摘要:

OF CLOSED CARBON-CHAINS. 215 XXL- The Synthetical Formation of Closed Carbon-chains. Part V. Experiments on the Synthesis of Heptamethylene-derivatives. By PAUL C. FREER Ph.D. and W. H. PERKIN jun. Ph.D. WHEN ethylic malonate is treated with methyltetramethylene dibro-mide the only product of the reaction is ethylic methylpentamethyl-enedicarboxylate but when methylpentamethylene dibromide is used, besides ethylic methylhexamethylenedicarboxylate a considerable quantity of a second substance is formed which is the product of the action of 1 mol. of methylpentamethylene dibromide on 2 mols. of ethylic malonate thus :-2(COOC,H5),CHNa + CH,-CHBr*[CH2],*CH2Br = (COO C,H5 )&H*CH (C H3)*[CH2],*CH ( COOC,H5)2 + 2NaBr. This ethereal salt for which we propose the name ethylic isohep-tane-wzwz-tetracarboxylate is converted by hydrolysis into the corre 2 16 FREER AND PERKIN SYNTHETICAL FORMATION sponding acid and this on heating t o 200" is split up into carbonic anhydride and a new acid of the succinic series (methylazelaic acid)-(C 0 OH) ,CH*CH ( CH3) *[ C H,] 1' C H( C 0 OH) 2 = Isoheptanetetracarboxylic acid.COOH*CH,.CH(CH3)*[ CH,],*COOH + 2C0,. Methy lazelaic acid. Ethylic isoheptanetetracarboxylate was for these researches of special importance because as will be seen from a glance a t its formula, it contains two hydrogen-atoms which from their position with regard to the carb-ethoxyl-groups are capable of being displaced by sodium, forming a disodium compound of the following formula :-(COOC,H,),CNa~CH(CH,)~[CH,l,CNa(COOC,H,)2.This disodium compound when treated with iodine or bromine should be converted into ethylic methylheptamethylenetetracarbo-xylate,* thus :-( C 0 0 C,H,) ,CNa-CH ( CH,) - [ CH,] 4- CNa( C 0 0 C2H5) + Br = CH2.C H ( C H3) -4 ( C 0 0 C2H5) 2 C H d I + 2NaBr. 'CH?-CH,--C (COOC,H,), Methylheptamethylenetetracarboxylate (1 1 2 2 ) . This ethylic salt on hydrolysis would then yield the corresponding t,etracarboxylic acid which on heating to 200" would be converted into methylheptamethylenedicarboxylic acid (1 2) and carbonic anhydride, thus :-CH,.CH( CH,)-C( COOH), - CH2( I \CH,-CH,--C( COOH), Methylheptamethylenetetracarboxylic acid (3 1 1 2 2). C H,* CH ( C H3) -CH* C 0 O H CH,/ I + 2 c 0 . \cH,-cH -CH.CO OH MethylheptamethylenedicaPboxylic acid (3 1 2).TO prove that such a change had taken place it would be only necessary t o show (1) that the resulting methylheptamethylenedicarb-oxylic acid differed in its properties from the methylazelaic acid produced by the hydrolysis of ethylic isoheptanetetracarboxylate * Compare the formation of ethylic teti*amethylenetetracarboxylate from ethylic but~~e-wzw,-tetracarboxylate (Trans. 51 IS) also of ethylic pentamethylene-tetracarboxylate from ethylic pentane-wzw2-tetracmboxylate (Trane. 51 240) OF CLOSED CARBOS-C,HAINS. 217 before its treatment with sodiiim and bromine ; and (2) that the re-sulting acid was capable of forming an anhydride thus proving that the two carboxyl-groups which at first were separated by seven carbon-atoms were now in the ortho-position.Two careful experiments were tried with the object of carrying out this synthesis (bromine being used) but although from the decolori-sation of every drop of bromine as it came in contact with the sodium compound it seemed as though the decomposition had taken place in the way desired on examining the product it was found that no heptamethylene-ring had been formed. The resulting ethereal salt was a mixture containing a considerable quantity of reqenerated ethylic isoheptanetetracarboxylate and some very high-boiling complex products. It is impossible a t the pre-sent stage of these experiments t o explain what really takes place in a reaction of this kind ;* the only clear point is that as far as we could tell no trace of a heptamethylene-derivative is produced.This research does not of course prove that a closed carbon-chain of seven atoms cannot be formed ; but it would nevertheless appear to throw doubt on the existence of a chain of these dimensions. Experiments are being carried on the results of which it is hoped will clearly settle this important point. E thy lie Isohept artetetracarbox y late, (C 0 0 CZH,) ZC H a CH (CH,). [ C H?]4* C H (CO 0 CZH,) . When the product of the action of methylpentamethylene dibromide on ethylic malonate is distilled as described in the previous paper (p. 206) ethylic me thylhexamethylenedicarboxylate passes over, whilst a thick yellowish oil remains behind consisting of crude ethylic isoheptanetetracarboxylate. If this crude residue be submitted to fractional distillation under a pressure of 60 mm.nearly the whole of it will pass over without the slightest decomposition between 265" and 28S0 and on once or twice refractioning the oil is easily obtained pure boiling at 273-276". Analysis. 0.1808 gram substance gave 0.3970 gram GO and 0.1408 gxam HZO. Theory. C 2 0 ~ 3 4 0 8 . Found. C 59-70 per cent. 59.83 per cent. H 8-45 , 8.65 ,, 0 31.84 , 31.52 ,, * Compare for similar experiments Kipping (this vol. pp. 22 and 23). POL. LIII. 218 FREER AND PPERKIN SYNTHETICAL FORMATIOX E thylic isoheptanetetracsrboxylate is a thick colourless syrup boiling at 273-276" (60 mm.). When dissolvedin ether and treated with 2 mols. of sodic ethylate, a yellowish-whit,e sodium compound is precipitated. Sereral attempts were made to nnalyse this but it was found to be impracticable, owing t o its being so soluble in ether and so bygroscopic.Methylaxe laic Acid C 0 OH*CH,*CH (CH,)* [ CHz] 5* C 0 OH. When treated with alcoholic potash ethylic isoheptanetetracarb-oxylate is readily hydrolysed. I n carrying out this hydrolysis, 20 grams of the pure ethereal salt was mixed with a solution of 20 grams of pure potash dissolved in pure methyl alcohol and boiled in a flask connected with a reflux apparatus for about six hours. The excess of alcohol was then distilled off the residue dissolved in water, the resulting colourless solution neutralised with dilute sulphuric acid and evaporated on a water-bath till quite free from alcohol and ether. Excess of sulphuric acid was then added and the isoheptane-tetracarboxylic acid extracted at least 20 times with pure ether.The ethereal solution after drying over calcic chloride and evaporating, deposited the free acid as a thick colourless syrup which was not analysed b u t a t once converted into methylazelaic acid. I n order to do this the flask containing the isoheptanetefracarb-oxylic acid was heated in a metal bath slowly to 200" and kept a t that temperature until the evolution of carbonic anhydride had entirely ceased. The resulting brownish-coloured oil was dissolved in a little water boiled with a small quantity of animal CharcoaI, aud the almost colourless solution evaporated on a water-bath. As however the residue even after standing for some days over sulphuric acid in a vacuum showed no signs of crystallisation it was further purified by conversion into the ethereal salt.For this purpose the crude substance was dissolved in pure ethyl alcohol, saturated with hydrogen chloride and allowed to stand for some hours. Water was then added the ethereal salt extracted with ether washed with dilute carbonate of soda solution the ether distilled off and the residue fractioned under reduced pressure (100 mm.). In this way it was easily obtained pure as a thick oil boiling at 212-215" (100 mm.). Analysis. 0.1655 gram substance gave 0.1500 gram H,O and 0.3936 gram GO,. Cl'IH260-I. Found. Theory. 65.11 per cent. C . . . . . . . . H . . . . . . 10-08 , 10.07 ,, 0 . . . . 24-81 , 25.04 ,, 64.89 per cent OF CLOSED CARBON-CHAINS.219 The ethylic salt of methylazelaic acid is a colourless liquid of peculiar odour and boils at 212-215" under a pressure of 100 mm. It is isomeric with ethylic sebate which boils at 307-308" under ordinary pressures. In order to obtain methylazelaic acid the ethereal salt was gently boiled with a slight excess of a solution of potash in pure methyl alcohol f o r two hours the excess of alcohol distilled off the product dis-solved in water and the solution evaporated nearly to dryness. The residue was then dissolved in a little water acidified with dilute sulphuric acid and extracted two or three times with pure ether. The ethereal solution after beine; carefully dried over calcic chloride was evaporated and in this way the new acid was obtained as a colourless syrup; this after standing for some days over sulphuric acid in a vacuum solidified to a hard cake of crystals.These were freed from a small quantity of oily mother-liquor by spreading out on a porous plate and the acid was thus obtained quite colourless. After drying over sulphuric acid in a vacuum it gave the following numbers on analysis :-0.1334 gram substance gave 0.1070 gram H20 and 0.2908 gram coz. Theory. C10H1804. Found. C 59.41 per cent. 59.44 per cent. 0 31.68 ? 31-65 ,, H 8.91 , 8.91 ,) Methylazelaic acid thus prepared melts at 43-44' and when heated in small quantities in a test-tube appears to distil without decomposition. It is fairly easily soluble in boiling water and on cooling the liquid becomes milky owing t o the separation of the acid in oily drops.It is readily soluble in ether alcohol benzene and chloroform but cannot be recrystallised from any of these solvents, as on evaporating its solutions it is invariably obtained as a syrup which only crystallises again after standing for some time over sul-pliuric acid in a vacuum. Methylazelaic acid is isomeric with sebacic acid (m. p. 197") and heptylmalonic acid (m. p. 97-98"}. Balts of Methylazelaic Acid. Silver #aZt.-To prepare this salt the pure acid was dissolved in a little dilute ammonia the solution allowed to stand over sulphnric acid in a vacuum till free from excess of ammonia and the silver salt precipitated by the addition of nitrate of silver. It is thus obtained as a white amorphous mass which after collecting on a filter washing Q 220 FREER AND PERKIN SYNTHETICAL FORMATION well with water and drying over sulphuric acid in a vacuum gave the following numbers on analysis :-0.2380 gram substance gave 0.0833 gram H20 0.2507 gram CO,, and 0.1233 gram Ag.Theory. C10%04Ag2. Found. C 28-84 per cent. 28.80 per cent. H 3.84 , 3-89 ,> 0 15-38 , 15.51 ,, Ag 51.92 , 51-80 ,, 'If a neutral solution of the ammonium salt be treated with various reagents it behaves in the following way :-Calcic Chloride. Cupric Sulphate . . Lead Acetate Zinc Sulphate Bzric Chloride hfagnesic Sulphate Cobalt Nitrate Nickel Sulphate . . Added to a cold strong solution of the am-monium salt gives no precipitate ; on warm-ing however the calcium salt separates as a white curdy precipitate which when examined under the microscope presents very much the appearance of potato-starch.Gives a bluish-green precipitate almost in-soluble in water. A white amorphous precipitate. Gives no precipitate even in strong solutions. On warming however the zinc salt separates as a curdy-white mass. The free acid dissolves readily in baryta-water forming an easily soluble salt not precipitated by boiling. Gives no precipitate. Gives no precipitate. Gives no precipitate in the cold; on gently warming the solution a pink precipitate separates which on boiling becomes reddish-violet. When added to a hot strong solution produces a pale-green (almost white) precipitate. Action of Bromine 01% the Disodium Compound of Ethylic Isoheptane-tetrcrcarboxy late.This experiment which was instituted in the hope of obtaining a neptamethyleiie-derivative as mentioned in the introduction was cnrried out in the following way and with the following quanti-ties : OF CLOSED CARBON-CHAINS. 221 Expt. I. Expt. 11. isohePtanetetra-} 17.00 grams. 22-78 granls. carboxylate . Sodium 1.93 , 2.60 ,, Bromine 6.72 , 9-00 ,, In both experiments the sodium was dissolved in as little absolute alcohol as possible the resulting sodic ethylate diluted with a large quantity of pure dry ether (about 100 C.C. in Experiment I and 200 C.C. in Experiment II) and mixed with the ethylic isoheptane-tetracarboxylate. This caused the formation of a small amount of a yellowish flocculent precipitate but the greater part of the disodium compound remained in solution.This mixture was cooled with ice, and the bromine added to it drop by drop the whole being well agitated during the operation. The resulting colourless product was then well washed with water, the ethereal solution evaporated and the residual oil (which in Experiment 11 weighed nearly 22 grams) hydrolysed by boiling with a solution of potash in methyl alcohol. As soon as the hydrolysis was complete the alcohol was distilled off water added the solution acidified with dilute sulphuric acid and several times extracted with ether. After drying over calcic chloride and evaporating off the ether a thick almost colourless syrup remained which was now heated to 200" to cause the tetracarboxylic acid to split up into dicarboxylic acid and carbonic anhydride.The residue which was slightly brownish was then converted into its ethylic salt by treat-ment with ethyl alcohol and hydrogen chloride In this way a brownish oil was obtained which on fractioning under reduced pressure (100 mm.) distilled for the most part between 'LOO" and 260', leaving a small quantity of a dark brown residue. On repeated fractioning rather more than one-half of this oil distilled bet ween 210" and 220". This oil was not analysed but at once hydrolysed and the free acid examined. The whole quantity was boiled with a solution of potash in methyl alcohol for four hours and the acid isolated in the usual way by acidifying with dilute sulphuric acid and extracting with pure ether. I n this way a considerable quantity of a nearly colourless syrup was obtained which on standing for some days over sulphuric acid in a vacuum solidified almost completely.The cake of crystals was purified from a little oily mother-liquor by spreading out on a porous plate and after a few days became perfectly hard and colonrless. This substance on examination proved to be methylazelaic acid. It melted at 43-44," showed all the properties of this acid and gave the following results on analysis : 222 RUCRER ON THE 0.1351 gram substance gave 0.1075 gram H20 and 0.2935 gram co2. Theory. C10H1804. C 59.41 per cent. H 8.91 ,, 0 31-68 ,, I f methylheptamethylenecarboxylic product of these reactions it would on hydrogen chloride as described above, the boiling point of which would not Found.59.25 per cent. 8.84 ,, 31.91 ,, acid had been present in the etherification with alcohol and have yielded an ethereal salt, have differed very much from that of ethylic methylazelate. By the hydrolysis of the fraction of this ethereal salt boiling a t 210-220" methylazelaic acid was obtained but as far as we could see no trace of any other acid was present. I n order however to be more sure of this result the higher and lower fractions of this ethereal salt (200-260") were also submitted to hydrolysis and in this way a syrupy acid was obtained which on standing deposited a small quantity of methylazelaic acid. The mother-liquors from the crystals were now heated in a met,al-bath for some time a t 250-280" in the hope that i f any methylheptn-methylenedicarboxylic acid were present it would in this way be converted into its anhydride. On t'reating the product with dilute ammonia however it readily dissolved showing that no such change had taken place. From these results therefore it is evident that the action of bromine on the disodium compound of et'hylic isoheptaaetetra-carboxylate no heptamethylene-derivative is formed

ISSN:0368-1645    

DOI:10.1039/CT8885300215

出版商:RSC    

年代:1888

数据来源: RSC

摘要:

