OF THE SYSTEM NAPHTHALENE-PHENOL. 3 



form. It is indeed more rational to suppose that all sorts of 

 association and dissociation take place to a greater or less extent. 

 When one of the chemical species so preponderates over the 

 others, that their existence may be neglected in quantitative con- 

 siderations, then the substance is said to be normal. In other 

 cases the substance is called associated or dissociated according 

 to the circumstances. 



It is beyond doubt that naphthalene is a normal substance 

 in the sense above defined, because it is one of the components 

 of several systems, whose fusion curves satisfy fairly well the 

 equation for that of an ideal solution. On the other hand, 

 phenol must be looked upon as a highly associated substance. 

 Even in dilute solutions the depression of the freezing point 

 caused by it is far below the normal value. We have therefore 

 to assume the existence of the following chemical equilibrium in 

 the solution. 



2CÄ0 -Z (CÄOX (a) 



3CeHeO -^ (CÄ0)3 {h) 



etc., etc, 



When we assume further that each of the chemical species CßHoO, 

 (C6HcO)2, (C6H60)o, etc., has a chemical potential represented 

 by the equation (1), then the following conditions must be 

 satisfied by the polymers when they are in equilibrium. 



^=^2 (a) 



-^ = ^3 (/3) 



etc., etc., 

 in which Ci, G, Cz etc., are the molar fractions of the chemical 



