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2110 BALL AND ABRAM : BISMUTHINITRLTES.

Published on 01 January 1913. Downloaded by Cornell University Library 30/06/2017 07:42:59. WXXJ V. --€?ismu t h initrit es. By WALTERCRAVEN BALL and HAROLDHELLING ABRAM. IN previous communications (T., 1905, 87, 761; 1909, 95, 2126; 1910, 97, 1408) one of the authors of the present paper has described several compounds of bismuth nitrite with the alkaline nitrites. These compounds were chiefly remarkable aa affording a method for the gravimetric estimation of sodium, and for its separation from potmsium, owing to the insolubility of msium sodium bismuthinitrite and the non-formation of the corresponding potassium salt (T., 1910, 97, 1408). As it is unusual to find such sharp differences in the behaviour of sodium and potassium salts, the present authors have investigated all the salts of this series which they have been able to obtain, in order to discover, if possible, other facts bearing on this difference in behaviour. The salts which have been obtained all fall into two groups, of which View Article Online

BALL AND ABKAM : BlSMUTElINITRlTES. 2111

the general formula are respectively X,Bi(NO,), and X,YBi(N02),. In these formulae X represents any of the metals ammonium, potassium, rubidium, msium, and thallium, whilst Y stands for either lithium, sodium, or silver. There are thus possible five compounds of the X,Bi(NO,), series, or simple bismuthinitrites, and of these, four have been obtained, the attempts to obtain the ammonium salt having been 60 far unsuccessful owing to the great instability of concentrated solutions of ammonium nitrite in the presence of acid. Although the ammonium salt has not been obtained, bismuthinitrites of several organic nitrogenous bases, such as cocaine and brucine, can easily be prepared. Of the mixed bismuthinitrites of the general type X,YBi(NO,),, fifteen are possible; for each of the metals X might exist together in a compound with any of the three metals represented by Y. These compounds have all been obtained. Although many attempts have been made to prepare compounds, in the solid state, containing two metals of the X series together, or two metals of the Y series together, they have been entirely unsuccessful. The same remark applies to all the attempts the authors have made to obtain compounds in the solid condition, containing two atoms of a Y series metal with one atom of an element represented by X, or to prepare compounds having the formula Y,Bi(NO,),. The simple bismuthinitrites of sodium and of lithium probably exist in solution, for deep orange-coloured liquids result when bismuth nitrate is added to solutions of the nitrites of these metals, just as happens in the case of potassium nitrite or of rubidium nitrite. Whereas, however, the bismuthi- iiitrites of the two latter metals can be precipitated from their Published on 01 January 1913. Downloaded by Cornell University Library 30/06/2017 07:42:59. solutions, this cannot be done with lithium or sodium. The apparent impossibility of preparing mixed bismuthinitrites containing only metals of the X series, or of the Y series, is well shown by adding czesium nitrate to separate solutions of the nitrites of sodium and of potassium each containing bismuth. With the sodium solution there occurs an immediate precipitate of the mixed salt, sodium czesium bismuthinitrite, even when traces only of msiurn salt are added. With the potassium solution there is no apparent change until a large quantity of cmium has been added, when a precipitate of the simple wsium bismuthinitrite gradually settles. Again, silver nitrate, the nitrate of an element of the Y series, when added to a solution of sodium nitrite containing bismuth, produces no deposition of a mixed compound containing two elements of the Y series, but on the addition of a potassium solution, or of a solution of any of the metals of the X series, there is at once a precipitation of the mixed X-Ag salt. View Article Online

2 112 BALL AND ABRAM : BISMUTHINITRITES.

This difference in behaviour between sodium and potassium, which, as above-mentioned, is sufficiently pronounced to form a method of separating them, is now to some extent explained; for potassium, being a metal of the X series, will not form a mixed bismuthinitrite with ciEsium, also a, metal of this series, whereas sodium, belonging to the Y series, will do so. As the caesium sodium salt is a very insoluble one, the metal can in this way be separated from potassium, collected, and weighed.* In a similar manner, cmium and rubidium may be separated from potassium,+ for on adding a mixture of salts of the three metals to a concentrated solution of sodium nitrite containing bismuth, the mixed bismuthinitrites of sodium with caesium, and of sodium with rubidium, will precipitate, being only very sparingly soluble, whilst the very soluble potassium sodium salt remains in solution. It seems, then, necessary, in order that a mixed bismuthinitrite should be capable of existence, that it should coxitain a metal of the isomorphous series, (NK,), K, Rb, Cs, T1, together with one belonging to the isomorphous series, Li, Na, Ag, the metal of the former series being present in the greater atomic proportion. A further series of five compounds exists, containing nickel in addition to a metal of the X series. These compounds are precipitated when a nickel salt is added to the solution of a nitrite of * Incidentally, this explains another fact noticed in studying the estimation of sodium as sodium cssium bismuthinitrite. The reagent used contained 30 grams of potassium nitrite, 3 grams of bismuth nitrate, and about 1.5 grams of cesium nitrate per 100 c.c., and produced a yellow precipitate of sodium cmium bismuthinitrite on the addition of traces of a sodium salt. When a reagent containing less potassium nitrite was made up, it was noticed that part of the cesium woulcl

Published on 01 January 1913. Downloaded by Cornell University Library 30/06/2017 07:42:59. gradually deposit as czesiuni bismuthinitrite, more being thus precipitated the lower the concentration of the potassium nitrite. Conversely, when the reagent contained more than 30 grams of potassium nitrite per 100 c.c., it could hold more cesium salt without deposition of cesium bismuthinitrite. There would appear to be an equi- lihrium between the aniounts formed 6f the very soluble potassium bismuthiuitrite and of the relatively insoluble ctxsium bismutliinitrite, the concentration of thc latter, when high concentrations of potassium nitrite were used, failing to reach the value necessary for precipitation. Theso facts seem to render unlikely the existence, even in solution, of a potassium cesium bismuthinitrite. j. Cssiuni may also be separated from rubidium by taking advantage of the greater insolubility of the cesium sodium bismuthinitrite. Thus, if a mixture of' caesium and rubidium nitrates is added to a concentrated solution of potassium nitrite containing bismuth, and then a sodium salt gradually, the cssium sodium bismuthinitrite will precipitate with a very small concentration of sodium, whilst the rubidium will remain in solution until a much greater concentration of sodium is attained. One of the authors has used this method satisfactorily for separating cmium from an impure rubidium chloride obtained in the extraction of lithium. The separation has not been iuvestigated quantitatively, and some rubidium nmains in solution. View Article Online

