208 



Allen, Crenshaw, Johnston, and Lav sen — 



composition in a, solid solution A = 

 is the change in the melting point 



02 T 2 



(Cj — C 2 ), where A 



T is the melting point 

 (absolute) of the solvent, I is the heat of fusion of the same, and 

 C x and C 2 the concentrations of the solute in the liquid and solid 

 respectively, we fold that the melting temperature is raised if 



Fig. 13. 



1220° 

 1210° 

 1200° 

 1190° 



I 1180 C 



© 



s 



H 1170 c 



1160 c 



1150' 



1140' 



1130° 



















































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Fig. 13. 



Time in Minutes. 

 Melting and freezing curves of pyrrhotite in hydrogen sulphide. 



the liquid which first forms contains less of the solute than the 

 original solution. We do not, to be sure, know the composi- 

 tion of the first liquid which forms, but as the final liquid prod- 

 uct contains less sulphur than the original solid, it is impossi- 

 ble to believe that this is not the case with the first liquid also. 

 Melting temperature of pyrrhotite in sulphur vapor. — If 

 this conclusion is correct, it follows that by raising the pressure 



