So WORK OF ELECTRICAL FORCES. 



certain conditions the discharges have a distinctly oscillatory cha- 

 racter ; but we shall see that these oscillations may be explained in 

 a totally different manner. Hence no conclusion can be drawn in 

 favour of the hypothesis which assigns a certain inertia to electrical 

 masses, and in the present state of science no decisive fact can be 

 claimed for or against this hypothesis. 



93. DISCHARGE OF BATTERIES. QUANTITY BATTERY. Total 

 Discharge. We have seen that the capacity Q of a battery 

 arranged for quantity is equal to the sum of the capacities of each 

 of the jars. 



If the total energy of the battery is transformed with heat during 

 the discharge, then, calling J the mechanical equivalent of the unit 

 of heat, and Q the heat disengaged, we have 



W = -MV = -~ = C 1 V 2 = JQ. 



2 2 L^^ 



If the battery consists of p identical jars, of capacity C, the 

 formula becomes 



We thus see that, for a given charge, the energy, or the heat 

 disengaged, is inversely as the number of jars, and that for a given 

 potential the energy is proportional to the number of jars. 



94. Incomplete Discharge. Let us consider two batteries of the 

 capacities C x and C 2 , the former charged with a mass M and the 

 second in the neutral state, the outer coatings being connected with 

 the earth. Let us suppose that instead of discharging the first, we 

 join the coatings so as to form a single jar of the capacity C x + C 2 . 

 The discharge is said to be incomplete; it represents a loss of energy, 

 and produces a disengagement of heat. Before contact, the potential 

 energy of the first battery was 



After contact, the energy of the system has become 



