1 87 1.] Heat, and Force. 83 



different amount of heat is evolved in different circumstances, 

 or that the 'distribution of it is regulated, not according to 

 the resistance of the different parts of the circuit, but partly 

 according to these and partly according to the electro-motive 

 power of the metals used in the cells ; and that the total 

 heat circulating in the circuit is not equal to the heat pro- 

 duced by the chemical changes taking place. 



11. Let me add that the laws regulating the amount of 

 heat produced in each part of the external conducting-wire 

 of a battery seem to be tolerably well established, both by 

 the experiments of Miiller, on which they are based, and by 

 corresponding laws, regulating the heat produced in various 

 parts of a circuit by the discharge of Leyden jars; but that 

 where they utterly break down, is when we go on to extend 

 the same laws to the liquid cells of a galvanic battery and 

 to. the whole galvanic circuit. 



Note. After the above had been placed in the printer's 

 hands, I discovered the true law which generally regulates 

 the distribution of heat in! a galvanic circuit, and published 

 it in the " Chemical News," of Nov. 4th and nth, vol.xxii., 

 pp. 224, 238. The reasonings by which this law is estab- 

 lished being too late for the present number of the " Quarterly 

 Journal of Science," will be published either in an early 

 number of the " Chemical News," or in the next number of 

 the "Quarterly Journal of Science." I will merely add that 

 the law is as follows : — The heat produced in a battery is 

 divided into three parts ; (1) That arising from local action 

 which is confined to the battery ; (2) A given portion of the 

 residue also retained in the battery ; and (3) The remainder 

 which is transmitted through the circuit. Calling these 



IT 



H x , H 2 , and H 3 ; — — |— depends upon, and represents, the 



electro-motive force of the negative element in respect: to 

 the positive element. 



Indeed, the difference between one negative element and 

 another consists in the property they have of transmitting 

 different amounts of the heat produced in the battery. 

 Portions of H 3 are evolved in each part of the circuit, 

 including the battery, in proportion to the resistance of each 

 part. Hence if R be the battery resistance, and r the 

 exterior resistance of the circuit, HR and Hr the heat evolved 

 in the battery and in the external part of the circuit — 



HR = H r + H 2 + M . 

 R-f r 



and Hr== 3 

 R + r 



