333 New Cobalt Minerals. 



has recently busied himself without being able to find any 

 ground, in all the depths of astronomy, for a greater change of 

 annual heat than at the highest from 3° to 4°, and besides this 

 change could only have come on very gradually, and could never 

 have produced a sudden destruction of all organic nature. Still 

 less do we find in the unequal temperature of space surrounding the 

 earth, as assumed by Poisson, an explanation of the cause of these 

 changes of heat and cold in terrestrial bodies ; for, while a con- 

 siderable increase in the coldness of the space in which the earth 

 moves, would indeed produce a greater dissipation of the warmth 

 of the earth, a lower temperature of the polar nights and more 

 rapid loss of heat in our nights, it could scarcely be the means of 

 freezing over all the bodies of water on its surface ; and further- 

 more, these changes could only after a long space of time exert 

 an influence— and that a very gradual one — on the annual tem- 

 perature and organic life. We are thence peremptorily referred 

 to hypotheses to account for that change of temperature, but 

 hypotheses are justly regarded as unproductive, and, although 

 they played an important part in the geology of the last century, 

 yet certainly physical inquirers, who do so much honor to our age 

 as HH. Agassiz and Schimpfer, will again and again visit the 

 smooth worn rocks before they resort to this extreme expedient, 

 and repeat the question to themselves and others, whether this 

 polishing could only be the effect of ice, or whether every possi- 

 bility is cut off", that they may have been produced by water cur- 

 rents, as previous to their labors was generally believed. 



II. On two neio Cobalt Minerals^ from Moduni in Noriuay ; 

 by Hr. Prof. Dr. Wohler, (with a note by Prof. Shepard,) 

 from a letter to Hr. Dr. Blum. 



We were too late with our examination of the new Modum 

 Cobalt minerals, which you gave me last autumn. My analysis 

 of them had been completed for some time, and I was about ar- 

 ranging the results, when I came across an acticle by Scheerer 

 of Modum, in the last number of Poggendorff"'s Annals, where the 

 same minerals are accurately and fully described.* Scheerer's 



* The cobaltic-arsenical-pyrites here mentioned, is described by Scheerer, as oc- 

 curring in two varieties ; one of which is crystallized and compact, and as having 



