Alcoholic proof
measure of alcohol content / From Wikipedia, the free encyclopedia
Alcoholic proof is a measure of how much ethanol there is in an alcoholic drink. It is commonly used the world over, on the basis that 100 degrees proof is the equivalent of 50 % alcohol by volume (ABV or Alc/Vol). In the United States, it is double the percentage of ABV. A hydrometer can be used to measure the precise proof of a spirit. This test has gone through many formal changes.
A "proven" solution was defined as 100 degrees proof (100°). People have found out that this takes 57.15% ethanol. This value is still used as the British definition. A simpler ratio to remember is seven to four: 70° proof is 40% alcohol by volume.
The "proof" system was introduced in the 18th century. The British claim that this term has a nautical background. Every evening, sailors would line up for their daily quota of grog/rum. This had to first be proved to be as strong as promised and not watered down. The spirit was tested with gunpowder: a mixture of water and alcohol proved itself when it could be poured on a small amount of gunpowder and the wet powder could still be lit. If the powder did not ignite, the mixture had too much water in it and the grog was considered below proof.
It might have happened earlier, as the Americans claim that this definition came about in the 17th century when European traders began making a large quantity of distilled spirits and wine available to American Indians. The very same process led to the nickname firewater, this time given by Native Americans. There is no record of the finite strength of the distilled spirits in the context of its sale to or consumption by Native Americans.