Potassium nitrate, charcoal and sulphur (sulfur, US-English) are the traditional ingredients of what substance?
Sulfur BC and found in Hanzhong. By the 3rd century, the Chinese discovered that sulfur could be extracted from pyrite. Chinese Daoists were interested in sulfur's flammability and its reactivity with certain metals, yet its earliest practical uses were found in traditional Chinese medicine. A Song dynasty military treatise of 1044 AD described different formulas for Chinese black powder, which is a mixture of potassium nitrate (), charcoal, and sulfur. It remains an ingredient of black gunpowder. Indian alchemists, practitioners of "the science of mercury" (sanskrit rasaśāstra, रसशास्त्र), wrote extensively about the use of sulfur in alchemical operations with mercury, from
Potassium nitrate after being cut off from its supplies of mineral sodium nitrates from Chile (see nitratite). Potassium nitrate can be made by combining ammonium nitrate and potassium hydroxide. An alternative way of producing potassium nitrate without a by-product of ammonia is to combine ammonium nitrate, found in instant ice packs, and potassium chloride, easily obtained as a sodium-free salt substitute. Potassium nitrate can also be produced by neutralizing nitric acid with potassium hydroxide. This reaction is highly exothermic. On industrial scale it is prepared by the double displacement reaction between sodium nitrate and potassium chloride. Potassium nitrate has a wide variety