saltpeter

[neilr01]

where can i buy saltpeter

[bhvma]

Technically 'saltpeter' is potassium nitrate. It's typically available in reagent grade from a pharmacy, but will be expensive because of its purity, and controlled because it is potentially dangerous. Depending on your need, a much cheaper equivalent might be ammonium nitrate, a common fertilizer available at a farm supply outlet. Sodium nitrate could also be useful, from the same outlet.