COPPERING. 167 



The wire, which is wound on large drums, slowly passes 

 through a series of baths, until it is coated with a sufficient 

 thickness of copper. The duration of each operation is of about 

 sixty hours. Sixteen kilometres of steel wire are covered in a 

 day, the weight of the copper required being 250 kilogrammes. 

 The total daily production of this immense factory may reach 

 50 kilometres. 



COPPERING OP NON-METALLIC BODIES. Hockin recom- 

 mends, for coppering non-metallic bodies, dipping them into 

 iodined collodion, afterwards immersing them in a solution of 

 argentic nitrate and exposing them for a few seconds to the 

 light ; then into a bath of ferric protosulphate acidulated with 

 nitric acid, and finally to deposit the copper on these bodies by 

 means of an almost neutral solution of cupric sulphate. 