222 RUCRER ON THE XXII.-On the Range of Molecular Forces. By A. W. R~~CKER M.A. F.R.S. THE subject on which I have been asked to address the Chemical Society is the Range of Molecular Forces and it will perhaps be well that I should by way of prelude explain the meaning which I myself attach to that term. The investigation of the movements of a group of atoms or molecules is-though far more complex-in some respects similar to the study of the solar system. Newton proved that the Sun th RANGE OF MOLECULAR FORCES. 223 planets and their satellites behave as if a mutual action at ti distance taking place between them modified their motions in accordance with a very simple rule. The wonderful impetus which this rule-the law of gravitation-gave to astronomy has led to many attempts to apply a similar method t o molecular dynamics.Newton’s law is thus frequentlyregarded as being only the first term of a more complex expression which if complete would-on the hypothesis of action a t a distance-give the true law of mutual force between the ultimate particles of matt,er. The first term expresses all the results of experiment when the distances between the particles are con-siderable but is insufficient when they are near together. The investigation of the other terms which then become important may be properly spoken of as the study of molecular forces. Sir William Thomson (Proc. Roy. Institution 11 Pt. 111 483) has indeed expressed the opinion that it is possible that the phenomena of cohesion and others which arc! ordinarily ascribed to a departure a t small distances from the law of gravitation may not be incon-sistent with it.In that case the additional terms are introduced by the attempt to apply a formula founded on the assumed continuity of matter to phenomena which are caused by its “ coarse grainedness.” Interesting as this suggestion is it has not been worked out suffi-ciently tjo make it easy to translate all that we know of molecular action into language consistent with it. I shall therefore adhere to the ordinary usage and assume that it is probable that a somewhat complex expression is required for the full statement of the law of force between two molecules. If this formula were fully known the physical interpretation to be given to it would still be open to discussion Formerly it would no doubt have been considered sufficient to state as an ultimate fact that the law of the force in play between two molecules varies with the distance t!hat it is for instance attractive when they are far apart, repulsive when they are near together.Now such a supposition is branded as artificial but I venture to think that the artificiality is due rather to the acceptance of the hypothesis of action a t a distance than to the assumed complication of the law. There are two closely related yet really distinct ways in which an apparent repulsive force may be (in the ordinary sense of the word) explained. It may as has been the case with centrifugal force be shown to be an effect of motion and inertia without any abandonment of the theory of action at a distance in the case of the other forces involved.Or it may be explained as a result of the properties of a medium by which mat,ter is surrounded or of which each atom is a epecialised part If action a t a distance is thus reduced to action in proximity if machinery is imagined adequate to account for tlie effects which distant bodie 224 RUCKER ON THE produce upon each other it should explain not only the repulsions but also the attractions not only molecular elasticity but gravita-tion. It is I believe sometimes thoughtX that the next step in the progress of the theory of the constitution of matter will be the assumption of an unexplained attraction only between its ultimate particles while their elasticity is okherwise accounted for. This explanation of elasticity may or may not involve the hypothesis of a medium extending between the molecules.If we dispense with it we must not be content with vague analogies to account for the behaviour of two molecules during an encounter. It is true that a comet coming out of space toward the solar system might and probably would travel round the Sun without a collision but in meteor swarms and in gases with non-repelling molecules collisions must take place and Sir William Thomson (Rep. Brit. ASSOC. 1884 616) has insisted on the fact that the result of such collisions in a gas must be the transformation of energy of trans-lation into energy of vibration with the spontaneous cooling of the gas as a result. It is precisely because no such effect is observed that the theory of elastic molecules is abandoned.We are thus driven to suppose that elasticity is due to a repulsion, and if we refuse to accept the theory of action a t ;;L distance to introduce a medium by which the effect of a repulsion acting a t :t distance may be produced. It is however absurd to accept attraction a t a distance and to refuse to conceive of a repulsion acting nnder similar circumstances to admit the one without explanation and to invent a medium to account for the other. The most pregnant suggestions as to the constitution of matter which have hitherto been made do not proceed on these lines. An unexplained attraction is not assumed between vortex atoms in addition to the effects which follow from the laws of hydrodynamics. If it were necessary to adopt such an hypothesis the vortex atom theory would evidently be as artificial as that embodied in the bald statement that the law of force changes with the distance from attraction to repulsion.It is perhaps possible that some such hybrid theory might serve as a useful basis for calculation but from the philosophical standpoint it would not be a whit more conceivable than any other which involves action a t a distance. If then we are to retain the language of the latter theory in any part of our discnssion it will be convenient and not less accurate to retain it throughout 011 the distinct understanding t h a t it is a conventional mode of representing facts which we do not fully understand and which it does not suffice to explain completely.* “ On the Law of Molecular Force,” by W. Sutherland Phi7. Mag. July 1887, p. 127 RANGE OF JIOLECULAR FORCES. 285 A better method of expression may be found when suggestions like the vortex-atom theory of Sir William Thomson and the granular theory of Professor Osborne Reynolds (Phil. Mag. December 1885) are worked out. They no doubt will present grave difficulties as to the true nature of the action in proximity which takes place between contiguous granules or between neighbouring layers of the ideal fluid in which the vortices are formed but they will be justified as working hypotheses if they reduce the di5cul ties connected with the explana-tion of a large number of physical phenomena under a few heads. If then we use provisionally the language of action at a distance in the expectation that it will ultimately be replaced by a theory of action in proximity I think we ought from the first to admit that the law of force between molecules may be very complicated.We must not dismiss any idea which experiment suggests-such for instance as that there are several alternations of attraction and repulsion between two molecules as the distance between them diminishes-merely because it appears arbitrar-y and lacking in simplicity. It may be admitted for the sake of argument that we naturally look for simplicity in our fundamental assumptions but if the machinery by which distant bodies affect each other if the medium by which force is transmitted is simple it by no means follows that its effects on matter can be expressed on the action at a distance hypothesis by an easy formula.Even in the case of a single ball moving through a perfect liquid bounded by an infinite plane it will be apparently attracted to or repelled by the boundary according as it is projected parallel to or towards it. In the vortex-atom theory the behaviour of two molccules during an encounter would depend entirely upon the circumstances of the collision and cannot be very shortly de-scribed. I n the important case of a single vortex ring passing by a large number of others uniformly distributed it will experience a repulsion.* In Professor Osborne Reynolds’s grauular theory two molecules would exhibit mutual attraction and repulsion at different distances. I n none of these cases can the fundamental assumptions be regarded as complicated yet they all give rise to repulsions as well as attractions.They do not lead to simple expressions for the forces in play between molecules separated by distances of the same order of magnitude as their diameters. It would be perhaps too much to say that a simple result could only be produced by a medium of com-plicated constitution but it is certainly true that we have ci priori no more right to expect simplicity in the results of its action than simplicity in its constitution and that the two are not necessarily obtained together. f ‘‘ Motion of Vortex Rings,” J. J. Thomson. Mncmillan 1883 p. 55 226 RUCEER ON THE Thus much it has been needful t o say in order to explain the point of view from which I wish to regard molecular forces in this lecture.I shall use the language of the action a t a distance theory throughout, not-as I hope I have made clear-because I believe in it but because, i n so far as it can express them at all it affords a self-consistent method of describing facts the causes of which are as yet imperfectly under-stood. I shall not discuss the question of the representation of the forces by an algebraical formula. I cannot in the short time a t my disposal exhanst tho more limited subject to which I intend to confine myself. I desire only t o lay before you an outline of the results of the principal experiments which have been made with the view of determining the distances through which a law of force apparently different from that of gravitation obtains.The greatest distance from a molecule at which this deviation is sensible is called " the radius of molecular action." It constitutes the superior limit to the range of molecular forces. The inferior limit is what is ordinarily called the radius of a molecule but which if we regard the molecules as exer-cising when in close proximity a mutual repulsion is a length related to half the average minimum distance between their centres during an encounter. This distance may depend on the temperature and on the physical state of the body so that the diameter of a molecule may be different according as it is determined from experiments on gases or liquids. While retaining it as a convenient phrase it will emphasise the con-ventional sense in which it is used if we speak of the diameter of a gaseous or liquid molecule as the case may be.Between the limits thus defined the law of force is unknown, though interesting suggestions have been made by Maxwell and others, but apart from this question which as I have said I do not now discuss, the limits themselves may be determined very differently by different methods. The question as to whether a molecular force is " sensible " a t a given distance from the molecule depends partly upon the sensitiveness of the means used to detect it and partly upon the nature of the phenomenon-electrical optical or otherwise-studied. It is impossible therefore to group the results of various observa-tions into a connected whole but it may nevertheless be useful to give a short ~e'surne' of the conclusions to which different observers have been led and to attempt to arrange them as far as may be in order.The largest values which have been obtained for the magnitude of the radius of molecular action have been deduced from observations on the condensation of films of gases and vapours on the surfaces of solids. Quincke (Pogg. Ann. 108 326 1859) in 1859 argued that if it be assumed that the law of molecular force is the sam RAKU'GE OF BIOLECULAR FORCES. 227 for molecules in the gaseous liquid and solid states the superior specific gravity of a solid would enable it to condense a gas upon its surface. It is evident however from recent observations that the nature of the solid is of eren greater importance than its density. Among the more remarkable investigations on this point is that of Bunsen ( V i e d .Ann. 20 552 1883). A bundle of glass threads the total surface of which was determined by preliminary observations and calculations was enclosed in a chamber connected with a long tube, the lower end of which was dipped in mercury. The gradual rise of the mercurial column showed that an apparent absorption of carbonic acid by the glass was still going on a t the end of three years. Later observations ( W i e d . Ann. 24 1885 322) proved that although the glass had been carefully dried it is impossible to get rid of all the adhering moisture unless the temperature is raised to a point not far short of the critical temperature of water. If this precaution Bas been omitted carbonic acid if present will according to Bunsen be dissolved in the water-film and since the inner layers of the liquid are subjected by molecular attraction to a pressure which is measured by hundreds of atmospheres they are capable of absorbing enormous quantities of the gas.The strong acid thus formed appears to attack the glass and it was found that nearly 6 per cent. of the total mass of glass threads employed had been disintegrated ( W i e d . Ann., 29 1886 161). The long-continued apparent condensation was, therefore really slow chemical action. Nay more when the glass had been dried a t a high temperature no appreciable condensation of carbonic acid on the surface took place in eight days ( W i e d . Ann., 24 1885 335). A small quantity of water was then introduced and absorbed by the glass threads with a rapidity which showed that when really dry they acted as a more powerful desiccator than calcium chloride.Immediately after the introduction of the water the absorption of the C02 began as before which proved that moisture was necessary to produce the phenomenon or that carbonic acid does not condense to a measurable amount on dry glass. By exposing glass threads to a series of constant teniperatures until in each case no more moisture could be exhacted by the passage of a current of dry air over them and by measuring the successive quantities of water thus obtained Burlsen waa able to calculate the total thickness of the water film which at each of these temperatures is irremovable by dry air. Under ordinary conditions water does not eva,porate when its vapour exerts upon the surface a particular pressure the magnitude of which varies with the temperature.Any internal layer parallel to the surface is subjected to an additional molecular pi-essure which increases rapidly with the depth until th 228 RUCKER ON THE 6 *YO 5'47 3 -63 1'32 0 *4,2 0 -00 boundary of the superficial portion of the liquid is reached after which it becomes constant throughout the interior. If the interior mass of water be replaced by a solid which exerts, ceteris paribus a greater attraction on vater than that of water itself, the molecular pressure would be increased and thus the vapour-tension might be diminished without evaporation taking place. The defect of the external pressure would be balanced by the increased molecular attraction.If then we assume that the thickness of the water film which cannot a t any given temperature be removed by dry air is such that the pressure due to molecular attraction a t the surface of the film is equal to the pressure of aqueous vapour at the temperature a t which the experiment is made it is possible when the vapour-tension is known to calcnlat-e the molecular pressure f o r given thicknesses of the film. The following table expresses Bunsen's results. The temperature is expressed in degrees centigrade. The thickness neglecting some minor corrections is indicated by D and expressed in terms of micromillimetres (p.p.)* The pressure is ex-pressed in atmospheres :-1 *278 20 .791 ----t. D. 23' 107 21 5 329 415 468 503 If the desiccation with dry air was incomplete the thickness of the films very much exceeded the above limits.Thus in one experiment in which the drying was purposely imperfect the water layer was 232.4 p.p. thick. The interpretation to be placed on these results has however been again rendered doubtful by the experiments of Warburg and Ihmori (Wied. Ann. 27 481 1886). These observers constructed a small balance of extraordinary delicacy which was enclosed iii an exhausted receiver which could be connected at pleasure with vessels containing strong sulphuric acid or water. When it had been dried by frequent evacuation water vapour was admitted, and the weight of the films deposited on a thin glass bulb suspended from the balance was determined.They found that if the glass was washed with boiling water before the experiment the deposited film was very much thinner than if this * The micromillimetre is the millionth part of a millimetre RANGE OF MOLECULAR FORCES. 229 precaution had been omitted. The thickness diminished in two experi-ments in the proportion of 48 to 4 and 23 t o 2. I n a third case no film could be detected even when the temperature of the receiver was only 0.2" above the dew point. Glass rods which have been boiled for a few minutes will not discharge an electroscope even when they have for long been in a relatively damp atmosphere under circumstances such that rods of the same glass which have not been similarly treated conduct readily. The film of moisture adherent to glsss may thus be divided into two parts distinguished as the permanent and temporary respectively, of which the latter disappears under the influence of a long-con-tinued current of dry air while the former can only be removed by raising the temperature.Warburg and Ihmori conclude that the temporary film (with which they alone deal) is not produced by tlie molecular at,traction of the glass as a whole on water vaponr. They refer to experiments which prove that if glass powder be boiled in water measurable quantities of alkali are dissolved. They therefore, assume that there is a certain quantity of free or loosely combined alkali on the surface of the glass and that it absorbs water until a solution is formed the vapour-tension of which corresponds to thc hygrometric state of the air in the neighbourhood.If carbonic acid is then absorbed by the solution the glass may be attacked and the process continued. Further experiments have been made by Ihmori (Wied. Ann. 31, 1006 1887). He finds that the water films on clean unvarnished metal surfaces are extremely thin varying from 10 to 3p.p. On oxidised metal they may be twice as thick and he inclines to tlie view that in all cases the phenomenon is due to oxidation. Varnished metal may in 20". absorb enough t o produce a layer 286 p.p. thick, and sealing-wax also absorbs large quantities. Nineteen experiments on quartz gave a mean thickness of 22 ,u.p. with a maximum of 62 p.p. Six observations made when the crystal had been previously washed gave a mean of 4 p.p.and a maximum of 6 p.p. only. The mean result of 11 experiments on platinum was under 3 p.pu. the maximum being 122 p p . I n the case of a piece which was specially cleaned by heating no condensation could be detected. Agate absorbs large quantities of water. Films the thickness of which varied between 562 and 1640 pp. are stated to be the result of an hour's exposure to a moist atmosphere. It is however well known though Herr Ihmori does not' refer to the fact that agate consists of alternate layers of quartz and a porous form of silica allied to opal. Professor Judd has kindly furnished me with specimens which have been immersed in coloured solutions. These have been absorbed by the porou 230 RUCKER ON THE layers and thus coloured bands are formed.I n this way a good imitation of an onyx may be produced. There can be no doubt that tlhe surface exposed by the agate to the water-vapour includes that of the interior of a vast number of capillary tubes and is enormously greater than the mere external surface. The quantity of water absorbed does not therefore give any indication of the thickness of the water film and no deduction as to the radius of molecular action can be drawn from it. The net result of these experiments is to render it doubtful whether in the case of substances which are not dissolved or chemically acted on by water any measurable temporary film is formed a t temperatures above the dew point. If such a film is formed in these cases its thickness is according to Warburg and Ihmori in general very much less than the radius of molecular action as determined by Quincke.PfeifEer (Wied. Bei. 8 635 1884) who published some experi-ments on the absorption of gases by solids a t high pressures arrived a t the conclusion that layers of ammonia and carbonic acid of the thick-ness of 450 p.p. and 240 p.p, are formed on charcoal made from firwood. As however the result is based on calculations made from box-wood charcoal in which it is assnmed that it condenses SO exactly in the same way as glass does but little reliance can be placed on it. It is probable that water films play as important a part in the ap-parent condensation of SO on the surface of glass as they do in that of co,. Another group of experiments has been made with iron oxide, alumina and silica which readily absorb water and carbon bisulphide.Thus Muller-Erzbach (Ezner’s Rep. 21,409,1885) measured the grains of finely powdered oxide of iron under the microscope and concluded that a certain area was greater than that of a given weight of the powder. He then deduced from this datum and the weight of CS absorbed by the oxide the thickness of the film. Assuming that the specific gravity of the absorbed CS was increased from 1-27 to 1.60 by causes similar to those which affect the specific gravity of water of crystallisation he concluded that the film was a t least 1000 p p . in thickness. Similar calculations (Exner’s Rep. 21 553 1885) gave 1700 +,u. for the thick-ness of a film of CS adherent to alumina. He finally concludes that the radius of molecular action is at least 1500 p.p.(Wied. Ann., 28 696 1886). Kayser (Wied. Ann. 14 450 ISSl) as the result of experiments on the condensation of gases on glass thread was of opinion that the quantity condensed depended on t’he closeness with which the fibres were packed and that the radius of molecular action was of the same order of magnitude as the diameter of the threads. He fixes its magnitude a t from 2000 to 3000 p.p. As these observations were made before the importance of getting rid of the water film b RASGE OF MOLECULAR FURCES. 231 heating had been demonstrated they cannot be accepted as support-ing this enormoils value. Passing next to the condensation of the more permanent gases, I may refer to a calculation made by Callendar," on the assnmp-tion that the differences between the coefficients of expansion of air between 0" and 100" C.given by various air thermometeru, depend on the quantity of air condensed when they are cooled and thus upon the ratio between the surface and volume of the bulbs, which of course varies with their shapes. He shows that the values for the coefficients of expansion of air at constant volume between 0" and 100" C. obtained by Regnault Bidfour Stewart and himself, would agree if the weight of air condensed between those tempera-tures is 10-6 grams per sq. em. From this we deduce that the thick-ness of the film removed by heating from 0" to 100" C. would be 10 p.p. if the density be assumed to be the same as that of water. Schumann (Wied. Am,. 27 91 1886) has also recently pointed out that if the layer of air condensed on glass reaches con-siderable dimensions the length of a mercurial thyead in a capil-lary tube would be appreciably different according as the film was or was not present.He therefore connected a long bent capillary tiibe with a bulb and when the positions of the ends of a thread of mercury had been determined it was transferred to the bulb. The tube was then exhausted and heated to 312" C. which could be accomplished without heating the mercury. When the apparatus had become cold the mercury was returned to the capillary tube. Its length was found to be precisely the same as before. The thickness of the air film removed by the heating could not therefore according to Schumann have been greater than 70 pp.His method of course involves the assumption which seems legitimate that the mercury would not remove the fiIm from the glass as it moved along the tube. An argument to the same effect may be drawn from some observa-tions made by Bottomley (Chem. News 51 85 1885) and published in 1885. He exhausted a vessel containing glass fibres by means of ft mercury pump until the pressure as indicated by a McLeod gauge was 0.3 M.? He then heated the vessel and its contents until some of the glass fibres began to soften and collected the gas which was given off. It amounted in all to 0.45 c.c. at 15" C. and 760 mm. and when analysed was found to contain 8-24! per cent. GOz 248 per cent. Oz, and 75.2 per cent. N?. The total surface of the fibres was 14-48 sq. cm. The gas as it left the vessel was dried and it is not stated that the * " On the Practical Measurement of Temperature," Phil.Trans. vol. 178 (1887)) A. p. 161. t M = 1 millionth of an atmosphere 232 RUCKER ON THE glass fibres had been previously washed so that there probably was a water film of the magnitude of which no estimate could be formed. It is therefore probable that the gases were partly dissolved but a t all events the observations lent no support to the idea that the gas film on glass dried only by contact with dry air is very thick. If we assume that the mixture when collected was of the same density as air and that when in contact with the glass it had the same density as water the thickness of the film of condensed gas was 4 ,u.p. which is somewhat less than the number deduced on the same hypothesis from Callendar’s suggestion.On the whole looking only a t the very contradictory results attained by different researches and without regard to arguments which T shall presently adduce I must confess that I do not think we can a t present draw any certain conclusion as to the magnitude of the radius of molecular action from observations on the condensa-tion of vapours or gases. TO justify this view I cannot perhaps do better than quote from two of the gentlemen who have studied the phenomena most closely. I n 1885 Miiller-Erzbach remarks (Exner’s Rep. 21 1885 407) :-“Ich habe nun . . . ein Mittel gefunden durch welches ich auf einfache Weise glaube beweisen zu konnen dass die i n Betracht konimenden Molecularkrafte nicht nur bei unmittelbarer Beriihrung wirksam sind sondern selbst noch in einem griisseren Abstand als ihn Hr Quincke nach seinen Versuchen bestimmt hat.” In 1886 Warburg and Ihmori sum up these results as follows (Wied.Ann. 27 507 1886) :-“ Es liegt uns fern die Richtigkeit der Schlusse Quincke’s auzueweifeln . . . . Allein in den Messungen, welche wir uber das Gewicht der Wasserhaut bei Glas und anderen Kor pern anges tellt ha ben ist uns nic hts en t’gege n ge t reten woraus eine Wirking der Molecularkrafte auf niessbare Distanzen hin zu erschliessen wiire.” The first important attempt to measure the radius of molecular action was made by Plateau (Stntique des Liguides 1873 1, 210). Arguing that the surface-tensions would decrease if the thickness of a soap film became less than twice the radius he made experiments to determine whether the pressure exerted on the enclosed air depended on the thickness.His method was open to criticism. The soap bubble was made of a mixture of soap water, and glycerine and thus its constituticn would alter unless it were surrounded by aqueous vapour of a determinate tension. No pre-cautions were taken to secure this condition. The bubble was pro-duced a t the end of a tube bent so as t o form a manometer. The liquid used to measure the pressure was water while the rate of thinning of the bubble was accelerated by enclosing it in a covere RASGE OF MOLECULAR FORCES. 233 beaker in which were placed some sticks of caustic potash. Under these circumstances it is impossible to say what the final constitution of the liquid might be.By measuring the specific electrical resistance of various mixtures of glycerine and soap and water and the resist-ance of cylindrical soap films formed of the same substances Pro-fessor Reinold and I have been able to measure the changes i u the constitution of films when subjected to variations in the temperature or hygrometric state of the surrounding air. We found it very diffi-cult to secure constant conditions and that under circumstances far more favourable than those of Plateau’s experiments the films lost one of the 57.7 volumes of water originally contained in every 100 of solution in times which varied between four and eight minutes (Phil. Trans. Part 11 1881 486). As Plateau’s film lasted two days it is evident a change of compo-sition sufficient to have caused a marked or considerable change in surface- tension due to thinning might have occurred.Platleau observed no change in the pressure when the colours of the bubble proved that its thickness was 118 p.p and thence concluded that the radius of molecular action is < 59 p.p. This inference is not so certain as he appears to have thought ii; to be. Maxwell (Art. “ Capillary Action,” Enc. Brit. ed. ix) has shown that if we neglect the change of density in the surface of the liquid and the thermal phenomena which accompany the thinning of a film the surface-tension will remain nnchanged until the thickness is equal to the radius of molecular action. It is difficult to estimate the extent to which this result might be affected by a theory which took cognisance of the motion of molecules and the change of surface-density.Per-h a p therefore all that we are entitled to say is that if no change is observed in the tension of a film of given thickness the radius of molecular action must be less than that thickness but that if a change is observed it must be greater than half that thickness. Thus the superior limit fixed by Plateau’s experiment would be t’wice as great as it has been generally assumed to be. Quincke (Pogg. Ann. 1869 137 402) attacked the problem in another way. He placed a layer of Martin’s silvering solutiorl between a glass cylinder of 120 mm. radius and a plane sheet of glass. A double wedge of silver which was thinnest in the centre, was deposited on the surface.Two sheets of glass thus prepared were fastened together with a small interval between them with their silver sides inwards and adjusted so that silver layers of equal thickness were as nearly as possible opposite to each other. A glass cell open at the top and bottom having thus been formed the lower part was immersed in distilled water. The cell being vertical the water rose highest in the centre where it might be considered to be VOL. LIII. 234 RUCKER ON THE in contact with the gIass. On each side as the silver sheet became thicker the capillary elevation diminished. It was measured at known distances from the centre and the angle between the solid and the liquid surface calculated. This would became constant when the thickness of the silver layer was such that the attraction of the glass on the water was negligible.The silver was afterwards converted into iodide of silver and the thickness of the layer a t different parts deduced from the colour. Similar experiments were made wihh other substances. The results may be summed up as follows if we write p for the radius of molecular action in terms of micromilli-metres :-p > 54-2 for watw silver and glass, - 43.3 , mercury sulphide of silver aud gIass, - 59.0 , mercury iodide of silver and glass, < 80.0 , mercury collodion and glass. The quantity p as given by these experiments strictly speaking measures not the radius of molecular action but the distance a t which the difference between the molecular forces exerted by glass and silver becomes inappreciable.This would probably be somewhat less than the true radius but nevertheless the net result is to show that the radius of molecular actiop is approximately = 50 p.p. It is much to be desired that this conchion should be in every way tested, and that similar observations should be undertaken by other physicists. I hope tjo show in the course of this lecture that it does receive im-portant confirmation from the behaviour of thinning soap films. Plateau’s experiment has been repeated and modified in various ways. Ludtge ( P o g g . Ann. 139 1870 SSO) inshead of directly measuring the pressure exerted by bubbles compared the pressures due to thick and thin films by balancing them against each other. A soap film having been formed a t the end of a tube it was allowed to thin and the other end was then closed by another film.Air was forced in the films assumed the form of spherical segments and tl]eii* curvatures were compared. If p is the pressure exerted by a soap bubble of which T and R are the surface-tension and radius respec-tively p = 4T/R. Hence if the tensions of the thick and thin films were different their radii would be different also. He concluded that the radius of molecular action was much larger than Plateau and Quincke’s observations would have led us to suppose and that con-trary to expectation the thicker film had the less surface-tension. His experiments were repeated and extended by Van der hlensbruyghe (BruxeZZes Acad. Sci. BUZZ. 30 1870 322) who was unable to detect the alleged change of tension.Afterwards howerer he suggested and adduced experiments to prove that the phenonienoi RAKGE OF MOLECULAR FORCES 235 was probably real and due to the cold produced by the continu;al evolution of fresh liquid surFaces as the films thiuned (Bruxelles Acad. Sci. Mern. 43 1882 No. 4 18). Lastly Professor Reinold and I (Phil. Trans. 177 Part 11 627, 1886) have employed similar methods. We balanced two cylindrical films the one against the other ; one of them was kept thick by passing up it an electyic current which we have shown carries the matter of a thin film with it (Phil. Mag., 19 94 1885). The other was allowed to thin and the ten-sions were deduced from the cuwatures. The above figurerepre-sents diagrammatically the essential parts of the apparatus.The cylinders were formed between platinum rings and their interiors could be put in connection with each other or with the external air by stopcocks. The apparatus actually used was somewhat complicated. The films were formed in a closed glass box surrounded by water. They could be made and adjusted without opening the box so that the temperature and hygrometric state of the enclosed space were constant. A difference of surface-tension was indicated by a bulging of one film and a contraction of the other. Several possible causes of error were investigated and as the distorted films were unduloids, formulse were devised by means of which we could at once calculate the difference of the tensions of the two films when their lengths and maximum or minimum diameters were known.We found as has indeed been noticed by others that the surface-tension of a newly-formed film diminishes and that from 10 to 15 minutes must elapse before it acquires an approximately constant valne. By measuring the magnitude of the changes of surface-tension thus developed we proved that they were far too great to be accountled for as Van der Mensbrugghe supposed by cooling due t o thinning. The calculated R 236 RUCKER ON THE change was 0.0016 per cent. while we observed changes of 9 per cent. The effect is probably only a striking instance of the difficulty of preserving a liquid surface pure. If however two films of very different thicknesses but neither of which had been very recently formed were compared the difference of tension (if any) was very small and was not constant either as to sign or amount.We concluded that no evidence of a change in surface-tension dependent on the thickness of the film is furnished by a direct comparison of the tensions of thin and thick films over a range of thickness extending from 1350 milliooths of a millimetre down to the stage of extreme tenuity when the film shows the black of the first order of Newton’s scale of colours. Had any such dif-ference as large as one-half per cent. of the value of the tension existed we must have detected it. The magnitude of the lower limit when the film appears black was given bp the results of a previous research (Pld. Trans. Part 11 1813, 645). We had determined the thickness of black soap-films by measnreaents based on two independent methods the one electrical, the other optical.I n the first we measured the resistance of cylin-drical films and deduced the thickness on the assumption that the specific resistance was the same as that of a thick layer of the same liquid. The apparatus used is shown in the figure. The film was formed The lower part of the glass between the platinum rings A and B RANGE OF MOLECULAR FORCES. 2 37 Method. vessel was flooded with the solution and C is an endless linen band which dipped in the liquid and could be rotated from the outside. I t was thus kept moist and the hygrometric state of the air was main-tained at a constant point. The current flowed from the binding screw D to A thence through the film to B and E.At F a pair of insulated gold wires penetrated the film. They were concected with the opposite quadrants of an electrometer and the differences of potential between them and between the extremities of a known resistance inserted in the circuit were measured alternately. Prom these the resistance of the film between the needles was deduced. I n the second method we passed the two rays of light used in an apparatus* for the production of the phenomenon of interference by means of thick plates through two tubes in which a number of plant: films had been formed. A known number of films was then broken in each tube in turn. The thickness was deduced from thedisplacement of the interference bands on the assumption that the mean I-efractive index of the thin films was the same as that obtained by the ordinary methods from experiments on the liquid in mass.The results may be summarised as follows :-No. of films observed. Liquid. Electrical . . Electrical . . Optical . . ,. Optical . . . . Liquide glycQrique . . . . Soap solution, out glycerine .ft.?- { 99 )) 5 7 13 9 Mean thick-ness in terms of 10-6 mm. 11.9 10 -7 11 -7 12 -1 Probable error of a single observation. -f 0.2 f 0’6 f 1’4 f 0.8 The close agreement between these numbers obtained by different methods and by calculations based upon different assumptions proves conclusively that the thickness of a black film is generally about, 12 p . ~ . We found that the thickness of different films might vary within several millionths of a millimetre but that in any given film the thickness of the black part remains constant-at all events from a short time after its first formation.At first sight then it appears as though our result was in direct opposition to that obtained by Quincke and proved that the radius of molecular action is <12 pp. This is not the interpretation we ourselves put upon it. The black and coloured parts of a film are separated by a sharp line, which shows that there is a discontinuity in the thickness. Thus in extreme cases the rest of the film may be 250 times thicker than the black part with which it is apparently in contact. * Sometimes called a Jamin’6 Interferential Ref ractometer 238 RUCKER ON THE The accompanying figures represent the life history of a film which Professor Reinold and I watched for several hours.They are sections deduced from the colours observed at intervals. The thickness is magnified 5000 times more than the length. The upper part of the film. was black and the enormously rapid change in thicknem at the edge of the black is well shown. Sir William Thornson (Proc. Roy. Instit. 11 Part 111 485 1887) and Professor Reinold and myself (Phil. Trrans. 177 Part 11 679 and 684 1886) independently arrived at the conclusion that our observations on the uniform thickness of the black part of a film and on the discontinuity in the thickness at its edge prove that when the film reaches a certain degree of tenuity the snrface-tension diminishes to a minimum and begins to increase again when the thickness is somewhat greater than 12 p,p.The relation between the surface-tension and thickness may thus be represented by a curve like that shown in the accompanying figure. When t,he thickness is great the surface-tension is constant. When it reaches the value which corresponds to P the tension begins t RANGE OF MOLECULAR FORCES. 239 diminish. The thicker parts of the film now tear the thinner parts asunder. Rupture would inevitably follom were it not for the fact that when a certain degree of tenuity is reached the surface-ten-sion again increases and when the thickness is 12 p . ~ . becomes equal to that of a thick film as indicated by the equality of the ordi-nates at P and Q. Equilibrium is thus possible between two parts of a film of which the one has the thickness corresponding to Q and the other any thickness greater than that corresponding to P.It is also stable for any further decrease in the thickness of the film below Q would cause a further increase of tension; the thinner parts would therefore contract and become thicker. In other words the film could not under ordinary circumstances thin to below that thickness for which the surface-tension regains its normal value. The discontinuity at the edge of the black and the uniform thickness G f a black film are thus both accounted for. Our failure to detect any measurable difference of surface-t'ension between thick and thin films means not that the radius of molecular action is less than 12 p.p., but that the changes of tension which produce the sharp edge of the black are certainly <W5 per cent.of its whole value. Let us then examine this remarkable phenomenon a little more closely. It is a result of ordinary observation that in a thinning film there is a range of unstable thickness which is always missing between the black and coloured parts. The instability is very strikingly shown by an experiment which Professor Beinold and I bave often performed. If an electric current be sent up a cylin-drical film the upper part of which is black the sharp edge is obliterated. The current carries liquid up with it smoothes oi€' the discontinuity and the colours pass into the black by a gradual tran-sition through grey. As soon however as the current is broken the old state of things is re-established.The grey disappears and the black is again bounded by a definite sharp edge. The change takes place in from 10 to 16 seconds. The colours which thus vanish correspond to the range of unstable thickness. Its lower limit is fixed by the experi-ments of Professor Reinold and myself as being nearly 12 .u.p. The upper limit is more difficult to determine as the colour by which the black part of the film is bordered varies and is probably largely determined by accident. This however may certainly be said that when the film thins in the normal way the discontinuity in the khick-ness never occurs within the grey region. The colour next to the black may rise into the second or higher orders ; it never sinks below a full white of the first order. It is therefore probable that the decrease i n surface-tension begins at a thickness less than that which corre-sponds to the middle of the white and greater than that whic 240 RUCEER ON THE corresponds to the beginning of the black or faint blue which surrounds it.According to Newton these thicknesses are 96 and 45 ,u.p. respectively the mean being 70 ,u.p Let us now assume that Quincke’s value of the radius of molecular action is correct. The greatest possible thickness a,t which the surface-tension of a film could begin to diminish is then 100 p.p. Any film thicker than this would have two complete surface layers and a layer of “ interior ” liquid separating them. Its surface-tension could not therefore depend on the thickness. On the other hand if Maxwell’s theory were correct, the tension would remain unaltered until the thickness was equal to the radius of molecular action that is 50 p p .It is not I think, probable that any improvement in the theory would reduce this limit, though it might increase it. Hence we arrive a t the conclusion that t h e limits of thickness f i w d b y observation as those between which t h e sugnce-tension of a f i l m begins t o diminish (96 and 45 ,u.p.> are yrutc-tically i d e n f i c a l with the l i m i t s deduced by theory from Quiszcke’s expe-riment (100 a n d 50 p.,u.> as those within which such decrease o q h t $ r s t to be observed. Curious and important as I venture to think this conclusion is T do not wish to press it too far. The fact that the limits of doubt imposed by two independent lines of argument are a t the present moment the same,is a more or less accidental coincidence.The vital point is that the value of the radius of molecular action as determined by Quincke is certainly of the same order as and cannot possibly differ much in mag-nitude from that which may be deduced from the properties of soap films. Quincke’s result is therefore not an isolated fact. It receives the strongest possible confirmation from a totally different line of research. The radius of molecular action cannot if Maxwell’s theory be accepted, be greater than 96 pp. which is the superior limit to the tllickness a t which the surface-tension begins to decrease. If the ordinary view be correct it cannot be less than one-half of 45 p.,u. which is the lower limit to that thickness.Hence the true value of the radius of molecular action lies between 96 and ‘23 p.p and the value found by Quiiicke (50 ,u.,u.) is inter-mediate between these. However therefore we combine the figures we deduce from the two observations the same result viz. that 50 p.p. is of the same order of magnitude as the radius of molecular action a conclusion which i t is not too much to say has now strong claims to rank as an ascertained fact. Van der WaalsX deduced from his theory distances between 0.15 and * “ Die Continuitat des ga*foimigen und fliissigen Zustandes.” Van der Waals. The matter may also be presented in another way. Trtinslat,ed by F. Roth Leipzig 1881 p. 107 RANGE OF MOLECULAR FORCES. 2-21 0.29 p . ~ which are less but as he thinks not very much less than the radius of molecular action and he expresses the opinion that Quincke's value is larger than our knowledge of capillary phenomena will allow.As the numbers he himself obtains are from 0.01 to 0.02 of the thickness of a black soap-film i t is evident from the above discus-sion that they are very much too small. Passing next to the lower limit of the unstable thickness ( l a ,p.p.), we must enquire what is the cause of the increase of surface-tension to which the uniform thickness of the black film is due. On this point it may be well to speak with a certain amount of reserve until the theory of the constitution of liquids is more fully developed. If however, we accept equations obtained by Maxwell in which the movements of the molecules and the surface change of density are neglected the phenomenon can be at once explained if we suppose that the increase of surface-tension corresponds to a change from attraction to repul-sion in the intermolecular forces.If the force exerted by a liquid mass on a particle is repulsive when the distance of the particle from the surface lies between certain limits then the tension of films the thick-ness of which is comprised between the same limits will increase instead of decreasing as the thickness diminishes. From this point of view therefore the explanation of the sharp edge of the black part of a soap film would be that when the molecular force between a liquid bounded by a plane surface and a molecule in its neigh-bourhood first becomes sensible i t is an sattraction but that a t some lesser distance which is nevertheless greater than 1 2 x 10-6 mm., it becomes a repulsion.It must however be distinctly understood that the explanation that the increase in surface-tension is due to the action of a repulsive force is only put forward as suggested by Max-well's theory. I think that this conclusion is very much more doubt-ful than that which determines the thickness at which the surface-tension would begin to diminish b u t the further discussion of this p i n t would involve a mathematical argument with which I will not a t present trouble you. If however apart from the question as to how it may be mechani-cally explained the view be accepted that the surface-tension falls t,o a minimum and is again increasing when the thickness is 12 pp.the veiy interesting question arises whether there is any experimental evidence that at some thickness less than 12 k.p. it again diminishes. In answer it may be remarked that in general the black spreads slowly and quietly over the film and may take an hour or more in travelling from the top to the bottom of a cylindrical film 26 mm. long. All the statements I have hitherto made refer to cases i n which the mode of formation was thus normal (Phil. Trans. 177 [ a ] 677, 1886). " At times however the black is formed with something like 212 RUCKER ON THE convulsion. Not only does it spread with extraordinary rapidity but the edge is violently disturbed and large patches rise through the coloured part of the film.Whenever this occurs the film breaks before long but in four cases we were able to obtain measurements before rupture. We are not able to produce this phenomenon at will, but the few observations we have been able to make on it are in agreement among themselves.” I n all cases the cylinder which thinned most rapidly bulged the other contracted. The differences thus produced between the diameters varied from 0.35 to 0.75 mm., and could not be accounted for by the sudden renewal of the surface of the thinning film (which would have produced a change in the other direction) or by any other cause known to us. The measure-ment of the thickness of such films would probably settle the question as to whether the black when formed in this abnormal way corre-sponds to the stateof unstable equilibrium which would exist if after increasing the surface-tension again diminished as the film became thinner or to a second state stable within narrow limits of thickness.Such experiments would however be attended with extraordinary difficulties as they would involve measurements on films which are practically always short-lived and which are possibly theoretically unstable. Another method of investigating the magnitude of the radius of molecular action is based on the phenomenon of electrolytic polarisa-tion. If we immerse in acidulated water two similar metal plates which are not attacked by the acid they will be a t the same potential. When a current is passed from the one to the other they will if the metal and acid have been properly chosen become covered with films of oxygen and hydrogen respectively.The sum of the differ-ences of potential due to metal I gas I liqiiid is not the same as that due to the single metal I liquid contact and varies with the nature of the gas. Hence the coated plates assume different potentials but the full difference is not established until the surface-density of the deposited gas exceeds a certain value. If then we suppose that the film is uniform and that the metal and liquid cannot be regarded as completely separated until the thickness of the film exceeds t,he radius of molecular action we may by plausible assumptions as to the density of the gas estimate its magnitude. Thus F. Kohlrausch ( Y o g g . Ann. 148 153 1873) concluded that if the gases are eupposed to be a t their ordinary densities the polarisa-tion of a platinum electrode is complete when it is coated with a layer of oxygen 20 pp.in thickness. It is evident that this assump-tion as to the density of the gas is totally a t variance with the views ordinarily pnt forward in discussions on the condensation of gases 011 solids as to the great molecular pressure to which the condensed fil RAXGE OF MOLECULAR FORCES. 243 is subjected and that doubt on this point deprives such observations of all value for our present purpose. To reduce the uncertainty as to the density of the polarising layer it is evidently better to substlitute another metal for a gas. This has recently been done by Oberbeck (Wied. Ann. 31 337 1887). The films were deposited on platinum electrodes and the liquids used were solutions of ZnSO, CdS04 and CuSO4.Three platinum plates were immersed in the solution contained in a rectangular cell. Two plates of the metal of which the sulphate was used (zinc say) were interposed between the central platinum plate and the other two and were used as electrodes by means of which a Iziyer of zinc was deposited on both sides of the central plate. Electrolysis was continued until the difference of potential between the coated plate and the external platiiiums which were not affected by the current was the same as that between Zn and Pt (1.13 Daniell). The current was then stopped and for a time the electromotive force slowly diminished after which a very rapid decrease was observed.The film was spontaneously re-dissolved and the sudden change in the rate of the fall of the electromotive force was regarded as indicating that the thickness of the metallic layer had become less than the radius of molecular action. If a is the quantity of metal deposited on each sq. cm. (which could be calculated from the current strength &c.) ; and e the time whicb elapsed after the completion of the eiectro-lysis before the rapid fall of E.M.F., i t was found t.hat these quantities were connected by a relation of the form-a = A + Be, where A and B are constants. Of these A is the quantity of zinc on each sq. cm. when its thickness is just less than the radius of molecular action and by means of two experiments in which a and 8 have different values it can be calculated.Oberbeck concludes that if the specific gravities of the electrolytic layers are the same as those of the metals under ordinary circumstances the thicknesses necessary to establish the full difference of potential are between 2 and 3 ,up. for zinc between 1 and 2 p.p. for cadmium and rather less than 1 p+. for copper. Interesting as these results are they are as Oberbeck himself points out open to criticism. The rapid decrease in the E.M.F. might be explained by supposing that when the zinc layer becomes very thin, parts of the platinum plate are uncovered and that local action takes place which rapidly dissolves the zinc. ThiB is certain to occur unles 2-14 RUCKER ON THE the metallic film is uniform. To test its uniformity the experiment was repeated with a solution of acetate of lead as the electrolytic liquid.The colour of the platinum electrode showed that the deposit was uniform over the greater part of the plate but was slightly thicker towards the edges. No data as to the colours displayed are given but unless the difference of the tints was very slight it would correspoud to a variation of tliickness greater than that assigned to the radius of molecular action. The next method which I propose to describe aims at a measure-ment of the distance between two consecutive layers of molecules. If plates of Zn and Cu are connected by a metallic wire they assume different potentials (P and p ) the Zn becomes positively the Cu negatively electrified. When the plates are parallel to each other, and separated by a distance t centimetres they form a condenser and if + e is the charge upon 1 sq.cm. of the Zn plate e = (P -p>/47t. Hence st is a constant which depends only on the nature of the metals and is independent of the distance between them. When the metals are in contact the potential difference remains unaltered and we may regard the surface molecules as being oppositely charged and separated by a very small interval. The two charges are said by v. Helmholtz to constitute an electric double layer ( P o g g . Ann., 89 211 2853 ; Wied. Ann. 7 337 1879). The mutual action of two metals or of a metal and liquid when in contact is t'herefore the resultant of the molecular forces and the electrical attractions and repulsions which are in play between the different parts of the double layer.Thus v. Helmholtz (BerZin Wissenschnft. Abh. 925 1882 ; see also Wied. Ann. 16 31 1882) has proved theoretically that the surface-tension depends on the electrical charge and is a maxi-mum when it vanishes and as is well known Lippmann (Annales de Chemie 5 4<94 1875j has shown that the surface-tension of mercury in contact with dilute acid is a function of the difference of potential between them arid that every motion of the common surface changes the potential difference in such a way as to produce an alteration in the surface-tension which checks the motion. By means of a theory which it is unnecessary to reproduce here he (Compt. rend. 95 687 1882) drew from his experiments the con-clusion that for such differences of potential as he employed the capacity of a given area of a Hg 1 H,O surface is constant.Hence the distance between the two electrified surfaces is constant and can be deduced from the theory. Oberbeck ('CVied. Avzn. 21 157 1884) and Falck have measured the electro-motive force of polariss tion produced by alternating currents on metals immersed in solutions of Ki,SOa KCl KBr and KI. They The value found is 0.03 p.p RANGE OF MOLECULAR FORCES. 245 conclude that the capacity of the double layer is not constant but is a function of the charge so that its t,hickness must be regarded as variable. They deduce however its limiting value when the charge is zero i.e. the distance between the nearest layers of molecules under normal conditions when no current is passing.The magni-tude of this initial value depends more on the metal than on the liquid. The following table holds for solutions of KC1 or KBr and gives the thickness of the double layer deduced from the forrnula-t = l/4n-C, where C is the initial capacity. t in t,erms of Metal. 1 P*P-I-- --Nickel Aluminum Gold . Silver 1-04 0 *67 0 *06 0 *02 When dimensions so small as these are reached the validity of the method of representing the phenomenon as due to two uniform layers of electricity is very doubtful. The values of t in the case of gold and silver are comparable with the diameters of the molecules them-selves and thus t can only be regarded as a conventional length re-presenting the thickness of an artificial condenser by which the real molecular arrangements may be approximately imitated.L. Lorenz (Pogg. Ann. 140 644 1870) has also based upon electrical theory an estimate of the distance between neighbouring water molecules. He concludes that it is < 0.1 p.p. A very interesting paper has lately been published by 0. Wiener (Wied. Ann. 31 629 1887) in which he attacks the problem of the determination of the thickness of the thinnest metallic plate which affects reflected light in the same way as a thick plate of the same metal. It is well known that in general when light passes from a less dense to a more dense transparent medium the phase of the reflected ray is altered by half a wave-length. This is proved by the fact that the centre of Newton’s rings as seen by reflected light is black.For the difference in the phases of the rays reflected from the front and back surfaces of the film respectively depends partly on the thickness of the film and partly on any change of phase which the rays may undergo on reflection or refraction. As the film becomes very thin the difference in the paths of the two rays due to its thicknes 246 RUCKER ON THE becomes negligible and thus if the phase were not affected by reflection or refraction the rays reflected from the centre of the rings where the film is thinnest would be nearly in accord or the centre would be bright when viewed by reflected light. The fact that the centre is dark is explained by the assumption that when a ray of light, passes from a less dense to a more dense transparent medium the phase of the reflected ray is altered by half a wave-length.When light is reflected at a metallic surface an alteration of phase also takes place but it is not necessarily half a wave-length and it is on this peculiarity that Wiener’s method is based. I n the light reflected from a thin film of air enclosed between the two glass plates those rays will be wanting for which the difference of phase produced (1) by the difference in the lengths of the paths of the rays reflected at the first and second surfaces and (2) by the change of half 5t wave-length produced on reflection at the air-glass surface is an odd multiple of half a wave-length. In the spectrum of such light dark interference bands will be visible corresponding to the missing rays.If the second surface had been silvered (the thickness of the air film remaining unaltered) the effect of the first of the above two causes would be the same as before but that of the second would be different. Hence the particular kind of light for which the total retardation was previously an odd multiple of the half wave-length would no longer satisfy that condition and the interference bands in the spectrum would occupy new positions. If the second surface had been partly silvered two contiguous spectra could be obtained in which the interference bands appeared broken. I n the experiments with which we are specially concerned Wiener proceeded as follows :-A thin film of mica was partly covered by R second with a straight edge. Silver was deposited on it by discharge from a silver electrode (Wied.AWL 29 353 1886). The layer thus formed was thickest in the centre and thinned away gradually. When the covering mica was removed the silver film was bounded on one side by a straight line. Thus when light was reflected from th RANGE OF MOLECULAR FORCES. 217 film on to the slit of a spectroscope (the silvered side being furthest from the instrument) two spectra were seen side by side as is shown in the figure (p. 246). The displacement of the interference bands varied with the thickness of the film but became constant when the thickness exceeded a certain value. It was measured for certain parts of the spectrum at a number of points the positions of which on the mica were determined. The silver was then converted into silver iodide, and the displacement of the interference bands was again determined at the selected points.From this latter measurement the thickness of the iodide and therefore of the original silver film could be deduced by formulE for the discussion of which I must refer to the original paper (Zoc. cit. p. 664). Curves were then drawn showing the rela-tion between the thickness of the silver and the change of phase pro-duced by it. Curves I 11 and These are reproduced in the figure. I11 were obtained by the same mirror but by observations in different parts of the spectrum. Curve I corresponds to the orange (X = t;47), I1 to the green (X = 534). and I11 to the blue (X = 455). The re-tardation increases very rapidly for the blue less rapidly for the other colours till a thickness of about 4 p.p.is attained. Afterwards it alters more slowly and is nearly constant at the greatest thickness for which the measurements were made viz. 12 p.p. Observations made with another mirror confirmed the result t,hat the change of phase reached its maximum value for a thickness of about 12 p+ but indicated a more uniform rate of increase. Herr Wiener ascribes this difference to a slight oxidation of the silver films. The smallest thickness for which any displacement of the bands could be observed is estimated as rather less than 0.2 p.p. We have now reached the point at which we may investigate the inferior limit to the range of molecular forces viz. the so-calle 248 RUCKER ON THE radius of the molecules. This part of my subject has been so fully discussed by Sir William Thomson (hTatumZ Philosophy Thomson and Tait Pt.11 495 1883; Proc. Roy. Instit. 1883 ; Exnw's Rep., 21 182 1885) and 0. Meyer ( D i e Kir~etiscke Theorie der Gase, 225 1877) that it will be unnecessary f o r me to reproduce their arguments in full. I shall therefore content myself with shortly stating their results and describing at greater length a more recent method developed by Dorn and Exiier. Sir William Thomson (Natural Pldosophy 502) concludes that the diameter of the gaseous molecule cannot be less than 0.02 p.,u., and that the distance from centre to nearest centre in solids and liquids may be estimated a t from 0.07 to 0.02 ,K.,u. He points out that when plates of zinc and copper which are con-nected by a metal approach each other work is done in virtue of the attraction caused by their assuming different electrical potentials.If the plates are split up into an increasing number of thin layers and arranged Zn and Cu alternately so that the thicknesses of t.he plates and of the intervening spaces are equal the work done will vary as the square of the number of plates. I f the thickness i n question were 0.1 p p . the heat-equivalent of the work done would be sufficient to raise the temperature of the metals by 62" C. if it were 0.025 p.p. the heat would suffice to raise the mass through 992" C. The conclusion is drawn that the molecules of Zn and Cu are pro-bably a t least 0.1 p+. and certainly more than 0.025 p . ~ . in diameter. Again when a liquid film is stretched work is done upon it and it.is also cooled. To keep its temperature constant heat must be supplied, and if the thickness were reduced to 0.05 p.p. the heat-equivalent of the total amount of energy imparted to the film would be about twice the latent heat of steam. As it is incredible that the film could absorb so large a quantity of energy and yet remain in the liquid state it is certain that if it could be reduced to this extreme tenuity, the work done in stretching it would cceterisparibus be less when it was very thin than when it was relatively thick. Hence the surface tension must diminish before the thickness of the film is 0.05 p.p., and Sir William Thomson thinks t]hat there cannot ''be any consider-able falling off in the contractile force as long as there are several molecules in the thickness.It is therefore probable that there are not several molecules in a thickness of " 0.05 p p . From a consideration of the transmission of light t'hrongh transparent bodies he also con-cludes that the distance between the centres of contiguous molecules i n solids and liynids is greater than 0.05 pp. The fourth method used by Sir William Thomson is based on the theory of gases. An important formula has been deduced by Clausius, and in a slightly different form by Maxwell which establishes RANGE OF RIOLECULAR FORCES. 249 relation between the diameter of the molecule (d) the mean free path (L) and the ratio of the total volume of the molecules to the volume of the gas (21). It may be written d = 6J%L.The value of v which is called by Loschmidt the condensation coefficient has been obtained in various ways. Sir William Thomson concludes from the general results of experiments on the condensa-tion of gases that a gas could not be made 40,000 times denser than it is under ordinary atmospheric pressure and at ordinary temperatures. Loschmidt (Sitxungsber. Wien. Akad. m a t h Classe 52 Abt. 2 404, 1866) made use of Kopp’s formula-specific volume = molecular weight divided by the density at the boiling point-to calculate the densities in the liquid state of gases which had not then been liquefied. He assigned to the various elements specific volumes somewhat different from those selected by Kopp. Thus assuming those of oxygen and nitrogen to be 11 and 12 respectively the calculated densities are 16/11 = 1.4545 and 14/12 = 1-1666.Hence taking air as a mixture of four parts of nitrogen and one of oxygen he calculated the density in the liquid state to be 1.224. If the molecules are spheres they will when packed as closely as possible occupy a space which bears to the sum of their volumes the ratio 1-17 1. He assumes that in a liquid they are closely packed and deduces as an approximation to the true density 1.224 x 1-17 = 1.5 say. Hence v = 0-001293/1.5 = 0.00086. He takes as the value of the mean free path 140 p.p., whence d = 1 p.p. If however we use the value of L given by Meyer ( D i e kinetische Theorie der Gass l40) viz. 95 p.,u. we get d = 0.68 p.p. 0. Meyer (Thenrie der Gase 225) employing a similar method for nine substances the density of which is known both in the liquid and gaseous states by direct experiment found Talues for the molecular diameters which lie between 1.18 p.p.for N,O and 0.44 p p . for H,O. Dorn ( W i d Arm. 13 378 1881) and more recently Exner (Rep. der Phjysik 21 425 1885) have obtained the value of the so-called condensa tion-coefficien t v in another way. Clausius ( D i e mechanische Behaizdlmy der Electricitat I11 Abschnitt) has given a formula which connects K the specific inductive capacity of a dielectric and ZI as above defined on the assumption that the molecules of the dielectric are conductors and are surrounded by a non-conducting medium. This formula is-Hence v > 25 x According t o Maxwell’s electromagnetic theory of light if n is the TOL.LXII. 250 RGCICER ON THE Air H2 . GO,. . co N,O refractive index of the dielectric for r a p of infinite wave-length K = u2 a t all events to a first approximation. This equation is not satisfactorily fulfilled in the case of liquids or easily condensible gases, partly perhaps because our knowledge of the law of dispersion is insufficient to enable us to calculate the value of PZ. from the refractive indices of the comparatively short luminous and dark waves which have been studied experimentally. In the case of gases in which the dispersion is very small this difficulty is not met with. As the specific inductive capacity is also very nearly unity the experimental difficul-ties which attend its determination are great.The first measurements of this kind were made by Boltzmann and Professors Ayrton and Perry. More recent observations of Klernen@i6 are in good accord with the results obtained by Boltzmann. The agreement between the values of /Kand of n as determined by Mascart is not satisfactory f o r vapours but is very close in the case of the morc perfect gases. The following table is abstracted from that given by Klemen6i6 (Exner’s Rep. 21 611 1885) :-1 *000255 1 *000132 1 -000473 1 -00034.5 1 *000 4.97 1 d K . Boltzrnann. --- I KlemenEiE. I -I---1 -000347 1 -000579 n. 1 ‘000293 1*000139 1 ’00e454 1 -000338 1 a000516 This table shows that the value of 2 may be approximately deter-mined in the case of gases for which we know either K or n. As TI is the ratio of the space occupied by the molecules to the t’otal volume of the body of which the former is a const,ant and the latter varies iiiversely as the density (8) of the substance it is evideIit that for each substance 1118 should be a constant.Hence (n’ - l)/S(n2 + 2) shonld be the same a t all temperatures and for all physical states of the same substance. This result has been obtained independently from optical consiclera-tions by H. A. Lorentz ( W i e d . Ann. 9 641) and L. Lorentz ( W i e d . Aszn. 11 70) and has been tested experimentally by the latter and Prytz (Wied. Ann. 11 104) in a large number of cases. Although the refractirc indices are those for D and not for waves of iufinite length the agreement is very close. 1 give in the following table as samples the first three substances mentioned in the final tables of these two observers.The number RASGE OF MOLECULAR FO LLCES. 251 Substance, compared are the values of (a2 - l)/8(n2 + 2) for the same sub-stance in the liquid and gaseous states :-Molecular Tolurne, 10-5 x Substance. I- --E t)liyl ether . Ethyl alcohol. . Water . Methyl acetate. Ethyl forrnate . Methyl alcohol Observer. Liquid. -~ 0 *30264 0 -28042 0’ 20615 0 ‘2567 0 ‘2375 0 ‘2437 Vapour. 0 * 3068 0.2825 0 * 2068 0 -2559 0 2399 0.2419 The following table contains the values of z1 for some of the ele-ments. From Avogadro’s law it follows that these numbers are pro-portional to the volumes of the molecules ; and if we divide them by the number of atoms in the molecule we obtain numbers proportional to the atomic volumes.In the case of H, ZI was determined from the specific inductive capacity in all other cases from the refi-active index. I n this and the next table I quote from Exner. I I-- -Hz. N2 . 0 2 . c1 . 84. . P‘j . . . . . . . . . . . . . Hg C (from CO - 0) 8 . 8 20 18 51 108 91 37 -Atomic volume, 10-5 x 4 -4 10 9 25 27 23 37 14 From these atomic volumes it is of course possible to calculate the molecular volume of any compound of these substances. Thus the molecalar volume of water = 8.8 + 9 = 18 nearly. obtained from K in the cases of the first five substances and from n in that of the others, together with the calculated values deduced from the above atomic volumes :-The following table gives the values of s 252 RUCKER ON THE Substance.Air CO NzO CHj . C2Hj . NH . Roo . NO H2S HC1 C,N . so v (observed), 10-5 x 17*[20] 31 33 31 44 26 17 20 43 30 56 44 v (calculated), 10-5 x 19 32 34 32 45 23 18 19 36 29 48 45 These results on the whole confirm the accuracy of the physical meaning of the expression (nz - l ) / ( n z + 2) and tend to show that the diameter of the molecule is the same in the liquid and gaseous states. It is important to note however that from the theoretical point of view there is a good deal of confusion. The meaning of the expression (K - l)/(K + 2) is deduced from an electrical theory put forward by Clausius.It should only be equivalent to (w2 - l)/(nz -+ 2) when v is calculated for waves of infinite length and as a matter of fact K and n2 are not eqml for most vapours when n has a value proper to any of the visible rays. If then (I( - 1)/8(K + 2) is really the same for a liquid and its vapour for neither of which n, is known we should not prim& facie expect that (nZD - l ) / S ( ~ 2 ~ + 2) would be the same for both. Nevertheless experiment shows that the variations produced in this expression by the passage from the liquid t o the vaporous state are less than the discrepancies due to the imper-fect agreement between the values of K and w2 in the case of most vapours for which both have been determined. I n cases where K is not = nz the value of v deduced from n2 is to be preferred.Thus the specific inductive capacity of flint glass as determined by Dr. Hopkin-son (PTOC. Roy. Xoc. 43 161) is 9.5 which makes 21 nearly = 0.8. I f we assume the refractive index to have been 1.7 we get 21 rather less than 0.3 which is in far better agreement with the results obtained from gases. I n the case of conductors the values of K are very high. The annexed table gives the value of v for several liquids calcu-lated directly from K and ,n2 as determined by Dr. Hopkinson (Zoc. cit.). The value is also given deduced from the atomic volumes of the gases, * This number appears to be incorrect. Boltzmann’s value for K is l%OOti90, which gives = 20 x This will be used hereafter RANGE OF MOLECULAR FORCES.253 CSHlo C,jH,j C,Hlo CloH12 C,H, viz. 14 x 10” for C and 4.4 x the chemical formula of which is C,H, we have-for H. Thus for the substance 2.05 1.9044 0.260 2-38 2’2614 0.325 2.42 2.2470 0.321 2.39 2’2238 0.317 2.25 2’2254 0.294 D 2 = (14n + 4 . 4 ~ ) 1 0 - ~ 12n x 0-00008961 L1 where D is the density of the liquid. Substance. -Amylene . Benzol . . . Toluol . . Xylol . . . . Cymol . . . . I- I-I-4P”-0 -232 0 -296 0 -291 0 -290 0 -290 v calculated. --0 ‘237 0 *278 0 -286 0 *284 0 *295 In these cases then all three methods of calculating v indicate that from one-fourth to one-third of the volume of the liquid is filled with matter. Another interesting point is that this method of regarding the formula (mz-l)/S(n2 + 2) enables us to assign a physical meaning to the specific refraction of a substance.I n the above calculations it has been assumed that the atomic volume of a substance is the same whatever the nature of its union with the other atoms may be. Landolt however (Liebig’s Annnlen, 213 1882 75) has undertaken a careful comparison of specific refractions calculated by the ordinary formula (n-l)/8 and by (nz-1)/ij(n2 + 2). He finds that the latter is more constant when the values obtained for the liquid and gaseous states are compared and he calculates the specific atomic refractions by means of it. He finds it necessary to assign different values to 0’ and O” which from the point of view we are discussing indicates a dieerenee of atomic volume.It must also be remarked that a very low value of the specific inductive capacity of air when the pressure was 0.001 mm. has been obtained by Professors Ayrton and Perry which might if confirmed by future experiment affect the questions we have been discussing. The fol-lowing table of their results is abridged from Ayrton’s Practical Elec-tricity p. 310. The letter k indicates that the specific inductive capacity of air at $60 mm. is taken as unity. The numbers which refer to air are alone extracted 254 RUCKER ON THE Approximatre pressure in mm. 0 *001 5 760 k. 0 *994* (about) 0.9985 1 ~0000 They have in a pamphlet " On Certain Modifications that must be Introduced in the E'undamental Notions of the Mathematical Theory of Electricity," p.5 proved that if 6 be the density referred to air a t 760" mm. and 0" C. as unity if 1.000294 be the refractive index of air under the same standard condition referred to that of a vacuum as unity and if k be defined as above-0.0005888 + 1 1.000388 " k = This expression is obtained by Biot and Arago's formula (nz-l)/a = constant but a practically identical result will be attained if we use instead the expression employed by Exner. It follows that k has a limiting value when 6 = 0 such that if k is the specific inductive capacity of a vacuum referred to t h a t of air at 760 mm. as unity, k = 1/1*000588 = 0.999412. At 5 mm. k = 0.999416 as givenby the formula. This agrees with the value obtained by Boltzmann viz., 0.99941 (Practical Electricity loc. cit.) but is not in such close agreement with that obtained by Ayrton and Perry themselves.The difference might easily be ascribed to errors of experiment but the value 0.994 when the pressure was 0.001 mm. was obtained in a later research (Rep. IBril. Ass. 1880.) Its accuracy is inde-pendent of that of the measurements a t a pressure of 5 mm. and as far as I am aware no other observers have carried out experiments in gases of such extreme tenuity. It is therefore much to be desired that further observations should be made on the specific inductive capacity of air a t low pressures. The importance of such a research would be enhanced from the fact that it has been pointed out by Professor Fitzgerald (Xep. Brit. ASS., 1880 Zoc. cit.) that the values obtained for the capacity of an air condenser between " about 0.02 and 0.2 mm.pressure bear a general resemblance to those obtained for the Crookes' force." For my present purpose however it is snficient to remark that if the ratio of the specific inductive capacities of air at pressures of 0.001 and 760 mm. is about 0.994 1 then either Maxwell's theory fails when Professor Ayrton informs me that that giren in Practical Electrirify viz. 0.94 is a misprint. * This number is correct RAKGE OF MOLECULAR FORCES. 255 applied to rare gases or the refractive indices of air a t these pressures are in the ratio JO-994 1 that is 0.997 1. Now the fact that the re-fractive index from a vacuum to air a t atmospheric pressure is about 1*000294 is proved iiot only by direct experiments on air of different densities but also by the agreement between the observed and calcu-lated results of the effect of atmospheric refraction on the apparent positions of stars.Hence if we admit the validity both of tbe expe-rimental determination of the specific inductive capacity of air a t a pressure of 0.001 mm. and of the application of Maxwell’s theory of this case we must conclude that the refractive index of highly rarefied air referred to that of a vacuum as unity is 0.997 x 1.000294 = 0.997293 and that it is about 0.27 per cent. less than that of a vacuum. The alteration in the ordinary refractive index of air which would be required to make this quantity > 1 would make the calculated atmospheric refraction nearly ten times greater than that which is actually observed.It is therefore evident that either the experimental result is affected with error or that Maxwell’s theory does not apply to a rare gas. I n either case the conclusions arrived a t need not affect the application of Maxwell’s theory to sub-stances for which K = n2 and f o r which therefore it appears to be a t all events an approximation t o the truth. obtained by Exner are remarkably confirmed by those deduced from the theory of Van der Waals. In the general relation between pressure volume and temperature given by him a constant b occurs which is according to Van der Waals = 471 and, according to 0. Meyer = $ 4 2 ~ . Meyer deduces it from a comparison between the terms of Van der Waals’ formula and the constants of a similar empirical formula of Regnault’s.The values so obtained are of the same order as those given by other methods, but I do not think that hleyer’s plan is as satisfactory as those adopted by Van der Waals himself as it largely depends on the valnc of a very small constant in the empirical formula. Van der Waals makes two comparisons-the one with Regnault’s observations (Die Continuitut &c. 73 to 79) and the other with Cailletet’s results (Zoc. cit. 98 and 99) and he shows that the constants obtained by the former method produce a fair agreement with the observations of Andrews (Zoc. cit. 80). The table is obtained by taking these results (comp. Meyer Kine-tische Theorie 75) and reducing all values to the standard pressure of one atmosphere. The values of The value of b may be obtained in several ways 256 RUCKER ON THE Mean 1 Value of b from Value of v according to I Regnault.0*00195 1 0.00049 0 *00050 0 *00012 0 *0023 0 -00057 I- -0*00035 0.000088 0 *00041 Air .E€z . . . . . . COa . . . . , Cailletet. --0.00050 -0*00195 0 -00049 0 -0023 0. Meyer, The value of b for SO2 deduced from experimenh by Cagniard de la Tour is 0.0032 which leads to v = 0.0006 according to Meyer’s formnla. As these early observations were probably not so accurate as the others we are discussing I shall not make use of his results, also as Meyer’s relation between b and v appears to be the best I shall hereafter employ it only. Before discussing this table further I must point out that there are some slight errors in the books which deal with the subject and which account for discrepancies between the figures as given by others and hy myself.The numerical value of b which is proportional to the ratio of the volume of the molecules to the volume of the gas under standard conditions increases with the standard pressure and may be taken as proportional to it. The values obtained by Van der Waals from Regnault and Caille-tet’s results are referred to pressures of 1 m. and ‘760 mm. respectively, Ruhlmann (Xechanz’sche Warmetheorie 2 244 Vieweg und Sohn, 1885) reduces them all to a pressure of 1 metre but in so doing he multiplies the numbers which are referred to an atmosphere by 0.76 instead of dividing. Thus as corresponding to 0.00198 he gives 0.0015 and so on.By this mistake he conceal8 the practical identity of the values obtained by Van der Waals. The value of b for CO, referred to a pressnre of 1 m. is 0.003 (Die Continuitat &c. 74). Van der Waals calculates it for 1 atmcisphere on p. 80 and finds b = 0.0023. Yet Meyer (Kinetische Theorie 231) treats this value as though it referred to the larger pressure and finds that for COz d = 0.18 p.p. ilistead of 0.23 p.p. which is the correct value deduced from his other data. I point out these errors only to prevent confusion on the part of those who might happen to compare the different tables of values. In the next table are the values of v obtained from the specific inductive capacity the refractive index and the theory of V#n &r Waals :-0. Meyer himself makes a similar mistake RASGE OF MOLECULAR FORCES.--Air . Table of Values of v. Calculated from K as deter-mined by Calculated from n, Mascart. Boltzmann KlemendiE 10-5 x 10-5 x 10-5 x ----20 20 20 H2 8.8 8 -8 coz . 33 I 32 257 9 . 3 30 Calculated from b Van der Waals and 0. Meyer, 10-5 x 35 41 8.8 Without laying stress on the extraordinary similarity between the values of 21 obtained in the case of H from the dynamical theory of gases and from electrical and optical formulae I think that the agree-ment as to the order of the magnitudes of v calculated by such various methods is very strong evidence that they are approximately correct. It will also be observed that they are intermediate in value between the superior and inferior limits given by Loschmidt and Sir William Thomson respectively.Loschmidt regarded the liquid as formed of molecules in contact an assumption which could not give too small a value for v ; Sir W. Thomson selects a condensation coefficient which he is sure is not large enough. We thus get in the case of air-Superior limit (Loschmidt) 86 x lod5 Actual value calculated from b 35 x lom5 79 9 , n . . 20 x 7 9 , K 20 x 10-5 2.5 x Inferior limit (Sir W. Thomson) We may therefore conclude that the space occupied in the sense previously defined by the molecules in air at 0" C. and 760 mm. is about one five-thousandth (0.0002) of t,he volume of the gas. As Loschmidt's calculation is based on the assumption that in a liquid v= 1/1.17= 0.85, and as Exner's value in the above table is 2O/% of his it follows that in liquid air the value of v would be about 0.2.Very similar values are obtained for substances which can be liquefied easily. Thus the observed value of v for water vapour is 0.00017. This is referred to 0" C. and 760. But at 0" C. and 4.6 mm. (the maximum tension of aqueous vapour at that temperature) the volume of saturated steam is 210,660 times the volume of the liquid. Under standard conditions this would be reduced to 210,660 x 4*6/760 = 1275 258 RUCKER ON THE Substance. Viscosity. Hence for liquid water 21 = 0.00017 x 1275 = 0.22. We conclude that in liquids about one-fifth only of the total volume is filled with matter which is in fair accord with the numbers before obtained from Hopkinson’s results.To calculate the diameter of a molecule we must know not only v but also L. This may also be determined by three independent methods of experiment viz. by the determination of the coefficients of viscosity diffusion and thermal conductivity. As the values of the coefficient of viscosity given by Meyer are not reduced to 0” C. I take the values of L deduced from these given by Ruhlmann (Me-c7~zanische Wai-rnetheoyie 227). For those which depend on diffusion, I quote Stefan’s deductions from Loschmidt’s experiments as given by Exner (loc. cit. 450). Taking the coefficients of thermal con-ductivity determined by experiment by Kundt and Warburg, Winklemann and Stefan as given by 0. Meyer (Zoc. cit. 194) I have calculated back to the coefficients of viscosity by the formula f = 1*53qc where 5 and q are the coefficients of conductivity and viscosity and c is the specific heat a t constant volume and have then deduced L from the coefficient of viscosity thus calculated.The results are given in the following table and prove that there is a t all events no doubt as to the order of the magnitude of L. Thermal conductivity. Diffusion. Values of L. I L in p.p. calculated from l--l--I-- --Air R3 co . co . N,O 99 194 66 97 66 ~ 71. 139 50 65 42 110 186 55 106 59 We are now if the various theoretical assumptions are allowed in a position t o calculate the diameter of a molecule of air H,. o r Con, by three absolutely independent met,hods. We may combine the values of 8 obtained from the specific inductive capacity the refrac-tive index and the theory of Van der Waals with the values of L deduced from the coefficients of viscosity diffusion and thermal con-ductivity respectively.The results are showu in the following table : RANGE OF MOLECULAR FORCES. 259 Substance' Diameter of gaseous molecule in p.p. calculated from Specific inductive Refractire index Expansion and thermal and diffusion. conductivity. capacity and viscosity. Air. . . . . . . . . . . . . . Hz coz . . . . . . . . . . . . . 0 -17 0 *14l 0 .18 0 -12 0.11 0 *13 0 -33 0.14 0 -19 Without insisting too much on an agreement which can be exem-plified in the case of a few gases only and which would probably not be exhibited by the results of experiments on vapours it is not too much to say that it cannot possibly be fortuitous and that it leaves very little doubt that the so-called diameter of a gaseous molecule is of the same order of magnitude as 0.2 ~ .p . I n conclusion I think i t may be well to attempt to class the phe-nomena which have been observed in very thin layers of matter and the results of calculations on the size of molecules in the order of the magnitudes involved. It is probable that such a statement will have to undergo much correction in the futnre but i t may be useful and suggestive in the present. A t all events I think it will show that the time has passed when any estimate however rough as to the magnitude of' molecules or of the radius of molecular action is to be welcomed.We know now what the order of these magnitudes is, and observations are wanted based on reliable methods and leading to definite results. I n drawing up such a table I shall therefore reject measurements which appear to me to be open to very grave doubt. In the first place all results as to the condensation of liquid films 011 solids which lead to values of the radius of molecular action of several hundred or even several thousand micromillimetres must be rejected until they are confirmed by other methods. The onus of proring that the bodies used are not porous not absorbent and not affected with impurities which can unite chemically with or dissolve in, water lies with the invest,igntors who adopt this method. Not only have the observations on agate varnished metals and glass shown that these are grave and probable sources of error but Ihmori has proved that when they are as far as possible got rid of the thickness of the condensed film is very small.The fact that soap films exhibit no trace of change in their surface-tension or other properties till a thickness of about 50 p.p. is reached makes it absolutely incredible that the radius of molecular attraction should have a magnitude o 260 RUCKER ON THE from 500 to 3000 p.p. I n this view I am supported by the opinion of Sir W. Thomson who has laid it down as “ quite certain that the molecular attraction does not become sensible until the distance is much less than 250 micromillimetres ” (Proc. Roy. Inst. 11 Part 111, 415 1887). Important too as the observations of Ihmori and Warburg are, I do not think that they can be used for our present purpose.They refer only to the temporary film and therefore do not afford direct information as to the distance between the surface of the glass and the outermost water layer. This is given by Bunsen’s observations, though it is doubtful what the nature of the attraction by which the water is held may be. I shall also reject calculations based on the polarisation produced by gases. The uncertainty as to the density of the films deprives these estimates of all value. The same objection does not however, apply to measurements of the thickness of the electrical double layer. I shall therefore include these and the results of observations on the polarisation of metal by metal subject of course to t,he criti-cisms which I have already made.I include Plateau’s results on account of their historical interest. Table of Properties of Thin Films and of Molecular Mag?iitudes. 118 p.p. Superior limit to the radius of molecular action deduced from Plateau’s experiments on the pressure of a soap bubble by Maxwell’s theory that the surface-tension first diminishes when the thickness of the film = p. 96-45 p.p. Between these limits the thickness of a film begins to be unstable, Hence the radius of that is the surface-tension begins to diminish. molecular action must be < 96 p.p. and > 22 p.p 59 p.p. Superior limit to p deduced by Plateau on the assumption that the surface-tension first diminishes when the thickness = 2p.50 p.p. Value of p deduced by Quincke from experiments on capillary elevation. Hence the thickness should begin to be unstable when it is 100 p.p. or 50 p.p. according as we adopt Plateau’s or Maxwell’s views. There is therefore a remarkable accord between Quincke’s result and the superior limit Probably the truth lies between the two RANGE OF MOLECULAR FORCES. 261 t o the unstable thickness (96-45) obtained by Reinold and Rucker from experiment. 12 p.p. Average thickness of black soap-films measured by two independent methods. As the tension of a black film is equal to that of a thick film the surface-tension which begins to diminish at 50 p.p. must increase again and reach its original value at 12 p . ~ The fact that each black film is of uniform thickness proves that the surface-tension is still increasing at 12 p.p.which is the lower h i i t to the range of unstable thickness. This is also about the thickness below which, according to 0. Wiener a thin silver plate will no longer produce the same effect on the phase of reflected light as a thick silver plate would do. 10.5 1A.p. Thickness of t'he permanent water film observed by Bunsen on unwashed glass at a temperature (23" C.) at which the vapour pressure of water is small. 4 p.p. to 3 p.p. Average distance from centre to nearest centre of molecules in gases under standard conditions calculated by Meyer. If Exner's values of v be accepted the distance would be more nearly 2 p.p. 3 p.p. to 1 p.p. Thickness of metal films required to polarise platinum completely according to Oberbeck.1 p.p. to 0.02 pp. Thickness of electric double layer according to Obei-beck and Falck. Lippmanzl found 0.3 p . p . 0.2 p.p. Smallest thickness of silver which affects the phase of reflected light. 0.14 to 0.11 p.p. Diameter of gaseous hydrogen molecule as given by combining-(1.) The specific inductive capacity and coefficient of viscosity. (2.) The refractive index and coefficient of diffusion. (3.) The law of expansion and the thermal conductivity. 0.07 t o 0.02 p.p. Average distance bet ween centres of molecules snpposed arrange 2 62 SCHUNCTL ON Ti-IE SUPPOSED IDENTITY uniformly in liquids and solids according to Thornson. limit found by L. Lorenz wils 0.1 p.p. A superior 0.02 p,p. Inferior limit to the diameter of a gaseous molecule according to These results may be shortly summed up as follows:-Thomson. 118 96-45 59 50 12 12 10-5 4-3 3 -1 1-0'02 0 *2 0'14-0 '11 0 * 07-0 * 02 0'02 Superior limit to p i I 1 } { 1 Range of unstable thickness begins Superior limit to p . . Range of unstable thickness ends { Action of silver plate on phase of reflected Thickness of permanent water film on glass at 23°C Mean distance between centres molecules in gases at '760 mm. Thickness of metal films which polarise plati-Thickness of electric double layer Smallest appreciable thickness of silver film Diameter of gaseous hydrogen molecule Mean distance between centres of nearest Inferior limit to diameter of gaseous molecule . . Magnitude of p light alters r!?.t } num i liquid molecules,. Plateau. (!Maxwel!). R,einold and Riicker. Plateau. Quincke. Rcinold and Itiicker. Wiener. Bunsen. 0. Meyer. Oberbeck. Lippmann and Oberbeck. Wiener. Exner. 0. Meyer. Van der Waals. W. Thornson. W. Thomson

