Does black powder only become combinable at the forge? I decided to go ahead and mix them while I was within BF1/L3 by dragging the salt over the coal but no mixture occurred; it just disappeared (ie, nothing to mix the sulfur with).
The actual ingredient is salt peter which is rumored to have certain affects that it is rumored that, because of these affects, military cooks mix it into their foods. It was found in a military kitchen. Hmm, I wonder?
