PHYSICS: P. W. BRIDGMAN 
11 
resistance itself; the direction of change may be either an increase or 
a decrease. Another statement of this fact is that the temperature 
coefficient changes very httle with pressure; this is shown in the second 
and the third columns of the table. This is perhaps surprising when 
it is remembered that the pressures used here are in many cases great 
enough to compress the metal to considerably less than its volume at 
0°Abs. at atmospheric pressure. The instantaneous coefficient de- 
TABLE 
METAL 
AVERAGE TEMPERATXJRE 
COEFFICIENT 0 TO 100° 
PRESSURE COEFFICIENTS 
At 0 kg. 
At 12 000 
kg'. 
Instantaneous coefficient 
at 0° 
Instantaneous coefficient 
at 100" 
Average coefficient 
0 to 12,000 kg. 
At 0 kg. 
At 12,000 
kg. 
At 0 kg. 
At 12,000 
kg. 
At 0° 
At 100° 
In 
-|- . UU4UO 
1 c\c\ 'iQi 
-.04226 
-.04016 
-.045103 
-.O4IO723 
-.04021 
-0.41313 
Sn 
447 
441 
byoO 
4iU0Z 
67 /O 
svzu 
.5951 
Tl 
517 
499 
41319 
4180 
41456 
4I2OO 
4151 
4226 
Cd 
424 
418 
41063 
6837 
4IIO6 
5887 
6894 
6927 
Pb 
421 
412 
41442 
4I22O 
41483 
4237 
4212 
4I253 
Zn 
416 
420 
5540 
5425 
5524 
b407 
64700 
b4544 
Al 
434 
435 
5416 
5365 
6397 
5373 
638 1 5 
53766 
Ag 
4074 
4069 
5358 
5321 
5355 
5331 
63332 
53362 
Au 
3968 
3964 
5312 
5286 
5304 
5292 
62872 
52918 
Cu 
4293 
4303 
6201 
479 
5I84 
475 
61832 
4770 
Ni 
4873 
4855 
458 
6142 
6163 
6156 
61473 
61575 
Co 
3657 
3676 
6941 
6814 
6755 
6704 
6873 
6726 
Fe 
6206 
6184 
5241 
6218 
5247 
5230 
62262 
62353 
Pd 
3178 
3185 
5198 
6190 
5I89 
487 
61895 
61863 
Pt 
3868 
3873 
5I975 
5I8I 
6190 
5I82 
61870 
61838 
Mo 
4336 
4340 
5I33 
426 
5I3O 
5I25 
5I286 
51265 
Ta 
2973 
2967 
5I49 
5I39 
6153 
5I47 
61430 
1486 
W 
3219 
3216 
5I28 
5I2I 
5I3O 
5I23 
5I234 
5I258 
Mg 
3901 
O555 
O555 
Sb 
473 
403 
+ Oal220 
+ 4IO64 
+ 6768 
+ 5723 
+ 4I22O 
+ 6768 
Bi 
438 
395 
+ 0454 
+ 4213 
+ 41524 
+ 4I8954 
+ 42228 
+ 419804 
Te 
-.00632 
-.O3I29 
10° to 20°, 20° to 24°, 3 extrapolated from 50°, ^ extrapolated from 75°. 
creases with rising pressure, as is natural, but it is at first sight strange 
that the percentage decrease is in nearly all cases less at the higher 
temperatures. 
The numerical results of the above table are not in particularly good 
agreement with the previous results of Lisell and Beckman.^ Sugges- 
tions as to the reasons for the discrepancies may be found in the detailed 
paper. Beckman has made extended application of his results to a 
theory of the pressure effect recently put forward by Gruneisen,^ and 