ISSN:0368-1645    

DOI:10.1039/CT8885300222

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年代:1888

数据来源: RSC

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2 62 SCHUNCTL ON TEE SUPPOSED IDENTITY XXII1.-On the Supposed Identity of Rutin and Quercitrin. By EDWARD SCHCNCK Ph.D. F.R.S. RUTIN a crystalline yellow colouring matter was discovered by Weiss (Planrm. Centr. 1842 903) who obtained it by treating the leaves of Rzcta graveoZeus with alcohol or acetic acid and described some of its properties. It was next examined by Borntrager (Annnlen 53 385) who confirmed the statements of his pre-decessor and also analysed the substance and its lead compound. Rocbleder and Hlasiwetz (AnnaZen 82 197) obtained from the capers of commerce the flower-buds of Cupparis spinosa a colourin OF RUTlN AND QUERCITRIN. 263 matter having the properties of rutin and the same composition as that given by Borntrager and in 1858 (Jlanchester Nemoirs 2 Ser., 15 122) I showed that the same substance could be easily procured from the leaves of common buckwheat Polygonurn Fugopyrum.I n a second investigation undertaken by himself Hlasiwetz (Annalefi 96, 123) found that by the action of strong acids rutin is decomposed, yielding quercetin and sugar and the quantities of the two latter formed by its decomposition being very nearly those required in accordance with the then accepted formula of quercitrin he con-cluded that quercitrin and rutin were identical. This conclusion seems to have been generally adopted by compilers of handbooks and dictionaries. Afew years later however Zwenger and Dronke (AiznaZeiz 123,145) endeavoured again to prove that the t w o bodies were really distinct, and that though they were very similar in many respects they differed with regard to some of their properiies as well as in composition.The conclusion they arrived at was that whereas quercitrin was a corn-pound of 1 mol. of quercetin with 1 mol. of sugar (dextrose?) minus water rutin contained 1 mol. of quercetin and 2 mols. of another kind of sugar. This conclusion is an approximation to what I believe to be the truth. If however it had been known a t the time that the sugar formed by the decomposition of quercetin is isodulcite, C6H1406 and not glucose and that rutin yields the same kind of sugar as quercitrin the subject would have again been involved in the obscurity which the authors had attempted to remove. Among the earlier memoirs on the subject there is one by Stein (J.yr. Chem. 58 399; 85 351; 88 280) who obtained from so-called Chinese yellow berries the unexpanded flower-buds of Xoplzora juponica a colouring matter which he considered to be identical with rutin from rue. Foerstm (Ber. 15 214) however who has recently examined this substance supposes it to be distinct and has accor-dingly named it sophorin. The properties of quercitrin and of its products of decomposition having of late years been minutely studied and its composition accurately ascertained by Liebermann and Hamburger and others and rutin so far as I know not having been anew examined it seemed to me that i t might be interesting again to compare the two substances, and if they were found to be distinct to ascertain wherein the differ-ence consists.The quercitrin which I used was prepared in the usual way from quercitron bark. The rutin was obtained from Polygonuyn fago-yyvi~nz leaves and though it had been kept for many years had undergone no change and seemed quite pure. The yellow colouring matter from buckwheat leaves has the sam 264 SCBUNCK ON THE SUPPOSED 1L)ENTITY properties as the rutin from garden rue but the latter contains some impurity which is not easily removed a fact already pointed out by Zwenger and Dronke. Rutin even after numerous crystallisations, retains a faint greenish tinge and may be described as being of a pale primrose-yellow whereas the colour of quercitrin inclines more to lemon-yellow. I n the following table the reactions in which the two substances show a marked difference are placed side by side ; the reactions in which no difference could be observed are omitted.@cercetin. Soluble in 280 parts of boiling water. Soluble in 3.5 parts of boiling absolute alcohol. SoIuble in 125 parts of ordinary ether. Easily decomposed when its watery solution to which sul-phuric acid has been added is boiled. When a dilute alcoholic solu-tion containing silver nitrate is shaken up with three times its volume of ether the latter acquires R crimson colour; the colour soon fades metallic silver being a t the same time deposited. An aqueous solution gives with stannous chloride a light red pre-cipitate. By the action of bromine crys-tallised tetrabromoquercitrin is formed. By the action of chlorine on the substance suspended in water a yellow body is formed which contains chlorine and is insoluble in water but soluble in alcohol, the alcoholic solution leaving, Rutin.Soluble in 170 parts of boiling water. Soluble in 5 parts of boiling absolute alcohol. Soluble in 335 parts of ordinary ether. Very slowly decomposed by the action of boiling dilute sul-phuric acid. A dilute alcoholic solution con-taining silver nitrate shaken up with ether imparts to the latter a light yellow colour. An aqueous solution gives with stailnous chloride a bright yellow precipitate. By the action of bromine only amorphous products are obtained. On passing chlorine through water with rutin in suspension, the latter dissolves entirely. The solution on evaporation over sulphuric acid leaves a brown amorphous residue which has a OF RUTIN AND QUERCITRIN.265 Rutin. Quercitrin. I on evaporation an amorphous residue. ~ astringent taste and shows some ' of the reactions of tannin the watery solution giving a dark-green coloration with ferric chlo-ride and a flocculent precipitate with gelatin. Rutin dyes the same colours on mordanted calico as quercitrin the alumina mordant acquiring a yellow and the iron mordant a more or less intense olive colour but using equal weights of both substances the shades produced by quercitrin are perceptibly darker. Rutin yielded on analysis the following results :-0*4686 gram of substance dried in the desiccator lost on heating at 130" 0.0186 gram water equal to 3.97 per cent.1.7352 grams substance dried in the desiccator lost on heating at 130° 0.0696 gram water equal to 4.01 per cent, I. 0.5510 gram substance dried at 130" gave 1.0588 gram CO and 11. 0.4748 gram substance dried at 130' gave 0,9152 gram CO and These numbers correspond in 100 parts to-0,2623 gram H,O. 0.2348 gram H,O. I. 11. C 52.40 52-55 H . . 5-28 5-49 On adding sulphuric acid to a watery solution of rutin and boiling, yellow crystalhe needles are deposited consisting of a product of decomposition. The boiling must be continued for some time the decomposition being much more slowly effected than with quercitrin. After cooling the yellow needles are collected and washed. They have the properties of quercetin and also the same composition as the following results of their analysis show :-I.0.5002 gramsubstance heated for 24 hours at 130" gave 1.0896 11. 0.2667 gram substance dried at 130" gave 0.5928 gram CO and 0.3050 gram quercetin from quercitrin gave 0.6700 gram CO and These numbers correspond in 100 parts to-gram CO and 0.1784 gram H,O. 0.0851 gram H,O. 0.1022 gram H,O. VOL. LIXI. 266 SCHUNCK ON THE SDPPOSED IDENTITY Quercetin I. 11. Mean. from quercitrin. C 59.49 60.62 60.05 59.90 H . . . . . . . . 3.96 3.54 3.75 3.74 The formula C2,H,,0, for quercetin requires-C 60.00 H 3-33 By acting on the product from rutin with acetic anhydride and sodium acetate an acetyl compound was obtained crystallising i n white needles and having the same appearance and showing the same melting point as the componnd formed in the same way by acting on the quercetin from quercitrin.The product soluble in water formed along with quercetin by the action of sulphuric acid on rutin is isodulcite. It is obtained from the filtrate after remo.ral of the acid by evaporating to a syrup, dissolving the latter in absolute alcohol adding several times its volume of ether to the alcoholic solution and allowing the liquid after the milkiness caused by the addition of ether has subsided as a syrupy deposit to evaporate slowly. The substance thus obtained has the same crystalline form and general proFerties as the isodulcite from quercitrin. Its melting point is 90-91". The products of decomposition of quercitrin and rutiu with acids being the same there remains only one way of explaining the difference between the two substances and that is to suppose that the relative quantities of the products of decomposition formed differ in the two cases.Now the formula C42H50025 which I would propose for rutin requires in 100 parts-C . . . . 52.83 H 5.24 with which as will be seen the numbers found by experiment agree. According to Zwenger and Dronke rutin dried at 150-160" contains-C . . 52.66 H 5.00 numbers which also correspond with those required by the above formula. The substance dried a t 100" still retains it would appear 2 mols. H,O which are expelled a t 130". According to the formula C,,H,,O, + 2H,O the loss on heating would be 3.63 per cent. Ex-periment as stated above gave 3.97-4.01 per cent. The formula C42H50015 + 2H20 requires-C .. 50.90 H 5.4 OF RUTIN AbD QUERCITRIS. 26'7 The following numbers show the results obtained by various experimenters in the analysis of rutin dried at the ordinary tempera-ture or at 100':-Rochleder Z m e n g e r Boriitrager and Hlaswietz and Dronhe Schunck, from rue. from capers. from capers. from buckwheat. C 50*30 50.15 49.44 49-85 H . . . . 5.60 5-70 5-52 5-88" If the formula given above be adopted then the decomposition of rutin by acids must be represented by the following equation :-C~zH50025 + 4H20 = C24Hie,Oi1 + 3C6H1406. Quercetin. Isodulcite. In accordance with this equation 100 parts of rutin should yield-50.31 quercetin and 57.22 isodulcite. Experiment gave-48.50 quercetin and 55.20 isodulcite ; numbers which approximate to those required by theory and differ widely from the respective amount's 60.76 and 46.08 corresponding with the formula C36H38020 which according to Iiebermann and Hamburger is that of quercitrin.It would appear therefore that whereas quercitrin contains 2 mols. of isodulcite to 1 of quercetin r u t h has 3 mols. of isodulcite to 1 of quercetin. This being admitted the great resemblance subsisting between the t w o substances as well as the differences observed, such as in the degree of solubility and tinctorial power would be easily explained. I have been assisted in these experiments by Mr. Percy Carter Bell, whose services as a skilful manipulator and a careful worker I have much pleasure in acknowledging. f These numbers agree still better with the formula C42Hc50025 + 3H20 which requires in 100 parts-C 50.00 H . 5.55 Tn accordance with this formula the 1055 on heating should be 5-38 per cent. Zwenger ard Dronke found that rutin dried a t 100" lost on being heitted for some tiiiie at lX-ICiO" 5.92 per cent. of water

ISSN:0368-1645    

DOI:10.1039/CT8885300262

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年代:1888

数据来源: RSC

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2 68 XXIV.-On the Composition of Japanese Bird-lime. By EDWARD DIVERS M.D. F.R.S. and MICRITADA KAWAKITA M.E., F.C.S. of the Imperial University T6ky6 Japan. NO results worthy of publication seem to have been obtained in the examination of bird-lime uutil the year 1884 when J. Personne (Compt. rend. 98 1585) made known those obtained by his father and himself. When that paper appeared we ourselves had been for some time occupied with the investigation of Japanese bird-lime and had already obtained results which proved to be in general agreement with those of Personne and yet sufficiently unlike them, and in some respects in advance of them to lead us to continue our work although he had promisedfurther attention to the subject. Up to the present date however nothing more from him has appeared, and we now offer this paper as an extension and partial confirmation of his observations.Bird-lime or tori-mochi is prepared in Japan just as it is in Northern Europe from a species of holly by macerating and pound-ing its inner bark in water and afterwards picking out the fragments of crushed tissue from the viscid mass. Bird-lime exists ready formed in the bark in great abundance and is not apparently modi-fied in any way by fermentative action during its preparation. I n Europe it is prepared from the common or prickly-leaved holly ( I l e a aplLifoliU7?2) but in Japan it is obtained from Mochi-no-ki the I. integra of Thunberg (Prinu,s imtegra H and A.). We are not familiar with bird-lime as prepared in Europe but judging from descriptions Japanese bird-lime is like it except perhaps in not having a greenish hue although of that even we are not certain since the Japanese product may well have it sometimes when quite freshly prepared.Bird-lime is extensively used in Japan as in Europe for catching birds and insects and with the usually attendant cruelty. In manuals of economic botany we find enumerated as peculiar constituents of the holly a bitter principle named ilicine an aromatic resin and bird-lime itself. I n the account of bird-lime given in Ure’s Dictional-y the true substance is not well distinguished from the viscid matter of mistletoe (Viscurn aZbum) examined by Rejnsch from which it appears to be entirely different. Some ProFerties of Japanese Bird-lime. The bird-lime is pde-greyish nearly opaque of faint peculiar d o u r almost tasteless soft elastic tenacious and adhesive to dr ON THE COMPOSITION OF JAPANESE BIRD-LIME.269 surfaces and slightly lighter than water. It can be preserved in water for an illdefinite time without change except on its upper surface. Exposed to air it very slowly turns brown outside and becomes coated with a thin brittle skin. If heated moderately it gives off water and above 100" froths from disengagement of steam. By the loss of its moisture it becomes transparent brown, and while hot of the consistency of cold oil. If now allowed to cool, it remains transparent and forms a soft solid mass elastic tenacions, and sticky as before somewhat resembling Canada balsam in appear-ance. Ether carbon bisulphide chloroform light petroleum and benzene dissolve bird-lime leaving a residue which although of not inconsiderable volume is of little weight.Cold alcohol scarcely dissolves it a t all and even hot alcohol which has some solvent action a t first attacks merely the surface-portion of the mass. The alcoholic solution as it cools deposits a nearly colourless transparent, adhesive matter differing but little from the purified bird-lime itself. Ether is much to be preferred to other solvents because it yields a clear solution whereas carbon bisulphide and the rest give milky liquids owing t o the presence of water. The ether solution mixed with alcohol becomes turbid and deposits a tenacioixs mass. Freed from water and particles of woody fibre bird-lime undergoes scarcely any change when heated up to temperatures below 350° merely becoming slightly fluorescent and a little darker in colour and acquiring a feeble waxy odour.About the melting point of zinc, however it uudergoes destructive distillation in which most of it comes over as fatty acids and fluorescent hydrocarbons of waxy and mild empyreumatic odour and buttery consistence ; very little per-manent gas is formed and only a small carbonaceous residue is left. Bird-lime burns in the air with a bright smoky flame. h'ulphuric acid dissolves it slowly forming a red liquid which blackens only when heated and which when poured into water gives a viscid precipitate like bird-lime but dark-coloured. Boiling nitric acid slowly dissolves it with partial oxidation this solution also yields a precipitate with water.The sulphuric acid solution poured into concentrated nitric acid, and then diluted with water yields a precipitate of it mixture of feebly nitrated compounds. Aqueous solutions of potassium hydroxide only slowly and slightly emulsify bird-lime ; fusion with the hydroxide is attended with much darkening in colour and leaves a mass which emulsifies in water. Potassium hydroxide in strong spirit slowly dis-solves the greater part of purified bird-lime producing a dark-coloured solution. I n this way,-that is by continued boiling with strong alcoholic potash-bird-lime has been attacked by both Personne and ourselves in order to determine its composition. It is not very sensitive to reagents. T 250 DIVERS AND KAWAKITA ON THE The Constituents of BiT-d-lime.Personne has found bird-lime prepared from I. nquijolium t o con-tain water 27 and vegetable de'bris and calcareous salts 23 parts per cent. tlhe remaining and essential part being some caoutchouc the compound ether or ethers of a new alcohol ancl other matters un-determined. The acids o r acid forming the ethers were also not investigated by him. He isolated the caoutchouc by saponifying the ethers with alcoholic potash which left the caoutchouc un-dissolved. Japanese bird-lime is much cleaner than that described by Per-some containing only 2 per cent. of dry-bark fragments and no separate lime salts. Its water content however is larger (probably because it is kept in stock under water) the percentage lost at 110-120" being 38.Caoutchouc forms about 6 per cent. leaving 54 per cent. as the proportion of compound ethers and allied mat,ters. The Bark &.-Of the 23 parts per cent. found in French bird-lime by Personne some 13 parts consisted of calcium oxn1ate.x On boiling out the bark fragments from Japanese bird-lime with sodium carbonate some oxalate was dissolved out but only in emall quantity. The bark burnt t o ashes gave as much as 6.3 per cent. of ash prin-cipally calcareous and largely phosphate but of course with some carbonate ; but as the whole ash was only one-eighth per cent. of the entire bird-lime and as only a little of the calcium salts was oxalate, Japanese differs in this respect remarkably from French bird-lime. The Caoutchouc.-As we have stated the caoutchouc can be sepa-rated by boiling out the purified bird-lime with alcoholic potash and this is the best way of proceeding.It is however difficult to get it quite free from potash and to this end needs to be repeatedly dis-solved in ether and reprecipitated by alcohol. The caoutchouc can also be separated by dissolving the bird-lime in ether and pre-cipitating the solution with 95 per cent. spirit but then only very imperfectly because the main constituent of the bird-lime is also pre-cipitated in part. The caoutchouc of bird-lime is pale-yellow and transparent highly elastic and when heated evolves the well-known penetrating odour. A combustion gave carbon 86.56 and hydrogen 11-31 per cent. so that oxygen to the extent of 2 per cent. was present.Before weighing it out it had been kept for some time at 120-130". It left a trace of ash when burnt. Other and Priwipal Constituents of Bird-lime.-We have not fully isolated these by proximate analytical methods but their general * Not phosphate aa stated in the abstract of Personne's paper in this Journal (46 1365) COMPOSITION OF JAPANESE BIRD-LIME. 2 i 1 pi-operties appear to be those of the partially purified bird-lime ; for when a boiling alcoholic solution of bird-lime is evaporated and cooled, or again when an ethereal solution of bird-lime is mixed with a little alcohol to separate the caoutchouc and then evaporated in either case the solid matter obtained is like the partially puritied bird-lime except in being colourless when deposited from the alcoholic solution.Products of the XaponiJication of Bird-lime and their Isolation.-Saponification with alcoholic potash yields besides the residual caout-chouc firstly the potassium salt of palmitic acid and a very little of that of a semi-solid acid which we have been unable to purify or identify ; secondly two crystalline alcohols; and thirdly a small quantity of a resinozd substance. The separation of these may be carried out in somewhat different ways and is unavoidably tedious. The purified bird-lime is boiled for two hours with potash and 95 per cent. spirit in a flask fitted with a reflux condenser ; and the alkaline solution decanted from the caoutchouc is poured into dilute spirit, by which a voluminous gelatinous precipitate is produced consisting of the alcohols with some of the resinoid body and potassinm palmi-tate.The precipitate is well broken up by stirring collected on a cloth filter pressed and washed with dilute spirit. Three ways of proceeding from this point have been employed by us. In one the precipitate is diffused through dilute spirit stirred well and warmed with calcium chloride solution. The now much less voluminous precipitate is repeatedly washed with water dried, and extracted with ether which leaves the calcium palmitate undis-solved. Spirit of 95 per cent. may be used in place of ether but as it dis-solves out a little calcium salt its use is less satisfactory. On evnporat -ing the ether (or spirit) the alcohols and resinoid body are obtained. A second way of proceeding is to warm the precipitate with water and hydrochloric acid until it has shrunken to a small volume wash repeatedly with water press moderately and extract with light petroleum which dissolves out the palmitic acid and some of the resino’id substame and leaves behind all the alcohols and the rest of the resino’id substance.After treatment by either method the resinoid compound is separated by repeated extractions with warm 80 per cent. spirit. A small quantity of the alcohols at the same time dissolves and may be partly recovered by precipitation with a very little water and extracting the precipitate with 80 per cent. spirit. The third way of proceeding which is simpler in exicution than the others but much less effective is to use 70-80 p;.r cent. spirit in place of the light petroleum in the second way of working.This dissolves out the resino‘id substance as well as palmiti acid. Personne’a method of procedure is to pour the product e,f saponifi 2'12 DIVERS AND KAWAKITA ON THE cation into water to wash the precipitate with much water treat it with acetic acid to neutral reaction again wash dry dissolve in hot 90 per cent. spirit cool and crystallise out the bird-lime alcohol from the solution. We have not found this method to work well on account of the great difficulty in washing properly the voluminous gelatinous precipitate and in just neutralising it with acetic acid. This precipitate contains besides the alcohols and resinojid substance, much acid potassium palmitate to which indeed its bulky natnre is partly due and we have found it far preferable to convert the potas-sium palmitate either into the calcium salt or into free acid as above described.Personne seems not to have recognised the presence of any fatty salt in the precipitate containing the alcohols. Separation of the Alcohols fyom each other and their Puri$cation.-The crude solid alcohols can only be fully separated from each other by fractional extraction with strong spirit repeated until the products obtained are of constant melting point. The alcohols already treated as described with 80 per cent. spirit to remove the resinoid substance, are warmed with successive portions of spirit increasing in strength from about 85 per cent. t o over 90 per cent. each portion of the solvent depositing crystals of the alcohols as it cools and each mother-liquor by successive evaporations yielding a series of other crystalline deposits all similar in appearance.When the last mother-liquors are too small in quantity and too impure to yield a satisfactory product by further evaporation they arc rejected or worked up for the little resino'id substance they contain. The portions of the alcohols least soluble in spirit consist principally of the one alcohol and those most soluble of the other alcohol. By a repetition of the treatment with Epirit the intermediate portions yield other series of deposits of higher and lower degrees of solubility the extremes of which contain the two alcohols. The portions of the less soluble alcohol are sub-mitted to further fractionation until the part undissolved by hot 90 per cent.spirit and that dissolved and deposited by it on cooling have the same melting point. It is then finally dissolved in hot 95 per cent. spirit crystallised out and again tested as to its melting point. The most soluble crystalline deposit consisting principally of the more soluble alcohol requires much further fractionation in order to separate the less soluble alcohol on the one side and the resinoi'd substance on the other so that the ultimate yield of the pure alcohol becomes very small. In fractionating out this alcohol spirit of 85 per cent. i! used but finally this alcohol like the other should be crys-tallised out from 95 per cent. spirit in order to get good crystals. Personne observed the comparative insolubility of the solid alcohol in 80 per ;ent.spirit but making no use of this fact he purified the cake of crude solid alcohol by repented crystallisations from boilin COMPOSlTlON OF JAPANESE BIRD-LIME. 273 90 per cent. spirit. During the piirification he met with a sub-stance of peculiar form visible under the microscope and less soluble in spirit than the solid alcohol and this he found to be gradually removed by repeated crystallisation. We have met with no such substance in Japanese bird-lime. Puri$ication of the Resinoid Compound.-This is found mainly in the 80 per cent. spirit used to wash the crude alcohols after they have been separated from palmitic acid. When this separation has been effected in the second way the spirit contains some fatty acids also.The light petroleum used to dissolve out palmitic acid also contains some of the resino'id substance. I n order therefore to separate palmitic acid the residue after evaporating the petroleum spirit is dissolved in alcoholic potash the palmitic acid precipi-tated by calcium chloride water added and the precipitate washed, dried and extracted with ether On evaporating the ether the resinoid substance is left still mixed with some of the alcohols but free from any fatty acid. The inipure product is dissolved in strong spirit, and left to evaporate slowly. The alcohols separate as indistinctly crystalline opaque matter while the resin separates on the bottom and sides of the vessel as a translucent gummy deposit still contain-ing spirit ; the resin is then redissolved in spirit and the solution left t'o evaporate for two hours.On repeating these operations several times it is obtained in a condition in which it has no longer any tendency to deposit crystalline matter. Separation and Pura3cation of the Fatty Acids.-By far the greater part of the fatty salts remain dissolved when the saponified bird-lime solution is poured into dilute spirit. The filtrate and washings from the gelatinous precipitate of alcohols are diluted with water mixed with hydrochloric acid and warmed in order to separate the fatty acids. By similar and well-known methods the portions of these acids thrown down along with the bird-lime alcohols can be recovered after separating them as calcium salts from the alcohols and resinoid substance and added to the main quantity.The crude fatty acids which when cold form a soft brown solid mass are dis-solved in alcoholic potash and precipitated again with calcium chlo-ride ; the calcium precipitate is washed with spirit which removes chlorides and some colouring matter as well as some of the calcium salt of the soft fatty acid ; the precipitate is then washed with ether, as this dissolves out most of the remaining colouring matter and calcium salt of the soft fatt'y acid more easily than spirit does ; lastly, it is heated with hydrochloric acid and water in order to get the crude palmitic acid. On repeating these operations once or twice and finally crystallising the product from spirit the palmitic acid is obtained in a pure state. By appropriate treatment the spirit and ether washing 274 DIVERS AND KAWAKITA OX THE of the calcium precipitate yield the semi-liquid acid although in an impure condition.Palmitic acid can also be prepared from bird-lime by destructive distillation. Its purification from hydrocarbons by means of saponifi-cation presents no great difficulty and need not be described. The Alcohols of Bird-lime. To one of the two alcohols of bird-lime we give the name mochylic cclcohol formed from the Japanese word nzochi for (bird-)lime or glutinous matter ; and to the other we attach the name i l k ~ l i c alcohol, essentially the same as ilicic alcohol given by Personne to the single alcohol described by him but framed more in accordance with the accepted nomenclature for alcohols. Our ilicylic alcohol differs but little from Personne's ilicic alcohol.Both the alcohols of bird-lime are obtained in tufts of small slender lustrous prisms and are dis-tinguishable from each other only iu solubility in melting point and in composition. -Wochylic alcohol occurs much more abuudan tly than ilicylic alcohol. It dissolves well in 95-98 per cent. spirit but is almost insoluble in 80 per cent. spirit. It is very little soluble in light petroleum i n the cold is readily soluble in ether and dissolves also in con-centratted sulphuric acid to which like bird-lime itself it imparts a red colour. It melts a t 234" and under atmospheric pressure decomposes a t a little below the melting pdint of zinc the principal product being a viscid matter apparently t(he hydrocarbon to be described among the products of the destructive distillation of bird-lime.In a vacuum it sublimes slightly at a little above 160" and freely and entirely near and above its melting point without decom-posing or changing in melting point. Heated with palmitic acid in a sealed tube a t 150-160" it yields a substance indistinguishable from bird-lime in essential properties a sticky transparent matter readily soluble in ether but nearly insoluble in the strongest spirit. Our attempts to obtain mochyl acetate by the action of acetic oxide or chloride have been unsuccessful. Ilicylic alcohol differs from mochylic alcohol in melting a t 172" and in being moderately soluble in 85-90 per cent. although almost in-soluble in 80 per cent. spirit. It begins to volatilise in a vacuum below 150" and sublimes freely near its melting point in beautiful t u f t s of needles still melting a t 172'.Heated with palmitic acid it also forms a substance like bird-lime. It fails apparently to yield an acetate even after long heating at 150-170" with acetic oxide in which when hot it as also mochylic alcohol readily dissolves partly crystallising out again unchanged on cooling and partly becoming COMPOSITION OF JAPANESE BIRD-LINE. 2 i 5 dark viscid matter not the acetate. Personne found that his ilicic alcohol when treated with acetic oxide yielded a crystalline acetate melting at 204-206". The melting point of Personne's ilicic alcohol was 175" and its boiling point above 350° but under a reduced pressure of 100 mm. it began to sublime a t 115".I n appearance and in behaviour to spirit of different strengths it was like our ilicylic alcohol. Both mochylic and ilicylic alcohols dissolve in a mixture of sulphnric and nitric acids and from the solution water separates a gelatinous matter readily soluble in spirit and deflagrating only slightly when dried and heated. C7aeinical Comnpositdon. of the Two AZco7ioZs.-Combustion of the two alcohols has given us the following results :-Mochylic Alcohol m. p. 234". Carbon 83.37 83.39 83.28 83.42 Hydrogen . 12.29 12-16 12.38 12.30 - 4.28 100-00 I. 11. 111. C26Ir4 6 0 -Oxygen. - - Ilicylic AZcoh01 m. p. 1.72". Carbon 83.09 82.98 83.02 Hydrogen . . . . . . . 11-93 11.92 11.95 Oxygen - 5-03 100*00 I. 11. C,,R,,O. --Ilicic Alcohol m.p. 175" (Personne's Analyses). Carbon . . 83.25 83.64 83.48 83.07 83.40 83.36 83.33 Hydrogen 12.18 12.44 12.17 12.24 11.98 12.20 12.22 - 4.45 I. 11. 111. IT. V. Mean. C2,H,,0. Oxygen - - - - -100*00 It will be seen that Personne's numbers vary rather widely but fall for the most part between those obtained by us for our two alcohols. It mill alsobe seen that the formula he has proposed as agreeing best with the mean of his analysis is thak of a homologue of our alcoho!s, the general expression being C,H,,-,O. As he worked on bird-lime from a species of Ilex different from that which yields Japanese bird-lime it cannot for the present be decided whether ilicic alcohol is distinct from the alcohols here described 276 DIVERS AND KAWAKITA ON THE The Resinoid Component of Bird-lime.The resinoild substance is obtained in pale-yellow fragments which are brittle and not sticky like bird-lime. It melts a t 110" and does not volatilise when heated to 220" in a vacuum. Above 360" it darkens boils and distils without much apparent change. It is very soluble in spirit even of 80 per cent. strength also in ether When its alcoholic solution is sufficiently evaporated by heat it separates from its solvent as a viscid liquid still containing spirit but this evaporates on further heating below 100". I t s solubility in spirit is not in-creased by the presence of potassium hydroxide. Heated with the solid hydroxide barely to the melting point it slowly combines with it probably a t the same time absorbing oxygen.The cooled mass wholly dissolves in water from which hydrochloric acid precipitates a gelatinous substance very brittle when dried. We have not further examined it for want of material. When bird-lime is kept for a long time a thin brittle skin forms on its surface which is readily soluble in spirit. This skin consists probably of the resino'id substance. If it does not then me have no evidence as to whether the resino'id substance is produced during the saponification of the bird-lime or exists in it ready formed as the result of slow atmospheric oxidation. In composition the resinoi'd substance differs from mochylic alcohol only in having two atoms less of hydrogen as the following analyses and calculation show :-I. 11. C26H440. Carbon 83.79 83.66 83.87 Hydrogen.. 11.80 11.92 11.83 Oxygen. . - 4.30 -100*00 The Fatty Acids of Bird-lime. The fatty acids of bird-lime are two as already stated palmitic acid and in small quantity only a semi-liquid acid the calcium salt of which is soluble in spirit and in ether. This acid haa not been further examined. The other shows all the characters of pnlmitic acid. Analysis of (I) acid prepared by saponi-fication and (11) acid obtained by destructive distillation of purified bird-lime :-Melting point 61.5" COMPOSlTION OF JAPANESE BIRD-LIME. 277 I. 11. Pslmitic acid. Carbon 74.98 74-86 75.00 Hydrogen . 12.67 12.55 12.50 - 12.50 Oxygen. . -100~00 The potassium salt yielded 13.3 per cent. of potassium. Products of Destructive Distillution. These have been already enumerated so far as their nature is known to us and the result of analysis of the palmitic acid has just been tabulated.The principal hydrocarbon distilling next after t'he palmitic acid was prepared from the middle portion of the distillate by treating it with hot spirit so as to leave about half of it undis-solved. This was then washed with cold spirit. The h-j-drocarbon thus left was a thick oil slightly yellow but not fluorescent. On analysis it gave numbers agreeing with the formula C26H44 :-Found. Calculated. Carbon 87.59 87.64 Hydrogen . 12-49 12.36 --100.08 100~00 Apparently the same compound is obtained by distilling mochylic alcohol under the ordinary atmospheric pressure. The decomposition of the main constituent of bird-lime by heat may therefore be thus represented :-Mochyl palmitate C,,H7,O = c2,& + C16H320~, and the decomposition of mochxlic alcohol by-C2J€46O = CJ344 + H20. The last fractions of the distillate consisted of hydrocarbons yielding No attempt was made to isolate the nearly 91 per cent. of carbon. caoutchouc-hydrocarbons no doubt present in the mixture. Comtitution of Bird-lime. Bird-lime is closely allied to the waxes and consists principally of mochyl and ilicyl palmitates C42H,60z and C&&&,. VOL. LIII.

ISSN:0368-1645    

DOI:10.1039/CT8885300268

出版商:RSC    

年代:1888

数据来源: RSC

摘要:

