578 JAMES ASTON 
cible, and we have completely eutectiferous freezing. This is also 
the case between 50 per cent. and too per cent. Si, with the two 
components FeSi and Si. 
CALCIUM AND MAGNESIUM METASILICATES 
Strictly analogous to this is the diagram (Fig. 7) of solidification 
of calcium and magnesium metasilicates, also determined at the Geo- 
MELTING TEMPERATURES CA-NMG SILICATES 
S400 
TEMPERATURE 
X ‘ 
oy eae 
is} 8 
eres ES 
S250 
PERCENT 116 5103 
IGS 7 
physical Laboratory of the Carnegie Institution by E. T. Allen and 
W. P. White. As will be seen, at 47 per cent. MgSiO,+53 per 
cent. SiO, there is indication of the formation of the compound MgsiO, 
CaSiO, the mineral diopside. This diopside breaks the diagram into 
two parts each of the partial-solubility type. For the left-hand side, 
« Allen and White, ‘‘Diopside in Its Relations to Calcium and Magnesium Meta- 
silicates,” Am. Jour. Sci., January, 1909. 
