On some Hovel Thermo-Electric Phenomena. 309 



have been discoverable in the part AA'. However, the 

 chlorine spectrum was easily obtained from AA X ; and on 

 comparison with BB' the intensity of the chlorine lines was 

 found to be the same in both cases. The tubes were fused on 

 again and the experiment repeated, making A the anode, 

 when the same result was obtained. 



This proves that if any convection of the chlorine does take 

 place, it is to an extremely small extent, and is certainly not 

 sufficient to account for the effect observed. 



To Prof. H. Kayser I wish to acknowledge indebtedness. 

 Physical Institute, Bonn, 

 February 1900. 



XXYI, On some Novel Tlier mo-Electric Phenomena. By 

 W. F. Barrett, F.B.S., Professor of Experimental Physics 

 in the Royal College of Science for Ireland*. 



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. 11. 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 : — 



Iron 68'8 per cent. 



.Nickel 25'0 



Manganese 5*0 ., 



Carbon 1*2 „ 



The specific electrical resistance of this alloy was found by 

 Mr. Brown and myself to be higher than that of any other alloy 

 we had hitherto examined f . It amounted to no less than 97 - 52 

 microhms per cub. centim. (at 15° C). At the same time its 

 variation of resistance with change of temperature was com- 

 paratively 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 resist- 

 ance of this specimen, and of another similar alloy with some- 

 what 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 testino- 

 * Communicated by Prof. G. F. FitzGerald, F.R.S. From a separate 

 impression of the Trans. Roy. Dublin Soc, vol. vii. pt. v. 

 f See Trans. R.U.S. vol. vii. pt. 4. 



Phil. Mag. 8. 5. Vol 49. No. 298. March 1900. Y 