RALT, AND ARRAM : RISMUTHTNITRITES. 2113

auy of t,lieue metals, ill presence of bisluutll. The Y inetals do not appear to form any mixed compounds with nickel. The bismuthinitrites Tesemble the cobaltinitrih closely in formulae, colour, and solubility i’n many cases ; thus silver produces no precipitate with lithium or sodium cobaltinitrite, nor with sodium or lithium solutions containing bismuth (sodium and lithium bismuthinitrites), but on the addition of a salt of a metal of the X series the corresponding X-Ag cobaltinitrite or bismuthinitrite is precipitated as a yellow or red, crystalline powder. In preparing the bismuthinitrites, chlorides should be absent, or present in only very small amount ; otherwise bismuth oxychloride w ill precipitate. As the bismuthinitrites are all hydrolysed by water, in most cases rapidly, it is impossible, as a rule, to wash them. They are generally prepared by precipitation from a strong solution of a nitrite, and it is, in consequence, difficult to remove all traces of mother-liquor from the preparations. The most that can be done is to remove the mother liquor as completely as possible by the aid of the pump, and then to press the crystals on porous plates. The nearly dry crystals are then kept for some hours, under pressure, between sheets of filter paper. Fortunately, the salta are highly crystalline, which renders it easier to remove mother liquor, bat the difficulty of completely effecting this removal frequently shows itself slightly in the analyses; thus the thallous sodium salt, which is precipitated on adding a thallous salt to a strong solution of sodium nitrite containing bismuth, shows a rather too high percentage of sodium. This effect on the analytical results is hardly evident in the case of the less soluble bismuthinitrites, such as the silver salts, for these can be precipitated from a less concentrated Published on 01 January 1913. Downloaded by Cornell University Library 30/06/2017 07:42:59. mother liquor, but is chiefly seen in those which are the most soluble. The proportions of the different salts used in the preparation of the various bismuthinitrites may, as a rule, be considerably varied, and those given are simply the amounts which the authors have found to yield good results. In a few cases, such as that of the potassium sodium bismuthinitrite, the salt is formed with difficulty, and the proportions given cannot be much departed from. Frequently the method of preparation may be reversed; thus potassium lithium bismuthinitrite may be made either by adding lithium nitrate to a solution of potassium nitrite containing bismuth, or by adding potassium nitrate to the corresponding lithium nitrite solution. The nitrites used should be as pure and as free from alkali as possible. For convenience, the description of the various bismuthinitrites is divided into three parts. Part I describes the simple View Article Online

2114 BALL AND ARRAM : BISb.IUT€€INITRI'I'ES.

bismuthinitrites; Part 11 Clie iiiixed salts; aid Part 111 the salts containing nickel.

PART I. The Simple Bismuthinitrites. These salts form yellow or orange, hexagonal plates. They are less stable and more soluble, on the whole, than the mixed salts, from which they differ also in crystalline form. The potassium and rubidium salts are very unstable, as indeed are all the bismuthinitrites that contain water. In the case of msium, which is the most electropositive of the metals, the formula of the salt is Gs3Bi(NO,),,Bi(NO,),, and in the case of thallium, which is the least electropositive of the metals concerned, it is T13Bi(N02)6,T1N0,,H,0. It is a curious fact that the more strongly electropositive caesiuni should be able to combine with more bismuth nitrite, whereas the much less electropositive thallium should need an extra molecule of thallium nitrite in order to form its salt. The potassium and rubidium salts have the normal formulae K,Bi(NO,),,H,O and RbsBi(N0,),,2H,0, but it is possible that other hydrates of the two salts exist.

Potassium Bismut hiwitrit e, K,Bi (N 0,),,H20. The properties and composition of this salt were given iu a former paper. It was previously prepared by passing nitrous fumes into a suspension of bismuth hydroxide in concentrated aqueous potassium nitrite, but can also be obtained by adding

Published on 01 January 1913. Downloaded by Cornell University Library 30/06/2017 07:42:59. bismuth nitrate to a very concentrated aqueous solution of this salt. The solution of bismuth nitrate used throughout the work described in this paper was made by warming 50 grams of crystalline bismuth nitrate with 10 C.C. of fuming nitric acid and a little water. After dissolution of the salt, the liquid was made up to 100 C.C. with water. When some of this bismuth solution is added to four times its volume of an 80 per cent. solution of potassium nitrite, potassium bismuthinitrite is precipitated in fine, golden plates. Access of air must be avoided as much as possible, and the solution must not be cooled, for although this gives a larger yield of the salt, it leads to conta.mination with potassium nitrate. The salt should be collected by the aid of the pump, pressed on a porous plate, and dried finally by pressure between sheets of filter-paper. It crystallises in large, golden-yellow or orange plates, is unstable, View Article Online

BALL AND ABRAM : BISMUTHINITRITES. 2115

and cannot be kept, at the ordinary temperature, for more than a few days. Its properties and full analyses were given in the earlier paper.

Rubidium Bismuthartitrit e, Rb3Bi(N0,),,2H,O. This salt can best be prepared by adding bismuth nitrate solution to a concentrated solution of rubidium nitrite (see p. 2131). On adding 3 or 4 C.C. of the bismuth solution to 20 or 30 C.C. of 50 per cent. rubidium nitrite solution, the salt is rapidly precipitated. It is collected and dried as for the potassium salt, It is very unstable, even more so than the potassium salt, probably because it contains two inolecules of water. Other hydrates possibly exist. It forms orange-yellow plates, which on keeping become white, with evolution of oxides of nitrogen. It is considerably less soluble than the potassium salt. Found : Rb = 33.56 ; Bi = 26.74 ; NO, = 35.44, 35.75 ; qO(by difference) = 4.26. Rb,Bi(N0,),,2H20 requires Rb = 33-01; Bi = 26.79 ; NO,= 35-55 ; H,O=4*65 per cent.

