8 Dr. J. G. Gray on the Magnetic Properties of a 



434 c.G.s. units for the cooled specimen when exposed to the 

 same magnetizing force. 



Table II.— 



Nickel-Man 



ganese Specimen ; 10 per cent. M 



n. 





Specimen as cast. 



Specimen after annealing Specimen after quench- 

 from 900° C. ing at 900° C. 



Value 

 of 

 H. 













*=16 C C. 



*!=:-190 O C. 



*=16° C. 



;=-190°C. *=16°oL=— 1 



90° C. 

 K. 



I. 



K. 



1 



4-40 



I. 



K. 



I- 



K 



1. 



K. I. 



5 ... 



,30 



6-00 



22 



30 6-00 



26 



5-20 



46 



920 37 



7 43 



10 ... 



74 



740 



60 



600 



75 7-50 



60 



600 



b6 



8 60 86 



860 



15 ... 



104 



693 



94 



6"26 



109 7-26 



97 



6-46 



116 



772 126 



8-40 



20 ... 



125 



6-25 



120 



6-00 



130 6-50 



129 



645 



140 



7 00 152 



760 



40 ... 



190 



4-75 



206 



5-15 



212 5-30 



224 



5 60 



204 



5*10 220 



565 



60 ... 



236 



3-93 



264 



4-40 



258 4-30 



280 



460 



240 



400 276 



490 



80 ... 



267 



334 



306 



3-83 



287 



359 



318 



398 



270 



338 316 



395 



100 ... 



288 



2-88 



336 



336 



308 



3-08 



353 



353 



288 



2-88 345 



345 



150 ... 



321 



214 



384 



2-56 



344 



2-30 



404 



2-70 322 



2-14 398 



2-66 



200 ... 



336 



1-68 



416 



2-08 



368 



1-84 



434 



217 344 



3'44 428 



214 



As in the case of the specimen containing 5 per cent. Mil, 

 quenching the specimen had the effect of considerably im- 

 proving its magnetic susceptibility for low field-strengths. 

 For H = 10 C.G.s. units the susceptibility of the quenched 

 specimen at room-temperature was 8*0 as against the value 

 7*5 for the annealed specimen at the same temperature. 

 For fields greater than about 30 c.G.s. units, however, the 

 susceptibility of the quenched specimen at room -temperature 

 was less than that of the annealed specimen. 



The results yielded by the specimen containing 15 per 

 cent. Mn are shown in Table III., and the magnetization 

 curves in PL I. fig. 6. The susceptibility of this material 

 in the cast and annealed conditions for low and moderate 

 field-strengths is greater than that of the alloy containing 

 10 per cent. Mn. Thus Eor the annealed conditions o\ the 

 two alloys the susceptibilities of the 10 per cent, and 15 per 

 cent. Mn specimens at room-temperature, and Eor a field- 

 strength oi L0 o.G.s. units, were found bo be 7*5 and L1'5 

 respectively ; for E= 20 c.G.s. units the corresponding values 

 were 6*5 and 8*4. For high field-strengths, however, the 

 susceptibility of tin 1 annealed specimen containing L5 per 

 cent. Mu was decidedly lower than that of the L0 per 

 cent. Mn specimen in the same condition. 



