"[…] it took a relatively long time for people to realize that no one could make pure alcohol or pure water from ethanol and water."
"This is because ethanol is not an ordinary mixture, it’s an azeotrope. Instead of boiling purely and separately at two different temperatures, its vapor will form a certain proportion. Steam from alcohol is 95.57 percent alcohol. Get a pot of 95.57 percent ethanol boiling and the steam will be 95.57 percent ethanol right down until the last drop evaporates. That’s the limit."
Why Can’t You Distill Liquor That’s 100 Percent Pure Alcohol?
The highest proof alcohol you can buy is Everclear, at 190 proof. That’s nothing! Let’s get together and make an alcohol that’s 200 proof! Except we can’t possibly do that. There’s a physical limit to how pure alcohol can actually get, and we’ll tell you why.