( 197 ) 



the opposite case two points for which v = b, come in its stead. 



For neither with an homogeneous double point, nor for an heteroge- 



/du\ fdv\ 



neous double point, — =0. And in the point in which — I = " 

 \*»J P l \ da! Jpl 



or ( — ) = 0, (see p. 185) — . has not a value which presents any 



\dvj dl 



particularity. 



The second form will differ from the one described here in so far 

 that the temperature at which the detaching of the longitudinal plait 

 takes place, is assumed to be equal to TV, (critical temperature of 

 the second component,. 



This may take place if the temperature at which — = disappears. 



is not only higher than 7*, , but also higher than TV, (a case to 

 which I alluded already before in these Contributions). 



Fig. 28. 

 Then the p, ^-projection is given by fig. 28. The highest tempera- 



ture which then occurs, is that at which 



d"ty 



disappears. 



That for the mixture helium and hydrogen the second shape of 



the plaitpoint line can occur, and that therefore T g can be > Tj„ 



follows immediately from the formula for the value of T g (These 



Proc. May 24, 1907) viz.: 



a, 4- a -, — 2a., 1 — w 



MRT, = 2 ' ' - x{l-x) ?-. 



b '(14-y)' 



For the case, namely, that a, and a„ may be neglected, and 

 &! <[ 6 S and x^>— , we find really T g > J/-,. Thus we find for 



a: = 0,4, which belongs to — — = 0,3704, MRT q > — -. For still 

 higher value of x, this value of T„ would be found still higher, but 



