L oJ 
IV. 
ON THE ELECTRICAL CONDUCTIVITY AND MAGNETIC PERMEABILITY 
OF VARIOUS ALLOYS OF IRON.* 
By W. F. BARRETT, F.R.S.; W. BROWN, B.Sc.; R. A. HADFIELD, M. Insr. C.E. 
(Prates II.-IX.) 
[Read Frsruary 22 (Part I.); May 17 (Part II.), 1899. ] 
INTRODUCTORY. 
Tue first part of the present paper contains the results of an examination of 
the electrical conductivity of upwards of one hundred alloys of iron, very many 
of these alloys being entirely new metallurgical products: the second part con- 
tains an examination of the magnetic properties of typical specimens of these 
alloys, complete B and H curves being made in each ease. 
In addition to the iron alloys described in the first part, many others were 
made, but rejected, either owing to the difficulty of getting good castings or the 
impossibility of forging or rolling the specimens. 
Process of Manufacture. 
For the purpose of the present research, there remained upwards of one 
hundred different alloys of iron or “steels,” which appeared to be fairly 
homogeneous, and could be forged and rolled. These specimens were rolled into 
rods of a uniform thickness, and of as small a diameter as could conveniently be 
obtained. In general the process of manufacture was as follows :— 
Ingots, 24 inches square, were cast of each alloy; these ingots were then 
forged and rolled at a bright red heat (about 900°C.) into bars 11 inch diameter. 
These bars were again heated to 900°C. and rolled into the experimental rods, 
which were of nearly circular cross-section and approximately 0°2 inch in 
* A joint authorship is given to this paper, as the preparation of the various alloys, and the 
determination of their chemical composition and mechanical properties were undertaken by Mr. Hadfield 
at the Hecla Steel Works, Sheffield, whilst the investigation of the physical properties of these alloys, 
described in the present paper, was made by myself, and Mr. Brown, at the Royal College of Science for 
Treland.— W. F. B. 
TRANS. ROY. DUB. SOC., N.S. VOL. VII., PART IY. M 
