XC PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May I9O9, 



nothing to be desired on this point. The volume is less precisely 

 known ; it is obtained by multiplying two quantities only approxi- 

 mately ascertained — the estimated area and the estimated mean 

 depth. Sir John Murray gives it as 323,800,000 cubic miles. 1 

 Prof. Joly, using Prof. H. Wagner's estimate of the area, arrives at 

 339,248,000 cubic miles 2 ; Dr. P. W. Clarke gives 302,000,000 3 ; 

 and Dr. K. Karsten 4 307,496,000. Between the highest and the 

 lowest of these estimates there is a difference of about 10 per cent., 

 an almost negligible quantity in an enquiry like the present. We 

 may take 310,000,000 as sufficiently near the truth, and using 

 this number we obtain the results given in the following table : — 



Table I. — Quantities of substances lield in solution by the Ocean. 



Na 



... 13,982,000 X 10° tons ' 



CI 



... 25,211,400 X 10 9 tons 



Mg ... 



... 1,704.200 



Br 



87,000 



Ca 



545,120 



S0 4 ... 



... 3,508,110 



K 



504,700 



i co 3 ... 



93,048 



Thus, in round numbers, the quantity of sodium present in the 

 Ocean amounts to 14 x 10 15 tons. 



The next quantity to be determined (Na r ) is the annual amount of 

 sodium carried down into the Ocean by rivers, and with this our 

 real difficulties begin. The requisite data are scanty and imperfect. 

 For the greater number at our disposal we are indebted to the 

 Government of the United States, which pursues, greatly to the 

 advantage of its people, an enlightened policy, with regard both to 

 this and all other branches of geology. Directly we cross the 

 Canadian frontier information begins to fail ; no systematic analyses 

 of rivers have been made in the Dominion, not even of the 

 St. Lawrence, and such isolated analyses as exist are of compara- 

 tively little value. As to the composition and annual discharge of the 

 Mackenzie we know absolutely nothing. It is the same when we turn 

 to other regions under the British flag : we have no analyses of the 

 Ganges, the Indus, or the Niger, not to mention the smaller rivers 

 of British India, Africa, Australia, and New Zealand. When the 

 rivers of the British Empire have been as thoroughly surveyed as 

 those of the United States, we shall be in a better position to discuss 

 the problem before us : in the meanwhile, we must make the best 

 use of such information as we possess. 



1 Scottish Geogr. Mag. 1888, p. 39. 



2 J. Joly, Trans. Eoy. Dub. Soc. vol. vii (1899) p. 30. 



3 ' The Data of Geochemistry ' Bull. no. 330, U.S. Gecl. Surv. 1908, p. 22. 



4 'Eine Neue Berechnung der Mittlereu Tiel'e der Oceane ' Iuaug.-Diss., Kiel, 

 1894. 



