“A STUDY OF THE ELECTROLYTIC 
 PREPARATION OF HYDROXYLA- 
 MINE HYDROCHLORIDE AND 
 HYDROXYLAMINE SULPHATE” 
 
 BY 
 
 FULLER FRANCIS ROSS 
 
 THESIS 
 
 FOR THE 
 
 DEG REE OF BACHELOR OF SCIENCE 
 
 IN 
 
 CHEMICAL ENGINEERING 
 
 COLLEGE OF LIBERAL ARTS AND SCIENCES 
 
 UNIVERSITY OF ILLINOIS 
 
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Acknowledgment 
 
 The writer desires to express his 
 gratitude to Dr, J. H. Beedy, who has 
 aided in this v/ork hy his very helpful 
 suggSstions, 
 
Index to Contents 
 
 Page 
 
 I. Introduction* 1 
 
 II, Historical 2 
 
 III, Purpose of the problem 7 
 
 IV. Experimental 8 
 
 V. Conclusion 17 
 
 VI, Bibliography 16 
 
A STUDY 0? THE ELECTROLYTIC PREPARATION OP 
 HYSROXYLAI.TIME HYDROCHLORIDE MB HYDROXYLAl^IITE 
 
 SULPHilTE 
 
 Intro Auction 
 
 Electrical methods in reduction and oxidation have the 
 decided advantage over strictly chemical methods in that they are 
 more readily controlled "by adjustment of the potential. Further- 
 more, the products are purer, since there are no reduction or 
 oxidation "by-products to "be removed, Verj'- probably, it is the 
 element of cost, which limits more extensive use of electrolytic 
 methods. 
 
 Numerous methods have been suggested for the preparation 
 of hydroxiy’-lamine , some impracticable, others with varying merits. 
 Reduction of nitrites, nitrates, nitric acid and nitric oxide to 
 Kydroxylam.ine have been discussed in some dsta>il by some authors. 
 
 In every case, the methods are more or less unsatisfactory because 
 of small yields. Besson ^ in 1911 claimed he had obtained the 
 compound by the action of a silent dischiarge upon moist ammonia and 
 similarly in 1909, Ezio Comanducii'^ investigated the effect of an 
 electric discliarge upon a mixture of ammonia and 03^gen, with 
 production of Hydro xylamine. Neither of these methods have been 
 given much attention, but they go to illustrate an extended use 
 of electrical methods in organic preparations, 
 
 A great many authors ascribe the difficulty of preparation 
 
 of the amine to the formation of by-products as aresult of the 
 
According to Raschig*^ (1890-) the hydrochloride of 
 Hydroxj'l amine is obtained as follows: A saturated solution of 
 
 sodium nitrite (l mol. ) is added to a solution of hydrogen sodium 
 sulphite (2 mols. ) in a cooled vessel, and then a cold saturated 
 solution of potassiumi chloride is added. After 24 hours the 
 Hydroxylamine disulphonate separates. This salt is boiled in water 
 several hours. After cooling the Ifydroxylamine sulphate separates 
 out and is converted into the hydrochloride form with bariim 
 chloride* 
 
 The same authors, Divers and Haga^, 9 years later (1896) 
 claimed that Sodium nitrite in the presence of Sodium carbonate 
 could be reduced to the amine by use of Sulphur dioxide gas if a 
 temperature of 2-3 degrees centigrade below zero was maintained, at 
 which temperature hydro xj^l amine will not be deccmiposed by the 
 sulphur dioxide present. The solution of oximidosulphonate is 
 hydrolyzed to NH 2 OH by a few drops of H 2 SO 4 after two days maintain- 
 ing a temperature of 80-85°, Besides these, C, F. Boehringer and 
 
 p 
 
 Sdhne° and F, B, Ahrens have attemipted to carry out efficient 
 electrolytic methods for the preparation of the salts of Bydroxy- 
 lam.ine, 
 
