16 THE OCEAN WOELD. 



iron, copper, and even silver in various quantities and proportions, 

 according to the locality of the specimen. In examining the plates of 

 copper taken from the bottom of a ship at Valparaiso, which had been 

 long at sea, distinct traces of silver were found deposited by the sea. 

 Finally, we find dissolved in the ocean a peculiar mucus, which seems 

 of a mixed animal and vegetable nature, and is evidently organic 

 matter proceeding from the successive decomposition of the innumerable 

 generations of animals which have disappeared since the beginning of 

 the world. This matter has been described by the Count Marsigli, 

 who designates it sometimes under the name of glu, and sometimes as an 

 unctuosity. It is the " ooze " of marine surveyors, and consists chiefly of 

 carbonate of lime, ninety per cent, of which is formed of minute animal 

 organisms. Its mealy adhesiveness results from the pressure of the 

 superimposed water. The numerous salts which exist in the sea can 

 neither be deposited in its bed, nor exhaled with the vapour, to be 

 again poured upon the soil in showers of rain. Particular agents retain 

 these salts in solution, transform them, and prevent their accumula- 

 tion. Hence sea water always maintains a certain degree of saltness 

 and bitterness, and the ocean continues to present the chemical 

 characters which it has exhibited in all times, varying only in certain 

 localities where more or less fresh water is poured into the sea basin 

 from rivers : thus the saltness of the Mediterranean is greater than 

 that of the ocean, probably because it loses more water by evaporation 

 than it receives from its fresh-water affluents. For the opposite 

 reason, the Black and the Caspian Seas are less charged with these 

 salts. The Dead Sea is so strongly impregnated with salt that the 

 body of a man floats on its surface without sinking, like a piece of 

 cork upon fresh water. The supposed cause is excessive evaporation 

 and the absence of rivers of any importance. 



The saltness of the sea seems to be generally less towards the poles 

 than the equator ; but there are exceptions to this law. In the Irish 

 Channel, near the Cumberland coast, the water contains salt equal to 

 the fortieth of its weight ; on the coast of France, it is equal to one 

 thirty-second ; in the Baltic, it is equal to a thirtieth ; at Teneriffe, a 

 twenty- eighth; and off the coast of Spain, to a sixteenth. Again, in 

 many places the sea is less salt at the surface than at the bottom. In 

 the Straits of the Dardanelles, at Constantinople, the proportion is as 

 seventy-two to sixty-two. In the Mediterranean, it is as thirty-two 



