CHEMICAL THEORY OF SOLUTIONS. PART I. 69 



The molar fractions of the three chemical sjoecies under the 



heading " direct " have been calculated more directly from the 

 data of CuNAEUS by means of the following equations, 



(y^ (l-x')P 



185.6 

 x' P 



160 



The empirical molar fraction of the gas phase has been 

 calculated as follows : 



Po:+P 



the calculated partial pressures being employed. 



It is quite probable that the other value for the vapour 

 pressure of the pure chemical sj^ecies GiH^O, that is -^ = 162, 

 is more in accordance with the facts. But the exact determina- 

 tion of tangents from curves being very difficult, better agreement 

 could hardly be expected. At any rate the foregoing is quite 

 enough to demonstrate that our theory is not a purely hypothe- 

 tical construction which corresponds to no reality. 



(3) Boiling Point imder Constant Pressure. 



Here we may proceed as in § 2 (c) of the preceding chapter. 

 In equation (44) 



C\ TZy^ + Co,7To,+ G P,^ = P 



we have now to consider P as constant, and the molar fractions 

 as well as the vapour tensions of the pure chemical species as 

 functions of temperature. Cx etc. can be expressed as explicit 



