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 without the least danger; the cartridges being waterproofed, it can be employed in wet bore holes, and it can be tamped with water; and finally, as it contains sufficient oxygen to oxidise the carbon, no carbonic oxide (CO) gas is formed, i.e., its detonation is perfect.  It is a very safe explosive to use, being little susceptible to either blows or friction.

Not long ago, a committee, composed of Prof.  P. Bedson, Drs Drummond and Hume, Mr T. Bell, one of H.M.  Inspectors of Coal Mines, and others, in considering the problem whether the fumes produced by the combustion of tonite were injurious to health, carried out a series of experiments in coal mines for this purpose.  The air at the “intake” was analysed, also the air of the “return,” and the smoky air in the vicinity of the shot holes.  The cartridge was surrounded by the flame-extinguishing mixture, and packed in a brown paper bag.  During the first experiment nineteen shots were fired (= 6.29 lbs. tonite).  The “return” air showed only a trace of carbonic oxide gas (CO).  At the second experiment thirteen shots were fired (= 4.40 lbs. tonite), and analysis of the air of the “return” showed that CO was present in traces only, whilst the fumes contained only 1.9 to 4.8 parts per 10,000.