1036 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1954 



samples (Chemical analysis indicated that Sample 1 was 



(NiO)o.77(FeO)o.23Fe203 , 

 as distinct from 



(NiO)o.7B(FeO)o.25Fe203 



for Sample 4) but it is possible that other more subtle differences such as 

 the arrangement of the divalent nickel and iron ions are involved. Volt- 

 ages induced in the secondary winding on Sample 3 for various applied 

 fields were much higher than for the other samples at room temperature. 

 This confirms the presence of more than one wall as indicated by the 

 domain pattern. Therefore no further data were taken on this sample. 

 Each sample, after it had been cooled to the temperature of lic^uid 



100 200 300 400 



TEMPERATURE IN DEGREES KELVIN 



Fig. 8 — Plot of v/{H — He) for Sami)]e 4 as a function of temperature. 



