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

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