760 DIVERS AND HAGA OXYAMIUOSULPHONATES 1;XXI.-Oxyamidosulphonates and their Conversion into Hyporiitrites. By EDWARD DIYERS M.D. F.R.S. and TAMEMASA HAGA P.C.S. IN our paper on the Reaction between Sulphites and Nitrites of Metals other than Potassium (Trans. 1887 51 659) we gave notice of our intention to work on the reactions with the sodium salta. This we have done and are already in a position to materially extend an AND THEIR CONVERSION INTO HYPONITRITES. 761 modify our knowledge of the chemistry of the sulphazotised com-pounds contained in the writings of our predecessors in the investiga-tion Fremy (Ann. Chim. Phys. [3] 15 408) A. Claus and Koch, (Annalen 152 336; 158 52 and 194) Berglund (Bull. Soc. Chirn., 25 455 ; Bela. 9 252 and 1896) and Raschig (Annalen 241 161).We propose t o publish our contribution t o this large subject in it few short papers like the present each complete in itself. Oxyarnidosulphonates the subject of the presel=t paper are the sulphazidates of Fremy the sulphydroxylamates of Claus the hydroxyl-amiiae-monosulphoitates of Raschig. Between the one set of terms-&hilo- imido- and amido- oximitlo- and oxyamido-sulphonates-and the other set-amine- and hydroxylarnine- tri. di- and mono-sulpho-nates-there is not much to choose. As however it is desirable on the score of consistency to employ exclusively either one set or the other, the use already prevalent of nitrilo- imido- and amido-sulphonate makes it advisable to employ the term oximido- and oxyamido-sul-phonate rather than hydroxylamine- di- and mono-sulphonate.Oxyamidosulphonic acid known only in solution was first prepared by Fremy who found that potassium oximidosulphonate (neutral sulphazotate) sooner or later decomposed into acid sulphate and the oxyamido salt the change taking place at once when the. solution was boiled. Altering the atomic weights to those now accepted and writing empirically his formula to which he attached no censtitu-tional significance his equation becomes-Claus has shown however that these formulae do not correctly repre-sent the composition of the salts ; and Raschig has confirmed Clam’s statement. The t w o f o r m u h corrected stand as S4018K41110N2 and S20,K2H4N2 or HON(S03K),( OH,) and HONH( S03K) accord-ing t o Claus. The latter formula we find it necessary to modify slightly.To get the oxyamidosulphonic acid pure for the preparation of its salts Fremy neutralised the hydrolysed solution of potassium ox -irnidosulphonate with ammonia added barium chloride filtered off the sulphate and then by the addition of baryta-water threw down a precipitate of a dibarium oxyamidosulphonate. This salt when washed was decomposed by adding just enough sulphuric acid to combine with the barium ; the filtered solution of the new acid being used f o r preparing the salts by combining it with the corresponding bases. The acid appears to be the only sulphoxyazotised acid pas-* He recognised the peculiarity and importance of this first instance of what we now style the hydrolysis of a sulphonate into a sulphate 7 62 DIVERS AND HAOA OXYAlfIDOSULPHONATES sessing any stability.Clam introduced a slight modification in E’remy’s process by omitting the preliminary neutralisation with ammonia As we have discovered a second barium salt which is neutral and soluble we treat the barium precipitate in a different way and thereby avoid the contamination of the salts with sulphite as the latter is always present in Fremy’s barium precipitate (see the sec-tion of this paper headed ‘‘ Decomposition of Oayanaidosulphonates by AZkaZim Bases,” p. 765). The dibnrium salt is as found by Fremy, very alkaline to litmus and we add to it only enough sulphuric acid to remove half the barium as sulphate getting a neutral solution which contains only monobarium oxyamidosulphonate ; from this the acid and its salts can be prepared by adding the equivalent quantity of sulphuric acid or a aulphate.In order to determine the quantity of snlphuric acid requizled it is necessary to estimate the barium in a portion of the solution. Rascbig prepares an impure acid from Fremy ’s solution obtained by boiling potassium oximidosulphonate so as to hydrolyse it into potassium sulphate and oxyamidosulphonate. To do this he removes the potassium snlphate by alcohol and then concentrates the solution of the acid to a syrupy consktence. Sodium oxyamidosulphonate as prepared by Fremy and by us is a clear gummy liquid as viscous as molasses; this when exposed over sulphuric acid under diminished pressure never solidified or showed any sign of crystallisation. Potassium ozyamidosulphonste prepared and analy sed by Fremy by Claus and by us wben crystallised from its hot solution forms six-sided places as stated by Premy but the plates are more often square ; by spontaneous evaporation of the cold solution however, thick tables and bold prisms are obtained.Claus