I'm wondering who decided vodka should be 40% and why? (Have to include a little filler to make the question long enough to pass quality standards. )
It seems 40% is just the right mix. Here is an article on the subject:
In case the article is no longer available, here are the main points:
If you mix 40 parts of alcohol and 60 parts of water, the alcohol acts as an antifreeze, allowing the mixture to stay liquid below zero. So you can leave vodka in a freezer and the bottle won’t burst.
This 40/60 mixture has other fascinating properties. You can pour vodka into an open glass at room temperature and the alcohol and water will evaporate in such a way that it will leave the relative concentrations unchanged. If you come back later, you’ll still have vodka — just less.
How to check the alcohol content? At 40 percent or more alcohol, you can set fire to the fumes. Add a little water and you can’t anymore.
As you add alcohol to water to achieve that 40 percent balance, the mixture becomes more viscous, because there are enough alcohol molecules to start forming spaghetti-like chains. This contributes to the smoothness of vodka and its almost syrupy consistency when cold.
by Northeastern University physicist John Swain
Not only vodka is 40% (or 43% in most countries) but many other distilled beverages are as well: whisky and brandy, for example are usually sold at 43%.
This is the case for several reasons.
Firstly, legislation. Allowable alcohol strengths and the resulting taxes they attract are all regulated. Whisky, for example, cannot be less than 40% ABV and still be legally sold as whisky in the US.
Secondly, flavor. When you get over 43%, the alcohol strength begins to interfere with flavor.
Thirdly, effect. Beverages with 50% or more of alcohol can hit the drinker rather hard. Also, health consequences begin to play a role here.
Fourth: cost. If you make a beverage much stronger than it legally needs to be, you either drive up the product price (thus reducing sales volumes) or cut into your profit margin. The economy of volume plays a role here, especially for the large alcoholic beverage producers.
Incidentally, the reason why most cream liqueurs are sold at about 17% ABV is that with less alcohol the cream is susceptible to spoilage (the alcohol acts as a preservative) but at much higher strengths the alcohol tends to destabilize the suspension.
This question is very popular in Russia. The answer may be found in Russian wiki: https://ru.wikipedia.org/wiki/Водка#Появление_40-градусной_водки Here is the translation of the main part
Prior to the appearance of alcoholometers in Russia, the fortress of a water-alcohol mixture (“bread wine”) was measured by so-called annealing. If half of the wine was burned out of the wine, it was called "polugar". "Polugar", whose fortress was about 38%, served as the basic normative unit of vodka fortress, since 1817 - the recommended one, since 1843 - officially anchored. Subsequently, when the fortress began to be measured by alcohol meters, the Minister of Finance of the Russian Empire, M. H. Reitern, offered to round this number to forty. There were two reasons: the convenience of counting the volume of wine and incoming excise taxes, and a kind of stock "for shrinkage and leakage" so that the consumer in any case is guaranteed to receive the usual 38 "polugar" degrees.
Besides in Russia there are a lot of myths about it, for example, that it was Mendeleev who discovered that 40 is the best ratio.