138 THIO-ACIDS AND SALTS.- Sodium Thioantlmonate, Na 3 SbS 4 • 9 H 2 O.
Sodium thioantimonate, or "Schlippe's salt," is formed by the interaction
of antimony sulphide, sodium sulphide, and sulphur; sodium thioantimonite
may first be formed in the dry way (Schlippe), or the whole process may be
carried out in the wet way (Mitscherlich). According to Schlippe's method,
sodium sulphate is heated together with charcoal and antimony trisulphide
in the furnace; sodium sulphide is formed by reduction, and this immediately
combines with the antimony sulphide. By suspending the pulverized fusion
in water and boiling it with powdered sulphur, the sodium thioantimonite is
converted into thioantimonate.
In recrystallizing the salt, it is necessary to add a little sodium hydroxide
to prevent hydrolysis, for otherwise the free thioantimonic acid which would
form would decompose into antimony sulphide and hydrogen sulphide.
Sodium thioantimonate is used in making the medicinal preparation of anti-
mony pentasulphide. - Mix thoroughly 36 g. of powdered stibnite (34 g. = 0.1 mol.),
43 g. of anhydrous sodium sulphate, and 16 g. of powdered charcoal.
Place the mixture in a Hessian crucible, which should be about half
filled, cover with a layer of charcoal, and heat in a charcoal furnace
until the charge comes to a state of quiet fusion, and then heat ten
minutes longer. Pour the melt upon an iron plate, pulverize the
mass when cold, and boil it half an hour with 7 g. of flowers of
sulphur and 300 c.c. of water. Add a little caustic soda solution
and evaporate the filtrate to crystallization in a porcelain dish.
Collect the crystals, wash them with a little alcohol, and work
up the mother-liquor further. Recrystallize the combined por-
tions, adding a little caustic soda to the solution; dry the product
in a vacuum desiccator over lime, upon which a few drops of
ammonium sulphide have been poured. The yield is 40 to 50 g.
of light-yellow well-formed crystals.- Slake 26 g. of quicklime with hot water, stir it up to a paste
with an additional 80 c.c. of water, and add a solution of 70 g.
crystallized sodium carbonate in 250 c.c. of water. Bring the
mixture to boiling in an iron dish, and while it is boiling add little
by little a paste made from 36 g. of powdered stibnite, 7 g. of pow-
dered sulphur, and 12 g. of water. When, after boiling about
15 minutes, the gray color of the antimony sulphide has disap-
peared, filter the solution through linen cloth and extract the
residue by boiling it with 100 to 150 c.c. of water. Bring the