1865.] CHEMISTRY OP NATURAL WATERS. 19 



heat and alkalies in the form of ammonia, is present in the lime- 

 stones, marls, argil lites, and sandstones of former geological 

 periods, in qualities scarcely inferior to those in similar deposits of 

 modern times, amounting, for most of the ancient sedimentary 

 strata, to from one to five thousands of nitrogen ;* from which it 

 will be seen that the amount of this element thus retained in the 

 rocky strata of the earth's crust is very great.f 



§ 33. If we attempt a chemical classification of natural waters 

 in accordance with the principles laid down in the preceding sec- 

 tions, they may be considered under the following heads : 



A. Atmospheric waters. 



B. Waters impregnated with the soluble products of vegetable 



decay. 



C. Waters impregnated with the salts from decomposing feld- 



spathic rocks, and holding a portion of carbonate of soda 

 as a characteristic ingredient. 

 J). Waters holding neutral salts of sodium, calcium, or magne- 

 sium from strata where they existed as solid salts, or as 

 impregnating brines. 



E. Waters holding chiefly sulphates from decomposing pyrites; 



copperas and alum waters. 



F. Waters holding free sulphuric or hydrochloric acid. 



§ 34. The name of mineral waters is popularly applied only to 

 such as contain sufficient foreign matters to give them a decided 

 taste; and hence the waters of the divisions A and B, and many of 

 the feebler ones of C and D, are excluded. Those of E and F 

 have peculiar local sources ; but those of C and D are often asso- 

 ciated in adjacent geological formations, and their commingling 

 in various proportions gives rise to mineral waters intermediate in 

 composition. In accordance with these considerations, a classifica- 

 tion of mineral waters for technical purposes was adopted by me 

 in the Geology of Canada, p. 531, including only those of C, D, 

 and F, which were arranged in six classes. 



I. Saline waters containing chlorid of sodium, often with large 

 portions of chlorids of calcium and magnesium, with or 



* Ann. des Mines [5], xviii, 151-523. 



t For an exposition of the views put forward in the four preceding 

 sections, see my paper in the Canadian Journal for 1858, p. 206. 



I 



