CHEMICAL THEOKY OF SOLUTIONS. PAKT I. 73 



The fusion point of the normal substance can, therefore, be 

 profitably employed to elucidate the state of chemical equilibrium 

 in the solution. For this purpose the determination of C<^ by 

 the equation 



e 



(i-i) 



<^? = (v-i)(i-^) ~-.;3r (33) 



seems to be the most convenient. That v must be found by 

 trial is the weak j^oint in this method. But when its value is 

 once determined, Ca and ^ can readily be found. For the 

 determination of the characteristic quantities v, D., and 3^ three 

 fusion points are necessary. 



(2) The Solid is the Associated Component. 



Of which chemical species the solid phase of the associated 

 substance consists is a matter of indifference, because the heat 

 of dissociation or association will be included in the heat of 

 fusion as it is observed or calculated. But it is otherwise when 

 the solid phase consists of the mixture of the two chemical 

 species ©x and ©ß. In this case the heat of fusion must vary 

 with the temperature on account of the variation of the degree 

 of association in the solid phase. As this consideration leads to 

 a tolerably complicated result, we shall not discuss it in this 

 place. 



In the following we shall consider the solid phase to be in 

 immediate relation to the chemical species ©p in the solution. 

 Then we have by equation (17) 



C\ = e^^'^'o 'J-'^ (54) 



