220 ELECTRO-METALLURGY 



printed from an almost unlimited number of times ; but they are better calculated 

 than those of copper to withstand those inevitable accidents constantly occurring in 

 printing establishments. Printers are sometimes obliged to set aside as useless their 

 best plates, which are often damaged by a grain of sand, or by a chance knot in the 

 paper. These accidents not only involve the expense of renewing the plates, but 

 sometimes occasion interruptions and delays in works of a very pressing nature. 

 These are some amongst the many advantages which may bo expected to accrue from 

 the introduction of iron electrotype.' 



ELECTRO-DEPOSITION OF NICKEL. ' It is only within the last few years that nickel- 

 plating has been brought prominently into notice but Mr. Smeo, in his " Elements 

 of Electro-metallurgy," published in 1852, has the following on the subject: 

 ' The nitrate and sulphate of nickel, the ammonio-nitrate, and sulphate of nickel, 

 the nickelo-cyanide of potassium, but especially the chloride of nickel, require con- 

 sideration. The nitrate is very soluble, but the metal has no groat inclination to 

 be precipitated, for the hydrogen appears rather to prefer being evolved than to reduce 

 the metal. The sulphate of nickel is also used as a double salt, and the metal is re- 

 duced more readily from it than from the nitrate. It is best reduced by the compound 

 battery process with a platinum positive pole, though a nickel positive pole may bo 

 employed. The solution of either nitrate or sulphate combined with alkalis, those of 

 ammonia deserving the preference, ought to be as strong as possible. The chloride 

 forms an excellent material for precipitation, by means of a nickel positive polo with 

 one or two batteries. The nickel so deposited has a peculiar white, brilliant lustre, 

 looking almost like glass. The deposit is so beautiful when removed from the negative 

 polo that it forms a great contrast to the common nickel metal, and no person would 

 ever suppose that there was any similarity of composition between that substance, 

 still less identity. For practical purposes the chloride is first, and next to it is the 

 sulphate for the reguline deposit." Several processes for nickel-plating have been 

 patented within the last four years, but it is difficult to see how the inventors can 

 claim any right to more than the exclusive use of some probably immaterial detail. 

 Napier coated articles with nickel in 1847 ; and although there have doubtless been 

 improvements in the various methods, it will be seen from the extract from Smoe 

 above quoted, that it is only some special detail of the process that can be claimed. 

 In one of the latest of those patents, taken out in the United States this year, tho in- 

 ventor claims a solution of either of the soluble salts of nickel, which must bo free 

 from potash, soda, lime, alumina, or nitric acid, the said solution to be perfectly 

 neutral. M. Becquerel, however, states that potash in no way affects the deposition 

 of the nickel, the double sulphate of nickel and potash being as useful as the double 

 sulphate of nickel and ammonia. The batteries in use for nickel-plating are, we 

 believe, principally the Smee and the Bunsen with their modifications, although the 

 Daniell and the Grove elements are also suitable ; but the chief requirement from the 

 battery is a uniform and unchanging current perfectly free from variation. Napier 

 says it is indispensable that the battery should be so arranged that tho quantity of 

 electricity generated should correspond with the extent of surface to be coated ; and 

 it appears to us that Napier is correct in this, but wo take from Dr. Feuchtwanger 

 the details of the apparatus employed in an extensive nickel-plating establish- 

 ment in the United States. The plating-trough consists of a large wooden box 



5 ft. 6 in. long, 2 ft. wide, and 14 in. deep, lined with asphaltum varnish. (Wo have 

 reason to believe that good dry oak is tho best wood of which to make tho troughs 

 used in electro-plating: other woods will answer, but oak is both cheapest and best 

 in the long run.) The capacity of this vat is about 70 gallons, tho liquid consisting 

 of hot water, to each gallon of which three quarters of a pound of the double sulphate 

 of nickel and ammonia is allowed. Tho battery consists of six zinc plates, 9x10 in., 

 well amalgamated, and six carbon plates of tho same dimensions. Tho box containing 

 theso is lined with lead, and holds ton gallons of water, to which 20 ozs. of sulphuric 

 acid are added. This battery is said to remain in active operation for two weeks, tho 

 zinc plates needing no re-amalgamation for four months. Tho articles to be plated 

 are suspended from copper and brass wires stretched across the vat, and require from 



6 to 10 hours' immersion. The battery is kept constantly at work ; as soon as one set 

 of articles is plated another replaces it. According to Dr. Feuchtwanger, the plating 

 solution must be kept neutral, litmus-paper being frequently used, and if acM is 

 present caustic ammonia must bo added till the li^uM is brought to tho normal state, 

 tho tendency being to wt<rk acid. It is also necessary, of course, to replace tho con- 

 sumed salts. If chloride of nickel and ammonia is used, tho proportions are four 

 ounces of the salt to a gallon of water. Dr. Feuchtwanger also de.M-rilies wh-it ho 

 terms "a simple nickel-plating apparatus ; " but his account is not so explicit . 



be deemed needful. However, the apparatus consists of a " bath or vat containing tho 

 usual nickel solution of double salt (the sulphate, wo presume), three quarters of a 



