A hard, heavy, ductile metal, found native, and in many ores; of these the most important is _copper pyrites_, which is a sulphuret of copper. Next to gold, silver, and platinum, copper is the most malleable and ductile of metals; it may be drawn into wires as fine as hair, or beaten into leaves as thin as those of silver. The rust of copper is very poisonous. Copper, mixed with a certain quantity of tin, forms bell-metal. With a smaller proportion, it forms bronze, a substance used in sculpture for casting figures and statues. It is an abundant metal, and is found in various parts of the world. Native oxides of copper are found in Cornwall, Siberia, and in North and South America. _Oxide_, a substance combined with Oxygen,[8] in a proportion not sufficient to produce acidity. _Sulphuret_, a combination of sulphur with a base. [Footnote 8: See Chapter XIII., article Oxygen.] What are the uses of Copper? They are too various to be enumerated. In sheets it is much used to sheathe the bottoms of ships, for boilers, and other utensils. Copper coin was the only money used by the Romans till the 485th year of their city, when silver began to be coined. In Sweden, houses are covered with this metal. What is a Mine? A cavity under ground, formed for the purpose of obtaining metals, &c.; mines are often very deep and extensive. The descent into them is by a pit, called a shaft; the clues by which mines are discovered, are, mineral springs, the discoloration of vegetables, the appearance of pieces of ore, &c. _Clues_, signs or means by which things hidden are brought to light. What is Brass? A factitious metal, consisting of copper and zinc. Brass is lighter and harder than pure copper, and less subject to rust; owing to these properties, together with its beautiful color, it is extremely useful in the manufacture of many utensils. _Factitious_, made by art, not found in a natural state. What is Zinc? A metal of a brilliant bluish white color. Its name was unknown to the ancient Greeks and Arabians. It is mixed with other substances in the ore, from which it is obtained by smelting in the furnace. It has never yet been found native or pure. For what is Zinc used? From its readiness to dissolve in all acids, and unite with other metals, it is used in alloy with them in the composition of brass, &c. Thin sheets of zinc are also used to cover roofs of houses, and in the manufacture of various household utensils. What is Lapis Calaminaris? Lapis Calaminaris, or calamine stone, is a native carbonate of zinc, of some use in medicine, but chiefly in founding. It is, sometimes brownish, as that found in Germany and England, or red, as that of France. It is dug out of mines, usually in small pieces; generally out of those of lead. Calamine is mostly found in barren, rocky soils. _Founding_, the art of casting metals. CHAPTER XI.