Gunpowder is a mixture of potassium nitrate oxidant that, together with sulfur and carbon, produces large amounts of nitrogen and carbon dioxide gas:

S(s) + 3C(s) + 2 KNO3(s) → 3CO2(g) + N2(g) + K2S(s)

It is also known as black powder (that is what it looks like). It was †rst made in China, around the †rst millennium, whilst in the West the Franciscan monk Roger Bacon had a recipe for making it in the mid-thirteenth century. It is straightforward to make up and handle and can be set off easily. However, it is a weak explosive and also produces smoke when ignited, giving away the user’s position on the battle†eld. It is also useless when damp, giving rise to the saying “keeping your powder dry”. Thus, in warfare, gunpowder was superseded as a propellant by smokeless powders, such as cordite, and supplanted by nitrocompounds as a shell †lling.