278 XXV.-Chenzical Inves figation of Wackenroder’s Solution and Explanation of the Formation of its Constituents. By Professor H. DEBUS Ph.D. F.R.S. C 0 “YEN T S . PAGE Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278 A. Preparation of Wackenroder’s Solution . . . . . . . . . . . . . . . . . . . . . . . . . 281 Composition of . . ,. 282 A New Allotropic Modification of Sulphur . . . . . . . . . . . . . . . . . . . . . 282-286 Potassic Pentathionate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291 7 . . . . . 299 Zinc Cupric 300 Potassic Hexathionate . . . . . . . . . . . . . . . . I. . . . . . . . . . . . . . . . . . . . . . 302 (a) Potassic Pentathionate .. . . . . . . . . . . . . . . . . . . . . . . . 311 (6.) Tetrathionate 311 (c.) Trithionate . 313 Action of Acids . . . . . . . . . . ,. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316 Spontaneous Decomposition of Wackenroder’s Solution . . . . . . . . . . . . . . 317 Discussion of the Changes of Polythionates in Aqueous Sohitions . . . . . . 319 Explanation of two Properties of Ozone . . . . . . . . . . . . . . . . . . . . . . . . . . 324 , of the Spontaneous Decomposition of Peroxide of Hydrogen 326 Action of Sulphuretted Hydrogen on Polythionates. . . . . . . . . . . . . . . . . 328 Action of Sulphurous Acid on Polytliioriates . . . . . . . . . . . . . . . . . . . 331 Influence of Time on the Formation of Yentathionic Acid .. . . . . . 336 Sulphurous Acid and Potassic Thioeulphate . . . . . . . . . . . . . . . . . . . . . . . . 343 Sulphurous Acid and Chloride of Sulphur . . . . . . . . . . . . . . . . . . . . . 345 Sulphurous Acid and Sulphur . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347 Explanation of the Formation of the Polythionates . . . . . . . . . . . . 348 C. The Formulae of the Polythionates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351 7 7 7 9 . . . . . . . . B. Decomposition of an Aqueous Solution of-,, ,, Introduction. THE milky liquid produced by the action of sulphuretted hydrogen on an aqueous solut’ion of sulphurous acid contains according to Wackenroder and other chemists besides free sulphur a peculiar acid called pentathionic acid.This acid cannot be separated from its solution by distillation or crystallisation and consequently has not yet been prepared in a pure state. Ludwig could not produce pentathio-nates but in place of these he obtained bodies having the composition of double salts of tetra- and penta-thionic acids. Wackenroder Kessler, and Spring failed like Ludwig in their endeavours t o produce penta-thinnates from Wackenroder’s solution. These unsuccessful experiments together with some positive indi CHEMICAL INVESTIGATION OF WACKENRODER’S SOLUTION. 2 7 9 cations which need not be considered in this place caused Spring to come to the following conclusions :-1. The so-called pentathionic acid is identical with tetrathionic acid.2. The reactions which are described as characteristic of penta-thionic acid are also produced by ammonic tetrathionate. 3. Pentathionic acid is a solution of sulphur in tetrathionic acid, not in atomic proportions but of the same description as the solution of sulphur in carbon disulphide. A salt prepared by Lenoir before the publication of Spring’s researches by adding baric carbonate to a Wackenroder solution has very nearly the composition of baric pentathionate. This salt is, according to Spring a mixture of sulphur and baric tetrathionate I do not think that Lenoir who is known to me as a careful worker, would ana#lyse such a mixture and describe it as a pure compound. But if the substance is not a mixture of baric tetrathionate and snl-phur then it must be baric pentathionate or a mixture of various polythionates of the average composition of a pentathionate.In order to test the correctness of Spring’s views I suggested to Mr. Lewes Assistant in the Laboratory of the Royal Naval College, some experiments on the preparation of salts of pentathionic acid. He carried out these experimentas with much perseverance and skill, and succeeded in preparing nearly pure potassic and baric penta-thionates. Shaw has repeated some of the experiments of Lewes and con-firmed his results. Lewes however could not recrystallise his penta-thionates they decomposed into sulphur and tetrathionates. This decomposition is regarded by Spring as a posit’ive proof that the salts obtained by Lewes are mixtures of tetrathionates and sulphur.Although I did not doubt the interpretation of Lewes a thorough investigation of the subject appeared to me to be desirable from more than one point of view. It was desirable to prepare pure penta-thionates a,nd t o examine some reactions of the polythionates of more than ordinary interest. The compounds usually called acids like sulphuric acid H2S04 are regarded in this papel. as hydrogen salts and the name of acid is reserved for the so-called anhydrides. Therefore the dioxide of sulphur SOo is called sulphurous acid and the compound with water, H2S03 is called hydric sulphite. Hydrogen plays in such compounds the part of a metal. Polythionates are bodies represented by the formulae MoS306 MoSd06 ;?iT2S506. arid M2S606 in which “ M ” stands for hydrogen or a monovalent metal.Wackenroder’s solution is the liquid obtained by the passage of Correct expression also promotes correct thinking. u 280 ISEBUS CHEXICAL INVESTIGATIOS OF sulphuretted hydrogen through an aqueous solution of sulphurous a,cid until the latter is completely decomposed. 1 will before describing my own experiments give a list of the papers which have hitherto been published on pentathionic acid and pentathionates. 1. PIessy “ On some New Acids of Sulpliur produced by the Action of Sulphur Chloride on Sulphurous Acid ” (Compt. rend. 21, 473 ; Ann. Chim. Phys. 20 162 ; Berzelius Jahresbericht 26, 72; 28 24). 2. Th. Thomson “ A New Acid obtained by the Action of Sul-phuretted Hydrogen on Sulphurous Acid ” (Ann. Phil. 12, 4.41).3. Wackenroder “ On Pentathionic Acid ” (Archiv der Pharmacie, 48 272 140 ; Berzslius Jahresbericht 27 36). 4. Lenoir “ On Baric Pentathionate ” (Annalen der Chernie und Pharmacie 62 253 ; Berzelius Jahresbericht 28 21). 5. Ludwig “ On Potassic and Baric Tetrapentathionate ” (A?-chiu der Pharmacie 51 259 ; Berzelius Jahresbeyicht 28 108). 6. Fordos and GAlis “ Action of Sulphur Chlorides on Sulphurous Acid ” (Ann. Chim. Phys. 22 66 ; 28 451 ; Berzelius Jahres-bericht 29 13). 7. Kessler “ On Polythionates ’’ (Poggendorf Ann. 74 249 ; Ber-zelius Jahresbericht 29 15). 8. Sobrero and Selmi ‘i On the Action of Sulphuretted Hydrogen on Sulphurous Acid ” (Ann. Chim. Phys. 28 210 ; Liebig’s Jahresbericht 3 264). 9. Risler-Bennet “ Formation of Pentathionic Acid by the Action of Zinc on Sulphurous Acid ” (Poggendorf Ann.116 470). 10. Chancel et Diacon “ Conversion of Penta- into Tetra-thionic Acid” (Compt. rend. 56 710). 11. Rammelsberg “ Potassic Pentathionate ” (Liebig’s Juliresbericht, 12. W. Spring “Contributions to our Knowledge of the Poly-thionic Acids ” (Berichte der deutschen chemischen Gesellschatit, 6 1108). “ On the Non-existence of Pentathionic Acid ” Liebig’s Annalen 199 97 ; 213 329). 10 136). 13. Sting1 and Morawski (Liebig’s Jahresbericht (1879) 11 10). 14. Takamatsu and Smith “ On Pentathionic Acid ” (Journal of the Chemical Society 37 552 ; 41 162). 15. Lewes V. “ On Pentathionic Acid ” (Journal of the Chemical Society 39 68 ; 41 300). 16. Curtius ‘‘ Experiments with the so-called Pentathionic Acid ” (Jour.prukt. Cheinie [2] 24 225) WACKENRODER'S SOLUTION. 281 17. Shaw " On the Preparation of Pentathionates" (Journal of the Chemical Society 43 351). 18. Smith " Note on Pentathionic Acid " (Journal of the Chemical Society 43 355). 19. Snlzer " On a New Mode of Formation of the so-called Penta-t'hionic Acid (Rerichte der deutschen cheinischen Gesellscltait (1886) 1696). A. COMPOSITION OF WACKENRODER'S SOLUTION. I. Preparation. A slow current of sulphuretted hydrogen is passed for two hours through 480 C.C. of a nearly saturated solution of sulphurous acid a t a few degrees above 0" C. The liquid which must still contain a large excess of sulphurous acid is now kept for 48 hours in a closed bottle a t common temperatures. The operation is then repeated a current of hydric sulphide is again passed for two hours and the liquid allowed to remain a t rest for two days.The treatment in this manner is continued till all the sulphurous acid is decomposed ; about two weeks are necessary for the accom-plishment of this purpose. Certain precautions have to be observed if the end of the operation is to be recognised by the disappearance of the odour of the sulphurous acid. If the current of hydric sul-phide is discontinued as soon as the liquid ceases to smell of sulphu-rous acid and the bott'le is then taken out of the cold water by which it is surrounded and is allowed to stand for a few hours at common temperatures the liquid will again assume an intense odour like sul-phurous acid. The treatment with sixlphuretted hydrogen must then be repeated and is only regarded as complete when after standing for several holm at common temperatures the solution no longer smells like sulphurous acid.The liquid so prepared is of milky appearance and contains a large precipitate of sulphur which is separated by filtration. The filtrate is however not clear and cannot be obtained clear by filtration because it contains in suspension a con-sidcrable quantity of sulphur in very small particles which will pass .through the best Swedish filtering-paper. In a bottle of about an inch in diameter i t appears semi-transparent i n transmitted light of a reddish-brown colour becoming more transparent on warming and more opaque on cooling. Our problem now will be t o determine the composition of this liquid.We shall have to separate the substances contained in the soli-rtion and ascertain their nature and after completing thia t,ask we shall have to explain their formation from the original material N-ater, sulphurous acid and sulphuretted hydrogen 282 DEBUS CHEMICAL INVESTIGATION OF The experiments described in this paper prove that Wackenroder’s solution contains the following substances :-a. Small drops of sulphur in suspension. b. Sulphur in sohition in the colloidal condition similar to silica dissolved in diluted hydric chloride. Sulphur in this condition forms a new hitherto unrecognised allotropic modification. c. Hydric sulphate. d. Traces of hydric trithionate. e. Hydric tetrathionate. f. Hydric pentathionate.g. A polythionate with more sulphur than a pentathionate probably hydric hexathionate. 11. Examination of the Sulphur which separates as a Precipitate during the Passage of Sulphuretted Eydrogen through the Solution oj. Xu lphurous Acid. The greater mass of this sulphur is of a soft gummy nature and forms with water an emulsion in which drops of sulphur can be seen under the microscope. A portion of it is however present in the ordinary modifications in hard brittle particles and mixed with these are observed elastic membranes. The latter were probably formed by adhesion of liquid sulphur to the sides of the vessel and gradual hardening of the layer into a mass like caoutchouc. The emulsion formed by the soft plastic portion with water cannot be rendered clear by filtration.If it is diluted with much water a brown-yellow semi-transparent liqnid is obtained from which a solution of saltpetre throws down a copious precipitate of sulphur. 111. Examiitation of the Jiltered Wackenroder Solution. The milky fluid does not become clear even after standing two or three weeks in a quiet place. A drop observed under the microscope appears homogeneous but after about five minutes a riiig of yellow particles appears round the edge of the drop and grows by degrees towards the centre. This deposit is seen to be composed of minute dyops of sulphur. The quantity so separating is evidently much larger than the amount in suspension consequently a precipitation of dissolved sulphur has taken place. The addition of a little water causes this precipitated sulphur to dissolve.The filtered Wacken-roder solution contains rather large quantities of sulphur in simple .solution as colloidal sulphur in a new allotropic modification which I will distinguish as “ 6 ” sulphur. The solution of &-sulphur resembles the solution of silica in dilute hydric chloride. A drop o WACKENRODER’S SOLUTION. 283 the Wackenroder solution left on a piece of glass evaporates and dissolved sulphur corresponding to the amount of evaporation, separates in the liquid state. A larger portion of the Wackenroder solution was now evaporated under the receiver of an air-pump over pieces of potassic hydroxide. Considerable quantities of sulphur in a viscous semi-fluid condition, separated as the solution became more concentrated.The surface of the evaporating liquid looked as if a layer of oil was floating on it, and at the sides of the basin a yellow shining coating like varnish was observed. The liquid beca,me clear and transparent in layers of 2+ inches in thickness after about 8 of it had evaporated and appeared slightly opalescent like a solution of a,lbumin. In this condition, however it still contains much 8-sulphur in solution because further evaporation addition of hydric chloride sodic chloride baric chloride, saltpetre cupric sulphate and other salts respectively cause the pre-cipitation of considerable quantities of sulphur. The same effect but in less degree is likewise observed when the concentrated solution is kept in a closed bottle in a dark place. The second port’ion was mixed with twice its volume of water and the third with twice its volume of an aqueous solution of sulphurous acid.After standing 21 days a deposit of sulphur in each of the three portions had taken place. The smallest deposit was in the second and the largest in the third. Water retards sulphurous acid accelerates the precipitation of 6-sulphur. A Wackenroder solution was saturated with sulphurous acid and allowed to remain in a closed bottle for a few days. It became perfectly clear both the suspended and the dissolved &,sulphur falling down as a precipitate. Experiments were now made to separate from Wackenroder’s solution which had been so far concentrated as to appear clear and transparent in layers of 2 inches in thickness the dissolved 8-sulphur by means of diffusion and thus to obtain a pure aqueous solution of sulphur.A porous cell like those used in galvanic batteries was immersed for a few days in dilute hydric chloride in order to remove alkalis and other soluble substances and then well washed with water. Wackenroder’s solution was placed in this cell and the latter in a large vessel containing water. The acid of the solution rapidly diffused through the porous clay but the coagulation of the sulphur began and was completed before all the acid had diffused. A second ex-periment made in the same manner as well as a third made with parchment paper failed in the same way. The sulphur which had separated during the evaporation of the About 100 C.C. were divided into three equal portions 284 DEBUS CHEMICAL INVESTIGATION OF filtered Wackenroder solution was collected on a 6lter.The particles united in the course of the night into one semi-transparent lump of the appearance of wax and of a gummy sticky nature. I n another experiment the sulphur separated in a more fluid condition. The filter on which it had been collected was placed upon blotting-paper. Some of the sulphur like oil was absorbed by the paper after the evaporation of the water. A little of this sulphur was mixed with some clear Wackenroder solution and a drop of the mixture placed under the microscope. The sulphur was partly seen in minute trans-parent drops and partly in irregularly formed masses rounded off a t the edges. The remaining sulphur on the filter could not be purified by washing with water.Much of it passed with the water through the filter and farmed an emulsion resembling the original Wacken-roder solution ; only drops of sulphur could be seen in this emulsion under the microscope and after a few hours a sediment of drops separated. A portion of the emulsion was allowed to remain in a bottle a t rest from June to December It was still of the nature of an emulsion a precipitate could be observed but the liquid above this precipitate was not clear. Carbon disulphide benzene ether olive oil chloroform or tannin did not clear the liquid but powder of charcoal baric carbonate alkalis a concentrated solution of hydric chloride hydric nitrate and potassic nitrate caused complete precipitation of the sulphur in sus-pension and solution.Addition of much water caused the emulsion to become almost clear ; at least in layers of an inch in thickness it appeared perfectly clear transparent and slightly yellow. Solution of saltpetre produced in this diluted clear liquid a copious precipitate of sulphur. The drops of sulphur i n suspension in the emulsion appear therefore to be soluble in much water. Another portion of the said emulsion was allowed to evaporate under the exhausted receiver of an air-pump over hydric sulphate. The sulphur remained as a thin elastic membrane resembling caoutchouc. This membrane did not again form an emulsion with water neither did alcohol appear to produce any effect on it but carbon disulphide dissolved a portion and took away its elasticicy.Some suiphur which had separated during the evaporation of Wackenroder’s solution over potassic hydroxide in the exhausted receiver of an air pump and which mas of the same plastic gummy nature as the sulphur described above was placed in some water, in which it dissolved forming a turbid solution. The dissolved portion was reprecipitated by addition of sodic chloride then filtered, and the filtering-paper with the precipitate placed on blotting-paper ; the adherent aqueous solution passed into the paper and the remain-ing sulphur was then mixed with water with which it formed a WACKENRODER’S SOLUTION. 285 emulsion and from this was again precipitated by a solution of common salt. The sediment was again collected on and pressed between layers of bibulous paper and after these operations put in water in which a portion of it dissolved.After two or three filtrations an almost clear opalescent liquid similar to a solution of albumin was obtained. The filtrate became quite clear on warming and more turbid on cooling. Red and blue litmus-papers were not affected by it. A piece of bright silver foil immersed in it turned black by degrees. Sodic chloride hgdric chloride alkalis saltpetre and baric carbonate res-pectively caused the formation of a precipitate of sulphur. The same effect was produced by recently precipitated baric sulphate. Ammonia produced no change. Some of the filtrate evaporated on a watch-glass left a viscous transparent residue. I conclude from these experiments that a great part of the sulphur which separates during the evspora-tion of a Wackenroder solution is soluble in much water or more correctly in water which conhains a little acid or a very little common salt.We are now able to explain why a Wackenrader solution which contains sulphur in minute drops in Suspension and possesses the character of an emulsion will not become clear even if it is allowed t o stand for months in a closed bottle in a quiet place. We prepare emulsions by mixing intimately oil with gum albumin or other colloids and water. The minute drops of oil are prevented by the colloi’d from uniting and separating as a layer on the surface of the water. A colloyd cannot diffuse through a membrane formed of another colloid perhaps because the molecules are too large and sluggish in their motions.In the case of an ordinary emulsion the large sluggish molecules of the collojid place themselves between the drops of oil impede their motion and thus prevent their union. Now the sulphur which is in solution in the Wackenroder liquid acts like a colloid as gum or albnmin in an ordinary emulsion and prevents the union of the minute drops of sulphur which are in suspension in the liquid. The Wackenroder solutiofi loses the character of an emulsion as soon as the dissolved sulphur is removed. Sulphur separates as a precipitate if Wackenroder’s solution is kept for some time or if it is evaporated. But however the separa-tion is effected the precipitated sulphur is far less soluble than it mas before its coagulation. In the beginning of the evaporation when the liquid is less acid the sulphur fieparates in a more liquid and soluble condition whereas later on when the Wackenroder solution becomes more concentrated the precipitated sulphur is harder and more brittJe in fact is made up in a great measure of the ordinwy modifications.Also the temperature of evaporation has an influenc 286 DEBITS CHEMICAL INVESTIGATION OF on the condition of the sulphur. At lower temperatures a larger proportion of liquid soluble sulphur is separated than at higher temperatures. It will be understood from these remarks that the sulphur which separates during evaporation from a Wackenroder solution is a mixture of different modifications. Besides 8-sulphur7 which forms an emulsion and dissolves in much wgter it contains ordinary sulphur, for if it is treated with alcohol &sulphur is dissolved and the remain-ing portion contains small rhombic octahedra.On the other hand, bisulphide of carbon will extract octahedral sulphur and leave the amorphous behind. It appears according to my observations that 8-sulphur if kept very long becomes gradually converted into hard brittle sulphur. However? I have made no special experiments on this point. The properties of soluble collo’idal sulphur suggest the following method for its preparation. A current of sulphuretted hydrogen is passed through not more than 120 C.C. of an aqueous solution of sulphurous acid a t a few degrees above 0” C. until all the sulphurous acid is decomposed. The liquid is then filtered and concentrated over pieces of potassic hydroxide in the exhausted receiver of an sir-pump.The evaporation is stopped as soon as the liquid commences to become clear and the precipitated sulphur is collected on a filt,er. If we take a retrospective view of the properties of the sulphur as it is contained in solution in Wackenroder’s liquid and can be ob-tained from it by partial evaporation we find that it possesses all the properties which Graham* describes as characteristic of the collo’ids. The sulphur dissolved in Wnckenroder’s solution does not diffuse through porous clay or parchment. It is held in solution by very feeble force. Slow and gradual separation takes place when its solutions are kept for some time or complete precipitation if appa-rently inert substances such as sodic chloride charcoal powder or baric sulphate are added.The unstable condition of its molecules, their slow change into other modifications and finally its gummy, sticky condition remind one of the colloids. Sulphur can com-bine with hydric tetrathionate and form hydric pentathionate and although large quantities of both sulphur and hydric tetrathionate are in Wackenroder’s solution they do not combine but seem to be inert towards each other. All this points to the coiiclusion that we have to deal with a new allotropic modification of sulphur. The chemical powers are likewise very feeble. * Chemical and Physical aesearches. Collected by James Young pp. 593-596 WACKENRODER’S SOLUTION 287 Wnckenroder’s solution can be concentrated on a water-bath with-out decomposition until it reaches the sp.gr. 1.32. The &sulphur is all coagulated before it reaches this point of concentration. Further evaporation on the water-bath causes evolution of sulphurous acid and precipitation of sulphur. In a partial vacuum over pieces of potassic hydroxide at common temperatures I have concentrated i t to the sp. gr. 1.46 without decomposition. In this concentrated con-dition it is usually described in the text-books as pentathionic acid, H2S506. A small quantity which had been left for some time under a bell-jar over pieces of potassic hydroxide had evaporated to dryness. The dry residue was amorphous and intermixed with crystals. A few drops of water dissolved the amorphous portion and left beautiful small octahedral crystals of sulphur.The aqueous solution showed the reactions of a pentathionate. From this observation it seems to follow that hydric pentathionate can exist in the solid form. Wackenroder’s solution of the sp. gr. 1.46 is a colourless transparent oily liquid of great refractive power and intensely acid. It destroys the coherence of the fibres of filtering-paper and cau only be filtered when of lower sp. gr. than 1.4. A sample of 1.3 sp. gr. I have kept in a closed bottle in a dark place for three months without apparent change then a slow decom-position set in with evolution of sulphurous acid aiid precipitation of sulphur a decomposition which was not completed in two years. Wackenroder’s solution is apparently for two reasons described in the text-books as hydric pentathionate :-1.Kessler described three rea’ctions of this liquid which hydric tri-and tetra-thionate do not give; and-2. He found that the acid of the solution contained sulphur and oxygen in the ratio of 5 5. Before I repeated the analysis of Wackenroder’s solution I first investigated Kessler’s analytical method. This chemist found that pot’assic tctrathionate and mercuric cyanide decompose at loo” as represented by the following equations :-(See Potassic Pentathionate.) HgCy2 + K2s406 = 2KCy + HgS406 and HgS,O + 2HzO + 2KCy = HgS + S + 2KHSOa + 2HCy. If instead of potassic tetrathionate a Wackenroder solution is taken, the same products of decomposition are obtained only with this difference that in place of potassic hydric sulphate we have hydric sulphate and in the precipitate instead of 1 atom of mercury and 2 of sulphur 1 atom of the metal and 3 of sulphur.From these results the conclusion has been drawn that Wacken-roder’s solution contains an acid similar to tetrathionic acid with 5 atoms of sulphur in 1 molecule 288 DEBUS CHENICAL INVESTIGATION OF Takamatsu and Smith and also Lewes have confirmed the above results of Kessler. It is however desirable to test Kessler's method with a pure pentathionate which hitherto has not been done. Pot'assic pentathionate should be decomposed according to the fol-lowing equation :-I f therefore the amount of sulphate in solution and the quantity of mercury and sulphur in the precipitate be determined from the numbers so obtained the composition of the pentathionate can be cnl culat ed .The preparation of potassic pentathionate will be described in another part of this paper. A sample of very pure salt was employed in the experiments. The mercuric cyanide was bought as pure in the market. Afterwards whilst using it I discovered the presence of mercuric chloride in it. The error caused by this impurity was duly corrected. 0.703 gram crystallised potassic pentathionate was boiled with a solution of mercuric cyanide. 0.773 gram of a black precipitate was produced. 0.677 gram of the latter yielded on treatment with bromine-water 0.118 gram of pure sulphur and on addition of baric chloride to the filtrate from the sulphur 0.311 gram of bnric sulphate. The filtrate from the baric sulphate gave with hydric sulphide 0.547 gram of mercuric sulpliide.The filtrate from tlie precipitate produced with mercuric cyanide at loo" gave with baric chloride 0.917 gram of baric sulphate. According to these numbers we obtain for the composition of the black precipitate caused by mercuric cyanide-Sulphur 0.183 Mercury. 0.538 Chlorine 0.052 0.773 -The difference obtained by the subtraction of the weights of the sulphur and mercury from the weight of the precipitate represents the weight of the chlorine which was present in combination with mercury and sulphur as mercuric sulphochloride. Mercury 0.392 Sulphur. . 0.183 Mercuric chloride 0.198 G.773 -The amount of sulphuric acid corresponding to 0.917 gram of baric sulphate contains the rest of the sulphur and all the oxygen o WBCRENRODER’S SOLUTION.289 the potassic pentathionate. Adding this amount 0.315 gram to the above mercury and sulphur we obtain the weight of the mercuyic pentathionate corresponding to the weight of potassic pentathionate taken = 0.890 gmm. Replacing the mercury 0.592 gram by its equivalent of potassium 0.152 gram we obtain 0.650 gram of potassic pentathionate which would combine with 0.0525 gram of water forming 0.7025 gram of the crystallised salt instead of 0.703 gram the amount actually taken. In 100 parts we have-Calcnlated according to Found. zK2S506 + 3H20. Sulphur. . 44.01 44-32 Potassium 21.65 81.60 Water . 7.48 Oxygen 26.92 26-59 99-99 The calculated composition of the potassic pentathionate has been proved to be correct by other methods which will be described in another part of this paper ; Kessler’s method therefore yields accu-rate results.A sample of Wackenroder’s solution of the sp. gr. 1.46 was diluted with four times its volume of water and the clear slightly yellow liquid used in the following experiments :-I. Determination of Dissolved Xulyhur. 10 C.C. mixed with solution of saltpetre gave 0.005 gram of sul-phur. 11. Determination of Hydric Xdpha fe. 10 C.C. gave with baric chloride 0.243 gram of baric sulphate. 111. DetermiRation of the Xulphur and Oxygen of the Polythionates. 10 C.C. boiled with mercuric cyanide which contained also a little chloride gave 2.875 grams of mercuric sulphochloride and sulphur. The filtrate gave with baric chloride 3.882 grams of baric sulphate.Subtracting the baric sulphate found previously (11) we have f o r the remaining weight 3.639 grams corresponding to 0.499 gram of sulphur and 0.750 gram of oxygen as derived from the polythionates of the Wackenroder solution. 0.868 gram of the mercuric sulpho-chloride and sulphur precipitate treated with bromine-water gave 0.024 gram of sulphur and the Gltrateon addition of baric chloride gave 1.430 gram of bai-ic sulphate. The filtrate from the bnric sulphat 290 DEBUS CHENICAL INVESTIGATION OF yielded with hydric sulpbide 0.694 gram of mercuric sulphicle. 0.997 gram of the mercuric sulphochloride and sulphur precipitate burnt with plumbic chromate and metallic copper iii the front part of the tube gave 0.683 gram mercury but no water or carbonic acid, According to these data 2.875 grams of precipitate composed of mercuric sulphochloride and sulphur contain after the subtraction of the mercuric chloride and the sulphur which existed in Wackenroder’s solution free and was precipitated by saltpetre (I) 0.724 gram o€ sulphur and 1.494 gram of mercury.If the sulphur of this precipi-tate 0.724 gram is added to the sulpliur of the sulphuric acid pro-duced by boiling with mercuric cyanide 0-499 gram we obtain the sulphur of the polythionates = 1.223 gram and if we add to this sulphur the oxygen of the polythionates 0.750 gram present in the sulphate obtained by boiling with mercuric cyanide and the hydrogen equivalent to 1.494 gram of mercury me obtain the composition of the polythionates of Wackenroder’s solution-Sulphur 1.223 Oxygen 0.750 Hydrogen 0.015 -1.988 Or in 100 parts-Sulphur .Oxygen . Hydrogen . And the atomic mtio-H From these experiments, Calculated. Found. H,S,O,. . 61.52 62.01 . 37.72 37-21 . 0.75 0.77 99.99 99-99 s = 2 5-12 it seeins to follow that Wackenroder’s liquid is really a solution of pentathionic acid and aa Kessier Taka-matsu and Smith and Lewes obtained nearly the same numbers, the probability of this conclusion is thereby increased. I f a substance is obtained under different conditions and a t different times of the Same quantitative composition it is probably a pure compound. Nevertheless another interpretation may be given to the analytical results. Wackenroder’s solution may be a mixture of an equal num-ber of molecules of tetrathionic acid and the unknown hexathionic and if it has this composition it would if analysed by Kessler‘ WACKENRODER’S SOLUTION.291 method yield numbers agreeing with the composition of pentathionic acid. In order to ascertain which of these two interpretations is correct I prepared and examined some of the salts which can be formed by the acid or acids of Wackenroder’s solution with metals, Potassic Pentathionate. Kessler attempted the preparation of this salt but obtained only a mixture of tetrathionate and sulphur. Ludwig divided a Wacken-roder solution into two equal parts neutralised one part with potassic carbonate and added the other part. The solution gave on evapora-tion crystals of the composition K4S9012,H20 which Ludwig regarded as a compound of potassic tetrathionate and pentathionate.Rammels-berg measured the crystals of a salt which he called potassic penta-thionnte but as the mode of preparation the properties and the analysis are not described it remains doubtful whether the salt was a penta- or tetra-thionate. The first chemist who prepared nearly pure potassic pentathionate was Lewes. He added by degrees to a portion of Wackenroder’s solution about half the quantity of potassic hydroxide which would be required for its complete neutralisation. Sulphur was precipitated during this operation and the filtrate from the precipitate gave, by spontaneous evaporation crystals of hydrated potassic penta-thionate. The following experiments were made with a Wackenroder liquid of 1.19 sp.gr. of which 5 C.C. required for neutralisation 8.2 C.C. of a solution containing 13.8 per cent. of potassic hydroxide. The solu-tion of potassic hydroxide was added drop by drop with constant stirring to 25 C.C. of Wackenroder’s liquid until the acid was nearly neu tralised. Much sulphur was precipitated and some sulphurous acid produced. The liquid which was still acid was filtered and allowed to evaporate spontaneously. Sulphur separated again whilst the exaporation proceeded and had to be removed two or three times. At last crystals not of potassic pentathionate but of potassic tri-thionate were formed. This negative result seeins to show that the pentathionic acid of the Wackenroder solution has been decomposed during the neutralisation or subsequent evaporation.One drop of a solution of potassic hydroxide causes imwLediateZy 8 precipitate of sulphur in a solution of potassic peritathionate. This salt cannot exist in alkaline solutions. The addition of potassic hydroxide to an acid solution in the ordinary way even by constant stirring will cause for moments in certain parts of the mixing liquids an alkaline reaction and consequent decomposition in case of penta-thionic acid. As the addition of the base proceeds and the amoun 292 DEBUS CIIEMICAL INVESTIGATION OF of free acid becomes smaller transient alkalinity will be more frequent and of longer duration and consequently the more consider-able hhe decomposition. From these considerations it seems to follow that in order to prevent as much as possible the decomposition of the pentathionate the Wackenroder liquid ought to be concentrated the potassic hydroxide very dilute the mixing of the two as rapid as possible and finally not more of the base ought to be added than is required for tho neutralisation of about.half of the acid present. The experiincnts confirm this conclusion. No pentathionate could be obtained by Ludwig’s method a method which was also adopted by Spring. These chemists divided Wackenroder’s solution into two equal parts and neutralised one part completely. This cannot be done without producing transient alkalinity in parts of the mixing liquids and decomposition of the pentathionate. If the other part of Wackenroder’s solution is added and the united liquids Concentrated no crystals of pentathionate are obtained.Lewes could prepare the potassic pentathionate because he added to a given quantity of Wackenroder’s solution only half the amount of potassic hydroxide required for its neutralisation so that the base nearly always met a n excess of acid. Kessler has by means of his analytical method determined the quantity of polythionic acids in Wackenroder’s solution of given sp. gr. The following are his results :-Specific gravity. Percentage of S505. 1.233 32.1 1.32 41.7 1-47 56.0 1.506 59-7 By means of these numbers the quantity of potassic hydroxide to be added to Wackenroder’s solution of given strength can approxi-mately be calculated. 100 C.C. of a liquid of 1.883 sp. gr. would contain according to my estimate 48.6 grams of acid (S,O,) and would require 22.5 grams of potassic hydroxide for neutralisation.A solution of 6 grams of potassic hydroxide in 1OOc.c. of water was sucked into a pipett,e with a very narrow aperture at its lower end and using the pipette as a stirring rod were allowed to run into 50 C.C. of Wackenroder’s solution of 1.283 sp. gr. As the cnd of the stem of the pipette moved through the acid the weak solution of potassic hydroxide ran slowly out and always met a large excess of acid. In this manner very little sulphur was precipitated indicating that very little if any potassic pentathionate had been decomposed. The mixture was now filtered and allowed to concentrate in a partia WAGKENRODER'S SOLUTION. 293 vacuum over pieces of potassic hydroxide.After two days' evapora-tion a crust of prismatic crystals had formed. This crust weighing 4.6 grams was removed and the mother-liquor put back into the vacuum. Two more crops of crystals were obtained the first weighing 6.2 and the second 1.5 grams. As the crystals of these three separations appeayed to be of the same shape they were united and recrystallised. Lewes could not at first recrystallise potassic pentathionate the salt decomposed with separation of sulphur. Fordos and Gklis observed, long ago that the polythionic acids are more stable in presence of other acids. This observation as well as the conditions under which crystals of potassic pentat,hionate are obtained from Wackenroder's solution suggested to Mi-. Lewes a method of recrystallisation which proved very successful.He dissolved the potassic pentathionate in water which was acidulated with a little sulphuric acid and observed that the crystals could be reproduced from this solution. I took 50 grams of water acidulated with 0.66 gram of hydric sulptiate and introduced into this liquid a t 50" the 12.3 grams of crystals obtained as before described. All dissolved except a few milligrams of sulphur which mere separated by filtration. The filtrate was run into a glass dish with a flat bottom and allowed to concentrate by spontaneous evaporation. As the solution became stronger two descriptions of well-developed crystals some of them Q of an inch in diameter separated from the liquid. Six-sided prisms with pyramids only on one end and with the side on which they were resting much developed could easily be distinguished from four-sided rhombic or six-sided star-like plates.The first were found to be potassic tetrathionate and the second pot'assic pentathionate. The latter is also sometimes obtained in short thick prisms with more or less developed pyramids. It is the eiilargementJ of two sides of these prisms parallel to the chief axis and opposite to each other which causes them to appear sometimes like six-sided plates. Both descrip-tions of crystals were placed on blotting-paper and after they were dry the potassic pentathionate could easily be picked out from the mixture ; its weight was 4.2 grams. Both the potassic penta- and tetra- thionate were recrystallised a second time from water acidulated with hydric sulphat'e.50 C.C. of Wackenroder's solution of 1.283 sp. gr. yielded in this way 12.3 grams of a mixture of potassic tetra- and penta-tbionate and this mixture was resolved by two cry stallisations into 2.25 grams of very pure potassic pentathionate and 4.0 grams of potassic tetrakhionate. The yield by this methodof preparation isnot good as a t least half of the pentathionic acid of Wackenroder's solution remains in the original mother-liquor. I was fortunate enough to find a method VOL. LIIL. 294 DEBUS CHEMICAL INVESTIGATION OF generally applicable by means of which every pentathionate which will crystallise can be prepared without loss of pentathionic acid. The principle of the method will be understood from the following descrip-tion.The acids of Wackenroder's solution are strong and not volatile. If mixed with an acetate the hydrogen of the polythionates, H28506,H2Sa& is exchanged for metal producing metallic poly-thionates and hydric acetate. The latter evaporates if the mixture is exposed t o the atmosphere. These operations can be performed without decomposition of the pentathionates. 43 C.C. of Wackenroder's solution of 1.343 sp. gr. contain according to my calculation (see page 292) 24 grams of pentathionic acid (S60,) and would according to the following equation-H,S506 + 2KCaH,0z = R,S506 + 2C2H4O2, require 19% grams of potassic acetate for the forniation of potassic pentathionate and hydric acetate. I took a little less only 16.66 grams of previously fused potassic acetate dissolved it in the smallest quantity of water and acidulated with a few drops of hydric acetate.This solution was now mixed with 43 C.C. of Wackenroder's liquid of sp. gr. 1.343. The mixture measured 85 c.c. and was put on a large plate so as to present a great surface to the atmosphere and then placed in the window of a small draught closet in order to cause a constant current of air to pass over the surface of the mixture. The acetic acid and water evaporated in 24 hours and left a white crystal-line residue which was repeatedly pressed between layers of Swedish filtering-paper. This residue (26 grams) dissolved in 50 C.C. of water acidulated with 1 C.C. of hydric sulphate a t 40" C. leaving only about 0.005 gram of sulphur behind.The sulphur was separated by means of a filter and the filtrate which did not smell of acetic acid left to spontaneous evaporation in a vessel with a flat bottom. The crystal-lisation commenced on the following day and yielded 18.75 grams of very fine crystals of a mixture of potassic tetra- and penta-thionate, instead of only 12 grams as in the previous experiment. Some of the crystals were & of an inch in diameter. 5.75 grams of potassic pentathionate could be picked out of the mixture. The remaining 13 grams as well as the 5.75 grams of pentathionate were each by itself twice recrystallised from water acidulated with a little hydric sulphate. For 1 gram of salt 2.25 grams of water and 0.02 gram of the acid were taken. The crystals obtained were large and well developed so that the peritathionate could easily be separated from the potassic tetra-thionate.In this manner 5 grams of very pure potassic pentathionat \VBCEENRODER’S SOLUTION. 295 and 6.35 grams of pure pottassic tetrathionate mere obtained. The yield is more than twice as great as in the previous experiment. The use of potassic acetate i n place of potassic hydroxide is there-fore highly advantageous because all the acid of Wackenroder’s solution can be converted into the potassium salt and the hydric acetate which is set free tends to prevent the decomposition of the potassic pentathionate. The pentathionates of the heavy metals can only be produced by the addition of the acetates of the metals to Wackenroder’s solution. The mother-liquors of the crystals mentioned above still contained much potassic pentathionate and tetrathionate ; they can easily be recovered by adding for every molecule of sulphuric acid used 2 mols.of potassic acetate and evaporating to dryness at common tempera-tures. The residue of polythionates and sulphate is then treated in the same way as the original crystals. Potassic pentathionate is obtained quite pure by crystallisation from water acidulated with hydric sulphate. But i t is also possible t o crystallise the salt from pure water. 40 grams of water were heated to 50° and then potassic pentathionate in powder was introduced by degrees until the liquid mas nearly saturated. The solution was now passed through a filter into a beaker. The crystallisation commenced almost immediately and proceeded so rapidly that one could see the lighter mother-liquor rise from the newly-formed crystals towards the surface of the solution.About one or two hours after the latter had assumed the temperature of the room the mother-liquor was poured off a crop of very fine prisms, some 5 of an inch in length. The salt remaining in the mother-liquor can be recovered by precipitation with alcohol but not by evapora-tion because it decomposes in to tetrathionate and sulphur. This decomposition occurs even if a concentrated solution is left standing for several hours. The crystals of potassic pentathionate cannot be kept long. In the course of a month or two yellow points are observed in them these points grow and increase in number, until the whole crystal is turned into a yellow pulpy mass consisting chiefly of water potassic tetrathionate and sulphur.The cause of this spontaneous decomposition is the presence of water contained in cracks and fissures of the crystals. In order tlo preserve the salt the crystals must be rubbed to a fine powder and the latter washed with dilute alcohol. In this state I have kept the salt over hydric salphate in an exsiccator for two or three years without the slightest change. Analysis of Potassic Pedathionate. 0.662 gram were oxidised with hydric nitrate and the excess of the latter I-emoTed by evaporatioii A. Crystallised from pure water. x 296 DEBUS CHEMICAL INVESTIGATION OF with hydric chloride. On addition of baric chloride 2.084 grams of baric sulphate were precipitated.0,972 gram of the same salt gave 0.471 gram potassic sulphate. 11. 0.518 gram were treated with bromine-water and the excess of bromine evaporated on the water-bath. 0945 gram of sulphur remained undissolved ; the filtrate from this sulphur gave with bark chloride 1.3565 gram of baric sulphate. The bromine used in this experiment was proved to be purc. 0.931 gram of the substance was evaporated with pure hydric sulphate and heated to redness. The weight of the residue was 0.448 gram. B. Potassic pentathionate prepared by the addition of potassic hydroxide to Wackenroder’s solution and crystallisation from water containing hydric sulphate. 111. 0.701 gram was oxidised with bromine-water and the un-dissolved sulphur washed with dilute ammonia.0.114 gram of sulphur was obtained and 1.405 gram of bark sulphate by pre-cipitation with baric chloride. 1.598 gram of the substance heated to redness left 0.770 gram of potassic sulphate. 2 931 grams burnt with plumbic chromate in a combustion-tube gave 0.2265 gram of water. IV. Potassic pentathionate prepared by Mr. Lewes a<nd analysed by Mr. Cowper. 0.4895 gram gave 0.235 gram of potassic sulphate. 0.5045 gram gave 1.6175 gram of baric sulphate. 0.7205 gram gave 0.057 gram of water. C. Potassic pentathionate obtained by the addition of potassic acetate to Wackenroder’s solution and crystallisation from water con-taining hydric sulphate. V. 0.541 gram oxidised with bromine-water and the solution precipitated with baric chloride gave 1.741 gram of baric sulphate.0.453 gram heated to redness left 0.221 gram of potassic sulphate. Percentage Conyosition. Theory. I. 11. 1x1. IT. V. 2K,S5O,+3H,O. Potassium 2!.70 21.57 21.58 21.54 21.80 21.60 Sulphur . . 43.23 44.61 43.76 44.03 44.20 44.32 - 26.59 Oxygen. . . . 7.72 1-91 - 7.48 Water . . - -59.99 - - - --The atomic ratios are-I. K S = 2 4.85 II. K S = 2 5-04 111. K S = 2 4.94 IV. K S = 2 4.9 WACKENRUDEB'S SOLUTlON. 297 Potassic pentathionate dried over hydric sulphate has consequently, the formula 2K,S506,:3Hz0. Lewes mentions three salts K2S50G KC2S50G,H20 and K2S50s,2H,0. Shaw calculated from his numbers the formula K,S,O,*H,O. The salts prepared by Lewes and Shaw were not recrystallisod but were analysed in the same state in which they separated from the original solution.I believe they were not quite pure. If we consider the hydrogen of the water of crystallisation replaced by potassium in tlie formula 2K,S506,3H,0 we have the composition of 5 mols. of po tassic thiosul p hate. The crystalline forms of potassic pentathionate have been described on p. 293. The salt dissolves in about 2 parts of water with reduction of temperature forming a perfectly clear transparent and neutral solution. The aqueous solution cannot be kept long without change ; after a few days sulphur separates and potassic tetrathionate remains in solution. The presence of a little hydric sulphate prevents this decomposi-tion. The crystals which are obtained by evaporation from an acidu-lated solution are frequently crossed by fissures.The aqueous ~ o l u -tion can be boiled for a short time without apparent change; if, however the boiling is continued for 15 or 20 minutes then the odour of hydric sulphide becomes perceptible. A piece of sheet copper or silver will turn black in the course of a few days in the aqueous solu-tion in consequence of the formation of metallic sulphides. The brown colour of a solution of iodine in potassic iodide is in the course of a day or two decolorised by potassic pentathionate. Potassic per-manganate produces a brown precipitate and hydric sulphate is formed which remains in solution. Platinum black placed in a perfectly neutral solution of potassic pentathionate causes the latter t o become intensely acid and to comport itself with bark chloride like a sul-phate.Sulphur is not precipitated in this reaction. Potassic penta-thionate decomposes at high temperatures as represented by the equation-It is not soluble in alcohol. 2KzS506,3HzO = 2KzS04 f 2SOz + S + 3HZO. The reactions of Wackenroder's solution have hitherto been described as the reactions of pentathionates. But Wackenroder'e solution is a mixture of at least three polythionates. Being in pos-session of some very pure pentathionate I therefore took the oppor-tunity to study its reactions somewhat minutely. Reactions characteristic of Penta t hionat es. I. An ammoniacal solution of silver nitrate causes in a solution of potassic ammonic or baric pentathionates a brown coloration whic 295 DEBUS CHEMICAL ISVESTIGATION OF rapidly becomes darker and by degrees a black precipitate is thrown down from the mixture.This reaction is not produced in a solution of tri- or tetra- thionat'es pot'assic thiosulphate or ammonic sulphite. An ammoniacal solution of silver nitrate also seems to have no effect on them. Consequently a pentathionate even if present in very small quantity can be detected by means of this reaction in a mix-ture containing potassic tri- and tetra-thionates and sodic potassic or ammonic thiosulphates. The solution of zinc in sulphurous acid produces with an ammo-niacal solution of silver nitrate an immediate grey precipitate and the supernatant liquid appears clear and colourless. 11. Potassic hydroxide in solutions of pentathionates immediately produces a separation of sulphur.As tri- and tetra-thionates and thio-sulphates are not changed by this reagent a proportionally small quantity of a pentathionate can be detected in a mixture of the four salts by addition of potassic hydroxide. The latter however is not so sensitive a reagent as the ammoniacal silver solution. 111. Ammonia added to a solution of potassic pentathionate causes, after about one or two minutes a precipitation of sulphur. IV. Sulphuretted hydrogen produces in an ammoniacal solution of a pentathionate an immediate precipitate of sulphur. V. An ammoniacal solution of mercuric cyanide produces with pc tassic pentathionate a black precipitate by degrees at ordinary temperatures at once at 100" C. VI. Ferric chloride plumbic nitrate cupric chloride cupric acetate, cobaltic nitrate zinc sulphate cupric sulphate plumbic acetate hydric chloride and bark chloride cause no change in solutions of potassic pentatbionate.Qeneral Reactions of Polythiovtates and Thiosulphates. I. Mercurous nitrate produces with penta- and tetra-thionates a fine yellow and with trithionates and thiosulphates a black precipitate. 11. Cupric sulphate mixed with solutions of potassic tri- tetra- 01-penta-thionates or an aqueous aolution of sulphurous acid or the solu-tion of zinc in sulphurous acid causes no apparent change at common temperatures. The same reagent does not affect tetra- and penta-thionates at loo", but produces at this higher temperature with trithionates or thio-sulphates a black and with the solution of zinc in sulphurons acid a red precipitate.Cupric snlphate added to a solution of ammonic sulphite produces a yellow precipitate at common temperatures. 111. Hydric chloride does not change solutions of tetra- and penta WACKENRODER'S SOLUTION. 299 thionates but in about ten minutes in such as contain trithionates and in about one minute in those of thiosulphatee it causes a separation of sulphur and sulphurous acid. A mixture of the four salts became turbid in two minutes. IV. Ferric chloride causes transient coloration in the following solutions :-a. Thiosulphates violet changing to yellow. 71. Sulphurous acid in water brown changing to yellow. c. Zinc in aqueous sulphurous acid brown changing to colonrless. The reagent causes a permanent brown colour in aqueous solution of amm onic sul phi t e.V. Baric chloride produces in solutions of sodic or potassic thio-sulphate a white crystalline precipitate which even in boiling water, is only sparingly soluble but it does not change solutions of the poly-thionates at common temperatures or those of tetra- and penta-thio-nates at 100". Thiosulphates and trithionates can be detected in a mixture of the two in the following manner :-Chloride of barium is added to the neutral mixture as long as a precipitate is formed ; the latter is baric thiosulphate and can be proved to be so by means of ferric chloride and hydric chloride respectively. The filtrate from the baric thiosulphate is boiled for about five minutes when if barium trithionate is present the smell of sulphurous acid will appear and a white precipitate will be thrown down insoluble in hydric chloride, and not volatile at a red heat on a piece of platinum-foil.These reactions are not observed with baric dithionate. If free acid should happen to be present in the original mixture it must be neutralised wihh baric carbonate. Zinc Pentat hionat e could not be obta.ined in a pure state. 45 C.C. of Wackenroder's solution of the sp. gr. 1.325 mere mixed with a concentrated solution of 22 grams of zinc acetate Zn(C2H302)2,3H20 and the mixture allowed to evaporate at common temperatures. A crystalline mass and a very little mother-liquor remained after two days' exposure to a current of air in a draught closet. The residue (46 grams) was pressed between layers of blotting-paper and then dissolved in 30 C.C.of water which were acidulated with a little hydric sulphate. No insoluble matter remained behind. The solution left to spont'aneous evaporation deposited nothing but crystals of zinc sulphate. T'he mother-liquor remained liquid in common air but in dry air under a bell-jar over pieces of potassic hydroxide solidified to a white amorphous mass like porcelain which dissolved again in yery little water. The solution gave the reactions of a pentathionate 300 DEBUS CREJIICAL INVESTIGATION OF The solid residue decomposed completely in the course of two months sulphur zinc sulphate and probably sulphurous acid being the products found. C u p ic Pent a thiona t e was obtained in small fine blue crystals by the following method :-20 grams of cupric acetate were dissolved in 250 C.C.of water and the solution mixed with 45 C.C. of Wackenroder’s solution of sp. gr. 1.325 and the mixture left to evaporate on two large plates in a draught closet a t ordinary temperatures. After two days a blue crystalline mass was formed on each plate the residue of one plate was pressed between blotting-paper and then dissolved in water acidulated with hydric sulphate. A few brown flakes remained undissolved. The blue filtrate from these during spontaneous evaporation yielded long fine needles in such abundance that the whole appeayed like jelly, and this when placed on bibulous paper left a blue solid mass which could not be dried over hydric sulphate without decomposition. It turned brown and was after this change of colour only partially soluble in water.The residue on the second plate also changed its colour in the course of two days from blue to brown because a portion of it had undergone a similar decomposition to the needle-shaped crystals mentioned above. The brown mass was pressed between layers of filtering-paper and then extracted with water. A portion dissolved forming a blue solution and a brown solid in appear-ance like cuprous oxide was left. The blue solution which was a1 lowed to evaporate at common temperatures yielded crystals without decomposition. Three crops of crystals were obtained ; the first and second consisted of cupric sulphate the third of fine prismatic crystals cf cupric pentathionate ; 0.460 gram of the latter dried over hydric sulphate and dissolved in bromine-water gave by the usual methods 0.095 gram of cupric oxide 1.350 gram of bslric sulphate and 0.002 gram of sulphur ; 100 parts contain-Theory.Found. CUS,O + 4Hz0. Copper . . . . 16.49 16-11 Sulphur . . 40.74 40.92 Cupric pentathionate is easily soluble in water. Mercurous nitrate produces in the solution a yellow and ammonia a blue precipitate ; the latter is soluble in an excess of the reagent. The blue ammoniacal solution thus obtained reacts with ammonia-silver nitrate like potnssic pentathionate. Potassic hydroxide causes in solution of cupric penta-thionate a blue precipitate which is only partially soluble in hydric chloride Ieaving a residue of sulphur. Similar experiments with WACKENRODER’S SOLUTION. 301 mixture of potassic tetrathionate and cupric sulphate in place of cupric pentathionate gave no brown colouring with the silver solution and no precipitate of sulphur with potassic hydroxide.A brown solid a product of decomposition of one of the salts con-tained in the original mixture of Wackenroder’s solution and cupric acetate has been mentioned on p. 300 ; the mode of forniation and the composition of this substance I have not accurately ascertained. Wackenroder’s solution contains an acid with more sulphur than the pentathionic acid probably hexathionic acid. The atomic ratio of copper to sulphur in the brown product was found t o be = 1 4. From this it would appear probable that it is formed from cupric hcxathionate according t o the equation-CUS,O + 2H2O = 2H2SO4 + CUS,.A more detailed and accurate examination was not carried out because the substance absorbed oxygen from the air. A tube con-taining a portiou which had been dried over hydric sulphate for the purposes of analysis increased 0.035 gram in weight in two weeks. The brown product of decomposition resembled in colour and other properties the precipitate which forms on the addition of the higher sulphides of potassium to a solution of cupric snlphate. The colour is at first a bright red or reddish-brown but during washing on the filter acquires a darker colour no doubt in consequence of oxidation. Examination of the Nother-liquor of Potassic Pmtathionate. According to the experiments described so far Wackeiirod er’s solution-the pent athionic acid of the text-books-is a mixture of at least two acids tetra- and penta-thionic acids.The tetrathionic acid is not a product of decomposition of pentathionic acid because a Wackenroder solution can be evaporated with potassic acetate with precipitation of very little sulphur. We have now to examine the mother-liquors (pp. 293 294) from which pot’assic tetra- and penta-thionate had separated by crystallisation. For this purpose, the filtering-paper which had been used to free the crystals from adhering mother-liquor (p. 294) was extracted with water and the extract mixed with the mother-liquors which had been poured off the crystals (p. 295). The united liquids contained hydric sulphate according to my calculation a quantity capable of decomposing 8 grams of potassic acetate.A concentrated solution of a little less than this quantity of potassic acetate was now added and the entire mixture left to evaporate on plates in a draught closet. Nearly all the water had disappeared in two days and a solid residue with very little mother 302 DEBUS CHEMICAL INVESTIGATION OF liquor was left. This was pressed between layers of blotting-paper, and then dissolved in 30 C.C. of water acidulated with 1 C.C. of hydric sulphate. Only a little sulphur according to my estimate not more than 0.01 gram remained undissolved. The weight of the dissolved portion was 18 grams. The filtrate from the small quantity of sulphur was clear and slightly yellow. In the course of a day however it turned turbid and a few milligrams of sulphur separated.After a second filtration it remained clear. With reagents it acted like a pentathionate with this difference, that ammonia caused a n immediate copious precipitate of sulphur, and a similar precipitate was obtained a t 100" with cupric sul-phate. The solution was put into a glass vessel with a flat bottom, and allowed to concentrate a t ordinary temperatures. During the evaporation solid matter separated and was collected in six portions. The 1st portion consisted of potassic tetra- and penta-thionate crystals. The 2nd appeared as a crust of warty formation in which no crystalline structure could be discovered by means of a lens. The 3rd formed small six-sided plates the 4th was like the 2nd and the 5th and 6th resembled the 3rd portion. The mother-liquor which remained a t last was so small in volume that no further experiments could be made with it.The 2nd and the 4th portions appeared t o be formed of the samo substance and were homogeneous throughout. They were therefore united washed with dilute alcohol and dried over hydric sulphate. This substance appeared to be potassic hexathionate mixed with some potassic hydric sulphate and free sulphur. I could not remove these impurities. If the substance is dissolved in water with a little hydric sulphate and left to evaporate it will although sulphuric acid is present partially decompose with separation of sulphur and pro-duction of pentathionate. I attempted therefore to determine the impurities and calculate the composition of the remainder. The sub-stance is well characterised by its physical and chemical properties.I will on the basis of the following determinations call it potassic hexathionate. I. 0.240 gram was d-issolved in water slightly acidulated with hydric chloride and precipitated with baric chloride. The precipitate contained besides baric sulphate also the free sulphur which was mechanically mixed with the potassic hexathionate. The precipitate was collected on a weighed filter and dried over hydric sulphate. Its weight was Pound to be 0.033 gram. At a red heat the weight diminished t o 0.024 gram. The difference of the two weights 0.009 gram represents the weight of the free sulphur. 11. 0.288 gram oxidised with bromine-water and the products precipitated with baric chloride gave 1.046 gram of baric sulphate WACKENRODER’S SOLUTION.303 and 0.3124 gram gave after heating to redness 0.1385 gram potassic sulphate. 0.330 gram of the substance burnt with potassic chromate gave 0.021 gram water. According to the dat,a given under 11 100 parts of the substance contain-Potassium 19.92 Sulphur 49.89 Oxygen 23.83 Water 6.36 100.00 According to the determinations of I 3.75 per cent. of sulphur are present in the free state and 1.37 per cent. in the form of potassic hydric sulphate. 