Alumina with Silica, Lime and Magnesia. 313 



Table VI.— Curve of melting points. (Curve A, B, C, D, E, F, G, H) 



Percentage of 

 A1 2 3 



75-22 

 * 



67-5 



64-58 60 



59 



57 



56 55 



54 



53 



Component in 





















excess melts . 1710° 



1581° 



1587° 



1568" 



1537 J 



1495° 



1444° 



1458" 



1443 u 



1389° 











66 



48 



1500 



54 



63 



35 



85 











66 



50 



1499 



50 





37 



87 









... 







64 



48 



98 



50 





33 



86 











68 



48 





48 





34 



82 















65 



49 



__ 



47 



__ 



38 







---- 



— - 



---- 



68 



49 



-- 



47 



-- 



40 



-- 



Mean 



1710 



1581 



1587 



1566 



1547 



1498 



1449 



1461 



1437 



1386 



Percentage of 

 A1 2 3 



52-22 



51 



49 



48 



47 



46 



45 



44 







Component in 























excess melts . 



1387" 



1383° 



1429° 



1435 u 



1440° 



1480° 



1495° 



1525° 









90 



83 



23 



36 



40 



79 



93 



24 









85 



84 



25 



32 



37 



82 



98 



25 









84 



83 



24 



33 



36 



81 



97 











83 



84 



25 



33 





83 



90 



. 









84 



84 



20 



28 

 28 



-- 



-- 



93 



-- 









... 



-- 



-- 



33 

 32 















Mean 



1386 



1384 



1424 



1432 



1438 



1481 



1494 



1525 























* Determination in iridium furnace with optical pyrometer. 

 Table VII.— Eutectic CaO.Al 2 3 +3Ca0.5Al 2 3 . (Line G E) 



Percentage A1 2 3 



67-5 



70 



73-22 



74-2 



75-22 



76-5 



Eutectic melts 



1581° 



1582° 



1582° 



1578° 



1577° 

 1579 



1572° 



1574 



1574 



Mean ._ 



1581° 



1582° 



1582° 



1578° 



1578° 



1573° 



The A1 2 3 melts too high, for safe determination in the 

 iridium furnace. Apparently, some 3Ca0.5Al 2 3 crystallizes 

 with the alumina since its optical properties are slightly 

 changed, but we have been able to detect CaO.Al 2 3 in the 

 95 per cent mixture, so that the range of this solid solution is 

 less than five per cent. 



Lime-Magnesia and Magnesia- Alumina. — While the melt- 

 ing temperatures of both of these series lie beyond our present 



