Properties of an Extensive Series of Alloys of Iron. 21 
We have recently received from Messrs. J. Sankey and Son, of Bilston, a speci- 
men of the ‘‘Lohy ” iron that they manufacture for transformers, and which has 
a hysteresis loss of only 0°32 watts per lb. for a maximum induction = 4000 
C. G. S., and a frequency of 100 cycles per second. 
The results obtained with our silicon-iron and aluminium-iron alloys when 
carefully annealed are considerably better than the “ Lohy” iron at this 
maximum induction and frequency. The figures are as follows :— 
Shy ts dbo : : 3 ; : 0°38 watts per lb. 
itor” Ib, 5 j : 0:3 208 ass 
898 E, yee jog kk es OU). 
IMG TPEERE aH eka d CON Bw hOr9s 
”) ”? ”) 
In conclusion, the question remains to be considered what is the chemical 
or physical change produced in iron by the presence of other metals, so that on 
the one hand the magnetic permeability of the alloy is practically destroyed by 
the added element, and on the other increased. From their strong chemical 
affinities for oxygen and the halogens, silicon and aluminium may act both 
chemically and physically. By combining with oxygen or with dissociated gas 
they may render the iron freer from oxide of iron, or give it a closer texture 
and prevent fine honeycombs being formed. Microscopic examination of 
sections of all these alloys is needed; such examination cannot fail to throw light 
on the relation between magnetic qualities and the size and nature of the grain, 
or the crystalline structure of the alloys. Experiments also need to be made on 
the recalescent points or critical temperatures of these alloys, and on the question 
whether part of the iron, or of other metals entering into these alloys, is in an allo- 
tropic state. The condition in which the carbon exists in the alloy is also a matter of 
great importance magnetically as well as mechanically. The change in the 
magnetic quality of iron and iron alloys by annealing no doubt largely consists 
in the alteration in the state of the carbon, as well as of the iron, at the tempera- 
ture of recalescence.* 
As magnetisation involves a molecular change in magnetic bodies, whatever 
affects the state of molecular aggregation in these bodies affects their magnetic 
susceptibility. An increase or decrease of mechanical hardness means an increase 
or decrease of the power of resisting molecular change; and hence magnetic 
hardness or high coercive force, and magnetic softness or high permeability, 
correspond to the mechanical hardness or softness of iron and its alloys. It is 
thus easy to understand why a body which in the annealed state is feebly 
magnetic in a certain magnetic field becomes non-magnetic in the same field 
* In this connexion Herr Kamps has some valuable observations in his second Paper in Stahl und 
Eisen for October, 1899. 
TRANS.. ROY DUB. SOC., N.S., VOL. VIII., PART I. K 
