166 



THE ULTIMATE SOURCE OF COMMON SALT. 



thickness of 100 feet, we get about 3 cubic miles of salt. There remain 

 the Spanish, Irish, French, Swiss, North American, Bolivian, Peruvian, 

 Mexican, African, Chinese, Burman, and Asiatic Russian, the cubical contents 

 of which I have no means of estimating, but, judging from analogy and 

 general report, I cannot be far wrong in giving them each one or two cubic 

 miles of salt, as they are local and comparatively insignificant beds, say at 

 the outside 41 cubic miles for all. We thus get 500 cubic miles of rock salt, 

 arranged as follows : — 



Deposits. 



Cis-Tndus 

 Trans-Indus 

 Carpathian 

 English 

 All others 



Cubic miles. 



10 

 20 

 416 

 3 

 41 



Doubling this for the sake of all undiscovered rock salt deposits in the 

 earth, whether above or below the bed of the sea, we get a total of 1,000 

 cubic miles of rock salt. My own impression is that this calculation errs 

 very much on the side of excess; that there is much less than 1,000 cubic 

 miles of rock salt formation extant. Nevertheless, I leave it so, as it the 

 better helps to prove my proposition, that the sea has not appreciably 

 altered in salinity, since it was first formed, down to the present time, for, 

 as before stated, the addition of 1,000 cubic miles of rock salt to the sea, 

 would be inappreciable to animal or plant life. 



J. J. L. R. 



