174 GEOLOGICAL HISTORY OF LAKE LAHONTAN. 



and 0.056416 part jjer thousand as the average of the calcium carbonate 

 contained in the waters of American rivers. 



In a table of 48 analyses of European river waters given by Bischof, ^ 

 the average of total solids is 0,2127, and the average of calcium carbonate 

 0.1139 part per thousand. From the analyses of 36 European river waters 

 published by Roth,'''' including some of those tabulated by Bischof, we ob- 

 tain 0.2033 part per thousand as the average of total solids; and 0.09598 

 jjarts per thousand as the average of calcium carbonate. In both Ameri- 

 can and European river waters, so far as can be determined from the data 

 at hand, the average of total solids in solution is 0.1888, and the average of 

 calcium carbonate 0.088765 part per thousand. These figures may be 

 assumed to represent the average composition of normal rivers. It will be 

 noticed that the average for calcium carbonate amounts to nearly one-half 

 of that for total solids. 



Knowing the volume of a stream and the percentage of mineral matter 

 it holds in solution, we can ascertain the amount of dissolved matter that 

 it contributes annually to the ocean or enclosed lake to which it is trib- 

 utary. To one unfamiliar with such investigations the amount of solid 

 matter thus annually transported in an invisible state from the land to the 

 sea will appear truly astonishing. 



The Thames at Kingston, as determined by the Royal Rivers Pollution 

 Commission of Great Britain, has an average daily flow of 1,250,000,000 

 imperial gallons; the water contains of inorganic impurities 19, and of or- 

 ganic and volatile 1.68 grains per gallon. This is equivalent to 3,364,286 

 pounds, or 1,682 tons (of 2,000 pounds each), of inorganic matter daily; of 

 this two-thirds, or 1,121 tons, are calcium carbonate, and 271 tons calcium 

 sulphate. 



The average flow of the Croton River, which supplies New York City, 

 is 400,000,000 gallons daily, which contain 365,428 pounds; or nearly 183 

 tons of impurities; of these 47 tons are calcium carbonate.^® 



"Chemical Geology, Euglish edition, LoDilon, 1354, Vol. I, pp. 76 and 77. 

 "Chemical Geology, Berlin, 1879, Vol. I, pp. 450 and 457. 

 '^Rep. American Public Health Association, Vol. I, p. 554. 



