In this video, we learn how to make potassium nitrate for black powder. First, purchase some Pottasche. After this, mix equal parts of the pottasche with ammonium nitrate. These will combine together, then set the glass on top of the measuring device and the mixture will start to bubble slightly. You will see a black formation occur inside of the mixture. After this, remove the ammonium carbonate from the water using a filter. Then you will be left with potassium nitrate. Be very careful with this, as it's a harmful chemical. Be sure to wear gloves while handling it, and enjoy!