TREATMENT OF ORES. 243 



treatment of ores is good, but more expensive than the ordinary 

 metallurgical process. It is exactly as if it were sought to 

 obtain motive power by boring artesian wells; the engineer 

 consulted would answer: This system may be adopted, par- 

 ticularly in countries where fuel is at an extraordinarily high 

 price, and where no waterfalls are to be found. 



It must be observed that Becquerel's works took place long 

 before the invention of continuous-current dynamo-electric 

 machines, notwithstanding which the question of production 

 of electricity never jeopardised the success of his works. The 

 factory which he established at Grenelle was well organised ; 

 the necessary electric currents were produced at a very moderate 

 cost, and all the operations were well co-ordinated. If Becquerel 

 has not obtained an industrial success, it is simply owing to the 

 fact that the processes of amalgamation and roasting in ordi- 

 nary use are more economical than the treatment by means of 

 sodic chloride. Things were thus thirty-five years ago, and 

 they have not altered since. 



LAMBOTTE-DOUCET'S METHOD. This process, applied to 

 zinc ores, has been tried at the Bleyberg mines. It consists 

 in dissolving the previously roasted ore in the hydrochloric acid 

 of commerce so as to obtain a neutral and concentrated solution 

 of zincic chloride. The iron is eliminated by means of chloride 

 of lime and oxide of zinc ; it precipitates in a state of ferric oxide. 

 The chloride of zinc thus obtained is submitted to the action of 

 the electric current with graphite anodes and zinc cathodes. 



Under the action of the current the zinc is deposited on the 

 cathode, and the chlorine is liberated at the anode. Under 

 these conditions the anode polarises rapidly ; the solution, 

 originally neutral, becomes acid, and soon after the current 

 does not precipitate any more metal. 



LUCKOW'S METHOD. This process is based on the use of 

 the zinc ore as an anode. The electrolysis is done in large 

 rectangular baths. The cathode is constituted of a zinc plate, 

 and the anode of a mixture of ore and coke placed in an open- 

 work case. A wooden frame loaded with lead and covered with 

 a thick tissue is placed under the cathode in order to collect 

 the precipitated zinc. The froth which, during the operation, is 



R 2 



