( 155 ) 



CHAPTEll X. 



COPPERING. 



Intermediate Coppering Coppering of Zinc Coppering of Cast and Wrought 

 Iron Of the Importance of the Industry of Coppering on Cast Iron 

 Coppering of Cast-iron Rollers for Calico Printing Coppering of Telegraph 

 Wires Coppering of Non-metallic Bodies. 



INTERMEDIATE COPPERING. We have seen from the preceding 

 that it is often useful and sometimes necessary to copper 

 the objects which are to be nickeled, silvered, or gilt ; we do not 

 intend again to review the operations already described, but 

 will formulate a few general recommendations upon the subject 

 of intermediate coppering. In principle, this operation must 

 be carried out with the greatest care in all its parts in order 

 that the subjacent metals should entirely lose their special 

 character; small articles or those plated in chaplets must 

 be dipped in a hot bath so as to be rapidly coated with 

 a film of copper. We advise taking the objects out of the bath 

 as soon as they are coppered all over, to scrape them in 

 order to ascertain the adherence of the precipitate, to clean the 

 swollen parts and rub them with tartar, then to wash them and 

 put them back into the bath. 



The coppered piece must not, before receiving the coating 

 of gold, silver, or nickel, be dried, but washed in pure water and 

 taken to the galvanic bath after a snort passage in water and 

 the shortest possible one in air. Let us again call attention to 

 the fact that when silvering or gilding, the coppering must be 

 followed by a slight amalgamation, which is not required in the 

 nickeling process. 



COPPERING OF ZINC. The industry of zinc works of art, 

 which was a few years ago a flourishing one in France, is 