found the crystals to be anhydrons and Fremy’s analysis and formula agree with this observation. Fremy’s analytical resul ts cannot be relied on how-ever and we have already had t o give an instance of this in the present paper md shall have to give others. We differ from Claus, inasmuch as we find t h a t all the crystals of this salt effloresce slowly over sulphuric acid and on analysis give results indicating the presence of 1 mol. H,O. The solutions shorn a great tendency to supersaturate and it often becomes very difficult to crystallise them.When thoroughly dry the crystals can be kept for months without undergoing much change but if moist they are unstable hydrolysing, and becoming acid to litmus. The acidity developed is that of hydroxyammonium sulphate hadly showing with methyl-oramge. When heated they suddenly intumesce below loo” and are com-pletely decomposed. It is neutral in reaction AND THEIR CONVERSION INTO HYPONITRITES. 763 23.45 7-69 19.76 9-29 To determine the sulphur and nitrogen we hydrolped the salt by heating it in a sealed tube with hydrochloric acid at 130" following Raschig's process which however gives somewhat irregular results, as we afterwards found (see the analysis of the dibarium salt).The hydroxylamine thus produced was estimated by iodine after addition of potassium hydrogen carbonate. Water could not be removed by exposure over sulphuric acid at the ordinary temperature and pressure rapidly enough t o be convenient for analytical purposes ; this and other sulphazotised salts retaining according to our ex-perience part of their water of crystallisation with great tenacity. Neither could the water be conveniently driven off in the oven, because of the decomposition of the salt at about 95"; we made a fairly good estimation of it however by moderately heating the salt in a Sprengel-vacuum in a long bulbed tube containing also sulphuric acid The following is a table of our results:-I -7-56 17-50 -HONH(SO,K),OHZ. Potassium. .Sulphur . Oxyamidogen HONH . Water . 23 -08 7'58 18 -94 10 *39 a. -22 '53' 7'34 17 -96 6. f-'--Sample a mas in prisms b in tabular crystals. We have given much consideration to Claus's results apparently carefully obtained, but we are unable to offer any explanation of their difference from ours. We have prepared the salt in winter and in summer (when he found it difficult to work) by evaporation of cold solutions and by cooling hot solutions and have always obtained crystals which slowly effloresced in the desiccator. Dibarium osyamidosulphorcate prepared by Fremy and by us is a crystalline alkaline nearly insoluble salt. It dissolves in hydro-chloric acid and then shows by the odour evolved the presence of sulphite as an impurity varying from a trace only to a considerable quantity.The only analytical datum given by Fremyis that the salt is formed from one equivalent of acid and two equivalents of baryta. We have analysed it and found for it a composition agreeing with the formula given by Fremy less the H by which his formuh generally exceed those now adopted. In this analysis and that of the following salt we slightly modified the method of hydrolysis so as to get uniform and higher numbers * Slight lose of potrtssium sulphate during cooling known to have occurred 7 64 DIVERS AND HXGA OXYAMIDOSULPIIONATES 36.2'7 16-84 for the hydroxylamine. The modification consisted in heating for some time with hydrochloric acid at 100" before raising the tempera-ture to 130". We find that hydroxyammonium sulphate itself may be rapidly heated with acid to 130" or even higher withont getting low results from which it would appear that at the moment of its formation at 130" from its sulphonic-derivative hydroxylamine is less stable than when already formed.The constitution of the 35.88 16-65 - -N( 0 H) *s 0 dibarium salt is expressed by the formuIa Ba<N(olr) ,sO~>Ba,0H2. Calculated. Found. Barium 53.31 53.13 Sulphnr 12.45 12.41 Oximidogen HON 12.06 12.02 Barium oayamidosulphonate prepared by us in solution first as already described in this paper (p. 762) by adding just enough sul-phuric acid to the dibarium salt to remove half its barium. The neutral liquid thus obtained yields crystals of the salt on evaporation over sulphuric acid; it is very soluble and forms small hard bril-liant square tabular crystals intermixed with minute square prisms ; the crystals contain water.When long kept it decomposes. Heated neady to loo" it suddenly and violently decomposes into gases and barium sulphate. In annlysing it the barium was determined in one case by igniting it with sulphuric acid (a) ; in two cases the salt was slowly heated with dry sodium carbonate whereby oxygen was absorbed from the air after which the heat was raised until the mixture fused and the barium and sulphur were then both determined ( b ) ; in another case the salt was hydrolysed by heating with