ALGAL UTILIZATION 445 



possibility of obtaining by-products. One of the new processes was 

 the distillation or char process in which the dried weed was heated 

 in a retort. Using this process ammonia, soda, potash, iodine and 

 charcoal could be obtained. Another important process involved 

 fermentation whilst in more recent times the Russians have em- 

 ployed an electrolytic method of separation. One of the principal 

 sources of iodine in Russia is Phyllophora nervosa^ a red algal 

 species that grows in the Black Sea. 



Iodine from kelp is still manufactured in Japan, about 5-7 per 

 cent of the world's supplies coming from this country. Laminaria, 

 Ecklonia and Eisenia are the genera principally employed and about 

 100 tons of iodine are produced annually. In all the weeds used as a 

 source of iodine, the iodine is most probably present in an organic 

 form. The actual amount varies from season to season, from species 

 to species, from organ to organ, and is also affected by immersion, 

 temperature and degree of wave action. In general the amount is of 

 the order of o- 13-0-23 per cent of the dry weight of weeds such as 

 Laminaria, Fucus, Ecklonia and Eisenia. 



Big areas on the Pacific Coast of North America and Canada are 

 occupied by laminarians, e.g. Macrocystis (see p. 186), Nereocystis 

 (see p. 184) and Alaria (see p. 188). About 19 10 America began to 

 pay attention to these weeds as a source of potash because of diffi- 

 culties with German suppUes. The average potash content of these 

 weeds is quite considerable and indicates the extent to which they 

 can accumulate a salt that is present in the medium in relatively 

 small amounts. The average dry weight content in Macrocystis is 

 around i6 per cent, in Nereocystis around 19 per cent and in Alaria 

 around 7 per cent. Again there is variation with season, habitat, 

 nature of the organ (stipe or blade) and so on. These weeds are 

 much easier to collect than those in Europe and generally speaking 

 some form of barge was employed which cut the weeds under water 

 (as they floated on the surface), the cut material being collected and 

 transferred to the barge by a conveyor belt. In order to obtain the 

 maximum results the weed was dried in revolving driers and then 

 treated either by a destructive distillation process or else by a fer- 

 mentation process. In the former 12 tons of dry Macrocystis yielded 

 2-3 tons of gas, 3-3 tons of ammonia, 2-i tons of tar, 3 tons of 

 potash salts, 1-2 tons of charcoal and 20 lb. of iodine. The latter 

 process was more elaborate and yielded a greater variety of pro- 

 ducts : 



