Day and Shepherd — Lime-Silica Series of Minerals. 291 



Observations along the curve of melting points are con- 

 tained in Table II. The eutectic KL (pseudo-wollastonite + 

 a-calcium orthosilicate, Table 3) was found in all compositions 

 containing more than 50 per cent and less than 65 per cent 

 CaO. Not a trace of it could be detected in the 65 per cent 

 composition, though diligent search was made for it. A great 

 many determinations were made of it of which the values are 

 given in Table III. 



Table III. 



Eutectic. Pseudo- Wollastonite 



+ a-Calcium Orthosilicate. 





Percentage 

 of CaO 50 



(I 



52 



jine KL, 

 54 



fig. 3.) 

 555 



57 



60 



625 



Eutectic 1428° 



1432° 



1435° 



1427° 



1419° 



1431° 



1426° 



melts 1435 



1428 



1437 



1428 



1428 



1422 



1431 



1432 



1428 



1434 



1427 



1428 



1425 



1429 





1428 



1435 



1428 



1430 



1426 







1429 



1435 



1427 



1429 



1426 







1428 



1432 



1428 



1429 



1426 







1430 



1432 



1429 



1433 









1433 



1435 



1431 



1434 









1426 



1433 



1430 



1434 









1433 



1430 



1430 



1441 









1427 



1429 





1438 









1431 







1435 









1430 















1426 















1430 















1431 













Mean 



1432° 1430° 1433° 1429° 1431° 1426° 1429 ( 



The properties of the metasilicate separating along CD are 

 also slightly different from those of the pure pseudo-wollas- 

 tonite, and up to 50 per cent the mixture appears homogene- 

 ous, so that the metasilicate probably takes up about 1 per 

 cent of orthosilicate in solid solution. The melting point of 

 the orthosilicate determined in the iridium furnace was found 

 to be 



2077° 

 2085° 

 2083° 



Mean 



2082 ( 



Another charge observed at 2035° was found entirely 

 unmelted. Optical methods of temperature measurement are 

 not competent to determine the melting temperature of the 



