Barrett — On the Magnetic Moment of Steel, etc. 467 



The following table gives the results of the experiments : — 



Table V. 

 Magnetic Moment of Ingots of Manganese Steel. 



* The numbers marked with an asterisk require to be reduced nearly 5 per cent, 

 when the length of the ingot is taken into account, as in those cases the distance from 

 the magnetometer needle was small. Thus the moment per gramme of the first and 

 last ingots instead of being -0257 would be -0245 units. 



This table at once reveals the striking fact that the magnetic 

 moment does not decrease as the amount of manganese increases ; 

 on the contrary, the specimens having the smallest and the largest 

 per-centage of manganese had practically the same magnetic 

 moment. One specimen, No. 6, had an abnormally high mag- 

 netic moment. This may be due to some accidental cause in the 

 casting — several experiments with this ingot giving perfectly 

 coincident magnetic moments, as did further experiments with 

 No. 8, with almost the same per-centage of manganese, and yet 

 having a magnetic moment fifty times smaller. In fact there 

 appears to be no relation between the magnetic character of the 

 alloy and the amount of manganese present ; nor does the appear- 

 ance of the fraction give any clue to the differences observed. 



Another striking fact revealed in Table V. is the extraordinary 

 difference in magnetic character of specimens having almost iden- 

 tical composition. Thus, not only ingots marked 6 and 8 already 

 referred to, but ingots 13 and 14 have each practically the same 

 amount of manganese, and yet the magnetic moment of one is 

 upwards of three times that of the other. This difference is pro- 

 bably due to the different state of aggregation of the particles 



