136 DEPOSITION OF NICKEL, IRON, LEAD, TIN. 



Coating with Palladium. Palladium is a metal very easily depo- 

 sited. The solution is prepared by dissolving the metal in nitro- 

 muriatic acid, and evaporating the solution nearly to dryness ; then 

 adding cyanide of potassium till the whole is dissolved : the solution 

 is then filtered and ready for use. The cyanide of potassium holds 

 a large quantity of this metal in solution, and the electrode is acted 

 upon while the deposit is proceeding. Articles covered with this 

 metal assume the appearance of the metal ; but, so far as we are 

 aware, it has not yet been applied to any practical purpose. It 

 requires rather a thick deposit to protect metals from the action of 

 acids, which is, probably, the only use it can be applied to. 



Coating with Nickel. Nickel is very easily deposited ; and may 

 be prepared for this purpose by dissolving it in nitric acid, then add- 

 ing cyanide of potassium to precipitate the metal ; after which the 

 precipitate is washed and dissolved by the addition of more cyanide 

 of potassium. Or the nitrate solution may be precipitated by car- 

 bonate of potash ; this should be well washed, and then dissolved in 

 cyanide of potassium ; a proportion of carbonate of potash will be 

 in the solution, which we have not found to be detrimental. This 

 latter method of preparing the nickel plating solution is simple, and, 

 therefore, has our recommendation. The metal is very easily depo- 

 sited ; it yields a colour approaching to silver, which is not liable to 

 tarnish on exposure to the air. A coating of this metal would be 

 very useful for covering common work, such as gasaliers, and other 

 gas-fittings, and even common plate. The great difficulty expe- 

 rienced is to obtain a positive electrode : the metal is very difficult 

 to fuse, and so brittle that we have never been able to obtain 

 either a plate or a sheet of it. Could this difficulty be easily over- 

 come, the application of nickel to the coating of other metals would 

 be extensive, and the property of not being liable to tarnish would 

 make it eminently useful for all general purposes. We coated 

 articles with nickel seven years since, and, though they have been 

 exposed to the air from that period to the present, they still retain 

 their brilliancy, and continue untarnished. 



Antimony, Arsenic, Tin, Iron, Lead, Bismuth, and Cadmium. We 



have deposited these metals from their solutions in cyanide of 

 potassium ; but not for any useful application. 



iron. Iron may be very easily deposited from its sulphate : dis- 

 solve a little crystalline sulphate of iron in water, and add a few 

 drops of sulphuric acid to the solution : one pair of Smee's battery 

 may be used to deposit the iron upon copper or brass. The metal 

 in this pure state has a very bright and beautiful silver colour. 



L.ead. Lead may be deposited from an acid solution, such as the 

 acetate, but requires some management of strength of battery: it 

 may also be deposited from its solution in potash of soda. 



