Rankin and Wright — Ternary System CaO-Al 2 3 -SiO v 39 



Point 9 is the quintuple point for A1 2 3 , CaO.Al 2 3 .2Si0 2 and 

 Al 2 3 .Si0 2 . (CaO 15*6, A1 2 3 36-5, SiO, 47-9); 1512° ± 5°. 



Point 10 is the quintuple point for SiO, (tridymite), Si0 2 

 (cristobalite) and Al 2 3 .Si0 2 (sillimanite). (CaO 6*6, A1 2 3 17*6, 

 Si0 2 75-8); 1470°. 



Point 11 is the quintuple point for 3CaO 5A1 2 3 , 2CaO.Al 2 3 . 

 Si0 2 and A1 2 8 . (CaO 31-2, A1,0 3 44-5, Si0 2 24-3); 1475° ± 5°. 



Point 13 is the quintuple point for 2CaO.Al 2 3 .Si0 2 , 2CaO.Si0 2 

 and CaO.Al 2 3 . (CaO 48-3, A1 2 3 42, Si0 2 9*7); 1380° ± 5°. 



Point 16 is the quintuple point for 3CaO.Al 2 3 , 3CaO.Si0 2 and 

 2CaO.Si0 2 . (CaO 58.3, A1 2 3 33, Si0 2 8-7); 1455° ± 5°. 



Point 17 is the quintuple point for CaO, 3CaO.Al a 3 and 

 3CaO.Si() 2 . (CaO 597, A1 2 3 32'8, SiO, 7*5); 1470° ± 5°. 



Point 18 is the quintuple point for CaO, 2CaO.Si0 2 and 3CaO. 

 Si0 2 . (CaO 68-4, A1 2 3 9% Si0 2 22-4); 1900° ± 20. 



Point (18) was located by extrapolation of the bonndary 

 curves 16-18 and 17-18. The direction of the lower parts of 

 these curves — temperature up to 1600° — was determined by 

 quenchings ; the temperature of the upper parts of these is 

 beyond the range of our temperature measurements, so that 

 neither the location or temperature of point 18 is very accu- 

 rate. Point 18 is the dissociation temperature of 3Cal).Si0 2 . 



Point 19 is the quintuple point for a2CaO.Si0 2 ,/32CaO.Si0 2 

 and 3CaO.Al 2 0, (CaO 54*5, A1,0 3 38, Si0 2 7*5) ; 1390°. 



Point 20 is the quintuple point for a2CaO.SiO a ,j82CaO.SiO t 

 and 2CaO.Al 2 0,.SiO, (CaO 48*7, A1,0 3 39-3, SiO, 12) ; 1430°. 



Recapitulation ; the Concentration-Temperature Model. 



In the preceding pages we have recorded equilibrium tem- 

 peratures as determined within the limits of our apparatus for 

 the three binary systems and for the ternary system ; in other 

 words, we have presented the temperatures corresponding to 

 quintuple points, boundary curves and fields. By interpolation 

 from the determined melting temperatures we may draw con- 

 stant temperature lines or isotherms ; this has been done for 

 every 100° from 1200° to 1700° and the resulting diagram is 

 given in fig. 8, which shows, moreover, the melting tempera- 

 tures and compositions of each compound, component, quadru- 

 ple point and quintuple point. 



By erecting the concentration-temperature diagram (fig. 7) 

 for each boundary curve (fig. 6) perpendicular to the plane of 

 the corresponding projection of each boundary curve (fig. 6), 

 one constructs a concentration -temperature solid model whose 

 surface represents the melting temperature of all ternary com- 

 positions of Ca0-Al 2 3 -Si0 2 . A detailed description of the 

 method used in the construction of a solid model is given in a 



