Study on the Demagnetizing Field on Measurement of Ferromagnetism of Magnetite by Means of Powder Method

Abstract

As a convenient measurement of ferromagnetism the powder method have been used for valuations of various magnetic minerals.
In the method total magnetic flux is measured by ballistic galvanometer using filled powder in nonmagnetic cylindrical tube instead of usual bar shaped specimen. However in the method as the demagnetizing factor have never been solved, magnetization curve, i. e. variation of intensity of magnetization against effective magnetic field can not be obtained, only shared curve, i. e. variation of intensity of magnetization against external magnetic field is obtained on the supposition that the demagnetizing factor equals to zero.
In order to extend the method so as to be able to obtain magnetization curve directly from this measurement, the author experimentally decided the demagnetizing factor by using bar shaped and powdered. magnetite.
The results obtained are summarized as follows
(1) In the region of initial permeability the demagnetizing factor takes the value of about 0.9
(2) It seems to take the values of ranging from 0.92 0.95 to in the region of reversal process.
(3) In the region of continuous rotation it gradually decreases with the increase of intensity of ma gnetization.
These results may have fundamental importance in utilization of the above method.