350 

 I. 



lower temperature, for x a value was found, somewhat different 

 from the formerly observed one with a fresh solution. Thus, altliough 

 the iron-oxide-solution remains "stable" until relatively higher 

 temperature and in general does not coagulate on heating, it seems 

 however yet to undergo some irreversible change, which is manifested 

 by the somewhat changed value of the free surface-energy. 



The described method is evidently also adapted for the investigation 

 of colloidal solutions of different nature; it is planned to determine 

 these values so highly important for the chemistry of the colloids 

 in the case of a more extended series of colloidal substances. 



1) Freundlich, Kapillarchemie (1909), p. 28. 



2) Volkmann, Wied. Ann. 11, 177, (1880) ; 17, 353, (1882) ; 53, 683, 644, 

 (1894); 56, 457, (1895): 62, 507, (1897); 66, 194, {1898). 



3) Brunner, Pogg, Ann. 70, 481, (1847). 



^) WoRLEY, Journ. Chem. Soc. 105, 266, (1914). 



•'') The other points mentioned in the diagram, have the following significance : 

 ^^= Weinberg, Z. f. phys. Chem. 10, 34, (1892); *S = Sieg, Diss. Berlin, 

 (1887j; E--RAYLEIGH, Phil. Mag. (5), 30, 386, (1890); ,S's = Sentis, Ann. de 

 rUniv. Grenoble, 9, 1, (1887); i/= Proctor Hall, Phil. Mag. ^5), 36 385, 

 (1893); 12= Magie, Wied. Ann. 25, 421, (1885). These data were obtained by 

 very dii'feient methods; they are evidently appreciably deviating from each other. 