5.12 per cent. of sulphur have conse-quently to be deducted from 49.89 per cent. as found under 11. If likewise the potassium oxygen and hydrogen of the potassic hydric sulphate are subtracted the following quantities are left :-Potassium 18.25 Sulphur 44.77 Oxygen 21.09 Water 5.98 90.09 Theory.And in 100 parts :-Found. R2S,06 + 1*5H,O. Potassium 20.25 19.84 Sulphur 49.69 48.85 Oxygen 23.40 24.42 Water 6-63 6.87 99-97 99.98 The atomic proportions are-KzS5.,,05.aa + 1.41 HzO. Sulphur and potassium have been found too high and accordingly oxygen somewhat too low. Potassic hexathionate separates from its solution in crusts of warty masses without crystalline structure. More pure than the sample analysed I found some amongst the 5th crop of crystals (p. 302). As this did not contain free sulphur it dissolved in water to a clear solution. The aqueous solutions of this salt decompose with separation of sulphur even when free hydric sulphate is present and are thu 304 DEBUS CHEMICAL INVESTIGATION O F distinguished from those of the pentathionate.Potassic nitrate, which completely precipitates 2-sulphur (sulphur in the collo'idal con-dition in solution) does not change the solution of the hexathionate. Ammonia produces a precipitate of sulphur immediately (difference from pentathionate) and ammonincnl solution of silver nitrate, potassic hydroxide and mercurous nitrate react with hexathionate as with pentathionate. The crystals obtained from the mother-liquors of potassic hexa-thionate (p. 302) were potassic pentathionate rendered impure by potassic sulphate. 0.369 gram gave after ignition 0.183 gram of potassic sulphate. I n 100 parts :-Found. Theory. Potassium 22.23 21.60 The impure substance which has been described as potassic hexa-thionate decomposes so rery easily that I could not hope to prepare it in a perfectly pure state.I have therefore by the following experi-ments attempted to prove the existence of polythionates containing more sulphur than pentathionates and thus increase the probability of the existence of hexnthionates. The Wackenroder's solution used in these experiments was not pre-pared exactly as described on p. 281. Sulphuretted hydrogen was passed into smaller quantities of sulphurous acid than in former preparations. Not more than 120 C.C. were taken for each experi-ment with the result that the decomposition of the sulphurous acid required less time than before. Hydric sulphide was passed for one hour through the sulphurous acid solution and again on the next day for two hours.The reactions were then completed and no more free sulphurous acid could be observed. The resulting solution was now concentrated on the water-bath until i t showed the sp. gr. 1.257 and then filtered from the precipitated sulphur. Reactions of the Concentrated Solution. It produced with potassic hydroxide ammoniacal silver nitrate, rnercuroiis nitrate and cupric sulphate respectively the reactions of potassic pentathionate. Ammonia gave a copious precipitate of sul-phur. No difference in this respect could be observed when the reagent was added in large excess. Samples of Wackenroder's solu-tion prepared as described on p. 281 did not show this behaviour. Analysis of the Concentrated Solution. 10 C.C. of the sp. gr. 1,257 were diluted with 15 C.C.of water WACKENRODER’S SOLUTION. 305 I. 5 C.C. of the diluted liquid were precipitated with bark chloride. Weight of precipitate = 0.121 gram. Free sulphur was not present. 11. 5 C.C. of the diluted liquid when boiled with mercuric cyanide, gave 0.969 gram of a black precipitate consisting of mercury and sulphur which was collected on a previously weighed filter. The filtrate from this precipitate gave with baric chloride 1.692 gram of baric sulphate. 0.907 gram of the mercuric cyanide precipitate dis-solved in bromine-water gave 0.136 gram of sulphur and 1.052 gram of baric sulphate from which data we calculate for the entire precipi-tate of 0.969 gram 0.299 gram of sulphur and by difference 0.670 gram of mercury. 111. 5 C.C. of the diluted liquid boiled with mercuric cyanide gave 0.971 gram of a precipitate consisting of mercuric sulphide and sul-phur.The filtrate mixed with baric chloride yielded 1.682 gram of baric sulphate. IV. 5 C.C. of the dilnted liquid oxidised with bromine-water and precipitated with baric chloride gave 3.686 grams of baric sulphate and 0.018 gram of sulphur. According to determinations I 11 and 111, 5 C.C. of the diluted liquid contain 0.5135 gram of sulphur in com-bination in the form of polythionic acids. According to determina-tions I and IV 5 C.C. contain after deduction of the sulphur present in the form of sulphuric acid 0.507 gram of sulphur. The two numbers 0.513 and 0.507 are sufficiently near to allow the conclusion that the liquid under examination contains besides some sulphuric acid only sulphur compounds of the form H2S,06 (poly-thionic acids).The atomic ratio of the sulphuric acid formed by boiling the diluted liquid with mercuric cyanide to the mercury and sulphur of the precipitate formed in the same operation is-[I and 111 SO Hg S = 2 1 2.78 [I and 1111 So3 Hg S = 2 1 2-79 which means that the average composition of the polythionic acids of the solution is nearly expressed by the formula Sa.s05 or H,S4.,06, a formula which would correspond to 4 mols. of hydric pentathionate and 1 mol. of hydric tetrathionate (see p. 287) viz. a Wack-enroder solution containing 4 mols. of pentathionic acid and 1 mol. tetrathionic acid would give the analjt.ica1 results described. From the above determinations me calculate that 1 C.C.of Wacken-roder’s solution of sp. gr. 1.257 contains 0.389 gram of acid of the average composition s4.7505 and 0.0207 gram sulphuric acid (SO,). 0-389 gram of acid S4.7505 can decompose 0.3285 gram of potassic acetate KC2H,0, and produce 0,5463 gram anhydrous polythionate. 95 C.C. of Wackenroder’s solution of the sp. gr. 1.257 were therefore 306 DEBUS CHEMICAL INVESTIGATION O F mixed with a solution of 30 grams of potassic acetate and left to con-centrate at ordinary temperatures. The crystalline residue remaining after 24 hours’ evaporation weighed after pressing between filtering-paper 45 grams. According to theory 30 grams of potassic acetate can produce 49.8 of anhydrous polythionates of the average composi-tion K2Sb.7506. The mother-liquor of the crystalline residue wbich bad been absorbed by the Swedish filtering-paper was extracted with water and the aqueous extract examined separately.The pressed residue 45 grams was dissolved in 80 C.C. of water containing 1 C.C. hydric sulphate a t 50” a few milligrams of sulphur were separated hy filtration and the clear filtrate left to crystallise a t common t,emperatures in a vessel with a flat bottom. A crop of fine crystals, consisting partly of potassic tetrathionate and pertly of potassic penta-thionate formed in the course of a few days. The two descriptions of crystals were easily separated from each other. 24.5 grams of potassic tetrathionate and 10.5 grams of potassic pentathionate were collected. The degree of purity of the crystals can be judged by the following determinations :-u.Potassic pentathionate. 0.407 gram gave 0.200 gram of potassic sulphate therefore 100 b. Pot assic t e trathionate. 0.544 gram gave 0,308 gram of potassic sulphate ; 100 parts contain, therefore 25.3s parts of potassium instead of 25-82 parts as required by theory. The potassic pentathionate contains 0.42 per cent. of potassium more and the potassic tetrathionate 0.44 per cent. potas-sium less than the theoretical quantities which means that the picked out pentathionate contained 10 per cent. of tetrathionate and the selected tetrathionate 10 per cent. of pentathionate. Several of the smaller crystals of both salts frequently grow together. 95 C.C. of Wackenroder’s solution of 1.257 sp. gr. contain according to analysis 36.96 grams of acids of the average composition If the solution contains for every molecule of tetrathionic acid 3 mols.of pentathionic acid then after addition of 30 grams of potassic acetate it should have produced 41.4 grams of hydrated potassic pentathionate and 11.5 grains of potassic tetrathionate. Instead of these quantities only 4 of the theoretical amount of pentathionate and more than double the theoretical quantity of tetrathionate were actually ob t ai n e d. The assumption that Wackenroder’s solution contains only tetra-thionic and pentathionic acids is therefore incorrect ; it must contain besides these another acid with more sulphur than pentathionic acid. 95 C.C. of Wackenroder’s solution of 1.257 sp. gr. contain according parts contain 22.02 parts of potassium.Theory requires 21.6 parts WACKENRODER’S SOLUTION. 307 to analysis 24.27 grams of sulphur and 12.73 grams of oxygen united to polythionic acids. 10.5 grams potassic pentathionate ( 2K2S,06,3H20) collected as described contain 4.66 grams of sulphur and 2.33 grams of oxygen united as S,O,. 24.5 grams of potassic tetrathionate ( K2Sa06) contain 10.38 grams of sulphur and 6.49 grams of oxygen united as Sa05. Now if we subtract the sulphur and oxygen of the tetrathionic (S40,) and the pentathionic acids (S,O,) contained in the potassium salts from the sulphur and oxygen of the polythionic acids contained in the 95 C.C. of Wackenroder’s solution the remainder will be the sulphur and oxygen of the acids contained as potassic polythionates in the united mother-liquors.24-27 grams S - (4.66 + 10.38)S = 9.24 grams S. 12.73 grams 0 - (2.33 + 6.49)O = 3.91 grams 0. Now 9.24 3.91 = 189 80 = S5+ O, for which we may take-S 6 0 5 . That is t o say the average composition of the potassic polythionates contained in the mother-liquors of the above potassic penta- and tetra-thionates is represented by the formula-K2S606, or corresponds to the composition of a hexathionate. The united mother-liquors and aqueous extracts of the Swedish filtering-paper were mixed with 3 grams of potassic acetate in order to convert the greater portion of hydric sulphate present into potassic sulphate and then placed on a plate in the window of a draught closet. The solid residue which was still moist was pressed between layers of filtering-paper, and in khis condition weighed 11.5 grams.It was now put in 10 C.C. of water which contained $ C.C. of hydric sulphate ; it all dissolved except a trace of sulphur which was separated by means of a filter. The filtrate which however did not appear to be quite clear was allowed to concentrate at common temperatures. After a few days, a crust of warty formations appeared without crystalline structure. This was removed and the mother-liquor a second time gave a crust of warty matter which like the first was dried on blotting-paper. The remaining mother-liquor was now practically exhausted. A few days after their preparation the two separations of warty forma-tions began to decompose with development of sulphurous acid.In order to prevent this decomposition they were placed in water. The first dissolved with the exceptlion of some sulphur the second left a propori,ionately small quantity of a sparingly soluble potassium salt. The evaporation was finished in 24 hours 308 DEBUS CHEJIICAL INVESTIGATION OF The molecules of potassic hexathionate are evidently of a most unstable nature and little hope was left of their complete separation from other matter. The two aqueous solutions mentioned just before were united, filtered and the atomic ratio of potassium sulphur and oxygen of the salt or salts in solution determined according to Kessler’s method. I. Determination of sulphates. 5 C.C. were mixed with baric chloride and 0.33 gram of bark sul-phate obtained. IT. Determination of sulphur oxygen and metal in the polythio-nates .5 C.C. of the filtrate were boiled with a solution of mercuric cyanide. The precipitate consisting of sulphur and mercury weighed 0.333 gram and the filtrate from this precipitate gave with baric chloride 0.831 gram of baric sulphate. After deducting the sulphate found under I a residue of 0.501 gram is left which contained 0.0688 gram of sulphur. 111. Determiriation of the mercury and sulphur in the precipitate mentioned under 11. 0.313 gram of the precipitate were digested with bromine-water until all the mercury was dissolved. 0.028 gram of sulphur was left undissolved arid the filtrate from this sulphur gave with baric chloride 0.635 gram of baric sulphate which contains 0.08i2 gram of sulphur.The filtrate from the baric sulphate gave with hydric sulphide 0.228 gram of mercuric sulphide which contains 0.196 gram mercury. If however the mercuryis taken to be equal to the difference between the weight of substance taken and the sulphur found then its quantity would be = 0.1978 gram. The last number I consider to be more correct than the former and therefore I shall adopt it. From these numbers we obtain for the composition of 0.333 gram of precipitate found in 11 0.122 gram of sulphur and 0.211 gram of mercury. The atomic ratio of the sulphur in the sulphuric acid pro-duced by boiling with mercuric cyanide to the mercury and sulphur of the precipitate formed at the same time is therefore-S of SO Hg S = 2.04 1 3-63. If the sulphuric acid of 0.501 gram of baric sulphate found in I1 is added to the mercury and sulphur of the mercuric cyanide precipitate, we obtain the weight of the mercuric polythionate and if we replace in this the mercury by its equivalent of potassium we have the average composition of the potassic poly thionates of the solution, as expressed by the forniula-~ * S 5 .6 1 0 6 1 ~ WACKENRODER’S SOLUTION. 309 Therefore the solution contains a polythionate with more sulphur than the pentathionate. The following experiment shows that besides sulphates and pol$-thionates no other sulphur compounds are present in the solutions. IV. 5 C.C. treated with bromine-water until all the sulphur was oxidised t o sulphnric acid and precipitated with baric chloride gave 1.i28 gram of baric sulphate.Deducting from this weight the amount of sulphate found in I tliere remains a quantity of baric sulphate which contains 0.192 gram of sulphur. According to I 11 and 111 fhe total sulphur present in 5 C.C. of the liquid as polythionates is = 0.191 gram. Hence it follows that the solution contains only sulphates and polythionates. Reactiom of the Solui5on. Although clear immediately after filtration the liquid soon became turbid and deposited a comparatively small precipitate of sulphur. This precipitate did not further increase even in the course of weeks. But as soon as it was separated by filtratlion the clear liquid in the course of an hour again became turbid and soon foimed a quantity of precipitate about equal to the former. Then the pre-cipitation would stop until the liquid was filtered when it would commence again.I have repeated the filtration five or six times always with the same result. These observations I explain as follows:-The liquid contains easily decomposable potassio hexathionate which decomposes with separation of sulphul- but the latter separates i n a condition in which it can recombine with potassic pentattionate and produce a higher polythionate. In every unit of time a certain portion of sulphur is set free and a certain portion redissolved. The precipitation stops when both actions become equal. Hydric chloride ferric chloride cobalt sulphate and cuprie sulphate caused no change in the liquid. Ammonia gave a copious precipitate con-sisting of yellow flakes of sulphur ; and a large excess of ammonia a white crystalline precipitate soluble in an excess of water.Potassic hydroxide srnmmiacal solution of silver nitrate mer-curous nitrate and hydric snlphide respectively gave the same reae tions as with a pentathionate. The experiments described prove that Wackenroder’s solution con-tains in addition to tetra- and penta,-thionic acid one or more acids of similar constitution b u t richer in sulphur than the two acids named. The acid is probably hexathionic acid. I f during the preparation insu#icie?.zt hydric sulphide has been passed through the sulphurous acid trithionic acid also will be present. The small amount of liydric sulphate which I found in VOL. LJU. 310 DEBUS CHEMICAL INVESTIGATION OF Wackenroder’s solution is most probably the resnlt of the oxidising action of the air on sulphurous acid.Lenoir Ludwig Kessler and others ha,ve attempted the preparation of pentathionates by the complete or partial neutralisation of the acids in Wackenroder’s solution and precipitation of the salts formed by means of alcohol. The results were as might be expected very dis-cordant. For it is ciear that the concentration of Wackenroder’s solution as well as the strength and volume of the alcohol used must have according to the experiments described in this paper an influence on the composition of the precipitate. Kessler obtained potassic tetrathionate and sulphur Ludwig R mixture of baric tetra- and penta-thionates and Lenoir a precipitate nearly of the composition of baric pentathionate. Some experiments of my own show the variations in the composi-tion of the precipitates very cIenrly.Wackenroder’s solution of sp. gr. 1-25 was neutralised with baric carbonate filtered and then precipitated with twice its volume of alcohol. The crystalline preci-pitate was redissolved in a small quantity of water the solution separated by filtration from a little sulphur and then reprecipitated by alcohol. The precipitate obtained in this way had nearly the composition of baric pentathionate but might be a mixture of baric tetra- penta- and hexa-thionates. On addition of more alcohol to the first filtrate from this precipitate, it gave another precipitate in which barium and sulphur were con-tained in the atomic proportion Ba S = 1 4.28. The filtrate from the last precipitate gave with more alcohol a third precipitate of the atomic ratio Ba S = 1 3.8, and if the alcohol which was added in three portions had been added at once the ratio of barium to sulphur in the precipitate would pro-bably have been = 1 4%.It is clear that by such methods pure substances cannot be obtained with certainty. The Wackenroder’s solution has been proved in this paper to contain before its evaporation large quantities of sulphur in a new modification 8-sulphur in solution and besides this tetra- penta-, and probably hexa-thionic acids. We have now to explain the formation of these prodncts from the original materials-sulphuretted hydrogen sulphurous acid and water. This problem is one of the most complicated in chemistry WACKENRODER'S SOLUTION.311 B. ON THE FORMATION OF THE CONSTITUENTS OF WACKENRODER'S SOLUTION. Decomposition of an Aqueous Solution of Potassic Pentathionate. A concentrated solution of this salt was allowed to stand for a few months in a beaker covered with a piece of filtering-paper. From time to time some water was added in order to make good the loss caused by evaporation. Very soon in less than 48 hours after the preparation of the solution sulphur began to separate and slowly continued to do so for several weeks but even after three months the decomposition was not quite complete for potassic penta-thionate could still be detected (see p. 298). AS soon as the separa-tion of sulphur appeared to be practically complete the solution was passed through a filter and allowed to evaporate spontaneously.A fine crop of crystals of potassic tetrathionate was obtained. 1.228 gram dried over hydric sulphate gave after ignition 0.7035 gram of potassic sulphate. 1.0695 gram of the same subst.ance oxidised with bromine-water gave 0.090 gram of sulphur and 2.616 grams of baric sulphate from which data we calculate for LOO parts-Found. Potassium . . 25.68 Sulphur . . . . 42.02 Theory. K2S40,. 25.82 42.38 The decomposition can be represented by the equation-K2S,06 = R2Sa06 + S. The mot,her-liquor contained however small quantities of potassic tri- and penta-thionates and seme potassic and hydric sulphates. The sulphur on the filter could not be washed because it passed through the pores of the filter with the water.The crystals of potassic tetrathionate obtained formed with water a neutral solution which was not changed on addition of potassic hydroxide or of an ammo-niacal solution of silver nitrate. Decomposition of an Aqueous Xohtion of Potassic Tetrathionate. Fine large crystals of the salt were carefully examined. 1.14 gram dried over hydric sulphate left after ignition 0.656 gram of potassic sulphate. 0.6945 gram of the same substance osidised with bromine-water and the solution precipitated with baric chloride gave 2.145 grams of baric sulphate. Hence in 100 parts 312 DEBUS CIIEMICBL INVESTIGATION OF Found. K&&. Potassium 25-79 25.82 Sulphur. . . 42.41 42.38 The aqueous solution of this substance was not changed on addition of ammonia-silver nitrate and potassic hydroxide respectively.Also cupric snlphate produced no reaction with it a t 100". The substance, therefore is pure potassic tetrathiona,r;e. The neutral solution was left standing for 12 days at 18". It was now stroiigly acid but still clear and smelt strongly of sulphurous acid. The appearance of sulphurous acid without separation of sulphur indicated the probable formation of a compound richer in sulphur than the t e t rathionat e. I now prepared another solution of 0.5 gram of potassic tetrathionate in 10 C.C. of water and made with this and with the solution 12 days old the following corriparative experiments :-0.5 gram of this pure salt was dissolved in 10 C.C. of water. Reagents . Litmus . BaC1 + HC1+ H,O . NaHO . NH,HO AgNO + NH4HO.cut304 . Pe2C16 Hg?(N03)2 Kew solution of potassic tetrathionate. neutral no change J Y > J no change at 100" no change yellow precipitate no change Twelve-days old solution of potas-sic tetrathionate. Strongly acid. Copious precipitate. Brown colouring &black precipitate. Precipitation of much sulphur. Black precipitate a t 100". Turbid after a few minutes. Grey precipitate. No change. These reactions prove that an aqueous solution of potassic tetra-thionate a t 18" slowly decomposes into potassic pentathionate and potassic trithionate sulphurous acid and potassic sulphate as repre-sented by the following equations :-Further on it will be shown that potassic trithionate decomposes as follows :-3&s306 = BKZSO + 2SOz + KZSjO,, and the spontaneous decomposition of potassic tetrathionate a t 18" is fully explained.The following experiment will furnish an idea of the rate a t which the decomposition proceeds :-The temperature of my laboratory is from October to May nearl WACEENBODER'S SOLUTIOS. 313 constant 18" so that all these experiments have been performed practically at the same temperature. A solution of 1 gram of potassic tetrathionate in 10 C.C. of water was tested at intervals as described in this table. Time in hours after preparation. 22 76 96 16s 288 Litmus. --neutral 7 7 7 7 slightly acid strongly acid Reagents. Ammonia-silver nitrate. ~~ No change. Feeble reaction of pentathionate. Reaction of pentathionate.Strong reaction of pentathionate. Very strong reaction of pentathio-natc. Ammonia-silver nitrate is the most sensitive reagent for penfathio-nates. The formation of pentathionate could only be detected with sodic hydroxide after the solution had been standing more thau 168 hours. The crystals of potassic tetrathionate kept in a closed bottle smelt of sulphurous acid after some time. Water enclosed in cracks and fissures of the crystals is the cause of this decomposition. The perfectly dry salt can be kept without the slightest change. Decomposition of an Aqueous Solution of Potassic Trithionate. The equation on p. 312 representing the decomposition of this salt in aqueous solutions has t o be proved. The salt used in the following experiments had been prepared by the action of sulphurous acid on potassic thiosulphate and two or three times recrystallised from hot water.1.2855 gram dried over hydric sulphate gave after ignition 0,8275 0.643 gram of the same substance oxidised with bromine-water gave Hence in 100 parts-gram potassic sulphate. 1.662 gram of baric sulphate. Found. K2s306-Potassium. . 28.85 28.88 Sulphur . . 35.49 35.55 A clear neutral solution of 1 gram of this salt in 10 C.C. of water, Boon after its preparation gave no reaction with ammonia-silver nitrat 314 DEBUS CHEMICAL INVESTIGATION OF or potassic hydroxide and therefore did not contain any pentathi nate; after standing 24 hours the solution had acquired an ac reaction without separation of sulphur. The decomposition can be represented by the equation-2K2S,0 = Kc,S,O + K2S04 + SO2.Potassic pentathionate was not detected at this stage of the trans-formation. Six days after the preparation of the solution potassic sulphate and sulphurous acid were found in abundance and com-paratively large quantities of potassic penththionate were detected by means of ammonia-silver nitrate and potassic hydroxide respec-ti vel y . I t follows therefore that an aqueous solution of potassic tri-thionate decomposes at 18" slowly into potassic sulphate sulphurous acid and sulphur but the latter is not set free as it enters into com-bination with potassic trithionate forming tetra- and penta-thionate respectively-SKZSaOij = 2Kc,S04 + 2SOe + K2S506. A solution of one of the three salts pot,assic penta- tetra- or tri-thionate will contain if left to itself f o r some time all three salts.An attempt to separate the salts so formed by crystallisation failed, because the quantity of material (6 grams) I used was not large enough f o r the purpose the crystals being too small and interlaced t o allow of their mechanical separation. The question " Can common sulphur combine with potassic tri-or potassic tetra-thionate as sulphur does statu nascendi ?" suggested the following experiment :-0.940 gram of sulphur which had been crystallised from carbonic disulphide was left in contact with a concentrated solution of potassic t'etrathionate for 24 hours. The sulphur was after the lapse of this time collected on a weighed filter and found to have lost only 1 mgrm.in weight and the solution of the potassic tetrathionate appeared to be quite unaltered ; no trace of pentathionate could be detected in it. From this experiment and from a similar one made by Mr. Lewes with sulphur and hydric tetrathionate rhombic sulphur appears to be insoluble in potassic tetrathionate. Spring asserts however that hydric t'etrathionate dissolves flowers of sulphur if digested with it for a month or two (Annalen 213, 339). He analysed the solutions according to Kessler's method, by boiling with mercuric cyanide and found that the ratio of sulphur in the mercuric sulphide to the sulphur precipitated in the free state increased during the digestion of hydric tetrathionate with sulphur WXCKENRODER’S SOLUTION. 315 Hydric tetrathionate gave with mercuric cyanide (p.287)-[HzSOA] EIgS S = 1.98 1 1.04. And after treatment with flowers oE mlphur-HZSO HgS 55 = - 1 1.85. The change of the ratio 1 1.04 into 1 1.85 proves according to Spring solution of sulphur in the acid. Now there is good reason for assuming that hydric tetrathionate comports itself in an aqueous s o h -tion like the potassium salt viz. it will decompose into hydric tri-thionnte and hydric pentathionate and the former changes into hydric sulphate sulphurous acid and sulphur which in statzc nascendi would recombine with undecomposed hydric tetrathionate and pro-duce pentathionate. But if these reactions occur then the above ratio 1 1.04 can change into 1 1.85 without the solution of an atom of sulphur in hydric tetrathionste.Therefore Spring has not proved the solubility of flowers of sulphur in hydric tetrathionate. Potassic tetrathionate does not only combine with sulphur in stntu nascendi set free by its own spontaneous decomposition but generally with sulphur in statu nascendi forming potassic pentathio-nate. Bromine-water decomposes potassic tetrathionate according to the equation-K2Sa06 + 2H,O + Br2 = 2RBr + 2H,S04 + s,. I f the bromine-water is added cautiously and slowly the sulphur, instead of falling down will combine with another portion of PO-tassic tetrathionate and produce potassic pentathionate. Or if a solu-tion of potassic tetrathionate is mixed with hydric sulphate and hydric sulphide passed in excess the followiug decomposition will take place :-Also in this case the sulphur instead of becoming free will com-bine with undecomposed potassic tetrathionate and produce the penta-thionate.This behaviour of sulphur in statu ?lascendi enables us to prepare potassic pentathionate from tetrathionate. Preparation of Potassic Pentathionate from Potassic I’etrathionate. 72 grams of pure potassic tetrathionate were dissolved in 24@ C.C. of water acidulated with 4 grams of hydric sulphate. A sample of this solution gave with ammonia-silver nitrate and potassic hydroxide respectively no reactions of pentathionate. A slow current of hydric sulphide was passed for one hour through the solu 31 6 DEBUS CHEMICAL INVESTlGATION OF tion and the liquid after this treatment allowed to stand for two days in a closed cylinder.The smell of sulphuretted hydrogeu was gone a t the end of this time without separation of much sul-phur. The quantity of sulphur which had precipitated was in fact not more than would have separated if sulphuretted hydrogen water had been left standing in a closed bottle for two days. The solu-tion now comported itself with ammonia-silver nitrate and potassic hydroxide respectively like one of potassic pentathionate. I n order to extract this salt the small precipitate of sulphur was separated by filtration the clear filtrate allowed to evaporate spontaneously a t common temperatures and the crystals which formed were from time to time removed from the liquid. Seven portions of crystals were collected. The first consisted of pure potassic tetrathionate the second contained in addition a little potassic pentathionate the third a little more of this salt and the last four crops of crystals were very rich in pentathionate.These which weighed 24 grams were united and dissolved in 70 grams of water acidulated with 1 C.C. of hydric sulphate. The solu-tion left to spontaneous evaporation gave first only crystals o f potassic tetrathionate and towards the end of the crystallisation only crystals of potassic pentathionate. The crystals were very fine most of them a quarter of an inch in diameter and could easily be picked out from a crystal or two of tetrathionnte. A little more than 3 grams of pure potassic pentathionate was collected. I. 0.354 gram gave after ignition 0.171 gram of potassic sulphate. IT. 0.59 gram gave 0.2855 gram potassic sulphate.0.3845 gram completely oxidised with bromine-water pave on addition of baric chloride 1.241 gram of baric sulphate. 111. 0.19 gram of another preparation gave 0.092 gram of potassic sulphate. In 100 parts-I. 11. 111. 2K2S,0 + 3H,O. Potassium . . . . 21.64 21.69 21.68 21.60 Sulphur . . . . . . - 4,492 - 44.32 Action of some Acids OVL the Solutions of Potassic Polythionates. Two test-tubes one containing 10 C.C. of a pure concentrfited solution of potassia pentathionate and the other 10 c,c. of a similar solution mixed with & C.C. of hydric sulphate were corked and kept for several days near each other. The solution containing potassic pentathionate only was after eleven days quite turbid from fre WACKENRODER’S SOLUTION.317 snlphur and after three weeks contained a comparatively large precipitate of sulphur. The solution which contained besides potassic pentathionate a little hydric sulphate appeared to be quite unchanged after three months. Into four test-tubes 10 C.C. of different solutions were introduced in the 1st was a 10 per cent. solution of pure potassic pentathionate in the 2nd a similar solution with one drop of strong hydric chloride in the 3rd a similar solution with three drops of hydric chloride and in the 4th a similar solution with some acetic acid. The solution of pure potassic pentathionate commenced to deposit sulphur within three d a p after its preparation the one which contained hydric acetate in addition to the potassium salt remained unchanged for a fortnight, and then entered into slow decomposition with precipitation of sulphur.The sulphur precipitate continued to increase for some weeks. After seven months the solutions were filtered and carefully examined. The same substances potassic pentathionate potassic trithionate, and potassic sulphate were found in both. The tubes which con-tained hydric chloride besides potassic pentathionate showed no signs of decomposition after seven months’ keeping. Therefore com-paratively small quantities of hydric chloride or hydric sulphate prevent the decomposition of potassic pentathionate in an aqueous solution whilst hydric acet,ate exerts a retarding influence only. The spontaneous decomposition of potassic tetrathionate is likewise prevented by the presence of about 2 per cent.of hydric sulphate ; a solution of potassic trithionate acidulated with hydric sulphate decomposes apparently quite as easily as a solution of the pure salt . 6.5 grams of potassic trithionate were dissolved in 30 C.C. of water containing 4 C.C. of hydric sulphnt,e. After 24 hours large quantities of sulphurous acid were observed and in the course of two weeks precipitation of sulphur had taken place. Spontaneous Decomposition of WacZcen?roder’s 80 lution. As this solution is a mixture of the hydrogen salts of the pols-thionic acids its spontaneous decomposition might be expected if no hydric sulphate were present. But as my solutions usually contained about 2 per cent. of this substanoe the question arose whether this amount of sulphate exerts a protecting influence over the polythionates of the solution.A sample of concentrated Waokenroder’s sollition oould be kept foF three months in a dark place without the slightest decomposition. But after this time a slow decomposition set in whioh manifeste 318 DEBUS CHEMICAL IYVESTIOATION OF itself by the development of sulphui~ons acid and the precipitation of sulphur. After two years the liquid appeared like a strong solution of sulphurous acid and contained a proportionately large precipitate of nionoclinic sulphur. The liquid aboTe this sulphur was perfectly clear it was separated by filtration from the sediment and then placed over pieces of potassic hydroxide under a bell-jar. After eight days, all the sulphurous acid had left the solution and combined with the potassic hydroxide.The small quantity of sulphur which had sepa-rated during the evaporation of the sulphurous acid was removed from the liquid by filtration. The qualitative examination of the filtrate revealed the presence of R small amount of hydric trithionate some hydric liexathionate (ammonia gave an immediate precipitate even when used in excess), and much hydric pentathionate. The remainder of the filtrate was evaporated nntil its sp. gr. was 1.284. During evaporation some sulphur separated. The filtrate from this sulphur measured 35 c.c. and was a t first clear but soon became turbid. A concentrated solution of 13.5 grams of potassic acetate was added to it and the mixture placed in a draught closet. The crystalline cake le€t after evaporation of the water and hydric acetate was recrystallised from water acidulated with a little hydric snlphate.Four portions of crystals were separated and collected. a. Crystals like potassic pentathionate. 0.510 gram gave after ignition 0-2496 gram of potassic sulphate. I n 100 parts-Found. Theory. Potassium 21.93 21-60 The solution of these crystals comported itself with potassic hydroxide ammonia-silver nitrate and mercurous nitrate respectively, like a pentathionate. b. Crystals like potassic tetrathionate. 0.613 gram gave 0.347 gram of potassic sulphate. I n 100 parts-Pound. Theory. Potassium. . 25.37 25.82 A solution of these crystals behaved with solution of potassic hydroxide ammonia-silver nitrate mercurous nitrate and cupric sulphate like a tetrathionate.c . Crystals of potassic sulphate. d. , 9 , From these experiments it follows that Wackenroder's solutio WACKER’RODER’S SOLUTION. 319 decomposes spontaneously like the potassium salts of the polTthionic acids and that this decomposition is very slow being incomplete even after two years and is probably retarded but not prevented by the presence of about 2 per cent. of hydric sulphate. Such an amount of sulphate would prevent the decomposition of potassic pentathionate and tetrbthionate. Does the Air promote the Xpontaueous Decomposition of Potassic Tetra-t hionate,? Three tubes were about half filled with a solution of 8 parts of water and 1 part of potassic tetrathionate. Two of the tubes were exhausted by means of the air-pump and then sealed in a blowpipe flame.The third tube was closed by a cork and placed by the side of the two others. The liquids in all these tubes had become acid after 12 days but only those in the exhausted tubes had deposited sulphur. Potassic pentathionate could be detected in all three tubes. Therefore the decomposition of potassic tetruthionate solution had been more rapid in the exhausted tubes. Discussion of the behaviour of the Potassic Polythionates i n Aqueous So 1 ut ion. I t has been shown (pp. 311 and 312) that these salts decompose in aqueous solutions according to the equations-(1.) K,SSOS = KzSa06 + S. (2.) 2Ki,S406 = K2S,06 + K2S306. (3.) K(zs30tj = KK,SO~ + so + s. But the sulphur of this last reaction is not set free but combines with undecomposed potassic trithionate forming potassic tetra-thionate-or pentathionate-KzS306 + s = Ki,S406; KzS306 + &= &,Sa06.The last three equations can be united-5Ki,s306 = & s 5 0 6 + KzS406 + 3&so4 + 3soz . . . . . (3.) The reactions are consequently of a reciprocal nature that is to say, they are reversible and can take place in opposite directions appa-rently with equal facility. This interesting behaviour is no doubt, in great measure dependent on the heat of formation of the pols-thionates 320 DEBUS CHEMICAL INVESTIGATION OF Thomsen (Thermochenzische Untersicchungen 2 264 ; 3 236) calcu lates the following values for the heat of formation of the bodies in question -Hydric dithionate . . . . . . , trithionate .. . . . , tetrathionate . . . . . , pentathionate . . . . Potassic di thionate. . . . . . . . , trithionate , tetrathionat'e . . . . , pentathionate . . . . From these numbers it appears that the hydrogen and potassium salts of the polythionic acids develop by their formation from water and the elements less and less heat as they become richer in sulphur. When potassic trithionate unites with 1 atom of sulphur no less than 8640 cal. are rendered latent and the same quantity of energy seems to be stored up when potassic tetrathionate unites with 1 atom of sulphur forming pentathionate. The compounds with regard to these sulphur atoms are endothermic. A sulphur-atom which detaches itself from a molecule of potassic tetrathionate carries away with it an amount of energy corresponding to about 9000 cal.and this amount is sufficient to enable the atom to reunite with amolecule of trithionate to tetrathionate or with the latter to form pentathionate. The near approach to equality of the differences in the last column suggests tliat the differellt sulphur atoms are really of equal thermo-chemical value. The reactions represented by the equations (l) (2) and ( 3 ) 011 p. 319 occur under the same chemical and physical conditions and take place in the same liquid. From this i t follows of necessity that in it solution containing potassic tri- tetra- and penta-thionate decomposi-tion and re-formation of these salts must be continuously going on, that is to say the sulphur atoms are in uninterrupted migration from salt to salt.The molecules of liquids are regarded as being in a state of con-tinual motion-translatory rolling one over the other and rotating round their centres of gravity (Clausius Abhandlzclzgen 1867 2,237). The colliding molecules must come in this way in variable positions towards each other. Not every relative position of 2 mols. enables them to enter into chemical reaction but of all positions which 2 mols. can assume towards each other there will be one more favourable to chemical action than the others. This relative position of 2 mols. towards each other I will call their " position of reaction. WACKENRODER’S SOLUTION. 321 Whenever 1 mol. of potassic pentathionate meets a molecule of potassic trithionate in the position of reaction 2 mols.of potassic tetrathionate will be the result of their interaction (p. 319) o r if a molecule of potassic pentathionate meets with one of tetrathionate in the position of reaction the transfer of a sulphur-atom from the pentathionate to the tetrathionate will follow. The penta- becomes tetra- and the tetra- penta-thionate. Two molecules of potassic tetrathionate in their position of reaction produce one of trithionate and one of pentathionbte. Like a pendulum which during its fall acquires the necessary uis viva to rise again to a height equal to that of its descent so the sulphur atoms of one polythionate acquire during decomposition the necessary energy to combine with another polythionate. The decomposition represented by the equations mentioned before and the conditions under which they occur require of necessity the migration of one sulphur atom of potassic tetrathionate and of two sulphur atoms of potassic pentathionate between the molecules of the potassic polythionates ; hut they also point out that after some time a certain transient ratio between the quantities of the polythionates will be established.This will occur if in a unit of time as much of each of the salts present is re-formed as is decomposed. If one of the three polythionates penta- tetra- or tri-thionates is dissolved in water the solution will after some time contain all three and their relative quanfities will depend on the conditions just stated. If this state of equilibrium between the formation and decomposi-tion of the polythionates could be maintained then the relative quantities of the different salts would remain unaltered.But this cannot be on account of the decomposition of potassic trithionate into potassic sulphate sulphurous acid and sulphur a chemical change which cannot be rerersed. Ths oxidation of the sulphurous to sulphuric acid which prevents the decomposition of penta- and tetra-thionate exercises also in course of time a disturbing influence. As soon as a certain amount of hydric sulphate has accumulated the spontaneoiis decomposition of potassic penta- and tetra-thionate will cease but that of potassic trithionate will go on. Hence the final state of equilibrium which ought to result after a long time (several months) would be potassic sulphate hydric sulphate sulphur potassic tetrathionate and potassic pentathionate each of them in certain fixed quantity and not undergoing further chemical change.Another important conclusion following from the equations (p. 319) is that in spite of the liquid condition the molecules come comparatively seldom into the position of reaction. Equation (2) is only partially realised after a 10 per cent. solutio 32 2 DERUS CHEMICAL INVESTIGA TION OF of potassic tetrathionate has been kept for 12 days. In this trans-€ormation no external energy has to be introduced the internal forces are sufficient for the purpose and nevertheless it proceeds very slowly probably f o r the reason given. But if the mo:ecules although they are in the liquid state only seldom assume t h e position of reaction towards each other then t h e y cannot be so movable arnongst each other as i3 commonly assumed they must have a tendency dependent on their chemical nature to set themselves in certain positions towni-ds each other and these positions need not be the positions of reaction.A solution of potassic penta-thionate decomposes by degrees into potassic tetrathionate and sulphur. If a molecule of sulphur contains only six atoms of sulphur and if the composition of potassic pentathionate in solution is the same as in the dry state then 3 mols. of hydrated potassic pentathionate must come into the position of reaction in order to decompose according to the equation-3[2Ki,S,0,,3H20J = 6K2Sa06 + s + 9H,O. The slowness of this decomposition indicates that the position of reaction is not often assumed by the molecules of potassic penta-t hionate.If now we consider molecules of potassic tetrathionate placed between the molecules of the pentathionate then the decomposition of the latter ought to be further retarded. The mere presence of tetra-molecules between the penta-molecules would be a mechanical hindrance to the latter to meet in the position of reaction and the tetra-molecules would also have a tendency to combine with sulphur in s t a t u nascendi set free by the decomposition of potassic penta-thionate and with this sulphur again to form potassic pentathionate, thus restoring the original state of things. To test this conclusion the following experiments were made. Four solutions were prepared of the following composition -I.0.6 gram of potassic pentat'hionate in 10 C.C. of water. 11. 0.6 gram of potassic pentathionate and 0.5 gram potassic tetrnthionate in 10 C.C. of water. 111. 0.6 gram of potassic pentathionate and 2-5 grams of potassic tetrathionate in 15 C.C. of water 1 mol. of K2S,06 and 5 mols. R,S,Os. IV. 0.483 gram of potassic pentathionate and 4.09 grams of potassic tetrnthionate in 15 C.C. of water or 1 mol. of K,S,0,,1&E20 + 10 mols. K2S40s. The solutions were perfectly clear and neutral and were placed i WACKENRODER'S SOLUTION. 323 corked tubes in the same test-tube stand. .After the lapse of 10 days, the following changes had taken place :-I and I1 had deposited a small precipitate of snlphur I11 and IV were still clear and like I and 11 neutral.After the lapse of 14 days an increase in the quantity of the sulphur precipitate in I and I1 was noted ; I was still neutral I1 slight'ly acid. Some of the potassic tet'rathionate of I1 had decomposed into sulphur and trithionate and some of the latter into potassic sulphate sulphur, and sulphurous acid. I11 was still clear but slightly acid and produced with baric chloride a little baric sulphate. NO odour of sulphurous acid was percep tihle. IV was slightly turbid smelt of sulphurous acid and gave a copious precipitate with baric chloride. The sulphur of I and I1 was collected on weighed filters. I gave 0.020 gram. I1 only 0.004 ,, That is to say the solution of pure potassic pentathionate had deposited in 14 d q s five times as much sulphur as the solution which contained for every molecule of potassic pentathionate a molecule of potassic tetrathionate or two-fifths of the pentathionate of I and only two twenty-fifths of that salt of I1 were decomposed.Solution I11 was still clear after the lapse of 21 days and free from the smell of sulpliiirous acid but IV now contained much precipitated sulphur and also free sulphurous acid. I n the course of the fourth week sulphur and sulphurous acid also appeared in Solution 111. In another series of experiments with three solutions of which the first contained only potassic pentathionate the second in addition to every molecule of pentathionate a molecule of tetrnthionate and the third 2 mols. of t'etrathionate to 1 of pentathionate similar resnlts were obtained.After the lapse of seven days much sulphur was found in the solution of pure potassic pentathionate considerably less in the solution which contained an equal number of molecules of both salts and none at all in the liquid in which the molecular ratio of penta- to tetra-thionnte was as 1 to 2. These experiments prove that the decomposition of pota ssic penta-thionate into potassic tetrathionate and sulphur is retarded by the presence of potassic tetrathionate and that the degree of retardation is dependent on the quantity of potassic tetrathionate. The retardation was greatest in the above experiments when the solutions contained 1 mol. of potassic pentathionate to 5 mols. of the tetrathionate. The decomposition became accelerated again whe 324 DEBUS CHEMICAL IXVESTIGSTIOX OF 10 mols.of tetrathionate were mixed with 1 mol. of pentathionate, because the chemical change represented by equation (2) (p. 319) tends to increase the quantity of the potassic pentathionate. By means of similar experiments it was proved tlia t the decomposition of potassic tetrathionate expressed by equation (2) (p. 319) is retarded by the presence of potassic pentathionate. The cause of this influencr is easily seen. If we add potassic pentathionate to a solution of potassic tetrathionate which is partially decomposed according to the equation-2K,S,O = K&06 + K2S30,, TTrith formation of potassic trithionnte then t'he sulphur liberated by the spontaneous decomposition of the pentathionate-K,S,O = K&O + s, will combine with the trithionate and reproduce tetrathionate and so prevent the decomposition expressed by the equation-K,S;,O6 = K2SOd + SO + s.Not less intelligible is the fact that for a certain proportion of the two salts potassic tetra- and penta-thionate the rate of change will be a minimum and if one of these two salts is present in greater pro-portion its peculiar decomposition will preponderate a8nd thereby increase the rate of change. It has been shown that hydric sulphate prevents the spontaneous decomposition of potassic penta- and tetra-thionates. A certain pro-portion of the sulphate about 2 per cent. is sufficient for this purpose, :tnd its action consists in preventing the molecules of these polythio-iiates from assuming towards each other the position of reaction.The hydric sulphate has a polarising action on the molecules and, perhaps in a similar way it acts on the molecules of water in electro-lysis. Explimation of two Properties of Ozone. Ozone and potassic pentathionate resemble each other in some respects ; both undergo slow spontaneous decomposition. Acids render them more stable.* Alkalis cause rapid chemical decomposition, oxygen is given off from ozone and sulphur from potassic penta-t,hionate.t Both the oxygen liberated from ozone and the sulphur from the pentathionate were in endothermic combination. * V. Babo Bmelin-Kraut Randbook 1 26 ; Jeremin Jahresbericht by Liebig. t Soret Gmelin-Kraut 1 and 2 27. &c. 1878 197. This paper p. This paper p. 311 WACKENRODER'S SOLUTION. 325 An aqueous solution of potassic pen tathionate decomposes very slowly into potassic tetratbionate and sulphur.Ozone by degrees, at common temperatures returns to the condition of ordinary oxygen,* and both transformations agree in this respect that they are not com-plete after the lapse of six months. The explanation given of the spontaneous decomposition of potassic pentathionate may therefore, with a high degree of probability be applied to the slow chemical change of ozone. Concentrated solutions of potassic pentathionates decompose with greater rapidity than weak ones and oxygen highly charged with ozone loses the latter more quickly than gas which contains a smaller quantity of ozone. Whenever 2 mols. of ozone meet under favourable conditions that is to say when they come into such a position that an oxygen atom of one can combine with an oxygen atom of the other, or in other words when they come in the position of rewtion then 2 mols.of ozone will be transformed into 3 mols. of common oxygen. This will happen more frequently in a gas which contains a larger than in one with a smaller number of ozone molecules. The 2 mols. which participate in this reaction are of comparatively simple structure, so that we may assume that every collision brings them into the position of reaction and causes their conversion into oxygen. Notl two but perhaps six or more molecules of potassic penta-thionate molecules of complex structure must collide in the position of reaction in order to produce a molecule of sulphur and potassic tetrathionate.This will d priori not happen in every collision as in the case of ozone and consequently we arrive at the conclusion that the spontaneous decomposition of potassic pentathionate into sulphur and potassic tetrathionate will be a much slower process than the transformation of ozone into oxygen. The facts are in perfect accord with this conclusion. Ozone if kept. will become richer in oxygen and poorer in ozone, at first rapidly afterwards as the quantity of oxygen becomes larger more and more slowly until a t last a small residue of ozone appears to undergo no further diminution (Berthelot). Brodie (Phil. Tmns. 1872,445) observed that ozonised oxygen when kept lost nearly one-third of its ozone in the first 90 hours. The loss during this interval of time was by no means uniform but dimi-nished rapidly towards the close.It amounted during the first 66 hours to nearly & and during the next 24 hours only to 2% of the original quantity. The oxygen molecules as they increase in numbers and move between the ozone molecules diminish the 'frequency of collision between the latter and the consequent production of oxygen just as f Andrews and Tait Qmelin-Kraut 1 and 2 26 ; Berthel.ot Jahreshericht 1818, 197; Brodie Phil. Z'pans. 1872 445. VOL. LIlI. 32 ii DEBUS CHEMICAL INVESTIGATION O F potassic tetrathionate retards the decomposition of potassic penta-thionate. And applying the explanation of the chemical action between these two salt,s to ozone and oxygen we arrive at the con-clusion that the oxygen molecules during their motion of translation, and consequent collisions with ozone molecules take an atom of oxygen from the latter and thus become ozone molecules and the ozone molecules in consequence of this loss will become oxygen molecules.Expressed in other words in ozonised oxygen the ozone is continually decomposed and re-formed or oxygen atoms migr:bte between oxygen and ozone molecules. I n the same way as has been shown a siilphur atom passes from a molecule of potassic pentathionate to a molecule of potassic tetrathionate the latter becoming peiita- and the former tetra-thionate. The conversion of ozone molecules into oxygen molecules during the keeping of ozonised oxygen as well as the retardation of this pro-cess as a consequence of an increase of the quantity of tbe oxygen of the mixture are I think fully explained by tbe theoretical views described.But also the fact that the amount of ozone i n oxygen cannot be increased beyond a certain limit call be deduced from the same conceptions. The oxygen molecules are split into atoms by electricity and the atoms so set free combine with oxygen molecules to form ozone. The ozone molecules by their collisions again form oxygen molecules. The limit beyond which oxygen cannot be changed to ozone is attained when in a given time as much ozone is repro-duced in one operation as is decomposed in the other. Explanation of the Decomposition of Peroxide of Hydrogen. This substance comports itself in a chemical sense very much like ozoiie and pentathionates.An aqueous solution ol peroxide of hydro-gen contains less of the latter substance a few months after prepara-tion than it did a t first probably in consequence of decomposition, according to the equation-2H202 = 2H2O + 0 2 . This decomposition proceeds more rapidly in concentrated than i n weak solutions and is accelerated by a rise of temperature.* A solution which in one litre contained 3 8 5 grams of active oxygen, in 87 days lost 3.678 grams but was not completely decomposed after two years. Older samples had lost all their peroxide of hydrogen. This behaviour is very like that of a solution of potassic pentathionate, * Berthelot Jahresbericht 1880 p. 136; also according to my own observa-tions R A CKCNRODE R'S SOLUTION. 32 7 and both substances are endothermic compounds.Whenever 2 mols. of peroxide of hydrogen meet in the position of reaction then decompo-sition into water antl oxygen will take place but if they collide i n other positions thcn they will not decompose. From this teiict the properties of perosirle of hydrogen mentioncrl before can be deduced. The spontaneous decomposition will bo retarded when water molecules are placed between the niolecules of peroxide of hydrogen a,nd tlie retardation will increase with the quan-tity of water. d weak solution ole peroxide of hydrogen is more stable than a concentra,ted one. The similarity which exists between the spontaneous decompositions of potassic pentathionate antl peroxide of hydrogen justifies i l i e assumption that peroxide of hydrogen and water comport themselves towards each other like potassic pantatIiiona0e and tetrat hionate.It has been prove(l that an atom of sulphur can separate from penta-thionate and unite with tetratliionate (p. 323). By analogy then we conclude that when R molccule of water am1 a molecule of peroxide of hydrogen during collision asslime the posit;on of reaction the water will become peroxide of hy'irogen and the peroxide of hydrogen water that is to say an atom oE oxygen will migrate from one mole-cule to another. The peroxide of hydro9en in an aqueous solution is therefore in a continunus state of dec~otuposition and formation hoir-ever in such a -way ifhat for each stale of concefltration the arnonnt of decomposition (very small in weak solutions) prevails over the amount of forniaii,m i n the same time.The decomposiiion of peroxide of hydrogen into water and oxygen is retarded by some and acceleraled by other substances. Platinum, silver. oxide and manganic dioxide respectively promote whilst acids preI-ent the decomposition. Platinnm possesses a great attraction for oxygen its powder absorbs more than 200 times its volume of the gas. This attraction is also exerted towards oxygen which is in chemical combination. If now a piece of platinum is placed in peroxide oE hydrogen the molecules of the latter will place themselves in such a position on the surface of the platinum that one oxygen-atom of the peroxide*is turned towards the plat'inum arid a s near to it as possible. The per-oxide is polnrisetl. Hut th i s has the effect also of bringing the oxygen-atoms of different moleciiles of peroxide in such close proximity on the surface of tlie metal t h a t they can combine to form common oxjgen the decomposition of the peroxide into water and oxygeii and development of euergy being t h e consequence.The action of the platinum places the rnolecules of the peroxide in the posL'tiora of reuctioib towards each other. The action of silver oxide and of black oxide of manganese are similar. 2 328 DEBUS CHEMICAL INVESTIGATION OF Similar observations can be made on the aqueous solutions of the oxides of chlorine &c. (Williamson Annalen 54 133). The Action of Hydric Xulphide on Pentathiolzates. 2.95 grams of potassic pentathionate were dissolved in 20 C.C. of water and a very concentrated solution of 8.458 grains of dihydric tartrate added.The precipitated potassic hydric tartrate was after two days’ standing removed by filtration and a slow current of hydric sulphide passed for half an hour through the clear filtrate. The liquid was now put aside in a well-stoppered cylinder for 24 hours. The smell of hydric sulphide had disappeared after the lapse of this time. This treatment with hydric sulphide was repeated several times until all the hydric pentathionate was decomposed. The result of these operations was a copious precipitate of sulphur and a clear colourless liquid. Only a trace of trithionic acid could be discovered in this liquid. Hydric pentathionate and hydric sulphide therefore form water and sulphur :-H,S,06 + 5H2S = GH2O + 10s.The non-production of hydric sulphate is interesting. An aqueous solution of 10.3 grams of potassic pentathionate was treated like hydric pentathionate with hydric sulphide until no further action appeared to take place. A copious precipitate of sulphur had collected which was separated by filtration and the filtrate care-fully examined. Potassic trithionate and potassic thiosulphate were detected and obtained in crystals by evaporation. The reactions are probably represented by the following equa-tions :-K:,SjOs + H2S = K2SZO3 + H,S?O + Sz H2S,03 = SO + H,O + S 2K2S203 + 3SOs = 2K2Sj06 + S, and these united :-3K2S5Os + 3HzS = K-SSZO + 2K,S30 + 3HzO + 10s. Action of Hydric Xulphide on Tetrathionates. A solution of pure hydric tetrathionate prepared by the same method as that by which the corresponding pentathionate had been obtained was treated repeatedly with hydric sulphide till the decom-position appeared to be complete.Less sulphur was precipitated in these operations than in the cor-responding experiments with hydric pentathionate. In the resulting liquid hydric pentathionate alone could be discovered. From this i WACKENRODER’S SOLUTION. 329 appears that hydric tetrathionate decomposes with hydric sulphide iuto water and sulphur,:-H2S406 + 5H2S = 6HzO + YS. Some of the sulphur in statzc nnscendi combines with hydric tetra-thionate to form h ydric pentathionate. If the treatment with hydric sulphide had been continued long enough only water and sulphur would have been obtained. Action of Hydric Xulphide o n Trithionales.Hydric sulphide acts on potassic trithionate only very slowly much more slowly than on pentathionates or tetrathionates. A solution of potassic trithionate saturated with hydric sulphide had to stand three days before all the hydric sulphide was decomposed. The odour of sulphurous acid could then be perceived and a precipitate of sulphnz. had fallen down. The liquid was separated from the sulphur and examined after it had undergone four treatments with hydric sulphide. Potassic thiosulphate potassic sulphate and sulphur were the only products of decomposition found :-Hydric trithionate was prepared from the barium salt and the latter from a Wackenroder’s solution which contained some free sulphurous acid and baric carbonate.The baric pentathionate and tetrathionate were deprived by the baric sulphite respectively of two and of one atom of sulphur and converted into baric trithionate tbe baric snlphite itself becoming bark thiosulphate. Analysis of the baric tritbionate :-0.3915 gram dried over hydric sulphate and oxidised with bromine-water produced 0.259 gram and the filtrate on addition of baric chloride 0.505 gram of baric sulphate. 100 parts of the salt contain according to these numbers 38.88 parts of barium and 26.89 parts of sulphur. The formula 2BaS306 + 3Hz0 requires 38.48 parts of barium and 86.97 parts of sulphur. The atomic ratio is-Ba S = 1 2.94. 5.942 grams of this salt were dissolved in 50 C.C. of water and pre-cipitated with 1.687 gram of hydric sulphate.The filtrate from the baric sulphate measured 75 c.c. and comported itself with reagents like h y dric t ri t h ionat e. Twenty-four hours after preparation the filtrate had acquired the odour of sulphurous acid and a precipitate of sulphur had fallen down. The latter was separated by filtration and the clear liquid placed unde 330 DEBUS CHEMICAL INVESTIGATION O F a bell-jar over pieces of potassic hydroxide. The sulphurous acid volatilised in the course of two days but another precipitate of sulphur was found in the liquid. Put back into a closed bottle the odour of sdphurous acid reappeared in one 01' two clays. These Observations irldicate that hydric trithionate is a t common tempcratures in a slow state of decomposition. After several weeks undecomposed hydric trithionate could still be detected by means of a qualitative examina-ti o 11.'l'wo days after the preparation of the hydric trithionate no hydric pentathionate could be delected in it but after the hpse of 14 days, considerable quantities of it and also of hydric sulphate were observed. 