30 ART. 10. — K. IKEDA : STUDILS ON THE 



The third condition is an assumption which does not stand in 

 any necessary connection with tlie concej^tion of the ideal solution 

 developed in the present study. Tammann has observed that 

 the heat of fusion is nearly constant along the fusion curve of 

 one component system (the temperature-pressure curve). And as 

 the heat of mixing is nil in the case of ideal solutions the 

 assumption seems to be quite plausible. But the specific heats 

 of the same component as solid and liquid are in general not 

 equal. Hence the condition will rarely be fulfilled exactly. 

 Still for the cases in which the temperature range is somewhat 

 limited the assumption may be admitted as a convenient ap- 

 proximation. Two conditions out of the three being thus ex- 

 traneous to the conception of an ideal solution, tliere remains 

 only the first condition to be examined. Excepting the cases 

 in which the gas pressure or the osmotic pressure are avowedly 

 taken into consideration, the idea of molecular weight is 

 generally rather vague in thermodynamical discussions, and the 

 molecular weights employed in calculating Ci may well be those 

 in the gaseous state and not those in the liquid state. This 

 is often explicitely stated in the deduction of the laws of dilute 

 solutions. Hence the first condition does not coincide with 

 condition (1) or (2), and it is doubtful whether the three con- 

 ditions given by Roozeboom sufiice to establish equation (17). 

 On the other baud Dahms mentions conditions (1) and (2) 

 explicitely. 



The relation between the temperature and the composition 

 of an ideal solution which is in equilibrium with a solid phase, 

 either a comjDonent or a compound, can be deduced in the 

 following manner. The equation (see page 7), 



