THE ELECTRICAL RESISTANCE OF CERTAIN ALLOYS. 603, 
TABLE II. 
Resistance. 
Temperature. 
Observed. Calculated. 
GO" C. 7-170 7165 
38:0 7215 PATE 
50°6 7-245 7:246 
69:0 7:285 7:288 
85:2 B25 7323 
102°7 73575 7:360 
118°7 7:395 7:392 
135-4 7425 7425 
1513 7455 7-455 
These results may be combined in the formula : 
R=7'126 + :00248¢— 00000227, 
whence 
r=1+'000348022 — 000000280662’, 
and 
k=1—:00034802¢ + 000000401782. 
With this we may compare the formula which MATTHIESSEN and Vocr™ give for 
an alloy of the same metals containing 19°65 per cent. by volume of platinum, viz., 
k=1—-00033005¢ + :000000208032?. 
As in the former case, their formula applies only between 10°C and 100°C., and 
the discrepancy, though not great, may be partially due to this circumstance. 
The following table contains the coefficients of corresponding formule for 
platinum and silver whose temperature limits are not very different from our own. 
Metal. kor 7. A. B. Lime (Cy Observer. 
Platinum, | & — ‘0027461 + 0000046494 i = Wee Lenz. 
“5 r + 0032724 0 0° - 200° ARNDTSEN,. 
Silver, k — ‘0036568 + ‘0000058993 0° - 213° Lrnz. 
. r + 0034142 0 0° — 200° ARNDTSEN. 
* k — ‘0038287 + 000009848 10° — 100° MatrHigssEeNn and von 
Bose. 
Again it is clear that the rate of variation of the resistance of the alloy is 
less than that of either of its constituents. 
Silver-Palladium Alloys. 
Table III. contains results of measurements of an alloy, 25 per cent. of which 
by mass and therefore about 23°6 per cent. by volume is palladium. 
* Phil. Trans. Roy. Soc. Lond., vol. cliv. (1864), p. 167. 