Caesium BismuthirLitrite, Cs3Bi(NOz)s,Bi(N0,),. This substance can be obtained by adding bismuth nitrate solution to caesium nitrite solution (prepared from czesium sulphate and barium nitrite, p. 2130). It is much less soluble than the two preceding salts, so that less concentrated solutions may be used in its preparation. It is obtained by adding one or two drops of nitric acid, then

Published on 01 January 1913. Downloaded by Cornell University Library 30/06/2017 07:42:59. gradually 2 or 3 C.C. of bismuth nitrate solution to 20 C.C. of a 25 per cent. solution of caesium nitrite, shaking continually. A voluminous, yellow, crystalline precipitate is formed at once, which is collected after a few minutes, and dried as for the previous salts. It may also be prepared by adding czsium nitrate to a solution of potassium nitrite containing bismuth. To prepare it in this manner, 20 grams of the nitrite (as free from sodium as possible) are dissolved in about 40 C.C. of water; then about 7 C.C. of the bismuth nitrate solution are added, together with enough nitric acid to dissolve any precipitate (due to free alkali in the potassium nitrite) which may be produced. To the clear liquid 5 C.C. of a 10 per cent. solution of caesium nitrate are added, and it is kept in a closed vessel (provided with a Bunsen valve for the escape of oxidm of nitrogen) for several hours. Should any yellow precipitate be produced (cesium sodium bismuthinitrite, due to traces of sodium in the reagents used) it is collected, and about 20 C.C. more of the View Article Online

2116 BALT, AND ARRAM : RISMU'I'HINITRITES.

rzesiuin solution are added. The precipitate of czsiuni bisiuutlii- nitrite should be collected after several hours' keeping, It consists of golden to orange, hexagonal plates, closely resembling lead iodide. Contrary to expectation, the salt was found to give results on analysis agreeing with the formula @s$i(NO,),,Bi(NO,),, the percentages of cesium and of bismuth being about the same, and corresponding therefore with the atomic ratio 3CTs : 2Bi. Found : Cs = 33.43, 32.8 ; Bi = 33.80, 33.4 ; NO,= 33.0. Cs,Bi(N02)G,Bi(N0,)3 requires C's = 33-44 ; Bi = 33.87 ; NO,=33.7 per cent. On account of the flaky nature of the crystals it is difficult to free this salt entirely from its mother liquor. [I'hiall.iu?n Bisnzuthinitrite, T13Bi(N0,),,T1N0,,H20. For this preparation it is necessary to use a solution of thallous nitrite (the preparation of this salt is described in the following paper, p. 2131) containing 20 per cent. or more of the salt. To 50 c.2. of this orange-coloured solution (the solid thallous nitrite is red) are added a few drops of acetic acid,* and then gradually 2 to 3 C.C. of the bismuth solution. A golden-yellow, crystalline precipitate is formed, which must be collected and dried as quickly as possible. Should the substance tend to decompose and turn white during its preparation, this is due to deficiency of nitrite in the solution (TlNO, contains less than one-fifth of its weight of NO,), and may be remedied by the addition of a little 50 per cent. pobassium nitrite solution; too much of this salt will cause the precipitate to redissolve. The salt forms fine, golden-yellow, hexagonal plates, which have Published on 01 January 1913. Downloaded by Cornell University Library 30/06/2017 07:42:59. a high specific gravity. It is unstable, gradually becoming white. Found: T1=59*8; Bi=15.2. Tl,Bi(N0,),,T1N02,H,0 requires T1=59*8; Bi = 15.25 per cent. The numbers found for the bismuth and thallium agree very accurately therefore with the proportions required by the formula suggested. Tho same would, however, apply to the formula T13Bi(N0,),,T1N0, almost equally well; for in it the ratio of bismuth to thallium is the same) and the molecular weights are neasly the same. It is clear that a direct determination of the amount of nitrite present would settle which of the formuh is correct, but, unfortunately, we were unable to devise a method for the estimation of nitrite in the presence of thallium, which should at the same time distinguish between nitrous and nitric nitrogen. * Acetic acid rather than nitric ; for thallium acetate is much more soluble thau the nitrate, and therefore less likely to contaminate the precipitated compound. View Article Online

BALL AND ABRAM : BISMUTH1NITRITES. 2117

The method employed throughout this work for the estimation of nitrogen was to oxidise the nitrite to nitrate by means of an excess of acid permanganate at Oo, titrating the excess of permanganate with a ferrous salt. When a thallium salt was present, this was also oxidised to the thallic state, but always incompletely. Experi- ments made with thallous sulphate showed that at Oo, and under the conditions used, very nearly two-thirds of the thallium was oxidised to the thallic state (or, alternatively, that the whole of the thallium was oxidised to an intermediate stage of oxidation; we have not yet had an opportunity to test the point further). If, however, both thallium and a nitrite were present, the oxidation of the thallium was more complete than if thallium alone had been present. Thus, although it is impossible, in this way, to estimate exactly the amount of nitrite in those bismuthinitrites which contain thallium, yet by finding the amount of oxygen absorbed from permanganate it is possible to estimate the nitrite approximately. In the case of thallium bismuthinitrite, for example, if the formula were Tl,Bi(NO,)G,TINO,, the percentage amount of oxygen absorbed would be 11.75, on the assumption, never quite realised, that the thallium is completely oxidised to the thallic state. The percer,tage found, 12.3, was greater than this, so that this formula must obviously be incorrect. The alternative formula, Tl,Bi(NO,),,T1NO~,H,0, would, on the assumption of complete oxidation of the thallium, require 12.90 per cent. of absorbed oxygen. The amount of oxygen absorbed, representing that required for the complete oxidation of the nitrite plus that required for the partial oxidation of the thallium, therefore confirms the formula T1,Bi(NO,),,TINO,H,O.

Published on 01 January 1913. Downloaded by Cornell University Library 30/06/2017 07:42:59. In the case also of the other bismuthinitrites containing thallium, the amount of oxygen absorbed is given, instead of the amount of nitrite.