hydrochloric acid the separated barium sulphate (representing all the barium and half the sulphur of the salt) weighed the other half of the sulphuric acid precipitated with barium chloride and lastly the hydroxylamine titrated with iodine (c).The results were the following:-(HONHSO&Ba,OH,. Barium . Sulphur . Oxyamidogen HONH 36 -15 16 -88 16.88 c. 35.53 16 -49 16 -50 The Hydrolysis of Ozy amidosulphonic Acid. Although oxyamidosulphonic acid is relatively stable the fact that Raschig its solution does decompose was fully noticed by Fremy AND THEIR CONVERSION INTO HYPONITRITES 765 has found that the decomposition proceeds sharply and in presence of hot acid rapidly according to the equation-2HONHSO3H + 2H2O = (NEsOH),SOa + HzSOa. With this important observation we fully agree from experience. Fremy stated that when the acid is boiled with water it decomposes wholly into acid ammonium sulphate and oxygen or hydrogen per-oxide.His finding ammonia and oxygen (or any gas) cannot be explained. He appears to have tested for hydrogen peroxide by adding manganese dioxide which would account for his finding it. since an effervescence of nitrous oxide might easily pass for one of oxygen. Claus expressed his hesitation to accept Fremy’s equation (modi-fied)-2H0NH(S03H) + 2H,O = 2(NH4)HSOa + 02-as quanti-tative b u t at the same time admitted that he had also obtained (besides sulphuric acid) ammonia and oxygen (or nitrous oxide). Raschig got other results as already stated and did not find either ammonia or oxygen or nitrous oxide. These inexplicable differences have their parallel in what is contained in the next section of this paper only there the differences noticed arise between ourselves and the other workers.I n presence of hydrogen potassium carbonate oxyamidosulphonaOes react with iodine solution like a hydroxylamine salt only very much more slowly ; so that their amount can be titrated in this way without previous hydrolysis though only with difficulty. Decomposition of Oxyamidosulpbonates by Alkaline Bases. The decomposition of oxyamidosulphonates by a solution of potas-sium hydroxide appeared to have been fairly well worked out when we came to give attention to it. Fremy had observed that when heated with excess of this reagent the potassium salt disengaged ammonia as well as oxygen of which as he says he had established the absolute purity by analysis. Hence it seemed that oxyamido-sulphonates undergo the same decomposition when heated with alkali as when heated with acid.Lossen had just discovered hydroxylamine when work on the sulphazotised compounds was taken up by Clans and this circum-stance led the latter to see in the reaction between potassium hydroxide and Fremy’s sulphazidate as observed by Fremy and by himself most convincing evidence that the salt is constituted as a sulphonic derivative of hydroxylamine and is decomposed by the action of alkali into this base and potassium sulphate. He did not, he admits succeed in isolating the hydroxylamine or any of its salts 766 PIVERS AND HAGA OXYANIDOSULPHONATES but he found all the sulphur of the sulphazidate converted into sul-phate and the other compounds in just the same proportions as Lossen had found when hydroxylamine is decomposed by heating with alkali, namely ammonia equivalent to between a third and a half of the total nitrogen and gases which neither extinguished nor rekindled a glowing match and were therefore not the pure oxygen of Fremy’s finding but might well be nitrogen mixed with nitrous oxide as required on the supposition made.Added to this was the fact of the reducing action which the alkaline mixtnre exerted upon copper and silver salts and the proof seemed complete. Raschig in his recent paper went further in the matter than Claus, and with or without experimental evidence-for we cannot decide from his words-concluded that an (unheated) alkaline solution of oxyamidosulphonic acid is actually a solution of free hydroxylamine, the latter being present in the quantity calculated from the amount of the acid taken and therefore just such a solution of hydroxyl-amine as is wanted for preparing aldoximes and acetoximes.Now with two exceptions namely that nitrous oxide is given off, and that copper and silver salts are reduced-an action to be tzeated of in the following section of this paper-we are unable to confirm any of the observations of these chemists. This decomposition of oxyamidosulphonates by alkali is of another and still more interest-ingcharacter than Claus and Raschig conceived it to be. That the oxyamidosulphonates are hydroxylamine-derivatives which hydro-lyse in acid solutions into hydroxylamine and sulphate is indeed, certain as ascertained by Raschig.But nevertheless in aZkaZine solutions they give neither sulphate nor hydroxylamine nor the decomposition-products of hydroxylamine. Oxyamidosulphonates decompose with potassium