24 SOILS. 



It will be noted that in all the drain waters, lime is the in- 

 gredient most abundantly leached out, and as reference to the 

 acids shows, mainly in the form of carbonate, also in that of 

 sulfate. Magnesia is next in amount among the bases; next 

 in amount is soda, largely in the form of sodium chlorid or 

 common salt. Potash is present only in small but rather uni- 

 form amounts. Of the acids the carbonic is the most abundant, 

 sulfuric next; chlorin and silicic acid come next, in about 

 equal amounts. Nitric acid passes off in small, but still rela- 

 tively considerable amounts. 



Comparison of the drain waters with the river waters, while 

 showing a general qualitative agreement, also shows a marked 

 diminution of total solids (from 285.7 to 188.7; hence " soft 

 river water"), and especially of lime (from 107.6 to 43.2), 

 together with the carbonic acid with which it is mostly com- 

 bined ; indicating a deposition of lime carbonate in the river 

 deposits or alluvial lands. There is, on the other hand, little 

 if any general difference in the magnesia content of the two 

 classes of waters ; nearly the same is true of soda, so that these 

 two bases really show a considerable relative increase when 

 the diminished total is considered. Potash remains about the 

 same all through, viz. two parts or a little more ; phosphoric 

 acid shows a fraction of one millionth ; nitric acid varies greatly 

 but is usually higher in the drain waters, sometimes showing 

 a heavy depletion of the land by the leaching-out of this im- 

 portant plant food. 



It has been computed by John Murray, as quoted by Rus- 

 sell, 1 that the volume of water flowing into the sea in one 

 year, including all the land areas of the earth, is about 6524 

 cubic miles. From the average composition of river waters 

 as given above, it would follow that nearly five billions (4,975,- 

 117,588) of tons of mineral matter are annually carried away 

 in solution from the land into the sea. The amount of sedi- 

 ment carried at the same time is many times greater; in the 

 case of the Mississippi river, it is more than five times the 

 amount of the matter carried in solution. 



Comparison of the river waters among themselves shows 

 less of any consistent relation to climatic conditions than might 

 have been anticipated. The waters of the arctic streams 



1 Rivers of North America, p. 80. 



