Graded Series of Nickel-Manganese Alloys. 7 



units the values of the intensity of magnetization are 316 

 and 350 c.g.s. units at 15° C. and —190° C. respectively. 



Table I.— Nickel-Man 



ganese Specimen ; 



5 per cent. Mn. 





Specimen as cast. 



Specimen after annealing 

 from 900° C. 



Specimen after quench- 

 ing at 900° C. 



Value 





























of 

 H. 



5 ... 



*=16° C. 1 £=-190° 0. 



^ = 16° C. t=- 



190° 0. 



£=16° C. 



t= - 190° 0. 



I. 

 18 



K. I. 



K. 



I. 



1 20 



K. 



I. 



K. 



I. 



38 



K. 



I. 



K. 



3-60 15 



3-00 



4-00 



16 



3-20 



7-60 



30 



6-00 



10 ... 



44 



4-40 38 



3-80 



' 48 



4-80 



40 



! 4-00 



67 



6-70 



60 



6-00 



15 ... 



68 



4-53 ■ 64 



4-26 



77 



5-13 



66 



j 4-40 



92 



6-13 



89 



5-92 



20 ... 



86 



4-30 83 



4-15 



97 



4-85 



89 



i 445 



110 



5-50 



110 



5-50 



40 ... 



139 



3-48 , 143 



357 



158 



3-95 



155 



3-87 



162 



4-05 



172 



4-30 



60 ... 



177 



2-95 187 



311 



195 



325 



203 



3-38 



196 



326 



212 



3-53 



80 ... 



209 



2-61 220 



2-75 



224 



2-80 



236 



! 2 95 



225 



2-81 



244 



305 



100 ... 



232 



2-32 244 



2-44 



248 



2-48 



264 



! 2-64 



249 



2-49 



271 



2-71 



150 ... 



272 



1-81 290 



1-93 



292 



1-95 ! 317 



2-11 



293 



1-95 



320 



2-13 



200 ... 



291 



1-45] 312 



1-56 



316 



1-58 350 



1-75 



318 



1-59 



353 



1-76 



The behaviour of the specimen after quenching exhibits 

 some remarkable features. In the first plnce the susceptibility 

 for low fields is found to have undergone a marked improve- 

 ment. At room-temperature the intensity of magnetization 

 is found to be 38 c.g.s. units for a field of 5 c.g.s. units, as 

 against 20 c.g.s. units for the material in the annealed con- 

 dition. Crossing of the I-H curves at 15° C. and - 190° C. 

 takes place for a value of the magnetizing force of 20 C.G.S. 

 units. For field-strengths greater than this value the 

 susceptibility of the material is practically that which is 

 characteristic of the annealed specimen. 



The results obtained on testing a specimen containing 

 10 per cent. Mn are exhibited in Table II. and in PL I. 

 fig. 5. The specimen exhibited properties whose general 

 features are similar to those shown by the specimen previously 

 described. The improvement in magnetic quality for high 

 fields brought about by cooling to the temperature of liquid 

 air is, however, much greater. For the annealed condition 

 of the alloy the I-H curves corresponding to 15° C and 

 — 190° C. cross for a value of the magnetizing force of 

 24 c.g.s. units ; for the quenched alloy they cross for 

 H = 10 C.G.s. units. The improvement in magnetic quality 

 which follows upon the cooling is very great for high fields. 

 For the annealed material at 15° C. the intensity of magne- 

 tization is 368 c.g.s. units for H = 200 c.g.s. units as against 



