DISTILLATION

the conversion of substances into vapors, afterwards condensed into liquid form, is employed to separate and purify liquids, especially organic liquids. Heat converts liquids into vapor; cold converts vapors into liquid. These two proce es constitute d. Solid particles, being inconvertible into vapor, are left behind. Liquids have distinct boiling-points at which they pa into vapor, so liquid-impurities of lower boiling-point can be condensed and collected first, while those of higher boiling-point than the required liquid are left behind. The nece ary apparatus consists of a distilling flask and a condenser. The d. flask has a long neck and along, narrow side-tube. In the neck is a cork fitted with a thermometer, the bulb of which comes just below the side-tube and records the temperature of the vapor. The condenser is a gla tube with a gla or metal jacket with entrance and exit tubes through which cold water runs continuously. A cork bearing the side-tube from the d. flask fits into one end, while the other end dips into a coll. The d. flask is ‘heated, and when the thermometer records that the vapor is pa ing through the side-tube into the condenser at the boiling-point of the required liquid, a fresh collecting flask is connected.