Gun Powder

Collier's New Encyclopedia (1921)

like many other socalled "modern inventions," gun powder appears to have been known to the Chinese several centuries before its invention in Europe, whether we ascribe the invention to Roger Bacon in the 13th century or to Friar Schwartz in the 14th. Its earliest well-authenticated use in war- Crecy in 1346. fare was at the battle of Its use was rapidly extended and within a century after Crecy it had driven the bow and arrow from the field and relegated the lance and the battle axe to the secondary position of weapons for special emergencies only. It is rather surprising that for more than five centuries, the ingredients first used remained unchanged. These were saltpeter, charcoal and sulphur;-charcoal to furnish the fuel for burning, saltpeter to furnish the oxygen needed to combine with the carbon of the charcoal, and sulphur to accelerate the rate of burning. The products of combustion are carbon dioxide and nitrogen, both gases, and the sulphate and carbonate of potassium, both solids. The expansive force of the gases is due not alone to the change from the solid to the gaseous state, but to the further expansion from the heat released by the change. The solids, being finely divided, produce the dense smoke which marks the firing of a gun loaded with what is now commonly called "black powder" as distinguished from the more modern smokeless powder. Not every explosive substance is suitable for use as a "propellant" in a gun. To be available for such use, not only must the explosive develop great power but it must develop this power gradually, so that the projectile shall be started from its seat slowly and driven down the bore more and more rapidly as the pressure behind it rises to a maximum. If the full pressure were developed instan taneously, the gun would be ruptured before the projectile was started from its seat. Here we touch upon the difference between "explosion" and "detonation." The explosion of a charge of powder in a gun, sudden as it is, is slow compared with the detonation of the "high explosives," nitro-glycerine, gun-cotton, etc. In one case we have an actual burning, the flame of which passes from grain to grain of the powder, occupying an interval which is perfectly appreciable and can be measured. In the other case we have a shattering of the chemical structure and a re-arrangement of the atoms in a new structure, which is as nearly instantaneous as any process known to nature. It has been stated that for several centuries after the introduction of gun powder, its composition remained practically unchanged. This does not mean that no improvements were made. There are several factors besides the nature of of the powder which inthe ingredients nts fluence its behavior. Of these, the most important are the size, shape and density of the grains. A large grain burns more slowly than a small one, and a dense grain more slowly than a light one. And slow burning means less violence of explosion and more gradual and progressive development of pressure. The rate of burning is still further affected by the shape of the grain-a grain which exposes a large surface to ignition burning more rapidly than one of smaller surface. Taking adv advantage of these facts, artillerists designed many forms of powder grains of varying degrees of effectiveness, but hampered always by the limitations of expansive power inherent in the chemical composition of black powder. It was early recognized that certain of the high explosives would be ideal for gun powders if they could be tamed into the slow and regular burning needed for a propellant. It was realized not only that their power was enormously in excess of the maximum to be hoped for from black powder, but that, as the products of their combustion were entirely gaseous, a powder made from them would be pr practically smokeless. Many plans were tried for bringing them under control, but the problem was not solved until, toward the end of the last century, the French chemist and artillerist Vielle discovered that the burning of gun-cotton could be perfectly controlled by making it into a colloid. A colloid is a hard, horn-like substance, entirely homogeneous, and free from the cellular structure which, in simple gun-cotton, allows the flame of ignition to flash instantaneously throughout the mass. Singularly enough, it was found that one of the substances in which gun-cotton could be dissolved for colloiding was another of the most violent of high explosives, nitro-glycerine. When these two extremely sensitive and tremendously powerful explosives are treated together by suitable processes, their combined power is preserved but their sensitiveness almost completely eliminated. The resultant substance is the well-known British "Cordite", one of the most efficient of the modern smokeless powders. Another of the substances having the power of colloiding gun-cotton Vol. IV-Cyc-BB is acetone, used in American and French smokeless powders. As has been already stated, none of these powders are absolutely smokeless, but such smoke as they produce is lar largely water-vapor, which dissipates quickly. The point should be emphasized, however, that smokelessness is a matter of altogether secondary importance, the real value of gun-cotton ders lying in their power, which is powders enormously greater than that of black powder, and in the facility with which they lend themselves to variations of size and shape suitable for guns of vari- This point is forcibly ous calibers. brought out in the variegated shapes and sizes of smokeless powders used in the United States Army and Navy. See EXPLOSIVES.