1869.] and their Uses. 337 



We are told that " the red weed kelp is the only really paying 

 trade; nevertheless, some black weed kelp is manufactured, but it is 

 most unproductive, for, on account of the price for soda, it is never 

 worth more than \l. 10s. to 21. 10s. a-ton, and even at these prices 

 there is not a good demand for it. Previous to the repeal of the 

 salt duty the soap-maker obtained his alkali (soda) from ' Spanish 

 barilla,' or kelp ; Yar-Connaught in those days yielded from 3000 

 to 4000 tons of black weed kelp annually, and Scotland about 

 20,000 tons per annum ; but now from Prussia and Austria vast 

 mineral supplies of alkaline salts are obtained, therefore black weed 

 or reeshagh kelp, chiefly valuable on account of these salts, are 

 scarcely worth making." 



Between the former prices for the black weed kelp (about 16^. 

 a-tou) and that now paid for the red weed kel]) (4Z. a-ton) there is 

 a vast difference, and seemingly the former ought to have been the 

 most productive trade. Nevertheless, it was not to the manufac- 

 turers, unless they were also the proprietors of the land, for as the 

 black weed grows between high and low water mark the cutters of 

 the weed had to pay a high rent to the proprietors of the land, 

 which considerably diminished the profit on the kelp ; while all 

 the red weed grows below low- water mark. However, some pro- 

 prietors charge a small sum for the right to collect the " claddagh " 

 or " seawrack," and others a royalty per ton for leave to burn the 

 kelp on their shores. 



As only a trace of the iodine compounds is found in the black 

 weed, why therefore should they occur in the red weed ? And 

 from whence does the latter receive them ? Neither of these 

 questions has been satisfactorily answered, nor does their im- 

 portance seem to have been considered. As the " black weed " is 

 daily lying exposed many hours to the atmospheric agencies, 

 possibly this exposure may be unfavourable to the secretion of the 

 iodine producing salts ; this suggestion, however, seems to be con- 

 troverted by none of these compounds occurring in the " reeshagh " 

 — The " red weed " apparently cannot receive the iodine from any 

 particular rock, as this class grows luxuriantly on granite, gneiss 

 schist, limestone, sandstone, slate, and in fact on every rock found 

 on the west coast of Ireland, even on blocks in the gravel, if 

 they are heavy enough to anchor the weed and prevent it being 

 wafted away by the tidal currents. Iodine is rather rare in nature ; 

 Apjohn says " Iodine is found in nature only in a state of combina- 

 tion. In 1811 it was discovered by Courtois in kelp, in which it 

 exists united to sodium and potassium ; and it has since been found 

 in combination with the same metal in sea-water, several salt 

 springs, and the ashes of the sponge. M. Bussy has detected it in 

 the coal of Allier, and M. Duflos in the coal of Silesia. Lastly, the 



