Variation in the Pressure of Saturated Vapours. 73 



Acetone, C 3 H 6 0. 

 16. 1st Method. 



t 25° 30° 55° 60° 65° 



x 3-819 3-426 2-6888 2-1175 2S053 



t 70° 75° 80° 85° 90° 



x 2-2440 2-4341 2-4075 3*1974 3-1758 



t 95° 125° 



x 3-3307 4-7688 



Although there is an irregularity in this series of #'s, still 

 it is evident that x has a minimum value between 60° and 70° ; 

 I take 65°, and the arithmetical mean of three values of x 

 answering to the temperatures 60°, 65°, and 70 c . In this 

 manner I find 



#=2-2227, 

 whence 



c-d = 2*2227 x ^=0*076645. 



According to Regnault c= 0*5580 and <?! -=0*4125 ; 

 hence 0—^=0*1455. 



Determining q from c and x we find that ^ = 0*4814, and 

 the difference between this value and that given by experi- 

 ment, 0*4125, may be referred to errors in the calorimetric 

 observations. 



According to equation (9), 



#=3690*37; 

 hence 



r =yx ^=127*25. 



According to Regnault's formula, r 65 = 127*54. 

 2nd Method. 



t. 



2>- 



dp 

 dt' 



t. 



V- 



dp 

 dt' 



o 



50 



608-86 



725-95 



860-48 



1014-32 



28-774 

 32-825 



o 



70 



1189-38 

 1387-62 

 1611-05 



37-264 



55 



75 



60 



80 



65 







t 60° 65° 70° 



r 127-87 12748 127'10 



0-39 0-38 



c-c x 0078 0-076 



