CH. IV.] 



GLYCINE. 



73 



at 45 to 50 C. Join this flask to another distilling 

 flask B, by a tight-fitting rubber stopper. Connect the 

 side neck, D, of this to an exhaust pump, and put the 

 pump in action. The screw clamp, C, is on a piece of 



Q 



Fig. 8. Distillation in vacua.* 



pressure tubing attached to a glass tube drawn to a fine 

 capillary that passes to the bottom of the flask. The 

 screw must be tightened until the bubbles of air pass 

 through the fluid at such a rate that they cannot quite 

 be counted. The flask B is cooled by means of a stream 

 of cold water, which passes on to it by means of a double 

 T-piece. In the absence of this it is advisable to place a 

 piece of filter paper on the flask to keep the stream of 

 water well spread. 



* For alternative method see p. 99. 



