of the Eio Colorado. It is difficult to say why the Arabian Gulf 

 should be called the Eed Sea, unless it be that it contains a good 

 deal of a microscopic alga (called Trychodesmum erythrceum) of a 

 reddish colour. 



The chemical composition of sea water is extremely complex, 

 owing to the numerous and ill understood combinations and double 

 decompositions which occur among its various bases and acids. 

 Analysis shows it to consist of certain simple substances, such as 

 Chlorine, Bromine and Iodine, and four principal bases, soda, 

 magnesia, lime, and potass combined with sulphuric acid. Chlorine 

 is by far the most abundant principal in sea water, no less than 

 half the weight of its saline matter being due to its presence. 

 Soda is the next in quantity, then follow magnesia combined with 

 sulphuric acid, and two substances much more rare, lime and potass. 

 Sea water necessarily contains traces, more or less abundant, of every 

 soluable substance in the world, including gold and silver. It was 

 only in the last century that the silver fcund to exist in sea water 

 was ascribed to the wrecks of the numberless vessels containing 

 specie, especially to the rich Spanish galleons which had sunk with 

 their cargoes of doubloons ! The copper sheathing of ships often 

 becomes slightly coated with an amalgam of silver, which, owing 

 to galvanic action, rapidly deteriorates its quality. Small as is the 

 quantity of silver in a gallon of sea water, it is nevertheless cal- 

 culated by a I rench chemist, that the ocean contains more silver 

 in solution than there is in circulation among all the nations of the 

 earth. In fact no less a quantity than two millions of tons. So 

 enormous is the bulk of the ocean, that if aU the salt it contains 

 could be extracted and spread over the surface of the earth, it 

 would form a layer of 30 feet in depth. — 1000 grains of sea water 

 contain : — 



Water 9620 



Chloride of Sodium 271 



Chloride of Magnesium 5"4 



Chloride of Potassium 0*4 



Bromide of Magnesia O'l 



Sulphate of Magnesia ... .. 1'2 



Sulphate of Lime O'S 



Carbonate of Lime 0"1 



Leaving a residuum of — a'9 



consisting of sulphuretted hydrogen, hydrochlorate of ammonia, 

 iodine, oxide of iron, copper, and silver. 



Our seas thus contain the most powerful mineral waters which 

 exist, and if sea water were only expensive, or Hmited in quantity, 

 it would be credited with the cure of aU the ills which flesh is heir 

 to. Thousands of invalids would rush to any inland town posses- 

 sing a spring half as rich in mineral matter as the sea, and yet it 

 is hardly ever taken as a medicine, except by sailors, who know its 

 value. In large doses sea water acts as an emetic ; the concentra- 



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