32 



ART. 12. — H. HIKOBE : ON THE FUSION SURFACES OF THE 



Naphthalene. 



N 



Chlorubenzeiie. 



Fi 



relation as to naphthalene. Naphthalene can be replaced in the 

 solution mol for mol by chlorobenzene without causing any 

 change in the concentration of the 

 phenol which is in equilibrium with 

 the solid phase. 



The isotherms of the fusion fur- 

 face of naphthalene are concave towards 

 the line C P, and the empiricial molar 

 fraction of naphthalene decreases with 

 the increasing proportion of phenol. 

 The fusion surface of chlorobenzene lies 

 of course much lower than the other 

 two, but it must have a form quite 



similar to that of naphthalene, and the isotherms must lie as 

 shown in the figure. 



The eutectic curve E O must be the longest of the three, 

 being the line of intersection of the fusion surfaces of the two 

 components with the highest melting points. The other two 

 eutectic curves F O and GO would be relatively undeveloped. 



So much can be supplemented from the symmetry relations 

 of the three components. These relations can be readily com- 

 prehended, when we consider that naphthalene and chlorobenzene 

 are normal, undissociated substances fulfilling the conditions of 

 the ideal solution with respect to each other, while phenol is an 

 associated substance. That the isotherms of the fusion surface 

 of naphthalene are concave to the axis C F at least in the region 

 where the molar fraction of phenol is not very large, is also to 

 be expected. ^^ But in order to account quantitatively for the 



1) See Art. 10 uï this vohiiue. 



