186 Ferguson and Merwin — The Ternary System. 



application. Little, however, has been done to show its 

 applicability to silicate melts. 20 Attention is therefore 

 called to the following definite observations which tend 

 to show that the phenomenon is by no means rare in snch 

 melts and may be the rnle rather than the exception. 

 (1) Allen, Wright and Clement 21 describe the forma- 



Fig. 6. 



Fig. 6. A model representing' the solidus and liquidus temperature-con- 

 centration relations in the part of the ternary system CaO-MgO-Si0 2 given 

 in fig. 2. The dark upper portion represents the pseudowollastonite solid 

 solutions; the lighter lower portion represents the wollastonite and 5CaO.- 

 2Mg0.6Si0 2 solid solutions; the black vertical wires with the connecting 

 wires represent the fixed points and boundary curves; and the black vertical 

 wires with light knobs at top represent the compounds akermanite (A) and 

 diopside (D). W=CaO.Si0 2 , wollastonite and pseudowollastonite. 



tion of an unstable fibrous magnesium silicate which 

 forms from quickly cooled melts and which transforms 

 into the stable clino-enstatite. 



20 Fenner (this Journal (4) 36, 342, 1913), in his study of the forms of 

 silica observed the formation of unstable phases in certain solutions some- 

 what resembling these melts and discussed Ostwald's law of successive reac- 

 tions in relation to their formation. 



21 This Journal (4), 22, 406, 1906. 