PART 11. Mixed Bismuthinitrites. These salts are, in general, less soluble and more stable than the simple bismuthinitrites. In consequence of their less solubility, they are more easily prepared. In crystalline form they differ from t-he plate-shaped crystals of the simple salts, forming crystals which appear to be octahedral. They vary in colour from the pale yellow of the aium silver salt to the red of the thallium silver compound. With the exception of those containing water of crystallisation, such as th_e lithium ammonium salt, they are relatively stable, and \OL. Clll. 7A View Article Online

2118 BALL AND ABRAM : BISMUI'EINITRITES.

can be kept unaltered for months. Some of them, such as the czsium sodium salt, remain unaltered at looo. They are, however, very liable to rapid decomposition under certain conditions ; for example, a large number of specimens of the various compounds which had been kept unaltered for weeks, in a store desiccator, were found to have all suffered decomposition, more or less complete, shortly after the introduction into the store vessel of a specimen of the potassium nickel salt. The decomposition appeared to be due to the slow liberation of oxides of nitrogen from the very unstable potassium nickel salt. There have been, however, other cases of the sudden decomposition of specimens that had remained for a long time unaltered, for which there were no obvious causes. On account of this instability, specimens of some of the salts were kept for some days in contact with a closed tube containing 5 milli- grams of radium bromide, but there was no evidence of decomposition, nor was anLy phosphorescence produced. Short exposures to Rontgen radiation also produced no perceptible effect. Light acted very slowly on the silver salts, producing a gradual blackening. For convenience, the mixed bismuthinitritea are divided into three groups: Group A containing those salts in which the metal represented by Y in the general formula X,YBi(NO& is lithium; group B, those in which Y is silver; group C, those in which Y is sodium.

Group A. Bismuthinitrites containing Lithium. ,4 mmonium Lithium Bzsm u thini tm't e, (NH,),LiBi (NO,),,H,O.

To about 16 C.C. of a 50 per cent. solution of lithium nitrite (the

Published on 01 January 1913. Downloaded by Cornell University Library 30/06/2017 07:42:59. preparation of this salt is described in the following paper, p. 2133) are added 4 C.C.of the bismuth nitrate solution. The, mixture is cooled to Oo, and about 3 grams of ammonium nitrate in 10 C.C. of water are added. After a few minutes, during which time the containing vessel is surrounded with ice, the yellow, crystalline precipitate is collected, dried on a porous plate, and then by pressure between sheets of filter-paper, as previously described. The salt consists of fine, bright yellow crystals, probably octa- hedra. It is unstable, and cannot be kept at the ordinary temperature for more, than a few days. Water hydrolyses it readily . Found : NH, = 6-70; Li = 1-23; Bi = 38.4 ; NO,= 50.1 ; H,O(by difference) = 3.57. (NH,),LiBi(NO,),,H,O requires NH4= 6.62 ; Li = 1.27 ; Bi = 38.2 ; NO,= 50.6 ; 30= 3.31 per cent. View Article Online

kAtL AND ABRAM : BISMUTEINITRITES. 2219

Po tassium Lit h.ium Bis mu t&ni trit e, K,LiBi (NO,) 6.

To about 50 C.C. of a 50 per cent. solution of potassium nitrite are added between 5 and 10 C.C. of the bismuth nitrate solution, and 3 or 4 grams of a soluble lithium salt, such as the nitrate or acetate, dissolved in about 20 C.C. of water (m previously mentioned, the chloride must not be used, as it would cause bismuth oxychloride to precipitate). A yellow precipitate of the salt rapidly settles, partly on the walls of the containing vessel, and after an hour or more this is collected and dried, as in the case of the salts previously described. The preparation may be reversed by adding the solution of a potassium salt to a solution of lithium nitrite containing bismuth. The salt forms bright yellow, apparently octahedral crystals, resembling the ammonium lithium compound, but quite stable. It is easily hydrolysed by water. Its specific gravity at 15O is 3-21. Found : K = 13-97; NO, = 48.3. ES_LiBi(N02), requires K= 13.74 ; NO,=48.5 per cent.

Rubidium Lithium Bismut?Liwitr.ite, Rb,LiBi(NO,),,

To 20 C.C. of 50 per cent. lithium nitrite solution are added about 10 C.C. of the bismuth nitrate solution, then 2 to 3 grams of rubidium nitrate dissolved in enough water to bring the total volume to about 60 C.C. The compound is precipitated rapidly, and may be collected after about an hour, and dried as previously described. The preparation may be reveraed by adding a soluble lithium salt to a solution of rubidium nitrite to which bismuth nitrate has been added.

Published on 01 January 1913. Downloaded by Cornell University Library 30/06/2017 07:42:59. The salt forms yellow, apparently octahedral crystals, very similar to the potassium lithium salt in all respects, but less soluble. It is a quite stable compound. Found : Rb = 26.8 ; Li =0*97 ; NO, = 41.34. Rb,LiBi(NO,), requires Rb = 25.8 ; Li = 1.05 ; NO, =41*71 per cent.

To 20 C.C. of 50 per cent. lithium nitrite solution are added 5 to 10 C.C. of bismuth nitrate solution, then 2 to 3 grams of caesium nitrate in enough water to bring the total volume to about 60 C.C. The yellow precipitate is collected after about an hour, and dried as previously described. The salt forms yellow crystals resembling those of the rubidium salt, but still less soluble. It is quite stable. Found : Ce = 35.0 ; Li = 1-00; NO, = 36.6. Cs,LiBi(NO& requires Cs = 35-1; Li = 0.92; NO,= 36.5 per cent. 7a2 View Article Online

2 120 BALL AND ABllAM : BISMUTEIINITRITES.

Thalli u m Lithium Bismu t hinit r i t e, T1,LiBi (NO,),. To 40 C.C. of a 25 per cent. solution of lithium nitrite in water about 4 C.C. of the bismuth nitrate solution are added, followed by 20 C.C. of a 10 per cent. solution of thallium nitrate or acetate, the addition being made gradually. The salt is collected after about an hour, and dried as previously described. The colour of this salt differs considerably from those of the other bismuthinitrites, as it is pale brown. It forms bright crystals, probably octahedral. It is quite stable, and rather insoluble. Found : T1= 45.4 ; Li = 0.84 ; Bi = 23.04. Tl,LiBi(NO,), requires T1= 45.4 ; Li = 0.77 ; Bi = 23.1 per cent. The percentage amount of oxygen absorbed by the salt froiii permanganate solution at Oo was 13.8 (see p. 2117); assuming that all the thallium was oxidised to the thallic state, it should be 14.2.

