UTILIZATION (>K SEAWEEDS IN THE UNITED STATES. 



175 



coasts, it is quite remarkable thai n<> one has undertaken the manufacture of this 



product. Supplementary to the outlineof the Japanese thud of preparing iodine, 



it is therefore deemed advisable to give some account of the iodine industry in 

 Scotland. 



Nearly all marine algse contain iodine, but a few have such a comparatively large 

 quantity that they are utilized almost exclusively. In the early days of iodine and 

 soda manufacturing on the Scotch coasts, only " rockweeds" or " wrack." technically 

 known as cut-weed kelp, were used; they represented three species— namely, Fucus 

 vesiculous, F. serratus, and Ascophyllum nodosum.. Stanford lls.s-1-) gives an 

 interesting historical account of this industry: 



This crude substance (kelp), which for many years made the Highland estates so valuable, was 

 :il first made as tin- principal source of carbonate of soda. At the beginning of the century it realized 

 620 to £22 per ton, and the Hebrides alone 

 produced 20,000 tons per annum. The im- 

 portation of barilla then began, and for the 

 twenty-two years ending 1822, the average 

 price was tilt 10s. The duty was then taken 

 off barilla, and the price of kelp fell to £8 10s. ; 

 and in 1823, on the removal of the salt duty. 

 it fell to £3, and in 1831 to i'2. Tt was used 

 up to LS4.T in the soap and glass factories of 

 Glasgow, for the soda. Large chemical works 

 were then existing in the island of Barra for 

 the manufacture of soap from kelp, ami a very 

 large sum of money was lost there. In the 

 meantime, soda was being largely made by 

 the Le Blanc process, and superseded kelp, 

 which was always a most expensive source, 

 yielding only about 4 per cent, often less than 

 1 per cent. It must have cost the soap- 

 makers what would be equal to £100 per ton 

 for soda ash, the present price of which is £6. 



The manufacture of iodine and potash 

 salts then began to assume some importance, 

 but the kelp required was not the same, that 

 which contained the most soda containing the 

 least iodine and potash. Chloride of potas- 

 sium, the principal salt, was at one time worth 

 £25 per ton. The discovery of the Stassfurt 

 mineral speedily reduced this price to about 



a third, anil the further discovery of bromine in this mineral also reduced the price of that element 

 from :;ss. per pound to Is. 3d., its present price. The amount of bromine in kelp is small, about a 

 tenth of the iodine, and not now worth extracting. Large quantities are now produced in Germany 

 and America. More recently, the manufacture of iodine from the caliche in Peru has attained large 

 proportions, and has so far reduced the price of that article as to make its manufacture from kelp 

 unremunerative. 



The plants were cut at low tide, floated ashore, dried and burnt. This kelp, 



burnt into a dense fused slag, contained the most carbonate of soda, and was that variety which 

 employed so many poor crofters and cotters, and enriched so many Highland lairds. It is now worth- 

 less, and the Fuei, which hang from the rocks at low water in luxurious festoons, are now entirely 

 unutilized. 



Rock weed ' Fuctui i esiculo " 