'The equation-H,S,j06 = HZSO + SO2 + s, 1-epresents the slow decomposition of the solution. But the sulphur does not all separate in the free state a portion unites with undecom-posed hydric trithionate forminq hydric pentathionate and probably h ydric tetrathionate. The solution of hydric trithionate behaves in the same manner during evaporation on the water-bath only the decomposition is much more rapid. But even after the solution has been evaporated to + of its original volume and has parted with much sulphur and sulphurous acid undecomposed hydric trithionate can be detected in it.I concluded from these observations that hydric tritliionate would be easily decomposed by hjdric sulphide. Experi-ment proved this conclusion to be erroneous. A solution of hydric t ri thionate was saturated with sulphuret ted hydrogen immediately after its preparation and kept in a closed bottle for three days. No change could be observed the liquid seemed to contain after this lapse of time as much hydric sulphide as i t did immediately after the passage of the gas. Over pieces of potassic hydroxide under a bell-jar it lost, in a few days the sulphuretted hydrogen and a little sulphur was precipitated. The qualitative examination revealed the presence of some hydric sulphate and hydric pentathionate besides the hydric trithionate.Hence it appears that hydric trithionate is not acted upon 5 y hydyic sulphide a t commoii temperatures. Hy dric pentathionate and hydric tetrathionate are easily decom -posed by hydric sulphide ; hydric trithionate a far less stable compound, which slowly evolves sulphurous acid is not acted on. The explana-tion of this anomaly appears to me to be as follows :-Hydric tetra- and penta-thionate produce with hydric sulphide water and sulphur but n o h y d k sulphute. The hydrogen of the ~ J J chic sulphide reacts with the oxygen of these compounds. During A second experiment gave similar results WACKENRODER'S SOLUTION. 331 their spontaneous decomposition in aqueous solutions sulphur is separated but no sulphate is produced.An aqueous solution of hydric trithionate on the other hand is continuously in a slow st'ate of de-composition with formation of hydric sulphate. The arrangement of the atoms in t'he trithionate must be such that the affinity of sulphur for oxygen is easily satisfied. In the case of a solution of hydric tri-thionate saturated with hydric sulphide two influences make them-selves felt. On the one hand the afEnity of the sulphur atoms for the oxygen atoms a,nd on tbe other hand the affinity of the hydrogen of the hydric sulphide for the oxygen of the trithionate. These two attractions are opposed to and counterbalance each other so that a solution of hydric trithionate saturated with hydric sulphide is accord-i n g to experinlent more stable than one of pure hydric trithionate.A different result is obtained where hydric sulphide is passed into a mixture of the three polythionates hydric trithionate hydric tetra-thionafe and hydric pentathionate. The hydric trithionate quickly disappears. Sulphuret ted hydrogen and hydric tetra- or penta-thionate produce water and sulphur. Sulphur in sfatu nascendi combining with hydric trithionate forming respectively tetrathionate and pent at h i on ate . Prom the foregoing observations the conclusion may be drawn that if a current of sulphurelted hydrogen is passed through a Wach-en-roder's solution in which hyclric trithionate hgdric tetrathiona t,e and hydric pentathionate are present) until t h e gas ceases to act on tlie solution water and sulphur will be the f i n d products of decomposition.This conclusion was verified by experiment. The equation-by which t)he text-books represent the chemical action between hydric sulphide and sulphurous acid is correct for the filial products of the reactions. The polythionntes a,re intermediate products be tween the original materials sulphurous acid sulphurelt,ed hydrogen and water on the one hand and sulphvr and waler the fixed products on tbe other. Action of Sulphurous Acid o n Polythiosmtes. Action of XulpIcurods Acid on Hydric Pe7itathinnate. Sulphurous acid parhially converts hydric pentathiovate into hydric trithionaLe. The solution oE hyclric pentra,bhiooate was obhined by the precipitation of poiassic peviil,oh;outtie wihh hydric dartrnte as described on p.328. One volume of ths liquid so prepared was mixe 332 DERUS CHEMICAL INVESTIGATION OF with two volumes of concentrated hydric sulphite. The colourless liquid became intensely yellow in the course of three hours and during the following t,wo days deposited some sulphur. After it had been kept in a closed bottle for three days i t was placed over pieces of potassic hydroxide under a bell-jar and allowed to remain till all the sulphurous acid had volatilised and combined with the base Sulphur was precipitaked whilst the sulphurous acid was escaping and the yellow liquid became colourless. After all the sulphurous acid was gone a qualitative examination of the remaining liquid proved the presence in it of hydric trithionato and hydric pentathionate.The action of sulphurous acid on hydric pentathionate may therefore be explained as follows The sulphurous acid withdraws sulphur from the pentathionate forming a yellow solution. This solution of sulphur in sulphurous acid deposits some of its sulphur in the form of a precipitate when i t is left standing in a closed bottle or during the vo1at;ilisation of the sulphurous acid. The pentathionate from which the sulphur has been taken by the sulphurous acid becomes in con-sequence hydric trithionate. The sulphur unites with the sulphurous acid with a very feeble force the compound behaving like a simple solution of sulphur in sulphurous acid. I will assume that this com-pound which we shall have to consider again is thiosulphuric or hyposulphurous acid S202 :-H?S,O + 2S02 = H?S,O + 2x202.This decomposition is however incomplete even a Zlxrge excess of sulphurous acid does not convert all the pentathionate into trithionate. Probably therefore the reaction is of a reciprocal nature and the hydric trithionate can receive from thiosulphuric acid SzO, sulphur, and re-form hydric pentathionate. Action of Sulphurous Acid or Sulphites on Potassic Pentathionate. 10 grams of potassic pentathionate dissolved in 30 C.C. of hydric sulphite to a yellow liquid. Baric carbonate was now added until all the acid was neutralised. Instead of baric sulphite baric thiosulphate was obtained as an abundant crystalline precipitate. The filtrate from the sparingly soluble baric thiosulphate was freed from barium by careful addition of potassic carbonate and then concentrated for crystallisation.No potassic pentathionate could be detected the reaction with metallic salts like those of potassium or barium therefore is complete. The reactions can be represented by the following equations :-K2S,0 + 2S0 = K2S306 + 2S202 and 2BaC0 + 2S20 = 2BaSZ0 + 2C0,. Crj-stals of pure potassic trithionate were obtained WACKENRODER'S SOLUTION. 333 Action of Dipotassic Sulphite on I'otassic Pentathionate. 4 grams of pure potassic pentathionate dissolved a t 17" in 20 C.C. of water with a reduction of 3" of temperature. The solution was mixed with one of pure dipotassic sulphite K,SOs. A consider-able quantity of sulphurous acid was set free and a small precipitate of sulphur formed.Addition of barium chloride caused the precipita-tion* of a large amount of baric thiosulphate. The proportionally large quantity of the latter and the evolution of much sulphurous acid lead to the conclusion that dipotassic sulphite is decomposed by water into potassic hydroxide and sulphurous acid and that the potassic hydroxide decomposes the potassic pentathionate according to the equation-2K2S506 + 6KH0 = 5K,X2O3 + 3H20. Action of Xulphurous Acid on Hydric Tetrathionate. The hydric tetrathionate was prepared by double decomposition of potassic tetrathionate and hydric tartrate. One volume was mixed with two volumes of a concentrated solution of sulphurous acid. The mixture was still colourless three hours after preparation and turned yellow in the course of the three following days but without sepura-tion of sulphur.Placed over pieces of potassic hydroxide under a bell-jar for the removal of the sulphurous acid the yellow colour dis-appeared with the sulphurous acid but without the precipit'ation of sulphur (p. 332). The examination of the liquid after the sulphurous acid was gone proved the presence of much hydric trithionate and hydric pentathionate. The sulphurous acid had acted on the tetra-thionate in the same way that it does on the pentathionate it had taken away sulphur from the h-ydric tetrathionate and thus convertecl the latter into hydric trithionate. But the thiosulphuric acid &02, instead of precipitating sulphur during standing or during evapora-tion of the sulphurous acid gave up half its sulphur to hydric tri-thionnte or undecomposed hydric tetrathionate thus causing the formation of hydric pentathionate.The reciprocal nature of the reaction mentioned a,s an explanation on p. 332 is thus confirmed. Action of Sulphairous Acid on Wuclzenroder's Solution. A sample of this solution which did not contain sulphuretted hydrogen or sulphurous acid was used for the following experiments, without concentration on the water-bath. The 8-sulphur in solution as well as the sulphur in suspension were precipitated. To a small portion Borne cupric sulphate was added 334 DEBUS CHEMICAL INVESTIGATION OF The filtrate of this precipitate remained clear a t lOO" hence hydric trithionate was not present. From another portion the collo'idal sulphur was precipitated by a solution of saltpetre and the filtrate from the sulphur tested with an ammonia-silver nit'rate solution.Much hydric pentathionate was discovered. Tetrathionste and hexathionate were also present. Some of this Wackenroder solution was mixed with twice its volume of a concentrated solution of sulphurous acid. The mixture was then divided into two portions one portion was placed over pieces of potassic hydroxide under a bell-jar the other portion tested with cupric sulphate. A considerable dark-brown precipitate was obtained indicating much hydric trithionate. Sulphurous acid solution or the Wackenroder solution each heated with cupric sulphate to loo" re-mained unchanged. The portion of the mixture of sulphurous acid and Wackenroder solut8ion which had been placed over pieces of potassic hydroxide, was likewise tested with cupric sulphate after the volatilisation of the sulphurous acid.No precipitate was obtained at loo" conse-quently no hydric trithianate o r hydric tliiosulphate was present. The sulphur which had been wit>hdrawn from hydric tetrathionate or hydric pentathionate by the sulphurous acid had again united with the hydric trithionate during the voldilisation of the sulphurous acid thus re-forming hydric tetrathionate and hydric pentathionate. Another portion of a mixture of Wackenroder solution and liydric sulphite was allowed to stand 24 hours in a closed bottle before it was placed under a bell-jar over pieces of potassic hydroxide. After the volatilisation of the sulphurous acid considerable quantities of hydric trithionate were discovered by means of cupric sulphate.Another larger portion of Wackenroder's solution was saturated with sulphurous acid gas and then lel't to stand five days in a closed bottle. The liquid was perfectly clear and yellow at the end of this time the collo'idal sulphur having precipitated. It contained, however much sulphur in the form of thiosulphuric acid S,O (p. 332). I will mention here a few more observations on khe properties of this combination of sulphur and sulphurous acid. If left to stand for a long time sulphur will continually but slowly separate from it. The yellow colour becomes paler in consequence. But it appears to require many months before all the sulphur will pre-cipit,ate in this manner.Hydric chloride hydric sulphate potassic nitrate sodic chloi idc respectively do so with decoloration of the solution. The same effect follows the volatilisation of the sulphurous acid either spontaneously 8 t common temperatures or by boiling. I have not been able to separate this The addition of water causes no precipitation oE sulphur WACKENRODER'S SOLUTION. 335 compound from the solution it seems to exist only in presence of free sulphurous acid. Neutralisation with bark carbonate throws down baric thiosulphate as a precipitate leaving baric trithionate in solution. A precipitate so obtained was almost entirely soluble in boiling water, and the solution gave crystals of baric thiosulphate on evaporation. 0.664 gram of the crystals dried over hydric sulphate and oxidised with bromine-water gave 0.596 gram baric sulphate and the filtrate with baric chloride 0.584 gram of the same salt.Hence in 100 parts :-Theory. Found. 3BaS20 + 2H,O. Barium 52.72 52.49 Sulphur 24.40 24.52 For this reason I regard the yellow solution of sulphur in sulphurous The filtrate of the bark thiosulphate gave a crystalline precipitate acid as thiosulphuric acid SzO,. with alcohol. I. 0.739 gram of this precipitate left after ignition 0.482 pan1 bark sulphate. 11. 0.573 gram gave 0.376 gram baric sulphnte. 111. 0-283 gram oxidised with bromine-water gave 0.185 gram baric snlphate and the filtrate on addition of baric chloride again 0.360 gram of the same salt. Hence in 100 parts :-Found. r- 7 Theorv.I. 11. 111. 2BaS,O +" 3H20. Barium . . 38.28 38.59 38.28 38.48 Sulphur - - 26.45 2696 If Wackenroder's solution contains besides its usual constituents hydric pentathionate hydric tetrathionate and hydric hexathionnte, a sufficient quantity of sulphurous acid then only baric thiosulphate and baric trithionate are obtained after neutralisation with baric carbonate. This behavionr probably explains the results obtained by Cnrtius. These observations and experiments explain perfectly the action of. sulphurous acid on a Wackenroder solution. Immediately after the mixture has been prepared some of the hydric pentathionate and hydric tetrathionate are reduced by the sulphurous acid to trithionate, the sulphurous acid itself forming thiosulphuric acid SzOz with sulphur.If now a t once or very soon after the preparation of the mixture volatilisation of the sulphurous acid takes place then half the sulphur of the thiosulphuric acid SzOz will reunite with the trithio 336 DEBUS CHEMICAL INVESTIGATION O F nate forming hydric tetrathionate and hydric pentathionate and the original state of things is re-established. B u t if the mixture is allowed to stand for some time one or more days before the volatilisation of the sulphurous acid then a portion of the sulphur of the thiosulphuric acid S202 will precipitate in one of the ordinary modifications. If after such precipitation volntilisation of the sulphurous acid occurs then the sulphur resulting from the decomposition of the remaining thiosulphuric acid S202 is not sufficient to convert all the hydric trithionatc into tetrathionate or pentathionate.After the evaporation of the sulphurous acid the solution then contains hydric trithionate as is shown by the following experiment. A portion of the Wackenroder's solution charged with sulphurous acid as men-tioned on p. 334 was deprived of its sulphurous acid after five days' standing. The qualitative examination revealed much hydric trithionate and on account of the reciprocal nature of the reactions also hydric tetra-thionate and hydric pentathionate. The yellow colour of another portion of the solution had almost disappeared a year afterwards, that is to say nearly but not all the thiosulphuric acid S202 was decomposed. After removal of the sulphurous acid by evaporation, hydric trithionate hydric tetrathionate hydric pentathionate and hydric hexathionate were found in the remaining liquid.In$icence of Time on the Formation of Hydric Pentuthionate. To a saturated solution of sulphnretted hydrogen a solution of sulphurous acid was gradually added drop by drop until the odoni. of hydric sulphide had disappeared. Every drop of sulphurous acid caused a precipitate of sulphur. The action therefore appears to be instantaneous and the mixhre ought not to contain either of the substances. A tube was now quite filled with the mixture and the liquid poured from it into a larger vessel and shaken with air. The latter acquired the smell of sulphurous acid and paper moistened with lead acetate turned brown when immersed in the air conse-quently small quantities of hydric sulphide and sulphurous acid can exist for some time in a liquid prepared as described without mutual decomposition revealing their presence by their usual odour.The experiment was now repeated in reversed order. A slow current of sulpharetted hydrogen was passed for 20 minutes through a saturated solution of sulphurous acid at 0". After the lapse of 10 minutes, some of the liquid was shaken in a large vessel with air ; the latter took up sulphurous acid gas but not hydric sulphide. The liquid, however turned a paper moistened with lead acetate brown. The latter reaction could not be obtained after 12 hours WACKENRODER’S SOLUTION. 337 The same results were obtained after the liquid bad been treated a second time for 20 minutes with sulphuretted hydrogen.After a third treatment with sulphuretted hydrogen the sulphurous acid appeared to be decomposed. The liquid no longer smelt of sulphurous acid, but had a feeble odour of hydric sulphide. Also when the liquid was shaken with air it did not acquire the smell of sulphurous acid. The feeble odour of hydric sulphide disappeared however after three hours’ standing and a strong smell of sulphurous acid could now be perceived. Some of the liquid now shaken with air transferred to the latter both sulphurous acid and sulphuretted hydrogen the former recog-iiisable by its smell and t<he latter by its action on paper moistened with lead acetate. Even eight days after these experiments traces of sulphuretted hydrogen and sulphurous acid could be detected in the liquid.Similar observations were made repeatedly. The experiments described show that although concentrated soln-tions of sulphurous acid and sulphuretted hydrogen react immediately, small quantities of these two substances can exist side by side in a Wackenroder solution for some time without decomposing each other. An aqueous solution of sclphurous acid heated on a water-bath very soon loses all its acid. A similar solution mixed with sulphur powder requires a very much longer time for the volatilisation of the sul-phurous acid. Between sulphur and sulphurous acid a considerable attraction exists which manifests itself under the circumstances described. The Wackenroder solution holds much colloiidal sulphur in suspension and solution and this by its attraction for the sul-phurous acid may be the cause of the phenomena described.Perbaps also thiosulphuric acid S202 (p. 332) may be present in a Wacken-roder’s solution and by its slow decomposition into sulphur and sulphurous acid cause the reappearance of sulphurous acid some hours after the preparation of the Wackenroder’s solution appears to be finished. The yellow compound of sulphur and sulphurous acid, which I have called thiosulphuric acid plays an important part in the formation of hydric pentathionate. A slow current of sulpliuretted hydrogen was passed through 500 C.C. of a nearly saturated eolution of sulphurous acid at o”, 50 C.C. were taken out after the current had passed 25 minutes and placed in a closed bottle and another 50 C.C.were placed over pieces of potassic hydroxide under a bell-jar. Through the remaining 400 C.C. of the liquid a slow current of sulphuretted hydrogen was again passed for 65 minutes and then 50 C.C. were removed to a closed bottle, and another 50 C.C. put over potassic hydroxide 335 DEBUS CHEMICAL INVESTJGATION OF The same operation was repeated three times. I bad conse-quently five portions of liquid of which No. 1 ha,d been treated with sulphuretted hydrogen 25 minutes ; No. 2 50 minutes; No. 3, 85 minutes ; No. 4 120 minuies ; No. 5 180 minutes. The last portion No. 5 did not smell of sulphurous acid immedi-ately after prepaxation but did so two days later. It was then treated for several minutes wif,h sulphureLted hydrogen and after this did not again acquire the srnpll of snlphurous acid.Each of the 0 t h ~ four portions contained much free sulphuroixs acid. Each portion coiisisted of two parts one kept by itself in a bottle, the other over pieces of potassic hydroxide under it bell-jar. The parts over potassic hydroxide had in the course of two or three days lost their free sulphurous acid. They were now examined for the con-stituents OF Wackenroder’s solution. The srilphur in suspension and in solutiou was precipitated by addition of a solution of potassic nitrate and the clmr filtrate of the precipitate tested wilh the reagents mentioned on pp. 297 and 298. No. 1 contained only a very s m a l l quantity of hydric psntathionate and hydric trithiunats. No. 2 contained more of bolh substances than No.1 No. 3 more than No. 9 a,nd No. 4 more than No. 3. No. 5 was richer in penlathionate and poorer in trithionate than No. 4. Examination of the Poytions whi;h had been kept for a few Days in closed E0ttlt.s. These exhibited remarka hle d i Kerences from those which had been placed over potassic hydvoxide immediately after prepai-ation. The last named still possessed the cbfi racter of an emulsion contaiuing much sulphur in snspension and solution. The porlioas which had been kept a few days in closed vessels were with the exception of Xo. 5 clear and of yellow coZo~ii* and no longer belt1 s r ~ ? p h u r in sus-pension nor did they s’uow the slightest opalescence (p. 283). Nos. 1, 2 3 and 4 still containcd con:iclerable quantities oE sulphurvus acid, and sulphur in combination with it as S202.These differences were caused by the sulphurous acid which as will be remembered precipi I ates the suspended and dissolved collojidal sulphur in the course of a few days. After haviiig stood for five days in closed bottles {,he five portions were placed over pieces of potassic hydrwyide under a bell-jay. In proportion as the sulphurous acid volali1ist.d and was absorbed by the potassic hydroxide the solui ions lost their yellow colour arid deposited sulphnr. Arter the Iirpse of 48 hours tbey were colourless and free from sulphurous acid as shown by the test with starch coloured blue by iodine. The odourless a8nd colourless liquid WACKENIZODE R'S SOLUTION. 339 were now separated from the precjpitaCed sulphur by filtration.The examination of the filtrates showed that Nos. 1 2 3 and 4 contained much more hydric pentathionate and trithionate than the correspond-ing portions which had been placed over potassic hydroxide imme-diaiely after preparation. No. 1 of the latt,er set gave wit)h potassic hydroxide or ammonia-silver nitrate only very feeble indications of the presence of hydric pentathiouate. No. 1 of the set which had been kept five days in closed bottles comported itself with the reageuts like a concentrated solution of hydric pentathionate and similar observations were made with regard to the quantities of hydric trithionate in the two sets OE liqiiids. The examination of Nos. 2 3 and 4 gave the same results. No. 5 again contained much less bydric trithionate than Xo.4 but appeared to be richer in penta-thionate . Consequently if a solution of sulphurous avid is partially decom-posed by sulphurefted hydrogen arid then the residual sulphurous acid immedial,ely removed by evaporation a comparatively sniall yield of hydric penta)thiona,te and hydric trithionate is obtained. If however the solution is allowed to siand a few days before the volatdisation of Lhe undecomposed sulphurous acid then compara-tively large quantities of the two polgthionic acids mentioned are formed. The yellow solu-tion of sulphur in sulphurous acid or more probably combination of the two which I have called thiosulphuric acid Sz02 because it Eorms thjosulphates when neutralised wij h bases and decomposes into sulphur and sulphurous acid when the lather can evaporate, seems t o be the source of the hydric pentsthionate.The thiosulphuric acid is only stable in presence of a very large excess of sulphurous acid. If the excess of sulphurous acid be not very large then condensa-tion of t h e thiosulphuric acid into pentathionic acid will take place by degrees :-and How is this unexpected result to be explained ? 5S2O2 = 2S505, 2s50 + 23320 = 2H',S,O,. This condensation dependent on the quantity of sulphurous acid present requires days for its accomplishment and does not occnr at all if the sulphurous acid is in very large excess. Therefore we conclude that i f hydric sulphide be passed through a solution of sulphurous acid uninterruptedly till all t h e acid is decom-posed but liLtle hydric pentathionate will be found in the resnlting mixture.The followiug experiments were made with the view of testing this conclusion. In order to shorten the time of the experi 340 DEBUS CHEMICAL INTrESTIGATION OF ments quantities of 180 C.C. of sulphurous acid only were operated upon at a time instead of 480 or 500 C.C. as on former occasions. A slow current of sulphuretted hydrogen was passed through 120 C.C. of a saturated solution of sulphurous acid a t a few degrees above 0". The decomposition was complete in three and three-quarter hours. Four operations of this description yielded 480 C.C. of Wacken-roder's solution which were evaporated on a water-bath until the residual liquid was of the sp. gr. 1.267. The filtrate from the coagulated sulphur measured 41 C.C.It was diluted to 52 C.C. and was then of the sp. gr. 1.24. Reactions of this Filtrate.-It gave a bright yellow precipitate with mercurous nitrate (absence of hydric trithionate). Potassic hydr-oxide and ammonia-silver nitrate respectively reacted as with penta-thiunates but with feeble intensity. Analysis of the Filtrate. I. 5 C.C. gave with baric chloride 0.281 gram of baric sulphate. 11. 5 C.C. were boiled for a few minutes with mercuric cyanide aud digested at 100" for two hours. The precipitate of mercuric sulphide and sulphur weighed 2.431 grams and the filtrate from this precipitate gave with baric chloride 4.321 grams of baric sulphate. 0.324 gram of the precipitate by mercuric cyanide treated with bromine water gave 0.0425 gram of sulphur and 0.375 gram of baric sulphate which together contain 0.094 gram of sulphur.The filtrate of the 0.375 gram of baric sulphate gave with hydric sulphide 0.266 gram of mercuric sul-phide containing 0.229 gram of mercury. 0.094 gram of sulphur + 0.229 gram of mercury = 0.323 consequently a loss of 0.001. This loss will probably be in tlhe weight of the mercury ; therefore, we take the mercury to be 0.230 gram. Hence 2.451 grams of the precipitate caused by mercuric cyanide contain 0.711 gram of sulphur and 1.740 grams of mercury. 0-524 gram of the precipitat,e of mercuric sulphide and snlphnr was oxidised with aqua regia and gave on precipitation with baric chloride 1-08 gram of bark sulphate containing 0.1483 gram of sulphur. The difference between the weight of the sulphur and the precipi-tate taken is equal to 0.3357 gram of mercury.According to this second experiment 2.451 grams of the mercuric cyanide precipitate contain 0.694 gram of sulphur and 1.757 grams of mercury. The mean of both experiments is 0.702 gram of sulphur and 1.748 grams of mercury WACKENRODER’S SOLUTION. 341 From these numbers we calculate-SO Hg S = 1.984 1 2.51, and for the composition of the hydric polythionates of the Wacken-roder solution analysed-for which we adopt-and for the mean composition of the acids, H2S4.4905.95, H2S4.506, s4.50,. Preparatiom of the Potassium Salts. The remaining 37 C.C. of the analysed solution mere mixed with a concentrated solution of 12 grams of potassic acetate and the mixture placed on a plate i n the window of a draught closet.The dry residue, obtained after 24 hours weighed after pressing between layers of filter-ing paper 22 grams. It was moistened with some water and pressed again between paper whereby i t sustained a loss of 6 grams. The remaining 16 grams were now dissolved in 30 C.C. of water acidulated with 15 drops of hydric sulphate and separated by filtra-tion from a few milligrams of sulphur. A few hoitrs after filtration, the clear liquid deposited a trace of sulphur and in the course of some days gave t w o crystallisations of po tassic tetrathionate. These weighed 6 grams. Reactions of these Crystals. They formed with water a clear colourless neutral solution which on addition of potassic hydroxide and ammonia-silver nitrate respectively remained unchanged but gave a bright yellow precipi-tate with mercurous nitrate.Determinatio 12 of Potass ifc m. 0.831 gram gave 0-478 gram of potassic sulphate. Hence in 100 parts-Calculated. Found. K2S40,. Potassium . . . . 25.7 25.8 The salt t,herefore is potassic tetrathiona ke. A third crystallisation also consisted of nothing but crystals of tetrathionate. The fourth and last crystallisation contained a few crystals of potassic pentathionate which were picked out from the accompanying potassic tetrathionate. VOL. LIII. 2 342 DEEUS CHEMICAL INVESTIGATION OF The entire weight of the latter amounted to 9 grams and of the penta-salt to 1% grams. Consequently the yield of hydric penta-thionate is much smaller when hydric sulphide is passed uninter-ruptedly through a solution of sulphurous acid till tjhe latter is com-pletely decomposed than when the operation is conducted as described on page 281 with interruptions of from 36 to 48 hours when nearly equal weights of the two potassium salts were obtained.These results confirm the theory mentioned on page 339. Weak solutions of sulphurous acid appear to produce propor-tionately larger quantities of the polythionic acids than more concen-trated solutions. Experiment 1.-A elow current of sulphuretted hydrogen was passed for two hours throiigh 480 C.C. of a concentrated solution of sulphur-ous acid and the liquid was allowed to stand for two days. The operation with sulphuretted hydrogen was then repeated for two hours and the solution allowed to stand for 48 hours.The treatment with sulphuretted hydrogen was continued in this manner until all the sulphurous acid was decomposed which was the caseafter two weeks. Expe&nent 11.-Only 120 C.C. of sulphurous acid was taken in the following preparation. The experiment was made in the same manner as the first but required on account of the smaller quantity of acid much less time for its performance. On the first day hydric sulphide was passed for one hour and on the second for an hour and a half the decomposition of the sulphurous acid was then complete. Experiment I11 was made like Expt. I1 with 120 C.C. of sulphurous acid. I n Expts. I and I1 the acid was of the same strength in Expt. I11 an acid of half this strength was taken.Experime?Lt IV was performed like Expt. 11 with this difference, that the sulphuretted hydrogen was passed uninterruptedly until all the sulphurous acid was decomposed. The results calculated for the same quantity of sulphurous acid are as follows:-Expt. I . 480 C.C. of sulphurous acid gave G5 C.C. of Wackenroder Expt. 11. 480 C.C. of sulphurous acid gave 55 C.C. of Wackenroder Expt. 111. 960 C.C. of siilphurous acid gave 55 C.C. of Wackenroder Expt. IT. 480 C.C. of sulphurous acid gave 41 C.C. of Wackenroder Experiments I and I1 show that occasional interruptions of solution of sp. gr. 1.265. solution of sp. gr. 1.246. solution of sp. gr. 1.268 solution of sp. gr. 1.267 WACKENRODER’S SOLUTION. 313 from one to two days’ duration in the passage of the sulphuretted hydrogen and longer treatment with this gas yield the largest quantity of acid.Expts. I1 and 111 indicate that it is of advantage to use a weak solution of sulphurous acid. Expt. IV shows that if sulphuretted hydrogen be passed through a solution of sulphurous acid uninterruptedly until it is completely decomposed absolutely and relatively the smallest quantity of acid will be produced. The increase in the quantity of the hydric pentathionate which takes place when a solution of sulphurous acid which is only partially decomposed by sulphuretted hydrogen is kept a few days appears to be due to a condensation of thiosulphuric acid S202 according to the equa-tion-5s202 + 2HzO = 2E2S50,. As the quantity of hydric tetrathionate seems to remain unchanged, and not to be dependent on this condition it is probably formed by the direct union of the reacting bodies-3502 + HzS = H,S,Os.If this theory be correct then pentathionates ought to be formed generally by the action of sulphurous acid on sulphur in stutu nascendi. The results of the following experiments support this conclusion. Action of Sulphurous Acid on Potnssic Thiosulphate. Five grams of potassic thiosulphate 2K2S20,,3H20 were dissolved in 100 C.C. of a concentrated solution of sulphurous acid. The intensely yellow solution could be kept without separation of sulphur or any other apparent change. Hydric chloride caused decolorisation and precipitation of liquid sulphur which in the course of a few days became solid and opaque. A portion mixed with two or three volumes of alcohol gave a crystad-line precipitate which was soluble in water with the exception of some globules of sulphur.The a8queous solution produced on addition of baric chloride R crystalline precipitate which was only partially soluble in boiling water. The dissolved portion was baric thiosulphate the insoluble baric sulphate and sulphite. Other substances were not observed. From these experiments i t appears that potassic thiosulphate is decom-posed by sulphurous acid into potassic sulphite and thiosulphuric acid which remains unchanged in the large excess of sulphurous acid present (p. 339). I n another experiment 5 grams of potassic thiosnlphate were dis-solved in only 5 c . ~ . of sulphurous acid. The yellow solution deco-2 A 344 DEBUS CHEMICAL INVESTIGATIQN OF lorised in the course of three days the smell of sulphurous acid disappeared and sulphur was precipitated.A few C.C. of sulphurous acid were again added when the same effects fojlowed the mixture turned yellow and smelt of sulphurous acid but lost both colour and odour with precipitation of sulphur in the course of a day or two. The addition of small quantities of sulphurous acid was continued until it ceased to produce coloration and its odour permanent. Alto-gether 18 C.C. of sulphurous acid were used and 0.153 gram of sulphur was precipitated. Sulphurous acid added in small quantities to potassic thiosulphate therefore does not act like a large excess. Absolute alcohol added to the decomposed solution of potassic thio-sulphate precipitated potassic trithionate and in the filtrate from the latter ?)otassic penfathionate was discovered by means of ammonia-silver nitrate.According to the text-books potassic thiosulphate and sulphurous acid produce potassic trithionate and sulphur as repre-sented by the equation-2KZS203 + 3S0 = 2K2S.306 + S, which would require the precipitation of 0.368 gram of sulphur from 5 grams of potassic thiosulphate. Experiment gave only 0.153 gram, not half t'he calculated quantity. The missing siilphur is in the form of potussic tetrcrthionate and yentathionate in the solution. The sulphurous acid decomposes a por-tion of the potassic thiosulphate into potassic sulphite and thiosulphuric acid which by condensation is transformed into pentatliionic acid.The latter and the potassium salts produce potassic pentathionate and sulphurous acid or thiosnlphuric acid which when very liltle sulphurous acid is present will partially decompose into sulphur and s ulphnrous acid. Potassic sulphite and potassic pentathionate form potassic thiosul-phate and potassic trithionate. The final products of the action of sulphurous acid on potassic thiosulphate are potasssic trithionate as chief product potassic tetra-thionate and pentathionate and sulphur. The reactions may be 1-epresented by the equation-6K2S,03 + 9x0 = K2S5O + K2Sa0 + 4K,S,O,. I n reality less potassic pentathionate and Cetrathionate and more potassic trithionate are produced on account of the precipitation of sulphur in quantities varying in different experiments.In confirmation of the explanations given here of the action of sulphurous acid on potassic thiosulphate I found that potassic penta-thionate and sulphurous acid produce similar results viz. potassic tetrathionate trithionate and sulphur. A third experiment gav WACKENRODER'S SOLUTION. 345 results similar to the second. A fourth experiment was made with a view of separating the potassic tet'rathionate and pentathionate from the trithionate and obtaining each salt in a pure form. 55 grams of potassic thiosulphate were treated with sulphurous acid until the whole quantity was converted into polythionates. Alcohol precipitated potassic trithionate the filtrate on standing deposited crystals of pure potassic tetrathionate but gave by spon-taneous evaporat,ion crystals of all three salts interlaced in such a way that they could not be separated mechanically ; an aqueous solution of the mixed salts however comported it,self with the reagents like one of a pentathionate.The precipitate of sulphur amounted to 4.86 per cent. Chloride of Sulphur and Xu.$hurous Acid. The view expressed on page 343 on the formation of pentathionates is also confirmed by the experiments of Plessy (p. SSO) and Fordos and GBlis (p. 280). The salts prepared by these chemists were how-ever not pure and their analytical methods unsatisfactory. I haw therefore repeated their experiments. Sulphurous chloride SZCl2 and water decompose into hydric thio-sulphate sulphur and hydric chloride-2S,CI + 3H,O = H,Sz03 + 4HC1 + s,.The hydric thiosulphate HzSz03 however soon splits up into water, sulphur and sulphurous acid. Gmelin (G?ne.h-f<ruzbt 1 Abth. 11, 401) quotes a statement of Carius according to which sulphurous chloride and water produce hydric chloride sulphurous acid and sulphuretted hydrogen -S,Cl + 2H,O = 2HC1 + SO + EzS. The sulphuretted hydrogen and the sulphurous acid would form the constituents of Wackenroder's solution. This view of Carius ( A n n a h 107 333 et seq.) of the decomposition of sulphurous chloride by water is entirely hypotheticaz not supported by experi-ments and has been advanced by him as an argument in favour of his view of the chemical constitution of the chlorides of sulphur. Sulphurous chloride dissolves in an aqueous solution of sulphurous acid without precipitation of sulphur but the smallest quautity of sulphuretted hydrogen produces even with a very large excebs of sulphurous acid an ilnmed iute precipitate of sulphur.The formation of hydric sulphide required by the equation of Carins does not therefore occur. Accordingly I adopt the first explanation of t'ho clecornposition of sulphurous chloride by water 346 DEBUS CHEXICAL INVESTIGATION O F 30 grams of sulphurous chloride were introduced by degrees into 480 C.C. of a concentrated aqueous solution .of sulphurous acid. The chloride of sulphur after repeated shaking dissolved witlzozlt precipitation of sulphur but with an increase of temperature from 18" to about 50". A very small precipitate of sulphur separated after the lapse of two or three days.The mixture was kept for a week and then concentrated on the water-bath until all the sulphurous acid was gone. To remove the larger portion of hydric chloride lead carbonate was now added and the filtrate from the lead chloride freed from lead in solution by the careful addition of hydric sulphate. The filtrate of the lead sulphate was concentrated to the sp. gr. 1.285. At this state of concentration it, measinred 26.5 C.C. A qualitative examination of the liquid revealed the presence of hydric pentathionate and a trace of trit,liionste. A strong solution of potassic acetate was added and the mixture allowed to evaporate in a current of ordinary air. A crystalline cake which formed in the course of the two following days was freed from adhering mother-liquor by pressure between folds of filtering-paper ; 11.5 grams of solid matter so obtained dissolved in 15 C.C.of water and 0.3 C.C. of hydric sulphate and left only a few milligrams of siilphur as residue. The filtered solution on spontaneous evaporation yielded 7.2 grams of crystals too small f o r mechanical separation. They were therefore redissolved in another similar quantity of acidulated water and the solution left to concentrate a t ordinary temperatures. This time a crop of fine large crystals of potassic pentathionate and tetrathionate were obtained. Both descriptions of crystals could easily be sepa-rated. Analysis of the Pe&athionic Crystals. 0.52 gram dried over hydric sulphate.left after ignition 0,252 gram of potassic sulphate.I n 100 parts Found. Theory. Potassium 21.72 21.60 The substance gave the reactions of a pure pentathionate. Analysis of Potassic Tetrathionate. 0.6934 gram dried over hydric sulphate gave after ignition 0.396 gram of potassic sulphate. In 100 parts Found. Theory. Potassium. . 25-61 25.82 The reactions likewise agreed with those of a tetrathionate WACKESRODER'S SOLUTION. 347 The polythionic acids have been formed in this experiment by the action of sulphurous acid on one of the products of decomposition of hulphurous chloride and water viz. hydric thiosulphate and I believe whenever nascent sulphur and sulphurous acid meet under favourable conditions polythionic acids will be formed. If so then hydric pentathionate ought to result from the decomposition of hydric thiosulphate H2S303 in water.25 grams of baric thiosulpha0e were digested with 9.1 grams of hydric sulphate diluted with five times its weight of water. The filtrate froni the baric sulphate after concentration on the water-bath, gave a liquid which comported itself with potassic hydroxide am-monia-silver nitrate and mercurous nitrate respectively like a solu-tion of hydric pentathionate. But a considerable portion of the hydric thiosulphate had decomposed into water sulphur and snl-phurous acid. Will ordinary sulphur produce polythionic acids with sulphurous acid ? A quantity of flowers of sulphur was washed for a long time first with cold afterwards with boiling water until the wash-water did not change blue litmus paper. Some of the washed sulphur was placed on blue litmus paper and left on it for some time.The colour did not change. 10 grams of the washed and dried flowers of sulphur were sealed with 36 C.C. of concentrated sulphurous acid in a glass tube and a second tube charged with the same volume of acid mith-out sulphur. The two tubes remained for five days at common temperatures, and were then heated for several hours on a water-bath to 60-80". This treatment did not appear to have effected any change in either of the tubes. Both were now opened their contents transferred to evaporating dishes and warmed on water-baths until all the sul-phurous acid had volat,ilised. I observed on this occasion that the acid escaped from the dish containing sulphur a t a much slower rate than it did from the other.Both liquids were finally concentrated to one-fifth of their original volume. Examination of the Liquid left by the Pure Sulphurous Acid. The blue colour of litmus paper was changed to red ; baric chloride gave a white precipifat e insoluble in hydric chloride and mercurous nitrate a white prec Gitate of mercurous sulphate. Addition of ammonia-silver nitrate produced no change and cupric sulphate gave no reaction a t 100". But silver nitrate caused a very slight floccu-lent precipitate of a very pale brownish colour. Hence hydric sul-phate is present and polythionic acids are absent 348 DEBUS CHEMICAL INVESTIGATION OF Examination of the Liquid left by Sulphurous Acid and Sulphur. Baric chloride indicated the presence of hydric sulphate and mer-curous nitrate gave a precipitate of mercurous sulphate which was coloured slightly yellow.Ammonia-silver nitrate produced a very sZight brownish coloration and a few brown gelatinous flakes made their appearance after some time. Silver nitrate caused a very small brown precipitate. From these reactions it seems to follow that sulphurous acid and flowers of sulphur form under the conditions described an infiiiitesimal quantity of hydric pentathionate. This result is however of a very doubtful nat'ure. Only one reaction the one with the silver solution, can be advanced in its favour and as the number of substances which reduce silver solutions is very great no certain conclusion can be drawn from the experiment. Commercial flowers of sulphur is a very impure substance.It contains sulphates of various descrip-tions hydric calcic aluminic and iron sulphates were found in the wash-water. The latter gave with silver nitrate a precipitate which gradually became black. Some of the wash-water was first concen-trated on the water-bath and then evaporated to dryness on a piece of platinum foil. It left a considerable residue which a t a higher temperature evolved hydric sulphate and a t a red heat assumed :L transient black colour as if an organic substance were present. On the whole the experiment with flowers of sulphur and sulphurous acid is of a negative nature and we are only ceytain that nasceut sulphur with water and sulphurous acid produces polythionic acids. Explanation of the Formaiion of the Comtituents of Wackenroder's Solution.We are now able to explain the formation of the constituents of Wackenroder's solution from the original materials sulphuretted hydrogen sulphurous acid and water. Hydric sulphide and sul-phurous acid in the presence of water react immediately with sepu-ration of sulphur (p. 336). J t appears t'hat hydric pen tathionate is not the direct product of' this react'ion (p. 338) a t all events the greater part of it is slowly formed when a solution of sulphurous acid only partially decomposed by sulphui etted hydrogen is kept for some days (p. 339). A current of sulphuretted hydrogen passed through 120 C.C. of sulphurous acid without interruption until all the acid is decomposed causes the formation of a small quantity of hydric pentathionate (p.342). If the current of hydric sulphide is stopped after the decomposition of about half of the sulphurous acid arid the liquid is now allowed t o reinain a t rest for two days aiic WACKENRODER’S SOLUTION. 349 Potassic tetrathionate. after the lapse of this time sulphuretted hydrogen is again passed until the operation is completed a larger quantity of hydric penta-thionate is produced. But the best yield of hydric pentathionate is obtained when the passage of the hydric sulphide is interrupted five or six times each time for from 36 to 48 hours during the course of the entire opera-tion (p. 281). The following table contains an outline of the experimental re-sults :-Pot assic pentathionate. Time required for the complete decompoei-tion of sulphurous acid by aulphurett ed hydrogen.6 6 6 I. 3 to 4 hours for 120 C.C. in one opera-tion 11. Sulphuretted hydrogen passed twice, each time 18 hours on separate daye. Q,uantity 120 C . C . 111. Sulphuyetted hydrogen passed 8 times, each time 2 hours on separate days. Quantity 480 C.C. 1 2 6 Ratio of the weights of the salts obtained. The quant.ity of tetrathionate appears to be proportionally t.he same in all experiments and quite independent of the time of preparation. From this I conclude that hydric tetrathionate is a direct prodiict of the reaction of sulphuretted hydrogen on sulphurous acid and is formed by combination as represented by the equation-3S0 + H,S = H,S,O,. If hjdric sulphide and sulphurous acid respectively had no action on hydric tetrathionate then the latter would be the sole product O F the reaction.But as both decompose the tetrathionate an unusual complexity of reactions is the result. As long a s the sulphurous acid is in great excess as in the begin-ning of the operation most of the sulphuretted hydrogen reacts with the sulphurous acid and we may at this stage disregard the reaction between the tetrathionate and snlphicle. The two substances hydric: sulphide and sulphurous acid meeting in squeons solution in the proportioris of the above equation and in their positions of reaction, combine and form hydric tetrathionate. But the hydric tetrathionate molecules and free sulphurous acid produce hydric trithionate arid thiosulphuric acid S20 (pp. 333 and 3%).This reaction liowever i 350 DEBUS CHEXICXL INVESTIGATION O F very slow and of a reciprocal nature. I n conseqnence it is only partial, and as thiosulphuric acid can transfer sulphur to hydric tetrathionate, and so cause the formation of hydric pentathionate the solution will now contain-Free sulphurous acid, Thiosulphuric acid, Hydric trithionate, Bydric tetrathionate. and Hydric pentathionate. If now sulphuretted hydrogen were passed in until all sulphurous acid had disappeared and if no other reactions took place then hydric tri- tetra- and penta-thionates would be the products. And for every molecule of hydric pentathionate a molecule of hydric trithionate would be present. This result is modified by the reaction we have so far disregarded viz.by the decomposition of the hydric tetrathionate by sulphuretted hydrogen into water and sulphur ; one part of t.he sulphur so set free combines in statu n a s c e d i with hydric trithionate to form hydric tetrathionate and with tetrathionate to form penta-thionate and with the latter t o form hexathionate. The quantitative relations are such that a t the moment when all the sulphurous acid has disappeared all the hydric trithionate has also been reconverted into tetrathionate. Another part of the sulphur produced by the action of hydric sulphide on hy dric tetrathionate remains in solution as colloidal sulphur-6-sulphur-and the remaining quantity falls down as a precipitate or remains in suspension. If then the three reactions-the formation of hydric tetrathionate and its decomposition by sulphuretted hydrogen and sulphurous acid, respectively-are taken into consideration we should have as final products of the action of sulphuretted hydrogen on an aqueous solution of sulphurous acid sulphur as a precipitate sulphur in suspension sulphur in solution and hydric tetra- penta- and hexa-thionates.This is the condition of the Wackenroder solution the preparation of which has been described on p. 340. Hydric tetrathionate is the chief product. But if the passage of the sulphuretted hydrogen through the solution of sulphurous acid is conducted with interruptions of several hours’ duration then the condensation of thiosulphuric acid into pentathionic acid with formation of hydric pentathionate (p. 281) takes place and the quantity of the pentathionate becomes in consequence five or six times greater than before.And i f sulphuretted hydrogen is passed through n Wackenroder solution after all the sulphurous acid has disappeared and until it ceases to act on the polythioni WACKENRODER'S SOLUTION. 351 acids present water and sulphur will be the final products of decom-position. The polythionic acids acre then intermediate products of t8he reaction of sulphuretted hydrogen with an aqueous solution of sulphurous acid, and the equation-SO2 + 2H2S = Ss + 2H20, given by the text-books is correct for the final products. C. On the Formulce of the Polytkionates. We will now attempt to represent the constitution of the polythio-nates by rational formulae derived from the chemical facts described in this and the papers of other authors.In some of the best of our text-books,* the formula-s3(so2oH)2, is given for hydric pentathionate and it is stated that baric penta-thionate is formed from baric thiosulphate and sulphuric chloride according to the equation-2 [SO { :>Ba] + SCI = BaS,O + BaCl,. These formulze we will trace to their original sources. Bloomstrand (Chenzie der Jetzzeit 158) appears to have been the first chemist who represented hydric pentathionate by the formula S3(S020H), and Mendel6eff (Ber. 3 870) after him adopted the same expression. The latter believes that several unknown compounds of sulphur and hydrogen can exist HzS3 H2S4 H2S5 all derived from sulphuretted hydrogen by replacing an atom of hydrogen by the residue HS.If now in the compounds of sulphur and hydrogen H2S H2S2 and HzS3, the two hydrogen-atoms are replaced by the radical of hydric sulphate, SO,,H the formulze of hydric tri- tetra- and penta-thionate are obtained , OH.S02*OH - S<S02*OH + 2H,0. { 4- O€€-SO,*OH - SO,*OH Hydric trithjonate. So2'oH + 2H20. OH-SO,.OH - ''{ 'J 4- OH*SO,.OH - S2<S0,*OH Hydric tetrathionate. * Kolbe H A Short Text-Book of Chemistry translated by Prof. Humpidge. Richter Lehrbzcch 1881 p. 222; Roscoe and Schorlemmer London 1884 p. 171. 1 p 354 352 DEBUS CHEJIICAL IXVESTIGATIOK OF Hydric pentathionate. MendelAeff shows that the hydrogen salts of the polythionic acids agree in several respects with the sulphonic acids and that his formuh indicate how to prepare the former in a rational manner As a a example he mentions that sulphurous cliloride and dipotassic sulphite ought to give potassic tetrathionate :-Mendeleeff has not as far as I know made this experiment or tested his theoretical conceptions in other ways.This work has beeii carried out by W. Spring ( B e r . 6 1108) who did not realise the last equation but obtained instead of potassic tetrathionate trithio-nate and some potassic thiosulphate. Sulphuric chloride and dipo-tassic sulphite gave likewise potassic trithionate and also potassic chloride. The equation-SCl2 + 2KS03K = 2KC1 + S(S03K),, is given in explanation of the reaction. But Spring did not use sulphuric chloride and dipotassic sulphite only he also had water present. And if the water is taken into con-sideration then a very different explanation may be given of his results.Sulphuric chloride SCI2 and water produce sulphurous acid hydric chloride and sulphur. Hydric chloride decomposes dipotassic sulphite into potassic chloride water and sulphurous acid. If the reacting substances are taken in quantities as required by the equa-tion half the dipotassic sulphi te remains undecornposed. Dipotassic: sulphite and sulphur form potassic thiosulphate. The latter and sulphurous acid produce as is well known potassic trithionate and as has been shown in this paper some potassic tetra-thionnte and pentathionate. Consequently the results of Spring’s experiments can be explained by well-known facts and as they can be explained in more than one way it follows that his experiments cannot throw any light on the coiistitution of the polythionates, and the same remarks may be made with regard to the experiment with baric thiosulphate.Spring mixed this salt with some water and then added sulphurous chloride S,Cl2. After precipitation of the dissolved barium by an excess of hydric siilphstte and the excess of hydric snlphate by baryta- water h WACKENRODER’S SOLUTION. 353 obtained a liquid which gave “ all the reactions of pentathionic acid.” Therefore the formula of this acid is-The experiment teaches nothing about the constitution of penta-thionic acid. Sulphurous chloride and water alone without the assistance of baric thiosulphate will furnish a liquid exhibiting the reactions of hydric pentathionate or baric thiosulphate and dilute hydric sulphate without sulphurous chloride will do the same.SO H The formula S,< so:a is therefore a purely hypothetical concep-tion and it is to be regretted that on the evidence described it has been admitted in books intended f o r beginners. The metallic salts of sulphurous acid are according to Strecker’s reaction (Annalen 148 90-119) constituted as follows :-Ag*S 0,. O*Ag, viz. one atom of metal silver in this case is directly combined with sulphur. Bunte’s (Ber. 7 (1874) 646) experiments confirm Odling’s (Chem. Xoc. J. 22 255) formula for the thiosulphates. Sodic ethylic thiosulphate and hydric chloride produce mercaptan sodic chloride, and hydric sulphate-C,H,-S.S02-OKa + H,O + HC1 = C,H,SH + NaCl + H2SOa, hence the ethyl of the thiosulphate is in direct combination with sulphur.The behaviour of the thiosulphate with mercuric chloride wyrees with this conclusion. The salts of potassium have a similar constitution hence-Dipotassic sulphi te K*SO,*OK, Potassic thiosulphate K.S*SO,OK. Dipotassic sulphite combines directly with sulphur t,o produce the thiosulphate. This sulphur therefore joins the group KSO of clipotassic sulphite. On the other hand some thiosulphates for example the calcium salt easily lose sulphur and become sulphite. Hence this second atom of sulphur of thiosulphates is held by a feeble force only. Potassic thiosulphate and iodine produce potassic tetrathionate and patassic iodide. Three formulae are probable for the tetrathionate : 354 DEBUS CHEMICAL INVESTIGATION OF Potassic tetrathionate can lose one atom of sulphur and become tri-thionate ; hence we have one of the three following f o r m u h for the last-named salt :-KS O,*O K*S 0,O KO.SO,S I VI.I ' SO *OK IV. s<s*;.oK; V. KS - S 0,- 0 Now potassic trithionate can combine with sulphur in statu nascendi as dipotassic sulphite does. The power to take up sulphurbelongs in the case of the last-named salt to the atomic group KSO (p. 353) and we shall be justified in attributing in the case of the trithionate the same property t o the same cause viz. t o assume in the trithionate the presence of the group KSO,. This assumption is also supported by the fact that potassic trithionate is a derivative of potassic hydric sulphite and sulphur.Hence the formula 1V must be eliminated because it .does not con-tain the atomic group KSO, and there remain the formulE V and V I for the trithionate. Our choice is guided by the following considerations :-Two of the sulphur-atoms of the potassic pentathionate occupy positions in the molecule essentially different from those of the other three. These two atoms of sulphur can successively or together be removed, and the residue of the molecule can exist by itself or can reunite with sulphur and reproduce pentathionate. The trithionate behaves with regard t o sulphur like an element. Bnt if an atom of sulphur is removed from potassic trithionate then the residue K2S,06 decomposes at the same time into potassic sulphate and sulphurous acid and from these materials the original salts (K,S,Os K2S5O6) cannot be obtained by direct combination.Froni this it follows that one of the three sulphur atoms of potassic tri-thionate holds the proximate constituents of the salt in chemical combination viz. the existence of the salt as a polythionate is de-pendent on this sulphur-atom. This condition is satisfied by for-mula. VI but not by formula V. We support this conclusion by the following experiments and considerations :-If potassic pentathionate had the constitution-S,(SO,.OK), WACKENRODER’S SOLUTION. 355 bromine-water would decompose the salt according to the equation-S,SO,.OK + Br2 + 2H20 = S3 + 2KBr + 2H2S04. I. 1.4089 grams of potassic pentathionate were dissolved in water, and mixed by degrees with bromine water containing 0.684 gram or 1 mol.of bromine. Every drop of bromine-water caused turbidity, which disappeared again on stirring the mixture with a glass rod. But i t remained thick after a certain quantity of bromine had been added. A precipitate of sulphur fell down. This was of a soft, plastic nature and was collected on a weighed filter. Its weight was found to be = 0.075 gram but on account of its soft nature it could not be powdered in a mortar and could not be entirely freed from potassium salts by washing. Heated on platinum foil i t left some residue. The filtrate from the sulphur precipitate contained much potassic pentathionate and hydric or potassic sulphate. It was slightly opalescent and on standing deposited a thin membrane of sulphur on the side of the beaker.Probably some of the sulphur separated by bromine had combined with undecomposed pentathionate to form hexa-thionate and the spontaneous decomposition of the latter caused the deposition of the sulphur membrane. Sodic chloride caused no pre-cipitate in the filtrate. 11. 0.561 gram potassic pentathionate was mixed in aqueous solu-tion by degrees with 0.497 gram of bromine (2 mols.). The sulphur precipitate weighed after washing with diluted ammonia and drying over hydric sulphate 0.0635 gram. The filtrate contained besides undecomposed thionate sulphates. 111. 1.0965 grams of potassic pentathionate were mixed in aqueous solution with 1,948 gram of bromine (4 mols.). The precipitated sulphur was a t first soft but soon became hard and brittle.It was powdered in an agate mortar washed with dilute ammonia and dried over hydric sulphate. The .filtrate was n o longer acted o n by bromine-watay. All potassic pentathionate had been decomposed. Baric chloride added to the filtrate gave a precipitate of baric sul-phate weighing 2.034 grams. Hence 1.0965 gram of potassic penta-thionate gave with bromine-water 0.206 gram of sulphur as a precipi-tate and 0.279 gram in the form of baric sulphate. Its weight was 0.806 gram. In 100 parts-Found. Theory. Sulphur . . . . . . 44.31 44.32 Therefore 4 mols. of bromine had precipitated from 1 mol. of potassic pentathionate 2.13 atoms of sulphur and oxidised to sulphuric acid 2.87 atoms 3 5 6 CHEMICAL INVESTIGATION OF WXCKENRODER'S SOLUTION. 1 mol of I. One rnol. of potassic pentathionate } + { bro;ine 1 gave 0.6 atom of sulpliur. KzS506 . . . . . . . . 11. Ditto + 2 mols. , 1.27 7 , 111. Ditto f 4 mols. , 2.13 7 7 The sulphur in I and 11 on account of its physical properties, coiild not be obtained quite pure by washing ; hence it has been found too high. From these experiments I conclude that the decomposition of potassic pentathionate by bromine-water takes place according t o the equation-2&S506,3H20 + 8Br2 + 9H20 = 4KBr + 4 s + GH,SO + 12HBr, and that if less bromine be taken than is required by this equation a proportionate quantity of pentathionate remains undecomposed. Two atoms of the sulphur of a molecule of potassic pentathionate, K2S506 are precipitated as such and three are oxidised to sulphuric acid. The conclusion is that the tlhree oxidisable atoms of sulphur are alreacly in the molecule of pentathionate in combination with oxygen, :ind are so in the trithionate resulting from the decomposition of the p3ntathionate. As the formula V does not fulfil these condi-tions we must eliminate it and we have then only one foi*rnula VI, left for potassic trithionate and this formula agrees with the proper-ties of the salt. We find then the following formulae for the potassic polythionates :-K- S O,-O KO-SO,*S 1 Potassic trithionate. KS.SO2.O I Potassic tetrathionate. KO.SO2.S K Sz.S 0,O KO.SO,*S KS,*SO,*O KO*SO,*S I Potassic pentathionate. I Potassic hexathionate. According t o these formulae potassic trithionate contains the group K*S02 in which the potassium is in direct combination with the sulphur. Potassic sulphide K,S can combine with two three or more atoms of sulphur and this propertcy of potassic sulphide is not. lost i ON THE DENSITY OF CERIUN SULPHATE SOLUTIONS. 357 the combination K-SO,. The hydrogen salt of tetrathionic acid contains according to this theory the radicals HO and HS and that of pentathionic acid the radicals HO and HS, and hydric hexathio-nate HO and HS,. The hydrogen of these radicals is replaceable by metals. HS also occurs' in persulphide of hydrogen and like this compound potassic pentathionate is immediately decomposed by alkalis and rendered more sta3blc by acids. Water also causes both snbstances to decompose in the same manner. Moist persulphide of hydrogen produces sulphuretted hydrogen and sulphur a solution of potassic pentathionate potassic tetrathionate and sulphur. Groups of the same constitution as HS and KS confer similar properties on the compounds in which they occur. Royal Naval College Greenwich, December 1887

