286 THE MANUFACTURE OF KELP. 



known to chemists, but, probably from tbe fact that it is conducted on 

 desolate shores, at a considerable distance from centres of civilisation, it 

 has not yet received that attention its importance demands. 



The manufacture is at present limited to a few parts of Great Britain, 

 the western and northern islands of Scotland, the north-west coast of 

 Ireland, and Guernsey. 



In the Scotch islands the weeds are collected in the summer, dried in the 

 sun, and burned in shallow rectangular pits ; the fire requires a very high 

 temperature, and the salts enter into igneous fusion ; the fused mass is 

 broken up by throwing water on it, and the kelp thus produced is a vitreous 

 conglomerate, in the best specimens of which the carbonised stems of 

 Laminaria digitata may be distinguished. It is of this plant — called 

 bardarrig or the " drift weed " — that the most valuable kelp is made ; if 

 unadulterated it will yield the lixiviator from 10 lbs. to 15 lbs. of iodine 

 per ton. The "cut-weed "is the Laminaria saccharina, called " Slaten- 

 varra," but this is mixed with several Fuci, and generally the latter pre- 

 dominate ; the kelp produced from it does not afford more than half the 

 iodine yielded by the former. 



The kelp in the north-west of Ireland is made principally from the 

 "drift weed" consisting of "sea rods," as the Laminaria is there called ; it 

 is burnt in small heaps, and at a lower temperature ; the kelp produced is, 

 consequently, more porous and much richer than that from the western 

 islands. Some of the drift weed, too, is stacked in the winter for burning 

 in the summer ; a portion of the Irish kelp is made from " cut weed," 

 principally the Fuci. 



Professor Graham first directed attention to the seaweed ash of 

 Guernsey as the richest source of iodine ; this results from the fact that 

 the Laminaria digitata is used, and a very low heat is employed in the 

 production of the ash. Mr. Arnold, of Guernsey, is the only lixiviator of 

 kelp there, and he informed me that the local government had more than 

 once tried to stop the lixiviation altogether, and owing to the peculiar 

 laws of that island he is unable to carry it to any great extent. A large 

 manufactory in one of the Channel Islands could produce immense quan- 

 tities of iodine and potash, and the insoluble ash would still be retained 

 as manure. 



I am indebted to Mr. William Paterson, of Glasgow, who alone 

 lixiviates nearly four-fifths of the kelp of commerce, for the following 

 statistics of the actual annual average amounts of kelp paid for, with the 

 prices on the kelp shores. Those prices do not include freight and other 

 charges incidental to the carriage of kelp to Glasgow. The average is 

 taken on the last two years. 



"Western Islands. 



1,800 tons cut weed kelp, at £2 £3,600 



800 „ drift weed „ „ 4 3,200 



400 „ „ „ „ 6 2,400 



3,000 £9,200 



