102 Ferguson and Merwin — The Ternary System. 



Table VIII. 

 Quenches which determine the temperature relations at point 6. 



Time 

 Composition wt. % Temp. in Phases present 



CaO MgO Si0 2 °C. min. 



49 6 45 1374 20 No glass 



1379 20 Glass -4- crystals 



50 5 45 1378 20 Glass -f crystals 



1374 20 No glass 



49 7 44 1375 15 No glass 



1384 15 Glass -f- crystals 



Point 7 is a quintuple point between £2CaO.Si0 2 , 3CaO. 

 2Si0 2 and 2CaO.Mg0.2Si0 2 . The composition is CaO 

 49-5, MgO 6-2, Si0 2 44-3, and the temperature is 



1387 ± 5°C. 



Table IX. 

 Quenches which determine the temperature relations at point 7. 



Time 

 Composition wt. % Temp. in Phases present 



CaO MgO SiO a °C. min. 



49 7 44 1384 15 Glass + 3Ca0.2Si0 2 + 2CaO.Mg0.2Si0 2 



1389 15 Glass + 2CaO.Si0 2 + 2CaO.Mg0.2Si0 2 



50 6 44 1391 15 Glass + 2CaO.Si0 2 + 3Ca0.2Si0 2 



1384 15 Glass -f 2CaO.Mg0.2Si0 2 + 3Ca0.2Si0 2 



Point 8 is a eutectic between 2CaO.Mg0.2Si0 2 , a2CaO. 

 Si0 2 and a monticellite solid solution. Its composition 

 is CaO 39, MgO 18-3, Si0 2 42-7, and its temperature 



1436 ± 5°C. 



Table X. 

 Quenches which determine the temperature relations at point 8. 



Time 



Phases present 



Glass -f- crystals 



No glass 



Glass -j- crystals 



No glass, crystals including 2CaO.Si0 2 



Glass -j- crystals 



Glass -j- crystals 



No glass, crystals including 2CaO.Si0 2 



Point 9 is a quintuple point between 2CaO.Mg0.2Si0 2 , 

 forsterite, and a monticellite solid solution. Its compo- 

 sition is CaO 33-3, MgO 22-3, Si0 2 44-4, and its tempera- 

 ture 1436 ± 5°C. 



CaO 



MgO 



Si0 2 



°C. 



min 



39 



19 



42 



1443 

 1436 

 1443 

 1438 



20 

 20 

 60 

 45 



39-5 



18 



42-5 



1443 

 1438 

 1432 



30 

 20 

 15 



