SYSTEM NAPHTHALENE-CHLOROBENZENE-PHENOL, ETC. ô 



lively simple case. I chose the system consisting of naphthalene, 

 chlorobenzene, and phenol. The two former components are 

 known to be normal or nnassociated substances ; and the melting 

 point of naphthalene is such that the temperatures of fusion fall 

 mostly within the range in which exact measurement can be 

 made with comparative ease. Phenol is chosen as the third 

 component as it is known to be highly associated. As all 

 the chemical species of the system are aromatic compounds 

 and hence of allied chemical nature, it is probable that the 

 conditions of ideal solutions are fulfilled with tolerable approxima- 

 tion. Chemical combination between the components appears 

 to be excluded, so that the only chemical reaction which takes 

 place in the solution is the polymerisation and depolymerisation 

 of phenol. 



The determination of the molecular complexity of snbstances 

 in the liquid state is a very important subject, but the methods 

 hitherto employed for the purpose are rather one sided and not 

 very accurate. Of these the method of Eötvös, and Ramsay 

 and Shield alone is applicable to pure liquids. But there is 

 some doubt about the mode of calculation involved. Other 

 methods are applicable only to solutes in dilute solutions ; par- 

 ticularly the cryoscopic method and that of the partition co- 

 efficient have been employed with success. In cases like the 

 present, these methods of heterogeneous equilibrium can be em- 

 ployed over a very wide range of concentration. 



Beckmann^^ demonstrated for the first time by the cryoscopic 

 method that phenol is polymerised in its solutions. Neenst^^ 

 arrived at the same conclusion by the method of partition co- 



1) Zeits. f. physik. Cliem., 2, (ISSS), 715. 



2) Zeits. f. physik. Cheiu., 8, (LS91), IIG. 



