434 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1941 



surprising that the Chinese attribute vermifugal properties to marine 

 algae in general. 



At one time iodine, widely used in medicine, was derived from the 

 seaweeds. In 1804 a French chemist named Bernard Courtois began 

 work on nitrate of sodium, the process consisting of decomposing 

 nitrate of calcium by the carbonate of sodium obtained from the 

 burnt ashes of the seaweeds called kelp. In the course of his work, 

 he observed that the iron vessels which he was using became corroded 

 if the liquors from which the sodium salts had been crystallized were 

 left in them for a long time. He found that these liquors when dis- 

 tilled with sulfuric acid liberated a body with a beautiful blue vapor. 

 He examined this vapor and discovered some of its properties; for 

 example, its formation of a detonating compound with ammonia. 

 He gave a specimen of it to Clement who read a paper on it, but the 

 rest of the investigation concerning it was carried on by Gay Lussac. 

 Iodine was first employed as medicine by Coindet, of Geneva. 



Iodine is a nonmetallic element which exists in certain marine algae 

 particularly the kelps and rockweeds. These seaweeds are the largest 

 of the algae that belong to the family Laminariaceae. The kelp in- 

 dustry for many years was an important one as well as a lucrative 

 one in parts of England, Ireland, Northern France, Norway, and Den- 

 mark. It was engaged in by the peasants of the sea coasts who 

 gathered the kelp by hand or by boat and burned it in covered 

 trenches by the shore. After a time, the chemists found it cheaper to 

 derive their iodine from the saltpeter beds of Chile and the great 

 kelp industries of northern and western Europe began to decline. 

 Brown seaweeds are still gathered for their iodine on the coasts of 

 Japan, Scotland, Ireland, and Norway. 



Iodine probably exists in seaweeds in the form of sodium iodide. 

 Besides iodine, the ashes contain sodium carbonate, sodium chloride, 

 potassium chloride, sodium sulfate, and other salts in small amounts. 

 The deep sea Fuci contain the most iodine, and when these are burned 

 at a low temperature for fuel as on the island of Guernsey, their 

 ashes form more iodine than does ordinary kelp. In Japan, the sea- 

 weeds most used are Echlonia (pi. 9, fig. 1) and Sargassum which 

 contain about 0.14 percent of iodine. In France, species of F'u<nis 

 are employed. The ash contains sometimes about 5 percent of iodine, 

 but usually below 1 percent. During World War I, the United 

 States began to utilize its vast groves of kelps, Macrocystis (pi. 7, 

 fig. 1) and Nereocystis (pi. 9, fig. 2), which grow on the Pacific coast. 

 The ash was burned to obtain potassium salts and iodine, but as 

 soon as the war ended, the production of potash and iodine from 

 kelp slowed down, as at the present prices for potash the utilization 

 of kelp did not seem profitable. 



