MERCURY 



235 



1444 



lime, the cinnabar may be brought into intimate contact with its decomposer, other- 

 wise much of it will be dissipated unproductively in fumes, for it is extremely volatile. 



Figs. 1443, 1444, 1445 represent a cheap and powerful apparatus contrived by Dr. 

 Ure at the request of the German Mines Company of London, and which was mounted 

 at Landsbcrg," near Obermoschel, in the Bavarian Khein-Kreis. 



Fig. 1440 is a section parallel to the 

 front elevation of three arched benches 

 of retorts, of the size above specified. 

 Each bench contains 3 retorts of the form 

 represented by a a a. i is the single 

 fire-place or furnace, capable of giving 

 adequate ignition by coal or wood to the 

 three retorts. The retorts were built up 

 in an excellent manner by a,n English 

 mason perfectly acquainted with the best 

 modes of erecting coal-gas retorts, who 

 was sent over on purpose. 



In the section, fig. 1444, a is the body 

 of the retort; its mouth at the right- 

 hand end is shut, as usual, by a luted iron 

 lid, 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 at 

 L, closed with a screw-plug. Through 

 this hole a wire rammer may be introduced, to ascertain that the tube is pervious 

 and to cleanse it from the mercurial soot, when thought necessary, c is a cross sec- 

 tion of the main condenser, shown in a longitudinal section at c c, fig. 1446. This 



1445 



pipe is 18 inches iu diameter, and about 20 feet long. At a a, &c., the back ends of 

 the retort 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 from sudden ex- 

 pansion or 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 repress every trace of mercurial vapour, and it is laid with a slight 

 inclination from i to h, so that the condensed quicksilver may spontaneously flow 

 along its bottom, and pass through the vertical tube, D, into the locked-up iron chest, 

 or magazine, e. This tube, D, is from the beginning closed at bottom, by immersion 

 in a shallow iron cup, always filled with mercury, k is a graduated gauge-rod, 

 to indicate the progressive accumulation of quicksilver in the chest, without being 

 under the necessity of unlocking it. 



The air-tight apparatus was erected some years ago, and was found to act perfectly 

 well. The whole cost of the nine large retorts, with their condensing-apparatus, iron- 

 magazine, &c., was very little more than two hundred pounds \ As the retorts are 

 kept in a state of nearly uniform ignition, like those of the 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 pitch for decomposing the mercurial ores, they are 

 capable of working off a charge, under skilful management, in the course of 3 hours. 

 Thus, in 24 hours, with a relay of labourers, 8 charges of at least 5 cwts. of ore each 

 might be smelted = 2 tons with 3 retorts, and 6 tons with 9 retorts; with a daily 

 product from the rich ores of Almaden, or even Idria, of from 12 cwts. to 20 cwts. 



