254 ELECTROLYSIS. 



composition of the baths. An ulterior electrical action decom- 

 poses these chlorides in their turn, and gives metallic deposits 

 on the cathode. 



In order to obtain some result, even small, with this process, 

 the following conditions must be observed : 



1st. Polarisation at the anode and at the cathode must be 

 avoided. Polarisation is counteracted by giving a continuous 

 motion to the mass of ore, which liberates the adhering gas. 

 Continuous collection of the deposits at the cathode prevents 

 polarisation. 



2nd. In order to obtain a complete attack of the ore, it 

 must be submitted, in all its parts, to the action of the nascent 

 chlorine. This result is obtained by giving the mass a con- 

 tinuous motion, thus bringing all its points into contact with 

 the conductors of electricity. 



The experimental apparatus used by Mr. Lambert, consists 

 of a case divided into two compartments by means of a porous 

 partition. One of these compartments receives the bath in 

 which the cathode is immersed ; the cathode being a simple 

 copper strip, which is cleaned and replaced at regular in- 

 tervals of time. The ore is placed in the other compartment. 

 Electric conductivity is established by means of a carbon plate 

 facing the cathode, and upon which rest some transversal 

 partitions, also of carbon material ; so that the ore is main- 

 tained in a veritable carbon carcase. The stirring is obtained by 

 means of a current of water specially adapted for the purpose. 



Werdermanns Method. Amongst the numerous patents 

 taken out for the electro-chemical treatment of metallic ores, 

 we shall mention those of Werdermann, which made a certain 

 sensation in the United States. 



Werdermann, in the first instance, sent a very powerful 

 current into the furnaces when the ores were in fusion, or at 

 least at a red heat. Then, after some absolutely fruitless 

 experiments, he decided upon a more rational, if not more 

 industrial treatment. 



This treatment was as follows : 



The ores containing some precious metals associated with 

 sulphur, arsenic, antimony, or other analogous substances, were 



