requires a very high temperature to ignite it, and cannot, under
ordinary circumstances, when unconfined, be exploded by the application of
heat. It is little affected by immersion in water, unless prolonged, when
the chlorate dissolves out, leaving a practical inexplosive residue.[A] It
was found to be very sensitive to combined friction and percussion, and to
be readily ignited by a glancing blow of wood upon wood. It was also
deficient in chemical stability, and has been known to ignite
spontaneously both in the laboratory and in a magazine. It is an orange-
coloured plastic mass, and smells of nitro-benzol.

[Footnote A: Col. Cundill, R.A., "Dict. of Explosives," says: "If,
however, it be exposed to moist and dry air alternately, the chlorate
crystallises out on the surfaces, and renders the explosive very
sensitive."]

~Tonite No. 3~ contains 10 to 14 per cent. of nitro-benzol (see Tonite).
Trench's Flameless Explosive contains 10 per cent. of di-nitro-benzol,
together with 85 per cent. of nitrate of ammonia, and 5 per cent. of a
mixture of alum, and the chlorides of sodium and ammonia.

~Tri-nitro-Toluene.~--Toluene, C_{7}H_{8}, now chiefly obtained from coal-
tar, was formerly obtained by the dry distillation of tolu-balsam. It may
be regarded as methyl-benzene, or benzene in which one hydrogen is
replaced by methyl (CH_{3}), thus (C_{6}H_{5}CH_{3}), or as phenyl-
methane, or methane in which one hydrogen atom is replaced by the radical
phenyl (C_{6}H_{5}), thus (CH_{3}C_{6}H_{5}). Toluene is a colourless
liquid, boiling at 110 deg. C., has a specific gravity of .8824 at 0 deg. C., and
an aromatic odour. Tri-nitro-toluene is formed by the action of nitric
acid on toluene. According to Haeussermann, it is more advantageous to
start with the ortho-para-di-nitro-toluene, which is prepared by allowing
a mixture of 75 parts of 91 to 92 per cent. nitric acid and 150 parts of
95 to 96 per cent. sulphuric acid to run in a thin stream into 100 parts
of para-nitro-toluene, while the latter is kept at a temperature between
60 deg. to 65 deg. C., and continually stirred. When the acid has all been run in,
this mixture is heated for half an hour to 80 deg. C., and allowed to stand
till cold. The excess of nitric acid is then removed. The residue after
this treatment is a homogeneous crystalline mass of ortho-para-di-nitro-
toluene, of which the solidifying point is 69.5 deg. C. To convert this mass
into tri-nitro derivative,