Barrett — On the Magnetic Moment of Steel, etc. 465 



In order to construct a curve of magnetization with increasing 

 magnetizing force a more extensive series of experiments were 

 made on one of the virgin test bars, No. 598, containing 18*4 per 

 cent, of manganese. The weight of this bar was 467 grammes, 

 its specific gravity 7*8, its length 16 centimetres, and diameter 

 2 centims. The scale of the magnetometer was 100 centims. 

 distant = D, and the scale reading of the magnetometer is given 

 as before in millims. In each case the specimen, as before, was 

 first magnetized in the helix, then removed and brought to the 

 magnetometer, the reading taken, and then the sample reversed 

 end for end : hence the deflection due to one pole is one-half of 

 that read. 



A series of comparative experiments were made with a bar of 

 ordinary steel glass hard and a bar of ordinary mild steel. In 

 each case the specimen is magnetized with a current of definite 

 strength, removed from the helix, and its moment tested in an 

 adjoining room. The following are the results : — 



Table IV. 



Effect of increasing strength of field on the Magnetic Moment of 

 Manganese Steel. 



Test Bar No. 598, containing 18-4 per cent of manganese. 



2d 



