The Magnetic Properties of almost pure Iron. 

 Table I. 



371 



Dissipation of energy by magnetic hysteresis in ergs per cycle 

 per cubic centimetre. 



Transformer plate 

 rolled from Swedish 

 iron (Ewing). 



220 

 410 

 640 

 910 

 1200 

 1520 

 1900 

 2310 



fi. 

 2560 

 3340 

 3880 

 4230 

 4410 

 4450 

 4330 

 4090 

 3790 



Pure Iron 11 tested 

 as received. 



Pure Iron II tested 

 after annealing. 





/*• 





/*• 



350 



2000 



262 



2500 



500 



2730 



460 



3190 



800 



3330 



720 



3810 



1100 



3700 



1010 



4350 



1450 



4138 



1350 



4800 



1760 



4375 



1670 



5380 



2160 



4445 



2020 



5440 



2600 



4615 



2450 



5490 



3100 



4545 



2860 



5460 



4400 



4000 





4900 



5900 



2641 





3260 





1415 





2050 



Table II. 



Limits of H. 



Limits of B. 



~\BdB. 



fi. 



Coercive force 

 in C.G-.S. units. 



0-783 



1965 



262 



2510 



0-50 



114 



4840 





4245 





117 



5150 



1080 



4400 



73 



1 -42 



7500 





5280 





1-66 



9100 



2490 



5480 



0-90 



223 



11460 





5140 





2-68 



12500 





4660 





4-74 



14270 





3010 





9-24 



15270 





1650 



113 



Apparent Magnetic Instability. 



Whilst making the foregoing experiments, the author noticed how 

 great was the apparent magnetic instability in this specimen, and 

 thought it worth while to investigate this more closely. 



It has already been noticed, and is well known, that if the mag- 

 netising force be varied from one maximum value through zero to a 

 value equal, say, to the then coercive force of the materia], that 

 tapping the specimen will produce a considerable change of induc- 

 tion ; or, if the observed kick on a ballistic galvanometer (in circuit 

 with a secondary coil wound on the specimen) due to such change be 

 added to the observed kick when the magnetising force is raised to 



