Copper.
A metal; one of the elements. Symbol, Cu; atomic weight, 63.5;
equivalent, 63.5 and 31.75; valency, 1 and 2; specific gravity, 8.96.
It is a conductor of electricity, whose conductivity is liable to
vary greatly on account of impurities.
Annealed. Hard drawn.
Relative resistance (Silver = 1), 1.063 1.086
Specific resistance, 1.598 1.634 microhms.
Resistance of a wire at 0° C. (32° F.),
Annealed. Hard Drawn.
(a) 1 foot long, weighing 1 grain, .2041 ohms .2083 ohms.
(b) 1 foot long, 1/1000 inch thick, 9.612 " 9.831 "
(c) 1 meter long, weighing 1 gram, .1424 " .1453 "
(d) 1 meter long, 1 millimeter thick, .02034 " .02081 "
microhm. microhm.
Resistance of 1 inch cube at 0°C. (32° F.) .6292 .6433
Percentage of resistance change,
per 1° C. (1.8° F.) at about 20° C. (68° F.) = 0.388 per cent.
Electro-chemical Equivalent (Hydrogen = .0105) Cuprous .6667
Cupric .3334
In electricity it has been very extensively used as the negative plate
of voltaic batteries. It has its most extensive application as
conductors for all classes of electrical leads.
Copper Bath.
A solution of copper used for depositing the metal in the electroplating
process. For some metals, such as zinc or iron, which decompose copper
sulphate solution, special baths have to be used.
The regular bath for copper plating is the following:
To water acidulated with 8 to 10 percent. of sulphuric acid as much
copper sulphate is added as it will take up at the ordinary temperature.
The saturated bath should have a density of 1.21. It is used cold and is
kept in condition by the use of copper anodes, or fresh crystals may be
added from time to time.
For deposition on zinc, iron, tin and other metals more electropositive
than copper, the following baths may be used, expressed in parts by
weight:
Tin
Iron and Steel. Cast Iron
Cold Hot. and Zinc. Zinc.
Sodium Bisulphate, 500 200 300 100
Potassium Cyanide, 500 700 500 700
Sodium Carbonate, 1000 500 --- ---
Copper Acetate, 475 500 350 450
Aqua Ammoniae, 350 300 200 150
Water, 2500 2500 2500 2500
These are due to Roseleur.