IX.] CHEMISTRY OF NATURAL WATERS. 115 



the admixture of these in varying proportions. Sulphates are 

 sometimes present in these waters, but never predominate ; in 

 their absence, salts of barium and strontium are often met with. 

 The chlorides are generally, if not always, associated with bro- 

 mides and iodides. Small quantities of potassium-salts are also 

 present, while borates, phosphates, silicates, and small portions 

 of iron, manganese, and alumina, are generally present. These 

 various waters are occasionally sulphurous, and those of the 

 last three classes may be impregnated with carbonic acid. 



V. The fifth class includes acid waters remarkable for containing 

 a large proportion of free sulphuric acid, with sulphates of 

 lime, magnesia, portions of iron, and alumina. These waters, 

 which are characterized by their sour and styptic taste, gen- 

 erally contain some sulphuretted hydrogen. 



VI. The sixth class includes some neutral saline waters in which 

 the sulphates of lime, magnesia, and the alkalies predomi- 

 nate ; chlorides being present only in small quantities. 

 These waters, like the last, are often impregnated with sul- 

 phuretted hydrogen. 



The above classification, although adopted originally for the 

 convenient description of the mineral waters of Canada, will, it 

 is thought, be found to embrace all known classes of natural 

 waters, with the exception of those included under E, and of 

 some waters from volcanic sources holding hydrochloric acid, 

 These may constitute two additional classes. In the first three 

 of the classes above described, chlorides predominate ; in the 

 fourth, carbonates ; and in the fifth and sixth, sulphates. The 

 waters of the first, second, and sixth classes are neutral ; those 

 of the third and fourth, alkaline j and those of the fifth, acid. 



