to Calcium and Magnesium Metasilicates. 



11 



The first is to extrapolate downward the liquidus curves AB 

 and BC in fig. 1, and take the mean of the points where they 

 intersect the eutectic line HI. The accuracy of this extrapo- 

 lation is limited by the uncertainty of the liquidus curve for 

 some distance on each side of the eutectic composition. We 

 found with these particular silicates that the results agreed to 



Fig. 3. 



1379° 



1377° 



1375° 



1373° 



1371° 



1369° 



1367° 

























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1361° 



































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1359° 



























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1357° 





















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1355° 















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1353° 















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;.y 



w 

































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1351 c 











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s 



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1349° ' 















































Time : \ minute. 



Location of the eutectic composition. 



Curves I-I and Il-II, 28 per cent and 30 per cent MgSi0 3 just above the 

 eutectic point. 

 Curves I'-I' and II'-II' the same at higher temperature. 



5 per cent with a probable error of not over 2 per cent in the 

 eutectic composition. 



A more accurate determination seemed for some time to in- 

 volve considerable difficulty, but a satisfactory solution of the 



