NICKEL-PLATING. 117 



the other hand, complicate his electric installation, so that no 

 final advantage would result. But this is not the case with the 

 nickel-plater, whose trade is to deposit metal on pieces manu- 

 factured and sold elsewhere, and whose means of action and 

 experienced staff allow him to avail himself of all the progress 

 which science or practice place in his way. 



To him there is no small economy on operations effected on 

 a large scale and frequently renewed : the motive power 

 economised is represented by a saving in fuel, economy in 

 labour by a reduced staff, &c. It is particularly with regard 

 to the latter manufacturer that we will examine the question 

 of the anodes,* advising the former manufacturer to use nickel 

 anodes exclusively. 



Soluble and insoluble anodes can be used in nickel-plating. 



The soluble anodes must be of chemically pure nickel, in 

 rolled bars preferably to cast bars, as the rolling makes uniform 

 the porosity of the metal and regulates its dissolution in the 

 bath. 



Kolled bars are not quite so good conductors of electricity, 

 but their surface being always large, this little discrepancy has 

 no sensible influence on the consumption of current. 



The insoluble anodes may be of platinum or carbon. When 

 made of platinum, they are everlasting but very expensive ; 

 made of carbon, they are cheap but readily get disaggregated, 

 which causes disturbances in the baths, and they have to be 

 replaced from time to time. 



The foregoing are, speaking in a general manner, the con- 

 stitutional qualities of nickel, platinum, and carbon anodes ; we 

 will now examine their chemical behaviour and the influence 

 which they exert on the electric current and the nickel bath. 



It is primd facie clear that the deposition of nickel will take 

 place on all the pieces placed in the bath with either nickel or 

 insoluble anodes ; but in the first case the anodes will, as fast 

 as the pieces get coated with the metal, combine with the 

 electrolytic solution, restoring to it the nickel which it 

 liberates, whereas in the second case the bath will grow weaker 

 in metal, since the nickel carried by the electrolysis from the 

 * See M. Pfanhauser's work on the same subject, Vienna, 1883. 



