Making Gunpowder out of Corpses Worldbuilding Stack Exchange
Freely. Then add water for a total of about 300 gallons of yuck. Place it in a safe spot (far away from the house, if possible). After 10 months, pour it out onto shallow trays to dry. Separately with a mortar and pestle or handcranked mill, grind charcoal (all natural, no Match Light) to a powder and set aside.