Group B. Bismuthinitrites containiny Sil uet-. These salts crystallise well, and, with the exception of the potassiumsilver compound, are stable. In the series ammonium- silver, potassium-silver, rubidium-silver, and caium-silver the solubility and the depth of colour decrease with increasing molecular weight: the ammonium silver salt is red, and the most soluble of the group, the potassium salt, is red inclining to orange, and less soluble, the rubidium-silver compound is orange and still less soluble, and the czsium-silver salt is yellow and very insoluble. The thallium--silver salt is also of very low solubility, but is red. The specific gravities of these compounds also increase

Published on 01 January 1913. Downloaded by Cornell University Library 30/06/2017 07:42:59. with increasing molecular weight, and have the following values at 15-16O: Ammonium-silver salt. Found, 3.05, 3.06. Mean, 3.055. Potassium-silver ,, ,, 3.32, 3.34, 3.33. Mean, 3.33. Rubidium-silver ,, ,, 3-66, 3.68, 3-67. Mean, 3.67.

Czsium-silv er 9, ,, 3.883, 3.875. Mean, 3.88. Thallium-silver ,, ,, 4.860, 4.874. Mean, 4.87.

,4mmonium &Ever Bismuthiizitt-ite, (NH4),AgBi(N0,),. This salt can be prepared by adding a solution ol silver nitrate to a solution of ammonium nitrite containing bismuth nitrate, but as acidified solutions of a.mmonium nitrite are very unstable it is more convenient to add first bismuth nitrate, and then silver nitrate, to a solution of sodium nitrite in water. This mixture does not yield a precipitate of sodium--silver salt, as both these metals belong to the Y group, as previously explained. On now View Article Online

BAIJL AND ADRAM : BISMUTHINITRITES. 2121

adding a solution of ammonium nitrate, a red, crystalline precipitate of the ammonium-silver salt will fall. To 25 C.C. of a 50 per cent. sodium nitrite sqlution are added 5 C.C. of the bismuth nitrate solution, then with constant shaking about 10 C.C. of a 10 per cent. solution of silver nitrate. The white precipitate of silver nitrite at first produced will dissolve (silver nitrite being soluble in concentrated solutions of the nitrites of the alkali metals), but there will probably remain a slight permanent precipitate of silver chloride, due to chloride almost always present in the reagents. Should this be the case, it is removed by filtration, and about 2 grams of ammonium nitrate dissolved in a very little water are added. A red, crystalline substance will be precipitated, which must be collected after a few minutes. The liquid should be kept cold throughout, and the filtration accomplished as quickly as possible. The substance is dried, as in the case of the former salts. The substance forms fine, red crystals, apparently octahedral. It is not particularly insoluble, and the crystals can be obtained fairly large. It is quite stable at the ordinary temperature, specimens having remained unaltered after several months. Water hydrolyses it rapidly. When quite dry it explodes very feebly on being rubbed in a mortar, as also do some of the other bismuthinitrites containing ammonium. Found: Ag=17-2; NH,=5*4; NO,=43.7. (NH,),AgBi(NO,), requires Ag= 17.2; NH, = 5-75; NO,=43*9 per cent.

Po tassiu rn Silver Bism u t luini t rit e, K,AgB i (NO,), .

Published on 01 January 1913. Downloaded by Cornell University Library 30/06/2017 07:42:59. To 30 C.C.of 50 per cent. potassium nitrite solution are added about 10 C.C. of the bismuth nitrate solution, then silver nitrate (say, 2 per cent. solution) until all chloride that may be present is precipitated, and the orange-red potassium-silver bismuthinitrite begins to fall. The mixture is filtered, and to the filtrate about 70 C.C. more of the silver nitrate solution are added gradually and with constant shaking. The salt is collected, and dried as for the other salts. By using a fairly dilute silver solution the substance is obtained in larger crystals. More concentrated solutions may be used, but in that case the salt will be precipitated in minute crystals. The Salk forms orangered, apparently octahedral crystals. It resembles the ammonium-silver salt closely, but is less soluble. For some reason, which the authors have, so far, been unable to explain, this salt appears to be less stable than the other mixed silver bismuthinitrites. One would expect it to be much more View Article Online

2122 BALL AND ABRAM : BISMUTHINITRITES.

stable than the ammonium salt, but the reverse is the case, and the preparations hitherto made, about seven in number, have all gradually decomposed and become white on keeping, whereas preparations of the other mixed silver bismuthinitrites, made at the same time and kept under similar conditions, have remained unaltered. Found: Ag,=16.2; NO,=41*2. KzAgBi(NO,), requires Ag= 16.1 ; N02=41.2 per cent.

Rzzb idi'um SiE v er Bismu t 11 inz'trit e, Rb,AgBi(NO,),. This salt may be obtained by adding bismuth nitrate, and then silver nitrate, to a solution of rubidium nitrite (the preparation of this salt is described in the following paper, p. 2131), but the use of this salt may be avoided in the following manner. If bismuth nitrate, and then rubidium nitrate, are added to a solution of sodium nitrite, the result is the precipitation of rubidium sodium bismuthinitrite. If, however, silver nitrate be added before the rubidium salt, this precipitate will be replaced by an orange- yellow one of the rubidium-dver salt. The amount of rubidium nitrate must be limited, so that there is always enough silver present to for= the rubidium-silver compound, to the exclusion of the more soluble rubidium sodium salt. To 15 grams of pure sodium nitrite (free from potassium) water is added until the volume of the solution is about 80 C.C. To this are added about 5 C.C. of the bismuth nitrate, then gradually, and with shitking, about 15 C.C. of 10 per cent. silver nitrak solution. Should any silver chloride form, it must be filtered off, Finally, about 1 gram ol rubidium nitrate dissolved in about 10 C.C. of Published on 01 January 1913. Downloaded by Cornell University Library 30/06/2017 07:42:59. water is added. After allowing to remain for a short time, the precipitate is collected and dried as previously described. The salt forms orange-yellow, probably octahedral crystals. It is only very sparingly soluble, and not very rapidly hydrolysed by water. Found : Ag = 14.2 ; Rb = 22.3 ; NO, = 36.2. Rb,AgBi(NO,), requires Ag = 14.14 ; Rb = 22.4 ; NO,=36 2 per cent.

