alcohol stregths

[kopend]

what does it mean on a bottle of spirit when it says .... proof. & how can you get over 100% proof

ie,  i had some vodka that was 176 proof

[j2buttonsw]

Proof is out of 200% (stupidly) so divide by 2 to get "proper" % (176% proof is 88% aqueous alcohol)

[OBonio]

I always thought the proof measurement is the quantity needed to make gun powder combust. ie 176% is 1.76 times the amount of gunpowder. Someone might have been pulling my leg there though.

[OBonio]

Seems like they weren't :

http://www.madsci.org/posts/archives/feb98/888729125.Ch. r.html

[Gef]

Don't agree with j2. Most whisky is now 40% ABV which used to be 70 degrees proof. More like a conversion factor of 1.75

[Bangkok]

The standard ABV used to be 50%, which if demonstrated to be correct it was 100% proof (proven). 

[Loosehead]

It's not percent proof it's degrees proof, a common error.

[rinkytink]

 

Dictionary.com has:

Proof: The alcoholic strength of a liquor, expressed by a number that is twice the percentage by volume of alcohol present.

[Tim123]

In the same way that we can't agree on what a gallon or a ton is, the USA and UK have different definitions of proof spirit.

100% Alcohol by Volume = 175 Degrees UK Proof =200 Degrees US Proof.

100 Degrees UK Proof = 57% ABV.

100 Degrees US Proof = 50% ABV.

[Octavius]

Proof is another (older) measure of the strength of an alcoholic liquid.
It had its origins in days when a simple test was needed that the liquor did indeed contain a *correct* measure (or more) of alcohol. And it was indeed a simple test.
Some of the liquor was poured over a little gunpowder and ignited. If the alcohol content was adequate, then it would burn 'just right' with a steady blue flame and eventually ignite the gunpowder. If there was insufficient alcohol then it would fizzle out and the gunpowder would be too wet to burn. The 'just right' condition 'proved' the liquor and it was declared to be '100% proof'.

In the US a very simple relationship is defined between 'proof' and %AbV. It is that
proof = 2 � %AbV
So, 180 proof (US) = 90 %AbV.

It the UK it was laid down by an Act of Parliament in 1816 that "a quantity of 100% proof liquor would have the same weight as 12/13 ths of the same volume of pure water at 51�F." (That is twelve thirteenths)
So,
100 proof (UK) = 57.06 %AbV
200 proof (US) = 100 %AbV = 175.25 proof (UK)
100 proof (US) = 50 %AbV = 87.6 proof (UK)

At one time (in the days of sailing ships, cannons and gunpowder) the makers of Plymouth Gin distilled a special gin for the Royal Navy. It was 57%AbV or 100% proof. Why?
In order to keep it secure it was stored in the magazine close by the gunpowder. So, even if it leaked and wetted the gunpowder, at 100% proof the gunpowder would still explode.

Though that need has been long gone, they still market the stuff!

In the metric system, it is very convenient to know that the %AbV multiplied by 10 immediately tells us how many millilitres of alcohol there are in 1 litre of the mixture. But other measures are much used and the arithmetic is not so easy.

[j2buttonsw]

Hurray! We're all right! Nice answers Tim and Octa

[smee.tracey]

Oh Octavius how are you so wise? Do you NEVER leave your 'puter? Only joshing, it's a comfort to know you are there