CHEMISTRY: FERGUSON AND MERWIN 
17 
rent through it, and the charge fell into a mercury bath which instantly chilled it. 
When cold the charge was opened and the content was examined under a petro- 
graphic microscope by means of which the phases present could be identified. 
The results of the hundreds of heat treatments which were carried out dur- 
ing this study cannot be presented in detail in a paper as brief as this one 
must be, but we hope in a general way to indicate their character. 
2570 
FIG. 1. THE TRIANGULAR CONCENTRATION DIAGRAM IN MOL-PER CENT 
The heavy lines are the boundaries of the fields, the solid light lines are the isotherms 
which are readily measured, the lighter dotted lines are the high temperature isotherms which 
are not so accurately known and the heavier dotted lines are limits of the solid solutions. 
The solid solutions may also be distinguished from the isotherms in that they have arrows 
which indicate the fields which correspond to the respective solid solutions. The tempera- 
tures given correspond to (1) the quintuple points, (2) the quadruple points, (3) the melting 
points of the compounds and (4) the melting points of the component oxides. 
The phases which occur in the three main binary systems and which also 
have fields in the ternary system are: (1) CristobaHte, Si02, (2) Tridymite, 
Si02, (3) Pseudowollastonite, a CaO.Si02, (4) Tricalcium di-sihcate, 3CaO. 
2Si02, (5) a Calcium orthosilicate, a 2CaO.Si02, (6) Lime, CaO, (7) 
Periclase, MgO, (8) Forsterite, 2MgO.Si02. 
