UNPUBLISHED FRAGMENTS. 427 



In the above case of dissociation the formula would be 



For a coexistent solid phase of the solvent we have for constant 

 pressure 



At 



m s being for convenience taken the same in both phases. 

 Then 



In integrating for small values of y D we may treat the coefficients 

 of dt and cfy D as constant. This gives 



rt'\ 



or if we write Q 8 for (the latent heat of melting for the unit 



7/lg 



of weight of the solvent), we have 



This may be written 



-A*- 8 * At * 



M 8 Q 8 M 8 



According to Raoult, the first member of this equation has a value 

 nearly identical for all solvents and solutes (supposed definite com- 

 pounds). This would make the second member the same for all 

 liquids of " definite " composition, when we give M B the value for the 

 molecule in the liquid state. I should think it more likely that these 

 properties should hold for the two members of the equation 



A m s M I> _ At 

 " 



which are pure numbers (of no dimensions in physical units). In 

 this form it has a certain analogy with van der Waals' law of 

 " corresponding states." 



With a coexistent vapor phase of the solvent, we have 



At 



-T- Tf- 



v v M D 