ISSN:0368-1645    

DOI:10.1039/CT8885300278

出版商:RSC    

年代:1888

数据来源: RSC

摘要:

ON THE DENSITY OF CERIUN SULPHATE SOLUTIONS. 357 XXVL-Note on the Deizsity of Cerium Sdphate Solutions. By €3. BRAUNER Ph.D. F.C.S. late Fellow of Owens College. (Communication from the Laboratory of the Bohemian University, Prague.) SINCE the publication of MendelBeff’s paper on the Density of Salt Solutions (Russ. Chem. SOC. Jourgz. 1884 184 in which this eminent chemist shows that the density of solutions regularly increases with the molecular weight of the salts dissolved) and especially since the publication of the same author’s important work on Solutions,* the interest of chemists has been more than ever directed t o this subject ; every new exact determination therefore may be regarded as useful material for a further study of this important subject. In the case of the rare earth metals not a single solution has as yet been studied from this point of view partly on account of the rarity * A.fi1eHde.IkB.b. 13 3C~X%~OBa€lie BOdHbIX% paCTBOp0B.b IIO yJ%dh-Holly B$c~. C.-Tl[eTep6ypra 1887 (D. Mendelkeff. “ Research on Aqueous Solutions with regard to their Density,” St. Peteraburg 188’7 21 and 520 pages large SYO.). I n this important work which on account of its theoretical and practical value ought to be translated into a Western-European language the whole of the material relating to the density of aqueoue solutions is collected and unalysed with an originality peculiar to the great Russian chemist. YOL. LIII. 21 358 BRAUNER ON THE DENSITY OF of the material partly because only a very few of the rare earths can be regarded as homogeneous bodies.For the present investigation cerium (cerous) sulphate was used, which served me for the determination of the atomic weight of cerium (Trans. 1885 879) ; cerium sulphate as regards its solubility in water exhibits two peculiarities by which it is distinguished from the majority of salts. It is more soluble in cold than in warm water, and the anhydrous salt is not only more soluble but far more easily soluble in water than the hydrated salt. Many chemists assume that each of these salts is dissolved in water as such and that the solubility a t a higher temperature decreases, because on heating the cold saturated solution of the anhydride, hydrates of the salt which cannot exist in solution a t that high temperature are formed and deposited.The question whether a solution of an anhydrous salt is identical with that of the hydrated salt has been discussed of late especially by English chemists and therefore in the present case I tried to deter-mine whether there was any difference observable between solutions of the anhydrous and hydrated cerium sulphates of equal concentra-tion. The following experiments show the unequal solubilities of the anhydyous and the hydrated salts. If anhydrous cerium sulphate is added to water a t 0-3" little by little with continuous stirring it dissolves quickly and completely until 60 parts of anhydrous sulphate have been used for 100 parts of water. If more of the salt is added it is not only converted into crystals of the hydrate but crystals of the hydrate are also gradually deposited from the solution this being accompanied by development of heat.When the temperature of the liquid (and salt) has risen to 15" it becomes converted into a kind of crystalline paste. On stirring this for some time a t 15" until no further separation of crystals takes place and then separating the liquid from the solid portions a solution is obtained containing 27.88 parts of the anhydrous sulphate to 100 parts of water. If 31.62 parts of the anhydride be dissolved in 100 parts of water a t 0-3" no salt separates out from the solution on raising its tem-perature to 15". This is however the maximum of concentration of a solution whose density can be determined in the usual way for after standing for some time a t 15" crystals of a hydrate begin to separate out in the picnometer.When the solution has been standing for some days exposed to the air a t 15-18' in an open vessel so that spontaneous evaporation occurs a great part of the salt crystallises out and a solution remains containing 17.69 parts of the anhydride to 100 parts of water CERIUM STJLPHATE SOLUTIONS. 359 How difficult it is to attain the final point of saturation without starting with a supersaturated solution may be seen from the following. Anhydrous snlphate 14.56 parts was dissolved in 100 parts water at 3". After standing for a few days exposed t o the air numerous crystals of a hydrate separated but the saturated solution con-tained only 15-59 parts of anhydride to 100 of water. Crystals of the hydrate Ce,(SO& + 8H20 were stirred from time to time with water at 15" during two days in such proportion that a great part of the salt remained undissolved ; in this case only 17.52 parts (anhydrous salt) were dissolved by 100 water.On one occasion a solution of 19.80 parts of the anhydride in 100 water was obtained on concentration by spontaneous evaporation but on trying t o obtain such a saturated solution of the hydrate once more in the same way solutions were obtained containing after two days 11.66 parts and after five days only 12.24 parts in 100 water. From this it will be seen that on saturating water with cerium sulphate at the mean temperature of 15-18" solutions may be obtained containing from 12-24! to 31-62 parts of salt in 100 water ; it is however difficult t o determine the point at which " saturation " ceases and " supersaturation " begins.For the determination of the density of the solutions two Thorpe picnometers of 18.9 C.C. (a) and 22.5 C.C. ( b ) capacity were used. In the middle of the narrow neck two fine lines 1 mm. distant were engraved and the volume of each of these intervals was determined by putting into the vessel full of water a drop of mercury of a known weight (MendeGeff). This volume was found to be for a 0.0054 and for b 0.0042 C.C. As one-tenth of that interval can be measured by optical means the corresponding sp. gr. can be estimated to within about 0.00002. The temperature was determined by means of a normal Geissler thermometer showing distinctly O*0lo the zero point of which was corrected several times duying the investigaticn.All determinations were made at 15" ; and in order to keep this temperature constant for a sufficient length of time in the glass vessel (with flat sides) containing about 4 litres of water into which the picnometers were plunged the temperature of the surrounding air was kept artificially at 15-5-15.6". The weights used were carefully corrected and the weight of the liquids and vessels reduced to a vacuum. By using the method of vibrations the error does not exceed 0.1 mgrm. which makes the error 0.00001 in the density. For calculation of the sp. gr. 0.999159 was taken as the mean density of water at 15" water at 4" = 1. The air was pumped out of the solutions before weighing, but this could not be carried too far in the case of the more con-centrated solutions.2 3 360 BRAUNER ON THE DENSITY OF Calculated. After each determination the contents of the picnometer was transferred to a weighed platinum crucible and this was weighed in a thin glass weighing bottle so as to prevent any loss which might be caused by evaporation. The solution was then carefully evaporated on the water-bath and the anhydrous salt obtained by heating the crucible at 440" in the sulphur-bath described in the paper quoted above. The experimental error caused by inexact determination of the amount of salt in solution has the greatest influence on the final result for a difference of +0*005 part of salt i n 100 parts of water makes as much as +0.00005 in the density. The first series of experiments was made with solutions of the anhydrous sulphate the second series with solutions of the hydrated salt of nearly equal concentration; these were prepared afresh for each experiment by synthesis.The first column of the tables A and B below shows the quantity of anhydrous salt contained in solution €or 100 parts of water present (not the percentage) the second the Difference. A. Solutions of the Anhydrous Sulphate Ce2(S04), at 15'14". 1'03006 1 y' -0'00001 5 __ 100' 21.19 _ _ _ _ ~ -31-62 Density found. 149.1 99.9 Density mean. 1 -19649 - 0 '00009 1 -030026 1 '030071 1 * 03005 3z 0 -00002 1 -058082 1 *058151 1 -080026 1 '079983 -__-1 '05812 -+ 0 -00004 1 -08000 f 0 * 00002 --1.05795 1 +0-00017 -I-1'08003 1 -0*00003 1 -090810 1 090880 1 -09085 f 0 *00004 1 -09939 f O -00003 - ~ -1.09077 1 +0*00008 328 -7 299 * 5 -249 -5 ---1 '09952 - 0 *00013 I -___-1.11905 1 +0-00012 ~ 1.099418 1 *099362 1.119153 1 *119169 1 - 119171 1 -119196 1 '1191t f O ~00002 12 -66 1 -136646 1 -13665 1.13651 ~ +0*00004 I -- " X I " V 1 -146212 1 -146247 1 - 14623 zk 0 *00002 1 *196426 1 *196367 1 '28'777 -1 -19640 &0*00003 1 -28'778 1'28788 1 -0'0001 CERIUM SULPHATE SOLUTIONS.36 1 number of molecules of HzO holding 1 mol. of the respective salts (anhydrous and hydrated) in solution the third the density found, the fourth the mean numbers the fifth the numbers calculated by the interpolation formulse given below the sixth the differences between the numbers calculated and found.B. Solutions of the Hydrated Xulphate Ce2(S0& + 8HZO. ~ ~~~~ Calculated. 1 * 03015 -1 *0599 1 1 '07902 ----1 '08029 -1 *09936 --1 * 09960 -1 * 10981 --1 * 11521 1 *13605 1 -Y' X -100' Density found. Density mean. Difference. 3 -18 -6.31 -x *35 994 -2 1 *030060 1 '030068 1 * 030075 1 *030106 1 *03008 ~0~00002 - 0.00007 1 -059561 1 -059957 1.05956 -f 0 - 00000 + 0 *00005 500 -3 378 *4 -372 -3 299 *9 --+ 0 -00008 1 '0'79062 1 -0'79130 1 -07910 & 0 '00003 8-48 -10 -53 -10 -56 -11 a 66 1 .Of30337 1 * 050282 1 -08031 f 0 -00003 + 0 -00002 1 -099292 1 '099273 1 '09928 ,J 0 '00001 1 -099606 1.099564 1 -09959 f 0 * 00002 - 0 *00001 1 -109857 1 a 109883 1 '10587 f 0 '00001 + 0 '00006 1 -115294 1 *115300 1 *136180 --+ 0 -00009 1-11530 f 0 ~00000 1 * 13618 12 -24 14 -52 -+ 0 WO13 In order to see whether the densities of the solutions of the anhy-drous salt are identical with those of the hydrate of equal concentra-tion the densities for equal concentration had to be calculated.Dr. A. Seydler Professor of Natural Philosophy in our University has kindly calculated by a complicated formula involving the use of the method of least squares the equations for parabolas showing the dependence of the density on the concentration in both series of experiments but as the equations were calculated only from the data obtained by me without regard t o the fact that water at 15" has a density of 0.99916 the corresponding values in the equations had fo be extrapolated which makes them somewhat uncertain (0.99966 an 362 0.99964 instead of 0,99916) Other methods of calculation however gave no better results.The equations are ( d = density at 15" x = salt for 100 parts water) : (A,) For the anhydride d = 0.999665 + 0*00964010 - 0-0000166~~. (B.) For the hydrate d = 0.999636 + 0.0096646~ - 0*00001839~~. The values calculated by the aid of these formulze for 2 to 14 parts of salt in 100 water (14 being the maximum of concentration of the solution of the hydrate) are given in the following table :-BRAUNER ON THE DENSITY OF D emit y of anhydride solution. ~--0.99967 -~__--X -100' Density of hydrate solution.0 * 99964 0 1 *03796 1 *05691 1.07572 1 * 09441 1 -11296 1 *13137 ~---~-----___-___ 2 4 -1 * 03800 1 '05696 1 '07578 1 *09444 1 -11296 1.13134 -- G 8 -Difference. - 0.00003 + 0 *00001 + 0.00004 + 0 * 00005 + 0 *00006 + 0 *00003 0 ~00000 -0 *00003 From a comparison of both series it follows-1. That the densities of solutions of anhydrous cerium sulphate are identicaZ with the densities of the solutions of the hydrated salt. 2. That the differences in both series fall entirely within the un-avoidable experimental errors for the differences never exceed those between the numbers found and calculated as is seen from Tables A and B. Finally it should be mentioned that if solutions of the hydrate and those of the anhydride of equal concentration be evaporated in vessels of equal size and material on the same water-bath those of the anhydride will show an inclination to deposit monoclinic prisms of the salt Ce2(S04) + 5H20 whereas solutions of the hydrate + 8H20, are more inclined to deposit rhombic octahedrons of the salt, Ce2(SOa)s + 8H20.This difference in behaviour of the two solutions holds good only for those concentrations in which the salt begins to be deposited not on merely heating the solutions but only after some water had evaporated. I cannot say definitely whether this may no CERIUM SULPHATE SOLUTIONS. 363 be due partly to chance; that it is reaJly the case however is seen from the following analyses :-(a.) EvaToration of a Solution of the Anhydrous Salt. The salt Ce2(S0& + 5Hz0 is stable at 100". Weight of salt-(a.) Directly after evaporation at 200". . After drying at 100" f o r 5 hours After drying at 100" for 10 hours . After drying at 100" for 15 hours . Weight of anhydrous salt (440") . (p.) Salt at 100" Salt at 440". . (y.) Salt at 100" . . . . . . . . . . . . Grams. 1.4677 1.4474 1.4458 1.4445 1.2547 1.1828 1.0204 1.2244 1.0577 Water in Calculated for per cent. Ce2(X04)3 + 5H2O. 14-51 13.66 13-31 13.19 13.14 13.72 13.62 (b.) Evaporation of a Sohtion of the Hydrated Salt. The salt Ce2(S04)3 + 8H,O loses 4 mols. H20 at 100". Water in Grams. per cent. Hydrate. Requires. Weight of salt-(%.) After evaporation at 100" 1,4975 19.92 8H20 20.21 100" . 1.3479 11.03 4H,O 11.24 ( / 3 . ) Salt at 100". . 1.3093 11.11 4H20 11.24 Aft,er drying 2 hours at Anhydrous at 440". . 1.1992 Salt at 440". . 1.163

ISSN:0368-1645    

DOI:10.1039/CT8885300357

出版商:RSC    

年代:1888

数据来源: RSC

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XXVI1.-A Gasometric Method of Detewiining AGtrous Acid. By PERCY F. FRANKT~AND Ph.D. B.Sc. F.I.C. Assoc. Royal School of Mines. IN the course of some experiments which 1 have been carrying on fol* some time past it became necessary to determine the proportion of nitrous acid present in certain solutions containing both nitrates, nitrites and ammonia the problem being still further complicated by the presence of organic matter. The estimation of nitrous acid in such mixtures is usually effected colorimetrically by the well-known reactions of metaphenylenediamine or of sulphanilic acid and naphthylamine hydrochloride on an acidulated solution of the nitrite the latter reaction being very much more delicate than the former. Both of these colorimetric methods are however only adapted for measuring very minute traces of nitrous acid and werv quite unsuitable for my purpose.I may however mention in pnss-ing that I have found the modificat,ion of the sulphanilic acid method introduced by Zambelli (Abstr. 1887 533) very much to be pre-ferred to either of the above well-known methods. Zarnbelli adds to the solution containing the nitrite a drop of a saturated solution of sulphanilic acid then a drop of an aqueous solution of phenol thc mixture being then rendered alkaline with ammonia ; the presence of nitrous acid is indicated by the appearance of a coloration varying from faint yellow to intense reddish-yellow (like the colour oE a strong solution of potassium dichromate) according to the quantity of the nitrous acid present.The author states that this method is capable of indicating the presence of 1 part of nitrous nitrogen in 40,000,000 parts of water. So that whilst its delicacy is extreme i t has also the advantage that the reagents employed are permanent in solution ; the solutions of naphthylamine hydrochloride and more especially of metaphenylenediamine becoming very rapidly dis-coloured on keeping. I therefore invariably adopt this method for qualitatively testing for nitrites as well as for obhining a relative estimate of the amount present in different solutions. For the purposes of the experiments upon which I was engaged, however it was necessary to have a method which should be capable of dealing with much larger quantities of nitrous acid than are suit-able for colorimetric estimation.Owing to the presence of organic matter in the solutions in question the ordinary method of deter-mining nitrous acid by means of a standard solution of potassium permanganate was out of the question and on this account a gaso A GASOMETRIC METHOD OF DETERMINING NITROUS ACID. 36 metric method appeared to be the most suitable for the purpose, especially as only very small absolute quantities of the nitrite were available. Under these circumstances the reaction bet ween nitrous acid and urea naturally suggests itself as especially suitable since the volume of nitrogen gas evolved is double that of the nitrogen in the nitrite and the errors of experiment thus become divided by two. I have since found that this reaction had been utiliskd for thc purpose of nitrous acid estimation by Longi (Guzzetta 13 469-479) although his mode of operation is quite different from mine, and would not have been adapted to the determination of the small quantities of nitrous acid which I had at my disposal.My preliminary experiments were made with a solution of sodium nitrite standardised by means of potassium permanganate. (1.) 20 C . C . of the standard solution of sodium nitrite are evaporated to dryness in a small beaker on the water-bath to the residue is then added a large excess of crystallised urea (about 0.25 gram) about 2 C.C. of boiling water are then added from a wash-bottle to the mix-ture in the beaker and in this the urea and nitrite rapidly dissolve ; the solution is then carefully transferred to fhe cup of a tube similar to that used in the determination of nitric acid by the mercury-method and as figured in the cut.This tube which I employ of the following dimensions (6" long by $" in diam. internal the cup being 1" in depth) is filled with mercury and trough. By carefully opening the tap the stands in a mercury-liquid in the cup i 366 FRANKLAND A OASOMETRIC METHOD OF admitted into the tube. The beaker is now repeatedly rinsed with small quantities of boiling water and the rinsings similarly transferred to the mercury-tube. An excess of dilute sulphuric acid (1 5) only amounting to a few C.C. in volume is now poured into the cup and admitted into the tube. A vigorous evolution of gas then commences, and continues for some five minutes. This gas consists of a mixture of nitrogen and carbonic anhydride.The decomposition in the cold with an excess of urea taking place according to Claus (Bey. 4 140), as represented by the equation :-BCO(NH,) + N,O = CO(NH40) + CO + 2N2. After 15 minutes when the decomposition may be taken to be complete a strong solution (1 3) of pure caustic soda (free from nitrite) is added through the cup and the mixture violently agitated until the carbonic anhydride is completely absorbed. The lower extremity of the tube is then firmly closed with the thumb and the tube transferred to another mercury-trough in which the gas and liquid are passed into the "laboratory-vessel" of an apparatus for the measurement of gases. The volume of nitrogen under known conditions of pressure and temperature is then ascer-tained and from this the weight of nitrogen can be calculated.Thus in the experiment in question-Volume of nitrogen = 13.79 C.C. Pressure = 255.5 mm. of mer-cury. Temperature = 18.9" C. Weight of nitrogen from 10 C.C. of standard sodium nitrite solu-tion = 0*0013615 gram. Weight of nitrous nitrogen in ditto determined by standard per-manganate = 0*001346 gram. (2.) 10 C.C. of the same sodium nitrite solution similarly treated, yielded-Volume of nitrogen = 13.79 C.C. Pressure = 127.5 mm. of mer-cury. Temperature = 17.7" C. Weight of nitrogen from 10 C.C. of standard sodium nitrite solution = 0.0013645 gram. Thus the accordance of the nitrogen found with that calculated from the standardisation with permanganate is very close.Experiments were made in order to determine whether the reaction between the urea and nitrite is really complete in 15 minutes or whether a larger volume of nitrogen would be obtained if the time for the reaction was extended. Thus three portions of 10 C.C. each, of a solution of sodium nitrite were evaporated in three small beakers, each of which was treated as above described ; in the case of the first portion the reaction with the urea was interrupted at the end o DETERMINING NITROUS ACID. 367 ~~~ ~ Reaction Volume Pressure interrupted of after nitrogen. in mm. ture. 15 minutes by the addition of the excess of caustic soda whilst in the case of the second portion the addition of the caustic soda was made after three hours and with the third portion after 23 hours.The following results were obtained :-~ Weight of nitrogen from 10 C . C . of solution. No. 1 . 15 minutes 13 *79 C.C. 252 -7 13 *2' C. 0*0013734 gram 3 hours 253.7 13.5 0'0013774 , : ;:::I 23 , 1 : 1 252.2 1 13.6 : 1 0.0013688 ,, The above results show that the reaction is complete in 15 minutes, and that no more gas is evolved even if the time is extended to 23 hours. Comparison of Urea-method with Mercury-method of determiihg Nitrites. Experiments were also made in order to compare the results of the urea-method with those obtained by the mercury-method which does not discriminate between nitrous and nitric nitrogen. The same standard solution of sodium nitrite was employed for the purpose, with the followiug results :-(1.) 20 C.C.of the solution of sodium nitrite were evaporated in a small beaker on the water-bath. The residue was then repeatedly extracted with very small quantities of hot water and these successive extracts transferred to the mercury-tube as described above. The small beaker was then rinsed with strong sulphuric acid (free from nitrogen-compounds) and the rinsings which amounted in volume to that of the aqueous extract were also transferred to the mercury-tube. The mercury-tube was then closed at the bottom with the thumb of the right hand and the tube violently shaken without however allowing the acid mixture in the tube to come in contact with the thumb. The evolution of nitric oxide commenced at once and the pressure exerted by the liberation of the gas in the tube had to be relieved by with-drawing the thumb from the extremity of the tube when under mercury.The evolution of gas was complete in the course of a few minutes and the gas was then transferred to the measuring apparatus as described before. In this case also the volume of nitric oxide obtained is twice that of the nitrogen which it contains. Volume of nitric oxide = 13.76 C.C. Pressure = 246.9 mm. of Weight of nitrogen from 10 C.C. of standard solution of sodium Thus-mercury. Temperature 16.3" C. nitrite = 0.001323 gram 3 68 FRANKLAND A GASOMETRIC METHOD OF (2.) 20 C.C. of the solution of sodium nitrite treated in a perfectly similar manner yielded-Volume of nitric oxide = 13.79 C.C. Pressure = 256.2 mm. of Weight of nitrogen from 10 C.C. of solution = 0.001376 gram.( 3 . ) 20 C.C. of the solution of sodium nitrite were evaporated to dryness in a small beaker and the nitrous nitrogen determined by the urea-method. Thus-mercury. Temperature = 16.6" C. Volume of nitrogen = 13.79 C.C. Pressure = 256.0 mm. of Weight of nitrogen from 10 C.C. of solution = 0.001375 gram. (4.) 20 C.C. of the solution of sodium nitrite similarly treated mercury. Temperature = 16.7" C. 9 i el de d-Volume of nitrogen = 13-79 C.C. Pressure = 256.2 mm. of Weight of nitrogen from 10 C.C. of solution = 0.001375 gram. Weight of nitrous nitrogen in 10 C.C. of solution of sodium nitrite (as determined by standard permanganate) = 0.001346 gram. The results obtained by both gasometric methods thus not only agree very closely together but also with the permanganate estima-tion.mercury. Temperature = 16.9" C. Determination. of Nitrous Acid in Presence of Peptones and Ammonia Salts. On applying the urea-method to the actual solutions in which I wished to determine the nitrous acid I found that the results obtained were invariably very decidedly low. The solutions in question con-tained calcium nitrate invert-sugar peptone and carbonate of lime in suspension besides very minute quantities of calcium chloride, magnesium sulphate and potassium phosphate. Potassium phosphate 0.1 gram7 Magnesium sulphat e 0.02 Calcium chloride. . 0.01 , Nitrogen (combined in the form 0.168 ,, Invert -sugar 0.3 , Peptone. 0.25 , J Thus- " I fper 1000 C.C. i of calcium nitrate) . . . .. . . . . . . . . . . This solution was in fact prepared for the cultivation of certain micyo-organisms in order t o ascertain their action on the nitric aci DETERMINING NITROUS ACID. 3ti9 present. Although this solution was in the first instance quite free from ammonia yet durizg the growth of some of the micro-organisms under examination ammonia was produced and it became necessary to have a method for determining the nitrous acid in the presence of the latter. Experiments mere first made by adding known quantities of a standard solution of nitrite to the above solution free from ammonia, which may for convenience be designated as Solution A. (1.) I n the first place the nitric nitrogen in Solution A was deter-mined by evaporating 10 c.c. and treating the residue by the mercurg-method ; this gave-Weight of nitric nitrogen in 10 C.C.Solution A = 0.00337 gram. (2.) 20 C.C. of a solution of sodium nitrite was similarly treated, the nitrous nitrogen being determined by the mercury-method ; this gave-Weight of nitrogen in 10 C.C. solution of sodium nitrite = 0*001445 gram. ( 3 . ) 20 C.C. of sodium nitrite solution were evaporated aud the nitrous nitrogen determined by the urea-method ; this gave-Weight of nitrogen in 10 C.C. of solution of sodium nitrite = 0.001405 gram. A mixture of 5 C.C. Solution A and 10 C.C. of the sodium nitrite solution was evaporated and the nitrous and nitric nitrogen in the residue determined by the mercury-method ; this gave-Total weight of nitrogen = 0.00217 gram, if from this the nitric nitrogen in the 5 C.C.of Solution A is sub-tracted only 0.001085 gram N is left for the 10 C.C. of sodium nitrite. (5.) A similar mixture of 5 C.C. Solution A and 10 C.C. of the sodium nitrite solution mas evaporated and the nitrous nitrogen determined by the urea-method ; this gave-Nitrous nitrogen = 0.00104 gram. this coincides therefore very closely with the amount found by difference in the previous experiment. ( 6 . ) A similar mixture of 5 C.C. Solution A and 10 C.C. of the sodium nitrite treated similarly to ( 5 ) gave-Nitrous nitrogen = 0.00103 gram. (7.) Another experiment was made to see whether the amount o 370 FRANKLAND A OBSOMETRIC METHOD OF nitrous nitrogen lost was diminished by increasing the proportion of nitrite to Solution A.For this purpose a mixture of 5 C.C. Solution A and 20 C.C. of sodium nitrite was evaporated and the nitric and nitrous nitrogen determined together by the mercury-method. The result was-Total nitrogen = 0.00412 gram. Subtracting the nitric nitrogen of the 5 C.C. Solution A the nitrous nitrogen left amounts to 0.002435 gram for the 20 C.C. sodium nitrite employed or 0.001218 gram for 10 C.C. Thus by increasing the proportion of nitrite to a given qnantity of Solution A the proportional loss of nitrous nitrogen is diminished. From rough experiments in which the nitrogen evolved by the urea-method was measured in the common nitrometer I have every reason t o believe that the ingredient of Solution A which causes the loss of nitrous nitrogen on evaporation is the peptone and not the invert-sugar.In fact possibly the peptone and nitrite enter into a reaction of a similar kind t o that which takes place when a solution of an alkaline nitrite is heated with a solution of an ammonium salt, thus-NH4C1 + NaNO = N + NaCl + ZOH,. It occurred to me that such an action of the peptone might, possibly be counteracted by the presence of an excess of caustic alkali during the evaporation of the solution on the water-bath. To ascertain whether this was the case or not the following experiments were made :-(1.) 20 C.C. of standard sodium nitrite were mixed with 10 C.C. of Solution A and 2 drops of a strong solution of caustic potash (1 2) were added to the mixture which was then evaporated to dryness, and the nitrous nitrogen determined by the urea-method.The result was-Volume of nitrogen = 13.79 C.C. Pressure = 258.2 mm. of Nitrous nitrogen per 10 C.C. = 0.001388 gram. (2.) A perfectly similar mixture to which no potash had been Volume of nitrogen = 13.79 C.C. Pressure = 216.7 mm. of Nitrous nitrogen per 10 C.C. = 0.0011631 gram. (3.) 10 C.C. of the sodium nitrite solution alone gave-Volume of nitrogen = 13.79 C.C. Pressure = 137.5 mm. of Nitrous nitrogen per 10 C.C. = 0.0013645 gram. mercury. Temperature = 16.4" C. added gave-mercury. Temperature = 16.8" C. mercury. Temperature = 17.7" C DETERNINING NITROUS ACID. 371 From these experiments it is evident that the addition of the caustic potash had entirely prevented the loss of nitrous nitrogen during the evaporation of the nitrite with the peptonc.The influence of ammonia salts on the determination of nitrous acid had next to be ascert,ained. For this purpose the following experiments were made :-(1.) 25 C.C. of the standard solution of sodium nitrite (0.001346 gram N per 10 c.c.) were a,dded t o 5 C.C. of a standard solution of ammonium chloride (1.5735 grams NH,C1 per litre) four drops of the strong solution of caustic potash being added to the mixture; this was then evaporated to dryness and the nitrous nitrogen determined by the urea-method. The result was-Volume of nitrogen = 13.79 C.C. Pressure = 317.0 mm. of Nitrous nitrogen per 10 C.C. = 0.0013754 gram. (2.) 25 C.C. of sodium nitrite with 10 C.C. of ammonium chloride and four drops of caustic potash were treated in a precisely similar manner :-mercury.Temperature = 13.8" C. Volume of nitrogen = 13.79 C.C. Pressure = 311.2 mm. of Nitrous nitrogen per 10 C.C. = 0.0013474 gram. (3.) 25 C.C. of the sodium nitrite solution were evaporated with 10 C.C. of the ammonium chloride without any addition of caustic potash. On treating the residue according to the urea-method not a trace of gas was evolved showing that the whole of the nitrous nitrogen had been dissipated by evaporation with ammonium chloride. From experiments (1) and (a) however it is evident that the. quantity of caustic potash there added had been quite sufficient to prevent any destruction of nitrous nitrogen during evaporation. Finally a series of experiments was made in order t o ascertain whether in a mixture containing nitrates nitrites and ammonia the nitrate could be determined by the mercury-method after evaporating the solution to dryness with an excess of ammonium chloride and the nitrite by the urea-method after evaporating with an excess of caustic potash.Thus-(1.) 10 C.C. of a solution of calcium nitrate were evaporated and the nitric nitrogen determined by the mercury-method ; this gave-mercury. Temperature = 14.4" C. Volume of nitric oxide = 22.63 C.C. Pressure = 306.6 mm. of Weight of nitric nitrogen per 10 C.C. = 0.0053937 gram. mercury. Temperature = 17.2" C 372 11 GASOMETRIC METHOD OF DETERMINING NITROUS ACID. (2.) Ditto in every respect. Volume of nitric oxide = 22.63 C.C. Pressure = 310.4 mm. of Nitric nitrogen per 10 C.C.= 0.005451 gram. The strength of the solution of calcium nitrate may thus be taken (3.) 20 C.C. of a solution of sodium nitrite were evaporated and the mercury. Temperature = 17.7" C. as 10 C.C. = 0.00542 gram nitrogen. nitrous nitrogen determined by t,he urea-method ; thus-Volume of nitrogen = 13-79 C.C. Pressure = 249.7 mm. of Nitrous nitrogen per 10 C.C. = 0*001346 gi'am. (4.) 10 C.C. of the solution of calcium nitrate with 20 C.C. of the solution of sodium nitrite and 20 C.C. of solution of ammonium chloride (1.5735 gram NH,Cl per litre) were evaporated to dryness on the water-bath and the nitric nitrogen determined by the mercury-method. Thus-mercury. Temperature = 15.5" C. Volume of nitric oxide = 13.79 C.C. Pressure = 512.4 mm. of Nitric nitrogen per 10 C.C.= 0.0055335 gram. mercury. Temperature = 15.1" C. (5.) Ditto in every respect. Volume of nitric oxide = 13.79 C.C. Pressure = 511.2 mrn. of Nitric nitrogen per 10 C.C. = 0.005485 gram. mercury. Temperature = 16.9" C. (6.) 10 C.C. of the solution of calcium nitrate with 20 C.C. of the solution of sodium nitrite and 10 C.C. of ammonium chloride were evaporated with five drops of strong caustic potash the nitrous nitrogen being then determined by the urea-method. Thus-Volume of nitrogen = 13.79 C.C. Nitrous nitrogen per 10 C.C. = 0.001452 gram. Pressure = 268.4 mm. of mercury. Temperature = 14.Z" C. ( 7 . ) Ditto in every respect. Volume of nitrogen = 13.79 C.C. Pressure = 259.2 nim. of Nitrous nitrogen per 10 C.C. = 0.001400 gram. These results show that the difficult task of quantitatively det'er-mining nitric and nitrous acids in the presence of ammonia can be mercury. Temperature = 15.0" C ACTION OF SPECIFIC MICRO-ORGANISMS ON NITRIC ACID. 373 satisfactorily accomplished by means of the mercury- and urea-methods respectively the destruction of the nitrous acid on the one hand being effected by means of an excess of ammonium cbloride, whilst on the other hand all loss of nitrous acid can be avoided by evaporation with excess of caustic alkali. This mode of procedure has a great advantage over all differential methods of determining nitrous and nitric acids as each acid is determined individually and quite independently of the other. The urea-method of determining nitrous acid as described above is both convenient rapid and trustworthy and is suitable for all cases in which only small quantities of nitrous acid are available. The method may also be adapted for use with the common nitro-meter when larger quantities of nitrite are present

ISSN:0368-1645    

DOI:10.1039/CT8885300364

出版商:RSC    

年代:1888

数据来源: RSC

摘要:

