved in
the solution, it. is always advisable to add fresh concentrated
cyanide solutions of the zinc and copper salts from time to time,
taking care, however, only to add them in sufficient quantity to
obtain the desired effect--a coating of good colour with but
trifling evolution of hydrogen at the negative electrode. Bacco's
Solution.--The following solution is said to yield a brass deposit
upon zinc work that will stand burniHhiug, and the deposit may be
obtained either by simple immersion or by the battery. A solution
is first prepared by dissolving equal parts of sulphate of zinc and
sulphate of copper in water. A strong-solution of cyanide of
potassium is then added in sufficient quantity to redissolve the
precipitate formed; to the resulting solution one-tenth to
one-fifth of liquid ammonia is added, and the solution is then
diluted with water until it stands at about 8" Baume. For a
light-coloured deposit of brass 2 parts sulphate of zinc to I part
sulphate of copper are used. In adding cyanide to the solution of
the sulphates, great care must be taken to a%'oid inhaling the...
|Country of origin:
||246 x 189 x 17mm (L x W x T)
||Paperback - Trade
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