122 Barrer, Brown, aNd Haprintp— Researches on the 
appears to be the reduction in conductivity produced in iron alloyed with that 
element. Thus the tungsten-iron alloys are better conductors than the aluminium- 
iron alloys; the latter, in fact, having a very high resistivity, the atomic mass of 
aluminium being very low. This relation appears to hold true of the thermal as 
well as of the electrical conductivity of these alloys. 
The ratio &/k’ of the electrical to the thermal conductivity is best exhibited 
in the curve shown in fig. 3, where the ordinates represent the thermal and the 
abscissee the electrical conductivities given in Table VI., and referred to copper 
as 100. "he curve, it will be seen, is a fairly smooth one, and of parabolic form, 
except when the conductivities are very low. In that case the curve becomes 
So [| 
I 
wo 
Q. 
Qa. 
O 
aJ 
> 
8 ae 
oO 
aS 
=C) 
iS 
o 
O 
= eet 
E 
= 
@ 
i 
ood 
Electrical Conductivity, Copper =100 
Fig. 3. 
much steeper, that is, the magnitude of the ratio increases, which confirms 
Lorentz’s statement. The numerical value of the ratio, when the conductivities 
are expressed in C. G.S. units, is, however, much greater than that given by 
Lorentz. More exact measurements of the thermal conductivities in unannealed 
specimens of these alloys are urgently needed. Unfortunately we have been 
unable so far to carry this out, as Mr. Hadfield wanted the specimens at 
Sheffield. Moreover, owing to the present overcrowded state of the physical 
laboratory at the College of Science, it has been found impossible to carry on 
satisfactorily any original physical work for some time past, as the whole of the 
available space is occupied by students, 
