And£rson. — Electrical Deposition of Nickel. 509 



Resume. 



The main results of this investigation may be summarized thus : — 



1. In the electrical deposition of nickel from ammoniacal solution the 

 efficiency is remarkably low. This may possibly be due to polarization 

 effects. The nickel is perhaps present as Ni(NH 3 ) r ions and a small pro- 

 portion as Ni. Oxidation appears to take place at the anode with the 

 formation of Ni(OH) 3 , for on removal of the anode it was often found to 

 be practically coated with a black deposit, presumably of nickel hydroxide, 

 On being allowed to stand in the solution it dissolved, forming Ni(NH 3 ),. 

 Periodic phenomena are also to be observed at the anode. 



2. In the presence of ammonium nitrate the rate of deposition is greatly 

 diminished. The electrical energy appears to be utilized primarily in the 

 reduction of the nitrate, and only when that has reached an advanced stage 

 does deposition of the metal appear to take place in any quantity. 



3. Periodic phenomena are observable at the cathode ; and if the P.D. 

 cathode solution is studied a sudden rise in the P.D. seems to be a safe 

 criterion that electrical separation of the metal has begun. 



4. The reduction of the nitrate appears to be first to hydroxylamine 

 and finally to ammonia. The hydroxylamine undergoes some subsequent 

 change, and nitrous acid does not seem to be formed. 



5. Even in the presence of nitrate the use of the divided cell yielded 

 distinctly better results. The deposit of metal was much more even than 

 when the undivided cell was used. The writer hopes at a future date to 

 investigate more fully the application of the divided cell to the separation 

 of nickel ; and the results thus far obtained seem to justify the possibility 

 that conditions may be devised under which the deposition of the metal 

 may be a commercial success. 



Art. XL VII. — Notes on an Artesian Trial Bore, Westshore, Napier. 



By P. W. Holmes, M.Inst.C.E., Engineer-in-Chief, Public Works 



Department. 



[Read before the Wellington Philosophical Society, 19th July, 1916 ; received by Edita», 

 30th December, 1916 ; issued separately, 10th December, 1917.] 



The construction of the railway northward from Napier requires the 

 building of a long bridge across a part of the Inner Harbour, while the 

 proposed extension of the Inner Harbour works necessitates the removal 

 of the present road bridge ; and, as decay has rendered it unsafe, it has 

 been decided to erect a combined road and railway bridge, and to build 

 the structure of reinforced concrete. The length of the bridge is 1,232 ft. ; 

 the width, 41 ft. 



In the mixing of the concrete a large quantity of fresh water is neces- 

 sary, salt or brackish water not being permissible where concrete has to be 

 reinforced with iron or steel. A large quantity of fresh water will also be 

 required to supply the boilers of the machines used in the construction of 

 the bridge, and of the locomotives which will be working on the construc- 

 tion of the line as far as the River Esk, the first source of supply after 

 leaving Napier. 



