238 ELECTROLYSIS. 



chloride of aluminium and 4 parts of dried and pulverised sodic 

 chloride. He filled with this solution and up to the same level, 

 a varnished porcelain crucible and a well dried porous porcelain 

 tube placed in the middle of the crucible. A platinum plate 

 and a carbon plate were respectively used as negative and 

 positive poles. The crucible was kept constantly heated. As 

 soon as the electric current passed, the aluminium and the sodic 

 chloride were deposited on the platinum plate, and the chlorine 

 with a little chloride of aluminium evaporated. The deposit 

 was afterwards treated by water in order to dissolve the sodic 

 chloride and the grey powder united into a regulus, by suc- 

 cessive fusions, by means of the double chloride of aluminium 

 and sodium as flux. 



M. Sainte-Claire Deville afterwards prepared aluminium 

 from sodium without using an electric current, and obtained 

 a superior result with this second method which is outside our 

 subject. 



BECQUEREL'S PROCESS FOR THE GOLD, SILVER, AND COPPER 

 ORES. Becquerel more than thirty years ago described a com- 

 plete method for the electric treatment of silver, lead, and 

 copper ores ; this method, ignored by many inventors, had the 

 privilege of being from time to time patented under different 

 names, and especially in countries where the legislature does not 

 admit of an examination previous to the granting of the patent. 



The complete description of the said process is to be found 

 in the 'Traite d'electricite et de magnetisme/ by Messrs. C. 

 and E. Becquerel, published in 1875. We will give a brief 

 account of them. 



The treatment of ores by the wet method, due to this 

 celebrated scientist, is based on the property possessed by 

 silver chloride and plumbic sulphate to dissolve in a saturated 

 solution of sodic chloride and sulphate of copper in water. 



The chloruretting of the silver is effected by the wet or dry 

 method, according to the state of combination of the silver in 

 the ore ; the wet method is used when the silver is in a metallic 

 state, or in a state of simple sulphide ; the dry method is neces- 

 sary if the silver is in a state of double sulphide. 



To chloruret a silver ore, the first operation consists in 



