464 Scientific Proceedings, Royal Dublin Society. 



following experiments were made: — Ingot No. 43, with 1*93 °/ 

 of manganese, was submitted to a current of 20 amperes, equal to 

 a field of 260 c. g. s. units, for 5 seconds, and then tested by the 

 magnetometer again for three successive 10 seconds, the magneti- 

 zing force was applied, and the magnetometer deflection each time 

 taken. Here are the results — the moment is proportional to the 

 magnetometer deflection : — 



Table I. 



Ingot No. 43, 



Hence, in magnetizing this specimen 25 seconds is as effective as 

 35 for the current emploved. In another specimen with 9*65 °/ D 

 of manganese the effect of a still stronger field was tried. 



Ingot No. 8, 



A similar experiment was made with one of the forged test 

 bars, No. 596, containing 14 - 48°/ of manganese. 



Test Bar No. 596, 



A body is said to be magnetized to saturation when no increase 

 of the magnetic force can increase its magnetization any farther. 

 In this particular case a field rising to 700 units applied for 30 

 seconds magnetizes the specimen to saturation. 1 



1 "With a similar bar of ordinary magnet steel a field of 300 units applied for 10 

 seconds magnetized it to saturation. 



