When chains, etc., are electro-gilt their surfaces are coated with a film of pure gold, which assumes a pale yellow tint when deposited from a new solution, or from a slightly warm one, or by a very low tension current. The colour may be deepened by re-dipping in an old solution or in one heated to 180" F., or under the influence of a 10-volt current. If the chain is made of bronze, copper, or dark brass, or coated with a deep colour gold, the deep colour may be restored by carefully heating it on a sheet of iron over a gas stove, or over a charcoal fire. The chain must be moved about whilst being heated, and removed at once when the colour comes. When cool, it must be polished by brushing with a hard brush.