190 



E. A. STEPHENSON 



Clarke 1 and Steiger, 2 who found that the solutions obtained by 

 allowing various minerals — including orthoclase — and rocks to 

 stand in contact with water containing a few drops of phenolphtha- 

 lein developed more or less alkalinity. Cornu 3 obtained an alkaline 

 reaction toward moist litmus paper from various powdered minerals. 

 Konigsberger and Miiller 4 found also that adularia was but little 

 attacked at 300 C. by pure water, the chief attack being parallel 

 to the principal cleavage. Up to this temperature water alone is 

 not to be considered an important reagent toward adularia or 

 hornblende. 



Group II: Effect of sodium carbonate solutions on feldspars. — 

 The efficiency of carbonate solutions in hydrothermal processes is 

 commonly conceded; this conclusion is based on the abundance of 

 carbon dioxide in certain hot spring waters, and the presence of 

 carbonates in the altered rocks and in the veins. The data given by 

 Clarke 5 and by Peale 6 show not only that carbon dioxide dominates 



TABLE II 



in certain thermal waters but that sodium is generally an abun- 

 dant metallic ion in such waters. The concentration is low, rarely 

 reaching as much as 1 per cent, though the carbonates make up as 

 much as or even more than three-fourths of the total dissolved 

 matter. In order then to follow the original plan and to use solu- 

 tions comparable to those found in nature, solutions of sodium car- 

 bonate were employed as shown in Table II. The concentration 



1 F. W. Clarke, Jour. Am. Chem. Soc, XX, 739-42. 



2 George Steiger, ibid., XXI, 437-39. 



3 F. Cornu, Tsckermak's MiUeilungen, XXIV, 417-32. 



J F. W. Clarke, Bull. 491, U.S. Geol. Survey, pp. 180-81. 

 6 A. C. Peale, Bull. 32, U.S. Geol. Survey. 



4 Op. cit., p. 360. 