Caesium Sil uer Bcismuthinitrite, Cs,AgBi(NO,),. Although this compound is the most. insoluble of all the bismuthinitrites, it is one of the most difficult to obtain in the pure state. It cannot be obtained pure by adding bismuth nitrate and silver nitrate to a solution of caium nitrite, as when thus prepared it is contaminated with the insoluble msium bismuthinitrite. An View Article Online

BALL AND ABRAM : BISMUTEINITRI'I'ES. 2123

attempt was made to prepare it by adding bismuth nitrate and caesium nitrate to a solution of potassium nitrite, then gradually adding silver nitrate in smaller quantity than would be required to precipitate the whole of the caium as msium-silver salt. It was thought that this might yield a pure product, the czsium-silver salt being formed exclusively, as it is much less soluble than the potassium-silver compound. This was not the case, as determina- tions of the nitrite and of the silver showed that the product contained several parts per cent. of the potassium-silver salt (Found, NO, = 34.5 ; Cs,AgBi(NO,), requires NO, = 32.2 per cent.). Better results may be obtained by effecting the precipitation in a more dilute solution of potassium nitrit,q, but the most satisfactory method is to use a dilute solution of sodium nitrite, conducting the preparation as in the case of the preceding salt, rubidium-silver bismuthinitrite. Although msium-sodium bismuthinitrite is an insoluble sa!t, the czesium-silver compound is still less soluble, and precipitates preferentially. The quantities to be used and the method of preparation are exactly as described for the rubidium- silver salt. Found : NO, = 32.4. Cs,AgBi(NO,), requires NO,= 32.2 per cent. The salt forms pale yellow, very minute crystals, which are very insoluble, and decomposed only slowly by water. It blackens slowly on expcxsure to light, but in absence of light appears to be stable. Thallium Silver Bismuthinitrite, T1,AgBi(No2),. This salt cannot readily be obtained by the addition of bismuth nitrate and silver nitrate to thallium nitrite solution, as thallium bismuthinitrite itself is an insoluble compound. It can, however,

Published on 01 January 1913. Downloaded by Cornell University Library 30/06/2017 07:42:59. easily be prepared in a way exactly similar to that described for the rubidium-silver and czsium-silver salb, as it is very much less soluble than the thalliumsodium salt. To 15 grams of pure sodium nitrite (free from potassium), water is added until the volurne of the solution is about 60 c.c., then 5 C.C. of the bismuth nitrate solution, 15 C.C. of 10 per cent. silver nitrate solution, and a few drops of dilute acetic acid are added. The mixture is filtered, if necessary, to remove traces of silver chloride, and to the clear filtrate 20 C.C. of a 5 per cent. solution of thallium nitrate are gradually added. The red precipitate is collected after a few minutes, and dried as in the previous cases. The salt forms a red, finely-divided, crystalline powder, which is very insoluble, and only slowly decomposed by water. It appears to be quite stable. Found : Ag = 10.8 ; TI = 40.4. Tl,AgBi(N0,)6 requires Ag = 10.8 ; T1= 40-8 per cent. View Article Online

2124 BALL AND ABRAM : BISMUTHINI’I RITES.

Group C. Bismuthinitrites contahing Sodium. These are all bright yellow, crystalline salts, and they differ very much in their solubilities. The ammonium--sodium salt is very soluble, and can only be obtained from concentrated solutions; the potassium salt is extremely soluble, can only be prepared from solutions of definite concentration, and has probably not yet been obtained in a pure state; the rubidium-sodium compound is of only sparing solubility, and the cesium-sodium salt is very insoluble. The thallium salt is not particularly soluble, and can easily be prepared in the pure state. The ammonium-sodium, rubidiumsodium, and casiumsodium salts have, as previously mentioned, been described in earlier papers, but some further methods of preparation, etc., are included here.

Ammonium Sodium Bismzlt hinitrit e. As previously prepared, this salt was obtained by dissolviiig solid bismuth nitrate in a cold, very concentrated solution of ammonium nitrate, and pouring the resulting liquid into a cold, nearly satur- ated solution of sodium nitrite. Analyses of the bright yellow powder obtained pointed to the formula (NH,),NaBi(NO,),. Sub- sequently, it has been prepared by adding a concentrated solution of ammonium nitrate to a concentrated solution of sodium nitrite containing bismuth. In order to prepare it in this manner, about 16 grams of the nitrite are dissolved in the least possible amount of water at the ordinary temperature, 5 C.C. of the bismuth nitrate solution are added, the mixture cooled with ice, and the compound Published on 01 January 1913. Downloaded by Cornell University Library 30/06/2017 07:42:59. precipitated by the addition of a previously-cooled solution of 4 grams of ammonium nitrate in about 5 C.C. of water. The yellow precipitate is collected after a few minutes, and dried as previousry described. It is identical in appearance with the product obtained by the former method, and under the microscope appears homogeneous. On analysis, however, the percentage of ammonium was found to be 6.04 and that of sodium 5-17. The ratio between these numbers ia 1.17, and that between 3(NH,) and 2Na is 1.176, pointing to the formula 9(NH,),6Na,5Bi(N02), for the salt prepared in this way. This formula, would require NH,=5.97 and Na=5.07 per cent. (compare the case of the czesium-sodium salt, given below). This and the succeeding salt can only be prepared from such concentrated solutions that it is very difficult to remove all mother liquor and ensure that a pure substance is being dealt with. View Article Online

BALL AND ARRAM : BISMUTHINITRITES. 2125

Potassium Sodium Bisniuthinitrite. This salt was at first thought to be incapable of existence, as on adding bismuth nitrate to a very concentrated solution of equal parts of tlhe mixed nitrites of sodium and potassium, the substance deposited consisted of orange-yellow plates of potassium bismuthinitrite. It was found, however, that if a concentrated solution of potassium nitrite was gradually added to a concentrated solution of sodium nitrite containing bismuth, when a cetrain amount of the potassium salt had been added, bright yellow, octahedral crystals deposited, containing occasionally a few much larger, orange- colourod plates of potassium bismuthinitrite. These, if present, could be removed and a homogeneous product obtained. To 20 grams of sodium nitrite are added 20 C.C. of water and 5 C.C. of the bismuth nitrate solution. The mixture is cooled to Oo, and any sodium nitrate that may deposit is filtered off. Into this liquid is poured a solution of 5 grams of potassium nitrite in about 5 C.C. of water, and the whole cooled to Oo. Should no precipitate form, a further small addition of potassiuni nitrite is made. After about half an hour the very finely-divided, yellow precipitate is collected, and as much as possible of the remaining mother liquor carefully removed by pressure on a porous plate. The salt is a finely-divided powder, consisting of very small, bright yellow crystals, probably octahedral. The substance is unstable, and water at once hydrolyses it, although very small quantities of water produce a yellow solution. On analysis the percentage of potassium found wae 13.4, whilst the amount required by the formula K,NaBi(NO,), is also 13-4. The percentage of NO, found was, however, much below the

