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IX. 
RESEARCHES ON THE PHYSICAL PROPERTIES*OF AN EXTENSIVE SERIES 
OF ALLOYS OF IRON. Parrs IV. anp V. 
By W. BARRETT, ERS.; W. BROWN, B.Sc; ann R. A. HADFIELD, 
Vice-President of the Iron and Steel Institute. 
[Read, Marcu 15, 1904. ] 
AR LVE 
THERMAL CoNnDUCTIVITY. 
Tux series of alloys that forms the subject of these researches was, as described in 
Part I., prepared and carefully analysed at the Hecla Steel Works, Sheffield, of 
which one of the authors is Managing Director. Parts I. to III., published in the 
Scientific Transactions of the Royal Dublin Society, dealt with the magnetic pro- 
perties and electric conductivity of these alloys. We have shown that iron, when 
alloyed with a comparatively small quantity of certain metals, can be rendered 
nearly, and in some cases wholly, non-magnetic, though the iron present may 
amount to from 70 to 88 per cent. On the other hand, we have found certain 
non-magnetic elements, such as aluminium and silicon, when alloyed in small 
percentages with iron, render the alloy more magnetic——more permeable to 
magnetic lines of force at ordinary temperatures—than the purest commercial 
iron. The effect on electric conductivity was no less marked. A comparatively 
good conductor like aluminium, when alloyed, even in small quantities, with iron, 
enormously reduced the conductivity. In fact, the highest electric resistivity of 
any known metallic wire was found in some of these composite iron alloys.* 
A summary of our results was given in a paper read by one of us before the 
Institute of Electrical Engineers ;} and in that paper it was stated that “a series 
of experiments are in progress in which the thermal conductivities of these alloys 
are being measured.” 
The first part of the present paper deals with this aspect of the inquiry, and 
gives the results of a series of preliminary determinations of the relative thermal 
* Sci. Trans. Roy. Dub. Soc., vol. vii., partiv. ; and vol. viii., parti. (1902). 
Tt See Proc. Institute Electrical Engineers, 1902, vol. xxxi., part 156. 
TRANS ROY. DUB. SOC., N.S., VOL. VIII.—PART IX. U 
