[ iy 9 
V. 
ON SOME NOVEL THERMO-ELECTRIC PHENOMENA. 
By W. F. BARRETT, F.RB.S., 
Professor of Experimental Physics in the Royal College of Science for Ireland. 
(Pratt Xa.) 
[Read Frsruary 22, 1899. | 
In the course of a determination of some of the physical properties possessed by 
various new alloys of iron, which had been prepared by Mr. R. A. Hadfield, of 
Sheffield, I found the thermo-electric behaviour of a particular nickel steel, to 
which five per cent. of manganese had been added, to be so remarkable that it 
seemed worthy of a separate note. 
The analysis of this alloy (kindly supplied to me by Mr. Hadfield) was as 
follows :— 
IRD, 6 . 68°8 per cent. 
Nickel, : 5 OW es 
Manganese, : » BW - 
Carbon, af vrlGe 55 
The specific electrical resistance of this alloy was found by Mr. Brown and 
myself to be higher than any other alloy we had hitherto examined.* It amounted 
to no less than 97°52 microhms per cubic cent. (at 15° C.). At the same time its 
variation of resistance with change of temperature was comparatively small, the 
temperature coefficient being 0:08 per cent. per degree C. (between 0° and 250° C.). 
The thermo-electric behaviour of the various alloys of iron which Mr. Hadfield 
had kindly placed in my possession was in course of investigation, and the 
enormous electrical resistance of this specimen, and of another similar alloy with 
somewhat less nickel, led me to try earlier than I should otherwise have done some 
of its other physical properties. 
A preliminary experiment was made by coupling a wire of this new alloy 
successively with different metals and testing the thermo-electric power of the 
various junctions up to a red heat. When an iron wire was used as the second 
metal the thermo-electric force quickly rose till a certain temperature much below 
redness was reached, and then remained almost stationary, notwithstanding the 
* See Trans. R.D.S., Vol. vu., Part 4. 
TRANS. ROY. DUBe SOC., N.S. VOL. VII., PARY VY. U 
