Saltpeter. Do you know what it is? I didn’t, but the word sure did conjure up some awkward images. For most of us born after the Great Depression, we know saltpeter as potassium nitrate. Up until about the 1930s, saltpeter works were a booming industry in Chile, Bolivia, and Peru. The three countries were supplying most of the world with potassium nitrate to be used in fertilizers, rocket propellants, fireworks, and gunpowder.