beautified and preserved from rust in this way.

Figure 44 illustrates an electro-plating bath in which a number of
spoons are being plated. A portion of the vat V is cut away to
show the interior, which contains a solution S of the double
cyanide of gold and potassium when gold is to be laid, and the
double cyanide of silver and potassium when silver is to be
deposited. The electrodes are hung from metal rods, the anode A
being a plate of gold or silver G, as the case may be, and the
cathode C the spoons in question. When the current of the battery
or dynamo passes through the bath from the anode to the cathode,
gold or silver is deposited on the spoons, and the bath
recuperates its strength by consuming the gold or silver plate.

Enormous quantities of copper are now deposited in a similar way,
sulphate of copper being the solution and a copper plate the
anode. Large articles of iron, such as the parts of ordnance, are
sometimes copper-plated to preserve them from the action of the
atmosphere. Seamless copper pipes for conveying steam, and wires
of pure copper for conducting electricity, are also deposited, and
it is not unlikely that the kettle of the future will be made by
electrolysis.

Nickel-plating is another extensive branch of the industry, the
white nickel forming a cloak for metals more subject to corrosion.
Nickel is found to deposit best from a solution of the double
sulphate of nickel and ammonia. Aluminium, however, has not yet
been successfully deposited by electricity.

In 1836 De la Rue observed that copper laid in this manner on