b. Liquation of Crude Antimony in Crucibles. This method allows a better yield, but the consumption of fuel is greater, and varies according to the manner of firing, and the length of the operation.

Liquation in Crucibles in an Open Fire. This liquation operation is the most expensive with regard to fuel, and may be used where wood is cheap and the ores are rich and do not require a high temperature. Great quantities may then be produced in larger vessels in a short time, and without such injury to the health of the workmen as occurs when operating with closed furnaces. This liquation may be conducted close to the mine, and the cost of transport saved, so as partially to balance the greater consumption of fuel.

This mode of liquation is adopted in several places: we give three examples :

1. At Wolfsberg (Hartz).-The simple apparatus in use here is represented by Fig. 167. a, a, are the side walls FIG. 167.

provided with openings for the admission of air. b, crucible for receiving the ore, several of which stand side by side; they have pierced bottoms. c, lower crucible for receiving the liquated crude antimony. d, ash, sand, &c., to enclose the lower crucible. e, fire-place.

Grey antimony ore, previously dressed by a hand sorting, is treated. The remaining gangue always contains mechanically some sulphide of antimony, particularly when the ore is too rapidly heated. The residues seldom contain less than one-tenth, and sometimes one-fourth of their own weight of sulphide of antimony.

2. At Malbosc*, in the province of Ardèche. Here the crucibles are conical, and pierced at the bottom; they are

DUMAS, Angew. Chem., iv., 146.

0.33 metre high, and o°22 metre wide on the top; 25 or 30 of these crucibles stand in a row between the two side walls, 0*25 metre high, with 0'40 metre distance between them. Each crucible contains about 30 lbs. of raw ore. They are placed upon receiving crucibles sunk into the earth; the space round the upper crucibles is filled with coal, and the coal is ignited by wood shavings. Four smeltings are usually made in 40 hours, by which time the crucibles serving as receivers are filled; when cooled they are broken in such a manner as to admit of being luted and used again; but at least half the upper and lower crucibles is lost by each operation. Twenty crucibles, when charged four times, contain I ton 4 cwts. of ore, and yield in 40 hours 938 lbs. of crude antimony, at a consumption of about 1 tons of coal and 4 cwts. of wood; therefore 100 lbs. of crude antimony require for their production 300 lbs. of coal and 40 lbs. of wood rubbish.

3. At Magurka,* in Lower Hungary, two crucibles, each II inches high and capable of containing 8 or 9 lbs. of antimony, are placed one inside the other, and these again in a third crucible, which is surrounded to half its height by ash, &c. About thirty of these compound crucibles are placed in a row between two side walls with a space of 1 foot between each. This space is filled up with thin pieces of dried fir-wood 2 feet long, and the crucibles are covered with a layer of this wood; the mass of wood is kindled simultaneously by torches. From 4 to 4 tons of crude antimony are produced in 1 hours, consuming about 880 cubic feet of wood when the weather is fair.

Liquation in Vessels Standing in Closed Furnaces.This method is chiefly adapted for poor ores requiring a higher temperature. Two sorts of apparatus are employed.

a. Furnaces allowing Interrupted Operations, having the receivers either inside or outside the furnace.-In either case the liquation vessels must cool after each charge for the residues to be removed.

* Oesterr. Ztschr., 1856, p. 59. Bgwkfd., xix., 190. B. u. h. Ztg., 1861, p. 123.

At Lincouln,* in the department Haute-Loire, 75 conical clay crucibles, each 19 inches high, 11 inches wide at the top, and 9 inches wide at the bottom, are placed in a kind of muffle furnace; each bottom is pierced with 5 holes of inch diameter, and they stand upon crucibles 9 inches high, 10 inches wide at the top, and 8 inches at the bottom, and serving as receivers. Each crucible is charged with 40 lbs. of ore, so that of rich ore is placed on the bottom, upon this

of ore mixed with gangue, and on the top of poor ore. A moderate heat is given for an hour, in order to avoid as much as possible the decrepitation of the pieces of ore; next the heat is increased for three hours, and then kept moderate again for the last two hours, to lessen the loss of metal by volatilisation. The receivers then contain 20 or 24 lbs. of crude antimony, which are removed after the furnace has been allowed to cool for from 20 to 24 hours; I tons of ore consume 15 or 16 cubic feet of birch-wood, yielding about 50 per cent of sulphide of antimony. The waste of crucibles is considerable.

b. Furnace with continuous Operations.-This furnace is constructed so as to allow the removal of the residues after each charge, thus causing a considerable saving of time and fuel, and rendering this method more advantageous than other processes.

