Variation in the Pressure of Saturated Vapours. 71 



pressures, because the latter are small ; owing to this the 

 values obtained for x are irregular. But above 95° x in- 

 creases regularly. If # = then c = Ci ; unfortunately there 

 are no direct experimental data for c x . From equation (9), 



# = 4606-8, 

 whence 



r =4606-8 x ,-fo = 4=9-008. 



loo 



According to Berthelot the heat of vaporization of ethylene 

 bromide, under the atmospheric pressure, is equal to 43*78. 



2nd Method. 



The results obtained by this method also present a certain 

 irregularity. 



I here give several values. 



t 85° 90° 95° 100° 105° 



r 49-182 49-121 49-058 49-118 49-045 



0-061 0-063 -0-060 0-073 

 o-c l 0-0122 0-0126 -0-0120 00146* 



The difference c — c x is nearly zero, and the heat of vapori- 

 zation 49*058 like that given above. 



t. 



Pressures. 



t. 



Pressures. 



Calculated. 



Observed. 



Calculated. 



Observed. 







-20 .. , 



- 10 







30 



60 



0-85 



1-66 



315 



16-74 



65-87 



1-73 



2-48 



3-92 



17-20 



65-75 



o 



80 



110 .... 

 130 



160 



190 



144-24 

 400-90 



788-18 

 1607-7 

 3203-2 



144-02 

 401-08 



725-77 

 1572-5 

 5020-8 



15. 1st Method. 



Methyl Alcohol, CH 4 0. 



-10° 

 13-483 



100° 



2-7562 



15° 

 10-696 



105° 

 2-8201 



25° 30° 



9-6978 6-4699 



110° 115° 



2-6484 2-8616 



50° 

 4-1952 



120° 

 2-8190 



70° 

 3-3502 



95° 

 2-7869 



Notwithstanding certain irregularities there can be no 

 doubt but that x has a minimum value at 100°. 



** See Notes at end. 



