Explosives have played a great role in the history of the different countries. It is believed that the first explosive to be discovered was gunpowder. The Chinese used it as early as the 9th century AD. They were originally used for making fireworks. It was only much later that it began to be used for firing guns when the European nations began using it in the 14th century. At that time gunpowder was made from a mixture of potassium nitrate, charcoal and sulphur. This mixture continued to be used till the end of the 19th century.
In 1845, Schoenbein, a German chemist, experimented with different materials trying to make an explosive, which would be even more powerful than gunpowder. He treated cotton fibres with a mixture of nitric acid and sulphuric acids. This resulted in the production of nitro-cellulose, or guncotton, which was a fibrous product resembling cotton. It had a more explosive effect than the existing gunpowder.
At around the same time, an Italian chemist, Ascanio Sobrero, was also experimenting with different chemicals in order to make a powerful explosive. He added glycerin to nitric and sulphuric acid to make nitroglycerin. This was an even more powerful explosive than guncotton.
Nitroglycerin was a very explosive material. It presented great danger especially in transportation. Alfred Bernhard Nobel, a Swedish Chemist and engineer, tried to solve this problem. He had found a less dangerous way to produce nitroglycerin but it was still not safe enough for handling. It still tended to explode during transportation.
One day, Alfred Nobel discovered that one of his cans of nitroglycerin had leaked into the box of kieselgur in which they were stored as a safety precaution. Kieselguhr is a kind of light earth of volcanic origin and is absorbent and chalk-like. The mixture of nitroglycerin and kieselguhr formed a kind of hard mass. Nobel recognized in this mixture the solution to his problem. Thus dynamite was discovered in 1866. It was an excellent explosive, which was less sensitive to shock.
Dynamite is used in bombs and for rock blasting. It is not set off by heat but needs a small explosion from a detonator to make it blow up. Dynamite is used extensively these days in war as well as in peaceful jobs. Old buildings are often demolished using dynamite. They are also used for blasting rocks in quarries and in mountain sides for making tunnels and roads.
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