78 



ELECTROLYSIS. 



The bobbin is constituted by a cylinder of iron wires, round 

 which is wound the induced copper wire. It differs from the 

 Gramme machine in this respect, that no portion of the wire is 

 inside the iron core. The induced wire is divided into sec- 

 tions which are attached to a commutator identical with that of 

 Gramme. 



The current is collected by means of Gramme brushes 

 pressing on the collectors, or by means of copper ribbons pressed 

 in position by flat springs. 



FIG. 14. 



Siemens Machine. 



Messrs. Siemens have manufactured a great number of 

 types of Hefner Alteneck machines, and notwithstanding that 

 they have found their principal market in the applications of 

 electric lighting, they have not overlooked the problems 

 relating to electro-metallurgy. 



In the chapter treating of the refining of metals, we shall 

 have an opportunity of describing the large machine in use at 

 the refining works of Oker. We should have liked to give in 

 this place a table of the machines usually employed in electro- 



