Joule. 34 1 



That equivalents exist is no proof of oneness, but we 

 see here great progress made by Faraday in the con- 

 sideration of the unity of power and the relation of import- 

 ant forms of power. 



We shall quote here some of Joule's early papers. 



On the Heat Evolved during the Electrolysis of Water. 

 January 26, 1843. By James Prescott Joule. Vol. 

 VII. , Second Series, Memoirs of the Literary and Philo- 

 sophical Society of Manchester, pp. 101, 103, 104, no. 



' ist. In an electrolytic cell, there are three distinct 

 obstacles to the voltaic current. The first is resistance to 

 conduction ; the second is resistance to electrolysis without 

 chemical change, arising simply from the presence of 

 chemical repulsion ; and the third is resistance to electro- 

 lysis accompanied by chemical changes. 



' 2nd. By the first of these (the resistance to conduction) 

 heat is evolved exactly as it is by a wire, according to the 

 resistance and the square of the current ; and it is thus 

 that a part of the heat belonging to the chemical actions 

 of the battery is evolved. By the second, a reaction on 

 the intensity of the battery occurs, and wherever it exists 

 heat is evolved exactly equivalent to the loss of heating 

 power in the battery arising from its diminished intensity. 

 But the third resistance differs from the second, inasmuch 

 as the heat due to its reaction is rendered latent and is 

 thus lost by the circuit. 



' 3rd. Hence it is that, however we arrange the voltaic 

 apparatus, and whatever cells of electrolysis we include in 

 the circuit, the whole caloric of the circuit is exactly ac- 

 counted for by the whole of the chemical changes. 



