222 ELECTRO-METALLURGY 



discover, thoso two solutions are inherently incapable of giving a coherent, tenacious, 

 flexible metal, such as is required in the arts of electrotyping and elcctro-plati;: 

 the other two solutions named, the inventor believes that, before liis improvements, 

 the best results wore obtained from the double chloride of nickel and ammonium, but 

 the metal deposited from it is of such a character as to bo worthless when deposited 

 to any appreciable thickness. It is accompanied with the deposit of peroxide, and is 

 therefore brown or black. It is extremely liable to split up into thin scales, which 

 may be rubbed off even with the hand. This want of coherence and tenacity unfits it 

 for the requirements of the arts. The metal deposited from the double sulphate of nickel 

 and ammonia is substantially the same as the above, but it is not BO easily obtained. 

 If, with these solutions, a battery-power is used of an intensity of two Grove colls, or 

 thereabouts, a white deposit may bo obtained of considerable thickness, but still with 

 such a tendency to split up in scales that it is practically useless, and neither solution 

 gives the full equivalent due to the current. 



' It has been discovered, however, that the difficulties attending the use of t lie-so 

 last-named solutions, and the character of their deposits, are not inherent in the nature 

 of the solutions, but are due to the modes of preparing them, or to the presence in 

 minute quantities of certain substances which are generally employed in making them, 

 or in the reduction of the nickel used in making them. In order, "therefore, to pivpaiv. 

 these solutions in such a manner as to give the results reached, it is necessary to adopt 

 processes in their preparation and observe precautions which shall either dispense 

 with the use of these substances altogether or shall effectually remove them if they 

 are employed.' 



The patentee then proceeds to give the following directions : ' In preparing this 

 solution, I prefer the use of pure nickel ; but commercial nickel may be used. Com- 

 mercial nickel almost always contains more or less of the re-agents employed in the puri- 

 fication or manufacture of the metal, such as sulphate of lime, sulphide of calcium, 

 sulphide of sodium or potassium, chloride of sodium, and alumina. When any of 

 these substances are present it is necessary to remove them ; this can be done by 

 melting the nickel, or by boiling it in water containing at least 1 per cent, of hydro- 

 chloric acid. The boilings must be repeated with fresh acid and water until the waste- 

 waters give no indication of the presence of lime when treated with oxalate of 

 ammonia. When the metal is purified by melting, the foreign substances collect on 

 the top of the melted metal in the form of a slag, which can be removed mechanically. 

 If the nickel contains zinc it should be melted, in order to volatilise the zinc and drive 

 it off. The crucible in such case must not be closed so tightly as to prevent the 

 escape of the zinc fumes. If copper, arsenic, or antimony is present in the nickel it 

 can be removed after the nickel is dissolved by passing sulphuretted hydrogen 

 through the solution. The acid to be used in dissolving the metal consists of one 

 part strong nitric acid, six parts muriatic acid, and one part water. Nitric acid or 

 muriatic acid may bo used separately, but the above mixture is preferred. A 

 quantity of this acid is taken, sufficient to dissolve any given amount of the metal, 

 with as little excess of the former as possible ; a gentle heat is all that is required. 

 The resulting solution is then filtered, and to prepare the solution of the double 

 sulphate of nickel and ammonia, a quantity of strong sulphuric acid, sufficient to 

 convert all the metal into sulphate, is added, and the solution is then evaporated to 

 drym-ss. The mass is then again dissolved in water, and a much smaller quantity 

 than before of sulphuric acid is added, and the whole again evaporated to dryings, 

 the temperature being raised finally to a point not to exceed 650 Fahr. This tempe- 

 rature is to be sustained until no more vapours of sulphuric acid can bo detected. The 

 resulting sulphate of nickel is pulverised and thoroughly mixed with about gjjth of its 

 weight of carbonate of ammonia, and the mass again subjected to a gradually- 

 increasing temperature, not to exceed 650 Fahr. until the carbonate of ammonia is 

 entirely volatilised. If any iron is present, the most of it will be converted into an 

 insoluble salt, which may be removed by filtration. The resulting dry and neutral 

 sulphate of nickel is then dissolved in water by boiling, and if any insoluble residue 

 remains, the solution is filtered. From the weight of the nickel used before solution, 

 the amount of sulphuric acid in the dry sulphate can bo calculated. This amount of 

 sulphuric acid is weighed out, diluted with four times its weight of water, and 

 saturated with pure ammonia or carbonate of ammonia ; the former is preferred. 

 This solution, if it is at all alkaline, should be evaporated until it becomes neutral, 

 t-i test-paper. The sulphate of ammonia of commerce may likewise l>r used, but pure 

 sulphate of ammonia is to be preferred. The two solutions of the sulphate of nickel 

 and sulphate of ammonia are then united and diluted with siillicii-nt water to have 

 J .', ./.. t 2oz.s. of nickel to each gallon of si, hit ion, and the, solution is ready for use. 



"'In preparing the solution of the double chlorid* of nickel and ammonium, the 

 nickel is to be purified and dissolved in the same manner as is described for tho 



