Illustrations of the Extraction of Mercury in Furnaces with continuous Operations. A. New Method used in the Palatinate.*-In 1847, a new distillation apparatus, represented by Figs. 161, 162, and 163, was introduced into Landsberg by Dr. Ure. Fig. 161 is a section, parallel to the front elevation, of three arched benches of retorts, with an area of at least I square foot, and 7 feet in length. Each bench contains three retorts, whose shape is shown by a, a, a; 1, is the single fire-place or furnace, capable of giving adequate heat to the three FIG. 161. FIG. 162. * URE's Dictionary of Arts, iii., 72. θα retorts, by coal or wood. In the section (Fig. 162) a is the body of the retort; its mouth is at the right hand, and is shut by a luted iron, secured with a cross bar and screw bolts; its other end is prolonged by a sloping pipe of cast-iron 4 inches in diameter, furnished with a nozzle hole (1), closed by a screw plug. A wire rod may be introduced through this hole to ascertain that the tube is pervious, and to cleanse it from the mercurial soot when necessary. e is a cross section of the main condenser, shown in a longitudinal section at c, c (Fig. 163). This pipe is 18 inches in diameter, and about 20 feet long. At a, a, &c., the back ends of the retorts are seen with the slanting tubes b, b, &c., descending through orifices in the upper surface of the condenser pipe, and dipping their ends just below the water line (h, i); g is the cap of a water valve which removes all risk of danger from sudden expansion and condensation. The condenser is placed within a rectangular trough, made either of wood or stone, through which a sufficient stream of water passes to keep it perfectly cool, and condense every trace of mercurial vapour. It has a slight inclination from i to h, so that the condensed mercury may spontaneously flow along the bottom, and pass through the vertical tube (D) into the locked iron chest or magazine (e). This tube (D) is from the beginning closed at the bottom by immersion in a shallow iron cup always filled with mercury; k is a graduated guage rod to indicate the progressive accumulation of mercury in the chest. As the retorts are kept in a state of nearly uniform ignition, like those of gas works, neither they nor the furnaces are liable to be injured in their joints by the alternate contractions and expansions which they would inevitably suffer if allowed to cool; and being always ready heated to the proper degree for decomposing the mercurial ores, they are capable of working off, under skilful management, a charge in 3 hours; thus, in 24 hours, with a relay of labourers, 8 charges of at least 5 cwts. each might be smelted, equal to 2 tons with three retorts, and 6 tons with nine retorts. The ore treated in this furnace should be ground to a moderately fine powder, so that when mixed with quick lime the cinnabar may be brought into intimate contact with it. B. Method at New Almaden and New Idria* in California. -According to Bealey, the cinnabar ores contain 400 lbs. of ores of the size of a nut, and mixed so as to contain 40 per cent of mercury, are mixed with 600 lbs. of pulverised quick lime, and heated in iron retorts at a moderate red heat for from 21 to 32 hours, according to the quality of the fuel (wood). The mercurial fume condenses in a vertical conical receiver, which is kept cool by dropping water upon it. The resulting mercury is tapped off by a pipe. 100 lbs. of ore, containing 40 per cent of mercury, consume an equal quantity of good air-dried wood; 100 lbs. of ore, containing 1 per cent of mercury, require 50 lbs. of wood. Some establishments use vertical retorts, each 8 feet long. One of these retorts treats 125 lbs. of ore, mixed with quick lime, in 4 hours. The volatilised mercury collects in receivers under water. The rotating retorts, 3 feet long and 2 feet wide, at Enriqueta mine, treat the same quantity of ore (125 lbs.) in 2 hours. * B. u. h. Ztg., 1851, p. 769; 1857, p. 377,; 1861, p. 316; 1862, p. 227. Bgwkfd., xvi., 144. Berggeist, 1856, p. 219; 1858, p. 165; 1862, pp. 337, 342. In 1861, the production of mercury throughout the world amounted to 3,050 tons; of these were produced CHAPTER VII. BISMUTH. PRINCIPAL ORES OF BISMUTH. THE principal ore, and almost the only source of the metal used in the arts, is Native Bismuth, sometimes associated with Bismuth Glance, Bi2O,; bismuth ochre occurs in smaller quantities. These ores are generally associated with nickel and cobalt ores. Bismuth is also found in certain smelting products, such as cobalt speiss for the manufacture of smalt, and speiss and matt obtained from smelting argentiferous cobalt and nickel ores. A certain amount of bismuth is sometimes concentrated in the intermediate products resulting from smelting lead, copper, and silver ores,* when it cannot be detected in the ores themselves. Synopsis of Processes for the Extraction of Bismuth from its Ores. Bismuth may be extracted from its ores— 1. By a Liquation Process, which is the one most commonly employed. This process consists of heating the ores to 249° C., at which temperature the bismuth will melt and run out of the earthy and metallic associates; in this manner bismuth is sometimes obtained as a by-product when purifying cobalt and nickel ores. The methods of liquation adopted in the different smelting works differ chiefly * B. u. h. Ztg., 1854, p. 112; 1859, pp. 67, 287, 420. Bgwkfd., iii., 289. |