MODERN EXPLOSIVES.

Taranaki Daily News, Volume LVII, Issue 116, 9 October 1914, Page 6

MODERN EXPLOSIVES.

INTERESTING EXPERIMENTS. LECTURE BY PROFESSOR EASTERFIELD. At Wellington on Tuesday a lecture by I'rofessor HastcrfU'ld on'the subject "War Explosives," took place. The professor said that a high tempo iiture and a dillusion ot gasses were two features of explosions. Detonations occurred when t'he explosion travelled nt a fast rate —thousands of feet per second, not only (lame, but light could produce an explosion. The experiment of burning magnesium wire in proximity to a mixture of chlorine resulted in an explosion. But the most common cause of explosions was concussion. Houses in which nitro-glyccriue was made were separated from one another by earthworks to interrupt tlio pulse' of the explosion. Experiments with iodino of nitrogen, a few grains of which were (placed in six adjacent heaps, illustrated this point. Dealing with war proper, thq professor explained the composition of gunpowder, which was known to Rogen Bacon in the thirteenth century. It had gone almost entirely out of use, said the lecturer, as a means of propelling projectiles. But before its disappearance it was used in the British Army in the form of cakes, not powder. Nitre, obtained from nitrates, was a necessary ingredient to gunpowder, guncotton, and most other explosives. .Most of the nitrates come fron India/ overseas and Continental nations, especially Germany, had made strenuous efforts to obtain supplies by chemical experiments. The French discovered a way of obtaining nitrates from sewage, and the Germans Jiad discovered a method of making nitrates from the air in localities where electric power was cheaply obtainable. A German-owned nitrate factory existed in-Norway, and tho product could easily -be carried to Prussia/ "The pro- !

feasor calculated that £IOOO a day went up the Wellington Gas Company's chimneys in the form of nitrates. Gun-cotton, continued the lecturer, cotton soaked in nitric acid, was for a long time used in guns, but sometimes it detonated itself of burning, and bo burst the barrels, and sometimes exploded when stored. Not cotton alone, but any cellulose, mich as Xew Zealand flax, would do for the basis of guncotton. Both this and nitroglycerine were similar in nature. When these two explosives were incorporated and mixed witli vaseline the result was a jelly called cordite, used all over the world as a propellant. The professor then showed cross sections of different kinds of shells, including common shell and shrapnel. Lyddite (picric acid, made from carbo'.ie acid, made in turn from coal tar) was used to pack shells. Picric acid was used for dye for fifty years before its exploding properties were suspected. It exploded with great force, killed all men within twenty-five yards of the exp'osion, and reduced a steel shell to metal dust. Lyddite, however, exploded when brought into contact with rust, and this was its great disadvantage. To overcome this, the inside of a shell was varnished, and another coal tar product was being tried to obtain a new explosive without this disadvantage. Fulminate of mercury, made from nitric acid, quick silver and alcohol, was used ior making detonating caps. A detonator composed of this substance, containing IS grains, exploded with such forco as to split a railway sleeper when the experiment was tried. All modern explosives, said the professor in conclusion, were the result of continuous experimenting in the chemical laboratories. Great Britain was now spending £30,000 per annum on explosive experiments at Woolwidh, and the reproach that she depended on the, search of other nations no longer existed.