Degrees of Heat in Absolute Measure. 73 



If, owing to the transference of energy, electromotor forces are 

 formed in the interior (thermoelectricity), for no element in 

 which they arise does either Joule's or Ohm's law hold. Yet 

 even in this case the latter equation seems to retain its validity ; 

 for it agrees with the observation that a constant current which 

 passes through one section of a conductor from a less to a 

 greater tension produces an absorption of heat which is propor- 

 tional to the intensity of the current and to the increase of tension. 

 Yet in this case we disregard any possible thermoelectric 

 currents in the interior of the body, and we obtain from the 

 last equation, by means of equations (4), 



dt dx dx dy dy dz dz 



Comparing this equation with equation (2), we see that the 

 laws for the propagation of electricity by electrical conduction 

 and by thermal conduction have quite the same form ; the po- 

 sitive or negative electrical tension and the absolute temperature 

 calculated from absolute zero will correspond to each other, and, if 

 we choose the absolute measure for the degree Centigrade which 

 has here been proposed, may be measured with the same units. 

 In accordance with these equations a body will receive in each 

 element of its volume the same increase in energy, whether it be 

 unelectrical and have in various places a different absolute tem- 

 perature T, or whether it be uniformly warmed and have an 

 electrical tension +P whose numerical value in each point is 

 equal to T. It is, however, here presupposed that k has in both 

 cases invariably the same value, which is only approximately 

 true. In the next moment the ratio will be materially altered, 

 since the increase of energy in the electrical body occurs in the 

 form of heat, not of electrical tension. 



Hence the law for the propagation of electricity cannot be 

 determined by equation (7), which can only serve to define the 

 increase of energy, whereas, as we have seen, the laws for the 

 propagation of heat are defined by equation (2). If electricity 

 continuously moves without change through a body (and this is 

 the only case we can here deal with, as we do not take induced 

 currents into consideration), the quantity of electricity is in each 

 moment the same, and the equation then becomes 



n _ du .dv dw 

 dx dy dz 

 This equation, combined with equations (4), gives 



dx dx dy dy dz dz ^ ' 



The electrical tension will therefore have to be determined from 