ACTION OF SPECIFIC MICRO-ORQANISMS ON NITRIC ACID. 373 XXVIK-The Action of some Bpec$c Micro. organisms on Nitric Acid. By PERCY F. FRANKLAND Ph.D. B.Sc. F.S.C. Associate Royal School of Mines. THAT nitric acid may be reduced to nitrous acid by the agency of bacteria appears to have been first shown in 1875 by Meusel (Ber. 8, 1215) who found that well-water containing nitrates and bacteria on standing for some days gave a definite reaction for nitrous acid, which was prevented by the addition of antiseptic substances such as salicylic carbolic or bmzoic acids. He also found that on adding nitrates and carbohydrates to water containing bacteria the nitrates soon became converted into nitrites. In 1882 Gayon and Dupetit (Ber. 15 1882 2736) describe the reduction of nitrates by " anaGrobic " micro-organisms.Again in the same year DBhBrain and Maqueniie (Bey. 15 1882 3081) ascribe the reduction of nifrates in the soil to the agency of the butyric ferment, the so-called BaciElus amylobacter. I n 1883 Gayon and Dupetit (Ber. 16 1883 '221 ; Conzpt. rend. 95, 1365) further describe the decomposition of nitrates by other anaiirobic micro- organisms, The reduction of nitrates by micro-organisms is also frequently referred to by Warington in his well-known researches on nitrification, and has been also confirmed and elaborated by Nunro (Trans. 1886, 632). Heraeus (ZeitscJir. f. Hygiene 1886 193) has also made experi-VOL. LIII. 2 374 FRANKLAND THE ACTION OF ments on the reduction of nitrates by micro-organisms and these appear to be the first in which pure cultivations obtained by the modern methods of separation and isolation which can alone guarantee the absolute purity of the cultures have been employed.To these experiments further reference will be made later on. With few exceptions however all the experiments referred to above have been made not with pure cultivations of well-characterised micro-organisms but with casual mixtures of microbes such as are obtained from soil sewage natiiral waters and the like. I n the course of investigations which I have now been carrying on for some years past. on the micro-organisms present in the atmosphere and in natural waters I hare had occasion to collect a number of micro-organisms from these sources to cultivate them in a state of purity and to characterise them in such detail that they may be readily identified by subsequent observers.It appeared to me there-fore very desirable that the action of these asrial and aquatic micro-organisms on nitrates should be carefully studied more especially as there has been some tendency to believe that nearly all microbes possess the property of decomposing nitrates if placed under suitable conditions. Method of Experiment. The nitric acid submitted to the action of the va,rious micro-organ-isms was in combination as calcium nitrate contained in a solution capable of nourishing the microbes. In the first instance solutions were employed in which the only nitrogen present was the nitric nitrogen of the calcium nitrate but in such solutions the growth of the micro-organisms was so uncertain that it was found necessary to introduce a small proportion of peptone although thereby somewhat complicating the composition of the nutritive liquid.The solution which ultimately appeared most suitable for the pur-pose had the following composition :-Potassium phosphate Calcium chloride (fused) Invert sugar Magnesium sulphate (cryst.). . Nitrogen (combined in the form of calcium nitrate) Peptone . 0.1 gram7 0.01 O.O2 ” I I’ > 0.5 ,, 0.65 , J in 1000 C.C. of dis-tilled water with 4 grams of pure ’ calcium cirbo-nate in suspen-sion. This solution was poured into sterilised bottles plugged with sterile cotton-wool so that each bottle was from three-fourths to five-sixths filled with liquid.The bottles so filled were then finally sterilised by steaming for one hour on four successive days SOME SPECIFIC MICRO-ORGANISMS ON NITRIC ACID. 37 5 The solution thus prepared gave no reaction either with Nessler's solution or with the sulphanilic acid and phenol test €or nitrous acid. Into these sterilised solutions the particular micro-organisms were inoculated with a platinum needle the cotton-wool stopper being singed in a Bunsen flame just before extracting it to permit of the introduction of the platinum needle the stopper being then imme-diately replaced when the inoculation was complete. Of the micro-organisms experimented with those derived from air have been fully described by me (Roy. Xoc. Phil. Trans. 1887 178 B, 255-287) whilst those derived from water will short,ly be similarly described.First Xem'es of Experz'meds. A series of bottles containing the above solution were inoculated in the way described with the various micro. organisms mentioned below ; the inoculated bottles were then placed in the incubator and kept at a temperature of 50" C. and submitted to examination after the specified intervals of time. In examining the solutions a number of pipettes which had been steam-sterilised were kept in readiness the cotton-wool plug of the bottle to be opened was singed in a Bunsen, then withdrawn with a pair of forceps and the sterile pipette intro-duced and by means of it a few cubic centimetres of the liquid taken out the cotton-wool plug being then immediately replaced. The results of this first examination (table p.376) showed at once that there exist very marked differences in the behaviour of different micro-organisms towards nitrates. Thus whilst some of the orga-nisms in question had in the course of tbree days converted a large amount of nitrate into nitrite others had given rise to the production of no nitrite at all whilst the growth of others again had resulted in the formation of only traces of nitrous acid. It is moreover noticeable that these differences are by no means dependent upon the greater or less vigour of the growth to which the several organisms give rise in this medium. Thus many of the organisms such as B. viscosus, nubilus subtilis produce strong visible growths in the solution, rendering the latter excessively turbid or producing flocculent deposits without giving rise to the formation of any nitrite.It is moreover very noticeable that all the organisms without exception which give rise to the production of an appreciable amount of nitrous acid are bacilli whilst not one of the micrococci examined gives rise to more than a doubtful indication of nitrite. Again it is very remarkable how differently two organisms like R. subtilis and B. cereus which in their microscopical and other mor-phological characters are only with difficulty dist.inguishable behave 2 c 376 FRASKLLAND THE ACTION OF Exanzination of h'olutiono after 3-4 Days' Growth at 30". Name of micro-organism. Bacillus ramwws . . B. uiolacew. B. v m i c u l a v i s B. Izu6ilus B. viscosus 3.aquatilis B. liquidus . B. arborescens . B. aurantiacus B. cereus B. subtilis . B. l m i s B. pest ;fer B. p&xxtecs B. prodigiosus. B. aurescens €3. aureus . B. Jluorescens . B. chlorinus B. citreus . B. profusus 3. pt?ymoq-pBus. . Sarcina aurantiaca. Sarcina lutea Sarcina lipuef aciens Streptococcus lipue-Xicrococcus rosaceus M. carnicolor . M. git9as M. albus M. candicaus M. chryseus . Blank experiment . . f aciens Appearance of solution. Liquid clear but abundant mem branous growths on sides ol bottle Liquid very slightly turbid nu. merous violet lumps on botton: of bottle Liquid very turbid but not muck deposit Liquid turbid not much deposit Liquid turbid not much deposii Liquid very tnrbid not much Liquid turbid nok much deposit No visible growth No visible growth Liquid not very turbid but con.Ditto Liquid turbid not much deposit Liquid very turbid not much Liquid very slightly turbid, Liquid turbid not much deposit Liquid not very turbid but some Liquid very turbid,and consider-Liquid very turbid not much Ditto Liquid very slightly turbid a Liquid slightly turbid not much Liquid scarcely turbid Liquid very turbid not much Ditto Liquid slightly turbid distinct Liquid very slightly turbid Liquid turbid not much deposit Ditto Ditto deposit siderable flocculent deposit deposit little or no deposit yellow deposit able yellow deposit deposit little yellow deposit deposit deposit deposit Liquid very slightly turbid Ditto Liquid almost perfectly clear Liquid perfectly clear Reaction with sulphanilic acid phenol, and ammonia.Very strong. Very strong. Strong. None. None. Very faint. Strong. None. None. Strong. None. None. Very strong. Very strong. Strong. Decided. Faint. Distinct. Distinct. Distinct . None. None. None. None. None. None. Very faint. None. None. None. None. None. None SOME SPECIFIC MICRO-ORGANISMS ON NITRIC ACID. 37 7 Examination of the same Solutions after 41 Days' Growth. Name of micro-organism. B. ramosus* . . . . B. violaceus* . . . . B. vermicularis" , B. nubi1u.P . B. viscosus . . . . B. aquatiZtP . . . . B. liquidus' . . . . , B . arborescens-B.aurantiacus" B. cereus* . . . . , B. subtilis* . . . . B. lawis* . . . . B. pestifer" . . . , B. pZicatus- . . . . B. prodigiosus + , B. aurescens- . . B. aurew- . . . . , B. YfEeCorescens - . B. chlorinus* . . . B. citreus- . . . . . B. profusus- . . . B. polymorphus -Sarcina auran-Sarcina Idea* Sarcina liquefaci-Streptococcus Ei-M. rosaceus- . . . tiaca -em* quefaciens" M. carnicolor- . M. gigas . . . . . . . M. alhus- . . . . . . M. candicans- . . M. chryseus + . . . .Blank exprnt,. - . . -Origin. Water 11 11 Y Y 1 , 9 9 9 9 9 1 9 1 Air 11 11 Y1 > ? 11 f Y Y 1 J I J 9 19 >1 >1 1 9 9 1 91 19 9 3 Y 9 ,Y >1 11 JJ -Appearance of solution. Liquid quite clear much flocculent deposit Liquid nearly clear.Con-siderable violet deposit Liquid elightly opalescent. Not much deposit Liquid almost clear Ditto Liquid slightly opalescent Liquid slightly turbid Liquid quite clear Liquid almost clear. Orange deposit Liquid nearly clear. Much flocculent deposit Ditto Liquid nearly clear Ditto Ditto Liquid slightly opalescent Liquid very turbid. Some yellow deposit Liquid very turbid. Con-siderable orange deposit Liquid almost clear Liquid opalescent. Some Liquid clear Liquid almost dear Liquid quite clear Liquid very turbid. Some yellow deposit Dit,to Liquid very turbid Liquid clear Liquid very opalescent. Liquid slightly opalescent. Liquid almost clear Liquid clear Liquid almost clear Ditto Liquid perfectly clear yellow deposit Little red deposit No red colour teaction with di-phenyl-amine.Strong 91 Y7 19 7 1 9 7 71 1? Y J 71 >1 7, 11 11 Y Y 1 , J Y 71 11 19 1 ) 9 1 1 7 >, Y Y 9 9 Y Y f9 > Y > I 2 1 1 ) J1 Reaction with sulphanilic acid phenol, and ammonia. Strong yellow-red. Strong yellow-red. Strong yellow-red. Straw colour. None. Very faint in-deed. Strong yellow-red. None. None. Strong yellow-red. None. None. Strong yellow-red, 39 9 1 Faint B trmw. Y Y Strong yellow. Straw. Strong yellow. Straw. None. None. None. None. None. Pale straw. Strong yellow. None. None.None. None. None 378 FRANKLASD THE ACTION OF towards nitrates ; thus whilst B. cereus reduces the nitrate power-fully B. subtilis yields no nitrite whatever and thus the two organisms become most sharply distinguishable on being submitted to this chemical test. The solutions tested a s above were now allowed to remain at the ordinary temperature of the laboratory (about 20") until they were again examined 41 days after their first inoculation (table p. 377). Thus the longer preservation of the solutions had produced no marked difference in the results. The solutions which gave a strong reaction for nitrous acid after three days' growth still gave the same, and those which gave no reaction in the former examination were still free from nitrite after 41 days excepting in the case of AI.carnicdor which though free from nitrite before now gave a dis-tinct reaction. Further experiments have shown that this organism, M. carnicolor does slightly reduce the nitrate and moreover in a more marked manner than the very similar M. rosaceus which in no case gave more than a very faint indication of nitrite. The fact that all the solutions gave strong reactions with diphenyl-ainine shows that i n no case had the oxidised nitrogen been destroyed, that is completely reduced to ammonia assimilated as organic nitro-gen or eliminated as free nitrogen or oxide of nitrogen. The solutions were again examined after another interval the total length of time since inoculation being now 137 days ; the reactions for nitrous acid were practically identical with those given in the last series and need not therefore be repeated.The solutions were, however on this occasion also tested for ammonia with Nessler's solution with which they were fouiid to exhibit great differences. Thus in the above solutions those which yielded a strong reaction with the Nessler test are marked* whilst those which yielded a distinct but not very strong one are marked + and those which yielded practically no reaction are marked -Second Series of Ezperirnents. In order to determine whether the results obtained in the former series of experiments were constant for the particular micro-organ-isms or merely accidental a number of similar solutions were inoculated with some of the micro-organisms which had produced the most striking results.After three days' growth in the incubator a t 30° these inoculated solutions were submitted to examination with Nessler's test with the diphenylamine test and by nieans of sulph-anilic acid phenol and ammonia. Thus : SOME SPECIFIC MICRO-ORGANISMS ON NITRIC ACID. 37 9 Examination of Xolutions after three Days' Growth at 30". Name of micro-organism. B. ram0su.s . . B. cereus . . . . B. subtilis . . . . B. viscosus . . . . B. chlorinw M. rosaceus . . . M. carnicolor . . Blank experi-ment Appearance of solu-tion. - - ~ Liquid quite clear but numerous tufts over sides and bottom of bottle Abundant flocculent matter and deposit Abundant flocculent deposit Liquid very opalescent, 1it.tle or no deposit Ditto Ditto Liquid very opalescent, very slight flocculent deposit Liquid quite clear Reactions with Diphenyl-smine._--Very deep blue Ditto Ditto Ditto Ditto Ditto Ditto Ditto Sulphanilic acid. Very strong yello w-red Ditto None None Strong chrome- yel-low Faint Chrome-y el-low colour None Nessler. Strong. Fairly strong. Ditto. None. Very strong. Slight. Slight. None. Thus in each case the previous results were confirmed. Quantitative Experiments. Having thus by the above experiments determined which micro-organisms give rise to the reduction of nitrates to nitrites a number of quantitdive experiments were now made in order to ascertain the manner in which the nitrogen was distributed in the forms of nitrate, nitrite and ammonia after the growth of the several organisms.The determinations of nitrate and nitrite were made on the lines laid down in my previous communication " On the Determination of Nitrous Acid," the nitric acid being estimated by the measurelrrent of the nitric oxide gas obtained by decomposition with mercury whilst the nitrous acid was estimated by measuring the nitrogen liberated by the action of urea and dilute sulphuric acid. For the purpose of these determinations 10 C.C. of the solutions were in each case taken and on this account the actual results obtained for this volume of solution are given below as well as those calculated to parts per 100,000. The accurate determination of ammonia in solutions of this kind is attended with great difficulty owing to the presence of basic product 380 FRANKLAND THE ACTION OF other than ammonia ; these give colorations with the Nessler-test which cannot be satisfactorily compared with those obtained with a standard solution of ammonium chloride owing to the difference in the colours.The estimations of ammonia cannot therefore lay claim to any great degree of accuracy but they serve to indicate certain broad differences in the action of the various micro-organisms. These determinations of ammonia were made by diluting a measured volume of the solution (the exact volume taken depending upon the propor-tion of ammonia present) with distilled water free from ammonia and then nesslerising. The first series of quantitative experiments was made with a num-ber of solutions which remained in the incubator at 30" for 26 days and then for nine days more at the ordinary temperature of the laboratory (about 16-18'] before they were submitted to examina-tion.With these solutions the following results were obtained. Blunk E::lperinzent.-The liquid was clear and transparent. (u.) 10 C.C. yielded 0.003342 gram nitrogen as nitrate. ( b . ) 10 , 0.003384 , 9 , (4 10 ) 0.003324 7 9 9 (d.) 10 , 0.003451 9 9 , Mean . . 0.003375 9 9 9 , or 33-75 parts of nitric nitrogen psr 100,000 parts of solution. Note.-This solution was prepared with twice the quantity of The solution was free from ammonia and nitrites. Bacillus vermicdnris.-The liquid was very opalescent with a fine deposit at the bottom it yielded strong reactions €or ammonia and nitrous acid.calcium nitrate mentioned on p. 374. 10 C.C. yielded 0.0012907 gram nitric nitrogen. 9 9 0.0021143 , nitrous nitrogen. 9 0.0034050 , nitrogen as nitrates and nitritee. Ammoniacal nitrogen in 10 C.C. = 0.000326 gram. 12.91 Parts per 100,000 Nitrous nitrogen . . . . . . 21.14 { Ammoniacal nitrogen . . 3.26 Nitric nitrogen . . . . . . . . BaciZEus pestifer.-The liquid gave very strong reactions for am-monia and nitrous acid. 10 C.C. yielded 0*001069 gram nitric nitrogen. 9 0.002285 , nitrous nitrogen. 3 ) 0.00335% , nitrogen as nitrates and nitrites SOME SPECIFIC MICRO-ORGANISMS ON NITRIC ACID. 381 Ammoniacal nitrogen in 10 C.C. = 0*000412 gram. Nitric nitrogen 10.69 Ammoniacal nitrogen . . 4.12 Parts per 100,000 22.85 Bacillus ramosus.-The liquid mas clear but contained abundance of characteristic tufted growths ; it gave strong reactions €or ammonia and nitrous acid.10 C.C. yielded 0.001668 gram nitric nitrogen. 3 0.001646 , nitrous nitrogen. Y 9 0.003314 , nitrogen as nitrates and nitrites. Ammoniacal nitrogen in 10 C.C. = 0*000309 gram. Nitric nitrogen 16.68 Ammoniacal nitrogen 3.09 Parts per 100,000 16.46 Bacillus prodigiosus.-The liquid was very opalescent but there was not much deposit ; it gave strong reactions for ammonia and nitrous acid. 10 C.C. yielded 0.0020355 gram nitric nitrogen. 9 0.0011931 , nitrous nitrogen. 79 0.0032286 , nitrogen as nitrates and nitrites. Ammoniacal nitrogen in 10 C.C. = OmOO0515 gram. Nitric nitrogen 20.36 Ammoniacal nitrogen .. 5.15 Parts per 100,000 11.93 Bacillus liquidus.-The liquid gave very strong reactions for am-monia and nitrous acid. 10 C.C. yielded 0*002042 gram nitric nitrogen. 9 0.001134 , nitrous nitrogen. 9 9 0.003176 , nitrogen as nitrates and nitrites. Ammoniacal nitrogen in 10 C.C. = 0*00068 gram. Nitric nitrogen 20.42 Parts per 100,000 11.34 Ammoniacal nitrogen . . 6.80 Bacillus pEicatus.-The liquid gave no ammonia reaction but n strong one for nitrous acid 382 FlZAKKLAND THE ACTION OF 10 C.C. yielded 0.002550 gram nitric nitrogen. ?9 0.000504 , nitrous nitrogen. 99 0.003054 , nitrogen as nitrates and nitrites. -Nitric nitrogen 25.50 Parts per 100,000 Nitrous nitrogen 5.04 { Ammoniacal nitrogen . 0 Bacillus jZuowscens.-The liquid gave practically no reaction for ammonia and not a strong one for nitrous acid.10 C.C. yielded 0.0032322 gram nitric nitrogen. 9 0.0000797 , nitrous nitrogen. 9 0.0033119 , nitrogen as nitrates and nitrites. Nitric nitrogen 32.32 Ammoniacal nitrogen . . 0 Parts per 100,000 0.80 Xnrcina Zutea.-The liquid was very opalescent with a fine yellowish It gave a very strong reaction for ammonia but none for deposit. nitrous acid. 10 C.C. yielded 0.0029928 gram nitric nitrogen. Ammoniacal nitrogen in 10 C.C. = 0.000371 gram. Nitric nitrogen 29.93 Ammoniacal nitrogen . . 3.71 Parts per 100,000 0 Bacillus apuatiZis.-The liquid was very opalescent with little or no I t gave a strong reaction for ammonia but none for nitrous deposit.acid. 10 C.C. yielded 0.002597 gram nitric nitrogen. Ammoniacal nitrogen in 10 C.C. = 0*000261 gram. Nitric nitrogen 25.97 { Ammoniacal nitrogen . 2.61 Parts per 100,000 Nitrous nitrogen 0 The above results may be conveniently summarised in the following table which also records the results of some determinations of am-monia made in solutions in which litkle or no nitrous acid had been produced by the action of the micro-organisms ; SOME SPECIFIC JIICRO-ORGANISMS ON ISITRIC ACID. 383 Quantiiative Results of Growth of Micro-organisms during 35 Days. Name of micro-organism. Blank experiment . . B. vermicularis . B. pestifer . B. ramosus B. l i p i d u s B. plicatus BJluorewens . Sarcina luiea . B. aquatilis Sarcina aurantiaca B.aurantiacus . B. aurescens . B. aureus B. viscosus B. prodigiosus Nitric nitrogen. 33 *75 12 -91 10 *69 16 '68 20.36 20.42 25-50 32 -32 29 -93 25 -97 Not determined Y j 91 32)-'63 Parts per 100,000. Nitrous nitrogen. -0 21 -14 22 -85 16 -46 11.93 11 -34 5.04 0.80 0 0 0 trace J 9 9 ) 0 Nitrogen as nitrates and nitrites. 33 '75 34 * 05 33 * 54 33 '14 33 '29 31 -76 30 *54 33'12 29 '93 25 -97 ----32 -63 Amrnoniacal nitrogen. 0 3 *26 4.12 3 a 0 9 5 *15 6'80 0 0 3.71 2 -61 0 - 3 4 2'06 0 *26 0 -82 0.52 From the above table it will be seen that in no case was the nitric acid of the original solution completely reduced and in those cases in which notable proportions of nitrous acid were produced the sum of the nitrous and nitric nitrogen was almost exactly equal to the nitric nitrogen in the original solution the ammonia in these cases being apparentlF derived from the decomposition of the peptone contained in the original solution.The peptone in the original solution amounted to 25 parts per 100,000 and it was found by combustion with soda-lime that the peptone employed contained 13.65 per cent. of uitrogen ; there would therefore be 3.41 parts of peptone-nitrogen per 100,000 which considering the impossibility of making accurate determiriations of ammonia in liquids of this kind does not differ very materially from even the largest proportions of ammoniacal nitrogen found in the solutions.There is in fact no evidence of the nitrate in the original solution being largely reduced to ammonia in any case. The following three experiments are of interest as showing how the reduction of the nitrate to nitrite may become complete and confirming the above opinion that none of the oxidised nitrogen is yeduced to ammonia. These experiments were made with a solution having the same composition as the one used in the above experi-ments only with less calcium nitrate in it. The solutions wer 384 FRANKLAND THE ACTION O F inoculated with Bacillus subtilis R. cereus and B. mmosus the nitric acid being also determined in a portion of t,he solution not inoculated. Blank Bayeriment.-This gave 19.30 parts nitric nitrogen per B. subti2is.-The solution was examined 70 days after inoculation.The nitric nitrogen only was determined as it gave no reaction for nitrous acid. 100,000. 10 C.C. gave 0.001950 gram nitric nitrogen or 19.50 parts of nitric B. cereus.-This also was examined 70 days after inoculation. 10 C.C. gave 0.001962 gram nitrous nitrogen or 19.62 parts nitrous B. ramsus.-This also was examined 70 days after inoculation. The 10 C.C. gave 0.001968 gram nitrous nitrogen or 19.68 parts nitrous nitrogen per 100,000. The nitrous nitrogen only was determined, nitrogen per 100,000. nitrous nitrogen only was determined. nitrogen per 100,000, Thus the solution in which the B. sicbtilis had flourished retained its nitrate quite unchanged although from numerom other experi-ments we know that a notable proportion of ammonia must have been formed and this must consequently have been derived from the organic nitrogen of the peptone.The whole of the original nitric nitrogen on the other hand was found as nitrous nitrogen in the solutions in which B. cereus and B. rurmsus had flourished so that the ammonia which numerous other experiments show to have been produced in these solutions, must have been derived from the organic nitrogen of the peptone. Experiments with Exclusion of Air. In all the experiments hitherto described the bottles containing the solutions were plugged with cotton-wool only so that more or less free circulation of air was possible. Experiments were now made in order to ascertain whether if access of air to the solutions was prevented materially different results would follow.For this purpose, immediately after inoculation the cotton-wool plugs were cut down so as to be flush with the neck of the bottle ; a quantity of melted wax was then allowed to drop on to the cut surface of the plug until the bottle was completely sealed and the surface of the wax was then further thickly coated with cerate. For these experiments a number of those micro-organisms wer SOME SPECIFIC MICRO-ORGANISMS ON NITRIC ACID. 385 taken which had in the previous experiments exerted no reducing action on the nitrate and which it was thought might possibly do SO when air was wholly excluded in this manner. The inoculated bottles were kept in the incubator at 30" for 14 days a,nd they then remained 21 days longer at the ordinary tem-perature of the laboratory (16-18") before examination.The solutions were tkus 35 days old when the following results were obtained :-BaciZZus subtiZis.-The liquid was quite clear but abundance of flocculent matter had collected on the bottom of the bottle. The Iiquid gave a strong reaction for ammonia but none for nitrous acid. 10 C.C. yielded 0.003349 gram nitric nitrogen. 7 ) 0.000168 , ammoniacal nitrogen. Parts per 100,000 Nitrous nitrogen 0 Nitric nitrogen 33.49 { Ammoniacal nitrogen . . 1.68 Thus just as in the previous experiments with this micro-organism, Bnc-ilZus Zavis.-The liquid was slightly opalescent ; some flaky The liquid gave a the nitric nitrogen remained wholly uiiaff ected by its growth. matter had collected at the bottom of the bottle.distinct reaction for ammonia but nolie for nitrous acid. 10 C.C. yielded 0.005379 gram nitric nitrogen. 71 , 0.000027 , ammoniacal nitrogen. Parts per 100,000 Nitrous nitrogen. 0 Nitric nitrogen 33.79 { Ammoniacal nitrogen . . 0.27 Thus as before the nitric nitrogen had remained wholly unaffected Sarcina Ziquefaciens.-The liquid had become quite clear but some The liquid by the growth of this organism. fine deposit had collected on the bottom of the bottle. gave a distinct reaction for ammonia but none for nitrous acid. 10 C.C. yielded 0.003360 gram nitric nitrogen. 9 , 0.000049 , ammoniacal nitrogen. Nitric nitrogen 33.60 { Ammoniacal nitrogen . . 0.49 Parts per 100,000 Nitrous nitrogen 0 In this case again the exclusion of air had not altered the result, the nitric nitrogen remaining quite unaffected by the growth of the organism 386 FRANRLANL) THE ACTION OF Sarcina aurantiaca.-The liquid was slightly opalescent with a con-It gave a strong reaction for siderable yellow flocculent deposit.ammonia but none for nitrous acid. 10 C.C. yielded 0.003420 gram nitric nitrogen. 9 2 , 0.000057 , ammoniacal nitrogen. Nitric nitrogen 34.20 { Ammoniacal nitrogen . . 0.57 Parts per 100,000 Nitrous nitrogeii 0 The nitric nitrogen had thus again remained quite unaffected. Micrococcus candicam-The liquid had become clear but some de-There was no reaction either for posit had collected at the bottom. ammonia or nitrous acid. 10 C.C. yielded 0.003330 gram nitric nitrogen. Nitric nitrogen 33.30 Parts per 100,000 Nitrous nitrogen O { Ammonincal nitrogen .0 In this case again the vigorous growth of the micro-organism had been without any effect on the nitrate. Bacillus aquatiZis.-The liquid was slightly opalescent with a small amount of deposit; it gave a strong reaction for ammonia but none for nitrous acid. (a.) 10 C.C. yielded 0.002621 gram nitric nitrogen. (b.1 9 , 0.002597 , ¶ ? Nitric nitrogen 26.09 c Ammoniacal nitrogen . . 1-34 Parts per 100,000 Nitrous nitrogen 0 The results obtained in this case coincide very closely indeed with those previously obtained when the air was not excluded and they show that this organism causes the disappearance of a considerable proportion of the nitric nitrogen without any corresponding formation oE nitrous acid or ammonia.Sirnilnr experiments were also made with two organisms which had previously been found to effect a powerful reduction of nitric to nitrous acid. Thus :-BaciZZus cerezcs.-The liquid had become quite clear but a consider-able amount of flocculent matter had collected on the bottom. The liquid gave vei-y strong reactions for ammonia and nitrous acid SOME SPECIFIC MICRO-ORGANISMS ON NITRIC ACID. 38 7 10 C.C. yielded 0.0016467 gram nitric nitrogen. !a 1 7 , 0.0013368 , nitrous nitrogen. (b.1 9 , 0.0013655 , 7 7, Y , 0.0002255 , ammoniacal nitrogen. Nitric nitrogen . . . . . . 16*47} = 29-98. Parts per 100,000 Nitrous nitrogen . . . . 13.51 { Ammoniacal nitrogen. 2.26 Bacillus ramosus.-The liquid had become quite clear but there were the characteristic streaming flocculi on the sides and bottom of the bottle.The solution gave very strong reactions for ammonia, and nitrous acid. 10 C.C. yielded 0.001724 gram nitric nitrogen. (4 3 , 0*001571 , nitrous nitrogen. (b.) 9 , 0.001561 , 9 9 9, 9 , 0.000309 , ammoniacal nitrogen, Nitric nitrogen . . . . . . 17'p4} = 32.90. Parts per 100,000 Nitrous nitrogen . . . . 15.66 { Ammoniacal nitrogen. 3.09 Thus in the case of both of these organisms the results are essentially similar whether the air is excluded or not the nitrate being powerfully reduced to nitrite whilst an appreciable quantity of aminoniais generated which at any rate in the case of B. ramosus, appears to be exclusively derived from the organic nitrogen of the peptone. Experimends with varying Proportions of Peptone and SzLgar.Of those organisms which powerfully reduce nitrates to nitrites, two representatives were taken-B. ramosus and B. pestifer-and with these further experiments were made with a view to ascertain whether the amount of nitrite formed in a given time was due to the proportion of either peptone or sugar or of both present in the solution. For this purpose five different solutions were employed as fol-lows :-Solution No. 1.-This was the same solution as tbat employed in the previous experiments and containing-Oe30 gram} in 1000 c.c. 0.25 Cane-sugar (inverted) . . . . . . . . Peptone ,, Solution Nos. 2 3 4 and 5.-These differed from No. 1 only in the proportions of sugar and peptone which they contained thus : 388 FRANKLAND THE ACTION OF 2.3. 4. 5 . in 1000 C.C. Cane-sugar (inverted). . 0.6 gram 2.4 0.6 2.4 { Peptone 0.25 , 0-25 1.0 1.0J These five solutions were inoculated with 3. ramosus and B. pestifel-respectively and kept for 19 days in the incubator at 32-33' before examination. The results obtained may be most conveniently snmmarised in the following table :-Parts per 100,000. Solution I. (Peptone 0.25 gram ; sugar 0.3 gram.) B. ramosus. B. pestifer. Nitric nitrogen 16.74 13.1 7 Nitrous nitrogen 16.08 22.27 Ammoniacal nitrogen 2.56 2.87 Solution 11. (Peptone 0.25 gram ; siigar 0.6 gram.) Nitric nitrogen 7.13 6.04 Nitrous nitrogen . . . . . . . . . . 27.02 28.72 Ammoniacal nitrdgen 2.26 1-64 Solutwn 111. (Peptone 0.25 gram ; sugar 2.4 gram.) Nitric nitrogen 11.71 4.15 Ammoniacal nitrogen 0.62 0.62 Nitrous nitrogen 21.18 29.09 Solutwn IV.(Peptone 1.0 gram ; sugar 0.6 gram.) Nitric nitrogen. . lost trace Ammoniacal nitrogen 6.15 3.69 Nitrous nitrogen . . . . . . . . . . 32.11 34.74 Solution '0. (Peptone 1.0 gram ; sugar 2.4 gram.) Nitric nitrogen 0 0 Nitrous nitrogen 32.60 33-98 Ammoniacal nitrogen 3.08 0.41 From this table it is apparent that as the proportion of organic matter in the shape of sugar and peptone is increased in these solutions so the amount of nitrate reduced to nitrite in a given time is also increased. Moreover the amount of nitrate reduced is far more dependeut 011 the proportion of peptone than on that of sugar SOME SPECIFIC MICRO-ORGANISMS ON NITRIC SCID.389 Thus solutions I1 and I11 contain the same proportion of peptone, whilst the sugar in 111 is four times as great as that in 11 yet not-withstanding the reduction to nitrite is much the same in both case, and with B. ramosus in fact the reduction is somewhat greater in solu-tion I1 than in 111. Again solution 1V contains f o u r times as much peptone as solution 11 whilst the proportion of sugar is the same in both; but whereas a considerable proportion of nitrate is left in solu-tion 11 it is practically completely reduced to nitrite in No. 1V ; or, in other words whilst the quadrupling of the peptone brings about complete reduction of the nitrate to nitrite (compare solutions I1 and IV) quadrupling the amount of sugar results in little or 110 increased reduction of nitrate.Another point brought out by these experiments is that the am-monia developed in these solutions is due to decomposition of the peptone and not to reduction of nitric or nitrous acids. Thus solu-tioris I 11 and IT1 all contain the same snznll proportion of peptone, and all yield comparatively small proportions of ammonia; it is, moreover particularly noticeable that solution 111 which contains four times as much sugar as 11 yields the smallest proportion of ammonia whilst solution I which contains the same amount of pep-toile but the least sugar yields the largest proportion of ammonia of the first three solutions ; whilst solution IT which contailis four times as much peptone as 11 with the same amount of s~igar yields the largest proportion of ammonia of all and solution V which con-tains the same amount of peptone as I V but four times the amount of sugar yields only a small proportion of ammonia.It appears there-fore that the maximum yield of ammonia is obtained when the pro-ycjrtion of peptone to sugar is high and the least when the proportion of peptone to sugar is low. Action of the various Micro-o?-ganisms o n ArnmoniTcat Nitrogen. I n order to ascertain whether any of these organisms possessed the power of oxidising ammoniacal nitrogen to nitrates and nitrites t h e j were severally inoculated into a solution of the following composi-tion :-Potassium phosphate. . . . . . . . Magnesiuni sulphate (cryst.). 0.02 ,, Calcium chloride (fused) a . . 0.01 ,, Ammonium chloride .. . . . . . . Cane-sugar (inverted) . . . . . . Peptone 0.1 gram] 1 in 1000 C.C. of dis-1 tilled water with } 4 grams of pure ” 1 calcium carbonate 79 I in suspension. , J 0.5 0.3 0-25 vor,. LIII. 2 390 ACTIOX OF MICliO - 0 RGAKISMS ON NITRIC ACID. The solutions were examined after 40 days' growth but in no case was anything more than a faint indication of nitrous acid obtainable with sulphanilic acid phenol and ammonia. It is worthy of notice that Heraeus (Zeitsch. f. Hygiene 1886 220) has experimented with three of the micro-organisms which I have had under observation viz. R. subfilis B. prodigiosus and B. ranzosus. On growing these in sterilised urine he found that B. subtiZis alone gave no nitrous acid reaction whilst the other two gave distinct reactions for nitrites; from this he concludes that 13.prodigiosus and B. ramosws possess oxidising powers and that R. suhtilis does not. My experiments however conclusively prove that both B. ~arnosus and B. prodigiosus exert a reducing action, whilst B. subtiZis does not ; and therefore that the nitrous acid reac-tions which he obtained in the case of the two former organisms, must obviously have been due to the reduction of the nitrate in the urine and not to oxidation of ammoniacnl nitrogen RS he supposes. That nitric nitrogen is an invariable constituent of human urine has been shown by Warington (Trans. 1884 669) and has i n fact been long known. The principal results arrived at in this investigation may be sum-marked as follows :-1.That there is a great difference in the power possessed by micro-organisms of reducing nitric acid. Of the 32 forms under examina-tion 16 or li were found to reduce nitric to nitrous acid more or less completely whilst 15 o r 16 were quite destit'ute of this power. 2. That this difference in reducing power may in certain cases be of great value in distinguishing between micro-organisms morpho-logically very similar. 3. The behaviour of the various micro-organisms in question was not altered in this respect by preventing access of air to the solu-tions in which they were cultivated. 4. I n no case did the reducing action lead t o the formation of any considerable amount of ammonia the development of ammonia in tdhe solutions being due principally if not wholly to the decomposi-tion of the peptone.5. In the case of two of the organisms possessing a strong reducing power it was found by more detailed experiments that the quantity of nitrate reduced to nitrite in a given time was depecdent on the proportion of organic matter-peptone and sugar-present in the solution the peptone exerting a far greater influence in this respect than the sugar. 6. I n these special experiments mentioned above it was found that the development of ammonia was dependent upon the peptone and sugar present the amount of ammonia formed being greatest wit ACTION OF ALCOHOLS ON ETHEREAL SALTS. 391 the highest proportion of peptone to sugar and least with the greatest proportion of sugar to peptone. 7. In nearly all cases in which partial or total reduct’on of nitrate to nitrite had taken place the sum of the nitrogen as nitrate and nitrite in the “ fermented ” solution was practically identical with the nitric nitrogen in the original ‘( unfermented ” solution whilst in those cases in which no reduction to nitrite took place the nitrate in the solution remained practically unaffected by the growth of the micro-organism. In one case however it was found that an organism, B. tquatilis which does not .reduce nitrates to nitrites caused by its growth the disappearance of a considerable proportion of nitric nitrogen this result being confirmed by a second experiment. 8. None of the organisms under examination were found capable of oxidising ammoniacnl nitrogen to nitrous or nitric acids when inti-o-duced in to a nutritive solution containing ammonium chloride

ISSN:0368-1645    

DOI:10.1039/CT8885300373

出版商:RSC    

年代:1888

数据来源: RSC

摘要:

ACTION OF ALCOHOLS ON ETHEREAL SALTS. 391 X X I X - A c t i o n of Alcohols on Ethereal Salts in Presence of S m l l Quantities of Xodic Alkylate. By T. PURDIE Ph.D. B.Sc. Professor of Chemistry in the University of St. Andrews and W. MARSHALL B.Sc. CONSIDERINCI the close analogy existing between metallic and ethereal halts on the one hand and metallic hydroxides and alcohols on the other it might well he expected that the chemical change ordinarily called double decomposition so constantly exhibited by nietallic salts iind bases would also be of frequent occurrence among their organic analogues the ethereal salts and alcohols. Various isolated instances of interchange of alcoholic radicle occuri*ing between ethereal salts and alcohols have been recorded. The Frobability of a double decomposition of this kind taking place in the course of operations on ethereal salts in alcoholic solution is indeed commonly recognised and proTided f o r by employing the alcohol con-taining the same radicle as the ethereal salt operated on ; but so far as we are aware these reactions have not except in a few instances, been made the subject of special study.Priedel and Crafts (L4nt~aZen 130 198 ; 133 807) heated various mixtures of alcohols and ethers amongst others mixtures of ethylic acetate with amylic alcohol and arnplic acetate with ethylic alcohol, 2 u 398 PURDIE AND MARSHALL ACTION OF and found that in each case interchange of radicle occurred. They concluded that this interchange was not due to varying specific affinities of the alcohols but was to be attributed rather to the in-fluence of mass.Rose (Annalcn 205,240) has shown on the other hand that in the case of the ethereal carbonates the alcohol of higher molecular weight can displace almost entirely the alcohol of lower molecular weight, vhile the converse reaction takes place to only a small extent. A. Bachmann (Annnlen 218 50) heated methylic and ethylic acetates with various alcohols of the C,H2,+,0H series to the boiling point of the higher boiling substance and did not observe any action. G. Bertoni (Ber. X. 17 251) prepared several ethereal nitrites by the action of alcohols on amylic nitrite and found contrary to the experience of R6se with the carbonic ethers that the amount of decomposition effected diminished with the increasing molecular weight of the alcohol.It has been shown by one of us (Trans. 1885,862 ; 1887,627) that, in general when an ethereal salt and alcohol a,re mixed and a minute quantity of sodic alkylate is added an extensive sometimes complete interchange of alkyl radicle takes place between the salt and the alcohol at the ordinary temperature. Several instances of this peculiar ackion of sodic alkylate noted by other observers were quoted in the paper referred to ; and recently Conrad and Epstein (Ber. 20, 3057) and Peters (Ber. 20 3323) have observed that the action is so complete in the case of mixtures of acetoacetates with alcohols that it furnishes a convenient method of preparation from ethylic accto-acetates of otlier acetoacetates which are procured with difficulty by the usual methods.The results of the experiments previously communicated by one of us to this Joizrnal show as might be expected that the amount of interchange of radicle which takes place in the presence of sodic alkylate is largely influenced by the rclative proportions of ethereal salt and alcohol used but they also give some indication that the interchange is conditioned to a certain extent by the composition of the alkyl radicles concerned in the action. Thus when sodic amylic oxide was added to a mixture of ethylic oxalate and amylic alcohol the ethylic oxalate almost entirely disap-peared axid much amylic oxalate was formed whilst in the converse case of amjlic oxalate and ethylic alcohol the formation of ethylic oxalate could not be detected.Similarly the action between ethylic acetate and amylic alcohol taking into account the unavoidable loss of amylic acetate incurred during fractional distillation was apparently greater than that between arnylic acetate and ethylic alcohol. The following investigation was undertaken with the view of determinin ALCOHOLS ON ETHEREAL SALTS. 393 whether in general the more complex radicle may be regarded as possessing under the conditions of our experiments a greater affinity for the hydroxyl oxygen of the acid than the less complex radicle. Onr results lead us to the conclusion that excluding the methyl radicle such is the case with respect a t all events to acetic acid and the radicles of the CnH2Bn+l type. Our experiments were conducted as follows :-The materials were taken in the proportion of 1 mol.of ethereal salt to 1 mol. of alcohol and i$a atom of sodium. In each cast, 50 grams of the ethereal salt mere employed and this was mixed with three-fourths of the alcohol. The sodium was dissolved in the remaiii-ing fourth and the solution of the alkylate then added slowly to the mixture of alcohol and ethereal salt. After the mixture had stocci 24 hours it was subjected to fractional distillation and the distillation continued until it could be inferred from the smallness of the inter-mediate fractions that a fairly complete separation of the low and high boiling ethereal salts had been effected. The lowest or in some cases the two lowest boiling fractions containing a mixture of alcohol a i d ethereal salt were mixed with a measured quantity of standard potassic hydrate in excess ; the mixture was allowed to stand some time in a well-stoppered flask and then digested using a reflux con-denser until hydrolysis was complete.The residual alkali was determined by means of standard sulphcric acid and the weight of ethereal salt in the fraction found by calculation. In the case of the action of a low boiling alcohol on it high boiling ethereal salt the percentage of ethereal salt which had undergone exchange of radicle was calculated directly from the amount of ethereal salt found in the low boiling fractions. In the converse case, it was impossible to determine the amount of high boiling ethereal salt formed by saponifying the higher boiling fractions much sub-stance being unavoidably lost from liquid left in the flask after each distillation.I n these cases accordingly the percentage of ethereal salt acted on had to be calculated from the difference between the weight of ethereal salt used and the weight of the same found in the low boiling fractions. I n every instance a blank experiment in which no sodic alkylate was used was performed as far as possible under the same conditions as in the actual experiment. As the first two experiments may be regarded as typical of the others some details of working are given which are omitted in succeeding experiments. I t may be added that in mofit cases as iu our second experiment the weight of the low boiling fraction agreed to within about 1 gram with the weight calculated on the assumption that the numerical result obtained by hydrolysis representcd th 394 PURDIE ASL) MARSHALL ACT103 OF actual amount of interchange of alkyl radicle that had occurred and that the separation of the ethereal salt's was complete.Isoamylic Acetate and Methylic Alcohol.+ Employed 50 grams of isoamylic acetate; methylic alcohol 12.3 grams ; sodium 0.088 gram. Percentage of isoamylic acetate con-verted (1) 31.7; (2) 30.7; mean 31.2. Blank experiment 2*:3. These results were obtained by hydrolysis of the fractions boiling under 70" in experiments (1) and (2) and under 70" and 70-80" in the blank experiment after three distillations. The weights of the several fractions were as follows :-Experiment (2). Blank experiment. Under 703 .14.2 9.0 70- 80 . 0.6 2.0 80-100 . 0.5 0.8 100-120 . 1.0 0.5 Over 120 . 40.5 45.7 I n experiment (2) the total weight of the two lowest boiling frac-tions is about 2.5 grams less than it should be on the assumption that, 30.7 per cent. of the amylic acetate had been coiiverted into met,hylic acetate and it is probable therefore that the actual amount of inter-change that occurred was several per cent. higher than that found, the error being due to imperfect separation of the methylic acetate from the higher boiling fractions and to loss by evaporation. It was found that in distilling 50 grams of methylic acetate an average of 0.3 gram of substance was lost during each distillation. Methylic Acetate nnd Isoani ylic Alcohol. Employed methylic acetate 50 grams ; isoamylic alcohol 59.4 grams ; sodium 0.155 gram.Percentage of methylic acetate converted (I) 52.2 ; (2) 51.2 ; mean 51.7. The fractions saponified were those boiling under 70" and 70-80" a,fter three distillations weighing in (2) 32.5 and 2.5 grams respec-tively. Supposing in this experiment 51.2 per cent. of the methylic acetate to have been converted into amylic acetat,e the mixture of residual methylic acetate with the methylic alcohol formed should weigh 35.5 grams which agrees fairly well with the weight actually found namely 35 grams. The corresponding fractions in the blank experiment weighed 48.2 and 0.8 gram. Blank experiment 6.8. * The amjl compounds used are from ordinary fermentation amplic alcohol ALCOHOLS ON ETHEREAL SALTS. 395 Isoamylic Acetate and E t h y l i c Alcohol.Employed isoamylic acetate 50 grams ; ethylic alcohol 17.7 grams; Percentage of isoamylic acetate converted 25.6. These numbers were obtained by sodium 0.088 gram. Blank experiment 4.1 per cent. hydrolysis of the fractions boiling under 80" after six distillations. Etlzylic Acetate and Isoaw ylic Alcohol. Employed ethylic acetate 50 grams ; isoamylic alcohol 50 grams ; sodium 0.13 gram. Percentage of ethylic acetate converted (1) 62.0 ; (2) 61.4 ; mean 61.7. Blank experiment 8.8. These numbers were obtained by hydrolysis of the fractions boiling in (1) and (2) under 80" after five distillations and in the blank experiment under 85" and 85-90' after six distillations. Isobutylic Acetate and MethyEic Alcohol. Employed isobutylic acetate 50 grams; methylic alcohol 13.8 grams; sodium 0.099 gram.Percentage of isobutylic acetate converted, 42.1. Blank experiment 8.8. The fractions saponified were those boiling xnder 70" and 70-80" after the distillations had been repeated four times. Methylic Acetate and Isobutylic Alcohol. Employed methylic acetate 50 grams ; isobutylic alcohol 50 grams ; sodium 0.155 gram. Percentage of methylic acetate converted (1) 45.6; (2) 44.6; mean 45.1. Blank experiment, 6.2. The same fractions as in the last experiment were saponified. Isobwtylic Acetate and E t h y l i c Alcohol. Employed isobutylic acetate 50 grams ; ethylic alcohol 19.8 grams ; sodium 0.099 gram. Percentage of isobutylic acetate Converted 29.3 ; in blank experiment 9.1. The fractions that were saponified were those boiling under $OD 80-85" and 85-90' after six distillations.The separation of the ethereal salt was probably less complete than in the previous experiments. Ethylic Acetate and Isobutylic Alcohol. Employed ethylic acetate 50 grams ; isobutylic alcohol 42 grams ; sodium 0.13 gram. Percentage of ethylic acetate converted 59.4 ; in the blank experiment 16.1. The mixtures were distilled six times, and the fractions saponified were those boiling under 85" and 85-90' 396 PURDIE ASI) MARSHALTJ ACTION OF The separation of the residual ethylic acetate was not very satisfactory, and the numbers found are probably several per cent. too high. Experiments similar to those described were undertaken in order to determine the amount of interaction between amylic acetate and propylic alcohol and between propylic acetate and amylic alcohol, but from consideration of the weights of the lower boiling fractions and the results obtained by their hydrolysis it was evident in these cases that tbe separation of the ethereal salts was very imperfect.With amylic acetate and propylic alcohol the percentage numbers obtained were as follows .-Experiment with sodic alkylate 20.9 ; blank experiment 4.3 ; and with propylic acetate and amylic alcohol -experiment with sodic alkylate 37 ; blank experiment 32.3. An experiment was also performed with methylic acetate tertiary butylic alcohol and sodic butyl oxide. The formation of butylic acetate could not be detected. The form in which the sodic alkylate is added does not seem to have much influence on the extent of the reaction.Thus the amount of interchange of radicle occurring between methylic acetate and amylic alcohol is much the same whether the sodium be added in the form of amyl oxide or methoxide. Interchange of radicle between alcohol and ethereal salt is induced also by the addition of zinc chloride thoEgh this substance is by no means so active as sodic alky late. I n all the reactions we have examined except that of propylic acetate and isoamylic alcohol the result of which is not to be relied on the influence of the sodic alkylate in inducing the interchange of alkyl radicle between the ethereal salt and the alcohol is very marked. It appears further that the extent of the interchange which occurs is not determined solely by the proportions in which ethereal salt and alcohol are present but is influenced by the specific affinities of the alkyi radicles concerned.This is apparent from inspection of the following table in which the experiments are arranged in pairs so that the result of each experiment may be compared with that of its converse. I n column A are given the percentages of interchange occurring when sodic alkylate is used; in column B the numbers obtained by subtracting from these the percentages found in the corresponding blank experiments. The numbers in column B repre-sent probably more accurately at all events in some cases the rela-tive amounts of interchange of alkyl radicle that take place as by subtraction of the apparent amount of interchange occurring in tlie blank experiment a rough correction is applied for errors due t o loss by evaporation imperfect separation &c ALCOHOLS OX ETHEREAL SALTS.397 Isoamylic acetate and methylic alcohol . . Methylic acetate and isoamylic alcohol . . . Isoamylic acetate and ethylic alcohol . . . . Ethylic acetate and isoamylic alcohol . . . . Isobutylic acetate and methylic alcohol . . Methylic acetate and isobutylic alcohol. . . Isobutylic acetate and ethylic alcohol . . . . Ethylic acetate and isobutylic alcohol . . . . { { A. 31 '3 5 7 25.6 61.7 42.1 45.1 29.3 59.4 B. 28.9 44.9 21.5 59.9 33.3 38.9 20.2 43.3 It is evident that a much greater interchange of alkyl radicle occurs when the alcohol of coniplex radicle acts on the ethereal salt of simple radicle than in the converse case except in the isobutyl-methyl reactions in which the extent of the interchange is about the same and this holds true whether the numbers in column A or I3 are considered.Experiments involving the separation of the ingredients of a com-plex mixture of liquids by fractional distillatiou are not capable of exact quantitative interpretation and we are aware that the differ-ences of extent of reaction shown by our numerical results may in some cases be accounted for by experimental error. We think never-theless we are justified in drawing the conclusion that excluding the methyl radicle the affinity of the alkyl radicle for the hydroxyl oxygen of the acid as measured by the special reaction under con-sideration increases with increasing complexity of the alkyl radicle, bnt that with regard to the methyl radicle its affinity is greater than that of the ethyl and less than that of the amjl radicle.The grounds of this conclusion will be made more evident by arranging the numerical results already given so as to show in juxtaposition the amounts of interchange which takes place when (1st) an alcohol acts on two different acetates and (2nd) two different alcohols act on one and the same acetate. 1st Isoamylic acetate and metbylic alcohol . . . { Isobut,ylic acetate and methylic alcohol . . Isoamylic acetate and ethylic alcohol . . . . Isobutylic acetate and ethylic alcohol . . . . Ethylic acetate and isobutylic alcohol . . . . Methylic acetate and isobutylic alcohol .. Ethylic acetate and isoamylic alcohol . . . . Methylic acetate and isoamylic alcohol . . A. 31.2 42.1 25-43 29.5 59.4 45.1 61-7 51-7 B. 28.- 9 33.3 21.5 20.2 43.3 38.9 52.9 44.9 2nd Isoamylic alcohol and methylic acetate . . 51.7 44.9 33.9 { Isobutylic alcohol and methylic acetate . . . 45. 398 COULDRIDGE SOME INTERAUTIOXS OF A. B. 2nd Isoamylic alcohol and ethylic acetate . . . . . 61.7 52.9 43.3 Ethylic alcohol and isobutylic acetate . . . . 20.2 Methylic alcohol and isobutylic acetate. . . 42.1 33.3 Ethylic alcoliol and isoamylic acetate . . . . 21-5 28.9 { Isobutylic alcohol and ethylic acetate . . . . 59.4 29.3 25.6 { Methylic alcohol and isoamylic acetate . . . 31.2 { The only numbers which do not accord with the conclusion stated above are those given in column B for the action of ethylic alcohol on isoamylic and isobutylic acetates. The reaction under consideration is a complex one and its course is no doubt influenced by the relative stability of the different sodic alkylates the etherificatiori values of the alcohols and other factors. Menschutkin has shown that rnethylic alcohol holds a distinctive position among its homobgues in respect of power of etherification. A similar though not identical peculiarity is also emphasised in the reaction we have studied. The power possessed by alcohols to effect interchange of alkyl radicle in presence of sodic alkylate would seem to be associated however with the limits and not with the initial velocity of etherification as in correspondence with the former, excluding methylic alcohol this power increases with increasing molecular weight of the alcohol. It may be added that our con-clusions accord with the observations of Rose and of Peters already alluded to

ISSN:0368-1645    

DOI:10.1039/CT8885300391

出版商:RSC    

年代:1888

数据来源: RSC

摘要:

398 COULDRIDGE SOME INTERAUTIOXS OF XXX.- Some Interactions of Nitrogen Chlorophosphide. By WARD CODLDRIDGE B.A. CHLOROPHOSPHIDE of nitrogen was carefully and at length examined by Gladstone a t the request of its discoverer Liebig ; and about the same time Gerhardt examined the interaction in which it is formed. Since that date the only work which has been done with it excepting Wichelhaus' confirmatory determination of its high vapour-density is that of Hofmann who stxidied the interaction of aniline and chloro-phosphide of nitrogen. My object in resuming the investigation of chlorophosphide of nitrogen was i f possible to elucidate its forma-tion and to examine in more detail its reaction with amines. As my work proceeded other issues suggested themselves. I endeavoured to displace the chlorine-atomg by cyanogen-groups ; and as the effort NITROGEN CHLOROPHOSPHIDE.399 which had been made to remove by the action of sodium and potassium. the chlorine and to isolate the radicle of phosphorus and nitrogen had not given very definite results I tried the action of zinc ethide expecting by this means to displace the chlorine by ethyl, and thus to form compounds of which the reduction products would have been interesting. But to work with this substance one has to meet the difficulty of its preparation and as Gladstone found the yield is but small. My method of preparation was a slight modification of that given by Gladstone (Jour. Chem. Xoc. 3 135). Instead of attaching receivers directly to the flask in which the ammonium chloride and the phosphorus pentachloride are heated by a Bunsen burner a straight condenser was first fixed to the flask in order to return to the sphere of action any unaltered vaporised pentachloride and to condense the chlorophosphide of nitrogen which would otherwise have been carried over by the evolved hydrogen chloride and would, in part have been lost.The chlorophosphide of nitrogen was purified by driving over with steam. The objection to this method of purifica-tion is that the steam decomposes some of the product; but i n its favour is the fact that it is less trouble than t o extract with anhydyous ether. The yield was somewhat variable; but in no case was it large. The maximum yields I obtained amounted to 10 grams of chlorophosphide of nitrogen from 100 grams of phosphorus penta-chloride and 200 grams of ammonium chloride; whereas the theoretical yield calculated from the equation-3PC1 + 3NH3 = P,N,Cltj + 9HC1, would be 41 grams.Gladstone states that his yield was uniformly about 6 per cent. of the pentachloride used. The smallness of the yield is most probably explained by the following experiments. I found that when dry ammonia gas is passed through a dry tube over melted chlorophospliide of nitrogen a reac-tion takes place which results in the transformation of the greater part of the latter substance into a greyish-white infusible powder, and in the volatilisation of the smaller portion on to the cooler part of the tube where it remains unaltered; this same greyish-white infusible substance is also obtained when chlorophosphide of nitrogen and ammonium chloride are heated in a sealed tube at a temperature of 150" for an hour or more; at the end of which time mere traces only of chlorophosphide of nitrogen remain.The fol-lowing equation represents the reaction :-P,N,CI,j + 3NH3 = P,N?(NH)3 + 6HC1. P hospharn 400 COULDRIDGE SOME ISTERXCTIOSS O F The greyish-white infusible substance is readily characterised as phospham. This easy transformat ion of chlorophosphide of nitrogen into phospham renders the view distinct that the molecule of phospham is not PN(NH) but is P3N3(NH), just as chlorophosphide of nitrogen is not PNC1 but is P,N,CI,. The production in the first instance of chlorophosphide of nitrogen receives a simple explanation in terrns of the following equation :-C1 H Cl H 3C1,PCl + 3HN = P,N,Cl + 9HC1.Gerhardt (Ann. Clzim. Phys. 18,205) who investigated the action of phosphorus pentachloride on ammonium chloride concluded that the fortnrttion of phosphorus nitrogen chloride,* occurring as it does in small quantities was accidental. But the above-mentioned action of ammonia would lead to another conclusion. And indeed not only does ammonia react with phosphorus nitrogen chloride but also amines generally appear to remove the chlorine. Hofmann (Bey. 17, 1909) found that by dissolving phosphorus nitrogen chloride in aniline, and warming the solution on a water-bath the whole solidified ; and from the solid mass by extracting the aniline hydrochloride and the unaltered aniline by hydrochloric acid and water he obtained a white, solid substance which after crystallisation from glacial acetic acid, gave on analysis numbers corresponding to the constitution I repeated this experiment using somewhat larger quantities of substances.There was formed the white substance which Hofmann described and together with it a viscid dark-coloured oil which was separated by digestion with cold alcohol after treating the solid mass with hydrochloric acid and water. This oily substance is extremely soluble in alcohol ether and benzene and appears to be unaltered by boiling with a large quantity of water for 10 hours. All attempts to crjstallise it were futile ; and after standing for two months it shows no signs of crystallisation. This resinous matter was formed in every case from the action of phosphorus nitrogen chloride on the amines which I used.Hofmann considered that if this compound P,N,( NH.C,H,), were heated with hydrochloric acid it might lose 3 mols. of aniline and be converted into the corresponding phospham-derivative P3N3( NCsH,),. But 1 found that when heated in a sealed tube with strong hydro-chloric acid it remained unaltered a t a temperature of 150" and f Tbis name seemR preferable to " chlorophosphide of nitrogen. NITROGEN CHLOROPHOSPHIDE. 401 when the temperature was I-aised to 250" it was completely deconi-posed into phosphoric acid ammonium chloride and aniline. Thus-P3N,(NH*C,H,) + 12H20 + 9HC1 = 3NHAC1 + 6C6H5*NH2,HCl + 3H3POa. I next used instead of aniline orthotoluidine. On mixing together tlie phosphorus nitrogen chloride and the orthotoluidine the mixture gets warm; and on heating on the water-bath it finally solidifies.Instead of a t first treating the solid mass with hydrochloric acid I used ether to remove the excess of orthotoluidine fearing lest the hydrochloric acid might be the cause of the production of the resinous substance. After filtering off the ethereal extract a white solid re-mained but its ready solubility in water proved it to be orthotoluidine hydrochloride. Theethereal extract gave a residue after thr removal of the free orthotoluidine of a viscid oil similar to that obtained when aniline was used. Thus a t loo" no product of the type P,N,R was formed. But when the orthotoluidine and the phosphorus nitrogen chloride were heated a t temperatures of 150" or 250' such a substance was produced together with the resin; so that on extracting the solid mass with ether and with hydrochloric acid and water a white substance remained which could be crgstallised in slender needles from hot alcohol.I t s melting point is 241-242'. The formula P3N3(NH*C6H,.CH3)6 requires 12.17 per cent. of nitrogen ; 1 found 12.16. When phenylhydrazine was mod there was at a temperature of loo" formed in addition to the viscid oil a crystallisable substance which I extracted as in the previous instance. It was crysrallised from alcohol. Its melting point was 200". The constitution, P,N3(NH*NH.C,H,)6 requires 11.97 per cent. of phosphoiws and 27.03 per cent. of nitrogen ; my analysis gave 12-15 per cent.of phos-phorus and of nitrogen 27.27. The reaction with piperidine and phosphorus nitrogen chloride is very rapid. So much heat is evolved that the piperidine begins to boil. The reaction is completed by warming on a water-bath. The products are here again a viscid oil in much smaller quantity than in the other instances and a crystallisable componnd. The latter can with difficiilty be crystallised from alcohol. On heating it decom-posed before me1 ting. The formula P3N,(NC5H,,) would require-Pound. 14.3 Phosphorus . . . . . . . 14-08 per cent. Nitrogen. . . . . . . . . . 19.89 , 19.8 Diphenylamine and diamylamine do not at ordinary temperatures react with phosphorus nitrogen chloride 402 STUART AC'I'IOX OF Attempts were made t o prepare cyanogen-derivatives of phosphorus nitrogen chloride by dissolving it in alcohol and heating the solution with silver cyanide a t a 100" for several hours.But the phosphorus nitrogen chloride was entirely decomposed and prussic acid was set free. On evaporating the alcohol a thick oil with a strongly acid reaction was obtained. It readily gave off ammonia when warmed with baryta-water and otherwise reacted as a mixture of acid am-monium salts. It showed Gladstone's test for azophosphoric acid ; for on adding a drop of ferric chloride to the ammoniacal solution of the acid the liquid became brown and no trace of precipitate was formed. But on applying this test to a solution of ammonium phos-phate I obta.ined exactly the same result. Previous efforts which had been made to remove the chlorine and t o isolate the radicle had not yielded very definite results. I found that sodium or sodium amalgam acts very slowly on a benzene solu-tion of phosphoric nitrogen chloride ; so I mixed it with dry zinc-dust exhausted the tube and heated the mixture. Much gas was evolved smelling of cyanogen. The phosphorus nitrogen chloride was entirely decomposed and the phosphorus remained behind in combination with the zinc. I next tried the action of zinc ethide on the phosphorus nitrogen chloride ; but at ordinary temperatures the substances do not react. The University Laboratory, Ca 112 bridge

ISSN:0368-1645    

DOI:10.1039/CT8885300398

出版商:RSC    

年代:1888

数据来源: RSC