How it began
Gunpowder was invented by Chinese alchemists in the 9th century, during the late Tang dynasty. It came out of Taoist experiments with sulfur and saltpeter in the search for longevity drugs and for ways to transmute materials. The first confirmed references are in two Taoist texts: a formula of 808 combining sulfur, saltpeter and birthwort, and a text about 50 years later warning that heating sulfur, realgar and saltpeter with honey had burned hands and faces and even burned down a house. Alchemists called the discovery huoyao, fire medicine, a name still used for gunpowder in China.
How it works
Gunpowder, also called black powder, is a mixture of saltpeter (potassium nitrate), sulfur and charcoal. For about 300 years its composition has been roughly 75 percent saltpeter, 15 percent charcoal and 10 percent sulfur. Prepared in about those proportions, it burns rapidly when ignited and produces approximately 40 percent gaseous and 60 percent solid products, the latter mostly appearing as whitish smoke.
How it spread
Knowledge of the mixture moved west across Asia. Traces of its Chinese origin survive in the terms used in the Muslim world for related items: saltpeter was described as Chinese snow or Chinese salt, fireworks were called Chinese flowers and rockets were called Chinese arrows.
What changed first
Britannica reports that black powder was being used in China for fireworks and signals by the 10th century. The earliest surviving chemical formula for gunpowder is in the Wujing Zongyao, a Song dynasty military manual of 1044. Between the 10th and 12th centuries the Chinese developed the huo qiang, or fire lance, a short-range device that channeled the force of the powder through a cylinder, at first a bamboo tube. The powder was also used in smoke bombs, rockets and bombs thrown by mechanical artillery.
What lasted
Gunpowder is popularly listed as one of the Four Great Inventions of China. Britannica describes it as an invention that dramatically changed human affairs, and as the first explosive of its kind. The Chinese name fire medicine remains a reminder that it began as a side result of the search for drugs to lengthen life.
