BAEU8.] 
PYRO-ELECTRIC PROPERTIES OF ALLOYS. 
129 
stand-glass of distilled water ami making the customary measurements. 
To mak« the process more convenient the left-hand scale-pan was re- 
placed by a special lateral arm, being virtually a bent lever, the weight 
of which was concentrated as near its lower end as practicable, in order 
that the platinum rod might be hung as far from the center of figure or 
standard of the balance as possible. In this way abundant room for 
the stand-glass was easily secured. Measurements of density are sub- 
servient tor the calculation of specific resistances, but they have an 
intrinsic value of their own. 
Table 29 contains the results of the density experiments. In it I, q, 
and m refer to the length ( cm ), the section (a cm ), and the mass (g) of the 
bars of alloy. z/ t and A denote their densities at t° and 0°, respect- 
ively. The alloys are usually arranged in series of increasing percent- 
ages of alloy, but where more than three alloys are examined these 
percentages must be inferred from the values of Z/ . Special analysis 
of all the wires would be superfluous, for the reasons stated in the in- 
troduction. The results are intended to be purely physical. 
Table 29. — Density of platinum alloys. 
No. 

7 
9 
10 
10 
» 
12 
12 
13 
P 
14 
14 
15 
Alloy. 
Platinum , 
.. do 
...do 
Gold 
...do 
...do 
...do 
...do 
..do ... 
Silver 
...do 
...do 
...do 
...do 
.. do 
Palladium 
..do 
...do 
...do 
..do 
...do 
Iridium 
...do 
...do 
...do 
...do 
...do 
Copper 
...do 
...do 
...do 
i — do 
Bull.54- 
l 
<1 ■ 
m 
t 
At 
Ao 
22.80 
0.01233 
5. 9P89 

19.5 
21.305 
21.321 
22.18 
1187 
5. 6108 
18.0 
21. 297 
21.311 
22.18 
1187 
5. 6108 
12.6 
21.303 
21.313 
15.46 
0. 01333 
4. 3877 
20.0 
21.290 
22. 306 
15.45 
1335 
4. 3877 
13.2 
21.260 
21.270 
15.50 
1343 
4.4177 
20.2 
21.200 
21.222 
15.48 
1345 
4.4177 
13.4 
21.211 
21.221 
35.80 
0746 
5. 6434 
13.4 
21. 128 
21.138 
35.82 
0743 
5. 6433 
20.3 
21.191 
21. 207 
15.22 
0. 01285 
4. 1344 
20.3 
21. 138 
21. 154 
15. 23 
1282 
4.1346 
13.5 
21.163 
21. 173 
23.92 
1263 
6. 3454 
13.6 
20. 991 
21. 002 
24.05 
1265 
• 6. 3798 
20.3 
20. 964 
20. 980 
24.05 
0759 
3. 5377 
20.2 
19. 380 
19.396 
24.04 
0758 
3. 5381 
13.9 
19.394 
19. 405 
16.66 
0.01252 
4. 3754 
13.5 
20. 975 
20. 965 
16.65 
1250 
4. 3754 
13.8 
21.016 
21.027 
16.10 
1316 
4.3491 
14.0 
20. 523 
20. 534 
16.11 
1314 
4. 3492 
13.7 
20.535 
20. 546 
17.60 
1280 
4.4809 
13.9 
19. 892 
19. 903 
17.60 
1278 
4. 4810 
14.2 
19. 904 
19. 915 
16.34 
0. 01265 
4. 3896 
14.3 
21.237 
21. 248 
16.27 
1265 
4. 3819 
14.3 
21.283 
21. 294 
16.00 
1288 
4. 3865 
14.5 
21. 282 
21. 293 
16.01 
1289 
4. 3866 
14.6 
21. 252 
21.264 
17.95 
1280 
4. 8977 
14.8 
21. 308 
21. 320 
17.85 
1282 
4. 8804 
14.8 
21. 306 
21.318 
15.95 
0.01315 
4. 3335 
15.4 
20. 662 
20. 674 
15.68 
1317 
4. 2718 
14.8 
20. 666 
20.678 
14.74 
1298 
3.9415 
15.0 
20. 584 
20. 596 
15.02 
1293 
3.9990 
15.5 
20.592 
20. 604 
17.32 
1303 
' 4.2391 
15.8 
18.7c] 
1 797 
Ao 
Mean. 
21.315 
21. 288 
21.221 
21.172 
21. 163 
20. 991 
19. 400 
21. 006 
20. 540 
19. 909 
21.271 
21.279 
21. 319 
20. 676 
20. 600 
(783) 
