Variation in the .Pressure of Saturated Vapours. 77 



t. 



Pressures. 



t, 



Pressures. 



Calculated. 



Observed. 



Calculated. 



Observed. 



o 



-20 .... 







20 ,,, 

 30 



192-39 

 466-65 

 996-31 

 13990 



187-55 

 465-18 

 996-23 

 1399-0 







40 



1919-6 

 25795 

 4407-4 

 8771-3 



19196 

 2579-4 

 44050 



8722-8 



1 



50 



70 



100 





Ethyl Bromide, C 2 H 5 Br. 



19. 



t 



X . 



1st Method. 



15° 

 3-780 



25° 

 2-637 



60° 

 1-6066 



35° 

 1-986 



65° 

 1-6199 



45° 



1-7282 



70° 

 1-7383 



50° 

 1-5200 



t . 



55° 

 1-A695 



75° 

 1-7615 



x has a minimum value at 55° which is equal to 1*4695. 

 Hence 



c-d=l-4695 x taI^ = 0-027017. 



According to Regnault c= 0*2153, and according to Wiede- 

 mann q = 0*1 744 ; hence c— c r = 0*0409. 



Conversely, assuming c=0*2153 and 0—^=0*0270, we find 

 c x = 0*1983 instead of 0*1744 obtained by experiments. 

 Further we have 



#=3296*47, 



r = 3296*47 x j^^ = 60*608. 



According to Berthelot the heat of vaporization under the 

 atmospheric pressure is 61*65; there do not exist any obser- 

 vations for other pressures. 



2nd Method. 



t. 



P> 



dp 

 di' 



t 



i>- 



dp 

 dt' 



o 



40 



801-92 



947-28 



1112-79 



1300-35 



35243 

 39-848 



o 



60 



1511-92 

 1749-47 

 2015-06 



44-843 



45 



65 



50 



70 



55 







