( 191 ) 



At the pressure of 61,5 atms. the melting-point line runs strongly 

 to the right, because lo^f is pretty strongly negative here. 



Finally it is still worthy of note that there are two pi'essures for 

 which the melting-point line presents another, not yet mentioned, 

 peculiarity ; they are the pressures of the two critical end-points 

 /> and q. 



The melting-point line corresponding to the pressure of the first 

 critical end-point p (39,7 atms.) touches the continuous liquid-vapour 

 branch of the tirst part of the three-phase region in p, and the melting- 

 point line for the pressure of the second critical end-point (/ (62 alms.) 

 touches the continuous liquid-vapour line of the second part of the 



0, from which it 



three-phase region in q. In these points — ^ 



follows that the melting-point line must possess an horizontal tangent 

 thei-e, whicli van dkr Waai.s Sr. M already pointed out. So the 

 melting-point line at the pressure of the critical end-point p not only 

 possesses two vertical tangents, but moreovei' a point of inflection 

 wilh horizontal tangent. 



The melting-point line at the pressure of the second critical end- 

 point q, however, only possesses a point of inflection with horizontal 



1) These Pioc. June 1905, p. 193. 



13^ 



