558 Transactions of the Canadian Institute. [Vol. VII. 



the volume of water, and, evaporation keeping pace with the inflow, a 

 concentration of the salts held in solution took place. An examination 

 of the present sources of inflow shows that these do not contain the 

 sodium, potassium, calcium and magnesium in the relative proportions 

 which are found in the lake. Gilbert estimates that it would take only 

 eighteen years to give the lake through its fresh water inflow, all the 

 calcium it now contains and that 850 years would to this end be re- 

 quired for magnesium. He does not deal with the case of the potassium 

 of which the analyses he reports show only traces in the inflow water, 

 but this also may have been due to faulty methods of determining that 

 element. These latter seem to be the only explanation for the great 

 discrepancy between the amounts of potassium found by Talmage* in 

 1889 and Bassettf in 1873]:. 



Short as is the extreme period required by Gilbert's calculations to 

 affect all the changes in the composition, it has epitomized the history 

 of the ocean. Even if we postulate that the primitive rock crust of the 

 globe in pre-Cambrian times contained more sodium chloride than what 

 is found now in Archaean formations, there is also more of this salt in 

 the strata of later geological periods which cover the drainage area of 

 Utah Salt Lake. Of course there is not a complete parallel between 

 the latter and the ocean, for the relative proportions are not exactly the 

 same, but their approximate similarity is striking, and, it may be added, 

 very convincing as to the extreme probability of the thesis maintained 

 above. § 



TABLE A. 



RIVERS. 



Na. K. Ca. Mg. SO3. CI. Si. Fe. 



1. St. Lawrence .. . 100 22.9 638.0 143.4 'S^-o 223.0 343-° 



2. Ottawa 100 64.2 416.7 82.5 67.3 224.3 402.0 



3. Mississippi 100 35.5 462.0 82.0 17. i 8.4 86.4 17.0 



4. Amazons 100 72.6 1,089.0 i35-6 36-0 90.0 



5. Nile 100 22.2 75.1 41.5 18.5 16.0 44.4 



6. Assinaboine 100 10.5 122.0 69.4 127.9 SO-O 



7. Red River 100 12.3 133.3 83.2 190.0 91.4 



8. Nineteen Rivers 



(Murray) 100 38.6 590.9 134.2 197.6 53.5 145.3 37.9 



* Science, Vol. 14, i88q, p. 445. 



t Chemical News, Vol. 28, 1873, p. 236. 



See Table B, Utah Salt Lake, 26 and 27. 



§ In Lake Shirwa, according to J. E. S. Moore, (" The Tanganyika Problem," 1902, p. 22,) we have a 

 lake which was once fresh, but has become salt through the loss ot its outlet. So far as I know no 

 analyses have been made of its waters. 



