Saltpeter

Saltpeter is a flammable powder that can be found in bat guano in caves across the world. The flames themselves are quick to burn out, and do not provide any force to them, leading it’s major use to be fire starting and food preservative.

Effects
It has an acidic bitter taste to it, but otherwise has no lasting effect, though it might not sit well. In an alchemic brew, it gives it a splashing like effect, reacting violent when suddenly moved or the breaking of the vial.

Rarity
Fairly easy to find, as it can be found in bat guano in caves across the world.