Beckmann

Method of. A method for the determination of the depre ion of the freezing-point. A hard gla tube, from 2 to 3 cm. in diameter, with a lateral projection, is filled with from 15 to 20 grams of the solvent (weighed out accurately in centigrams), and closed with a cork in which are placed an accurate thermometer and a stout platinum wire serving as a stirring rod. The lower part of the tube is attached by means of a cork to a somewhat larger, wider tube, which serves as an air-jacket. The entire apparatus projects into a beaker-gla filled with a freezing-mixture. Cold water will answer for glacial acetic acid and ice water for benzene. The congealing-point of the solvent is determined by cooling this to from 1° to 2° below its freezing-point; then by agitation with the platinum rod (after addition of platinum dippings) the formation of crystals is induced. The thermometer rises. When the mercury becomes stationary, the reading indicates the freezing-point of the solvent. The ma is allowed to melt and an accurately weighed amount of substance is introduced through the lateral projection. When this has di olved, the freezing-point is determined as before.