Determining Alcohol Proof

Determining alcohol proof is necessary if you drink alcoholic beverages. Satisfy your curiosity with techniques for determining alcohol proof and what it really means.

What alcohol proof means

The phrase "alcohol proof" refers to the percentage of ethyl or grain alcohol that is in a solution of alcohol in water. The proof value is twice the percentage of alcohol in the solution. If a solution is 45 percent alcohol, it is described as 90 proof.

The term itself

Historically, the term "proof" in reference to the amount of alcohol in a solution is traced back to the days of first selling alcoholic beverages. A qualitative test is said to have been developed as an indicator of how much alcohol a beverage contained. First, some of the beverage was poured onto black powder. Second, an attempt was made to ignite the powder. If the powder ignited, it was deemed "proof" that it contained enough alcohol. If the powder did not ignite, that was evidence that the beverage contained too much water.

Alcohol proof today

The days of pouring a beverage onto black powder to determine its alcohol content are over. Today, the percentage of alcohol in a water solution is generally determined using a hydrometer, a floating device which measures the specific gravity or density of the solution. Because alcohol has a lower density than water, the density of a solution decreases as the percentage of alcohol in the solution increases. The hydrometer has a long stem that projects from the solution. As the density of the solution decreases, the stem sinks further into the solution. Thus, the amount of the stem that projects out of the solution indicates the percentage of alcohol in the solution. The less the stem projects from the solution, the higher the alcohol proof.

Whether you choose a shot glass or a cocktail, alcohol can satisfy in many different forms. The issue of how to determine the alcohol proof of a beverage is not usually the subject of everyday conversation, but it is an interesting conversation starter at your next cocktail party.