Melt 1 lb. tin in a crucible, and ½ lb. of purified quicksilver to it; when this is cold, it is reduced to powder, and ground, with ½ lb. sal-ammoniac and 7 oz. flour of sulphur, till the whole is thoroughly mixed. They are then calcined in a matrass; and the sublimation of the other ingredients leaves the tin converted into the mosaic gold powder which is found at the bottom of the glass. Remove any black or discolored particles. The sal-ammoniac used must be very white and clear, and the mercury of the utmost purity. When a deeper red is required, grind a very small quantity of red lead with the above materials.

True Gold Powder

Put some gold-leaf, with a little honey, or thick gum-water made with gum arabic, into an earthen mortar, and pound the mixture till the gold is reduced to very small particles; then wash out the honey or gum repeatedly with warm water, and the gold in powder will be left behind. When dry, it is fit for Use.

Dutch Gold Powder is made from Dutch gold-leaf, which is sold in books at a very low price Treat in the manner described above for true gold powder. When this inferior powder is used, cover the gilding with a coat of clear varnish, otherwise it will soon lose its bright appearance.

Copper Powder is prepared by dissolving filing or slips of coppier with nitrous acid in a receiver. When the acid is saturated, he slips are to be removed; or, if filings be employed, the solution is to be poured off from what remains undissolved. Small bars are then put in, which will precipitate the copper powder from the saturated acid: and, the liquid being ponied from the powder, this is to be washed clean of the crystals by repeated waters.

General Directions For Bronzing

The choice of the above powders is, of course, determined by the degree of brilliancy you wish to obtain. The powder is mixed with strong gum-water or isinglass, and laid on with a brush or pencil; and, when not so dry as to have still a certain clamminess, a piece of soft leather wrapped round the finger is dipped in the powder, and rubbed over the work. When the work has been all covered with the bronze, it must be left to dry, and any loose powder then cleared away by a hair-pencil.

The Bronzing of Plaster Casts is effected by giving them a coat of oil or size varnish, and when this is nearly dry applying with a dabber of cotton or a camel hair-pencil any of the metallic bronze powders; or the powder may be placed in a little bag of muslin, and dusted over the surface, and afterwards finished with a wad of linen. The surface must be afterwards varnished.

Bronzing Iron

The subject should be heated to a greater de-greee than the hand can bear, and German gold, mixed with a small quantity of spirit-of-wine varnish, spread over it with the pencil; should the iron be already polished, you must heat it well, and moisten it with a linen rag dipped in vinegar.