10 Dr. J. (x. Gray on the Magnetic Properties of a 

 Table IV. — Nickel-Manganese Specimen ; 20 percent. Mn. 



Value 

 of 



11. 



.") ... 



Specimen ;is c 



ist. 



Specimen after annealing 

 from 900° 0. 



Specimen after quench- 

 in- at 000° C. 



rf=16°0. 



*=-190°C. 



*=16°C. 



/=- 



190° C. 



;=16° c. 



/=-190°C. 



T. K. 



1. 



K. 



I. 

 20 



K. 

 100 



I. 

 30 



K. 



I. K. 



I. 



K. 



16 3-20 



7 



1-40 



600 



10 025 



27 



5-40 



10 ... 



•2C> 260 



26 



2-60 



32 



320 



7<) 



7-0(1 



L-5 015 



51 



510 



15 ... 



:-J4 2 27 



52 



346 



41 



2-7;-! 



99 



0-0(1 



20 o-i2 



64 



4 26 



20 ... 



40 200 



80 



4-00 



47 



2 35 



123 



6-15 



2-;» 012 



78 



3-90 



40 ... 



56 1-40 



148 



3-70 



64 



1-00 



181 



4 52 



:;•;> 0*08 



112 



2-80 



60 ... 



65 108 



179 



2-98 



76 



127 



210 



360 



45 007 



131 



2 18 



80 ... 



72 01) 



202 



2-52 



85 



106 



236 



2-95 



5 006 



110 



1-83 



100 ... 



77 0-77 



218 



2- IS 



91 



001 



250 



2-50 



5-5 0-05 



L58 



1-58 



150 ... 



90 0-60 



248 



1 -CI'. 



102 



068 



270 



L-8-1 



60 04 



177 



118 



200 ... 



96 048 



270 



1-35 



110 



055 



296 



L-48 



65 003 



L92 



096 



In the experiments now described the lowest Held employed 

 was 5 C.G.s. units. For this alloy in fche annealed condition 

 this field-strength produced an intensity of magnetization of 

 20 c.G.s. units and 30 O.G.S. units at "if) 0. and —190° C. 

 respectively. Thus the magnetization curves corresponding 

 to the two temperatures cross, it" they do cross, tor a very 

 low value of the magnetizing force. 



The effect of quenching this material is in large measure 

 to destroy its magnetic quality. Al room-temperature the 

 quenched specimen was practically non-magnetic, the intensity 

 of magnetization for a field-strength of 200C.G.S. units being 

 only 6* c.G.s. units. At the temperature of liquid air. how- 

 ever, the specimen exhibited very considerable magnetic 

 quality. For H = 20 C.G.s. units the intensity of magneti- 

 zation of the quenched material at — 190° C. was 78 c.G.s. 

 units as againsi 2*5 c.G.s. units for room-temperature ; For 

 H=200 c.G.s. units the intensit v of magnetization at — L90 ( '. 

 was 192. 



It may he mentioned at this stage thai in the case el' all 

 these nickel-manganese alloys, in all the three conditions, do 

 transformation oi the material is brought aboul by cooling 

 to the liquid-air temperature ; the magneti/.at ion curve at 

 room-temperature following upon cooling to —190° C. is 

 practically identical with thai obtained at room-temperature 

 before cooling. Thus in the ease o\' the specimen containing 

 20 percent. Mn the effeci of quenching al 900 C. has been 

 to lower the critical temperature to the neighbourhood o\' 

 room-temperature. This particular specimen was sel aside 



