Ferguson and Merwin — The Ternary System. 87 



by Boeke. 29 The method used was that of heating curves 

 (the quench method has not been perfected) and was 

 scarcely adequate. Many curves were obtained which 

 were susceptible of various interpretations. The most 

 probable interpretation was based upon the assumption 

 that the inversion temperature of the wollastonite was 



Fig. 6. 



d£o e 



JfyO-3£O z 



CaOJToO-ZSiO, 



Zzmuk of ' 3obid 

 '-^ Solution, of/3 GuO-JiO. 



3&QeS7uO r 



ZffyO -3iO z 



Fig. 6. — Partial ternary diagram showing the previously published results, 

 wt. per cent. 



never raised enough by solid solution to cause the solid 

 solutions to appear as primary phases. 



The chief optical properties observed for diopside are 

 as follows : 30 



a = 1-664-6, p = 1-671-3, y = 1-694-5; +2V = 59°; y A c 

 = 38%°. 



29 Grundlagen der physikalisch-chemischen Petrographie, 182, 1915. 



30 Including new determinations. 



