( 832 ) 



which equation shows that it consists of two straight lines, which 



dp 



join the point x = and v = with the points for which = 



for the second component. At temperatures which are not too far 



below (Tk)n, the locus = lies, therefore, entirely outside the 



dx* 



curve - - = 0, and is then restricted to the left side of the figure. 



oV 



2 nd . As second limiting case we take b l = b s , but a 1 differing from a a . 



ti UPT cPax(l-.v) 1 2(q 1 + q a -2 t f l a | 

 Then MRl n = - — — , and because x = - M A 1 ,, = — ~n — , 



* dx* b 2 J 46 



whereas MRTk is equal to — - ' for x= 1 / i . Then, too, 



27 

 T 7 may be larger than r J\ viz. when — ('?i-f-^ s — 2a la )X</ 1 4-tf s +2a 18 ) 



23 

 or if 2a ls < — (^ -f- a,). But oven if 7', should be < 71-, this implies 



O 1 



by no means that shortlv before its disappearance the locus — — 



1 l dv* 



d'y 

 lies in the region in which is negative, Lne previously calculated 



dv* 



v — b 

 values of —r— show that this disappearance takes place at a ver y small 



volume, which may be smaller, and in the limiting case will certainly 



be smaller than the liquid volumes of the curve — — = 0. To ascer- 



dv* 



tain whether the disappearance of -— - = takes place in the region 



in which is negative, we may substitute the value of T q , x g and 



dv* 



d'lb 



v g in the form for , and examine the conditions on which this 



dv* 



d> (1— 2x q y „ , 



value of becomes negative. If we write for -—— = y g , then : 



aV 4# g (l—wg) 



^rT>rv d*ax n {l — x q ) l — y q v g —b g 2y q v q l + y >7 



jMtilq = , — > — — 



oV b q (l+y 9 Y b q l—y g b g l- y q 

 and 



fd*y\ MRT g 2a 



\dv' ) 9 (Vp — bgY Vg % 



