82 THE ROYAL SOCIETY OF CANADA 



0.446 0.446 



0.223 :— :-L = 2.10 



2 0.217 



P ^i?? = 0.210 °-^" = 1.93 



2 0.217 



Average 0.217 



However, it appears that this massive phosphide is not homo- 

 geneous. In the first metallographic observations on surfaces only 

 plain polished or etched with bromine water, the phosphide had 

 seemed to be quite pure and uniform, but later it was seen on heat- 

 tinted surfaces that some, at least, of the phosphide areas consisted 

 of a mixture of two constituents, one, the more easily oxidized, of a 

 dark blue colour, the other of a yellow or reddish colour similar to 

 that of 38% nickel alloy or taenite. It may be a reasonable specula- 

 tion to suppose that the less easily oxidizable component actually is 

 "taenite" which has been included and perhaps partially digested 

 by the phosphide, since the taenite and phosphide occur in a similar 

 relationship as a dual eutectic surrounding the Kamacite areas. If 

 this supposition is correct it is likely that the phosphide is essentially 

 (FeNi)3P or possibly (FeNi)2P with some included taenite. Stead, 

 in his exhaustive researches on iron and phosphorous, showed that 

 FcsP is the usual form in which phosphorus appears as a compound 

 in iron, this and the compound Fe2P, w^hich is formed only under 

 exceptional conditions, being the only definite compounds of iron and 

 phosphorus identified by him. 



Physical Properties 

 The phosphide is a brilliant tin-white in colour and very brittle, 

 breaking with a somewhat conchoid al fracture. It has been much 

 fractured in situ (PI. VIII, Fig. 7; PI. X, Fig. 12) and the particles as 

 isolated seem to be in a state of strain as they often crumble at the 

 merest touch. It is attracted and held by a common horseshoe 

 magnet. Owing to the extreme brittleness and the minute areas 

 available for testing, i*t is difficult to determine the hardness. How- 

 ever, fragments as isolated, when rubbed on glass under the binocular 

 are seen to scratch though they crumble in the process. The glass 

 itself was just scratched by orthoclase, while the orthoclase was not 

 scratched when the phosphide was rubbed on it. The hardness is, 

 therefore, about 6 in Mohs scale. Though the phosphide is thus 

 apparently harder than the Kamacite ground mass it polishes lower, 

 forming depressions, owing to its extreme brittleness and its fractured 

 character. 



