A N T I M O N Y : ITS HISTORY, CHEMISTRY, MINERALOGY ...
A N T I M O N Y : ITS HISTORY, CHEMISTRY, MINERALOGY ...
A N T I M O N Y : ITS HISTORY, CHEMISTRY, MINERALOGY ...
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tHE ANTIMONY PREPARATIONS AND THEIR USES. 16l<br />
chloride of antimony. They are then dried and melted with a<br />
certain proportion of antimony sulphide and quicklime, in order to<br />
transform the whole into antimony green. The addition of a small<br />
quantity of quicklime is intended for decomposing the small proportion<br />
of chloride of antimony which may still remain in the<br />
residues.<br />
" 2. Preparation of the Hyposulphite of Lime.—This salt is cheaply<br />
prepared by the action of sulphurous acid upon the sulphide or polysulphide<br />
of calcium, or the oxysulphide. The sulphurous acid is<br />
produced by burning brimstone or roasting pyrites or sulphide of<br />
antimony.<br />
"The polysulphide of calcium is prepared by boiling finely ground<br />
sulphur with newly slaked lime and sufficient water. It is advantageous<br />
to add to this solution of polysulphide a certain proportion<br />
of powdered oxysulphide of calcium, which is the residue of the<br />
lixiviation of crude soda. In the absence of oxysulphide, quicklime<br />
may be added.<br />
" Sulphurous acid, in its reaction upon the sulphide and oxysulphide<br />
of calcium, sets sulphur free and forms a sulphite of lime,<br />
which, in the presence of sulphur and undecomposed sulphide, is soon<br />
transformed into hyposulphite of lime. The reaction is aided by<br />
the elevation of temperature which takes place in the apparatus.<br />
" The liquor is examined now and then to see whether it is alkaline,<br />
neutral, or acid. As soon as it has become slightly acid, it is run<br />
from the apparatus into a large settling-tank, where it generally<br />
becomes neutralised by a certain quantity of undecomposed oxysulphide<br />
of calcium held in it. If, after stirring for some time, the<br />
liquor preserves its acid reaction, sulphide of calcium is added until<br />
complete neutralisation is effected, which is ordinarily made apparent<br />
by a black precipitate of sulphide of iron.<br />
"After settling for some time, the clear liquid is decanted, and<br />
forms a solution of nearly pure hyposulphite of lime. The same<br />
vessel is subsequently used for neutralising the liquors obtained<br />
during the process of manufacture.<br />
" 3. Preparation of Vermilion of Antimony.—The red sulphide of<br />
antimony is prepared with the above solutions of chloride of antimony<br />
and of hyposulphite of lime.<br />
" The apparatus consists simply of several wooden tanks, holding<br />
from 20 to 30 hectolitres each, and raised about 1 metre above the<br />
floor. These tanks are so arranged that they may be heated by<br />
steam, passed through a copper or lead pipe, opening about 2 decimetres<br />
from the bottom, or, what is preferable, through a coil of<br />
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