104 
PHYSICS: E. H. HALL 
Proc. N. A. S. 
Zinc 
. c 
CiX 10« 
C 2 
Q 
5 
\' C X 10 16 
So 
5 100 
0.0613 
16.7 
0 
1.55 
7 
240 
0.015 
0.178 
0.238 
a (ergs/°C.) 
6 100 
noX io-* 
noXio" 
k 0 X 10* 
fciooXlO 18 
Data 
Calc. 
0.99r 
0.99 T 
0.266 
0.266 
0.262 
0.258 
211 
212 
274 
225 
180 
127 
CONSTANTAN 
c 
CiX 10« 
C 2 
<7 
5 
X'oX 10» 
h 
8 0 
5 100 
0.135 
141 
0 
1.55 
6 
65 
48 
0.003 
0.158 
0.215 
a (ergs/ 0 C.) 
e \oo 
OoX 10-" 
HiooX 10- 4 
koX10« 
&100X10 8 
Data 
7.94T 
0.052 
0 
064 
108 
106 
20.4 
20.4 
Calc. 
7.94r 
0 052 
0 
076 
108 
55 
Manganin 
c 
CiX10« 
C2X 108 
Q 
s 
X'oX lOi 6 
h 
K 
5 100 
0.050 
-98 
4.07 
1.51 
9.65 
54 
0 . 0034 
0.228 
0.311 
0 (ergs/°C.) 
K 
6 ioe 
noX io* 
niooX 10 4 
koX 10 6 
*iooX10» 
Data 
Calc. 
(-0.828 -0.0067/) T 
(-0.828 -0.0067/) T 
0.051 
0.051 
0.063 
0.068 
207 
206 
275 
223 
23.8 
23.8 
The preceding tabulation deals with every metal and alloy for which 
I have the necessary data, except cadmium, and for this metal, as I have 
shown elsewhere, 10 there is some reason for doubting the correctness of 
the data, Bridgman's value for <j in cadmium being about ten times as 
large as that found by other investigators. 
In the table that follows, 7 is the estimated ratio, expressed in per cents, 
of the number of free electrons to the number of atoms, including the 
positive ions, within the metal at 0° C. In arriving at the given value 
of 7 I have made use of the equation 
k = g (7) 
for the free-electron conductivity. The second member differs from 
Drude's familiar expression for the total conductivity, supposed by him 
due entirely to the free electrons, only in having 4 instead of 6 in the de- 
nominator. I have taken /, somewhat arbitrarily but not without re- 
gard to what others have done in this particular, as equal to ten times the 
centre to centre distance of adjacent atoms. 
