244 HAROLD L. ALLING 
(5) soda-lime-carnegieite, (6) soda-barium-carnegieite, (7) lime- 
barium-carnegieite, (8) potash-barium-carnegieite, (9) potash- 
barium-lime, and (10) potash-lime-carnegieite. 
As it is not possible, within the limits of the present paper, to 
discuss all of these ternary systems, we are compelled to confine 
our considerations to the most important series, the potash-soda- 
lime feldspars. 
THE POTASH-SODA-LIME FELDSPARS 
The first important paper outlining the ternary system, K-, 
Na-, Ca-feldspars, appeared in 1905 from the pen of J. H. L. Vogt. 
Tracings of his original figures are here reproduced in Figure to. 
The two upper diagrams illustrate the conventional method of 
representing the space model. The plagioclase series will be ~ 
recognized as occupying the back plane. It will be seen that 
Vogt’s conception of the solidus TandTay was that it assumed a 
straight line, which recent laboratory work has modified to a 
concave one as will be recalled by consulting Figure 2. The 
binary solubility lines extending from the eutectic temperatures to 
the base of the space model, which indicate low or normal tem- 
peratures, are not drawn. In the plan view the ternary solubility 
lines, /g and kz, at eutectic temperature, are shown projected to 
the base. The plan view may represent the ternary diagram at 
eutectic temperatures, or the diagram at normal temperatures 
provided the binary solubility lines are vertical. Vogt’s 
original conception was that these lines were vertical. However, 
Warren has correctly suggested that these lines should be inclined, 
approaching the sides of the binary diagram with lowering tem- 
perature. This modification is called for in order to explain the 
formation of perthites (“‘perthoids’’) due to exsolution. 
The Or-An binary is more or less hypothetical. 
If the plan view be considered as a transverse section of the 
diagram cut at eutectic temperature, the areas AnAbgh and kiOr 
represent solid solutions of the components at this temperature. 
At normal temperature these areas should be more restricted than 
is actually shown by Vogt, occupying less space on the diagram. 
Positions outside of these areas represent compositions where 
tJ. H. L. Vogt, Tschermak’s Mineralog. und Petrogr. Mitt. (1905), pp. 24 et seq. 