 Ahrens^ (1903) reduced 50 percent llitric acid in a 50^ 
 Sulphuric acid solution using a cooled lead cylinder for an anode 
 and for the cathode an amalgamated lead cup, cooled by a mixture of 
 salt and ice. He passed a current of 24 amperes for tv;o hours and 
 forty minutes after which time the Hydroxy lamiine sulplia.te formed, 
 was removed from, the ca.thode cup and the sulphate precipitated out 
 with barium chloride. The converted Hydro xj'-l amine hydrochloride 
 Vt’as then filtered from the bariumi sulphate and evaporated to 
 
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 dryness under diminished pressure* The salt was purified from the 
 ammonium chloride hy several crystallizations from hot water equal 
 to 1/2 of its weight. Ahrens claimed a yield of 80^ of the Nitric 
 acid used. His v/ork carried out with a zinc cathode shov^ed a yield 
 of a 15-25^ solution of Hydroxj’’lamine salt using a solution of 
 nitric acid, 2 amperes current and maintaining a temperature of 0 
 
 degrees centigrade. 
 
 "5 4 
 
 Tafel' * , a.hout the same time, employed practically the 
 same method as Ahrens, claiming a 75-80^ yield of Hydroxylamine 
 hydrochloride, based on the Nitric acid used. One precaution out- 
 lined was that in the addition of the barium chloride solution to 
 the Hydroxylamine sulphate solution care should be taken to retain 
 a temperature of 30 -40 degrees centigra.de. The same procedure was 
 carried out for filtration and crystallization of the hydrochloride 
 as was outlined above, in Ahrens* work. 
 
 Otto Flaschner ^^(1907} studied the electro -reduction of 
 Hydroxylamine and of nitric acid using various cathode materials 
 v;ith rather varied results. He em.phasized the fact that different 
 metals as cathodes gave different potentials and in each case the 
 extent of reduction differed. A high potential seemed conducive 
 to the production of Hydroxylam.ine while the low potential resulted 
 in the usual formation of a large quantity of ammonia. 
 
 The latest work of any im.portance has been done by 
 E. P. Schoch'' and P.. H. Pritchett (1916), The3? developed a method 
 for preparation of the Hydroijqylamine hydrochloride directly v/ithout 
 the intermediate barium chloride precipitation. They developed a 
 method using an am.algamated lead cathode and a porous cell enclosing 
 a lead rod for an anode. Fifty percent hydrochloric acid was 
 
placed in the cathode compartment and fifty percent sulphuric acid 
 in the anode chamber. By the addition of small quantities of fifty 
 percent nitric acid to the cathode compartment, the investigators 
 were able to obtain the Hydro:^’lamine hydrochloride directly. A 
 vacuum distillation to dryness and a recrystallization with 
 absolute alcohol gives an 80^ yield, the 20^ loss being attributed 
 to the evolution of arrmonia or the formation of ammonium compounds. 
 There was a certain amount of ammonium chloride in the crj^stallized 
 hydrochloride. Impest igat ion showed; Ethyl alcohol at 15® C. 
 dissolves 44.3 grams. Hydro :^ylam,ine hydrochloride. Alcohol at the 
 same temperature dissolves 6.2 grair.s ammonia chloride. In this 
 work a current of 50 amperes ws.s passed through the cell for three 
 hours. The temperature was maintained at 15 degrees or less. 
 
 Various m.echanical ideas were brought into use such as a vacuum 
 cylinder arranged to keep the cathode solution circulating through 
 a cooling mixture. According to more recent information, it has 
 been found that this method has not been nearly as successful as 
 originally described. An attempted duplication of the work by the 
 authors themselves has resulted in very low yields, 
 
 M. A, Beeson published his work on the study of an 
 electric discharge on wet and on dry ammonia gas. He found that the 
 effect of an electric discharge on dry ammonia resulted in the 
 partial formation of nitrogen and hydrogen. The ammonia gas is 
 dried by passing through a long column of fused potassium hydroxide 
 then refrigerated and subjected to the discharge, thus yielding the 
 products mentioned above. He found that the electrical discharge 
 did not react in a similar manner in the presence of moist 
 ammonia, but decomposed into Hydro xjriamine and hydrogen according 
 
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- 6 - 
 
 to the following reaction: NH 3 + H 2 O = Ha+ ITHaOH 
 
 Besson confirmed the presence of Hydro :xylarnine by reducing a copper 
 sulphate solution. 
 
