M. P. A. Favre's Thermal Researches on the Battery. 311 



a battery of five elements. The acid was pure* in the first ope- 

 ration, while, in the last, half of it had been replaced by sulphate 

 of zincf. 





Tr , n Heat confined to 

 Value of r. the battery. 



millims. units. 



Heat expended in 



7000 millims. of wire 



units. 



. (1) 



(2) 



. . 70 1994 

 . .106 9282 



17840 

 10552 



hence 



Total heat of the 



circuit R+r. 



units. 



Heat confined 



to the battery. 



units. 





(1) . . . . 18018 



(2) .... 10712 



1816 

 9122 



What is the origin of this quantity of heat which thus re- 

 mains confined within the battery J? 



It seems to me that it can only be explained on the assump- 

 tion that the following actions come into play either together or 

 separately : — (1) the condensation of hydrogen upon the plati- 

 num, which becomes an obstacle to the transmission of the cur- 

 rent; (2) the local action due to the passage of the hydrogen 

 from the nascent to the ordinary state; (3) the action, also 

 local, due to the sulphatation of the zinc deposited on the pla- 

 tinum plates — a deposit arising from the electrolysis of sulphate 

 of zinc, as this salt continually increases in the liquid in which 

 the couples are immersed. 



I will first remark that if the hydrogen offers a passive resist- 

 ance to the passage of the current, this resistance is included in 

 the internal resistance of the battery, the thermal constituent of 

 which has already been calculated. Moreover I estimate that 

 no considerable fraction of the quantity of heat indicated by the 

 calorimeter in which is the battery (a quantity which increases 

 with the number of anterior operations) can be attributed to 

 the influence of the condensed hydrogen. 



III. I have confirmed a fact already stated by several phy- 

 sicists, that the quantity of hydrogen condensed on the surface 

 of the platinum is very small, and does not go on increasing in- 

 definitely. Working with two of Sm.ee' s elements joined to- 



* The sulphuric acid used, of a given degree of dilution, liberated 19,834 

 thermal units in acting upon zinc. 



f I may mention that in my couples the passive resistance which the 

 sulphate of zinc presents to the current is sensibly equal to that presented 

 by sulphuric acid. 



X In my previous experiments 1 had found this quantity equal sometimes 

 to 4000, sometimes to about 6000 units ; the variation is much greater in 

 the present experiments (from 1800 to 2000), but under well-defined con- 

 ditions. 