FIG. 168.

VOL. I.

R

* KARST., Arch., 1 R. xviii., 158.
2 N

The peculiar furnace used at Malbosc,* in the department of Ardèche, in France, is shown by Fig. 168. The mineral is placed in large retorts (R, R), four of which are set in each furnace. At the bottom of each of these cylinders an aperture is left, corresponding with a similar opening by which they are supported. Beneath these, in the chambers c, c, are placed earthen pots (P, P) into which the melted sulphide descends through the openings in the cylinders. Each cylinder lasts about three weeks, and is charged with 5 cwts. of ore, which are liquated in three hours. The residues are then removed either from the mouth of the cylinders or from an opening which they have on one side, and which is kept closed during the process by means of a clay plug. The liquated sulphide of antimony must flow from the cylinder with a blue flame; a red flame shows that the temperature is too high; 100 lbs. of crude antimony are produced every hour, at a consumption of 64 lbs. of coal; 100 lbs. of ore consume 22 lbs. of coal, the ore yielding 50 per cent of sulphide of antimony.

II. PRODUCTION OF REGULUS OF ANTIMONY

(METALLIC ANTIMONY).

Regulus of antimony was formerly produced from crude antimony, but latterly it has frequently been produced direct from very rich ores. The decomposition of the sulphide is conducted either by combined processes of oxidation and reduction, or by means of iron together with alkaline fluxes. The metal (regulus) resulting from slightly impure ores is usually so impure as to require a calcination for the separation of arsenic, iron, lead, copper, sulphur, &c. The appearance of a star upon the surface of the regulus indicates a certain degree of purity. Rammelsberg says that the star is formed by a great number of rhombohedrons gradually decreasing in size, joined at their edges, and placed in parallel rows, forming three radiated groups from one centre. The alkaline fluxes scorify the earthy and metallic oxides and decompose sulphide of antimony; chloride of sodium

KARST., Arch., i. R. xviii., 158.

transforms foreign metals into chlorides, which then enter the slag; and sulphate of soda being reduced when in contact with coal to sulphide of sodium, forms sulpho-salts, which assist scorification. An addition of iron decomposes sulphide of antimony, but part of it enters the regulus. Upon adding some sulphide of antimony during the calcination of metallic antimony, the foreign metals become sulphuretted, entering the slag with the sulphide of sodium.

Production of Regulus of Antimony from Crude
Antimony.

The decomposition of sulphide of antimony may be effected

1. By Roasting Reduction Processes.-If the roasting is conducted carefully, the sulphide of antimony becomes transformed into sulphurous acid and a yellowish white antimoniate of antimony. This antimoniate forms with sulphide of antimony an easily fusible compound, possessing no constant composition, and not losing any of its sulphur by further roasting. The roasted mass (oxide of antimony, antimoniate of antimony, and oxysulphide of antimony), then requires to be reduced. This is effected by smelting it in a crucible, or on the hearth of a reverberatory furnace, for about an hour, after having mixed it with one-tenth of its own weight of raw tartar, or with I part of coal and a part of carbonate of potash. The yield of metal amounts to 65 per cent; it is poured into iron moulds. previously brushed over with tallow or loam water.

In Upper Hungary* the crude antimony, after being crushed and ground, is completely roasted in a muffle furnace in quantities of 3 cwts., yielding 82 per cent of roasted mass. Five cwts. of this mass are mixed with 10 per cent of small coal and from 3 to 6 per cent of sulphate of soda, and smelted in a French antimony furnace (page 545) for about 20 hours. The slag is then removed from the metal bath, and the socalled star slag (from 20 to 25 lbs. of an admixture of 50 per cent of perfectly roasted crude antimony, 2 per cent of

B. u. h. Ztg., 1862, p. 408.