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



c x has not been measured, but it can be found from the pre- 

 ceding : c 1 = , 0764. 

 From equation (9), 



y = 7962, 

 hence 



r = 7962x^=248*8. 



According to Personne, at 316° the heat of vaporization 

 of sulphur is 362*0. To render these data comparable they 

 must be brought to one temperature. Being unable to do 

 this accurately, we will calculate it approximately by sub- 

 tracting the product of 0-15817 x (550-316) from 362, 

 which gives 37'0. Thus we have 



r 650 = 325*0. 

 2nd Method. 



t. 



p. 



dp 

 dt' 



t. 



fr 



dp 

 dt' 



520 



2133-30 





550 .*.... 



3086-51 



36-283 



530 



2421-97 





560 



3465-33 



39-505 



540 , 



2739-21 



33-203 



570 .., 



3877-08 





The first two differential coefficients are the arithmetical 



means of two almost similar numbers; but the third coefficient, 



in the absence of data for the vapour-pressure at 580°, is a 



single value. 



t 540° 550° 560° 



r 25037 248-82 247-09 



1-55 1-73 



c-c x 0-155 0173 



The arithmetical mean for c — Ci is 0-164. Neither this 

 value nor that of r differ from those determined above. 



t. 



Pressures. 



t. 



Pressures. 



Calculated. 



Observed. 



Calculated. 



Observed. 



390 



450 



500 



530 



263-20 

 774-59 

 1634-2 

 2421*7 



272-31 

 779-89 

 1635-3 

 2422*0 



540 



560 



570 



2739-3 

 3464-9 

 3877-0 



2739-2 

 3465-3 

 3877-1 



