304 



A. W. Witkowski on the 



— 140°, —145° (liquid ethylene boiling under reduced 

 pressure). 



The arrangement of the thermostat in which liquid ethy- 

 lene has been boiled under reduced pressure is represented in 

 tig. 3. A tali cylindrical glass vessel A, standing on a horizontal 



Tbimp 



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brass plate, is covered with another brass plate PP, the dia- 

 meter of which is somewhat larger than the diameter of the 

 upper flat edge of the glass vessel. By means of three brass 

 pillars, fastened to the lower plate, and screw-heads pressing 



