70 K. D. Kraevitch on an Approximate Law of the 



The values of c—Ci proved to be not quite similar to each 

 other, or to the figure found by the 1st method, probably 

 because the vapour-pressures, taken at rather low tempera- 

 tures, are small and the errors they contain have a great 

 influence on the calculation. The value of r , 52*063, 

 however, is similar to the former value. 



t. 



Pressures. 



t. 



Pressures. 



Calcu- 

 lated. 



Ob- 

 served. 





Calcu- 

 lated. 



Ob- 

 served. 









-20 



9-76 



9-80 



9-79 



o 



40 



214-12 



214-18 



214-63 



-10 



18-43 



18-47 



18-47 



60 



442-87 



447-43 



445-61 







32-94 



32-95 



32-95 



100 



1404-8 



1467-1 



14290 



20 



90-97 



90-99 



9100 



140... 



3316-9 



3709-0 



3421-1 



30, 



142-08 



142-27 



142-24 



190 



7269-6 



93990 



7647-3 



In order to verify the results, I repeated the calculations 

 by the 1st method through intervals of 10°, between 10° and 

 40°. 



t -10° 



x 6-0955 



0° 10° 



6-2747 6-3953 



20° 

 6-1217 



30° 

 60431 



40° 

 5-6925 



This table removes all doubt as to x attaining a maximum 

 at 10°, hence 



c-cx= 6-3953 x^ =0-08305. 

 154 



which is somewhat different from that found above, 0*08942. 

 The same value is obtained for y as before, 4061*2. The 

 vapour-pressures calculated from these data are given in the 

 fourth column. 



Ethylene Bromide, C 2 H 4 Br 2 . 

 14. 1st Method. 



In the case of ethylene bromide the calculations presented 

 great irregularities, with which it was exceedingly difficult to 

 deal. By means of numerous attempts and recalculations, I 

 came to the conclusion that x has a minimum value of nearly 

 zero, at 95°. The pressure at this point is equal to 245*51. 

 Below this temperature, the errors contained in the vapour- 

 pressures are probably considerable compared to the true 



