SALTNESS OF THE . SEA. IJ 



' .The water of the Mediterranean contains more salts than that of 

 tne ocean. 



The following are, according to M. Usiglio who was one of a 

 commission sent to examine the different kinds of salt water in the 

 south of France the component parts of one hundred gallons of 

 Mediterranean water : 



Ibs. 



Chloride of sodium 29-524 



Chloride of potassium . . . . . . . . . 0-405 



Chloride of magnesium 3 '2 19 



Sul^nate of magnesia 2-477 



Chloride of calcium G'oSo 



Sulphate of lime I- 557 



Carbonate of lime 0*114 



Bromide of sodium 0*356 



Protoxide of iron ..,.., , . o'ooi 



43735 



We conclude, from the quantity of sea salt contained in the 

 water of the ocean, that if it were spread over the surface of the 

 globe, it would form a layer of more than thirty feet in height. 



The salt contained in sea water gives it a greater density than 

 fresh water; its average specific weight is 1-027. The density of 

 the water of the Mediterranean is, according to M. Usiglio, 1*025 

 when at the temperature of seventy degrees. But the saltness of 

 the sea varies very much under the influence of a great many 

 local circumstances, among which we must count principally cur- 

 rents, winds favourable to evaporation, rivers coming from the 

 continents, &c. 



It has been remarked that the sea is less salt towards the poles 

 than at the equator ; that the saltness increases, in general, with the 

 distance from land, and the depth of the water ; that the interior 

 seas, such as the Baltic, the Black Sea, the White Sea, the Sea of 

 Marmora, and the Yellow Sea, are less salt than the ocean. The 

 Mediterranean is an exception to this last rule ; it is, as we have 

 seen, salter than the ocean. This difference is explained by the fact 

 that the quantity of fresh water brought into it by rivers is less than 

 that lost by evaporation. The Mediterranean must therefore grow 

 salter with time, unless its water is discharged into the ocean b y a 

 counter current, which would run under the current coming from the 

 Atlantic by the Straits of Gibraltar. 



The Black Sea, on the contrary, the water of which has a density 

 of only i f oi3, receives from rivers more fresh water than it loses by 



