166 ALEX. L. DU TOIT. 



Illuminating are Gautier's 1 experiments in which he 

 obtained a solution containing silicate of soda (with a trace 

 of borate it should be noted) by digesting powdered granite 

 in warm water, while at the same time only a minute trace 

 of the potash of the felspars was dissolved ; in the presence 

 of 00 2 at relatively low temperatures the sodic silicate was 

 converted into carbonate. Long ago Daubree had dis- 

 coved that soluble compounds could be obtained by merely 

 grinding felspar in water, and that this action was assisted 

 by 00 3 but inhibited by NaOl. 



The production of the sodic carbonate by the carbonation 

 of felspars is thus quite feasible, and it remains therefore 

 to investigate the circumstances under which such changes 

 could have taken place. 



The analyses 2 of typical intake sandstones prove these 

 rocks to be rather poor in alkalies and alkaline earths, and 

 to have the percentage of soda almost universally lower 

 than that of potash. Since they, as well as the artesian 

 sandstones cut in the bores, are all more or less kaolinic in 

 character, and must have carried a fair amount of felspar 

 originally, it is only reasonable to conclude that they had 

 yielded up a certain proportion of their soda to the waters 

 percolating through them. On the other hand it is most 

 essential to observe the location along the eastern side of 

 the basin of nearly all the highly alkaline waters, and that 

 such are often high in chlorine also. 



The great quantity of carbon dioxide present, far higher 

 even than in the "highly carbonated'' waters of Iowa for 

 example, seems out of all proportion to the amount that 

 would be derived from the atmosphere under any but the 

 most abnormal of circumstances (see next section), and 



1 La Genese des eaux thermales. Annales des Mines, ix, p. 316, 1906. 



8 E. F. Pittman, Problems, etc., p. 15, 1908; The Composition and 

 Porosity of the Intake Beds, etc., p. 9, 1915. 



