Page:Popular Science Monthly Volume 56.djvu/323

Rh down the train of gunpowder to the fulminate, which then detonates and causes the detonation of the dynamite.

Although gun cotton, nitroglycerin, and their congeners can be and usually are fired by detonation, there has within recent years been a great number of compositions invented which, while formed from gun cotton alone or mixtures of it with nitroglycerin, burn progressively when ignited and are therefore available for use as propellants; and since the products of their burning are almost wholly gaseous, they produce but little or no smoke and are therefore called smokeless powders. As upward of fifty-seven per cent of the products of the burning of ordinary gunpowder are solids or easily compressed vapors, this comparative smokelessness of the modern powders is a very important characteristic, and



when used in battle they seriously modify our former accepted methods of handling troops. While this is the feature of these powders which has attracted popular attention, a far more important quality which they possess is the power to impart to a projectile a much higher velocity than black powder does, without exerting an undue pressure on the gun. A velocity of over twenty-four hundred feet per second has been imparted to a one-hundred pound projectile with the powder that I have invented for our navy, while the pressure on the gun was less than fifteen tons to the square inch.

Prior to my work in this field all the so-called smokeless powders were mixtures of several ingredients, resembling gunpowder in this respect. But, considering the precise and difficult work that was expected of these high-powered powders and the difficulty