The term proof that is found today on every bottle of liquor dates back centuries. In earlier times, there was no scientific way to find out how much alcohol was in liquor.
So dealers who bought and sold liquor tested the products by soaking gunpowder in the beverage and then lighting it. If the gunpowder caught fire, it meant that the liquor contained more alcohol than water. This test was considered “proof” that the beverage was strong, and beverages that allowed the gunpowder to ignite were called “100 proof.”
Today, the word proof means something different. In America, the proof number is equal to twice the percentage of alcohol in the beverage. So if a drink contains 40 percent alcohol, it’s called “80 proof.”
An American alcohol used for cordials is the most powerful in the world, 190 proof, or 95 percent pure alcohol!