A Manual of the Chemistry of the Carbon Compounds

THE CARBON COMPOUNDS. 103
+ J } 0
It is a colourless mobile liquid, boiling at 126°, and solidifying at
— 13?. It is not explosive, aud not inflammable, but on pouring it
over red-hot charcoal a vivid combustion sets in.
Methine-trisulpiumicAddGRJ. SUgH.-—This acid is formed by
(SOSH
heating calcium methyl-sulphate with a large excess of fuming
sulphuric acid for some time to 100°. To obtain the free acid, the
lead salt is decomposed by hydrogen sulphide; it crystallizes in long
deliquescent needles. It is a powerful tribasic acid, decomposing
nitrates and chlorides, and forming well-crystallized salts, of which
the lead and barium salt are sparingly soluble in water.
Ghtanidine C(NH)(NH3)2.—This powerful base was first obtained
from guanine C6H6N6O, a compound occurring in guano. It is also
formed by heating biuret (see page 67) in a current of dry hydrochloric
acid gas.
Gnanidine is also easily produced by heating cyanogen iodide •with
an alcoholic solution of ammonia:—
ION + 2NHS = C(NH) j JJJJ* + HI
or by the action of alcoholic ammonia upon chloropicrin:—
CC18NO2-+ 4NH8 = C(NH)(NH2)2 + 3HC1 4 N2 + 2HaO
Guanidine combines with acids, forming crystalline salts, of which
the nitrate is only sparingly soluble in water. When a solution
of silver nitrate is added to its solntion the compound CH6N3.AgN03
separates in colourless needles. On adding gold chloride to a mode'rately
concentrated solution of guanidine hydrochloride the double
salt CH.N3 C1H + AuCl3 crystallizes after some timo in beautiful,
deep-yellow, long needles.
To obtain the free base the hydrocliloride or hydriodide is decomposed
with a solution of silver sulphate, and baryta-water is added as
long as a precipitate is formed. On evaporating the filtrate in vacua,
guanidine is left behind in colourless crystals, which are soluble in
water and alcohol; it possesses a strongly alkaline taste, and readily
absorbs carbon dioxide from the air.
FOBMYL COMPOUNDS.
Methyl Aldehyde or Formalddiyde CH2O is a colourless gas,
possessing a pungent and suffocating smell. It is formed by passing
a current of air charged with vapour of methyl alcohol over a coil of