 So far, we have discussed the various important methods of 
 electrolytic preparation of Hydroxy lamine salts and have only men- 
 tioned other methods that are related to the problem. Since this 
 present work makes use of an Illium cathode, a short discussion of 
 the alloy seems apropos. 
 
 Illium is an acid-resisting alloy invented by Professor 
 S, W, Parr^^ of this University. It has several compos- 
 itions but possessing an important property in each case-it*s 
 resistance to corrosion by acids such as sulphuric and nitric acids. 
 It is given the general formula; 
 
 SO.Sbfo nickel 
 21,07 Chromium 
 2.13 Tungsten 
 1,09 Aluminium 
 ,98 Manganese 
 6.42 Copper 
 ,76 Iron 
 4 . 67 Mo lyb den urn 
 1.04 Silicon 
 
 It possesses a high electrical resistance. Very little detail has 
 been printed upon the various properties of Illium. Assuiaing that 
 the alloy possessed the property of electrical conductance, it was 
 thought possible to utilize it as an electrode in the ordinary type 
 of electrolytic reduction reactions. 
 
 According to Allmand , the effect of the cathode material 
 on the course of reduction is two -fold, 
 
 1, Different cathodes catalyse the reaction in such a 
 manner that reduction can take place with a far less negative cathode 
 potential at some cathodes than at others. 
 
-7- 
 
 2. At the same cathode potential, the current density 
 
 can vary, 
 
 A change in the surface area of the cathode would change the current 
 density and possibly give a more desirable potential for reduction. 
 
 In other words, when the surface area of the electrode is 
 altered, the strength of the current remaining the same, the number 
 of ions discharged at unit surface varies in direct proportion. 
 Therefore, by selecting a suitable electrode, it is possible to cause 
 the concentration of the ions to vary within wide limits, 
 
 III 
 
 Purpose of the Problem 
 
 Some authors have stated that Hydroxylamine was prepared 
 when the temperature \vas 30-40degrees centigrade (Tafel'^), 
 
 Schoch and Pritchett kept the temperature about 15 degrees or less. 
 It was thought desirable to obtain some a.dditional information, then, 
 about temperature regulation in this preparation. 
 
 Since Illium has never been used for electrolytic work an 
 investigation of its availability for this purpose suggested itself. 
 By-products, or further reduction products of Hydroxj-'l- 
 araine such as ammonia and ammonium salts, keeps the maximum yield 
 of the amine at 80^. If this process could be perfected so as to 
 prevent any further reduction than Hydroxylamine, the yield could be 
 appreciably increased. 
 
 Reduction of nitric acid is the usual practice. It would 
 be interesting therefore to study its electrolytic reduction in some- 
 what the same manner as before and also to study the reduction of 
 nitrites which is already one stage closer to the formation of the 
 
M0M 
 
 amine than nitrates. 
 
 IV 
 
 Experimental 
 
 GEITERAL liCETIIOB 
 
 Solutions 
 
 Anode (Porous cell)- 40 cc bO% H2SO4 
 Cathode (outer glass cell)- lOOcc bO% H2SO4 
 Cathode (outer glass cell)- 15cc bO% HNO3 
 
 Diagram and setting- next page. 
 
