( J68 ) 



Here Ü and S coincide with the summit of the curve —- = O, and 



0,/; - 



SO also F and R with C. The parts with the cusps liave now 



disai)peared once for all through the eutectic point. 



Tiie i)oints a\' , .i\' and ,??/ coincide Avitli the horizontal tangentin 



the point of i?iffe.riou Q,S. This point ^2,^ lies apparently at ,r' = i, 



0'"-' 

 as the curve — ^ =: or T = (/^iS'.v (^ — -''') i« perfectly symiuctrical 



on either side of the sunnnit at d' = ^ according to our supposition 

 «/ =z «/ (in consequence of />/ = />/). 



Not before this instant we may say that the meltingpoint curve 

 has obtained a perfectly normal course, running continuously without 

 any cusp from A to B with a mininnnn in D where ,v = x' (fig. 16). The 

 point of inflexion with a horizontal tangent has passed into an ordinary 

 [)oint of inflexion with an oblique tangent. This point of inflexion also 

 will gradually disappear when ,i' continues to diminish, and for still 

 smaller values the mininuun also will disappear from the melting- 

 point line which will then show a continuously ascending course from 

 B to A. It is of course ])0ssible that the miiiimuni has disappeared 

 already before, of which tig. l^h gives an example. 



The transition of lig. 15 is determined l)y the equations (G) for 



'd%' 1 



.r' Lv' = ,r' = ./■ ') = i, in connection with —- = or T =^ - a ^. 



We find: 



/3' = 0,822G ; x = 0.8030 ; T = 402°,6 . (,i;/ = .vj = a;,' = 0,5). 



The points .r/ and .r, may further be calculated from equation (6). 



(?). The mininnnn disappears apparently (see III equation (5/>^s-), 



when 



T —T 



i^'<-V^- (14) 



^'■2 — ^\ 



For with ,^ = formula (5 ^^.s) passes into — /5' < — 



-^ 1 



T T 



Qy ^j' ^ _J ^. This formula expresses the condition for the occur- 



rence of a minimum. P'ormula (14) expresses consequently that no 

 minimum wdll occur. 



The minimum disappears therefore in our case as soon as [i' 



7 

 becomes equal to — or 0,5823 . 



ƒ. In the above considerations we have lost sight of the rudi- 

 mentary pieces which huxe been detached (compare VI). 



