125 



-4 



15 



20 MIN. 



O 5 10 



Fig. 7. The double freezing point as observed by various authors. For 

 the sake of comparison, all the curves have been plotted to the same scale. 

 (From Luyet and Gehenio, 1937.) 



(Curve 6, Fig. 7). They used potato tissue in the form of 

 hollow cylinders slipped about the bulb of a mercury ther- 

 mometer. In order to control the cooling velocity and the 



