516 Prof. Nordenskiold — Expedition to Greenland. 



YI. — Account of an Expedition to Greenland in the tear 1870. 



By Prof. A. E. Nordenskiold, 



Foreigu Correspoudent Geol. Soc. Loud., etc., etc., etc. 



Part V. 



{Continued from page 463.) 



VrOTWITHSTANDING the very inconsiderable amount of sulpliur 

 X^l 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 inexplicable. I 

 shall therefore somewhat more fully detail the observations and expe- 

 riments 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, sometimes 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 its sur- 

 face, and ultimately, when unpacked two months later in Stockholm, 

 crumbled to a reddish brown powder, consisting partly of a fine 

 rust powder, partly of angular bits of iron, rusty on the surface, and 

 varying in magnitude from the size of a pea to that of a hemp-seed. 

 An entirely unchanged, and therefore, on a fresh surface of frac- 

 ture still metallic, portion of Stone 4, began at one corner to 

 rust, swell and crumble, while the remainder of the iron remained 

 unaltered. The rust spread itself like a fungous growth over the 

 rest of the piece, and extended itself to the interior, which thereupon 

 swelled and crumbled like an efflorescent salt. During this time the 

 weight of the piece of iron increased. 



Weight of a fragment of iron when packed 29-935 gr. 



„ „ after 129 days 30-143 gr. 



Weight of the unchanged iron 24-529 gr. 



SO that 5'-406 gr. had weathered away to a rusty -brown powder and 

 during this time had increased in weight 0'208 gr. or 3-8 per cent. 



In a hermetically sealed glass tube the iron was completely 

 unchanged. 



In a glass tube, that had been hermetically sealed, but in which a 

 fine crack had taken place in cooling, the iron continues to crumble 



In a eudiometer over mercury, the iron in a few days absorbed a 



