14 Magnetic Properties of Nickel-Manganese Alloys. 



by the specimen containing 5 per cent. Bin. The improve- 

 ment in magnetic quality tor high fields is, however, mach 

 greater in this material. In the annealed condition of the 

 metal the magnetization curves corresponding to 15° C. and 

 — 190° C. cross Eor E = 24 C.G.S. units, the curves for the 

 quenched material at the two temperatures cross for 

 11=10 O.G.S. units. Quenching this material at 900° C. 

 improves its magnetic quality for low fields. 



6. The material resulting from alloying nickel with 



15 per cent. Mn behaves normally in thai the magnetization 

 curve corresponding to —190° C. lies at first below and 

 finally above that corresponding to 15° 0. The curves cross 

 for H=14 C.G.S. units for the annealed material, and for 

 H = 7 c.G.s. units for the quenched material. The improve- 

 ment in magnetic quality for high fields produced by cooling 

 a specimen is very great. 



7. The nickel-manganese alloy containing 20 per cent, 

 manganese exhibited very remarkable magnetic properties. 

 In all conditions of the metal the magnetization curves 

 yielded on testing the specimen at 15° C. and —190° C. 

 cross for very small values of the magnetizing force 1 , and tin* 

 improvement in magnetic quality brought about by cooling 

 to the temperature of liquid air is enormous. Quenching a 

 specimen at 900° C. rendered it non-magnetic at room-tem- 

 perature. At —190° C, however, it exhibited very decided 

 magnetic properties. 



8. Specimens containing 25 and 30 percent, of manganese 

 were tested in all three conditions at 15'' ('.and — 190 Q ( '. 

 They were found to he feebly magnetic. The magnetization 

 curves at the two temperatures cross Eor very small values 

 of the magnetizing force. 



9. Unlike the manganese- and nickel-steels, the nickel- 

 manganese alloys are not changed in magnetic quality by 

 being cooled to the temperature oi' liquid air. A magneti- 

 zation curve yielded by a specimen at room-temperature, 

 following upon cooling to —190° C, is practically identical 

 with that yielded by the specimen at rooai-temperat lire 

 pre\ ions to being cooled. 



The work described in this paper was carried out in the 

 Natural Philosophy [nstitute o\' the University o\' Glasgow, 

 and the author desires to express his thank- to Prol 

 Gray For the interest lie bas taken in the progress ^\' the 

 experiments. 



