136 CHEMISTRY OF NATURAL WATERS. [IX. 



chloride of potassium is equal to not less than 25.0 per cent. 

 There does not, however, appear to be any relation between 

 the proportion of alkaline carbonate and that of potassium, 

 since the salts from the waters first named are more alkaline 

 than those of St. Ours ; while those of the alkaline water of 

 Joly contain less than one per cent of potassic chloride. 



The amount of this salt obtained from the water of the 

 Ottawa Eiver is worthy of notice, being equal to not less than 

 32.0 per cent of the alkaline chlorides, while in the waters of 

 the St. Lawrence it amounts to 16.0 per cent.* A large pro- 

 portion of potassium relatively to the sodium has already been 

 observed in the case of many ordinary river and spring waters, 

 and this is readily explained when we consider the extent to 

 which potash is set free by the decomposition of both vegetal 

 and mineral matters at the earth's surface. The process by 

 which this base is eliminated in filtering through soils has 

 already been explained in 5. The occasional presence of 

 considerable amounts of potash in sulphated mineral waters 

 (Lersch, Hydro-chemie, page 346) is explained by the power 

 of solutions of gypsum to set free this alkali from soils ( 7), 

 and also probably in some cases .by the dissolution of double 

 potassic salts like polyhallite. Strata holding glauconite, which 

 occurs alike in paleozoic and more recent formations,t may also 

 be conceived to yield potash-salts to infiltrating waters. 



53. It will be seen that the waters above noticed, in 

 which the proportion of the potash to the soda is large, are 

 but feebly saline, so that the real amount of potassium is in 

 no case great. The fact of especial importance as n 

 the alkaline metals in the waters whose analyses we have given 



* See London, Edinburgh and Dublin Phil. Mag. (4), XIII. 239, and Geol- 

 ogy of Canada, page 565, where analyses of both of these waters may be 

 found. 



f For a notice, with analyses by the author, of a green hydrated silicate 

 of alumina, iron and potash, allied to glauconite, from the palaeozoic rocks 

 of Canada and of the Mississippi valley, see the Geology of Canada, pages 

 487, 488 ; where also will be found an analysis by the author of the glauconite 

 from the cretaceous formation of New Jersey. See also Amer. Jour. Science 

 (2), XXX. 277. 



