438 
PROFESSOR C. H. LEES: THERMAL AND ELECTRICAL 
Table of Electrical Resistivities, and of the Ratio of Resistivities at -170° C. 
and at 0° G. 
p in ohms per centimetre cube. 
Po- 
d-Wdo- 
do- 
-r 
o 
'Sr 
o 
Copper . . . 
1•62 x 10 ® 
•253 
Tin .... 
10-16 x10~ 6 
•307 
1 -56 
•241 D.F. 
13-1 
•310 D.F. 
1-58 
N* 
Lead. . . . 
19-6 
•345 
Silver.... 
1-55 
•326 
20-4 
•343 D.F. 
1-49 
•317 D.F. 
— 
•345 O.C. 
_ 
•305 O.C. 
19-8 
N. 
1-51 
N. 
Iron .... 
13-16 
•383 
Aluminium . . 
2 • 72 
•257 
9-11 
•188 D.F. 
2-58 
•272 D.F. 
10-7 
N. 
2-62 
N. 
Nickel . . . 
12-08 
• 465 
Zinc .... 
5-92 
•328 
12-35 
•207 D.F. 
5-77 
•312 D.F. 
12-0 
N. 
Cadmium 
7-12 
•343 
10-0 
•343 D.F. 
The values of the ratio p_ in /p 0 in the case of Dewar and Fleming’s metals have 
been calculated from their tables of results with the help of Callendar’s table,! 
connecting their platinum temperatures with hydrogen temperatures. 
From this table it follows on the strength of Matthiessen’s rule that impurity 
raises the resistivity, that the materials used in the present experiments were, in 
some cases less and in some cases more pure than those used by Dewar and Fleming. 
In most cases the difference is not large, but in the cases of cadmium and tin the 
materials used have a considerably less resistivity, and in the case of iron a consider¬ 
ably greater resistivity than those used by Dewar and Fleming. In the case of 
nickel and iron the ratios of the resistivity at —170° C. to that at 0° C., are much 
larger than the corresponding ratios calculated from their observations. The total 
amount of impurity present in each of these specimens is less than 1 per cent-., so 
that the influence of even small quantities of impurity seems to be very marked. 
The table of values of the product of electrical conductivity into absolute tempera¬ 
ture, given on p. 437, shows a general tendency for the product to increase with 
decrease of temperature for all the metals tested except iron and nickel, and these 
contained a little impurity. The increase is relatively small in the case of lead, 
Niccolai’s results, ‘ Accad. Lincei At-ti,’ 16, p. 906 (1907). His results at low temperatures have 
not been used, as there is no indication that the temperature readings of the thermo-junctions used by him 
have been reduced to the hydrogen scale. 
t Callendar, ‘Phil. Mag.,’ 47, p. 214 (1899). 
