THE OCEAN: ITS POTENTIALITIES AND PRODUCTS 9 



saved the fur seal. Now the United States has an annual revenue of over a million 

 dollars a year from the Pribilof Island rookeries (Chapter 34). 



Hair seals and walrus furnish hides from which valuable leathers are prepared. 



Whale Oil and Meal. Whaling played a very important part in the early eco- 

 nomic history of the United States. The New England whalers searched the oceans 

 for whales and furnished a large part of the world with illuminating oil, candles, 

 and whalebone. With the discovery of petroleum the importance of deep-sea 

 whaling rapidly diminished. However, the invention of the harpoon-gun in 1874 

 gave the industry new life and the discovery about a decade ago of a practical 

 means of hardening the oil by hydrogenation made possible the annual prepara- 

 tion of $70,000,000 worth of whale products. 



Porpoises, dolphins, and blackfish furnish valuable oil and leather; but, as 

 relatively few are captured in any one locality, the fishery is of little commercial 

 importance. 



Tortoise Shell. Turtle fisheries are established in nearly all tropical waters. 

 Valuable meat is obtained from the green turtle and an ornamental material, 

 tortoise shell, is procured from the shields of the carapace of the hawksbill turtle 

 (Chapter 31). 



Sponges. Sponge fisheries are of importance at Key West, Nassau, Algeria, and 

 in the Mediterranean (Chapter 35). The limited extent of the fishery, together 

 with the great demand for sponges, keeps the price high. Since sponges can be 

 cultivated, more interest should be given to the fishery so that an industry of 

 great commercial value might be developed. 



Coral. The Japanese and Italian coral fisheries have furnished a valuable orna- 

 mental material for many centuries. Formerly, the Mediterranean Sea yielded the 

 major portion of the world's production, but now Japanese coral is of major com- 

 mercial importance ( Chapter 9 ) . 



Salt and By-products. The ocean is a great potential source of common salt, 

 potassium, magnesium and calcium salts, iodine, and bromine. At present, com- 

 mon salt is the most important inorganic product obtained by the evaporation of 

 sea water; this industry is described in Chapter 2. While salt is usually a cheap 

 product, its manufacture is essential for human life. 



In hot arid countries where large tracts of level land lie close to the sea salt is 

 usually made on a large scale. In certain districts of Portugal, Spain, France, China, 

 and California there are valuable salines. Valuable by-products, such as potassium 

 and magnesium salts and iodine, may be prepared from the mother liquors re- 

 maining after the crystallization of the salt. As yet, the industries have been slow 

 to utilize these salts. In California, magnesia, magnesium salts, and magnesium 

 oxychloride cement are manufactured in large quantities from the bittern (Chap- 

 ter 3). 



Vegetable Products. Seaweeds are more extensively utilized in Japan than in 

 any other country. If they were harvested in similar quantities in other parts of 

 the world, their annual production would reach a very high figure indeed. In addi- 

 tion to being almost universally eaten algae find numerous other uses in Japan. 

 An important glue, or size, funori, is manufactured from certain species. Agar, 

 or kanten, is prepared on a large scale. This substance, as well as being a food, 

 finds extensive use as a medicine and in the preparation of media for bacterial 

 growth. 



