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BRONZE
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BRONZE , an alloy formed wholly or chiefly of See also:copper and See also:tin in variable proportions. The word has been etymologically connected with the same See also:root as appears in " See also: Bronze containing about 7 parts of copper to 1 of tin is hard, brittle and sonorous, and can he tempered to take a See also:fine edge. See also:Bell-metal varies considerably in composition, from about .3 to 5 parts of copper to 1 of tin. In See also:speculum metal there are a to 21 parts of copper to 1 of tin. Statuary bronze may contain from 8o to 90 % of copper, the See also:residue being tin, or tin with See also:zinc and See also:lead in various proportions. The bronze used for the See also:British and See also:French copper coinage consists of 95 % copper, 4 % tin and 1 % zinc. Many copper-tin See also:alloys employed for machinery-See also:bearings contain a small See also:pro-portion of zinc, which gives increased hardness. " See also:Anti-See also:friction metals," also used in bearings, are copper-tin alloys in which the amount of copper is small and there is See also:antimony in addition. Of this class an example is " Babbitt's metal," invented by See also:Isaac Babbitt (1799–1862); it originally consisted of 24 parts of tin, 8 parts of antimony and 4 parts of copper, but in later compositions for the same purpose the proportion of tin is often considerably higher. Bronze is improved in quality and strength when fluxed with See also:phosphorus. Alloys prepared in this way, and known as phosphor bronze, may contain only about 1 % of phosphorus in the See also:ingot, reduced to a See also:mere trace after casting, but their value is nevertheless enhanced for purposes in which a hard strong metal is required, as for See also:pump plungers, valves, the bushes of bearings, &c. Bronze again is improved by the presence of See also:manganese in small quantity, and various grades of manganese bronze, in some of which there is little or no tin but a considerable percentage of zinc, are extensively used in See also:mechanical See also:engineering. Alloys of copper with See also:aluminium, though often nearly or completely destitute of tin, are known as aluminium bronze, and are valuable for their strength and the resistance they offer to corrosion. By the addition of a small quantity of See also:silicon the tensile strength of copper is much in-creased; a See also:sample of such silicon bronze, used for See also:telegraph wires, on See also:analysis was found to consist of 99.94 % of copper, 0.03 % of tin, and traces of See also:iron and silicon. The bronze (Gr. xaXKbs, See also:Lat. aes) of classical antiquity consisted chiefly of copper, alloyed with one or more of the metals, zinc, tin, lead and See also:silver, in proportions that varied as times changed, or according to the purposes for which the alloy was required. Among bronze remains the copper is found to vary from 67 to 95 %. From the analysis of coins it appears that for their bronze coins the Greeks adhered to an alloy of copper and tin till 400 B.c., after which See also:time they used also lead with increasing frequency. Silver is rare in their bronze coins. The See also:Romans also used lead as an alloy in their bronze coins, but gradually reduced the quantity, and under Caligula, See also:Nero, See also:Vespasian and See also:Domitian, coined pure copper coins; afterwards they reverted to the mixture of lead. So far the words xaXKbs and aes may be translated as bronze. Originally, no doubt, xaXKbs was the name for pure copper. It is so employed by See also:Homer, who calls it EpvOpbs (red), aiattic& (glittering), 4aevvbs (shining), terms which apply only to copper: But instead of its following from this that the See also:process of alloying copper with other metals was not practised in the time of the poet, or was unknown to him, the contrary would seem to be the See also:case from the passage (Iliad xviii..474) where he describes See also:Hephaestus as throwing into his See also:furnace copper, tin, silver and See also:gold to make the See also:shield of See also:Achilles, so that it is not always possible to know whether when he uses the word xaXKbs he means copper pure or alloyed. Still more difficult is it to make this distinction when we read of the mythical Dactyls of See also:Ida in See also:Crete or the Telchines or See also:Cyclopes being acquainted with the smelting of xaXa6s. It is not, however, likely that later Greek writers, who knew bronzein its true sense, and called it xaXKbs, would have employed this word without qualification for See also:objects which they had seen unless they had meant it to be taken as bronze. When See also:Pausanias (iii. 17. 6) speaks of a statue, one of the See also:oldest figures he had seen of this material, made of See also:separate pieces fastened together with nails, we understand him to mean literally bronze, the more readily since there exist very See also:early figures and utensils of bronze so made. For the use of bronze in See also:art, see METAL-See also:WORK. Additional information and CommentsThere are no comments yet for this article.
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