BLAST′ING POWDERS

(Melville and Callow’s). Prep. 1. ( Powder No. 1. ) Chlorate of pota a, 2 parts; red sulphuret of arsenic, 1 part; to be separately carefully reduced to powder, and lightly mixed together, scrupulously avoiding the use of iron instruments, percu ion, much friction, the slightest contact with acids, or exposure to heat. 2. ( Powder No. 2. ) Chlorate of pota a, 5 parts; red sulphuret of arsenic, 2 parts; ferrocyanide of pota ium (pru iate of potash), 1 part; as No. 1. 3. ( Powder No. 3. ) Chlorate of pota a and ferrocyanide of pota ium, equal parts. Obs. These compounds are not permanently injured by either salt or fresh water, merely requiring to be dried to regain their explosive character. They po e fully eight times the force of ordinary powder. One of their advantages, especially to the underground miner, is the very trifling extreme facility with which they explode by attrition, contact with a strong acid, and a slight elevation of temperature, render them unsuited to most of the purposes of ordinary gunpowder. On this account they should only be prepared in small quantities at a time, and with the utmost caution. Mr Callow, the inventor of them, lost several of his fingers, and was rendered a cripple for life, by an explosion of the kind referred to, which occurred only a few weeks after the sealing of his patent. A straw, or small strip of wood, only slightly wetted with oil of vitriol, and applied to a small heap of the powder, produces instantaneous explosion. Captain Wynand’s ‘Saxifragine’ is composed of nitrate of baryta, 76 parts; charcoal, 22 parts; and nitre, 2 parts. Schultze’s wood-gunpowder is composed of granulated wood treated with a mixture of nitric and sulphuric acid, afterwards impregnated with a solution of nitre. M. Bäudish has invented a method by which this wood-gunpowder may be compre ed into a solid substance, exerting great power and free from danger by transport. Litho fract eur, a white blasting powder used in Belgium, is a substance similar to gun-cotton. Me rs Nenmayer and Fehleisen’s haloxylin is composed of charcoal, nitre, and yellow pru iate of potash. See Gun-cotton , Gunpowder , Mining , .