Black Powder
The original firearm propellant, a mix of charcoal, sulfur, and saltpeter that fouls heavily and is much weaker than modern powder.
Black powder is the oldest gunpowder, a mechanical mixture of charcoal, sulfur, and potassium nitrate, or saltpeter, that served as the only firearm powder for centuries. It ignites readily and burns fast, but it produces a large cloud of smoke and far less energy per grain than its modern replacement, so a much larger charge is needed to reach a given velocity.
Its other hallmark is heavy, corrosive residue. Black powder leaves thick fouling in the bore that attracts moisture and must be cleaned promptly to prevent rust. These drawbacks are exactly what smokeless powder was developed to solve, and outside of muzzleloaders and historical arms black powder has been retired from precision shooting.