( 16:5 ) 



If once more tlie case that two connodal lines intersect is examined, 

 it is easily seen, that the two intersection-points are nodes of the 

 longitudinal plait (second plait). When the temperature rises they 

 approach each other, and when the curves touch, the point of contact 

 may be considered as two nodes having fallen together. From this 

 follows, that when two connodal curves touch, the point of contact is 

 a plait-point of the longitudinal plait (second plait). The spinodal 

 curve of the longitudinal plait will therefore also touch the spinodal 

 curve of the transverse plait (first plait). A consequence of this is, 



. dp 



that the differential coefficient — (see T. M. p. 15) must be in 



this case which points to a maximum or minimum of the line 

 p=:/i(a-i), that is the curve, which represents the relation between 

 the composition and the pressure of the saturated vapour of the 

 mixture. 



To test this conclusion experimentally, some pressures of vapour 

 were measured according to the method denoted by Leiifeldt 

 (rhil. Mag. July 1898), the results follow: 



