THE LIQUEFACTION OF GASES 67 



object through 250"" of the 273° which separates 

 the freezing-point of water from the absolute 

 zero has taxed the skill of experimenters for 

 several generations. Temperatures, as already 

 pointed out, are more justly compared by con- 

 sidering their ratio on the absolute scale than by 

 considering the number of degrees Centigrade or 

 Fahrenheit which separate them. 



