( 589 ) 
Hence, if we characterize the Prrrrer-effect by the absorption of 
heat I, ;, taking place in this case, 
K 9, a 4B | A7 2 a a Ni 43 
== Nu == = —— Wg En . . . J 
Suid FC aati. area mm oy, 
Dh. In the second place, substituting again for / the value (14), 
we shall apply (42) to a homogeneous part of the circuit. We have 
then to consider loy A as a function of the temperature 7’, so that 
we may write 
1 
2aT dlog A 
Ln 
for the heat developed between two points kept at the temperatures 
T and 7+d7, if a current of unit strength flows from the first 
point towards the latter. What Kervin has called the “specific heat 
of electricity’ (THomson-effect) is thus seen to be represented by 
2aT dlog A 
de rds 
(44) 
u=—T— 
$ 14. An important feature of the above results is their agreement 
with those of the well known thermodynamic theory of thermo- 
electric currents. This theory leads to the relations 
— 7 d HH U 45 
Ur — U = AT Pr 5 A NL deeds : 5 ( oD) 
and 
fed 
SOE 
Dd at Pers eyes 0) 
1 
T' 
in which wy and wy are the specific heats of electricity in the 
metals I and II, at the temperature 7, whereas / denotes what we 
have calculated in § 10, viz. the electromotive force in a circuit 
composed of these metals and whose junctions are kept at the 
temperatures 7” and 7", the force being reckoned positive if it 
tends to produce a current which flows from L towards I through 
the first junction. 
The values (44), (45) and (85) are easily seen to satisfy the 
equations (45) and (46). 
Instead of verifying this, we may as well infer directly from (42) 
that our results agree with what is required by the laws of thermo- 
dynamics. On account of the first of these we must have 
2 Gi = — FF 
and by the second 
