168 Profs. Hagen and Rubens on some Relations 
and the value « * of Table II. in place of the conductivity A 
given in electrostatic measure, we obtain 
36°5 
(100—R) = / KX ° : : ° : . (3) 

or 
(100—R). V«e= . =CAu |. eee 
Therefore the relation between the reflecting-power and the 
conductivity of metals, experimentally given in the region of 
long waves, corresponds perfectly with the demands of Max- 
well’s theory. The value of the constant C,=(100—R) V« 
is, according to Table IL., 
194 at X= Au 
LO. hi Sp 
fies ext 
and the corresponding theoretical values of the constant C,, 
computed from the Maxwell equation (4), are 
18°25 for 4u 
‘ 17 Oe 
L054 55.512 
They show a better agreement with the values given above 
than might have been expected or even hoped for. 




TaBie III. 
(100—R) for X=12n. 
Metals. 
Observed. | Computed. 
Gilets: cccdnessachaseareeee seam 1-15 13 / 
COpPer nw. cnseas oust ceases 16 ee! 
ONE 6; sos Coa cee boxe eee 21 1°6 
Platmuwi)s. 5.0.4 .asac teen | 3°5 ) 35 
NIGKEl 656.3 Sane. vee eee ee 4-1 | 36 
SL 2] Rae 7 UR emmeceaes Stef 2), 4-9 ) 47 
Bramiitln. hee cceeei eo (17°3) 11°5 
Patent Nickel P ...<.:5/.ccs<e a 6 : 54 
Patent Niekel Me 3.007 ee-cene: 70 | 6:2 
Constantin (ee tee. & 22. Son 6:0 ) (pe: 
| Rosse’s Alloy....... ..s:esssee+e | ri . 73 
| Brandes and Schiinemann’s } | 9-1 86 | 
ALOY.. <2. o3tapens. eee H | ) 
BoA a ee a 
* « is the reciprocal value of the resistance of a conductor one metre 
long and of one square millimetre cross-section in ohms. 
