186 
DRS. A. MATTHIESSEN AND C. VOGT ON THE INFLUENCE OF 
Table XVI. ; and therefore, if the values in Table XIV. were smaller, those in the 
columns headed r 100 o— r' 100 o and r 0 o — would agree much better together. 
If 
^100° ^ioo 0== ^V 4 (^) 
be correct, we may suppose that 
r t T t ~r Q o — r„o ; 
that is, the absolute difference between the observed and calculated resistances of an alloy 
at any temperature is equal to the absolute difference between the observed and calculated 
resistances at 0° C. ; or, in other words, 
r t — /^constant. (4) 
Table XVII. contains some examples which show this to be the case. 
Table XVII. 
Alloy. 
T. 
r. 
r'. 
Difference, 
0° 
1092-9 
10050 
879 
20 
11710 
1083 0 
880 
CdPb e ■ 
40 
1253-1 
1164-9 
88-2 
60 
13387 
1249-8 
88-9 
80 
1424-5 
1335-8 
88-7 
100 
15106 
1422 2 
88-4 
( 
0 
11904 
10021 
18-83 
20 
12711 
107-98 
1913 
Gold-copper, containing 0 7 1 j 
volume per cent, of gold . . . j 
40 
135-44 
11616 
19-28 
60 
143-92 
124-63 
19-29 
80 
152-39 
133 21 
1918 
l 
100 
160-64 
141-76 
18-88 
( 
0 
468-71 
121-36 
349-35 
: 
20 
479-00 
13077 
348-23 
Gold-silver, containing 79-86) 
40 
489-38 
140-67 
348-71 
volumes per cent, of gold... j 
60 
499-93 
150-92 
34901 
80 
510-57 
161-31 
349-26 
l 
100 
521-30 
171-67 
349-63 
The values given in the column r were calculated with the help of the formulae from 
Tables VII. and IX., those in the column r' with that deduced for the correction of 
conducting-power for temperature of most of the pure metals, namely, 
If, now. 
A=100-0-37647£+0-0008340f. 
r t -r ! t — constant, . . , 
( 4 ) 
it is clear that we may deduce the formula for the correction of resistance or conducting- 
power for temperature of an alloy as soon as we know its composition and its resistance 
at any temperature ; for, as / 100 . , , and r\ may be calculated by means of the formula 
given for the correction of conducting-power for temperature for most of the pure 
metals, viz. 
A=100— 0-376472+0-0008340* 2 * 
Loc. cit. 
