Why don’t they just make the proof the same as the percentage?
Proof is used to describe the alcohol content of certain beverages for historical reasons. There’s no need to change the meaning of the word just to simplify your life, Llardie. If you want to know the percentage it’s right there. It’s called “the percentage”.
I’ve often wondered this myself. Where did “proof” come from? Why isn’t liquor expressed as a percentage?
In days of old they ysed to put an amount of alcohol into acnon and see how far it fired, thus determining the strength of alcohol.
Although they dont fire it in a canon anymore, the proof (dont know about the name though) determined the actual strength and purity of the stuff. the volume is just how much of it is in the drink.
Beer in UK used to be referred to as “specific gravity” rather than ABV, but that just confused everyone even more.
Just go and pour myself another beer… hic…
I always heard (sorry, no cite) that 100 proof liquor (50% alchohol) would burn if a flame was introduced, and this was “proof” of the strength of the spirit. Seems unlikely that by coincidence, exactly 50% is needed for flammability, but maybe it’s rounded off.
I suppose it would be easy to test, but the strongest stuff I have in the house is 80 proof.
I believe that the strength of spirit needed for “proof” was, in contemporary parlance, 86.6° (which is why Scotch whiskey is distilled and diluted to this peculiar-sounding level). This was ultimately (I don’t know why) systemized at 150°, and an “archaic” degree of proof was about 4/7 of 1% (you can read British and Anglo-Irish stories of the 19[sup]th[/sup] century and find references to liquor that is “above proof”).
Later, American distillers decided (again, I don’t know why) to decouple proof from the idea of “proving” the distillate, and settled on calling a degree 0.5%.
IIRC in the UK 100% alcohol is 180 proof. 180 crops up a lot in old measurements- 180 degrees to a straight line, 180 between freezing and boiling etc. etc… This may have been adjusted to 200 degrees in the US.
Thus 70 proof used to be about 40% alcohol- most alcoholic spirits. Navy Rum was 100 proof- about 55% alcohol.
Original gravity is a measure of how much sugar has been turned into alcohol. For instance if the Specfic Gravity of the original brew is 1050 and it is brewed to a drinkable 1015, the OG is 1050. A handy rule of thumb is that Original Gravity approximates to ABV by merely removing 1000 from it. No scientific reason, but 1030 is aboy 3% and 1060 is about 6%.
There were a number of ways of testing ‘Proof’; one of them was a test involving dousing a measured volume of gunpowder with a measured volume of the liquor, the less liquor it took to prevent ignition, the lower the proof.
One of the things I learned in my “Alcohol Use & Abuse” class is that it is impossible to make 200 proof (100%) liquor in the real world because as soon as air touches it, the alcohol evaporates and the proof immediately drops to 199. Doesn’t answer the question, but it is one of those facts that is stuck in my head forever.
An unpressurized distillation process in normal air will not distill higher than 95% alcohol. By using double distillation, and a water free atmosphere for the condensation vessle that can be increased to 98% with a bit of care. Anything above that requires very specialized equipment, and it will absorb water from even fairly dry air if exposed.
Note: Even 151 proof liquor can be very harmful to the body if taken straight. Pure alcohol will destroy tissue upon contact.
Tris
“It was a woman drove me to drink and I didn’t even have the decency to thank her.” ~ W.C. Fields ~
What about Everclear? Does that mean it’s dangerous to drink it right out the bottle?
— G. Raven
Yes
This is a mathematical impossibility, so please allow me to unstick it for you. Assuming, as you say, that you are able to (if only for an instant) produce 100% liquor, then evaporating some must necessarily reduce the amount, but not the proportion, of alcohol in the vessel. I’m not sure if I can put this any simpler, but it seems extremely obvious to me. The only way you can alter the percentage of alcohol in 200-proof liquor is by adding water (or some other non-alcoholic substance), not by removing alcohol.
To clarify: By exposing the alcohol to air on this planet, you are necessarily exposing it to water vapor, some of which will dissolve into the alcohol (while some of the alcohol evaporates into the air) and thereby decrease the overall proof.
toadspittle’s explanation is the one I’ve commonly heard, and it sounds plausible, but my sources have always been drinking buddies, none of whom were chemists.
As for drinking pure (180 proof) alcohol, it may not be wise, but it’s pretty common in regions where white lightning (corn liquor) is distilled and distributed. I’ve partaken of it quite often, though I can’t drink it straight.
My cousins are in the habit of mixing it with schnapps. I find it quite hilarious that they use liquor to cut their liquor. My preferred method is to dribble a few tablespoons over a tumbler full of ice shavings, and then sip the resulting diluted mixture. I find a pure white lightning buzz is very different from any other alcohol inebriation - much more euphoric and bereft of any aftereffects aside from dehydration. But it’s very easy to overindulge; one must be careful not to completely debilitate oneself… 
I don’t know if I’m gonna sound like a geek or a drunk…
Proof: MrO is correct, with the information provided by Mangetout mixed in. When spirits were made and sold, one often wondered if it were watered down to boost profits. One way to prove if it were strong enough (however that was defined) was to pour some on gun powder and light it. If the gunpowder was completely wet with the spirits yet still burned, the spirits were “proven” with certainty (dare I say 100%?) to be strong enough (again, “for what” eludes me.) Later, it was shown that a solution of roughly 50% alcohol would allow this to happen. So, if 100 proof is 50% alcohol… natch.
200 proof: Many moons ago, when I worked in the chemistry department at a major university, I bought and sold 200 proof alcohol. (I occasionally used it.) It comes two ways:
1)200 proof alcohol, which is actually a teensy bit less than 200 proof because a bit of benzene is added to help keep the vapor pressure down and to keep moisture out. In laboratory settings, the benzene can be separated out easily.
2)pure, 100%, no additives, no preservatives, no questions asked alcohol. The semi-scientific name for this is “punctilious”. This is specially distilled and separated to deep moisture out. Further, it is bottled and sealed to protect its contents. This is the real deal - used for chromatography and such where purity is paramount. It also makes one hell of a mixer.
Nobody was ever stupid enough to do a shot of either, given that Benzene is poisonous and pure alcohol will mess you up in a big way.
Fun info: We had to have special permission to sell ethanol (methanol, isopropanol, butanol, etc. were fine) because of the alcohol tax. Because this stuff was not for consumption (especially the stuff with benzene) we got state permission to sell it without a liquor license and without charging alcohol tax.
The punctilious ethanol came in 1 pint bottles. The Benzene tainted stuff came in a 55 gallon drum. When I poured the tainted stuff, I had to get EXACTLY 55 one gallon containers out of it - no more and no less. I hated pouring out this stuff - it took forever to make sure the volumes in 55 cans were exactly the same, and you had to do it relatively quickly so it wouldn’t evaporate.
Geek. 