A Manual of the Chemistry of the Carbon Compounds

68 THE CHEMISTRY OF
with a concentrated aqueous solution of potassium cyanate. It
crystallizes in white ueedlea, melting at 130°,
Carbonyl Sulphide or Carbon Oxysitlphide COS.—This compound
is formed by passing carbon monoxide and sulphur vapour through a
red-hot porcelain tube. It is, however, best prepared by adding
potassium sulphocyanate to a cold mixture of four parts of water
and five parta of concentrated sulphuric acid, the sulphooyanic acW
which is first set free, taking up water, forms ammonia and carbonyl
sulphide:—
C H } S + H 2° * C0S + NH 3
Carbonyl sulphide is a colourless gas possessing a peculiar resinous
smell, resembling at the same time that of hydrogen sulphide; it is
very inflammable, burning with a blue flame. It is slightly soluble
in water, and appears to occur in some sulphur springs. Caustic
potash absorbs it but slowly, potassium carbonate and sulphide being
formed:—
COS + 4 KOH = K,CO, + K2S + 2H2O
Carbon, Bisulphide CS4 is obtained as a heavy colourless liquid by
passing sulphur vapour over red-hot charcoal. The commercial product
has a very unpleasant odour, due to impurities contained in it;
these may be destroyed by heating the crude sulphide with water in
closed tubes to 100°.
Pure carbon disulphide boils at 43 - 3°, and possesses an ethereal
odour. On evaporating it rapidly, by means of a strong current of
air, so much heat becomes latent that a portion of the sulphide solidifies
to a white mass resembling cauliflowers, and melting again at
— 12°. Carbon disulphide i3 insoluble in water, and has at 0° the
specific gravity l - 0272 ; it is highly inflammable; its vapour, when
mixed with air, takes five at 149'. It is poisonous; the inhalation of
its vapour produces giddiness, congestion, and vomiting. It i3 manufactured
on a large scale, as it is found to be an excellent solvent
for resins, oils, fats, caoutchouc, phosphorus, sulphur, &o. On account
of its inflammability and poisonous properties great care must be taken
in using it.
SuIpJwcarhonic Acid and 8iUphoc