COPPERPLATE COPPER SMELTING 325 Wallaroo mines, on Yorke peninsula, which em- ploy from 2,000 to 3,000 miners, and the Burra- Burra mine, employing about 1,000 hands. The exports from the colony of fine copper and ore from 1862 to 1871 were : YEARS. Fine copper, tons. Ore, tons. YEARS. Fine copper, tuns. Ore, tons. 1862. 1868. 1864. 1866. 1866. 4,294 4,802 6,702 5,010 6,270 6,218 5,823 4,510 16,180 16,870 1867. 1868. 1869. 1870. 1871. 8,036 6,211 4,639 6,471 6,895 10,681 20,854 26,814 20,886 20,127 The value of the copper exports in 1871 was 648,569. In New South Wales in 1872 there were 18 copper mines, with a nominal capi- tal of 831,000, and a subscribed capital of 460,240. The product of 1871 was 667 tons of copper, valued at 44,123; exports, 1,350 tons of raw copper, worth 87,575, and 1,370 tons of ore, worth 14,264. The imports into Great Britain from Victoria from 1867 to 1871 were : 1867. 1868. 1869. 1870. 1871. Ore and regu- lus, tons Value Unwrought and partly wrought cop- per, tons Value 5,477 59,193 768 253,685 8,488 84,630 281 20,160 6.666 64,545 1,085 73,066 8,125 91,613 445 27,700 8,522 37,698 1,202 92,668 Small quantities of copper are also produced in West Australia. There are copper mines in the Taurus, in Persia, India, Cochin China, and Japan. From the last named country considerable quantities are shipped to China and elsewhere in the East, the exports in 1870 from Hiogo and Osaka amounting to 1,290 tons, worth $426,375. Copper is likewise found in Morocco, in South Africa, and on the W. coast of that continent. The imports of ore and regulus into Great Britain from the Cape of Good Hope in 1867 were 5,935 tons, worth 108,534; in 1868, 2,843 tons, worth 62,407; in 1869, 4,628 tons, worth 92,155; in 1870, 6,926 tons, worth 118,155; in 1871, 6,414 tons, worth 143,812. The total pro- duction of the world at different periods has been estimated as follows: in 1830, 25,500 tons; in 1840, 41,000 tons; in 1850, 54,700 tons. Simonin, in his " Underground Life," calculates the yield in 1865 to have been 65,000 tons, worth $500 a ton. COPPERPLATE. See ENGEAVING. COPPER SMELTING. With the exception of the native copper from Lake Superior, and smaller quantities from Peru and Bolivia, nearly all the copper of the world is obtained from sulphuretted or oxidized ores, which re- quire for the separation of the pure metal a long and somewhat costly process. This is effected either in the dry or the wet way ; that is to say, by operations in the furnace, or by processes which allow the copper to be separated in a dissolved form in watery solution, and sub- sequently precipitated therefrom. The term smelting applies more properly to the first pro- cess, but we shall briefly describe both the dry and wet methods. The treatment of the native oxides and carbonates is extremely sim- ple, requiring only their fusion with charcoal and a proper flux in a small blast furnace, by which metallic copper is at once obtained. In the case of the sulphuretted ores, which gen- erally contain more or less iron and other foreign metals, the treatment is much more complicated, and depends upon the fact that the copper has a greater affinity for sulphur than the associated metals ; so that if a double sulphuret of copper and iron be partially oxidized by roasting in the open air, and then melted in a furnace, the iron in an oxidized condition unites with the foreign matters to form a more or less fusible cinder or slag, while the copper, still retaining its sulphur, separates in the shape of a dense brittle mass known as regulus or matt. To facilitate this process, various ores are often mixed together in order to secure greater fusibility, and oxid- ized ores are sometimes mixed with highly sulphuretted ones, by which means the copper of both is got in the form of regulus. In some districts low-grade ores, of perhaps 4 or 5 per cent., are thus converted into a regulus of 30 per cent, or more, which is then shipped to some other place for further treatment. This regulus holds also any gold or silver which may have been in the ore, and hence the copper ores of Colorado, rich in precious metals, are there converted into regulus, which is sent elsewhere for further treatment. The regulus or concentrated copper ore thus obtained, still containing a portion of iron and sulphur, is again roasted and fused with some flux, where- by a richer regulus is obtained ; and this oper- ation is repeated until a nearly pure disulphide of copper results. For the extraction of the copper from this two plans are adopted. The first, still followed in Wales and in most Eu- ropean works, consists in partially roasting the refined regulus, by which a part of the sulphur is removed as sulphurous acid, and the com- bined copper is converted into oxide ; and then causing the latter to react upon the yet unoxid- ized portion, the sulphur of which fixes upon the oxygen of the oxide to form sulphurous acid, while the copper of both is left in the metallic state. The reaction may be thus rep- resented : Cu 2 S + 2Cu 2 O=Cu 8 + SO a . Thesec- ond plan consists in continuing the roasting and oxidation of the purified and pulverized regulus until the whole of the sulphur is ex- pelled. The copper, being then in the condition of oxide or suboxide, is treated directly with charcoal in the same way as the native oxides and carbonates. The latter method, known from its inventor as Napier's, is now generally pursued in Chili, and is said to offer great ad- vantages on the score of economy of fuel and labor over the older system. The copper ob-
