( 198 ) 



if a, -f- « s — 2a„ becomes appreciably smaller than a,, this may, of 

 course, be different. In this case the plait remains a complex plait 



d'xp 



and 



far as 



dx' ~ 



T= 7ït, . At, this value of T has = disappeared 



do' 



still exists. So above TV, the complex plait is to be 



considered as a longitudinal plait. 



If in the case described above we have a plaitpoint line that pro- 

 ceeds continuously in the tv-plane, .starting on the lefthand side in 

 the critical point of the first component, and terminating in the critical 

 point of the second component, though a maximum value of x, and 

 then also a minimum value may be possible, still another case is 

 possible, and most likely this case is met with in the mixture water 

 and phenol. Of course the first mentioned line, which starts and 

 terminates in the critical point of the components, must continue to 

 exist, if we continue to assume that the plait remains closed on the 

 side of the limiting volumes. Else it splits up into 2 parts, which I, 

 however, consider as two parts of one and the same branch of the 

 plaitpoint curve. If another branch is possible, it must be a separate 

 closed carve — which, however, if the plait is supposed open on 

 the side of the limiting volumes, may be considered as starting in 

 a point of the line v = b, and terminating in another point of this 

 line. We meet with this case when the longitudinal plait detaches 

 itself at a temperature which is lower than 7t, and T^. As has 

 been described above, the longitudinal plait will have quite retreated 

 to volumes smaller than those of the liquid branch of the binodal line 

 of the transverse plait at a certain value of T higher than the tem- 

 perature of detaching. Then the three phase pressure no longer exists, 

 and the first mentioned branch of the plaitpoint line, which joins the 

 critical points of the components, has its simplest shape. In fig. 29 



Fig. 29. 



