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. [Illustration: TORPEDO PRACTICE. Bow discharge.] 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 which had always been found in securing uniformity in mixtures, and that this difficulty had become the more apparent as the gun became more highly developed, I sought to produce a powder which should consist of a single chemical substance in a state of chemical purity, and which could be formed into grains of such form and size as were most suitable for the piece in which the powder was to be used. I succeeded in so treating cellulose nitrate of the highest degree of nitration as to convert it into a mass like ivory and yet leave it pure. In this indurated condition the gun cotton will burn freely, but it has not been possible to detonate it even when closely confined and exposed to the initial detonation of large masses of mercury fulminate. [Illustration: TORPEDO PRACTICE ON THE CUSHING. Broadside discharge.] I am happy to say that this principle has now been adopted by the Russian Government, and by our navy in its specifications for smokeless powder; but they have, I think unwisely, selected a cellulose nitrate containing 12.5 per cent or less of nitrogen instead of that of the highest nitration.