PART IV. COST OF ELECTRIC LIGHTING. 



The expenses attending electric lighting are of various 

 kinds, and belong, independently of the first cost of the 

 apparatus, to 1, the production of the electric current; 

 2, the combustion of the carbons. It is true that for a 

 long time little attention was paid to this last expense, 

 because it was so small in comparison with the other. But 

 now when, thanks to induction machines and thermo-electric 

 piles, electricity can be cheaply produced, it has become im- 

 portant, and may reach a higher figure than the other, espe- 

 cially with electric candles. 



At various times important investigations have been made 

 regarding the cost of the voltaic arc, either with batteries or 

 with induction machines, and we are going to give the 

 briefest possible summary of them, although it must be con- 

 fessed that they are not yet sufficiently conclusive to be im- 

 plicitly relied upon. 



Cost of the Electric Light with Batteries. In an 



interesting Report presented in 1856 to the Societe d 'encourage- 

 ment, Ed. Becquerel states that when applied to the produc 

 tion of a voltaic arc, a Bunsen battery of 60 elements, having 

 zincs 20 centimetres high by 8*5 centimetres diameter, and 

 porous vessels 20 centimetres high by 6-5, consumed in 3 

 hours 956 grammes of zinc and 1,464 grammes of sulphuric 

 acid. This makes the cost about i franc per hour. Estimating 

 the expenditure of nitric acid at one equivalent of acid for 

 one of zinc, as shown by experiment, Becquerel estimated 

 the cost of that liquid at i franc 46 centimes, which would 

 give a total cost of 2 francs 46 centimes. But, as he points 

 out, the real cost is higher than that, for even if the zinc 

 that remains could be used for other purposes, the nitric acid 



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