Scientific Notes: An explosive element of modern civilisation

EXPLOSIVES HAVE provided the world's most powerful source of portable energy for almost a millennium.

The story of explosives begins with gunpowder, ranked by Thomas Carlyle, along with printing and the Protestant religion, as one of "the three great elements of modern civilisation". Because it looks like soot, gunpowder is commonly known as blackpowder; it consists of a mixture of potassium nitrate, sulphur and charcoal.

It was almost certainly invented in China in the middle of the ninth century AD, and it was first used there in fireworks to frighten away evil spirits. It was probably intro-duced into the Western world by Roger Bacon about 1250 AD, using an enigmatic anagram to hide its composition. Although it was far from perfect, it was the only explosive to be used for practical purposes for around 600 years.

Thereafter, from around 1870, it was replaced by the so-called high explosives or nitro-compounds. The first two were nitrocellulose or guncotton and dynamite, made from nitroglycerine, but they were followed, over the years, by blasting gelatine, gelignite, Lyddite, TNT, RDX, PETN, HMX, and HNIW.

Important events in the history of explosions include the methods of testing gunpowder, which, surprisingly, led to the invention of the steam engine; the early development of cannons and hand guns; the downfall of the Byzantine empire, in 1453, when new-fangled gunpowder proved to be more effective than the old Greek fire; the advance of the Moguls into northern India in 1526; the overthrow of the Incas in Peru, the Aztecs in Mexico, the Red Indians in America, the Aborigines in Australia, and the Maoris in New Zealand; the collapse of the feudal system in Britain; the defeat of the Spanish Armada in 1588; the edict of King Charles I, in 1626, that "his loving subjects . . . shall keep and preserve all the urine of man" to provide potassium nitrate; the rise and fall of the American Powder Trust; the American Civil War; the great British shell shortage at the start of the First World War; the dropping of the atomic bombs on Hiroshima and Nagasaki to end the Second World War; the post-war development of the hydrogen bomb; and the use of Semtex by terrorists.

The formidable Alfred Nobel, born in Stockholm in 1833, played a major role in the story. He invented the patent detonator, dynamite, blasting gelatine, gelignite, and ballistite, and, on his death in 1896, he ruled a world-wide empire with 93 factories, and his estate was valued at pounds 2m.

Nobel's English contemporary was Sir Frederick Abel, the Chief Chemist to the War Office, who devised a safe method of making guncotton and invented cordite. Guy Fawkes is an infamous member of the rolecall for his activities on 5 November 1605; Sir William Congreve for his invention of early rockets at the start of the 19th century; the du Pont family, who fled from France to America, in 1800, and established a gunpowder factory in Wilmington, Delaware, which has grown into today's vast international organisation.

One, the Rev Alexander Forsyth, thanks to his enjoyment of shooting wildfowl in Scotland invented the percussion cap which revolutionised the firing of guns, in 1805; Thomas Bickford, a Devonian leather merchant, invented safety fuse, which greatly reduced the risk in the setting off of explosives; the American, Charles E. Munroe, made shaped charges; Chaim Weizmann, saved the day, in 1915, by inventing a method of making acetone from conkers, and eventually became the first President of the State of Israel; and the international team of scientists, led by Rob-ert Oppenheimer and General Leslie Groves, brought the Manhattan Project, which developed atomic bombs, to fruition during the Second World War.

What they achieved, in a unique field of tech- nology, has greatly affected all our lives.

G.I. Brown is the author of `The Big Bang - a history of explosives' (Sutton, pounds 19.99)