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XXXVI. Thermal Researches on the Battery. 

 By M. P. A. Favre*. 



I HAVE formerly insisted upon the utility of considering, in 

 the investigation of voltaic currents, the absolute quantity 

 of heat put in play in the whole circuit and in each of its parts. 

 The investigations contained in this paper have principally for 

 their object to ascertain the origin of the heat which is not found 

 in the circuit, and which is confined to the couples. As in this 

 abstract I cannot produce the numerous Tables referring to the 

 various series of experiments, I shall restrict myself to indica- 

 ting the tendency of the results and the conclusions which seem 

 to follow from them. 



I. I repeated Pouillet's experiments on the intensity of the 

 current according as we work with a single couple or with a 

 battery of any number of couples — the electromotive force and 

 the internal resistance of each couple being equal, and the ex- 

 ternal resistance II either equal to zero or varied by the intro- 

 duction of different lengths of wire. Working under these con- 

 ditions, I restricted myself to investigating the distribution of 

 heat corresponding to the resistances II and r of the circuit. 



I worked successively with one, two, three, four, and five 

 couples t, and found that for the same amount of chemical action 

 and the same finite value of R, the quantity of heat due to the" 

 internal resistance of the battery was greater than the quantity 

 due to that of the couple. Thus the calorific effects in both cases 

 are in the direction which Pouillet had remarked for the inten- 

 sities. 



II. I repeated the same experiments a great number of times 

 in succession, and without renewing the liquid, until at least half 

 of the sulphuric acid was changed into sulphate of zinc. It was 

 difficult to exceed this limit ; for when I made several couples 

 work simultaneously, R being equal to 0, the platinum of one or 

 more couples became covered with so large a quantity of zinc, 

 that it could not dissolve with sufficient rapidity, rendering 

 impossible any calorimetric determination. 



In each series of experiments II was made alternately =0 

 and =250, 500, and up to 7000 millims. of my normal platinum 

 wire, so that I could calculate the internal resistance of the 

 couple or the battery in each of the successive experiments. 



I give here the numbers furnished by the first and the last 

 operation of one of the series of experiments made by means of 



* Translated from the Comptes Rendus, November 23, 1868. 

 t The liquid was renewed each time. 



