Rankin and Wright — Ternary System CaO- Al.fi \-Si0 2 . 65 



CA8„ASxi\dS. (c) Triangle 0-0,8-18; there will appear 

 consecutively : pure CJS; G 2 S and CaO ; CJS, CaO and G 3 S ; 

 C 2 S and <7 3 #and finally Cj8, Cy8 sad C 3 A. (d) Triangle 0,S- 

 18-0; there will appear consecutively: pure CaO; CaO and 

 G 2 8; 0,8, CaO and 0,8; C 2 S and C 3 S; and finally CJS, C 3 S 

 and C 3 A. (e) Triangle C&0- X- C 3 S ; there will appear con- 

 secutively: pure CaO; CaO and C 2 S; CaO, OJS and C 3 S; 

 CaO and C 3 S ; and finally CaO, OJS and G 2 A. (f) Triangle 

 O^S-Z-16; there will appear consecutively: OJS; G 2 S and 

 0,8; 0,8, 3 S and ^1; <7 2 #and <7 3 ^L; and finally 0,8, 3 A 

 and (7.J-3. (g) Area (7 3 #- 67 3 J.- Y ; there will appear con- 

 secutively: pure CaO; CaO and C 3 S; CaO, C 3 S and (7 3 ^1 ; 

 6^ and (7,-4; and finally 0,8, 3 A and £ 2 #. (A) Area 6' 3 J- 

 17-Z; there will appear consecutively : pure CaO ; CaO and 

 3 8 or CaO and 3 A; CaO, 0,8 and 3 A ; <7 3 #and <7 3 A : 

 0,8, 3 A and G 2 S; 0,8 and 3 A; and finally 3 A, ftSand 



(3) There are four areas which represent the compositions of 

 solutions which have crystallization curves of type (3). (a) 

 Triangle G 3 S,-4^B' ; there will appear consecutively : pure 

 0,8; CJS and C 3 S 2 ; pure 3 S 2 ; 3 8 2 and OS; and finally 

 3 8 2 , 6$ and 2 AS. (b) Area 9-W-V; there will appear con- 

 secutively: pure A; A and AS; pure AS; AS and OAS 2 

 and finally AS, CAS 2 and 8. (c) Triangle C 3 8-18-Y; if the 

 crystallization curve intercepts the boundary between 18 and 

 O, there will appear consecutively : CaO ; CaO and 0,8 ; CaO, 

 2 S and 3 S; CslO-0 3 S; pure 0,8; C 3 S and 2 8; and finally 

 3 S, OJS and C 3 A ; or if solutions intercept boundary between 

 18- Y, there will appear : pure CaO ; CaO and 3 8, pure OJS; 

 3 S and 2 S ; and finally 3 S, 2 S and 3 A. (d) Area <7 3 J.- 

 17-D ; there will appear consecutively : pure CaO ; CaO and 

 3 A; pure 3 A; C 3 A and 2 8 or (7 3 Jl and <7 5 4 3 ; and finally 

 3 A, C,S and C t A Vt 



General Conclusions as to the Nature of Crystallization in 

 Ternary Solutions of Ca0-Al 2 3 -Si0 2 . — The nature of the 

 crystallization of a ternary solution depends upon the original 

 composition of the solution and the class of boundary curve 

 which the crystallization curve intersects. There are two 

 general classes of boundary curves : 



1. Boundary curves along which two phases crystallize 

 together. A tangent drawn at any point on a boundary curve 

 of this class will intersect the line joining the compositions of 

 each of the two phases. This class is illustrated by all those 

 boundary curves of which one end is a eutectic point. For 

 example, in fig. 17, boundaries A-2,J-1. J/-5, 11-7, 16-15, 

 13-14, F-U, etc. 



2. Boundary curves along which one phase crystallizes while 



Am. Jour. Sci.— Fourth Series, Vol. XXXIX, No. 229.— January, 1915. 

 5 



