" Proof refers to the percentage of ethyl alcohol by volume in any particular type of alcoholic beverage. Proof corresponds to twice the percentage rate. For example, a bottle of whiskey may be 80 proof or 40% alcohol by volume."
If I recall correctly, there's more to it than that. If you take a liter of grain and mix it with a liter of water, you don't get two liters of mixture, you get less. Here's why:
The molecules of water and alcohol intersperse with one another in less volume. Consider what happens when you pour together a bushel of peas and a bushel of potatoes. You don't get two bushels of the mixture, because the peas fill in the spaces between the potatoes. Same with alcohol and water.
And that's why there are varying uses of proof, if I remember my high school science teacher correctly. Some people determine the proof by using percentage of volume and others by percentage of weight. When I get a chance I'll see if I can do a bit more research on this. I would think that chance will come around the 9th of June. Assistance willbe greatly appreciated.
TEd
