Archive for Proof

What’s that prove?

We are all familiar with the word “proof” when it comes to alcohol. In the US it’s 2x the ABV. In the UK it’s more complex. The proof is expressed in “degrees” (and uses the same symbol as temperature degrees).

I find the history of “proof” to be fascinating. The story is that when the British Navy paid its sailors partially in Rum, the sailors had to have a way to verify that the Rum was…potent. The test that they came up with involved three things that were readily available: Rum, Gunpowder and Matches.

It turns out that the weakest alcohol solution that will still permit the Gunpowder to ignite is 57.1% ABV. For some reason that I can’t fathom, this was denoted 100 degrees proof.

The formula is (4/7)*175 = 100 degrees proof. The 4/7 bit is the ratio of alcohol to water (i.e., 4 parts out of 7 are alcohol). Of course, the sailors didn’t know it was 57.1% ABV…that was beyond their ability to measure. They just wanted to get drunk! I have some whisky that is 100 degrees proof and it’s quite drinkable…and apparently it will do the job of inebriating the imbibers.

I have no idea what the 175 is for in the proof formula, but because it’s not 200, the maximum degrees proof that you can have occurs when you have (7/7) alcohol (100% ABV) and that gives 175 degrees proof. In the US, that would be 200 proof.

Personally, I think the proof system is confusing and if even wikipedia can’t explain it, then we have to just move on to the far less complex ABV system. It’s much simpler!