( I7:i ) 



lil llio second t'iise, fig. '2, 1 siipposcd the suliibililj- ut" li in .1, 

 even at (lie ci-ilieai leinperalui-e of .1, to he still so small, lliat jnsi 

 a little above it the line cd interseets Ihe criUcal curve. Then such 

 an intersection takes place in two ])oinls ^> and ry. 



Now the critical teinperatures and [iressnres between a and //and 

 between (/ and h refer (o unsdluiuiU'd sobilions. At [i and r/, however 

 where the p, Mine of the solutions and vapours saturated of solid B 

 and the critical curve meet, the case occurs, when the saturated 

 solution is found at its critical teni[)eralure ; for here the vapour- 

 tension of the saturated solution is (piite equal to the critical pres- 

 sure and so .mtitration teiujx'i'idiu-c diul crUlail ti'iiipri'dtnfe naist 

 coincide. 



If we were to prolong the critical curve from ji to q, we should 

 jiass through the region of solutions and \ai)ouis stijtermturated of 

 solid B. Hence critical })lienomena will be possible here only provided 

 that the solid phase B does not occur. So this part of the criiical 

 curve is inetastahle. 



To prolong the three-phases-line between p and <i, on the other 

 hand, is impossible, as will soon l)e evident. 



A third case forming a transition between tig. 1 and 2 would be 

 the following: the curve cd would touch the inside of (he critical 

 curve in one point. The points [> and q would coincide at this point. 

 Hence the chance that such a case should occur is extremely small. 



A better insight than by the p, /-projections of the representation 

 in space is, however, given by the p, ,7>projections, especially when 

 these are combined for different temperatures as in fig. 8 and 4, 

 Avhicli has alread)^ been indicated by Prof. Bakjiuis Roozkboom ^). 

 That is why I here add />, ./-projections both for case 1 and for 

 case 2 and in order to be able to construct from (hese projecdons 

 the entire t, ,r-diagranis also, I have given the projections starting 

 from the critical temperature of A up to the melting point of B. 



The preceding yAt'-diagrams 3 and 4 corresj)ond with the />, /-dia- 

 grams 1 and 2. Let us first confine ourselves to tig. 3. At the 

 critical temperature / of the substance A, ae and <ic are the yy,,/> 

 curves for coexisting vapours and litpuds (unsaturated solutions). 

 The [)oints c and e indicate die satui-aU'd solution and the va])our 

 in equilibrium with it. Further for the same tenqierature </ c is tlie 

 />, ,t'-curve for the raj/onrs and cf the y>, ./-curve for the solutions 

 coexisting with solid B. According to the theory of van dkr Waals 

 (/e and r/' are at bottom two portions of a continuous cujtc, which 



1) Zeilschr. f. Eieklrocli. 33, OGo, (1903). 



12^ 



