A Manual of the Chemistry of the Carbon Compounds

THE CARBON COMPOUNDS. 135
surrounded by warm water afc about 50°. Alcohol and different
products are condensed and flow back, whilst the vapour of the
aldehyde, after having passed through a descending condenser, is absorbed
in anhydrous ether. On passing dry ammonia gas into the
ethereal solution, a white crystalline solid, called aldehyde-ammonia,
CJI4O.NH3 separates. On distilling this substance with dilute sulphuric
acid, pure aldehyde is obtained, which may be dried over calcium
chloride. Acetaldehyde is a colourless liquid, boiling at 21°,
and haying a very pungent and suffocating smell. It is readily
solnble in water; caustic potash transforms it into a brown resinous
mass, like all aldehydes it is very easily oxidized, and acts therefore
as a powerful reducing agent. Thus, on heating it with a little
ammonia and nitrate of silver, metallic silver separates out, coating
the 8ides of the vessel with a bright mirror:—
C2H4O + AgaO = C2H4O2 + Ag8
It combines with ammonia, and forms a crystalline compound,
which has a peculiar smell of mice. The constitution of aldehydeammonia
is the following:—
H^—CH3
OH
By dilute acids it is decomposed, aldehyde being liberated and an
ammonium salt formed. When kept in the moist state it undergoes
a slow decomposition, and is changed into a brown syrupy liquid,
which contains a basic oompound called aldehydine or hydracetamide
C 1 6Hl2Wg :—
afCAQNH,) = C,,HMN +- NHS + 3H2O
Aldehydine is an amorphous mass, soluble in water, and possessing
an alkaline reaction. It combines with acids, forming amorphous
salts. On boiling its aqueous solution ammonia escapes, and a new
base, oxytrialdine CaHuN0, is obtained, which possesses properties
very similar to those of aldehydine.
If aldehyde-ammonia is heated with alcohol, the bases oxytetrdldins
Hj-NO and oxi/pentcMine C,0H16NO are obtained.
Aldehyde combines with the acid sulphites of the alkali-metals,
and forms crystalline compounds, which are not very soluble ia
water; thus if aldehyde is shaken with a cold concentrated solution
of acid sodium sulphite, the liquid is converted into a magma of
( OH
crystals having the formula CHS.CH | gQ Na- Dilute acids or
alkalis again liberate aldehyde from these compounds.
With anhydrous praasie acid, aldehyde forms the compound