551 



Magnetization in Ferromagnetic Metals and Alloys. 



From these numbers, we see that in Swedish iron, tungsten- 

 steel and nickel, the cooling by liquid air diminishes the 

 magnetization in low fields, but increases it in the strong. 

 In Swedish iron and tungsten-steel the change is very small ? 

 amounting at most to 2 or 3 per cent.; but in nickel the 

 initial diminution is considerably larger, amounting to about 

 10 per cent, in the maximum. The field, in which the effect 

 of cooling changes its sign, is 115 C.G.S. for Swedish iron 

 and tungsten-steel, and 580 C.G.S. for nickel. Fleming and 

 Dewar*, who first thoroughly studied the magnetization of 

 iron and steel in liquid air, did not observe an increase of 

 magnetization; perhaps the field was too weak to indicate 

 such an increase. 



In cast and annealed cobalts cooling always diminishes 

 magnetization ; the effect is rather greater in cobalt when 

 annealed than in the cast state. 



In Swedish iron, tungsten-steel, and nickel the magneti- 

 zations before and after the cooling coincide with each other 

 for all fields. In cast and annealed cobalts there is a con- 

 siderable residual change of the magnetic condition. 



(b) Magnetization of Nickel- Steels. 



The intensities of magnetization at the temperatures of the 

 room and of liquid air are given in Table II. 



Table II. 



Nickel-Steel 70'32 per cent. 



/=21 c 



•ic. 



^=-186° C. 



z<=30 



5 -5C. 



H. 



I. 



H. 



I. 



H. 



I. 



0-24 



9 



0-28 



6 



0-93 



35 



1-52 



120 



202 



96 



1-52 



127 



2-20 



310 



2-61 



221 



1-65 



233 



8-01 



500 



3-62 



455 



2-75 



374 



11-20 



721 



10-94 



662 



6-07 



593 



17-20 



794 



20-5 



835 



11-17 



712 



82-5 



903 



31-4 



911 



16-20 



784 



63-3 



969 



45-5 



971 



36-9 



869 



91-4 



988 



81-4 



1031 



52:9 



952 



232-1 



1004 



169-3 



10B3 



101-3 



987 



381 



1008 



253-3 



1072 



186-0 



996 



492 



1008 



337 



1078 



283-6 



999 



576 



1008 



439 



1088 



438 



999 



672 



1009 

 22'2 



601 



1098 



628 



1 



999 



* Fleming and Dewar, Proc. Roy. Soc. lx.-p. 81 (1896). 



