168 ELECTROLYSIS. 



CHAPTER XI. 



ELECTED PLATING AND ELECTBOTYPING. 



Object of Electroplating Simple Bath Moulds in Plastic Material Massive 

 . Electroplating Statuary or Relievo Electroplating Qualities of Electro- 

 plating Copper Electroty ping Moulds Baths Modus Operand! Dura- 

 tion of the Operation Finishing of the Electrotypes Mounting Steel- 

 coated Electrotypes. 



1. ELECTROPLATING. 



OBJECT OF ELECTROPLATING. The invention of electroplating 

 dates from 1839, and has been claimed by Jacobi, Jourdan, 

 and Spencer. Jacobi, who also conceived the soluble anode, 

 having established his priority by the publication of his pro- 

 cesses, is generally considered as the veritable inventor. 



The sole object of Jacobi and his colleagues was the re- 

 production of medals and works of art by depositing on their 

 surface a non-adhering metal which could be used as a negative 

 mould. The operation was effected in a simple bath, and many 

 manufacturers are actually working by the simple bath process. 



SIMPLE BATH. This apparatus is composed, in principle, 

 of a wooden vat lined internally with lead or gutta-percha, and 

 containing a solution of cupric sulphate. 



This vat (Fig. 27) contains some linen bags filled with 

 crystals of sulphate, for the purpose of maintaining the liquor 

 in a state of uniform saturation during the whole time of the 

 operation. In the middle are placed a certain number of 

 porous cells, generally made of unchilled porcelain, and contain- 

 ing dilute sulphuric acid and a zinc plate. All the zinc plates 

 Z Z Z are connected together by means of a copper rod T T, 

 the latter being itself connected with one or more smaller copper 

 rods, from which are suspended the pieces to be reproduced. 



