194 



Transactions. — Miscellaneous. 



[5.000 



The general results of these experiments conclusively show 

 that soft iron and steel exhibit quite appreciable magnetic 

 viscosity in rapidly-changing fields. The effect is far more 

 marked in the case of steel than in soft iron. 



The greatest departure of the slow- 

 cycle from the rapid-cycle curve is shown 

 at the " knee" of the magnetizing curve. 



When finely-divided iron or steel is 

 subjected to rapidly-alternating currents 

 the loss of energy due to magnetic hys- 

 teresis is greater than for slow cycles. 

 In the case of steel the loss of energy 

 would be quite 10 per cent, more than 

 for slow cycles, and in soft iron not so 

 much. 



In later experimeiits it was shown 

 that the effect observed was in no way 

 due to any screening of the interior mass 

 of metal from induction. The iron wire 

 of which the ring was composed was of 

 too small diameter to exhibit any appre- 

 ciable screening effect, due to induced 

 currents, for the period investigated. 



Table for Curve 7. 



In my paper published last year (Trans. N.Z. Inst., xxvii., 

 art. li'x.) it was shown that iron could be magnetized and 

 demagnetized when the magnetism was reversed more than 

 100,000,000 times j)er second. Soft iron and steel exhibit the 

 effect of magnetic viscosity quite strongly for a frequency of 

 1,000 ; but whether the loss of energy due to hysteresis increases 



