NITRO-GLYCERINE [Cp116N30,e., or C6I15(N04)306], known also as glonoin or glor oil, is a compound Which is prOdwie^d'by the action of .a mixture of strong nitric and ,u1 phuric acids on glycerine at low temperatures. Two methods of preparing it are given in Watts's Dictionary of Chemistry, vol. ii., pp. 890, 891, to which we must refer the reader who seeks for details on this subject. According to whatever method it is pre pared, it is obtained as a light yellow oily liquid, of specific gravity varying from 1.5.2-5 to 1.6, inodorons, but having a sweet, pungent, aromatic taste; a single drop, however, if placed on the back of the tongue, produces headache and pain in the back, which last for many hours. It is only slightly soluble in water, but dissolves readily in ether, alcohol, and methylated spirits. This substance was discovered in 1847 by Sobrero, then a student in the laboratory of Pelouze iu Paris, and afterwards professor in Turin. But though its discoverer ascertained its remarkable properties as an explosive, it remained simply an object of scientific interest till 1804, when it began to be manufac tured on a large scale for blasting purposes by Nobel, a Swede resident in Hamburg. If ignited in the open air, nitro-glycerine burns rapidly and with a brisk flame, without any exploiou; if poured out in a thin sheet, it ignites with difficulty, and burns incom pletely. But it explodes at once if it is exposed to a moderately blow or concus sion, to the concussion due to the explosion of gunpowder, to contact with red-hot iron, and especially to the action of detonating mixtures and fulminates; it likewise explodes on exposure to a high temperature (see below); the explosion, however it is produced, being in all cases excessively rapid,,and unaccompanied by smoke. It is this explosive power that renders this compound a useful agent in blasting. According to Dr. Rudolf Wagner, the distinguished Bavarian technologist, it may be cooled down to 4' without becoming solid; but this statement probably refers to the chemically pure compound; for the nitro-glycerine of commerce, which was patented by the first maker, under the name of Nol)el's Nicht Hasting Oil, becomes solid if exposed for a considerable time to a temperature of 46°, crystallizing in long needles, which arc most dangerous to handle, since they explode, even on being gently broken, with appalling violence. At 320',
nitro-glycerine begins (according to Dr. Adriani) to decompose, giving oft red vapors; and if the heat be suddenly applied, or slightly raised above this point, the substance explodes with great violence; while, according to other observers, it is liable to explode at 240', or a little higher; and if exposed for a length of time to half that temperature, explosion may take place at 180' or less. It is obvious from the formula for nitro-gly cerine that it may be assumed to consist of glycerine, in which three atoms of hydrogen are replaced by three of peroxide of nitrogen, NO.. The products of the com plete combustion of 100 parts of pure nitro-glycerine are—water, 20 parts; carbonic acid, 5S; oxygen, 3.5; and nitrogen, 18.5; and hence it has been calculated that one volume (say, a cubic inch) of this compound, at a specific gravity of 1.6, yields, on com bustion or explosion: .
Aqueous vapor, 554 volumes (say cubic inches) Carbonic acid, . . . . . . 469 " Oxygen, 39 " Nitrogen, . ..... . 236 " CC Ag 1298 '`According to Nobel, these gases expand, on explosion, to 8 times their bulk; in which case, one cubic measure (say, one cubic inch) of nitro-glycerine will yield 10,384 cubic measures (say, cubic inches) of gases; while one cubic measure of gunpowder will only yield 800 cubic measures-of gases. Hence, it follows that, for equal bulks, nitro-gly cerine is 13 times as strong as gunpowder, while for equal weights it is 8 times as strong.
The danger of using this compound in mining. etc., is greatly increased by its insta bility. Even when pure, it is liable, at a heat of or less, to undergo slow, spontane ous decomposition into glycerine, oxalic and hydrocyanic acids, ammonia, etc., with a continuous-escape of gaseous products, which, exerting pressure on the liquid, renders it so prone to explosion that even a slight concussion is attended with danger; and the impure commercial compound decomposes far more rapidly than the pure nitro-gly cerine; indeed, impure nitro-glycerine may, from this cause, be regarded as "dangerously self-explosive even while standing quietly" (Adriani, op. cit.).