Gunpowder was not invented overnight, as far as historians can tell, it was a gradual process over hundreds of years to get from the initial discovery of an unknown explosive substance, to the sophisticated black powder that we know today. In 142 AD, during the Han Dynasty, a man named Wei Boyang wrote the first recorded text regarding gunpowder. He wrote about a concoction of three powders that would "fly and dance" violently in his “Book of the Kinship of the Three”, which detailed the experiments made by the early alchemists. It’s impossible to be absolutely certain that he was talking about gunpowder, but there is no other explosive known to scientists that uses three powders.
Chinese Taoist alchemists were certainly a major force behind the invention of gunpowder. Emperor Wu Di (156-87 B.C.) of the Han dynasty funded research by the alchemists on the secrets of eternal life. In their search for the elixir of life the alchemists experimented with the sulphur and saltpetre heating the substances in order to transform them.
By 300 AD, a scientist of the Chin dynasty called Ge Hong had actually written the ingredients of gunpowder and described the effects. He made gunpowder by mixing sulphur, charcoal, and saltpetre, also called potassium nitrate. Sulphur is found naturally in our environment as a yellow rock, it is mined and processed to create sulphur that can be used in gunpowder. You can make saltpetre with animal manure by leaving it to sit and decompose, potassium nitrate crystals form in the manure, and these can be drained off by washing the manure through with water. The three separate powders are then mixed together, using roughly fifteen parts of saltpetre to three parts of charcoal and two parts of sulphur. The reason gunpowder explodes is that it burns incredibly quickly and when it burns it releases hot gases that are larger in volume than the original powder, causing a rapid expansion, and thus the explosion.
It was during the rule of the T'ang Dynasty, about 700 AD, when people really began to use gunpowder in the way we expect today. T'ang Dynasty emperors are known to have used gunpowder to put on “magical” fireworks displays. By 904 AD, Chinese inventors realised that you could also use gunpowder as a very powerful weapon. Initially the army used gunpowder in the form of crude rockets. They put small stone cannonballs inside bamboo tubes and blasted the cannonballs out by igniting gunpowder at one end. This is basically the same principal that makes guns work today.
The Chinese Emperors tried their best to keep their incredible discovery under wraps, but by the 1100's AD their secret had escaped, and people in the Islamic Empire also began to comprehend how to use gunpowder for weapons. It wasn't long before Europeans also learned how to use this amazing new Black Powder. We aren't sure exactly how the Europeans first found out, but it has been suggested that it may have had something to do with the Third Crusade, crusaders returning to Europe brought tales with them of a terrible new weapon, like a monster that could breathe fire! The Chinese Emperors’ secret was out, and the world had a new way of fighting its wars.
There is no doubt that the use of gunpowder in warfare changed the face of the world forever. It became possible to engage an enemy at greater distances than before, and as accuracy and range improved over time, so did the sophistication of the weapons. From crude rockets to cannon to hand guns and bombs. Even today long after the first rocket was ever fired, the same basic principles apply. Advancements in technology mean that gunpowder itself is now only used in smaller arms. However anyone today firing a gun can thank the work of the early Chinese alchemists who, ironically, in their search for eternal life, discovered the most efficient way of ending it.