 Procedure 
 
 The general method of reduction of nitric acid in the 
 presence of sulphuric acid was attempted in which the desired 
 product should he Hydroxylamine sulphate. Twenty amperes current 
 was passed through the Cell for 1 1/4 hours. A lead tube 3/8 inches 
 in diameter and 2 feet long was coiled into a spiral so that it just 
 fit into the anode chamber, a porous cup 1 1/2 inch in diameter and 
 3 inches high. Water was passed through the tube, the temperature 
 being 18® Centigrade, Around the cathode compartment, a m.ixture of 
 salt and ice was used to aid in keeping down the temperature. The 
 cathode electrode was an Illium lug of 7.599 square centimeters 
 surface area. The cathode chamber was a glass cylinder 3 inches in 
 diameter and 4 inches high. The 15 cubic centimeters of nitric acid 
 was added in about 15 minutes, or at the rate of 1 cubic centimeter 
 per minute. After 1 1/4 hours, the reaction was stopped. It was 
 observed that the brown fumes of nitrogen (HO2 ) issued from the 
 anode during the reaction, but more actively at the beginning of the 
 reaction than near the end. The lead anode was eaten through 
 
VIPI^fG Di/2&G/^ra 
 CELL /3EBClLfGEnENT„ 
 
 Wdt-mr- Cooleei L.e«ct t^rrocfe. 
 
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completely and lead sulphate deposited in the bottom of the cell 
 due to the oxidation effect of nitrogen dioxide in the presence of 
 the sulphuric acid solution. The brown ring test with ferrous 
 sulphate formed the unstable FeS 04 *^ 0 , verifying the presence of 
 unreduced nitric acid or at least no further reduction than nitrous 
 acid. The usual steps in this rSduction are; 
 
 MO 3 = MO 2 = ITH 2 OH = ITH 3 
 
 The increase of temperature around the cathode as the process 
 continued followed the graph as shown on the next page. Tests with 
 Fehling’s solution showed the absence of Hydroxylamine. It is 
 evident that the procedure as carried out was above the decomposition 
 temperature of Hydroxylamine , therefore eliminating the possibility 
 of its preparation, 
 
 COHTROL OF TEI.fPERATURE 
 
 The next attempt to control temperature prompted a slight 
 change of set-up. In this case the lead anode coil was placed around 
 the porous cell and the porous cell was made the cathode compartment. 
 The quantities used ; 
 
 Anode - 200 cc b0% H 2 SO 4 
 Cathode- 30 cc 50^ H 2 SO 4 
 Cathode 3.2 grams, HITO 3 (4-5cc 50;^) 
 
 The current was reduced to ten amperes. The temperature of the 
 water through the lead tube was I 6 degrees Centigrade. An ice and 
 salt mixture surrounded the anode chamber. The temperature was 
 much mo?.’e under control in this case than before as will -be seen 
 by the graph. The solution of Hydroxylamine sulphate was treated 
 with barium chloride solution (50^) and the sulphate precipitated 
 
( 
 
“10 
 
 out, leaving the hydrochloride of Hydroxyl amine in sol^ition. This 
 solution was evaporated almost to dryness and the crystals removed 
 as formed. Treatment with 95^ ethyl alcohol extracted the hydro- 
 chloride crj'stals or at least v/hat appeared to be the crystals of 
 the salt. Crystals of ammonium, chloride remain comparatively 
 undissolved. The insoluble crystalline residue was filtered off. 
 
 The crj^stals treated with sodium hydroxide gave off abundant 
 ammonia fumes, confirming the statements of some authors that the 
 electrolytic reduction of nitric acid goes over completely into 
 ammonia and ammoniumi compounds. The alcoholic solution, upon 
 evaporation in vacuum* on the water bath, gave additional crystals 
 which also gave the test for ammonia. Hehling’s solution was not 
 reduced by the crystals of either the first or second batch. The 
 crystals were distinctly acid and gave off an odor of chlorine. 
 
