The boiling point of a 50-50 mixture, for example, would be halfway between the boiling points of the pure substances, and the degree of separation produced by a single distillation would depend only on each substance's readiness to vaporize at this temperature. This simple law was first stated by 19th-century French chemist Fran ois Marie Raoult. Distilled alcoholic beverages are possible due to the different boiling points of the two primary ingredients in the original mixture i.e. water and ethyl alcohol. This differential makes it possible to boil out the alcohol from a beverage such as wine, mead, or beer while leaving the water and other substances behind. The alcohol, on boiling, is captured and recondensed into a liquid of considerably higher alcoholic concentrations.
Distillation separates substances based on their volatility.
Two substances, such as water and ethyl alcohol, can only be separated if their boiling points differ by at least 1 degree Celsius. If their boiling points are too similar then the vaporized molecules will remain attached as they rise. The simplest still is a pressurized system containing a heat source, a tank to hold liquids, a hood or gooseneck tube to collect vapors, and a condenser, or container, where the vapor is turned into liquid. Distillation, though, appears hundreds of years earlier in the historical records of various geographical localities. Distilled beverages may date as far back as 800 BC in China with a distillate of Sake.