506 Transactions . 



Discussion. 



From the results obtained it was evident that the electrical energy was 

 utilized in effecting some reaction other than the separation of the metal 

 from the solution. Accordingly a series of experiments was undertaken 

 in order to ascertain the way in which the energy was used up. 



Now, on comparing the sets of values showing the variation in the P.D. 

 at the cathode and the rate of deposition of the metal, it will be noticed 

 that a sudden rise in P.D. appears to occur when the metal is beginning 

 to be separated in quantity. This was investigated, and from a number 

 of experiments this rise in P.D. appeared to be an infallible criterion that 

 deposition had commenced. Furthermore, during the course of the deposi- 

 tion subsequent to this sudden rise in the P.D. at the cathode the values 

 for the latter exhibited a gradual diminution, as was previously observed 

 in the absence of nitrate. 



Series 3. 



The preceding series of experiments was repeated, using a greater 

 current-density, but similar results were obtained. 



Series 4. 



The most probable manner in which the energy would be utilized would 

 be in effecting the reduction of the ammonium nitrate. This reduction 

 may lead to a variety of products, according to the extent to which the 

 reduction has taken place — e.g., nitrous acid, hydroxylamine, or ammonia 

 may result. 



In the case where one equivalent amount of ammonium nitrate 

 (0-85 grin.) was added, the amounts of hydrogen necessary to effect the 

 reduction to the three stages were calculated from Faraday's law to be 

 0-0212 grm., 0-0637 grm., and 0-0849 grm. respectively. 



The amounts of hydrogen liberated during the electrolysis, deducting 

 the equivalent of the amount of nickel deposited, were calculated to be — 

 At end of one hour, 0-037 grm. ; at end of 'two hours, 0-075 grm. ; at end 

 of three hours, 0-1045 grm. ; at end of four hours, 0-1398 grm. 



This series of experiments, then, was performed in the hope of 

 isolating hydroxylamine, which one might reasonably expect to be one of 

 the products of the reduction. 



Estimation of Hydroxylamine. 



At the end of a definite interval of time the electrolysis was inter- 

 rupted and the solution evaporated to dryness. From the mixture of 

 salts so obtained the hydroxylamine was exti acted by trituration with 

 absolute alcohol ; on evaporation of the latter the salt crystallized 

 out. The hydroxylamine so obtained was dissolved in carefully dis- 

 tilled water, and estimated in the usual May by the reduction of boiling 

 Fehling's solution,* which proceeds according to the following equation : 

 2NH 2 OH + 4CuO = 2Cu 2 + N 2 + 3H 2 0. The cuprous oxide was 

 filtered through a Gooch crucible, dried carefully, and weighed, and hence 

 the corresponding amount of hydroxylamine could be readily computed. 



*H. O. Jones and F. W. Carpenter, The Estimation of Hydroxlyamme, Jovrn. 

 Chem. Soc, vol. 83, 1903, pp. 1394-1400. 



