Process used to separate the substances composing a mixture; it involves a
change of state, e.g., liquid to Gas, and subsequent condensation (see States Of Matter). A simple distillation apparatus consists of three parts: a flask in which
the mixture is Heated, a condenser in which the vapor is cooled, and a vessel in which the
condensed vapor, called distillate, is collected. Upon heating, the substances with a
higher Boiling Point remain in the flask and constitute the residue. When the substance with the
lowest boiling point has been removed, the temperature can be raised and the
process repeated with the substance having the next lowest boiling point. The
process of obtaining portions (or fractions) in this way is called fractional
distillation. In destructive distillation various solid (see States Of Matter) substances, such as wood, Coal, and oil shale, are heated out of free contact with Air, and the portions driven off are collected separately. Distillation is used
in refining Petroleum and in preparing alcoholic beverages.