hydroxide and similar reagents exclusively into sulphite and hyponitrit,e and the decom position-products of a hyponitrite. No ammonia is formed, neither so far as we could judge any sulphate or any nitrogen or, if any only unimportant quantities of nitrogen and sulphate. The difficulty of keeping a sulphite solution for days free from sulphate, and of detecting small amounts of nitrogen in presence of nitrous oxide are well known and sufficiently explain any uncertainty in oiir results. The total absence of ammonia peremptorily forbids any admission of the generation of hydroxylamine.Cold dilute alkali or alkaline-earth hydroxide suffices to partly effect the change under consideration. Consequently every attempt to form dipotassium or disodium oxyamidosulphonate corresponding with the dibarium salt has failed in our hands because of this re-solution of the salt into simpler ones on the addition of alkali. For the same reason also we find that Fremy’s dibarium salt describe AND THEIR CONVERSION INTO HTPONITRITES. 767 in this paper although insoluble cannot be prepared quite free from sulphite and wheu kept for any considerable time becomes charged with it and also contains traces of hyponitrite. To effect the complete or nearly complete conversion of khese salts into sulphite and hyponitrite they may be either left for days in the cold with the very strongest potassium hydroxide solution or be heated to boiling for a short time with strong alkali.I n both cases, effervescence occurs due t o the decomposition of hyponitrite. The gas evolved is not the feeble supporter of combustion met with by Claus but behaves like oxygen as Fremy had observed; i t is not oxygen however but nitrous oxide soluble in water. The highly alkaline liquid when acidified gives abundance of sulphur dioxide, and if neutralised merely will give with barium chloride a precipitate which might of course be taken for sulphate by a mind prepossessed, as Claus’s almost admittedly was and which does as is well known, rapidly change into sulphate on the filter. When partially or fully neutralised with acetic acid the solution on treatment with sufficient silver nitrate gives much silver hyponitrite together with a very little reduced silver owing to the sulphonic acid not being entirely destroyed.At first the silver nitrate goes to form potassium silver sulphite but this can be avoided if desired either by using the barium salt instead of the potassium salt or by adding barium hydroxide and then filtering o f f the barium sulphite before adding the silrer nitrite. This decomposition actually furnishes by far the most productive method of preparing hyponitrite yet discovered. The following are the results of some trials we have made the silver hyponitrite having been purified by the authors’ method (Trans. 1884 45 Sl) that is by dissolving it in nitric acid and reprecipitatiiig with sodium car-bonate.Generally the silver hyponitrite was directly weighed but in one or two cases it was converted into chloride before weighing :-Digestion of 0.5772 gram of crystals of potassium oxyamido-sulphonate for 24 hours with a saturated solution of potassium hydroxide containing some solid potash. It still contained a very small quantity of the sulphonic salt undecomposed but the yield of hyponitrite in this case was 76 per cent. of the theoretical amount ; Boiling 0.9370 gram of crystals with concentrated potassium hydroxide for a short time was attended with copious efferves-cence of nitrous oxide but still left a little of the salt undecom-posed ; the yield of hyponitrite however was 30 per cent. of the equivalent of the salt taken.In order to prepare hyponitrite from nitrite in this way there is n 768 DIVERS AND HAQA OXTAMIDOSULPHONATES necessity to have the oxyamidosulphonate pure ; a well-prepared solution of either alkali salt safficiently concentrated is all that is necessary if treated with solid potassium hydroxide. Working in this way we found-0.4545 gram of sodium nitrit,e* after conversion into the sulphonic salt and treatment in the cold with the most concentrated potash for 24 hours gave hyponitrite amounting to 40 per cent. of the full yield had all the nitrite been utilised ; 0.5833 gram of sodium nitrate," after conversion was treated first in the cold for 21 hours and then at 100" for a quarter of an hour, and yielded hyponitrite amounting t o 492 per cent.of the cal-culated quantity. In order to get results as good as these however one modification of the process for getting the oximidosulphonate from the nitrite must be followed; we reserve the account of this for the paper on these salts. Here we need only mention that we can get at least 85 per cent. of the calculated quant.ity of oximidosulphonate from the nitrite a proportion far higher than that previously obtained by Raschig the only quantitative worker. In consequence of the