68 Rankin and Wright — Ternary System CaO-Al 2 \-SiO \. 



The data in Table XXIII illustrate that type of crystallization 

 curve in which a solid phase wholly disappears at a quintuple 

 point. Thus for a solution of the composition CaO 48'5, 

 A1 2 3 12, Si0 2 39*5 at a temperature of 1340° the crystalliza- 

 tion curve has reached the boundary curve S-4, 2CaO.Si0 2 

 and 2CaO.Al 2 3 .Si0 2 crystallizing together; at 1330° it has 

 passed through quintuple point 4 and proceeded along bound- 

 ary 4-6, 2CaO.Al 2 3 .Si0 2 and 3Ca0.2Si0 2 separating together; 

 at 1310° it has reached eutectic point 6 and the solution has 

 solidified to CaO.Si0 2 , 3Ca0.2Si0 2 and 2CaO.Al 2 O s .Si0 2 . 



Table XXIII. 

 Examples of crystal phases present during the course of a crystallization 

 curve which passes through a quintuple point and ends at a eutectic. 



Composition 

 weight percentage Temp. Present 

 CaO A1 2 Q 3 SiQ 2 



48-5 12 39-5 1340 Glass + 2CaO. Al 2 8 .Si0 2 + 2CaO.SiO a 



1330 Glass + 2CaO. Al 2 3 .Si0 2 + 3Ca0.2SiO a 



1310 CaO.Si0 2 + 2CaO.Al 2 3 .Si0 2 + 



3Ca0.2Si0 2 



60 32-5 7'5 1480 Glass + CaO 



1460 Glass + 3CaO. A1 2 G 3 + sCaO.SiO, 



1440 Glass + 3Ca(). A1,0, + Ca 2 Si0 4 



59 32-5 8-5 1470 Glass + 3CaO Si0 2 



1455 Glass + 3CaO.Si0 2 + 3CaO.Al 2 3 + Ca 2 Si0 4 

 1440 Glass + 3CaO Al a O, 4- Ca,SiQ 4 



The data in Table XXIV" illustrate that type of crystalliza- 

 tion curve in which a solid wholly disappears on a boundary 

 and the curve proceeds across a field to another boundary. 



Table XXIV. 



Examples of crystal phases present during the course of a crystallization 



curve which passes across a field. 



Composition 

 weight percentage 

 CaO A1 2 3 Si0 2 



Temp. 



Phases Present 



53 4 



43 



1420 



Glass + 2CaO.Si0 1 







1415 

 1410 



Glass + 2CaO.Si0 2 + 3Ca0.2Si0 2 

 Glass + 30aO.2SiO 2 



14 38'5 



47-5 



1574 



Glass + A1 2 3 







1570 

 1550 

 1545 



Glass + Al 2 3 + Al 2 Si0 5 

 Glass + A1 2 3 + A1 9 SK) 5 

 Glass + Al 2 Si0 6 



63 25 



12 



1610 



Glass + CaO + 3CaO.SiO, 







1500 



Glass + 3CaO.Si0 2 







1475 

 1425 



Glass + 3CaO.Si0 2 + Ca 2 Si0 4 

 Glass + Ca 2 SiG 4 + aCaO. A1 2 3 



