90 THE ROYAL SOCIETY OF CANADA 



evident that what has been said regarding sections of the meteoric 

 crystals applies with equal force to Stead's crystals of FcsP. The 

 crystal forms in both cases must be considered still open to question. 



Physical Chemistry 



The Annaheim meteorite presents interesting problems in 

 physical chemistry and the writer believes it would be well worthy 

 of study by iron and steel metallurgists. Certain outstanding 

 peculiarities of structure which seem to defy explanation may be 

 briefly noted. First of all we have the easily fusible phosphide 

 crystals (melting point about 1060° or less) embedded in the 6.87% 

 nickel iron ground mass of much higher melting point (iron 1530°, 

 nickel 1452°, cobalt 1478°), and containing little, if any, phosphorus. 

 Then, though the massive phosphide quite properly appears to 

 function as eutectic, the 38% nickel alloy, with presumably much 

 higher melting point (Invar 1425°), appears to play an equal part in 

 the eutectic partnership. If the structure is interpreted in other 

 ways difficulties still remain. Stead performed an experiment which 

 shows that rough but unquestionable crystals of FesP may be pro- 

 duced in iron containing 1.95% P by repeated long annealing at 

 900°C. and slow cooling (Loc. cit. Plate XII, No. 20). In this experi- 

 ment, however, the molecular rearrangement of the phosphide 

 into the crystal form was not complete as 1 .06% of P still remained 

 in solid solution in the iron. It may be, then, that the meteoric 

 phosphide crystals represent the final result of a long continued 

 natural annealing process, perhaps under considerable pressure. 

 Stead's crystals on heating to 1100°C. lost their form and coalesced 

 into rounded and elongated masses somewhat resembling the un- 

 crystallized phosphide of the Annaheim iron. 



In endeavouring to account for the structures of the Annaheim 

 iron we must consider two factors which may have had a tremendous 

 efïect, and which are seldom taken into account in researches on 

 ordinary iron and steel, viz., time and pressure. Enormous pressure 

 to which the iron may have been subjected when in its parent body, 

 according to the operation of Le Chatelier's principle, might have had 

 a considerable efïect on the melting points of the various constituents, 

 and a tendency might be expected for the elements to form such 

 combinations as would have the least volume at any particular 

 temperature. Slow cooling through an immense time period would 

 provide opportunity for complete molecular rearrangement and 

 segregation. 



