... vodka!
On 1865, January 31 Dr. Mendeleev (creator of the periodic table) managed to convince humanity with his thesis for a doctor's degree on "Mixing alcohol with water", proving the optimal percentage of 40 as the maximum amount the be enjoyed without severe health effects. This day is marked as the day the vodka we know today first appeared on the public market.
Source (in Russian):
http://blogs.mail.ru/mail/nataxa13/1...C350469E0.html
Translator:
www.freetranslation.com