"Gimme charcoal to the measure two
Send the bullet where you want it to
Gimme sulfur to the measure three
Make that powder gonna keep you free
Gimme saltpeter, measure fifteen
Sweetest shootin' that you've ever seen"
Leslie Fish, "Black Powder and Alcohol"

Black powder, the first form of gunpowder ever invented, is a fuel/oxidizer mixture. The charcoal provides the fuel for combustion; the sulfur accelerates the reaction; the saltpeter provides the oxygen. This is why black powder can operate in the absence of air.