104 Ferguson and Merwin — The Ternary System. 



use of the iridium furnace, but the temperature probably 

 lies above 1900 °C, the temperature at which the trical- 

 cium silicate decomposes into lime and a2CaO.Si0 2 . 



The exact temperature relations at the quintuple points, 

 at the quadruple points on the side lines, and along the 

 boundary lines, may be depicted by constructing a model 

 which has as a base the concentration diagram, fig. 8, and 

 upon which the temperatures are shown as vertical dis- 



Fig. 9. 







■ CaO| 





wT 



ii 









1 







■If® 



>— ^ 







\ >S5|L 4 





^HH 







r 



.. 





Fig. 9. — A model constructed by plotting vertically upon the concentra- 

 tion diagram as given in fig. 8, the temperature of complete fusion of the 

 compositions lying along the boundaries of the fields of stability of the 

 various phases. 



tances above this base. Fig. 9 is a photograph of such 

 a model. 41 This particular model includes and correlates 

 the previous results of Bowen on this ternary system, 



41 This is the framework of a solid model. A description of the construc- 

 tional details of such a model is given by Rankin and Wright, this Journal, 

 39, 1, 1915. 



