Ferguson and Merwin — The Ternary System. 95 



Time 



Composition 



! Wt. % 



Temp. 



in 



Phases present 36 Boundai 



CaO 



MgO 



Si0 2 



°C. 



min. 







53 



3 



44 



1450 



30 



Glass -f- 2CaO.SiO, 7, 



c 



49 



7 



44 



1398 



15 



Glass -j- trace 2CaO.SiO, -f 



trace 2CaO.MgO.2SiO., 7 



, 8 



47 



9 



44 



1426 



15 



Glass -f 2CaO.Mg0.2Si0 2 





46 



10 



44 



1410 



60 



Glass + 2CaO.Mg0.2Si0 2 





45 



12 



43 



1450 



20 



Glass -f 2CaO.SiO, 





42 



15 



43 



1450 



30 



Glass + 2CaO.SiO, 





42 



14-5 



43-5 



1448 

 1453 



15 



20 



Glass -f 2CaO.SiO, -f- 



2Ca6.MgO.2SiO, 

 Glass 





39 



18 



43 



1444 



20 



Glass + 2CaO.MgO.2SiO., 





39-5 



18 



42-5 



1449 



35 



Glass -4- 2CaO.SiO, 





36 



20-5 



43-5 



1438 

 1445 



15 



20 



Glass 4- CaO.MgO.SiO, -f 



2CaO.MgO.2SiO, 8 

 Glass 



, 9 



34 



22 



44 



1445 

 1439 



30 

 30 



Glass + CaO.MgO.SiO. + 



2CaO.Mg0.2Si0 2 





35 



22 



43 



1473 



20 



Glass + CaO.MgO.SiO., 





31-5 



22 



46-5 



1410 



30 



Glass + 2MgO.SiO, 4 



, 9 



33 



22 



45 



1428 

 1432 



20 

 15 



Glass -|- 2MgO.SiO, -f 



2CaO.MgO.2SiO, 

 Glass 





32 



25 



43 



.1477 



15 



Glass + 2MgO.SiO, 9, 



11 



32 



26 



42 



1501 



60 



Glass -j- 2MgO.SiO., 





33 



24 



43 



1472 



15 



Glass 4- CaO.MgO.SiO, 





33 



25 



42 



1460 



30 



Glass 4- CaO.MgO.SiO, 





37 



21 



42 



1467 



15 



Glass 4- CaO.MgO.SiO, 8, 



10 



37 



22 



41 



1485 



15 



Glass 4- CaO.MgO.SiO, 





38 



20 



42 



1483 



15 



Glass -f CaO.MgO.SiO, 





38 



21 



41 



1489 

 1493 



15 

 15 



Glass -j- CaO.MgO.SiO, -f 



2"CaO.Si0 2 

 Glass 





38 



22 



40 



1506 



15 



Glass + 2CaO.SiO, 





39 



19 



42 



1484 



15 



Glass 4- 2CaO.SiO, 





39 



20 



41 



1492 



15 



Glass 4- 2CaO.SiO, 





34 



25 



41 



1507 



20 



Glass -j- MgO 10, 



11 



37 



23 



40 



1517 



20 



Glass -f MgO 





38 



23 



39 



1539 



10 



Glass 4- MgO 10, 



12 



40 



22 



38 



1560 



30 



Glass 4- MgO 4- trace 2CaO.SiO, 





44 



21 



35 



1690 



30 



Glass -j- trace MgO 4- trace 



2CaO.SiO, 





31-5 



27 



41-5 



1522 



15 



Glass 4- MgO 4- 2MgO.SiO, 12, 



H 



30 



28 



42 



1537 



30 



Glass 4- 2MgO.SiO, 





29 



30 



41 



1545 



15 



Glass 4- MgO 





The £2CaO.Si0 2 field, 



if such a field exists, is too si 



11 a 



to be shown upon the diagram. If no solid solution 

 exists, it consists of that portion of the 2CaO.Si0 2 field 

 which lies below the isotherm 37 of 1420° since the inver- 

 sion of the /3 form to the a form in the pure compound 

 occurs at this temperature. The points 14 and 16 lie too 

 close to the point 15 to be separately located. 



37 See figure 12, beyond. 



