Gunpowder is an explosive material that burns rapidly to form high-pressure gas. Expansion of this gas inside the barrel of a gun can accelerate a bullet to great speed. Gunpowder is therefore used as a propellant in a variety of ammunition. It is also used in explosives for blasting operations, in fireworks, and in fuses.
Kinds of gunpowder.
The first important substance used as gunpowder in guns and cannons was black powder. Black powder consists of a mixture of saltpeter (potassium nitrate), charcoal, and sulfur. These ingredients are pressed together and then broken into small pieces. In some cases, graphite is added. Grains of black powder range from fine powder to pellets.
Variations of the basic formula for black powder have been used for special purposes. Sulfurless gunpowder contains saltpeter and charcoal but no sulfur. It is not as powerful as regular black powder, but it causes less corrosion (gradual wearing away) of the gun barrel. For commercial black powder used in fireworks and blasting, saltpeter sometimes is replaced by less expensive sodium nitrate.
There are several disadvantages in using black powder, including corrosion, dirt, and much smoke. But such problems have been largely eliminated by the development of smokeless gunpowders. The most important ingredient in these smokeless powders is nitrocellulose. Some smokeless powders also include nitrate salts and additives. In others, called colloided powders, the nitrocellulose is dissolved in nitroglycerin.
History.
People in Asia were probably the first to acquire knowledge of the explosive properties of saltpeter and sulfur. This knowledge moved westward, probably through contact with the Arabs, and eventually reached Europe in the 1200’s. Gunpowder contributed to changes in the social system of Europe in the 1300’s and 1400’s. Since about the 1100’s, rulers and armies had relied in part on stone castles to defend the estates of lords and nobles. The castles could not stand against assaults by heavy cannonballs fired by gunpowder.
Smokeless gunpowder was developed in the 1800’s. An early kind of smokeless powder was guncotton, an invention of the mid-1840’s. It exploded powerfully but was dangerous to manufacture. A more useful powder was invented in 1864. About 1887, the Swedish chemist Alfred Nobel created the first colloided powder. Today, smokeless powder is more commonly used in ammunition than is black powder.
