Pusser'S Gunpowder Proof Rum

Gunpowder Proof: Prior to the invention of the hydrometer, the Royal Navy ship’s “Pusser” shutdown claims of watering down sailors’ daily tots by dousing a bit of gunpowder in the rum and attempting to light. If the mixture ignited, the rum was “at proof.” If it didn’t, the Pusser might find himself tossed to sea.