EXPLOSIVES (from Lat. explosus, p.p. of explodere, to drive out, to drive out a player with clapping, to explode; from ex, out + plaudere, plodere, to clap, strike, applaud), are substances which easily react at comparatively low temperatures with the formation of a con siderable volume of highly expanded gas, the evolution of heat and light and the production of sound. At ordinary temperatures they may be solid bodies like gunpowder or liquid like nitroglycerin or gaseous like fire damp mix tures. They may consist wholly of a single chemical compound like mercuric fulminate, or of mixtures of combustible substances with sup porters of combustion or oxidizing agents like blasting powder, which is a mixture of char coal, sulphur and sodium nitrate. Though the temperature is different for each explosive they can all be caused to explode if heated to the explosion temperature, which under given cir cumstances are for nitrogen chloride, 93° C.; mercuric fulminate, 152° C.; emmensite, 165° C.; nitrostarch, 175° C.; dynamite and gun cotton, each 180° C.; and blasting gelatine, C.; nitroglycerin, 218° C.; blasting powder, C.; picric powder, 273° C.; rifle powder, 275° C.; best sporting powder, 315° C.
History.— The inventor of gunpowder, the oldest of explosives, and the place where it originated, are not known. The invention has been ascribed by different authors to Marcus Grmcus, Albertus Magnus, Roger Bacon and Berthold Schwarz; to the Arabians, whose works were largely used by Marcus Grwcus in his writings; to the Hindus, because of cer tain passages occurring in the code of Gentoo laws prepared by Indian savants by order of Warren Hastings in the 18th century; and to the Chinese because of certain statements made by Marco Polo. There seems to be little doubt that this confusion exists (1) because modern meanings have been given to words and phrases used in the old manuscripts; (2) because of the intentionally confusing methods employed by the writers of the Middle Ages; and (3) be cause gunpowder for use in guns was not the invention of any one person, but was really the result of a progressive development.
It is recorded that what moderns call °Greek fire," and the ancients called unaphtha,° was employed in the defense of Constantinople in the 7th century and that these fiery composi tions were propelled against the enemy by means of arrows from bows, or in hollow vessels of stone or iron thrown by war engines. Though consisting at first of pitch, rosin, sulphur and similar easily inflammable and highly combusti ble substances, it is easy to imagine that in the tentative development of these materials of war nitre was added to the combustible substances and that there was thus produced a deflagrating composition for use as bursting charges in bombs and grenades and for the manufacture of devices analogous to modern firecrackers and rockets with which to frighten and confuse their foes.
The supposition that gunpowder was known before it was applied for use in guns is sup ported by the older historians. All the com ponents and mixtures for Greek fire similar to gunpowder were already known in the time of Hassan-al-Rammah (1290). From an exhaustive search of the literature Guttman arrives at the conclusion °that gunpowder was gradually de veloped from Greek fire, and that it was known for years before cannons and guns were thought of. The use of purer materials in making it developed its propulsive power, and led to the subsequent invention of cannons and guns. The Arabians were the first to make gunpowder-like mixtures, probably about 1280 A.D., while the idea of utilizing their propulsive force, that is the invention of guns and cannons, belongs to the monk, Berthold Schwarz, of Freiburg, Sax ony; the date of the latter invention being prob ably 1313 A.D." It is accepted as indisputable that gunpowder mills existed at Augsburg,.Ger many, 1340, and at Spandau, Germany, 1344, and that the English used gunpowder in guns at the battle of Crecy, 1346.