Excerpts from Books and Wikipedia
Chinese alchemists discovered gunpowder in the ninth century (c. 800). "Arab chemists acquired knowledge of gunpowder in the thirteen century, rapidly employing it for military purposes, including the production of a gun made from a bamboo tube reinforce with iron. . . . By the late nineteenth century, "black powder" had been replaced by nitrocellulose, resulting in a smoother, more powerful explosion from a firearm with little smoke deposit." [1001 Inventions]" The correct formula for making gunpowder--from saltpeter [potassium nitrate], sulphur, and charcoal--was first discovered in China, perhaps as early as the ninth century AD; and by the Twelfth century Sung armies used both metal bombards and grenades. The new technology gradually spread westwards until by the early fourteenth century several Arabic and European sources mention iron artillery and the first known illustration of a bombard in Europe (dated 1327, right) bears a striking resemblance to the earliest picture from China (dated 1128, left)." [Cambridge Illustrated History of Warfare, p. 106]