ELECTROLYSIS. 



the wire and the relative speed of the two organs, the effects 

 would become more powerful. This is indeed what experience 

 first, and then theory, completely demonstrated. Instead of a 

 magnet, an electro-magnet excited by an external source, or 

 more frequently by the machine itself, is generally used. 



The magnet or electro-magnet which influences the con- 

 ducting wire is called inductor, and the portion of the conductor 

 which moves in the magnetic field is called induced. 



The first machine constructed with a view of realising 

 Faraday's conception, generated currents alternately positive 

 and negative which had to be redressed by means of special 

 devices called commutators before they could be used for 

 electroplating purposes. These commutators wore out rapidly, 

 and gave rise to large sparks, so that these primitive machines 

 did not offer sufficient advantages over batteries to supersede 

 the latter. In reality they met with no success, and were 

 employed on a very limited scale only. 



M. Zenobe Gramme produced the first practical continuous- 

 current machine. His works revolutionised the old electrical 

 industries, and gave rise to some new ones. It is therefore 

 only just to begin our review of the various machines used in 

 electrolysis with that of this celebrated inventor. 



GRAMME MACHINE. The 



FlG - 10 - Gramme machine is composed 



of an iron wire ring on which 

 are wound copper wires, and of 

 a cylinder made of a series of 

 blades or segments attached 

 to the said copper wires; the 

 whole mounted on a spindle 

 and revolving inside any given 

 magnetic field. 



The iron wire ring is known 

 as the Gramme ring. 



The copper wire wound 

 round the ring is called the 

 induced wire. 

 The cylinder ol blades is called the collector. 



Ordinary Gramme Bobbin. 