 A partic-1 explanation for not obtaining Hydroxy lamine might be again 
 attributed to the temperature which was still too high around the 
 cathode to favor its formation. The lowest temperature during the 
 run was 22® Centigrade, with an average temperature of appro xim*ately 
 39° Centigrade. The decomposition of Kydrosylamdne takes place 
 at 33® Centigrade, 
 
 GREATEST HEATIHG AROUHi: THJi! CATHODE 
 Apparently the highest heating area is in the cathode 
 compartment. This v/as found to be true not only when the cathode 
 
 was in the inner cell and surrounded by the lead anode water coil, 
 
 to 
 
 but also when the ca,thode chamber was the outer chamber nex;^the 
 ice-salt mdxture. The latter method seemed the most promising, 
 i.e. v/ith the cathode cell as the outer cell. 
 
- 11 - 
 
 EFPECT OF SLOW ADDITION OF NITRIC ACID 
 A porous cell 2 inches in diameter and 4 inches high was 
 substituted for the 1 1/2 inch cell so as to give a greater capacity 
 and reduce mechanical difficulties. Glass tubes were placed into the 
 ca.thode chamber and an ice-salt water mixture alloY/ed to flow through 
 them thus aiding in keeping the solution in the cathode cooler than 
 ever before. 
 
 The quantities used 
 
 Anode - 125 cc, 50^ H 2 SO 4 
 Cathode 150 cc. 50^ H 2 SO 4 
 Cathode 30 cc. 50^^ HNO 3 
 
 In every determination made, the nitric acid was added more or 
 less rapidly. Possibly too ra,pid an addition of the acid would 
 prevent its reduction of Hydro rylamine. At any rate very positive 
 brown ring tests showed the presence of unreduced nitric acid in the 
 cathode solution. This time care v/as taken to add the acid drop by 
 drop at the rate of 1/2 cc, per minute. A current of 10 amperes v/as 
 passed through the cell for two hours. The current was allowed to 
 continue for one hour a.fter the last addition of nitric acid had 
 been made, A.fter the first hour, some of the cathode solution 
 pipetted out and m.ade alkaline, gave an excellent reduction reaction 
 (Fehling*s solution) confirming the presence of Hydroxyl amine. To 
 ascertain just where the reduction reaction took place in the cathode 
 cell, a portion of the solution farthest away from the electrode v/as 
 subjected to the brown ring test (FeS 04 ). The presence of unreduced 
 nitrates or nitrites was confirmed. No reduction of Fehling^s 
 solution could be obtained. Evidently, then^ the reaction for 
 
- 12 - 
 
 reduction took place in the immediate vicinity of the cathode and 
 those nitrate or nitrite ions which were migrated did not enter into 
 any reduction process. The lead anode v/as covered with a hrown 
 lead dioxide. Upon titration with 2 % potassium permanganate, the 
 solution showed 20^ ammonium hydroxide. During electrolytic 
 reduction operations such as we have carried out, there is hydrogen 
 evolved at the cathode. After two hours the Illium lug v/as covered 
 with a brown film and at the same time no m.ore bubbles of liydrogen or 
 of any gas came off through the liquid. The reaction was stopped. 
 After an hour a repeated test v^rith Fehling’s solution gave negative 
 results. The probable reason for not obtaining Hydroxylamine again 
 was because of the presence of unreduced nitric acid in the cathode 
 solution which reacted with the Hydroxylamine form.ed, decomposing it, 
 
 FACTORS EFFECTING STABILITY OF HYDRO XYLAI^DTE 
 
 Further attempts have shown that the use of two Illium lugs 
 with a total area of 15 square centimeters gave better results, 
 because a more desirable potential for reduction is obta,ined. 
 
 The follow'ing determiinat ion was run for three hours; 1 1/2 
 hours of that tim.e was taken in adding the nitric acid. The current 
 of ten amperes was again used but with a greater cathode area the 
 potential developed was different. The sarnie quantities of solutions 
 were used as in previous run. The cathode solution was kept at a 
 temperature of 12® - 13® Centigrade during the run, A jigger aided 
 in shaking up the nitric acid into the solution as it Tvas added. 
 
