WATER 113 



ization of many materials which could not 

 otherwise be brought to the organisms which 

 need them. 



It has been calculated by Murray 1 that 

 the total yearly run off of all the rivers of the 

 earth is about 6500 cubic miles, carrying 

 nearly 5,000,000,000 tons of dissolved mineral 

 matter and prodigious quantities of sediment. 

 The average composition of such water has 

 been estimated as follows : — 



Parts per Million 



Potassium as K 2 2.40 



Sodium as Na 2 7.10 



Lithium as Li 2 0.20 



Calcium as CaO 43.20 



Magnesium as MgO 14.70 



Manganese as Mn 3 4 1.20 



Iron as FeO 2.80 



Aluminium as A1 2 3 3.10 



Silicon as Si0 2 16.40 



Carbonic acid as C0 2 46 



Phosphorus as P 2 5 0.30 



Nitric acid as N 2 5 3.80 



Sulphuric acid as S0 3 8 



Chlorine as CI 3.70 



Ammonia as NH3 0.07 



Total mineral matter 152.97 



It is, of course, almost exclusively to these 

 constant accessions that the ocean owes its 

 salinity, which in the course of time has 

 reached well-nigh inconceivable magnitude. 

 The common salt alone in the oceans of all 



1 Russell, "Rivers of North America," p. 80. 



1 



