Ferguson and Merwin — The Ternary System. 173 



Solid Solutions with Diopside and Silica. — Several 

 experiments were carried out in order to determine if 

 any solid solutions existed "between the calcium metasili- 

 cate-diopside line in the ternary system and the meta- 

 silicate-silica part of the side line. For this study the 

 composition CaO 46.2, MgO 1.2, Si0 2 52.6, was used. 



Wollastonite: Heated at 1000 °C for 40^ hours. The 

 charge then consisted of wollastonite which appeared 

 brown under the microscope, evidently due to the pres- 

 ence of silica. 



Pseudowollastonite: Heated at 1400 °C for 2 hours. 

 The charge then contained pseudowollastonite and no 

 evidence indicating the presence of silica was obtained. 



Evidently the wollastonite solid solutions do not 

 extend appreciably from the diopside line toward the side 

 line. The pseudowollastonite solid solutions on the con- 

 trary do extend somewhat in this direction but the limits 

 of the solutions on the diopside line and on the side line 

 preclude any great amount of solid solution in this 

 region. 



Solid Solutions between the Wollastonite-Diopside and 

 the Wollastonite-Akermanite Solid Solutions.— The opti- 

 cal similarity of all the pseudowollastonite solid solu- 

 tions makes impossible a determination of the extent of 

 these solutions in the region under discussion by means 

 of the microscope. However, if no solid solutions exist 

 within this region, then the region should consist of two 

 fields, one for each series of solid solutions with the usual 

 type of boundary curve. 10 



In the results upon the liquidus relations of the whole 

 ternary system given in the previous paper, no evidence 

 of such a boundary exists. Several additional experi- 

 ments were made in order to be sure that such a bound- 

 ary might not be overlooked. The results are given in 

 Table III. 



Table III. 



Quenches which indicate the extent of the area of solid solutions of 

 pseudowollastonite. 

 Time 



Composition wt. % 



Temp. 



in 



Phases present 



CaO MgO SiO, 



°C. 



min. 





45-3 6-2 48-5 



1450 



30 



One-half glass 





1470 



30 



All glass 



44 6 50 



1450 



30 



Considerable quantity of crystals 





1470 



30 



Glass -f trace of crystals 



Ernst Janecke, Zs. phys. Chem., 67, Case 2, p. 661, 1909. 



