(551 ) 
of components. For a simple substance a phasis is stable. as long as 
For a binary mixture the following condition must be satisfied : 
Ou ey 
de? 
for a ternary mixture the following condition must be satisfied : 
aA ate ews 3 agit at ay \2 
dw 5) dw (=) dw Jr a (sa) 
de? ty due yp “ue Oy dp oy 
Ou? Oy? dady da? dy? 
The transition of the stable and unstable phases takes therefore 
place at 
ea (oh 
dw dw dz dv dw pe dy ov 
POT Pe POT 7 
dz? dy” 
and 
EE 
du? * dado’ dydv 
dvdw’ da?’ dyde 
dvdy * dxdy’ dy? 
What the spinodal curve is for the binary mixture (see fig. 2 
the curve CEPE'C’) the surface represented by (6) is for the ternary 
mixture, viz. the limit between the stable and unstable phases. In 
the sides of the prism described on the triangle ory, this surface 
must therefore pass through the spinodal curves of the pairs of 
which the ternary system is composed. So we find from equation (6) 
which may be written: 
37 
Proceedings Royal Acad. Amsterdam. Vol. IV, 
