218 THE SEAS 



As a result the enormous salinity* of over 200 parts per 

 thousand has been reached. The difference between this 

 concentration and that of sea water is due to the very small 

 volume of water in the " Dead Sea " compared with that 

 of the ocean which requires almost incalculable quantities 

 of salt to raise its salinity appreciably.) 



In the Atlantic Ocean for the same reasons as those 

 given above we find the highest salinity in the central 

 part, the Sargasso Sea, and the lowest in polar regions 

 where the continual precipitation of rain and snow from the 

 atmosphere tends to dilute the surface layers. 



Besides this common sea salt there are also many other 

 substances to be found in solution. In fact there are 

 present traces of almost all known chemical elements. 

 This is only natural when we consider that particles of all 

 kinds of substances must eventually be washed down from 

 land. Amongst these many bodies silver, radium and gold 

 are to be found. The presence of gold has of course 

 attracted men's attention, and certain unscrupulous people 

 have attempted to obtain capital from those who have been 

 misled by the visions of amassing large fortunes out of 

 sea water. Actually, however, gold is present in such 

 minute traces that the cost of its extraction would be 

 greater than the value of the amount obtained. The 

 quantities present have been variously estimated and 

 probably differ slightly from place to place. The highest 

 value obtained is one grain of gold in one ton of sea water ; 

 that is, in order to obtain sufficient gold for that very rare 

 coin, the sovereign, one would have to treat chemically 

 over 100 tons of sea water. 



It would be even less profitable to attempt to extract 

 the silver, although there is evidently plenty there in bulk ; 



* Dead Sea Salt differs from Sea Salt in the proportions of its 

 constituents. 



