COMPOSITION OF SPRING WATERS 169 



Classification of Natural Waters. 



Clarke (4: ijj/) has summarized the characters of natural wa- 

 ters in the following classification : 



I. Chloride waters. Principal negative ion CI. 



A. Principal positive ion sodium. 



B. Principal positive ion calcium. 



C. Waters rich in magnesium. 



II. Sulphate waters. Principal negative ion SO4. 



A. Principal positive ion sodium. 



B. Principal positive ion calcium. 



C. Principal positive ion magnesium. 



D. Waters rich in iron or aluminum. 



E. Waters containing heavy metals such as zinc. 



III. Sulphato-chloride waters, with SO4 and CI both abundant. 



IV. Carbonate waters. Principal negative ion CO3 or HCO3. 



A. Principal positive ion sodium. 



B. Principal positive ion calcium. 



C. Chalybeate waters. 



V. Sulphato-carbonate waters SO4 and CO3 both abundant. 

 VL Chloro-carbonate waters CI and CO3 both abundant. 



\TI. Triple waters, containing chlorides, sulphates and car- 

 bonates in equally notable amounts. 



VIII. Siliceous waters. Rich in SiOo. 



IX. Borate waters. Principal negative radicle B^O^. 



X. Nitrate waters. Principal negative ion NO3. 

 XL Phosphate waters. Principal negative ion PO4. 

 XII. Acid waters. Contain free acids. 



A. Acid chiefly sulphuric. 



B. Acid chiefly hydrochloric. 



While this emphasizes the essential types, it must be borne in 

 mind that many waters are intermediate in character between these 

 types, and their classification with one or the other may be a n^atter 

 of opinion. 



Gases and Organic Matter in Natural Waters. 



Besides the dissolved mineral matter found in tlie natural wa- 

 ters of the world, there exist various dissolved gases and a varying 

 proportion of organic matter. The relative quantity of different 

 gases varies according to the temperature, as shown in the follow- 

 ing table prepared by R. W. Bunsen and quoted by Clarke (4 : 4^) : 



