Soldiers that didn't want to accept watered rum would wet their powder with newly delivered rum and see if it would burn (explode). If there was sufficient alcohol then the rum was 100 degree "proof".
Half of that alcohol content corresponds 50 proof (50%), and so on, though there are some differences in how the US and the EU make measurements.
I don't know about the soldiers testing their rum,but 100 Proof whiskey is 50% alcohol by weight, 50 proof would be only 1/4 alcohol.Chat with our AI personalities
Degree proof is equal to twice the percent by volume summed at as proof of an alcoholic drink.