between Optical and Electrical Qualities oy Metals. 163 
very satisfactorily with the results obtained in our previous 
researches. 
It is well known that the reflecting-power of metals is 
subject to very rapid changes in the ultra-violet and visible 
spectrum. That is not the case in the infra-red ; for this 
spectral region the curves of fig. 2 show a very regular form 
eceeaaee aan 
cies eo ee et ep 
O10) Wisit2: As le 

Cst. stands for Constantan, Mg/. for Magnalium, B. § S. for Brandes 
and Schiinemann’s alloy. The curves for Patent Nickel M and P lie very 
close to that of Constantan. The visible spectrum (from A=0°45 p to 
A=0'7 ») is marked by the two small vertical lines at the left-hand 
corner of the curves. 
for all the metals and alloys. In every case the curve rises 
asymptotically to R=100 per cent. On comparing the 
reflecting-powers of different metals with each other in the 
region of greater wa 8, e to their 
reflecting-power—the 2 always bis the same order of 
succession. This law is still more obvious when we consider 
the intensity entering the metals (100—R) instead of the 
reflecting-power (R). Although (100—R) diminishes conti- 
nually with the increasing wave-length, it does so in the same 
M2 



