Potassium Chlorate: Chlorine through Potash, Ure 1839

Potassium chlorate, once 'oxymuriate of potash', gave the first friction matches their fire. Andrew Ure (1839) describes making it by bubbling chlorine through strong potash solution until the chlorate crystallises out, and purifying it by recrystallising from boiling water. Chlorine is deadly: outdoors and with a respirator only.