Under the former Sykes hydrometer system, abandoned by UK for beverage alcohol measurement in 1980 to align with EU metrology, 70 proof was equal to U.S. 80 proof, that is, 40% ABV (Gay Lussac system). Sykes assigned 100 proof to a proven spirit, one mixed with gunpowder that burned (both powder and spirit) when set alight, which occurred most satisfactorily at 57.1% ABV. 175 proof was 100% pure alcohol (200 U.S. proof). Anything over 100 proof Sykes was "overproof", anything under, "underproof". 70 proof was 30 underproof.