g at 184 deg. C. On exposure to air it absorbs
oxygen and resinifies, becoming deep brown in colour; it ignites
readily, burning with a large smoky flame. It possesses a somewhat
pleasant vinous odour and a burning aromatic taste; it is a highly
acrid poison.

[v.02 p.0048]

Aniline is a weak base and forms salts with the mineral acids. Aniline
hydrochloride forms large colourless tables, which become greenish
on exposure; it is the "aniline salt" of commerce. The sulphate forms
beautiful white plates. Although aniline is but feebly basic, it
precipitates zinc, aluminium and ferric salts, and on warming expels
ammonia from its salts. Aniline combines directly with alkyl iodides
to form secondary and tertiary amines; boiled with carbon disulphide
it gives sulphocarbanilide (diphenyl thio-urea), CS(NHC_{6}H_{5})_{2},
which may be decomposed into phenyl mustard-oil, C_{6}H_{5}CNS, and
triphenyl guanidine, C_{6}H_{5}N: C(NHC_{6}H_{5})_{2}. Sulphuric acid
at 180 deg. gives sulphanilic acid, NH2.C_{6}H_{4}.SO_{3}H. Anilides, compounds
in which the amino group is substituted by an acid radical, are
prepared by heating aniline with certain acids; antifebrin or
acetanilide is thus obtained from acetic acid and aniline. The
oxidation of aniline has been carefully investigated. In alkaline
solution azobenzene results, while arsenic acid produces the
violet-colouring matter violaniline. Chromic acid converts it into
quinone, while chlorates, in the presence of certain metallic salts
(especially of vanadium), give aniline black. Hydrochloric acid and
potassium chlorate give chloranil. Potassium permanganate in neutral
solution oxidizes it to nitrobenzene, in alkaline solution to
azobenzene, ammonia and oxalic acid, in acid solution to aniline
black. Hypochlorous acid gives para-amino phenol and para-amino
diphenylamine (E. Bamberger, _Ber._, 1898, 31, p. 1522).

The great commercial value of aniline is due to the readiness with
which it yields, directly or indirectly, valuable dyestuffs. The
discovery of mauve in 1858 by Sir W.H. Perkin was the first of
a series of dyestuffs which are now to be numbered by hundreds.
Reference should be made to the articles DYEING, FUCHSINE, SAFRANINE,
INDULINES, for more details on this subject. In addition to dyestuffs,
it is a starting-product for the manufacture of many drugs, such
as antipyrine, antifebrin, &c. Aniline is manufactured by reducing
nitrobenzene with iron and hydrochloric acid