602 PROFESSOR MACGREGOR AND DR KNOTT ON 
Metal. |& or 7. A. B. Limite (C). Observer. 
Tron, k - 00472 + 0000084664 0°- 244° | Lznz.* 
* r + ‘004726 0 low temps. Ep. Becqu@ret. + 
s r + 0041304 + 0000052713 0°- 200° | Arnptsen.t 
. k — 0051182 + 000012915 10°—100° | Marruiessen and Voer.§ 
5 i + 004516 + 000005828 100°- 860° | Benort.|| 
Gold, k — ‘0021341 + 0000030684 18° —284° | Lenz. 
. r + 003397 0 low temps. Ep. Brcqueret. + 
= k — 0036745 + 000008443 10°-100° | Marraressen and von 
Boss. ** 
a r + 003678 + 000000426 100° - 860° | Benort.|| 
It will thus be manifest that the rate of variation of the alloy’s resistance 
with temperature for any ordinary temperature is not intermediate between 
those of its constituents, but is less than either of them. For 
© for our alloy = —-00037198 + 00000104108, 
while according to MATTHIESSEN, VocT and von Bosz, whose temperature limits 
agree more closely with ours than the others’, 
& for iron = —-0051182 + 000025834, 
& for gold= —-0036745 + “000016886. 
The above is true also, whichever of the values given in the table we regard as 
the most exact.tt 
Silver-Platinum Alloy. 
Table II. gives the results of experiments with our only silver-platinum 
alloy. It contained 35 per cent. by mass or about 211 per cent. by volume of 
platinum. 
* Mem. de l’Acad. des Sci, de St. Petersbourg, t. ii. (1833), p. 652. 
+ Comptes Rendus, t. xxii. (1846), p. 416. 
t Pogg. Ann., Bd. civ. (1858), p. 1. 
§ Phil Trans. Roy. Soc. Lond., vol. cliii. (1863), p. 373. 
|| Comptes Rendus, t. Ixxvi, (1873), p. 342. Burnorr has corrected his results for change of 
dimensions. 
{| Mem. de l’Acad, des Sci. de St. Petersbourg, t. iii pt. 1 (1838), p. 451. 
** Phil. Trans., vol. clii. (1862), p. 23. 
tt See ArnpTsEN, Pogg. Ann., Bd. civ. (1858), p. 57. 
