Silver is a lustrous silvery metal extremely malleable and ductile: symbol Ag (Lat. argentum). Known since prehistoric times, silver occurs native in Peru, but the chief ores are sulpides, from which the metal is extracted by smelting with lead. It is the best metallic conductor of both heat and electricity, and its most important compounds are the chloride and bromide which darken on exposure to light, the basis of photographic emulsions. Silver is used for tableware, Jewellery, coinage, electrical contacts and electro-plating, and as a solder it makes good metallic joints at 720ºC. The world’s greatest producer of silver is Mexico (c. 40,000,000 troy oz. p.a.) followed by the U.S.A., Canada, Peru, the Russia, Australia and Japan.
Aluminium is the most abundant metal, valuable for its light weight, having at. no. 13, at. wt. 26·98, and chemical symbol Al. Nearly one-twelfth of the substance of the earth’s crust is composed of aluminium compounds, but aluminium in its pure state was not readily obtained until the middle of the 19 th century, for it oxidizes rapidly, and much energy is needed to separate the metal from chemical combination. Pure aluminium is a soft white metal. It is one of the lightest of metals, its specific gravity being 2·70, and for this reason is widely used in shipbuilding and aircraft. In the pure state it is a weak metal, but when alloyed with other elements such as cooper, silicon, or magnesium, alloys of great strength are obtained. Commercially, aluminium is obtained from bauxite (q.v) and requires large supplies of electric power, as at Kitimat in Western Canada. Aluminium is much used in steel-cored aluminium overhead cables and for canning uranium slugs for reactors. Aluminium is an essential constituent in the Alcomax series of magnetic materials; and as a good conductor of electricity is used in the form of foil in electrical capacitors. In the U.S.A. the original name suggested by Sir Humphry Davy Aluminum (aloo-) is retained.
Cooper is a chemical element, one of the earliest metals used by man. Chemical symbol Cu; at. no. 29; at. wt. 63·54. It is salmon pink, very malleable and ductile, and used principally on account of its toughness, softness, and pliability, high thermal and electrical conductivity, and resistance to corrosion. When alloyed with tin it forms bronze, a relatively hard metal, the discovery of which opened a new age in human pre-history. Until about a century ago, Spain and Cornwall were the chief producers, but these are now of minor importance compared with the U.S.A. (which produces about a quarter of the world’s output). Chile, Canada, Zambia, and the Katanga area of the Congo. Cooper is usually commercially extracted from cooper pyrites. Large deposits containing cooper sulphide occur in the Lake Superior district in North America, and in Spain. Other ores from which cooper is extracted include malachite, crysocolla, and atacamite.
Gold is a heavy, valuable, yellow metallic element, with symbol Au, atomic number 79, and atomic weight 197·0. Gold has long been valued for its durability, malleability, and ductility, and because it may be easily recognized. It is unaffected by temperature changes and is highly resistant to acids. Its main uses are in coin and jewellery. South Africa produces almost 75 per cent (30,500,000 fine oz. p.a.) of the world’s gold and other major producers are the Russia, Canada, U.S.A., and Australia. For manufacture, gold is alloyed with another strengthening metal, fineness being measured by the parts of pure gold in 24 carat.
Nickel is a lustrous white metal discovered by Cronstedt in 1751, the name being an abbrevation of Swedish kopparnickel (false cooper): symbol Ni, as. wt. 58·71, at. no. 28. It has a high melting point, low electrical and themal conductivity, and can be magnetized. Nickel may be readily forged when hot, and is though, malleable, and ductile when cold. Canada provides the most extensive deposits, which are usually extracted with cooper. Smelting precedes separation, after which the Nickel is purified. It is used in coinage; in chemical and foodstuff industries for its resistance to corrosion; in electronics and for electroplating. The most important use, however, is in alloys with iron, steel, cooper, and chromium, incl. Nickel steel for armourplating and burglar-proof safes, Moneal metal, invar, constantan, nichrome permalloy, perminvar, and other magnetic alloys and stainless steels, cupro-nickel, nickel-silver, and others. Finely divided nickel is used as catalyst in the hydrogenation of vegetable oils.
Aluminium is the most abundant metal, valuable for its light weight, having at. no. 13, at. wt. 26·98, and chemical symbol Al. Nearly one-twelfth of the substance of the earth’s crust is composed of aluminium compounds, but aluminium in its pure state was not readily obtained until the middle of the 19 th century, for it oxidizes rapidly, and much energy is needed to separate the metal from chemical combination. Pure aluminium is a soft white metal. It is one of the lightest of metals, its specific gravity being 2·70, and for this reason is widely used in shipbuilding and aircraft. In the pure state it is a weak metal, but when alloyed with other elements such as cooper, silicon, or magnesium, alloys of great strength are obtained. Commercially, aluminium is obtained from bauxite (q.v) and requires large supplies of electric power, as at Kitimat in Western Canada. Aluminium is much used in steel-cored aluminium overhead cables and for canning uranium slugs for reactors. Aluminium is an essential constituent in the Alcomax series of magnetic materials; and as a good conductor of electricity is used in the form of foil in electrical capacitors. In the U.S.A. the original name suggested by Sir Humphry Davy Aluminum (aloo-) is retained.
Cooper is a chemical element, one of the earliest metals used by man. Chemical symbol Cu; at. no. 29; at. wt. 63·54. It is salmon pink, very malleable and ductile, and used principally on account of its toughness, softness, and pliability, high thermal and electrical conductivity, and resistance to corrosion. When alloyed with tin it forms bronze, a relatively hard metal, the discovery of which opened a new age in human pre-history. Until about a century ago, Spain and Cornwall were the chief producers, but these are now of minor importance compared with the U.S.A. (which produces about a quarter of the world’s output). Chile, Canada, Zambia, and the Katanga area of the Congo. Cooper is usually commercially extracted from cooper pyrites. Large deposits containing cooper sulphide occur in the Lake Superior district in North America, and in Spain. Other ores from which cooper is extracted include malachite, crysocolla, and atacamite.
Gold is a heavy, valuable, yellow metallic element, with symbol Au, atomic number 79, and atomic weight 197·0. Gold has long been valued for its durability, malleability, and ductility, and because it may be easily recognized. It is unaffected by temperature changes and is highly resistant to acids. Its main uses are in coin and jewellery. South Africa produces almost 75 per cent (30,500,000 fine oz. p.a.) of the world’s gold and other major producers are the Russia, Canada, U.S.A., and Australia. For manufacture, gold is alloyed with another strengthening metal, fineness being measured by the parts of pure gold in 24 carat.
Nickel is a lustrous white metal discovered by Cronstedt in 1751, the name being an abbrevation of Swedish kopparnickel (false cooper): symbol Ni, as. wt. 58·71, at. no. 28. It has a high melting point, low electrical and themal conductivity, and can be magnetized. Nickel may be readily forged when hot, and is though, malleable, and ductile when cold. Canada provides the most extensive deposits, which are usually extracted with cooper. Smelting precedes separation, after which the Nickel is purified. It is used in coinage; in chemical and foodstuff industries for its resistance to corrosion; in electronics and for electroplating. The most important use, however, is in alloys with iron, steel, cooper, and chromium, incl. Nickel steel for armourplating and burglar-proof safes, Moneal metal, invar, constantan, nichrome permalloy, perminvar, and other magnetic alloys and stainless steels, cupro-nickel, nickel-silver, and others. Finely divided nickel is used as catalyst in the hydrogenation of vegetable oils.
