OF THE SYSTEM NAPHTHALENE-PHENOL. 5 



liquid phase has been established beyond any doubt, belongs to 

 the same class, the reaction^^ being represented by 



3 C,H,0 -^ CJÎA 



Acetaldehyde. Paraldehyde. 



Since volume-changes usually accompany polymerisation, 

 pressure must exercise some influence on the equilibrium. But 

 the effect can be considerable only when the variation of pressure 

 amounts to hundreds of atmos2:)heres. We may therefore safely 

 ignore it in the present study, in which the pressure remains 

 practically constant at one atmosphere. Hence iv is to be con- 

 sidered as a function of temperature alone. 



It is a necessary consequence of equation (1), that the equa- 

 tion of VAN t'Hoff 



dT BT'- 



applies to the present case. Here D is the heat of dissociation 

 of one gramme-molecule of (CgHgOJs including the heat expended 

 in performing any mechanical work accompanying the chemical 

 change. We may assume, without much hesitation, D to be 

 constant, because the heat capacity of 3 CgHgO will be very nearly 

 equal to that of (CGHgO):^. The equation can therefore be inte- 

 grated, when it assumes th« following simple form : 



I^^^B \Z TJ^ ^9) 



where % represents the temperature at which i^ becomes unity. 



It is not very probable that naphthalene and phenol should 



form compounds, and even when they do so, the compounds 



1) HoLLMAi^N; Zeitb. pbybik. Chem., -43, 129 (1903). 



