HOW THE WATERS OP THE OCEAN BECAME SALT, 



47 



ocean of various regions and far from land, it has been found 

 tbat the proportions of salts and carbonates do not mucli 

 vary. This is doubtless owing to that w^onderful system of 

 currents by which the waters are kept in a state of perpetual 

 movement, and owing to which there is a constant inter- 

 change of the v/armer waters of the equatorial regions with 

 the colder of the polar. Sea Avater is essentially a chlorinated 

 alkaline mineral water, the saline contents of which consist 

 chiefly of sodic, magnesic, potassic, and calcic chlorides and 

 sulphates ; together with a number of other substances in 

 much smaller proportion. The total amount of dissolved 

 contents in the water of the open ocean varies from about 

 28 to 39 grammes per litre. Forchhammer fixes the mean 

 amount of such contents at 34*404 grammes per litre,* and 

 the mean proportions of the constituent substances to each 

 other and 100 parts of chlorine are as foUowsf : — 



9 What is most striking in this analysis is the large propor- 

 tion of chlorine, and the greatest difficulty w^e are met with 

 m order to account for the salts of sea water is the 

 abundance of this gas. Recollecting that chloride of sodium 

 is the most abundant salt both in most salt lakes and in 

 sea water, we are justified in seeking for a solution to our 

 problem by an examination into the mode of origin of salt 

 lakes. 



10 Now there is one peculiarity which characterises all salt 

 lakes over the surface of the globe, namely — that they have 

 no outlet ; they are closed lakes. Whether we take the 

 case of the salt lakes of W estern America, those of Central 

 Asia and the Dead Sea, we shall find that they are not 

 drained by rivers. 



11 In such cases the lakes are constantly receiving supplies 

 of water from streams and springs, but do not give it off in the 

 same manner, inasmuch as it is evaporated into the air as fast 



* rhil. Trans., civ, 303 et seq. t Wait's Diet. Clam., Vol. v, 1019, 