Published on 01 January 1913. Downloaded by Cornell University Library 30/06/2017 07:42:59. required quantity, being 43.6 as against 47.2. This may have been partly due to decomposition, but the formula K,NaBi(NO,), can only be regarded, from these results, as probable, but not certain.

Rubidium Sodium Bismuthinitrite, Rb2NaBi(NO&. This salt has been previously described by one of the authors, and it is sufficient to mention here that it is best prepared as a bright yellow, crystalline precipitate by adding rubidium nitrate to a 15 per cent. solution of sodium nitrite containing bismuth. It is also formed in the reverse manner from rubidium nitrite by adding first bismuth nitrate, then sodium nitrite.

Caesium Sodium Bismu t hinitrit e. The properties of this salt, and its use as a means of determining sodium gravimetrically, have been described by one of t,he present View Article Online

2126 BALL AND ABRAM : RZSMUTHINITRITES.

authors in a former paper, and the salt is also referred to on p. 2112 of this paper. Like the ammonium-sodium compound, its composition appears to vary somewhat with the method of preparation. When prepared by adding a sodium salt to a solution of potassium nitrite containing bismuth and cmium, the ratio between the czeesium and sodium in the salt was found to be 3Cs:2Na, pointing to the formula 9C’sN02,6NaN0,,5Bi(N02)3, but a sample made in absence of potassium nitrite contained an amount of msium corresponding with the normal formula : CqN&i(NO,),.

Thallium Sodium Bismuthinitrite, T1,NaBi(N02),,H20. To 25 C.C. of a 50 per cent. solution of sodium nitrite are added 5 C.C. of the bismuth nitrate solution, and then 1 or 2 grams of thallium nitrate or acetate in about 20 C.C. of water. The bright yellow crystals are collected after about an hour, and dried as previously described. The salt forms fairly large, honey-yellow crystals, which are moderately stable on keeping, but are decomposed gradually when heated to looo. Found : T1= 43.86 ; Na= 2.82 ; Bi = 22-36. TI~aBi(NO,),,H,O requires T1= 43.73 ; Na = 2-47 ; Bi=22*30 per cent. Another specimen, prepared in a very similar manner, did not contain any water, and was quite stable.

PART111. B ism u t h i ni t r a t e s c o n t a i n i n g N i c k e I.

Published on 01 January 1913. Downloaded by Cornell University Library 30/06/2017 07:42:59. When nickel nitrate is added to solutions of the nitrites of sodium or of lithium containing bismuth, no precipitate is formed. On thO addition of a salt of any of the metals of the X class a brownish-yellow or brownish-red precipitate of a mixed bismuthinitrite of the metal X and nickel is formed. These substances deposit slowly, and are micro-crystalline. They are produced with very small amounts of nickel. Owing to lack of time, these compounds were not fully investigated, but rather complex ratios were found on analysis between the metal X and nickel contained in them. Possibly this may be due to the substances consisting of mixtures of closely similar compounds containing a metal X and nickel in different ratios. Ammonium Nickel Bismuthinitrite. To 40 C.C. of a 50 per cent. solution of sodium nitrite are added 10 C.C. of the bismuth nitrate solution. and then to the mixture View Article Online

BALT, AND ABRAM : BISMUTHINITRITES. 2127

cooled with ice a solution of 5 grams of ammonium nitrate and 2 grams of nickel nitrate in 20 C.C. of water. After a few minutes the reddish-yellow precipitate is collected and dried in the usual way. The substance forms a yellowish-brown, micro-crystalline powder. It is very unstable, slowly evolving oxides of nitrogen, and water decomposes it immediately. It has not been possible to assign a definite formula to the substance, as the composition of different specimens varied considerably. Found: NH,=6.05, 6-45; Ni=4.16, 3.59; Bi=32-9; NO,=50*0 per cent. The substance also contained some water.

Yotassiurn Nick el Bismu t hini tri t e .

To 40 C.C. of a 50 per cent. solution of potassium nitrite are added 5 C.C.of the bismuth nitrate solution, and then about a gram of nickel nitrate in 10 C.C. of water. Much of the precipitate deposits on the walls of the vessel. It is collected and dried in the usual manner. This salt is a yellowish-brown, micro-crystalline powder, very similar to the nickel-ammonium salt, and, like it, very unstable. As the salt decomposed gradually while being dried, giving off oxides of nitrogen, the value obtained for the (NO,) is too low. The ratio between the bismuth and nickel in the salt is not affected by this decomposition. It was found to be 7.39, whereas the ratio 2Bi : Ni is 7.09. Found : Ni = 4-25; Bi = 31.4 ; NO, = 43.7 per cent.

Published on 01 January 1913. Downloaded by Cornell University Library 30/06/2017 07:42:59. The ccmpound approximates to the composition R,Ni,2Bi(NO2),, plus about 6 molecules of water.

