METALLIC WIRES BY ELECTRICITY. 467 
Experiment 48.—A wire of the same thickness, 10 lines long. 
Number Quantity Indication of 
of jars. of electricity. thermometer. 
ie q- 6. a. 
4* % 78 1°24 
6 9:0 1:00 
eishih 12°8 1:04 A bend in the wire. 
9 Lych 0°87 The same. 
10 20°6 0°82 Wire is incandescent. 
ll 24°0 0:79 The same. 
12 OTe 0°75 The wire is white-hot. 
bor 28:0 0°93 The wire is broken to 
pieces. 
In those cases where destruction of the wire ensued, the value 
of & is calculated, not for the whole quantity of electricity g, but 
for 0°77 g, retaining the whole amount of intensity, as nearly 
0°23 of the whole quantity used remains behind in the battery 
(p. 461). 
If the retarding power of the thin wire in the connecting cir- 
cuit is expressed by V, then former researches show that the 
_ magnitude of « is proportional to , in which the value of 
1 
14+6V 
6 is dependent upon the constant part of the connecting circuit. 
The visible decrease of the value of « in the above experiments, 
which with the discharges employed only happened when the 
thin wire was used, indicates therefore an increase in the retard- 
ing power of this wire. Beginning with the discharge which 
produced the first mechanical effects, the wire obstructs the 
following discharges so much the more the stronger they are. 
But these retardations do not keep even pace with the increase 
of the discharge ; certain periods are observed, within which they 
vary but little, and these periods are in evident connexion with 
the effects of the discharge. Thus the first considerable increase 
of retarding power occurs when the wire is violently shaken by 
the discharge, the second with the appearance of bends in the 
wire, and when the wire at length fuses the retarding power 
again decreases. Thus the first conjecture which presented 
itself is contradicted, that the retarding power of a wire is de- 
pendent upon the temperature which the wire acquires by the 
discharge (in which case the discharge must be considered as 
dissected into the different pulsations, of which it is composed). 
