Page:Outlines of Physical Chemistry - 1899.djvu/138

 118 OUTLINES OF PHYSICAL CHEMISTRY

Landsberger's Method The apparatus resembles that used for a steam distilla- tion and is shown in fig. 27. The vapour from c, which passes through a, does not pass off at b until it has come through the small opening a and filled the space between a and b. 1 The boiling point of the solvent is determined as follows : In the tube a is placed such a quantity of the liquid that at the end of the experiment the bulb of the thermometer will be well immersed (7 c.c. of ether or carbon disulphide, 4 c.c. of chloro- form or acetone, 5 c.c. of alcohol, 7 c.c. of water, c.c. of benzene). A sufficient quantity (250 c.c.) of the same liquid is put into the flask c. The connections are all made and a Liebig ^ condenser is fitted on to b, then the liquid in c is boiled and 'the flame so regulated that the vapour at first condenses in a, and afterwards raises the liquid in a to its boiling point. After a few (2 to 6) minutes the temperature becomes quite constant, and the Fla - 29 boiling point of the solvent

may be noted. The method adopted for obtaining the boiling points of a series of solutions is the following : The tube a is dried and weighed {correct to centigrams) ; a then a weighed quantity of the substance and a convenient quantity of the solvent are introduced. The boiling point is then determined just

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