Professor Preobrazhensky from a novel "Heartof a Dog" advised to bite a hot meal after vodka. For example, a thick borshch (beetroot soup) or a good portion of meat, in order not to wake up in a salad. It's time to consider this wise advice, as January 31 is the birthday of Russian vodka.
Of course, the holiday is unofficial. On this day in 1865 Dmitri Mendeleev defended his famous PhD thesis "On the combinations of water with alcohol". The purpose of this work was to study the specific weight (density) of ethanol solutions in water at different temperatures and in different concentrations. However, Mendeleev did not invent a 40-degree beverage; he even did not use the word "vodka".
So, where this magic number of degrees — 40 is coming from? Turns out, it comes from the old method of determining the content of alcohol in the beverage –the annealing. Annealing is a simple process: a bread wine (formerly known grain spirits) was pouredin the bucket and burned up. It was considered a standard when about half of the liquidevaporates. This was called a polugar. This occurs if the alcohol volume is about 40%. By the way, the proof of vodka in Russia was not strictly standardized. Traditionally different sorts: 38, 45 and even 56 degrees were produced.