中国古代四大发明――火药 Four greatest inventions of ancient China---gun powder

    火药，是用硝石、硫磺和木炭的粉末混合在一起制成的，人们叫它“黑火药”。

    火药的发明与炼丹有直接的关系。中国古时候，炼丹家把矿物和植物配合起来，放在炉中烧炼，想炼出能使人长生不老的“仙丹”来，当然，这是不可能实现的事情。但是，炼丹家在炼丹过程中却发现了能燃烧爆炸的物质，制出了火药。火药大约出现在隋代。唐朝末年，火药开始用在军事上。宋代，火药武器已经广泛使用。

    公元13世纪，火药和火药武器开始西传，先传到阿拉伯国家，后来又传到欧洲的一些国家。

Gunpowder, also known since the late 19th century as black powder, was discovered in the 9th century in China, attributed to Chinese alchemists searching for an elixir of immortality.

Gunpowder was made by mixing elemental sulfur, charcoal, and saltpeter (potassium nitrate). The charcoal traditionally came from the willow tree, but grapevine, hazel, elder, laurel, and pine cones have all been used.

When the ingredients were carefully ground together, the end result was a powder that was called 'serpentine.' The ingredients tended to require remixing prior to use, so making gunpowder was very dangerous. People who made gunpowder would sometimes add water, wine, or another liquid to reduce this hazard, since a single spark could result in a smoky fire. Once the serpentine was mixed with a liquid, it could be pushed through a screen to make small pellets, which were then allowed to dry.

This discovery led to the invention of fireworks and the earliest gunpowder weapons in China. In the centuries following the Chinese discovery, gunpowder weapons began appearing in the Arab world, Europe, and India.