338 TJie Sea-weeds of Yar-Connaught, [July, 



iodides of silver and mercury have been met with in Mexico and 

 iodide of zinc in Silesia." In South America salts of iodine occur in 

 some rock masses ;* and for this reason some savans are favourable 

 to the idea, that the American continent is the source of supply to 

 these shores, the Gulf stream actinf^ as the carrier, and that it is 

 on the shores washed by its waters that the iodine producing fuci 

 principally grow. Against this it might be put forward, tliat the 

 Gulf stream weed " Sargassum bacciferum " is very poor in iodine. 

 This, however, may be only negative evidence, as there may be 

 richer varieties nourished in the same waters, and the '' gulf weed " 

 may be destitute of iodine for somewhat similar reasons to those 

 which prevent the black weed and the reeshagh of Yar-Connaught 

 from secreting it. 



If the iodine is brought over by the Gulf stream, naturally it 

 might be expected that it should be best developed near the source, 

 and in places farther removed it ought to be less and less, according 

 to distances ; this however does not seem to be the case, for IVIr. 

 Steven says, " Iodine although very sparingly developed in sea- 

 water is very generally distributed, and the iodine producing fuci, 

 wherever found, in Ireland, England, Scotland, Channel Islands, 

 France, or Japan, are nearly uniform in composition. In 1857 

 I analysed some specimens of L. digitata vera and L. digitata 

 stenophylla from Iceland. They were identical in every respect 

 with those found at home ; quite as rich in iodine as the best 

 Irisli." In none of the published analyses of sea- water that I can 

 find, is the quantity of iodine recorded, it being always mentioned 

 as " a trace." To settle the question whether the GuK stream is 

 the carrier of it to these shores, it seems necessary that a series 

 of analyses should be made, especially of the waters of the Gulf 

 stream, in all of wliich the quantity of iodine should be carefully 

 determined. In some medical books there is the vague statement, 

 " A cubic foot of sea- water contains "005 grain of iodine," but as 

 no authority is given, much reliance cannot be placed on its value, t 



* See 'Manual of Mhieralo<ry,' l)y .J. D. Dana, M.A., &c., &c. ; and ' Glossary 

 of Mineralogy,' by H. W. Bristow, F.IJ.S., &c., &c 



t In the journal den Connaismnc.es iV/e'd/m/es ( published in November last), there 

 is a brief notice of a method proposed by M. Moride whereby to jircpare tinctures 

 from t!ie iodine pi'oducing sea-weeds for medicinal jmrjioses. In it are first men- 

 tioned the iodine and non-iodine jiroducinp; weeds, and then the writer goes on 

 to state :—" Sea-weeds containing more chlorine and potash than soda are richer in 

 iodine than in bromine, and the contrary is the case if the plant contains more 

 sulphuric acid and sfxla than potash." (.'uided by these general facts, ]\I. I\Ioride 

 conceived tlu; idea of turning these jjlants to account in their natural ishite. that is, 

 without subjecting tlicm to a combustion which may modify them considerably, 

 and drive off their most useful volatile ingredients. M. Houssinganlt and M. 

 Humboldt had stated that in America tiic inhabitants of the Cordilleras of tiie 

 Andes were in the liabit of using the decoctions of sea-weeds, or else their alcoholic 

 tinctures, in cases of scrofula, wens, and lymphatic tendencies. These liquids are, 



