1st fraction- 



Calcium acetate 



Potassium chloride 



Weed 



I 



fermentation liquid 



I 



2nd fraction 

 Calcium acetate 



Calcium propionate 

 Calcium butyrate 



Calcium valerianate 



3rd fraction 



Calcium acetate 



Potassium iodide 



Potassium chloride 



Potassium chloride 



Organic acids 



Y 

 Iodine 



t 

 Algin 



The main reason for the failure of this industry, as compared 

 with the European one, was the fact that similar products could be 

 obtained more economically from other sources. 



The kelp trade in Europe and America, despite its failure, formed 

 the background to the present major kelp industry, the production 

 of alginates. This is because the same brown seaweeds form the 

 raw material. 



Algin, which is a complex compound of polymers of d-man- 

 nuronic acid, was first discovered in 1883, but whilst it is not so 

 difficult to obtain it pure under laboratory conditions, it has so far 

 proved expensive to prepare pure on a commercial scale. The 

 amount in the various Fucales and laminarians used varies from 

 15-40 per cent, though the percentage varies seasonally, being 

 lowest in spring and highest in the autumn. It is also affected by 

 habitat (exposure or protection) and depth, whilst in the case of 

 Macrocystis at least there is evidence of a variation with latitude. 

 This is probably associated with temperature and light variations 

 with latitude, since algin is regarded as one of the products of meta- 

 bolism. Algin and alginates have become of great importance since 

 1940, and whilst there has been no great change in the method of 

 collection in the U.S.A., in Europe considerable study has been 

 devoted to this problem. This is essential if continual supplies of 

 the submerged Laminaria spp. are to be available. It seems that 

 some continuous sort of grapnel method will be most reliable for 

 their collection. Nearly all the experimental work in this connexion 

 has been carried out by the Scottish Seaweed Research Associ- 

 ation. 



Various methods of extraction have been devised, but in'general 



446 



