( 159 ) 



27 . . 

 The iactor — - is iji pertecl coiicordaiu'c willi (lie tactor which 



o 



occurs in tlie fbnmila of the vjiponr pressure, wlien we put tlie 



quantity h independent of tiie vohinie. I iiave sliown before tiiat it 



must be aboul doubled, when we assume variability for /^ — or ratlier 



27 

 the tactor -^ is not increased, but the assumption of the smaller 



o 



value of b comes to (h)ubiini>,' the factor, when we sul)stitute the 



a 

 value of //, foi" y . Without carrying out the elaborate calculations, 



whicli in our case might be the consequence of assumption of the 

 variability of b, 1 think to be justified in concluding to the doubling 

 of that factor as a sufficiently ap})roximated value. Then we find 

 back exactly the same value as 1 had found in "Ternary Systems", viz. 



1— .t'l A', \T d.v pk d.vj^ 



in which formula ƒ ma}^ put about 7. 



. ^fc , ^ ,. dlpk 



As - — — — — = A, we mav put tor — — : 



d lofi Ti: d log h 

 dx div 



Hence (G) becomes : 



1 - .v^ .v.^ \T tJ d.v ^ h d.v ^ ' 



dh 

 From the form (7) we derive, that onlv wiien = 0, and so 



d,r 



when the molecules of the mixed sul)staiu'es are of the same size, 



the concentration of the coexisting phases is the same for the mixture 



with minimum critical tempei'ature. If the size of the molecules is 



not the same a\^=,i'.^ for tlie mixture for which 



f 1 \ dTi, 1 dh 



(8) 



T TfJ d.v h d.v 



dh , , 



Tf — is positive, as is the case tor nuxtures of acetone and etiier 



d,r 



(ether as second component), then ,r = .i\^ for a mixture for wliicli 



dn 



d.v 



and therefore also the maximum pressure in the ^;, .i' line has shifted 

 to the side of the conqxment with fhe smallest molecule. If we 

 multiply both members of (8) by T, the shifting pro\es to increase 



is negative. Then tiie concentration wliere ,i\ and .i\ are ecpuil 



