5. Copper, with about one-fourth of its weight of lead, forms _pot-metal_. _Brass_ is an alloy of copper and zinc. The proportion of the latter metal varies from one-eighth to one-fourth. Mixtures, chiefly of these two metals, are also employed to form a variety of gold-colored alloys, among which are _prince's metal_, _pinchbeck_, _tombac_, and _bath-metal_. 6. A series of alloys is formed by a combination of tin and copper. They are all more or less brittle, rigid, and sonorous, according to the relative proportions of the two metals; these qualities increasing with the amount of tin. The principal of these alloys are, _bronze_, employed in the casting of statues; _gun-metal_, of which pieces of artillery are made; _bell-metal_, of which bells are made; and _speculum-metal_, which is used for the mirrors of reflecting telescopes. 7. The alloys of copper were very prevalent among the nations of antiquity, and were used, in many cases where iron would have answered a much better purpose. The instruments of husbandry and of war, as well as those for domestic uses generally, were usually made of bronze, a composition which furnishes the best substitute for iron and steel. The Corinthian brass, so celebrated in antiquity, was a mixture of copper, gold, and silver. 8. The earliest information of the use of this metal by mankind, is found in the fourth chapter of Genesis, in which it is stated, that "Tubal-Cain was the instructer of every artificer in brass and iron." This individual was the seventh generation from Adam, and was born about the year of the world 500. THE COPPERSMITH. 1. Copper, being easily wrought, is applied to many useful purposes. It is formed into sheets by heating it in a furnace, and compressing it between steel rollers. The operation of rolling it constitutes a distinct business, and is performed in mills erected for the express purpose. 2. The rolled sheets are purchased according to weight by the coppersmith, who employs them in sheathing the bottoms of ships, in covering the roofs of houses, and in constructing steam-boilers and stills. He also fabricates them into a variety of household utensils, although the use of this metal in preparing and preserving food, is attended with some danger, on account of the poisonous quality of the verdigris which is produced on the surface. 3. An attempt has been made to obviate this difficulty, by lining the vessels with a thin coating of tin. This answers the purpose fully, so long as the covering of tin remains entire. But, in cases of exposure to heat, it is liable to be melted off, unless it is kept covered with water.