MODIFIED METHODS OF ANALYSIS. 27 



Distilling flask. Comparable results can only be obtained in 

 distillation by always using flasks of the same dimensions. The flask 

 found most satisfactory in this work is an ordinary 300 cc flask, 

 8 cm in diameter, with the side tube 8 cm from the main bulb, and 

 the neck extending 8 cm above the side tube. The neck is 2 cm in 

 diameter and the side tube is 5 mm. 



Manometer. An open manometer with a movable scale graduated 

 in millimeters, and provided with double connections, must also be 

 provided. 



FIG. 1. Apparatus for the fractional distillation of turpentine. 



Pressure regulator. This consists of a glass tube about 1 inch in 

 diameter and about 24 inches long, fused at one end, nearly filled 

 with water, and stoppered with a two-hole stopper, carrying two 

 glass tubes, one of which extends to the bottom of the large tube, 

 the other being free to move up or down. 



Condenser and receivers. An ordinary condenser is connected with 

 three stoppered, graduated cylinders, by means of two-way stopcocks, 

 care being taken to insure close connection and the exposure of a 

 minimum length of tubing to the turpentine. The stopper of each 

 cylinder is provided with a stopcock connection with an air chamber, 