decomposition of much of the potassium hyponitrite into hydroxide and nitrous oxide the determination of' the hyponitrite found does not of itself serve to prove that the formation of this salt is the only decomposition of the oxyamido-sulphonate. But it does make this deduction highly probable when taken along with the occurrence of so much nitrous oxide and sulphite and the absence of ammonia nitrogen and sulphate.The determination of the sulphite however seems sufficient of itself to prove that the decomposition is of one kind only although here too, any very close a.pproach to the calculated amount cannot be expected, considering the ready oxidisability of sulphites to sulphates and that the sulphonate is never entirely decomposed. The presence of hypo-nitrite and its reaction with potassium iodide render a volumetric estimation of the sulphite by means of iodine impossible ; in order, therefore to estimate the sulphurous acid we availed ourselves of its reaction with stannous chloride. The latter has no action either upon hydroxylamine (Divers and Haga Trans.1885 47 624) or upon oxyamidosulphonic acid. Our method of procedure was to put into a pressure-bottle the diluted solution of the salt decomposed by alkali and neutralised mix it with excess of stannous chloride and almost fill the bottle with water. The tightly closed bottle was kept in nearly boiling water for an hour and then left to cool. The * Measured off for analysis as oxyamidosulphonate solution produced from a large quantity of nitrite worked upon AND THEIR CONVERSION IXCO HPPONITRITES. 769 washed precipitate of stannous snlphide was heated with hydro-chloric acid and pot,assium chlorate until all the sulphur had been oxidised and the solution after being evaporated to dryness was again evaporated to dryness with hydrochloric acid.Finally after removing the tin by hydrogen sulphide the sulphuric acid in the filtrate was estimated as barium salt. In this way from 0.7470 gram of salt which by long keeping had slightly hydrolysed, we got sulphur equivalent t o 88.63 per cent. of all that was in the original sulphonic salt. This result renders i t clear that sulphite and, therefore hyponitrite are the only two primary products of the change. The reaction by which hyponitrite and sulphite are formed consists probably i n the substitution of potassium for the hydrogen of the oxyamido-radicle and then of spontaneous decomposition of the potassium compound. There is no hydrolysis or saponification, simply dissociation or chemical fission-HONHSO3K + 2KOH = KONKSOSK + 2HzO 2KONKSO3K = (K0N)z + 2KzSO3.Raschig bas observed a decomposition of Fremy’s potassium sulph-azite by strong potash into sulphite and nitrite very similar to this. We would gladly account for. the differences between the results found by other chemists and our own but we are able to do little in this direction. We have to face the fact that Claus’s work was quantitat,ive. The only suggestion we can offer is that Fremy and Claus’s preparations originally pure were not treated with alkali until they had been kept long enough to undergo the decomposition (fully in Claus’s case)-SHONH(S03K),OH = (HONH,)2SO + K2S04 into hydroxylamine and sulphate. Such a mixture would behave exactly in the manner observed. As for oxygen Fremy must have mistaken nitrous oxide for it and in making this supposition we have evidently the support of Claus and Raschig.Lastly as to Claus’s nitrous oxide diluted with nitrogen dilution with air and steam may perhaps have been the cause of the properties of the gas he got differing from that obtained by Fremy and ourselves. Oxyamidosulphonates evaporated to dryness on a water-bath with potassium or sodium carbonate evolve carbon dioxide during the last stages of the evaporation and yield much sulphite. No hypo-nitrite can remain undecomposed under such circumstances. A solution of oxyamidosulphonate left even in the cold for a day with the carbonate shows evidence of the presence of st little snlphite 7 i0 DIVERS AND HXGA OXTAMIDOSULPHONATES After repeated evaporations with potassium acetate an alkaline mixture containing a minute quantity of sulphite is left.Oxidation of 02 yamidosubhonates by Basic Reagents. Fremy observed that manganese dioxide dissolved as manganous salt in oxyamidosulphonic acid with effervescence due to evolution of oxygen also that the same reagent caused it lively effervescence in a solution of the potassium salt. These observations are correct save that he mistook nitrous oxide for oxygen. Finally he found that the potassium salt immediately reduced salts of silver copper and gold. We must however except copper from this statement unless alkali were present. Claus as we have already had occasion to mention found that the potassium salt in the presence of potassium hydroxide reduced ,salts of copper and silver in the cold just like