Brassing.
The deposition of a coating of brass by electrolysis. The plating bath
contains both copper and zinc. As anode a plate of brass is used. The
operation must be constantly watched. The deposition of both metals goes
on simultaneously, so that a virtual alloy is deposited. By changing
the depth of immersion of the anode the color of the deposit is varied.
As a formula for a brassing bath the following are typical. They are
expressed in parts by weight.
(a) For iron and steel.
I.
Sodium Bisulphate, 200
Potassium Cyanide, 70 per cent., 500
Sodium Carbonate, 1,000
Water, 8,000
II.
Copper Acetate, 125
Zinc Chloride, 100
Water, 2,000
Add the second solution to the first.
(b) For zinc.
I.
Sodium Bisulphate, 700
Potassium Cyanide, 70 per cent., 1,000
Water, 20,000
II.
Copper Acetate, 350
Zinc Chloride, 350
Aqua Ammoniae, 400
Water, 5,000
Add the second solution to the first.
Use a brass anode; add more zinc to produce a greenish color; more
copper for a red color. A weak current gives a red color; a strong
current lightens the color. The battery power can be altered, a larger
or smaller anode can be used, or a copper or zinc anode can be used to
change the color of the deposit. The bath may vary from 1.036 to 1.100
sp. gr., without harm.
Break.
A point where an electric conductor is cut, broken, or opened by a
switch or other device, or simply by discontinuity of the wires.
Break-down Switch.
A switch used in the three-wire system to provide for the discontinuance
of the running of one of the dynamos.
By connecting the positive and negative bus wires to one terminal of the
active dynamo, and the neutral bus wire to the other terminal, one
dynamo will supply the current and the system operates like a two-wire
system, but can only be used for half its normal capacity.
Breaking Weight.
The weight which, applied in tension, will break a prism or cylinder, as
an electric current conductor.