A deflagrating or low explosive compound, consisting of a mixture of an alkali nitrate, usually potassium or sodium nitrate, mixed with charcoal and sulphur, which is mostly pressed, granulated and classified into definite grain fractions.

It is easily ignited, friction sensitive, and produces dense smoke. Still used as a propellant in fireworks although the advent of so-called smokeless powder has now reduced its role in commercial military type rockets, few remaining military uses, such as igniters, in fuses to give short delay, in black ammunition and as spotting charges.

It deflagrates faster than it donates; and is thus classified as a low explosive. The standard composition is 75% potassium nitrate, 10% sulphur and 15% charcoal. There are also graded compositions containing 74,70,68 or 64% potassium nitrate. Corresponding compositions based on sodium nitrate are known as B-Black Powder.