 This solution tested positively for Hydroxylamine sulph.a,te with 
 Fehling’s solution, both at the lov/ temperature and at ordinarj^ room 
 temperature. This confirmed the stability of Hydroxylamine sulphate 
 

 
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-13- 
 
 when these two factors are kept in mind: 
 
 1, Keep the temperature at 15® Centigrade or less, 
 
 2, Continue the electrolysis for a considerable time aftei 
 the last addition of nitric acid. This seems to insure more complete 
 reduction of the nitric acid and lessens the opportunity of its 
 being present in large enough quantities to decompose the Hydro xy- 
 lamine. How an attempt was made to convert the Hydroxylamine 
 sulphate into the hydrochloride, by a better method than the old 
 barium chloride method used before. Eickhoff^^ states that if the 
 calculated quantity of barium chloride be added to the Hydroxylamine 
 sulphate solution and the barium sulphate removed by filtration, the 
 Hydroxylamine hydro chlo ride may be separated by concentration and 
 crystallization. This method is difficult to carry out, however, 
 and the yield is always poor. If barium chloride is in excess, 
 double salts form and then it is not easy to calculate the exact 
 quantity of the chloride required for neutralization. 
 
 COITVERSIOIT OE THE SULPHATE TO THE HYDROCHLORIDE THROUGH 
 
 BEHZALDOXIIS 
 
 The acid solution was neutralized with sodium hydroxide 
 keeping the temperature belov/ 15® Centigrade. Then 100 cubic 
 centimeters of benza.ldehyde , ice cold, was add.ed to the Hydroxylamine 
 sulphate. The purpose of this procedure was to form the oxim.e and 
 then to hydrolyze the oxime with hydrochloric acid giving the 
 aldehyde again and Hydroxylam.ine , Later attempts at hydrolysis were 
 unsatisfactory as far as conf irmato rj’- tests for Hydroxylamine 
 hydrochloride were concerned. The cause due to the fact that in 
 neutralizing the solution with sodium hydroxide the solution must 
 
14- 
 
 have been made alkaline. If this was true Hydro xylamine would have 
 been liberated before it had an opportunity to combine with the 
 aldehyde, as the oxime. According to the literature, a large amount 
 of the Hydroxylamine is lost even upon careful hydrolysis of the 
 oxime in slightly acid or neutral solution. It is quite possible 
 to explain the reaction between the amine and the aldehyde as 
 follows, however 
 
 
 'O 
 
 H 
 
 -h NH^ OH 
 
 L 
 
 /MHpH 1 
 Co,oir~ ioH] 
 
 
 'H 
 
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 1 
 
 
 ■H 
 
 Hd 
 
 CJ-LC 
 
 ngH 
 
 H 
 
 Hy d ro lamin e - 
 
 Hydrochloride Benzaldehyde Benzaldoxime 
 
 If Hydro xjj^lamine hydrochloride could be prepared in 
 electrolytic cell directly without any intermediate steps such 
 barium chloride precipitation or a hydrolysis of an amine, the 
 method would be invaluable, Schoch and Pritchett offer such a 
 and so a study of the reduction of nitric acid in the presence 
 hydrochloric acid instead of sulphuric acid was carried out. 
 
 the 
 as a 
 
 metho< 
 
 of 
 
 DIRECT PREPARATICH OE THE HYDROCHLORIDE 
 The qu 8 .ntities used 
 
 Anode - 125 cc 50^ H 2 SO 4 
 
 Cathode 150 cc 50^^ HCl 
 
 Cathode 20 cc 50^ H>T0a 
 

-15- 
 
 A current of 10 amperes was used. The temperature was kept at 
 11® - 14® Centigrade. Two hours was taken in adding the nitric acid 
 and this was followed "by another hour of electrolysis to reduce the 
 nitric adid as completely as possible. It will be observed that 
 sulphuric acid was placed in the anode chamber as before. 
 
 Hydrochloric acid would have eaten the lead anode if it had been 
 substituted. 
 
