212 ELECTROLYSIS. 



in these works the baths were joined in parallel, it became 

 necessary to construct machines of a very low internal resist- 

 ance, so as to produce a great quantity of electricity with a 

 comparatively low electromotive force. 



The electromotive force increasing rapidly with the speed 

 of the machines, M. Gramme was led to think that it would 

 be possible to obtain much more considerable metallic deposits 

 than were usually obtained without a proportional expenditure 

 of motive power. 



In order to as much as possible prevent the phenomena of 

 polarisation, which would have modified the problem without 

 facilitating its solution, M. Gramme took the particularly 

 simple case of the electrolysis of sulphate of copper, using &s 

 anodes and cathodes copper plates of equal dimensions, and 

 proposed to demonstrate that one bath offering to the current 

 a given resistance and depositing a given weight of metal per 

 hour, could always be replaced by two baths of the same nature 

 having each half the resistance and depositing together twice 

 as much metal in the same time ; and this without any altera- 

 tion in the expenditure of motive power, or in the electric 

 current traversing the metallic solution. 



First Series of Experiments. The first experiments under- 

 taken by M. Gramme were conducted with a variable number 

 of baths all placed in parallel, that is to say, according to the 

 old method. They proved that with one or thirty-six baths 

 the deposition is the same with a constant intensity. This 

 was a confirmation of Faraday's law, industrially realised 

 with an excellent continuous-current dynamo-electric machine. 

 Each bath contained only one anode and one cathode, having 

 each 16 square decimetres of surface. The intensity of the 

 current was 6 '3 amperes. With one single bath the depo- 

 sition was found to be at the rate of 7 grammes per hour; 

 with twelve baths it was 7'1 grammes; and with thirty-six 

 baths, that is to say, with a surface of anodes equal to 6 

 square metres, it was 7 1 grammes (about 2 decigrammes per 

 bath). 



Second Series of Experiments. Table No. 1 gives the results 

 of experiments conducted on baths joined in a chain, like the 



