( 520 ) 

 For llie second term niijf of the hiiKHhil line we have : ^) 



mi — — (24) 



''s' 



so that the cnrve of contact and the l»inüdal line differ in the term y\ 

 We now write: 



A'i= %' -f mi,i/ + . . . 

 from which ensues: 



x,. — xi = [lur — mu) ?/' + (25) 



(hit of (25) it is evident, that the binodal line 1)0b' and the curve 

 of contact rOr' must have with respect to each other a position as 

 in fig-. 10. In this figure the part rO of the curve of contact has 

 l>een drawn outside, the part r'() inside the binodal line. 



If we calculate w^ith the help of (23j and (24) in,. — mi, we then 

 see that the sign of this difference depends on q, thus on the position 

 of P. It is therefore also i)0ssil)le that for ihi- same surface rO lies 

 inside and r' outside the iiinodal line. 

 The curve of contact : 



X = _ y^ + . . . 



and the spinodal line (11): 



Gci^j — (/,* , , 



X — — — y- J^ , . . 



differ already in the coefficient of i/'\ Hence for a plaitpoint of the 

 first kind the curve of contact will always fall as in fig. 10, just like 

 the binodal line, on the outer side of the spinodal line. 



As we have seen above the curve of contact consists of two 

 branches intersecting in the plaitpoint ; one is the branch rOr', 

 considered above, the other the l)ranch i\(J)\' . 



Fig. 11. Fig. 12. 



If in fig. 10 we restrict ourselves to that part of the lines repre- 

 senting stable conditions, we find fig. 11. Also the case represented. 



1) D, J. KORTEWEG, I.e. G9, 70. 



