CHAPTER XII. 



SEAWEED AND ITS USES. 



Various uses of Seaweed Sea wrack for packing and upholstery For manure 

 Kelp and iodine Carrageen moss Seaweed for food Large employ- 

 ment in China and Japan Gelose Other applications of seaweed. 



SEAWEEDS are largely employed in Europe and the ex- 

 treme East in industry, agriculture, and manufactures. 



The marine plants are of much more importance than is 

 generally supposed, and it is doubtful whether they may 

 not yet be further utilized to advantage. Liebig, in his 

 " Familiar Letters on Chemistry," says, " Every one knows 

 that in the immense, yet limited, expanse of the ocean, 

 whole worlds of plants and animals are mutually dependent 

 upon, and successive to, each other. The animals obtain 

 their constituent elements from the plants, and restore 

 them to the water in their original form, when they again 

 serve as nourishment to a new generation of plants. The 

 oxygen which marine animals withdraw in their respiration 

 from the air, dissolved in sea water, is returned to the 

 water by the vital process of sea plants ; that air is richer in 

 oxygen than atmospheric air, containing 32 to 33 per cent, 

 while the latter only contains 21 per cent The oxygen 

 now combines with the products of the putrefaction of dead 

 animal bodies, changes their carbon into carbonic acid, 

 their hydrogen into water, while their nitrogen assumes 



