A Manual of the Chemistry of the Carbon Compounds

00 THE CHEMISTRY OF
cyanate with dilute sulphuric acid, but a part of the acid easily
undergoes a change by taking water up and forming ammonia and
carbon oxysulphide COS, a decomposition analogous to the formation
of ammonia and carbon dioxide from cyanic acid. By adding
ferric chloride to a solution of snlphocyanic ncid or a sulphocyanate
the liquid assumes a deep blood-red colour. This very characteristic
reaction is caused by the formation oifcrrie sulpluxyanidc ^ -*'* [ So,
a salt which may be obtained in small blackish red crystals on evaporating
a solution of ferric hydroxide in sulphocyanic acid.
Gyanogcn Sulphide Q-M- J- S, is formed by heating a mixture of
eyanogen iodide and silver sulphocyanate :—
CN) can,, n canl}
+ Ag} S -Ag| + CN} S -
It sublimes in transparent rhombic plates, which smell like
cyanogen iodide, and readily dissolve in water, alcohol, and ether. By
caustic potash it is decomposed thus:—
+2|O= JS+ JO +
I&omtyiliocyaHxtes.—When persulphocyanio acid is treated wi
alcoholic solution of potash, it yields potassium isosnlphocyana
which is obtained by slow evaporation from an aqueous solution in
hard crystals having the composition CSNK + H2O. This body may
be easily.'distinguished from potassium snlphocyanate by adding to its
aqueous solution a drop of ferric chloride, a brown coloration being
produced, which disappears agnin on adding more of the ferric salts.
When the isosulphocyanate is heated, it melts and undergoes a molecular
change, being transformed into the common sulphocyanate.
The free isoswlphocyanic acid has not yet been obtained, but we are
acquainted with a series of ethers of this acid, of which the best
known is oil of mustard or allyl isosnlphocyanate, having the con-
stitutioa N
f
•<
CS
PV , from which it follows that iaosulphocyanio acid is
sulplwcarhimich (CS N j TT .
AMIDES OF CYANOGEN.
csn
Cyanamidc H > N.—On passing gaseons cyanic acid into a solu-
H I
tion of ammonia in ether, ammonium chloride separates out, and the
solution yields oa evaporation cyanamidc in colourless crystals, which
melt at 40° and are readily soluble in water. On adding nitric acid
to its aqueous solution it is converted into carbamide:—