As substitutes for thin films of the genuine metal, paints resembling gold, silver, bronze, etc., have long been widely employed. These paints are formed by mixing what is known as metallic bronze with a suitable medinm which may be one out of, say, twenty liquids. A few of these are gum water, copal varnish, white spirit varnish, a mixture of turpentine and French polish, and a solution of collodion cotton in amyl acetate diluted with petroleum ether. Most metallic bronze powders are alloys of various metals reduced by pulverising mechanically or by precipitation by chemical agency. To make a very good gold powder, finely grind gold leaf with honey and stir with water to dissolve the latter. Change the water several times, then filter and dry. Another way to treat pure gold or gold leaf to obtain gold bronze powder is to dissolve it in nitro-muriatlc acid, and precipitate it by introducing copper or sulphate of irou. In the former case the precipitate must be digested in distilled vinegar, and washed repeatedly with water. Then it should be dried. Other metals may be treated in a similar way, the desired colour being obtained by the use of basic chromate of lead, oxide of uraninm, autimouiate of lead, borate of copper, oxide of iron, vermilion, or even red ochre.

Mixtures of copper, tin, zinc, and iron in various proportions produce grades of yellow, orange, purple, green, and grey. Pale gold powder is a mixture of 13 1/2 copper and 2 3/4 of zinc. Red tones are produced by adding more copper. Dutch leaf has 20 to 30 per cent, of zinc and from 70 to 75 per cent, ot;opper, and is sometimes ground with real gold to pro'luc" bronze powder. French leaf has more zinc, is harder, and is a purer yellow. Florence leaf has still more zinc. White leaf is principally tin. The fragments from the manufacture of these metals are pounded, then brushed through sieves, ground in gum water on marble slabs for six hours, sorted, and dried. The following is a cheap gold bronze. Grind and make into a paste with oil, verdigris 8 oz., tutti powder (flower of zinc) 4oz.. borax and nitre 2oz. each, corrosive sublimate 2dr. This is fired and, when cold, rolled into leaves, being afterwards ground to powder. To make a copper brouze, plunge a plate of irou into a hot solution of sulphate of copper; the fine scales of copper thrown down are repeatedly washed with water, and mixed with six times their weight of bone dust. A powder having the colour of bronze, which is especially suitable for plaster, etc., can be made as follows.

A mixture of i parts (by measure) of sulphate of copper solution and 1 pari: of sulphate of iron solution is added to a strained solution of soda-soap in linseed oil. The metallic soap, which is precipitated, is washed with cold water, strained, and dried to powder. This is applied in a medinm made by boiling litharge with linseed oil and adding white wax. A very simple way of making gold bronze is to sprinkle powdered tin into very dilute sulphate of copper. This will throw down some finely divided gold coloured bronze. To make a red brouze, add pulverised red ochre or a solution containing chloride of antimony and sulphate of copper - 12 to 20 parts of copper and 1 of tin. Another red bronze is made thus: Heat sulphate of copper 100 parts, with carbonate of soda 00 parts, until it becomes a mass: when cold, powder, add copper filings 15 parts ami again well mix. Maintain at a white heat for twenty minutes, and when cold reduce to an impalpable powder, wash, and dry. For mosaic gold powder, melt equal parts of sulphur and white oxide of tiikin a crucible over a clear fire. Constantly stir with a rod of glass [not iron) till a yellow flaky powder appears.

Another way of making this powder is to use equal parts of sulphur, tin, quicksilver, and sal-ammoniac. Melt the tin in a crucible, and add the quicksilver, and maintain the heat until the mixture is of a gold colour and till no fumes of quicksilver arise. When cold, grind the combination with sulphur and sal-ammoniac. A method of making silver bronze is to melt together 1 oz. each of bismuth and tin. When tin is heated above melting point in contact with the air it becomes a yellowish-white powder, and volatilises at a white heat. Add from loz. to l 1/2oz. of quicksilver, and when cold pulverise the alloy. To make a dark olive-green bronze, add muriatic acid and arsenic to a mixture of orange bronze. To give some idea as to the range of colours in which it is possible to produce bronze powders, it may be mentioned that the Japanese make dark brown powder approaching black by oxidised iron; deep warm brown by different proportions of the same material; light brown by bronze; deep red by copper. They mix iron, gold, and silver, and get a blue by means of steel. Another colour is produced by equal parts of gold dust, vermilion, and charcoal. Plumbago is used to produce a black powder. The colour of the powders is affected by acids.

Freshly bronzed articles are given an antique appearance by rubbing them with a soft rag or brush dipped in a mixture of 3/4oz. of sal-ammoniac and l 1/2 dr. of salts of sorrel dissolved in 1 qt. of vinegar.