( 588 ) 
if 
Ww NDE Ee (40) 
Eh 
and 
WV Spe EO a NEN 
7, h exh 
§ 18. The expression (37) for the amount of heat produced in 
the element dv may now be divided into three parts. 
The first of these 
12 
WI da 
oz 
; de 4 
corresponds to Jounn’s law. Indeed — is the resistance of the part 
of the circuit extending from (2) to (ez + da). 
The second part 
d 
er (W, =) de 
is entirely independent of the current, as appears from (40). It may 
therefore be considered to be due to ordinary conduction of heat. 
This is confirmed by comparing it with what has been said in $ 9. 
It remains to consider the quantity of heat 
d 
7 di aA We =) de, 
or, if (389) and (41) are taken into account, 
mid log A 
Sere agin 
This expression, proportional to the current and changing its sign 
if the latter is reversed, will lead us to formulae for the PrLtmr- 
effect and the Tuomson-effect. Reduced to unit current, it becomes 
: m dlog A j 3 
Ca Zeh da EAN a (42) 
a. 1 shall suppose in the first place that, between two sections 
of the ecireuit, there is a gradual transition from the metal I to the 
metal II], the temperature and consequently / being the same through- 
out this part of the circuit. Then, reckoning « from the metal I 
towards II, and integrating (42), I find for the heat produced at the 
“place of contact” by a current of unit strength flowing from I 
towards II, 
m Ajj 200 Aq 
lon - log 3 
POI Noa SCM NCA 
