138 Iodine in Aluminous Slates. 



nious idea respecting the part which the species of Fucus 

 take in the formation of aluminous slates. It consisted in 

 admitting that the fuci, after having accumulated in their 

 substance the sulphates contained in sea water, converted by 

 putrefaction after death the sulphate of potash into siil- 

 phuret of potassium ; this in turn precipitated the iron con- 

 tained in the sea water in the state of sulphuret of iron, 

 which became mixed with the clay and other substances, 

 some of which are organic, and owe their presence to the 

 putrefaction of the fuci. Chemical analysis, by demonstrat- 

 ing the presence of iodine in aluminous slates, added a new 

 and powerful argument in favour of this hypothesis. The 

 ash of fuci contains, in fact, a considerable quantity of iodine, 

 which might lead to the supposition that this substance 

 would be also found, at all events in small quantity, in these 

 deposits, if the fuci really take that part in the formation of 

 these slates, which M. Forchammer attributes. Now, M. 

 Genteles, while engaged in some researches on the manufac- 

 ture of alum, has isolated iodine from the aluminous slates 

 of Latorp in Sweden. This discovery, joined to that of 

 Duflos, of the presence of iodine and bromine in the coals of 

 Silesia, will suffice to draw the attention of geologists to the 

 confirmation which they furnish of the ideas of M. Forcham- 

 mer, respecting the formation of the aluminous schists.^ 

 ^vanberg^s Jahrsbericht. 



Iodine in the Atmosphere, — Bain, Dew^ and Snow. 



Mr Chatin, who followed with so much success MuUer in 

 his investigations in the distribution of iodine, has announced 

 to the French Academy of Sciences the important fact of the 

 existence of that substance in the atmosphere, also in rain- 

 water, dew, and snow. It thus appears, that iodine is very 

 generally distributed, having been detected in the waters of 

 the ocean, lakes and springs, in the solid crust of the earth in 

 various mineral compounds, — in many plants, chiefly, if not 

 entirely, aquatic, in animals, and now as an ingredient in the 

 earth's atmosphere, — and in rain, dew, and snow. 



We may add, that the late discovery in the air we breathe 

 of iodine and ozone, shews the importance of a more continued 

 chemical investigation of the atmosphere, particularly during 



