﻿Electrical Resistance of Alloys. 600 



while that of alloys was not greatly changed. It seemed 

 possible, therefore, as the temperature was reduced, that the 

 true resistance of an alloy might decrease and the false 

 resistance become relatively great, Experiments similar to 

 those described above were therefore made with alloys at the 

 temperature of solid C0 2 and of liquid air, but in no case 

 could any false resistance be found. 



Other experiments with a 20-ohm coil of German silver 

 balanced against one of lead gave similarly negative results. 

 Whether this is due to the frequency being too small to 

 overtake the equalisation of temperature of the junctions, 

 future experiments, which I hope to carry out, will perhaps 

 determine. 



The experiments of Hagen and Rube us * on the reflecting 

 and emissive powers of metals for infra-red rays do not help 

 us. They show that the electrical conductivity can be found 

 by measuring the reflecting or emissive powers to within a 

 few per cent. Alloys do not occupy an exceptional position. 

 The experiments do not put in evidence the magnet properties 

 of iron and nickel. 



In any case indirect evidence in favour of Rayleigh's 

 theory is not wanting. Liebenow gives the results of his 

 calculation in a form involving two constants, which he calls 

 the inner molecular heat conductivity of the metals. By 

 assigning proper values to these the formula expresses well, 

 in some cases such as gold and silver excellently, the relation 

 between resistance and composition when applied to the 

 measurements of Matthiessen, Feussner, Haas, and others. 

 They are not, however, altogether convincing. The heat 

 conductivities to be ascribed to the different molecules seem 

 to bear no relation to the conductivities as usually measured 

 in the mass. Thus, taking the heat-conduction of copper as 

 unity, silver requires to be taken as 2 C 3 and gold as 2, while 

 copper-zinc has the value 3 ascribed to it. 



1 might also point out that a frequent constituent of the 

 high resistance alloys in common use is nickel, a metal for 

 which the Peltier effect and other thermo-electric properties- 

 are strongly pronounced. 



In conclusion I have to thank the Government Grant 

 Committee of the Royal Society for help in defraying the 

 cost of this research. 



Cass Institute. 



London, E.C. 



* Annul d. Physik. vol. ii. p. 873 (1903). 



