Properties of a Mixture of Liquids. 

 Temp. 20°. ir A = 301-78. tt b = 433-26. r= 



407 



79. 



?• 



p (calc). 



p (obs.). 



1 



425-9 



no obs. 



1-385 



417-8 



414 



2-936 



387-2 



387 



Temp. 30°. tt a =436-97. tt b = 636-33. r=-79. 

 q. p (calc). p (obs.). 



1 621-9 no obs. 



1-385 609-7 602 



2-936 563-7 560-9 



These are the only measurements of vapour-pressures, that 

 I have been able to find, sufficiently extensive to serve as a 

 test for the theory given above. In addition, there are the 

 measurements of F. D. Brown on the composition of the 

 distillate from a mixture of benzene and carbon disulphide ; 

 these were carried out by the ordinary method of fractiona- 

 tion at constant (atmospheric) pressure, and therefore at a 

 temperature varying from 47°*8 to 76°*9. To make use of 

 them, a diagram was drawn showing the relation between 

 log q (ratio of masses in liquid) and log t (ratio in vapour) 

 This was found to show a slight curvature, convex to the 

 axis of q, in accordance with the fact that the ratio of the 

 vapour-pressures of the pure substances (jr B / , 7r A ) decreases as 

 the temperature rises. The set of observations, however, 

 could be represented with fair approximation by the straight 

 line 



log tf =T48 + 0*9 logq. 



from this are derived the numbers in the third column below. 

 The table gives the reduced results of Brown's observations, 

 unlike those quoted from Wiillner and Regnault, which give 

 direct experimental numbers. 



Per cent. 



Do. in 



Do. in 







benzene in 



vapour 



vapour 



Log 7T B /7T A . 



Temperature. 



liquid. 



(obs.). 



(calc). 







95 



82-0 



810 



•4396 



76°2 



90 



694 



68-1 



•4474 



725 



85 



593 



59-0 



•4539 



69-4 



80 



51-3 



513 



•4591 



666 



70 



38-8 



39-3 



•4700 



62-2 



60 



29-3 



303 



•4779 



58-8 



50 



22-3 



23-2 



•4853 



55-7 



40 



171 



173 



•4920 



530 



30 



123 



12-3 



•4972 



509 



20 



82 



8-0 



•5016 



492 



10 



41 



41 



•5053 



47-8 



