710 THE APPLICATIONS OF PHYSICAL FORCES. [BOOK v. 



anode only gave an uneven deposit of insufficient thickness. M. 

 Lenoir proposed to employ an insoluble anode, made of platinum 

 wires twisted through all parts of the inside without touching it. 

 Crystals of sulphate of copper, enclosed in a gutta-percha pocket 

 pierced with holes, furnished the copper necessary for the renewal of 

 the solution, as the deposit thickened, but this was a costly method 



FIG. 457. Arrangement of the mould or electro- FIG. 458. A vase reproduced in electrotype, 



typing objects in the round. 



and only applicable to small objects. M. Plant^ replaced the platinum 

 by lead : a nucleus of lead pierced with holes is introduced into the 

 mould, roughly reproducing its form, only a little smaller, so as to 

 leave between the nucleus and the side a suitable interval. 



Fig. 457 shows how this nucleus of lead is arranged in one of the 

 halves of the mould which served for the electrotypic reproduction of 



