Proof as a way of measuring the strength of a given liquor came
from a practice used by the early American settlers to test their brews.
They saturated gunpowder with alcohol and ignited it: too strong, it
flared up; too weak, it sputtered. A strong blue flame was considered the
sign of proper strength. Almost straight alcohol was diluted with water
to gain the desired flame. Half and half was considered 100 proof. Thus,
86-proof bourbon is 43% alcohol. Because alcohol dilutes itself with
water from the air, 200-proof, or 100%, alcohol is not possible. The U.S.
standards for
...more
