Few substances in history have had as profound an effect on human history as gunpowder... and its discovery was an accident!
Ancient alchemists in China spent centuries trying to discover an elixir of life that would render the user immortal. One important ingredient in many of the failed elixirs was saltpeter, also known as potassium nitrate.
During the Tang Dynasty, around 850 A.D., an enterprising alchemist (whose name has been lost to history) mixed 75 parts saltpeter with 15 parts charcoal and 10 parts sulfur. This mixture had no discernable life-lengthening properties, but it did explode with a flash and a bang when exposed to an open flame. According to a text from that era, "smoke and flames result, so that [the alchemists'] hands and faces have been burnt, and even the whole house where they were working burned down."
Many western history books over the years have stated that the Chinese used this discovery only for fireworks, but that is not true. Song Dynasty military forces as early as 904 A.D. used gunpowder devices against their primary enemy, the Mongols. These weapons included "flying fire" (fei huo), an arrow with a burning tube of gunpowder attached to the shaft. Flying fire arrows were miniature rockets, which propelled themselves into enemy ranks and inspired terror among both men and horses. It must have seemed like fearsome magic to the first warriors who were confronted with the power of gunpowder.
Other Song military applications of gunpowder included primitive hand grenades, poisonous gas shells, flame throwers and land mines.
The first artillery pieces were rocket tubes made from hollow bamboo shoots, but these were soon upgraded to cast metal. McGill University professor Robin Yates notes that the world's first illustration of a cannon comes from Song China, in a painting from about 1127 A.D. This depiction was made a century and a half before Europeans began to manufacture artillery pieces.
By the mid- to late-eleventh century, the Song government had become concerned about gunpowder technology spreading to other countries. The sale of saltpeter to foreigners was banned in 1076. Nonetheless, knowledge of the miraculous substance was carried along the Silk Road to India, the Middle East, and Europe. In 1267, a European writer made reference to gunpowder, and by 1280 the first recipes for the explosive mixture were published in the west. China's secret was out.
Down through the centuries, Chinese inventions have had a profound effect on human culture. Items like paper, the magnetic compass, and silk have diffused around the world. None of those inventions, however, have had quite the impact that gunpowder has, for good and for bad.