PROF. NORDENSKIOLD, EXPEDITION TO GREENLAND. 441 



The Ovifak iron is extremely crystalline and brittle, so that 

 smaller pieces may be broken with a hammer ; and, with the ex- 

 ception of the little bits of basalt on or near the surface, it is not 

 mixed with any silicates visible to the naked eye. The iron from 

 the basalt ridge differs from the other by a rougher fracture and 

 greater toughness. With the naked eye one can seldom discover 

 any nodules of troilite or iron-sulphide. In the weathered detritus, 

 on the other hand, a few black magnetic grains were found, with 

 strongly reflecting facettes and octahedral surfaces, which on 

 examination we found to be magnetite. When cut and polished, 

 the different specimens varied very greatly; on some of them parts, 

 yellow as brass, of troilite were discernible, and the polished 

 surface of the metal itself appeared, when the light fell on it in a 

 certain direction, divided into rounded parts, of different brilliancy 

 and shades of colour. Other pieces seemed to form a perfectly 

 homogeneous aggregate of crystal needles of carburetted nickel- 

 iron. The Widmanstadtian figures were visible after etching on 

 some, but not all, of the specimens. These were particularly dis- 

 tinct on. the iron from the above-mentioned basalt ridge. In 

 general the iron was so hard that they would not undertake at the 

 ironworks to saw through any of the larger balls, in cousequence 

 of which I know no more of the internal character of the meteoric 

 iron than what I could ascertain from the specimens which fell to 

 pieces. 



Part V. ('' Geological Mag.," for November 1872, p. 516.) 



Notwithstanding the very inconsiderable amount of sulphur it 

 contains, this Greenland iron has a remarkable tendency to fall to 

 pieces by the action of the air. The weathering depends on an 

 oxidation, probably produced by a quantity of chlorine contained 

 in the iron, and its great porosity ; nevertheless, some of the 

 phenomena connected with the weathering still appear to me in- 

 explicable. I shall therefore somewhat more fully detail the 

 observations and experiments made towards explaining this very 

 disagreeable circumstance. 



The Ovifak meteoric iron does not fall to pieces at the place 

 where it was found, though sometimes washed by the sea, some- 

 times left bare ; but on the shore it was preserved at the temperature 

 of the sea, which varies but little during the whole year. 



Even during the passage, when the masses lay packed in wooden 

 chests in the hold, and were exposed to a very moist atmosphere 

 and at a temperature but little above freezing-point, the unbroken 

 stones did not suffer perceptibly ; whereas almost all the fragments 

 packed in the same manner split into pieces, more particularly 

 those which I had preserved in the heated cabin. 



From some of the pieces of iron sea-green drops oozed out, which 

 afterwards became reddish-brown by the action of the atmosphere. 

 They contained protochloride of iron with traces of sulphate. 



One of the larger pieces, which, after our return home, was 

 placed in a room of ordinary temperature, soon began to crack on 



