Just some info:
Modern Blackpowder has a formula of 75% KNO3, 10% sulphur and 15% carbon.
Blackpowder is a mixture of 76% Potassium Nitrate (Saltpeter, KNO3), 14% Charcoal (Carbon, C), and 10% Sulfur (S). These were roughly the percentages, by weight, used by the U.S. Military in the mid 1800s.
Later formulas for gunpowder increased the potassium nitrate to about 75%, charcoal 15% and the sulphur to 10%, giving more power to the mixture.
The current standard composition for black powder manufactured by pyrotechnicians was adopted as long ago as 1780. Proportions by weight are 75% potassium nitrate, 15% softwood charcoal, and 10% sulfur. These ratios have varied over the centuries and by country, and can be altered somewhat depending on the purpose of the powder. For instance, low power grades of black powder, unsuitable for use in firearms but adequate for blasting rock in quarrying operations, is called blasting powder rather than gunpowder with standard proportions of 70% nitrate, 14% charcoal and 16% sulfur; blasting powder may be made with the cheaper sodium nitrate substituted for potassium nitrate and proportions may be as low as 40% nitrate, 30% charcoal and 30% sulfur.