An old method of describing the alcohol content of spirits; originally defined as a solution of alcohol of such strength that it will ignite when mixed with gunpowder. Proof spirit contains 57.07% alcohol by volume or 49.24% by weight in the UK. In the USA it contains 50% alcohol by volume. Pure (absolute) alcohol is 175.25° proof UK or 200° proof USA. Now largely replaced by % alcohol by volume.
Subjects: Medicine and Health.