osition of tonite I have found by analysis to be 51 per
cent. gun-cotton to 49 per cent. barium nitrate. The heat liberated is
practically the same as for an equivalent weight of KNO_{3}; but the
barium nitrate mixture weighs 2,223 grms. instead of 1,971 grms., or
one-eighth more. The advantage in mixing a nitrate with gun-cotton is that
it supplies oxygen, and by converting all the carbon into carbonic acid,
prevents the formation of the poisonous gas carbonic oxide (CO). The
nitrates of potassium and barium are also used admixed with nitro-
cellulose in several of the sporting smokeless powders.

~The Manufacture of Tonite.~--The explosive tonite was patented by Messrs
Trench, Faure, and Mackie, and is manufactured at Faversham and Melling at
the works of the Cotton Powder Company, and at San Francisco by the Tonite
Powder Company. It consists of finely divided and macerated gun-cotton
incorporated with finely ground nitrate of barium which has been carefully
recrystallised. It is made by acting upon carbonate of barium[A] with
nitric acid. The wet and perfectly purified, finely pulped gun-cotton is
intimately mixed up between edge runners with about the same weight of
nitrate, and the mixing and grinding continued until the whole has become
an intimately mixed paste. This paste is then compressed into cartridges,
formed with a recess at one end for the purpose of inserting the
detonator. The whole is then covered with paraffined paper.

[Footnote A: Witherite, BaCO_{3} + 2HNO_{3} = Ba(NO_{3})_{2} + CO_{2} +
H_{2}O.]

The tonite No. 2 consisted of gun-cotton, nitrates of potash and soda,
charcoal and sulphur. Tonite No. 3[A] is composed as follows:--Gun-cotton,
19 per cent.; di-nitro-benzol, 13 per cent.; and barium nitrate, 68 per
cent. or similar proportions. It is a yellowish colour, and being slower
in its explosive action, is better adapted for blasting soft rock.

[Footnote A: Tonite No. 1 was patented by Messrs Trench, Faure, and
Mackie, and tonite Nos. 2 and 3 by Trench alone.]

Tonite is extensively used in torpedoes and for submarine blasting, also
for quarries, &c. Large quantities were used in the construction of the
Manchester Ship Canal. Among its advantages are, that the English railways
will take tonite on the same footing as gunpowder; it is a very dense
material; if wetted it can easily be dried in the sun; it very readily
explodes by the use of a proper detonator; while it burns very slowly and