Joule. 343 



the manifestation, in another form, of the mechanical force 

 with which atoms combine ; on the other hand, the pheno- 

 mena of electrolysis by the voltaic battery give us positive 

 proof that the mechanical force of the current requisite to 

 procure the decomposition of an electrolyte is the equivalent 

 of the heat due to the recombination of the elements. 

 Thus it appears that electricity is a grand agent for con- 

 verting heat and the ordinary forms of mechanical power 

 into one another.^ 



On a New Method of Ascertaining the Specific Heat of 

 Bodies. Read December 2, 1845. Memoirs of Philoso- 

 phical Society of Manchester^ Vol. VII. Second Series, 

 p. 562. 



* When any body, capable of conducting the voltaic 

 electricity, is placed in the circuit of a battery, the quantity 

 of heat evolved by it in a given time is proportional to its 

 resistance to conduction and the square of the quantity of 

 transmitted electricity. Consequently, if a wire traversed 

 by a voltaic current be made to communicate to any body 

 the heat which it evolves, the capacity for heat of that body 

 and the wire taken together will be directly proportional 

 to the square of the quantity of electricity transmitted in a 

 given time to the resistance of the wire and to the time, 

 and inversely proportional to the increase of temperature 

 of the body. Hence we derive the general equation, 



where y is put for the capacity, c for the voltaic current, 

 r for the resistance of the wire, t for the time, and h for the 

 increase of temperature. 



