576 JAMES ASTON 
whether the composition of the original molten mixture lay to the 
left or right of the eutectic ratio; and a composite eutectic A saturated 
with B and B saturated with A. 
Of this type are the Sn-Zn, Au-Ni, Ag-Cu alloys. 
Besides these three general types of solubility which we have con- 
sidered, numerous others could be taken up in detail. For example, 
A and B might form one or more definite compounds, which com- 
pounds could have with A and B and with each other, independently 
different solubility relations. Or again, there might be only partial 
solubility while the alloy was still molten. However, all are really 
combinations and elaborations of the fundamental types to fit more 
complicated conditions. 
ISOMORPHISM OF FELDSPARS 
Referring now to one of the few investigations in this line which 
have been carried out in geological research, we have (Fig. 5) the 
MMELTING Te MELA TURES SOODA-LIME FELOSPARS 
1600 
HSEGEC Eee 
om EE Ae eee) 
RS eae 
TEMPERA TORE 
XN 
G 
8 
oem 
AEE 
4100 
AN Ab,ANs AB, AN A6 As As An F An, 
AN /00 64 es G8o- /. 4 A 26 Oo An 
ABo oe = so S AE 658 aA 6 709 AB 
Fic. 5 
freezing-point curve of the soda-lime feldspars, as determined by Day 
and Allent at the Geophysical Laboratory of the Carnegie Institution. 
The work was conducted exactly as indicated for alloys, by time- 
«Day and Allen, Isomorphism of the Feldspars (Publications of the Carnegie 
Institution). 
