( 826 ) 



Physics. - " Contriüution to the theory of binary mixtures*" III. 

 by Prof. J. L). van dkr Waals. 



Continued, see page 727. 



We shall now proceed to describe the course of the spinodal 

 curve and the place of the plait points when choosing regions of 

 fig. 1 which lie more to the right. But it has appeared from what 

 precedes that to decide what different cases may occur, we must 



know the relative position of the curves = O and — — = 0, to 



»/./•'-' dv* 



</> 

 which now the curve =0 is added; so the relative position at 



different temperatures of the three curves which occur in the equation 



of the spinodal curve. 



The curves — = and = may be considered as sufficiently 



dv dasdv 



known, and the knowledge of the relative position of these curves 



with regard to each other enabled us already before to elucidate 



sufficiently the critical phenomena of mixtures with minimum critical 



temperature - and though with regard to the relative position of 



these lines some particularities are met with, which have not expressly 



been set forth, I shall assume the properties of these lines to be 



known. But the curve - - = is less known - and it has appeared 



da? 



from the foregoing remarks, that if we wish to understand the occur- 

 rence of complex plaits, the relative position of this curve with 



</> 

 respect to the curve = must be known. If this line lies alto- 



gether within the region where is negative, it has no influence 



dv* 



to speak of on the course of the spinodal line, but if it lies either 



partially or entirely outside this region, the influence on the course 



of the spinodal curve is great, and the existence of this curve accounts 



for the complexity of the plait and gives rise to the phenomena of 



non-miscibility . 1 have, therefore, thought it advisable to investigate 



d*ti) 



the properties of the curve = 0, before proceeding to the descrip- 



d.v* 



tion of the course of the spinodal curve also in other regions of 



tig. 1. A perfectly exact investigation of this line would, of course, 



require a perfectly accurate knowledge 'of the equation of state. But 



