<P> Alcohol proof is a measure of the content of ethanol (alcohol) in an alcoholic beverage . The term was originally used in the United Kingdom and was equal to about 1.75 times the alcohol by volume (ABV). The UK now uses the ABV standard instead of alcohol proof . In the United States, alcohol proof is defined as twice the percentage of ABV . </P> <P> The measurement of alcohol content and the statement of content on bottles of alcoholic beverages is regulated by law in many countries . </P> <P> The term proof dates back to 16th century England, when spirits were taxed at different rates depending on their alcohol content . Spirits were tested by soaking a pellet of gunpowder in them . If the gunpowder could still burn, the spirits were rated above proof and taxed at a higher rate . As gunpowder would not burn if soaked in rum that contained less than 57.15% ABV, rum that contained this percentage of alcohol was defined as having 100 degrees proof . The gunpowder test was officially replaced by a specific - gravity test in 1816 . </P> <P> From the 18th century until 1 January 1980, the UK measured alcohol content by proof spirit, defined as spirit with a gravity of ​ ⁄ that of water, or 923 kg / m, and equivalent to 57.15% ABV . </P>

Where did the term proof for alcohol come from
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