TREASURE FROM THE SEA 



J. W. Chanslor 



Maritime Safety Division 



U. S. Naval Oceanographic Office 



The sea is "water" only in the sense that water is the dominant 

 substance present. Actually, it is a solution of gases and salts in 

 addition to vast numbers of living organisms, the majority of which 

 are quite minute. Since the beginning, materials in solution and in 

 suspension, carried by rivers, have been deposited in the oceans and 

 seas of the world. It is to the wealth related directly and indirectly 

 to these materials that this article is directed, rather than pirate 

 treasure. 



CUBIC MILE 



Few consequential resources ashore are so little developed as 

 those of the sea. Taken as a whole, the quantities of materials avail- 

 able from the sea are so gigantic that they can hardly be computed. 

 Listed are a few of the more abundant compounds that are present 

 in a single cubic mile of sea water. A cubic mile is a measure of 

 enormous size and one rather difficult to visualize. It may be of 

 some help, however, to point out that a body of water 26 miles long, 

 10 miles wide, and 3.3 fathoms deep would contain appro.ximately 

 one cubic mile. 



Approximate amount of minerals in one cubic mile of sea water 



Sodium Chloride (common salt) 128,000,000 tons 



Magnesium Chloride 17,900,000 tons 



Magnesium Sulphate 7,800,000 tons 



Calcium Sulphate 5,900,000 tons 



Potassium Sulphate 4,000,000 tons 



Calcium Carbonate (lime) 578,832 tons 



Magnesium Bromide 350,000 tons 



Bromine 300,000 tons 



Strontium 60,000 tons 



Boron 21,000 tons 



Fluorine 6,400 tons 



Barium 900 tons 



Iodine 100 to 1200 tons 



Arsenic 50 to 350 tons 



Rubidium 200 tons 



Silver up to 45 tons 



Copper, Lead, Manganese, Zinc 10 to 30 tons 



Gold up to 25 tons 



Uranium 7 tons 



In the above table, the first five items show what great quantities 

 of minerals can be extracted from sea water. With the exception 

 of sodium chloride, however, these minerals still exist in dilute 

 amounts compared with the medium in which they are suspended. 

 Nevertheless, it has been possible to extract some of these products, 

 such as sodium chloride, magnesium, and bromine from the sea. 

 Other minerals, such as potassium and iodine, can be obtained with 

 less expense from terrestrial salt deposits. These deposits of salt are, 

 of course, the remains of ancient seas. Consequently, when their 

 stocks are exhausted, we shall have to turn directly to the abundant 

 seas. 



MINING THE SEA 



It should not seem strange to consider the sea as a vast mineral 

 mine. For, our oceanic waters contain more minerals than have 

 ever been mined by man. 



On land, when minerals are taken from mines, they are not re- 

 placed. And. as this ore is used up, industry is forced to use lower 

 and lower grades, making extraction more difficult and expensive. 



Such, however, is not the case with our seas. For, as previously 

 mentioned, the sea is a great reservoir constantly receiving the pro- 

 ducts of erosion, decay, and runoff. Although in great dilution, here 

 is a source of almost limitless amounts of all the minerals and metals 

 we use. 



Mining the endless resources of the sea is not nebulous hope, but 

 rather a growing actuality, with continued expansion— the frontier 

 of chemists. 



SALT.— The most common product from the sea is salt or sodium 

 chloride. Every gallon of sea water contains just over a quarter 

 of a pound of common salt. Or, stated differently, each cubic mile 

 of sea water contains enough salt to supply the world's needs for nine 

 years. Each year millions of tons are mined in places like San Fran- 

 cisco Bay, where sea water is trapped in shallow ponds and evaporated 

 by solar heat. The world uses some 35,000,000 tons of salt each year, 

 but only a comparatively small amount of this comes directly from the 

 sea. Salt mined underground such as in Kansas, Michigan, Ohio, 

 etc., is obtained from brine wells precipitated by ancient seas. Some 

 of these deposits, 350,000,000 years old, are occasionally 1,000 feet 

 thick and a mile or more below the present surface of the earth. 



Salt is a prerequisite to good health, as well as a preservative 

 and condiment. Some of the earliest trade routes of the world were 

 established for the desire of this "luxury." When man's diet con- 

 sisted of uncooked food, the fresh meat he consumed provided his 

 required salt. But, when he began to boil his food, a considerable 

 amount of the salt was lost. History does not clearly state when 

 man first began to gather salt from the sea, but records do indicate 

 that the Chinese obtained it prior to 1,000 B. C. by evaporation. 



Upon the simple evaporation of sea water, the mixture of salts 

 that remains is not at all like the table salt to which we are ac- 

 customed. Sodium chloride has a brackish but not bitter taste. On 

 the other hand, calcium and magnesium salts are very bitter and 

 hence the higher their content in common salt, the more bitter its 

 taste. In addition to being quite bitter, calcium and magnesium 

 salts are highly hygroscopic, and salt in which their contents are 

 high is normally wet, refusing to "run." Several different grades 

 of edible salt are manufactured, all predominately sodium chloride 

 but none pure sodium chloride. Various procedures are undertaken 

 during evaporation, giving different degrees of purification. Also, 

 other chemicals are added for special purposes. 



MAGNESIUM.— The most spectacular treasure from the sea 

 is perhaps magnesium. The Dow Chemical Company began the 

 manufacture of magnesium from sea water at Freeport, Texas in 

 January 1941. This was the first time a metal had been produced 

 in commercial quantities from sea water. There are currently four 

 companies in the United States extracting magnesium hydroxide 

 from the sea. 



To make metallic magnesium from sea water, it is necessary 

 to separate the magnesium from the sea water. This is accomplished 

 by treating the sea water with lime, precipitating magnesium as 

 "Milk of Magnesia." The milk of magnesia is treated with hydro- 

 chloric acid and evaporated to dryness as magnesium chloride. This 

 salt is put through electrolytic cells where the electric current turns 

 the compounds into metallic magnesium. In a million pounds of sea 

 water there are approximately 1,000 pounds of magnesium. 



Had it not been for World War II, the magnesium in the sea 

 might well have remained there. But, with the war came great 

 demands for metallic magnesium for use in incendiary bombs, flares, 

 etc. This new and sudden demand ran into millions of pounds per 

 year. A very significant contribution to winning the war can be 

 attributed to sea water magnesium, and the ability of the United 

 States to master conversion problems before its enemies did. 



BROMINE.— Of the many elements present in sea water, the 

 first to be recovered systematically was bromine. Unlike many 

 products from the sea, there has long been a demand for bromine 

 compounds due to their sedative properties. They are also used 

 in photography and in the manufacture of certain dyes. Bromine 

 was formerly extracted from the ash of burned seaweed. Later it 

 was obtained from brine or salt deposits of ancient seas. The tech- 

 nical experience gained by the Dow Chemical Company in the ex- 

 traction of bromine from brine wells, was of great value when the 

 demand for this product exceeded the supply. 



During the 1920's, the General Motors Corporation, while trying 

 to improve gasoline for use in more powerful internal combustion en- 

 gines, discovered that tetraethyl lead added to gasoline allowed much 

 higher compression ratios to be obtained and prevented "knocking." 



