DEWAR VESSEL n.
A double-walled glass vessel for holding liquid air, etc., having the space between the walls exhausted so as to prevent conduction of heat, and sometimes having the glass silvered to prevent absorption of radiant heat; -- called also, according to the particular shape, Dewar bulb, Dewar tube, etc.
DISTILLATION n.
rom the more fixed; specifically, the operation of driving off gas or vapor from volatile liquids or solids, by heat in a retort or still, and the condensation of the products as far as possible by a cool receiver, alembic, or condenser; rectification; vaporization; condensation; as, the distillation of illuminating ga…