612 



Professor J. 0. Arnold 



[Jau. 24, 



steels, made by the lecturer and Professor A. A. Read, of the Uni- 

 versity of "Wales, has yielded results of profound theoretical and 

 probably practical importance. The slide on the screen (Table II.) 

 shows that vanadium does not seem to form a double carbide with 

 iron. It gradually wrests the carbon from the carbide of iron till 

 when about 5 per cent of vanadium is present FcgC cannot exist, 

 and practically speaking only a vanadium carbide V4C3 containiog 



I200°C 



MOO 



10 20 10 20 10 



Seconds occupied by unit fall in Temperature 



Fig. 10. 



15 per cent of carbon is present, and this constituent is constant at 

 any rate in tool steels containing up to 14 per cent of vanadium. The 

 raicrographic analysis of these alloys, as shown in the three micro- 

 graphs about to be thrown upon the screen, has resulted in the 

 discovery of three new constituents, viz. vanadium pearlite (Figs. 8 

 and 8a), vanadium hardenite, and vanadium cementite (see top area of 

 Fig. 9). Vanadium hardenite seems to have a hardness of 8 (topaz) 

 as compared with the hardness 7 (quartz) of iron hardenite. 