 The final reduced solution gave the conf irmato rjr test for 
 Hydroxylamine so the next step was the evaporation under vacuum on 
 the water bath. It was possible to only partially evaporate the 
 solution, hov/ever, upon analysis, it was found that there Y/ere 
 sulphate ions present in the salution, and this meant a high boiling 
 constituent. The sulphate ions had migrated from the anode cell 
 and had to be removed from the mixture of IIH 2 OH.HCI and HCl by 
 precipitation with barium chloride. Again this involved intermediate 
 steps of precipitation, filtration and re-evaporation. Apparently 
 the loss of Hydroxylamine was again experienced. If any of the 
 nitric acid was present and unreduced it vfculd without doubt 
 decompose the Hydroxylamine when the solution was heated during 
 evapo ration, 
 
 REDUCTION OE NITRITES TO BENZALDOXIL'ES 
 Nitrites are one stage farther reduced than nitrates 
 therefore, why would it not be possible to use all the current energy 
 in the reduction process from the nitrite stage on to the Hydroxyl- 
 amine stage? At the same time, if Hydroxylamine is formed could it 
 not be converted into benzaldoxime directly in the cell and later 
 hydrolyzed to give Hydro x^j’-lamine hydrochloride? 
 
- 16 - 
 
 This possibility was next considered. 
 
 The quantities used 
 
 Cathode 60 cc 50^a HCl 
 
 70 cc Benzaldehyde 
 15 cc UalT 02 (15 gr, ) 
 
 Anode 125 cc 50^ H 2 SO 4 
 
 The temperature was higher for some reason a.nd was about 25® Centi- 
 grade, With a current of ten amperes flowing for t"wo hours, a. 
 two -layered solution was obtained. The benzaldehyde was separated 
 from the hydrochloric acid solution. The solution reduced potassium 
 permanganate, but did not effect Fehling’s solution. It was con- 
 clusive of the absence of the amine. It is understood that nitrites 
 are readily reducable in acid or neutral solutions and in fact we 
 find some reducing constituent present in this case. Whether the 
 Hydroxylamine will combine with the aldehyde in acid solution is 
 very doubtful. The Hydroxylamine, if formed, probably decomposed 
 imm.ediately because the temperature was 25® Centigrade during the 
 run. Sodium nitrite is very easily decomposed by an acid solution 
 setting free nitrous acid (nitric and nitrous oxides. ) 
 
-17- 
 
 V. 
 
 Conclusion 
 
 From the work carried out we have been able to observe some 
 of the characteristic reactions 7/hich occur in the electrolytic 
 reduction of nitric acid or sodium nitrite and from these observatiom 
 certain points have evidenced themselves namely, - 
 
 1. The reduction of nitric acid to Hydro ::!ylamine depends most 
 vitally upon the maintainance of as low a temperature as possible 
 preferably 15° Centigrade or less, 
 
 2. To obtain the best results, a continued run for some length 
 of time after the last addition of nitric acid is desirable. This 
 might be further explained by the fact that, 
 
 5, Hitric acid, when present to any great extent, in an unre- 
 duced state decomposes hydro xylamine. 
 
 4. The importance of adding nitric acid drop by drop to the 
 cathode solution instea,d of by rapid addition is fundamental. This 
 gives a better opportunity for the total reduction of the acid as it 
 is dropped into the solution. An accumulation of unreduced acid 
 verifies conclusion 3. 
 
 5. Reduction occurs only in the immediate vicinity of the cathode 
 
 electrode and not through the entire cathode solution as is sometimes 
 
 / 
 
 suppo sed, 
 
 6. Illium can be used successfully in the electrolytic reduction 
 of nitric acid. It has a sufficiently high potential when in a 50 ^ 
 sulphuric acid solution to warrant its use for a cathode electrode. 
 
1 
 
 ’’ * , ,') 
 
-18- 
 
 VI 
 
 Eitliography 
 
 1. M. A, Besson, Comptes Rendus, 152, 1850 (1911.) 
 
 2. Ezio Comanducii, Chem. Zentr. I, 1530 (1909) 
 
 3. J. Tafel Zeit, Anorg, Chem. 31, 289, (1902) 
 
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