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changes in composition. We have found that compositions between 

 10 per cent and 40 per cent iron, 10 per cent and 80 per cent nickel, 

 and 10 per cent and 80 per cent cobalt have marked perminvar 

 characteristics. 



The hysteresis losses of the alloys in the annealed condition are 

 plotted in Fig. 6 for a maximum flux density of 5,000 gauss. This 



Fig. 7 — Intrinsic inductions for annealed alloys at H = 50. 



diagram illustrates again the abrupt change in the magnetic properties 

 as we pass from alloys with large iron content to those in which nickel 

 predominates. In this figure the lowest energy losses are those for 

 alloys in the neighborhood of the 78.5 permalloy composition. In the 

 iron-cobalt series the 50 per cent cobalt alloy has the lowest hysteresis 

 loss. 



