SOLID SILVER ARTICLES MADE BY THE BATTERY. 123 



sarily be full of minute interstices between the crystals : hence 

 when a metal, such as copper, is plated, it is liable to be acted upon by 

 the atmosphere, or injured by whatever is brought into contact with it. 



This objection was not without foundation, as all deposited metals 

 are crystalline in texture, but they do not necessarily leave inter- 

 stices : the objection, however, is almost entirely removed by keeping 

 the articles in motion during the deposition : by motion and proper 

 arrangement of battery we have deposited silver of as high specific 

 gravity as hammered silver, which could not be the case if it were 

 porous. 



2d objection : As only pure silver is deposited, it must necessarily 

 be soft, and consequently liable to abrasion, and more rapid wear. 



This objection is also partly true. Only pure silver can be depo- 

 sited ; but it is not necessarily soft : the quality of the deposit, in 

 this respect, depends (as already noticed) a great deal upon the 

 nature of the solution and the battery power. Intensity of battery 

 gives hardness to the metal deposited. There is no complaint more 

 common amongst the burnishers of electro-plated articles, than that 

 the metal is hard ; and it is far from being an uncommon occurrence, 

 that some goods have to be heated so that they may be more 

 easily burnished or polished. How far this annealing may affect the 

 wear of the goods is not yet ascertained. That the silver is pure we 

 think an advantage, hence the superior colour which electro-plated 

 goods possess : besides which, purchasers are not subject to the risk 

 of having a plate much alloyed. 



3d objection : The mounts or prominences of articles, which must 

 have the greatest wear, have the least and thinnest deposit. 



This objection is entirely without foundation, as the prominences 

 have always the greatest portion of deposit, and the hollow parts 

 the least. 



Solid Silver Articles made by the Battery. Silver may be deposited 



from its cyanide solution upon wax moulds polished with black-lead, 

 almost as easily as copper ; but for this purpose it is better to have 

 the solution much stronger in silver than for plating. We have 

 found that 8 ounces of silver to the gallon of solution make a very 

 good strength. Nevertheless, no articles are made in silver by de- 

 positing upon wax in this manner. Strong solutions of cyanide of 

 potassium and silver act upon wax, and would soon destroy a mould. 

 The method of making articles in solid silver by the electro-process 

 has been already explained (page 54), namely, a copper mould is 

 made by the electrotype, and the silver is deposited within this 

 mould to the proper thickness ; after which it is kept in a hot solu- 

 tion of crocus and muriatic acid, or boiled in dilute hydro-chloric 

 acid, which dissolves the copper without injuring the silver. 



The method which we esteem as best for dissolving off the copper 



