Mr. Smee on the production of Electrotypes. 531 



down at the platina or hydrogen end upon the medal or mould 

 placed for its reception. 



The mode which I adopt is, first to obtain a long dish or trough, 

 and then to place a wire in the inside along its bottom, which is 

 connected to the zinc of one of the cells of my battery along the 

 opposite side of the vessel; a large piece of copper is placed in con- 

 nexion with the silver of the battery, and a solution of sulphate of 

 copper is then added. By this ai-rangement the current is generated 

 at the zinc, passes to the medal, reduces the copper whilst the oxy- 

 gen and acid are transferred to the refuse copper, and dissolves a 

 corresponding quantity of copper, and by this means the solution 

 is always kept saturated with the metal. 



When medals are to be copied, they are singly placed in contact 

 with the wire in connexion with the zinc of the battery, and in this 

 way many may be done in the same vessel, and any may be taken 

 out and examined without the slightest interruption to the others. 

 The rapidity of the j^rocess may be increased without detriment by 

 the use of two to six or even more cells of the battery, as the 

 -copper will still be extremely tough. It will be found that my 

 battery will require not the slightest alteration, except once a day, 

 when the liquid should be changed. I have tried other solutions 

 of copper, such as the nitrate ; but although the process is hastened, 

 the metal is apt to be brittle, or to have other imperfections. 



When engraved plates are to be copied, the first copy is in basso re- 

 lievo, and therefore a second is required to be made which is in " inta- 

 glio," and then ready for printing. Copies may even be taken of non- 

 conducting substances, as wood-cuts, &c., by brushing them over 

 with black-lead, taking care that the copper wire is in good contact 

 with the plumbago. 



The great advantages of this mode of proceeding above all others 

 are, first, the quality of the copper is far better than when reduced 

 in the usual way as described by Messrs, Spencer and Solly ; this 

 advantage is owing to the use of the copper at the oxygen end as 

 suggested by Mr. Mason ; secondly, all the plates or medals, for 

 there is no limit to the number, are in the same vessel ; thirdly, the pro- 

 cess may be hurried or retarded, accordingly as the number of plates 

 of the battery are increased or diminished ; fourthly, the plates 

 wiU not require to be interfered with till the precipitation is com- 

 pletely finished ; and there are many other more trifling advantages 

 which it would be tedious to enumerate. 



The mode of proceeding here detailed differs but little from 

 others which have been described ; but these trifling diff'erences are 

 so important in practice, that this mode will probably supersede 

 «very other. In fact, I have had the pleasure of seeing many most 

 valuable copper-plates subjected to this process, and the specimen 

 which accompanies this paper is I believe the first which has ever 

 undergone the ordeal of having the large number of impressions, 

 require d for any publication, printed from it. Of course it is a perfect 

 facsimile, and therefore this method would be of the greatest im- 

 portance.to bankers for their notes, and is far superior to Mr. Perkins's 

 process for the multiplication of plates, because in that case they 



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