60 AET. 10.— K. IKEDA : STUDIES ON THE 



evaluate tlie characteristic magnitudes of the system such as 

 7t^, Tvo,, and ^. According to equations (5) and (37) r.^ can be 

 found by producing the tangent at a; = to tlie curve of 79« so 

 as to meet the pressure axis at a; = 1. The height of the point 

 of intersection is equal to tt^. 



From the value of p^ at a; = 1 the molar fraction of ©a in 

 the pure associated component can be determined, and then 7rp 

 can be calculated from pr^ at x = 1. 



V can also be determined from the tangent of the ano-le, 

 which the curve of p makes with the x axis at x — \. From 

 equation (5) and (43) we have 



(^),= ^«(4^)=-!^+("-i)(^'".).}P. 



Hence ç, the degree of association of the pure associated com- 

 ponent, is given by 



/^\ 

 V dx j\ , 



ç = l + (v-l)(q,), = 



■^ 



and for v we have 



iip\ 



CtOb J I -| 



^" +1 (45) 



(^ß)i 



When V is thus determined S\ can be calculated from equation 

 (32), and we are now in a position to give a quantitative account 

 not only of the vapour pressures, total and partial, of the whole 

 system, but also of the state of chemical equilibrium in the 

 homogeneous solution, liquid as well as gaseous. 



As the measurement of the partial pressures, or molar frac- 

 tions ill the gas phase, is rather troublesome, it often happens 

 that the curve of the total pressure alone is determined. Even 



