114 CHEMISTRY OF NATURAL WATERS. [IX. 



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 associated in adjacent geological formations, and their 

 commingling in various proportions gives rise to mineral waters 

 intermediate in composition. In accordance with these con- 

 siderations, a classification of mineral waters for technical pur- 

 poses was adopted by me, in 1863, in the Geology of Canada, 

 p. 531, including only those of C, D, and F, which were ar- 

 ranged in six classes. 



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

 portions of chlorides of calcium and magnesium, with or 

 without sulphates. The carbonates of lime and magnesia 

 are either wanting, or present only in small quantities. 

 These waters are generally bitter to the taste, and may be 

 designated as brines or bitterns. 



II. Saline waters which differ from the last in containing, besides 

 the chlorides just mentioned, considerable quantities of 

 carbonates of lime and magnesia. These waters generally 

 contain much smaller proportions of earthy chlorides than 

 the first class, and hence are less bitter to the taste. 



III. Saline waters which contain, besides chloride of sodium and the 



carbonates of lime and magnesia, a portion of carbonate of 

 soda. 



IV. Waters which differ from the last in containing but a small 



proportion of chloride of sodium, and in which the carbonate 

 of soda predominates. The waters of this class generally 

 contain much less solid matter than the three previous cl 

 and have not a very marked taste until evaporated to a 

 small volume, when they will be found, like the last, to be 

 strongly alkaline. 



Of these four classes, I. corresponds to the division D, and 

 IV. to C, while II. and III. are regarded as resulting from 



