The manufacture of leaf metal and bronze powder is frequently conducted in the same works, which also often prepare the requisite alloys; we, therefore, give a few examples of the composition of the alloys which produce certain shades. The more zinc the alloys contain the lower is their melting point, the greater their brittleness and hardness and the paler their colour. An increase in the copper causes the colour of the alloy to approach more nearly to that of gold, and increases the malleability, a property useful in making leaf metal, but not desirable in making metallic powder. A zinc copper alloy which contains between 1 and 7 per cent. of zinc has an almost pure red, or even a dark red colour; an alloy containing 7·4 to 13·8 per cent. of zinc has a pure golden yellow colour, between 16·6 and 25 per cent. of zinc a yellow appears. An increase of the percentage of zinc above this point produces the colour of brass; it is noteworthy that an alloy containing still more zinc, 33 to 41 per cent., again shows a reddish colour, which is most developed when the alloy contains equal parts of zinc and copper. If the zinc is increased still further the shade gradually goes over to white; this change is already observed in an alloy containing 51 per cent. of zinc, which shows a pure golden yellow colour, and is very brittle. When the zinc rises to 53 per cent. the colour is reddish white; at 56 per cent. it is yellowish white, at 64 per cent. bluish white, and between 75 and 90 per cent. the alloy is bluish-grey. The alloys for bronze powders of different shades have the following composition, according to R. Wagner:— Copper, Zinc per cent. per cent. Pale yellow 83 17 Red 94-90 6-10 Deep red 100 Bronzes from English, French and Bavarian works contain the following percentages of copper:— ENGLISH BRONZES. Orange 9·82 per cent. Deep yellow 82·37 ” Pale yellow 80·42 ” FRENCH BRONZES. Copper red 97·32 per cent. Orange 94·44 ” Pale yellow 81·29 ” BAVARIAN BRONZES. Copper red 98·92 per cent. Violet 98·82 ” Orange 95·30 ” Straw yellow 81·55 ” Speiss yellow 82·34 ” In each case the remainder of the alloy consists entirely of zinc. Alloys containing from 1 to 35 per cent. of zinc are only malleable in the cold. The malleability is at the greatest with a content of zinc between 15 and 20 per cent.; such alloys are the most suitable for making leaf metal. Alloys containing between 36 and 40 per cent. of zinc may be hammered either cold or hot, whilst the former alloys become brittle on heating. When the percentage of zinc is still further increased the malleability decreases. The most brittle alloys contain 60 to 67 per cent. of zinc.