to Calcium and Magnesium Metasilicates. 



27 



lated on the assumption of a purely additive relation. A sim- 

 ilar expansion is known in other cases.* CD contains the 

 volumes of mixtures of magnesium silicate and the diopsicle 

 mix-crystals. The minimum B, indicating a compound, falls at 

 about 49 per cent MgSi0 3 instead of 46*3 per cent, which is 

 demanded by the formula CaSi0 3 .MgSiG 3 . This is because a 



Fig. 





A 

























\ 

























\ 

























\ 



• 

 \ 

























\ 

























\ 

























\ 



\ 

























\ 

























\ 

























\ 



\ 

























\ 

















•3150 









\ 



\ 

























\ 



\ 







pr*- 1 





> 



D 



■3100 











\ 





/ 



>C 



















\ 



/ 













•3050 











} 



/ 













10 20 

 CaSi0 3 



40 50 60 70 

 Weight per cent. 



110 

 MgSiO a 



melt of the latter composition forms a crystalline mass which 

 always appears to contain more bubbles than the other compo- 

 sitions in its immediate neighborhood, so that the density of 

 the crystals is not only absolutely but also relatively too low. 

 It will be remembered in this connection that the diopside 

 which was crystallized from calcium chloride had a specific 

 gravity of 3'275, while that which was crystallized from a melt 

 of the composition CaMgSi 2 G 6 had a density of only 3*24. 



*E. S. Shepherd, Journ. Phys. Chem., viii, 245, 1904. 



