40 REPORT—1863. 
of alloys in a solid state, from the determination of their conducting-powers 
for electricity*. 
The number of alloys experimented with was upwards of 250; they were 
all made of purified metals, and their conducting-power determined with a 
modification of Wheatstone’s balance, arranged by Kirchhoff, under whose 
direction the first results were obtainedt. The method of observation 
emanating from such a distinguished physicist is a sufficient proof of its 
accuracy and trustworthiness. And here a great difficulty in carrying out 
such researches may be mentioned ; for one is apt to fall into one of two errors: 
either the metals used for the experiments are not pure, or the method em- 
ployed for the determinations is faulty. Thus, for instance, compare the 
experiments on the influence of temperature on the electric conducting-power 
of the metals between 0° and 100°. Calling the conducting-power of each 
at 0° 100, at 100° it is, according to 
Conducting-power at 100° 
Saunt aie Lenz tf. Arndtsen §. Becquerel |. Ae Rar 
Silver .... 100 74:5 74:5 71:3 71:6 
Copper .... 100 rire ea lore 70°8 70:3 
CTOl disc fs 100 84:9 5 iting 74:6 rage 
PAG sha a ‘ae 100 te sctpats 731 71:2 
Cadmium .. 100 Lbs bisa 71:2 70-7 
irons, « <: 100 «cee 68:3 67°9 61:2** 
SP dons 100 71:8 ee 61:8 70-1 
Platinum .. 100 nh te 75°4 84-3 
Lead;...... 100 71:4 72°6 69-7 70-4 
Antimony... 100 he 5 wate a: 705 
Arsenic.... 100 ee ayat4 eee 69:9 
Bismuth .. 100 as sais Be 70:7 
Now Lenz and Arndtsen experimented with commercially pure metals. 
Arndtsen remarks at the end of his paper, ‘‘ From the foregoing data it is 
very probable that the influence of temperature on the conducting-power of 
all metals in the state of absolute purity would be found to be in all cases 
the same.’”’ Becquerel, on the contrary, used pure metals for his experiments, 
but his method of observation was very indifferent. The results given in the 
last column were obtained by the employment of Kirchhoff’s arrangement of 
Wheatstone’s balance, as well as pure metals. On looking at the above, it 
is obvious that from the last series we may deduce the law that the conduct- 
ing-power of pure metals (iron excepted) decreases between 0° and 100° in 
the same degree ; whereas from the others the existence of the law is only 
problematical. 
The conclusions drawn from the research on the electric conducting- 
power of alloys were as follows :— 
That in respect to this property the metals may be divided into two classes. 
A. Those metals (lead, tin, zine, and cadmium) which when alloyed with 
each other conduct electricity in the ratio of their relative volumes. 
B. Those metals (bismuth, antimony, platinum, palladium, iron, aluminium, 
gold, copper, silver, and probably most of the other metals) which when 
* Phil. Trans. 1860. + Phil. Mag. Dec, 1859. 
t Pogg. Ann. vol. xxiv. p. 418, and vol. xlv. p. 105. § Pogg. Ann, vol. civ. p. 1. 
|| Ann. de Chim. et de Phys. (3) vol. xvii. p. 242. 
“| Phil. Trans. 1862, p. 1. ** Proc. Royal Soe. vol. xii. p. 472. 
