Gunpowder is composed as a mixture of three ingredients: potassium nitrate (saltpeter), sulphur and charcoal. Potassium nitrate supplies oxygen for the reaction. Charcoal provides carbon and other fuel for the reaction. Sulfur serves as a fuel and also lowers the temperature required to ignite the mixture.
Procedure of making gunpowder went like this: charcoal and sulphur were prepared by being pulverized and sieved to remove foreign matter. Pulverization was done in horse-driven crushing mills. The saltpeter, charcoal and sulphur were weighed out in desired proportions which were determined by the way in which gunpowder will be used. Rockets used gunpowder with slower burning rate while bullets needed gunpowder with faster burning rate. Mixture is then then mixed together in a revolving drum. A little water is also added to make a so called green mixture. Mixture is then grinded in so called incorporating mills. They would make a mill cake which still contained a small amount of water. From the mill cake a meal powder was got by crushing with mallets or by a crushing machine. The meal powder was then again pressed and compacted to form cakes of hard press cake. Press cake was about half of the thickness of the mill cake but it had no water. After that, a corning is done. It is a process in which press cakes is broken down to form small granules of powder or corns of approximately the same size. When it was introduced in the sixteenth century, it was done by hand but in time it was done by machines which had series of rollers with different textures. After breaking granules are sieved to divide different sizes for different purposes. The remaining dust was removed in this process called dusting which uses a sieve in the shape of gauze-covered revolving cylinder. This dust is returned to the beginning of the process. The granules of gunpowder are tumbled and polished in a process called glazing. This increases their resistance to moisture which would render gunpowder unusable. In the nineteenth century this was done with a coat of black lead or graphite which was applied to the exterior. During glazing, granules can be dried but if they were not drying is done afterwards in stoves at a temperature of 40C which further reduces their moisture. This finishes production of gunpowder and makes it ready for testing. Gunpowder is tested for quality and consistency using mortars and canons on a firing range.
Proportions of ingredients differ by the country of origin and for their intended purpose. 75% potassium nitrate, 15% softwood charcoal, and 10% sulfur is used for pyrotechnics. Gunpowder for blasting rocks has 70% nitrate, 14% charcoal, and 16% sulfur but it also can be made from 40% nitrate, 30% charcoal, and 30% sulfur. In 1879, French war powder had 75% saltpeter, 12.5% charcoal and 12.5% sulfur while English war powder used the ratio 75% saltpeter, 15% charcoal, 10% sulfur. At the same time, British Congreve rockets used 62.4% saltpeter, 23.2% charcoal and 14.4% sulfur, but the British Mark VII gunpowder was made from 65% saltpeter, 20% charcoal and 15% sulfur.