How is actual proof determined in terms of alcoholic content?

soonappear

Gunpowder was originally used to determine actual proof. Spirits were graded with gunpowder: a solution of water and alcohol "proved" itself when it could be poured on a pinch of gunpowder and the wet powder could still be ignited. If it didn't ignite, the solution had too much water in it and the proof was considered low or "underproof". This process led to the nickname firewater, coined by Native Americans. A "proven" solution was defined as 100 degrees proof (100°). This has since been found to occur at 57.15% ethanol. This is still used as the British definition. A simpler ratio to remember is 7:4 - 70° proof is 40% alcohol by volume. A hydrometer was traditionally used to measure the precise proof of a spirit, a practice which has gone through many formal changes. Apr 11 06, 11:30 PM

Baloo55th

I have grave doubts about the firewater name coming from methods of establishing the proof rating of spirits - how many traders would go to the trouble of proving whiskey to Injuns? Surely the name comes from the effect on the back of the throat of spirit that has been (to quote the current WKD adverts) been "Carefully matured for, oooh, minutes". Aguardiente is the same as firewater in meaning, but is a type of brandy not whiskey. Apr 12 06, 3:53 AM

peasypod

Alcoholic proof is a measure of the quantity of ethanol within the subject beverage, and is approximately twice the percentage of alcohol by volume (ABV). In the United States, the proof number is twice the percentage of the alcohol content measured by volume at a temperature of 60°F (15.5°C). Apr 12 06, 6:34 AM