it is dissolved by gently heating it with four
times its weight of sulphuric acid (95 to 96 per cent.), and it is then
mixed with 1-1/2 times its weight of nitric acid (90 to 92 per cent.), the
mixture being kept cool. Afterwards it is digested at 90 deg. to 95 deg. C., with
occasional stirring, until the evolution of gas ceases. This takes place
in about four or five hours.

The operation is now stopped, the product allowed to cool, and the excess
of nitric acid separated from it. The residue is then washed with hot
water and very dilute soda solution, and allowed to solidify without
purification. The solidifying point is 70 deg. C., and the mass is then white,
with a radiating crystalline structure. Bright sparkling crystals, melting
at 81.5 deg. C. may, however, be obtained by recrystallisation from hot
alcohol. The yield is from 100 parts di-nitro-toluene, 150 parts of the
tri-nitro derivative. Haeussermann states also that 1:2:4:6 tri-nitro-
toluene can be obtained from ordinary commercial di-nitro-toluene melting
at 60 deg. to 64 deg. C.; but when this is used, greater precautions must be
exercised, for the reactions are more violent. Moreover, 10 per cent. more
nitric acid is required, and the yield is 10 per cent. less. He also draws
attention to the slight solubility of tri-nitro-toluene in hot water, and
to the fact that it is decomposed by dilute alkalies and alkaline
carbonates--facts which must be borne in mind in washing the substance.
This material is neither difficult nor dangerous to make. It behaves as a
very stable substance when exposed to the air under varying conditions of
temperature (-10 deg. to +50 deg. C.) for several months. It cannot be exploded by
flame, nor by heating it in an open vessel. It is only slightly decomposed
by strong percussion on an anvil. A fulminate detonator produces the best
explosive effect with tri-nitro-toluene. It can be used in conjunction
with ammonium nitrate, but such admixture weakens the explosive power; but
even then it is stated to be stronger than an equivalent mixture of
di-nitro-benzene and ammonium nitrate. Mowbray patented a mixture of 3
parts nitro-toluol to 7 of nitro-glycerine, also in the proportions of 1 to
3, which he states to be a very safe explosive.

~Faversham Powder.~--One of the explosives on the permitted list (coal
mines) is extensively used, and is manufactured by the Cotton Powder Co.
Ltd. at Faversham. It is composed of tri-nitro-toluol 1