vn.J 



COSMIC DUST. 



251 



were found numerous metallic particles that were attracted by 

 the magnet, and were found to contain iron, cobalt, and possibly 

 nickel also. 



4. On the melting of 500 gram, hail, which fell in Stockholm 

 in the autumn of 1873, similar metallic particles containing 

 cobalt (nickel) were obtained, which, in this case, might possibly 

 have come from the neighbouring roofs, because the hail was 

 collected in a yard surrounded by houses roofed with sheet-iron 

 painted red. The black colour of the metallic particles enclosed 

 in the hail, their position in the haij, and finally, the cobalt 

 they contained, however, indicate in this case too, a quite 

 different origin. 



5. In a dust (kryokonite), collected on the inland ice of 

 Greenland in the month of July, 1870, 

 there were also found mixed with it grains 

 of metallic iron, containing cobalt. The 

 main mass consisted of a crystalline, double- 

 refracting silicate, drenched through with an 

 ill-smelling organic substance. The dust 

 was found in large quantities at the bottom 

 of innumerable small holes in the surface of 

 the inland ice. This dust could scarcely be 

 of volcanic origin, because by its crystalline 

 structure it differs completely from the 

 glass-dust that is commonly thrown out of 

 volcanoes, and is often carried by the wind 

 to very remote regions, as also from the 

 dust which, on the 30th March, 1875, fell 

 at many places in the middle of Scandinavia, 

 and which was proved to have been thrown 

 out by volcanoes on Iceland. For, while 

 kryokonite consists of small angular double- 

 refracting crystal-fragments without any 

 mixture of particles of glass, the volcanic 



Haga-dust^ consists almost wholly of small microscopic glass 

 bubbles that have no action on the polarisation-planes of the 

 light that passes through them. 



1 I use this name because the ash-rain of March 1875 was first observed 

 at Haga palace near Stockholm, and thus at the outer limit of the known 

 area of distribution of the dust. It was first through the request whicli 

 in consequence of this observation was published in the newspapers, tluit 

 communications regarding singular observations in other quarters should 

 be sent to the Swedish Academy of Sciences, that it became known that 

 a similar rain had about the same time taken place over a very large part 

 of middle Sweden and Korway. The dust however did not fall evenly, 

 but distributed iu spots, and at several different times. The distance 

 from Stockholm of the volcanoes, where the outbreak took place, is nearly 

 2000 kilometres. 



SECTION OF THE UPPER 

 PART OF THE SNOW ON 

 A DRIFT-ICE FIELD IN 

 80° N.L. 



One-half the natural size. 



