C. L. Speyers — Molecular Weights of Liquids. 435 



The parabola-like curve shows how a changes with the tem- 

 perature for pairs of coexistent phases. The dotted Hues of I 

 and II connect the coexistent phases. The two X's of III are 

 not connected by a dotted line, because the values of the interme- 

 diate compositions and pressures are given by Konowalow. " He 

 points out that at the temperature to which this curve belongs, 

 which temperature is very close to the critical one, p' varies 

 very slightly with the composition for a range between 25 and 

 60 per cent grammolecules of anilin, whereas, according to 

 figure 1, this should only be so between the limits of 37 and 51 

 per cent. We account for this quite readily, by the increasing 

 value of a. Plot VI has been taken from a previous article.* 



The following table contains the other data from Konowalow. 



Jitrobenze: 



ae in methyl 



iodid. 



Nitrobenzene in a 



mrylene. 



£ = 18-1° 



p = 310-7mmHg 



t = 18-1° p = 391mmHg 



n 



p' 



a 



n 



P' 



a 



19-7 



260-5 



1-3 



16-5 



351-2 



1-7 



40 



210-7 



1-4 



32*3 



332-9 



2-7 



50 



185-4 



1-5 



41-6 



323-7 



3-3 



66-6 



137-1 



1-6 



59-9 



294*8 



4-6 



82 



79-5 



1-6 



66-6 



263-8 



4-1 









78-8 



207-9 



4-2 



Nitrobenzene in ether 









*=18\L 



5 p = 416mmHer 



Nitrobenzene in pentane. 



n 



P' 



a 



*=18*1° 



p =536 



"3mmHg 



16 



359 



1-2 



n 



P' 



a 



40-3 



294-6 



1-6 



5-9 



514-3 



1-5 



50*9 



2616 



1-8 



two layers 



504-0 





59*1 



232-3 



1-8 



78-2 



479-6 



30 



63-9 



215-7 



1-9 









66-6 



203-5 



1-9 









75 



166*3 



2-0 









76 



160-9 



2-0 









86-6 



98-7 



2-0 









92-5 



59-5 



21 









These data have been plotted in figure 3. The activity 

 factor of nitrobenzene is pretty constant in methyl iodid and 

 in ether, in amylene it increases considerably as the nitroben- 

 zene increases, while in pentane the increase is 20 times what 

 it was at the beginning. In this case, however, we have two 

 coexistent phases. Unfortunately, the compositions of the 

 coexistent phases are not given, only one composition before 

 the coexistent phases have formed and one after the coexistent 

 *Journ. Phys. Chem., ii, 347 (1898). 



