One of my greatest memories of science class as a kid, was making saltpeter from scratch with a particularly creative teacher. First, we built a latrine and the

One of my greatest memories of science class as a kid, was making saltpeter from scratch with a particularly creative teacher. First, we built a latrine and the class pee’d on straw and lime for a couple of months. Then, we boiled the straw in copper pots, poured the liquid into jars, and suspended cotton string in the jars. As the liquid evaporated, saltpeter grew as crystals on the string.