A N T I M O N Y : ITS HISTORY, CHEMISTRY, MINERALOGY ...

TIIK METALLURGY OK ANTIMONY. 131
sulphide) removes sulphur by fusion, and converts arsenic intoarseniatc
of soda or potash. Tho conversion of copper and iron into their
sulphides by sulphide of antimony can be facilitated by the addition of
soda or potash, or of (Glauber salt and charcoal. Those sulphides form
a slag with the sulphide of sodium produced from tho reduction of the
(Jlaubor salt, and with the soda or potash present. These sulphides
are easily removed by antimony glass.
The use of common salt, carnallito, or magnesium chloride to
volatilise some of the forQign metals present as chlorides, and to slap;
others, may also occasion great loss of metal duo to volatilisation.
As lead can easily be separated from its oxido or sulphide by
motallic antimony, tho above-mentioned methods are ineffective for
its elimination. It can, howevor, only partially be eliminated by
chloridising, which, as previously hinted, causes groat loss due to
volatilisation. Mitscherlich suggestod that tho elimination of lead
should be effected before tho smelting of antimony sulphide by
the addition of 4 per cent, of iron, which removes all the lead and a
comparatively small amount of antimony.
in commerce, the purity of antimony regains is judged by the
appearance of the fern-liko "star" on its surface.
If the metal is impure, or if tho pure metal has been oxposod
during solidification, or if the slag covering sets before tho motal does,
or if a trace of undocomposod slag or potash comes into contact with
tho surfaco, the characteristic fern-liko structure is not exhibited.
1. Refining in Pot Furnaces.—This kind of furnace is, or has
been, in nso at Sopttanos in Franco, in England, and at Oakland in
California. The fuel consumption is groat, and therefore it is
advisable to uso it for small quantities only.
At ttoptumes tho furnaco held thirty orueiblos, tho shape of tho
furnaco being that of a barrel cut lengthwise through tho middle.
Its dimensions were :—
Length 7 foot.
Breadth across each end , . . . . . . 4 ,,
Breadth in the middle . . . . . • . 6 ,,
The bod wan 6 inches luwur than tliu bridge.
The height of tho roofabovo tho bridgn . . . . 8 inches.
,, „ ,, tho middle of tho bed . . 1 foot 6 inches.
,, ,, ,, tho cud whero tho IIuo loft tho
furnace . . . .10 inches.
Length of ftrojvhice 5 foot.
Breadth ,, , 1 foot 8 inchoH,
Dopth ,, ,, from roof to burn. . . . . 1 ,, 4 ,,
Width of working door in tho longer iront Hide . . . 1 ,, 8 ,,