Geology and Natural History. 145 
IL GroLtogy AND NATURAL HISTORY. 
1. On the Cosmical dust which falls to the earth with atmos- 
pheric precipitation ; by A. E. NorpensKx1éLtp.—In the early part 
of December, 1871, the region about Stockholm was visited by a 
snow fall of unprecedented magnitude. Nordenskidld availed 
himself of this opportunity to investigate whether the apparently 
pure snow did not contain particles of foreign matter. A cubic 
meter of the snow was collected and melted with all possible pre- 
cautions: it was taken, 
storm (which lasted several days), when the atmosphere must have 
en purified from all accidental dust. Notwithstanding this, a 
cobalt or nickel 
ti 
Which covered the drift ice, which itself had come from much 
higher latitudes, was found to be thickly dusted with minute black 
Particles ; they rested in part on the surface, and were in part en- 
nthe icy snow mass some inches below. The dust was 
k when collected, but became gray on drying. It proved to 
fontain metallic particles which, with sulphate of copper, gave a 
Precipitate of metallic copper. The experiment was repeated later, 
material being obtained from a layer consisting of a granular 
*rystalline mass of altered snow, covered by eight millimeters of 
old harden : i "as 
ose and had recently fallen. At this place it was estimated that 
about 0-1 to 1° milligram of the magnetic particles were contained 
ion insoluble in acids consisted of a firm, angu- 
Am. Jour, Sc1.—Turrp Serres, Vou. IX, No. 50.—Fes., 1875. 
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