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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158 THE METALLURGY OF ANTIMONY,<br />
tion in the arts, I have examined its preparation from beginning to<br />
end, and I have therefore aimed at producing hyposulphite of soda<br />
and the chloride of antimony on a manufacturing scale. In regard<br />
to the hyposulphite of soda, and in order to avoid crystallisations,<br />
which require a special apparatus, I followed a process which gave<br />
me this salt in a state of sufficient purity, at a time when its preparation<br />
was but little understood. The process was based upon the<br />
employment of the sulphide of soda.<br />
" In my researches I have demonstrated that this salt should be<br />
employed in the natural state, in order to avoid the reaction of the<br />
sulphurous acid upon the hyposulphite resulting in the Langlois salt,<br />
which, being also decomposed, becomes sulphate of soda. In the<br />
preparation of the sulphite I have followed the process of M. Camille<br />
Koechlin, which consists in burning sulphur in a convenient apparatus.<br />
It consists of a sieve holding large crystals of soda, suspended in a<br />
cask open at the top. The bottom is connected by means of a pipe<br />
with a small clay furnace, upon which the sulphide is thrown in<br />
small quantities at a time.<br />
"The combustion of the sulphur is regulated by means of a trapdoor<br />
; the draught is good, and after two or three days the crystals of<br />
soda are transformed. Should there be portions unacted upon, the<br />
easily crumbling sulphite is rubbed off, and the core of carbona/fce is<br />
replaced in the cask. A solution of 25° Be. strength is made from<br />
the sulphite, and is afterwards heated and saturated with crystals of<br />
soda. When the addition of this salt ceases to produce an effervescence<br />
(litmus paper does not give sufficient indications), or rather,<br />
when a diluted sample of the liquor produces a slight disengagement<br />
of carbonic acid by the addition of hydrochloric acid, then sublimed<br />
sulphur is put in, and the mixture is heated for three hours upon<br />
a water-bath. During that time the evaporated water is replaced<br />
and the mass is frequently stirred. The cold liquor is diluted with<br />
water until the strength is 25° Be.<br />
" The protochloride of antimony is easily prepared by boiling in<br />
hydrochloric acid the powdered native sulphide of antimony. When<br />
the disengagement of hydrosulphuric acid begins to be slow, the<br />
whole is boiled for a few minutes. After cooling, the clear liquid is<br />
decanted.<br />
" In order to obviate the inconvenience of the production of sulphuretted<br />
hydrogen, the gas is collected in a solution of soda, or it is<br />
burned at the end of a glass tube connected with the vessel where<br />
the reaction takes place. If a burning alcohol lamp be placed at the<br />
end of the tube, the combustion of the gas will not be arrested, even