This is prepared in a similar manner to the corresponding potassium compound, nickel nitrate, and then bismuth nitrate being added to a solution of rubidium nitrite. It is a reddish-yellow powder consisting of minute crystals, which are less soluble and much more stable than the potassium salt. As this salt could be kept for some time, it was analysed fully, and the results are, no doubt, mor0 correct than those obtained with the two previous salts which are difficult to analyse on account of their instability. Found : Rb = 29.0 ; Ni = 2.75 ; Bi = 28.0 ; NO,= 37.14 ; H,O(by difference) = 3.11. View Article Online

2128 BALL AND ABRAM : RISMUTHINITRITES.

The formula which corresponds most nearly with these numbers is Rb7Ni3{I3i(NO2),),4H20, for the ratio of Rb to Ni from the above numbers is 10.5, whilst the atomic ratio 7Rb : Ni is 10.2. This formula requires Rb = 27.4 ; Ni = 2.69 ; Bi = 28.6 ; NO2= 38.0 ; H20= 3-30 per cent. The NO,/Bi ratio is 37.14/28*0=1*326, whilst the ratio 6NO,/Bi= 276/208= 1.327. Caesium Nickel Bismuthinitrite. This is prepared in the same manner as the rubidium salt (the nickel nitrate must be added before the bismuth nitrate, otherwise cmium bismuthinitrite will precipitate), and resembles it closely in appearance and properties. Found: Cs=36-6; NO,=32*6. These figures would indicate a formula similar to that of the rubidiu-nickel salt, for the ratio of Cs to NO,=36.6/32.6 = 1.12, whilst that of 7Cs to 18N02, required by the formula Cs7Ni3{ %(NO,),), is 1.12. The numbers agree most closely with the formula Cs7Ni3{ Bi(NO,),} ,6H20, which would require Cs=36.5; NO,=32.5 per cent. Thallium Nickel Bismuthinitrite.

Fifteen grams of sodium nitrite are dissolved in about 60 C.C. of water, and 5 C.C. of the bismuth nitrate solution are added, as well as a few drops of acetic acid and 1 or 2 grams of nickel nitrate. A solution of 2 grams of thallium nitrate in about 40 C.C.of water is now added, when ths substance is precipitated at once as a fine, red powder. This is collected after an hour or so, and dried as

Published on 01 January 1913. Downloaded by Cornell University Library 30/06/2017 07:42:59. previously described. The salt is a reddish-brown, crystalline powder, which is insoluble and decomposed slowly by water. It appears to be quite stable. Found : T1= 46.54 ; Ni = 3-23. T14Ni,2Bi(N0,), requires T1= 44-28; Ni = 3.13 per cent. Methods of AnaZys.is. In order to estimate the bismuth in these compounds the nitrite present was expelled by boiling with hydrochloric acid, the bismuth then precipitated with hydrogen sulphide, the sulphide dissolved in nitric acid, and the solution precipitated with ammonium carbonate, the precipitate being ignited and weighed as the trioxide. Bismuth and silver were separated by precipitation of the silver with a slight excess of hydrochloric acid in the presence of much nitric acid. View Article Online

BALL AND ABRAM : BISMUTHINITRITES. 2129 Thallium and bismuth were separated by dissolving the salt in dilute hydrochloric or sulphuric acid, and then precipitating the bismuth as sulphide (the precipitate may contain a little thallium, which was separated by the method described by aookes '( Select Methods."). In the case of thallous silver bismuthinitrite, where the three metals are present together, the silver and bismuth were co-precipitated as sulphides from a solution in dilute sulphuric acid, and then separated by dissolving the sulphides in nitric acid (the nitric acid used in this case was more concentrated than that used for dissolution of bismuth sulphide alone, as the silver sulphide dissolved with difficulty) and precipitating the silver as chloride. The thallium was determined generally by oxidation with deci- normal permaaganate, at a little below looo, in the presence of hydrochloric acid, the thallium solution having been previously boiled with sulphurous acid to ensure the absence of thallic salts

(Crookes, " Select. Methods "). Thallium was also, in a few cases, determined as thallous iodide. In the analysis of thallium nickel bismuthinitrite the salt was boiled with hydrochloric acid and much water to avoid precipitation of thallous chloride; the bismuth separated as sulphide, and the filtrate containing the nickel and thallium divided into two equal Fortions. To one of these was added some sulphurous acid, and the liquid boiled for some time. On titration with permanganate, 46.52 parts per cent. of thallium were found. The nickel and thallium in the other portion were separated by sodium carbonate, the thallium remaining in solution. After removal of the nickel this portion was treated exactly as the former one, and gave 46.55 per cent. of thallium. The nickel present, therefore, did not interfere with the estimation of the thallium with perman- Published on 01 January 1913. Downloaded by Cornell University Library 30/06/2017 07:42:59. ganate. Nickel was estimated either as the dimethylglyoxime compound or as the monoxide after precipitation as peroxide. It was separated from the alkalis either by ammonium sulphide or dimethylglyoxime. After the heavy metals had been removed by the methods indi- cated, cesium, rubidium, and potassium were estimated as platini- chlorides or as sulphates, lithium as sulphate, sodium as sulphate or as sodium czsium bismuthinitrite. When two of the alkali metals were present at the same time, such as msium and lithium, the czesium was estimated as platinichloride in one portion, and the cmium and lithium together as sulphates in another portion, the lithium being then determined by difference. The determination of ammonium in these compounds must be made very carefully, or the results will be too low, presumably owing to interaction between the NH, and NO, groups. A weighed quantity of %hesubstance is dropped into coEd fairly dilute sodium View Article Online

2130 BALL AND ABRAM: THE NITRITES OF THALLfUM',

hydroxide solution, and the ammonia then distilled off in a current of steam. Nitrite was determined by oxidation with permanganate in the following manner : Distilled water acidified with sulpburic acid so as to contain about 1 per cent. of the acid was well boiled to expel air, and then cooled to Oo. A bottle holding about half a iitre was nearly filled with the cooled acidified water, and enough permanganate added to give the liquid a just perceptible pink tint. About one and a-half times the required quantity of N/10-permanganate was now run into the bottle, and a weighed amount of the substance, not much greater than 0.1 gram, added in a small tube. The bottle was well shaken, and when all solid particles had disappeared, the excess of permanganate was estimated by means of a ferrous sulphate solution. The determination has to be made with care, but gives very satisfactory results unless the compound also contains thallium, in which case, as has been previously mentioiied in this paper (see p. 2117>, the thallium is ahpartly oxidised.

The thanks of the authors are due to the Chemical Society for a grant from the Research Fund, which has defrayed the greater part of the cost of the above work, and to the managers of the Davy Faraday Research Laboratory for permission to conduct the work there. THE DAVY-FA~UDAYEESEARCH LABOKATORT, ALDEMARLE ST., w. Published on 01 January 1913. Downloaded by Cornell University Library 30/06/2017 07:42:59.