( 181 ) 



The following cluiiige which now will lake place coiisisis in the 

 quantity ivig passing through zero, l>ecause llie point (>' will have 



T 



F'm. L 



to pass the point whei-e the vapour branch of the border-lino has 

 its maximum pressure. 



So beyond this point all the quantities of the fraction which then 

 govern the vapour line, are positive, so 



+ + + + 



7 — -^ — r^ ^ — • (8) 



{Xs X„) VI,, — {,Vl — Xn) Vsf 



+ + + -f 



but the sign of numerator and denominator is negative, because the 

 Second member of the numerator and the second member of the 

 denominator predominate, and this remains the same up to the 

 critical end-point p, so that in the point where G and K have 

 coincided : 



dT ^ 

 So the vapour-line of the tirst part of the three-phase region need 

 not possess a vertical tangent. 



If we now proceed to the vapour branch of the second part of 

 the three-phase region, it is iioteworthy that the order in wdiich the 

 quantities iCsf and luig become zero in the })oint (t is the reversed 

 one of that which exists for the vapour branch of the tirst [)art of 

 the three-phase region. Even by a graphical way it is easy to see that 

 now tirst wi,, and then ?y,/- jiasses througli zero. 



It is further worthy of note that in the critical end-point 



dT 



T 



SLG 



dT 



^JJx 



'■<•/■ 



d]p 



When now, as for ether-anthracpiinone, — - of the three-|)hase line 



dT 



is negative in q, it appears from the above relation that, ■?;,ƒ undoubt- 



