168 
DBS. A. MATTHIESSEN AND C. YOGrT ON THE INFLUENCE .OF 
a similar manner. The reason for grouping alloys made of different metals under 
different heads has already been elsewhere discussed*. It has also been only considered 
necessary to experiment on one wire of each alloy, as the results obtained agree, in most 
cases, very closely with those calculated, and as it has been proved by a few determina- 
tions, which are given in Table I., that the same values were obtained for the percent- 
age decrement in the conducting-power of the alloy between 0° and 100°, when series of 
determinations were made with two wires of the same alloy. 
. Table I. 
Alloy. 
Volumes per cent. 
Percentage decre- 
ment observed be- 
tween 0° and 100°. 
Gold-copper (hard drawn) . . . 
98-63 of Au 
21-87 1 
Gold-copper (hard drawn) . . . 
98-38 „ 
21-75 
Gold-silver + (hard drawn)... 
52-08 „ 
6-50 y 
Gold-silver (hard drawn) . . . 
52-08 „ 
6-48 
Gold-silver (annealed) 
52-08 „ 
6-72 J 
Gold-silver (annealed) 
52-08 „ 
6-70 1 
Gold-silver (annealed) 
52-08 „ 
6-71 1 
Gold-silver (annealed) 
79-86 „ 
10-15 f 
Gold-silver (annealed) 
79-86 „ 
10-21 J 
Tin-cadmium 
23-50 of Sn 
28-89 1 
Tin-cadmium 
23-50 „ 
29-08 J 
Remarks. 
Series made with wires of different 
specimens of the alloy. 
Two series of determinations made 
with the same wire. 
Series made with different wires of 
the same specimen of the alloy. 
The method and apparatus employed for the determination of the conducting-power 
at different temperatures was the same as that described and used for the experiments 
on the pure metalsf. We have, however, in many cases only taken observations at 
three intervals, as we found that almost the same formula was deduced from observations 
made at three different temperatures as from seven, especially when the temperature of 
the second observation was the mean of the other two ; now as three or more observa- 
tions were made at each interval, it was easy to obtain the wished-for temperature as 
the mean of several determinations. Thus the formulae deduced for correction of con- 
ducting-power for temperature of the alloy Cd Pb 6 were — 
From seven observations . . . X=9-287— 0-03250l£+0-00006743f. 
From three observations . . . X=9‘286— 0-032450^+ 0-00006683^. 
Again, those deduced for the alloy Sn 2 Zn were — 
From seven observations . . . X=16 , 876 — 0 - 065544£+(H)00147l£ 2 , 
From three observations . . . x=16 - 899— 0 , 065790£-f-0 , 0001454£ 2 , 
where A represents the conducting-power at t° C. 
We have here taken, as in former papers, the conducting-power of a hard-drawn 
silver wire at 0°=100 as defining our unit. The normal wires were made of german 
silver, the resistances of which were determined by comparing them with the gold-silver 
alloy J, the conducting-power of a hard-drawn wire of which is equal to 15-03 at 0 G . 
* Philosophical Transactions, 1860, p. 162. f Ibid. 1862, p. 1. 
t Philosophical Magazine for February 1861. 
