REFINING OF COPPER AND LEAD. 201 



30 square metres, which corresponds to a total active surface ol 

 1200 square metres. 



The cathodes of refined copper are about 1 millimetre in 

 thickness. 



The distance between the anodes and the cathodes is about 

 5 centimetres. 



The quantity of copper deposited per hour is 30 50 kilo- 

 gratnmes, and per day about 8000 kilogrammes. The machine 

 has worked day and night for the past nine years. The 

 expended motive power is 16 horse-power, which corresponds 

 to 4,320,000 kilogrammetres per hour. Each kilogramme of 

 copper thus treated therefore consumes 141,700 kilogrammetres 

 (about one-half horse-power per hour). 



The Norddeutsche Affinerie possesses besides, two other 

 series of baths, which still further economise the motive power. 

 These baths, 120 in number in each series, are joined in tension. 

 Each of them has 15 square metres of surface of anode, and a 

 resistance of '00084 ohm. The total resistance of the 120 

 baths is therefore 1 ohm. 



The current is produced by two Gramme machines No. 1, 

 joined in tension, and is of a maximum capacity of 300 amperes, 

 with 27 volts of total electromotive force at 1500 revolutions 

 per minute. 



The quantity of copper refined is 900 kilogrammes per 

 twenty-four hours. 



The motive power expended is 12 horse-power, which 

 corresponds to about 80,000 kilogrammetres per kilogramme 

 of copper refined. 



We will again refer to this installation, which in concep- 

 tion is the best in existence. 



MESSRS. OESCHGER, MESDACH & Co.'s WORKS. Messrs. 

 Oeschger, Mesdach & Co. have installed in their factory at 

 Biache-Saint-Waast (Pas de Calais), a Gramme machine iden- 

 tical with that which had been built for M. Wohlwill, and 

 which is illustrated p. 200. 



This machine supplies the current to twenty baths, and its 

 daily production is 400 kilogrammes. 



The vats are made of wood, nearly 3 inches thick, and lined 



