Page:The American Cyclopædia (1879) Volume VII.djvu/44

 EXPLOSIVES causes is a greater volume of evolved gases. The actual product of heat units as compared with the combustion of gunpowder is propor- tional, according to Dr. Craig, to the respective amounts of oxygen concerned in the two cases ; but the greater volume of the gases from gun cotton renders their temperature lower and their mechanical effect greater. This material burns without explosion when ignited in the open air. Ordinary percussion sometimes ig- nites it a source of peril in packing bore holes. The acid and aqueous gases which it evolves have prevented its use in ordnance ; moreover, it is very hygroscopic and liable to spontaneous decomposition, sometimes leading to explosion, rendering its storage perilous. Many of these objections, together with that of bulk, have been removed by Abel's process of manufac- turing gun cotton in compressed solid cylinders, which burn harmlessly, can be stored and trans- ported with safety, and explode with great power when ignited under confinement by means of a detonating powder. The experi- ments of Gen. Lenk, in Austria, led to this im- provement. The compressed gun-cotton is adopted in that country for artillery. Gun cotton is used as a filter for strong acids, and also (dissolved in ether) as a yarnish. (See COLLODION, and GUN COTTON.) Xyloidine is the white, pulverulent, and very explosive sub- stance obtained by Braconnet in 1833, by treating starch with concentrated nitric acid. Lithofracteur is the name originally given to a white blasting powder, consisting of coarsely ground saltpetre and sulphur, with a third substance, supposed to be sawdust or bran, treated with nitric acid. The improved litho- fracteur described below is a different sub- stance. Schultze's chemical powder, some- times called wood gunpowder (introduced in 1864), contains no sulphur ; and the charcoal is replaced with wood which has been tritu- rated, deprived of its acids, soluble salts, pro- teine, and albumen, and treated with concen- trated sulphuric and nitric acid. These grains of wood are subsequently saturated with nitrate of potash or baryta, or both, and dried. The powder can be wet and dried again without weakening it ; hence it may be kept or trans- ported in a damp state with perfect safety. It is about one third as dense as gunpowder, is more powerful, and leaves but a trifling residue. But it seems to have been superseded by nitro- glycerine compounds. Some inexplicable ex- plosions have occurred with it. The gases produced from it in mining have been com- plained of, possibly without good reason. Haloxyline is a powder tried in Austria, which contains no sulphur, and in which the char- coal is apparently represented by woody fibre. Like the slow-burning Neumeyer powder, it gives comparatively little noxious gas, is hygro- scopic, and works better in solid than in fis- sured rocks. It is asserted to burn harmlessly in the air; but like many other "harmless" powders, it has given rise to some strange and disastrous explosions. The above account of its composition follows the OesterreicMsche Zeitschrift (1866 and 1867); Wagner's " Tech- nology " (1870) says it contains charcoal, nitre, and yellow prussiate of potassa. Nitro-glyce- rine. This substance, known also as fulmina- ting oil, nitroleum, trinitrine, glyceryl nitrate, and glonoine, and undoubtedly the most impor- tant explosive since gunpowder, was discovered in 1847 by Sombrero, then a student with Pe- louze in Paris. It is formed by treating gly- cerine with concentrated sulphuric and nitric acid. (See GLYCERINE.) Until 1864 it found no practical application, except as a homoeo- pathic remedy for headaches similar to those which it causes. In that year Alfred Nobel, a Swede of Hamburg, began its manufacture on a large scale, and, though he sacrificed a brother to the terrible agent he had created, has persevered until in its later and safer forms nitro-glycerine has come into wide use and popularity. It is a clear, oily, colorless, odor- less, and slightly sweet liquid, heavier than water and insoluble in it, but soluble in ether and methyl alcohol ; crystallizes in long needles at 4 to 11 0. At 15 C. it becomes after a while thick ; prolonged exposure to 2 0. solidifies it. It detonates in the open air, under a strong blow or shock ; ignites with difficulty when poured out in a thin sheet, and even then burns incompletely without explosion. It can be evaporated at 100 C., if boiling is avoided ; but boiling, or the temperature of 180 C., causes an explosion. Confined or frozen, so as to permit the instantaneous transmission of an impulse through the mass, it will explode, sometimes under a very slight shock. It is usu- ally exploded with a detonating fuse. When badly prepared or preserved, it is liable to de- composition, yielding gases which exert a pres- sure within the containing vessel and create a condition of perilous sensitiveness to external shocks. The modern formula is CsHsNaOg, or 3 ; hence i<J is (No), in which 3 atoms of H have been replaced by 3 atoms of NO 2. Its specific gravity is 1'6; and 100 parts yield on combustion : CONSTITUENTS. By weight. By volume. 20 55,400 58 46900 Oxygen. . 3-5 3,900 Nitrogen 18-5 23,600 100-0 129,800 According to L'Hote, the oxygen is united with part of the nitrogen as protoxide. The heat liberated by the combustion is estimated to be twice as much as that of gunpowder; hence, while one volume of the latter yields in practice 200 volumes of cold gases, expanded by heat to 800 volumes, an equal weight of nitro-glycerine yields 1,298 volumes of gas, ex- panded to 10,384 volumes, giving 13 times the force of gunpowder. But the explosion takes