hydroxylamine ; his experiments liowever were qualitative only.Raschig who holds that a1 kalis convert oxyamidosnlphonates wholly in to their equivalent of hydmxylamine records no experimental determinations in support of this point though he quantitatively estimated the hydroxylamine produced by the action of an acid. The reaction which we find takes place is the conversion of the oxyamidosulphonate into sulphite and sulphate and the reduction of a quantity of metaI-oxide equivalent t o the oxidation of the oxyamido-residue and not to that of the hydroxylamine supposed to be pro-duced. That is to say the ouprous oxide obtained is just half what it would be were hydroxylamine first formed as believed by Claus and Raschig. The equation therefore will stand thus :-2HONH(S03K) + 2CuO + 2KOH = KZSO3 + KZSO + CUZO + NZO + 3Hz0, which shows that the potassium hydroxide takes the t w o sulphonic residues to form sulphite sulphate,* and water the copper oxide oxidising to water the two atoms of hydrogen of the two oxyamido-residues the hyponitrous acid left being resoIved finally into nitrous oxide arid water.After the reduction addition of hydrochloric acid liberates much sulphur dioxide. The reaction is not quite complete as it ceases when the solution becomes very dilute. Thus if to an aqueons solution of 1 gram of the oxyamidosulphonate in a litre of water a few drops only of a dilute solution of copper sulphate and then of potassium hydroxide, are added a permanent blue opalescence is produced but no cuprous oxide is deposited even when the solution is kept for hours in a * Hyposulphate waa searched for and could not be found AND THEIR CONVERSION INTO HYPONITRITES.771 closed vessel. This observation may serve to show that although, when very dilute alkalis do not produce much sulphite and nitrite, t h i g is not because hydroxylamine and sulphate are produced instead, for if such were the case the hydroxylamine would act upon the cupric hydroxide. The fact that the alkaline solution contains not hydroxylamine, but a sulphonic-derivative of it which gives sulphite in its reac-tions with reducible compounds and that i t has only half the action of its equivalent of hydroxylamine are serious if not fatal, objections to resorting to it as a reagent in organic research for the purposes suggested by Raschig.This chemist notwithstanding that he has pointed out (see his memoir p. 182) that the reason that oximidosulphonates do not possess any of the reducing powers of hydroxylamine is that in them the two active hydrogens of hydroxyl-amines are replaced by sulphonic radicles and that oxyamidosul-phonates by retaining one of these hydrogens are as easily oxidisahle as hydroxylamine itself has yet failed to see that his contention being well-founded it will be the oxyamidosulphonate and not hydroxylamine which exerts the reducing power in its aIkaline solu-lion. That it is so is shown by the fact determined by us that in the absence of reducible agents alkalis do not completely decompose oxy-itmidosulphonates and for the rest change them into sulpliite and hyponitrite neither of which gives a cnprons precipitate in presence of alkalis.It was unavoidable that the amount of sulphite produced should be imperfectly estimated partly because of the great oxidisability of the very dilute alkaline sulphite by air and partly because the decompo-sition of the oxyamidosulphonate is never complete. To measure it, the mother-liquoib of the copper precipitate was run into excess of half-decinormal iodine solution (mixed with acid enough to more than neutralise the mobher-liquor) and the unconsumed iodine titrated with sodium thiosulphate. The water used was always pre-viously freed from air by boiling. Of the salt 1.0967 grams treated with copper sulphate and potassium hydroxide gave in this way 40 per cent.of the sulphur of the salt as sulphite and that was our best result. Theory as given by us indicates 50 per cent.; whilst on the other view there should be none at all. Other portions of the mother-liquor of the copper precipitate were acidified to promote the hydrolysis of any of the sulphonate yemaining undecomposed and afterwards concentrated by evaporation. One of these then gave a distinct reduction with the copper mixture due t o hydroxylamine ; whilst another measured portion on titration with iodine in presence of hydrogen potassium carbonate also showed the presence of We have yet to supply particulars of our quantitative work 772 DIVERS AND IIAGA OXYAMIDOSULPHOKATES hydroxylamine equivalent however t o only one-twelfth of the whole salt.To measure the amount of copper reduced we added to 0.2913 gram of the salt (already slightly hydrolysed by keeping) dissolved in water a slight excess of a sort of Fehling’s solution much stronger than usual and with less alkali in it heated to boiling collected the cuprous oxide on a