Page:The American Cyclopædia (1879) Volume VII.djvu/46

 38 EXPLOSIVES earth a chemically prepared substance, possess- ing greater absorbing power, and capable of complete combustion with almost no solid resi- due. The Colonia powder, manufactured in Cologne, is said to be a black gunpowder, with 30 to 35 per cent, of nitro-glycerine. It is ex- ploded by artificial means only. Chlorate of Potassa Powders. The property of acids con- taining large proportions of oxygen to part with it readily is strongly shown by chloric acid, HClOs, in which the oxygen is very loosely held. The anhydric acid cannot be isolated ; but the salts (particularly of potassa and baryta) have been extensively employed in the manufacture of explosives, by mixing with combustible ma- terials. Even the heat of percussion or friction causes them when so mixed to detonate. A few centigrammes of chlorate of potassa rubbed in a mortar with sulphur or sulphide of anti- mony, will explode loudly and perhaps shatter the mortar. A chlorate should never be mixed by rubbing with a combustible substance. A mixture of chlorate of potassa with sugar, sul- phur, sulphide of antimony, or similar substan- ces, may be ignited by sunlight alone, or by a drop of sulphuric acid. On this principle were based the matches (now out of fashion) which were tipped with a mixture of chlorate of po- tassa and sugar, and were ignited by pressing them upon asbestus, saturated with sulphuric acid. During the French revolution, it was attempted to replace nitre in gunpowder with chlorate of potassa ; but the mixture was too explosive for artillery purposes. Berthollet's experiments at Essonne, in 1792, were stopped by a terrible explosion ; he had a narrow es- cape, and several were killed. A cane, striking powder on the floor, was the cause. Percus- sion caps were formerly filled with gunpowder out of which the nitre had been leached, and to which this chlorate had then been added. Sir William Armstrong uses a mixture of amor- phous phosphorus and chlorate of potassa as a percussion powder for discharging ordnance. A mixture of equal weights of black sulphide of antimony and chlorate of potassa is general- ly employed for this purpose. White gunpow- der, introduced in 1849 by Augendre, for bronze ordnance and shells, is composed of 28 parts yellow prussiate of potassa, 23 parts loaf sugar, and 49 parts chlorate of potassa. According to Wagner, the gaseous products of complete combustion should be 47'4 per cent., and the solid residue (cyanide and chloride of potassium and carburet of iron) 52-6 per cent. The gases from 100 grammes would amount, at C. and 769 mm. barometric pressure, to 40,680 cubic centimetres ; and at 2604*5 0., the estimated temperature of combustion, to 431,162 cubic centimetres. The cost and corrosiveness of this powder have prevented its adoption. Blake's "safety explosive," patented hi Eng- land, consists of one part sulphur and two of chlorate of potash. These substances are kept dry and separate, and mixed when required. The powder burns slowly when ignited, but its explosion is effected by means of a detonating tube, containing the compound itself, fulmina- ting mercury, and ordinary powder. The last is ignited. A blasting powder is made at Plymouth, England, consisting of tan bark soaked in chlorate of potash and covered with powdered sulphur. It is said to burn slowly in the open air, but to explode with great en- ergy when confined. Explosive paper is pre- pared by impregnating paper with a mixture of 9 parts chlorate of potassa, 4 of nitre, 3 of ferrocyanide of potassium, 3| of powdered charcoal, -^ of starch, yf-g- of chromate of po- tassa, and 80 of water which has been boiled about an hour. The paper, when dry, cannot be exploded by jar or percussion, or by a tem- perature less than that of its combustion. Ex- periments with it in Austria have given good results. Chloride of nitrogen is perhaps the most terrible explosive known to chemists. Dulong, who discovered it in 1812, and lost an eye and several fingers on the occasion, kept the discovery a secret, lest other chemists should repeat his perilous experiments. The unfortunate result was that Davy, who subse- quently made the same discovery, was also in- jured. It is sometimes unintentionally pro- duced in the treatment of ammoniacal solutions with chlorine. In such cases the chemist, hav- ing discovered its presence, quietly retires, locks the laboratory, and leaves the dreadful intruder to spontaneous and harmless decom- position, which takes place in the course of a day or two. Hypochloric acid, in gas or liquid form, is scarcely less dangerous. Pier ate of Potash Powders. Picric acid, obtained by the action of nitric acid upon carbolic acid, is a compound of carbon, nitrogen, hydrogen, and oxygen, the formula, as given in Wag- ner's "Technology," being C6H 3 (NO 2 ) 3 0. Its salts are explosive per se, and have been used in torpedoes. Their preparation has given rise to some frightful explosions; one at the Sorbonne, in 1869, killed five persons, and wounded many more. Dessignolle's powder for blasting is a mixture of picrate and nitrate of potassa, to which for a gunpowder charcoal is added. Sulphur is unnecessary. The ad- vantages claimed for it are the harmless charac- ter of the products of combustion (nitrogen, aqueous vapor, and carbonate of potash), and the control of its power by variation of the per- centage of the picrate. Ten grades are manu- factured, containing from 8 to 20 per cent, of this substance, the lowest being equal in effec- tiveness to common powder. Ammoniakrut is a new powder invented by the Swedish chemist Norrbin, and believed to resemble the foregoing, but to contain picrate of ammonia instead of potassa. It is black, doughy, and damp ; is ignited with difficulty by flame ; ex- plodes under percussion ; does not congeal at ordinary temperatures ; has an explosive ener- gy exceeding even that of dynamite; but is said to be liable to decomposition, to attract moisture and lose power when stored, and to