1904-5.] On the Magnetic Properties of Demagnetised Iron. 849 
Note on Some of the Magnetic Properties of Demagnetised 
and Annealed Iron. By James Russell. 
(Read June 19, 1905.) 
In a paper laid before this Society in July 1902, the magnetic 
seolotropy of iron demagnetised by decreasing reversals of co- 
directional and transverse magnetising forces, and also of iron left 
transversely magnetised, was established. In later communications 
(July 1903 and July 1904) it has further been shown that iron and 
nickel demagnetised by decreasing reversals of a directional force, 
develop an induction component at right angles to the subsequent 
magnetising force, which tends to disappear as saturation values 
are reached, when the angle between these two forces is other 
than 0° and 90°. In annealed iron this property is absent. 
The present preliminary communication is limited to experiments 
made with one sample of transformer iron, demagnetised by de- 
creasing reversals of co-directional (C) and transverse (T) forces 
and also by annealing (A). The letters C, T, and A will be used 
to represent these three conditions of demagnetisation respectively. 
The magnetic properties determined are: — permeability, reten 
tivity, coercive force, and the energy loss due to hysteresis. 
Permeability. — B-H curves of induction have been plotted for 
values of the magnetising force between the limits of H = 0*1 and 
H = 10. One set of curves, three in number, measures the 
induction from zero, due to the first application of many given 
values of H, superposed upon conditions C, T, and A respectively. 
Another set of curves measures one-half the induction change on 
reversal of the given values of H, after conditions C, T, and A 
respectively have been subjected to or modified by 200 reversals 
of that force. If any given value of H be represented by h, then 
Ch , T h, and Ah may conveniently signify that before the readings, 
from which these curves were plotted, had been recorded, h had 
first been superposed upon the molecular conditions of demagnetisa- 
tion and reversed 200 times. 
PROC. ROY. SOC. EDIN. — YOL. XXY. 
54 
