DISTILLATION, process of heating a liquid until its more volatile constituents
pass into the vapor phase, and then cooling the vapor to recover such
constituents in liquid form by condensation


            The main purpose of distillation is
to separate or to purification of a
large variety of materials mixture by taking advantage of their
different volatilities or the separation of volatile materials from nonvolatile
materials.


Seawater, for example, which contains about 4 percent
dissolved solids (principally common salt), may be readily purified by
vaporizing the water, condensing the steam thus formed, and collecting the
product, distilled water.


            If the boiling points of the
constituents of a mixture differ only slightly, complete separation cannot be
achieved in a single distillation.


An important example is the separation of water, which
boils at 100° C (212° F), and alcohol, which boils at 78.5° C (173° F). If a
mixture of these two liquids is boiled, the vapor that rises is richer in
alcohol and poorer in water than the liquid from which it came, but it is not
pure alcohol.


Distillation is a process
of separating the
component substances from a liquid mixture by selective vaporization and condensation.