filter washed rapidly and weighed the reduced oxide as black oxide. We thus obtained cupric oxide equal to 48 per cent. of the weight of the salt instead of 47 per cent. calculated from our equation. On the other theory twice as much should have been obtained. In alkaline solutions silver and mercuric hydroxides act just like cupric hydroxide qualitatively at least and yield much sulphite. Constitution of Hyponitrites as revealed by the Decomposition of 0 % ~ amidosu lp honnat es.The decomposition of oxyamidosulpbonates in to sulphite and hypo-nitrite sets at rest any doubt as t o the constitution of hyponitrites ; for coming in this case directly from zt substituted hydroxylamine, a hyponitrite must have its oxygen between the nitrogen and metal. Berthelot and Maquenne have recently published papers (Compt. rend. 108 1286 1305) containing analyses of calcium and atrontium hyponitrites. These analyses as they point out establish the accu-racy of the empirical formula given by one of us (Divers) to hypo-nitrous acid upon which doubt had been cast by previous work upon the silver salt by Berthelot himself and Ogier (Cumpt. rend. 96, 30 84). To this salt the latter chemists gave the formula Ag4N405, the correctness of which was afterwards contested by us (Trans,, 1884 45 78).Berthelot now admits that this salt cannot be obtained in a pure state thus confirming our view as against Zorn, van der Plaats and Menke all of whom claimed to have got it in a pure state without difficulty. Zorn’s opinion that the molecule of the acid contains 2 atoms of each of its elements already generally accepted is now endorsed by Berthelot and Maqneune. Lastly, Maquenne is disposed to deiiy that nitrous oxide can be the an-hydride of hyponitrous acid even to the same extent that carbon monoxide is the anhydride of formic acid but on grounds which t o us seem quite insufficient. Even the facts recorded in this paper can leave hardly any doubt that it is so. The formula of hyponitrous acid may now confidently be written as HO*N,*OH or (NOH), that is the acid is hydroximidogen of which NOH is the radicle AND THEIR CONVERSION INTO HYPONITRITES.773 APPENDIX. We have again determined the sulphite produced both when potas-sium oxyamidosulphonate is decomposed by potassium hydroxide alone, and also when it is oxidised by the same reagent and cupric oxide. In these determinations the work was done in closed vessels excluding the air so that no appreciable destruction of sulphite could have occurred through acrial oxidation. Also in measuring the sulphite formed when the salt is oxidised by cupric oxide we employed here for the first time the stannous chloride process described in the paper. The salt was treated with the cupric oxide in an atmosphere of hydrogen in a bottle which was afterwards without opening filled up with stannous chloride and water.Only then and for a moment was the bottle opened in order t o remove the cork and gas tubes and insert the stopper before heating the mixture for an hour in boiling water. We feared that in washing the tin sulphides the copper sulphides mixed with them would give trouble by oxidising on the filter but our fears proved groundless. For the other decomposition by alkali alone we boiled the salt for a few hours with potassium hydroxide in a small tube in connection with a hydrogen-apparatus and when ready quickly dropped this tube with its contents into the bottle of stannous chloride. With the precautions we have taken we have now no longer to admit any imperfection known to us to have existed in our preparations for analysis and can give the new results so far with confidence as being closely accurate.The decomposition of the oxyamidosulphonate by potassium hydroxide into hyponitrite and sulphite using 0.2007 gram of freshly crystallised salt in fine plates gave 89 per cent. (89.05) of the sulphur as sulphite confirming our earlier result cjf 88 per cent. The oxidation of the salt by cupric oxide into sulphite sulphate and nitrous oxide effected on 0.4298 gram of the above-described prepara-tion gave 44 per cent. (43.93) of the sulphur as sulphite a result confirmatory of our theory and better than our best previous result of 40 per cent. It thus appears clear that the sulphite formed when the oxyamido-sulphonate is oxidised by cupric oxide is half what is produced when t.he salt is decomposed by alkali alone. That only nine-tenths of the reckoned sulphite is obtained in either case is partly if not entirely due to two causes. One of them is that as already pointed out in each mode of decomposition a little oxyamidosulphonate (or a body like it) is always left at the end of the reaction. The other and main one is that the tin reaction is incomplete ; for working upon sulphite of a known degree of purity we have got by its mean8 only 91 and again 93i per cent. of the sulphite indicated. VOL. LT. 3