Defective colored gilding may also be Improved by the help Of the following mixture: Nitrate of potash, 3 oz.; alum, 1½ oz.; sulphate of zine, 1½ oz.; common salt, 1½ oz. These ingredients are to be put into a small quantity of water to form a sort of paste, which is put upon the articles to be colored; they are then placed upon an iron plate over a clear fire, so that they will attain nearly to a black heat, when they are suddenly plunged into cold wafer; this gives them a beautiful high color. Different hues may be had by a variation in the mixture.

Gold is taken from the surface of silver by spreading over it a paste made of powdered sal-ammoniac, with aqua fortis, and heating it till the matter smokes, and it is nearly dry; when the gold may be separated by rubbing it with a scratch brush.