( •^>^> ) 



when they, according to the inaccurate interpretation of the osmotic 

 pressnre, could move free and undisturbed throughout the space of 

 the solution. 



VAN DER Waals' equation of state, viz. 



ET a 



gives for the rarefied gas-state: 



_RT 



V a : RT 



V — b V 



RTf b a:RT 



V \ V V 



when we again content ourselves with terms of the degree - 



Let us nov^ write: 



then 



a 

 Rf~^~'^' 



V \ V J 



where v now represents the volume, in which 1 Gr. mol. of the 

 dissolved substance moves. This volume is however evidently (cf. 

 also ^4): 



1001,4 + 190 c 



or 



1001,4 



^(1 + 0,19 c), 



so that we get : 



1001,4 (1 + 0,1 9 c) V 1001,4 (1 + 0,19 c)) ' 



RT y 



or as 77^7:7- = 23,87 is (cf. § 4), and with y' = ^ 



1001,4 ' V • • ^ /' - f ~ 1001,4' 



, = 23,87 c^^-^^^..., ...... (3) 



and this is an altogether ditferent expression from (2'^). Not oidy is 

 v^ replaced by v (which gives rise to the factor 1 -j- 0,19 c), but 

 we also find 1 — y' c instead of 1 — 0,01 5 c. In this y' is different 

 for every dissolved substance, dependent on the values of a and b, 

 whereas the coefTicient 0,015 has the same value for all substances 

 dissolved in water, independent of the nature of the dissolved substance 

 (cf. ^ 4). Also the coefficient 0,19 depends on the dissolved substance 

 on its molecular volume). Moreover y' depends also on I'on account 



