Page:The American Cyclopædia (1879) Volume VII.djvu/45

EXPLOSIVES 37 place much more suddenly than that of gunpow- der ; hence the practical gain in effect is greater than the above figures show. The suddenness with which the force is developed renders nitro-glycerine unsuitable for ordnance. The very dangerous character of this material has led to various restrictions upon its transporta- tion. It continues to be used in many places, and is prepared on the spot as it is required. In the Hoosac tunnel, Massachusetts, the Uni- ted States works at Hallett's Point, New York, and at San Francisco, it was employed. Its insolubility in water and its liquid form and high gravity render it very convenient for sub- marine operations and blasting in wet ground. But its form brings a danger that portions of it, unexploded even in bore holes, may be scat- tered in rock fissures, or portions may be split accidentally, or may remain in vessels once filled, and afterward be exploded by accident. The proper way to get rid of it is to pour it into a running stream. To remove the great dangers connected with the preparation and transportation of this material, many proposi- tions have been made, principally for mixing the oil with some substance (wood spirit, sul- phate of zinc, lime or magnesia, &c.) which would render it inexplosive, and which could afterward be removed by simple means (e. g., by water) when the oil was to be used. None of these have come into use. "When congealed it has been thought more dangerous than when fluid ; but this view is now contradicted by many practical authorities. Certainly careless handling and thawing of frozen mtro-glycerine has caused much loss of life and property. Through the pores or in the stomach, even in small quantities, this oil causes a terrible head- ache and colic. Headache likewise results from inhaling the gases of its combustion ; but all persons are not alike affected by these ; and it is probable that most persons suffer little in- convenience from this cause when they have become accustomed to it. Nobel introduced in Swedish quarries the practice of soaking common gunpowder with nitro-glycerine be- fore blasting. The effect produced was very great ; but this method was soon superseded by the invention of dynamite or giant powder, also introduced by Nobel. Dynamite is finely pulverized silex, or silicious ashes, or infusorial earth (most frequently the last), saturated with about three times its weight of nitro-glycerine, and constituting a mass resembling damp Gra- ham flour. The pulverulent form prevents the transmission of ordinary sudden shocks, except under pressure in a confined space. The pres- sure of the inert mineral constituents serves also to absorb heat, so that a high temperature cannot be so easily imparted to the whole ; but when imparted, this temperature effects a great expansion of the gases and increased effective- ness of explosion. Ignited in the open air, dyna- mite burns quietly with nitrous fumes. Exploded (usually by means of a fulminating fuse or cap), it gives carbonic acid, nitrogen, and hydrogen, and leaves a white ash, with little or no smoke. Under favorable circumstances, the effective- ness of dynamite is equal or superior to that of nitro-glycerine ; a fact not surprising, if it be remembered that the latter is liable to scat- ter unexploded drops, by reason of the maxi- mum rapidity of its ignition. Dynamite is now generally recognized as the safest of all explo- sives. It is not affected by a prolonged tem- perature of 100 0., nor is it as dangerous as nitro-glycerine when it solidifies (at 8 0.). Neither light nor electricity nor ordinary shocks cause it to decompose or explode. The prin- cipal dangers connected with its use are those of the strong fulminating powders used in the percussion fuses to explode it. It is also pos- sible that if dynamite is carelessly made, it may contain an excess of nitro-glycerine, which, overcoming the capillary force of the mineral particles, may collect in drops and settle from the mass, becoming a source of serious accidents. Moreover, it may be that freezing, or thawing after freezing, has a tendency to segregate the oil. Dualline, introduced in 1869 by Lieut. Dittmar, is another nitro-glycerine powder, consisting probably (the exact composition is a secret) of Schultze's wood gunpowder, sat- urated with this oil. Another formula is, in 100 parts, 50 of mtro-glycerine, 30 of fine saw- dust, and 20 of nitre. It has been considera- bly used in Germany and the United States. As compared with dynamite (which it resem- bles in many respects), it has the advantage that it can be exploded under confinement with an ordinary blasting fuse; that it does not congeal so easily as dynamite ; and that it is cheaper. As a disadvantage, Serlo mentions, that under some conditions it partially ex- plodes, partially burns, and in this case pro- duces noxious gases. Improved lithofracteur, or lithofracteur-dynamite, manufactured by Krebs at Deutz near Cologne, is supposed to be the former lithofracteur saturated with ni- tro-glycerine. Another formula is, in 100 parts, 52 of nitro-glycerine, 30 of silex, 12 of stone coal, 4 of nitrate of soda, and 2 of sul- phur. This would be a mixture of dynamite with a very bad gunpowder. The safety and effectiveness of dynamite are claimed for this powder, with an additional advantage that it can be exploded at much lower temperature as low, according to some experiments, as 12 C. Nobel has recently patented new nitro-glycerine powders, of different degrees of strength. The strongest consists of 68 parts nitrate of baryta and 12 parts rich bituminous coal, saturated with 12 parts nitro-glycerine. Nearly as powerful is a mixture of 70 parts nitrate of baryta, 10 parts resin, and 12 parts nitro-glycerine. The effect of each may be in- creased by adding 5 to 6 parts sulphur. They are exploded with percussion fuses. Dr. Jus- tus Fuchs, formerly in Nobel's employ, has proposed as an improvement on dynamite a compound containing 85 instead of 75 per cent, of nitro-glycerine, and instead of infusorial