40 BELL SYSTEM TECHNICAL JOURNAL 



the other constituent suffers relatively little change of magnetization 

 at low magnetizing forces. 



To the engineer these alloys are of unusual interest. They may be 

 used to advantage for magnetic structures where the magnetizing 

 forces do not exceed the limits of constancy of permeability for the 

 various compositions. Interesting results have been obtained with 

 the 45 per cent nickel, 25 per cent cobalt and 30 per cent iron com- 

 position for continuous loading of telephone conductors and for cores 

 of loading and filter coils used in high quality transmission and in 

 carrier current circuits. For such purposes high resistivity is also 

 desired, and it has been found that the addition of a few per cent of 

 other metals such as molybdenum serves for this purpose. For 

 circuits requiring greater constancy or higher permeability other 

 compositions are more suitable. The best alloy for any specific 

 circumstance may be selected from a study of the magnetic properties 

 of the various compositions. 



