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METALLURGY op ANTIMONY. In treating certain ores to obtain tho metal, the first 

 object is to separate tho gangue, which was formerly done by filling crucibles with tho 



mixed materials, placing 

 them on the hearth of an 

 oven, and exposing them 

 to a moderate heat. As 

 the sulphide easily melts, 

 it runs out through a hole 

 in the bottom of the cru- 

 cible into a pot placed 

 beneath, and out of tho 

 reach of tho fire. But 

 the great loss from tho 

 breakage of tho crucibles has caused another method to be adopted. In this, the broken 

 ore, being sorted, is laid on the bottom of a concave reverberatory hearth, whore it is 

 reduced. 



Figs. 71 and 72 represent a wind or flame furnace, for the reduction of anti- 

 mony. The hearth is formed of sand and clay solidly beat together, and slopes from 

 all sides towards the middle, where it is connected with the orifice a, which is closed 

 with dense coal-ashes ; b is the air-channel up through the bridge ; c, tho door for 

 introducing the prepared ore, and running off the slags ; d, the bridge; c, tho grate ; 

 /, the fire or fuel-door ; g, the chimney. With 2 or 3 cwts. of ore, the smelting pro- 

 cess is completed in from 8 to 10 hours. The metal thus obtained is not puro 

 enough, but must be fused under coal-dust, in portions of 20 or 30 pounds, in crucibles 

 placed upon a reverberatory hearth. 



At Malboac, in the department of Ardeche, in Franco, the separation of the sulphide 



of antimony from its associated gangue is, or 

 was, effected by means of a peculiar appara- 

 tus (fig. 73). The mineral is placed in large 

 retorts, E E, of which four are set in each 

 furnace. An aperture is left at the bottom 

 of each of these cylinders, which corre- 

 sponds with a similar opening by which they 

 are supported. Beneath these, in the 

 chambers, c c, are placed earthen pots, P i>, 

 in which is received the melted sulphide as 

 it descends through the openings in the 

 cylinders. Tho fuel consumed on the grate 

 consists of fir-wood ; and the sulphide ob- 

 tained is converted into metallic antimony 

 by roasting in a reverberatory furnace, and 

 subsequent reduction by a mixture of 20 

 per cent of powdered charcoal which has 

 been saturated with a strong solution of the 

 carbonate of soda. 



Metallic antimony, as obtained by the 

 preceding process, is the antimony of commerce, but is not absolutely pure ; con- 

 taining frequently minute portions of iron, lead, and even arsenic, the detection 

 and separation of which belong to tho province of analytical chemistry; but 

 considerable purity may be secured by repeatedly fusing tho metal, mixed with a 

 little of its sulphide and some carbonate of soda, in a crucible. From 100 parts of 

 the impure metal in this way 94 of pure antimony are obtained. The addition of 

 sulphide serves the purpose of making fluid compounds of the sulphides of iron, arsenic, 

 and copper, with the soda. Wohler purifies antimony completely from arsenic (not from 

 iron and copper) by deflagrating 10 parts of the crude ore with 12 of nitre and 15 of 

 carbonate of soda ; washing away tho arsenic salt, and then smelting the residuary anti- 

 moniate of potash with black flux. Lead can be separated only by the humid analysis. 

 To obtain antimony free from iron, it should be fused with some antimonic oxide 

 in a crucible, whereby the iron is oxidised and separated. The presence of arsenic 

 in antimony is detected by the garlic smell, emitted by such an alloy when heated at 

 the blowpipe ; or, better, by igniting it with nitre in a crucible ; in which case 

 insoluble antimonite and antimonate of potash will be formed along with soluble 

 arsenate. Water digested upon the mixture, filtered, and then tested with nitrate of 

 silver, will afford the brown-red precipitate characteristic of arsenic acid. 



According to Berthicr, the following materials afford, in smelting, an excellent 

 product of antimony. _ From 100 parts of sulphide, 60 of protoxide of iron from tho 

 shingling or rolling mills (Hammerschlag), 45 to 50 of carbonate of soda, and 10 of 



