VAPORIZATION, 



53 



Elasticity-of steam 



takingatmospheric 



pressure as unity. 



1 



U 



2 



Temp. Fahr. 



212.0 



233.96 



250.52 



2 4 263.84 



3 275.18 

 34 285.08 



4 293.72 

 "44 300.28 



5 307.5 

 54 314.24 



6 320.36 

 64 326.26 



7 331.70 

 74 336.86 



8 341.78 



9 350.78 



10 - 358.88 



1 1 366.85 



12 374.00 



Some curious experiments were made by M. Cagnard de 

 la Tour on the vapour from various liquids at very high tempera- 

 tures, and under great pressures. He filled a small glass tube in 

 part with ether, alcohol, or water, and sealed it hermetically. 

 The tube was then exposed to heat, till the liquid passed en- 

 tirely into vapour. Ether became gaseous in a space scarcely 

 double its volume at a temperature of 320, and the vapour 

 exerted a pressure of no more than 38 atmospheres. Alcohol 

 became gaseous in a space about thrice its volume at the tem- 

 perature 4044> with a pressure of about 139 atmospheres. 

 Water acted chemically on the glass, and broke it ; but adding a 

 little carbonate of soda to it, the water became gaseous in a 

 space four times its volume at the temperature at which zinc 

 melts, or about 648. These results are singular, in so far as 

 the pressure or elastic force of the vapours proves to be much 

 smaller than that which corresponds with their calculated 

 density. It thus appears that highly compressed vapours lose 

 a portion of their elasticity, or yield more to a certain pressure 

 than air 5 by calculation, would do. 



