GILDIN'G.

1/3

Method of gilding silver, brass, or copper, ly means of an alloyof gold and mercury.

Eight parts of mercury and one of gold, are alloyed togetherby heating them in a crucible. As soon as the gold is perfectlyalloyed, the mixture is poured into cold water, and is then readyfor use.

Before the alloy can be laid upon the surface of the metal, thislast is brushed over with diluted nitric acid, in which it is of ad-vantage that some mercury may have been dissolved. Some ar-tists then wash the metal in simple water, and scour it a littlewith the finest sand, previous to the application of the gold; butothers apply it to the metal while still wet with the nitric acid.But in either case, the alloy must be laid Son as uniformly aspossible, and spread very even with a brass wire-brush, wettedfrom time to time with water. The piece is then laid upon agrate, over a charcoal fire, or in a small oven, or furnace,adapted to this purpose ; the heat drives off the mercury, andleaves the gold behind. Its defects are then seen, and may beremedied bv successive applications of more amalgam, and ad-ditional application of heat. Expert artists however make theseadditional applications while the piece remains in the furnace,though the practice is said to be highly noxious, on account ofthe mercurial fumes. After this it is rubbed with gilders wax,which may consist of four ounces of bees wax, one ounce ofacetite of copper, and one ounce of sulphate of copper; theythen expose it to a red heat, wdiich burns off the wax; andlastly, the work is cleansed with the scratch brush, and burnish-ed, if necessary, with a steel tool. The use of the wax seemsto consist merely in covering defects, by the diffusion of a quan-tity of red oxid of copper, which is left behind after the burning.

Painting with gold upon porcelain, or glass

Is done with the powder of gold wdiicli remains behind afterdriving off the nitro-muriatic acid from a solution of that metal,